IMPROVEMENTS IN THE MANUFACTURE OF GAS APPLICABLE FOR HEATING PURPOSES
Year: 1884

page_text: 1, MICHEL CAREN, Engineer, of Brussels in the Kingdom of Belgium do hereby
declare the nature of my said invention for "IMPROVEMENTS IN THE MANUFACTURE
OF GAS APPLICABLE FOR HEATING PURPOSES" and in what manner. the same is
to be performed, to be particularly described and ascertained in and by tho
following statement:-
Since the utilisation of the carbonic oxide contained in the waste gases of blast
furnaces, to heat the blast and warm the generators, efforts have been made to
produce monoxide of carbon directly from cheap inferior coal, in the hope of thus
effecting a saving in the cost of fuel. A saving can be realized under certain
conditions; but at high temperatures, the process gives results far below those
which were expected from it, and the use of carbonic oxide gas, as usually
produced, is practically impossible in blast furnaces for direct heating. The
carbonic oxide gas produced in the blast furnaces does not give up even one half
of the caloric absorbed by its production. This arises from the fact that the
carbonic oxide gas as actually produced, is from its very origin too much diluted.
It contains the nitrogen of the air which has served to convert into carbonic acid
gas the half of the carbon it contains: Now as 75 kilos of carbon require 200 kilos
of oxygen to produce 275 kilos of carbonic acid, and these 275 kilos of carbonic
acid taking up 75 kilos of carbon, produce 350 kilos of carbonic oxide, but mixed
with the nitrogen corresponding to 200 kilos of oxygen say 673 kilos, it follows
that 1023 kilos of carbonic oxide so produced will contain 673 kilos of nitrogen.
This fatal defect becomes at high temperaturo much more costly than if a coal had
been burnt containing not more than 35 per cent of carbon. The same consideration
applies to the free hydrogen contained in the fuel. It may therefore easily be seen
what serious drawbacks result from this dilution.
Taking equal quantities for the purpose of comparison, we find that the
following combustibles, burnt with the theoretical quantity of air, produce the
following results (for 1 kilo).
1. Good coke produces 6264 calories yielding 2244.

page_text: Good coke 1600 kilos.
Good coal 1377 kilos.
Diluted carbonic oxide gas 11286 kilos.
The enormous bulk of the last named combustible must obviously occasion
considerable losses of heat but neglecting these, let us consider the practical result.
The temperature of 2244 degrees which the coke yields is insufficient for blast
furnaces; the air for combustion must be heated from to 700 degrees or to
800 degrees, and we then obtain the following results.
Coke with hot blast temperature obtained 2835 degrees.
Good coal
"
"
"
2950
Diluted carbonic oxide gas hot blast, temperature obtained 2030 degrees..
So that the dilute carbonic oxido gas even with hot blast, does not produce even
the insufficient temperature of 2244 degrees which is yielded by coke burnt with
cold blast. If to this be added the consideration that use of a weight of combustible,
eight or nine times greater, increases proportionately the various losses of heat, it
becomes obvious why the use of carbonic oxide gas as hitherto applied has often
proved unsatisfactory and why it is inapplicable to certain metallurgical and
heating-purposes. Nevertheless-by means of the use of low priced fuel the 1
ordinary dilute carbonic oxide gas proves-economical for certain purposes at lower
temperatures.
Assuming however that the carbonic oxide undiluted with the 65 per cent or
upwards of incombustible gas is employed in the pure state, the results of the
combustions-would-compare thus:
1 kilo, diluted gas 800 calories; 1-1-286-kilos-required for ten million calories
produce 1730 degrees or with hot air 2030 degrees; 1 kilo pure gas 2926-calories;
3420 kilos required for ten million calories produce 2005 degrees (hot blast
unnecessary) Pure-carbonic-oxide therefore with cold blast gives a higher
temperature than coke with hot blast; and is far inore efficient than the diluted
gas used with hot blast. The economic importance of this use of pure carbonic
oxide gas is very great, thus the consumption of gas in a large blast furnaco
burning 100 tons of coke per diem at say 16 francs amounting to 1600 francs, it is
calculated would not exceed 200 tons costing 2 francs per ton, say 400 francs per
diem, an economy of 1200 francs. The advantage is exceptionally great in this case
but in other casos even where the gas is burned at lower temperatures the saving
remains very great.
