US1948536A - Heating system - Google Patents

Description

Feb. 27, 1934. w G NQACK 1,948,536

HEATING SYSTEM Original Filed March 1. 1929 2 Sheets-Sheet 1 l i 17 25 (U) 66 J1 1 67 I l 1 1 5 25 75 1 I I I W. G. NOACK Feb. 27, 1934.

HEATING SYSTEM Origifial Filed March 1, 1929 2 Sheets-Sheet 2 Patented Feb. 27, 1934- PATENT OFFICE HEATING SYSTEM Walter Gustav Noack,

Baden, Switzerland, as- I signor to Aktiengesellschaft Brown Boveri & Cie, Baden, Switzerland, a joint-stock company of Switzerland Application March 1, 1929, Serial No. 343,746, and in Germany March 19, 1928. Renewed May 26, 1933 25 Claims.

This invention relates to heating systems and it has among its objects the provision of an improved heat generating and exchanging system, and more particularly, a steam generator, in which the fuel is burned under pressure, as in a pressure-proof combustion chamber, and the pressure in the chamber is utilized to impart to the'combustion gases a high velocity across heat exchange surfaces holding a steam generating fluid to transfer thereto the major portion of the heat in the combustion gases.

The foregoing system of heat exchange and steam generation secures eflicient operation with greatly reduced space and cost requirements, as miles with greater simplicity compared with the systems used heretofore.

The foregoing and other objects of the invention will be best understood from the accompanying drawings, wherein Fig. 1 is a diagrammatic vertical sectional view illustrating one exemplification of the invention;

Fig. 2 is a view similar to Fig. 1 illustrating a modification of the invention;

Fig. 3 is a view similar to Fig. 1 showing another form of the heat exchange and apparatus;

Fig. 4 is a transverse sectional view along the line IV-IV of Fig. 3.

In the steam generators made according to the invention, a combustible mixture is subjected to combustion under pressure, or explosion in a closed pressure-proof combustion chamber. The pressure of the combustion gases so obtained is utilized to impart to the combustion gases a high velocity across heat exchange surfaces, for transferring the major part of the heat in the gases to boiler water or other medium to be heated held by said heat exchange surfaces.

For efficient transfer of heat from the combustion gases to the fluid held by the heat exchange surfaces it is important that the gases shall pass across said surfaces at high velocity. The increase of the velocity of the gases is made as large as practically feasible and the gases are discharged with velocities which-may even exceed the velocity of sound. At such high velocities the transfer of the heat to the heat exchange surfaces takes place at such a high rate that the heat exchange surfaces reach quickly a high temperature, and because of their mass, they retain this high temperature after the combustion gases have expanded and dropped down in temperature. Accordingly, if the explosions or combustion periods follow quickly one after another, it may happen that the gas tubes or heat exchange surfaces have a temperature which is only very little below, or even higher, than the temperature of the expanded gases passing along said surfaces. In such cases the remainder of the combustion heat within the gases cannot be transferred to the medium to be heated, and, as a matter of fact, the opposite may take place, the heat exchange surfaces may return heat to the passing gases.

Among the objects of the present invention is an arrangement which avoids these difiiculties. According to the invention, the steam generator, for instance, is so arranged as to have two separate heat exchange bodies, either steam generating bodies or preheaters, or the like. One of these bodies is arranged to be traversed by the hot high-pressure combustion gases, this highpressure or high-temperature unit being, for convenience, designated as the first stage unit. The second heat exchange body is arranged to be traversed by the low-pressure combustion gases, after their expansion, this low-pressure or low-temperature unit being designated, for convenience, as the scond stage unit.

Through the arrangement of two expansion stages in the form of a high-temperature highpressure heat exchanging device and a second low-temperature low-pressure heat exchanging device, there is always maintained a temperature gradient of proper direction between the combustion products and the heat exchange surfaces along which they pass. I avoid in this way the difficulties of having the heat exchange surfaces that were brought to high temperature by the highly compressed expanding combustion gases then brought into contact with the lowtemperature low-pressure gases during the later period of the expansion.

