Reaction control by regulating internal condensation inside a reactor

Methods and apparatuses for controlling exothermic reactions involving a first reactant contained in a liquid and a second reactant in a gas to form a reaction product by atomizing the liquid in an environment of a gas and removing heat of reaction by condensing vapors of the liquid in a reaction chamber. Preferably, the condensation takes place on a simultaneously atomized second liquid of lower temperature than the atomized liquid containing the first reactant. The compositions of the two liquids are preferably similar. This invention provides waste minimization and considerable environmental improvement.

FIELD OF THE INVENTION 
This invention relates to methods and devices for making reaction products, 
wherein a first reactant incorporated in an atomized liquid reacts with a 
gas containing a second reactant, under controlled condensation and 
temperature conditions. It provides waste minimization and considerable 
environmental improvement. 
BACKGROUND OF THE INVENTION 
Reactions where a first reactant, dissolved in a liquid, reacts with a 
second reactant contained in a gas under increased surface area conditions 
are known to the art. Such reactions are carried out in devices as 
scrubbers, burners, reaction vessels, and the like, for example. 
Atomization of liquids into a gaseous atmosphere is one of the above 
mentioned techniques described in the art. The atomization techniques for 
conducting reactions, disclosed in the art so far, are rather crude and 
lack innovative features for controlling such reactions with respect to: 
desired reaction product if the reaction product is an intermediate, yield 
in reaction product, conversion and conversion rate, temperature profiles 
in the reaction zone, average droplet size or diameter, evaporation rates, 
and the like. Actually in most, if not all, cases, the reaction product is 
substantially the final product expected under the crude overall 
conditions of the reaction. For example, in the case of a burner, where a 
fuel is atomized into an atmosphere of an oxygen-containing gas (such as 
air for example), the final product of reaction is carbon dioxide, with 
desired minimization of carbon monoxide and nitrogen oxides as much as 
possible. In another example, a scrubber for removing acidic compounds 
from a gas may use an atomized liquid containing alkali or alkaline earth 
compounds which react with the acidic compounds in the gas to form the 
corresponding salts. In still another example, ammonia and phosphoric acid 
react under atomization conditions to form ammonium orthophosphate, which 
is a final reaction product. 
On the other hand, reactions which are geared to produce intermediate 
products, especially in the case of oxidations, are not run under 
atomization conditions, since atomization promotes complete reactions to a 
final product. For example, oxidation of cyclohexane to adipic acid, or 
oxidation of p-xylene to terephthalic acid, have not been reported to be 
conducted under atomization conditions, and there is no incentive in the 
art to do so, since burning of cyclohexane to carbon dioxide has been 
expected to take place under such conditions. However, the inventors have 
discovered that in the presence of unexpected intricate critical controls 
and requirements of the instant invention, intermediate reaction or 
oxidation products, such as adipic acid, phthalic acid, isophthalic acid 
and terephthalic acid, for example, may be advantageously obtained under 
atomization conditions. 
The following references, among others, describe processes conducted in 
intermixing liquid with gaseous materials, mostly under increased surface 
area conditions. 
U.S. Pat. No. 5,399,750 (Brun et al.) discloses methods for preparing 
maleamic acid (aminomaleic acid) by reacting gaseous ammonia with molten 
maleic anhydride under reactant contact conditions of high surface area, 
for example reacting said gaseous NH.sub.3 with a thin film of said molten 
maleic anhydride or with said molten maleic anhydride in a state of 
vigorous agitation. 
U.S. Pat. No. 5,396,850 (Connote et al.) discloses a method of destroying 
organic waste in a bath of molten metal and slag contained in a vessel. 
The method comprises injecting organic waste into the bath to form a 
primary reaction zone in which the organic waste is thermally cracked and 
the products of the thermal cracking which are not absorbed into the bath 
are released into the space above the surface of the bath. The method 
further comprises injecting an oxygen-containing gas toward the surface of 
the bath to form a secondary reaction zone in the space above the surface 
of the bath in which the oxidizable materials in the products from the 
primary reaction zone are completely oxidized and the heat released by 
such oxidation is transferred to the bath. In order to facilitate 
efficient heat transfer from the second reaction zone to the bath, the 
method further comprises injecting an inert or other suitable gas into the 
bath to cause molten metal and slag to be ejected upwardly from the bath 
into the secondary reaction zone. 
U.S. Pat. No. 5,312,567 (Kozma et al.) discloses a complex mixing system 
with stages consisting of propeller mixers of high diameter ratio, where 
the blades are provided with flow modifying elements, whereby the energy 
proportions spent on dispersion of the amount of gas injected into the 
reactor, homogenization of the multi-phase mixtures, suspension of solid 
particles, etc. and the properties corresponding to the rheological 
properties of the gas-liquid mixtures and to the special requirements of 
the processes can be ensured even in extreme cases. Open channels opposite 
to the direction of rotation are on the blades of the dispersing stage of 
the propeller mixers fixed to a common shaft, where the channels are 
interconnected with gas inlet. The angle of incidence of a certain part of 
the blades of mixing stages used for homogenization and suspension is of 
opposite direction and the length is shorter and/or the angle of incidence 
is smaller than those of the other blades. Baffle bars are on the trailing 
end of the blades on a certain part of the propeller mixers used similarly 
for homogenization and suspension, and/or auxiliary blades at an angle of 
max. 20.degree. to the blade wings are arranged above or below the 
trailing end of the blades. 
U.S. Pat. No. 5,244,603 (Davis) discloses a gas-liquid mixing system which 
employs an impeller/draft tube assembly submerged in liquid. Hollow 
eductor tubes affixed to the impeller drive shaft are used to flow gas 
from an overhead gas space to the liquid in the vicinity of the assembly. 
The positioning and size of the eductor tubes are such as to maximize the 
desired gas-liquid mixing and reaction rate. 
U.S. Pat. No. 5,270,019 (Melton et al.) discloses an elongated, generally 
vertically extending concurrent reactor vessel for the production of 
hypochlorous acid by the mixing and reaction of a liquid alkali metal 
hydroxide and a gaseous halogen, wherein an atomizer is mounted near the 
top of the reactor vessel to atomize the liquid alkali metal hydroxide 
into droplets in the vessel. The vessel has a spraying and reaction zone 
immediately beneath the atomizer and a drying zone beneath the spraying 
and reaction zone to produce a gaseous hypochlorous acid and a 
substantially dry solid salt by-product. 
U.S. Pat. No. 5,170,727 (Nielsen) discloses a process and apparatus in 
which supercritical fluids are used as viscosity reduction diluents for 
liquid fuels or waste materials which are then spray atomized into a 
combustion chamber. The addition of supercritical fluid to the liquid fuel 
and/or waste material allows viscous petroleum fractions and other liquids 
such as viscous waste materials that are too viscous to be atomized (or to 
be atomized well) to now be atomized by this invention by achieving 
viscosity reduction and allowing the fuel to produce a combustible spray 
and improved combustion efficiency. Moreover, the present invention also 
allows liquid fuels that have suitable viscosities to be better utilized 
as a fuel by achieving further viscosity reduction that improves 
atomization still further by reducing droplet size which enhances 
evaporation of the fuel from the droplets. 
U.S. Pat. No. 5,123,936 (Stone et al.) discloses a process and apparatus 
for removing fine particulate matter and vapors from a process exhaust air 
stream, and particularly those emitted during post-production curing or 
post-treatment of foamed plastics, such as polyurethane foam, in which the 
exhaust air stream is passed through a transfer duct into which is 
introduced a water spray in the form of a mist of fine droplets in an 
amount which exceeds the saturation point; thereafter the exhaust air 
stream is introduced into a filter chamber having a cross-sectional area 
that is substantially greater than that of the transfer duct, and the 
exhaust air stream passes through at least one, and preferably a plurality 
of high surface area filters, whereby a portion of the water is removed 
from the exhaust air stream and collected in the filter chamber prior to 
the discharge of the exhaust air stream into the environment. 
U.S. Pat. No. 5,061,453 (Krippl et al.) discloses an apparatus for 
continuously charging a liquid reactant with a gas. The gas is dispersed 
in the reactant through a hollow stirrer in a gassing tank. The quantity 
of gas introduced per unit time is kept constant. 
U.S. Pat. No. 4,423,018 (Lester, Jr. et al.) discloses a process according 
to which a by-product stream from the production of adipic acid from 
cyclohexane, containing glutaric acid, succinic acid and adipic acid, is 
employed as a buffer in lime or limestone flue gas scrubbing for the 
removal of sulfur dioxide from combustion gases. 
U.S. Pat. No. 4,370,304 (Hendriks et al.) discloses methods by which 
ammonium orthophosphate products are prepared by reacting ammonia and 
phosphoric acid together at high speed under vigorous mixing conditions by 
spraying the reactants through a two-phase, dual coaxial mixer/sprayer and 
separately controlling the supply and axial outflow rate of the phosphoric 
acid at 1 to 10 m/sec. and the outflow rate of ammonia at 200 to 1000 
m/sec. (N.T.P.). Thorough mixing and a homogenous product is obtained by 
directing the outflow spray into a coaxial cylindrical reaction chamber of 
a specified size with respect to the diameter of the outermost duct of the 
sprayer/mixer. The product may be granulated on a moving bed of granules 
and adjusted in respect of the NH.sub.3 to H.sub.3 PO.sub.4 content by 
changing the concentration of the phosphoric acid and/or supplying 
additional ammonia to the granulation bed. 
U.S. Pat. No. 4,361,965 (Goumondy et al.) discloses a device for atomizing 
a reaction mixture, said device enabling the reaction mixture to be 
atomized in a reactor with the aid of at least a first gas and an 
atomizing nozzle. This device further comprises a supply of a second hot 
gas at the top of the atomizing device, serving to dry the atomized 
mixture, a supply of a third gas and means for distributing this third gas 
comprising an annular space of adjustable width and adapted to distribute 
in the reactor said third gas in the form of a ring along the inner wall 
of the reactor, so as to avoid any contact between the reaction mixture 
and said wall. The invention is applicable to the atomization of a 
reaction mixture. 
U.S. Pat. No. 4,308,037 (Meissner et al.) discloses methods according to 
which high temperature thermal exchange between molten liquid and a gas 
stream is effected by generating in a confined flow passageway a plurality 
of droplets of molten liquid and by passing a stream through the 
passageway in heat exchange relationship with the droplets. The droplets 
are recovered and adjusted to a predetermined temperature by means of 
thermal exchange with an external source for recycle. The process provides 
for removal of undesired solid, liquid or gaseous components. 
U.S. Pat. No. 4,065,527 (Graber) discloses an apparatus and a method for 
handling a gas and a liquid in a manner to cause a specific interaction 
between them. The gas is placed into circulation to cause it to make a 
liquid circulate in a vortex fashion to present a liquid curtain. The gas 
is then passed through the liquid curtain by angled vanes to cause the 
interaction between the two fluids, such as the heating of the liquid, 
scrubbing of the gas, adding a chemical to the liquid and the like. The 
vanes are spaced apart and project inwardly from the inner periphery of an 
annular support so that the circulating liquid readily moves into the 
spaces between the vanes to create the liquid curtain. A number of 
embodiments of the invention are disclosed. 
U.S. Pat. No. 4,039,304 (Bechthold et al.) discloses methods according to 
which waste gas is contacted with a solution of a salt from a pollutant of 
the gas. This solution is obtained from another stage of the process used 
for cleaning or purifying the gas. The resulting mixture of gas and 
solution is subjected to vaporization so as to obtain a dry gaseous 
substance constituted by the waste gas and the evaporated solvent for the 
salt. The gaseous substance thus formed contains crystals of the salt as 
well as the pollutant present in the original waste gas. The salt crystals 
and other solid particles are removed from the gaseous substance in the 
form of a dry solids mixture. The gaseous substance is subsequently mixed 
with an absorption fluid such as an ammonia solution in order to wash out 
and redissolve any salt crystals which may remain in the gaseous substance 
and in order to remove the pollutant present in the original waste gas 
from the gaseous substance. The pollutant and the redissolved salt 
crystals form a salt solution together with the absorption fluid and it is 
this salt solution which is brought into contact with the waste gas. The 
gaseous substance is exhausted to the atmosphere after being mixed with 
the absorption fluid. 
U.S. Pat. No. 3,928,005 (Laslo) discloses a method and apparatus for 
treating gaseous pollutants such as sulfur dioxide in a gas stream which 
includes a wet scrubber wherein a compressed gas is used to atomize the 
scrubbing liquid and a nozzle and the compressed gas direct the atomized 
liquid countercurrent to the flow of gas to be cleaned. The method and 
apparatus includes pneumatically conveying to the nozzle a material such 
as a solid particulate material which reacts with or modifies the 
pollutant to be removed or altered. The gas used for atomizing the 
scrubbing liquid is also used as a transport vehicle for the solid 
particulate material. In the case of sulfur oxides, the material may be 
pulverized limestone. 
U.S. Pat. No. 3,677,696 (Helsinki et al) discloses a method according to 
which, the concentration of circulating sulfuric acid is adjusted to 
80-98% by weight and used to wash hot gases containing mercury. The 
temperature of the acid is maintained between 70.degree.-250.degree. C., 
and the solid material separating from the circulating wash solution is 
recovered. 
U.S. Pat. No. 3,613,333 (Gardenier) discloses a process and apparatus for 
removing contaminants from and pumping a gas stream comprising indirectly 
heat exchanging the gas and a liquid, introducing the liquid under 
conditions of elevated temperature and pressure in vaporized and atomized 
form into the gas, mixing same thereby entrapping the contaminants, and 
separating clean gas from the atomized liquid containing the contaminants. 
U.S. Pat. No. 2,980,523 (Dille et al.) discloses a process for the 
production of carbon monoxide and hydrogen from carbonaceous fuels by 
reaction with oxygen. In one of its more specific aspects it is directed 
to a method of separating carbonaceous solid entrained in the gaseous 
products of reaction of carbonaceous fuels and oxygen wherein said 
products are contacted with a limited amount of liquid hydrocarbon and 
thereafter scrubbed with water, and said carbonaceous solid is decanted 
from said clarified water. 
