JP3630542B2 - Thermal storage superheater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention introduces combustion exhaust gas from an incinerator that treats municipal waste and industrial waste to a boiler attached to the incinerator to generate boiler steam, which drives the steam turbine to generate power. It is a regenerative type superheater installed in a waste incineration power plant that is designed to be installed, especially on the downstream side of a dust collector that treats combustion exhaust gas, and discharged from the dust collector to increase power generation efficiency Relating to a regenerative heating system that heats combustion exhaust gas using a heat storage tank and burner, superheats boiler steam by the heated combustion exhaust gas and burner combustion, and thermally decomposes dioxins in the combustion exhaust gas It is.
[0002]
[Prior art]
In general, as a waste incineration power plant that incinerates municipal waste and industrial waste, etc., and uses the incineration waste heat for power generation, municipal waste and industrial waste are burned in a waste incinerator. In addition, the combustion exhaust gas generated by combustion is guided to the boiler to generate boiler steam, and further, the combustion exhaust gas is guided to the economizer to recover heat, and the boiler steam is superheated by the superheater, and this superheated steam is sent to the steam turbine. What is supplied and generated is known.
[0003]
In this waste incineration power plant, in order to increase the power generation efficiency of the steam turbine power generator, the high temperature part (the exit side part of the combustion chamber of the waste incinerator) of the exhaust path of the combustion exhaust gas discharged from the waste incinerator is overheated. A superheater pipe is installed to superheat boiler steam flowing in the superheater pipe with high-temperature combustion exhaust gas.
[0004]
[Problems to be solved by the invention]
By the way, the combustion exhaust gas contains corrosive gas such as HCl and Cl ₂ and low melting point dust. Therefore, when the superheater tube of the superheater is installed in the high temperature part of the exhaust gas exhaust path as described above, the superheater tube is affected by various factors such as corrosive gas and dust in the flue gas and corrodes the superheater tube. Will progress rapidly. That is, a high temperature corrosion phenomenon occurs in the superheated tube. This high temperature corrosion phenomenon occurs remarkably when the temperature of the tube wall of the superheated tube exceeds 320 ° C.
[0005]
Therefore, in the conventional waste incineration power plant, in order to avoid high temperature corrosion of the superheated tube, the superheated steam temperature may be kept low to about 300 ° C so that the surface temperature of the superheated tube is 320 ° C or less. I didn't get it. As a result, the power generation efficiency could not be greatly improved.
[0006]
On the other hand, in addition to the above-described method, as a method of superheating boiler steam to 300 ° C. or higher, a superheat furnace is provided independently from a waste incinerator, and the boiler steam is superheated with a burner provided in the superheat furnace, or from a gas turbine. There are methods such as overheating boiler steam with high-temperature exhaust gas that is discharged, but all of them have a very small track record of adoption due to high fuel consumption and high equipment costs.
[0007]
The present invention has been made in view of such problems, and can cause boiler steam to be superheated with a small amount of burner combustion without causing corrosion in the superheated tube. An object of the present invention is to provide a heat storage type superheater capable of decomposing and removing dioxins contained therein.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a regenerative superheater according to the present invention includes a regenerative superheater installed on the downstream side of a dust collector for treating combustion exhaust gas from an incinerator, and a collection of outside air to the regenerative superheater. It is composed of a gas supply mechanism that can individually supply combustion exhaust gas that has passed through a dust device, and the regenerative heating furnace is formed of a solid heat storage body, and a plurality of heat storage tanks through which external air or combustion exhaust gas can pass A combustion chamber into which external air or combustion exhaust gas that has passed through each heat storage tank is introduced, a superheat pipe that is disposed in the combustion chamber and into which boiler steam is introduced, and is disposed in the combustion chamber. The gas supply mechanism can alternately supply outside air or combustion exhaust gas to some heat storage tanks and the remaining heat storage tanks of the regenerative superheat furnace, and is introduced into the combustion chamber. Outside air or combustion exhaust gas It is characterized in that the gas or combustion exhaust gas is constructed so as to discharge from the heat storage tank is not supplied.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of a regenerative superheater according to an embodiment of the present invention. The regenerative superheater comprises a regenerative superheater 1 and a gas supply mechanism 2, and is composed of municipal waste and industrial waste. Waste incineration power generation in which combustion exhaust gas G from an incinerator that treats waste, etc., is guided to a boiler attached to the incinerator to generate boiler steam S, and a steam turbine is driven by the boiler steam S to generate power Installed in the plant.
