JP2019094792A - Heat recovery power generation facility from flue gas and control method for the same - Google Patents

Abstract

To provide a heat recovery power generation facility that enables continuous operation in a stable state without causing pressure of a decompression boiler to exceed maximum use pressure.SOLUTION: A heat recovery power generation facility includes: a decompression boiler 4 for generating steam by heating heat medium water H by using flue gas G; binary power generation equipment 8 having an evaporation section 26 installed in a decompression steam chamber 22 and generating power by turning a turbine 28 by using steam obtained by heating and evaporating a refrigerant R with a low-boiling point flowing in the evaporation section 26 by using steam in the decompression steam chamber 22; a temperature detector 23 or a pressure detector 24 detecting a temperature of the heat medium water H in the decompression boiler 4 or pressure of the decompression steam chamber 22, respectively; a heat receiving section 34 that is installed in the decompression steam chamber 22 of the decompression boiler 4 and in which a cooling medium W flows; a cooling medium supply pipe 35 for supplying the cooling medium W to the heat receiving section 34; and a control valve 37 controlled by a detection signal from the pressure detector 24. On the basis of the detection signal from the pressure detector 24, the control valve 37 is opened to supply the cooling medium W to the heat receiving section 34, so as to lower pressure in the decompression boiler 4.SELECTED DRAWING: Figure 2

Description

  In the present invention, wastes such as sewage sludge containing sulfur components and municipal waste are burned in a combustion furnace (for example, an incinerator), heat is recovered from the generated combustion exhaust gas by a decompression boiler, and the heat recovered is subjected to binary power generation. TECHNICAL FIELD The present invention relates to a heat recovery power generation facility from combustion exhaust gas used for power generation by the apparatus and a control method thereof. Particularly, power generation is performed by recovering heat from combustion exhaust gas containing corrosive gas such as sulfur oxide (SOx). It is suitable for

  Generally, in a combustion facility that burns and processes waste such as sewage sludge and municipal waste, waste is burned in a combustion furnace such as an incinerator, heat is recovered from the generated flue gas by a boiler, and steam generated from the boiler is It is used to generate electricity with a steam turbine and a generator.

  However, in the above-mentioned combustion equipment, the water is evaporated by the boiler at atmospheric pressure or higher, and thus the installer needs a boiler / turbine chief engineer to install the boiler and the steam turbine, and the operator is qualified. In addition to being necessary, in terms of the amount of power generation, it will be a large-scale equipment.

Further, in the combustion equipment, the combustion exhaust gas contains sulfur oxides (SOx), (depending on the concentration of SO _3, the dew point is about 130 ° C.) condensation of SO ₃ is required sulfate corrosion protection by is there.

  On the other hand, the applicant has developed a heat recovery power generation facility from flue gas that does not require qualification as a boiler / turbine chief engineer etc. and does not cause corrosion even if heat is recovered from corrosive flue gas. (See Patent Document 1).

That is, although not illustrated, the heat recovery power generation equipment from the combustion exhaust gas is installed in a flue which flows the combustion exhaust gas generated in the combustion furnace, recovers heat from the combustion exhaust gas through the combustion exhaust gas, and It has a pressure reducing boiler whose internal pressure for heating and generating steam is kept below atmospheric pressure, and a binary power generator for heating and evaporating a low boiling point liquid refrigerant and rotating the turbine with the steam to generate electricity. The heat transfer water of the decompression boiler is an aqueous solution (lithium bromide aqueous solution) whose boiling point is equal to or higher than the dew point of SO ₃ gas contained in the combustion exhaust gas at atmospheric pressure or less, and the evaporation portion of the binary power generator Are installed in the decompression steam chamber of the decompression boiler, and the refrigerant in the evaporation section of the binary power generation apparatus is vaporized by the steam in the decompression steam chamber.

The heat recovery power generation facility from the combustion exhaust gas recovers heat by the pressure reducing boiler in which the internal pressure is maintained below atmospheric pressure and the heat medium water inside evaporates at atmospheric pressure or lower, and the boiling point of the pressure reducing boiler is the dew point of SO ₃ gas Since heat is recovered from the combustion exhaust gas using the above-described heat transfer water, qualifications such as a boiler / turbine chief engineer are not required, and sulfuric acid corrosion in the heat absorbing portion of the decompression boiler can be prevented, etc. Have the advantages of

  In addition to the above-described decompression boiler, a low-pressure boiler described in JP-A-57-33701 (refer to Patent Document 2) is known as a decompression boiler that does not require qualification by a boiler / turbine chief engineer or the like. There is.

The low-pressure boiler uses a lithium bromide aqueous solution as heat transfer water so that the boiling point is equal to or higher than the condensation temperature (130 ° C.) of SO ₃ at an operating pressure below atmospheric pressure. Further, a low pressure boiler is provided with a preheater and a heat exchanger connected thereto, and a Rankine cycle is adopted in which the working fluid (refrigerant) flowing in the preheater and the heat exchanger is preheated and boiled.

