WO1997013961A1

WO1997013961A1 - Power generating system by use of fluid

Info

Publication number: WO1997013961A1
Application number: PCT/KR1996/000171
Authority: WO
Inventors: Jae Hwan Kim
Original assignee: Jae Hwan Kim
Priority date: 1995-10-07
Filing date: 1996-10-07
Publication date: 1997-04-17
Also published as: AU7340496A; JP2000509122A; EP0858552A1

Abstract

The invention relates to a power generating system by use of fluid including a turbine system and a refrigerating system to generate power by use of the energy of the fluid in the normal temperature without using any fuel and to reduce air pollution resulted from the combustion of fuel, wherein the refrigeration and liquefaction in a condenser (12) of a multiple-stepped turbine system is performed by a heat exchanger in an endothermic part of a refrigerating system which constitutes a coolant circulating circuit, an operating means of the refrigerating system is installed to mutually deliver power with a rotational axis of the turbine system, the rotational axis (7) of the turbine system has an electric motor (8) thereon which is driven by an external electric power supply, working fluid in a boiler of the turbine system exchanges heat with the external fluid in the normal temperature and with an exothermic part of the refrigerating system to be heated until the working fluid in the boiler is in a gaseous state above the critical temperature, the pressure in the boiler is raised to generate a little amount of the heat of liquefaction so that the working fluid in the condenser may be liquefied at temperatures slightly below the critical temperature, and as a result the heat of liquefaction of the working fluid in the condenser is low.

Description

POWER GENERATING SYSTEM BY USE OF FLUID

Background of the Invention

This invention relates to a power generating system comprising a turbine system and a refrigerating system, wherein the power is obtained by use of the heat from an external fluid in the normal temperature.

Conventional power generating systems are directed to obtain motive power or electric power from the heat generated in the course of combustion of fuel, so that the conventional systems have disadvantages that the fuel expense is high and they cause air pollution due to the combustion of fuel.

Brief Summarv of the Invention It is an object of the present invention to provide a power generating system by use of the energy of the fluid in the normal temperature, without using^' any fuel.

It is another object of the present invention to provide a power generating system which reduces air pollution resulted from the combustion of fuel.

Brief Description of the Drawings

The present invention will be described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic view showing the construction of a power generating system according to the present invention; Fig. 2 is a schematic view showing the power generating system according to an embodiment of the present invention;

Fig. 3 is a schematic view showing the power generating system according to another embodiment of the present invention;

Fig. 4 is a schematic view showing the power generating system according to a third embodiment of the present invention;

Fig. 5 is a schematic view showing an antifreezing solution evaporation means.

Fig. 6 is a schematic view showing another antifreezing solution evaporation means, and

Fig. 7 is a cross sectional view showing the construction of an evaporation means in Figs. 4 and 5.

Description of the Preferred Embodiments of the Invention

Referring to Fig. 1, the power generating system by use of fluid according to the present invention includes an electric motor 1 rotatable by an external electric power supply. The rotational force of the electric motor 8 drives a compression means 30 installed in a coolant circulating circuit of a first refrigerating system 30 to 36 filled with coolant. Then, working fluid in a heat exchanger 12 is cooled and liquefied by an endothermic part 36 of the coolant circulating circuit and the pressure of the working fluid decreases inside the heat exchanger 12 and a flowing tube 10 at the outlet of a turbine 1. The working fluid in closed flowing tubes 10 to 20 moves from a higher pressured part 20 to a lower pressured part 10, and the removing force of the working fluid drives the turbine 1. The rotational force of a rotational axis 7 connecting the electric motor 8 and the turbine 1 drives a compression means

13 of the working fluid, the first refrigerating system 30 to 36 which constitutes a separate coolant circulating circuit, second and third refrigerating systems 40 to 45 and 50 to 55, and a heat exchanger 60 which absorbs heat from the external fluid.

The liquefied working fluid is removed to flowing tubes

14 to 20 in the higher-pressured part which are connected to the inlet of the turbine 20 by the compression means 13. Heat exchangers 11 and 15 and valves 73 and 76 which stand in a line in Fig.l are used in another embodiment. Also, the flowing tubes 177, 179, 182, 183, 185, 187 and 188, and the valves 178, 180, 181, 184 and 186 which stand in a line are used in other conditions. Flowing tubes in a dotted area of Fig.l may be neglected in this embodiment. The working fluid is heated in an exothermic part 34 of the first refrigerating system 30 to 36 and an exothermic part 45 of the second refrigerating system 45. The fluid is further heated by the external fluid in the heat exchanger 60 through which the external fluid, e.g., air passes. Then, the working fluid is finally heated in an exothermic part 53 of the third refrigerating system 50 to 55 and enters the turbine 1. The third refrigerating system is to absorb heat from the external fluid in the normal temperature and to heat the working fluid in the boiler 19.

