US2218266A - Water gas process - Google Patents

Description

a. PEARSON, JR- 2,218,266

Oct. 15, 1940.

' WATERGAS rnocEss Filed July 19, 1938 INVENTOR hi5 PzgfisozvJie BY a2 7 ATTORNEY Patented Oct. 15, 1940 v Q UNITED STATES PATENT OFFICE.

WATER GAS PROCESS Harry Brownley Pearson, In, New York, N. Y., assignor to Semet-Solvay Engineering Corporation, New York, N. Y., a corporation of New York Application July 19, 1938, Serial No. 219,914 Claims. (Cl. 48-208) This invention relates to processes for making heater exerts a draft on the open stack valve, carburetted water gas and more particularly to particularly if the valve is placed in a stack of a a novel process for minimizing explosion hazards height not substantially greater than that of the v in water gas operation. superheater, and causes air to enter through the 5 Within the past few years the carburretted open stack valve in an amount sufilcient to form 5 water gas industry has adopted a noveltype of an explosive mixture with the combustible gas water gas set involving a generator,"carburetor present in the set. and superheater located in separate and detached I have found that the formation of such exshells and connected in series, the top of the plosive mixtures may be prevented in the operagenerator communicating with the base of the tion of such reverse flow sets during the startingcarburetor, and the top of the carburetor comup period by causing a jet of suitable gas, prefmunicating with the top of the superheater so erably steam, to flow upwardly through the stack that flow takes place up through the carburetor concurrently with the opening of the charging and down through the superheater, just the redoor for admission of fuel into the generator, the

verse of the dircetion of flow in conventional carjet being at least sufiiciently powerful to overcome l5 buretted water gas equipment. This novel water the draft exerted on the carburetor and supergas set is disclosed and claimed in United States heater by the escape of volatiles through the Patent No. 2,118,096, granted May 24, 1938, and charging opening in the generator and that exwill be hereinafter referred to as the Reverse erted by the superheater on the stack so that conflow water gas set. In the operation of such currently with the escape of volatiles evolved reverse flow water gas sets it was found that upon charging through the charging opening of during the starting up periods pops or explosions the generator, gas present in the carburetor and would occur, particularly within the carburetor superheater flows through the stack and entry of and at times in the superheater; Such pops or air through the stack is effectively prevented.

Z5 explosions are objectionable, not only because Thus, in accordance with my invention, the opthey have a deleterious efiect upon the refracerations would involve cycles each consisting of tory lining and brickwork within the carburetor an air blasting Step alter at ng with water s and superheater, but also they indicate that exmaking steps involving the passage of steam plosive mixtures of gas are formed'within the through the fuel bed, and at intervals,say, after set during the starting-up period which upon every five or more cycles, the opening of the ignition might cause an explosion of suiiicient charging door, t e charging of fuel, which y intensity to destroy the water' gas set. The probbe coal or coke, into the generator, and the conlem of preventing the'formation of such explosive current passage of steam through the stack mixtures within the set has received the attenthroughout the charging operation, and while the tion of gas engineers, but, to my knowledge, no charging door is open, the steam pressure being satisfactory solution thereof has been found prior suilicient to create a draft in the stack greater y invention than the draft exerted on the carburetor by the I have discovered the occurrence of explosions escape of volatiles in the generator and also by in the water. gas set while introducing fuel into the downfiow superheater.

w the generator and during the starting-up period By the starting-up period as used in the o is caused by the tendency of the gases evolved specification and claimsismeant the period comin the generator upon charging to rise through mencing with a cold set, one in which the temthe open fuel charging inlet and create abackperature in the superheater is at atmospheric or draft through the carburetor, superheater and room temperature, or at a substantially higher stack, thus causing air to be drawn through the temperature due to long standby period in which stack valve and form explosive mixtures in the no gas has been made, which temperature may set; the mixtures explode when they are raised to be below 1,000 F., and terminating when the set ignition temperature by the hot refractory matehas been operated and until the temperature at rial in the set. The tendency of the hot gases the top of the superheater is from l250 to 1300 evolved in the generator during charging to cause F. and at the bottom of the superheater is from so the entry of air into the set through the stack 1,000 to 1100 F. For a standard water gas set valve in the reverse flow set, I believe, is aughaving a generator, the internal diameter of mented by the draft exerted by the downfiow which is 10 feet and completely enclosed in a superheater on the open stack valve, i. e. the natbuilding or other housing maintained at or about 5 ural tendency of. hot gas to rise within the super- F., the period required for startin'g up a set is may be about 2 hours for a set at atmospheric temperature or 30 minutes for a set in standby condition. In the case of a set in which the superheater is not housed within a building so that it is subjected to atmospheric influence, the starting-up period will obviously be much longer.

