THERMOELECTRIC POWER GENERATION SYSTEM

A thermoelectric power generation system includes a shell-and-tube heat exchanger configured such that a tube including double tubes of an inner tube and an outer tube is inserted into a shell, and a thermoelectric power generation module inserted into between the inner tube and the outer tube. The thermoelectric power generation module generates thermoelectric power using a temperature difference between a first medium flowing in the inner tube, such as coolant, and a second medium flowing outside the outer tube in the shell, such as excess water vapor.

TECHNICAL FIELD

The present invention relates to a thermoelectric power generation system using a shell-and-tube heat exchanger.

BACKGROUND ART

In a current industrial society, mainly in a factory, an electric power plant, a steel plant, an automobile, a building, an illumination, a ship, etc., an enormous waste heat amount of 60% or more of the total primary energy supply amount has been discharged to global environment. It has been assumed that 75% or more of such waste heat is drainage water or exhaust gas at 250° C. or lower. Such waste heat, e.g., drainage steam from a steam turbine, is recovered by a shell-and-tube heat exchanger. The drainage steam introduced into a shell (drum container) exchanges heat with, e.g., cold water flowing in a tube inserted into the shell.

SUMMARY OF THE INVENTION

Technical Problem

However, in a conventional shell-and-tube heat exchanger, drainage steam introduced into a shell can be cooled, but it is difficult to use hot water subjected to heat exchange in a tube. For this reason, recovered thermal energy is wasted, leading to a problem on energy saving.

The present invention has been made in view of the above-described point, and a main object thereof is to provide a thermoelectric power generation system capable of producing easy-to-use electric energy from waste heat energy and effectively using the waste heat energy.

Solution to the Problem

A thermoelectric power generation system according to the present invention includes a shell-and-tube heat exchanger configured such that a tube including double tubes of an inner tube and an outer tube is inserted into a shell, and a thermoelectric power generation module inserted into between the inner tube and the outer tube. The thermoelectric power generation module generates thermoelectric power using a temperature difference between a first medium flowing in the inner tube and a second medium flowing outside the outer tube in the shell.

In a preferred embodiment, the second medium flowing in the shell is drainage hot water and drainage steam in geothermal power generation, continuous blow hot drainage water from a boiler, flash steam from a boiler, drainage steam from a steam turbine, or drainage hot water or drainage steam from a gas engine.

In a preferred embodiment, the tube includes a plurality of tubes inserted into the shell. An inner tube of each tube is fixed to the shell with an inner-tube fixing tube plate, and an outer tube of each tube is fixed to the shell with an outer-tube fixing tube plate. The output of the thermoelectric power generation module is taken out through a clearance between the inner-tube fixing tube plate and the outer-tube fixing tube plate.

Advantages of the Invention

According to the present invention, a thermoelectric power generation system can be provided, which is capable of recovering thermal energy, which has not been recovered so far, by thermoelectric power generation to produce easy-to-use electric energy from waste heat energy and effectively use the waste heat energy.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the following embodiment. Moreover, changes can be made as necessary without departing from a scope in which advantageous effects of the present invention can be provided.

FIGS.1and2are views schematically showing the configuration of a thermoelectric power generation system10including a shell-and-tube heat exchanger50according to one embodiment of the present invention.FIG.2is a sectional view along an A-A line ofFIG.1.

As shown inFIGS.1and2, tubes12(two in the figure) are inserted into a shell (drum container)11of the heat exchanger50. Fluid (first medium)16such as excess water vapor flows into the shell11through an inlet13, flows between the inside of the shell11and the outside of the tubes12, and flows out through an outlet15. Coolant (second medium)14such as water is injected into the tube12front one end thereof, and exchanges heat with the fluid16such as excess water vapor. Accordingly, the fluid16is cooled, and the coolant14itself is warmed.

