US1903292A - Explosion tubbinb - Google Patents

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Patented Apr. 4, I933 UNITED STATES PATENT OFFICE HOIIZ'WABTH, OI" D'USSELDOBI' GERMANY, ASSIGNOB TQ HOLZWAB'IE GAB TURBINE 00., OF SAN FRANCISCO, CALIFORNIA, A OOBPORLTION O! DELAWARE EXPLOSION TURBINE Application filed Iebruu'y 8, 1929, Serial 10.

by means of coal dust, and more particularly but a continuous turbine 0 for effecting self-ignition of a coal dust and air mixture in the explosion chambers of such turbine.

Among the known internal combustion engines designed to employ coal dust as a fuel, those which effect ignition of the fuel in ,a manner similar to the Diesel process, that is, by injectin the coal dust into a body of hot compresse air in the combustion chamber, appear to have led to the first practical success; on the other hand, ordinary piston engines have not yet'been operated successfully with coal dust and air under self-ignition of the mixture. Many attempts have been made to efiect the combustion of coaldust-air mixtures in combustion turbines. It has been observed that the combustion of the mixture in the combustion chamber may be initiated by means of an electric spark, ration could not be attained as the combustion is in such case a very slow one, so that only low speeds could be obtained which were insuflicient to make the arrangement practical.

I have found that the rotational speed of the turbine can be raised to the point necessary to maintain the continuous operation of the same if a coal-dust-air mixture is introduced into the turbine under conditions which will efi'ect self-ignition. I have found that self-ignition of the fuel mixture is promoted by certain arrangements of parts in the combustion space which are at a higher'temperature than the surrounding arts, and that thereby a satisfactory regu arity and constancy in the self-ignition of the periodically charged mixture can be obtained. The parts which are to be kept at a higher temperature than their surroundings (the latter'term is to be understood to mean all the walls and parts which bound the combustion space) may, for example, be uncooled while the surrounding elements may be cooled, or these parts .may be inserted Within the bordering Walls of the combustion chamber as separate pieces so that the air space, which is present even when the fitting is exact, prevents the 837,084, and in Germany Il'ebruary 15, 1828.

flow of heat from these parts 'to the adjoining cooler elements of the combustion chamber. These parts may also be separately heated in the manner of incandescent heads, glowin spirals, etc. I

11 order to insure correct adjustment and proper control of the moment of ignition, I arrange suitable materials in the combustion space at such places that during the operation of the explosion chambers they assume a temperature suflicient to cause ignition of the fuel and-air mixtures, such materials having possibly also a catal ic action which favors rapid and comp ete combustion. Such materials are most suitably located in the neighborhood of those parts of the combustion chamber at which self-ignition, as experience has shown, is most favored or is initiated-experiments with piston explosion engines have shown that self-ignition does not proceed from the center of the body of gas-and may be advantageously supported 'upon catch surfaces of all kinds or introduced into roughenin grooves, undercuttings and so forth, in t ose parts of the combustion chamber which are at a higher temperature than their surroundings. I have determined that particularly those bodies serve as efiicient igniting bodies which possess very large superficial area'in a small volume of material. I have found that substances such as finely divided ashes or slag, which have a large superficial area for a unit of volume and are incombustible, possess the necessary action and are, moreover, not difficult to make. As the fine coal dust of the coal dust and air mixture exploded in the combustion chamber on combustion produces extremely small ash and slag particles,

bastion chamber at which the igniting mate- I rial is able to exert its action most favorably, and particularly those parts which are or can be maintained at a higher temperature than their surroundings, with devices such as Patented Apr. 4, I933 UNITED ST TES PATENT OFFICE HOLZWABTH, OI" DUSSELDORi' GERMANY, ASSIGNOB '10 HOLZWABTE GAB TURBINE 00., OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OI DELAWARE EXPLOSION TUBIBINE Application filed February 5, 1929, Serial No.

by means of coal dust, and more particularly for effecting self-ignition of a coal dust and air mixture in the explosion chambers of such turbine.

Among the known internal combustion en-, gines designed to employ coal dust as a fuel, those which efi'ect ignition of the fuel in a manner similar to the Diesel process, that is, by injectin the coal dust into a body of hot compressed air in the combustion chamber, appear to have led to the first practical success; on the other hand, ordinary piston engines have not yet'been operated successfully with coal dust and air under self-ignition of the mixture. Many attempts have been made to effect the combustion of coaldust-air mixtures in combustion turbines. It has been observed that the combustion of the mixture in the combustion chamber may be initiated by means of an electric spark, but a continuous turbine o ration could not be attained as the combustion is in such case a very slow one, so that only low speeds could be obtained which were insuflicient to make the arrangement practical. v

I have found that the rotational speed of the turbine can be raised to the point necessary to maintain the continuous operation of the same if a coal-dust-air mixture is introduced into the turbine under conditions which will eifect self-ignition. I have found that self-ignition of the fuel mixture is promoted by certain arrangements of parts in the combustion space which are at a highertemperature than the surrounding parts, and that thereby a satisfactory regu arity and constancy in the self-ignition of the periodically charged mixture can be obtained. The parts which are to be kept at a higher temperature than their surroundings (the latter'term is to be understood to mean all the walls and parts which bound the combustion space) may, for example, be uncooled while the surrounding elements may be cooled, or these parts may be inserted within the bordering walls of the combustion chamber as separate pieces so that the air space, which is present even when the fitting is exact, prevents the 837,084, and in Germany Iebruary 15, 1928.