It is noteworthy that the heat evolved by the combustion of gas made by my
system is approximately that evolved by pure hydrogen. My new process of
beating has therefore for its object the production, not of pure carbonic oxide but
of a mixture of the same with pure hydrogen.
Before describing the process it is necessary to make a few preliminary
explanations-
Carbonic acid contains by weight-
75 carbon
200 oxygen
275 say for 1000 kilos
carbon 272.7 kilos.
oxygen 727.3
"
Taking the cost of these 1000 kilos carbonic acid at francs 1.25 the 272-7 kilos
of carbon would cost francs 4.58. That is to say that 1000 kilos of pure carbon
would cost less than the price of a ton of inferior (Belgian) coal.
For producing pure carbonic oxide, coal slack at say 6 francs the ton is
available-It contains say:

page_text: These 780 kilos of carbon and 48 kilos of hydrogen are to be combined with
2860 kilos carbonic acid containing likewise 780 kilos of carbon. The operation is.
described hereafter in detail.
A gas is thus obtained composed of 2860 kilos carbonic acid and 780 kilos of
3640 kilos pure carbonic oxide add of
carbon
=
It should be noted at this point, that having the carbonic acid free from any
products of combustion, it would cost little beyond the expense of the chemicals
employed to absorb the ammonia by well known processes. This supplementary
profit which is sometimes considerable is not reckoned in the calculations. Another
economy however forms an integral part of our process. In the usual process of
preparing carbonic oxide gas, there is free access of air, whilst by this process the
operation takes place in a closed vessel at the exact temperature necessary.
I therefore obtain in addition to the ammonia aforesaid the products which the
1100 kilos of coal will yield, the value of which may be estimated at 4.50 francs ;
consequently the cost of the 3688 kilos is reduced to say 6.70 francs. This gives a
cost price of 1.81 francs per 1000 kilos gas or say with 19 francs extras two francs
in round numbers.
At this price, it is obvious that the use of the gas will be very advantageous for
heating at highor temperatures, since production of ten million calories requires.
Good coke 1600 kilos at 16 francs = 25.60
Good coal 1377
New gas
14
= 19.25
"
"2
"
3420
2
= 0.84
"
"
"
or a saving of 74 per cent on the coke and 65 per cent on the coal.
It is to be remarked morcover that there remains to the credit of the gas process
in addition, the cost of heating the blast, which is unnecessary with the gas fuel,
for instance to burn the above named 1600 kilos of coko, 12538 cubic metres of air
are requisite, the heating of which to 800 will require about 3 million calorios.
Now for the production of 3420 kilos of gas to replace the 1600 kilos of coke
900 calories per kilo must have been consumed say in all 3,100,000 calories.
Nevertheless the amount has been put on the safe side the production of 570 cubic
metres of gas requiring 1,677,000 calories.
It should be stated here once for all that the hercin contained estimates of cost,
heating power and other details are calculated on their theoretical values, neglecting
errors caused by variations of material, losses of heat et cetera. It is however
obvious that this should give results more favourable to the solid fuels because
the results of the combustion of a pure gas approach much more nearly to tho
theoretical calculations than do those of fuels less pure and more difficult to burn.
Comparing the pure with the impure heating gas, the cost prices for equal
quantities of 3088 kilos of combustible gas the ordinary gas requires.
2200 kilos carbon at 6 francs = 13.20 francs
1820 1000 bil n
9.7 GAS

page_text: Taking a temperature of 900 degrees the minimum temperature at which the air
can be regulated for the impure gas. The impure gas even with hot blast gives a
temperature of 2030 degrees, the pure gas with cold blast 2905 degrees.
