US1872883A - Process of manufacturing gas and carbonized fuel - Google Patents

Description

J. F. BYRNE. 1,872,883

PROCESS OF' MANUFACTURING GAS AND CARBONZED FUEL Fi1ed June 21. 1928 Aug. 23, 1932.

r Ms E l mm mm a M ma MM m M, l a Ma E o N Mm w s r 0 wa we .,mw wh wr N@ n f fm L.. I A MS a W rl. w z 2 w N a M ma i j 6j 2 .m W6 M6 .J 00 f Y 1 I j f ,f ..wuw aka? n f Z w a 9./ w1 W v 4 T W 7 f j www n f mw l mm 4 j M Wi nl w AIEMM M rc M m H/// ARM am waa C6 W 9u F 9a. .y mw? 2 ff fr Wa L M. m w W w, Mm rw@ w NM Wm M m m W s m MF m ,ws W 3 s w .s ad CM Patented Aug. 23,1 1932 UNITED STATES PATENT! OFFICE JOHN F. BYBNE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE KOPPERS COMPANY OF DELAWARE, A CORPORATION OF DELAWARE PROCESS OF MANUFACT'ORING GAS AND CARBON IZED FUEL Application vled June 21, 1928. Serial No. 287,193.

This invention relates to the manufacture of gas, such as water gas, or water gas and coal gas, from carbonaceous material such as coal. It relates also to the incidental carbonization of such material, Whether the carbonized product is to be removed as such, burned, or gasified.

My invention has a particular relation to the manufacture of water gas by reason of the fact-that it is adapted to be carried out in conjunction with the manufacture of water gas in apparatus and by a process only slightly modified with respect to existing apparatus and processes, yet with novel and hitherto unattainable results, of great advantage.

My invention furthermore presents a novel and practicable method whereby the carbonization of coal, whether for coking purposes alone or for gasification of the resulting product, may be carried out by means of the sensible heat contained in a bed of incandescent or highly heated fuel, such, for example, as is maintained Within the gas generators of current and prior practice.

The objects of my invention are to secure t-he operative advantages and results herein set forth, with provision for apparatus and process whereby they maybe secured, and,

also such other operative advantages andresults as may by implication found hereinafter to obtain, and including such modifica- I' tions and improvements relating thereto as are within the scope of the claims hereinafter4 made.

It is known that it is advantageous for many reasons to accomplish the carbonization of coal substantially entirely by. means of the sensible heat contained by a fuel bed, rather than by, means of the sensible heat of gases passing therethrough, or evolved therein, but the principle has hitherto been found to be difcult of application by reason of the4 dificulty of bringing the coal to be carbonized into effective contact with the heated fuel bed. It is obvious that uniform distribution is essential, and practical results have indicated that the actual depth or thickness of the layer of coal to be carbonized 'must be small to permit eective carbonization. Under these requirements, it has been found dificult to utilize any great proportion of such a fuel bed as might ordinarily be employed for thisV purpose, e. g., the fuel bed of a watergas generator.

It has been attempted to utilize the aforesaid principle by dropping a layer of coal upon the top of the fuel bed within a gas generator, but this procedure has produced a coke that is unsatisfactory by reason of its fluiines's and poor structure. Moreover, this procedure is ill adapted to the requirements of the gas generator, both with respect to fuel and operation.

'It has also been proposed to introduce a charge of fuel into the highly heated interior of a fuel bed by means of a stoking or ramming device, but it is obvious to those skilled in the art that the mechanical diiiculties are great andthat full penetration of the fuel bed can not be realized in this manner.

I have found that when finely comminuted coal is suspended in a gas or vapor about to be passed through a fuel .bed of, for example, such thickness and general characteristics as is ordinarily maintained .in a water-gas generator, and allowed to enterthe fuel bed sosuspended, the fine particles of coal are caused to penetrate the fuel bed and to be distributedsubstantially uniformly and entirely throughout the same.

