JP2011196191A - Exhaust heat recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust heat recovery system which achieves a combined power generation system achieving both an increase in the power-generating capacity of an exhaust heat power generation facility and recovery of cold by an absorption refrigerating machine and which has higher efficiency by using an exhaust heat recovery boiler with middle/low-temperature exhaust gas as a heat source.SOLUTION: In the exhaust heat power generation facility, hot water generated by an economizer 11 is sent to a flasher 16 to recover steam and high-temperature water, the recovered steam is supplied to the low-pressure stage of a steam turbine 21, and also the recovered high-temperature water is used as feed water for the economizer 11. A part of or the whole high-temperature water recovered in the flasher 16 is supplied as the heat source to the absorption refrigerating machine 31, and circulating hot water whose temperature is lowered by the absorption refrigerating machine 31 is added to the feed water to lower the temperature of the feed water to the economizer 11. Thereby, the amount of heat recovered in the economizer 11 is increased, the amount of steam and high-temperature water recovered in the flasher 16 is increased, and electric-generating capacity and the amount of cold water obtained by the absorption refrigerating machine 31 are increased.

Description

  The present invention relates to an exhaust heat recovery apparatus applied to an exhaust heat power generation facility, an installation incorporating a feed water heater that heats feed water with a process gas, and the like.

  In a conventional exhaust heat power generation facility, for example, as shown in FIG. 9, a boiler is equipped with an economizer, an evaporator, and a superheater, and a part of hot water heated by the economizer is recovered as low-pressure steam through a flasher. Thus, a configuration is adopted in which the steam is introduced into the low-pressure stage of the steam turbine, and the remaining hot water is superheated by the evaporator and the superheater and then introduced into the high-pressure stage of the steam turbine as high-pressure steam.

FIG. 9 is a process flow diagram showing an example of a conventional waste heat power generation facility.
In the waste heat boiler, the superheater, the evaporator, and the economizer are installed in the order from the upstream through which the heat exhaust passes. The economizer is supplied with hot water of about 90 ° C by a boiler feed pump, and part of the hot water heated by the economizer is supplied to the brackish water drum and separated by the brackish water drum. The part is supplied to the flasher. Moreover, a part of hot water can also be supplied to other external boilers.
The waste heat boiler in this facility may be various boilers that recover the heat of exhaust gas generated in a cement firing plant, a metal smelting furnace, a chemical factory, a garbage incinerator boiler, or the like.

The brackish water drum is a container that separates the hot water produced by the evaporator into hot water and steam. The separated hot water is returned to the evaporator to boil, and then sent again to the brackish water drum for steam and hot water. To separate. The steam separated by the brackish water drum is sent to a superheater to superheat and become high pressure steam, which is supplied to the high pressure stage of the steam turbine. On the other hand, the hot water supplied to the flasher is separated into low-pressure steam and high-temperature water by the flasher. The low-pressure steam is supplied to the low-pressure stage of the steam turbine, and the hot water is mixed with the feed water of the economizer, heated again by the economizer, supplied again to the flasher, and then separated into steam and high-temperature water.
The steam turbine converts the energy of the high-pressure steam input to the high-pressure stage and the low-pressure steam input to the low-pressure stage into the rotational energy of the impeller, and converts the energy into electric power by driving the generator connected to the rotating shafts. .

  The steam, which has been expanded by working in the steam turbine and has become low pressure and low temperature, is cooled and liquefied by the condenser through the chilled water produced in the cooling tower, collected at the bottom of the condenser, and supplied from the makeup water tank. The water is sent to the economizer as boiler supply water. Note that the ground steam (seal steam) that is supplied to the shaft seal portion of the steam turbine and prevents air from leaking into the steam turbine is returned to water by the ground steam condenser after use. It is injected into the vessel and added to the boiler feed water.

In this conventional facility, the exhaust gas temperature is determined according to the water supply temperature and the water supply amount at the economizer entrance. Therefore, even if the amount of hot water collected at the flasher outlet is increased in order to increase the amount of hot water to increase the amount of power generation, the boiler feed water temperature rises, so the amount of waste heat recovered by the boiler as a whole, and hence the amount of power generation, is reduced. The exhaust gas temperature could not be increased, and the exhaust gas temperature did not drop sufficiently.
On the other hand, in the carbon dioxide (CO2) absorption and recovery equipment that will be installed in the future, it is required to further reduce the exhaust gas temperature to about 40 °, so it is necessary to develop a technique for further reducing the temperature of the boiler exhaust gas. There is.

Patent Document 1 discloses a waste heat power generation system in which a waste heat recovery rate of a suspension preheater (PH) is improved in a cement firing plant to increase a total power generation amount.
Conventionally, since the exhaust gas temperature of PH and the exhaust gas temperature of AQC are different from each other, it is common to use the outlet gas of the PH boiler for drying the cement raw material and obtain steam with the AQC boiler to generate power.

  On the other hand, in the disclosed waste heat power generation system, an economizer is provided in an AQC boiler that recovers exhaust heat from an air quenching cooler (AQC), and hot water obtained by the economizer is steamed with hot water using a flasher. The steam is supplied to the low pressure stage of the steam turbine. In addition, the PH boiler has a second evaporator on the waste gas outlet side that recovers the waste heat of PH. The return hot water from the flasher is introduced into the second evaporator via the steam drum and heated and separated by the steam drum. The steam thus produced is introduced into the low pressure stage of the steam turbine together with the steam separated by the flasher. In this way, the waste gas energy of the PH boiler is effectively recovered to increase the power generation amount.