[0010]
That is, this heat storage type superheater is installed on the downstream side of the dust collector 3 for processing the combustion exhaust gas G from the incinerator, and the low temperature (180 ° C.) combustion exhaust gas G from the dust collector 3 is about 750 ° C. The regenerative heating furnace 1 is heated up to 1000 ° C., and the gas supply mechanism 2 is capable of supplying outside air A (air) and the combustion exhaust gas G having passed through the dust collector 3 to the regenerative heating furnace 1, respectively. Te cage, the combustion exhaust gas G that has passed through the dust collector 3 is heated by the heat storage tank 5 _1, 5 ₂ and the burner 8 regenerative heating furnace 1, the boiler steam S by the combustion of the combustion gas and the burner 8 the heated In addition to overheating, the dioxins in the combustion exhaust gas G are thermally decomposed.
[0011]
Although not shown, the waste incineration power plant is not shown in the figure, but is a waste incinerator (stoker type incinerator or fluidized bed type incinerator), boiler, steam turbine power generator (consisting of a steam turbine and a generator, etc.), economizer, It consists of a water jet quenching reaction tower, a dust collector 3 and a chimney.
[0012]
The dust collector 3 uses a semi-dry dust collector 3 that can efficiently remove hydrogen chloride, sulfur oxides, dust, heavy metals, and the like. This dust collector 3 is a combination of a reaction tower and a bag filter, and a lime layer is formed on the surface of the bag filter by blowing lime slurry into the reaction tower, through which hydrogen chloride, dust, etc. pass. At this time, hydrogen chloride or the like is absorbed by the lime layer.
[0013]
The regenerative heating furnace 1 is formed of a steel plate or the like, and is formed adjacent to a casing body 4 whose outer surface is covered with a heat insulating material (not shown), and a lower position in the casing body 4, and is used for the outside air A or combustion. Two heat storage tanks 5 ₁ and 5 ₂ through which the exhaust gas G can pass, and a combustion chamber that is formed at an upper position in the casing body 4 and into which the outside air A or the combustion exhaust gas G that has passed through the heat storage tanks 5 ₁ and 5 ₂ is introduced 6, an overheat pipe 7 disposed in the combustion chamber 6 through which the boiler steam S flows, and a burner 8 (oil burner or gas burner) disposed in the combustion chamber 6 for heating the overheat pipe 7 and the combustion exhaust gas G. It is comprised, and is installed in the downstream of the dust collector 3. The temperature efficiency of the regenerative heating furnace 1 is 95%.
[0014]
Further, both the heat storage tanks 5 ₁ and 5 ₂ of the regenerative superheat furnace 1 are formed by filling a lower position in the casing body 4 with a solid heat storage body such as ceramic, stone, or metal. In this embodiment, a solid heat storage body made of ceramic such as alumina or cordierite and having a honeycomb structure is used as the solid heat storage body.
[0015]
Furthermore, one end of the superheat pipe 7 disposed in the combustion chamber 6 is connected to the boiler via the header 9a and the boiler steam supply pipe 10, and the other end of the superheat pipe 7 is connected to the header 9b and the superheated steam. It is connected to the steam turbine of the steam turbine power generator via the supply pipe 11.
