JP2014105612A - Waste heat recovery facility, waste heat recovery method and waste treatment furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste heat recovery facility capable of effectively utilizing potential heat of exhaust gas, without decreasing a power generation amount.SOLUTION: A waste heat recovery facility 30 incorporated into a waste treatment furnace 1 including a waste heat boiler 8 includes: a heat exchanger 11 that is installed in a gas duct, in which pressurized supply water of a deaerator 25 supplied to the waste heat boiler 8 is supplied as a heated medium, and in which the heated medium heated by heat exchange with exhaust gas is circulated and supplied to the deaerator 25 as a deaeration heat source; and control mechanisms 32, 33 that adjust a water supply amount to the heat exchanger 11 so that exhaust gas discharged from the heat exchanger 11 is not less than a first predetermined temperature.

Description

  The present invention relates to a waste heat recovery facility, a waste heat recovery method, and a waste treatment furnace, and more particularly relates to a waste heat recovery facility, a waste heat recovery method, and a waste treatment furnace incorporated in a waste treatment furnace equipped with a waste heat boiler. .

  Waste treatment facilities such as large-scale waste incinerators and melting furnaces are provided with waste heat boilers, and power generation facilities that generate electricity using steam generated in the waste heat boilers are incorporated. Electric power necessary to operate the facilities is covered by self-generated power, and if there is surplus power, it is sold to an electric power company.

  The high-temperature exhaust gas generated in the waste treatment facility was cooled by a temperature-reduction tower provided in the flue, then removed by a dust collector such as a bag filter, and acid gas components were removed by a smoke-wash tower as necessary. Later exhausted from the chimney.

  The steam generated in the waste heat boiler is superheated by the superheater and then accumulated in the high-pressure steam reservoir. The required amount is supplied from the high-pressure steam reservoir to the steam turbine for power generation, and the exhaust steam from the steam turbine is recovered by the condenser. Water is collected in the condensate tank, then supplied to the deaerator from the condensate tank, degassed, and circulated and supplied to the economizer as boiler feed water heated to a predetermined temperature.

  And, in order to use steam as a heat source of various facilities such as heating facilities, a part of the steam accumulated in the high-pressure steam reservoir is accumulated in the low-pressure steam reservoir, a part of the steam accumulated in the low-pressure steam reservoir, Or the extraction from the middle of a steam turbine is supplied as a heating source of a deaerator.

  In Patent Document 1, extraction from a steam turbine is guided to an exhaust condensate tank through an extraction transfer pipe, a first type absorption heat pump is provided in the middle of the condensate transfer pipe, and the first type absorption heat pump is driven. The steam turbine bleed air is used as a heat source, the exhaust steam taken from the middle of the exhaust steam extraction pipe is used as the waste heat heat source to be recovered, and the condensate from the exhaust condensate tank is used. A power generation facility has been proposed that raises the temperature by introducing it to an absorber and a condenser.

  According to the power generation facility, the temperature of the condensate sent from the condensate tank to the deaerator increases, and the amount of bleed required to raise the temperature of the condensate by the bleed of the steam turbine is reduced in the deaerator. To do. That is, since the amount of steam flowing in the steam turbine after the extraction location can be increased, the amount of power generation can be increased.

Japanese Patent Application Laid-Open No. 08-021210

  However, the above-described conventional waste treatment facility has a problem in that it is necessary to use steam turbine bleed air or the like as a heat source for the deaerator, and the amount of steam provided for power generation is reduced. Furthermore, the high-temperature exhaust gas generated in the combustion furnace is cooled by a temperature reducing tower provided in the flue, and the temperature-reduced exhaust gas is removed by a dust collector installed on the downstream side. There was room for further improvement in terms of effective use.

  An object of the present invention is to provide a waste heat recovery facility, a waste heat recovery method, and a waste treatment furnace capable of effectively utilizing the retained heat of exhaust gas without causing a decrease in the amount of power generation in view of the above-described problems. is there.

  In order to achieve the above-mentioned object, the first characteristic configuration of the waste heat recovery facility according to the present invention is the waste heat incorporated in the waste treatment furnace equipped with the waste heat boiler as described in claim 1 of the claims. A recovery facility that is installed in a flue and is supplied with pressurized feed water of a deaerator supplied to the waste heat boiler as a heated medium, and the heated medium heated by heat exchange with the exhaust gas is deaerated. A heat exchanger that is circulated and supplied to the deaerator as a heat source, and a control mechanism that adjusts the amount of water supplied to the heat exchanger so that the exhaust gas discharged from the heat exchanger does not fall below a first predetermined temperature. It is in the point equipped with.

  The retained heat of the exhaust gas flowing down to the flue through the waste heat boiler can be efficiently recovered with a heat exchanger, and the recovered heat is used as a heat source for deaeration of boiler water. It becomes unnecessary and power generation efficiency can be improved. In addition, the exhaust gas that has been sufficiently reduced in temperature by the heat exchanger can be allowed to flow down toward the dust collector without providing a temperature reducing tower.

  Moreover, since the property of the waste processed in the waste processing furnace varies variously, the amount of exhaust gas flowing into the heat exchanger also varies. Even if the combustion state of the waste is greatly reduced and the amount of exhaust gas is reduced, the amount of water supplied to the heat exchanger is adjusted by the control mechanism so that the exhaust gas discharged from the heat exchanger does not fall below a predetermined temperature. Further, it is possible to prevent the occurrence of low-temperature corrosion in the heat exchanger and the flue on the downstream side of the heat exchanger and in each treatment facility disposed in the flue.