However, the waste heat power generation system in the cement firing plant disclosed in Patent Document 1 generates steam by using an AQC boiler and generates power. On the other hand, instead of using the outlet gas of the PH boiler for drying the cement raw material, the waste of the PH boiler is used. The heat recovery rate is improved by providing a second evaporator on the gas outlet side and using the steam generated by heating the return hot water of the flasher together with the steam obtained by the AQC boiler.
That is, since the heat energy of the exhaust heat recovery boiler outside the steam turbine is used for steam power generation, it is not a method of using the waste heat recovery boiler itself that is used to supply steam to the steam turbine.

Patent Document 2 discloses a combined power generation system composed of a steam turbine and a gas turbine that effectively uses the thermal energy of the gas turbine exhaust gas as part of the heat source of the steam power plant. Patent Document 2 discloses a combined power generation system including an absorption refrigeration machine cycle device that generates cold water using steam generated by an exhaust heat recovery boiler that recovers heat from gas turbine exhaust gas.
Furthermore, the means of using the residual heat energy of the gas turbine exhaust gas, which is often used in the conventional combined power generation system, as a heating source for the steam turbine condensate not only makes the condensate system complicated, but also recovers it with a low-pressure feed water heater. Since the amount of steam extracted from the steam turbine required for heating the water is reduced, the amount of exhaust of the steam turbine is increased, which can eventually result in an increase in the condenser transmission surface.

In the combined power generation system disclosed in Patent Document 2, heat recovery is performed by using the residual heat energy of the gas turbine exhaust gas for heating the fuel of the gas turbine as an alternative to heat recovery in the condensate. In addition, it is used as a heat source for the absorption refrigerator to generate cold water.
Thus, in order to recover heat for the exhaust gas in the medium and low temperature range of about 200 ° C. or lower, which has been limited in use from the viewpoint of economy, the energy is recovered as high temperature water with the heat exchanger added to that region. Thus, a method of using it as a heat source for an absorption refrigerator has been utilized.
However, the absorption refrigerator used in Patent Document 2 is used to supply cold water to the outside of the power generation facility, and does not directly improve the power generation efficiency in the combined power generation system.

JP 2008-157183 A Japanese Patent Laid-Open No. 2004-060507

Therefore, the problem to be solved by the present invention is to provide an exhaust heat recovery device that realizes a combined power generation system that achieves both increased power generation of exhaust heat power generation equipment and cold energy recovery by an absorption refrigerator.
Another problem to be solved by the present invention is to provide a more efficient exhaust heat recovery device using an exhaust heat recovery boiler that uses medium-low temperature exhaust gas as a heat source.

  The exhaust heat recovery apparatus of the present invention includes an economizer, a flasher, and a steam turbine. The hot water generated by the economizer is sent to the flasher, the steam and the high-temperature water are recovered by the flasher, and the steam recovered by the flasher is used as the steam turbine. In the exhaust heat power generation equipment that supplies the high-temperature water collected by the flasher to the economizer as the feed water, the system is further equipped with an absorption chiller, and part or all of the high-temperature water collected by the flasher Is added to the absorption chiller as a heat source, and the temperature of the recovered water in the economizer is increased by reducing the temperature of the feed water by adding the reflux hot water whose temperature has decreased in the absorption chiller to the economizer. It is characterized by increasing the recovery amount of steam and high-temperature water, resulting in an increase in power generation amount.

In the conventional method of supplying the entire amount of high-temperature water from the flasher to the ecomizer as it is, if you try to increase the amount of heat recovered in the economizer, the hot water that has become hotter will return to the economizer. Since the temperature difference from the exhaust gas temperature cannot be ensured, the heat recovery amount eventually remains at a predetermined value.
In the exhaust heat recovery apparatus of the present invention, part or all of the high-temperature water returning from the flasher to the economizer is drawn out for the absorption refrigerator and used as a heat source to return the hot water after the temperature is lowered to the economizer. For this reason, since feed water temperature falls, the heat recovery amount in an ecomizer can be increased.

As the amount of hot water produced in the economizer increases, the amount of steam in the flasher increases, increasing the heat energy supplied to the low pressure stage of the steam turbine and increasing the amount of power generation. On the other hand, part or all of the high-temperature water generated by the flasher is taken out as a heat source for the absorption refrigerator, thereby increasing the amount of cold water to be produced. In addition, high-temperature water that has been cooled by providing energy with an absorption chiller is confused with the water supply of the economizer and lowers the temperature of the water supply to enhance heat recovery in the economizer.
Thus, in the exhaust heat recovery apparatus of the present invention, both the amount of recovered steam and the amount of high-temperature water generated by the flasher can be increased.

  In addition, the absorption refrigerator can effectively utilize the low-temperature hot water generated by the economizer using a single-effect absorption refrigerator that uses a relatively low-temperature high-temperature water of about 120 to 150 ° C. as a heat source. When seeking higher efficiency with a refrigerator, it is preferable to use a double effect absorption refrigerator that produces cold water with high efficiency using steam of about 7 to 9 atg.

