US2751286A - Gasification apparatus with metallic water jacket nozzle for steam - Google Patents

Description

June 19, 1956 F. TOTZEK 2,751,286

GASIFICATION APPARATUS WITH METALLIC WATER JACKET NOZZLE FOR STEAM Filed Aug. 11, 1951 INVENTOR. FQ/EOQ/(H 7277229 6 yavm 14 Tree/v5 Y GASIFICATION APPARATUS WITH METALLIC WATER JACKET NOZZLE FOR STEAM Friedrich Totzek, Essen (Ruhr), Germany, assignor, by

mesue assignments, to Koppers Company, Inc., Pittsburgh, Pa., a corporation of Delaware Application August 11, 1951, Serial No. 241,413

9 Claims. (Cl. 48-=-=67) This invention relates to the production of valuable combustible gases by the gasification of finely divided fuels, particularly finely divided solid fuels, initially with oxygen and subsequently with steam, the fuel being suspended in the gaseous medium during the reaction and moving in substantially the same direction therewith. Such a gasification process is frequently referred to as gasification in suspension.

In order to obtain by gasification in suspension a gas of high calorific value with a good yield it is above all necessary for the fuel to react with the oxygen as far as possible only according to the equation 2C+O2:2CO. In a preferred method of carrying out the gasification in suspension this is achieved by pre-forming outside the gasification or reaction chamber an homogeneous mixture of the finely divided fuel, for example finely pulverized coal, and oxygen, or oxygen-enriched air, and then introducing this pro-formed mixture in the form of one or more jets with such a speed through nozzle-like openings into the reaction chamber, operating at increased temperature, that the mixture ignites not earlier than within the reaction chamber and reacts according to the aforesaid equation.

The temperatures thus produced are very high. At present there is no refractory material which solely of itself is economically available and capable of simultaneously withstanding these high temperatures and, the attack of the fuel ash remaining from the gasification. On the other hand it is not possible to form the walls of the reaction chamber completely of water-cooled metal surfaces, as is normally done in water gas and producer gas generators, since such cooled metal surfaces absorb too much heat and the temperature in the primary zone would thereby be lowered to such an extent that the high speed of reaction necessary for the gasification in suspension is no longer obtained.

According to an earlier suggestion of the inventor in U. S. application Ser. No. 43,950 filed August 12, 1948, steam, preferably superheated steam, is introduced into the intermediate space between the primary reaction zone and the reaction chamber walls, in such a manner that there is formed in the said intermediate space a cohesive shell or veil or envelope of co-currently flowing steam enclosing the primary reaction zone. This envelope of steam has two different functions. It serves primarily to maintain in the reaction chamber or in that zone of the reaction chamber in which the temperatures still lie above the fusing point of the fuel ash, such flow conditions which will prevent a movement of the ash particles towards the reaction chamber walls and contact of the same with the ash particles. On the other hand the steam envelope absorbs a certain amount of heat from the primary zone, resulting in further superheating of the steam and a corresponding reduction of the temperature of the walls, but this heat in contrast to the heat assumed by cooled chamber walls-is not lost to the gasification process but it is utilized to form valuable water-gas according to the equation C-l-HzO Hz-i-CO.

Patented June 19, 1956 It has been found that the practical operation of a gas producer for the gasification in suspension essentially depends on the fact that described special flow conditions are accurately maintained as far as possible in the intermediate space between the primary zone and the reaction chamber walls. If, for instance, a premature diversion or destruction of the steam envelope takes place, then undesirably large quantities of steam can pass into the primary reaction zone and impede the reactions taking place there, while on the other hand, mineral ash residues meet the refractory walls of the reaction chamber causing solid deposits or slags or the formation of some eutectic mixtures with the refractory material.

The supposition for favorable flow conditions in the reaction chamber of the gasification in suspension is, therefore, the suitable structure of the nozzle-like inlets for the solid fuel reaction media and the steam to be introduced for forming the steam envelope about the primary zone.