  In addition, waste treatment furnaces equipped with an economizer with a large heat transfer area to eliminate the temperature-decreasing tower in front of the dust collector and adopting the so-called low-temperature eco that efficiently recovers waste heat has a large combustion state of waste. If the amount of exhaust gas decreases and the amount of exhaust gas decreases, the economizer absorbs heat more than necessary and the outlet temperature decreases, which may cause low-temperature corrosion. However, according to the above-described configuration, even if a normal economizer that is not so-called low-temperature ecology is used, not only a temperature-decreasing tower is unnecessary, but also the amount of water supplied to the heat exchanger is adjusted by the control mechanism. Can be prevented in advance.

  In the second feature configuration, as described in claim 2, in addition to the first feature configuration described above, the control mechanism is configured so that the heated medium discharged from the heat exchanger has a predetermined pressure or more. In addition, it is configured to adjust the discharge amount of the heated medium.

  Pressurized feed water, which is boiler feed water, is used as the heated medium for recovering waste heat, and the discharge rate of the heated medium is adjusted by the control mechanism so that the heated medium becomes equal to or higher than the predetermined pressure. Can be efficiently degassed.

  In the third feature configuration, as described in claim 3, in addition to the first or second feature configuration described above, the heat exchanger is installed in a downstream flue of an economizer and supplied to the economizer. The pressurized water supply of the deaerator is branched and supplied as the medium to be heated.

  An economizer and a heat exchanger are arranged in this order along the flue, and pressurized water degassed by the deaerator is supplied to the economizer and the heat exchanger, respectively. Pressurized feed water heated by the economizer is supplied to the waste heat boiler, pressurized feed water heated by the heat exchanger is circulated and supplied to the deaerator, and the exhaust gas reduced in temperature after passing through the heat exchanger Supplied to the exhaust gas treatment facility. Normally, exhaust gas that has passed through the economizer is sent to a dust collector such as a bag filter through a temperature reducing tower. However, according to the above configuration, the temperature is sufficiently reduced by a heat exchanger, so it is necessary to provide a temperature reducing tower. In addition, waste heat can be recovered efficiently.

  In the fourth feature configuration, as described in claim 4, in addition to any of the first to third feature configurations described above, a plurality of wastes in which the heat exchanger is installed in each flue A processing furnace is also provided, and the deaerator is shared. The control mechanism is provided for a waste processing furnace that resumes operation when another waste processing furnace is in operation. In other words, the pressurized water is supplied from the deaerator to the controlled heat exchanger and the exhaust gas is heated.

  When the waste treatment furnace that has been stopped by regular inspection or the like is started up again, the furnace is shifted to a predetermined combustion state using fossil fuel. In the meantime, the relatively low temperature and high humidity exhaust gas flows into the flue, so that the deliquescent material captured by the dust collector contains moisture, and for example, the filter of the dust collector may become clogged or low temperature corrosion may occur. There is. Therefore, it has been necessary to heat the exhaust gas with a heat source such as an electric heater and a blower fan that guides the air heated by the heat source to the upstream flue of the dust collector, but it is controlled by pressurized water supplied from the deaerator. If the exhaust gas flowing through the target heat exchanger can be heated, the power required for the electric heater can be reduced. When other waste treatment furnaces are in operation, the pressurized water supplied from the deaerator is heated to a certain high temperature, for example, about 143 ° C., so that the pressurized water is radiated by the heat exchanger. Returning to the deaerator will not cause any inconvenience.

  In the fifth feature configuration, as described in claim 5, in addition to the fourth feature configuration described above, the control mechanism is configured so that the exhaust gas discharged from the heat exchanger exceeds a second predetermined temperature. In addition, the amount of water supplied to the heat exchanger to be controlled is adjusted.

  At this time, the amount of water supplied to the control target heat exchanger is adjusted by the control mechanism so that the exhaust gas discharged from the control target heat exchanger exceeds the second predetermined temperature. As a result, the deliquescence captured by the dust collector It can be surely avoided that the substance absorbs moisture and causes an unfavorable situation.

  The characteristic configuration of the waste heat recovery method according to the present invention is a waste heat recovery method for a waste treatment furnace equipped with a waste heat boiler as described in claim 6, wherein the waste heat recovery method is installed in a flue and the waste heat boiler For the heat exchanger in which the pressurized feed water of the deaerator supplied to is supplied as a heated medium, and the heated medium heated by heat exchange with the exhaust gas is circulated and supplied to the deaerator as a deaeration heat source Thus, the amount of water supplied to the heat exchanger is adjusted so that the exhaust gas discharged from the heat exchanger does not fall below the first predetermined temperature.

The characteristic configuration of the waste treatment furnace according to the present invention is a waste treatment furnace equipped with a waste heat boiler as described in claim 7, which is installed in a flue and supplied to the waste heat boiler. A heat exchanger in which pressurized feed water of an air supply is supplied as a heated medium, and the heated medium heated by heat exchange with exhaust gas is circulated and supplied to the degasser as a degassing heat source;
A waste heat recovery facility including a control mechanism that adjusts the amount of water supplied to the heat exchanger so that the exhaust gas discharged from the heat exchanger does not fall below a first predetermined temperature.