  Moreover, although the low temperature water manufactured with an absorption refrigerator can be supplied as a cooling heat source for air conditioning in various places, if it is used for air conditioning in a turbine room, it is possible to reduce power consumption in the power plant. Moreover, if it uses for the intake-air cooling of a gas turbine, the efficiency of a steam turbine can be improved and electric power generation amount can be increased. Furthermore, a cooler is provided near the exhaust gas outlet of the economizer, and cold water generated by the absorption refrigerator is supplied to the cooler to cool the exhaust gas of the exhaust heat boiler. For example, the supply gas temperature is about 40 ° C. It can be adapted to a preferable carbon dioxide gas recovery treatment apparatus.

  The second exhaust heat recovery apparatus of the present invention includes an economizer, a flasher, and an absorption refrigerator, sends hot water generated by the economizer to the flasher, collects steam and high-temperature water with the flasher, The recovered high-temperature water is returned to the economizer as water supply, and part or all of the high-temperature water recovered by the flasher is supplied as a heat source to the absorption chiller, and the reflux hot water whose temperature has been reduced by the absorption chiller is supplied to the economizer. In addition to this, by reducing the temperature, the amount of heat recovered in the economizer is increased, and the amount of steam and high-temperature water recovered in the flasher is increased.

  The second exhaust heat recovery apparatus of the present invention draws out part or all of the high-temperature water recovered by the flasher that receives the hot water of the economizer as a heat source of the absorption refrigerator without necessarily attaching a steam turbine. If high temperature water is used and returned to the economizer water supply and mixed, the temperature of the water supplied to the economizer will decrease, increasing the amount of heat recovered and being supplied from the flasher to the outside. As a result, the amount of hot water and steam increases.

  By using the exhaust heat recovery apparatus of the present invention, it is possible to realize a combined power generation system that achieves both increased power generation of exhaust heat power generation equipment and cold energy recovery by an absorption refrigerator. In addition, the exhaust heat recovery boiler can provide a more efficient exhaust heat recovery apparatus that uses medium-low temperature exhaust gas as a heat source.

It is a process flow figure of the waste heat recovery apparatus concerning the 1st example of the present invention. It is a process flow figure of the waste heat recovery equipment concerning the 2nd example of the present invention. It is a process flow figure of the waste heat recovery equipment concerning the 3rd example of the present invention. It is a process flow figure of the waste heat recovery equipment concerning the 4th example of the present invention. It is a process flow figure of the waste heat recovery equipment concerning the 5th example of the present invention. It is a process flow figure of the waste heat recovery equipment concerning the 6th example of the present invention. It is a process flow figure of the waste heat recovery equipment concerning the 7th example of the present invention. It is a process flow figure of the waste heat recovery equipment concerning the 8th example of the present invention. It is a process flowchart which shows an example of the waste heat recovery apparatus by a prior art.

  Hereinafter, the exhaust heat recovery apparatus of the present invention will be described in detail using examples. In each embodiment, components having the same function are given the same reference numerals to avoid duplication of explanation.

FIG. 1 is a process flow diagram for explaining a first embodiment of the present invention.
Compared with the exhaust heat recovery device according to the prior art shown in FIG. 9, the exhaust heat recovery device of the present embodiment is provided with an absorption refrigerator, and a three-way valve is provided in the return path of hot water from the flasher to the economizer. The difference is that part of the high-temperature water separated by the flasher, which has been returned to the economizer in the past, is used as the heat source of the absorption refrigerator, and the hot water whose temperature has been reduced is mixed into the water supply to the economizer.

The configuration of the exhaust heat recovery apparatus of this embodiment will be described with reference to FIG.
High-temperature exhaust gas is supplied to the waste heat boiler 10, heat is applied to a heat exchanger installed in the order of the superheater 11, the evaporator 12, and the economizer (carbon economizer) 13 and is discharged as low-temperature exhaust gas. Hot water is supplied to the economizer 13 by a boiler feed water pump 15, a part of the hot water produced by the economizer 13 is supplied to a brackish water drum 14 by a boiler feed water flow rate control valve 14a, and a part of the hot water supplied by a flasher is supplied. It is supplied to the flasher 16 by the control valve 16a. Moreover, a part of hot water can also be supplied to another external boiler by the feed water flow rate adjustment valve 14b to the external boiler.

  The brackish water drum 14 separates the hot water generated by the evaporator 12 into hot water and steam. Hot water separated by the brackish water drum 14 and hot water supplied from the economizer 13 are supplied to the evaporator 12. The steam separated by the brackish water drum 14 is sent to the superheater 11 to be overheated to become high pressure superheated steam, which is supplied to the high pressure stage of the steam turbine 21.

  On the other hand, the hot water supplied from the economizer 13 to the flasher 16 is separated into low-pressure steam and high-temperature water by the flasher 16. The hot water is distributed by the flasher outlet three-way flow control valve 16 c, partly mixed with the water supply of the economizer 13, heated by the economizer 13 to become hot water, and the rest supplied as a heat source for the absorption refrigerator 31. Is done. In the present embodiment, an absorption refrigerator using, for example, high-temperature water at 120 to 150 ° C. as a heat source can be used. The returned high-temperature water that is used as a heat source of the absorption refrigerator 31 and whose temperature is lowered is supplied to the economizer 13. When it is necessary to withstand the water supply pressure of the economizer 13, it can be appropriately pressurized by the hot water transfer pump 32. In addition, the cooling water of the cooling tower 26 is supplied to the absorption refrigerator 31, and the cooling water whose temperature has been increased by use can be returned to the cooling tower 26 and radiated to the atmosphere.

