System and process for vacuum thermolysis treatment of liquid or gas products the disposal of which is detrimental to the environment

System for the treatment of liquid and gas products, the disposal of which is detrimental to the environment. The system has a single thermolysis reactor, a chamber for feeding the liquid or gas products to be treated, an intermediate disk for the passage of the gas to be treated, a thermolysis chamber in which the thermo-catalytic-decomposition takes place and a purification chamber in which are selectively retained for elimination chemical elements released by thermo-catalytic-decomposition.

BACKGROUND OF THE INVENTION 
The present invention concerns a system and process for vacuum thermolysis 
treatment of liquid or gas products, the disposal of which is detrimental 
to the environment. Products hazardous to the environment are 
conventionally either stored or incinerated; in the former case the 
potential hazard remains and can only become aggravated by possible 
corrosion of the packaging. In the latter case incineration temperatures 
are very high (in excess of 1,000.degree. C.) and cause rapid wear of the 
plant and therefore very high operating costs; what is more, the gaseous 
products of incineration are vented to the atmosphere without any form of 
control which makes it impossible to provide all the required guarantees 
of non-pollution of the environment. 
An object of the invention is to remedy these drawbacks by means of a 
system for processing liquid or gas products whereby at a moderate 
temperature (typically 500.degree. C. to 900.degree. C., depending on the 
products to be processed) sufficient decomposition for fixing and 
eliminating harmful components that can be detrimental to the environment 
can be achieved. 
SUMMARY OF THE INVENTION 
To this end the invention proposes vacuum thermolysis (i.e. thermolysis at 
a subatmospheric pressure, typically less than 500 mbars, for example 
around 300 mbars) and continuous purification of the products of 
decomposition at the outlet. The products of decomposition are preferably 
monitored continuously at the outlet in order to be either disposed of or 
recycled for another cycle of processing. 
Operation at temperatures below 1,000.degree. C. does not cause any marked 
wear of the processing system, so that its service life is extended and 
its operating cost is reduced. 
To be more precise, the invention proposes a system for processing liquids 
and gases whose disposal is detrimental to the environment characterized 
in that it includes in a single thermolysis reactor, a chamber into which 
liquid or gas products to be processed are fed, an intermediate disk 
allowing gases to be processed to pass through it, a thermolysis chamber 
in which thermo-catalytic decomposition takes place, and a purification 
chamber in which chemical elements released by the thermo-catalytic 
decomposition and to be eliminated are selectively retained. 
In accordance with preferred and possibly combinable features of the 
invention: 
the system includes a combustible gaseous medium feed pipe charging into 
the thermolysis chamber or at the upstream end thereof; 
the feed chamber is provided with a heating system for vaporizing the 
liquid part of products to be processed introduced into the chamber and 
heating the gaseous mixture to a set point temperature; 
the intermediate disk has orifices of calibrated size for regular transfer 
of gaseous products to the thermolysis chamber at a flow rate determined 
by the temperature and pressure conditions in the feed chamber and the 
pressure in the thermolysis chamber; 
the thermolysis chamber contains a thermo-catalytic system embodying 
electric elements connected to an electrical power supply and a 
thermo-catalytic material, the thermo-catalytic system being heated 
electrically to a temperature enabling catalytic decomposition of the gas 
mixture, the additional energy required for thermolytic decomposition of 
the products to be processed being obtained by catalytic decomposition of 
the air/oxygen-combustible gas mixture; 
the purification chamber includes a lining of reactive materials adapted to 
have the decomposed gases flow through them in order to selectively 
eliminate radicals to be eliminated; 
the reactive materials are installed in the form of removable cartridges 
for ease of manipulation and for regeneration after use; 
the system includes means for modulating the temperature of a catalytic 
mass contained in the thermolysis chamber; to maintain the vacuum in the 
thermolysis chamber, the system includes, connected to the outlet of the 
reactor, a pumping set preceded by washing means adapted to further purify 
and cool the gases to a temperature compatible with the pumping set; 
the hardness of the vacuum obtained in the thermolysis chamber is 
controlled in accordance with indications of a pressure gauge fixed to the 
reactor on the downstream side of the intermediate disk, by modulation of 
the flow rate of the pumping set; 
the thermolysis reactor is thermally insulated to reduce heat losses and 
the intermediate disk, a thermo-catalytic system contained in the 
thermolysis chamber, and active materials contained in the purification 
chamber are removably installed; and 
the system for processing liquids and gases whose disposal is detrimental 
to the environment includes, on the downstream side of the thermolysis 
reactor outlet, a gas analyzer controlling valves to route the processed 
gases either to a disposal path or to the entry of the thermolysis 
reactor. 