A steam-generator embodying the foregoing principles and arranged so that the several parts maybe manufactured and assembled as separate and independent units, is shown in Fig. 1. It comprises a steam separator drum 11 which is partially filled with water. The drum is provided with a steam dome 12 and has the usual water gauge 13 and safety valve 14. Steam is derived from the drum by a steam outlet pipe 15. The water is heated and the steam is generated by means of an explosion-type combustion heater 16 shown in the drawing below the drum. The heater comprises a combustion chamber 17 and a heat exchanging device 18. The combustion chamber 17 has the form of a pressure-proof elongated cylinder 21 having at one end a tapered inlet wall 22 with an inlet opening 23 communicating through an inlet valve 24 with a I pump 52 included in the pipes, the water being" combustion gas inlet chamber 25 that is connected through a gaseous fuel feed pipe 26 to a compressor 27 by means of which the combustible gas is compressed for charging the combustion chamber 17. The inlet valve 23 may be of any of the well known types of inlet valves, such as used in explosion-type engines, and its closure and opening may be controlled by any of the known means therefor.

In the drawings the valves are indicated as being of the hydraulic control type and having a hydraulic control cylinder 28, this general type of valve control being, for instance, widely employed in the steam turbines manufactured by the assignee of the present application and being described in the publication of the Brown Boveri Company of January, 1926, entitled "Die Regelung Der Brown Boveri Damf Turbine".

At the end opposite the inlet 22, the combu tion chamber 17 is provided with an outlet duct 31' having two outlet openings 32 and 33 to which is connected the heat exchanging device 18. The heat exchanging device is shown consisting of two separate heat exchangers 34, 35. Each heat exchanger comprises an elongated tubular water container 36 traversed by a set of gas discharge pipes 37 which are secured within the two end walls. The container 36 of the heat exchangers is arranged to be filled with water or other medi-.

um that is to be heated, the combustion gases passing through the gas discharge tubes 37 in heat exchange relation thereto. This arrangement secures the flow of water or the fluid medium in a thin layer adjacent the heat exchange surfaces, resulting in efficient heating or steam generation. I

One of the heat exchangers 34 is mounted over the opening 32 in the gas discharge duct, and the other of the heat exchangers is mounted over the opening 33 of the gas discharge duct 31, this discharge duct serving as an inlet into the gas discharge tubes 37 of the heat exchangers. At the outlet end of said tubes the heat exchangers are connected to a gas outlet 41 which is provided with a valve unit 42 having two outlet openings 43 and 44 communicating with the outlet ends of the gas discharge tube 37 of the two heat exchangers 34 and 35. The outlet openings 43 and 44 are controlled by outlet valves 45 and 46 which may be controlled in a way similar to the inlet valve 23. From the outlet duct 41 the discharge gases may be passed into an exhaust turbine 47 driving a turbine rotor 47 which impels the compressor 27.

0f the two heat exchangers 34, 35 the first is arranged to be used as the first stage or highpressure high-temperature unit, while the second is arranged to be used as the second stage or lowpressure low-temperature unit.

A water circulating system is provided between the separator drum 11 and the heat exchangers. The water from the drum is conveyed to the hightemperature heat exchanger 34 by means of pipes 51 and is maintained in circulation by means of a heated in the heat exchanger and returned with the generated steam through a pipe 53, the steam separating and rising in the drum 11. Very efficient steam generation may thus be obtained by circulating the water at a high rate. The feed water is arranged to be supplied from a feed wa-' ter pipe 55 through a feed water pump 56 to the low-temperature stage heat exchanger 35 from whence it may be passed either directly into the separator drum 11 or into other preheaters, or as The operation' of the system of Fig. 1 is as fol-'- lows:

The combustion chamber 17 is charged with a combustible mixture through the inlet valve 24. To this end the air or combustion gases are compressed by the compressor 27 up to a certain pressure and charged into the combustion chamber 17, the fuel being added to the air of the combustion charge either before entering into the compressor or, while charging it, into the combustion chamber 17. Either gaseous fuel or powdered coal or fluid fuel, or the like, may be used. After charging the combustion chamber 17, the mixture is ignited by some suitable means, for instance, by spark plugs 61 as shown. In order to maintain the pressure of the combustible charge produced by the compressor 27 and secure a high combustion pressure, the outlet valves 45 and 46 are closed during the final period of compression and during explosion. After the combustion has been nearly carried out, the outlet valve 45 of the high-temperature heat exchanger 34 opens first and releases the highly compressed high-temperature combustion gases through the heater pipes 37 of the heat exchanger. The pressure produced by the combustion is almost entirely imparted to the gases and is converted into high velocity averaging about 200 meters per second or more. The high temperature and density of the gases combined with their velocity secure an extremely high rate of heat transfer through the heater pipes 37 to the water surrounding the same. Because of this high rate of heat flow, the gas discharge pipes heat up quickly and reach soon a temperature that is higher than the temperature of'the combustion gases,near the end period of their expansion.

The low-temperature heat exchanger 35 serves to derive as much as possible heat from the combustion gases during the later period of expanman. To this end the outlet valve 46 of this low-temperature heat exchanger 35 opens after the expanding gases in the combustion chamber 17 have dropped to a relatively low pressure, for instance, to the pressure produced by the compressor' 27. The remaining gases of the 'combustion chamber 17 are thereupon discharged through this low-temperature heat exchanger 35, being driven out by either anew combustible charge or by a charge of scavenging air. These combustion gases escaping through the second heat exchanger 35 have a lower temperature and come in contact with walls that are cooler than the walls in the high-temperature heat exchanger 34, providing thus a temperature, drop which permits the transfer of the heat remaining in said gases to the fluid medium circulating through the second heat exchanger. Since the pressure during this period is much lower than during the period of gas discharge through the high temperature heat exchanger 34, the velocity of the combustion gas flow through the gas tubes of low-temperature heat exchanger 35 will be also lower, being kept as high as possible; pref erably at an average value of about 150 meters per second or more. i

In the drawings, the gases discharged from the two heat exchangers are shown flowing pressure produced by the compressor.

exchanger with a separate exhaust turbine for each or with an exhaust turbines only for the high-temperature heat exchanger. In this gas turbine the remaining energy of the gases is converted into mechanical power for compressing the combustible charge.

The two heat exchangers are used for heating water of different temperatures. Thus, the hightemperature heat exchanger 34 is used for heating of the water which has already been preheated and brought near to the temperature of steam generation, the water being circulated as shown by the circulating pump 52. The low-temperature heat exchanger 35 is used for heating relatively colder water, for instance, fresh or slightly preheated feed water. The efilciency of the high-temperature heat exchanger is maintained by circulating the water or fluid at high velocity so that the steam bubbles developed therein are carried with it and do not separate until after reaching the boiler drum 11.

If the temperature of the feed water is brought by the low-temperature heat exchanger 35 to a sufficiently high value, it may be directly mixed with the circulating water through the connection 62 between the two heat exchangers.

Instead of heating the water that is to be converted into steam directly, an intermediate heating fluid of high boiling point may be used.

The gases flowing through the low-temperature heat exchanger 35 have a greater specific volume and .also a lower velocity than those flowing through the high-temperature heat exchanger 34. In order to secure as short as possible a discharge period, the flow cross-section in the low temperature exchanger is made relatively larger than the corresponding section in the high-temperature exchanger. This is of very great advantage and may be secured either by using a larger number of gas discharge tubes or by using tubes of larger cross-section.