The low pressure steam separated by the flasher 16 is supplied to the low pressure stage of the steam turbine 21.
The steam turbine 21 is driven by high-pressure steam that is input to the high-pressure stage and low-pressure steam that is input to the low-pressure stage, and generates electric power by driving a generator 22 whose rotating shafts are connected via a transmission mechanism.
The steam discharged from the steam turbine 21 is cooled and liquefied by the condenser 23 and sent as water to the economizer 13 through the condensate pump 24 and the make-up water flow rate adjustment valve 16b.
For cooling the condenser 23, cooling water produced by the cooling tower 26 is used.

The steam for sealing the shaft seal of the steam turbine 21 is condensed by exchanging heat with the condensate of the steam turbine 21 in the ground steam condenser 25 and injected into the feed water of the waste heat boiler 10.
Further, when the water supply to the waste heat boiler 10 is insufficient, the water supply is supplied to the condenser 23 from the supply water tank 28 by the supply water pump 27.

In the exhaust heat recovery apparatus of the present embodiment, the high temperature water recovered by the flasher 16 is supplied as a heat source of the absorption refrigerator 31, and the returned warm water whose temperature has decreased is supplied to the economizer 13, so the exhaust gas temperature and the temperature of the supply water The difference between the two increases and the amount of heat recovered in the economizer 13 increases.
Therefore, the amount of hot water from the economizer 13 to the flasher 16 increases, the amount of steam recovered in the flasher 16 increases, and the amount of power generated by the generator 22 increases. In addition, the amount of high-temperature water recovered in the flasher 16 increases, and the amount of heat supplied to the absorption refrigerator 31 also increases.
For example, in the case of a single-effect high-temperature water absorption refrigerator using a heat source of 120 to 150 ° C., the recovered high-temperature water can be used as a heat source if the operating pressure of the flasher 16 is set to 2 to 3 atg.

By using the exhaust heat recovery apparatus of the present invention, it is possible to realize a combined power generation system that achieves both an increase in the amount of power generated by the exhaust heat power generation facility and cold energy recovery by an absorption refrigerator.
In addition, the exhaust heat recovery boiler can provide a more efficient exhaust heat recovery apparatus that uses medium-low temperature exhaust gas as a heat source.
On the other hand, in the carbon dioxide (CO2) absorption and recovery equipment that will be installed in the future, it is required to further reduce the exhaust gas temperature to about 40 °, so it is necessary to develop a technique for further reducing the temperature of the boiler exhaust gas. There is.

FIG. 2 is a process flow diagram for explaining a second embodiment of the present invention.
The exhaust heat recovery apparatus of the present embodiment is a double-effect absorption refrigerator that uses steam and high-temperature water as a heat source as an absorption refrigerator, or a refrigeration facility that is equipped with a double-effect steam absorption refrigerator and a single-effect high-temperature water absorption refrigerator. It is intended to recover exhaust heat more efficiently. Compared to the first embodiment, in addition to the low pressure flasher, an intermediate pressure flasher that is operated at a higher pressure is installed, an intermediate pressure flasher and a low pressure flasher are installed in series, and the steam of the intermediate pressure flasher and the low pressure flasher The only difference is that high-temperature water is used as the heat source for the absorption refrigerator, so I will focus on the differences.

  In this embodiment, the hot water produced by the economizer 13 is introduced through the intermediate pressure flasher pressure control valve 17a, and separated into, for example, 7 to 9 atg of medium pressure steam and high temperature water and recovered. 17 is further provided. The high temperature water separated by the intermediate pressure flasher 17 is introduced into the low pressure flasher 16 operated at, for example, 2 to 3 atg via the flow rate control valve 17b, and is separated into low pressure steam and high temperature water. When the low-pressure flasher 16 runs short of high-temperature water, the amount of low-pressure steam and high-temperature water can be ensured by supplying hot water from the economizer 13 via the flasher refill hot water flow rate adjustment valve 16a.

  The medium pressure steam obtained by the medium pressure flasher 17 is supplied as a heat source of the absorption chiller 31 via the steam supply amount adjusting valve 17c. The high-temperature water generated by the low-pressure flasher 16 is partly or wholly supplied as a heat source of the absorption refrigerator 31 by the flasher outlet three-way flow control valve 16c, as in the first embodiment. The high-temperature water whose temperature has returned from the absorption refrigerator 31 is added to the water supply of the economizer 13 to lower the temperature of the water supply, and thus the amount of heat recovered in the economizer 13 can be increased.

  By using the medium pressure steam recovered by the medium pressure flasher 17 as a heat source for the double effect absorption refrigerator 31, the efficiency of the absorption refrigerator is increased and energy is saved. Usually, a double effect steam absorption refrigerator has a steam consumption of about 40% less than that of a single effect steam absorption refrigerator and has a large energy saving effect.

