JP4554527B2 - Energy-saving equipment using waste heat - Google Patents

Description

  The present invention relates to a boiler-steam turbine facility using a heat pump, for example, an energy-saving facility for utilizing waste heat of a power plant and an energy-saving operation method.

  As an example of recovering unused thermal energy by a heat pump, there is a conventional technique known in Patent Document 1. In this prior art, the inlet feed water of the low pressure feed water heater is heated by a steam absorption heat pump installed upstream of the low pressure feed water heater.

JP-A-3-906

  In the case of Patent Document 1, the amount of steam used directly decreases due to heating by the heat pump because it is applied to the deaerator or feed water heater on the high-pressure side of the extraction source that supplies steam to these heat pumps. The amount of steam. Since these steams generally use steam turbine bleed steam, even if the amount of bleed steam is reduced, the effect of the reduction is limited to the work after the steam turbine stage after the extraction steam is taken out. There is a problem that it ends up.

  The object of the present invention is to improve the utilization efficiency of unused energy recovered compared with the prior art when recovering waste heat using a heat pump, and to reduce the boiler fuel or increase the evaporation amount and increase the steam turbine output. It is to provide energy-saving equipment for heat utilization.

The present invention relates to a boiler, an air system for combustion with a boiler equipped with an air preheater, a steam operation system including a steam turbine driven by steam generated in the boiler, and condensing steam operated by the steam turbine to form the boiler In an energy-saving facility provided in a boiler-steam turbine facility using steam as a heat source with a condensate circulation system circulating in the steam system and a heat pump attached to the circulation system,
Steam extracted from the steam operating system is used as a power source, heat is absorbed from a low-temperature heat source, heat is recovered in a heat transfer fluid, and the heat pump is provided with a heat transfer fluid circulation system,
The hot fluid recovered by the heat pump is introduced into the boiler combustion air heating heat exchanger provided in the boiler combustion air system on the inlet side of the air preheater through the heat medium fluid circulation system. Provided is an energy saving facility provided in a boiler-steam turbine facility characterized in that boiler combustion air is heated.

  Further, the present invention provides a condensate whose temperature is raised by condensing the condensate from the condensate circulation system, exchanging heat with the boiler waste gas discharged from the air preheater and introduced into the heat exchanger for recovering boiler waste heat. Is returned to the condensate circulation system, and an energy saving facility provided in a boiler-steam turbine facility is provided.

  Further, the present invention is a method in which a hot metal fluid is branched from a heat medium fluid circulation system, is heat-exchanged with boiler waste gas discharged from the air preheater and introduced into a boiler heat recovery heat exchanger, The present invention provides an energy saving facility provided in a boiler-steam turbine facility, wherein the heated hot fluid is returned to the hot fluid circulation system.

  Further, according to the present invention, the hot-steam fluid from the hot-steam fluid circulation system is branched on the inlet side or the outlet side of the boiler combustion air heating heat exchanger. Provided is an energy saving facility provided in a boiler-steam turbine facility which is returned to an outlet side or an inlet side of a heat exchanger for heating air for boiler combustion.

  In addition, the present invention provides an energy saving facility provided in a boiler-steam turbine facility, characterized in that a desulfurization device is provided in a system between an air preheater and the boiler waste heat recovery heat exchanger.

Furthermore, the present invention provides a boiler, an air system for combustion with a boiler equipped with an air preheater, a steam operating system having a steam turbine driven by steam generated by the boiler, and condensing steam operated by the steam turbine. A condensate circulation system that circulates to the boiler, and a heat pump that is attached to the circulation system, uses steam extracted from the steam operation system as a power source, absorbs heat from a low-temperature heat source, and recovers heat to a hot fluid. In the energy saving operation method by the energy saving equipment provided in the boiler-steam turbine equipment using steam as a heat source,
Using the heat transfer fluid recovered by the heat pump as a heat source, it is introduced into the boiler combustion air heating heat exchanger provided in the boiler combustion air system on the inlet side of the air preheated air to heat the boiler combustion air The present invention provides an energy saving operation method using an energy saving facility provided in a boiler-steam turbine facility.

  In the present invention, a heat pump is used to pump waste heat to the condenser, which is used to heat boiler combustion air, thereby improving the utilization efficiency of the recovered unused energy compared to the prior art. It is possible to provide an energy saving facility using waste heat that can increase boiler combustion reduction, increase evaporation, and increase steam turbine output.

  The first embodiment for achieving the above object includes a heat pump that uses waste heat of an energy supply facility such as a bearing cooling facility of a steam turbine and a condenser cooling water system, and the heat pumped up by this heat pump. A heat exchanger for heating air for boiler combustion that directly or indirectly recovers heat to the boiler combustion air as a heat transfer fluid is installed, and the heat exchanger is installed on the inlet side of the air preheater in the boiler intake system There is.

  That is, for example, 90 ° C hot water pumped up from the steam turbine condenser heat pump by a steam absorption heat pump is supplied to the heat exchanger with the boiler combustion air, and the intake air temperature into the boiler is changed from 20 ° C to 50 ° C. When the temperature is raised to 0 ° C., the amount of heat brought into the boiler increases by the amount of 30 ° C. increase in the combustion air temperature. As a result, it is possible to save boiler fuel required to generate the same amount of steam, or to increase the amount of boiler-generated steam with respect to the same amount of boiler fuel used.