As shown, each heat exchanger has its separate discharge outlet valve. The control of these valves should be so arranged that the high-pressure discharge valve opens when the combustion or explosion is almost near its end, and that the low-pressure discharge valve opens after the expansion has been nearly completed, for instance, after the gases have reached approximately the The highpressure valve is preferably closed while the low-pressure valve 46 is open. However, the high-pressure valve may be left open during the entire discharge process and closed with the lowpressure valve immediately preceding the new charge. The actuation of the valves is effected automatically by a suitably driven control shaft, such as described in my copending applications, Serial No. 333,453, and Serial No. 343,745. It should be arranged so that the sequence of the combustion processes shall be regulated in accordance with the conditions in the system, such as the pressure in the steam boiler. This is indi cated in the drawings through the arrangement of an oil pressure pipe which supplies the oil pressure for operating the valves 24, 45 and 46 through valve pipes 66. The opening and 010- sure of the inlet valve 24 is controlled through a controlling device 67 by a regulator 68 in accord ance with the condition of the steam in the boiler tank 11 so as to increase or decrease the speed of the combustion cycles. The opening and closure of the outlet valves 45 and 46 is controlled by control devices '71, '72 which are operated by a temperature or pressure gauge '73 responsive tothe conditions in the combustion chamber 17 so as to open at the proper times. These control and regulating devices may be of any of the familiar types, for instance, they may be electrically operated, such arrangement being indicated in the drawings. The controlling devices of the inlet and outlet valves may be suitably interlocked as by an interlocking circuit 75.

Since the heat exchangers are active only during a period of time, each heat exchanger may be used in connection with several combustion chambers, for instance two combustion chambers may be used in connection with two heat exchangers, each combustion chamber discharging first through the high-temperature heat exchanger and then through the low-temperature heat exchanger, the discharge periods of the two heat exchangers being set back against each other by one-half of the cycle. The two discharge valves of each heat exchanger open then one after another so that each heat exchanger is alternately traversed by the combustion products of the two combustion chambers. Such arrangement is shown in Fig. 2 of the drawings in which the parts are otherwise like those in the plant shown in Fig. l.

The high-temperature or high-pressure heat exchanger may be combined with the low-pressure heat exchanger into a single unit. In such arrangement the water paths, as well as the gas flow path, are separated by suitable partition walls. Such combined heat exchanger is shown in Figs. 3 and 4. It has the form of a cylindrical tank 81 which is divided into an upper part 82 and a lower part 83 by a horizontal partition wall 84. The upper part constitutes the high-pressure exchanger and carries a set of gas discharge pipes 85 of relatively small diameter. The lower part 83 serves as a low-pressure heat exchanger and is provided with gas discharge pipes 86 of relatively large diameter. The high pressure discharge gases enter into the discharge pipes 85 at the inlet 87 and leave at the outlet 88. The low pressure gases enter into the low pressure discharge pipes 86 at the inlet 89 and leave at the outlet 90. The water for the high-pressure heat exchanger enters at 91 and leaves at 92, while that for the low-pressure heat exchanger ente'rs at 93 and leaves at 94. Y

The above described heat generating and exchanging systems are particularly advantageous when used in combination with an exhaust turbine, as shown in the drawings. As a driving medium for the exhaust turbine is used energy left in the gases of combustion after they leave the gas tubes of the heat exchangers 34 and 35. In order to maintain such operation of the exhaust turbine, the heat exchange surfaces and the free cross-section of the discharge nozzles of the turbine must be so designed that the exhaust gases shall have sufficient energy for driving the compressor, or any other auxiliary machinery.

It will, however, happen that changes in the load, or other irregularities, may reduce the energy reaching the gas turbine below the amount sufficient for supplying the required mechanical power. According to the invention, the second or low-temperature low-pressure heat exchanger 35 is used to remedy such conditions by actuating the low-pressure outlet valve 46 like an overload valve. The arrangement is such that if, for instance, the speed of the compressor drops, a suitable regulating device causes the low-pressure'outlet valve 46 to open somewhat earlier discharging gases of higher pressure and temperature into the gas turbine through the now enlarged outlet cross-section increasing the pressure and temperature of the gases supplied to the turbine. In this Way the desired increase of output of the gas turbine is obtained.

An arrangement for securing such operation of the boiler plant is indicated in Fig. 1, a speedresponsive regulator 101 actuated by the shaft of the turbine rotor 47 being shown connected through conductors 102 to the control device 72 of the low-pressure outlet valve 46. This regulator may be of any of the familiar forms used in electrical apparatus and is arranged to cause earlier opening of the valve 46 if the speed of the turbine rotor drops, and to delay the opening of the valve if the speed of the turbine rotor increases.

