US2204003A - Production of water gas - Google Patents

Description

JJune 1l', 19410. R, RUMMEL "PRODUCTION oF WATER @As 2 Sheets-Sheet 1 l'iled April 9, v1958 a MU SMN June11, 1940. R, HUMMEL y 2,204,003

rnonucwrou oF wmn @As Filed Aprilv 9, 19:59 2 sheets-sheet 2 Patented June ll, 1940 PATENT OFFICE PRODUCTION F WATER GAS Roman Rummel, Ruhland, Germany,assignor, by

mesne assignments,

to Kappers Company,

Pittsburgh, Pa., a corporation of Delaware Application April 9, 1938, Serial No. 201,193

In Germany 7 Claims.

The present invention relates to the production of water gas or the like from solid fuels especially from bituminous coals, by using a highly heated mixture of steam and gases, preferably a part of the water gas produced, for heating the fuel up to the temperature of the water gas reactlon,said mixture serving as a heat carrier and I shallterm the said mixture in this description as heat carrier.

In order to produce water gas or the like from fbituminous fuels, a shaft furnace is employed which is traversed by the fuel from the top downwards. In various zones of the shaft. there have been provided means for introducing gases into the shaft and/orfor withdrawing gases from the shaft. Contrivances for heating up the gases, for instance regenerators, such as of the Cowpersystem well-known for heating-up the air of blast furnaces, are connected with the shaft. The heat carrier, i. e., the mixture of gas and steam, heated-up in these -contrivances, is in-` troduced into the shaft and extracted lfrom thel shaft in Vsuch a manner that the fuel on its way from the top downwards is brought into `contact with the hot heat carrier and is heated thereby gradually, reaching finally that temperature at which the steam reacts with the carbon of' the fuel with the formation of a mixture of carbonio acid, carbon monoxide, hydrogen and other constituents, such mixture being the so-called water gas.

When the bituminous fuel, for instance brown coal, lignite, shale or any other suitable coal, is charged into the shaft, the fuel is first vdried and degasifled in the upper part of the shaft, analogously to the well-known coal distillationv process. As soon as the fuel is heated to a sufliciently high temperature, the reaction of carbon with steam begins. The upper part ofthe shaft is, there- 40 fore, called by me the degasication zone and the lower part is termed hereinafter as gasifylng zone. The exact position of both these zones, whichunder certain circumstances are not sharply separated from each other, especially when treating reactive fuels, depends on the working conditions, in particular on the temperature of the heat carrier and the position of the inlets April 10, 1937 duce the water gas or the` like in continuous operation. If regenerators areemployed for heating-up the heat carrier, it issof advantage to provide several of such regenerators and 'to connect them in alternation, by means' of suit- 5 able shut-off and reversing valves, with the gas producer shaft in such a manner -that continuously a hot heat carrier from one regenerator or from several regenerators is introduced into the gas producer shaft.

In many instances, it is desirous of obtaining the water gas, free from hydrocarbons which are formed during the degasiiication of the bituminous fuels. For the synthesis `of valuable hydrocarbons from hydrogen and carbon monoxide 15 in the presence of certain catalysts, containing nickel or cobalt or other substances, it is a requirement, for instance, that the gas be one which is free from such hydrocarbons which, similar to the tarry constituents formed at the 20 degasication of bituminous fuels, tend to deposit on the surface of the catalysts, which will thereby become ineffective or at least less effective.

