JP2010151432A - Incineration exhaust heat utilization system for utilizing exhaust heat of waste incinerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an incineration exhaust heat utilization system having a constitution capable of suppressing abrasion of a heat exchanger used in recovering heat without degrading power generation efficiency and combustion efficiency. <P>SOLUTION: This incineration exhaust heat utilization system 101 includes: an incinerator 21 for incinerating charged waste; a waste heat boiler 22 generating steam by using an exhaust gas discharged from the incinerator 21; a bag filter 24 disposed at a downstream side of the waste heat boiler 22, the heat exchanger 23 disposed between the waste heat boiler 22 and the bag filter 24, and recovering heat from the boiler exhaust gas of the waste heat boiler 22, and a direct contact type heat storage device 1 connected with the heat exchanger 23 and storing the recovered heat. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an incineration waste heat utilization system for effectively utilizing waste heat generated in a waste incineration facility.

  Conventionally, waste heat generated in a waste incineration facility equipped with a waste incinerator or the like has been used in various facilities such as a heated pool and a public bath near the waste incineration facility. Here, as a method of transporting the heat energy of waste heat from the waste incineration facility to these neighboring facilities, for example, a pipe such as a pipe is laid from the waste incineration facility to the heat utilization facility using heat. There is a pipeline transportation method to transport. Heat energy is sent to the heat utilization facility in the form of hot water, hot water, and steam through the laid pipe.

  However, with this method, there is a problem that the cost for laying pipes increases as the heat utilization facility becomes farther away. Under such a background, for example, a heat transport method described in Patent Document 1 has been proposed as a technique for transporting thermal energy possessed by exhaust heat without laying a pipeline.

  The heat transport method (waste incineration heat utilization system) described in Patent Document 1 stores heat in a heat storage and transfer device that can be moved anywhere in the form of a tank lorry, and this heat storage and transfer device allows hot water from a waste incineration facility. Heat is transported to a heat utilization facility such as a pool. According to this method, there is an advantage that heat energy can be transported at low cost not only to facilities near the incineration facility but also to relatively distant facilities.

JP 2008-106954 A

  However, in the waste incineration heat utilization system described in Patent Document 1, heat is recovered from steam generated in a waste heat boiler of a waste incinerator, heat is recovered from combustion air preheated by an air preheater, or waste incineration is performed. Heat is recovered directly from the high-temperature exhaust gas from the furnace.

  Here, when heat is recovered from the steam generated in the waste heat boiler, the amount of steam supplied to the power generation turbine is reduced, leading to a decrease in power generation efficiency. In addition, when heat is recovered from the preheated combustion air, the temperature of the combustion air decreases, leading to a decrease in combustion efficiency. Furthermore, when heat is recovered directly from the high-temperature exhaust gas from the waste incinerator, the heat exchanger is severely worn and repair costs increase.

  The present invention has been made in view of the above circumstances, and its object is to reduce the power generation efficiency and the combustion efficiency and to suppress the wear of the heat exchanger used for heat recovery. It is to provide an incineration exhaust heat utilization system equipped.

Means and effects for solving the problems

  As a result of intensive studies to solve the above problems, the present inventors installed a heat exchanger between the waste heat boiler of the incinerator and the dust collector, and from the boiler exhaust gas of the waste heat boiler using this heat exchanger. It has been found that the above problems can be solved by recovering heat, and the present invention has been completed based on this finding.

  That is, in order to solve the above-described problems, the present invention provides an incinerator that incinerates input waste, a waste heat boiler that generates steam using exhaust gas discharged from the incinerator, and the waste heat boiler. A heat exchanger that recovers heat from boiler exhaust gas that is installed between the dust collector installed on the downstream side of the waste heat boiler and the dust collector, and is recovered after heat recovery in the waste heat boiler, and An incineration exhaust heat utilization system comprising: a heat storage device connected to a heat exchanger and storing the collected heat.

  According to this configuration, since all the steam generated in the waste heat boiler can be used for power generation, a decrease in power generation efficiency can be prevented. Moreover, since heat recovery is not performed from the preheated combustion air, it is possible to prevent a decrease in combustion efficiency. Furthermore, since the temperature of the boiler exhaust gas discharged from the waste heat boiler is lower than the temperature of the high-temperature exhaust gas in the incinerator, it is possible to suppress wear of the heat exchanger used for heat recovery.

  Moreover, in this invention, it is preferable that the said heat exchanger collects heat from the said boiler exhaust gas of 170-250 degreeC from a viewpoint of the improvement of the heat recovery rate in a boiler, and heat exchanger wear suppression.

