JP4261438B2 - Power generation and seawater desalination system - Google Patents

Description

  The present invention relates to a power generation and seawater desalination system that can effectively use waste heat generated in various plants and the like and perform power generation and seawater desalination without newly consuming energy.

  In the past, exhaust heat of about 150 ° C. or less generated in various plants and the like has often been released into the natural environment as it is or through a cooling process as shown in FIG. There is an increasing number of cases where energy recovery is performed using a power cycle power generation system using a non-azeotropic mixed medium such as ammonia and water as a working fluid that can perform effective work even with such a low-temperature heat source.

  An example of such a power generation system is described in Japanese Patent Laid-Open No. 10-26009. This conventional power generation system is a non-azeotropic mixed medium cycle power generation system using ammonia as a low boiling point medium component and water as a high boiling point medium, and can efficiently generate heat by converting thermal energy into turbine work. It is a mechanism.

On the other hand, as an example of energy recovery by utilizing exhaust heat from a power plant or an internal combustion engine, many examples of using an evaporative seawater desalination apparatus have recently been seen. In the case of this seawater desalination system, seawater is used as a cooling medium for condensers and heat exchangers, the temperature of seawater is increased by using exhaust heat, the evaporation rate of seawater is increased, and the amount of condensation per unit time (freshwater) It is a mechanism to increase the yield of
Japanese Patent Laid-Open No. 10-26009

  Although the conventional power generation system is configured as described above and can recover thermal energy in the form of electric power, the remaining thermal energy obtained by raising the temperature of the working fluid by exhaust heat or the thermal energy released when the working fluid condenses. The amount of energy that is not used effectively is relatively large, and it cannot be said that energy recovery is sufficient. When trying to recover the heat energy to be discharged as much as possible in the mixed medium cycle, it is necessary to make the cycle more complicated, and there is a problem that the equipment cost increases.

  The present invention has been made to solve the above-mentioned problems, and not only can exhaust heat be introduced to operate the power generation cycle, but also the remaining heat energy that could not be recovered by the power generation cycle can be recovered effectively. The purpose is to provide a power generation and seawater desalination system that can efficiently acquire power and freshwater by combining seawater desalination equipment, and can reliably recover exhaust heat to reduce energy waste and environmental impact. And

  The power generation and seawater desalination system according to the present invention evaporates the working fluid by exchanging heat between the liquid working fluid and a predetermined high-temperature fluid, and converts the thermal energy possessed by the obtained gas-phase working fluid into power. While generating power with the power, the working fluid after converting the heat energy to power is condensed by exchanging heat with a predetermined low-temperature fluid, and the working fluid is returned to the liquid phase to exchange heat with the high-temperature fluid again. A power generation apparatus comprising a power cycle that repeats the process, an evaporation means for evaporating at least a part of seawater heated by a predetermined heat dissipation means and heated, and at least seawater lower in temperature than the heated seawater as cooling water A seawater desalination device that has at least a condensing unit to be used, and condenses the water evaporated by the evaporating unit by the condensing unit to obtain water not containing salt, and the heat dissipating unit includes the evaporating unit A portion of the remaining seawater that has not evaporated is supplied as the low-temperature fluid, and the first heat dissipating means as a condenser of the power generation apparatus that heats the seawater with condensation heat when condensing the working fluid; Part of the seawater used as cooling water by the condensing means of the desalination apparatus is supplied, and the high-temperature fluid and the seawater are heat-exchanged with the liquid-phase working fluid in the power generation apparatus to heat the seawater. It comprises a second heat radiating means, and the seawater after heat exchange by the first heat radiating means and the second heat radiating means is introduced into the evaporation means of the seawater desalination apparatus in a mixed state.

  As described above, in the present invention, the power generation device and the seawater desalination device using seawater are disposed, and the working fluid of the power generation device is heated and evaporated with the high-temperature fluid, and the remaining heat energy of the high-temperature fluid and the power generation device are used. By increasing the temperature of the seawater introduced to the evaporation means of the seawater desalination system with the exhaust heat of the heat, and operating the power cycle for power generation and the seawater desalination process simultaneously with the energy obtained from the high temperature fluid, the thermal energy of the high temperature fluid is reduced. It can be effectively used for power generation and seawater desalination to sufficiently recover energy, reducing the amount of energy released as waste heat to the outside as much as possible, improving the overall thermal efficiency and increasing the power obtained by power generation. The energy consumption related to seawater desalination, including pumping work on seawater, can be covered. The power generation and desalination without giving any can continuously run, very low-cost power and fresh water is obtained.

