JP2019090399A - Power generation system - Google Patents

Abstract

To provide a power generation system which eliminates the possibility of burning and generates power at low costs.SOLUTION: A power generation system 100 includes: a hydrate generation part 120 which cools a gas-liquid mixture of raw water and inactive gas with a first fluid to generate a hydrate of the inactive gas; a hydrate decomposition part 150 which heats the generated hydrate with a second fluid having a temperature higher than the first fluid to decompose the hydrate into the raw water and the inactive gas; an expander 172 which is rotated by the inactive gas generated by the hydrate decomposition part 150; and a power generator 174 which generates power by rotation of the expander 172.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power generation system that generates electric power by using a temperature difference of fluid such as ocean temperature difference power generation.

  Binary power generation has been developed in which power generation is performed using a heat source with a relatively small temperature difference, such as ocean temperature difference power generation, hot spring exhaust heat power generation, and high temperature drainage power generation. In binary power generation, the heat of the heat source heats and gasifies the low boiling point medium, and the gas of the low boiling point medium rotates the expander to generate power.

  As a low boiling point medium used for binary power generation, for example, hydrocarbons such as isobutane and pentane, ammonia, and fluorocarbon are used (for example, Patent Documents 1 and 2).

JP, 2014-125990, A JP, 2014-190285, A

  However, since the hydrocarbons described in Patent Documents 1 and 2 have flammability, they may burn and explode in the power generation system. Ammonia also has the potential to adversely affect the environment, and is flammable, and because fluorocarbon is an environmental pollutant, it is necessary to prevent the outflow to the outside, and there is a problem that the cost required for the outflow prevention increases. is there.

  An object of the present invention is to provide a power generation system capable of generating power at low cost without fear of combustion and in view of such problems.

  In order to solve the above problems, a power generation system according to the present invention cools a gas-liquid mixture of raw material water and an inert gas with a first fluid to generate a hydrate generation part of the inert gas. A hydrate decomposition unit that heats the generated hydrate with a second fluid having a temperature higher than that of the first fluid to decompose it into the raw material water and the inert gas; and the hydrate decomposition unit And an electric generator that generates electric power by rotation of the expansion machine.

  The inert gas may be a noble gas.

  In addition, the raw material water may contain an auxiliary agent that reduces the pressure for generating the hydrate.

  In addition, the inert gas may be krypton, and the auxiliary may be 1-methylpiperidine.

  According to the present invention, there is no fear of combustion, and power can be generated at low cost.

It is a figure for demonstrating the schematic structure of a power generation system. It is a figure which shows the experimental result of the hydrate phase equilibrium condition of an Example and a comparative example. It is a figure explaining the thermal efficiency of the engine cycle of a hydrate, and the conventional Rankine cycle of gas.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values and the like shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the specification and the drawings, elements having substantially the same functions and configurations will be denoted by the same reference numerals to omit repeated description, and elements not directly related to the present invention will not be illustrated. Do.

(Power generation system 100)
FIG. 1 is a diagram for explaining a schematic configuration of a power generation system 100. As shown in FIG. In FIG. 1, the flows of raw material water and hydrate are shown by solid arrows, the flows of inert gas are shown by dashed arrows, and the deep ocean water (first fluid) and the ocean surface water (second The flow of the fluid) is indicated by a dashed dotted arrow.

  The power generation system 100 of the present embodiment is a system that generates electric power using a temperature difference between deep ocean water (for example, about 4 ° C. to 8 ° C.) and surface sea water (for example, about 20 ° C. to 30 ° C.). . In the power generation system 100, the gas-liquid mixture of the raw material water and the inert gas is cooled with deep ocean water to generate hydrate of the inert gas, and the generated hydrate is heated and decomposed with the surface water of the ocean. The power is generated by rotating the expander with the high pressure inert gas. And the inert gas pressure-reduced by rotating an expander is mixed with raw material water again. As described above, in the power generation system 100, the inert gas is circulated as a gas (gas) or hydrate, and power generation is performed in the circulation process. In the present embodiment, deep ocean water and surface water are pumped up (in a structure that does not require potential energy) using the principle of siphon. Deep sea water and surface water are already existing, so detailed description is omitted. Hereinafter, the specific configuration of the power generation system 100 will be described.