  According to this configuration, heat is recovered from the boiler exhaust gas having a temperature of 170 to 250 ° C., which is lower than that of the high-temperature exhaust gas from the incinerator, so that the wear of the heat exchanger used for the heat recovery can be sufficiently suppressed. If the temperature of the boiler exhaust gas is less than 170 ° C., the heat recovery efficiency may be lowered and the problem of low temperature corrosion of the heat exchanger may occur. Further, when the temperature of the boiler exhaust gas is higher than 250 ° C., the amount of heat recovery in the boiler is reduced.

  Furthermore, in the present invention, the heat storage device is a direct contact heat storage device that houses a heat storage material used for latent heat storage and mineral oil that exchanges heat by directly contacting the heat storage material, and is 120 to 140 ° C. It is preferable to store the recovered heat by circulating the mineral oil.

  According to this structure, the low temperature corrosion of a heat exchanger can be suppressed more by making the temperature of the mineral oil used as a heat medium into 120-140 degreeC.

  Furthermore, in the present invention, the heat storage material is preferably erythritol. According to this configuration, it is possible to store heat by effectively using the latent heat of erythritol, and the heat storage amount of the heat storage device can be increased.

  Further, according to the second aspect of the present invention, from a 170 to 250 ° C. boiler exhaust gas discharged from the waste heat boiler by a heat exchanger installed between the waste heat boiler of the incinerator and the dust collector. An incineration exhaust heat utilization method comprising: a heat recovery process for recovering heat; and a heat storage process for storing the recovered heat in a heat storage device.

  According to this configuration, since all the steam generated in the waste heat boiler can be used for power generation, a decrease in power generation efficiency can be prevented. Moreover, since heat recovery is not performed from the preheated combustion air, it is possible to prevent a decrease in combustion efficiency. Furthermore, since the temperature of the boiler exhaust gas discharged from the waste heat boiler is lower than the temperature of the high temperature exhaust gas of the incinerator such as 170 to 250 ° C., the wear of the heat exchanger used for heat recovery is sufficiently reduced. Can be suppressed.

  In the present invention, the heat storage device is a direct contact heat storage device that houses a heat storage material used for latent heat storage and mineral oil that performs heat exchange by directly contacting the heat storage material, and in the heat storage step, It is preferable to store the recovered heat by circulating the mineral oil at 120 to 140 ° C. between the heat storage device and the heat exchanger.

  According to this structure, the low temperature corrosion of a heat exchanger can be suppressed more by making the temperature of the mineral oil used as a heat medium into 120-140 degreeC.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Here, first, the heat transport method using the heat storage device and the configuration of the direct contact type heat storage device will be described, and then the incineration exhaust heat utilization system including the heat storage device and the incineration waste heat utilization method by the system Will be described.

(Heat transport method using heat storage device)
FIG. 1 is a schematic diagram for explaining a heat transport method using the heat storage device 1. As shown in FIG. 1, in this heat transport method, heat utilization facilities such as a hospital, a school, a hot water pool, and a building heating facility are connected to the waste heat generated in the waste incineration facility 100 via a heat storage device 1. It is a method for transporting to 200. The heat storage device 1 is mounted on the loading platform 2 of the transport vehicle 3 and conveyed.

  First, waste heat generated in the waste incineration facility 100 is stored in the heat storage device 1 mounted on the loading platform 2 of the transport vehicle 3 such as a truck, and the heat storage device 1 is transported to the heat utilization facility 200 (see FIG. 1A). ). Then, heat is supplied from the heat storage device 1 to the heat utilization facility 200, and after the heat supply is completed, the heat storage device 1 is returned to the waste incineration facility 100 (see FIG. 1B). In this way, the heat storage device 1 reciprocates between the waste incineration facility 100 and the heat utilization facility 200 as necessary while being mounted on the loading platform 2 of the transport vehicle 3. Note that, among the arrows in FIG. 1, the dotted arrow indicates the moving direction of the transport vehicle 3, and the solid line arrow indicates the heat moving direction.

(Heat storage device)
Next, the heat storage device 1 will be described. FIG. 2 is a schematic diagram of the heat storage device 1. As shown in FIG. 2, the heat storage device 1 includes a heat storage material 12 that is used for latent heat storage, a heat storage container 11 that houses the heat storage material 12, and a heat medium 13 that has a smaller specific gravity than the heat storage material 12. A supply pipe 14 for supplying the heat storage container 11 from the outside to the heat storage container 11 and a discharge pipe 15 for discharging the heat medium 13 supplied to the heat storage container 11 to the outside of the heat storage container 11 are provided.