  In this case, if the air temperature at the inlet of the air preheater on the boiler intake side increases, the heat transfer characteristics of the heat exchanger will increase the exhaust gas temperature at the outlet of the air preheater on the boiler exhaust gas side. However, this reduces the heat recovery effect of the heat pump to the boiler intake side, which increases the heat transfer area of the boiler economizer on the inlet side of the air preheater in the boiler exhaust gas system, and reduces the amount of heat exchanged in the boiler economizer. By increasing, it is avoided by lowering the air preheater inlet temperature on the boiler exhaust gas system side.

  However, it is easy to increase the heat transfer area of a boiler economizer when designing from the beginning with a new boiler, but it is not always easy for an existing boiler.

  Therefore, in the second embodiment, a heat exchanger that performs heat recovery using a liquid having a temperature lower than that temperature is installed on the boiler exhaust gas side, and air preheating is performed by preheating boiler intake air on the inlet side of the air preheater. It is intended to compensate for the decrease in the heat exchange amount of the boiler, that is, the decrease in the heat recovery amount of the boiler exhaust gas, and recover the recovered thermal energy in the energy supply facility.

  In other words, when recovering the waste heat pumped up by the heat pump to the existing boiler intake system, the specifications such as the heat transfer area of the boiler economizer are determined based on the case where there is no heat recovery from the heat pump. In this case, it is considered that expansion of the heat transfer area is difficult because it is already incorporated in the boiler body and the boiler frame. In this case, a boiler waste heat recovery heat exchanger that recovers the heat of the boiler exhaust gas system is provided in a fluid having a temperature lower than that of the boiler exhaust gas to compensate for the decrease in the amount of heat recovery in the air preheater.

  The heat transfer fluid is not limited to boiler / turbine equipment such as boiler feed water and turbine condensate, but is used for heating a fluid that needs further heating at a location where the temperature is lower than the boiler exhaust gas temperature.

  The third embodiment is a boiler combustion air heating heat that preheats boiler combustion air on the inlet side of an air preheater in a boiler having an exhaust gas temperature at a chimney inlet of about 150 ° C. or higher, such as a heavy oil soot or coal fired boiler. Part of the heat transfer fluid taken out from the inlet side of the exchanger is heated by a boiler waste heat recovery heat exchanger provided on the downstream side of the desulfurization unit in the boiler exhaust gas system, and boiler combustion on the downstream side from the extraction section again The heat energy recovered from the boiler exhaust gas is used for heating the inlet heat transfer fluid of the boiler combustion air heating heat exchanger by being joined to the inlet portion of the air heating heat exchanger. On the other hand, the heat pump pumping heat quantity is secured by flowing a relatively low-temperature heat transfer fluid at the outlet of the heat exchanger for heating the combustion air for boiler combustion on the inlet side of the heat pump.

  In addition, in a boiler with a flue gas exhaust gas temperature of about 150 ° C. or more like a heavy oil fired boiler, the outlet heat transfer fluid of the boiler waste heat recovery heat exchanger is not returned to the boiler combustion air heating heat exchanger inlet. In addition, a heat exchanger is further provided on the boiler intake side of the boiler combustion air heating heat exchanger, and heat is recovered in the boiler combustion air and then recovered in the heat pump, thereby obtaining the same effect as in the third embodiment. You can also.

  The fourth embodiment is a boiler combustion air heating heat exchanger for preheating boiler combustion air on the inlet side of the air preheater in a boiler having an exhaust gas temperature of about 100 ° C. like a natural gas fired boiler. A part of the hot-steam fluid taken out from the outlet side is heated by a boiler heat recovery heat exchanger and merged with the boiler combustion air heating exchanger inlet, so that the thermal energy recovered from the boiler exhaust gas is used as boiler combustion air. Used to heat the inlet hot metal fluid of the heat exchanger for heating. On the other hand, the heat pump pumping heat quantity is secured by flowing a relatively low-temperature hot metal fluid at the outlet of the heat exchanger for heating the air for boiler combustion on the inlet side of the heat pump.

  As shown above, the boiler intake water, which is the most upstream system of the boiler, as in the boiler fuel system, is not heated by the unused energy pumped up by the heat pump as in the prior art. Heat directly. In addition, since the heating can compensate for the decrease in the amount of heat energy recovered on the boiler exhaust side in the air preheater, when the amount of unused energy pumped up by the heat pump is the same as in the conventional technology, the boiler This can be solved by increasing the amount of evaporation and reducing the amount of boiler fuel.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a system flow diagram of an embodiment relating to an energy saving facility using waste heat according to the present invention. First, the cycle of boiler-steam turbine equipment will be described.

  Fuel is supplied to the boiler 1 from the fuel supply device 2 to the boiler furnace 3. Outside air taken in from the pushing fan 4 is sent into the boiler furnace 3 through the intake duct 5. The exhaust gas after combustion in the boiler furnace 3 is discharged from the chimney 7 through the exhaust duct 6 to the atmosphere. Here, an air preheater 8 is provided between the intake duct 5 and the exhaust duct 6 so that a part of the thermal energy of the boiler exhaust can be recovered by the boiler intake air.