[0016]
On the other hand, the gas supply mechanism 2 is connected to the regenerative superheater 1 and the dust collector 3 respectively, and the outside air A or the combustion exhaust gas G is transferred to the two regenerator tanks 5 ₁ and 5 ₂ of the regenerative superheater 1. together may supply respectively alternately, it is configured so as to discharge the outside air a or the combustion exhaust gas G is introduced into the combustion chamber 6 from the outside air a or the combustion exhaust gas G thermal storage tank 5 ₁ is not _supplied, 5 ₂ Yes.
[0017]
Specifically, the gas supply mechanism 2 has one end connected to the dust collector 3 and the other end connected to one (left side) heat storage tank 5 ₁ (hereinafter referred to as the first heat storage tank 5) of the regenerative superheater 1. a first conduit 12 which is connected to _a called), the first end is connected to the other regenerative heating furnace 1 (referred to as thermal storage tank 5 _{2 (hereinafter} the second thermal storage tank 5 ₂ right)) 2 A conduit 13, an exhaust fan 14 connected to the other end of the second conduit 13 and connected to the chimney, a first damper 15 interposed in the first conduit 12, and a second conduit 13. The second damper 16 and one end thereof are connected to the upstream portion of the first conduit 12 upstream of the first damper 15 and the other end thereof is connected to the upstream portion of the second conduit 13 upstream of the second damper 16. The third conduit 17 connected in a branched manner and one end of the third conduit 17 are connected in a branched manner to a portion downstream of the first damper 15 of the first conduit 12. And the other end portion of the second conduit 13 is connected to the downstream side of the second damper 16 in a branched manner, the fourth conduit 18 is interposed in the third conduit 17, and the fourth The fourth damper 20 interposed in the conduit 18 and one end of the first damper 12 are connected to the upstream portion of the portion to which the third conduit 17 of the first conduit 12 is connected, and the other end is opened to the outside air A. The outside air conduit 21, the first outside air switching damper 22 interposed upstream from the portion of the first conduit 12 to which the outside air conduit 21 is connected, and the outside air switching 21 interposed in the outside air conduit 21. The second damper 23 is configured.
[0018]
Each of the dampers of the gas supply mechanism 2 (the first damper 15 to the fourth damper 20, the outside air switching first damper 22 and the outside air switching second damper 23) is a driving device (not shown) including a motor and a cylinder. Is controlled to open and close by controlling the drive with a control device (not shown). In this embodiment, the dampers 15,16,19,20,22,23 is the combustion exhaust gas G from the outside air A or the dust collector 3 a first thermal storage tank _{5 1} second and the heat storage tank _{5 2} to together it is supplied to each alternately, so that it can discharge the outside air a or the combustion exhaust gas G is introduced into the combustion chamber 6 from the outside air a or the combustion exhaust gas G thermal storage tank 5 ₁ is not _supplied, 5 _2, drive device and Open / close control is performed by the control device.
[0019]
Next, the case where the said thermal storage type | mold superheater is drive | operated is demonstrated.
First, as starting preparations for regenerative heating apparatus, both the thermal storage tank 5 _1, 5 ₂ of the solid heat accumulator regenerative heating furnace 1 while passing the superheated tube 7 the boiler steam S generated in a boiler heated by a burner 8, Stores heat in solid heat storage.
[0020]
That is, the first damper 15, the second damper 16, and the outside air switching second damper 23 are opened, and the third damper 19, the fourth damper 20, and the outside air switching first damper 22 are closed, and the exhaust fan in this state. 14 is operated to operate the burner 8.
Then, the outside air A (air), first flows into the heat storage tank 5 ₁ through a portion of the outside air conduit 21 and first conduit 12, it is preheated by solids regenerator while passing through the heat storage tank 5 ₁ flows into the combustion chamber 6, wherein after being heated by the burner 8, applying heat to the solid heat storage body while it flows second to the thermal storage tank 5 ₂ passing therethrough, the second in cooled state It is discharged from the chimney through the conduit 13 and the exhaust fan 14 into the atmosphere.
[0021]
Then, switching the first damper 15 fourth damper 20 after about 2 minutes each switching, the heat storage tank outside air A is introduced from the first thermal storage tank 5 ₁ of the second to the thermal storage tank 5 _2.