In order to produce by means of a heat carrier a water gas; free from all such hydrocarbons, 25 by means of a heat carrier a part of theheat carrier and of the newly developed water gas may be extracted from the gasifying zone of the gas producer shaft at such a point where the fuel is already fully degasified, i. e., practically free 30 from bituminous matter or where the fuel is degasifled at least to such a degree that the remaining'hydrocarbons decompose at the temperatures existing in the gas producer. The remaining part of the heat carrier and of the fresh- 35 ly made water gas, which is not withdrawn from the gasifying zone of the gas producer, flows upwards through the degasiiication zone of the gas producer and gives olf its heat to the fuel which is thus distilled. 40

A considerable disadvantage of the'before dex scribed process consists in that the heating-up of the fuel to the water gas reaction temperature and the gasifying of same takes place in one single` zone. Thereby. the temperature of the 45 heat carrier after entering the gasifylng zone, drops very quickly and the water gas reaction takes place slowly. Moreover, the fuel undergoes a secondary degasification by `its being heated in the gasifying zone, whereby alsofthe hydro- 50 carbons are withdrawn into the useful gas, notwithstanding the fact that the water gas necessary for the synthesis process should, however, be free from all tarry hydrocarbons, if possible.

An essential object of my present invention is to provide such improvements of the described method of water gas production which will overcome the before mentioned disadvantages and attain other improvements as hereinafter more particularly set forth and described.

Principally, my invention consists in introducing two separate heat carrier'streams into the gas producer, of which the one stream mainly degasies and preheats the fuels, and other stream gasifies, wholly or partly, the degasifled and preheated fuel in the presence of steam. 'I'he heat carrier in this manner, enters the degasification and the gasifying zones respectively preferably at an equal temperature and is led into the gasifying zone in co-current and into the degasication zone in counter-current, to the direction of movement of the fuel moving within the gas producer shaft from the top downwards. In this manner, the fuel reaches the gasifying zone at approximately the same temperature as the heat carrier. 'I'he sensible heat of the heat carrier and of the fuel is utilized for the formation of water gas. Since the fuel enters the gasifying zone in hot condition and is subjected to no further temperature rise, after it-reaches the water gas reacticn'zone then no secondary degasification of the fuel occurs, whereby no hydrocarbons enter the synthesis gas, as occurs with the old process in which the heat carrier when hottest first meets the hottest water gas reaction zone, instead of as here wherein the heat carrier when hottest first meets the fuel in advance of its entering the water gas reaction zone, thus giving up its highest specific heat in preheating the fuel as it is about to enter the water gas reaction zone before the endothermic reaction takes place. In this' manner, the fuel just abovey the water gas reaction zone is more highly preheated to closer the 'reaction' temperature before entering that zone, and the heat carrier is cooled somewhat of its excessive heat before reaching the endothermic water gas reaction zone. Consequently the water gas reaction is made to take place more rapidly and chance of secondary degasification avoided.

Furthermore, the present invention contemplates and makes it possible for the admission of steam, necessary for the productionof water gas, into the gasifying zone, and if necessary directly into the degasification zone of the gas producer, and it comprehends the utilization of the sensible heat of the fuel residue for the additional production of water gas. Figure 1 of the drawings shows schematically an exempliflcation of the process according to the present invention.

Figure 2 shows schematically a gas producer `in which the steam necessary for the production of water gas is introduced into the gasifying zone and the sensible'heat of the fuel residue is led back to the gasifying zone by means of steam fo the additional production of water ga's.

The fuel is discharged Vfrom the storage hopper I (of Fig. 1) by opening the slide 2 into the reservoir 3, from where it is delivered through a continuously or intermittently operated feeding de- .vice 4 to the gas producer 5. The gas producer 5 is illustrated on the drawings as a shaft-furnace. ,For the supply of the heat carrier, there have been provided several bridges 6 by which the h eat carrier is uniformly distributed over the cross section of the shaft. Above these bridges is situated the degasification or preheating zone a, underneath the bridges is the gasifying zone b.