  On the other hand, steam generated in the boiler 1 is guided to the steam turbine 11 through the main steam pipe 9 and the main steam control valve 10. A part of the steam that has entered the steam turbine 11 is sent out of the steam turbine 11 from the extraction pipe 13 before the extraction control valve 12. In addition, the steam that has passed through the extraction control valve 12 enters the condenser 15 through the steam turbine exhaust pipe 14. Steam works inside the steam turbine, and its thermodynamic energy is converted into kinetic energy and further into electrical energy in the generator 16.

  If the extraction steam pressure is within the range set in advance for the steam turbine 11, the main steam control valve 10 and the extraction control valve 12 of the steam turbine 11 do not depend on the amount of the extraction flow from the extraction pipe 13. The electric output of the generator 16 is controlled to a substantially constant pressure while keeping it constant.

  The steam flow after the condenser 15 is cooled by the cooling water in the condenser 15 to take away the latent heat of evaporation, and the steam becomes condensed water, which is on the condensate pipe 17 as steam turbine condensate (referred to as condensate). Pressurized by the condensate pump 18 and sent to the condensate tank 19. And it is pressurized by the deaeration water supply pump 21 installed in the condensate pipe 20 of the condensate tank 19 exit, is sent to the deaerator 22, and is heated. In this way, a condensate circulation system is formed.

  The heating steam source of the deaerator 22 is supplied from the extraction pipe 13 taken out before the extraction control valve 12.

  The boiler feed water that exits the deaerator 22 is pressurized by the boiler feed pump 26 on the boiler feed pipe 25 and then returns to the boiler 1.

  In addition, the replenishing water for the entire water / steam system is treated water treated for boiler feed by adjusting the opening of the condensate tank water level control valve 28 by the water level regulator 27 installed in the condensate tank 19. This is done by replenishing from the makeup water pipe 29.

  Further, in the example of FIG. 1, the cooling water of the condenser 15 is sent to the condenser 15 through the cooling water supply main pipe 32 by the cooling water pump 31 at the outlet of the cooling tower 30, and passes through the cooling water return main pipe 33. Return to the cooling tower 30 again. The latent heat of vaporization of the steam turbine exhaust steam exhausted from the steam turbine 11 to the condenser 15 heats the condenser cooling water, and the heat energy of the heated water is evaporated by the cooling tower 30 to the atmosphere. The heat is dissipated. The lost cooling water is automatically supplied to the cooling tower lower water tank 34.

  The heat absorption source water supply pipe 36 is branched from the condenser cooling water return main pipe 33 at the outlet of the condenser 15 after the condenser 15 has exchanged heat with the latent heat of vaporization of the steam exhaust from the steam turbine 11 and the temperature rises. Pressurization is performed by a heat absorption source water supply pump 37 provided in the branch pipe 36. The heat absorption source water which is a low-temperature heat source is led to a heat pump (single effect steam absorption heat pump) 35 through a source water circulation system 38, and the source water supply of the source water circulation system 38 is supplied to an evaporator 62 which is an internal component of the heat pump 35. Supplied through tube 38A.

  The return heat source water from the evaporator 62 of the heat pump 35 passes through the source water return pipe 38B of the source water circulation system 38 and joins the condenser cooling water return main pipe 33 at the inlet of the cooling tower 30.

  The supply system of the heating steam of the heat pump 35 is branched from the steam turbine extraction pipe 13, and then the steam reduced in temperature by the temperature reducer 40 installed in the heat pump steam pipe 39 is guided to the generator 41 constituting the heat pump 35, Finally, it becomes drainage inside the heat pump 35.

  The temperature-reduced water for reducing the temperature of the steam by the temperature reducer 40 is taken out by the temperature-reduced water pipe 71 branched from the water supply pipe 25 at the outlet of the boiler feed pump 26 and is supplied to the temperature controller 42 installed at the steam pipe at the outlet of the temperature reducer 40 The heat pump inlet steam temperature control valve 43 controls the detected temperature to be a predetermined temperature.

  The steam drain of the heat pump 35 is collected in the condensate tank 19 through the drain pipe 44. Here, the heat pump drain outlet valve 45 is set to have a differential pressure so that the discharged drain does not flush inside the pipe.

  A control valve 46 installed in the steam pipe 39 at the inlet of the heat pump 35 is for adjusting the temperature of the hot water supplied from the heat pump 35. The temperature of the hot water at the outlet of the heat pump installed in the hot water supply pipe 47 at the outlet of the condenser 61 inside the heat pump 35. The amount of steam is controlled so that the water temperature detected by the regulator 24 becomes the target temperature.