[0022]
That is, the first damper 15 and the second damper 16 are closed, and the third damper 19 and the fourth damper 20 are opened.
Then, the outside air A is the ambient air conduit 21, a portion of the first conduit 12, flows through a portion of the third conduit 17 and second conduit 13 to the second thermal storage tank 5 _2, passes through the heat storage tank 5 ₂ is preheated into the combustion chamber 6 by a solid regenerator during, wherein after being heated by the burner 8, a heat to the solid heat storage material during and flows first to the thermal storage tank 5 ₁ passing therethrough Then, in a cooled state, the air is discharged from the chimney to the atmosphere through a part of the first conduit 12, the fourth conduit 18, the part of the second conduit 13, and the exhaust fan 14.
[0023]
In the same manner, it performed by repeating the above operation for about 2 hours, heating the solid heat storage member to a temperature of the top of each thermal storage tank 5 _1, 5 ₂ of the solid heat accumulator is about 800 ° C..
[0024]
In this way, when the temperature of the top of both the thermal storage tank 5 _1, 5 ₂ of the solid heat accumulator is heated to a predetermined temperature, opens the first damper 22 for outside air switching, a second damper 23 for outside air switching The outside air A flowing in the respective conduits 12, 13, 17, 18 is switched to the combustion exhaust gas G from the dust collector 3, and the combustion exhaust gas G discharged from the dust collector 3 is guided to the regenerative superheated furnace 1. Switch the regenerative heating device to normal operation.
[0025]
That is, the first damper 15 and the second damper 16 are opened, and the third damper 19 and the fourth damper 20 are closed.
Then, the combustion exhaust gas G of about 180 ° C. discharged from the dust collector 3, the solid heat storage material is hot while the first flow into the heat storage tank 5 ₁ via the first conduit 12, passing therethrough Is preheated and flows into the combustion chamber 6.
[0026]
The combustion exhaust gas G flowing into the combustion chamber 6 is continuously heated by the burner 8 to become a high-temperature combustion exhaust gas G of about 850 ° C., and the superheated tube 7 is heated to superheat the boiler steam S flowing in the superheated tube 7. . At this time, since the combustion exhaust gas G flowing into the combustion chamber 6 is removed of hydrogen chloride, sulfur oxide, dust, and the like through the dust collector 3, even if it directly contacts the superheater tube 7, Does not cause corrosion. Further, since the combustion exhaust gas G flowing into the combustion chamber 6 is heated to about 850 ° C. by the burner 8, the dioxins in the combustion exhaust gas G are thermally decomposed.
[0027]
Combustion exhaust gas G that has been purified in the combustion chamber 6 is subsequently second flows into the heat storage tank 5 _2, after being chilled to about 220 ° C. by applying heat to the solid heat storage material while passing therethrough, the second conduit 13 and the exhaust fan 14 are discharged from the chimney into the atmosphere. At this time, the combustion exhaust gas G is rapidly cooled to about 220 ° C. while passing through the _second heat storage tank 52 and becomes below the production temperature of dioxins, so that resynthesis of dioxins is prevented.
[0028]
Then, when driving a regenerative superheater about 2 minutes with the above, the subsequent first damper 15 fourth damper 20 respectively switched, the heat storage tank combustion exhaust gas G is introduced from the first thermal storage tank 5 ₁ It switches 2 to the thermal storage tank _{5 2.}
[0029]
That is, the first damper 15 and the second damper 16 are closed, and the third damper 19 and the fourth damper 20 are opened.
Then, the combustion exhaust gas G of about 180 ° C. discharged from the dust collector 3, a portion of the first conduit 12, flows through a portion of the third conduit 17 and second conduit 13 to the second thermal storage tank 5 _2, While passing through this, it is preheated by the solid heat accumulator that is at a high temperature and flows into the combustion chamber 6.