The highly heatedmixture consisting of heatv carrier and steam, enters the shaft of the ,gas producer below the bridges 6 and separates here into two streams. The rst heat carrier stream is passed through the zone a, where it distills, and as its temperature lowers it then, at low temperature, dries and preheatsthe fuel, by givingoff its sensibleheat. The' second heat carrier stream is led through the zone b in which lies the fuel which was heated previously in the zone a. Under the influence of thel steam from the heat carrier upon the glowing fuel, water gas is produced in the zone b. 'The water gas together with the heat carrier leaves the shaft of the gas produced through the bridges 'I. The fuel residue below the bridges 1 is now for instance indirectly cooledin the boxes 8 through which water is led. It is then delivered by means of the continuously or intermittently operated feeding device 9 from the gas producer into the container I0 from Where it is discharged into cars;

i low temperature distillation gases as well as the steam generated from the water content of the fuel, flow along together with the heat carrier passing through the zone a, and leave the gas` producer through the gas outlet I3, and are delivered through the pipe line I4 into the detarrer The blower I6 sucks-off the tar-free gas and delivers it to the heater I'I for the gaseous heatcarrier, Where it is raised to the necessary degree of temperature. Here, a cracking and conversion of hydrocarbons originating from the lowtemperature distillation gases, takes place by means of steam. 'I'hen the heated gaseous heatcarrier is led through the pipe line I8 to the bridges 6, whence it reaches again the gas producer shaft. The steam necessary for the production of water gas and for the conversion of hydrocarbons isadded to the gaseous heat-carrier before the heater I1 through the pipe line I9, or behind the heater' II through the pipe line 20, or* through both.- The temperature of thel gaseous heat-carrier can hereby be controlled extremely well.

The gaseous heat-carrier that is passed through the zone b and the water gas produced in this zone, leave the gas producer shaft through the bridges I as the hydrocarbon-free nal water gas, and ow through the pipe line 2| to the heat exchanger 22, where they transmit the greatest amount of their sensible heat. The heat exchanger 22 is constructed preferably as a wasteheat'boiler in which the steam necessary for the production of water gas is generated. Then the gases are delivered to a cooling and cleaning plant consisting for instanceof a precooler 23, a me-A chanical gas purifier 24 and a final cooler 25. The blower 26 sucks the gas from the cleaning plant and delivers it lto the pipe line 21 which leads to the places of consumption.

The heat carrier streams are controlled through the blowers I6 and 26. So much of the heat carrier is introduced into the degasification zone a, as is necessary for the distillation, lowtemperature process, drying and preheatment of the fuel. 'I'he heat carrier together with the low-temperature distillation gases, as well as the vapours and the water gas produced within the range of high temperatures in zone a, leaves the gas producer through the gas outlet I 3 at a tem- If the fuel is not to be gasiiled completely, but

perature 'lying labove the dew point'of the gas so that the steam contained in the' gas does not condense. In the gas heater I1, the4 gases are heated-up to such an extent that a'cracking and conversion of the hydrocarbons from the .low

rtemperature distillation gases takes place `in reaction with steam. 'I'he heat carrier enters the gas producer through the bridges 6 at a temperature necessary for the water gas '.process. This temperature mainly depends on the reactivity of the coke lying underneath the bridges 6, and on the composition of the water gas to be produced. 'Ihe quantity of heat to be utilized for the reaction of the water gas process in the zone bis taken from the heatcarrier passing through this zone and lpartly from the heat stored in preheated coke when it reaches the zone b, so that both media are cooled-down by the endothermic water gas reaction. 'Ihe eect of the temperature drop in the zone vb is determined by the composition of the water gas to be produced. Theinlet and outlet temperature of the heat carrier of thezone b is. therefore, predetermined and fixed for the composition of `water gas that is to be made and for the kind of fuel that is to be used. The quantity of this heat tillation gases, which are cracked in the heater and converted, since the quantity of the heat carrier passing through the zone a, must be main-V tained permanently. This latter quantity"` may 'be controlled by the heat carrier blowers and' is determined by the heat quantity to be utilized in 'the zone a. for the production of water gas as well as for the low-temperature distillation treatment,