Instead of a single combustion chamber several combustion chambers may be used, the exhaust gases of all the combustion chambers op erating a single gas exhaust turbine which drives the compressor that supplies the compressed air for the combustion chamber. In such case, a single separator drum 11 may be used for all of the combustion chambers.

The present invention is directed only to the features of my invention disclosed and claimed herein involving the special arrangements of combustion chamber and heat exchangers and their operation. The novel apparatus for and methods of steam generation disclosed above in connection with the exemplifications of my invention embody many other novel features for causing high temperature compressed combustion gases to discharge at high velocity over a small evaporator structure and generate steam at a high rate as described and claimed in my copending applications, Serial No. 333,453 filed January 18, 1929, Serial No. 640,025 filed October 28, 1932, Serial No. 343,745 filed March 1, 1929, Serial No. 414,428 filed December 16, 1929, Serial No. 419,026 filed January '7, 1930, and Serial No. 558,260 filed August 20, 1931.

Many other modifications of the invention will suggest themselves to those skilled in the art and it is accordingly desired that the appended claims be given a broad construction commensurate with the scope of the invention within the art.

Iclaim:

1. In a heater system, a combustion chamber for subjecting a combustible mixture to combustion under high pressure, a plurality of heat exchangers, and means operatively connected with the combustion chamber for discharging the combustion gases from said chamber first through one of said heat exchangers and then from said chamber through another of said heat exchangers.

2. In a heater system, a combustion chamber for subjecting a combustible mixture to combustion under high pressure, a high-temperature heat exchanger, a relatively low-temperature heat exchanger, and means operatively connected with the combustion chamber for discharging the combustion gases formed in said chamber first through the high-temperature heat exchanger and upon reduction of the pressure within said chamber to discharge the remaining gases through the relatively low-temperature heat exchanger.

3. A heater system comprising a combustion chamber, means for periodically subjecting to combustion a combustible charge in said chamber to produce combustion gases of higher temperature and higher pressure than said charge, a plurality of heat exchangers, means operatively connected with the combustion chamber for discharging the high-pressure combustion gases from said chamber through one of said heat exchangers, and means for discharging the relatively low-pressure combustion gases from said chamber through another of said heat exchangers.

4. A heater system comprising a combustion chamber, means for subjecting to combustion a combustible charge in said chamber to produce combustion gases of high temperature and high pressure, a plurality of heat exchangers constituting stages of different temperature, and means operatively connected with the combustion chamber for discharging the gases of combustion from said chamber through said heat exchanger stages so that the high-temperature gases fiow to the high-temperature heat exchanger stages and the low-temperature combustion gases remaining in said combustion chamber after the discharge of the high-temperature combustion gases are discharged through the low-temperature stages.

5. A steam generator comprising a combustion chamber, means for subjecting a combustible charge to combustion in said chamber to produce combustion gases of high temperature and high pressure, a high-temperature heat exchanger holding a relatively high-temperature steam generating fluid, a low-temperature heat exchanger holding a relatively low-temperature steam gencrating fluid, and means operatively connected with the combustion chamber for releasing the combustion gases from said chamber to flow first through said high-temperature heat exchanger and then from said chamber through said low temperature heat exchanger in heat exchange relation with said fluid.

6. In a steam generator, a combustion chamber, means for subjecting a combustible charge to combustion in said chamber under high pressure, a high-temperature heat exchanger, a low-temperature heat exchanger, means operatively connected with said combustion chamber for discharging the high-temperature combustion gases from said chamber through said high-temperature heat exchanger, means operatively connected with said combustion chamber for discharging the low-temperature combustion gases from said chamber through said low-temperature heat exchanger, means for passing a high-temperature steam generating fluid in heat exchange relation through said high-temperature heat exchanger, and means for passing a relatively low-temperature steam generating fluid through said lowtemperature heat exchanger.