  As shown in FIG. 1, the power generation system 100 includes a gas-liquid mixing unit 110, a hydrate generation unit 120, a hydrate water separation unit 130, a pump 140, a hydrate decomposition unit 150, a dehumidifying unit 160A, 160 B, a power generation unit 170, a heat exchanger 180, a hydrate separated water dropping pressure unit 190, a cooling unit 200, a blower 210, a buffer tank 220, and a central control unit 230.

  The gas-liquid mixing unit 110 mixes the raw material water and the inert gas to generate a gas-liquid mixture. In the present embodiment, krypton (Kr) is described as an example of the inert gas. Moreover, 1-methyl piperidine (1-MPD) is contained in raw material water as an adjuvant which reduces the formation pressure of the hydrate in the hydrate production | generation part 120 mentioned later. The molar ratio of water to Kr and 1-MPD in the gas-liquid mixture is, for example, water: Kr: 1-MPD = 34: 5: 1. While maintaining the molar ratio of Kr and 1-MPD above and causing water to be present in crystal water (molar ratio: 34) or more, the stabilization reaction of hydrate formation in hydrate formation unit 120 is achieved. It becomes possible to maintain liquidity. The outlet of the gas-liquid mixing unit 110 is connected to the inlet of the hydrate generation unit 120 via a pipe 112.

  The hydrate generation unit 120 cools the gas-liquid mixture with deep ocean water to generate a hydrate of Kr. The hydrate generation unit 120 is configured by, for example, a mixer in which bubbles (microbubbles) of Kr are substantially evenly distributed in the liquid phase (raw material water), and the flow in the piping is made to be a turbulent flow. . The outlet of the hydrate generation unit 120 is connected to the inlet of the hydrate water separation unit 130 via a pipe 122.

  The hydrate water separation unit 130 is formed of, for example, a cylindrical container, and the entire container is cooled by deep ocean water. A solid-liquid mixture of hydrate and raw material water is introduced into the hydrate water separation unit 130 from the hydrate generation unit 120 via the pipe 122. The hydrate water separation unit 130 separates the solid-liquid mixture into mixed free gas and hydrate mixed water. Specifically, due to the difference in mass density between the free gas and the hydrate mixed water, the free gas is at the top of the hydrate water separation unit 130 and the hydrate mixed water is at the bottom of the hydrate water separation unit 130. To settle. However, since the reaction occurs in a large amount of raw water (carrier water) in normal operation, the Kr gas dissolves into the raw water. Therefore, almost no free gas exists, and the free gas hardly accumulates on the upper portion of the hydrate water separation unit 130. In the hydrate water separation unit 130, since the entire container is cooled with deep ocean water, decomposition of hydrate is suppressed also in the hydrate water separation unit 130, and dissolution of Kr gas is also promoted, and further, Hydrate formation will be promoted.

  Further, in the present embodiment, the solid-liquid mixture is jetted and introduced in the tangential direction of the hydrate water separation unit 130. Thereby, the solid-liquid mixture is swirled loosely in the hydrate water separation unit 130 so that hydrate crystals do not adhere to the inner wall of the hydrate water separation unit 130, and the hydrate is obtained by the centrifugal force and the specific gravity difference. It centers on the center of the hydrate water separation unit 130. Therefore, the hydrate is easily suspended in the coexisting free water (raw water), and the discharge to the pump 140 is facilitated. Moreover, when unreacted Kr gas exists, the contact efficiency of a bubble and raw material water can be improved, and it becomes possible to improve the formation efficiency of the hydrate in the hydrate water separation part 130.