[0030]
The combustion exhaust gas G flowing into the combustion chamber 6 is continuously heated by the burner 8 to become a high-temperature combustion exhaust gas G of about 850 ° C., and the superheated tube 7 is heated to superheat the boiler steam S flowing in the superheated tube 7. . At this time, since the combustion exhaust gas G flowing into the combustion chamber 6 is removed of hydrogen chloride, sulfur oxide, dust, and the like through the dust collector 3, even if it directly contacts the superheater tube 7, Does not cause corrosion. Further, since the combustion exhaust gas G flowing into the combustion chamber 6 is heated to about 850 ° C. by the burner 8, the dioxins in the combustion exhaust gas G are thermally decomposed.
[0031]
Combustion exhaust gas G that has been purified in the combustion chamber 6 will continue first flows into the heat storage tank 5 _1, after being chilled to about 220 ° C. by applying heat to the solid heat storage material while passing therethrough, the first conduit 12, the fourth conduit 18, the second conduit 13, and the exhaust fan 14, and then discharged from the chimney to the atmosphere. At this time, the combustion exhaust gas G is rapidly cooled to about 220 ° C. while passing through the _first heat storage tank 51 and becomes below the production temperature of dioxins, so that resynthesis of dioxins is prevented.
[0032]
On the other hand, the boiler steam S of about 270 ° C. supplied from the boiler steam supply pipe 10 to the superheat pipe 7 is overheated by the combustion exhaust gas G from which the burner 8 is burned and from which hydrogen chloride, sulfur oxide, dust, and the like are removed. after a superheated steam S ₁ of 450 ° C., thereby performing the power generation is supplied from the superheated steam feed pipe 11 to the steam turbine. Accordingly, high temperature / high pressure steam can be obtained without causing the problem of high temperature corrosion in the superheated tube 7, and the power generation efficiency can be greatly improved.
[0033]
Similarly, the first damper 15 and the second damper 16 and the third damper 19 and the fourth damper 20 are alternately switched at regular intervals (approximately every 2 minutes) to burn from the dust collector 3. the exhaust gas G to the first thermal storage tank 5 ₁ and the second thermal storage tank 5 ₂ continue to supply alternately to continue the operation of the regenerative superheater.
[0034]
The amount of fuel consumed by the heat storage type superheater is such that the amount of fuel and the combustion exhaust gas G required to heat the superheater tube 7 to change the boiler steam S at 270 ° C. to superheated steam S ₁ at 450 ° C. are 850 ° C.-800 ° C. = Total amount of fuel required to heat at 50 ° C.
Moreover, when this heat storage type superheater was used, the concentration of dioxins could be reduced from about 0.5 ng-TEQ / Nm ³ (O ₂ = 12% conversion) to 0.1 ng-TEQ / Nm ³ or less. .
Furthermore, this heat storage type superheater has the same amount of fuel required to change the boiler steam S at 270 ° C. to superheated steam S ₁ at 450 ° C. when compared with a direct combustion type steam superheat furnace without a heat storage tank. However, the amount of fuel required to heat the combustion exhaust gas G is about one-third that of a direct combustion steam superheated furnace without a heat storage tank. In other words, this heat storage type superheater uses significantly less fuel.
In addition, this regenerative superheater sets the combustion exhaust gas G discharged from the regenerative superheater 1 to about 220 ° C., and is about 40 ° C. higher than the temperature of the combustion exhaust gas G discharged from the dust collector 3 (about 180 ° C.). Since the temperature was raised, the white smoke from the chimney could be prevented.
[0035]
In the above embodiment, two heat storage tanks 5 ₁ and 5 ₂ are formed in the regenerative superheated furnace 1, but in the other embodiments, three regenerative superheated furnaces 1 are provided. You may make it form the above heat storage tank.
[0036]
In the above embodiment, the solid heat storage body forming both the heat storage tanks 5 ₁ and 5 ₂ is made of ceramic and has a honeycomb structure, but the solid heat storage body is made of a material having a large heat capacity. It can be anything. For example, the solid heat accumulator may be made of metal or stone, or may be used in combination with different materials.