  In addition, the power generation and seawater desalination system according to the present invention, if necessary, has a predetermined heat before the temperature of the high-temperature fluid is reduced to a temperature at which it can be handled as a product immediately after being distilled and refined in an oil refinery plant. It is the final purified product in the gas phase or liquid phase that retains energy.

  As described above, in the present invention, most of the retained heat of the final refined product refined in the oil refinery plant that has been cooled and discarded in the past is recovered by the power generation device and the seawater desalination device to obtain electric power and fresh water. The cost and effort of cooling the final refined product can be eliminated, and the energy balance of the entire plant can be greatly increased, together with the efficient production of electric power and fresh water without affecting each processing step on the oil refinery plant side. In addition, the operation cost can be reduced as compared with the case where the power generation device and the seawater desalination device are separately provided in the plant.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration explanatory diagram of a power generation and seawater desalination system according to the present embodiment.
In FIG. 1, the power generation and seawater desalination system 1 according to the present embodiment obtains power for power generation by phase change of a working fluid that exchanges heat with a final refined product fluid immediately after being refined in an oil refinery plant. The apparatus 10 includes a multistage flash evaporation type seawater desalination apparatus 20 that evaporates and condenses seawater heated by heat exchange with the final purified product fluid and the working fluid to obtain fresh water.

  The power generation apparatus 10 includes an evaporator 11 for exchanging heat between a working fluid of a power cycle for power generation (mixed water of ammonia and water, etc.) and a final purified product fluid as the high-temperature fluid, and obtaining a vapor of the working fluid. It operates with the working fluid vapor obtained in the evaporator 11, converts the thermal energy possessed by the working fluid into power, the generator 13 driven by the turbine 12, and condenses the steam exiting the turbine 12. In this configuration, the condenser 14 as the first heat radiating means in the liquid phase and the pump 15 that takes out the working fluid from the condenser 14 and introduces the working fluid into the evaporator 11 are provided. Each device that establishes the power cycle of the power generation apparatus 10 is the same as that used in a known non-azeotropic fluid mixture cycle, and detailed description thereof is omitted.

  The seawater desalination apparatus 20 includes a decompression vessel 21 whose interior space is decompressed to an atmospheric pressure or less, and a plurality of flashes as the evaporation means that obtains water vapor by flash-evaporating preheated seawater in the decompression vessel 21. An evaporation unit 22, a plurality of condensing units 23 as the condensing means for condensing water vapor obtained in the flash evaporating unit 22 in the decompression vessel 21 to obtain water containing no impurities (salt content), and the flash evaporating unit 22 A heat exchanger 25 as the second heat dissipating means for heating the seawater before being introduced into the tank, a plurality of pipelines and pumps for introducing seawater into and discharging fresh water or seawater into the decompression vessel 21 (illustrated) Is omitted).

  The flash evaporation section 22 is arranged as a plurality of compartments in the decompression vessel 21, and is provided with separators 22a that capture and remove fine water droplets (mist) of water mixed in the steam flow toward the condensation section 23. It is the structure which is made. Further, the condensing unit 23 has a heat transfer portion through which cooling water can be passed, and a plurality of the condensing units 23 are arranged corresponding to each flash evaporation unit 22 of the decompression vessel 21, and vapor evaporated by the flash evaporation unit 22. The steam is condensed by heat exchange with the cooling water, and the obtained condensed water is collected and sent to the outside. The flash evaporation section 22 and the condensation section 23 are known multi-stage flash evaporation type seawater fresh water. The configuration is the same as that of the conversion apparatus, and detailed description thereof is omitted.

  As the cooling water for each condensing unit 23, seawater taken from the sea is used, and this seawater is taken from a water intake pipe (not shown), introduced into the condensing unit 23 and used, and then from the condensing unit 23. It is taken out, part of which is directed to the heat exchanger 25 and the rest is discharged to the sea. A tank 27 for temporarily storing fresh water obtained as condensed water is also provided corresponding to the condensing unit 23.