  A pipe 132 connecting the hydrate water separation unit 130 and a hydrate decomposition unit 150 to be described later is connected to the bottom of the hydrate water separation unit 130, and a pump 140 is provided in the piping 132. Therefore, the hydrate suspension water (slurry) precipitated and separated by the hydrate water separation unit 130 is delivered to the hydrate decomposition unit 150 by the pump 140.

  During normal operation, there is almost no generation of Kr gas in the hydrate water separation unit 130, but the flow rate of the raw material water may be small, such as when the power generation system 100 is started, When it is out of the rate generation conditions, the free gas (Kr gas) is mixed in the solid-liquid mixture introduced to the hydrate water separation unit 130.

  For this reason, the blower 210 and the buffer tank 220 are provided, and the Kr gas generated in the hydrate water separation unit 130 is delivered to the buffer tank 220 by the blower 210. Specifically, the Kr gas is retained in the upper part of the hydrate water separation unit 130, and when the liquid surface of the raw material water becomes less than a predetermined height, the upper part of the hydrate water separation unit 130 and the buffer tank 220 Drive the blower 210 provided in the pipe 134 connecting the Then, the Kr gas accumulated in the upper part of the hydrate water separation unit 130 is discharged to the buffer tank 220. With the configuration provided with the buffer tank 220, the pressure fluctuation at the time of discharging the Kr gas from the hydrate water separation unit 130 can be reduced. An open / close valve 134 a and a check valve 134 b are provided between the blower 210 and the buffer tank 220 in the pipe 134. The on-off valve 134 a is opened as the blower 210 is driven, and closed as the blower 210 is stopped. The check valve 134 b prevents backflow of the Kr gas from the buffer tank 220 to the hydrate water separation unit 130.

  The pump 140 pressurizes the hydrate separated by the hydrate water separation unit 130 (specifically, a slurry of hydrate and raw material water) to a pressure that can be decomposed by the hydrate decomposition unit 150, and performs a hydrate decomposition unit. Send to 150. A check valve 132 a and a flow control valve 132 b are provided between the pump 140 and the hydrate decomposing unit 150 in the pipe 132. Further, a pipe 136 is provided to connect between the pump 140 and the check valve 132 a in the pipe 132 and the pipe 122, and the pipe 136 is provided with a flow rate adjustment valve 136 a. The configuration including the check valve 132 a prevents backflow of hydrate from the hydrate decomposition unit 150 to the hydrate water separation unit 130. Further, the flow rate of hydrate introduced from hydrate water separation unit 130 to hydrate decomposition unit 150 by flow rate adjustment valves 132 b and 136 a and the flow rate of hydrate returned to hydrate water separation unit 130 are adjusted. Become. Note that even if the Kr gas is released from the vent 134c (safety valve) without providing the blower 210, it does not cause a large loss.

  In the present embodiment, the pump 140 is driven by a hydrate separation water drop pressure unit 190 that rotates at the pressure (for example, about 5 to 7 MPa) of the raw material water generated by the hydrate decomposition unit 150 described later. With the configuration including the hydrate separation water dropping portion 190, the energy for driving the pump 140 can be reduced.

  In the present embodiment, since the power of the pump 140 may be insufficient only by the rotation by the hydrate separation water dropping pressure unit 190, the auxiliary driving device 192 is provided to assist the driving axial force of the hydrate separation water dropping pressure unit 190. . For example, at the time of startup of the power generation system 100, since the raw water is not generated in the hydrate decomposition unit 150, the hydrate separated water drop pressure unit 190 does not function. For this reason, the pump 140 is driven by the auxiliary driver 192 until the hydrate separation water dropping pressure unit 190 is in rated operation. The auxiliary drive unit 192 may be an electric motor or other power.