  In this embodiment, the waste heat pumped up from the condenser cooling water system by the heat pump 35 forms hot water fluid, and the push fan 4 is installed by the supply pump 48 installed in the supply pipe 47A of the hot water fluid circulation system 47. Is sent to a boiler combustion air heating heat exchanger 49 installed in a boiler intake duct 5 between the air preheater 8 and the air preheater 8. The hot fluid is hot water, for example. The hot fluid from the boiler combustion air heating heat exchanger 49 is recirculated to the heat pump 35 through the return pipe 47B. Inside the heat pump 35, it passes through the absorber 60 and the condenser 61, which are its constituent devices, in this order, and is again used as a temperature rise heated from the supply pipe 47A of the heat medium fluid circulation system 47.

  The temperature change when the waste heat to the condenser cooling water is pumped to the boiler intake system with the configuration shown in FIG. 1 will be described with reference to FIG.

  The vertical axis in FIG. 2 indicates temperature, and the horizontal axis indicates each part including a boiler intake / exhaust economizer and an air preheater. The broken line indicates the temperature of each part of the boiler intake / exhaust when the waste heat recovery of the condenser 15 by the heat pump 35 is not performed, and the solid line recovers the waste heat of the condenser 15 by the heat pump 35 as shown in the first embodiment. The temperature of each part at the time of heating boiler intake air with the heat exchanger 49 installed in the boiler intake duct 5 is shown.

  In the operation state indicated by the broken line in which no heat recovery is performed by the heat pump 35, the air temperature at the inlet of the air preheater 8 is 20 ° C., which is room temperature, as indicated by the solid line when the heat pump 35 is turned on. Preheated to ℃.

  However, the gas temperature on the boiler exhaust gas outlet side of the air preheater 8 is the one where heat recovery is performed up to 150 ° C. when the heat pump is not operated as indicated by the chain line, the air heating for boiler combustion on the intake side By passing water through the heat exchanger 49, the temperature on the boiler intake side of the air preheater 8 rises and the outlet temperature of the air preheater 8 on the boiler exhaust gas side slightly increases as shown by the solid line. This means that a part of the waste heat of the condenser 15 pumped up by the heat pump is discarded to the atmosphere through the boiler exhaust duct 6 and the chimney 7 while bypassing the boiler furnace 3. That is, Example 1 shows a basic equipment configuration in the case where unused energy pumped up by installing a heat pump is collected in the boiler intake air.

  In the first embodiment, the unused energy pumped up by the heat pump is used for heating the boiler combustion air in the heat exchanger 49 provided on the boiler intake side. As a result, the amount of exchange heat in the air preheater 8 is reduced. Then, a part of the recovered heat amount escapes to the boiler exhaust gas side.

  FIG. 3 is a system flow diagram of the second embodiment that improves the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and the description of the first embodiment is incorporated. The same applies hereinafter. FIG. 3 shows an example in which a part of the condensate branched from the turbine condensate pipe 20 is led to a boiler waste heat recovery heat exchanger 50 installed in the boiler exhaust duct 6 to recover heat by raising the turbine condensate temperature. Yes. The turbine condensate whose temperature has been raised by the heat exchanger 50 joins the condensate pipe 20 again. A three-way valve installed at the junction is a boiler waste heat recovery switching valve 63 for condensate depending on whether or not the heat pump 35 is operated. This waste heat recovery raises the condensate temperature at the inlet of the deaerator 22, so that the deaerator bleed flow rate decreases and the internal flow rate of the steam turbine 11 increases, resulting in an energy saving effect.

  In this case, when the desulfurization device 51 is installed further downstream of the air preheater 8 in the boiler exhaust duct 6, the boiler waste heat recovery heat exchanger 50 is installed further downstream, The low-temperature corrosion due to sulfides of the steel is to be suppressed as much as possible. Further, in this embodiment, a recirculation pump 54, a recirculation pipe 55, a boiler waste heat recovery heat exchanger inlet heat medium fluid temperature control valve 56, a thermometer 57 and a calculation are provided around the heat exchanger 50 for boiler waste heat recovery. The temperature control valve 56 is adjusted so that the condensate temperature at the inlet of the heat exchanger 50 is maintained at a temperature higher than a temperature necessary for avoiding low temperature corrosion in the heat exchanger 50. The recirculation flow rate ratio is controlled by the opening degree command value given from.

  FIG. 4 shows the temperature change of each part of the boiler intake / exhaust in the second embodiment. In FIG. 4, the vertical axis represents temperature, and the horizontal axis represents boiler intake / exhaust parts. In Example 2, the boiler waste heat is recovered by the boiler waste heat recovery heat exchanger 50 as shown by the one-dot chain line in FIG. 4, so that the exhaust gas temperature can be recovered up to the temperature before heat recovery by the heat pump. It can be seen that this supplements the increase in the outlet temperature on the boiler exhaust gas side of the air preheater due to the increase in the air temperature at the inlet of the air preheater by the heat exchanger for heating air for boiler combustion.