[0037]
In the above embodiment, the dampers 15, 16, 19, 20, 22, and 23 are provided in the respective conduits 12, 13, 17, 18, and 21 of the gas supply mechanism 2. In this embodiment, instead of the dampers 15, 16, 19, 20, 22, 23, rotary switching valves (not shown) are provided in the respective conduits 12, 13, 17, 18, 21 of the gas supply mechanism 2. You may make it interpose.
[0038]
In the above embodiment, the outside air A and the combustion exhaust gas G are sucked by the exhaust fan 14 and supplied to the regenerative superheated furnace 1, but in the other embodiments, the regenerative type is used. A pushing fan (not shown) may be provided on the upstream side of the superheating furnace 1 so that the outside air A and the combustion exhaust gas G are supplied to the regenerative superheating furnace 1 by the pushing fan.
[0039]
In the above-described embodiment, the supply / discharge line for the outside air A and the supply / discharge line for the combustion exhaust gas G are partially shared. However, in the other embodiments, the supply / discharge of the outside air A is performed. A line and a supply / discharge line for the combustion exhaust gas G may be provided independently.
[0040]
【The invention's effect】
As described above, the regenerative superheater of the present invention is a regenerative superheater equipped with a heat accumulator, a combustion chamber, a superheater tube, and a burner, from which hydrogen chloride, dust, etc. discharged from the dust collector have been removed. And heated by a heat storage tank and a burner, and the superheated tube is heated by the heated combustion exhaust gas and the burner.
In other words, this thermal storage superheater is designed to superheat the superheater tube with high-temperature combustion exhaust gas from which hydrogen chloride, dust, etc. have been removed, so that high-temperature and high-pressure superheated steam can be produced without causing high-temperature corrosion in the superheater tube. The power generation efficiency can be greatly improved.
Further, since the combustion exhaust gas is preheated by the heat storage tank and then heated by the burner, the fuel consumption of the burner can be greatly reduced, and superheated steam can be obtained with a small amount of burner combustion.
Furthermore, since the combustion exhaust gas is heated in the combustion chamber, dioxins in the combustion exhaust gas can be thermally decomposed, and the dioxins can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a schematic system diagram of a heat storage type superheater according to an embodiment of the present invention.
[Explanation of symbols]
1 is a regenerative superheater, 2 is a regenerative superheater, 3 is a dust collector, 5 ₁ and 5 ₂ are heat storage tanks, 6 is a combustion chamber, 7 is a superheat pipe, 8 is a burner, A is outside air, and G is combusting Exhaust gas, 8 is boiler steam.

Claims (1)

A regenerator superheater (1) installed downstream of the dust collector (3) that processes the combustion exhaust gas (G) from the incinerator, and the outside air (A) and the dust collector to the regenerator superheater (1) A regenerative superheater comprising a gas supply mechanism (2) capable of independently supplying combustion exhaust gas (G) having passed through (3), wherein the regenerative superheater (1) is a solid regenerator. A plurality of heat storage tanks (5 ₁ ), through which the outside air (A) or combustion exhaust gas (G) is formed, and the outside air (A) or combustion exhaust gas (G) that has passed through each of the heat storage tanks (5 ₁ ),. ) Are introduced into the combustion chamber (6), the combustion chamber (6), the superheat pipe (7) into which the boiler steam (S) is introduced, and the combustion chamber (6). (7) and a burner (8) that heats the combustion exhaust gas (G), and the gas supply mechanism (2) Can alternately supply the combustion exhaust gas (G) to a part of the heat storage tanks and the remaining heat storage tanks of the regenerative heating furnace (1), and the outside air (A) introduced into the combustion chamber (6) or A heat storage type superheater configured to be able to discharge combustion exhaust gas (G) from a heat storage tank not supplied with outside air (A) or combustion exhaust gas (G).

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