  The hydrate decomposition unit 150 is, for example, a container provided with a cylindrical heat transfer device, and the hydrate in the container is indirectly heated by the ocean surface water (for example, about 27 ° C.). Hydrate is introduced to the hydrate decomposition unit 150 via a pipe 132. In the hydrate decomposition unit 150, the hydrate is heated by the surface water of the ocean and decomposed into raw material water and Kr gas at high pressure (for example, about 5 MPa to 7 MPa). The dehumidifying parts 160A and 160B are connected to the upper part of the hydrate decomposing part 150 via the pipe 152, and the gas (wet Kr gas) discharged from the hydrate decomposing part 150 is the dehumidifying parts 160A and 160B. The water is removed in the process to form a dry Kr gas.

  Specifically, one end of the pipe 152 is connected to the upper portion of the hydrate decomposing unit 150, the other end is branched into two, and the dehumidifying parts 160A and 160B are connected to the other end, respectively. The dehumidifying parts 160A and 160B are filled with an adsorbent (for example, a molecular sieve or the like) that adsorbs water, and the water is removed from the mixed gas by a pressure swing adsorption (PSA) method.

  Then, the gas from which water is removed, that is, dry Kr gas (for example, about 24 ° C., about 5 MPa to about 7 MPa) is delivered to the expander 172 which constitutes the power generation unit 170 through the pipe 162, and the expander 172 And the expander 172 is rotated by the expansion energy.

  By the configuration provided with the dehumidifying parts 160A and 160B, the water content in the gas (Kr) delivered to the expander 172 can be reduced, and the water freezes in the expander 172, and the parts constituting the expander 172 It is possible to reduce the possibility of problems occurring in (for example, gas contact parts such as blades, bearings, etc.).

  Note that, while the wet Kr gas is supplied to the dehumidifying unit 160A and the dry Kr gas is sent from the dehumidifying unit 160A to the expander 172, that is, the water in the wet Kr gas is adsorbed in the dehumidifying unit 160A. During the removal, the supply of the wet Kr gas to the dehumidifying part 160B is stopped, and the dehumidifying part 160B is regenerated (water is desorbed from the adsorbent). On the other hand, while the wet Kr gas is being supplied to the dehumidifying unit 160B, the supply of the wet Kr gas to the dehumidifying unit 160A is stopped, and the dehumidifying unit 160A is regenerated.

  Specifically, the outlets of the dehumidifying parts 160A and 160B are connected to the pipe 164 in addition to the pipe 162, and the pipe 164 is connected to the gas-liquid mixing part 110. Then, when supplying the wet Kr gas to the dehumidifying unit 160A, the on-off valves 152a, 162a, and 164b are opened, and the on-off valves 152b, 162b, and 164a are closed. Then, the wet Kr gas generated in the hydrate decomposing unit 150 is introduced into the dehumidifying unit 160A, water is removed by the dehumidifying unit 160A, and then, the water is delivered to the expander 172. Further, the pressure difference between the dehumidifying unit 160B and the gas-liquid mixing unit 110 desorbs the water adsorbed by the adsorbent of the dehumidifying unit 160B, and the Kr gas remaining in the dehumidifying unit 160B and the desorbed water The mixed gas (wet Kr gas) is introduced into the gas-liquid mixing unit 110.

  Similarly, when supplying the wet Kr gas to the dehumidifying unit 160B, the on-off valves 152a, 162a, and 164b are closed and the on-off valves 152b, 162b, and 164a are opened. Then, the wet Kr gas generated in the hydrate decomposing unit 150 is introduced into the dehumidifying unit 160B, and after water is removed by the dehumidifying unit 160B, the moistened Kr gas is delivered to the expander 172. Further, the pressure difference between the dehumidifying unit 160A and the gas-liquid mixing unit 110 desorbs the water adsorbed by the adsorbent of the dehumidifying unit 160A, and the Kr gas remaining in the dehumidifying unit 160A and the desorbed water The mixed gas (wet Kr gas) is introduced into the gas-liquid mixing unit 110.