Accordingly, I suspend suitably comminuted coal, for example, 'coal of such particle size as is n ow commonly used for combustion purposes in boilers and the like, 1n a gaseous fluid about to be passed through a gas generator. Preferably, I so conduct this operation with respect to the manufacture of the gas and other conditions within the fuel bed that the finely divided fuel thus added is first carbonized rather than burned as coal, and after partial or complete carbonithe reduction of the actual water gas, or m e gas, rather than in the air used for maintaimng the high temperature of the fuel bed, but my invention in its broadest aspect contemplates the use, as a carrier for the coal, of any aseous fluid or vapor that is to be passed t rough the enerator.

The amounts an proportions of coal and the gas carrier will, of course, vary with the results to be attained, the requirements of the process as a whole, and the like, but in any case will be so re ulated and `controlled that substantially uni crm penetration of the fuel bed is`secured, while avoiding any excesses that mi ht tend to carry large amounts of the finely divided coal over into the subseuent apparatustraversed by the gas, such as t e carbureter and superheater of a carburetted water-gas set.

The amounts of finely divided coal added to the fuel bed may be varied considerably, and while it is preferred to introduce an amount at least sufficient to satisfy the requirements of the water-gas reaction, that is to say, sufiicient coal to supply enoueh carbon to react with substantially all of the active steam, my invention also contemplates the addition of greater amounts in order that an excess of carbonized fuel or coke may be produced.

My invention further contemplates the preferably continuous removal of this coke from the generator, together with the ash remaining after the combustion or gasification of the other fuel in the generator. The high-ash coke, or mixture of ash and coke, thus discharged may be utilized as a lowgrade fuel in boiler settings and elsewhere, or 1t may be treated for the removal of ash and be thereby made useful for many other purposes.

It will thus be apparent that, in contradistinction to the prlor art, my invention contemplates a process in which finely divided coal is carried into a highly heated and preferablyincandescent fuel bed in such manner that the coal penetrates the fuel bed substantially uniformly. The coal particles adhere to the incandescent coke of the fuel bed and are coked lar ely by the sensible heat of the fuel bed, rat er than by the sensible heat of gases passing therethrough or by the sensible heat of the generator lining. The coke formed from the coal is then burned or gasiied or is removed as such; that is to say, sufficient coalmay be added in this manner `to supply an excess over the requirements of the combustion and gasification reactions.

With regard to tbe terms combustion and gasification, it is intended that these shall designate reactions of exothermic and endothermic effect, respectively. It is, of course, well known to those skilled in the art 'that these may o. on concurrently, as for exi ample during t e air-blasting period of the cyclic water-gas process, or durin the manufacture of producer gas. It is a so obvious that the term gasification refers not only to an external reaction, such as the water-gas reaction, but also to an internal reaction, such as the destructive distillation of coal.

In order that my invention may be fully set forth and understood, I now describe, with reference to the accompanying drawing, which illustrates a 4preferred embodiment or embodiments of thc apparatus of my invention, the preferred manner in which it is embodied and practiced. In this drawing,

Figure 1 is a vertical sectional view of the Water-gus generator that is equipped with means for introducing finely comminuted fuel thereto and for removing ash or a mixture of ash and coke therefrom; and

Fig. 2 is a view, partly in elevation and partly in section, of a portion of a water-gas generator and includingr an alternate form of apparatus for introducing finely comminuted fuel thereto.

' Similar characters of reference designate similar parts in each of the views of the drawing.

Referring to the drawing and more particularly tol Fig. 1, a Water-gas generator is shown as constituted of a refractory structure 1 of a common form and configuration and which contains a. fuel bed 2 that is supported on a stationary grate 3. While my invention may be practiced in some of its aspects and modifications in a. generator having a simple stationary grate, I prefer to practice my invention in a water-gas generator that is provided with a grate device of the self-clinkering ty e whereby ash or a mixture of ash and carbonized fuel may be substantially continuously withdrawn from the fuel bed 2.