As shown inFIG.2, the tube12inserted into the shell11of the heat exchanger50includes double tubes of an inner tube1aand an outer tube1b, and a thermoelectric power generation module2is attached to the outer surface of the inner tube1apreferably through a heat dissipation sheet3a. Moreover, a heat dissipation sheet3bis mounted between the thermoelectric power generation module2and the outer tube1b. The coolant14flows in the inner tube1a.

Sheets with a high thermal conductivity are preferably used as the heat dissipation sheets3a,3binserted between the inner tube1aand the thermoelectric power generation module2and between the thermoelectric power generation module2and the outer tube1b. With this configuration, adhesion between the thermoelectric power generation module2and each of the inner tube1aand the outer tube1bcan be ensured, and a heat transfer loss can be reduced. As a result, a great temperature difference in the thermoelectric power generation module2can be ensured, and a thermoelectric power generation efficiency can be improved.

The double tubes sandwiching the thermoelectric power generation module2may be produced in such a manner that the thermoelectric power generation module is wound around the inner tube1athrough the heat dissipation sheet3a, e.g., a silicone rubber sheet having a thermal conductivity of 4 W/mK and a thickness of 1 mm, the heat dissipation sheet3bis attached thereto, and the outer tube1bis fitted thereon.

If a carbon sheet having a thermal conductivity of 30 W/mK is used as the heat dissipation sheet3b, heat transfer and slipperiness can be improved, and therefore, the outer tube1bcan be easily fitted onto the heat dissipation sheet3b. If seamless tubes, i.e., tubes with no joints, are used as the inner tube1aand the outer tube1b, a highly-reliable system having excellent pressure resistance and causing no leakage can be built.

FIG.3is a view showing a specific configuration of the thermoelectric power generation module2. As shown inFIG.3, P-type thermoelectric devices23and N-type thermoelectric devices24are alternately arrayed and mounted on wiring lands22formed on a flexible base substrate21. The P-type thermoelectric device23and the N-type thermoelectric device24are connected in series through a wiring layer26formed on a flexible upper wiring board25. Generated thermoelectric power is taken out through lead-out electrodes27.

The upper wiring board25is formed with slits28, each of which is formed between adjacent ones of the lines of the P-type thermoelectric devices23and the N-type thermoelectric devices24connected to each other. With this configuration, the module2is easily bendable in a direction at a right angle to the slit28, and by aligning the slits28with a tube axis direction, the module2can easily closely contact the inner tube1a. Note that in this figure, the flexible upper wiring board25is seen through for the sake of illustration of the state of lower chip mounting and wiring.

The thermoelectric power generation system10in the present embodiment is configured, for example, such that the inner tube1ahas an outer diameter of 25.4 mm, the thermoelectric power generation module2has a size of 10 cm square and a thickness of 1.2 mm, and the outer tube1bhas an outer diameter of 36 mm.

FIG.4is a view showing a method for fixing the inner tube1aand the outer tube1bof the tube12and taking out the output of the thermoelectric power generation module2in the shell-and-tube heat exchanger50.

As shown inFIG.4, the inner tube1aof the tube12is fixed to the shell11with an inner-tube fixing tube plate31, and the outer tube1bis fixed to the shell11with an outer-tube fixing tube plate32. The output33of the thermoelectric power generation module2is taken out through a clearance between the inner-tube fixing tube plate31and the outer-tube fixing tube plate32.

Other Embodiments

FIG.5is a view showing the configuration of a thermoelectric power generation system including the shell-and-tube heat exchangers50having a thermoelectric power generation function using drainage hot water and drainage steam in geothermal power generation.

In geothermal power generation, a geothermal spring source41is pumped up from a production well42, and is separated into steam44aand hot water44bin a steam-water separator43. The steam44ais introduced into a steam turbine45, and generates power by rotating the turbine45and a power generator47.

In normal geothermal power generation, drainage steam49from the steam turbine45is returned to water by a condenser, and together with the hot water44b, is returned to the ground through a return well46in order to avoid depletion of the spring source. Thermal energy is wastefully discarded.