  The system flow of Example 3 is shown in FIG. In the second embodiment, the heat amount of the boiler exhaust gas is collected in a system different from the heat medium fluid circulation system 47 of the heat pump. However, in the third embodiment, the heat medium fluid flowing in the heat medium fluid circulation system 47 of the heat pump 35 is shown. Have been collected. That is, in the third embodiment, instead of the turbine condensate shown in the second embodiment, a branch from a supply pipe 47A between the heat pump 35 and the boiler combustion air heating heat exchanger 49 is branched into the boiler waste heat recovery heat exchanger 50. After the heat transfer fluid is fed and the boiler exhaust heat is recovered by the boiler waste heat recovery heat exchanger 50, the heat transfer fluid is returned to the supply pipe 47A closer to the boiler combustion air heating heat exchanger 49 than the branch portion. System configuration. Around the boiler waste heat recovery heat exchanger 50, there are a recirculation pump 54, a recirculation pipe 55, a boiler waste heat recovery heat exchanger inlet heat medium fluid temperature control valve 56, a thermometer 57 and a calculation device 58. And the opening of the temperature control valve 56 is given from the arithmetic unit 58 so that the temperature of the heat medium fluid at the inlet of the heat exchanger 50 is maintained at a temperature higher than that necessary for avoiding low temperature corrosion in the heat exchanger 50. The recirculation flow rate ratio is controlled by the opening command value.

  That is, the thermometer 57 at the inlet of the boiler waste heat recovery heat exchanger 50 has a predetermined tolerance with respect to the acid dew point temperature at which the outer surface temperature of the heat transfer tube of the boiler waste heat recovery heat exchanger 50 is determined by the exhaust gas properties. The temperature control valve 56 is controlled so that the temperature having the temperature can be maintained. With this control mechanism, the temperature of the heat transfer fluid at the inlet of the boiler waste heat recovery heat exchanger 50 can be maintained at about 130 ° C. or higher during normal operation. Since this heat transfer fluid is further heated by the waste heat recovery heat exchanger 50 and then merges with the heat transfer fluid of about 90 ° C. supplied from the heat pump at the inlet of the boiler combustion air heating heat exchanger 49, the boiler The heat medium fluid temperature at the inlet of the heat exchanger 49 for heating the combustion air further rises from 90 ° C. Due to this effect, the amount of heat escaped to the exhaust gas side can be recovered again to the boiler intake side.

  A three-way valve 64 is provided at a portion where the heat transfer fluid exiting the boiler waste heat recovery heat exchanger 50 joins the heat transfer fluid inlet side of the boiler combustion air heating heat exchanger 49. The three-way valve 64 compares the heat medium fluid temperature detected by the thermometer 65 at the outlet of the boiler waste heat recovery heat exchanger 50 with the arithmetic device 66 and the heat medium fluid temperature supplied from the heat pump measured by the thermometer 24. The opening degree is controlled so that the temperature of the thermometer 65 maintains a preset temperature deviation.

  In the case of the third embodiment, the heat exchanger fluid boiler heat recovery heat exchanger 50 inlet / outlet temperature of the heat transfer fluid is recovered to the same temperature level as in FIG. However, in the second embodiment, turbine condensate is used as the heat medium fluid of the boiler waste heat recovery heat exchanger 50, whereas in the third embodiment, the heat medium fluid supplied from the heat pump 35 is used. . When the temperature of the turbine condensate of Example 2 is increased, the bleed flow rate of the deaerator 22 decreases and the internal flow rate of the steam turbine 11 increases, but as described above, it is saved as a reduction of the deaerator steam amount. Nearly 90% of the heat becomes waste heat to the condenser 15 again. That is, in the case of this prior art, only about 10% of the heat pumped-up heat amount contributes to an increase in the work amount in the steam turbine 11.

  On the other hand, in the third embodiment, the heat transfer fluid heated by the boiler waste heat recovery heat exchanger 50 is recirculated to the inlet side of the boiler combustion air heating heat exchanger 49 to increase the temperature of the boiler intake air. Since it contributes directly, the reduction rate of boiler fuel increases.

  As a fourth embodiment, a system in which the chimney inlet temperature of the boiler exhaust gas system can be lowered to about 100 ° C. as in the case of using a fuel having a low sulfur content in the fuel as in a natural gas fired boiler in FIG. The flow is shown.

  The major difference between the third embodiment shown in FIG. 5 and the fourth embodiment shown in FIG. 6 is that the branch point where the heat transfer fluid is taken out to the boiler waste heat recovery heat exchanger 50 is different from the boiler in the third embodiment shown in FIG. What is the inlet side of the combustion air heating heat exchanger 49 is the outlet side. On the other hand, the recovery destination of the heat transfer fluid after passing through the boiler waste heat recovery heat exchanger 50 is the inlet side of the boiler combustion air heating heat exchanger 49 as in the third embodiment. The boiler waste heat recovery heat exchanger 50 is provided around the recirculation pump 54, the recirculation pipe 55, the boiler waste heat recovery heat exchanger inlet heat medium fluid temperature control valve 56, and the thermometer 57 as in the third embodiment. And the arithmetic device 58, and the opening of the temperature control valve 56 is adjusted so that the temperature of the heat medium fluid at the inlet of the heat exchanger 50 is maintained at a temperature higher than that necessary for avoiding low temperature corrosion in the heat exchanger 50. Although the recirculation flow rate ratio is controlled by the opening degree command value given from the arithmetic unit 58, in the fourth embodiment, unlike the third embodiment, from the branch point of the heat transfer fluid to the heat exchanger 50 for boiler waste heat recovery. Also, the recirculation pump 54 is located upstream rather than the recirculation pipe 55 of the boiler waste heat recovery heat exchanger 50 because the recirculation pump 54 is joined to the upstream side.