  The power generation unit 170 includes an expander (for example, a turbine) 172 which is rotated by the expansion energy of the dry Kr gas, and a generator 174 which generates electric power by rotation of the expander 172.

  The outlet of the expander 172 is connected to the gas-liquid mixing unit 110 through the pipes 182 and 164. Therefore, the Kr gas expanded (reduced pressure) by the expander 172 is returned to the gas-liquid mixing unit 110. In addition, since the Kr gas expanded by the expander 172 is at a cryogenic temperature (for example, about -100 ° C.), the pipe 182 is provided with the heat exchanger 180.

  The heat exchanger 180 performs heat exchange between the Kr gas passing through the pipe 182 and the raw material water passing through the pipe 156 described later, transfers the heat of the raw water to the Kr gas, and brings the Kr gas to 0 ° C. or higher. Heat up. With the configuration provided with the heat exchanger 180, it is possible to avoid a situation where the piping 164 (a piping through which the water desorbed by the dehumidifying parts 160A and 160B passes) is frozen and the influence on the expander 172 can be avoided. .

  Thus, the Kr gas having passed through the expander 172, the Kr gas delivered at the time of regeneration of the dehumidifying parts 160A and 160B, and the Kr gas delivered from the buffer tank 220 are introduced into the gas-liquid mixing part 110. It becomes. When the dehumidifying parts 160A and 160B are regenerated, pressure fluctuations become large, and a large amount of Kr gas may be introduced into the raw material water in the gas-liquid mixing part 110. Therefore, the pipe 164 and the buffer tank 220 are connected by the pipe 222, and the pressure fluctuation of the Kr gas is absorbed by the buffer tank 220. With this configuration, in the hydrate generation unit 120, it is possible to suppress the stagnation of the hydrate formation reaction due to the fluctuation of the introduced amount of Kr gas, and to reduce the decrease in hydrate yield.

  On the other hand, raw material water (for example, about 24 ° C., about 5 MPa to about 7 MPa) generated by decomposition of hydrate in the hydrate decomposition unit 150 is sent to the hydrate separation water dropping pressure unit 190 through the pipe 154 The raw material water rotates the hydrate separation water dropping portion 190. With this configuration, it is possible to reduce the energy input from the outside to rotate the hydrate separated water dropping portion 190, that is, the energy input from the outside to drive the pump 140, and the pump 140 can be driven at low cost. It is possible to

  In addition, as above-mentioned, the raw material water produced | generated in the hydrate decomposition part 150 is about 24 degreeC, and 5 MPa-about 7 MPa, for example. Therefore, if the raw material water is used as it is for rotation of the hydrate separation water dropping pressure section 190, about 40% of the Kr gas dissolved in the raw material water is reduced when the raw material water is decompressed in the hydrate separation water dropping pressure section 190. And the operation of the hydrate separated water pressure drop portion 190 may be inhibited.

  Therefore, the cooling unit 200 is provided in the piping 154, and the raw material water generated in the hydrate decomposition unit 150 is cooled to about 7 ° C to 8 ° C. As a result, it is possible to suppress the gasification of Kr in the hydrate separated water drop pressure portion 190 to 5% or less. Therefore, it is possible to improve the durability of the hydrate separated water drop pressure unit 190 by reducing the influence (uniform flow) generated on the blades and the like of the hydrate separated water drop pressure unit 190. In the present embodiment, the cooling unit 200 cools the raw material water with deep ocean water (for example, approximately 6 ° C. to 10 ° C.) after cooling the gas-liquid mixture in the hydrate generation unit 120. With this configuration, it is possible to reduce the energy input from the outside to cool the raw water.