  The heat storage container 11 is, for example, a steel plate container (tank). By being covered with a heat insulating material such as glass wool or having a double-structured container, the heat storage container 11 is improved in heat insulation.

  As the heat storage material 12, it is preferable to employ a substance that has a large latent heat (heat of fusion) and becomes solid at room temperature, and examples of such a substance include erythritol. Erythritol is a substance having a melting point: about 121 ° C. and a heat of fusion: about 340 kJ / kg, and is solid at room temperature. In the following description, it is assumed that erythritol is adopted as the heat storage material 12 unless otherwise specified. Moreover, it is preferable to employ | adopt the substance which can maintain the state isolate | separated completely from the thermal storage material 12 as the heat medium 13, and mineral oil is mentioned as such a substance, for example. In the following description, it is assumed that mineral oil is employed as the heat medium 13 unless otherwise specified.

  In addition, as the heat storage material 12, sodium acetate trihydrate can also be employ | adopted. Sodium acetate trihydrate is a substance having a melting point: about 58 ° C. and a heat of fusion: about 250 kJ / kg, and is solid at room temperature. Moreover, you may employ | adopt heat storage materials, such as water, as a heat storage material. Water is a liquid having a very large specific heat (specific heat: 1 cal / g) and is suitable as a heat storage material. In the case where the heat utilization facility 200 is a facility that directly uses hot water such as a public bath or a warm water pool, the heat loss is that heat water stored in the heat storage container 11 as a heat storage material can be directly used in the heat utilization facility 200. Can be reduced.

  The heat medium 13 heated by exhaust heat from the waste incineration facility 100 (or dissipated to the heat utilization facility 200) is supplied from the supply rod 14 shown in FIG. 2 into the heat storage material 12 accommodated in the heat storage container 11. The heat storage material 12 is directly contacted with the heat storage material 12 to exchange heat with the heat storage material 12 and rise (floating) due to the specific gravity difference between the heat storage material 12 and the heat medium 13. The heat medium 13 reaches the layer of the heat medium 13 formed above the heat storage material 12. The heat medium 13 reaching the layer of the heat medium 13 and radiating (receiving heat) is heated from the waste heat of the waste incineration facility 100 (or to radiate heat to the heat utilization facility 200) from the discharge pipe 15. It is discharged outside.

(Incineration exhaust heat utilization system)
Next, an incineration exhaust heat utilization system will be described. FIG. 3 is a block diagram showing the incineration exhaust heat utilization system 101. As shown in FIG. 3, the incineration waste heat utilization system 101 is a waste incineration facility 100 in which a heat exchanger 23 and a heat storage device 1 are incorporated. In the following description, first, the outline of the waste incineration facility 100 will be described, and then the heat exchanger 23 and the heat storage device 1 will be described. It should be noted that the heat exchanger 23 can be grasped not as a device built into the waste incineration facility 100 but as a component device constituting the waste incineration facility 100 itself. There is no substitute for the devices constituting the system 101.

(Waste incineration facility)
As shown in FIG. 3, the waste incineration facility 100 includes an incinerator 21 that incinerates the input waste. Examples of the incinerator 21 include a fluidized bed furnace, a stoker furnace, and a gasification melting furnace. In this embodiment, the incinerator 21 has a processing amount of 10,417 kg / h / furnace (250 t / d / furnace).

  In addition, the waste incineration facility 100 includes a waste heat boiler 22, a bag filter 24 (dust collector), a reheater 25, a catalytic reaction tower 26, and a chimney 27 in order from the upstream side of the flow of exhaust gas discharged from the incinerator 21. It has. The waste incineration facility 100 includes a steam turbine 28 driven by steam generated in the waste heat boiler 22 and a generator 29.

  The high-temperature exhaust gas at 800 to 900 ° C. discharged from the incinerator 21 enters the waste heat boiler 22 installed in the subsequent stage. Steam (37,000 kg / h / furnace) generated by heat recovery from the high-temperature exhaust gas in the waste heat boiler 22 is supplied to the steam turbine 28 to rotate the turbine. Power is generated by the generator 29 as the turbine rotates. The power generation amount is about 20,000 kW / 3 furnace. The temperature of the steam generated in the waste heat boiler 22 is 300 to 400 ° C., and the pressure is 3 to 4 MPa.