The high temperature water recovered by the intermediate pressure flasher 17 is supplied to the low pressure flasher 16, and the generated low pressure steam is supplied to the low pressure stage of the steam turbine and recovered by electric power. A part of the intermediate pressure steam recovered by the intermediate pressure flasher 17 may be supplied to the intermediate pressure stage of the steam turbine 21 to recover energy with electric power.
The high-temperature water recovered by the low-pressure flasher 16 may be used as a heat source (120 to 150 ° C.) of a single-effect high-temperature water absorption refrigerator that is juxtaposed with a double-effect steam absorption refrigerator.

  In the case of using an energy-saving double-effect absorption refrigerator used in the so-called Genelink method, generally, hot water of 85 to 95 ° C. is used as a heat source, so that the low temperature of, for example, about 40 ° C. is set by the high temperature water temperature control valve 16d. The water supply may be mixed with high-temperature water supplied from the low-pressure flasher 16 to adjust the temperature, and then supplied to the absorption refrigerator 31.

The economizer return flow rate control valve 14c is a control valve that introduces hot water into the feed water from the outlet of the economizer 13 when the feed water temperature to the economizer 13 is too low, and maintains the feed water temperature within a predetermined range. is there. This valve is installed as needed.
The intermediate pressure steam backup flow rate control valve 14 d is a control valve that replenishes the intermediate pressure flasher 17 with steam from the brackish water drum 14 when the steam generated by the flasher is insufficient.

  According to the exhaust heat recovery apparatus of the present embodiment, the absorption refrigerator is operated using a part of the amount of heat recovered by the economizer 13, and the low-temperature warm water returning from the absorption refrigerator is mixed to supply water to the economizer 13. Thus, the amount of heat recovered in the economizer 13 can be increased, and at the same time, the amount of steam supplied to the low pressure stage and the intermediate pressure stage of the steam turbine 21 can be increased to increase the amount of power generation. Furthermore, the efficiency of exhaust heat recovery is improved by utilizing an efficient double-effect absorption refrigerator.

FIG. 3 is a process flow diagram for explaining a third embodiment of the present invention.
Compared with the second embodiment, the exhaust heat recovery apparatus of the present embodiment further improves the efficiency of exhaust heat power generation by collecting and using low-pressure steam by dividing the low-pressure flasher into two stages.
As shown in FIG. 3, the exhaust heat recovery apparatus of the present embodiment is a second low pressure flasher that operates at an intermediate pressure between the low pressure flasher 16 and the intermediate pressure flasher 17 as compared with the process of the second embodiment. The only difference is that the second low-pressure flasher 18 and the first low-pressure flasher 16 corresponding to the low-pressure flasher 16 of the second embodiment are connected in series, with a low-pressure flasher formed in series.
In the following, description will be given with an emphasis on differences from the second embodiment.

  In the present embodiment, the high-temperature water separated by the intermediate pressure flasher 17 operated at, for example, 7 to 9 atg is fed into the second low pressure flasher 18 operated at, for example, 3.5 to 6 atg via the flow rate control valve 17b. Flashed and separated into second low pressure steam and hot water. The high-temperature water separated by the second low-pressure flasher 18 is supplied to the first low-pressure flasher 16 operated at, for example, 2 to 3 atg via the flow rate control valve 18b and separated into the first low-pressure steam and the high-temperature water. The high-temperature water generated by the first low-pressure flasher 16 is distributed to the economizer 13 and the absorption refrigerator 31 and sent.

  The first low pressure flasher 16 and the second low pressure flasher 18 are provided with a flasher replenishment hot water flow rate control valve 16a for introducing hot water produced by the economizer 13 and a second low pressure flasher pressure control valve 18a, respectively. Thus, each operating pressure can be maintained.

Similar to the exhaust heat recovery apparatus of the second embodiment, the intermediate pressure steam generated by the intermediate pressure flasher 17 is supplied to the absorption refrigerator 31 as a heat source, and the first low pressure steam generated by the first low pressure flasher 16 is the steam turbine. 21 to the first low pressure stage.
In the exhaust heat recovery apparatus according to the present embodiment, the second low-pressure steam generated by the second low-pressure flasher 18 is further supplied to the second low-pressure stage of the steam turbine 21 to increase the thermal energy recovered by the steam turbine 21. This will increase the amount of recovered power and further improve exhaust heat power generation efficiency.

FIG. 4 is a process flow diagram for explaining a fourth embodiment of the present invention.
The waste heat recovery apparatus of the present embodiment differs from the second embodiment in that the waste heat boiler is a multi-pressure boiler composed of a high-pressure boiler section upstream of the gas and a low-pressure boiler downstream of the gas.
The high-pressure boiler section is composed of a superheater 11, an evaporator 12, an economizer 13, and a brackish water drum 14, and generates high-pressure steam and medium-pressure steam having high pressure and temperature. Supply to the pressure stage. The low-pressure boiler unit includes a low-pressure evaporator 41, a low-pressure economizer 42, and a low-pressure steam drum 44, generates low-pressure steam, and supplies it to the low-pressure stage of the steam turbine 21.