The process of this invention will be more fully described in connection with theaccompanying drawing, which discloses a preferred embodiment of a water gas set in which the process may be carried out.

Referring to the drawing wherein like reference numerals indicate like parts, there is shown a water gas set comprising a generator l, car-" buretor 2, and superheater 3. The carburetor is elevated so that. its base is substantially in the same horizontal plane with the outlet I of the generator and this outlet communicates with the inlet 5 to the carburetor by a refractory lined passageway 3. Generator I is equipped with the usual grate I for supporting a bed of fuel such as coal or coke and a fuel charging opening 8 adapted to be closed by a suitable closure 8' and is equipped with air inlets 9, H disposed beneath the grate and above the top of the fuel bed respectively. The generator I has a steam inlet l2 disposed beneath the grate for supplying steam thereto. An oil spray l3 leads into the top of the generator above the fuel bed to supply oil, which may be heavy oil such as Bunker C oil, during the gas making step, if desired.

-The carburetor 2 rests on a suitable structural steel support l4 andmay be provided at its base with two or more layers of refractory material l5 such as checkerbrick disposed on arches l8 positioned at the bottom of the carburetor. The portion of the carburetor above the oil spray is unobstructed throughout its horizontal cross sectional area. A water cooled oii spray I1 is located at the top of the carburetor, preferably on the vertical axis thereof and is arranged to supply oil, which may be gas oil or heavy oil such as residuum or Bunker 0 oil, to the carburetor during the water gas making steps in a direction countercurrent to the upward flow of water gas through the carburetor. A header l8 provided with downwardly directed pipes; I9 is arranged to supply secondary air to the base portion of the carburetor. The top ofthe carburetor has a gas outlet 2| leading into the top of the superheater 3.

Checkerbrick 23, which may be of the type disclosed and claimed in United States Patent No. 1,927,834 granted September 26, 1933, conipletely fills the superheater 3 and rests on arches 24 disposed at the base of the superheater. Gas outlet 25 of the superheater leads into a vertical refractory lined stack 26 provided at its top with stack valve 21; the stack valve may be opened and closed by any suitable means such as a hydraulic cylinder (not shown) connected thereto by link 21'. The stack preferably is of a height somewhat greater than the height of the superheater so'that, as shown in the drawing, stack valve 21 is disposed above the top of the superheater and constitutes the highest point of the set.

A conduit 23 leads from a point near the top of the stack 26 into a valve casing 29, which in turn communicates by pipe 3| with a wash box 32. Backrun line or conduit 33 leads from the base of the generator beneath the grate into valve casing 29. The valve casing 23, aswell known in this art, is provided with a three-way valve for reversing flow through the set, i. e. in

'above indicated, communicates with the superheater. The various valves of the set maybe operated manually or automatically in any desired manner to.carry out the steps of the watergas cycle, e. g. the valves may be operated by hydraulic cylinders controlled from a control nest as well known in this art.

In accordance with the invention, I provide a steam injector 31 extending upwardly into the stack adjacent the upper end thereof and communicating through pipe 33 with a suitable steam supply, e. g. a steam boiler. The injector is equipped with valve 39 having an operating member 40 connected by pivoted link ll to the stack valve so that opening and closing the stack valve results in simultaneous opening and closing of the injector valve.

Steam pipe 33 is provided.

with manually operated valve 33' to shut off the supply of steam to the injector when it is desired to open the stack valve without permitting steam to flow through the injector.

The process of this invention may be carried out in the apparatus herein described as follows: In starting up the cold set which may be at room temperature the fuel is first introduced into the generator. After combustion of a portion of the fuel in the generator so that the fuel bed is heated to a temperature of 1200 F. air is passed through the fuel bed and the resultant blast gases passed up through the carburetor, secondary air admitted through l9 and the mixture burned as it flows-up through the carburetor and down through the superheater, the blast gases passin through the stack valve 21 which is open connection 28 to wash box 32. This step may be of about two minutes duration.

The uprim may be followed by a backrun during which steam is introduced into the stack through steam inlet 35 and is preheated as it fiows through the stack, superheater and carburetor, backrun water gas being withdrawn from the base of the generator through backrun pipe 33. The backrun step may be of about one-half minute duration for the first few cycles.

The blast, uprun and backrun, with the usual purges, constitute a complete cycle. After about five or more cycles the fuel bed may be replenished or, if desired, the fuel bed may be replenished more or less often. During the addition of fuel, in accordance with this invention, the

stack valve is open and steam admitted through 39 at a pressure suflicient to create a draft which opening 3 so as to prevent the entry of air through sta k valve 21.