  As described above, according to the present invention, it is possible to provide a waste heat recovery facility, a waste heat recovery method, and a waste treatment furnace that can effectively utilize the retained heat of exhaust gas without causing a decrease in the amount of power generation. Became.

Explanatory diagram of a waste treatment furnace incorporating waste heat recovery equipment according to the present invention Flow chart of control procedure executed by control device of heat exchanger Explanatory drawing of an operation mode of a waste treatment facility provided with a waste heat recovery facility according to the present invention Explanatory drawing of the model for calculating the mechanical size of the heat exchanger according to the present invention Flowchart at the time of resuming operation of a waste treatment facility equipped with a waste heat recovery facility according to the present invention

Hereinafter, a waste heat recovery facility, a waste heat recovery method, and a waste treatment furnace according to the present invention will be described.
FIG. 1 shows a waste treatment facility provided with two stoker-type garbage incinerators 1 and 1 ′ having the same structure as an example of a waste treatment furnace.

  An object to be treated such as municipal waste thrown into the hopper 2 is charged into the furnace by the pusher mechanism 3 below the hopper 2 and is primarily burned while being stirred and pressed by the stalker mechanism 4, and the combustion gas is in the space above it. Is completely burned at a temperature of about 950 ° C. in the secondary combustion section 5.

  The primary combustion air is supplied from the primary combustion air supply mechanism 6 provided below the stalker mechanism 4 so that the waste is primarily burned on the stoker, and the vaporized combustible gas and the air that has not contributed to the primary combustion are secondary combustion. Secondary combustion is performed in part 5. Installed on the side wall of the secondary combustion section 5 is a gas supply mechanism 7 composed of a gas injection nozzle group for supplying a stirring gas for stirring the unburned gas and air completely in the secondary combustion section. Has been.

  A waste heat boiler 8 and a superheater 9 are installed above the secondary combustion unit 5. The exhaust gas that has passed through the waste heat boiler 8 and the superheater 9 is exhausted from the chimney 15 through an economizer 10, a heat exchanger 11, a bag filter 12 that is an example of a dust collector, and the like arranged in order from the upstream side along the flue. The

  The boiler feed water heated by the economizer 10 is supplied to the waste heat boiler 8 to generate steam, and the steam generated by the waste heat boiler 8 is superheated by the superheater 9 and accumulated in the high-pressure steam reservoir 27, The high-temperature and high-pressure steam accumulated in the reservoir 27 is supplied to the steam turbine 21 of the power generation facility 20, and the medium-pressure steam extracted from the steam turbine 21 is supplied to the deaerator 25 as a heat source for deaeration.

  The power generation facility 20 includes a steam turbine 21 and a generator 22 that is rotationally driven by the steam turbine 21. The steam discharged from the steam turbine 21 is condensed in the condenser 23 and stored in the condensate tank 24, and further led to the deaerator 25 where the dissolved oxygen contained in the condensate is degassed.

  The high-pressure steam reservoir 27, the power generation facility 20, the condenser 23, the condensate tank 24, and the deaerator 25 are shared by the two garbage incinerators 1 and 1 ′, and continuously when one of them stops. It is configured to generate electricity. In this embodiment, two waste treatment furnaces are provided side by side, and an example in which the power generation equipment 20 using steam generated in each waste heat boiler 8 is shared is shown. A material processing furnace may be provided, and the power generation equipment 20 using steam generated by the waste heat boiler 8 provided for them may be shared. Moreover, the power generation equipment 20 may be individually installed in each waste treatment furnace, and each equipment of the condenser 23, the condensate tank 24, and the deaerator 25 may be shared.

  The pressurized water supplied from the deaerator 25 to the economizer 10 by the water supply pump 31 is branched and supplied to the heat exchanger 11 as a heating medium. The pressurized water supply may be directly supplied from the deaerator 25 to the heat exchanger 11 by a water supply pump different from the water supply pump 31.

  The pressurized feed water heated by heat exchange with the exhaust gas in the heat exchanger 11 is circulated and supplied to the deaerator 25 as a heat source for deaeration. The exhaust gas that has been reduced in temperature after passing through the heat exchanger 11 is supplied to an exhaust gas treatment facility such as a bag filter 12 in the subsequent stage.

  The waste heat recovery facility 30 according to the present invention includes the above-described heat exchanger 11 and control mechanisms 32 and 33 that control the amount of pressurized water supplied to the heat exchanger 11 and the like.

  That is, the heat exchanger 11 is installed in the flue, and the pressurized feed water of the deaerator 25 supplied to the waste heat boiler 8 is supplied to the heat exchanger 11 as a heating medium and heated by heat exchange with the exhaust gas. The heated medium is circulated and supplied from the heat exchanger 11 to the deaerator 25 as a deaeration heat source.

  Then, the control mechanisms 32 and 33 adjust the amount of water supplied to the heat exchanger 11 so that the exhaust gas discharged from the heat exchanger 11 does not fall below the first predetermined temperature. The first predetermined temperature is a temperature higher than about 130 ° C. at which the equipment installed in the flue is cold-corroded and lower than a temperature causing damage to the filter cloth of the bag filter 12, for example, 140 It is set in the range of ° C to 160 ° C.