As a rule, the inlet openings for the fuel are arranged centrally in the reaction chamber or in the main axis thereof and the inlet opening for the stream of'steam serving to form the steam envelope, in the form of an annular nozzle which surrounds the inlet of the fuel or the gasification media reacting exothermically therewith.

Hitherto, this annular steam inlet nozzle was constructed of a high quality of ceramic or refractory material which withstood the high temperatures of the primary reaction zone. It is, however, diflicult to manufacture from ceramic material annular nozzles, particularly those of large diameter, all of one piece and simultaneously maintain the exact shape therein in operation which is required in the present case. Moreover, when such ceramic members are heated, particularly when heated on one side only, strains are formed which alter the structure to a greater or lesser degree. Thus, for example, the original smooth surface of the brick member which is most favorable for a laminar flow becomes rough after a certain period of heating.

With a deeper penetration on such change to a rough structure cracks and flakes finally form, completely changing the cross section of the nozzle.

Even the roughening of the surface leads to a turbulent flow in the marginal layers of the flow of steam which consequently mixes too early with the reaction media of the primary reaction zone and impedes the desired course of the gasification operations. Such disturbances take place to a greater extent with flaking or displacement in the steam nozzle, particularly if this is made in combining a number of parts, as is unavoidable with larger plants.

According to the invention, the disadvantages referred to are avoided by providing water-cooled metal surfaces, in which the annular inlets for the various constituents of the reaction, particularly the steam, can be constructed in the desired profile with suflicient accuracy and durability, in order to form the limits of the reaction chamber along the inlet of the gasification media, while the remainder, of the reaction chamber walls are otherwise made from a refractory ceramic material.

Surprisingly, it was found that at the region along the side of the region of entry for the reaction media, the reaction chamber walls can be formed of water-cooled metal surfaces without thereby producing noticeable or measurable heat losses. This discovery Was not to be immediately foreseen having regard to the unfavorable influence of heat consumption by the walls of the reaction chamber. This surprising fact is based essentially on the phenomenon that the primary reaction zone shows heat radiation practically only from the marginal layers beyond the inlets, lying in the direction of flow, while the heat radiation from the back of the primary reaction zone, that is, from the base of the combustion zone to wards the inlet nozzles of the gasification media is only, at the most, small.

The invention is preferably carried into effect by connecting the inlet nozzles for fuel and oxygen on the one hand, and for the steam which serves for the formation of the steam envelope on the other hand, to separate cooling systems. It is preferable to keep the inlet of the fueloxygen mixture to the lowest possible temperature in order to counteract a hack flow of the exothermic reaction from the primary reaction zone into the feed lines. On the other hand, the annular inlet nozzles for steam are with advantage maintained at a higher temperature corresponding or adapted to the superheating of the steam, which is achieved by separate cooling systems for the corresponding nozzle systems. For example, the steam nozzle may be cooled with water at increased pressure or possibly be connected with a cooling circuit in which circulates a molten metal or the like.

The end wall, constructed according to the invention, of the reaction chamber preferably constructed in the form of a truncated cone, has the great advantage that the profile of the inlet nozzles can also be completely maintained during a longer operation period. Deposits, for example of fuel dust particles cannot form on the cooled metal surfaces. It is also an advantage that this part of the reaction chamber when constructed in metal or steel presents a considerably smaller surface than when a ceramic construction is employed for the nozzle parts, since it is well known that ceramic materials can only be made with a relatively large wall thickness having regard to the specific properties of the materials. This relative decrease in the surface provides a further advantageous decrease in the heat losses at this point which, as has been found, amounts to practically less than O.8l.0% of the heat content of the fuel to be gasified.

The annular nozzle serving for the introduction of the current of steam is, according to a further important characteristic of the invention, preferably constructed in the manner of a venturi, the angle of divergence and the merging of which into the end surface of the central fuel-oxygen inlet is to be chosen so that all media flow into the reaction chamber in, as far as possible, a parallel stream without turbulence of the marginal layers.

The drawing illustrates two forms of construction of the invention.