A particular form of such device is illustrated, consisting in part of a Water-cooled beam 4 that is mounted for rotation in a horizontal plate immediately above and adjacent to the stationary grat-e 3. The beam 4 cousists principally of two arms of triangular cross-section which may be either straight or slightly curved after themanner of an inverted S.

The ends of the beam 4. are integrally attached to a revoluble pan 5 thatis situated immediately below an annular metal crushing ring 6 that forms that part of the wall of the generator 1 immediately above the level of the grate 3. The weight of the beam 4 and pan 5 are largely carried through a plurality of bearings 7 and sup iort brackets` 8 and the pan 5 is provided witli a ring gear 9 which meshes with a gear 10 connected to a suitable prime. mover (not shown).

Preferably, the beam 4 is rotated in a series of short stepwise. movements at a speed of about one revolution in 50 minutes. The

effect of this rotation is to agitato the fuel 4, to a point adjacent to the crushing ring 6.

and falls into the moving pan 5 to be removed therefrom by a stationary adjustable plough 12 to fall into a hopper 13. The maferial contained in the hoppers 11 and 13 is conveniently removed through a trap door 14.

Water is admitted to the interior of the beam 4 through an inlet conduit l5 and Hows -therefrom through a drain 16, the upper end of which is so positioned that the beam 4f remains substantially full of water at all times. The pressure ring 6 is also provided with ,water-.cooling means, as shown.

The generator 1 isprovided with a removable cover 17, an ofltake connection 18 leading from the upper part of the generator,

- and a conduit 19 terminating beneath the grate 3 and which may serve as an offtake connection for down-run gas or as a means for introducing air, steam or gas to the bottom of the generator for subsequent upward travel through the fuel bed 2. In the present instance, the'conduit 19 serves as an air blast connection during the blow period of the water-gas cycle and as an uprun steam connection during a part of the run period of the cycle. For the latter purpose, a steam line 20 is provided which terminates in the oonduit 19 and which is provided with a suitable valve mechanism 21.

ceous material Asuch as finely divided solid pitch or the like is supplied to the fuel bed 2 according to my invention in such manner as to substantially uniformly penetrate the same and preferably by being suspended in the steam about to be admitted to the generator 1. A portion or all of such fuel, depending largely upon the quantity of fuel to be added, may be supplied to the fuel bed 2 vby suspending it in the steam that is to be passed downwardly through the same. For this purpose, a special down-run steam connection 23 is provided, having-a valve 24. The down-run steam connection 23 communi- Cates through a vertical passage 25 and a horizontal passage 26 having a conveyor27 therein with a hopper 28 that is supplied with suitably comminuted fuel through a charging line 29 having a valve 30.

For the purpose of balancing the steam pressure in the line 23, a pressure connection 32 having a valve 33 is provided for the hopper 28. The pressure connection 32 is preferably connected to a supply of compressed air or other gas for the reason that the introduction of steam into the hopper 28 under ordinary conditions would cause ward through the same. When the usual type of stationary grate is employed, it is in most cases satisfactory to introduce the pulverized coal into the uprun steam before the latter passes through the grate.

In the present instance, in which a particular form of continuous grate device is used, it has been found that the construction of 85 the latter device is such that the entry of considera-ble portion of the fuel supplied in this manner to the generator is prevented, and this will be true of certain other continuous grate devices offering more resistance to the iiow of the gases than do the stationary gratos of the prior art.

For this reason, I provide means for introducing a portion of the uprun steam above the level of the grate 3 and means for suspending finely comminuted fuel in said portion of the uprun steam in addition to the means already described for introducing the remaining portion of the uprun steam in which no fuel is suspended.