  Furthermore, the control mechanisms 32 and 33 adjust the discharge amount of the heated medium from the heat exchanger 11 so that the heated medium discharged from the heat exchanger 11 has a predetermined pressure or higher.

  Note that the predetermined pressure is equal to or higher than a pressure at which the heat transfer rate is improved so that the deaeration can be efficiently performed and the medium to be heated in the heat exchanger 11 can be prevented from being vaporized. It is the pressure below the pressure which can prevent that the to-be-heated medium in the exchanger 11 blows, for example, is the pressure set to the range of 3 MPa-4 MPa.

  By providing such a waste heat recovery facility 30, the retained heat of the exhaust gas flowing down to the flue through the waste heat boiler 8 can be efficiently recovered by the heat exchanger 11, and the recovered heat is degassed from the boiler water. As a result, the amount of steam extracted from the steam turbine 21 for deaeration can be reduced or eliminated, and the power generation efficiency can be improved. In addition, the exhaust gas that has been sufficiently reduced in temperature by the heat exchanger 11 can be allowed to flow down to the bag filter 12 without being provided with a temperature reducing tower.

Hereinafter, the control mechanisms 32 and 33 will be described in detail.
A water supply valve mechanism 32a (32) is provided in a path for supplying a heated medium from the deaerator 25 to the heat exchanger 11, and a drain valve is provided in a path for circulating the heated medium from the heat exchanger 11 to the deaerator 25. A mechanism 32b (32) is provided. The valve mechanism 32 (32a, 32b) is composed of, for example, an electric diaphragm valve. The opening degree of each valve mechanism 32 (32a, 32b) is adjusted by an electric actuator driven by a signal from the control device 33 (33a, 33b).

  The control device 33 (33a, 33b) is incorporated in a control panel provided in a central management room away from the installation location of each valve mechanism 32 (32a, 32b), and measures the temperature of exhaust gas discharged from the heat exchanger 11. A signal input unit to which a measured value of a pressure sensor that measures the pressure of the pressurized water drained from the temperature sensor or the heat exchanger 11 is input, a signal output unit that outputs a control signal to each of the valve mechanisms 32a and 32b, and a signal input unit A control calculation unit for performing feedback calculation such as PID calculation for generating a control signal output from the signal output unit based on an input signal from the signal output unit.

  The control device 33 (33a, 33b) automatically controls the opening degree of each valve mechanism 32a, 32b so that these measured values become a predetermined target value. The control device 33 (33a, 33b) also includes an operation unit for manually controlling the opening degree of each valve mechanism 32a, 32b.

  The control device 33a controls the opening degree of the water supply valve mechanism 32a based on the temperature of the exhaust gas measured by the temperature sensor installed in the downstream flue of the heat exchanger 11, and exchanges heat from the deaerator 25. The amount of water supplied to the heated medium supplied to the vessel 11 is adjusted.

  Since the property of the waste processed in the incinerator 1 varies variously, the amount of exhaust gas flowing into the heat exchanger 11 also varies. When the waste combustion state greatly decreases and the amount of exhaust gas decreases, the control device 33a prevents the temperature of the exhaust gas discharged from the heat exchanger 11 from falling below the first predetermined temperature. The amount of the heated medium supplied from the deaerator 25 to the heat exchanger 11 is reduced.

  In this way, the amount of water supplied to the heat exchanger 11 is adjusted by the control device 33a, and the flue on the downstream side of the heat exchanger 11 is adjusted by adjusting the temperature of the exhaust gas so that it does not fall below the first predetermined temperature. Occurrence of low-temperature corrosion in each processing facility arranged in the flue and in the flue can be prevented.

  In a waste treatment furnace equipped with an economizer having a large heat transfer area in order to eliminate the temperature reduction tower in front of the bag filter 12 and adopting a so-called low temperature eco that efficiently recovers waste heat, the combustion state of the waste When the amount of exhaust gas is greatly reduced and the amount of exhaust gas is reduced, heat is absorbed more than necessary by the economizer and the outlet temperature is lowered, which may cause low-temperature corrosion. However, according to the above-described configuration, even when using a normal economizer that is not so-called low-temperature eco, not only a temperature reduction tower is unnecessary, but also the amount of water supplied to the heat exchanger 11 is adjusted by the control device 33a. The occurrence of low temperature corrosion can be prevented in advance.

  When the waste combustion state greatly increases and the amount of exhaust gas increases, the control device 33a sets the temperature of the exhaust gas discharged from the heat exchanger 11 to a third predetermined value set higher than the first predetermined temperature. The opening degree of the water supply valve mechanism 32a is increased so as not to exceed the temperature, and the amount of the heated medium supplied from the deaerator 25 to the heat exchanger 11 is increased. Note that the third predetermined temperature is higher than the first predetermined temperature, and slightly higher than the temperature at which the filter cloth of the bag filter burns out when the temperature of the exhaust gas discharged from the heat exchanger 11 rises above this temperature. The temperature is low.

  In this way, the amount of water supplied to the heat exchanger 11 is adjusted by the control device 33a so that the temperature of the exhaust gas can be adjusted so as not to exceed the third predetermined temperature. Can be prevented.