Therefore 2905 - 900 = 2005 useful effect.
2030900 = 1130 "
»
This indicates a saving of 48 per cent, in short the new gas is beyond comparison
superior to the usual impure carbonic oxide gas as fuel even more so than to good
coke or to coal.
•
The pure gas applied to gas motors would give valuable results as may easily be
seen from the following calculations: lighting gas requires for its manufacture
very good coal, and it leaves a large residue of coke for which a market has to be
found. To produce the pure gas however at say 2 francs the 1000 kilos inferior
coal is available, leaving a residue of nothing but ashes. In order however to
obtain the pure gas at the above price of two francs, it is necessary to recover the
gas burnt in the cylinders of the motors which limits its use to the place of
production. For factories requiring several motors placed at a distance from each
other, the results would work out as follows:
1000 cubic metres of lighting gas at 5 centimes the cubic metres cost francs 50.00.
3000 kilos of carbonic oxide gas replace the same at 2 francs 6.00 at 1 cubic
-metro_of_gas_per_horse power-per-hour, the horse power per hour would cost
5 centimes, and with carbonic oxide gas-0-6-centimes that is to say less per-horso
power than an excellent steam engine consuming 1 kilo of coal per hour costing
say 1 centime. It is to be noted that for a particular and continuous operation,
theoretically only one half of the carbonic acid contained in the products of
-combustion is required thus.:.
A portion of this surplus is of course required to replace leakages during the
process, and the rest may be utilised as may be found desirable.
The price of 1.25 francs the 1000 kilos of CO, which forms the basis of the
above calculation is a safe one, that is to say not too low. The carbonic acid is
obtained by the combustion of the carbonic oxide gas; the products are of two
kinds firstly those produced by the ordinary combustion. These contain per 1000
cubic metres of product-
CO, 275 kilos = 139 cubic metres
Cof-336
33
=
265
"
"
for 1000 CO₂ — 344
cubic metres
N
-
656
Secondly, the products of combustion of the blast furnaces part of which produced
by the deoxidisation of the ores does not contain nitrogen
1000 cubic metres of these usually contain
CO₂- 1914 kilos
N-1334
"J
966 cubic metres
-
- 1052
"
">
per 1000 CO, 478-8
cubic metres N 521.2
To separate these two gases I make use of a continuous current of water into
which the gases are forced under pressure: let the speed of the water be. 1 metre
per second; the co-efficient of solubility of the two mixed gases being respectively
CO. = 1 185 in 1 volume of water
N = 0.016
"
ditto
or expressed per cubic metre of water and per second with the usual products of
(1) CO, 1.185 x 344 = 407 × 1980 = 0 kilo 865
(2) N 0.016 x 658 = 10 × 1268 = 0 kilo 0.13
10
5

page_text: per second
CO, 1-185 x 478-8 = 507 x 1980 = 1 kilo 122
N 0.016 x 521-2 = 84 x 1268 = 0
0.10
It results from this difference in solubility of the two gases that the recovered
carbonic acid may be considered as pure to within 1 per cent, an insignificant
amount of impurity: it is also obvious that such cubic metro of water will yield
carbonic acid.
Ordinary products 3600 × 0.865 = 3114 kilos per hour = 74000 kilos por
24 hours.
Blast furnace products 3600 × 1,122 = 4040 kilos per hour
24 hours.
=
97000 kilos per
In order to obtain in the one case 344 cubic metres x 1.98 = CO, - 681 kilos,
and in the other case 478; 7 × 1.98 = CO₂ — 948 kilos it is necessary to compress
to 1 atmosphere 1000 metres of gas.