In the present embodiment shown in FIG. 4, hot water is supplied from the economizer 13 to the flasher 16 via the flasher replenishment hot water flow rate adjustment valve 16a. For example, the medium pressure steam recovered by the flasher 16 operated in an intermediate pressure range of 7 to 9 atg is used as the heat source steam of the absorption chiller 31 via the steam supply amount adjusting valve 16e, and the remaining steam is the steam turbine. 21 is supplied. The high-temperature water recovered by the flasher 16 can be partly or wholly branched by the flasher outlet three-way flow control valve 16c and used as a high-temperature water heat source for the absorption refrigerator 31.
When using medium-pressure steam, a double-effect absorption chiller with low steam consumption and high efficiency can be adopted, and the steam saved by the absorption chiller can be used as steam for power generation of the steam turbine 21. it can.

In the low pressure boiler section, hot water is supplied to the low pressure economizer 42 by the boiler feed pump 15. A part of the hot water produced by the economizer 42 is supplied to the low-pressure steam drum 44 by the low-pressure boiler feed water control valve 44a, and a part is returned to the water supply to the low-pressure economizer 42 via the low-pressure economizer return flow rate control valve 44b. It is. Moreover, the high temperature water produced | generated with the low pressure brackish water drum 44 is supplied by the high pressure feed water pump 45 as feed water of the economizer 13 of a high pressure boiler part.
The low pressure steam separated by the low pressure brackish water drum 44 is added to the low pressure stage of the steam turbine 21.

  Since the low-pressure boiler part is installed in the waste heat boiler 10 in addition to the high-pressure boiler part in the waste heat boiler 10, the waste heat recovery can be achieved to a higher degree. Further, since part or all of the high-temperature water returned to the low-pressure economizer 42 from the flasher 16 is extracted and used as a heat source for the absorption refrigerator 31, the hot water whose temperature has decreased is joined to the water supply of the low-pressure economizer 42 and supplied. At the same time when the absorption refrigerator 31 is operated, the efficiency of heat recovery can be improved by the decrease in the feed water temperature in the low-pressure economizer 42.

Further, in FIG. 4, a cold water cooler 43 is installed at the gas downstream side of the waste heat boiler 10 to further reduce the exhaust gas temperature discharged from the waste heat boiler 10. The cold water supplied to the cold water cooler 43 is supplied from the absorption refrigerator 31 as cold water of about 7 ° C., for example, and when the pressure of the cold water is insufficient, a cold water pump 48 is installed for pressurization. A necessary amount is supplied to the cold water cooler 43 by using the cold water flow rate adjusting valve 43a to adjust the exhaust gas temperature. When the exhaust gas temperature is set to 40 ° C. or lower, the carbon dioxide absorption treatment device (not shown) installed downstream of the waste heat boiler 10 can be operated efficiently, and the amount of carbon dioxide in the exhaust gas can be reduced.
In addition, when a water vapor | steam component exists in exhaust gas and the drainage by condensation occurs, it can be made easy to eliminate by providing a drain discharge port on the exhaust gas side of the waste heat boiler 10.

FIG. 5 is a process flow diagram for explaining a fifth embodiment of the present invention.
The exhaust heat recovery device of the present embodiment is applied to a multi-pressure boiler as in the fourth embodiment. Compared to the fourth embodiment, the exhaust heat recovery apparatus is a low pressure economizer instead of taking hot water supplied to the flasher from the economizer 14. 42, and the water cooled by the cooling tower 26 is used upstream of the cold water cooler 43 using low-temperature cold water produced by the absorption refrigerator 31 in the exhaust gas discharge section of the waste heat boiler 10. The difference is that the cooling water cooler 46 is provided to save the consumption of cold water and the exhaust gas of the waste heat boiler 10 is further cooled.
The cooling cooler 43 adjusts the respective refrigerant supply amounts required for reducing the exhaust gas temperature by the cooling water flow rate adjustment valve 43a, and the cooling water cooler 46 by the cooling water flow rate adjustment valve 46a.

The high-temperature water recovered by the low-pressure flasher 16 is also derived from the low-pressure economizer 42 and thus becomes colder, but can be used as a heat source for a so-called Genelink single-effect absorption refrigerator.
The low-pressure steam recovered by the low-pressure flasher 16 can be supplied to the low-pressure stage of the steam turbine 21 or used as a steam heat source for the absorption refrigerator 31.

In the waste heat recovery apparatus of the present embodiment, the exhaust gas temperature of the waste heat boiler 10 is lowered to 40 ° C. or less by increasing the amount of heat recovery in the low pressure economizer 42 to facilitate the recovery of carbon dioxide. Further, the exhaust gas temperature can be further lowered by the cooling water cooler 46 and the cooling water cooler 43, and the carbon dioxide recovery efficiency can be improved.
Since the cooling water cooler 46 is employed to reduce the load on the cooling water cooler 43, the amount of cooling water consumed in the waste heat recovery device can be reduced and the cooling water can be supplied to the outside for use.
In addition, when dew condensation occurs by these coolers, a drain discharge port for removing drain can be provided in the gas discharge unit.

FIG. 6 is a process flow diagram for explaining a sixth embodiment of the present invention.
In the fifth embodiment, the cold water cooler 43 and the cooling water cooler 46 are provided at the exhaust gas discharge port of the waste heat boiler 10, whereas in the exhaust heat recovery apparatus of the present embodiment, only the cooling water cooler 46 is used. Instead, a heat exchanger 47 is provided in the cooling water supply pipe of the cooling water cooler 46 so that the cooling water for cooling the exhaust gas is cooled by the cold water of the absorption refrigerator 31. The amount of cooling water supplied to the cooling water cooler 46 is adjusted by the cooling water flow rate adjustment valve 46a, and the amount of cold water supplied to the heat exchanger 47 is adjusted by the cold water flow rate adjustment valve 47a.
Since cold water has a higher grade than cooling water, when it contains a corrosive gas such as SO _{2 in} the exhaust gas, cold water is cooled by indirectly cooling the cooling water rather than incorporating the cold water pipe directly into the waste heat boiler 10. The configuration for supplying energy is preferable in terms of maintenance.