  The control device 33b circulates and supplies the heated medium from the heat exchanger 11 to the deaerator 25, and adjusts the pressure of the heated medium measured by a pressure sensor provided on the upstream side of the drain valve mechanism 32b. Based on, for example, the opening degree of the drain valve mechanism 32b is controlled so that the pressure falls within a predetermined pressure range, the opening degree of the drain valve mechanism 32b is controlled, and the deaerator 25 from the heat exchanger 11 is controlled. The discharge amount of the heated medium that is circulated and supplied to is adjusted.

  The control device 33b maintains the opening degree of the drain valve mechanism 32b if the pressure measured by the pressure sensor is equal to or higher than a predetermined pressure in the range of 3 MPa to 4 MPa, and if the pressure is less than 3 MPa, the drain valve The opening degree of the mechanism 32b is reduced to reduce the discharge amount of the heated medium, and the pressure of the heated medium upstream of the drain valve mechanism 32b is increased. If the pressure is greater than 4 MPa, the control device 33b increases the discharge amount of the heated medium by increasing the opening degree of the drain valve mechanism 32b, and decreases the pressure of the heated medium upstream of the drain valve mechanism 32b. Let

FIG. 2 shows control steps of the valve mechanisms 32a and 32b by the control device 33 (33a and 33b).
The control device 33a has a first predetermined temperature, for example, 160, in which the temperature of the exhaust gas that has passed through the heat exchanger 11 is set in order to avoid low temperature corrosion of the equipment provided in the flue downstream of the heat exchanger 11. When the temperature falls below 0 ° C. (S 1, Y), the supply valve mechanism 32 a is closed or the opening degree is reduced to reduce the supply amount of the heated medium supplied to the heat exchanger 11, thereby avoiding a decrease in exhaust gas temperature. (S2).

  When the temperature of the exhaust gas is equal to or higher than the first predetermined temperature and equal to or lower than the third predetermined temperature set higher than the first predetermined temperature (S3, N), the opening degree of the water supply valve mechanism 32a is maintained (S5). ). When the temperature of the exhaust gas is higher than the third predetermined temperature (S3, Y), the amount of pressurized water supplied to the heat exchanger 11 is increased by increasing the opening of the water supply valve mechanism 32a, The temperature of the exhaust gas is lowered to a third predetermined temperature or less (S4).

  If the pressure of the medium to be heated (pressurized water) supplied from the heat exchanger 11 to the deaerator 25 is within a predetermined pressure range, for example, 3 MPa to 4 MPa (S6, Y), the controller 33b is a drain valve. The opening degree of the mechanism 32b is maintained (S7).

  If the pressure is higher than the predetermined pressure range (S8, Y), the control device 33b increases the opening degree of the drain valve mechanism 32b so as to be maintained in the predetermined pressure range (S9). The amount of pressurized water supplied to the deaerator 25 is increased to prevent the heat exchanger from blowing up. If the pressure is lower than the predetermined pressure range (S8, N), the opening degree of the drain valve mechanism 32b is decreased (S10) so as to be maintained within the predetermined pressure range, and the heat exchanger 11 moves to the deaerator 25. The amount of pressurized water supplied is reduced to prevent the pressurized water from evaporating in the heat exchanger and the heated medium from being blown out.

  In steps S2 and S4, for example, PID control can be performed in which the opening target value of the water supply valve mechanism 32a is calculated based on a deviation between the current exhaust gas outlet temperature and the exhaust gas outlet target temperature, and the target value is controlled. . For example, the first predetermined temperature, which is the lower limit temperature for avoiding the low temperature corrosion described above, can be set as the exhaust gas outlet target temperature.

  In steps S9 and S10, for example, PID control for calculating a target value of the opening degree of the valve mechanism based on a deviation between the current pressure of the pressurized water and the target pressure set in a predetermined pressure range and controlling the target value is performed. It can be carried out.

  In the description using FIG. 1 and FIG. 2, one control device 33 is configured by two separate blocks indicated by reference numerals 33a and 33b. However, one control device is formed by one block in which each block is combined. It may be comprised, and may be comprised by the separate control apparatus corresponding to each block.

  In addition, when each block is configured by an individual control device, the control information may be transmitted and received with a signal line connecting the control devices. For example, the control device 33a can obtain the flow rate of the heated medium by receiving the throttle amount of the drain valve mechanism 32b from the control device 33b.

Hereinafter, based on FIG. 3, the driving | running aspect of a waste treatment facility provided with the waste heat recovery equipment 30 by this invention is demonstrated.
A gas for stirring is supplied to the secondary combustion section 5 of the incinerator 1 by a gas supply mechanism 7. The 4 MPa, 400 ° C. superheated steam obtained by the waste heat boiler 8 and the superheater 9 installed in the secondary combustion section 5 that burns in the range of about 800 ° C. to 1000 ° C. is supplied to the steam turbine 21 via the steam reservoir 27. And the generator 22 is driven.

  The exhaust steam from the steam turbine 21 is condensed in the condenser 23 and collected in the condensate tank 24. Thereafter, the condensate of about 60 ° C. collected in the condensate tank 24 is supplied to the deaerator 25 and degassed, and supplied to the economizer 10 and the heat exchanger 11 as boiler feed water heated to 143 ° C. .

  The boiler feed water supplied to the economizer 10 is heated to 200 ° C. and then supplied to the waste heat boiler 8. The boiler feed water supplied to the heat exchanger 11 is heated to a pressure of 3 MPa to 4 MPa and a temperature of about 160 ° C., and then circulated and supplied to the deaerator 25.