-
To compress and absorb in water 1 cubic metro at 1 atmosphere requires in
round numbers 7200 kilo-grammetres per cubic metre or for 1000 cubic metres say
28 horse power for one hour, say 28 kilos of coal at 12 fraucs, or 36 centimes :
then for
Ordinary products
Blast furnace products
1000 kilos CO, will cost francs 0.50
"
33
"
">
"
"
0.35
Even doubling these figures the cost only comes to 1 franc and 0.70 franc
respectively per 1000 kilos CO, it may therefore be assumed that the actual cost of
the carbonic acid will be less than 1.25 francs the 1000 kilos at which it has been
reckoned.
At first sight it might appear that having to deal with a gaseous combustible
would involve tho manipulation of a larger bulk of gas-this however is not the
case owing to the capacity of carbonic oxide gas for giving great heat with one half
its volume of oxygen. Thus to burn the following quantities of fuel giving equal
quantities of heat. (1) 1600 kilos of coke require 12,500 cubic metres of cold
air or 30,000 cubic metres heated to from 750 degrees to 800 degrees giving
17,000 kilos of combustion products. (2) 3420 kilos of gas of my manufacture
require 7636 cubic metres only of cold air; the products of combustion amount to
13450 kilos. Now as this gas weighs rather more than 1 kilo the cubic metre, we
3 have to introduce into the furnace at most
-
gas 3420
air 7636
11056 cubic metres.
Applying the same considerations to blast furnaces the advantage becomes still
more marked in favor of the gas firing.
Recapitulating the advantages of my process they may be stated briefly as
follows.
1. Great economy in all heating arrangements and especially in combustion at
high temperatures.
2. Recovery of ammonia and distillation products at least as well if not better
than in gas works.
3. Recovery of the ammonia from the products of combustion without other
expense than that of the chloride of calcium: the carbonic acid amply repaying the
other expenses.
4. Suppression of the superheating apparatuses which besides needing almost
constant repair greatly exceed in first cost the outlay necessary for one of my
carbonic oxide generators and apparatus for carbonic acid extraction in the cold.
5. Economy in working small and medium sized gas engines even as compared
with the best large high pressure steam engines.
6. Production of very high temperatures for fusing platinum and similar
operations same results as with pure hydrogen but giving immense economy
in price of material.

page_text: 7. Lastly the use of carbonic acid renders almost all kinds of bituminous schists,
peat et cetera available. The current of gas assists the distillation of the volatile
products, and as the carbonic oxide together with hydrogen escapes from our
furnace almost cold, the condensation of the volatile products is much facilitated.
Gas produced from schists et cetera will be just as rich as that from the best
materials, and will consequently be available for even the highest temperatures.
Before proceeding to the description of the drawing it is requisite to add a few
remarks upon the licating of blast furnaces without in the first instance reckoning
the coke really burnt for heating alone, let us consider the effects of the coke burnt
the products of combustion of which will in the state of carbonic oxide deprive the
oxide of iron Fe, O, of its oxygen. The composition by weight of this peroxide is
oveetly 1000
to produc
KITOS OF CUT DONA
the deoxidation of the mineral forming 825 kilos 00% But this is not all: this
carbonic acid traverses-fresh-layers of carbon and is reconverted into carbonic oxide,
re-absorbing as much carbon again as it previously contained, thus-1-12-5 x 2 = 225
kilos to form again 1050 kilos of carbonic oxide. Hence the deoxidation of
1000 kilos of mineral have taken 450 kilos of carbon instead of 225 kilos, or
50 per cent too much. The same process occurs with the excess of carbon
employed to give the necessary temperature, it must first be converted into
carbonic acid, then this carbonic acid re-absorbs uselessly as much carbon again
to reconvert into carbonic oxide. From this point of view alone the gas fuel gives
an economy of 50 per cent whatever be the actual consumption in addition to the
considerable economy in the cost price of gas as composed with coke, as has been
already explained.