Heat media like Freon R14, R13, carbon dioxide, ethane and ethylene which are in a gaseous state over a critical temperature in the normal temperature, or substances and their mixtures which have similar properties to the heat media may be used as the working fluid. Further, synthesized substances suitable for the system can be utilized. The temperature of the working fluid becomes higher than the critical temperature while flowing through the turbine 1, and at the outlet of the turbine the working fluid is discharged at the critical temperature or the temperatures a little below or above the critical temperature.

The working fluid should have lower temperature than the critical one and higher pressure than the saturated one to be liquefied. Accordingly, the working fluid at the outlet of the turbine 1 is liquefied in a condenser 12 as its temperature decreases by the endothermic part 36 of the first refrigerating system. However, since the latent heat, i.e., the heat of liquefaction is not large at temperatures below the critical temperature, the amount of heat absorbed by the endothermic part 36 of the first refrigerating system 30 to 36 is not large.

The working fluid is heated in turn by the exothermic part 34 of the first refrigerating system, the exothermic part 45 of the second refrigerating system, and then a flowing tube

22 of the heat exchanger 60 through which the external fluid passes. The working fluid is further heated in the heat exchanger 19 including the flowing tube of the exothermic part 53 of the third refrigerating system, and the temperature of the fluid increases.

According to the above described procedure, the power generated in the turbine 1 is larger than the power which drives the compression means 13 of the working fluid, the first to third refrigerating systems and a fluid transporter 61 of the heat exchanger. Therefore, after the first drive of an electric motor 8 by external electric power supply, self-generated power drives the system spontaneously, though the external electric power supply has been suspended when a stationery state is established, and extra self-generated power keeps a generator 9 driving, thus giving electric power.

Such a spontaneous driving of the power generating system of the invention will be explained in detail.

The work in Carnot cycle may comprise four steps, and the work obtained through isothermal expansion and adiabatic expansion may be the work done by the turbine. In this procedure, a heat source in high temperature is necessary to converse the thermal energy of gas into power as much as possible.

In the present invention, however, since the working fluid in the boiler is in gaseous state above the critical temperature, the pressure in the boiler can be freely controlled regardless of the temperature. The high pressure of the boiler can be achieved though the temperature in the boiler is not high, since the working fluid is not liquefied even when the pressures is high at temperatures above the critical temperature. A difference in pressure between the boiler and the condenser can be large though a difference in temperature between them is not large. A difference of saturated vapor pressure is larger than the temperature difference. Therefore, when the working fluid is liquefied in conditions that the temperature and the pressure are lower than the respective ones after the fluid works in the gaseous state above the critical temperature, a work done by the turbine can increase according to the pressure difference, but a work done by the refrigerator to eliminate the heat of liquefaction does not increase. Accordingly, the work done by the turbine is larger than the work done by the refrigerator.

The working fluid in a lower-pressured part(condenser) has large difference in density during the liquefaction, so that the power consumed by the compression means or pump is very little compared to the power obtained by the turbine, though the pressure difference between the lower-pressured and higher-pressured parts is large. While the work done by the turbine is the work done in the adiabatic procedure and the efficiency increases according the pressure ratio, the work done by the refrigerator reduces the amount of heat which is transferred by the power according to the temperature difference (reversed Carnot cycle). Accordingly, in the condition of the present invention, that is, in the condition that the pressure difference is much smaller than the temperature difference, the power that the turbine obtains can be larger than the power from the refrigerator.

However, in actual machines the power the turbine obtains and its efficiency are low when the temperature difference between the higher temperature part (the boiler) and the lower temperature part (the condenser) is too small. A temperature difference larger than a certain degree has to be guaranteed to drive the system of the present invention, since the temperature difference is required for the exchange of heat in the heat exchanger and since it is difficult to liquefy the fluid when the difference between the critical temperature and the liquefaction temperature (the temperature of the working fluid in the condenser) is too small, and accordingly the temperature for liquefaction should be lowered below some limit point. The work done by the refrigerator to increase the temperature is proportional to the temperature difference, so that the power obtained by the turbine can be larger than the work done by the refrigerator. Therefore, the heat of liquefaction is eliminated by the refrigerating system, and also the external fluid like air to be supplied to the boiler has the temperature raised by the third refrigerating system 50 to 55.