  A decompression exhaust device 24 is connected to the decompression container 21 through a pipe line, and the interior of the decompression container 21 is decompressed to a pressure equal to or lower than the saturated vapor pressure of water at the same temperature as seawater introduced into the decompression container 21. The temperature at which the water changes from the liquid phase to the gas phase (evaporates) in the evaporating unit 22 and the temperature at which the water changes from the gas phase to the liquid phase (condenses) in the condensing unit 23 to each temperature at atmospheric pressure. It is kept low compared to it. Thereby, a part of the water introduced into the decompression vessel 21 is changed from the liquid phase to the gas phase, and the temperature of the water remaining in the liquid phase is lowered.

  A portion of the seawater that has not evaporated in the decompression vessel 21 is extracted from the decompression vessel 21 and reaches the condenser 14 of the power generation apparatus 10. After the temperature rises due to heat exchange, the seawater exits the heat exchanger 25. And the flow returns to the flash evaporation unit 22, while others are drained from the decompression vessel 21 and discharged to the sea.

  The heat exchanger 25 is supplied with a part of the seawater used as cooling water in the condensing unit 23, and heat-exchanges the seawater with the final product fluid after the seawater is heat-exchanged with the liquid-phase working fluid. And heats the seawater. The structure itself as a heat exchanger is a known one, and detailed description thereof is omitted. Seawater that leaves the condensing unit 23 and travels toward the heat exchanger 25 reaches the heat exchanger 25 via the deaerator 26, and the scale is adjusted by seawater such as pH adjustment before and after the deaerator 26. Processing for preventing occurrence and the like is also performed.

  In addition, the pipe line which sends the final refined product fluid to the evaporator 11 of the power generation apparatus 10 and the pipe line which discharges the final refined product fluid whose temperature is lowered from the heat exchanger 25 are respectively existing in the oil refinery plant. It is connected to each pipeline before and after the final purified product cooling process, and the final purified product fluid is passed to this system side without going to the cooling process, and the entire system is connected to a part of the existing plant pipeline. The bypass pipe can be arranged at low cost.

  Next, the operation state of the power generation and seawater desalination system according to the present embodiment will be described. The final refined product fluid extracted from the final refining process such as a distillation column of an oil refinery plant is about 120 ° C., and is inherently passed through a cooling process, generally cooled to about 50 ° C., and condensed from steam as necessary. After being accompanied by a phase change such as becoming a liquid, it is delivered as a product. Instead of proceeding to the cooling step, this final purified product fluid is first introduced into the evaporator 11 of the power generation apparatus 10 from the plant line via the system inlet A, and operates in the liquid phase by heat exchange with the working fluid. Heat and evaporate the fluid. Although the temperature is lowered by heat exchange with the working fluid, the final purified product fluid still having a temperature higher than the outlet temperature of the cooling step leaves the evaporator 11 and then enters the heat exchanger 25 of the seawater desalination apparatus 20. Introduced and heat-exchanged with seawater to increase the temperature of seawater, while the temperature of itself is greatly reduced, discharged from the heat exchanger 25 in a state of approaching the outlet temperature of the cooling process, and existing purified product from the system outlet B Return to the unloading pipeline.

  In the power generation apparatus 10, the working fluid, which has been heated and evaporated by heat exchange with the final purified product fluid in the evaporator 11 and turned into a gas phase, operates the turbine 12, and the generator 13 is driven by the turbine 12 to generate power. I do. The working fluid that exits the turbine 12 is introduced into the condenser 14, and is condensed by heat exchange with non-evaporated seawater in the seawater desalination apparatus 20 introduced into the condenser 14, and becomes a liquid phase. Returning to the evaporator 11, each process after evaporation is repeated. Seawater used for the condensation of the working fluid in the condenser 14 receives the condensation latent heat of the working fluid and is heated to about 15 ° C.

  In the seawater desalination apparatus 20, first, seawater taken from the sea is introduced as cooling water into the condensing unit 23 through the intake pipe, and heat is exchanged with the steam around the condensing unit 23 to cool and condense the steam. The temperature rises. The seawater exits the condensing part 23 in this temperature rise state and proceeds to the drain pipe, and part of the seawater is once guided to the deaeration device 26 and removed from the seawater, and then sent to the heat exchanger 25. Discharged into the sea. In the heat exchanger 25, the introduced seawater is used as cooling water to exchange heat with the final purified product fluid separately introduced into the heat exchanger 25, and the temperature of the seawater rises. The seawater discharged from the heat exchanger 25 has a temperature about 10 ° C. higher than that at the time of introduction, and the seawater is led to the flash evaporation section 22 to desalinate.