  The raw material water whose pressure is reduced to about 1 MPa to 1.5 MPa by rotating the hydrate separation water dropping pressure unit 190 in this way is introduced into the gas-liquid mixing unit 110 through the pipe 156. Further, as described above, since the heat exchanger 180 is provided in the pipe 156, heat exchange is performed between the raw water and the Kr gas by the heat exchanger 180. Therefore, the raw material water is introduced into the gas-liquid mixing unit 110 after being cooled by the Kr gas (for example, cooled about 2 ° C. from the original temperature). As a result, it is possible to reduce the amount of deep ocean water used as a cold heat source for the hydrate generation unit 120.

  The central control unit 230 is constituted by a semiconductor integrated circuit including a CPU (central processing unit), reads a program, parameters and the like for operating the CPU itself from a ROM (Read Only Memory: read only memory), and serves as a work area. The entire power generation system 100 is managed and controlled in cooperation with a random access memory (RAM) and other electronic circuits. In the present embodiment, the central control unit 230 controls the flow control valves 132 b and 136 a and the flow control valve 164 c provided in the pipe 164 so that the pressure of the hydrate decomposition unit 150 is maintained at a predetermined set value. Adjust the opening degree. The central control unit 230 also monitors, for example, leakage of raw material water in the entire system of the power generation system 100 based on a not-shown liquid level detector installed in the hydrate decomposition unit 150.

  As described above, according to the power generation system 100 according to the present embodiment, the hydrate in the deep sea water is generated, the hydrate is decomposed in the surface water in the ocean, and the high pressure Kr gas is generated. The expander 172 is rotated by the expansion energy when the Kr gas expands to a low pressure Kr gas to generate power. This makes it possible to generate electricity at low cost without the possibility of combustion.

Moreover, in the present embodiment, Kr is used as a guest substance of hydrate. Since Kr has a stable formation reaction of hydrate as compared with other rare gases, stabilization reaction of the formation reaction of hydrate can be achieved by using Kr as a guest substance. In addition, Kr has a large molecular weight as compared to other inert gases (helium (He), neon (Ne), argon (Ar), nitrogen (N ₂ ), carbon dioxide (CO ₂ )). Therefore, when the pressure delivered to the expander 172 is equal, the density is increased, and the expander 172 can be miniaturized.

  Further, in the present embodiment, 1-MPD is contained in the raw material water as an auxiliary agent for reducing the generation pressure at the time of generating the hydrate of Kr. Heretofore, there has been a demand for the development of an aid in producing a hydrate of Kr. Therefore, as a result of intensive studies, the present inventors have found that 1-MPD can efficiently reduce the pressure of hydrate formation. Therefore, it is an auxiliary agent which reduces the formation pressure at the time of generating the hydrate of Kr, and is an 1-MPD characterized auxiliary agent, 1-MPD is made to mix the raw material water and Kr which were made to contain A Kr hydrate production apparatus comprising: a gas-liquid mixing unit; and a hydrate generation unit for cooling the gas-liquid mixture generated by the gas-liquid mixing unit; and raw material water containing 1-MPD And Kr are mixed to form a gas-liquid mixture, and the formed gas-liquid mixture is cooled.

  FIG. 2 is a diagram showing experimental results of hydrate phase equilibrium conditions of the example and the comparative example. In FIG. 2, as a comparative example, no auxiliary agent is shown as a white square, and an example is shown as a black circle. As a comparative example, phase equilibrium conditions (pressure and temperature conditions at which the hydrate and the Kr gas are in an equilibrium state) in the case of producing a hydrate of Kr without an auxiliary agent, as an example, 1-MPD as an auxiliary agent The phase equilibrium conditions were measured when the hydrate of Kr was formed. As a result, as shown in FIG. 2, it was found that even in the case of the same phase equilibrium temperature among the phase equilibrium conditions, the example had a lower phase equilibrium pressure than the comparative example.