Referring to the annexed drawings
Sheet 1 Fig. 1 is a vertical section of the apparatus. The vertical furnace or
generator is constructed of 3 pieces. AAA, the portion most exposed to heat is
of fire clay, the portion B B B exposed to a less heat is of cast iron as well as the
lower part C C designed to hold the ashes and scoriae. The carbonic acid is con-
ducted by tube E into the scorine and deprives them of the greater portion of their
heat, after which it traverses from below upwards the hottest portion of the furnace
wherein it is converted in contact with the fuel into carbonic oxide accompanied by
the hydrogen or volatile hydro-carbons, by vapour of water and by ammonia.
Arriving at the part B B B which is only moderately heated by the products of
the combustion, which have heated the exterior of the part A A A, the less volatile
portions of the tar condense upon the fuel contained in the part B B B and thero
pass out by the pipe H besides the gas and ammoniacal vapours, only the more
volatile distillates which may be condensed, together with the ammoniacal water
by the usual means.
The stoke hole I closes hermetically with a cover and ordinary clay joint; it
need only be opened when B B B is half empty.

page_text: The pipe H might equally well be connected with the top end of B. It has been
demonstrated that at high temperatures the products of combustion of the gas
retain an amount of heat sufficient to convert carbonic acid into carbonic oxide.
They return to the generator by the flue K passing in the direction of the arrows
and pass out considerably cooled by a Blue M having two or more branches. They
may also serve to evaporate the ammoniacal salts already alluded to. They are
then caused to pass through a solution of chloride of calcium, to absorb the
carbonate of ammonia which they contain.
Finally the pure carbonic acid is oxtracted for the purpose of producing carbonic
oxide and hydrogen in an apparatus described further on. Should these products
of combustion prove insufficient to give the heat necessary for the production of
carbonic oxide, and especially in the case of heating at low temperatures, the
deficiency may be supplied as already explained by burning the gas itself, the
products of the said combustion arriving also by the flue K. The receptacle O
which is discharged from time to time can contain a considerable quantity of
cinders etcetera, and it should nover be completely emptied, because these serve to
close the aperture at the lower part of CC. To secure an efficient seal, tho
cinders etcetera may be quenched with water. By closing the delivery fluo
for the carbonic acid the whole apparatus may be utilized for the production of
lighting gas.
Extraction of pure carbonic acid from the products of combustion.
Reference has already been made to the conditions involved in the extraction of
carbonic acid by dissolving it in water under an effective pressure of 1 atmosphero
without restricting the process to any one method of effecting this, the drawings
annexed show the details of an apparatus which effects an absolutely continuous
solution and delivery of pure carbonic acid. Sheet II Fig. 1 represents plan of
a water conduit A A A of diameter and length proportionate to the volume of
carbonic acid to be absorbed. In this conduit the water is kept in continuous
motion at a speed proportionate to the amount of gas to be absorbed. At each end
of its two branches the tube A A rises vertically at A¹ and A¹ to a height of at
least 11 metres so as always to maintain in the horizontal portion A a minimum
pressure of 1 atmosphere. As is shewn in the vertical section X X Fig. 3 the
upper ends of A¹ and of A" are connected into a cistern B B which completes
the communication between the two branches A' and A. Tho water containing CO₂
dissolved under pressure, rises at A¹ gradually giving off the gas until at B the rest
of the carbonic acid is liberated, the water being at that point only subject to
atmospheric pressure. The gas is collected by the tubulure C. The water having
yielded up its carbonic acid descends again by the tube A" to return into the
circulation of the horizontal tube A A A
The speed and the continuity of the current are assured 1st by the injection
at D in the direction of the current, of the mixture of carbonic acid and of nitrogen
which it is desired to separate. 2nd. by a screw H which is caused to revolve
according to the speed of current desired, and this arrangement serves also to mix
the water and gases more intimately together. The separation of the gases is
effected thus: the insoluble nitrogen collects at the upper part of the vertical
tube O, open widely in the direction C C. The nitrogen rushes into this tube full
of water and escapes into the air through it. The cistern B and the container C¹
should be of sufficient capacity to hold all the water displaced by the gases without
sensibly altering the pressure in the tube A A. A.