` the production of water gas according to the- Gil drying and preheating of the fuel. Therefore,

present invention may be also carried out in the zone a, whereby the temperature drop in the zone 'b can be altered correspondingly. By regulating the heat-carrier temperature and by altering the two heat carrier streams, water gas of any composition can be produced from all kinds of fuel. The fuel must, however, be such as to allow for the passage ofthe heat carrier. 'Ihe fuel, therefore, has to be of lumpy-size, i. e., ney grained fuel must be briquetted before being use Y Another mode of carrying out the process according to the present invention is shown in Figure 2. The heat carrier is delivered through the pipe line I8 to the bridges 6, separates within the i gas producer 5 below the bridges into two streams as above described. If now a fuel is pre-treated in the zone a for the'production of water gas, which fuel has a high percentage of moisture and requires a great amount of heat for its drying and low-temperature distillation, it is more advantageous to carry out the water gas production only in the zone b. For this reason, another set of bridges 28 are also for instance arranged in the zoneb.' Steam only, for the production of water gas is admitted through the bridges 28 to the zone b, said steam together with theheat carrier from bridges 6 flows to the bridges 1 and on itsway thereto it is converted to water gas with the glowing coke-carbon. In order to avoid a rapid and considerable drop of temperature in the zone b, the steam is superheated to the temperature existingin the zone b, which for instance can be arrived at by a superheating pipe coil 29 which is arranged in the heat carrier pipe line I8.

if a. certain quantity of coke is still to be left ungasiled to be recovered for heating the heat carrier, it is of advantage to make use of the sensible heat stll contained in the residue of coke leaving the zone U, to obtain an additional production of water gas. the coke underneath the bridges 'I in countercurrent to the fuel. Said steam takes the heat from the coke, superheating the steam and lateron being utilized in the reaction for the formation of water gas. The steam superheating process takes place in zone c of the gas producer shaft. The saturated or somewhat superheated steam ows in at point 30 in the box 3l which is in connection with the shaft zone c through the slots 32. The steam enters the zone c through the slots 32 and flows to the bridges 1. In this way, the coke is cooled-down and the steam is superheated until it has reached the degree of temperature necessary for the water gas reaction with coke in the portion of the fuel bed under the water gas reaction zone. The water gas thus developed is withdrawn, along withthe water gas leaving the zone b through the bridges 1.

By the separation of the heat carrier stream Within the gas vproducer as aforesaid, the cross section load of the gas producer is considerably improved, since the preheatingand the gasification of thefuel are separated from one another. The capacity based on the cross-section of the furnace is therefore larger than with the known processes. The sensible heat of the fuel residue is utilized in the gasifying zone for the water gas' reaction. Therefore, also the heat required for the carrying out of the process willbec'ome less. Moreover, the quantity of heat carrier circulating is hereby reduced.

Any kind of fuel may be used for the treatment.

Even wholly or partly degasified fuels allow for advantageous gasification, if carried out according to my` present invention. In this case, the fuel in the zone a is mainly preheated to-'the temperature required for the production of water gas. It is also possible to perform any desired stage of the water gas production within the zone a. The steam herefor may be added to the heat carrier before entering the gas producer or by the introduction of steam into the zone a, i. e.,

through the bridges similar to the' kind described before in connection with zone b, the heat carrier passed through thezone a being returned to the gas producer. By carrying out the gasification partly in the zone a, a uniform'cross section load across the entire height of the gas producer shaft can be attained which is of special advantage `with those fuels which require for their gasification and preheating a smaller amount of heat than for their partial and full gasification ln the gasifying zone b.

Accordingly, the highest efciency can be arrived at with the present invention, because of the full utilization of the entire space of the shaft.

Another exemplification of the process according to the present invention consists in leading both heat carrier streams separately into the gas producer shaft. Thereby, it is rendered pcssible to let them enter the degasiiication zone and the gasifying zone at a diilerenttempexiatures, which permits a further control and adaption to the gasifyng fuel. Furthermore. steam may be added to each heat carrier stream for a denite production of water gas in either or in both zones.