  A three-way valve 64 is provided at a portion where the heat transfer fluid exiting the boiler waste heat recovery heat exchanger 50 joins the heat transfer fluid inlet side of the boiler combustion air heating heat exchanger 49. The three-way valve 64 includes a heat medium fluid temperature detected by the thermometer 65 at the outlet of the boiler waste heat recovery heat exchanger 50 and a heat medium supplied from a single effect steam absorption heat pump measured by the thermometer 24. The fluid temperature is compared and the opening degree is controlled so that the temperature of the thermometer 65 maintains a preset temperature deviation.

  In the fourth embodiment, the heat medium fluid exchanges heat with the boiler exhaust gas in the boiler waste heat recovery heat exchanger 50 after heat exchange with the boiler intake air in the boiler combustion air heating heat exchanger 49. In this case, since the acid dew point temperature of the boiler exhaust gas is low, the heat recovery of the boiler exhaust gas is originally attempted up to about 100 ° C., and the exhaust gas in the inlet heat transfer fluid of the heat exchanger 49 for heating air for boiler combustion at about 90 ° C. This is because it is difficult to recover heat. Conversely, in the case of a natural gas fired boiler, since the sulfur content in the fuel is small, the acid dew point temperature of the boiler exhaust gas is low and the generally supplied heat transfer fluid temperature should not be lower than 60 ° C. From this, the heat transfer fluid of about 90 ° C. supplied from the heat pump 35 is recovered to the boiler intake air up to about 50 ° C. in the boiler combustion air heating heat exchanger 49, and then the boiler waste heat recovery heat exchange is performed. The heat is exchanged with the boiler exhaust gas. Here, the heat medium fluid temperature at the inlet of the boiler waste heat recovery heat exchanger 50 is maintained at 60 ° C. with the heat medium fluid recirculated from the outlet side. Note that the temperature of the outlet side heat transfer fluid fluid of the heat exchanger 50 for recovering boiler waste heat is increased to about 90 ° C., and this is circulated to the inlet of the heat exchanger 49 for heating air for boiler combustion. In the exchanger 49, the temperature of the heat medium fluid at the inlet and outlet is about 90 ° C. and 50 ° C., but since the circulation amount increases, the exchange heat amount increases, and heat is recovered from the boiler exhaust to the intake air.

  FIG. 7 shows the temperature of the heat transfer fluid, boiler intake air, and exhaust gas in the case of the fourth embodiment. A broken line is a temperature change in the case of a natural gas fired boiler facility of a conventional facility, and a solid line is a temperature change in the case of the fourth embodiment.

  The heating medium fluid heated by the boiler waste heat recovery heat exchanger 50 is not returned to the inlet of the boiler combustion air heating heat exchanger 49, but is used for boiler combustion air heating in the boiler combustion air system. A heat exchanger fluid in which a heat exchanger fluid and boiler combustion air is installed on the inlet side of the heat exchanger 49, and the amount of heat recovered in the boiler waste heat recovery heat exchanger is recovered in the boiler intake air to lower the temperature. It is also conceivable to recirculate the gas to the heat pump inlet.

  Further, the temperature control of the heat transfer fluid fluid at the inlet of the boiler waste heat recovery heat exchanger 50 has a similar effect by using a fixed orifice in the recirculation pipe 55 of the boiler waste heat recovery heat exchanger 50 instead of the temperature control. Can be obtained.

  The boiler waste heat recovery heat exchanger 50 is installed on the intake / exhaust side of the air preheater, so the boiler combustion air heating heat exchanger 49 is installed on the boiler intake system. In the boiler exhaust system, installation on the downstream side of the air preheater 8 is considered a standard position. However, in the case of a natural gas fired boiler with a low acid dew point temperature if there is no layout restriction, It is also conceivable to install them on the inlet side of the air preheater 8.

  Further, in a heavy oil fired boiler, a steam type air preheater is generally provided at the intake side inlet of the air preheater. However, when the heat exchanger 49 for heating air for boiler combustion of the present invention is installed, a steam type Since the intake air temperature of the air preheater is raised, the effect of reducing the amount of auxiliary steam can be obtained.

  Moreover, although the said heat pump type was made into the single effect steam absorption heat pump, the same effect is acquired also when using other types of heat pumps, such as a double effect steam absorption heat pump and a compression heat pump.

  In addition, in the heat exchanger 49 for heating air for boiler combustion and the heat exchanger 50 for recovering waste heat from the boiler, heat medium fluid is not directly supplied from the heat pump, but is exchanged through the heat exchanger. It is also possible to do.

  It is also conceivable that a system for raising the temperature of the steam turbine condensate with a heat pump and a system for raising the temperature of the boiler intake air of the present invention may be used simultaneously or switched.

