US2453928A

US2453928A - Thermal power plant

Info

Publication number: US2453928A
Application number: US674450A
Authority: US
Inventors: Oechslin Konrad
Original assignee: Aktiengesellschaft fuer Technische Studien
Current assignee: Aktiengesellschaft fuer Technische Studien
Priority date: 1945-06-22
Filing date: 1946-06-05
Publication date: 1948-11-16
Anticipated expiration: 1965-11-16
Also published as: FR929489A

Description

Nov. 16, 1948. K. OECHSLIN 3 THERMAL POWER PLANT Filed June 5. 1946 35 Fig.3

lnvenkor I Konrhd Occhs'lin Adorn dye Patented Nov. 16, 1948 THERMAL POWER PLANT Konrad Oechslin, Zurich, Switzerland, assignor to Aktiengesellschait Fuer Technische Studien, Zurich, Switzerland, a corporation of Switzerland Application June 5, 1948, Serial No. 674,450 In Switzerland June 22, 1M5

8 Claims. 1

This invention relates .to a thermal power plant in which at least the greater part of a gaseous working medium describes a cycle, this part being heated by a supply of heat from an outside source, then expanded in at least one turbine while giving up energy externally, and afterwards brought again to a higher pressure in at least one compressor, an exchange of heat taking place in a heat exchanger between the expanded and compressed currents of working medium before heat is supplied to the re-compressed part.

In thermal power plants of this kind it is usual to erect the heat exchanger separately from the turbine and the compressor, in which case the necessary connecting pipes can be laid above or underground. In such plants the losses of pressure in the pipes affect, as is well known, the degree of efilciency of the plant to a considerably higher extent than is the case in other thermal power plants such as steam turbines for example. It consequently becomes necessary, in plants of the kind hereinabove described, to make the velocity at which the working medium flows through the pipe small, so that the connecting pipes between the heat exchanger and the end of the turbine on the outlet side on the one hand and between the heat exchanger and the end of the compressor on the inlet side on the other hand will have to be of comparatively large dimensions. In addition to this there is the fact that the temperature of the working medium flowing from the turbine into the heat exchanger amounts ordinarily to at least 350 C. so that the control of the thermal expansions to which in particular a connecting pipe of comparatively.

large diameter and heated also to very nearly the temperature mentioned is subjected between the turbine and the heat exchanger, causes great difliculties. These are eliminated according to the present invention by the fact that the heat exchanger is built directly on to the end of the turbine on the outlet side and that the cross sectional area of the outlet end of the turbine casing merges, practically without change, into the cross section of the heat exchanger at which admission is to take place. The heat exchanger may also be conveniently built directly on to the end of the compressor on theinlet side, in which case the cross sectional area of the outlet from the heat exchanger casing can merge, with practically no change, into the cross sectional area of the inlet to the compressor casing. In such case connecting pipes between the heat exchanger and the turbine on the one hand and between the heat exchanger and the centrifugal compressor on the other hand may be entirely dispensed with.

The subject matter of the present invention is of inventive importance. Firstly, this is because in consideration of the special case involved the thermal expansions of the pipes set the designer practically insoluble problems so that the elimination of these difllculties constitutes a technical improvement. Moreover, losses by radiation from the pipes between the turbine and the heat exchanger do not occur at all in a type of construction according to this invention, as no pipe at all is needed, as stated, between these parts of the plant. The direct building of the heat exchanger on to the turbine also enables deflec-' tion of the working medium to be avoided as it flows over into the heat exchanger, so that the velocity at which the working medium flows through the turbine and the velocity at which it leaves this latter may be high. This enables the limit output of the turbine to be raised. The new type of construction also permits of an extremely convenient guiding of the flow of the working medium, in as much as no losses due to deflection and to the passage through pipes occur between the turbine, the heat exchanger and the turbocompressor, whichis of very special importance in thermal power plants for which this invention is intended. When the present invention is employed a direct and full admission of the working medium to the eflective surfaces of the heat exchanger is also secured. If the pressure at all points in the cycle of the plant is above atmospheric pressure, the turbine and the turbo-compressor will be small in comparison with the heat exchanger, so that this latter, owing to its great mass, can be used as a supporting element for the machines flanged on to it. This enables considerable economies in foundations and structural materials to be secured. The invention consequently permits, notwithstanding a smaller expenditure of structural materials, less weight, more compact construction and small foundations, conversion of the kinetic energy of the working medium issuing from the turbine with a better degree of efficiency than has hitherto been the case. For all the reasons mentioned I a thermal power plant according to the present invention is therefore particularly suitable for vehicles, ships for example, as in this case a small amount of space occupied and small weight with a good degree of efficiency play an important part.