It must also be noted that in all heating arrangements and especially in those at
low temperatures, the aspiration of the products of combustion instead of relying
on the chimney draught is a great advantage, so much so that many engineers
recommend it without reference to the utilisation of the products with the object
of economising fuel. As in practice about 10 cubic metres of air are consumed
per kilo of coal burnt, and in order to secure a good draught the products of
combustion should reach the chimney at a temperature of 400 degrees or there-

page_text: abouts it is thereforo a loss of at least 1400 calories for each kilo of coal burnt,
say of the heat produced if not more. My process utilizes the bulk of this
waste heat without any expense whatever, because the extraction of the carbonic
acid covers all costs and leaves as net profit (except cost of chemicals), the ammonia
extracted from these products of combustion.
To recapitulate; the invention consists essentially in
(a) The production of pure carbonic oxide, instead of carbonic oxide hitherto in
use mixed with say 67 per cent of nitrogen.
(b) The use of pure carbonic acid gas for producing this puro carbonic oxide.
(c) The production of this pure carbonic acid gas from the products of combus-
tion of already consumed gas and separated from the nitrogen which is found in
these products by a process and apparatus described in the Specification and based
upon the difference in solubility of the component gases.
(d.) The conversion of the pure carbonic acid gas into carbonic oxide by passing
over carbon contained in a retort which is heated externally: if coke or wood
charcoal be used, the carbonic oxide obtained would be absolutely pure; but if
the retort be filled with coal or tignite, the carbonic oxide will be mixed with
hydrogen, and all the distillation products of the coal will be obtained as bye
products.
-In-soine metallurgical operations it is possible to obtain pure carbonic acid gas
-free-from-nitrogon. It is obviously unnecessary-to-treat this gas for the separation
of nitrogen.
In order to produce gas of this kind, instead of making use of the ordinary blast
furnace the operation is divisible in two, namely―
(a) preparation, reduction of the mineral, decomposition of the carbonate of lime
in a heated space (see Sheet III A AA A¹ and through which mixed carbonic
oxide (pure) and hydrogen is blown at II.
(b) fusion properly so called in the hearth. CC¹ of tho mineral, well prepared by
carbonic oxide burned with access of air and introduced together by one or more.
pipes T at N. In the first operation-the-carbonic oxide gas is transformed into
carbonic acid by reducing the oxide of iron, mixes with carbonic acid gas set free-
from the limestone, and passes off above through cast iron pipes, into the receiver L
where the watery vapour is condensed, then through the retort F filled with carbon.
In this retort the gas is reconverted into carbonic oxide which escapes at the top
together with the ammonia and distillation products; these latter collect at X whilst
the gaseous carbonic oxide continues its course and passes into the reservoir Z.
From this the gas is drawn in order to be burnt at N or to be conducted
to H.
The combustion products obtained in the furnace C C₁ are set free without
meeting any obstacle, pass along P P P P P, heat the reducing retort for the
mineral A A A' A' then the retort filled with carbon F, and escape to the chimney
at K. They can also be regenerated as pure carbonic acid first, and then carbonic
oxide according to this process. If the heating is insufficient gas may be burnt
at S to increase it.
Gauges M M are attached to indicate pressures et cetera. By this process
whether the whole process in general be adopted, or it be only applied partially
to the making of pig iron, all the distillation products of the coal are recoverablo
as set forth.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. The extraction of practically pure carbonic acid from the products of combus-
tion of the gas in a manner, substantially as described.
2. The conversion of the pure carbonic acid gas into carbonic oxide gas mixed
with hydrogen by passing it through a column of fuel contained in a vertical
generator heated externally to a sufficient temperature.

page_text: 3. The improved process of manufacturing gaseous fuel specially adapted for
operations at a high temperature together with the arrangements for condensing
the products of distillation of the carbonaceous matter and utilization of the
products of combustion substantially as herein described and set forth.