  In addition, although the cooling water of the condenser is cooled by the cooling tower, direct cooling by river water or seawater can be easily considered. In other words, in the case of direct cooling by river water or seawater, if there is a water quality problem to introduce as heat absorption source water that is a low-temperature heat source directly into the heat pump, a non-contact type heat exchanger is placed in between Endothermic source water can be used.

  In addition, the heat absorption source water is not limited to the turbine plant, and it is conceivable to use unused energy outside the boiler plant or the system.

  Further, the cycle of the steam turbine plant is a non-reheat type condensate turbine, but the same principle applies to a reheat type steam turbine.

  Further, even when the main turbine is a back-pressure steam turbine and no condenser is installed, the waste heat source serving as the heat absorption source of the heat pump is exhaust steam from the steam turbine.

  This example shows the case where the steam turbine is driven by steam generated in the boiler and the heat recovery from the condenser, which is a conventional technology, is pumped up by a heat pump to recover the heat in the condenser system at the inlet of the deaerator. The comparative effect will be described below.

  First, when recovering heat from the condenser waste heat pumped up by the conventional heat pump to the condenser system at the inlet of the deaerator, the steam condition at the inlet of the steam turbine is 3.9 MPa (gauge pressure, hereinafter all gauge pressure), Assume 400 ° C., deaerator pressure is 0.25 MPa, and steam turbine exhaust condition is −94.66 kPa. The steam turbine condensate path from the condenser to the deaerator is pressurized by the condensate pump at the condenser outlet, and once collected in the condensate tank, the deaerated water pressure provided at the condensate tank outlet Water is sent to the deaerator by a pump. And after heating deaeration by steam turbine extraction with a deaerator, water shall be sent to a boiler economizer by a boiler feed pump. As for the makeup water, treated water is replenished to the condensate tank.

  In such a configuration, the steam turbine condensate temperature at the inlet of the deaerator is about 40 ° C., which is about room temperature, whereas the water at the outlet of the deaerator becomes a saturation temperature of the internal pressure. The temperature will be close.

  At this time, if heat recovery is performed by a heat pump between the deaerator and the deaerated water supply pump and the water supply at about 40 ° C. is heated to 90 ° C., the deaerator bleed flow rate before and after the operation of the heat pump is What has been raised to 140 ° C. from 40 ° C. water supply with an air vaporizer can be reduced to about 50% steam consumption since 90 ° C. water supply can be raised to 140 ° C.

  However, even if the deaerator steam amount is reduced by about 50% here, the effect of the reduction is that in the steam turbine from the stage supplying steam extracted from the steam turbine to the deaerator to the steam turbine exhaust. It only increases the amount of work. This is because the enthalpy of the extraction stage of the deaerator steam that decreases due to the recovery of unused energy to the steam turbine condensate system has only enthalpy closer to the steam turbine exhaust than the steam turbine inlet by. In the case of this case, about 90% of the heat saved as a reduction in the amount of deaerator steam becomes waste heat to the condenser again. That is, in the case of the prior art, only about 10% of the heat pumped up by the heat pump contributes to an increase in the work amount in the steam turbine.

  On the other hand, in this embodiment, a heat pump is used to pump up waste heat to the condenser, which is used for heating boiler combustion air. Assuming that the boiler efficiency is about 85%, about 85% of the heat pumped up by the heat pump contributes to an increase in boiler evaporation. Further, assuming that the efficiency of the steam turbine power plant is about 30%, the increase rate of the work in the steam turbine with respect to the heat pumped up by the heat pump is about 26% because 30% of 85% contributes.

  This is an effect that is 2.6 times as large as the contribution rate of the prior art, which is about 10%.

  In steam turbine power generation facilities, high efficiency has been achieved through high-temperature and high-pressure main steam conditions and combined power generation facilities combined with gas turbines, but these methods are limited to new plants, Application to existing power generation facilities that already have several hundred plants is difficult.

  On the other hand, the condenser of a power plant using a steam turbine wastes more than 60% of the fuel heat input to the boiler, and is generally a facility with a high annual utilization rate. The effect is great when measures are introduced.

  The present invention uses a heat pump to pump up heat energy, such as waste heat from condenser cooling water that is currently almost unused in boiler equipment for driving such steam turbines, to reduce boiler fuel and increase evaporation. In this case, the pumped heat amount is used to raise the temperature of boiler combustion air, and heat is recovered efficiently. Therefore, it can be widely applied to boiler facilities for driving condensate turbines regardless of business use or industrial use.