  The exhaust gas heat-exchanged by the waste heat boiler 8 and the superheater 9 and reduced in temperature to about 350 ° C. is reduced in the range of 210 ° C. to 180 ° C. by the economizer 10 and further 180 ° C. to 160 ° C. by the heat exchanger 11. After the temperature is reduced to the range of ° C., the dust is removed by the bag filter 12, and the acid gas component is removed by a smoke washing device or the like and then exhausted from the chimney 15.

  FIG. 4 (a) shows an example in which a boiler feed water at 143 ° C. is preheated to 200 ° C. and the exhaust gas is reduced to 210 ° C. by using a general economizer with 350 ° C. exhaust gas. . FIG. 4B shows an example in which a boiler feed water of 143 ° C. is preheated to about 210 ° C. and the exhaust gas is reduced to 180 ° C. by 350 ° C. exhaust gas using a high efficiency low temperature economizer. Yes.

  According to the former, it is necessary to install a temperature reducing tower, for example, a temperature reducing tower that sprays water on the exhaust gas to reduce the temperature between the economizer and the subsequent bag filter. Therefore, it is not necessary to provide a temperature reducing tower, and waste heat can be efficiently recovered.

  In FIG. 4 (c), the heat exchanger of the waste heat recovery equipment of the present invention is arranged after the economizer, and the boiler feed water at 143 ° C. is preheated to about 200 ° C. by the economizer by the exhaust gas at 350 ° C. An example is shown in which the temperature is reduced to 210 ° C., the boiler feed water at 143 ° C. is preheated to about 160 ° C. by the heat exchanger and the exhaust gas is reduced to 180 ° C. by the exhaust gas at 210 ° C.

Heat absorption Q, overall heat transfer coefficient K, heat transfer area A, temperature T, logarithmic mean temperature difference ΔT, specific heat C, flow rate W, exhaust gas heat exchanger inlet temperature Tg1, outlet temperature Tg2, heat medium inlet temperature Assuming Tw2 and outlet temperature Tw1, the following approximate expression is established.
[Formula 1]
Q = KAΔT
[Formula 2]
Q = {WCT (exit)-WCT (entrance)} ∝ (T (exit)-T (entrance))
[Formula 3]
ΔT = {(Tg1-Tw1)-(Tg2-Tw2)} / {ln (Tg1-Tw1) -ln (Tg2-Tw2)}
Here, K and WC are assumed to be substantially constant.

  When the logarithmic temperature difference ΔT in each of FIGS. 4A, 4B, and 4C is obtained, Q is obtained from Equation 2, and Q and ΔT are substituted into Equation 1 to obtain KA. In a), KA = 1.359, in FIG. 4B, KA = 2.218, in FIG. 4C, the front stage has KA = 1.359 and the rear stage has KA = 0.622. These values correspond to the total area of the heat transfer section.

  Based on the heat transfer area of the basic economizer in FIG. 4 (a), the heat transfer area is about 1.63 times larger in the high-efficiency low-temperature economizer in FIG. 4 (b), and FIG. When the heat exchanger of the present invention and the conventional economizer are combined, the heat transfer area is about 1.48 times. That is, the exhaust gas temperature can be reduced equally with a smaller heat transfer area than the high-efficiency low-temperature economizer of FIG.

  In a waste treatment facility in which two stoker-type incinerators 1, 1 ′ are provided as an example of a waste treatment furnace, the incinerator 1 ′ is also operated in the same manner as described above for the incinerator 1. In addition, even if it is a waste treatment facility provided with only one incinerator, the above-described incinerator 1 can be operated similarly to the operation.

  At the time of regular inspection of the waste treatment facility, both of the two incinerators are not shut down at the same time, and at least one of them is operated. This is because it is necessary to always incinerate municipal waste carried into the waste treatment facility, and it is therefore necessary to operate the power generation facility 20.

  When the incinerator that has been stopped due to periodic inspection or the like is started up again, a start-up operation is required in which fossil fuel is supplied to the auxiliary burner and the furnace is shifted to a predetermined combustion state. In the meantime, since the exhaust gas with relatively low temperature and high humidity flows into the flue, the deliquescent substance captured by the bag filter 12 contains moisture, and the filter may be clogged or low temperature corrosion may occur. is there.

  Therefore, as shown in FIG. 1, the waste incinerator 1 is provided with a heating source such as an electric heater H and an induction blower 19. The above-mentioned inconvenience is avoided by attracting the exhaust gas downstream of the flue with the induction blower 19 and heating it with the electric heater H and supplying it to the upstream side of the bag filter.

  However, if the waste heat recovery facility 30 according to the present invention is used, in order to reduce the electric power for heating the exhaust gas during the start-up operation, the heat that is heated by the heat exchanger 11 of the waste incinerator in operation is added. The stored heat of the pressurized water can be used to heat the exhaust gas from the waste incinerator that is in operation.

  That is, a heat exchanger 11 is installed in each flue, and a plurality of waste treatment furnaces 1 and 1 ′ each equipped with a control mechanism 32 and 33 for controlling each heat exchanger 11 are provided along with deaeration. In the waste treatment facility configured to share the container 25, the control mechanisms 32 and 33 of the waste heat recovery facility 30 incorporated in the waste treatment facility operate the other waste treatment furnace 1 ′. Assuming that the waste gas is supplied to the heat exchanger 11 provided in the waste treatment furnace 1 whose operation is restarted, pressurized exhaust water is supplied from the deaerator 25 to heat the exhaust gas.