7. In a steam generator, a container system with steam generating fluid, a combustion chamber, means for periodically subjecting a combustible charge to combustion in said chamber to produce combustion gases of high temperature and higher pressure than said charge, a high-temperature heat exchanger, a low-temperature heat exchanger, means operatively connected with said combustion chamber for-discharging after each explosive combustion the high-temperature combustion gases from said chamber through said high-temperature heat exchanger, means operatively connected with said combustion chamber for discharging after each explosive combustion the relatively low-temperature combustion gases from said chamber through said low-temperature heat exchanger, means for passing through said high-temperature heat exchanger steam generating fluid from said container system that is near steam generating fluid from said container system that is of relatively lower temperature than the fluid passing through said high-temperature heat exchanger.

8. In a steam generator, a combustion chamber, means for subjecting a combustible charge to combustion in said chamber to produce combustion gases of high temperature and high pressure, a high-temperature heat exchanger carrying a high-temperature steam generating fluid, a low-temperature heat exchanger carrying a low-temperature steam generating fluid, means operatively connected with said combustion chamber for discharging the high-pressure combustion gases from said chamber through said high-temperature heat exchanger to generate steam from the fluid carried therein, and means operatively connected with said combustion chamber for discharging relatively lower pressure combustion gases from said chamber through said low-temperature heat exchanger to preheat the fluid carried therein, said lowtemperature heat exchanger having a gas discharge cross-section greater than said hightemperature heat exchanger.

9. In a heater system, a combustion chamber, means for subjecting a combustible charge to combustion under pressure in said chamber, heat exchangers, means operatively connected with said combustion chamber for discharging the high-pressure combustion gases through a relatively small discharge area in said heat exchangers, and means operativelyconnected with said combustion chamber for discharging the relatively lower pressure combustion gases from said chamber through a relatively larger discharge area in said heat exchangers.

10. In a heater system, a combustion chamber, means for subjecting a combustible charge to combustion to produce combustion gases of high pres-.

sure in said chamber, a high-temperature heat exchanger, a low-temperature heat exchanger, and valve means operatively connected with said combustion chamber for causing the high-temperature gases from said chamber to pass through said high-temperature heat exchanger and for causing the relatively lower temperature gases from said combustion, chamber to flow through said low-temperature heat exchanger.

11. In a heater system, a combustion chamber, means for subjecting a combustible charge to combustion to produce combustion gases of high temperature and high pressure in said chamber, a high-temperature heat exchanger, a low-temperature heat exchanger, valve means for causing gases from said chamber to flow through said high-temperature heat exchanger, valve means for causing gases from said chamber to flow through said low-temperature heat exchanger, and means responsive to the conditions in said chamber for controlling the operation oi. said valve means.

12. In a heater system, a combustion chamber, means for subjecting a combustible charge to combustion in said chamber to produce combustion gases of high temperature and high pressure, a high-temperature heat exchanger, a. lowtemperature heat exchanger, valve means for causing gases from said chamber to flow through said high-temperature heat exchanger, valve means for causing gases from said chamber to flow through said low-temperature heat exchanger, and means responsive to the conditions in said chamber for controlling said valve means to cause the high-temperature gases from said combustion chamber to flow through said hightemperature heat exchanger and to cause the low-temperature gases from said combustion chamber to flow through said low-temperature heat exchanger.

13. In a heater system, a combustion chamber, means 'for periodically subjecting a combustible charge to combustion in said chamber to produce combustion gases of high temperature and higher pressure than said charge, a high-temperature heat exchanger, a low-temperature heat exchanger, means for discharging the combustion gases from said chamber through said heat exchange means, and means responsive to the conditions within said chamber for controlling the discharge of gases from said chamber through said heat exchange means to cyclically discharge the high pressure gases of each combustion through the high temperature heat ex changer and the low pressure gases of each combustion through the low temperature heat exchanger.