U.S. Pat. No. 2,301,240 (Baumann et al.) discloses an improved process for 
removing impurities from acetylene gas which has been prepared by thermal 
or electrical methods by washing with organic liquids, as for example oils 
or tars. 
U.S. Pat. No. 2,014,044 (Haswell) discloses an improved method for treating 
gas and aims to provide for the conservation of the sensible heat of such 
gas. 
U.S. Pat. No. 1,121,532 (Newberry) discloses a process of recovering 
alkalis from flue-gases. 
Currently, oxidation reactions for the production of organic acids, 
including but not limited to adipic acid, are conducted in a liquid phase 
reactor with reactant gas sparging. The reactant gas in these cases is 
typically air, but may also be oxygen. Sufficient reactant gas, with or 
without non-reactive diluents (e.g., nitrogen), is sparged--at relatively 
high rate--so that the liquid reaction medium is aerated to maximum 
capacity (typically 15-25% aeration). The relatively high sparging rates 
of reactant containing gas feed (hereinafter referred to as "reactant 
gas"), associated with this conventional approach, have several drawbacks: 
Costly reactant gas feed compressors are required to compress makeup 
reactant gas for sparging. These are expensive to install and operate 
(high electric or steam consumption), and have many utility problems 
resulting in excessive plant downtime. 
The required high gas rate makes it extremely difficult to control oxygen 
content in the reactor at low concentrations (due to the high reactor gas 
turnover rate). 
The required high gas rate makes it extremely difficult to control reaction 
temperature at low production rates (i.e., high turndown rate) for a given 
sized reactor system. This occurs because the gas used for sparging 
removes energy from the reaction system by volatilizing reaction liquid 
and liquid solvent--this volatilization effect is quite significant at the 
relatively high temperatures commonly associated with and required for 
oxidation reactions. Unless carefully balanced by an exothermic heat of 
reaction, this volatilization will act to substantially lower the 
temperature of the liquid content of the reactor. Thus, a properly sparged 
system can be designed for good temperature control at medium to high 
production rates, but will suffer temperature loss and loss of temperature 
control at significant turndown rate. 
High reactant gas feed rate results in relatively high reactor 
non-condensible off-gas rate. Non-condensible off-gases must either be 
totally purged to atmosphere, or--if oxygen content is high-partially 
purged and partially recycled to the reactor. The use of air as a reactant 
gas feed has drawbacks because it results in high rate of purge to the 
atmosphere--this is undesirable because this purge must first be cleaned 
in very expensive off-gas cleanup facilities in order to meet ever more 
stringent environmental requirements. The use of oxygen-only gas feed to 
the reactor may be undesirable because high sparging requirements result 
in low oxygen conversion in the reactor; low conversion results in high 
oxygen concentration within the reactor; and high oxygen concentration 
within the reactor may result in excessive over-oxidation of liquid 
reactants and liquid solvents with attendant high chemical yield loss 
(i.e., burning these to carbon monoxide and carbon dioxide). If the oxygen 
in the reactor is diluted with recycle nitrogen or gaseous-recycle inerts, 
then both high recompression investment and costs, and recompression 
utility problems are introduced. 
The current technology also suffers from a relatively low ratio of 
gas-liquid surface area to liquid reaction mass. The presently available 
art does not maximize this ratio. In contrast, the present invention 
maximizes said ratio in order: 
to increase reaction rate by increasing the mass transfer rate of gaseous 
reactants to liquid reaction sites; and 
so as to enable economic operation at relatively low concentration of a 
second reactant, such as an oxidant for example, in the gas phase. 
Operating at lower oxygen concentration with acceptable conversion rates in 
the reactor improves yield by reducing over-oxidations, and eliminates 
safety (explosion) problems associated with operation in the explosive 
oxygen/fuel envelope. In the current technology, reducing oxygen content 
below traditional levels would result in a non-economic reduction in 
reaction rate. However, a significant increase in the aforementioned 
ratio--relative to current levels--would offset this rate reduction 
thereby enabling economic operation at reduced oxygen concentration in the 
reactor. 
Another problem with the current technology is the sometimes formation of 
large agglomerations of insoluble oxidation products in the reactor. These 
can build up on reactor walls resulting in decreased available reaction 
volume, and in unwanted by-product formation due to over-exposure of said 
accretions to reaction conditions (e.g., high temperature) in 
oxygen-starved micro-reactor environments. These can also form large 
diameter, heavy solids in the reactor which can result in damage to 
expensive reactor agitator shafts and agitator seals resulting in costly 
repairs and high utility wear-problems. Finally, the current technology 
often requires expensive agitation shafts and seals capable of 
withstanding corrosive chemical attack and containing high system 
pressures. 
Substituting gas-phase reaction systems for liquid-phase reactors 
introduces new problems, chief among which is the difficulty of 
identifying a cost-effective, efficient, non-plugging, long-lived catalyst 
system. Liquid-phase catalyst systems are well-developed and 
well-understood. Unfortunately, these are non-volatile. Using a 
non-volatile catalyst in a gas-phase reaction system must necessarily 
often be subject to severe plugging problems as most organic acids 
resulting from oxidation reactions are non-volatile solids--unless 
dissolved in a liquid reaction medium. 
There is a plethora of references dealing with oxidation of organic 
compounds to produce acids, such as, for example, adipic acid. 
The following references, among the plethora of others, may be considered 
as representative of oxidation processes relative to the preparation of 
diacids. 
U.S. Pat. No. 5,321,157 (Kollar) discloses a process for the preparation of 
C.sub.5 -C.sub.8 aliphatic dibasic acids through oxidation of 
corresponding saturated cycloaliphatic hydrocarbons by 
(1) reacting, at a cycloaliphatic hydrocarbon conversion level of between 
about 7% and about 30%, 
(a) at least one saturated cycloaliphatic hydrocarbon having from 5 to 8 
ring carbon atoms in the liquid phase and 
(b) an excess of oxygen gas or an oxygen containing gas mixture in the 
presence of 
(c) less than 1.5% moles of a solvent per mole of cycloaliphatic 
hydrocarbon (a), wherein said solvent comprises an organic acid containing 
only primary and/or secondary hydrogen atoms and 
(d) at least about 0.002 mole per 1000 grams of reaction mixture of a 
polyvalent heavy metal catalyst; and 
(2) isolating the C5-C8 aliphatic dibasic acid. 
U.S. Pat. No. 5,463,119 (Kollar) discloses a process for the preparation of 
C.sub.5 -C.sub.8 aliphatic dibasic acids, similar to the one described in 
U.S. Pat. No. 5,321,157, with the main difference that after removing the 
adipic acid, the remaining matter is recirculated. 
U.S. Pat. No. 5,221,800 (Park et al.) discloses a process for the 
manufacture of adipic acid, according to which cyclohexane is oxidized in 
an aliphatic monobasic acid solvent in the presence of a soluble cobalt 
salt wherein water is continuously or intermittently added to the reaction 
system after the initiation of oxidation of cyclohexane as indicated by a 
suitable means of detection, and wherein the reaction is conducted at a 
temperature of about 50.degree. C. to 150.degree. C., at an oxygen partial 
pressure of about 50 to about 420 pounds per square inch absolute. 
The following references, among others, describe oxidation processes 
conducted in multi-stage and multi-plate systems. 
U.S. Pat. No. 3,987,100 (Barnette et al.) describes a process of oxidizing 
cyclohexane to produce cyclohexanone and cyclohexanol, said process 
comprising contacting a stream of liquid cyclohexane with oxygen in each 
of at least three successive oxidation stages by introducing into each 
stage a mixture of gases comprising molecular oxygen and an inert gas. 
U.S. Pat. No. 3,957,876 (Rapoport et al.) describes a process for the 
preparation of cyclohexyl hydroperoxide substantially free of other 
peroxides by oxidation of cyclohexane containing a cyclohexane soluble 
cobalt salt in a zoned oxidation process in which an oxygen containing gas 
is fed to each zone in the oxidation section in an amount in excess of 
that which will react under the conditions of that zone. 
U.S. Pat. No. 3,530,185 (Pugi) describes a process for manufacturing 
precursors of adipic acid by oxidation of an oxygen containing inert gas 
which process is conducted in at least three successive oxidation stages 
by passing a stream of liquid cyclohexane maintained at a temperature in 
the range of 140.degree. to 200.degree. C., and a pressure in the range of 
50-350 psig through each successive oxidation stage in an amount such that 
substantially all the oxygen introduced into each stage is consumed in 
that stage thereafter causing the residual inert gases to pass 
countercurrent into the stream of liquid during the passage of the stream 
through said stages. 
None of the above references, or any other references known to the 
inventors disclose, suggest or imply, singly or in combination, devices 
for conducting reactions under atomization conditions subject to the 
intricate and critical controls and requirements of the instant invention 
as described and claimed. 
SUMMARY OF THE INVENTION 
As aforementioned, the present invention relates to methods and devices for 
making reaction products, wherein a first reactant incorporated in an 
atomized liquid reacts with a gas containing a second reactant, under 
controlled condensation and temperature conditions. More particularly, it 
pertains to a method of making a reaction product in a reaction zone in an 
exothermic reaction from a first liquid containing a first reactant and a 
gas containing a second reactant, the method comprising the steps of: 
atomizing the first liquid to form a plurality of first droplets in the gas 
at a first flow rate, at a first atomization temperature, and at a 
reaction pressure; 
reacting at least partially the first reactant with the second reactant to 
form the reaction product and release heat; 
evaporating at least part of the first liquid, thereby removing at least a 
portion of the released heat; and 
restricting the portion of removed heat within predetermined limits by 
causing controlled condensation within the reaction zone. 
The present invention also pertains to a method of making a reaction 
product in an exothermic reaction from a first liquid containing a first 
reactant and a gas containing a second reactant, the method comprising the 
steps of: 
dividing the first liquid into a first stream and to a second stream; 
causing the first stream to have a first atomization temperature and the 
second stream to have a second atomization temperature lower than the 
first atomization temperature; 
atomizing the first stream to form a plurality of first droplets in the gas 
at a first flow rate and at the first atomization temperature; 
atomizing the second stream to form a plurality of second droplets in the 
gas at a second flow rate and at the second atomization temperature; 
reacting at least partially the first reactant in the first droplets with 
the second reactant to form the reaction product and release heat; and 
maintaining first droplet temperature within predetermined limits by 
evaporation of at least part of the first liquid from the first droplets, 
and 
condensation of at least part of the evaporated first liquid on the second 
droplets. 
Further, the instant invention is related to a method of making a reaction 
product in an exothermic reaction from a first liquid containing a first 
reactant and a gas containing a second reactant, the method comprising the 
steps of: 
dividing the first liquid into a first stream and to a second stream; 
causing the first stream to have a first atomization temperature and the 
second stream to have a second atomization temperature lower than the 
first atomization temperature; 
atomizing the first stream to form a plurality of first droplets in the gas 
at a first flow rate and at the first atomization temperature; 
atomizing the second stream to form a plurality of second droplets in the 
gas at a second flow rate and at the second atomization temperature; 
reacting at least partially the first reactant in the first droplets with 
the second reactant to form the reaction product and release heat; and 
maintaining first droplet temperature within predetermined limits by 
transferring heat from the first droplets to the second droplets. 
The controlled condensation is preferably caused by a second liquid 
atomized within the reaction zone. The second liquid may contain volatiles 
at a desired content, the volatiles having a desired volatility. The 
second liquid may enter the reaction zone under a condition selected from 
a group consisting of a second flow rate, a second atomization 
temperature, and a combination thereof, the second atomization temperature 
being lower than the first atomization temperature. 
The first liquid may also contain volatiles at a desired content, the 
volatiles having a desired volatility. 
The condensation rate may be at least partially controlled by one parameter 
selected from a group consisting of (a) temperature difference between the 
first and the second atomization temperature, (b) flow rate difference 
between the first and the second flow rate (c) the volatiles content of 
the first liquid, (d) the volatiles content of the second liquid, (e) the 
volatility of the first or second volatiles, and (f) a combination 
thereof. The condensation rate may also be controlled by changing the 
reaction pressure. 
It is preferable that, if the first liquid comprises a first set of 
ingredients, and the second liquid comprises a second set of ingredients, 
the first set and the second set have at least one common ingredient. It 
is more preferable that the first set and the second set comprise 
substantially the same ingredients, and even more preferable that the 
substantially same ingredients are substantially under the same 
proportions. 
The controlled condensation may be caused by a solid or liquid surface 
within the reaction zone or by a solid or liquid surface in the periphery 
of the reaction zone, or any combination thereof. 
Provisions may be made so that condensed material is at least partially 
separated from reacted material. 
It is preferable that the total amount of second reactant fed to the 
reaction zone is in a range corresponding to stoichiometric to two times 
stoichiometric with respect to the total amount of first reactant fed to 
the reaction zone. 
The present invention also pertains to methods as aforedescribed, wherein 
the first reactant comprises a compound selected from a group consisting of 
cyclohexane, cyclohexanone, cyclohexanol, cyclohexylhydroperoxide, 
o-xylene, p-xylene, m-xylene, a mixture of at least two of cyclohexane, 
cyclohexanone, cyclohexanol, and cyclohexylhydroperoxide, and a mixture of 
at least two of o-xylene, p-xylene, and m-xylene; 
the second reactant comprises oxygen; and 
the reaction product comprises a compound selected from a group consisting 
of cyclohexanone, cyclohexanol, cyclohexylhydroperoxide, adipic acid, 
phthalic acid, isophthalic acid, terephthalic acid, a mixture of at least 
two of cyclohexanone, cyclohexanol, and 
cyclohexylhydroperoxide, and a mixture of at least two of phthalic acid, 
isophthalic acid, and terephthalic acid. 