When the working fluid obtains heat from the external fluid rather than from the third refrigerating system, much higher efficiency and more power can be obtained. However, when the temperature of the external fluid is low, the temperature range in the turbine becomes small, since in low temperature the tensile strength of metal becomes weak and the rotational wings of the turbine becomes destructive.

If a system which is strong in the low temperature can be produced, a substance having very low critical temperature can be used as the working fluid, and accordingly if the third refrigerating system can be excluded, the production cost and the volume of the system can be reduced and the efficiency can be raised. In this case, the system of the present invention can be preferably utilized in various transportation means. When the temperature of the external fluid is low the third refrigerating system is driven. Further, when the temperature of the external fluid is high, the power transferring/discontinuing means 6a and 6b which are installed on a rotational axis 7 together with the coolant compression means 50 can be driven to discontinue the power so that the system may be driven without the operation of the third refrigerating system.

When the third refrigerating system is not worked, and the working fluid passes through the heat exchanger which is not working, the loss resulted from abrasion may be caused.

A flowing tube 172 and a valve 171 are therefore installed to be used as needed so that the working fluid may not pass through the heat exchanger 19.

When the external temperature is high, only the first refrigerating system 30 to 36 can be driven without the second refrigerating system.

Further, the flowing tubes 177 and 179 and the valves 178 and 180 can be installed in a line with the exothermic parts 33 and 34 to be alternatively used according to the properties of the working fluid and the temperature of the external fluid. Further, the flowing tubes 182 and 183 and the valve 181 can be arranged in a line, and a heat exchanger (not shown) can be installed to be connected with the flowing tubes 182 and 183. The unshown heat exchanger can have the same structure as the heat exchanger 60 without the antifreezing solution circulating circuit, or can be installed additionally to the heat exchanger 60.

When the pressure of the working fluid at the outlet 10 of the turbine is much lower than the critical pressure, the temperature of the working fluid decreases in the heat exchanger 11 and the fluid is condensed in the condenser 12. Then, the temperature of the fluid increases again in the heat exchanger. Accordingly, since the temperature difference of the working fluid from the critical temperature is small, it is more preferable that the exothermic part discharges heat to the external fluid rather than that the working fluid exchanges heat with the external fluid, when the external temperature is lower than the critical temperature.

When the heat exchangers 43 and 16 are closed, the flowing tubes 182 and 183 standing in a line are connected with the heat exchanger through which the external fluid passes to discharge heat to the external fluid. Also, when the external fluid has substantially the same temperature as the critical one, it is preferable that the working fluid exchanges heat with the external fluid in the heat exchanger.

In the above case, the second refrigerating system 40 to 45 does not have to be worked.

However, when the temperature of the extemal fluid is the same as or higher than the critical one and the temperature of the working fluid in the condenser 12 is much lower than the critical one, the temperature at the exothermic part of the first refrigerating system may be lower than the critical one. Then, the heat exchanger 43 is operated to exchange heat with the second refrigerating system, and the heat exchanger 16 and the flowing tubes 182 and 183 through which the working fluid exchanges heat with the extemal fluid are closed.

When the temperature at the exothermic part 45 of the second refrigerating system is lower than the critical one and higher than that of the extemal fluid, the flowing tubes 187 and 188 which stand in a line are connected to a heat exchanger (having the same structure as the heat exchanger 60) and include the valve 186 to discharge heat of the working fluid to the external fluid.

In the drawings, a valve and a flowing tube are arranged in a line with only one flowing tube of a heat exchanger, and another valve and another tube can be arranged in a line with the other flowing tube, so that the loss due to the abrasion may not be caused by the flow of the fluid through a non-operating heat exchanger (see 173 to 176 in Fig.l). The above alternative operation can be applied in the second to

- io - sixth embodiments.

In the above description, the system where the working fluid is heated by steps in the exothermic parts 34 and 45 of the first and second refrigerating systems, the heat exchanger 60 absorbing heat from the extemal fluid and the third refrigerating system reduces the power consumed by the refrigerating systems, thus increasing the efficiency of the system.

The working fluid is heated by the exchange of heat with the fluid at the outlet 10 of the turbine in the heat exchanger

15 and further heated in the exothermic part 34 of the first refrigerating system. Then, the fluid is heated in the exothermic part 45 of the second refrigerating system, and in the heat exchanger 60 where the external fluid flows, and finally heated in the exothermic part 53 of the third refrigerating system, thus entering the turbine.