Such means comprises ay plurality o steam inlets 35 inserted in the walls of the generator 1 just above the crushing ring 6. The inlets 35 are provided with steam valves 36 and communicate through passages 37 and 105 38 with a corresponding plurality of fuel hoppers 39 similar to the fuel hopper 28 already above described except that the inv dividual fuel hoppers 39 ordinarily need contain considerably smaller amounts ofvfuel 'the present invention;

In general, it is advantageous to superheat the steam supplied to the generator, and this may be done by any of the Well-known devices for that purpose, or by provision of a regenerator for extracting the necessary heat'from any of the hot gases leaving or passing through the water-gas apparatus. In general, also, the ordinary rates of air vand steam admission have been found satis- 1 30 factory for the purpose in view, and excessive rates tending to carry 'considerable quantities of fuel through and out of the fuel bed should be avoided. This isa matter largely within the discretion and observation of the operator.

To illustrate the invention more clearl the performance of a simple operating cyc e will. be reviewed. This cycle consists essentially of a heating period lcalled the blow, and a gas-making period called the run.

During the blow, air is admitted through the conduit 19 and passing upward through the fuel bed 2 causes partial combustion thereof, which results in the' generation of carbon monoxide and in an increase in the temperature of the fuel whereby the reactionsfduring the rest of the cycle which are endothermic and which require high temperatures may be satisfactorily carried on.

Theair-blast gases escape through the oiftake connection 18 into the usual combustion chamber of the ,gas-making apparatus (not shown). y

When a sufficient temperature has been attained, the supply of air is shut off and steam is admitted to the generator for the run. Generally steam is first passed through the fuel bed 2 in an upward direction. In the present instance, sufficient steam to'pro- `vide a carrier for the fuel to be introduced is admitted through the inlets' 35 carrying in suspension the finely comminuted fuel. Additional amountsof steam for this uprun may be admitted through the conduits 20 and 19 by opening'the valve 21..

The steam carries the carbonized fuel into and throughout the fuel bed 2 and deposits it in the interstices of the same. The fuel thus introduced adheres to the fuel already present in the generator and is carbonized bv the sensible heat of the same. the carbonized fuel then reacts with the steam to form blue water gas, which is removed through the oii'take connection 18.

For the purpose of controlling the temperature conditions within the fuel bed 2,

steam is also passed through the fuel bed 2 in the downward direction during a portion of the run known as the down-run. This portion of the cycle may be accomplished by closing the valves 21 and 36 and opening valve .24, thus allowing steam to enter through the inlet 23 carrying in suspension finely comminuted fuel from the hopper 28 and passing downward through the fuel bed 2, the comminuted fuel being deposited in the fuel bed 2 as before and the resultant -bl'ue water gas passing out of the generator into the conduit 19.

During the run, the performance of the endothermic reactions of carbonization and gasification causesthe temperature within the fuel bed 2 to fall until these reactions are 35 no longer efficiently supported and it betion by chargl Some of comes necessary to again introduce air to the fuel bed.

Before a new blow can be performed, th blue water gas 'beneath the grate 3 must be removed in order to prevent an explosion upon the subsequent admission of air. 4For this purpose, a second uprun is ordinari] performed, steam being admitted throng the conduits 20 and 19 and passing u ward through the fuel bed 2. Ordinarily uring this second brief uprun period, it is not necessary or desirable to continue the addition of fuel to the generator.

Vhile any amount of inely comminuted coal may be added to a water-gas generator according to the present invention for any of the various purposes herein cited, it is preferred to adda suicient amount of fuel in this fashion to at least satisfy the requirements of the water-gas reaction. Especially when only this much'finely divided fuel is added, an additional amount of coarser fuel ma be added by removing the cover 17. Co e, for example, may be ,added in this fashion either for the purpose'of supplying the carbon for the blow or for decreasing the density of the fuel bed or both.

The addition of a certain amount of coars-4 I er fuel to the fuel' bed may be found desirablein any instance, for the purpose of maintammg the fuel bed in asuiciently orous condition to permit adequate assage o gases and thorough penetration o the bed by the finely com-minuted coal introduced. For example, it is generally preferable to maugurate the operation of a water-gas machine to be operated according to my invenn it, in the iirst instance, with coke or other nel of relatively coarse size.

