JP3828366B2 - Regenerative heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a regenerative heat exchanger used in a waste incineration power plant that incinerates garbage such as municipal waste and industrial waste and uses the incineration waste heat for power generation.
[0002]
[Prior art]
Conventionally, this kind of waste incineration power plant has incinerated municipal waste and industrial waste with an incinerator, and the exhaust gas generated by incineration is led to a boiler attached to the incinerator to generate steam. It is known that power is generated by driving a generator via a turbine using this steam.
[0003]
Thus, in order to increase the power generation efficiency, such a waste incineration power plant is connected to the high temperature portion of the discharge path of the exhaust gas A discharged from the incinerator 50, that is, the outlet side of the incinerator 50, as shown in FIG. A metal superheater 52 is installed in the exhaust gas duct 51, and heat exchange is performed between the steam B flowing in the superheat pipe and the high-temperature exhaust gas A so that the steam B is superheated. Yes. In FIG. 3, 53 indicates a dust discharge device, and 54 indicates a secondary air blower.
[0004]
[Problems to be solved by the invention]
However, such a thing can only raise the steam temperature up to about 400 ° C due to the problem of high temperature corrosion of the superheater due to the dust containing acid gas and salt generated with incineration of waste, The power generation efficiency remained at around 20%.
[0005]
The present invention has been devised to solve this problem in view of the above-mentioned problems, and the problem is that a heat storage type that can suppress corrosion of the superheater and still improve power generation efficiency. To provide a heat exchanger.
[0006]
[Means for Solving the Problems]
The heat storage heat exchanger according to the present invention includes an exhaust gas duct through which exhaust gas flows, a pipe provided through the exhaust gas duct in a vertical direction, and a heat exchange between the pipe and the exhaust gas that is filled in a flowable manner. It is characterized in that it is composed of granules to be performed, a superheater that is provided at the bottom of the pipe and superheats the steam by the granules after heat exchange, and a circulation means for returning the granules after overheating to the top of the pipe Exist.
[0007]
The particles filled in the pipe in a flowable manner undergo heat exchange with the exhaust gas flowing through the exhaust gas duct via the pipe. The steam flowing in the superheater tube of the superheater is heated by the granules after heat exchange. The particles after the steam overheating are returned to the upper part of the pipe by the circulation means. And these things are repeated.
Since the superheater does not come into direct contact with the exhaust gas flowing through the exhaust gas duct, high temperature corrosion due to this does not occur. For this reason, the superheat temperature of the steam depending on the superheater can be increased, and the power generation efficiency due to this steam can be greatly improved.
[0008]
It is preferable to provide a high-temperature dust remover for removing dust in the exhaust gas in the exhaust gas duct upstream of the pipe. In this way, dust in the exhaust gas can be removed, dust can be prevented from adhering to the pipe, and the subsequent heat exchange efficiency can be improved.
[0009]
The pipe is made of ceramic, and the particles are preferably ceramic particles such as cinnabar or alumina having a particle size of 10 to 1000 μm. In this way, the pipe is not corroded at high temperature due to the exhaust gas, and the fluidity and heat transferability of the particles are enhanced, so that efficient heat exchange can be performed.
[0010]
The circulating means is preferably an air transport system that transports the particles by air, collects air containing the transported particles, and returns the collected particles to the pipe. In this way, the particles can be transferred relatively easily and reliably.
[0011]
The transport air is preferably used as combustion air (primary air or secondary air) in an incinerator. In this way, the heated transportation air can be used as it is as combustion air for the incinerator, which is extremely reasonable.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an incinerator equipped with a heat storage type heat exchanger according to the present invention. FIG. 2 is an enlarged schematic view showing a heat storage type heat exchanger.
[0013]
The main part of the heat storage heat exchanger 1 is composed of an exhaust gas duct 2, a pipe 3, a granule 4, a superheater 5, and a circulation means 6.