  However, the low pressure boiler does not perform heat recovery power generation from combustion exhaust gas generated by combustion of wastes such as sewage sludge as in the above-described heat recovery power generation equipment from combustion exhaust gas, and heat recovery from combustion exhaust gas by burner It is power generation, and there is no description at all regarding the pressure maintenance and temperature maintenance in the pressure reduction boiler when the amount and temperature of the flue gas fluctuate.

  In addition, as a binary power generation apparatus that recovers heat from a low-temperature heat source to generate electric power, a binary power generation apparatus described in Japanese Patent Laid-Open No. 2013-181398 (see Patent Document 3) is known.

  The binary power generation apparatus uses warm water as a heat source, adjusts the temperature of the warm water discharged from the evaporator to a predetermined temperature, and maximizes the amount of power generation.

  However, when the binary power generation system uses this binary power generation system for the heat recovery power generation equipment from the combustion exhaust gas described above, when the amount and temperature of the combustion exhaust gas suddenly change, the control of the circulation amount of refrigerant only reduces the pressure. Boiler pressure and temperature can not be within the allowable range.

  On the other hand, in the above-described heat recovery power generation facility from combustion exhaust gas, if the amount and temperature of the combustion exhaust gas fluctuate due to changes in the amount and waste calories of the waste introduced into the combustion furnace, The pressure and temperature fluctuate, and the second heat absorption side binary power generator operates to absorb the fluctuation.

  However, since the response of the binary power generation system is not quick, the heat recovery power generation facility from the flue gas responds when the fluctuation of the combustion exhaust gas is large or when the generator of the binary power generation system reaches the rated point (rated output). There was a problem that I could not do it.

  For example, when the amount and temperature of the combustion exhaust gas fluctuate in the direction of rapid increase, the internal pressure of the decompression boiler increases, and the temperature of the heat transfer water and the temperature of the evaporation water increase. At this time, the amount of heat absorption is increased by increasing the circulating amount of the refrigerant on the side of the binary power generation device.

  However, since the response of the binary power generation system is slow, the internal pressure of the pressure reducing boiler rises, and finally the safety device (safety valve etc.) set to the maximum working pressure (pressure slightly smaller than the atmospheric pressure) operates. The inside is in communication with the atmosphere, the atmosphere flows into the pressure reducing boiler, and the internal pressure of the pressure reducing boiler becomes the same pressure as the atmosphere.

  In this way, once the safety device is activated, the operation of the heat recovery power generation facility must be stopped once, and the inside of the decompression boiler must be sucked by the vacuum pump until it reaches a predetermined vacuum. The problem is that the operation efficiency and the power generation efficiency are significantly reduced.

Patent No. 6009009 Japanese Patent Application Laid-Open No. 57-33701 JP, 2013-181398, A

  The present invention has been made in view of such problems, and an object thereof is to reduce the pressure even when the amount of the flue gas flowing into the pressure reducing boiler is increased or the temperature of the flue gas is increased. It is an object of the present invention to provide a heat recovery power generation facility from flue gas and a control method thereof that enable continuous operation in a stable state without exceeding the maximum working pressure of the boiler.

  In order to achieve the above object, according to a first aspect of the present invention, combustion is carried out such that heat is recovered from combustion exhaust gas containing corrosive components which are discharged from a combustion furnace which burns waste and flows in the flue. Heat recovery power generation from exhaust gas, installed in a flue where flue gas flows, heat is recovered from flue gas through flue gas, and internal pressure for heating heat transfer water to generate steam is below atmospheric pressure The low pressure boiler and the evaporation unit are installed in the reduced pressure steam chamber of the pressure reduction boiler, and the low boiling point liquid refrigerant flowing in the evaporation unit is heated and evaporated by the steam in the reduced pressure steam chamber and the turbine is rotated by the steam to generate electricity Installed in the decompression steam chamber of the decompression boiler, and a temperature sensor or pressure detector for detecting the temperature of the heat transfer water of the decompression boiler or the pressure of the decompression steam chamber, respectively; A temperature receiving portion, a cooling medium supply pipe for supplying a cooling medium to the heat receiving portion, and a control valve interposed in the cooling medium supply pipe and controlled by a detection signal from a pressure detector; The low boiling point refrigerant of the binary power generation apparatus is circulated so that the temperature of the heat transfer water of the pressure reduction boiler or the pressure of the pressure reduction steam chamber is maintained at a predetermined temperature or pressure based on the detection signal from the detector or pressure detector. The refrigerant circulation pump is controlled to control the amount of power generation, and when the pressure in the pressure reducing boiler exceeds a set value, the control valve is opened based on the detection signal from the pressure detector and the cooling medium is transferred to the heat receiving portion To reduce the pressure in the pressure reducing boiler.