The present invention relates also to a method, wherein the first liquid 
contains a catalyst at a desired concentration, the first and second 
reactants are characterized by desired concentrations, the exothermic 
reaction is characterized by a conversion of the first reactant to 
reaction product, the exothermic reaction takes place in a reaction zone, 
the first droplets have a path within said reaction zone, said first 
droplets have a temperature as function of their path through the reaction 
zone, wherein said conversion is controlled by a parameter selected from a 
group consisting of: 
changing the first atomization temperature; 
changing the second atomization temperature; 
changing the catalyst concentration; 
changing the first reactant concentration in the first liquid; 
changing the volatiles content in the first liquid; 
changing the volatiles content in the second liquid; 
changing the second reactant concentration; 
changing the droplet size of the first liquid; and 
a combination thereof; and 
wherein said first droplet temperature is controlled by a parameter 
selected from a group consisting of: 
changing the first atomization temperature; 
changing the second atomization temperature; 
changing the catalyst concentration; 
changing the first reactant concentration; 
changing the volatiles content in the first liquid; 
changing the volatiles content in the second liquid; 
changing the second reactant concentration; 
changing the droplet size of the first liquid; and 
a combination thereof. 
This invention also pertains to a method, wherein the average droplet size 
of the second liquid is maintained at least adequately smaller than the 
average droplet size of the first liquid in a manner to decrease the 
probabilities of first droplets to collide with second droplets as 
compared to such probabilities when the average size of the second 
droplets is substantially the same as the average size of the first 
droplets. 
Further, the instant invention pertains to a method, wherein 
the reaction product comprises a compound selected from a group consisting 
of adipic acid, phthalic acid, isophthalic acid, and terephthalic acid, 
and 
the method further comprises a step of reacting said reaction product with 
a third reactant selected from a group consisting of a polyol, a 
polyamine, and a polyamide in a manner to form a polymer of a polyester, 
or a polyamide, or a (polyimide and/or polyamideimide), respectively. 
The method may further comprise a step of spinning the polymer into fibers. 
The present invention also pertains to an apparatus for making a reaction 
product in an exothermic reaction from a first liquid containing a first 
reactant and a gas containing a second reactant, comprising 
a reaction chamber; 
a first atomizer in the reaction chamber for atomizing the first liquid at 
a first flow rate, a first atomization temperature, and at a reaction 
pressure; 
condensing means within the reaction chamber for condensing vapors; and 
control means for maintaining first droplet temperature lower than a 
predetermined value by transferring heat from the first droplets to the 
condensing means. 
The condensing means may comprise a second atomizer for atomizing a second 
liquid at a second flow rate, and at a second atomization temperature. It 
is preferable that at least one of the first and the second atomizer is 
adapted to conduct interrupted atomization at desired intervals. 
The apparatus may further comprise one or more of: 
means for measuring the temperature of the droplets within the reaction 
chamber; 
means for recycling the first liquid in the reaction chamber; 
a divider for dividing the recycled first liquid into a first stream and a 
second stream, the first stream being directed to the first atomizer and 
the second stream being directed to the second atomizer; 
heating and/or cooling means (temperature controlling means) for bringing 
the first stream to the first atomization temperature and the second 
stream to the second atomization temperature; 
an arrangement, wherein the control means are adapted to maintain the first 
droplet temperature within predetermined limits by regulating the flow 
rates and atomization temperatures of the first and the second liquids; 
an arrangement wherein the control means are adapted to utilize data 
concerning temperature profiles in the reaction chamber in order to 
regulate the flow rates and atomization temperatures of the first and the 
second liquids; and 
means for feeding a total amount of second reactant in the reaction zone, 
the total amount of second reactant being in a range corresponding to 
stoichiometric to two times stoichiometric with respect to a total amount 
of first reactant fed to the reaction zone.

DETAILED DESCRIPTION OF THE INVENTION 
As aforementioned, the present invention relates to methods and devices for 
making reaction products, and preferably intermediate oxidation products, 
wherein a first reactant incorporated in an atomized liquid reacts with a 
gas containing a second reactant, which may preferably be an oxidant, 
under controlled conditions. The term "intermediate oxidation product", as 
aforementioned, signifies that the oxidation stops before substantially 
oxidizing the first reactant to carbon monoxide, carbon dioxide, or 
mixtures thereof. According to the present invention, the atomization 
conditions are subject to intricate critical controls and requirements as 
described and claimed hereinbelow. 
According to the present invention, conversion refers to conversion of a 
reactant to a reaction product. Thus conversion, at any point during a 
reaction, is defined as the percentage ratio of moles of reaction product 
formed during the reaction to the total moles of reactant in the 
feedstock, multiplied by the reciprocal of the number of moles of reaction 
product produced theoretically when one mole of reactant is completely 
converted to said reaction product. 
Transient conversion is the conversion taking place from the point that the 
first liquid is atomized to form first droplets to the point just before 
the first droplets coalesce to a mass of liquid, as described hereinwith. 
This occurs in just one cycle of droplet formation and droplet 
coalescence. 
Reactions which are geared to produce intermediate products, especially in 
the case of oxidations, have not been run under atomization conditions so 
far, since atomization promotes complete reactions to a final product. For 
example, oxidation of cyclohexane to adipic acid, or oxidation of p-xylene 
to terephthalic acid, have not been reported to be conducted under 
atomization conditions, and there is no incentive in the art to do so, 
since burning of cyclohexane to carbon dioxide has been expected to take 
place under such conditions. However, the inventors have discovered that 
in the presence of unexpected intricate critical controls and requirements 
of the instant invention, intermediate reaction or oxidation products, 
such as adipic acid, phthalic acid, isophthalic acid and terephthalic 
acid, for example, may be advantageously obtained under atomization 
conditions. 
The present invention enables economic oxidation reactions at improved 
yield with reduced compression costs and investment, using proven catalyst 
systems, with reduced off-gas waste-stream discharge to the atmosphere, 
with reduced off-gas cleanup investment and costs, without solids plugging 
or buildup problems, with high utility, high conversion rates, and with 
reduced oxygen concentrations in the reaction chamber. 
The ability to operate at lower oxygen concentration, made possible by this 
invention, with acceptable conversion rates in the reactor improves yield 
by reducing over-oxidations, and may eliminate safety (explosion) problems 
associated with operation in the explosive oxygen/fuel envelope by 
operating in the non-explosive oxygen/fuel envelope. In the current 
technology, reducing oxygen content below traditional levels would result 
in a non-economic reduction in reaction rate. In this invention, however, 
a significant increase in the ratio of gas-liquid interfacial area to 
liquid reaction mass--relative to current levels--offsets this rate 
reduction, thereby enabling economic operation at reduced oxygen 
concentration in the reactor. 
Yield improvements and/or operation parameters according to this invention 
result in waste minimization and considerable environmental improvement, 
which is a very important for the protection of the environment. 
Some of the key elements, which may be present singly or in any combination 
thereof, in the embodiments of the present invention, are: 
High productivity reaction volume; 
Elimination of reactor agitator and agitator seals; 
Efficient Catalyst Systems; 
Low or no off-gas waste-stream rate; 
Employment of an ultra-high ratio of gas/liquid interfacial area to liquid 
reaction volume; 
Employment of an ultra-low ratio of liquid reaction volume to liquid volume 
contained in the liquid-film diffusion zone attached to the gas interface; 
Variation and accurate control of the ratio of gas/liquid interfacial area 
to liquid reaction volume, and the ratio of liquid reaction volume to 
liquid volume contained in the liquid-film diffusion zone attached to the 
gas interface; 
Multi-parameter control of liquid reactant conversion; 
Multi-parameter control of liquid reaction mass temperature; 
Avoidance of solids buildup in the reactor; 
Internal condensation; and 
Easy recovery of high purity, high oxygen-concentration off-gas for recycle 
with low recompression requirements. 
This invention provides a more productive reaction volume than does the 
conventional technology. Reaction chamber productivity per unit liquid 
reaction volume is increased due to the greatly enhanced mass transfer 
rates afforded by this invention, coupled, if so desired, with measures to 
maximize droplet loading in the reaction chamber. Droplet loading in the 
reaction chamber may be maximized according to the present invention, by 
employing internal condensation and generating ultra-small liquid reaction 
droplets. The droplet loading, measured as a percent of reaction chamber 
volume occupied by the totality of the droplets in the reaction chamber at 
any one time, is preferably maintained in the range of 1-40%. More 
preferably, droplet loading is maintained in the range of 5-30%. More 
preferably still, droplet loading is maintained in the range of 10-20%. 
Excessively high droplet loading can lead to sudden and uncontrolled 
coalescence, and is to be avoided. Too low droplet loading can lead to low 
reaction chamber productivity. The optimal control of droplet loading and 
initial droplet size minimizes the coalescence of droplets, while in the 
reaction chamber, optimizes the mass transfer of oxygen or other oxidant 
from the gas phase to the liquid phase, and maximizes the liquid reaction 
volume available to support the desired product formation. 
As it will become clear in the course of this discussion, unlike in the 
conventional technology which utilizes sparging of oxidizing gases through 
mechanically agitated liquids containing reactants to be oxidized, there 
is no reaction chamber agitator and no agitator seals. This process 
simplification is made possible by the unique reaction environment 
provided by this invention, and is highly desirable as it reduces cost, 
investment, and improves plant utility compared to the conventional 
technology. 
Since according to the present invention the reaction is conducted within 
the droplets, which are in a liquid phase, the process still maintains the 
advantage of being able to employ efficient liquid-soluble catalyst 
systems, with the added advantage of attaining reaction conditions almost 
as efficient as those encountered in a homogeneous gaseous phase. 
Reactions in a gaseous phase would require costly and uncertain gas-phase 
catalysts or solid-phase catalyst systems. 
Further, this invention enables a low off-gas waste-stream rate, if so 
desired, which reduces the off-gas waste-stream rate to the environment, 
and reduces off-gas cleanup investment and costs, thus resulting in 
considerable environmental improvement. The low off-gas waste-stream rate 
may be made possible with a near-stoichiometric gaseous oxygen feed 
combined with high conversion rates and/or chemical yields, for example. 
In the conventional technology, reaction chamber non-condensible off-gas is 
commonly purged to the atmosphere without partial recycle back to the 
reaction chamber. This results in increased oxygen consumption and related 
cost, but is done to avoid high, non-economic recompression costs and 
investment. In the conventional technology, recompression costs and 
investment are high due to a high non-condensible load, and high recycle 
pressure requirement: 
high non-condensible load results from the relatively high chemical yield 
loss, and--in most instances--the use of air as the oxygen source; 
high recycle pressure is required to accommodate the high-pressure drop, 
subsurface sparging (into a liquid-filled reaction chamber) used in the 
conventional technology; 
the high-pressure drop is required, in the case of subsurface sparging, to 
overcome the liquid head in the reaction chamber and to provide high-power 
mixing; and 
high-power mixing is necessary, in the case of the conventional technology, 
to improve gas/liquid contacting and thereby accelerate the rate of oxygen 
transfer into the liquid phase. 
When condensation is employed at a stage before the pressure drop (internal 
condensation), the increased oxygen consumption and related cost, and the 
high, non-economic recompression costs and investment associated with the 
conventional technology are avoided. Internal condensation according to 
this invention is condensation of condensibles, which takes place within 
the pressurized system and before pressure drop to about atmospheric 
pressure. Inside condensation or inside internal condensation is 
condensation which takes place within the reaction chamber. According to 
this embodiment, it is possible to recycle oxygen-containing off-gas back 
to the reaction chamber with relatively low or no recompression 
requirement and cost. The recycle may be even eliminated without incurring 
significant adverse economic impact. When condensation is employed at such 
a stage, the recompression requirement is minimal--compared to the 
conventional technology--due to the low non-condensible off-gas rate, 
especially when near-stoichiometric oxygen feed is used. The low 
non-condensible off-gas rate is due to the combination of 
near-stoichiometric oxygen feed, with one or more of high second reactant 
conversion rate, high chemical yield, and internal condensation, enabled 
and provided for by the instant invention. 
According to the instant invention, when near-stoichiometric oxygen feed is 
desired, it is achievable by the high conversion of the oxygen feed to the 
reaction chamber per pass, hence needing little recycle requirement. The 
high chemical yield results in low non-condensible by-product formation, 
thereby significantly reducing off-gas purge load generated in the 
reaction chamber. Reduced off-gas purge load in turn reduces oxygen purge 
from the reaction chamber. Reduced oxygen purge from the reaction chamber 
minimizes oxygen recycle requirement. The implementation of internal 
condensation further reduces recompression requirement, as internal 
condensation outside the reactor further reduces oxygen recycle required, 
and the implementation of internal condensation inside the reactor reduces 
oxygen recycle requirement further still. This internal condensation 
significantly reduces oxygen physical yield-loss. In the limit, internal 
condensation, complete oxygen conversion per pass, i.e., stoichiometric 
oxygen feed, and zero non-condensible by-product formation would result in 
zero oxygen physical yield loss and zero recompression requirement. Due to 
the low non-condensible off-gas rate made possible when internal 
condensation is employed, it is significantly less costly (compared to the 
conventional technology) to forego recycle. 
In this invention, solids buildup in the reaction chamber may be prevented 
by washing the walls of the reaction chamber with preferably cooler, 
preferably catalyst-free liquid solvent, or with preferably catalyst-free 
liquid reactant, or with a mixture thereof. All surfaces of the reaction 
chamber, or a certain portion of those surfaces prone to solids buildup, 
may be washed in this manner. The wash liquid may be sprayed onto the 
surfaces so washed, or may be generated in situ as a result of internal 
condensation. Solids buildup is prevented because the solids in contact 
with these surfaces are continuously washed out of the reaction chamber. 
Furthermore, reaction in the wash-liquid is greatly minimized by the lower 
temperature or absence of catalyst, the short hold-up-time or a 
combination thereof. All solids produced in the reaction chamber are 
removed from the reaction chamber with the wash liquid. 