However, in the thermoelectric power generation system of the present embodiment, the hot water44band the drainage steam49are introduced into the thermoelectric power generation function-equipped shell-and-tube heat exchangers50shown inFIG.2to exchange heat with the coolant14and to generate thermoelectric power by the thermoelectric power generation modules (not shown) shown inFIG.2, as shown inFIG.5. Thus, waste energy can be effectively used.

FIG.6is a view showing the configuration of a thermoelectric power generation system including the shell-and-tube heat exchanger50having a thermoelectric power generation function using hot drainage water from a gas engine.

Hot drainage water52from a gas engine53is introduced into the thermoelectric power generation function-equipped shell-and-tube heat exchanger50shown inFIG.2, is cooled by exchanging heat with the coolant14, and is returned to the gas engine53by a pump54. In addition, thermoelectric power is generated by the thermoelectric power generation module (not shown) shown inFIG.2. Thus, waste energy can be effectively used.

FIG.7is a view showing the configuration of a thermoelectric power generation system including the shell-and-tube heat exchanger50having a thermoelectric power generation function using continuous blow hot drainage water from a boiler.

In order to prevent, e.g., impurity accumulation, maintenance is regularly performed for a boiler61to discharge continuous blow hot drainage water63. The continuous blow hot drainage water63is introduced into the thermoelectric power generation function-equipped shell-and-tube heat exchanger50shown inFIG.2, is cooled by exchanging heat with the coolant14, and is discharged to a drainage tank62. In addition, thermoelectric power is generated by the thermoelectric power generation module (not shown) shown inFIG.2. Thus, waste energy can be effectively used.

FIG.8is a view showing the configuration of a thermoelectric power generation system including the shell-and-tube heat exchanger50having a thermoelectric power generation function using drainage steam from a steam turbine.

A boiler61generates steam44ato drive a steam turbine45, and accordingly, a power generator47rotates to generate power. Drainage steam49from the steam turbine45is introduced into the thermoelectric power generation function-equipped shell-and-tube heat exchanger50shown inFIG.2, is cooled by exchanging heat with the coolant14, and is returned to water, i.e., is condensed. The condensate is returned to the boiler61by a water supply pump71. As described above, the heat exchanger50operates as a condenser, and thermoelectric power is generated by the thermoelectric power generation module (not shown) shown inFIG.2. Thus, waste energy can be effectively used.

FIG.9is a view showing the configuration of a thermoelectric power generation system including the shell-and-tube heat exchanger50having a thermoelectric power generation function using flash steam from a boiler.

An exhaust heat boiler61agenerates steam88to be used in a process. Raw water87stored in a water tank85is supplied to the exhaust heat boiler61aby a water supply pump86, and is preliminarily heated with exhaust heat discharged to an exhaust pipe82in an economizer81. Part of the raw water87is sent to a flash tank84, and generates hot water and flash steam.

The flash steam is introduced into the thermoelectric power generation function-equipped shell-and-tube heat exchanger50shown inFIG.2, is cooled by exchanging heat with the coolant, is returned to water, and is returned to the water tank85. Moreover, the coolant is warmed using the raw water87in the heat exchanger50. Thus, the thermoelectric power generation module (not shown) shown inFIG.2generates thermoelectric power using a temperature difference between the steam and the raw water, and waste energy in this system can be effectively used.

Valves83a,83b,83cin the middle of the system are for adjusting a steam amount and a thermoelectric power generation amount in the system according to steam and power demands. For example, in the case of a great power demand and a small steam demand, the valves83a,83bare opened to increase the thermoelectric power generation amount. In the case of a small power demand and a great steam demand, the valves83a,83bare closed to increase the steam amount. In the case of a great power demand and an extremely-small steam demand, the valves83a,83b,83care opened to increase the thermoelectric power generation amount. As described above, variable thermoelectric power generation operation is allowed by opening/closing of the valves83a,83b,83c.

The present invention has been described above with reference to the preferred embodiments, but is not limited to description of these embodiments. Needless to say, various modifications can be made.

DESCRIPTION OF REFERENCE CHARACTERS