According to a second aspect of the present invention, in the first aspect, the heat transfer water of the decompression boiler is an aqueous solution whose boiling point is equal to or higher than the dew point of SO ₃ gas contained in the combustion exhaust gas under atmospheric pressure. The characteristic is that the cooling medium is water at normal temperature.

  According to a third aspect of the present invention, in the first aspect or the second aspect, the superheat pipe is disposed in the heat medium water of the depressurization boiler, and the superheat pipe is connected to the evaporation portion of the depressurization steam chamber. The present invention is characterized in that the refrigerant heated in the evaporation section is led to the superheating pipe, where the refrigerant is further heated by the heat transfer water of the decompression boiler.

  A fourth invention of the present invention is the control method of heat recovery power generation equipment from flue gas according to any of the first invention, the second invention or the third invention, wherein the pressure detector reduces pressure. The pressure in the boiler is detected, and when the pressure in the pressure reduction boiler exceeds the set value, the control valve is opened to supply the cooling medium to the heat receiving portion to reduce the pressure in the pressure reduction boiler. There is a feature.

  According to a fifth aspect of the present invention, in the fourth aspect, the control valve is gradually closed when the pressure in the pressure reducing boiler becomes equal to or lower than the set pressure.

  According to the present invention, the heat receiving portion in which the cooling medium flows is installed in the steam pressure reducing chamber of the pressure reducing boiler, the cooling medium is supplied to the heat receiving portion by the cooling medium supply pipe, and the pressure in the pressure reducing boiler is supplied to the cooling medium supply pipe. Control valve controlled based on the detection signal from the pressure detector to detect the pressure, and when the pressure in the pressure reduction boiler exceeds the set value, the control valve is controlled based on the detection signal from the pressure detector Since the cooling medium is opened to supply the cooling medium to the heat receiving part and the pressure in the pressure reducing boiler is reduced, the amount of flue gas flowing into the pressure reducing boiler is significantly increased, or the temperature of the flue gas rises sharply. Even in such a case, the decompression boiler can be operated continuously in a stable state without exceeding the maximum working pressure.

  Further, according to the present invention, even when a problem (for example, a failure of the refrigerant circulation pump) occurs on the binary power generation device side and the refrigerant can not be circulated, the cooling medium is supplied to the heat receiving unit to receive the heat receiving unit. By making the heat receiving capacity of the heat generating capacity equal to or higher than the heat receiving capacity on the side of the binary power generation apparatus, it is possible to carry out the burning treatment of waste without stopping the operation of the facility itself.

  Furthermore, according to the present invention, since the cooling medium supplied to the heat receiving portion is water at normal temperature, a large temperature difference with the pressure reducing steam chamber of the pressure reducing boiler can be obtained, and the heat receiving portion is the combustion exhaust gas and the pressure reducing boiler or pressure reducing boiler It can receive heat earlier than the refrigerant.

  Furthermore, according to the present invention, since the control valve is gradually closed when the pressure in the pressure reducing boiler becomes equal to or less than the set pressure, circulation amount control of the refrigerant by the refrigerant circulation pump on the binary power generation device side is performed. The pressure inside the pressure reducing boiler will be operated at normal pressure.

It is a schematic diagram of the combustion equipment which installed the heat recovery power generation equipment from the flue gas concerning one embodiment of the present invention. FIG. 2 is an enlarged schematic system diagram of a heat recovery power generation facility from flue gas shown in FIG. 1.

Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.
FIG. 1 shows a combustion facility provided with a heat recovery power generation facility from a combustion exhaust gas G according to an embodiment of the present invention, which combustion air preheats the combustion exhaust gas G from the combustion furnace 1 (incinerator) for combustion. Heater, white smoke prevention air preheater 3, decompression boiler 4, dust collection device 5, and scrubbing device 6 in this order, heat is recovered from the combustion exhaust gas G flowing in the flue 7 by the decompression boiler 4 and the recovered heat Is supplied to the binary power generation system 8 and used for power generation, and the flue gas G passed through the decompression boiler 4 is treated with the dust collection device 5 and the smoke cleaning device 6 and then exhausted to the atmosphere from the chimney 10 via the induction ventilator 9 To release it.

  The combustion furnace 1 burns and treats waste such as sewage sludge and municipal waste, and the combustion furnace 1 is used to dry, burn, and burn the waste on the stoker 11. An incinerator is used.

  In the above embodiment, a stoker type incinerator is used as the combustion furnace 1. However, in another embodiment, a fluidized bed type incinerator may be used as the combustion furnace 1.

  The combustion air preheater 2 is installed in the flue 7 downstream of the combustion furnace 1. The combustion air supplied from the combustion air fan 12 is preheated by the combustion exhaust gas G, and the preheated combustion air is preheated. Are supplied by the combustion air supply duct 13 below the stoker 11 of the incinerator 1.