[0014]
The exhaust gas duct 2 is used for the exhaust gas A to flow therethrough. In this example, the exhaust gas duct 2 is connected to the outlet side of the incinerator 20, and the exhaust gas A generated at the incinerator 20 at 750 to 800 ° C. is passed therethrough.
[0015]
The pipe 3 is provided through the exhaust gas duct 2 in the vertical direction. In this example, the pipe 3 is made of ceramic, and a plurality of pipes having a diameter of 100 to 200 mm are provided to form a so-called pipe group. A funnel-shaped lower reservoir 7 is provided at the lower part of each pipe 3 so as to communicate therewith.
[0016]
The granule 4 is filled in the pipe 3 so as to be flowable and exchanges heat with the exhaust gas A. In this example, the granule 4 is made of dredged sand having a particle size of 10 to 1000 μm, preferably 100 to 200 μm. When the particle size is smaller than 10 μm, the handling property is deteriorated, and when the particle size is larger than 1000 μm, the fluidity is deteriorated.
[0017]
The superheater 5 is provided at the lower part of the pipe 3 and superheats the steam B by the particles 4 after heat exchange. In this example, the superheater 5 is provided in the lower reservoir 7 provided at the lower part of the pipe 3. Is provided.
[0018]
The circulation means 6 returns the particles 4 after steam overheating to the upper part of the pipe 3. In this example, the circulation means 6 is an air transport system in which the particles 4 are transported by the air C, and the air C including the transported particles 4 is removed. While collecting the dust and returning the collected particles 4 to the pipe 3, the transport air C is used as combustion air in the incinerator 20.
[0019]
In other words, the circulation means 6 is connected to the lower part of the lower reservoir 7 and discharges the granules 4 stored therein, and the blower that supplies air C to the granules 4 discharged therefrom. 9, an air transport pipe 10 that transports the granule 4 by the air C in the future, a separator 11 that separates the air C and the granule 4 from now on, and an upper part of each pipe 3. It consists of an upper distribution tank 12 that distributes the granules 4 from the separator 11 to each pipe 3, and a bubbling air pipe 13 that is provided in this pipe and fluidizes and homogenizes the granules 4 inside. Yes.
[0020]
The screw feeder 8 is cooled by a low-pressure steam or air. As the separator 11, a multi-cyclone or a ceramic filter is used. The transportation air C separated by the separator 11 is supplied to the discharge side of the secondary air blower 21 via the pipe 14 and used as secondary air (combustion air) of the incinerator 20. . Although not shown, the bubbling air pipe 13 is connected to an air supply source.
In FIG. 1, reference numeral 22 denotes a primary air blower.
[0021]
Next, the operation will be described based on such a configuration.
The exhaust gas A generated in the incinerator 20 of the garbage incineration power plant is discharged by the exhaust gas duct 2 and passes through the pipe 3 group of the regenerative heat exchanger 1 on the way.
The particles 4 filled in the pipes 3 so as to be flowable are subjected to heat exchange with the exhaust gas A through the pipes 3. The exhaust gas A is about 750 to 800 ° C. before heat exchange, and is about 650 to 700 ° C. after heat exchange.
The granules 4 after heat exchange are stored in the lower storage tank 7. And the vapor | steam B which flows through the inside of the superheater pipe | tube of the superheater 5 provided in the lower storage tank 7 is overheated by the granule 4 after heat exchange.
[0022]
Since the granule 4 is not corrosive and no corrosive components are mixed from the outside depending on the pipe 3, the steam temperature can be overheated to about 500 ° C., and the power generation efficiency is about 27 to 28%. Can be raised.
The overheated granule 4 stored in the lower storage tank 7 is discharged by the screw feeder 8 of the circulation means 6 and separated through the air transport pipe 10 by the pressurized air C from the blower 9 at an appropriate time. It is transported to the vessel 11. At this time, the flow velocity in the air transport pipe 10 is approximately 1 to 10 m / s and is appropriately adjusted depending on the properties of the particles 4. The air C and the granules 4 sent to the separator 11 are separated here, and the granules 4 are dropped into the upper distribution tank 12 below. The granules 4 sent to the upper distribution tank 12 are fluidized by the air from the bubbling air pipe 13 and are evenly distributed to the upper part of each pipe 3.