On the other hand, the boiler exhaust gas of about 190 ° C. discharged after the heat recovery by the waste heat boiler 22 is reduced to a temperature of about 170 ° C. through the heat exchanger 23 described later. This exhaust gas is sent to the bag filter 24 to remove dust and acid gas contained in the exhaust gas. Thereafter, the temperature is raised to about 210 ° C. by the reheater 25 and then enters the catalytic reaction tower 26. In the catalytic reaction tower 26, ammonia reacts with nitrogen oxides in the exhaust gas, and the nitrogen oxides are decomposed into harmless nitrogen and water. The exhaust gas leaving the catalytic reaction tower 26 is discharged from the chimney 27 into the atmosphere. The exhaust gas temperature at the smoke outlet is about 200 ° C., and the amount of exhaust gas is 59,000 m ³ N / h / furnace.

(Heat exchanger and heat storage device)
The heat exchanger 23 is installed between the waste heat boiler 22 and the bag filter 24. An example of the heat exchanger 23 is a plate heat exchanger. About 190 ° C. boiler exhaust gas is supplied to the heat exchanger 23 from the waste heat boiler 22.

  The heat storage device 1 is connected to the heat exchanger 23 via the heat medium circulation path 16. The heat medium 13 accommodated in the heat storage device 1 (accommodated in the heat storage container 11) is circulated in the heat medium circulation path 16 by the pump P. In the present embodiment, the heat storage amount of the heat storage device 1 is 1.6 GJ / h / furnace.

(Incineration exhaust heat utilization method)
Next, an incineration waste heat utilization method by the incineration waste heat utilization system 101 will be described. First, the supply pipe 14 and the discharge pipe 15 of the heat storage device 1 are connected to the heat medium circulation path 16. Thereafter, the pump P is operated, and the heat medium 13 is circulated in the heat medium circulation path 16. In the present embodiment, the circulation amount of the heat medium 13 is 40 m ³ / h / furnace.

(Heat recovery process)
The heat exchanger 23 recovers the exhaust heat from the boiler exhaust gas of about 190 ° C. that is discharged after the heat recovery by the waste heat boiler 22. The heat is transferred from the boiler exhaust gas to the heat medium 13 by the indirect contact between the boiler exhaust gas of about 190 ° C. and the heat medium 13 circulating in the heat medium circulation path 16 in the heat exchanger 23.

(Heat storage process)
The heat medium 13 raised to about 140 ° C. in the heat exchanger 23 returns to the heat storage device 1 through the heat medium circulation path 16 and directly contacts the heat storage material 12 in the heat storage container 11, so that the heat storage material 12 Heat is stored. The heat medium 13 that has radiated heat to the heat storage material 12 decreases in temperature to about 120 ° C., is discharged from the heat storage container 11, and enters the heat exchanger 23 again.

(Heat transport process)
When the heat storage to the heat storage material 12 in the heat storage container 11 is completed, the connection between the heat storage device 1 and the heat medium circulation path 16 is released, and the heat storage container 11 is transported to the heat utilization facility 200 by the method shown in FIG. To do. Then, heat is supplied from the heat storage device 1 to the heat utilization facility 200 via a heat exchanger (not shown) or the like.

  As described above, according to this incineration exhaust heat utilization system 101, all the steam generated in the waste heat boiler 22 can be supplied to the steam turbine 28 and used for power generation, resulting in a decrease in power generation efficiency. There is no. Moreover, since heat recovery is not performed from the preheated combustion air, the combustion efficiency of the incinerator 21 is not reduced. Furthermore, since heat is recovered from the boiler exhaust gas at a low temperature compared to the high temperature exhaust gas of the incinerator 21 of about 190 ° C. that is discharged after the heat recovery in the waste heat boiler 22, wear of the heat exchanger 23 is sufficiently suppressed. can do. In addition, it is preferable that the temperature of boiler exhaust gas shall be 170 degreeC or more and 250 degrees C or less. If the temperature of the boiler exhaust gas is lower than 170 ° C., the heat recovery efficiency may be lowered and the problem of low-temperature corrosion of the waste heat boiler 23 and the heat exchanger 23 may occur. In addition, when the temperature of the boiler exhaust gas is higher than 250 ° C., the boiler recovery heat amount is lowered, so that the power generation efficiency is lowered.

  Moreover, the low temperature corrosion of the heat exchanger 23 can be further suppressed by setting the temperature of the heat medium 13 circulating through the heat medium circulation path 16 to 120 to 140 ° C. Here, moisture is contained in the exhaust gas at a rate of 20 to 30%. Low temperature corrosion is a corrosion that occurs when condensation occurs on the surface of the iron shell in the heat exchanger 23 and corrosive gases such as chlorine gas and SOx (sulfur oxide) contained in the exhaust gas melt into the condensation. That is.

  Moreover, by adopting erythritol as the heat storage material 12, heat can be stored by effectively using the latent heat of erythritol, and the heat storage amount of the heat storage device 1 can be increased.