The first refrigerating system eliminates the heat of liquefaction of the working fluid in the condenser 12, to heat the endothermic part 43 of the second refrigerating system and then to heat the working fluid in the exothermic part 34.

Further, the second refrigerating system 40 to 45 obtains the heat from the first refrigerating system to heat the working fluid.

If the working fluid absorbs heat only from the third refrigerating system rather than from the heat exchanger 60 and the exothermic part 53 of the third refrigerating system, the total amount of heat absorbed by step by the heat

ll exchanger 60 and the third refrigerating system will be the same as the amount of heat only from the third refrigerating system. Further, the amount of heat absorbed by the first and second refrigerating systems is the same as the total amount of the heat absorbed by the above steps, and the amount of power consumption increases as much as the amount of heat. The procedure of thermal transmission between the first and second refrigerating systems is as follows. The exothermic part 33 of the first refrigerating system heats the endothermic part 43 of the second refrigerating system with the half amount of heat and then heats the working fluid at the exothermic part 34. Only half amount of the heat is transmitted to the second refrigerating system, which transmits only the half amount of heat to the working fluid, thus reducing the power consumption.

In a second embodiment of the present invention, a heat exchanger 11 where the fluids flowing in opposite directions exchange heat is installed in the flowing tube at the outlet 10 of the turbine. When the pressure at the outlet 10 of the turbine is much lower than the critical one and the temperature is as high as the critical temperature, the working fluid from the outlet of the compression pump 13 exchanges heat with the working fluid at the outlet 10 of the turbine. The working fluid at the outlet 10 of the turbine is cooled while the working fluid from the compression pump 13 is heated to increase the temperature. Therefore, the turbine can obtain large amount of power due to its large pressure ratio, and the turbine works at temperatures above the critical temperature, thus obtaining the higher efficiency than that of the working fluid in a vapor state. The power consumption can be reduced since the working fluid in a high temperature but in a low pressure is discharged from the outlet 10 of the turbine and the working fluids flowing in opposite directions exchange heat mutually. The mutual exchange of heat reduces the power to decrease the temperature by the endothermic part 35 of the refrigerating system.

When the temperature of the working fluid decreases in the condenser, the heat of liquefaction and the amount of heat eliminated increases, and the temperature range of the operation of the refrigerator increases, thus requiring more power to operate the refrigerator. However, since the pressure difference in the turbine is large, the turbine works more than the power to be consumed by the refrigerator and the working fluid works at temperatures above the critical temperature, increasing the working efficiency.

The lower the temperature of the working fluid in the lower-pressured part 10, the higher the efficiency. It is preferable to use substances whose critical temperature is close to the lowest limit temperature. The lower the critical pressure of the working fluid, the higher the efficiency.

In the present invention, many installations for the exchange of heat are used, and the efficiency of those installations is high when the temperature difference of the working fluids which exchange heat mutually is low.

It is preferable to use a heat exchanger where the fluids having a little difference in temperature exchange heat efficiently, e.g., the heat exchanger having high heat conductivity, high purity, large surface area and thin thickness. High efficiency can be obtained when using a heat exchanger manufactured of superconductor.

When the external temperature changes at any time due to the use of the working fluid having a low critical temperature, or the operation of the system is suspended, the internal pressure increases to cause problems in the operation of the system and the voltage at the output of the generator 9 changes at any time. Also, explosion and breakdown may be caused due to high voltage. The frequent change of the output voltage resulted from the change of the external temperature can be reduced when the operation of the pump and the valve 78 is automatically controlled by means of a pressure sensing means 77 of a storage tank 106 and a pressure controller installed in the higher-pressured part.

When the reduction of the voltage change is not sufficient, an automatic voltage controller can be installed at the output of the generator 9 to maintain the output voltage constant.

When the external temperature is high, the heat exchanger 60 through which the extemal fluid passes can be used as a refrigerator or an air conditioner.

In case that the heat exchanger 60 is used as the air conditioner, indirect heating method wherein a heat medium absorbs heat from the extemal fluid in the heat exchanger 60 to heat the working fluid may be adopted.

The flowing tube of the endothermic part 110 at one part of the heat exchanger 60 is connected to an antifreezing solution evaporation means 300 as shown in Fig.5 and flowing tubes 111 and 112 to heat the antifreezing solution in operation.

In the antifreezing solution evaporation means 300, an antifreezing solution flows down from a nozzle 62 at the upper part of the heat exchanger, and is diluted with the moisture in the air, to prevent freezing.