  In the deep sea water temperature range (about 4 ° C. to 8 ° C., ie, about 277.15 K to about 281.15 K), the phase equilibrium pressure is about 3 MPa in the comparative example, but about 1 MPa in the example. Was confirmed. That is, it was found that the pressure of hydrate formation in the hydrate formation unit 120 can be reduced to 1/3 by adding 1-MPD as an auxiliary agent.

  On the other hand, in the temperature range of ocean surface water (about 20 ° C. to 30 ° C., ie, about 283.15 K to about 293.15 K), the phase equilibrium pressure without an auxiliary agent is about 3 MPa to 9 MPa in the comparative example. On the other hand, in the Example, it was confirmed that it is about 1 MPa-3 MPa. That is, it was found that the decomposition pressure of the hydrate in the hydrate decomposition part 150 can be reduced to 1/3 by adding 1-MPD as an adjuvant.

  In addition, when the ratio of the hydrate formation pressure to the decomposition pressure, that is, the expansion ratio of the Kr gas is compared, it is confirmed that it is almost the same as about 3 times in both the comparative example and the example. That is, by adding 1-MPD as an auxiliary agent, the pressure of the entire system of the power generation system 100 is reduced to 1/3 while the recovery pressure at the expander 172 (the output of the expander 172 (power generation of the generator 174 It has been found that it is possible to maintain the amount)).

  As described above, it was confirmed that 1-MPD efficiently functions as an auxiliary agent in producing a hydrate of Kr.

(Comparison of Hydrate engine cycle with conventional Rankine cycle)
The thermal efficiency of the power generation system 100 (an engine cycle of a hydrate) using the above-mentioned hydrate and the thermal efficiency of the Rankine cycle using a conventional gas were calculated using the following formulas (1) to (3).
W = Δhg + Δhw−VΔp (1)
Q = ∫Cp, h × dT + Lh (2)
η = W / Q (3)
Here, W is work (energy obtained), Δhg is enthalpy difference of gas, Δhw is enthalpy difference of water, V is hydrate, molar volume of gas, Δp is pressure difference, Q is heat quantity (energy consumed) , Cp, h indicate specific heats such as hydrate and coexistent water, and Lh indicates heat of formation of hydrate or latent heat of condensation of conventional Rankine cycle gas.
In addition, the formation temperature of hydrate, the condensation temperature of conventional Rankine cycle gas was 282 K, the decomposition temperature of hydrate, and the evaporation temperature of conventional Rankine cycle gas were 293K.

  FIG. 3 is a diagram for explaining the thermal efficiency of a hydrate engine cycle and a conventional gas rankine cycle. As shown in FIG. 3A, in the engine cycle of Kr hydrate (hereinafter referred to as "the engine cycle of Kr hydrate using 1-MPD") in the case of using 1-MPD as an auxiliary agent, Since the expansion ratio of the gas in the engine does not decrease, even if the pressure is lowered, it is possible to obtain a thermal efficiency close to that of the Kr Hydrate engine cycle without any auxiliary agent. In addition, since the engine cycle of Kr hydrate using 1-MPD can lower the pressure as compared with the engine cycle of Kr hydrate without any auxiliary agent, the durability of the apparatus is significantly increased. It can be lowered (see Figure 2). Therefore, by using 1-MPD as an auxiliary agent, high power generation efficiency can be obtained even at low pressure, and the cost can be reduced because the design pressure of the device can be significantly reduced.

  It was also found that the thermal efficiency of the Xe hydrate engine cycle is higher than that of the Kr hydrate engine cycle using 1-MPD. However, the reaction of Xe hydrate was unstable. Furthermore, it has been found that the thermal efficiency of the Kr hydrate engine cycle with 1-MPD is higher than that of the methane hydrate engine cycle.

  As shown to FIG. 3 (a), (b), it turned out that the engine cycle of Kr hydrate using 1-MPD has thermal efficiency higher than the conventional Rankine cycle of ammonia. In addition, although the engine cycle of Kr hydrate using 1-MPD has thermal efficiency slightly lower than that of the conventional propane Rankine cycle, it is nonflammable and thus avoids combustion or explosion in the power generation system. be able to.

