US1844628A - Method of generating gas - Google Patents

Description

Feb. 9, 1932. c. w. ANDREWS ET AL METHOD OF GENERATING GAS Filed Sept. 22, 1928 2 Sheets-Sheet l EH50 Q2( 5 2 wZoN mzbwm E IN V EN TORS 03. Can/" M Mv-Bz ATTORNEYS I c. w. ANDREWS ET AL 1,344,623

METHOD OF GENERATING GAS Filed Sept. 22, 1928 2 Sheets-Shet 2 mm x INVENTORS- BY @011 vudv em ATTORNEYS Patented, Feb. 9, 1932 I UNITED STATES PATENT orricr.

omnnns w. ANLanws, or DULUTH, MINNESOTA, AND WILLIAM B.

.m'cxsoN arrears, NEW Yonx cnAPmiN, or

melon or GENERATING ens Application filed September-22, 1928. Serial No. 307,599.

- The primary object of the invention is to provide a method whereby a gas generator may be operated under such conditions as to so control the formation of. clinkers, as to prevent the formation of the large chnkers which tend to form in the ash bed, and lower portion of the fire bed in usual methods of operation. Particularly in the production of Water gas, clinkers of such'large size have been formed that it has been necessary to shut down the generator periodically and take out the clinkers manually with bars and sledge hammers.

Our prior application Serial Number 120,- 291, filed July 3, 1926, now Patent No. 1,709,335, dated April 16, 1929, entitled Method of generating gas, contains subject matter in common with the present application, certain'generic claims of a scope commensurate with those presented herein hav ing been contained originally in said prior application, together with other claims relatlng particularly to the manufacture of water gas, and said generic claims having been withdrawn in compliance with the ofli cial requirement that they be presented in a separate application from the said claims relating particularly to the manufacture of water gas. The present application therefore is intended to cover the subject matter withdrawn from the claims of the aforesaid prior application for the reasons above mentioned, as well as certain features of the invention as utilized for the purpose of gas enrichment.

\Ve have illustrated in the accompanying drawings a gas generator adapted to be operated in accordance with the invention, but it should be understood that this'particular gas generator is merely typical of an apparatus suitable for carrying out the invention, and that the principles of the invention are not confined thereto. Inv the drawings F ig. 1 is a central vertical sectional View showing the general construction of a gas generator adapted to be operated in accordance with the invention.

F igs. 2 and 3 are vertical sectional views,

partly diagrammatic, respectively showing the full height of a water gas eneratorand gas producer adapted to carry out the process of the present invention.

The invention is first described hereinafter as applied to the manufacture of water gas but it is to be understood that it is in a broad sense applicable to the making of producer gas or a mixed gas, or to the enrichment of industrial gases such as blast furnace gas, lime kiln gas, or gases obtained from any reduction process wherein a large percentage of CO must be left.

Gas generators both for water and producer gas have been operated with relatively thick ash beds, with the result that the ash in the lower parts of the ash bed has been relatively cold, and although such ash beds have been agitated to some extent from underneath, this agitation has not proved effective in breaking up very large clinkers, particularly in water gas generation, when once they have been formed, and the eifort has generally been made to minimize the formation of large clinkers by keeping the tem eratures Within the generator as low as possi is while still within the limits necessary for producing a commercial grade ofgas, the idea being that if the ash content of the fuel bed was kept below its liquef-ving temperature, there would not be so many large clinker masses formed. Moreover it has been customary to operate watergas generators, so as to maintain under the firebed a bed of thoroughly burned fuel deep enough to submerge the ash agitating member, thereby rendering it annecessary to water cool said member.

According to the present invention the gas generator is operated under such conditions that the temperature of the hottest zone of the fuel bed for the most part is well above the liquefying point of its ash content, where by liquid ash tends to run down in little rivulets from the hottest zone of' the fuel bed, to a slightly cooler zone directly beneath the same which latter zone, although somewhat below the liquefying point of the ash, nevertheless is sufficiently hot to permit the liquid ash, trickling into said zone, to continue its downward flow without losing its mobility until it reaches the small clinkers and partially burned fuel in the neighborcome thick as is customary in prior practice.