Otherwise, when the external temperature is low and the air passes through the heat exchanger 60 which absorbs heat, the moisture in the air may be frozen, thereby reducing the efficiency of the heat exchanger and causing suspension of operation.

In the above case, it is necessary to concentrate the diluted antifreezing solution to maintain a constant concentration. For this reason, the antifreezing solution is evaporated and concentrated while flowing through an evaporation means 310 in a low pressure, and the evaporated antifreezing solution is removed to the upper part 62 of the heat exchanger 60. The antifreezing solution at the lower part 63 of the heat exchanger 60 is removed to the evaporation means 310 to be concentrated and then retumed to the upper part 62. The flowing tube 110 of the heat exchanger 60 is an endothermic part of the refrigerating system constituting a separate coolant circulating circuit. The coolant is removed to the evaporation means 310 by a compression means 312 and heats the antifreezing solution while flowing through a flowing tube 320 installed in a path 370 inside the evaporation means. That is, the coolant supplements the heat of evaporation.

It is desirable that the refrigerating systems 312, 320, 316 and 250 absorb heat from the extemal fluid and heat the antifreezing solution when the extemal temperature is very low. On the contrary, when the extemal temperature is not so low, the compression means 312 works only as a fluid transporter and a separate flowing tube 318 and valves 380 and 381 are arranged in a line with the flowing tube passing the expansion valve 316, so that the fluid may flow into the flowing tube 318 to supply the heat absorbed from the external fluid to the antifreezing solution without the increase of the temperature.

The evaporation means 310 includes a vacuum pump 313 to evacuate the gas at the upper space. The antifreezing solutions to be discharged from and to enter the evaporation means 310 flow in opposite directions in a heat exchanger 314 and exchange heat each other. That is, the antifreezing solution which has been heated in the evaporation means heat the solution toward the evaporation means. Further, the antifreezing solution which has been heated in the above heat exchanger 314 exchange heat with the vapor discharged from the vacuum pump 313 in a heat exchanger 315 to be further heated, thus entering the evaporation means 310.

However, when the external temperature is not so low, the heat exchanger 314 can be excluded. The antifreezing solution is removed to the flowing tube 62 at the upper part of the heat exchanger 60 by means of a circulation pump 311, and the antifreezing solution which stagnates in the lower part 63 is absorbed by the absorption force since the intemal pressure of the evaporation means 310 is low. Therefore, a flux control valve 360 is installed to control the flux, and a water level sensor 330 is installed inside the evaporation means. The flux is automatically controlled through the valve 360 according to signals of the water level sensor 330 to maintain the level inside the evaporation means constant.

Fig. 7 is a sectional view showing the intemal paths of the evaporation means, wherein a flowing tube 320 of the refrigerating system is installed in a curved path 370, and the coolant and the antifreezing solution exchange heat mutually while flowing in opposite directions through the flowing tube

320 and the curved path 370.

It is preferable that the intemal path 370 of the evaporation means 310 is filled with sand, primarily heated earth and rocks, soil, fibers and so on, and the lower part of the path 370 is filled with relatively larger particles and the upper part is filled with relatively smaller particles, so that the antifreezing solution may flow through the larger particles in the lower part to be effectively evaporated.

Fig. 6 shows another embodiment of the antifreezing solution evaporation means wherein the external fluid passes rapidly by means of a blower 350 and the internal pressure of the evaporation means 310 is reduced by the vacuum pump.

Though the blower 350 and an inlet path 351 are shown to have large section in the drawings, it is preferable that the section is not too large and the air passes rapidly for evaporation. Fig. 2 shows a third embodiment of the present invention wherein turbines 1 to 5 has multiple- stepped reheating and regenerating turbine systems. The refrigerating systems 30 to 35 and 40 to 45 are installed in a two- stepped structure to liquefy the working fluid in a lower-pressured part at the outlet 82 of the turbine 5. Also, the exothermic parts 53 to

55 of the third refrigerating system are arranged in a line to heat the working fluid flowing into the respective reheating turbines.

The working fluid at the outlet 82 of the turbine is cooled and liquefied by the exothermic part 35 of the first refrigerating system 30 to 35, and then removed to the higher-pressured part by means of the compression pump 13.

The exothermic part 33 of the first refrigerating system heats the endothermic part 43 of the second refrigerating system 40 to 45. The working fluid in the second refrigerating system 40 to 45 absorbs heat from the exothermic part 33 of the first refrigerating system to be evaporated, and then heats the working fluid 105 in the exothermic part 45 to be liquefied.