Fig. 1 shows the construction of the invention with a water cooled nozzle for the steam in which the inner and outer annular nozzle walls are cooled on both sides by a separate cooling system.

Fig. 2 shows another form of the nozzle in which the walls of the annular steam nozzle are partly formed by the cooling jacket of the central fuel-oxygen nozzle, that is, the inner all.

In the apparatus according to Fig. l the gasification reaction takes place in the reaction chamber 1 widening conically in the direction flow and whose walls are formed of refractory material. The end wall of the rc action chamber 3 in which lie the inlets for the gasification media is formed of water cooled metal surfaces.

The fuel dust-oxygen mixture is injected centrally through, for example, three water cooled nozzle pipes 3. The water cooled nozzle pipes 3 are connected in such a manner with a cooling system (not shown on the drawing), that cooling water is introduced near the end protruding into the reaction chamber through, for example, an inner pipe and the heated cooling Water flows away rearwardly. (See Fig. 2.)

The nozzle pipes 3 are surrounded by the annular steam nozzle 4, the inner terminal walls of which, as indicated at 5 andfi, are made hollow forming cooling jackets. To the two jackets 5, 6 there is supplied a cooling medium, for example, water at increased pressure, through the pipes 7 and 8, while the heated water flows away through pipes 9 and 10 respectively. The annular nozzle 4 is formed in profile in the manner of a venturi. superheated steam is supplied to it from the rear through the passage 11 and the distributing passages 12.

In the example of construction just described with reference to Fig. 1, the annular nozzle 4, surrounding the central nozzle 3 for the fuel-oxygen mixture, and which nozzle 4 serves to form the envelope of gaseous medium, is bounded both at its inner as well as its outer face by separate cooling jackets which serve only to cool the annular nozzle 4 and are independent of each other as regards the cooling medium.

Surprisingly, it has been found that a sufficient cooling of the annular nozzle 4 for the envelope-forming gas can still be produced if there is provided as the outer boundary surface of the annular nozzle, as previously stated, a separate cooling jacket provided only for the annular nozzle 4, but the inner boundary surface of the annular nozzle, however, is formed by the cooled jacket of the central nozzle 3 for the fuel-oxygen mixture which has to be provided in any case for the fuel-oxygen mixture. The advantage of this form of construction according to the invention, lies in the simpler construction of the building elements forming the annular nozzle and in the omission of one of the two cooling medium circuits for the annular nozzle required hitherto, with the structure of Fig. 1.

Fig. 2 shows an example of the construction of this form of the nozzle head. The gasification chamber 21, the walls of which are formed of refractory material 22, widens conically in the direction of flow of the reaction media.

The fuel-oxygen mixture is injected centrally through, for example, three water cooled nozzle pipes 23 into the reaction chamber. The cooling medium for the central nozzle enters through conduit 33, is led. through a pipe into the vicinity of the end of the nozzle extending into the reaction chamber and leaves the nozzle through conduit 34.

The central nozzle 23 is surrounded by an annular nozzle 24 which is connected by an annular passage 32 with a supply pipe 31 for, for example, superheated steam. The outer boundary surface of the annular nozzle 24 forms a cooling jacket 26. Through this cooling jacket there flows a cooling medium, for example, water at increased pressure. The cooling medium is delivered at 27 and flows away again at 29.

The inner boundary surface of the annular nozzle 24 is formed by the water cooled pipe 23 of the central nozzle for the fuel-oxygen mixture. In this Way the second cooling system for the inner boundary surface of the annular nozzle 24, hitherto necessary with Fig. 1, is avoided and the entire construction of the nozzle head is simplified.