Steam is passed throughy a components.

If a synthesis gas is to be produced which, in additionvto the water gas constituents, still contains other gases, they can be added to the heat carrier stream, according to the present invention, either outside the gas' producer or inside the gas producer, in the gasifying zone, or in the degasication and preheating zone. For example, during the manufacture of a synthesis gas containing nitrogen in the gasifying zone, air is introduced. The oxygen of the air combines with the carbon of the fuel mainly to form carbon monoxide, whereas the nitrogen of the air leaves the gas producer as an inert gas, together with the gases resulting from the gasifying zone. The gas mixture leaving the gas producer `is led, if required, to a conversion plant in order to reduce all undesired gas constituents into synthesis gas If a high content of carbon monoxide is required to be produced by the heat carrying gas, which cannot be attained even with a hot run of the water gas process, then oxygen is, for instance, added to the heat carrier stream in the gasifying zone. Thisaddition of oxygen effects a gasification of the fuel to carbon monoxide, whereby an enrichment of the heat carrying gas with this gas takes place.

Furthermore, it is possible 4to maintain the composition of the heat carrying gas by the introduction of foreign gases into the gasifying zone. In the presence of glowing fuel and reactive gases, said gases are cracked or converted in the heat carrier. By this means or by any other combination suitable for the special case, it is possible to obtain any desired composition of heat carrying gases within the utmost limits,

quite independent of the kind of the fuel used.

1 have now described in the foregoing my present invention on the lines'of a preferred embodiment thereof, but my invention is not limited in all its aspects to the mode of carrying it out the water-gas reaction zone; and effecting said maintenance of the zones of the fuel bed by traversing the upper predistillation zone with a preheated gaseous heat carrier medium of watergas and circulation of the same from the upper predistillation zone together with hydrocarbons therefrom and steam through a separate heating-up stage to reheat the medium and thence back to the fuel bed through the lower water-gas reaction zone for the water-gas reaction therewith; the improvement comprising: introducing the gaseous heat carrier medium for the upper predistillation and lower water-gas reaction zone to the bed intermediate the respective zones, and in quantities for the respective zones to supply the heat requirements for the respective zones; withdrawing the hydrocarbon-free water-gas from the fuel bed at a zone intermediate the lower water-gas reaction zone and the region of withdrawal of solid residue from below the watergas reaction zone; the heat carrier for the respective zones being introduced-to the fuel bed at a region in which the stream divides and the part for the upper zone traverses the upper zone independently of the lower zone and the other part of the stream for the lower water-gas reaction zone traverses predistilled fuel from the upper zone before the predistilled fuel and the heat carrier reaches the lower water-gas reaction zone.

2. A method as claimed in claim 1, and in which the heat carrier stream for the upper predistillation degasifying zone is led countercurrent through the fuel therein, and the head carrier stream for the lower water-gas reaction zone ls led co-currently through the fuel of the waterl gas reaction zone.

3. A method as claimed in claim 1, and which includes the step of generating part of the watergas also in the upper predistillation degasifying zone.

4. A method as claimed in claim 1, and in which steam for water-gas reaction is injected directly into the fuel bed in the lower gasifying zone but above the lower oiftake for hydrocarbon-free water-gas.

5. A method as claimed in claim 1, and in which steam necessary for the water-gas production is added to the heat carrier after it leaves the heating-up stage but before it enters the fuel bed,

- whereby part of the water-gas is generated also in the upper predistillation degasifying zone.

6. A method as claimed in claim 1, and in which additional steam is also lled through the fuel residue in the region of the bed underneath the zone of withdrawal of hydrocarbon free water-gas, said steam transferring sensible heat of the fuel residue upwardly toward the lower watermedium that is to react in the lower water-gas reaction zone.

ROMAN RUMMEL.

Images