The solidifying zone above mentioned will then be located almost upon the grate of the generator, such zone being made up of partially consumed fuel, small clinkers and ash at red heat, with the result that the generator has no thick cold ash bed as heretofore. The agitating member, located directly over the generator grate, is where it will continually break up clinkers as aforesaid, and also thoroughly agitate the lower portion of the fire bed and assist in the uniform removal of the clinker and ash due to its up-and-outstroking action, thereby maintaining good gas making conditions in the firebed. The thin ash bed and the continuous agitation of the firebed make it possible to carry a greatly reduced de th of fire.

By supp ying air in sufficient quantity to maintain an ash liquefying zone in the fuel bed, and ejecting clinker and ash at such rate that the solidifying zone will be shallow and kept at a proper heat, the same agitating member may serve to perform continuously all of the above mentioned functions of preventing the formation of large clinkers by breaking up the clinkers as they form, agitating the fuel bed and assisting in the removal of the clinker and ash. For example, from 30 to 50 cubic feet of air (at atmospheric pressure and room temperature) may be used per pound of total steam, the smaller amount of air being used for fuel of low ash melting point and the larger amounts for fuels of higher ash melting point. Agitation in this invention is not through the medium of the ash as heretofore, but mostly through the medium of the partially consumed, but still burning, fuel.

The amount of steam fed into the bottom of the generator may also be regulated to control temperature conditions within the generator, the steam acting as a cooling medium, whereas the air fed in acts as a heating medium.

In the production of water gas, furthermore, the up and down runs may be proportioned to maintain ash liquefying and solidifying temperature conditions as above described, sfthat the clinkers will be properly broken up by the agitating member. The production of water gas usually involves a cycle of operations over a period of three to aseaeae eight minutes, the first operation being the passing of'a blast of air upwardly through the ash and fuel beds, another operation being an upward run of steam, and a third operation being a downward run of steamthe above operations usually taking up about the same amount of time, the up and down steam being about the same in quantity, according to prior practice.

In accordance with the present invention the upward blast of air will be sufiicient in quantity to raise the hottest zone in the fuel bed to such a temperature as may be required to liquefy the major portion of the ash content of the fuel bed. This temperature, with some grades of coke, may be, for example, from about 2700 to 3000 F. The quantity of the up-run steam may be (but is not necessarily) substantially lessened to assist in preventim the lower zone in the firebed from cooling 0% sufiiciently to unduly check the fiow of the molten clinker streams before coming within the radius of action of the agitating member. Good results have been obtained with but twenty (20) percent of up-steam runs. This makes a sufficiently increased proportion of down-steam runs, so that it will carry down from the upper zones suflicient sensible heat to assist materially in maintaining at a red heat the major portion of the clinker and ash upon the grate. Because of the high temperature maintained in the bottom of the fire, the steam up-ruhs may be entirely omitted if blue water gas is desired, or if the gas connections are arranged to pass part or all of the downrun water gas through the carburetor. This does not preclude removing gas from the ash pit by up purges. This unusually large percentage of down-run steam greatly increases the efficiency of water gas generation The usual practice in the operation of present day water gas generators involves not more than a 50% ratio of down-run steam to the total steam supplied.

it has been found with certain fuels that gases made in a deep fire bed of the above description, are exceptionally rich in quality, the air blast gases being too high in carbon monoxide for the most efficient operation. A substantially thinner firebed has resulted in substantially reducing the richness of the blast gases, which pass through the firebed at high velocity, without materially reducing the richness of the up and down-run water gases, which pass through the firebed comparatively slowly. The exceedingly high temperature described above and the uniform condition of the firebed, due to continuous agitation, render it unnecessary with some fuels to carry the usual depth of firebed, which is eight (8) to ten (10) feet, in order to obtain a satisfactory quality of gas; a satisfactory quality of gas has been obtained with one half the usual depth of firebed. This reduces the pressure drop through the firebed annular and alsoreduces the'combustible content of the blast gases leaving the fuel bed,'thus increasing the efliciency of the operation by developing more heat in the firebed, and carrying away less energy in the blast gases. For example, the blast ases may contain about 14% CO and 14% 0 The invention as illustrated ma be carried out in a gas generator similar to t e one more fully described in our copending application, Serial Number 737,238, filed September 12, 1924, now Patent No. 1,709,334 dated'April 16, 1929, entitled Gas generator, and accordingly the structural features of the generator will be described only in a general way herein. The gas generator is shown as provided with side walls 1 enclosing the fuel and ash beds and a stationary grate 2 through which air and steam will be passed, as previously described in connection with the production of water gas. As shown, a distributing chamber 3 underlies the grate 2 and is surrounded by an annular ash chamber 4 into which a portion of the ash will be deposited as hereinafter described. A certain amount of ash will also pass down through the grate 2 into the chamber 3.