flow of heat from these parts to the adjoining cooler elements of the combustion chamber. These parts may also be separately heated in the manner of incandescent heads, glowin spirals, etc. I

n order to insure correct adjustment and proper control of the moment of ignition, I arrange suitable materials in the combustion space at such places that during the opera tion of the explosion chambers they assume a temperature suflicient to cause ignition of the fuel and air mixtures, such materials having possibly also a catal ic action which favors rapid and comp ete combustion. Such materials are most suitably located in the neighborhood of those parts of the combustion chamber at which self-ignition, as experience has shown, is most favored or is initiated-experimen ts with piston explosion engines have shown that self-ignition does not proceed from the center of the body of gasand may be advantageously supported upon catch surfaces of all kinds or intro duced into roughenin grooves, undercuttings and so forth, in t ose parts of the combustion chamber which are at a higher temperature than their surroundings. I have determined that particularly those bodies serve as efiicient igniting bodies which possess very large superficial areaiin a small volume of material. I have found that substances such as finely divided ashes or slag, which have a large superficial area for a unit of volume and are incombustible, possess the necessary action and are, moreover, not difficult to make. As the fine coal dust of the coal dust and air mixture exploded in the combustion chamber on combustion produces extremely small ash and slag particles,

I provide measures whereby such ash and slag granules are caught and deposited u on a suitable art of the combustion cham r, such granu es upon solidification producing a body of highly active igniting material. I accordingly provide those parts of the combustion chamber at which the igniting mate- I rial is able to exert its action most favorably, and particularly those parts which are or can be maintained at a higher temperature than their surroundings, with devices such as catch surfaces, grooves, rougheningp, undercuttings and so forth into which t e ash or slag particles roduced by the combustion preci itate. e deposit so produced durmg e operation 0 the turbine exerts a favorable influence upon the initiation and the course of the combustion. In order that no unnecessarily large deposits may take place, the arts designed to carry the same are prefera 1y arranged in those sections of the chamberwherein the gases flow with great violence so that the portion of the deposit which is not positioned directly upon or only a short distance from the catch surfaces, i. e. in the grooves, undercuttings and so forth, is blown or burnt away by the stream of combustion gas.

Instead of generating the igniter deposit I from the operating coal dust used to generate the combustion gases employed to operate the turbine rotor, the same may be produced by means of an auxiliary and separate combustible coal dust and air mixture which is blown against the 'hot art or parts of the combustion chamber ad zipted to receive the same. The coal dust in this mixture is preferably more finely divided than that of the o crating mixture and also richer in volati, e matter. This auxiliary mixture, after the body of igniting material has been deposited, may be employed, if desired, to ignite the operating mixture in the combustion chamber. To this end, jets of such auxiliary mixturerare directed at predetermined moments against the igniter-carryin surface and self-ignited on contact with suc igniter, the flame so produced causing explomom or rapid combustion of the charge in the combustion chamber. In this way the advanta e is obtained that by controlling the auxi iary mixture completely independently of the operating coal-dust-air mixture, sharply defined self-ignitions of the periodic charges of such operatin mixtures can be obtained at arbitrarily a justable moments.

If no artificially produced igniters (i. e. produced outside the combustion chamber and manually positioned therein) are disposed in the combustion chamber, but instead only the conditions are observed which favor the formation of the igniter out of the operating or auxiliary combustible mixtures as by suitable arrangement of hot elements of the combustion chamber which are formed to receive a deposit of igniting material and trates b way of example several embodiments of m invention, and particularly of the heated e ements located in the combustion space, Fig. 1 shows diagrammatically a partial section through a turbine combustion chamber and nozzle valve; Fig. 2 illustrates an enlarged section of the nozzle valve head shown in Fig. 1; Fig. 3 is a partial lon tudinal section through an explosion tur ine provided with a nozzle valve of the iston type, and Fig. 4 is an enlarged detail of ig. 3.

F i 1 shows an explosion chamber a provide with the usual jackets for cooling the same. Valves b are arranged at the inlet end of the combustion chamber and are adapted to be controlled in well-known manner to charge the several operating media, such as scavenging air, charging air, operating fuel, starting fuel, etc., eriodically and in proper sequence. A nozz e valve 0 controls the communication between the interior of the combustion chamber a and the nozzle channel d, which latter conducts the explosion (gases to a nozzle e disposed opposite the bla es of the turbine rotor 7 located in the tur ine housing It. The head or plate 0 of the nozzle valve 0 is located in the path of the combustion gases as they stream out of the combustion chamber into the channel (1 upon opening of the valve. This valve head is consequently exposed to very hot gases during the operation of the turbine, and unless specially cooled reaches a temperature above that of the surrounding parts of the combustion chamber. The cooling of this valve head is, however, difiicult and cooling arrangements therefor are rather com licated.

In accordance with tiie present invention, the cooling of the nozzle valve head is omitted and the same thus permitted to attain a temperature higher than that of its surroundings. This element is advantageously located for such purpose because of the fact that it is positioned at a point at which the combustion gases flow very rapidly and is therefore struck most violently by such gases.

As indicated above, ash and slag, such as are deposited by an exploded mixture of coal dust and air, when heated to a high temperature, are capable of causing self-ignition of combustible mixtures of coal dust and air, such deposit of ash and slag having a large surface area per unit volume and probably aiding catalytically the combustion of the fuel and air. I have found that the face of the nozzle valve head which is struck by the stream of combustion gases as they issue from the explosion chamber is highly ada ted to support a mass of such ash and slag. 0 this end I may provide the face of the nozzle valve head with undercut surfaces 0, as shown at the right of Fig. 2, which provide a suitable clinging surface for a layer of igniter material 2' produced in any desired manner. The bottom face of the valve head may,

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