In addition, the power generation amount per unit volume of the gas sucked into the expander was derived. As a result, when the Kr hydrate engine cycle using 1-MPD, is 1.699 (kW / ^{m 3),} if the methane hydrate engine cycle, met 2.529 (kW / ^{m 3)} The Thus, although the amount of power generated per unit volume is larger for the engine cycle of methane hydrate than for the engine cycle of Kr hydrate, since the Kr hydrate is noncombustible, it will burn or explode in the power generation system Can avoid the situation.

Moreover, it is 0.082 (kW / m < ³ >) in the case of the Rankine cycle of ammonia, and is 0.083 (kW / m < ³ >) in the case of the Rankine cycle of propane, R-404A (molecular weight: 107.75). In the case of a Rankine cycle of 0.128 (molecular weight: 107.75). Therefore, it has been found that the engine cycle of hydrate such as Kr hydrate has a large amount of power generation per unit volume as compared to the conventional Rankine cycle of gas.

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is obvious that those skilled in the art can conceive of various changes or modifications within the scope of the claims, and it is naturally understood that they are also within the technical scope of the present invention. Be done.

  For example, in the above embodiment, Kr gas has been described as an example of the inert gas. However, the inert gas may be a noble gas (helium, neon, argon, xenon, radon (Rn)), nitrogen or carbon dioxide. In any case, the occurrence of combustion or explosion in the power generation system 100 by generating an inert gas hydrate and further decomposing the hydrate to generate a high pressure inert gas and rotating the expander 172. Can be generated efficiently while avoiding the

  Moreover, in the said embodiment, 1-MPD was mentioned as an example and demonstrated as an adjuvant. However, the adjuvant may be appropriately selected according to the guest substance of the hydrate. For example, if the guest material is Kr, 2,2-dimethylbutane may be used as an adjunct. Further, the auxiliary agent is not essential, and the raw material water not containing the auxiliary agent may be used to form the hydrate.

  Further, in the above embodiment, the configuration in which the dehumidifying parts 160A and 160B remove water from the mixed gas by the pressure swing adsorption method has been described as an example. However, the dehumidifying part may be formed of a water separation membrane or the like as long as it can remove water from the mixed gas.

  Moreover, in the said embodiment, ocean deep-sea water was mentioned as a 1st fluid and ocean surface layer water was mentioned as an example, and it demonstrated it as a 2nd fluid. However, there is no limitation on the first fluid and the second fluid, and the second fluid may be at a higher temperature than the first fluid (the temperature difference is, for example, about 20 ° C. to 25 ° C.). For example, water at normal temperature may be employed as the first fluid, and hot spring water or high-temperature drainage may be employed as the second fluid.

  INDUSTRIAL APPLICABILITY The present invention can be used for a power generation system that generates power using temperature difference of fluid such as ocean temperature difference power generation.

DESCRIPTION OF SYMBOLS 100 Power generation system 120 Hydrate generation part 150 Hydrate decomposition part 172 Expansion machine 174 Generator 180 Heat exchanger

Claims (4)

A hydrate generation unit for cooling a gas-liquid mixture of raw material water and an inert gas with a first fluid to generate a hydrate of the inert gas;
A hydrate decomposition unit that heats the generated hydrate with a second fluid having a temperature higher than that of the first fluid to decompose it into the raw material water and the inert gas;
An expander rotated by the inert gas generated in the hydrate decomposition unit;
A generator that generates electricity by rotation of the expander;
A power generation system characterized by comprising.   The power generation system according to claim 1, wherein the inert gas is a noble gas.   The power generation system according to claim 1, wherein the raw material water contains an auxiliary agent that lowers a pressure for generating the hydrate.   The power generation system according to claim 3, wherein the inert gas is krypton, and the auxiliary agent is 1-methyl piperidine.

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