When no coke is withdrawn from the generator by a continuous grate device, the subsequent additions to the fuel bed should cons1st substantially entirely of finely divided coal. The coke servesmerel as a framework for the practice of my invention, and 1s not to be regarded as the real generator fuel, even though small portions thereof may mcldentally be consumed in the process.

Under certain circumstances, it may be desirable or even preferable to add suilicient' finely comminutedcoal to the fuel bed 2 in the manner above described to satisfy 'the entire requirements of the generator with respect to both the exothermicy reactions lof :ge blow and the endothermic'reactions of e run.

In either of these instances, the beam 4- is' ing from the carbonization of the finely comminuted coal is correspondingly small, the reactivity of this coke with both air and steam is very high, and this fact promotes the efficiency ofthe water-gas process as a whole.

With regard to the ineness of the coal particles, it has been found that it is preferable to use coal that has been pulverized to such extent that not more than about 95 percent nor less than about 90 percent will pass a 100- mesh screeen, and not more than about 85 percent nor less than about 65 percent will pass a ZOO-mesh screen. However, it is obvious that these figures cannot be precisely adhered to in practice, and that slight deviations therefrom will not materially reduce the effectiveness of the process.

The advantages of the present invention under certain other circumstances are more fully realized when finely divided coal is introduced to the generator in excess of the gasmaking requirements of the same, whether incident to the air blow or the steam uprun. S

For example, it -may be desired to produce a small amount of comparatively rich gas and concurrentlyA to produce a low grade fuel comprising in reality a mixture of ash and wholly or partially carbonized coal suitable for use in boiler installations and elsewhere. In this instance, the amount of steam is reduced to an amount merely sufficient to carry the suspended coal particles and to assist in removing the gaseous products from the generator and the beam 4 is operated to remove not only ash but also an amount of carbonized fuel equivalent to the fuel added in excess of the blow and uprun requirements. It is obvious that the coal 4gas produced from the coal being carbonized is added to and enriches the blue water-gas formed by reaction with thel steam. Some of this coal gas may be cracked and some of the tar content of the coal gas may valso be cracked, thus adding small proportions of cracked coal gas and cracked tar gas to the total gas.

Furthermore, 1t is obvious that the grate device will, inthis instance, necessarily remove some of the coarser fuel that consti-- tutes the framework of the fuel bed, and that it may consequently be desirable to replace this loss by an equivalent addition of such relatively coarse fuel, in order to maintain the fuel bed in a state of suitable porosity. As in the previous instance, however, this coarse fuel is substantially inert, except as to the storage of sensible heat, with respect to the reactions involved.

In Fig. 2, a special installation is provided for use in conjunction with the so-called back-run process of carburetted water-gas manufacture. In that process, the downrun steam admitted to the generator is first` 'caused to pass through the superheater and carburetter of the carburetter water-gas set and enters the generator through the gen erator carburetter connection` 18.

Accordingly, I provide a suitable fuel hopper 50 and means comprising ` conduits 51 and 52 and a conveyor 53 in the conduit 51 for introducing finely comminuted fuel from the hopper 50 to the superheated steam passing 1through the'conduit 18 into the genera- The following summary of results is of particular interest as showing the results to be expected from the practice of my invention under various operating conditions.

Cycle A B C 1: Blow, minutes 3 3 3 Run, minutes 3 3% 3 Total, minutes 6 6% 6 Average aublast, cu. taper minute 12, 000 12, 000 12, 000 Average steam rate, lhs. per minute 174 190 32 steam .flv B c Steam per cycle, lbs 522 714 192 team decomposed, per cent- 7 50 50 Steam decomposed per cycle, lbs 402 357 96 Coal (8% ash) A B C Coal added for blue water gas er cycle lbs. 393 351 93 Coal added for blast per cyc1e?1bs 51o 51o 51o Coal added for solid fuel per cycle, lbs 1, 317 Total coal added per cycle, lbs 903 861 1, 920 Coke removed per cycle, lbs 922 Ash 1n coke removed, per cent 16. 7