  The white smoke prevention air preheater 3 is installed in the flue 7 downstream of the combustion air preheater 2 and heats the white smoke prevention air supplied from the white smoke prevention fan 14 with the combustion exhaust gas G. The heated white smoke preventing air is caused to flow to the flue 7 downstream of the induction ventilator 9 by the white smoke preventing air supply duct 15.

  The dust collection device 5 removes dust in the combustion exhaust gas G heat-recovered through the combustion air preheater 2, the white smoke prevention air preheater 3, and the decompression boiler 4. Conventionally, known bag filters are used.

  In the above embodiment, a bag filter is used as the dust collecting device 5. However, in other embodiments, an electric dust collector, a ceramic dust collector, or the like may be used.

  The scrubbing device 6 removes the acid gas in the flue gas G by bringing the flue gas G introduced into the inside of the device into contact with the water sprayed from the nozzle 16. A smoke water circulation pump 17, a flush water discharge pump 18 for discharging dirty flush water, and a flush water supply pump 19 for supplying fresh flush water are provided.

  And as shown in FIG. 2, the heat recovery power generation facility from the combustion exhaust gas G according to the present invention, as shown in FIG. 2, the flue 7 which flows the combustion exhaust G (white smoke prevention air preheater 3 and the flue 7 between the bag filter 5 ), Which recovers heat from the combustion exhaust gas G through the combustion exhaust gas G, and heats the heat transfer water H to generate steam, the pressure reducing boiler 4 whose internal pressure is kept below atmospheric pressure, and the evaporation section 26 Binary power generation installed in the depressurized steam chamber 22 of the boiler 4 and heating and evaporating the low boiling point liquid refrigerant R flowing in the evaporation unit 26 with the vapor in the depressurized steam chamber 22 and rotating the turbine 28 with the vapor to generate electricity The temperature medium 23 or the pressure sensor 24 for detecting the temperature of the heat medium water H of the pressure reduction boiler 4 or the pressure of the pressure reduction steam chamber 22, and the pressure reduction steam chamber 22 of the pressure reduction boiler 4 Heat receiving W flows 34, a cooling medium supply pipe 35 for supplying the cooling medium W to the heat receiving unit 34, and a control valve 37 interposed in the cooling medium supply pipe 35 and controlled by a detection signal from the pressure detector 24 Binary power generation so that the temperature of the heat transfer water H of the decompression boiler 4 or the pressure of the decompression steam chamber 22 is maintained at a predetermined temperature or pressure based on the detection signal from the temperature detector 23 or the pressure detector 24 The amount of power generation is controlled by controlling the refrigerant circulation pump 31 for circulating the low boiling point refrigerant R of the device 8, and the pressure in the pressure reducing boiler 4 exceeds the set value (the intermediate value between the maximum working pressure and the normal working pressure) Occasionally, the control valve 37 is opened based on the detection signal from the pressure detector 24 to supply the cooling medium W to the heat receiving unit 34 so as to reduce the pressure in the pressure reducing boiler 4.

  Specifically, as shown in FIG. 2, the pressure reducing boiler 4 is connected to the flue 7, and the can 20 which holds the heat transfer water H while the internal pressure is maintained below the atmospheric pressure, and the can 20. A plurality of smoke pipes 21 which are installed in a penetrating manner in a portion where the heat transfer water H is stored and through which the combustion exhaust gas G in the flue 7 passes and a reduced pressure steam chamber 22 formed in an upper side space in the can 20; Temperature detector 23 for detecting the temperature of the heat transfer water H, pressure detector 24 for detecting the pressure in the depressurized steam chamber 22, and the maximum working pressure (a pressure slightly smaller than the atmospheric pressure) of the internal pressure of the depressurized steam chamber 22 The combustion exhaust gas G which passes the heat medium water H in the can 20 through the inside of the plurality of smoke pipes 21 is provided with a safety device 25 (for example, a safety valve) or the like that opens the depressurized steam chamber 22 to the atmosphere when the temperature rises. Heat and evaporate by indirect heat exchange with the source, and place the generated steam in the reduced pressure steam chamber 22 They were together condensed to liquefy in contact with the evaporator section 26 of the binary power generation device 8, and to vaporize the refrigerant R flowing in the evaporator section 26.

  The can 20 has a structure in which the upper can 20a and the lower can 20b are connected in a communicating manner via the connecting pipe 20c, and the heat transfer water H is stored in the lower can 20b. A smoke pipe 21 is installed over the lower can 20 b, and a space in the upper can 20 a, an upper space in the lower can 20 b, and a space of the communication pipe 20 c form a reduced pressure steam chamber 22.