FIG. 7 is a process flow diagram for explaining a seventh embodiment of the present invention.
The waste heat recovery apparatus of the present embodiment is a waste heat recovery apparatus that efficiently recovers heat from an independent economizer and supplies cold water and steam. The economizer, the flasher, and the absorption refrigerator are configured as main components, and the main configuration is the same as the main configuration of the first embodiment.

Referring to FIG. 7, high-temperature exhaust gas is supplied to the waste heat boiler 50, the feed water supplied to the economizer 51 is heated by the boiler feed water pump 55, and the low pressure is obtained as hot water through the refilling hot water flow rate adjustment valve 52 a. Supplied to the flasher 52. The excess hot water can be supplied as hot water to other boilers via the feed water flow rate adjustment valve 56a to the external boiler.
The hot water supplied to the low pressure flasher 52 is separated into low pressure steam and high temperature water by the low pressure flasher 52.

  The flow rate of the low-pressure steam separated and recovered by the low-pressure flasher 52 is controlled by the low-pressure steam pressure control valve 52e so as to maintain the inside of the low-pressure flasher 52 at a predetermined pressure such as 2 to 3 atg. The low-pressure steam that has passed through the low-pressure steam pressure control valve 52e is supplied to an internal or external steam turbine or absorption refrigerator, or to an external low-pressure steam demanding device.

The high-temperature water separated and recovered by the low-pressure flasher 52 is distributed by the three-way flow control valve 52c, and a part or all of it is supplied to the absorption refrigerator 53 as a heat source, and the rest is supplied to the economizer 51 as an economizer. It is heated by the miser 51 to be hot water.
The high-temperature water, for example, 110 ° C. supplied to the absorption chiller 53 is provided with heat energy by the absorption chiller 53 to reduce the temperature to, for example, 90 ° C., and then the economizer via the transfer pump 54. It is mixed in 51 water supply.

The water supply to the economizer 52 should be the temperature when it is separated by the low pressure flasher 52, for example 110 ° C., if there is no return high temperature water from the absorption refrigerator 53, but it returns from the absorption refrigerator 53 to a low temperature. The temperature is lowered by mixing the hot water that has become. For this reason, the amount of heat recovery in the economizer 51 increases, and the amount of hot water to the low pressure flasher 52 can be increased.
Therefore, in the exhaust heat recovery apparatus of the present embodiment, when the amount of high-temperature water supplied to the absorption refrigerator 53 is increased, the amount of low-pressure steam generated by the low-pressure flasher 52 is increased. Both supply quantities can be increased.

The boiler feed pump 55 is used for flowing water to the economizer 51. The makeup water flow rate adjustment valve 52b is a regulation valve that replenishes water from a makeup water tank (not shown) when the water supply to the economizer 55 decreases due to vaporization or the like. Furthermore, when the absorption chiller 53 is a refrigerator that uses low-pressure steam as a heat source or a refrigeration apparatus that includes an absorption chiller that uses low-pressure steam as a heat source, the steam supply amount adjustment valve 52f is a low-pressure steam supply pipe. Is a control valve for supplying low-pressure steam to such a refrigerator.
Further, the cooling water used for the absorption refrigerator 53 may be supplied from an appropriate cooling water supply facility in the waste heat recovery apparatus or outside.

FIG. 8 is a process flow diagram for explaining an eighth embodiment of the present invention.
The exhaust heat recovery apparatus of the present embodiment can use a dual-effect absorption chiller with high efficiency by generating an intermediate pressure steam by adding an intermediate pressure flasher to the waste heat recovery apparatus of the seventh embodiment. However, there is no particular difference in other configurations.

  That is, in this embodiment, hot water produced by the economizer 51 is introduced through the intermediate pressure flasher pressure control valve 57a, and separated into, for example, 7 to 9 atg of medium pressure steam and high temperature water for recovery. A pressure flasher 57 is further provided. The high temperature water separated by the intermediate pressure flasher 57 is introduced into the low pressure flasher 52 operated at, for example, 2 to 3 atg via the flow rate control valve 57b, and separated into low pressure steam and high temperature water. When the low-pressure flasher 52 is short of high-temperature water, the amount of low-pressure steam and high-temperature water can be ensured by supplying hot water from the economizer 51 via the refill hot water flow rate adjustment valve 52b.

The intermediate pressure steam obtained by the intermediate pressure flasher 57 is supplied as a heat source of the absorption refrigerator 53 through the steam supply amount adjusting valve 57c. Further, when the amount of the intermediate pressure steam supplied from the intermediate pressure flasher 57 is insufficient, the intermediate pressure steam can be replenished from the appropriate external intermediate pressure steam supply source via the intermediate pressure steam backup flow rate adjustment 56b.
About this other structure, it is not different from the waste heat recovery apparatus of 7th Example.
The waste heat recovery apparatus of this embodiment improves the efficiency of exhaust heat recovery compared to the apparatus of the seventh embodiment by utilizing an efficient double-effect absorption refrigerator.