In the embodiments of this invention involving off-gas recycle, this 
invention provides means by which the recompression requirement can be 
greatly minimized or eliminated. Due to the small non-condensible off-gas 
rate associated with this invention, it is possible to educt the recycle 
off-gas into the reaction chamber using a liquid stream as the motive 
force. 
In the conventional technology, gas sparging bubbles are dispersed in a 
continuous liquid-phase comprised of liquid reactants, liquid solvents, 
dissolved reaction products and by-products, dissolved gases, and 
dissolved catalysts. A thin film of liquid is attached and surrounds each 
bubble, due to strong surface tension forces. While the thickness of the 
liquid-film is a function of many variables including, but not limited to, 
temperature and viscosity of the liquid solvent and liquid reactant, 
generally the thickness of the liquid-film is in the range of 0.05 inches 
to 0.0001 inches, and mostly in the range of 0.02 inches to 0.001 inches. 
Reactions can occur in this liquid-film and in the continuous-phase liquid 
surrounding this film. Reaction products may in fact be preferentially 
produced in the film, relative to the surrounding liquid, depending on the 
nature of the diffusional resistance inhibiting the transfer of materials 
from the liquid film into the surrounding liquid. In any event, it is 
expected that a significant amount of reaction will occur in the 
liquid-film due to its immediate proximity to the gas-phase second 
reactant, such as oxygen or other oxidant for example. In the conventional 
technology, the ratio of liquid reaction volume to liquid volume in the 
liquid-film is extremely high--typically, this would be several orders of 
magnitude. This extremely high ratio leads to two highly undesirable 
consequences: 
First, it leads to gross non-homogeneities in the concentration of reaction 
products between the two zones, with high localized product concentrations 
building up in the liquid-film. These high localized concentrations arise 
in the liquid-film in the conventional technology because a significant 
(perhaps even predominant) amount of reaction occurs in the liquid-film 
due to its immediate proximity to the gas-phase reactant, and because 
reaction products so formed in the liquid-film must necessarily increase 
in concentration--relative to the surrounding bulk liquid--to overcome 
diffusional resistance and migrate from the liquid-film out into the 
surrounding liquid. Furthermore, for a given production rate and 
conversion, the higher the ratio the higher the product concentration in 
the liquid-film. The worst consequence of high localized product 
concentration in the liquid-film in the conventional technology is that it 
leads directly to over-reaction products, such as over-oxidation for 
example. Over-oxidation results when already formed product continues to 
be exposed to reactive forms of oxygen. Over-oxidation in turn causes 
chemical yield loss, high product purification costs, and high waste 
disposal costs. 
Second, it leads to poor utilization of the total available reaction 
volume. This results because the most productive reaction volume is that 
in closest proximity to the gas-phase oxygen. The reaction volume closest 
to the gas-phase oxygen is the liquid-film. At very high ratios the amount 
of volume occupied by the liquid-film is extremely small; hence, the poor 
utilization at high reaction volume. 
This invention overcomes the aforementioned problems associated with the 
conventional technology by converting the reaction system to ultra-low 
ratio of liquid reaction volume to liquid volume in the liquid-film. This 
is the exact opposite of the conventional technology. In this invention, 
ultra-low ratios are obtained by converting the bulk stirred liquid phase 
to spray droplets of controlled small size suspended in the continuous 
gas-phase. The size of the droplets may be controlled such that the 
average radius of the droplet is preferably less than about 10 times the 
thickness of the diffusion film associated with the conventional 
technology. More preferably, the droplets should be controlled such that 
the average radius of the droplet is on less than about 5 times the 
thickness of the diffusion film associated with the conventional 
technology. More preferably still, the droplets are to be controlled such 
that the average radius of the droplet is less than about 1 time the 
thickness of the diffusion film associated with the conventional 
technology. In this way, the ratio can be decreased by orders of magnitude 
below that possible in the conventional technology. This is highly 
desirable because it enables a significant reduction in over-reaction with 
concomitant reduction in impurity levels, reduction in purification costs 
and investment, and reduction in waste-stream load, without loss of 
production rate, and with more efficient utilization of liquid reaction 
volume in the reaction chamber (compared to the conventional technology). 
Further, in the conventional technology, the ability to generate a high 
ratio of gas/liquid interfacial area to liquid reaction volume is 
constrained by natural effects (including liquid surface tension) to 
certain practical maximums. Heroic efforts, including high gas sparging 
rates and powerful agitation systems, have been employed to achieve 
operation near the upper maximum limit. The inventors theorized that a 
much higher ratio would be desirable, since it would facilitate the 
diffusion of oxygen reactant into a liquid film surrounding each gas 
bubble. This film is strongly attached to the bubble by strong surface 
tension forces. Reaction can occur in this film and in the 
continuous-phase liquid surrounding this film, and the ability to effect 
reaction in either zone is dependent on oxygen diffusion from the 
gas-phase into the film. In the conventional technology, higher diffusion 
rates may be only achieved by either increasing oxygen or other oxidant 
concentration in the gas passing through the liquid reaction phase, or by 
increasing the gas sparging rate. However, this is of very limited value, 
and only small improvements in diffusion rates may be made. 
In contrast, according to this invention, huge improvements in diffusion 
rates may be made by using ultra-high ratios of gas/liquid interfacial 
area to liquid reaction volume, which are obtained by converting the bulk 
stirred liquid phase into spray droplets of controlled small size within a 
continuous gas-phase. For this purpose also, the size of the droplets 
should be controlled such that the radius of the droplet is on average 
preferably less than about 10 times the thickness of the diffusion film 
associated with the conventional technology. More preferably, the droplets 
should be controlled such that the radius of the droplet is on average 
less than about 5 times the thickness of the diffusion film associated 
with the conventional technology. More preferably still, the droplets are 
to be controlled such that the radius of the droplet is on average less 
than 1 time the thickness of the diffusion film. By this method, the ratio 
of gas/liquid interfacial area to liquid reaction volume can be increased 
by orders of magnitude above that possible in the conventional technology. 
This is highly desirable because it enables a significant reduction in the 
oxygen concentration in the gas-phase without loss of production rate 
(compared to the conventional technology), or, alternately, higher oxygen 
diffusion rates (hence higher production rates) at comparable oxygen 
concentration in the gas-phase. 
The significant reduction in the oxygen concentration in the gas-phase, 
concurrent with still maintaining desirable high reaction rates, made 
possible by this invention, is extremely desirable because it acts to 
improve yield by reducing over-oxidation, improve safety by enabling 
operation further away from the oxygen/fuel explosive envelope, and 
minimize the amount of oxygen swept from the reaction chamber. Minimizing 
the amount of oxygen swept from the reaction chamber with other 
non-condensibles is desirable because it significantly reduces: (1) costly 
investment for waste off-gas environmental cleanup facilities, (2) waste 
off-gas discharges to the environment, thus providing considerable 
environmental improvement, and (3) very expensive, high maintenance, and 
potentially unsafe recompression requirements (all three of which cause 
problems in the conventional technology). 
According to the present invention, variation and accurate control of the 
ratio of gas/liquid interfacial area to liquid reaction volume, and the 
ratio of liquid reaction volume to liquid volume contained in the 
liquid-film at the gas interface are provided. Since, in the present 
invention, the gas-phase is the continuous-phase, both ratios may be 
simultaneously controlled by controlling the average droplet size and the 
droplet size distribution spectrum. For small droplets, surface tension 
forces will pull the droplets into near spheres. For spherical droplets, 
the ratio of gas/liquid interfacial area to liquid reaction volume is 
inversely proportional to droplet diameter, and the ratio of liquid 
reaction volume to liquid volume contained in the liquid-film is directly 
proportional to droplet diameter. Consequently, ultra-high ratio of 
gas/liquid interfacial area to liquid reaction volume and ultra-low ratio 
of liquid reaction volume to liquid volume contained in the liquid-film 
can be simultaneously achieved and controlled by reducing droplet diameter 
to very small, controlled diameters. Specifically, as aforementioned, the 
size of the droplets is to be controlled such that the diameter of the 
droplet is on average less than 10 times the thickness of the liquid-film 
associated with the conventional technology. However, since droplets of 
increasingly small size contain diminimous reaction volume, and since 
little further advantage is to be gained in enhanced reaction rate and 
reduced over-reaction, preferably the droplets are to be controlled such 
that the diameter of the droplet is more than 0.5 times the thickness of 
the liquid-film associated with the conventional technology. More 
preferably the droplets are to be controlled such that the diameter of the 
droplet is more than 1 time the thickness of the liquid-film associated 
with the conventional technology. While the thickness of the liquid-film 
associated with the conventional technology is a function of many 
variables including, but not limited to, temperature and viscosity of the 
liquid solvent and liquid reactant, generally the thickness of the 
liquid-film is in the range of 0.05 inches to 0.0001 inch. In absolute 
terms the preferred average droplet diameter is in the range of 0.001 to 
0.2 inch. 
The ways to control average droplet diameters in atomization is well-known 
to the art, and it includes, but is not limited to, nozzle design, 
variable nozzle characteristics, pressure of atomized material, pressure 
of gas if gas is used for the atomization process, and the like. 
The control of conversion within tight ranges and at desired levels is 
critical to a well run process. Erratic control leads to poor chemical and 
physical yields, process upsets, high purification costs, high trace 
impurity levels, high recycle requirements, lost utility, and reduced 
plant capacity. Too low conversion results in high recycle requirements, 
reduced physical yield, higher unit plant investment, higher unit energy 
consumption, and reduced plant capacity. Too high conversion leads to 
over-reaction, poor chemical yields, high purification costs, high trace 
impurity levels, higher unit plant investment, and reduced plant capacity. 
In this invention, multiple ways are provided to control conversion. 
Conversion may be controlled at a desired level by manipulation of 
variables, either alone or in combination with each other. Some of these 
variables are: 
Oxygen concentration in the reaction chamber. 
The ratio of the concentrations of liquid solvent to liquid reactant in the 
liquid feed to the reaction chamber. 
The concentration of catalyst in the liquid feed to the reaction chamber. 
The hold-up time of the liquid feed in the reaction chamber. 
The size or diameter of the droplets in the reaction chamber. 
The temperature of the droplets. 
According to this invention, conversion can be controlled, for example, by 
regulating the oxygen concentration in the reaction chamber. This is to be 
done by using oxygen as the limiting reagent. In this instance, the rate 
of oxygen feed to the reaction chamber would be increased or decreased as 
required to control conversion. Conversion is increased--holding all other 
parameters constant--by increasing oxygen feed rate, and thereby 
increasing oxygen concentration in the reaction chamber. Conversion is 
decreased--holding all other parameters constant--by decreasing oxygen 
feed rate, and thereby decreasing oxygen concentration in the reaction 
chamber. 
Further, conversion is increased--holding all other parameters constant--by 
increasing the concentration of catalyst in the liquid feed to the 
reaction chamber. Conversion is decreased--holding all other parameters 
constant--by decreasing the concentration of catalyst in the liquid feed 
to the reaction chamber. 
In addition, conversion is increased--holding all other parameters 
constant--by increasing the hold-up time of the liquid feed in the 
reaction chamber. Conversion is decreased--holding all other parameters 
constant--by decreasing the hold-up time of the liquid feed in the 
reaction chamber. Hold-up time of the liquid feed in the reaction chamber 
is controlled by varying the height of the gas-phase through the droplets 
fall. Hold-up time is increased by increasing the height, and decreased by 
decreasing the height. The height may be controlled in several ways. For 
example, it may be controlled by: 
Raising or lowering the height of the droplet spray nozzle or nozzles. 
Raising or lowering the height of a liquid pool at the liquid level at the 
end of the vertical reaction chamber. The height of the liquid pool can be 
determined and controlled by a variety of ways well known to the art. 
Also, conversion is increased--holding all other parameters constant--by 
decreasing the size of the liquid droplets in the reaction chamber. 
Conversion is decreased--holding all other parameters constant--by 
increasing the size of the liquid droplets in the reaction chamber. 
Droplet size inversely affects conversion by controlling oxygen mass 
transfer into the liquid reaction media. Since the ratio of surface area 
to volume for a spherical droplet is inversely proportional to the 
diameter of a droplet, and since oxygen transport from the gas-phase is 
directly proportional to the surface area of a droplet, then the ratio of 
oxygen mass transport to the liquid volume contained in a droplet varies 
inversely with the diameter of the droplet. Therefore, the relative oxygen 
mass transfer for larger droplets is smaller than that for smaller 
droplets, and conversion is correspondingly reduced when all other 
parameters are held constant. 
Because reaction rates are faster at higher temperatures, in this 
invention, conversion is increased--holding all other parameters 
constant--by increasing the temperature of the liquid droplets. Conversion 
is decreased--holding all other parameters constant--by decreasing the 
temperature of the liquid droplets in the reaction chamber. 
According to this invention, the heat of reaction may be removed from the 
liquid reaction mass as vaporized liquid reactant and vaporized liquid 
solvent. These vaporized materials may be condensed either outside or 
inside the reaction chamber as it will be discussed hereinbelow. Removal 
of heat inside the reaction chamber may be conducted for example by using 
condensation sprays, or condensation surfaces, or a combination thereof. 
It should be stressed that internal condensation may take place either 
outside or inside the reaction chamber, as illustrated later. Internal 
condensation is condensation which takes place within the system, before 
the pressure is relieved. Internal or external (outside the pressurized 
system) should not be confused with inside (inside the reaction chamber) 
and outside (outside the reaction chamber) conversion. 