Further, as the heat transfer water H, an aqueous solution having a boiling point of 100 ° C. or higher at atmospheric pressure or lower is used. The boiling point of the aqueous solution is a temperature at which condensation does not occur in the smoke pipe 21 through which SO ₃ contained in the combustion exhaust gas G passes. In this embodiment, since the dew point of SO ₃ is about 130 ° C., the boiling point of the aqueous solution is 130 ° C., and a 55 wt% lithium bromide aqueous solution is used as the heat transfer water H.

  As shown in FIG. 2, the binary power generation apparatus 8 includes an evaporation unit 26, a superheat pipe 27, a turbine 28, a generator 29, a condenser 30, a refrigerant circulation pump 31, a refrigerant circulation pipe 32, a control board 33, and the like. The evaporation unit 26, the superheat pipe 27, the turbine 28, the condenser 30, and the refrigerant circulation pump 31 are connected in a closed loop by the refrigerant circulation pipe 32, and the low boiling point refrigerant R (for example, pentane, ammonia ) Are circulated in the order of the evaporating unit 26, the superheating pipe 27, the turbine 28, the condensing unit 30, and the refrigerant circulating pump 31, and are returned to the evaporating unit 26.

  The evaporation unit 26 of the binary power generation device 8 is installed in the depressurized steam chamber 22 of the depressurizing boiler 4, and the vapor in the depressurized vapor chamber 22 evaporates the low boiling point liquid refrigerant R in the evaporator 26. The vaporized refrigerant R is led to the superheating pipe 27 where it is further heated by heat medium water H at 130 ° C., and the turbine 28 is rotated by the superheated refrigerant R so that the generator 29 generates electric power. The steam that has rotated the turbine 28 is cooled in the condenser 30 and becomes liquid refrigerant R and returns to the evaporator 26. Here, the liquid refrigerant R returned to the evaporation section 26 is again heated and vaporized by the vapor in the depressurized steam chamber 22, flows into the superheating pipe 27 and is further superheated by the heat transfer water H here, and then the turbine It is supplied to 28 to turn the turbine 28.

  As described above, in the binary power generation system 8, the refrigerant R serving to turn the turbine 28 circulates in the closed loop while repeating steam and liquefaction. The evaporation unit 26 installed in the decompression steam chamber 22 of the decompression boiler 4 is configured by arranging the bent evaporation tube 26 a in the decompression steam chamber 22.

  Further, the binary power generation device 8 detects the temperature of the heat transfer water H of the decompression boiler 4 or the pressure of the decompression steam chamber 22 respectively by the temperature detector 23 or the pressure detector 24 provided in the decompression boiler 4 and detects them. The refrigerant circulation pump 31 which circulates the low boiling point refrigerant R by the control panel 33 so that the temperature of the heat transfer water H of the decompression boiler 4 or the pressure of the decompression steam chamber 22 is maintained at a predetermined temperature or pressure based on the signal. It is configured to control and control the amount of power generation.

  The heat receiving portion 34 is formed by arranging the bent heat receiving pipe 34 a in the depressurized steam chamber 22 of the pressure reducing boiler 4, and the heat receiving pipe 34 a on the inlet side of the heat receiving portion 34 is connected to the heat receiving portion 34. A cooling medium supply pipe 35 for supplying the cooling medium W is connected, and a cooling medium discharge pipe 36 for discharging the heat receiving cooling medium W is connected to the heat receiving pipe 34 a on the outlet side of the heat receiving portion 34. As the cooling medium W, water at normal temperature is used. Here, water at normal temperature means water which is neither heated nor cooled. Also, this water has been freed from components that cause scale and corrosion problems.

  A control valve 37 is interposed in the cooling medium supply pipe 35 for supplying the cooling medium W. The control valve 37 is controlled by the control panel 33 based on the detection signal from the pressure detector 24 when the pressure in the pressure reducing boiler 4 exceeds the set value (the intermediate value between the maximum working pressure and the normal working pressure). It is supposed to be Thereby, the cooling medium W is supplied from the cooling medium supply pipe 35 to the heat receiving unit 34, where heat is received from the steam in the depressurized steam chamber 22 and the pressure in the depressurizing boiler 4 is lowered to a pressure at which the safety device 25 does not operate. Let In addition, the cooling medium W (water heated to become warm water) which passed through the heat receiving part 34 and was heated is used secondarily in other processes (for example, a warm water pool etc.).

  Next, the case where the sewage sludge is burnt-processed using the combustion equipment which installed the heat recovery electric power generation equipment from combustion exhaust gas W mentioned above is explained.

  Sewage sludge supplied into the combustion furnace 1 is dried, burned and post-burned on the stoker 11 and discharged out of the furnace. The moisture content of the sewage sludge was 70%.