  With the waste heat recovery apparatus of the present invention, it is possible to realize a combined power generation system that achieves both increased power generation of exhaust heat power generation equipment and cold heat recovery by an absorption refrigerator. In addition, the exhaust heat recovery boiler can provide a more efficient exhaust heat recovery apparatus that uses medium-low temperature exhaust gas discharged from various plants as a heat source.

DESCRIPTION OF SYMBOLS 10 Waste heat boiler 11 Superheater 12 Evaporator 13 Economizer 14 Braking water drum 14a Boiler feed water flow control valve 14b Feed water flow control valve 14c to external boiler Economizer return flow control valve 14d Medium pressure steam backup flow control valve 15 Boiler feed water pump 16 (First) (low pressure) flasher 16a Flasher replenishment hot water flow rate adjustment valve 16b Replenishment water flow rate adjustment valve 16c Flasher outlet three-way flow rate adjustment valve 16d High temperature water temperature adjustment valve 16e Steam supply amount adjustment valve 17 Medium pressure flasher 17a Medium pressure Flasher pressure adjustment valve 17b Flow rate adjustment valve 17c Steam supply amount adjustment valve 18 Second low pressure flasher 18a Second low pressure flasher pressure adjustment valve 18b Flow rate adjustment valve 21 Steam turbine 22 Generator 23 Condenser 24 Condensate pump 25 Ground steam recovery Water 26 Cooling Tawa 27 Supply Water Pump 28 Supply Water Tank 31 Absorption Refrigerator 32 Hot Water Transfer Pump 41 Low Pressure Evaporator 42 Low Pressure Economizer 43 Cold Water Cooler 43a Cold Water Flow Control Valve 44 Low Pressure Braking Drum 44a Low Pressure Boiler Water Supply Control Valve 44b Low Pressure Economizer Return Flow Control Valve 45 High pressure water supply pump 46 Cooling water cooler 46a Cooling water flow rate adjustment valve 47 Heat exchanger 47a Cold water flow rate adjustment valve 48 Chilled water pump 50 Waste heat boiler 51 Economizer 52 Low pressure flasher 52a Supply hot water flow rate adjustment valve 52b Supply water flow rate adjustment valve 52c Three-way flow control valve 52d High-temperature water temperature control valve 52e Low-pressure steam pressure control valve 52f Steam supply control valve 53 Absorption chiller 54 Transfer pump 55 Boiler feed pump 56a Feed water control valve 56b for external boiler Medium pressure steam backup flow control Valve 56c Economa Heather return flow control valve during pressure flasher 57a 57 pressure flasher pressure regulating valve 57b flow regulating valve 57c steam feed amount regulating valve

Claims (5)

  An economizer, a flasher, and a steam turbine are included, hot water generated by the economizer is sent to the flasher, separated into steam and high-temperature water by the flasher and recovered, and the steam recovered by the flasher is recovered from the steam turbine In the exhaust heat power generation equipment that supplies the high-temperature water collected by the flasher to the economizer as feed water, the system further comprises an absorption chiller, and the high-temperature water collected by the flasher A part or the whole is supplied to the absorption refrigerator as a heat source, and the amount of heat recovered in the economizer is reduced by adding low-temperature reflux high-temperature water whose temperature has decreased in the absorption refrigerator to the economizer. To increase the amount of steam and high-temperature water recovered in the flasher and increase the amount of power generation Heat recovery equipment.   The absorption refrigerator is a double-effect absorption refrigerator using high-temperature water and steam as heat sources, and the flasher supplies steam to the low-pressure stage of the steam turbine to supply high-temperature water to the economizer and the absorption refrigerator. 2. The exhaust heat recovery system according to claim 1, wherein the exhaust heat recovery unit is a two-stage flasher having a first flasher to be supplied and a second flasher for supplying steam to the absorption refrigerator and supplying high-temperature water to the first flasher. apparatus.   The exhaust heat recovery apparatus according to claim 1 or 2, wherein a cooler is provided downstream of the economizer, and cool water generated by the absorption refrigerator is supplied to the cooler to cool the exhaust gas.   An exhaust heat recovery device including an economizer, a flasher, and an absorption refrigerator, wherein hot water generated by the economizer is sent to the flasher, separated into steam and high-temperature water by the flasher, and recovered by the flasher. The recovered high-temperature water is returned to the economizer as feed water, a part or all of the high-temperature water recovered by the flasher is supplied as a heat source to the absorption chiller, and the temperature is reduced by the absorption chiller. Exhaust heat recovery characterized by increasing the recovery of steam and high-temperature water in the flasher by increasing the amount of heat recovery in the economizer by lowering the temperature by adding water to the economizer apparatus.   The absorption refrigerator is a double-effect absorption refrigerator that uses hot water and steam as heat sources, and the flasher supplies a steam to the outside and supplies the economizer and the absorption refrigerator with high-temperature water. 5. The exhaust heat recovery apparatus according to claim 4, wherein the exhaust heat recovery apparatus is a two-stage flasher including a second flasher that supplies steam to the absorption refrigerator and supplies high-temperature water to the first flasher.

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