Since the granule 4 is circulated by the circulation means 6, only the initial charging is required.
[0023]
Since the transportation air C separated by the separator 11 is heated by the granule 4, it is sent to the discharge side of the secondary air blower 21 by the pipe 14 and used as the secondary air of the incinerator 20. Is done.
[0024]
Next, a second example of the present invention will be described.
In the second example, a high temperature dust remover 15 for removing the exhaust gas A is provided at a position upstream of the pipe 3 of the exhaust gas duct 2 as indicated by a chain line in FIG. A ceramic filter or the like is used as the high temperature dust remover 15. In this way, dust contained in the exhaust gas A from the incinerator 20 can be removed by the high temperature dust remover 15, and dust does not adhere to the pipe 3. For this reason, the heat exchange efficiency is greatly improved.
[0025]
In the above example, the number of pipes 3 is plural. However, the number of pipes 3 is not limited to this.
In the previous example, the granule 4 was cinnabar sand, but is not limited thereto, and may be, for example, limestone.
The air C after transport is used as the secondary air of the incinerator 20 in the previous example, but is not limited thereto, and may be used as the primary air of the incinerator 20, for example.
[0026]
【The invention's effect】
As described above, according to the present invention, the following excellent effects can be obtained.
(1) Consists of exhaust gas ducts, pipes, granules, superheater, and circulation means. In particular, heat exchange is performed between exhaust gas and granules via pipes, and superheaters depend on the granules after heat exchange. Since the steam flowing through is overheated, the corrosion of the superheater can be suppressed and the power generation efficiency can be improved.
(2) Since a circulating means for returning the heated granule to the upper part of the pipe is provided, the granule can be reused and only the initial charging is required.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an incinerator equipped with a heat storage type heat exchanger according to the present invention.
FIG. 2 is an enlarged schematic diagram showing a heat storage type heat exchanger.
FIG. 3 is a schematic diagram showing a conventional incinerator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Thermal storage type heat exchanger, 2,51 ... Exhaust gas duct, 3 ... Pipe, 4 ... Granule, 5,52 ... Superheater, 6 ... Circulation means, 7 ... Lower storage tank, 8 ... Screw feeder, 9 ... Blower DESCRIPTION OF SYMBOLS 10 ... Air transport pipe, 11 ... Separator, 12 ... Upper distribution tank, 13 ... Air piping for bubbling, 14 ... Piping, 15 ... High temperature dust remover, 20, 50 ... Incinerator, 21, 54 ... Secondary air blower 22 ... primary air blower, 50 ... incinerator, 53 ... dust discharge device, A ... exhaust gas, B ... steam, C ... air for transportation.

Claims (3)

An exhaust gas duct through which the exhaust gas flows, a pipe provided vertically through the exhaust gas duct, a granule that is filled in the pipe in a flowable manner and exchanges heat with the exhaust gas, and a lower part of the pipe A superheater that superheats the steam by the granules after heat exchange and a circulating means for returning the superheated granules to the upper part of the pipe, and the circulating means is air that transports the granules by air Regenerative heat that is characterized by the fact that the air containing the transported particles is collected, the collected particles are returned to the pipe, and the transport air is used as combustion air for the incinerator. Exchanger.   The regenerative heat exchanger according to claim 1, wherein a high-temperature dust remover for removing dust in the exhaust gas is provided at a position upstream of the pipe of the exhaust gas duct.   The heat storage heat exchanger according to claim 1 or 2, wherein the pipe is made of ceramic, and the particles are ceramic particles such as cinnabar or alumina having a particle size of 10 to 1000 µm.

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