  The combustion exhaust gas G generated by the combustion is discharged from the combustion furnace 1 and heat-recovered by the combustion air preheater 2 and the white smoke preventing air preheater 3 to a temperature of about 650.degree. The combustion air preheated by the combustion air preheater 2 is supplied below the stoker 11 by the combustion air supply duct 13 and used for combustion, and the white smoke prevention air preheated by the white smoke prevention air preheater 3 Is supplied to the flue 7 downstream of the induction ventilator 9 by the white smoke preventing air supply duct 15.

  The flue gas G which has passed through the white smoke prevention air preheater 3 flows through the flue 7 into the decompression boiler 4 and is absorbed by heat while passing through the smoke pipe 23 and sent to the dust collector 5 at about 180 ° C. Here, the soot contained in the combustion exhaust gas G is removed.

  The flue gas G from which the soot and dust have been removed is sent through the flue 7 to the scrubbing apparatus 6, where after the acid gas contained in the flue gas G is removed by water spraying, it passes through the induction ventilator 9. It is mixed with the white smoke prevention air and emitted from the chimney 10 to the atmosphere.

Then, in the decompression boiler 4 of the heat recovery power generation facility, the inside of the can 20 is maintained at the atmospheric pressure or lower, and the heat transfer water H is filled. The heat transfer water H has a boiling point of 100 ° C. or higher below atmospheric pressure, and is a temperature at which condensation does not occur inside the smoke pipe 23 of the decompression boiler 4 through which SO ₃ contained in the combustion exhaust gas G passes. In this embodiment, since the dew point of SO ₃ is 130 ° C., the boiling point of the heat medium water H is 130 ° C. The surface temperature of the smoke pipe 21 of the decompression boiler 4 at this time is about 140 ° C., and corrosion is prevented.

  The heat transfer water H received from the combustion exhaust gas G through the smoke pipe 21 of the decompression boiler 4 is boiled to generate steam at 90 ° C. The generated steam contacts the evaporation pipe 26a of the evaporation unit 26 of the binary power generation device 8 installed in the decompression steam chamber 22 of the decompression boiler 4, condenses, and gives heat to the refrigerant R flowing in the evaporation tube 28a. The drain water condensed by the heat exchange in the evaporation unit 26 flows down to the side of the heat transfer water H stored in the lower can 20 a.

  The refrigerant R flowing in the evaporation pipe 26 a of the evaporation unit 26 is vaporized from liquid to gas by receiving heat. The vaporized refrigerant R is led to the superheating pipe 27, where it receives heat from the 130 ° C. heat medium water H of the decompression boiler 4 and is superheated to 120 ° C., and is sent to the turbine 28 of the binary power generation device 8 To cause the generator 29 to generate power.

The vaporized refrigerant R discharged from the turbine 28 is sent to the condenser 30 where it is cooled by the cooling water to become a liquid refrigerant R, and returns to the evaporator 26 by the refrigerant circulation pump 31.
Hereinafter, the above cycle is repeated.

  Next, control of the pressure reducing boiler 4 of the heat recovery power generation facility will be described.

When the amount of combustion and the amount of heat generation of the sewage sludge decrease, the inlet temperature of the pressure reducing boiler 4 and the flow rate of the combustion exhaust gas G decrease, so the amount of heat absorbed by the pressure reducing boiler 4 also decreases. At this time, the internal pressure of the pressure reducing boiler 4 (the pressure of the pressure reducing steam chamber 22) also decreases. When the internal pressure of the pressure reducing boiler 4 decreases, the saturation temperature of the heat transfer water H also decreases, so the temperature inside the smoke pipe 21 of the pressure reducing boiler 4 decreases. Therefore, the temperature inside the smoke pipe 21 becomes lower than the dew point of SO ₃ . As a result, the smoke pipe 21 of the decompression boiler 4 may cause sulfuric acid corrosion due to condensation of SO ₃ .

  In order to prevent this phenomenon (sulfuric acid corrosion of the smoke pipe 21), the temperature of the heat medium water H of the decompression boiler 4 or the pressure of the decompression steam chamber 22 is detected by the temperature detector 23 or the pressure detector 24. When the temperature of the heat transfer water H or the pressure of the depressurized steam chamber 22 becomes lower than the set value, a detection signal from the temperature detector 23 or the pressure detector 24 is sent to the control panel 33 of the binary power generator 8 to reduce the power generation amount. . In order to reduce the power generation amount, the control board 33 reduces the rotational speed of the refrigerant circulation pump 31 to reduce the circulation amount of the refrigerant R. When the circulation amount of the refrigerant R decreases, the inlet refrigerant condition of the turbine 28 is maintained even if the amount of heat absorbed by the evaporation unit 26 decreases.

  On the other hand, when the amount of combustion and the amount of heat generation of the sewage sludge rise, the inlet temperature of the pressure reducing boiler 4 and the flow rate of the combustion exhaust gas G rise, so the amount of heat absorbed by the pressure reducing boiler 4 also rises. At that time, the internal pressure of the pressure reducing boiler 4 (the pressure of the pressure reducing steam chamber 22) also increases.