Gas A B C Total gas produced per cycle, cu. It. 22, 410 20, 225 15, 570 Coal gas, per cent 24. 2 25. 6 74 Blue water gas, r cent 75.8 74. 4 26 Thermal value, t. u. per cu. ft 360 365 505 Under columns A and B are listed the results froma cycle with three minute blow, with 77% and 50% steam decomposition, respectively. While under ordinary Water-gas practice the steam decomposition does not ordinarily exceed 50%, it has been found that as much as 77% decomposition or even more can be attained by proper use of a continuous grate devicek of the type illustrated and described herein, and by reason ofthe reactivity of the finely divided coke within the fuel bed.

Under column C are listed the results from a cycle similar as to the blow but in which the amount of steam admitted to the generaltor is reduced to 'a minimum and an excess the gas produced has a thermal value of ap ot. t

proximately 505 B. t. u. per cubic fo -is apparent that a water-gas generator so operated becomes, in effect, a carbonizing retort.

While my invention has been described in connection with various specific illustrative examples, it will be obvious to those skilled y in the art that many modifications are possible which do not, however, depart from the spirit of the invention and are includedin the scope of the claims hereinafter made.

process is `operated to produce a gas consisting largely of coal gas, as 1n one of the instances hereinabove described.

My invention thus presents a practical and advantageous process of realizing a principle hitherto only realized with dif`cultyi. e.,

the carbonization of coal by means of thev sensible heat of'a fuel bed, and my invention further provides a process or rocesses whereby this principle may be app ied and utilized in the manufacture of fuel gas of characteristics variable over a wide range of results.

1 claim as my invention:

f 1. The process of manufacturing water gas and carbonized fuel in awater-gas generator having a bed of solid carbonizable fuel, which comprises alternatel heating said fuel bed by blasting it with air and generating wateras by passing steam through the thereby heated fuelbed, maintaining said fuel bed by introducing to it while suspended in steam passed through the same sufficient finely divided solid carbonizable fuel to provide an excess over that amount required for the combustion and gasification reactions which are set up .in said fuel bed by said air and steam, andremoving from the generator fuel bed solid fuel in carbonized form.

2. The process of manufacturing water gas and carbonized fuel in a water-gas generatorof solid carbonizable fuel, which v having a. bed comprises alternately heating said fuel bed by blasting water-gas by passing steam through the thereby heated fuel bed, maintaining said fuel bed by introducing to it while suspended in steam passed through the same sufficient finely divided solid carbonizable fuel to provide an excess over that amount required for the combustion and gasification reactions which are set up in said fuel bed by said airl and steam and in substantially continuously removing from the generator fuel bed solid fuel in carbonized form.

3. The process of manufacturing water gas and carbonized fuel in a water-gas generator having a. bed of solid carbonizable fuel, which comprises alternately heating said fuel bed by blasting it with air and generating water gas by passing steam through the thereby heated fuel bed, the direction of flow of the steam vdown-flow steam just it with air and generating' up-ow steam just before it traverses said fuel bed, in amount sufficient to provide an excess over that amount required for the combustion and gasification reactions which are set up in said fuel bed by said air and steam, and removing from the generator fuel bed solid fuel, in carbonized form.

4. The process of manufacturing water gas and carbonized fuel in a water-gas generator having a bed of solid carbonizable fuel, which comprises alternately heating the fuel bed by blasting it with air and enerating water gas by passlng steam throng the thereby heated fuel bed, the direction of flow of steam through the fuel bed being reversed from an up-fiow to a the steaming period, maintaining the fuel bed by sus endin finely comminuted solid carboniza le fue in the u -fiow steam and the fore they traverse said fuel bed, in amount sufficient to provide an excess over that amount required for the y through the fuel bed being upward during lat least a portion of the steaming period,

maintaining said fuel bed by suspending fine- 1y commmuted solid carbonizable fuel in the down-flow during a portion of

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