  Specifically, the control mechanisms 32 a and 33 a drive the feed water pump 31 to supply pressurized feed water from the deaerator 25 to the heat exchanger 11, flow down the flue, and flow into the heat exchanger 11. Heat the exhaust gas. The controller 33a controls the valve mechanism 32a so as to adjust the amount of water supplied to the heat exchanger so that the exhaust gas temperature at the outlet of the heat exchanger 11 exceeds the second predetermined temperature. At this time, the valve mechanism 32b may be opened or adjusted to a predetermined opening degree.

The amount of heat “Q (supply)” used to heat the exhaust gas to a predetermined temperature in the heat exchanger 11 is the amount of heat originally supplied to the steam turbine, and is necessary for heating the exhaust gas to the predetermined temperature with the electric heater H. It is equivalent to the amount of heat “Q (electricity)”.
[Formula 4]
Q (supply) = Q (electricity)

The power generation amount “Q (power generation)” when the heat amount “Q (supply)” is supplied to the steam turbine takes into account the steam turbine machine efficiency “η (machine)” and the generator efficiency “η (generator)”. For example, it is expressed by the following formula.
[Formula 5]
Q (departure) = Q (supply) x η (machine) x η (generator)

Since “η (machine)” and “η (generator)” are both smaller than 1 and η (machine) × η (generator) = 0.95, the following equation holds.
[Formula 6]
Q (Departure) <Q (Salary)

The following equation is established from Equations 4 and 6, and the electric power Q (electricity) used for heating by the electric heater is more than the electric power Q (electricity) generated by the amount of heat originally supplied to the steam turbine for electric power generation. That is, it means that heating the exhaust gas with the amount of heat originally supplied to the steam turbine for power generation is more efficient than heating the exhaust gas with an electric heater.
[Formula 7]
Q (departure) <Q (supply) = Q (electricity)

  As described above, when the other incinerator 1 ′ is operated, the pressurized water supply to the deaerator 25 is maintained at a sufficient temperature by the waste heat recovery facility 30 of the other incinerator 1 ′. Even if the low-temperature pressurized feed water discharged from the heat exchanger 11 of the incinerator 1 at the time of start-up is returned to the deaerator 25, no particular inconvenience occurs.

  As shown in FIG. 5, when the temperature of the exhaust gas discharged from the heat exchanger 11 is lower than the second predetermined temperature (SA1, Y), the control device 33a increases the opening of the water supply valve mechanism 32a. Thus, by increasing the supply amount of the pressurized water supplied from the deaerator 25 to the heat exchanger 11 (SA2), the heat transfer amount to the exhaust gas is increased.

  When the temperature of the exhaust gas is higher than the second predetermined temperature (SA1, N), the controller 33a reduces the opening of the water supply valve mechanism 32a and pressurizes the heat supplied from the deaerator 25 to the heat exchanger 11. By reducing the amount of water supply (SA3), the amount of heat transferred to the exhaust gas is reduced.

  After the start-up of the furnace is completed, the water supply valve mechanism 32a is closed, and then the control is performed to recover the retained heat of the exhaust gas shown in FIG.

  The second predetermined temperature is a temperature at which deliquescent substances captured by the bag filter can avoid a situation in which the moisture of the exhaust gas discharged from the heat exchanger absorbs moisture and causes an unfavorable situation, It is set to at least 100 ° C. or more, preferably 110 ° C.

  When it is necessary to avoid the occurrence of low-temperature corrosion due to the exhaust gas, it is preferable to use the electric heater H as an auxiliary to heat the exhaust gas temperature to the first predetermined temperature or higher. Control of the electric heater H at this time is also preferably performed by the control mechanisms 32a and 33a.

  In the above-described example, the heat exchanger 11 is installed in each flue of the plurality of waste treatment furnaces 1 and 1 ′, and the control mechanisms 32 and 33 for controlling the heat exchangers 11 are respectively provided. Although explained, one control device 33a, 33b which constitutes control mechanism 32, 33 may be provided, and the one control device 33a, 33b may be constituted so that each heat exchanger 11 may be controlled. In this case, heating control of the exhaust gas is performed on the heat exchanger 11 of the waste treatment furnace being started up, and the heat exchanger 11 of the waste treatment furnace being operated is connected to the deaerator. Control to supply the heat source is performed.

  In the above-described embodiments, the configuration in which the economizer 10 is provided in the flue downstream of the waste heat boiler 8 has been described, but heat exchange is performed in the flue downstream of the waste heat boiler 8 without providing the economizer 10. The structure provided only with the container 11 may be sufficient.

  In other words, the waste treatment furnace according to the present invention is installed in a flue and supplied with the pressurized feed water of the deaerator 25 supplied to the waste heat boiler 8 as a heated medium and heated by heat exchange with the exhaust gas. The heat exchanger 11 in which the heated medium is circulated and supplied to the deaerator 25 as a deaeration heat source, and the exhaust gas discharged from the heat exchanger 11 is supplied to the heat exchanger 11 so that it does not fall below the first predetermined temperature. And a waste heat recovery facility including a control mechanism for adjusting the amount of water supply.