The temperature'in the superheater gradually rises during each succeeding cycle of the process. When the temperature at the top of the superheater reaches about 1300 F. and at the bottom of the superheater about 1100 F., i. e. when the end of the starting-up period has been reached, it will generally not be necessary to continue the introduction of steam in the stack during the charging periods. Valve 39' in the steam line 38 may then be closed so that on continued opera tion of stack valve 21 valve 39 is operated by levers 40, 41, but no steam enters the stack because of the closing of valve 39. I

Since changes may be made without departing from the scope of the invention, it is intended that the above description should be interpreted in an illustrative and not in a limiting sense. I claim:

1. In the process of operating a carburetted water gas set involving a generator containing a bed of fuel, which is replenished from time to time through a charging inlet located at the top of the generator, a carburetor and superheater connected in series, the top of the generator communicating with the base of the carburetor and the top of the carburetor communicating ,with the top of thesuperheater, so that flow takes place up through the carburetor and down through the superheater, and a stack connected with the bottom of the superheater for flow therethrough, which process comprises repeated cycles, each cycle involving the step of blasting the fuel bed with air and burning the blast gases in the carburetor and superheater, alternating with the step of making water gas by passing steam through the fuel bed and passing the resultant water gas through the carburetor and superheater, the improvement which comprises at intervals between successive cycles of steps during the starting-up period of operation of the set, charging the fuel bed with fuel, and concurrently with the introduction of fuel into the generator, placing'the stack in communication with the atmosphere and introducing a jet of gas upwardly into the stack during the charging of the generator.

2. In the process of operating a carburetted water gas set involving a generator contaimng a bed of fuel, which is replenished from time to time through a charging inlet located at the top of the generator, a carburetor and superheater connected in series, the top of the generator communicating with the base of the carburetor and the top of the carburetor communicating with the top of the superheater, so that flow takes place up through the carburetor and down through the superheater, and a stack connected with the bottom of the superheater for flow therethrough, which process comprises repeated cycles, each cycle involving the step of blasting the fuel bed with air and burning the blast gases in the carburetor and superheater, alternating with the step of making water gas by passing steam through the fuel bed and passing the re-,

sultant water gas through the carburetor and superheater, the improvement which comprises at intervals between successive cycles of steps charging the fuel bed with fuel, and concurrently with the introduction of fuel into the gas upwardly into said stack while replenishing steam upwardly in the stack to create an upwardly draft in the stack which draft more than counterbalances the draft caused by the escape of volatiles in the generator, thereby preventing entry of air into the set through the stack during the charging of the fuel into the generator, and continuing the aforesaid introduction of steam into the stack during the charging periods until the temperature at the top of the superheater is from 1200 to 1300 F. and at the bottom of the superheater is from 1000 to 1100 F., and thereafter during repeated cycles discontinuing the introduction of steam into the stack during the charging periods.

3. In a process of manufacturing carburetted water gas in a water gas set involving a generator containing a bed of incandescent fuel adapted to be replenished from time to time through a charging inlet located at the top of the generator, a carburetor and a downflow superheater connected for now therethrough of water gas and blast gases from said generator up through the carburetor and down through the superheater and a stack connected to said superheater and having,a closure adapted to be opened while said generator fuel bed is being replenished, the improvement which comprises introducing a jet of said generator fuel bed thereby preventing gases rising in the generator creating backdraft in and drawing air into said set and forming explosive mixtures therein.

4. In a process of manufacturing water gas in a set involving a generator containing a bed of incandescent fuel adapted to be replenished from time to time through a charging inlet located at the top of the generator, a downfiow superheater connected for flow therethrough of water gas and blast gases from said generator down through said superheater and a stack connected to said superheater, the improvement which comprises introducing a jet of gas upwardly into said stack while replenishing said generator fuel bed, thereby preventing gases rising in the generator from drawing air into said stack and forming explosive mixtures in said set.

5. In a process of manufacturing carburetted water gas in a water gas set involving a generator containing a bed of incandescent fuel adapted to be replenished from time to time through a charging inlet located at the top of the generator, a carburetor, a superheater and a stack connected in series for flow therethrough of gases from said generator up through the carburetor, down through the superheater, and up through the stack, the improvement which comprises introducing a Jet of steam upwardly into the stack gases when replenishing=said generator fuel bed while the temperature of said stack gases is not high enough to impart sumcient buoyancy to the gases therein to counteract the tendency of the generator gases rising through the fuel charging inlet to create back draft in the set, thereby preventing air from being drawn into said stack

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