  Seawater from the heat exchanger 25 is guided to the flash evaporation section 22 in the decompression vessel 21, and a part of the seawater is vaporized by flash evaporation in the inner space of the decompression vessel 21 where the pressure is reduced to about 10 to 60 mmHg. At the same time, the temperature of the seawater drops.

  The vapor obtained by the evaporation of moisture passes through the separator 22a and flows into the condensing unit 23 in a state where the floating liquid (mist) is removed. In the condensing unit 23, the steam is cooled by exchanging heat with lower temperature seawater as cooling water, condensed to form water droplets that do not contain salt, and once collected in the tank 27, it is collected as a collective amount of fresh water W to the outside. Sent out. The seawater that has not evaporated in the flash evaporating unit 22 reaches the flash evaporating unit 22 in the next stage, part of which evaporates and condenses in the condensing unit 23, and the same process as described above is performed in the flash evaporating unit. This is repeated for 22 stages.

  Here, the seawater that has not evaporated in each flash evaporation section 22 is temporarily stored in the lower part of the decompression vessel 21, but most of the seawater is taken out of the decompression vessel 21 and sent to the condenser 14 of the power generation apparatus 10. Sent. The seawater led to the condenser 14 is used as cooling water and warmed by heat exchange with a high-temperature working fluid. The seawater thus warmed by the condenser 14 merges with the seawater that has exited the heat exchanger 25 and is supplied to the flash evaporator 22.

  In a steady operation state, the amount of seawater exchanged by the condenser 14 and supplied to the flash evaporation unit 22 is approximately twice the amount of seawater exchanged by the heat exchanger 25 and supplied to the flash evaporation unit 22. The working fluid that has obtained the high thermal energy of the final purified product fluid is reliably condensed with a sufficient amount of cooling seawater to maximize the work for power generation, while the heat exchanger 25 The remaining heat energy of the final refined product fluid can be reliably recovered to increase the seawater temperature as much as possible, heat can be effectively recovered from the final refined product fluid, and power generation and seawater desalination can be promoted in a balanced and highly efficient manner. Will be. In addition, by using seawater that could not be evaporated again as raw water for desalination, the amount of freshly drawn seawater passing through the deaerator 26 and the heat exchanger 25 toward the flash evaporator 22 is greatly increased. It is possible to reduce the amount of pretreatment for newly taken seawater, such as degassing and pH adjustment, and to suppress the cost increase associated with water intake.

  In this way, the seawater that has not evaporated in the flash evaporation section 22 in the decompression vessel 21 is warmed by the condenser 14 of the power generation apparatus 10 and is repeatedly introduced into the flash evaporation section 22. The introduced seawater is in a stable state at a higher temperature than the seawater introduced into the condensing unit 23, and the seawater is evaporated by the flash evaporation unit 22, so that desalination can be efficiently achieved.

  On the other hand, of the seawater that has not evaporated in the flash evaporator 22, the remaining portion that is not sent to the power generation device 10 side is discharged from the decompression vessel 21 and finally discarded to the sea. Since the temperature difference between the discarded seawater and the seawater originally in the sea is sufficiently small due to heat consumption during flash evaporation, the adverse effects on the surrounding environment due to discharge are small.

  As described above, in the power generation and seawater desalination system according to the present embodiment, the final refined product refined in the oil refinery plant is conventionally cooled using the power generation apparatus 10 and the seawater desalination apparatus 20 that use seawater. By operating the power cycle for power generation and the seawater desalination process at the same time and recovering this thermal energy with the discarded thermal energy, the amount of energy released as waste heat to the outside can be reduced as much as possible. In addition to improving the thermal efficiency, it will be able to cover the energy consumption related to seawater desalination, including the pumping work for seawater, using the power generated by the power generation. In addition, power generation and seawater desalination can be carried out continuously, and extremely low-cost electric power and fresh water can be obtained. In addition, the cost and labor of special cooling for the final purified product can be omitted, and the energy balance can be greatly improved in the entire plant.