The invention also proposes a process of processing liquids and gases whose 
disposal is detrimental to the environment, in which the liquids and the 
gases are fed into a feed chamber in which the liquids are vaporized. The 
vaporized liquids and the gases are passed into a thermolysis chamber in 
which a vacuum is maintained in operation, in contact with a catalytic 
mass heated to a temperature adapted to catalyze thermolytic decomposition 
of the vaporized liquids and the gases, and the vaporized liquids and the 
gases are passed into a purification chamber containing elements adapted 
to selectively retain predetermined substances released by decomposition. 
In accordance with further preferred features of the invention: 
the gaseous products leaving the purification chamber are washed, tested 
for the presence of harmful substances, and then either disposed of or 
recycled into the feed chamber; 
the vacuum is controlled in operation by the flow rate at which the gaseous 
products are pumped at the exit from the purification chamber; and 
the gaseous products are pumped after washing and cooling them. 
In conformity with the conditions mentioned hereinabove, the system of the 
invention offers the following advantages: it can be applied to any 
quantity of liquid or gas, either by modifying the cross section of the 
reactor and the length of the thermolysis chamber or by connecting in 
parallel as many reactors as necessary. The system of the invention does 
not cause any contamination by the gases which are purged of harmful 
components, firstly in the purification chamber and secondly in the washer 
on the upstream side of the pumping set; and the installation and 
operating costs are low as compared with those of incinerator systems. 
Objects, features and advantages of the invention emerge from the following 
description given by way of non-limiting example with reference to the 
appended drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, liquids (and gases) to be processed reach a feed 
chamber 1 through an inlet A from barrels or from a storage tank 17 from 
which they are fed by a metering pump 18. As an alternative, the chamber 
can be fed by gravity. 
On the upstream side of the feed chamber the reactor has a conventional 
plant (not shown) for preventing escape of the products to the outside and 
ingress of air; to give a non-limiting example of such means, a barometric 
seal leg can prevent ingress of air and check valves can prevent escape of 
the liquid and the gases to the exterior. 
A combustible gas mixture (air/oxygen-combustible gas) is fed into the feed 
chamber 1 via an inlet B from a storage tank 19, passing through a 
pressure gauge/pressure regulator 20 whose flow rate is slaved to the flow 
rate of the metering pump 18. The feed chamber 1 has heating means, in 
this example an electric heater element 2 located against the wall, on the 
outside of the enclosure, to vaporize the liquid part of the products to 
be processed, to heat the resulting vapor and to mix the vapor with the 
air and/or the oxygen arriving at the inlet B. The electric current 
heating the heater element 2 is controlled (at 13) on the basis of 
measurement (at 12) of the vapor pressure of the vaporized liquid-air-gas 
mixture in the feed chamber 1, for which there is a fixed set point for 
each mixture processed. 
An intermediate disk 3 is fixed and sealed to the exit from the feed 
chamber 1. The intermediate disk 3 embodies holes 3A of calibrated size 
through which the gaseous mixture and the gaseous or vaporized products to 
be processed are transferred to a thermolysis chamber 4 including a 
thermoreactor or a thermo-catalytic system and to which the disk is fixed 
and sealed; the transfer flow rate is dependent on the temperature and the 
pressure in the feed chamber 1 and on the pressure in the thermolysis 
chamber 4. It is regulated by modifying these parameters and the flow rate 
of the metering pump 18. 
In an alternate embodiment of the invention the combustible gaseous mixture 
fed to the thermolysis chamber 4 is not via the inlet B discharging into 
the upstream end of the thermolysis chamber 4 but via a pipe or inlet B" 
(shown in dashed outline) discharging directly into the thermolysis 
chamber 4. 
The thermolysis chamber 4 communicates with and is sealed to a purification 
chamber 9 closed at its downstream end by an end wall 11 and adapted to 
purify the products of the thermolytic decomposition taking place in the 
thermolysis chamber 4. The products of the composition leave via an outlet 
C in the end wall 11. 