In the case of condensation sprays, a portion of recycled liquid may be 
cooled in a heat exchanger or brought to a desired temperature by other 
temperature control means well known to the art, external to the reaction 
chamber, and be sprayed onto the interior reaction chamber walls, or into 
the gas-phase of the reaction chamber, or both. In the case where said 
spray is directed onto the reaction chamber wall, and in the instance 
where reaction products are relatively insoluble in said spray, then 
streams after filtering out the reaction products are preferable. The 
absence of catalyst in this case is also important, because this absence 
and the relatively cold nature of the incoming streams act to prevent 
reaction in said spray on the interior wall of the reaction chamber. In 
the case where reaction products are relatively insoluble, this absence of 
reaction prevents the highly undesirable accumulation of solids on this 
surface. Condensation spray is effective because hot, condensible gases 
inside the reaction chamber condense on the cool, liquid surface. The 
amount of condensation induced in this manner may be controlled by 
regulating the flow rate, temperature, and position of the condensation 
spray. Increasing the flow rate, decreasing the temperature, and 
controlling the condensation spray so as to increase its liquid surface 
area act individually or in combination to increase the rate of 
condensation of the vaporized liquid containing the reactant and vaporized 
liquid solvent; the converse is also true. 
Furthermore, in the case of condensation sprays, this invention provides 
both the means to control the liquid surface area of the condensation 
spray, and the means to prevent excessive contact of the reaction liquid 
spray with the condensation spray. Where condensation spray is directed 
against the side of the reaction chamber wall, the condensation surface 
area may be effectively controlled by manipulating the impingement 
position of the condensation spray nozzles on the side of the reaction 
chamber wall. Directing this spray higher up the side of the reaction 
chamber wall increases the condensation surface area. Conversely, 
directing it lower decreases the condensation area. Where the condensation 
spray is directed into the gas-phase of the reaction chamber, the 
condensation surface area may be effectively controlled by manipulating 
the size and amount of the droplets. Since the ratio of surface area to 
volume for a spherical droplet is inversely proportional to the diameter 
of a droplet, and since the cumulative volume of all of the droplets 
sprayed into the reaction chamber is fixed for a given flow rate, then the 
surface area may be easily and precisely increased--when all other 
parameters are held constant--by decreasing the droplet size. The converse 
is also true. Droplet size can be easily controlled using techniques well 
known to the art. 
Furthermore, in the case of condensation sprays, it is critical to prevent 
excessive contact of the reaction liquid spray with the condensation 
spray. This is true because the condensation spray may not contain 
catalyst and is deliberately cooled well below the reaction temperature of 
the liquid reaction media. Excessive mixing of these two sprays could 
result in a significant reduction in condensation efficiency, reaction 
rate, or both. Excessive mixing may be prevented in the first instance by 
positioning the spray nozzles so as to direct the condensation spray 
against the reaction chamber wall, and the liquid reaction spray into the 
gas-phase of the reaction chamber in a manner which minimizes wall 
contact. In the second instance, excessive mixing may be prevented by 
selecting a spray nozzle for the condensation spray which produces a very 
small diameter droplet. This technique is effective because very small 
droplets do not readily mix with similar, smaller, or larger sized 
droplets, thereby preventing the undesired contact with the liquid 
reaction spray. Furthermore, producing a very small condensation spray 
droplet is highly efficient, from the standpoint of the desired 
condensation of vaporized liquid reactant and vaporized liquid solvent, 
because it increases the condensation surface area. 
In the case of condensation sprays, and in the second instance, where the 
condensation spray is directed into the gas phase of the reaction chamber 
and where excessive mixing is prevented by selecting a spray nozzle for 
the condensation spray which produces a very small diameter droplet, this 
invention provides a reaction system in which the liquid contents of the 
reaction chamber are comprised of two different droplet types: both types 
simultaneously occupy the same reaction environment and each is in close 
proximity to the other, but each type remains separate, each may contain 
different concentrations of liquid solvent and liquid reaction chemicals, 
each type may be at significantly different temperatures, and each may 
perform different functions (namely, either condensation or reaction). 
In the case where vaporized liquid reactant and vaporized liquid are 
condensed inside the reaction chamber on metal surfaces, this may be 
accomplished in the first instance by externally cooling the reaction 
chamber walls with an external cooling jacket through which is circulated 
a cooling medium, like cooling water; or, in the second instance, by 
providing a cooling coil or other cooling surface inside the reaction 
chamber through which is circulated a cooling medium, like cooling water. 
In the first instance, condensation occurs inside the reaction chamber 
when condensible gases come into contact with the externally cooled 
reaction chamber walls. The walls cooled by this method may be the 
vertical sides of the reaction chamber, or the top, or the bottom, or a 
combination thereof. In the second instance, condensation occurs when the 
condensible gases come into contact with the internal cooling coils or 
other cooling surfaces inside the reaction chamber. 
According to this invention, non-condensible gases are swept away from the 
condensation surfaces (regardless of whether these condensation surfaces 
are the ones produced by the use of condensation sprays or by solid 
surfaces) by gaseous eddie currents inside the reaction chamber. These 
eddie currents may be induced by the combined liquid sprays inside the 
reaction chamber. The efficient removal of the non-condensible gases from 
the condensation surfaces is critical, because unless this is done, the 
condensation surfaces become blanketed by the non-condensibles, and the 
desired condensation is greatly diminished. 
As already discussed, according to this invention, non-condensible reaction 
by-product gases may be purged from the reaction chamber through an 
overhead gas outlet or they may be purged out the bottom of the reaction 
chamber. In the former case, the small diameter liquid reaction droplets, 
or the small diameter liquid reaction droplets along with very small 
condensation spray droplets, produced according to the methods of this 
invention, fall to the bottom of the reaction chamber, where they coalesce 
and exit the reaction chamber. In the latter case, the small diameter 
liquid reaction droplets, or the small diameter liquid reaction droplets 
along with the very small condensation spray droplets, either fall to the 
bottom of the reaction chamber and coalesce there, or are swept by the 
non-condensible purge gases into a swirling vortex at the bottom of the 
reaction chamber and, thereby, are brought into extremely close proximity 
with the liquid, where they coalesce, as it will be discussed in more 
detail later. The extremely close contact so induced is sufficient to 
coalesce the small diameter liquid reaction droplets, or the small 
diameter liquid reaction droplets along with the very small condensation 
droplets, from the gas purge into the liquid phase. In both cases, 
therefore, the liquids exiting the bottom of the reaction chamber may 
remove both the reaction liquid spray, and the condensation spray, if 
present, from the reaction chamber. 
Control of droplet impingement (to each other) resulting in increase of 
droplet size is very important, and as mentioned above, it may be 
controlled by controlling the droplet size of the first liquid or the 
second liquid or both. Reduction of the droplet size and decrease of the 
reactor loading favor the avoidance of impingement. Loading of the reactor 
is defined as the total volume of liquid divided by the total volume of 
the reactor. 
Monitoring carbon monoxide and carbon dioxide in the off-gases is a prudent 
precaution, since unexpected or higher than normal amounts of carbon 
monoxide and/or carbon dioxide signify poorly controlled or uncontrolled 
oxidation. Similar overriding rules applied by the controller help in 
preventing poor yields, conversions, and even explosions. 
In addition, carbon monoxide is harmful to the atmosphere and the reaction 
should be driven in a way to avoid its formation as much as possible. 
Optimization of the reaction conditions according to the instant invention 
has a beneficial effect in this respect. 
Our patent applications Ser. No. 08/477,234, U.S. Pat. No. 5,502,245 Ser. 
No. 08/478,257, U.S. Pat. No. 5,580,531 Ser. No. 08/477,195, and Ser. No. 
08/475,340, U.S. Pat. No. 5,558,842 all of which were filed on Jun. 7, 
1995, and all of which are incorporated herein by reference, disclose and 
claim miscellaneous methods and apparatuses for controlling reactions in 
general with special emphasis to oxidations, which may be combined with 
the embodiments of the present invention in any suitable manner, thus 
increasing even further waste minimization and resulting in considerable 
environmental improvement. 
Referring now to FIG. 1, there is depicted a conventional reactor 10, 
comprising a reaction chamber 11, connected to a condenser 12, which in 
turn is connected to a valve 13. A gas line 14 is also provided close to 
the bottom of the reaction chamber 11 for bubbling gas through a liquid 
containing a reactant, which reactant reacts with the gas a component of 
the gas to form a reaction product. The reaction chamber 11 may be 
pressurized, especially when the temperature required for the reaction to 
take place is higher than the boiling point of the liquid. This situation 
is very often encountered in the case of reactions involving organic 
compounds. Examples include, but are not limited to formation of 
cyclohexanone or cyclohexanol, or cyclohexylhydroperoxide, or adipic acid 
from cyclohexane by oxidation of the latter, usually by oxygen. Similar 
examples include formation of phthalic, isophthalic, or terephthalic acid 
by oxidation of the corresponding xylenes. 
This type of condensation may be labeled as internal outside condensation, 
since it takes place within the pressurized zone (internal), but outside 
the reaction chamber (outside). 
In this conventional case, large amounts of gases have to pass through the 
liquid in the form of gas in order to achieve an appreciable degree of 
reaction. This may not be true in the case of salt formation, where for 
example, an acidic gas passes through an alkaline liquid. However it is 
true for most organic reactions of this sort, and especially controlled 
oxidations (leading to intermediate oxidation products, other than carbon 
monoxide and/or carbon dioxide), wherein special attention has to be paid 
for avoiding combustion, or even explosion. The amount of gases increases 
even further if the gaseous reactant, such as oxygen for example, is 
diluted with an inert gas, such as nitrogen for example. In order to keep 
the gaseous flow adequately high for the reaction, and maintain the 
pressure within acceptable limits, valve 13 has to be open enough to allow 
the voluminous unreacted gases to escape to the environment. Recirculation 
of the high volumes of gases into the system is difficult and 
uneconomical. 
The main purpose of the condenser 12 in this conventional case of FIG. 1, 
is to remove condensibles from the voluminous gases before they escape to 
the environment. However, no matter how efficient the condenser 12 is, a 
small amount of condensibles will escape through valve 13 along with the 
gases. In reactors, such as the one illustrated in FIG. 1, removal of heat 
could be accomplished by direct cooling of the liquid, since the 
temperature of the liquid is actually the temperature which has to be 
controlled. Direct cooling of the liquid may be done, for example, with a 
jacket around the liquid or by a coil within the liquid. The gas/liquid 
interface, however, is too small in most cases for efficient cooling. In 
most cases the heat is removed by a volatile solvent in the liquid which 
evaporates during the course of the reaction. In the case of highly 
exothermic reactions, the massive amounts of evaporated solvent force 
large amounts of the gaseous reactant, such as oxygen for example, to 
follow the same path and finally be removed through valve 13. 
Recirculation of the gaseous reactant is very expensive, since it requires 
efficient high pressure compressors. 
In the reactor of FIG. 1, even if one had the valve 13 substantially 
closed, and were feeding just enough gaseous reactant, such as oxygen for 
example, to maintain a desired pressure by replacing the reacted amount of 
gaseous reactant with the liquid, comprising cyclohexane for example, the 
condenser would be filled with non-condensible gases at an early point, 
and condensation of condensibles would be reduced drastically if not 
ceased altogether. 
An internal (within the pressurized system) inside (within the reaction 
chamber) condenser (not shown) would not serve much of a purpose, since 
the liquid/gas interface is too small, and removal of reaction heat by 
condensation as a primary means heat removal would not be practical in 
this conventional arrangement. 
Another conventional arrangement is illustrated in FIG. 2, wherein the 
condenser 12 is located after the valve 13, and outside the pressurized 
zone. In this case an additional condensate tank 16 to collect the 
condensed condensibles, which may be recycled into the system. The 
problems described in the previous case become even more acute in this 
arrangement, especially with respect to increased contamination of the 
off-gases. 
In contrast to the above conventional systems, internal inside condensation 
may be used very efficiently according to the present invention. Three 
exemplary arrangements are shown in FIGS. 3, 4, and 5. 
In one embodiment of this invention, the reactor comprises a reaction 
chamber 22 as better illustrated in FIG. 3. The walls of reactor 22 are 
surrounded by a condenser in the form of a jacket 24. In the case that 
condensation is desired, a liquid 26, having a suitably low temperature, 
may be circulated in the jacket 24. The jacket 24 may also be used to 
heat-up the walls of the reaction chamber 22, by steam for example, if so 
desired. 
A first atomizer 28 having a plurality of nozzles 30 is disposed within the 
reactor, preferably at the upper end 32. 
The reaction chamber 22 is also provided with a gas line adapted to 
distribute a gas within the reaction zone 34 through a plurality of 
orifices 36. A gas exit port 38 is preferably located at the vicinity of 
the upper end 32 of the reaction chamber 22, and it is connected to valve 
39. Further, a liquid exit port is preferably located in the vicinity of 
the lower end 42 of the reaction chamber 22. 
The reaction chamber 22 is preferably adapted to withstand such 
temperatures and pressures, which are appropriate for the reaction 
conditions in the reaction chamber 22, and be suitable for the reactants 
and reaction products. Such materials and construction characteristics are 
well known to the art. For example, depending on the particular reaction, 
carbon steel, stainless steel, or Hastalloy may be required. In addition, 
the inside surface may be protected by coatings or linings of vitreous or 
other materials, such as glass or titanium, respectively for example. 
The atomizer 28 is preferably of the airless type (does not need an 
atomizing gas for its operation). Airless atomizers are well known to the 
art. The atomizer 28 may be steady at a certain position of the reaction 
chamber 22, or it may be movable, preferably in an up/down mode. 