Instead of steam, it is possible in some circumstances to introduce a gaseous medium, for example, a part of the useful gas produced, in the production of gas according to the invention, for example, when it is desired to produce a gas With a small hydrogen content or a gas free from hydrogen. The introduction of this other gaseous medium must, however, be effected in accordance with the same principles as described above with steam, that is, the primary reaction zone must be enclosed by an envelope-as complete as possibleof the flowing gaseous medium.

i claim:

1. An apparatus for the production of combustible gases by the gasification of finely-divided fuel comprising a ceramic-lined gasification chamber, inlet means located at one end thereof, said inlet means comprising centrallydisposed nozzle means adapted to inject axially into said gasificationcharnber a stream of finely-divided fuel suspended in a free oxygen-containing gas, a first fluid-cooied annular metal member surrounding said centrally-disposed nozzle means, a second fluid-cooled annular metal member surrounding said first annular metal member and spaced therefrom to form therebetween an annular nozzle for the introduction of an endothermic gasifying agent, a portion of the inner wall of said second annular metal member adjacent said chamber being disposed at an acute angle to the axis of said chamber and with respect to the direction of gas flow in divergent relationship with said was.

2. The apparatus of claim 1 in which each of said annular members comprises a chamber and means for passing a cooling fluid through each chamber.

3. The apparatus of claim 1 in which independent cooling means are provided for each of said annular metal members.

4. The apparatus of claim 1 in which the first annular member is adapted to cool the centrally-disposed nozzle means.

5. The apparatus of claim 1 in which the centrally disposed nozzle projects into the gasification chamber.

6. The apparatus of claim 5 including cooling means for said centrally-disposed nozzle means, said centrallydisposed nozzle cooling means being independent of the cooling means for said annular metal members.

7. An apparatus for the production of combustible gases by the gasification of a finely-divided fuel comprising a ceramic-lined gasification chamber, inlet means located at one end thereof, said inlet means comprising centrally-disposed nozzle means adapted to inject axially into said gasification chamber a stream of finely-divided fuel suspended in a free oxygen-containing gas, a first fluid-cooled annular metal member surrounding said centrally-disposed nozzle means, a second fluid-cooled annular metal member surrounding said first annular metal member and spaced therefrom to form therebetween an annular nozzle for the introduction of an endothermic gasifying agent, a portion of the inner wall of said second annular metal member adjacent said chamber being disposed at an acute angle to the axis of said chamber and said annular nozzle having a decreasing cross-sectional area to a point of minimum cross-sectional area and then an increasing cross-sectional area in the direction of gas flow.

S. The apparatus of claim 7 in which the decreasing cross-sectional area is continuously decreasing and the in creasing cross-sectional area is continuously increasing.

9. The apparatus of claim 8 in which a venturi-type nozzle is formed by said first and second annular metal members.

References Cited in the file of this patent UNITED STATES PATENTS 952,372 Speer Mar. 15, 1910 1,402,464 Winkelman a- Jan. 3, 1922 1,438,032 Frost Dec. 5, 1922 1,617,074 Matlock Feb. 8, 1927 1,814,097 Seil July 14, 1931 2,114,738 Heller Apr. 19, 1938 2,341,682 Andrews Feb. 15, 1944 FOREIGN PATENTS 664,950 Germany Aug. 25, 1938

Claims (1)

1. AN APPARATUS FOR THE PRODUCTION OF COMBUSTIBLE GASES BY THE GASIFICATION OF FINELY-DIVIDED FUEL COMPRISING A CERAMIC-LINED GASIFICATION CHAMBER, INLET MEANS LOCATED AT ONE END THEREOF, SAID INLET MEANS COMPRISING CENTRALLYDISPOSED NOZZLE MEANS ADAPTED TO INJECT AXIALLY INTO SAID GASIFICATION CHAMBER A STREAM OF FINELY-DIVIDED FUEL SUSPENDED IN A FREE OXYGEN-CONTAINING GAS, A FIRST FLUID-COOLED ANNULAR METAL MEMBER SURROUNDING SAID CENTRALLY-DISPOSED NOZZLE MEANS, A SECOND FLUID-COOLED ANNULAR METAL MEMBER SURROUNDING SAID FIRST ANNULAR METAL MEMBER AND SPACED THEREFROM TO FORM THEREBETWEEN AN ANNULAR NOZZLE FOR THE INTRODUCTION OF AN ENDOTHERMIC GASIFYING AGENT, A

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