Further, the third refrigerating system 50to55 are arranged to heat the working fluid in the boiler in the same way as in the first and second embodiments, but further includes reheating and regenerating turbines which are provided with additional heat exchanger and regenerating pump.

Exothermic parts 53, 54 and 55 of the third refrigerating system are in a line to reheat the working fluid which is heated first by the external fluid in the heat exchanger 60 before entering the respective turbines of the reheating turbine system 1 to 3. In the regenerating turbines 3, 4 and 5, part of the working fluid is derived from the respective turbines to be removed to the heat exchangers 76 and 81, where the working fluid exchanges heat with the working fluid in a liquid state which has been removed by the compression pump 13 to be liquefied and joined together.

The working fluid at the outlet of a last- step turbine 82 is removed to an outlet 14 after being liquefied in the condenser 87 and compressed with high pressure by means of the compression pump 13. Then the fluid is liquefied while exchanging heat with the working fluid discharged from the outlet 80 of the second- step turbine 4 of the regenerating turbine system. The liquefied working fluid joins the working fluid removed by a pump 101 and liquefied again while exchanging heat with the working fluid discharged from the outlet 75 of the turbine 3, so as to join together by the pump 102 in the same manner.

Also, the working fluid is heated in the exothermic part

45 of the second refrigerating system, in the heat exchanger

60 through which the extemal fluid passes, and in the exothermic part 53 of the third refrigerating system by step to be supplied to the turbine 1.

The temperature of the working fluid is preferable to be higher than the critical temperature so as to gasify the working fluid after being heated in the boiler 67 and the boilers 71 and 86 of the reheating turbine system (at least 30

"C or higher than the critical temperature), and to be maintained higher than the critical temperature while flowing toward the inlet 74 of the first turbine 3 of the regenerating turbine system. However, it is preferable to maintain the temperature of the working fluid lower than the critical temperature from the outlet 75 of the first- step turbine 3 of the regenerating turbine system and to maintain the difference between the temperature at the outlet 75 and the saturation temperature small. Further, the temperature and the pressure of the working fluid at the outlet of the turbine 82 is preferably lowered. If the pressure difference between the inlet of the turbine 68 and the condenser (lower-pressured part) is very large and, particularly, the pressure ratio is large, more power may be obtained by the turbine. The temperature and the pressure of the working fluid at the outlet of the turbine 82 are to be lowered but not to be saturated, and the temperature at the condenser 87 is lowered slightly more so as to cool and liquefy the working fluid.

In this case, the heat of liquefaction is high since the temperature is low, and the heat more than the heat of liquefaction may be eliminated since the temperature is lowered by the condenser. However, the pressure ratio between the higher-pressured part and the lower-pressured part is very large, since the pressure difference between the boiler and the condenser is large and the absolute pressure at the outlet of the turbine 82 is very low.

As the temperature of the working fluid is lowered than the liquefaction point (boiling point), the ratio of the saturated pressure to the temperature ratio becomes larger. For example, comparing a saturated pressure Al at a temperature A with a saturated pressure Bl at a temperature B which is lower than the temperature A, the ratio of the saturated pressure (Al-Bl) is larger than the temperature ratio (A-B) and this difference becomes even larger under the boiling point, so that the efficiency of the turbines greatly increases. Even though the efficiency of the turbines becomes higher as the pressure of the working fluid becomes higher at the inlet of the turbine 68 in the reheating turbine system, the pressure of the working fluid at the inlet 74 is to be kept low since the efficiency at the reheating turbine system decreases if the pressure of the working fluid at the inlet 74 of the turbines in the regenerating turbine system 3 to 5 increases. However, even if the pressure (absolute pressure) at the inlet 74 of the regenerating turbine system is low, the pressure at the outlet of the turbine 82 is lower than that of the inlet 74 and the pressure ratio between these two points 74 and 82 is large, so that the pressure difference in the reheating turbine system is also large to have enough efficiency.

Further, the efficiency of the turbines in the regenerating turbine system 3 to 5 is not so low, since the pressure difference is larger than the temperature difference in the regenerating turbine system. Therefore, it is preferable to use substances having a low critical temperature and a high liquefaction point (boiling point) as the working fluid to obtain high efficiency.