Two constructional forms of the subject matter of the invention are illustrated by way of example in the accompanying drawing in which:

Fig. 1 shows the first constructional form partly in elevation and partly in vertical axial section.

Fig. 2 shows the second constructional form in plan. with parts in section and Fig. 3 is an axial longitudinal section to a larger scale on the line III-m of Fig. 1, showing details of the end of the turbine on the outlet side and of the parts of the heat exchanger built directly on to it.

In Fig. 1, i denotes the coil of a heater I in which heat is supplied from an external source to the working medium (preferably air) which passes through a closed cycle. The air brought to a higher temperature in this heater i passes into a two-casing turbine, in which it expands while giving up energy externally; The two series-connected turbines are denoted by the reference symbols 2 and 3. The turbine 2 drives an axial flow compressor 4 and the turbine 3 supplies energy to a receiver of useful output constructed as a generator 5. The expanded air passes out of the outlet-of the turbine 3, which outlet is constructed as a straight, annular diffuser 8, into a heat exchanger 1, which is constructed as a contraflow apparatus and is built directly on to this end of the turbine 3 in such a way that the cross sectional area of the outlet from the casing of the turbine 3 passes over, i. e. merges with practically no change into the cross sectional area of the heat exchanger to which the working medium is to be admitted. The system of pipes I built into the heat exchanger therefore is impinged by the air flowing out of the turbine 3 directly and the admission to said system is a full one, so that under favorable conditions said air gives up heat to the current of working medium under a higher pressure which is delivered by the axial flow compressor 4 through a pipe 3 into the above mentioned system of pipes 1 In this arrangement the diffuser 6 at the outlet end of the turbine 3 may be made of such dimensions that the current of air flowing out of it is slowed down in it to just the velocity which is desired to enable it to give up heat under the most favorable conditions in the heat exchanger 1. The part of the air which is cooled down in the latter by giving up its heat passes, after flowing through a cooler 3. which is built into the casing of the heat exchanger 1. into the turbo-compressor 4, in which this part of the air is brought again to a higher pressure after which it is delivered into the pipe 3 above mentioned. On its inlet side the compressor 4 is likewise built directly on to the heat exchanger 1, and a connecting member I provided between these parts 4 and I is shaped like a nozzle so that the air shall be slightly accelerated as it flows through, which is desirable for the correct admission thereof to the first guide apparatus of the compressor 4. In this case also the cross sectional area of the casing of the heat exchanger 1 merges with practically no change into the cross sectional area of the inlet to the casing of the compressor 4. Since the mass of the heat exchanger 1 is great in comparison with that of the turbine 3 and of compressor 4, the heat exchanger may serve as a supporting element for themachines 3 and 4 flanged on to it so that the supports and foundations for both the turbine 3 andthe turbo-compressor 4 may be of small dimensions and therefore cheap. The current of air which is delivered by the compressor 4 through the pipe 3 into theheat exchanger I,

passes out of this latter, after it has taken up heat in it, through a pipe Ii into the heater I again which completes the circuit of the cycle.

Since the heat exchanger 1 is built directly on to the end of the turbine 3 on the outlet side and also directly on to the end of the turbo-compressor 4 on the inlet side, pipes between the parts I and 3 on the one hand and between the parts 1 and 4 on the other hand may be dispensed with, which furnishes extremely favorable conditions in respect of condition of flow, losses in pressure and radiation and presents no particularly diflicult problems in thermal expansion.

In the type of construction shown in Fig. 2 both the turbine and also the heat exchanger are constructed with two casings. The two parts of the heat exchanger which are connected in series and communicate with each other at the right hand end through pipes i2, i3 are denoted by the reference symbols l4 and II. I3 is the air heater from which the heated air passes first into the high pressure turbine I! through a pipe l3 and then out of this latter through a pipe i'3 into the low pressure turbine 20. The turbines l1 and 23 are arranged on diflerent shafts, so that they can run at different speeds. In this case the turbine I1 drives a compressor 2i and the turbine 23 a receiver of useful output constructed as a generator 22. Into each of the parts l4 and II of the heat exchanger is built a system of pipes 23. ,The system of pipes 23 built into the part l4 oi the heat exchanger is connected at one end through a header 24 and a pipe 25 to the heater l8 and at the other end through the pipe i2 to the system of pipes 23 of the part I! of the heat exchanger. This second system of pipes 23 is also connected through a distributing chamber 26 and a pipe 21 to the pressure section of the compressor 2 I This latter and the low pressure turbine 20 are, in this case also. built directly on to the heat exchanger IS. the connection to the outlet end of the turbine 20, which connection is constructed as a straight annular diifuser 23, and the connection to the inlet end of the compressor 2|. which connection is constructed as a nozzle 23. being disposed on the same side of this heat exchanger l4. II. A cooler 30 is also built into the part I I of the heat exchanger between its left hand end face and the distributing chamber 23.