In operation of this embodiment, a first liquid, for example a mixture of 
cyclohexane, a solvent such as acetic acid for example, a catalyst, such 
as a cobalt salt for example, an initiator, such as cyclohexanone or 
acetaldehyde for example, and other desirable adjuncts, in proportions 
which may be similar to the ones described in the art for conventional 
systems, and at an atomization temperature, enters the reaction chamber 
through the first atomizer 28 and nozzles 30 in the form of atomized or 
sprayed first droplets. The first liquid comprises a first reactant, which 
is cyclohexane in this example. At the same time that this atomization is 
taking place, a gas containing a second reactant, such as oxygen for 
example enters the system though gas line 33 and the plurality of orifices 
36 and moves in a substantially opposite direction than the first 
droplets. As the first droplets proceed within the reaction zone 34 from 
the upper part 32 toward the lower part 42 of the reaction chamber 22, the 
second reactant, oxygen for example, reacts at least partially with the 
first reactant, cyclohexane for example. During the reaction, heat is 
generated, which raises the temperature of the first droplets. As the 
temperature of the first droplet rises, evaporation of first liquid or 
components thereof takes place, thus lowering the temperature of the 
droplets. Droplet temperature may be controlled by controlling the rate of 
evaporation. Control of the rate of evaporation may be conducted by 
maintaining constant reactor pressure and by adjusting the rate of 
condensation of vapors on the condensing walls of the reaction chamber. 
This in turn is achieved by adjusting the temperature and rate of heat 
absorbed by the condenser in the form of jacket 24. Details of how is this 
carried out are discussed in a later section with reference to FIG. 6. 
Although FIG. 6 illustrates this for the embodiment of FIG. 5, all 
condensing mechanisms of this invention may be substantially controlled in 
the manner described with reference to FIG. 6. 
In contrast to the reaction chambers illustrated in FIGS. 1 and 2, the 
liquid/gas interface is huge in the case of the reaction chambers of this 
invention, and thus, condensation can be an excellent controlling factor 
of the rate of evaporation from the first droplets, and in turn an 
excellent control of the temperature of the first droplets. 
The excess gas is removed through gas exit port 38 and valve 39, while the 
first liquid is removed through liquid exit port 40. 
The pressure within the reaction chamber is controlled by the flow rate at 
which the gas enters the reaction chamber 22 through orifices 36 and the 
degree of opening of the valve 39, as well as the liquid condensate 
temperature. 
If the reaction is not complete by the time the first droplets reach the 
lower end of the reaction chamber, the first liquid may be partly or 
totally recirculated from the liquid exit port to the first atomizer 28, 
as is or after some treatment, well known to the art, to remove partially 
or substantially totally the reaction product and/or other adjuncts. 
A tremendous difference between the reactors of this invention (illustrated 
in FIG. 3 for example) and the conventional reactors (illustrated in FIG. 
1, for example) is that in the former case recirculation of liquids, which 
is very easy, may be required, while in the latter case, recirculation of 
gases may be necessary. 
Thus, in the case of this invention, the valve 39 may be substantially 
closed, and second reactant be introduced to the reaction chamber 22 per 
reaction needs, while merely recirculating the first liquid from the 
liquid exit port 40 back to the first atomizer 28. In contrast, if the 
same is desired for the conventional reactor illustrated in FIG. 1, the 
gas will have to be recirculated, which is a rather undesirable task. 
An additional advantage of the instant invention is that the temperature of 
the first droplets, which represent a rather small mass, may be controlled 
quickly and easily by internal inside condensation. In contrast, the big 
mass of liquid involved in conventional technology is necessarily very 
slow regarding forced temperature changes. 
In another embodiment of this invention, better illustrated in FIG. 4, a 
condensation coil 124 is used in lieu of the jacket 25 of FIG. 3. The 
operation of this embodiment regarding internal inside condensation is 
substantially the same as described hereinabove for the embodiment of FIG. 
3, with the difference that the internal inside condensation takes place 
on the coil 124 instead of the walls of the reaction chamber 122. 
In still another highly preferred embodiment of the instant invention, 
better illustrated in FIG. 5, there is provided a second atomizer 228' in 
addition to the first atomizer 228. The second atomizer 228' is adapted to 
form second droplets through nozzles 230' from a second liquid. The second 
droplets have a lower temperature than the first droplets formed by 
atomizer 228, and they are used as condensing means of vapors produced by 
evaporation of components from the first droplets. 
Although the second droplets produced from the second liquid may have any 
desired composition, it is preferable that they have at least one 
ingredient in common with the first droplets produced from the first 
liquid. It is more preferable that, if the first droplets comprise a first 
set of ingredients and the second droplets comprise a second set of 
ingredients, the first and second sets comprise the same ingredients. It 
is even more preferable that the two sets comprise the same ingredients 
under the same proportions. As a matter of fact, the first and the second 
droplets may be parts of the first liquid, which first liquid has been 
divided into two streams, a first stream corresponding to the first 
droplets, and the second stream corresponding to the second droplets. The 
basic difference between the first and the second droplets is that they 
are introduced to the reaction chamber at different temperatures (higher 
temperature for the first droplets, and lower temperature for the second 
droplets), and maybe different flow rates. The first droplets are utilized 
to perform the reaction, while the second droplets have as a main function 
to condense vapors produced by the first droplets, as the reaction 
proceeds and the temperature of the first droplets increases. Mixing of 
the two types of droplets with each other is highly undesirable, since it 
is detrimental to both reaction and condensation. 
Therefore, it is very important that as few as possible of the first 
droplets collide with second droplets in their path through the reaction 
zone. It is believed that the smaller the droplets the less the chances to 
collide. Thus, if there is no other compelling reason to increase the size 
of the droplets, they should be made to be as small as possible, of course 
within reason. It is also preferable that regardless of the size of the 
first droplets, the size of the second droplets is maintained adequately 
smaller in a manner to reduce the probabilities of collision between first 
and second droplets. 
The operation of this embodiment regarding internal inside condensation is 
substantially the same as described hereinabove for the embodiments of 
FIGS. 3 and 4, with the difference that the internal inside condensation 
takes place on the second droplets instead of the walls of the reaction 
chamber 22 or the coil 124, respectively. 
A controlled reactor device or apparatus 320 of the present invention can 
be exemplified by the schematic diagram illustrated in FIG. 6. Although 
the internal inside condensation in the example of FIG. 6 is conducted by 
a set of second droplets, which is highly preferable as discussed 
hereinabove, substantially the same or similar elements and operation 
principles may be used, regardless of the type of means used for 
conducting said internal inside condensation. 
The controlled reactor device 320 of FIG. 6 comprises a reaction chamber 
322, which is provided with a first atomizer 328 and a second atomizer 
328', preferably in the vicinity of the upper end 332 of the reactor 322. 
At the upper end 332, there is also a gas exit port 338 connected to a 
valve 339. In the vicinity of the lower end 342, there is provided a gas 
line 333 ending to one or more orifices 336. A liquid exit port 340 is 
also located in the vicinity of the lower end 342 of the reaction chamber 
322. 
One or more thermocouples 344, arranged within the reaction zone 334, are 
connected to a preferably computerized controller 346 through input lines 
344i. The thermocouples 344 may be positioned in any appropriate places of 
the reaction zone 334 in order to monitor the temperature of the falling 
droplets at different distances between the upper end 332 and the lower 
end 442 of the reaction chamber 322, either continuously, or at 
predetermined intervals of time. 
The device 320 is also provided with a source of first liquid, in the form 
of a tank 348, for example. A first pump 350 is adapted to pump a first 
stream of the first liquid from the tank 348 at a first controlled flow 
rate to a first heat exchanger 352, a first temperature monitor 354, a 
first flow rate monitor or first flow meter 356, and finally through first 
atomizer 328. In the same manner, a second pump 350' is adapted to pump a 
second stream of the first liquid from the tank 348 at a second controlled 
flow rate to a second heat exchanger 352', a second temperature monitor 
354', a second flow rate monitor or second flow meter 356', and finally 
through the second atomizer 328'. The heat exchanger may also be a simple 
heater or a simple cooler or chiller, depending on the reaction to take 
place and the initial temperature of the first liquid from the tank 348. 
According to the present invention, a heat exchanger may be a conventional 
heat exchanger, a heater, a cooler or a chiller. 
The first temperature monitor 354 and the first flow meter 356 are 
connected to the computerized controller 346 through input lines 354i and 
356i, respectively for providing the computerized controller 346 with 
first temperature and first flow rate information, respectively. In the 
same manner, the second temperature monitor 354' and the second flow meter 
356' are connected to the computerized controller 346 through input lines 
354i' and 356i', respectively, for providing the computerized controller 
346 with second temperature and second flow rate information, 
respectively. 
There is also provided a gas source 358, which contains the second 
reactant, oxygen for example, in the case of oxidation of cyclohexane to 
adipic acid for example. 
The second gas source 358 is connected to a pressurizing pump 360, which is 
connected to gas line 333, which in turn leads to the orifices 336 in the 
reaction chamber 322. Since the gas in most occasions is already 
pressurized in the gas source, which is usually a suitable tank, the 
pressurizing pump 360 may be replaced by a valve (not shown) or a pressure 
regulator (not shown), or both. 
A pressure gauge 362 is also provided within the reaction chamber 322 in 
order to provide pressure information to the computerized controller 346 
through input line 362'. 
Carbon monoxide and carbon dioxide monitors (not shown) are also preferably 
provided to transfer respective information to the controller 346 as 
already discussed earlier. 
The preferably computerized controller 346 controls the pumps 350 and 350' 
through output lines 350u and 350u', respectively, and the heat exchangers 
352 and 352' through output lines 352u and 352u' respectively. It also 
controls the valve 339 and the pressurizing pump 360 through output lines 
339u and 360u, respectively. As already mentioned, the pump 360 may be 
replaced by a valve or pressure regulator (not shown), in which case the 
valve or pressure regulator are controlled through line 360u in place of 
the pump 360. 
In operation of the controlled reaction device, a first stream of the first 
liquid, which comprises for example a mixture of cyclohexane as first 
reactant, a solvent, such as acetic acid for example, a catalyst, such as 
a cobalt salt for example, an initiator, such as cyclohexanone or 
acetaldehyde for example, and other desirable adjuncts, in proportions 
which may be similar to the ones described in the art for conventional 
systems, is pumped from tank 348 by pump 350 through the heat exchanger 
352, where it assumes a desired temperature, measured by the temperature 
monitor 354. 
The heated first stream passes through the flow meter 356, where its flow 
rate is measured, and then, it enters the reaction chamber through the 
first atomizer 328 and nozzles 330 in the form of atomized or sprayed 
first droplets at the first atomization temperature as measured by the 
temperature monitor 354. Both the first atomization temperature and the 
first flow rate are provided to the controller 346 for processing. If the 
temperature provided to the controller 346 is higher than the desired 
atomization temperature, the heat exchanger 352 is ordered by the 
controller 346, through output line 352u, to provide less heat to the 
first stream passing through the heat exchanger, until the first 
atomization temperature drops to the desired level. If the temperature 
provided to the controller 346 is lower than the desired atomization 
temperature, the heat exchanger 352 is ordered by the controller 346, 
through output line 352u, to provide more heat to the first stream passing 
through the heat exchanger 352, until the first atomization temperature 
increases to the desired level. 
Similarly, if the flow rate as measured by the flow meter 356 and provided 
to the controller 346 is higher than the desired first flow rate, the pump 
350 is ordered by the controller 346, through output line 350u, to lower 
its pumping action, until the first flow rate drops to the desired level. 
If the flow rate as measured by the flow meter 356 and provided to the 
controller 346 is lower than the desired first flow rate, the pump 350 is 
ordered by the controller 346, through output line 350u, to raise its 
pumping action, until the first flow rate increases to the desired level. 
A second stream of the first liquid, is also pumped from tank 348 by pump 
350' through the heat exchanger 352', where it assumes a desired second 
atomization temperature, lower than the atomization temperature of the 
first stream and measured by the temperature monitor 354'. 
The heated second stream passes through the flow meter 356', where its flow 
rate is measured, and the then, it enters the reaction chamber through the 
second atomizer 328' and nozzles 330' in the form of atomized or sprayed 
second droplets at the second atomization temperature (lower than the 
first atomization temperature) as measured by the temperature monitor 
354'. Both the second atomization temperature and the second flow rate are 
provided to the controller 346 for processing. If the temperature provided 
to the controller 346 is higher than the desired second atomization 
temperature, the heat exchanger 352' is ordered by the controller 346, 
through output line 352u', to provide less heat to the second stream 
passing through the heat exchanger 352', until the second atomization 
temperature drops to the desired level. If the temperature provided to the 
controller 346 is lower than the desired second atomization temperature, 
the heat exchanger 352' is ordered by the controller 346, through output 
line 352u', to provide more heat to the second stream passing through the 
heat exchanger 352', until the second atomization temperature increases to 
the desired level. 
Similarly, if the flow rate as measured by the flow meter 356' and provided 
to the controller 346 is higher than the desired second flow rate, the 
pump 350' is ordered by the controller 346, through output line 350u', to 
lower its pumping action, until the second flow rate drops to the desired 
level. If the flow rate as measured by the flow meter 356' and provided to 
the controller 346 is lower than the desired second flow rate, the pump 
350' is ordered by the controller 346, through output line 350u', to raise 
its pumping action, until the second flow rate increases to the desired 
level. 
At the same time that the first and second atomizations are taking place, a 
gas containing a second reactant, such as oxygen for example, enters the 
system though gas line 333 and the orifices 336, and moves in a 
substantially opposite direction than the first and second droplets. The 
pressure in the reaction chamber 322 is measured by the pressure gauge 
362, and the information is fed to the computerized controller 346 through 
input line 362'. If the pressure is higher than a desired pressure, the 
controller orders the valve 339 to assume a more open position, or it 
orders the pressurizing pump to reduce feeding of gas to line 333, until 
the pressure assumes the desired value. Since waste minimization is a very 
important factor for environmental improvement, the computerized 
controller is preferably programmed in a manner that larger opening of the 
valve 339 is used as a last resort. If the pressure is lower than the 
desired one, the controller 346 orders the valve 339 to assume a more 
closed position or the pump 360 to pass more gas to line 333 from the gas 
source 336. The flow of the gas through line 333 may be measured by a flow 
meter (not shown) on said line and fed to the computerized controller 346. 
It becomes then clear that the pressure in the reaction chamber and flow 
rate of gas to the reaction chamber can be controlled by adjusting the 
pumping action of the pressurizing pump 360 and the opening of valve 339. 