Fig. 3 is a view showing a fourth embodiment of this invention wherein the power generating system by use of fluid comprises a reheating turbine system without the regenerating system. In Fig. 3, the working fluid at the outlet of the last- step turbine 90 exchanges heat with the working fluid in a liquid state which is removed from the compression pump 13 in the heat exchangers 91 and 94, to be supplied to the condenser 92 after being cooled. A flowing tube 173 and an opening valve 176 arranged in a line with the heat exchanger 91 are adopted not to operate the heat exchanger 91 in the fifth embodiment. In the fourth embodiment, the heat exchanger 91 replaces the turbines in the regenerating turbine system and the heat exchanger. In order to obtain more power, instead of making the temperature and the pressure at the outlet 90 of the last- step turbine 3 substantially same as the critical temperature and the critical pressure, the pressure of the working fluid may be greatly lowered and the temperature may be maintained substantially same as the critical temperature. Then the working fluid is cooled in the heat exchanger 91 and further cooled in the condenser 92 to be liquefied. Therefore, the pressure ratio between the higher- pressured part (the boiler) and the lower-pressured part (the condenser) is very large and the temperature at the turbines 1 to 3 is maintained higher than the critical temperature, so that the efficiency of the turbine is improved.

As described above, in the fourth embodiment, the working fluids exchange heat each other to be cooled by the mutual heat exchanger 91 without the interaction between the turbines of the regenerating turbine system and the heat exchangers of the regenerating turbine system, thereby simplifying the structure. In the fifth embodiment of the present invention, the flowing tube 173 and the valve 176 are installed in a line with the heat exchanger 91 to prevent the working fluid from entering the heat exchanger 91 and to make the temperature and the pressure of the working fluid at the outlet of the turbine 90 substantially the same as the critical temperature and the critical pressure, so as to liquefy the working fluid at temperatures slightly below the critical temperature in the condenser 92. Therefore, the liquefaction heat to be eliminated by the refrigerating systems 130 to 136 and 40 to 45 is reduced as in the first embodiment.

Fig. 4 is a view showing the sixth embodiment of this invention, wherein the turbines 1 and 2 constitute a two-stepped reheating turbine system. The refrigerating systems 190 to 198 and 140 to 146 to heat the working fluid in the boiler comprise two steps rather than one step system to cool the working fluid in the condenser 157. The working fluid discharged at the outlet of a turbine

155 is cooled while exchanging heat with the working fluid in a liquid state which has been removed by the compression pump 13 and is liquefied by the endothermic part 236 of the first refrigerating system 230 to 236. The working fluid increases in temperature while exchanging heat mutually in the heat exchanger 156 and is heated by the exothermic part 233 of the first refrigerating system and then by the extemal fluid in the heat exchanger 60.

After being heated by the exothermic part 194 of the second refrigerating system 190 to 198 and the exothermic part 143 of the third refrigerating system 140 to 146 by step, the working fluid enters the turbine 1. The fluid obtains power from the first- step turbine and is discharged at the outlet 151. The working fluid is reheated by the exothermic parts 154 and 144 of the second and third refrigerating systems and enters the second-step turbine 2.

The exothermic parts 143, 194, 143, 195 and 144 are connected in serial or in parallel with each other to heat the working fluid sequentially, wherein the first exothermic part 193 of the second refrigerating system 190 to 198 heats the endothermic part 146 of the third refrigerating system firstly and then heats the working fluid secondly and thirdly.

Therefore, the third refrigerating system 140 to 146 absorbs only half of the amount of the heat from the second refrigerating system and after raising its temperature provides the working fluid with the heat, so that the power consumption by the third refrigerating system decreases by half comparing with the conditions that the second refrigerating system transmits all the heat to the third refrigerating system and the third refrigerating system transmits all the heat to the working fluid. The power consumption of the refrigerating system decreases as much as the extemal fluid can supply the heat to the working fluid in the heat exchanger 60, and the power consumption of the exothermic part 233 of the first refrigerating system may also decrease in the same way. Therefore, even though the refrigerating systems 190 to

198 and 140 to 146 to heat the boiler are formed in the two-stepped structure, the operation of the power generating system becomes possible.

The refrigerating systems to heat the boiler in the first to fifth embodiments may also be formed in the two- stepped structure as in the sixth embodiment.

In the fourth embodiment, though the stmcture of the turbine system is shown in the two-stepped reheating turbine system, the number of the steps may be increased.

The refrigerating system 230 to 236 to cool the working fluid of the condenser may also have the two-stepped structure and can be manufactured simply depending on various uses. In other words, it is possible to vary the stmcture of the refrigerating system according to the appliance and operation conditions, for example, the refrigerating system may have only one- stepped structure and the refrigerating system for heating the working fluid in the boiler may be omitted if the working fluid enters the turbine directly after absorbing heat from the extemal fluid in the heat exchanger 60.