The chambers or other components 1, 4, 9 and 11 are assembled and sealed 
together by means of flanges and gaskets (or even by welding) to form a 
reactor. 
A vacuum (i.e. a subatmospheric pressure typically less than 800 mbars) is 
maintained at all times in the thermolysis chamber 4 and the purification 
chamber 9, the absolute pressure in the thermolysis chamber 4 varying with 
the nature of the products to be processed. This pressure is 300 mbars, 
for example. 
The products of decomposition enter a washing column or "scrubber" 23 in 
which they are washed and cooled by vigorously sprayed water. The washing 
water is taken off by a pump 24 whose flow rate is slaved to that of a 
sprayer pump 26 spraying the water into the column 23. The flow rate of 
the sprayer pump 26 depends on the volume and the temperature of the 
decomposition gases entering the column 23. The washing water pumped from 
the outlet at the bottom of the column 23 by the pump 24 is fed first to a 
settling and cooling installation 25 and then to a neutralization 
installation 27 into which a neutralizing solution, such as a soda 
solution, for example, is fed as required. This solution is taken from a 
tank 21 by a metering pump 22 whose flow rate is controlled by the output 
of a monitoring device 27A such as a pH meter, for example. In the example 
shown here, the spray water pumped by the pump 26 is taken from the upper 
part of the tank 27. 
The washed and cooled gases are aspirated from the outlet at the top of the 
column 23 by a pumping set 28 (provided with vacuum pumps and heat 
exchangers, for example) which maintain the volumes of the thermolysis 
chamber, purification chamber and washer column at the required vacuum 
(typically 300 mbars--see above). The operation of the pumping set 28 and 
therefore the hardness of the vacuum in the installation are controlled in 
this example in accordance with the pressure in the purification chamber 9 
as measured by a sensor 16. 
Before they enter the pumping set 28 the gases flow through a gas analyzer 
30 which, depending on the results, and by operating valves 31 and 32 on 
the downstream side of the pumping set 28, directs the gases either into a 
chimney 29 or to a second input B' of the feed chamber 1 so that they are 
recycled and processed again. 
The washing column has a two-fold function in that, firstly, it continues 
the process of purification and, secondly, it cools the gas to a 
temperature acceptable for the pumping set 28. 
FIG. 2 shows by way of non-limiting illustrative example only an industrial 
implementation of the thermolysis reactor combining the feed chamber 1, 
thermolysis chamber 4 and purification chamber 9. The reactor is shown 
horizontal here, but it can operate in the same manner if vertical. The 
position can be chosen according to local installation conditions. 
The liquids arrive at the inlet A either by gravity feed or pumped by a 
metering pump. The air/oxygen-combustible gas mixture arrives at the inlet 
B. The gases to be processed or recycled after passing through the pumping 
set 28 arrive at the inlet B'. The feed chamber 1 is heated by the 
electric elements 2 in order to vaporize the liquids to be processed and 
to heat the gas mixture. Heating is controlled by the electric power 
regulator 13 according to the pressure as measured by the pressure gauge 
12. 
The holes in the intermediate disk 3 through which the hot gas mixture 
flows from the feed chamber 1 into the thermolysis chamber 4 are 
distributed along circumferential lines and have a flow cross section 
chosen to guarantee the required gas mixture flow rate in accordance with 
the variable parameters: upstream pressure and temperature (at 1), 
downstream pressure (at 4). The design of the intermediate disk 3 depends 
on the physical and chemical characteristics of the products to be 
processed. Mounting the intermediate disk 3 between respective flanges of 
the feed and thermolysis chambers 1 and 4 makes it easy to replace the 
intermediate disk 3 when the products are changed. 