  In embodiment mentioned above, although each valve mechanism 32a, 32b was automatically controlled by the control apparatus 33, the supply amount of the pressurized water supply to the heat exchanger 11 and the pressure of the heat exchanger 11 were demonstrated, The waste heat recovery method according to the present invention is not limited to automatic control by the controller 33, but manually adjusts the valve mechanism 32a so that the exhaust gas does not fall below the first predetermined temperature based on the exhaust gas outlet temperature of the heat exchanger 11. The valve mechanism 32b may be manually adjusted so that the pressure of the heat exchanger 11 is equal to or higher than a predetermined pressure.

  In other words, a waste heat recovery method for a waste treatment furnace equipped with a waste heat boiler is installed in a flue and is supplied with pressurized feed water of a deaerator supplied to the waste heat boiler as a heated medium. With respect to the heat exchanger in which the heated medium heated by the heat exchange is circulated and supplied to the deaerator as a deaeration heat source, the exhaust gas discharged from the heat exchanger does not fall below the first predetermined temperature. In addition, it may be configured to adjust the amount of water supplied to the heat exchanger.

  Similarly, at the time of start-up of the furnace, the feed water pump 31 is manually started to supply pressurized feed water from the deaerator 25 to the heat exchanger 11 and flow down into the flue and flow into the heat exchanger 11. The exhaust gas may be heated. At this time, the valve mechanism 32a may be manually adjusted so that the exhaust gas temperature at the outlet of the heat exchanger 11 exceeds the second predetermined temperature.

  In the above-described embodiment, the example in which the waste heat recovery facility is incorporated in the stoker-type incinerator has been described. However, the incinerator is not limited to the stoker-type, and other types of incinerators such as a fluidized bed type and a rotary kiln type. There may be. In addition, the waste treatment furnace is not limited to an incinerator, and may be any treatment furnace equipped with a power generation facility that generates power using steam generated in a waste heat boiler. For example, a melting furnace such as a coke bed melting furnace or a surface melting furnace It may be.

  The embodiment described above is a specific example of the present invention, and the scope of the present invention is not limited by the description, and the specific configuration of each part of the waste heat recovery facility exhibits the effects of the present invention. Needless to say, the design can be changed as appropriate within the range.

1: Incinerator (waste treatment furnace)
5: Secondary combustion section 7: Gas supply mechanism 8: Waste heat boiler 10: Economizer 11: Heat exchanger 20: Power generation facility 21: Steam turbine 22: Generator 23: Condenser 25: Deaerator 30: Waste heat Recovery equipment 31: water supply pumps 32, 32a, 32b: control mechanism (valve mechanism)
33, 33a, 33b: Control mechanism (control device)

Claims (7)

A waste heat recovery facility incorporated in a waste treatment furnace equipped with a waste heat boiler,
Pressurized water supply of a deaerator installed in a flue and supplied to the waste heat boiler is supplied as a heated medium, and the heated medium heated by heat exchange with exhaust gas is used as the deaerated heat source. A heat exchanger circulated and supplied to
A control mechanism that adjusts the amount of water supplied to the heat exchanger so that the exhaust gas discharged from the heat exchanger does not fall below a first predetermined temperature;
Waste heat recovery equipment equipped with.   The waste heat recovery facility according to claim 1, wherein the control mechanism is configured to adjust a discharge amount of the heated medium so that the heated medium discharged from the heat exchanger has a predetermined pressure or more.   The waste heat recovery facility according to claim 1 or 2, wherein the heat exchanger is installed in a flue downstream of an economizer, and the pressurized feed water of a deaerator supplied to the economizer is branched and supplied as a medium to be heated. A plurality of waste treatment furnaces provided with the heat exchangers are provided in each flue, and the deaerator is configured to be shared,
When the other waste treatment furnace is in operation, the control mechanism supplies the pressurized feed water from the deaerator to the heat exchanger to be controlled provided in the waste treatment furnace that resumes operation to generate exhaust gas. The waste heat recovery facility according to any one of claims 1 to 3, which is heated.   The waste heat recovery facility according to claim 4, wherein the control mechanism adjusts the amount of water supplied to the control target heat exchanger so that the exhaust gas discharged from the heat exchanger exceeds a second predetermined temperature. A waste heat recovery method for a waste treatment furnace equipped with a waste heat boiler,
Pressurized water supply of a deaerator installed in a flue and supplied to the waste heat boiler is supplied as a heated medium, and the heated medium heated by heat exchange with exhaust gas is used as the deaerated heat source. For heat exchangers circulated to
A waste heat recovery method for adjusting an amount of water supplied to the heat exchanger so that exhaust gas discharged from the heat exchanger does not fall below a first predetermined temperature. A waste treatment furnace equipped with a waste heat boiler,
Pressurized water supply of a deaerator installed in a flue and supplied to the waste heat boiler is supplied as a heated medium, and the heated medium heated by heat exchange with exhaust gas is used as the deaerated heat source. A heat exchanger circulated and supplied to
A control mechanism that adjusts the amount of water supplied to the heat exchanger so that the exhaust gas discharged from the heat exchanger does not fall below a first predetermined temperature;
Waste treatment furnace equipped with waste heat recovery equipment.

Images