  In general, a temperature reducing tower for lowering the exhaust gas temperature is installed between the waste heat boiler 22 and the bag filter 24. However, according to the incineration exhaust heat utilization system of the present invention, the temperature reducing tower is not necessary. Therefore, the installation space of the waste incineration facility 100 can be reduced accordingly. Moreover, since it uses without throwing away heat in a temperature-reduction tower, the exhaust heat utilization factor can be improved as the whole equipment.

  Next, another embodiment of the present invention will be described. FIG. 4 is a block diagram showing the incineration exhaust heat utilization system 101. 4, a second heat exchanger 30 is provided between the catalytic reaction tower 26 and the chimney 27 of the incineration exhaust heat utilization system of FIG. 3, and the heat medium circulation path 16 is also provided in the second heat exchanger 30. Except being connected, it is the same structure as the incineration exhaust heat utilization system 101 shown in FIG. 3, and the same name and the same code | symbol are attached | subjected.

  In the incineration exhaust heat utilization system 101 in FIG. 4, the heat recovery capability in the waste heat boiler 22 is strengthened, and the high-temperature exhaust gas is heat recovered up to 170 ° C., thereby further improving the power generation efficiency. However, when heat is recovered to 170 ° C. with the waste heat boiler 22, the amount of heat recovered from the boiler exhaust gas in the heat exchanger 23 is reduced. Therefore, the second heat exchanger 30 is provided at the outlet of the catalytic reaction tower 26, and heat is recovered from the exhaust gas at 170 ° C. to 220 ° C. discharged from the catalytic reaction tower 26. The exhaust gas at the outlet of the catalytic reaction tower 26 can be recovered and effectively used.

  In addition, since the exhaust gas at the outlet of the catalytic reaction tower 26 is in a state where dust and acid gas in the exhaust gas are removed, it is possible to further suppress wear of the second heat exchanger 30.

  As described above, in the incineration exhaust heat utilization system 101 in this embodiment, both effective utilization of unused energy and improvement in power generation efficiency can be achieved, and the overall thermal efficiency of the plant can be improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

It is a schematic diagram for demonstrating the heat transport method using a thermal storage apparatus. It is a schematic diagram of a thermal storage apparatus. It is a block diagram which shows an incineration waste heat utilization system. It is a block diagram which shows the incineration waste heat utilization system in another embodiment.

Explanation of symbols

1: Thermal storage device (direct contact thermal storage device)
12: Heat storage material 13: Heat medium 16: Heat medium circulation path 21: Incinerator 22: Waste heat boiler 23: Heat exchanger 24: Bag filter (dust collector)
30: Second heat exchanger 100: Waste incineration facility 101: Incineration exhaust heat utilization system

Claims (6)

An incinerator that incinerates the input waste;
A waste heat boiler that generates steam using the exhaust gas discharged from the incinerator;
A dust collector installed downstream of the waste heat boiler;
A heat exchanger that is installed between the waste heat boiler and the dust collector and recovers heat from the boiler exhaust gas discharged after the heat recovery by the waste heat boiler;
A heat storage device connected to the heat exchanger and storing the recovered heat;
Incineration exhaust heat utilization system equipped with. Incineration exhaust heat utilization system according to claim 1,
The incineration waste heat utilization system, wherein the heat exchanger recovers heat from the boiler exhaust gas at 170 to 250 ° C. The incineration exhaust heat utilization system according to claim 1 or 2,
The heat storage device is a direct contact heat storage device that houses a heat storage material used for latent heat storage and mineral oil that exchanges heat by directly contacting the heat storage material, and the mineral oil at 120 to 140 ° C. An incineration exhaust heat utilization system characterized by storing the recovered heat by circulation. The incineration exhaust heat utilization system according to claim 3,
An incineration exhaust heat utilization system, wherein the heat storage material is erythritol. A heat recovery step of recovering heat from a 170 to 250 ° C. boiler exhaust gas discharged from the waste heat boiler by a heat exchanger installed between the waste heat boiler of the incinerator and the dust collector;
A heat storage step of storing the recovered heat in a heat storage device; and
Incineration exhaust heat utilization method comprising. Incineration waste heat utilization method according to claim 5,
The heat storage device is a direct contact heat storage device that houses a heat storage material used for latent heat storage and mineral oil that performs heat exchange by directly contacting the heat storage material,
An incineration exhaust heat utilization method characterized in that, in the heat storage step, the recovered heat is stored by circulating the mineral oil at 120 to 140 ° C. between the heat storage device and the heat exchanger.

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