The agitating member 5 is shown in the form of a water cooled beam extending substantially diametrically over the grate and secured to a drive ring 6 which surroundsthe grate and is rotatably mounted upon the hearing ring 7. Suitable water cooling connections 8 may be led through chamber 3 to the agitating member.

In the operation of the generator a zone 9 of the fuel bed which extends down approximately to the line 10 indicated on the drawings, will be maintained at a heat sulficient to liquefy at least most of its ash content, with the result'that small streams of the liquid ash run down into the bed or zone 11 beneath the line 10 indicated upon the drawings, which is maintained at a temperature somewhat below the liquefying temperature of the ash (2,000 F. more or less, depending upon the melting point of the ash) but yet at a red heat sufficient to prevent the ash from cooling and taking a set too quickly. The agitating member 5 rotates within the above mentioned zone 11 and therefore directly engages and breaks up the solidifying ash before it can form into large clinkers. The beam should be made of substantial thickness and asshown its forward surfaces preferably are inclined, whereby it exerts a substantial upstroking effect which extends at least into the lower portion of the zone 9 and assists in maintaining good gas making conditions therein.

The beam is also outstroking in its action and tends to crowd the ashoutwardly beyond the periphery of grate 2, from whence the ash may pass downwardly through an ash discharge opening 12 to a trough are at a red heat, substantially down to the grate 2.

As shown, theportion of the generator walls surroundingthe agitating member 5, are water-cooled by means of the passages 14 in an annular wear member 15. This water-cooling tends to cool down the portion of the generator walls just above the ring 15 to such an extent that under ordinary conditions slag deposits would build up'which could only be removed manually after shutting down the generator. We have found, however, that if a zone in the fuel bed he maintained well above the ash liquefying temperature, as above described, the ash will quickly flow downwardly past said cooled portion of the generator wall into the radius of action of the agitating member without forming objectionable deposits as aforesaid.

A generator, operated in the above manner, therefore, may be run continuously, the ash being mechanically removed at the proper rate and the fuel and'ash beds mechanically agitated from underneath by the beam 5, to assist in maintaining good gas making conditions.

It has long been recognized that the socalled slagging producer is the most eflicient type; due to the extremely high temperatures necessary for liquefying the entire ash content of the fuel, but hitherto this type of producer has not proven commercial because of the cost and extreme difficulty of obtaining the required degree of fluidity with most fuels. -A modified slagging type is now made possible by the combinationof mechanical agitation and proportioning of the blast, and up and down runs above described. This improved method has all of the advantages of the slagging roducer and none of its disadvantages, and therefore forms an important part of this invention.

In Fig. 2 we have shown in a general way, a water gas generator having the parts more fully described above in connection with Fig. 1, and also having in its dome at the top, a steam inlet pipe 16 and a similar steam inlet pipe 17 in chamber 3 above described. A gas and blast outlet conduit 18 is also indicated at the'top, and air and gas inlet and outlet conduits 18a at the bottom, communicating with chamber 3. Fig. 2 also shows the ash liquefying zone 9 and ash solidifying zone" 10 in proper relation to the full height of Fig. 2 used for ma ing producer gas, the

various numerals denoting the same parts as in Fig. 2 with the exception that the up er firebed zone 19a of Fig. 3, will be somew at shallower than the corresponding firebed zone 19 of Fig. 2.

In a plying the invention to the enrichment 0 industrial gases as above mentioned, the steps of operation will be similar to those described above in connection with the manufacture of water gas, except that the up and down runs of steam are not employed as above described (althou h a certain amount of steam may be used if esired) and instead up and down runs of the industrial gas containing 00 and CO are admitted through the inlet openings 16 and 17 above described,

with the result that the CO content of the industrial gas is broken up and CO formed. In other words in using the invention for enrichment purposes an u -blast of air may be first passed through the firebed to heat the same up after which an up purge of steam may be passed through, although this is not essential; an up run of industrial gas may then be passed through, followed by a down run of industrial gas, althou h the latter two steps may be reversed, if esired, or the up-run of gas omited, particularly if a fairly large steam purge is used.

The gas obtained will be of the producer as type but usually of higher B. t. u. value; or example, blast furnace gas may be raised from a value of 94 B. t. u. per cubic foot up to 160 B. t. u. or more.