Claims

What is claimed is:

1. Power generating system by use of fluid comprising a turbine system and a refrigerating system, wherein the refrigeration and liquefaction in a condenser (12) of a multiple -stepped turbine system is performed by a heat exchanger in an endothermic part of a refrigerating system which constitutes a coolant circulating circuit, an operating means of the refrigerating system is installed to mutually deliver power with a rotational axis of the turbine system, the rotational axis (7) of the turbine system has an electric motor (8) thereon which is driven by an external electric power supply, working fluid in a boiler of the turbine system exchanges heat with the external fluid in the normal temperature and with an exothermic part of the refrigerating system to be heated until the working fluid in the boiler is in a gaseous state above the critical ' temperature, the pressure in the boiler is raised to generate a little amount of the heat of liquefaction so that the working fluid in the condenser may be liquefied at temperatures slightly below the critical temperature, and as a result the heat of liquefaction of the working fluid in the condenser is low.

2. Power generating system as claimed in claim 1, characterized in that heat is obtained from the external fluid by the refrigerating system which constitutes a separate coolant circulating circuit and the heat is supplied to the boiler.

3. Power generating system as claimed in claim 1 or claim 2, characterized in that the turbine system comprises multiple -stepped reheating and regenerating turbines, the temperature of the working fluid at each step of the reheating turbines is above the critical temperature, and the temperature and pressure of the working fluid at an outlet (82) of the last- step turbine is very low.

4. Power generating system as claimed in claim 1 or claim 2, characterized in that the turbine system comprises multiple-stepped reheating turbines, and the temperature of the working fluid at each step of the reheating turbines is above the critical temperature.

5. Power generating system as claimed in any preceding claim, characterized in that the working fluid at the outlet of the last-stepped turbine exchanges heat with the working fluid in liquid state discharged from a condensing pump, so that the working fluid entering the condenser is refrigerated and the liquid working fluid from the condensing pump is heated.

6. Power generating system as claimed in any preceding claim, characterized in that the refrigerating system to refrigerate and liquefy the working fluid of the condenser and the refrigerating system to heat the working fluid of the boiler are arranged to have two or more- stepped refrigerating systems constituting a separate coolant circulating circuit, thus increasing or decreasing by step the temperature of the working fluid and reducing the power to drive the refrigerating system.

7. Power generating system as claimed in any preceding claim, characterized in that the pressure of the working fluid at the outlet of the last- step turbine of the turbine system is very low.

8. Power generating system as claimed in any preceding claim, characterized in that the pressure of the working fluid at the outlet of the last- step turbine is made to be low but its temperature to be substantially the same as the critical temperature, increasing the pressure ratio between the boiler (higher-pressured part) and the condenser (lower-pressured part), and the working fluid at the outlet of the last-step turbine exchanges heat with the liquid working fluid discharged from the condensing pump to refrigerate the working fluid entering the condenser and to heat the liquid working fluid.

9. Power generating system as claimed in any preceding claim, characterized in that an antifreezing solution flows down from nozzles at the upper part of the heat exchanger (60) which absorbs heat from the external fluid, not to freeze the vapor included in the external fluid which passes through the heat exchanger (60) on the wall of the heat exchanger, but to be diluted with the vapor, and the diluted antifreezing solution is evaporated by a vacuum pump (313) while flowing through an antifreezing solution evaporation means, wherein refrigerating systems (312, 316, 320 and 110) constituting the separate coolant circulating circuit are installed to heat the antifreezing solution and to supplement the heat of evaporation, the exothermic part of the refrigerating system exchanges heat with the antifreezing solution, the endothermic part thereof absorbs heat from the external fluid in the flowing tube (110) of the heat exchanger (60), the antifreezing solution entering the heat exchanger (60) after evaporated in the evaporation means (310) exchanges heat with the antifreezing solution entering the evaporation means (310) to be heated, and then the antifreezing solution absorbs heat from the vapor discharged from the vacuum pump, and is further heated by the exothermic part of the refrigerating system in the evaporation means.

10. Power generating system as claimed in claim 9, characterized in that a blower (350) and flowing tubes (351 and 352) rather than the vacuum pump are installed at the upper part of the evaporation means (310) to accelerate the flow of the external fluid therethrough, decreasing the pressure of the antifreezing solution and promoting the evaporation, and a path (370) through which the antifreezing solution flows is filled with sand, primarily heated earth and rocks, and fibers.