14. In a heater system, a plurality of heat exchangers, a plurality of combustion chambers, means for subjecting combustible charges to combustion in said chambers to produce combustion gases of high temperature and high pressure, and means for cyclically discharging the combustion gases from said chambers through said heatexchangers so that the highpressure combustion gases of several combustion chambers flow through a common high-temperature heat exchanger and the low-pressure combustion gases of several combustion chambers flow through a common low-temperature heat exchanger.

15. In a heater system, a combustion chamber, means for subjecting a combustible charge to combustion in said chamber to produce combustion gases of high temperature and high pressure, a high-temperature heat exchanger, a low-temperature heat exchanger, means for discharging high-pressure gases from said chamber through said high-temperature heat exchanger, means for discharging relatively low-pressure gases from said chamber through said low-temperature heat exchanger, motor means for utilizing the exhaust gases from said heat exchangers, and means responsive to the load conditions of said motor for regulating the discharge of gases through said low-temperature heat exchanger.

-16. A heating system comprising a combustion chamber, means for subjecting a combustible charge to combustion in said chamber to produce therein combustion gases of high temperature and high pressure, a heat exchanger having a set of gas discharge ducts for receiving and passing combustion gases, additional combustion gas receiving means, and means operatively connected to said chamber to discharge the high pressure combustion gases from said chamber through said set of ducts and upon reduction of the pressure within said chamber to stop the discharge of the gases from said chamber through said ducts and to discharge the low pressure combustion gases from said chamber into said additional combustion gas receiving means, said heat ducts at which the major part of the heat present in the produced gases is transferred through the surfaces of said ducts while said gases flow at high velocity.

17. A steam generator comprising a combustion chamber, means for subjecting a combustible charge to combustion in said chamber to produce therein combustion gases of high temperature and high pressure, a heat exchanger having a set of gas discharge ducts for receiving and passing combustion gases, means for passing a steam generating fluid through said heat exchanger around said ducts, additional combustion gas receiving means, and means operatively connected to said chamber to discharge the high pressure combustion gases from said chamber through said set of ducts and upon reduction of the pressure within said chamber to discharge the low pressure combustion gases from said chamber into said additional combustion gas receiving means, said heat exchanger and the associated elements being so arranged in relation to said combustion chamber that the pressure of the combustion gases imparts to said gases a velocity of about 150 meters per second or more through said ducts to transfer the heat of said gases to the surrounding fluid to generate steam 18. A steam generator comprising a combustion chamber, means for periodically exploding a combustible charge in said chamber to produce therein combustion gases of high temperature and higher pressure than said charge, a heat exchanger having a set of gas discharge ducts for receiving and passing combustion gases, means for passing a steam generating fluid through said heat exchanger around said ducts, additional combustion gas receiving means, and means operatively connected to said chamber to cyclically discharge after the explosion the high pressure combustion gases from said chamber through said set of ducts and upon reduction of the pressure within said chamber to discharge the low pressure combustion gases from said chamber into said additional combustion gas receiving means, said heat exchanger and the associated elements being so arranged in relation to said combustion chamber that the pressure of the combustion gases imparts to said gases a velocity of about 150 meters per second or more through said ducts.

19. A heating system comprising a combustion chamber, means for subjecting a combustible charge to combustion in said chamber to produce therein combustion gases of high temperature and high pressure, a heat exchanger having a set of high pressure gas discharge ducts for heating a high-temperature fluid surrounding said ducts and a set of low pressure gas discharge ducts for heating a relatively low-temperature fluid surrounding said ducts, and means operatively connected to said chamber for first discharging the high pressure combustion gases from said chamber through said high pressure duct set and upon reduction of the pressure within the chamber to discharge remaining low pressure gases through said low pressure duct set, said high pressure ducts and the associated elements being so arranged in relation to said combustion chamber that the pressure of the combustion gases imparts to said gases a velocity per second or more of about 200 meters through said ducts.