A mixed gas may also be used, containing water vapor as well as CO, or liquid hydrocarbons may be added along with the runs to further improve the B. t. u. value of the gas, for example, through the inlet openings 16 and/or 17 above described in connection with Figs. 2 and 3.

Temperature conditions in the firebed will be controlled by proportioning the amount of air supplied, and the up and down runs to I maintain an intermediate ash liquefying zone and lower ash solidifying zone as above described in connection with the manufacture of water gas, whereby the agitation of the firebed breaks up any large clinkers and renders the firebed continuous and mechanically conditioned in its operation for the purpose of gas enrichment.

We claim:

1. The method of making combustible gas of the producer gas type-in a firebed containing a zone at an intermediate level and a second coler zone containin ash underneath said first mentioned zone, w ich includes airbefore large masses can form.

2. The method of making combustible gas of the producer gas type in a firebed containing a zone at an intermediate level and a second zone containing ash underneath said first mentioned zone, which includes air-blasting the firebed to maintain the first mentioned zone at a temperature suflicient to liquefy a substantial portion of its ash content, passing the liquefied ash content downwardly into said second mentioned zone, maintaining the second mentioned zone at a red heat somewhat below the ash solidifying temperature, whereby the ash passing downwardly from the first mentioned zone solidifies in the second mentioned zone, and passin an agitating member through said secon mentioned zone to break up clinkers while hot and before large masses can form.

3. The method of making combustible gas of the producer gas type in a firebed, which includes air-blasting the firebed and maintaining 11 zone therein at an intermediate level at a sufficiently high temperature to liquefy a substantial portion of its ash content, passing the liquefied ash content downwardly to a solidifying zone' beneath said first mentioned zone and agitating said solidifying zone to break up the clinkers while hot and before large masses are formed.

4. The method of makingcombustible gas of the producer gas type in a firebed, which includes maintaining a zone at an intermedi ate level in the firebed at a temperature sufficient to liquefy a substantial portion of its ash content, passing the liquefied ash content downwardly from said zone to solidify the same, removing ash from the bottom of the firebed at a rate sufiicient to leave at the bot tom of the firebed only a small amount of ash at a temperature somewhat below the ash solidifying point, and passing an upstroking agitating member through the bottom of the firebed to engage and break up the solidified clinkers which tend to form and agitate the firebed from underneath and assist in the removal of the ash.

5. The method of making combustible gas in a firebed, which includes separately airblasting the firebed and passing gases containing CO and CO therethrough, to maintain a zone in the firebed at an intermediate level at a suficiently high temperature to liquefy a substantial portion of its ash con tent, passing the liquefied ash downwardly to a solidifying zone beneath said first-mentioned zone, and breaking up the clinkers in said second-mentioned zone while hot andbefore large masses can form.

6. The method of making combustible gas in a firebed, which includes separately airblasting the firebed and passinggases con taining CO and CO therethrough in up and down runs to maintain a zone in the firebed at an intermediate level at'a sufiiciently high 110 temperature. to liquefy a substantial portion of its ash content, passing the liquefied ash downwardly-to a solidifyingvzone beneath said first-mentioned zone, and breaking up the clinkers. in said second-mentioned zone while hot and before large masses can form. 7. The method of maklng combustible gas in a firebed, which includes separately airblasting the firebed and passing gases containing CO and CO therethrough in up and down runs to maintain a zone in the firebed at an intermediate level at a sufliciently high temperature to liquefy a substantial ortion ofits ash content, assing the lique ed ash downwardly to a sohdifying zonebeneath said "first-mentioned zone, breaking up the clinkers in said second-mentioned zone while hot and before large masses can form, and in- 'jecting a liquid hydrocarbon along with one or more of said runs to further enrich the gas made. a

8. The method of making combustible in a firebed, which includes separately an blasting the firebed, purging the firebed by passing steam therethrough and passing gases containing 00 and CO therethrougn, to

maintain a zone in the firebed at an ,intermediate level at a sufliciently high tempera-v ture t0 liquefy a substantial ortion of its ash content, passing the lique ed ash down- 40 wardly to a solidifying zone beneath said first-mentioned zone and breaking up the clinkers in said second mentioned zone while hot and before large masses can form.

Executed at New York, in the county of 5 New York and State of New York, this 16th day of August, 1928. CHARLES W. ANDREWS. WILLIAM B. CHAPMAN.

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