  In the seawater desalination apparatus according to the above-described embodiment, the final refined product immediately after being refined in an oil refining plant is used as the high-temperature fluid. However, the present invention is not limited thereto, and the internal combustion engine, the power plant, and iron manufacturing are used. It is also possible to use cooling water, exhaust gas, and plant fluid generated at various plants such as incinerators or garbage incineration facilities, which can effectively use energy as well as the above and suppress the influence on the surrounding environment.

BRIEF DESCRIPTION OF THE DRAWINGS It is schematic structure explanatory drawing of the electric power generation and seawater desalination system which concern on one embodiment of this invention. It is a cooling process schematic explanatory drawing of the conventional plant.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power generation and seawater desalination system 10 Power generation apparatus 11 Evaporator 12 Turbine 13 Generator 14 Condenser 15 Pump 20 Seawater desalination apparatus 21 Depressurization container 22 Flash evaporation part 22a Separator 23 Condensing part 24 Depressurization exhaust apparatus 25 Heat exchanger 26 Desorption Ventilator 27 tank

Claims (3)

The liquid-phase working fluid is heat-exchanged with a predetermined high-temperature fluid to evaporate the working fluid, and the thermal energy possessed by the obtained gas-phase working fluid is converted into motive power, and power is generated with the motive power. A power generation apparatus comprising a power cycle that repeats the process of exchanging heat with a predetermined low-temperature fluid to condense and condensing the working fluid after conversion into motive power, returning the working fluid to the liquid phase and exchanging heat with the high-temperature fluid again;
One or a plurality of evaporating means for evaporating at least a part of the seawater heated by a predetermined heat radiating means and heated, and one or a plurality of condensing means using at least a seawater lower in temperature than the heated seawater as cooling water A seawater desalination apparatus that has at least the water evaporated by the evaporation means to condense the moisture by the condensation means to obtain water that does not contain salt.
A part of the remaining seawater that has not evaporated by the evaporating means is supplied as the low-temperature fluid, and the heat dissipating means serves as a condenser of the power generation apparatus that heats the seawater with condensation heat when condensing the working fluid. The high-temperature fluid and seawater after a part of the seawater used as cooling water by the first heat dissipating means and the condensing means of the seawater desalination device is supplied and heat-exchanged with the liquid-phase working fluid by the power generation device A second heat dissipating means that heats seawater by exchanging heat,
The power generation and seawater desalination system, wherein the seawater after heat exchange by the first heat dissipation means and the second heat dissipation means is introduced into the evaporation means of the seawater desalination apparatus in a mixed state. In the power generation and seawater desalination system according to claim 1,
The high-temperature fluid is a gas or liquid final refined product having a predetermined heat energy immediately after being distilled and refined in an oil refinery plant and before the temperature is lowered to a temperature at which it can be handled as a product. Power generation and seawater desalination system. An evaporator that evaporates the working fluid by exchanging heat between the liquid-phase working fluid and a predetermined high-temperature fluid, a turbine that converts the thermal energy of the obtained gas-phase working fluid into power, and the power obtained by the turbine A generator for generating electricity, and a generator having a condenser for exchanging heat with the seawater to convert the working fluid after converting the thermal energy into motive power and returning it to the liquid phase;
One or a plurality of evaporating means for evaporating at least a part of the seawater heated by a predetermined heat radiating means and heated, and one or a plurality of condensing means using at least a seawater lower in temperature than the heated seawater as cooling water A seawater desalination apparatus that has at least the water evaporated by the evaporation means to condense the moisture by the condensation means to obtain water that does not contain salt.
The high-temperature fluid supplied from the outside is subjected to heat exchange with the working fluid in the evaporator of the power generation device, and then introduced into at least one heat dissipating means of the seawater desalination device to exchange heat with seawater.
The seawater supplied from the outside was heated through the condensing means and the heat dissipating means of the seawater desalination apparatus, and then introduced into the evaporating means to partially desalinate, while the evaporating means did not evaporate. A part of the remaining seawater is introduced into the condenser of the power generation apparatus, and the process of renewing the seawater heated by the condensation heat and introducing it into the evaporation means of the seawater desalination apparatus is repeated to obtain a desalinated amount. A power generation and seawater desalination system characterized by replenishing the corresponding seawater by the amount supplied from the outside.

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