In the constructional form shown in Fig. 2 the working medium issuing from the low pressure turbine 20 passes at a speed which is determined by its diffuser-like outlet portion 23, along straight lines into the part i4 of the heat exchanger and meets the built-in system of pipes 23 at full admission, giving up heat meanwhile to the working medium flowing through this system of pipes 23 to the heater IS. The current of working medium which gives up heat then passes through the pipe l3 into the part II of the heat exchanger and finally, after having passed through the cooler 30, reaches the compressor 2i. where, prior to its entrance into the first guide apparatus of said compressor it has a certain amount of acceleration and also an even flow velocity imparted to it in the nozzle-like inlet part 23 of the compressor 2|. In this case also no pipes of any kind have to be provided between the low pressure turbine 20 and the part I4 of the heat exchanger on the one hand and between the part I! of the heat exchanger and the inlet end 23 of the compressor 2| on the other hand.

Fig. 3 shows the way in which a bearing 32 for the turbine shaft 34 can be built into a hub core member 33 arranged behind the last runner wheel 35 of the turbine. This hub core 33 is in its turn surrounded by a part of the turbine casing which is constructed as a straight, annular diffuser 3|.

What is claimed is:

1. Thermal power plant, in which a gaseous working medium describes a circuit, said plant comprising means by which heat from an external source is supplied to the working medium; at least two turbines connected in series and in which medium heated by said means expands; means whereby one of said turbines delivers power externally; a turbo-compressor arranged to be driven by the other of said turbines and interposed in said circuit so as to compress medium expanded in said turbines, and deliver it at higher pressure to said heat supplying means; and a heat exchanger constructed for longitudinal parallel heat-exchanging fiows in which medium after expansion through said turbines exchanges heat with medium flowing to said heat supplying means after compression by said turbocompressor, the discharge end of the second one of said series connected turbines being mounted directly on an end of said exchanger, the exchanger and said second turbine having housings which merge without substantial change of cross sectional area.

2. The combination defined in claim 1, in which the discharge end of the turbine connected with the housing of the exchanger is constructed as a straight annular diffuser.

3. Thermal'power plant, in which a gaseous working medium describes a circuit, said plant comprising means by which heat from an external source is supplied to the working medium; at least two turbines connected in series and in which medium heated by said means expands; means whereby one of said turbines delivers power externally; a turbo-compressor arranged to be driven by the other of said turbines and interposed in said circuit so as to compress medium expanded in said turbines, and deliver it at higher pressure to said heat supplying means; and a heat exchanger constructed for longitudinal parallel heat-exchanging fiows in which medium after expansion through said turbines exchanges heat with medium flowing to said heat supplying means after compression by said turbo-compressor, the discharge end of the second one of said series connected turbines and the inlet end of the exchanger, said second turbine and turbocompressor having housings which merge without substantial change of cross sectional area.

4. The combination defined in claim 3, in which the inlet end of the turbo-compressor is constructed as a nozzle.

5. The combination defined in claim 3, in which the exchanger housing serves also as a'supporting element for the connected turbine and for the turbo-compressor.

6. The combination defined in claim 3, in which the exchanger has a straight cylindrical housing, the high pressure turbine drives and is directly connected to the turbo-compressor and the low pressure turbine drives and is directly connected to a rotary machine which serves as the means for delivering power externally, the four units just specified being substantally coaxial with each other and with the exchanger, whereby symmetry with respect to the longitudinal axis is at least approximated and conditions favorable to use on ships are attained.

'7. The combination defined in claim 3, in which the exchanger is constructed with two casings side-by-side with connections which afford flows of the medium through the two in U-shaped paths between inlet ends which are proximate, whereby the said second turbine unit and the turbo-compressor are juxtaposed.

'8. The combination of the structure defined in claim 3 and a cooler of the surface type mounted in the path of medium entering the turbo-compressor and located substantially in the zone of mergence of the housings of the exchanger and compressor.

KONRAD OECHSIJN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 912,832 Oraker Feb. 16, 1909 1,743,759 Collingham Jan. 14, 1930 1,954,823 Lucke Apr. 17, 1934 2,392,823 Traupel Jan. 8, 1946 2,404,748 nn July 23, 1946