20. A heating system comprising a combustion chamber, means for periodically exploding a combustible charge in said chamber to produce there- 'in combustion gases or high temperature and higher pressure than said charge, a heat exchanger having a set of high pressure gas discharge ducts for heating a high-temperature fluid surrounding said ducts and a set of low pressure gas discharge ducts for heating a relatively low-temperature fluid surrounding said ducts, and means operatively connected to said chamber for cyclically discharging after the explosive combustions the high pressure combustion gases from said chamber first through said high pressure duct set and upon reduction of the pressure within said chamber to discharge remaining low-pressure combustion gases through said low pressure duct set, said high-pressure ducts and the associated elements being so arranged in relation to said combustion chamber that the pressure of the combustion gases imparts to said gases a velocity of about 200 meters per second or more through said ducts.

21. A steam generator comprising a steam separator vessel, a combustion chamber, means for subjecting a combustible charge to combustion in said chamber to produce therein combustion gases of high temperature and high pressure, a heat exchanger having a high pressure set of gas discharge pipes and a low pressure set of gas discharge pipes, for heating a low-temperature fluid surrounding said pipes, means operatively connected to said chamber for discharging the high pressure combustion gases from said chamber first through said high pressure discharge pipes and then upon reduction of the pressure within the chamber to discharge remaining low pressure combustion gases through said low pressure discharge pipes, and means for passing preheated high-temperature steam generating fluid around said high pressure gas pipes to'said separator vessel to generate steam in said fluid and separate it in said vessel, means for passing lowtemperature steam generating fluid around said low pressure gas pipes to preheat said fluid, said heat exchanger and the associated elements being so arranged in relation to said combustion chamber that the pressure of the combustion gases imparts to said gases through said highpressure set of gas pipes a velocity of about 200 meters per second or more.

22. A steam generator comprising a steam separator vessel, a combustion chamber, -means for periodically exploding a combustible charge in said chamber to produce therein combustion gases of high temperature and higher pressure than said charge, a heat exchanger having a high pressure set of gas discharge pipes and a low pressure set of gas discharge pipes means operatively connected to said chamber for cyclically discharging after each explosive combustion the high pressure combustion gases from said chamber first through said high pressure discharge pipes and then upon reduction of the pressure within the chamber to discharge remaining low pressure combustion gases through said low pressure discharge pipes, said heat exchanger and the associated elements being so arranged in relation to said combustion chamber that the pressure of the combustion gases imparts to said gases through said high-pressure set of gas pipes a velocity of about 200 meters per second or more.

23. The method of operating a steam generator comprising a combustion chamber, a high-temperature heat exchanger and a low-temperature heat exchanger, which comprises subjecting a combustible mixture to combustion under pressure in said combustion chamber and discharging the high-temperature combustion gases produced in said chamber through said high-temperature ne ates heat exchanger and upon drop of the temperature of the combustion gases in said chamber, discharging the low-temperature combustion gases through said low-temperature heat exchanger instead of through said high-temperature heat exchanger.

24. The method of operating a steam generator comprising a combustion chamber, a high-temperature heat exchanger and a low-temperature heat exchanger, which comprises periodically exploding a combustible charge in said combustion chamber to produce combustion gases of high temperature and higher pressure than said charge, and cyclically discharging after each explosion, the high pressure combustion gases from said chamber through said high-temperature heat exchanger and upon reduction of the pres sure in said chamber, discharging the remaining low-pressure combustion gases from said chamber through said low-temperature heat exchanger.

25. The method of operating a steam generator comprising a combustion chamber, a high-temperature heat exchanger having heat exchange surfaces in the form of ducts surrounded by a high-temperature steam generating fluid to be heated, and a low-temperature heat exchanger having heat exchange surfaces in the form of ducts surrounded by a low-temperature steam generating fluid to be preheated, which comprises periodically exploding a combustion charge in said combustion chamber to produce combustion gases of high temperatureand higher pressure than said charge, and cyclically discharging after each explosion, the high pressure combustion gases produced in the chamber through the ducts of said high-temperature heat exchanger at a velocity of about 200 meters per second or more, and upon reduction of the pressure in said combustion chamber to discharge the gases therein instead of through the ducts of the high-telnperature heat exchanger, through the ducts of the low-temperature heat exchanger.

WALTER GUSTAV NOACK.

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