In components 5, 6 and 7 of the thermoreactor (or thermolyzer) described 
below is where the thermo-catalytic decomposition reaction takes place: a 
porous catalytic mass 5 in which a gas mixture and the products to be 
processed circulate, electric heater elements, in this example in the form 
of radiant electric tubes 6 passing longitudinally through the catalytic 
mass to heat the latter to the temperature of the decomposition reaction 
and to supply the further energy needed to dissociate the molecules of the 
gas by means of the porous mass 5, and a tube 7 on which the catalytic 
mass 5 is mounted and which is plugged (here at its upstream end) to 
prevent the flow of gas outside the porous mass 5. A thermocouple 15 with 
a temperature outlet 8 gives an indication of temperature for controlling 
the chemical dynamics of decomposition by regulation of the input of 
electrical energy by means of a power regulator 14. The thermoreactor is 
removably housed in a thermolysis enclosure 4A and sealed thereto in order 
to prevent the gases from circumventing the porous mass 5 by flowing along 
the thermolysis enclosure 4A. 
In FIG. 2 the radiant tubes 6 are concentric (there are three tubes nested 
one within the other) and are connected to an electrical power supply, 
i.e. the regulator 14, by spacers at their upstream and downstream ends 
which provide both the electrical connection and mechanical stiffness. The 
tubes therefore conjointly form a single heater element heating the porous 
mass 5 homogeneously. 
The radiant tubes 6 of the thermolysis chamber 4 are filled with materials 
constituting the porous mass 5, so that the gas flow is sufficiently slow 
and turbulent to promote heat exchange; the nature of the filling 
material(s) is determined to suit the stability characteristics of the 
product, in order to catalyze its decomposition. 
FIG. 3 shows an alternate design of the thermoreactor, in which the radiant 
tubes are replaced by a heater element 6' embedded in the porous catalytic 
mass 5 in a helix around the central tube 7. It heats the porous catalytic 
mass 5 to the temperature required to instigate the decomposition 
reactions. Items in FIG. 3 similar to items in FIG. 2 are identified by 
the same reference numbers. The porous mass 5 in this embodiment is 
advantageously confined in a porous mass enclosure (not shown). 
The energy required for thermo-catalytic decomposition of the products to 
be processed is introduced by raising the temperature of the gas mixture 
in the feed chamber 1, by raising the temperature of the radiant tubes and 
the electric elements and by the catalytic decomposition of the 
air/oxygen-combustible gas mixture in the material of the thermo-catalytic 
system. 
The reaction dynamics of decomposition in the thermolyzer are controlled by 
regulating the electrical heating on the basis of data from thermocouples 
installed in the reactor and by the use of conventional electric current 
control systems, for example thyristor-based systems. 
An enclosure 9A of the purification chamber 9 contains cartridges 10 (in 
this example two consecutive cartridges) of active elements whose function 
is to retain by physical and chemical means the chemical radicals 
(especially halogens) resulting from thermolytic decomposition and to be 
eliminated. These active elements depend on the products to be processed. 
The cartridges 10 occupy all of the interior cross section of the enclosure 
9A; they are removable and are changed when purification is no longer 
sufficient, as indicated by the gas analyzer 30. They can then be 
regenerated and replaced. The successive cartridges 10 can be of different 
kinds to fix different chemical radicals. Purification can therefore be 
selective and progressive. The pressure sensor 16 on the downstream side 
of the cartridges 10 indicates the hardness of the vacuum so that the 
pressure can be set to the required value by modifying the flow rate of 
the pumping set 28. The decomposed and purified gases leave the reactor 
via the outlet C in the end wall 11. 
The catalytic reactor is thermally insulated over all of its length between 
inlet A and outlet C to minimize heat losses. 
To process "1-1-dichloroethane" arriving at a mean flow rate of 1 kg/s, for 
example, a disk has a hole in it with a cross section of 0.35 cm.sup.2. 
The catalytic mass has a length of 1.2 m and the cross section of the gas 
flow passage is 400 cm.sup.2. The mass is based on platinum oxide. The 
purification cartridges are based on dolomite to fix chlorine compounds 
released during catalytic decomposition. 
In this application the combustible mixture is fed directly into the 
thermolysis chamber in line with the catalyzer via the inlet or pipe B'. 
It is 960 g/s of oxygen and 540 g/s of propane (C.sub.3 H.sub.8). 
The target pressure in the feed chamber 1 is 3 bars and the set point 
temperature is 480K. 
The vacuum in the thermolysis chamber 4 is 0.6 bar and the porous mass 5 is 
held at a temperature in the order of 1,000K. 
It goes without saying that the above description has been given by way of 
non-limiting example only and that many variants can be proposed by the 
person skilled in the art without departing from the scope of the 
invention.