  When the internal pressure of the pressure reducing boiler 4 rises and becomes equal to or higher than the set pressure, the safety device 25 (safety valve) operates in the direction of opening to release the pressure in the pressure reducing boiler 4 and the atmospheric pressure and the internal pressure of the pressure reducing boiler 4 are the same. Become.

  However, in this case, a vacuum pump (not shown) is required to reduce the pressure in the pressure reducing boiler 4 to the atmospheric pressure or less when the pressure reducing boiler 4 is restarted.

  It is expensive and time consuming to spend such work and time, so I want to avoid it as much as possible. In order to prevent this phenomenon, the temperature of the heat medium water H of the pressure reducing boiler 4 or the pressure of the pressure reducing steam chamber 22 is detected by the temperature detector 23 or the pressure detector 24, and the temperature of the heat medium water H of the pressure reducing boiler 4 Alternatively, when the pressure in the depressurized steam chamber 22 exceeds the set value, a detection signal from the temperature detector 23 or the pressure detector 24 is sent to the control panel 33 of the binary power generation device 8 to increase the amount of power generation. In order to increase the power generation amount, the control board 33 increases the rotational speed of the refrigerant circulation pump 31 to increase the circulation amount of the refrigerant R. When the amount of circulation of the refrigerant R increases, the inlet refrigerant condition of the turbine 28 is maintained even if the amount of heat absorbed by the evaporator 26 increases.

  As described above, when the amount of combustion and the amount of heat generation of the sewage sludge change, the control by the circulation amount of the refrigerant R of the binary power generation device 8 is the same as the heat reception rate on the binary power generation device 8 side with the heat reception rate on the pressure reduction boiler 4 side When the heat receiving speed on the side of the pressure reducing boiler 4 is large and the holding amount of the heat transfer water H in the pressure reducing boiler 4 is small, the pressure of the pressure reducing boiler 4 is increased. . Moreover, when the amount of combustion exhaust gas G and the fluctuation | variation of temperature are large, the pressure in the pressure reduction boiler 4 may exceed the maximum working pressure (pressure slightly smaller than atmospheric pressure). As a result, the safety device 25 is activated.

  Therefore, when the fluctuation of the amount and temperature of the combustion exhaust gas G is large, that is, when the amount of the combustion exhaust gas G increases and the temperature of the combustion exhaust gas G rises, the heat receiving portion 34 and the control valve 37 are controlled. The safety control of the pressure reducing boiler 4 is performed.

  When the amount and temperature of the flue gas G fluctuate and the pressure in the pressure reducing boiler 4 exceeds the set value (intermediate value between the maximum working pressure and the normal working pressure), the detection signal from the pressure detector 24 is sent to the control panel 33 The control valve 37 is controlled by the control panel 33 to be opened.

  Thereby, the cooling medium W is supplied to the heat receiving pipe 34a of the heat receiving unit 34 through the cooling medium supply pipe 35, where the heat is received from the steam in the reduced pressure steam chamber 22 to lower the temperature in the reduced pressure steam chamber 22. The pressure in 4 is reduced to a pressure at which the safety device 25 does not operate. At this time, the heat receiving pipe 34a of the heat receiving portion 34 is accompanied by condensation heat transfer having a heat transfer coefficient higher than that of heat transfer due to natural convection or forced convection, and the cooling medium W which is a heat receiving body flowing through the heat receiving pipe 34a. Since water at normal temperature is used, the temperature difference with the pressure reducing steam chamber 22 can be large, and the combustion exhaust gas G, the pressure reducing boiler 4 (first heat receiving portion), the pressure reducing boiler 4 and the refrigerant R (second heat receiving portion) The heat can be received earlier.

  The heat is received by the heat receiving unit 34 installed in the depressurized steam chamber 22. When the pressure in the depressurizing boiler 4 becomes equal to or less than the set pressure, the control valve 37 is gradually closed by the control panel 33. At this time, since the control valve 37 is gradually closed, the control of the amount of circulation of the refrigerant R by the refrigerant circulation pump 31 on the side of the binary power generation device 8 catches up, and the pressure inside the decompression boiler 4 is operated at the normal pressure. Become. Finally, the control valve 37 is completely closed, and the supply of the cooling medium W to the heat receiving portion 34 is stopped.

  As described above, according to the above-described heat recovery power generation facility, when the pressure in the pressure reducing boiler 4 exceeds the set value (the intermediate value between the maximum working pressure and the normal working pressure), a detection signal from the pressure detector 24 is used. Based on this, the control valve 37 is opened to supply the cooling medium W to the heat receiving unit 34 and the pressure in the pressure reducing boiler 4 is reduced, so the amount of the flue gas G flowing into the pressure reducing boiler 4 increases significantly. Also, even when the temperature of the combustion exhaust gas G rises rapidly, the decompression boiler 4 can be continuously operated in a stable state without exceeding the maximum working pressure.