As aforementioned, the pressurizing pump 333 may be replaced by other 
devices, such as a pressure regulator for example, if the pressure in the 
gas source 358 is maintained at a suitable pressure greater or equal to 
the desired pressure in the reaction chamber 322. 
In case it is desired to remove inert gases, the opening of valve 339 may 
be increased. Simultaneously, if so desired, second reactant, for example 
oxygen, may be forced into the reaction chamber in order to maintain both 
the total pressure and the partial pressure of the second reactant at 
predetermined levels. A monitor (not shown) for second reactant may be 
positioned within the off-gas region to monitor the content of second 
reactant. This information, combined with the known amounts of second 
reactant entering the reaction chamber, may be easily correlated to the 
progress of the reaction, by simple mathematical techniques well known to 
the art, and easily performed by the computerized controller 346. 
As the droplets proceed within the reaction zone 334 from the upper part 
332 toward the lower end 342 of the reaction chamber 322, the second 
reactant, oxygen for example, reacts at least partially with the first 
reactant, cyclohexane for example. During the reaction, heat is generated, 
which raises the temperature of the first droplets. As the temperature of 
the first droplets rises, evaporation of first liquid or components 
thereof takes place. As aforementioned, the rate of evaporation may be 
controlled by adjusting the rate of condensation of vapors on the second 
droplets, the temperature of which is lower. By increasing the second flow 
rate (the flow rate of the second stream) and decreasing the second 
atomization temperature, the rate of condensation of vapors on the second 
droplets increases, resulting in an increase of vaporization rate from the 
first droplets, which in turn results in cooling of the first droplets. By 
decreasing the second flow rate (the flow rate of the second stream) and 
increasing the second atomization temperature, the rate of condensation of 
vapors on the second droplets decreases, resulting in an decrease of 
vaporization rate from the first droplets, which in turn results in 
reduced cooling of the first droplets. 
It can be seen then that heat transfer from the first droplets to the 
second droplets or any other condensation means is regulated by the 
controller 346. The vapor condensation, of vapors formed from the first 
droplets, on the second droplets may be at least partially controlled by 
one parameter selected from a group consisting of (a) temperature 
difference between the first and the second atomization temperature, (b) 
flow rate difference between the first and the second flow rate (c) the 
volatiles content of the first liquid, (d) the volatiles content of the 
second liquid, (e) the volatility of the first or second volatiles, and 
(f) a combination thereof. 
It is preferable that the total amount of second reactant allowed to enter 
the reaction chamber 322 is in the range corresponding to one time 
stoichiometric to five times stoichiometric, and preferably to two times 
stoichiometric, with respect to the total amount of the first reactant fed 
to the reaction chamber or reaction zone. This is very important for waste 
minimization and environmental improvement reasons, since the off gases 
produced under these conditions are minimized. In one example, if X moles 
of first reactant, such as cyclohexane for example, exist in an unreacted 
state in a reactor to form adipic acid by direct oxidation with oxygen, 
then preferably 2.5X to 12.5X, and more preferably 2.5X to 5X moles of 
oxygen are allowed to be present in the reactor, regardless of whether the 
reaction is a batch reaction or a continuous reaction. 
The thermocouples 344 take the temperature of the droplets and feed this 
information to the controller 346. In one embodiment of the present 
invention, the controller may order the pump 350' to interrupt pumping at 
certain predetermined intervals and for short periods of time. When this 
occurs, there are no second droplets in the reaction chamber, and 
therefore, the thermocouples directly measure the actual temperature of 
the first droplets in substantially the absence of condensation, as the 
first droplets proceed in the reaction zone 334 from the upper end 332 to 
the lower end 342 of the reaction chamber 322. If the interruption of the 
second droplet flow is of sufficiently short duration, the first droplets 
will continue to be cooled by the solvent vaporization effect, and the 
temperature measured by the controller under these circumstances 
represents the actual temperature that the first droplets attain due to 
the combined effects of heat released by the reaction and solvent 
evaporation, when the rest of the parameters remain constant. //If the 
interruption is allowed to continue for a sufficiently longer period of 
time, then the temperature measured by the controller represents the 
maximum temperature that the first droplets may attain due to the heat 
released by the reaction, when the rest of the parameters remain constant. 
The controller, based on this information, gives appropriate orders to the 
other components of the device to prevent this temperature from exceeding 
predetermined limits, if so desired, not only for purposes of controlling 
the reaction but also to prevent catastrophic results in case that the 
internal condensation is interrupted for prolonged periods of time by 
accident or otherwise, and the reaction heat released is excessive. This 
presents an additional safeguard. 
Although one thermocouple, preferably close to the lower end 342, may be 
used for monitoring temperature, it is more preferable to use more than 
one thermocouples 344 in the reaction zone 334 for determining the rate of 
temperature rise, or temperature profile in the droplet path. This is 
useful information, since, based on such information, the elevation of the 
second atomizer may be physically lowered to the point where the internal 
inside condensation is needed most. Also the controller 346 is preferably 
adapted to utilize data concerning temperature profiles in the reaction 
chamber in order to regulate the flow rates, atomization temperatures of 
the first and the second liquids, as well as other parameters as discussed 
hereinbelow. The higher the temperature changes from thermocouple to 
thermocouple the more drastic the changes ordered by the controller. 
Pressure inside the reaction chamber may influence the rates of evaporation 
and condensation, and thus it may be used by the controller 346, 
especially in combination with other parameters already discussed, to 
control the heat exchange between the first and second droplets. Lower 
pressure causes higher evaporation rate, while higher pressure causes 
lower evaporation rate, provided that the vapors are condensed. 
The first and second droplets preferably coalesce together into a mass of 
liquid 364, which exits the reactor through liquid exit port 340. 
Depending on the degree of completion of the reaction, the liquid 364 may 
be re-circulated into the tank 348, preferably after at least partial 
removal of the reaction product, or undergo other treatment, depending on 
the reaction. 
The miscellaneous control parameters according to the preferred embodiments 
of the instant invention are used in a way that condensation is controlled 
in a manner that in turn the conversion of the first reactant in the first 
droplets, the temperature of the first droplets, and the final composition 
of the first droplets may be controlled at one or more predetermined 
points within the reactor. 
There are mainly two aspects to first reactant conversion control. The 
first is to determine the first reactant conversion as a function of its 
path through the reactor, while the second is to control the first 
reactant conversion at a desired setpoint or setpoints. The amount of 
reaction in the first droplet and the amount of first reactant conversion, 
as a function of the first droplets path through the reactor, may be 
calculated by the computerized controller 346--using mass and energy 
balances well known to the art--as a function of: 
the overall temperature of the combined first and second droplets at a 
certain point or points within the reactor as determined by one or more of 
the thermocouples 344; 
first stream inlet flowrate as measured by first flowmeter 356, first 
atomization temperature as measured by the first temperature monitor 354, 
and composition as determined to be in tank 348, either because of mixing 
known materials in known amounts, or by analytical techniques well known 
to the art, or composition as modified in the first stream by introduction 
of desired ingredients through other streams (not shown); 
second stream inlet flowrate as measured by second flowmeter 356', second 
atomization temperature as measured by the second temperature monitor 
354', and composition as determined to be in tank 348, either because of 
mixing known materials in known amounts, or by analytical techniques well 
known to the art, or composition as modified in the second stream by 
introduction of desired ingredients through other streams (not shown); 
reactor pressure as measured by the pressure gauge 362; and 
the concentrations of inert gases, if present, and second reactant, such as 
oxygen for example, in the reactor. 
The first reactant conversion may also be directly measured by sample 
analysis. 
The first reactant conversion may then be controlled by the following 
guidelines (implemented alone or in concert by controller 346 and the 
corresponding control devices): 
conversion can be decreased by decreasing the first atomization temperature 
through the first heat exchanger 352; 
conversion can be decreased by decreasing second atomization temperature 
through the second heat exchanger 352'; this increases condensation on the 
second droplets, increasing vaporization from the first droplets resulting 
in lowering the temperature of the first droplets, and therefore, in 
decreasing conversion; 
conversion can be decreased by decreasing catalyst concentration; this can 
be done, for example, by introducing into the first stream a third stream 
(not shown), also controlled by the controller 346, containing all the 
ingredients of the contents of the tank 348, with lower content of 
catalyst or no catalyst; alternatively, in another example, the tank 348 
can contain substantially all ingredients except catalyst and the third 
stream (not shown), also controlled by the controller 346, can contain 
substantially only catalyst, preferably dissolved in a liquid medium, so 
that controller 346 can change appropriately the flow of the third stream; 
conversion can be decreased by increasing the concentration of the first 
reactant in the first liquid; this can be done, for example, by 
introducing into the second stream a fourth stream (not shown), also 
controlled by the controller 346, containing all the ingredients of the 
contents of the tank 348, but having higher content of first reactant; 
alternatively, in another example, the tank 348 can contain substantially 
all ingredients except first reactant and the fourth stream (not shown), 
also controlled by the controller 346, can contain substantially only 
first reactant, so that controller 346 can change appropriately the flow 
of the fourth stream; 
conversion can be decreased by increasing the concentration of volatiles in 
the first stream; evaporation of volatiles decreases the temperature 
resulting in lower conversion; also dilution due to volatiles introduction 
leads to lower conversion; incorporation of controlled amounts of 
volatiles may be achieved by a fifth stream (not shown) entering into the 
first stream and controlled by the computerized controller 346; 
conversion can be decreased by decreasing second reactant concentration in 
the reactor; this can be achieved, for example, by introducing into line 
333 an amount of inerts controlled (not shown) by the computerized 
controller 346; or it can be achieved, in another example, by decreasing 
the pumping action of the pressurizing pump 360, or increasing the opening 
of valve 339, or a combination thereof; 
conversion can be decreased by increasing first liquid droplet size through 
control (not shown) of the first atomizer by the controller 346, using 
methods well known to the art. 
The converse of these guidelines is also true. 
It becomes evident then that the desired values of conversion or transient 
conversion depend on a number of parameters, and can vary broadly in each 
particular case. For example, in some occasions, values of transient 
conversion may go as low as 0.05% or even lower. This is true not only in 
the context of the present invention, but also in the context of our 
co-pending applications Ser. Nos. 08/477,234, 08/478,257, 08/477,195, and 
08/475,340, all of which were filed on Jun. 7, 1995. 
There are two aspects to first droplet temperature control. The first is to 
determine the temperature of the first droplet as a function of its path 
through the reactor. The second is to control the temperature at a desired 
setpoint or setpoints. 
The first droplet temperature, as a function of its path through the 
reactor, can be calculated as a function of the following variables: 
amount of first reactant conversion having taken place in the first droplet 
as a function of its path through the reactor as calculated by the 
computerized controlled 346 or as measured by sample analysis; 
first stream inlet flowrate as measured by the first flowmeter 356, first 
atomization temperature as measured by the first temperature monitor 354, 
the average temperature between the first and second droplets as measured 
by the thermocouples 344, and the composition in the tank 348, as made or 
as modified otherwise in the first stream; 
second stream inlet flowrate as measured by the second flowmeter 356', 
second atomization temperature as measured by the second temperature 
monitor 354', the average temperature between the first and second 
droplets as measured by the thermocouples 344, and the composition in the 
tank 348, as made or as modified otherwise in the second stream; 
reactor pressure as measured by the pressure gauge 362; and 
the concentrations of inerts and oxygen in the reactor as computed by the 
computerized controller 346, or as measured by direct analysis 
Given this information, the temperature of the first droplet, at a point or 
points within the reactor, may be calculated by the computerized 
controller 346 using mass balances, energy balances, vapor-liquid 
equilibrium data, and kinetic rate equations for mass and energy transfer 
well known to the art. 
First droplet temperature may then be controlled by the following 
guidelines (implemented alone or in concert by the computerized controller 
346): 
the first droplet temperature can be decreased by decreasing first 
atomization temperature as measured by the first temperature monitor 354; 
the first droplet temperature can be decreased by decreasing second 
atomization temperature as measured by the second temperature monitor 354; 
the first droplet temperature can be decreased by decreasing catalyst 
concentration; this can be done, for example, by introducing into the 
first stream a third stream (not shown), also controlled by the controller 
346, containing all the ingredients of the contents of the tank 348, with 
lower content of catalyst or no catalyst; alternatively, in another 
example, the tank 348 can contain substantially all ingredients except 
catalyst and the third stream (not shown), also controlled by the 
controller 346, can contain substantially only catalyst, preferably 
dissolved in a liquid medium, so that controller 346 can change 
appropriately the flow of the third stream; 
the first droplet temperature can be decreased by decreasing the 
concentration of the first reactant in the first liquid; this can be done, 
for example, by introducing into the second stream a fourth (not shown) 
stream, also controlled by the controller 346, containing all the 
ingredients of the contents of the tank 348, with lower content or no 
first reactant; alternatively, in another example, the tank 348 can 
contain substantially all ingredients except first reactant and the fourth 
stream (not shown), also controlled by the controller 346, can contain 
substantially first reactant, so that controller 346 can change 
appropriately the flow of the fourth stream; 
the first droplet temperature can be decreased by increasing the 
concentration of volatiles in the first stream; evaporation of volatiles 
decreases the temperature; incorporation of controlled amounts of 
volatiles may be achieved by the fifth stream (not shown) entering into 
the first stream and controlled by the computerized controller 346; 
the first droplet temperature can be decreased by decreasing second 
reactant concentration in the reactor; this can be achieved, for example, 
by introducing into line 333 an amount of inerts controlled (not shown) by 
the computerized controller 346; or it can be achieved, in another 
example, by decreasing the pumping action of the pressurizing pump 360, or 
increasing the opening of valve 339, or a combination thereof; 
the first droplet temperature can be decreased by increasing first liquid 
droplet size through control (not shown) of the first atomizer by the 
controller 346, using methods well known to the art. 
The converse of these methods is also true. 