It is a system flow figure of Example 1 of the energy saving facility of waste heat utilization concerning the present invention. It is a figure for demonstrating the effect of Example 1. FIG. It is a system flow figure of Example 2 of the energy saving facility of waste heat utilization which concerns on this invention. It is a figure for demonstrating the effect of Example 2 and Example 3. FIG. It is a system flow figure of Example 3 of the energy saving facility of waste heat utilization which concerns on this invention. It is a system flow figure of Example 4 of the energy saving equipment of waste heat utilization which concerns on this invention. It is a figure for demonstrating the effect of Example 4. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Boiler, 2 ... Fuel supply device, 3 ... Boiler furnace, 4 ... Push-in fan, 5 ... Intake duct, 6 ... Exhaust duct, 7 ... Chimney, 8 ... Air preheater, 9 ... Main steam pipe, 10 ... Main steam Control valve, 11 ... Steam turbine, 12 ... Extraction control valve, 13 ... Extraction pipe, 14 ... Steam turbine exhaust pipe, 15 ... Condenser, 16 ... Generator, 17 ... Condensate pipe, 18 ... Condensate pump, 19 ... Condensate tank, 20 ... Condensate pipe, 21 ... Deaerated water supply pump, 22 ... Deaerator, 23 ... Dewarmed water pipe, 24 ... Heat pump outlet hot water temperature controller, 25 ... Boiler feed pipe, 26 ... Boiler feed pump, 27 ... Water level controller, 28 ... Condensate tank water level control valve, 29 ... Supply water pipe, 30 ... Cooling tower, 31 ... Cooling water pump, 32 ... Cooling water supply mother pipe, 33 ... Cooling water return mother pipe, 34 ... Cooling Tower bottom tank, 35 ... Heat pump (single effect steam), 36 ... Branch pipe, 37 ... endothermic source water supply pump, 38 ... endothermic source water circulation system, 38A ... source water supply pipe, 38B ... source water return pipe, 39 ... heat pump steam pipe, 40 ... temperature reducer, 41 ... heat pump generator , 42 ... Temperature controller, 43 ... Heat pump inlet steam temperature control valve, 44 ... Drain pipe, 45 ... Heat pump drain outlet valve, 46 ... Heat pump outlet hot water temperature control valve, 47 ... Heat transfer fluid circulation system, 47A ... Supply piping, 47B ... Return pipe, 48 ... Hot water supply pump, 49 ... Heat exchanger for air heating for boiler combustion, 50 ... Heat exchanger for boiler waste heat recovery, 51 ... Desulfurization device, 54 ... Recirculation pump, 55 ... Recirculation pipe 56 ... Heat exchanger inlet heat medium fluid temperature control valve for heat exchanger recovery for boiler waste heat, 57 ... Thermometer, 58 ... Computing device, 60 ... Heat pump absorber, 61 ... Heat pump condenser, 62 ... Heat Pump evaporator, 63 ... boiler waste heat recovery switching valve, 64 ... three-way valve, 65 ... thermometer, 66 ... arithmetic unit.

Claims (6)

A boiler combustion air system equipped with a boiler, an air preheater, a steam operating system equipped with a steam turbine driven by steam generated in the boiler, and a recovery system for condensing steam circulated in the steam turbine and circulating it to the boiler In an energy saving facility provided in a boiler-steam turbine facility using a water circulation system and a steam equipped with a heat pump attached to the circulation system as a heat source,
Steam extracted from the steam operating system is used as a power source, heat is absorbed from a low-temperature heat source, heat is recovered in a heat transfer fluid, and the heat pump is provided with a heat transfer fluid circulation system,
The hot fluid recovered by the heat pump is introduced into the boiler combustion air heating heat exchanger provided in the boiler combustion air system on the inlet side of the air preheater through the heat medium fluid circulation system. Energy-saving equipment installed in boiler-steam turbine equipment, characterized in that boiler combustion air is heated.   The condensate according to claim 1, wherein the condensate branches from the condensate circulation system, is exhausted from the air preheater, is heat-exchanged with the boiler waste gas introduced into the boiler waste heat recovery heat exchanger, and is heated. Is returned to the condensate circulation system, and is an energy saving facility provided in a boiler-steam turbine facility.   In Claim 1, a hot-steam fluid is branched from the said heat-medium fluid circulation system, is heat-exchanged with the boiler waste gas discharged | emitted from the said air preheater, and was introduced into the heat exchanger for boiler waste heat recovery, and temperature rising An energy-saving facility provided in a boiler-steam turbine facility, wherein the heated hot fluid is returned to the hot fluid circulation system.   In Claim 3, branching of the hot-steam fluid from the hot-steam fluid circulation system is performed on the inlet side or the outlet side of the boiler combustion air heating heat exchanger. An energy saving facility provided in a boiler-steam turbine facility, which is returned to the inlet side of a heat exchanger for heating air for boiler combustion.   5. The energy saving equipment provided in a boiler-steam turbine equipment according to claim 2, wherein a desulfurization device is provided in a system between the air preheater and the boiler waste heat recovery heat exchanger. A boiler combustion air system equipped with a boiler, an air preheater, a steam operating system equipped with a steam turbine driven by steam generated in the boiler, and a recovery system for condensing steam circulated in the steam turbine and circulating it to the boiler A water circulation system and a steam pump attached to the circulation system, including a steam extracted from the steam operation system as a power source, absorbing heat from a low-temperature heat source, and recovering heat to the hot water fluid, steam as a heat source In the energy saving operation method by the energy saving equipment provided in the boiler-steam turbine equipment,
Using the heat transfer fluid recovered by the heat pump as a heat source, it is introduced into the boiler combustion air heating heat exchanger provided in the boiler combustion air system on the inlet side of the air preheated air to heat the boiler combustion air An energy-saving operation method using energy-saving equipment provided in a boiler-steam turbine equipment, characterized in that

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