  Further, even when a problem (for example, a failure of the refrigerant circulation pump 31) occurs on the side of the binary power generation apparatus 8 and the refrigerant R can not be circulated, the cooling medium W is supplied to the heat receiving unit 34 to receive the heat receiving unit 34. By making the heat receiving capacity of the heat generating capacity equal to or higher than the heat receiving capacity on the side of the binary power generation device 8, it is possible to carry out the burning treatment of waste without stopping the operation of the facility itself.

  1 is an incinerator, 2 is an air preheater for combustion, 3 is a white smoke prevention air preheater, 4 is a pressure reduction boiler, 5 is a dust collector, 6 is a smoke scrubber, 7 is a flue, 8 is a binary power generator, 9 is an induction ventilator, 10 is a chimney, 11 is a stoker, 12 is a combustion air fan, 13 is a combustion air supply duct, 14 is a white smoke prevention fan, 15 is a white smoke prevention air supply duct, 16 is a nozzle, 17 is a flushing water circulation pump, 18 is a flushing water discharge pump, 19 is a flushing water supply pump, 20 is a can, 20a is an upper can, 20b is a lower can, 20c is a connecting pipe, 21 is a smoke pipe, 22 Is a decompression steam chamber, 23 is a temperature detector, 24 is a pressure detector, 25 is a safety device, 26 is an evaporator, 26a is an evaporator, 27 is a superheater, 28 is a turbine, 29 is a generator, 30 is a condenser 31 is a refrigerant circulation pump, 32 is a refrigerant circulation pipe, 33 is a control panel, 3 The heat receiving portion, 34a is the heat receiving pipe, 35 is a cooling medium supply pipe, 36 cooling medium discharge pipe, 37 is a control valve, G is flue gas, H is the heat medium water, R represents a refrigerant, W is the cooling medium.

Claims (5)

  A heat recovery power generation facility for exhaust gas from combustion exhaust gas that is generated by recovering heat from exhaust gas that is discharged from a combustion furnace that burns waste and contains corrosive components flowing in the flue, and is a flue that flows the exhaust gas Installed in the heat recovery water from the combustion exhaust gas through the combustion exhaust gas, and the internal pressure for heating the heat transfer water to generate steam is maintained below atmospheric pressure, and the evaporation section is in the pressure reduction steam chamber of the pressure reduction boiler A binary power generator installed that heats and evaporates the low boiling point liquid refrigerant flowing in the evaporation section with steam in the reduced pressure steam chamber and turns the turbine with the steam to generate power, temperature of heat transfer water of the reduced pressure boiler or reduced pressure steam A temperature sensor or pressure sensor for detecting the pressure in the chamber, a heat receiving unit installed in the reduced pressure steam chamber of the pressure reducing boiler, and a cooling medium flowing through the cooling medium And a control valve connected to the cooling medium supply pipe and controlled by a detection signal from the pressure detector, the pressure reducing boiler based on the detection signal from the temperature detector or the pressure detector. Controlling the amount of power generation by controlling a refrigerant circulation pump that circulates the low boiling point refrigerant of the binary power generation device so that the temperature of the heat transfer water or the pressure of the depressurized steam chamber is maintained at a predetermined temperature or pressure; When the pressure in the pressure reducing boiler exceeds the set value, the control valve is opened based on the detection signal from the pressure detector to supply the cooling medium to the heat receiving portion, thereby reducing the pressure in the pressure reducing boiler Heat recovery power generation facility from flue gas characterized by The heat medium water of the pressure reduction boiler is an aqueous solution whose boiling point is equal to or higher than the dew point of SO ₃ gas contained in the combustion exhaust gas at atmospheric pressure or lower, and the cooling medium is water at normal temperature. The heat recovery power generation equipment from the flue gas according to Item 1.   A superheat pipe is disposed in the heat medium water of the decompression boiler, and the superheat pipe and the evaporation section of the decompression steam chamber are connected to lead the refrigerant heated in the evaporation section to the superheat pipe, where the heating medium of the decompression boiler The heat recovery power generation facility from flue gas according to claim 1 or 2, wherein the water is further heated by water.   The method for controlling heat recovery power generation equipment from flue gas according to any one of claims 1 to 3, wherein the pressure in the pressure reduction boiler is detected by a pressure detector, and the pressure in the pressure reduction boiler is detected. When the pressure exceeds the set value, the control valve is opened to supply the cooling medium to the heat receiving section, and the pressure in the pressure reducing boiler is reduced. Control of heat recovery power generation equipment from flue gas Method.   The control method of heat recovery power generation equipment from flue gas according to claim 4, wherein the control valve is gradually closed when the pressure in the pressure reducing boiler becomes lower than the set pressure.

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