There are two aspects to first droplet composition control. The first is to 
determine the composition of the first droplet as a function of its path 
through the reactor. The second is to control the composition of a 
selected ingredient, or of a group of selected ingredients which together 
form a subset of all the ingredients present in the droplet, at a desired 
value or values. 
The first droplet composition, as a function of its path through the 
reactor, can be calculated as a function of the following variables: 
amount of first reactant conversion having taken place in the first droplet 
as a function of its path through the reactor as calculated by the 
computerized controlled 346 or as measured by sample analysis; 
first stream inlet flowrate as measured by the first flowmeter 356, first 
atomization temperature as measured by the first temperature monitor 354, 
the average temperature between the first and second droplets as measured 
by the thermocouples 344, and the composition in the tank 348, as made or 
as modified otherwise in the first stream; 
second stream inlet flowrate as measured by the second flowmeter 356', 
second atomization temperature as measured by the second temperature 
monitor 354', the average temperature between the first and second 
droplets as measured by the thermocouples 344, and the composition in the 
tank 348, as made or as modified otherwise in the second stream; 
reactor pressure as measured by the pressure gauge 362; and 
the concentrations of inerts and oxygen in the reactor as computed by the 
computerized controller 346, or as measured by direct analysis; 
temperature of the first droplet as a function of its path through the 
reactor 
Given this information, the composition of the first droplet, at a point or 
points within the reactor, may be calculated using mass balances, energy 
balances, vapor-liquid equilibrium data, and kinetic rate equations for 
mass and energy transfer well known to the art. 
First droplet composition of a selected ingredient, or of a group of 
selected ingredients which together form a subset of all the ingredients 
present in the droplet, may be controlled at a desired value or values by 
the following guidelines (implemented alone or in concert): 
Content of first reactant can be decreased by increasing first atomization 
temperature as described above; 
Content of first reactant can be decreased by decreasing second atomization 
temperature as described above; 
Content of first reactant can be decreased by increasing catalyst 
concentration as described above; 
Content of first reactant can be decreased by decreasing the concentration 
of the first reactant in the first liquid, or the first stream or the 
second stream or a combination thereof, as described above; 
content of first reactant can be decreased by decreasing the concentration 
of volatiles in the first liquid as described above; 
content of first reactant can be decreased by increasing second reactant 
concentration in the reactor as described above; 
content of first reactant can be decreased by decreasing first liquid 
droplet size as described above; 
content of volatiles can be decreased by increasing first atomization 
temperature as described above; 
content of volatiles can be decreased by decreasing second atomization 
temperature as described above; 
content of volatiles can be decreased by increasing catalyst concentration 
in the first stream as described above; 
content of volatiles can be decreased by increasing the concentration of 
the first reactant in the first stream as described above; 
content of volatiles can be decreased by decreasing the concentration of 
volatiles in the first stream as described above; 
content of volatiles can be decreased by increasing second reactant 
concentration in the reactor as described above; and 
content of volatiles can be decreased by decreasing first droplet size as 
described above. 
The converse of these methods is also true. 
It should be stressed that when the internal inside condensation is 
performed by solid surfaces within the reaction chamber, and not by means 
of second droplets, the first droplet temperature can be directly measured 
by thermocouples positioned in desired locations of the reaction chamber. 
The use of second droplets, however, for condensation is of utmost 
importance, since it presents an unprecedented way of ultra-efficient 
manner to control condensation within the reaction zone, in an exothermic 
reaction. 
The second liquid may have the same composition as the first liquid, as 
described above where it is in the form of a second stream of the first 
liquid, or it may have a different composition. It is highly preferable 
that it has the same composition. It may also have such a composition so 
that the mass of the liquid 364 after at least partial removal of the 
reaction product assumes a composition similar to the composition of the 
first liquid. For example, in the case of oxidation of cyclohexane to 
adipic acid, the second liquid may contain an excess of cyclohexane, which 
will virtually replace in liquid mass 364 the cyclohexane which will react 
in the first liquid. Absence of catalyst in the second liquid promotes 
absence of reaction in the second droplets. The second liquid may also be 
immiscible with the first liquid, so that they may be separated easily 
after removal from the reaction chamber. Nevertheless, close similarity of 
the first and second liquids, highly simplifies the process, and as 
aforementioned, it is highly preferable. 
In a different embodiment of the present invention, better shown in FIG. 7, 
the reactor 422 comprises a first atomizer 428, and a ring 428', which is 
adapted to distribute the second liquid substantially uniformly on the 
inside surface of the reactor 422 in the form of a thick film or curtain 
466. The second liquid has a lower temperature than the first liquid, and 
condensation of vapors produced by the first droplets takes place on the 
curtain of said second liquid which covers the periphery of the reaction 
zone. 
The operation of this embodiment is substantially the same as the operation 
of the previous embodiments, with the difference that the vapors produced 
by the first droplets condense on the curtain or thick film 446. 
In still a different embodiment of the present invention, better shown in 
FIG. 8, the reactor 522 comprises a first atomizer 528, and a ring 528', 
which is adapted to distribute the second liquid substantially uniformly 
on the inside surface of the reactor 522 in the form of a thick film or 
curtain 566, as in the case of the previous embodiment. The second liquid 
has a lower temperature than the first liquid, and condensation of vapors 
produced by the first droplets takes place on the curtain of said second 
liquid which covers the periphery of the reaction zone. At the lower end 
542 of the reactor 522 there is provided a pan 568, ending to a pan exit 
570, while the reaction chamber 522 ends to a reactor exit 572. 
The operation of this embodiment is substantially the same as the operation 
of the previous embodiment, with the difference that most of the reacted 
material falls into the pan and removed from the pan exit 570, while most 
of the condensed material is removed from the reactor exit 572. This at 
least partial separation of reacted material from condensed material is 
important, especially when the composition of the curtain 566 differs 
substantially from the composition of the first liquid. 
In still a different embodiment, better shown in FIG. 9, there is provided 
a jacket 624, similar to the jacket 24 of the embodiment depicted in FIG. 
3. The jacket 624 provides a cold solid surface in the reactor 622, on 
which surface vapors are condensed and are removed through the reactor 
exit 672, while most of the reacted material is removed from the fan exit 
670 after being collected by pan 668. 
The operation of this embodiment is substantially the same as the operation 
of the immediately previous embodiment. 
As aforementioned, the methods and the devices of the instant invention may 
be used for substantially any types of exothermic reactions, wherein a 
first reactant in a liquid reacts with a second reactant in a gas to form 
a reaction product. Such reactions include, but are not limited to 
esterifications, ether formations, amide or imide formations, salt 
formations, ammoniations, nitrations, oxidations, and the like. Oxidations 
are particularly suitable for oxidation reactions of organic compounds, 
wherein the major portion of the reaction product is an oxidation product 
different than CO, CO.sub.2, or a mixture thereof. One of the reasons why 
this is so, is that, due to the intricate criticalities of the present 
invention, the reaction rates, reaction homogeneity, yield, and other 
important properties are considerably improved, while in the absence of 
said criticalities complete oxidation to CO/CO.sub.2 would take place. 
Actually, the same conditions of atomization without said criticalities, 
are presently used in combustion engines of automobiles and other devices, 
to substantially completely oxidize (combust or burn in other words) 
organic compounds such as gasoline to a mixture of CO/CO.sub.2. 
In contrast, according to the present invention, if for example, the first 
reactant is cyclohexane, the major portion of the oxidation product may be 
substantially cyclohexanol, cyclohexanone, cyclohexylhydroperoxide, 
caprolactone, adipic acid, the like, and mixtures thereof. Organic acids 
are preferable oxidation products. 
Many catalysts used for reactions, such as oxidations for example, are 
transition metals having more than one valence states. Their major 
catalytic action is exhibited when they are at a higher valance state than 
their lowest valance state at which they exist as ions. One good example 
is cobalt in the case of oxidation of cyclohexane to adipic acid. An 
initiation period before the oxidation starts has often been attributed by 
researches to the addition of cobalt ions at a valance state of II. The 
cobalt catalyst is added at valance state II because cobaltous acetate, 
for example, is more readily available and it is less expensive than 
cobaltic acetate. Thus, it takes a period of time for the cobaltous ion to 
be oxidized to cobaltic ion and start acting as a catalyst according to 
methods in the art so far, unless cobalt II is used, or the cobalt II is 
preoxidized. Even then, it takes time to oxidize cobalt II to cobalt III 
ions, due to the small interface provided by bubbling the gas through the 
solution. 
In the case of the instant invention, this period of oxidation becomes 
considerably smaller because of the high interfacial surface area provided 
relative to liquid mass in the reaction chamber as atomized first 
droplets. In addition, the cobaltous ion can be pre-oxidized. 
As aforementioned, reactions, such as oxidations for example, according to 
this invention, are non-destructive oxidations, wherein the oxidation 
product is different than carbon monoxide, carbon dioxide, and a mixture 
thereof. Of course, small amounts of these compounds may be formed along 
with the oxidation product, which may be one product or a mixture of 
products. 
Examples include, but of course, are not limited to 
preparation of C.sub.5 -C.sub.8 aliphatic dibasic acids from the 
corresponding saturated cycloaliphatic hydrocarbons, such as for example 
preparation of adipic acid from cyclohexane; 
preparation of C.sub.5 -C.sub.8 aliphatic dibasic acids from the 
corresponding ketones, alcohols, and hydroperoxides of saturated 
cycloaliphatic hydrocarbons, such as for example preparation of adipic 
acid from cyclohexanone, cyclohexanol, and cyclohexylhydroperoxide; 
preparation of C.sub.5 -C.sub.8 cyclic ketones, alcohols, and 
hydroperoxides from the corresponding saturated cycloaliphatic 
hydrocarbons, such as for example preparation of cyclohexanone, 
cyclohexanol, and cyclohexylhydroperoxide from cyclohexane; and 
preparation of aromatic multi-acids from the corresponding multi-alkyl 
aromatic compounds, such as for example preparation of phthalic acid, 
isophthalic acid, and terephthalic acid from o-xylene, m-xylene and 
p-xylene, respectively. 
Regarding adipic acid, the preparation of which is especially suited to the 
methods and devices or apparatuses of this invention, general information 
may be found in a plethora of U.S. Patents, among other references. These, 
include, but are not limited to: 
U.S. Pat. Nos. 2,223,493; 2,589,648; 2,285,914; 3,231,608; 3,234,271; 
3,361,806; 3,390,174; 3,530,185; 3,649,685; 3,657,334; 3,957,876; 
3,987,100; 4,032,569; 4,105,856; 4,158,739 (glutaric acid); 4,263,453; 
4,331,608; 4,606,863; 4,902,827; 5,221,800; 5,321,157; and 5,463,119. 
Diacids (for example adipic acid, phthalic acid, isophthalic acid, 
terephthalic acid, and the like) or other suitable compounds may be 
reacted, according to well known to the art techniques, with a third 
reactant selected from a group consisting of a polyol, a polyamine, and a 
polyamide in a manner to form a polymer of a polyester, or a polyamide, or 
a (polyimide and/or polyamideimide), respectively. Preferably the polyol, 
the polyamine, and the polyamide are mainly a diol, a diamine, and a 
diamide, respectively, in order to avoid excessive cross-linking. The 
polymer resulting from this reaction may be spun by well known to the art 
techniques to form fibers. 
Examples demonstrating the operation of the instant invention have been 
given for illustration purposes only, and should not be construed as 
limiting the scope of this invention in any way. Although this invention 
has been mainly exemplified with oxidation process, any exothermic 
reaction between a liquid and a gas (under the conditions of the reaction) 
is includes in the realm of the instant invention. In addition it should 
be stressed that the preferred embodiments discussed in detail 
hereinabove, as well as any other embodiments encompassed within the 
limits of the instant invention, may be practiced individually, or in any 
combination thereof, according to common sense and/or expert opinion. 
Individual sections of the embodiments may also be practiced individually 
or in combination with other individual sections of embodiments or 
embodiments in their totality, according to the present invention. These 
combinations also lie within the realm of the present invention. 
Furthermore, any attempted explanations in the discussion are only 
speculative and are not intended to narrow the limits of this invention. 
In the different figures of the drawing, numerals differing by 100 
represent elements which are either substantially the same or perform the 
same function. Therefore, in the case that one element has been defined 
once in a certain embodiment, its re-definition in other embodiments 
illustrated in the figures by the same numerals or numerals differing by 
100 is not necessary, and it has been often omitted in the above 
description for purposes of brevity. 
The words "inlet line" and "outlet line" are used to signify lines adapted 
to transfer materials for the operation of the process, such as volatiles, 
reaction products, off-gases, and the like, for example. The words "input 
line" and "output line" have been used to signify lines adapted to 
transmit signals, which are mostly electrical, but they can also be 
hydraulic, pneumatic, optical, acoustic, and the like, for example. 
A diagonal arrow through an element denotes that the element is controlled 
though a line, preferably electrical, connected to the arrow. 
Internal condensation according to this invention is condensation of 
condensibles, which takes place within the pressurized system and before 
pressure drop to about atmospheric pressure. Inside condensation or inside 
internal condensation is condensation which takes place within the 
reaction chamber. 
Condensibles are substances having a boiling point higher than 15.degree. 
C., while non condensibles are substances that have a boiling point of 
15.degree. C. and lower. It should be understood that when referring to 
condensibles, it is meant "mostly condensibles" and when referring to 
non-condensibles it is meant "mostly non-condensibles", since small 
amounts of one kind will be mixed with the other kind at substantially all 
times. 
In cases where dilution or concentration of the droplets occurs as they 
travel from the atomizer to the sample collector, such dilution has to be 
taken into account in the calculation performed by the computerized 
controller by monitoring the sources of dilution or concentration and 
using well known to the art techniques. 
Response time between changing one variable or parameter and the result it 
brings about should also be taken into account, and the controller should 
be calibrated or programmed accordingly, by well known to the art 
techniques.