JP5974126B1 - Energy recovery equipment and waste incineration equipment - Google Patents

Abstract

An energy recovery apparatus capable of obtaining high-temperature steam while suppressing the use of a heat transfer tube made of a special material is provided, and a waste incineration facility that facilitates efficient energy recovery is provided. SOLUTION: One or two or more heat transfer tubes extending in a direction intersecting with a flow direction of exhaust gas are provided in an exhaust gas flow channel through which exhaust gas obtained by burning waste by a fluidized bed gasification melting furnace flows. The superheater 22 was provided and water vapor of 450 ° C. or higher was passed through the superheater, and the exhaust gas was configured to have an average temperature of 550 ° C. or lower and an average flow velocity of 3.0 m / s or lower. [Selection] Figure 1

Description

  The present invention relates to an energy recovery device and a waste incineration facility. More specifically, the present invention relates to an energy recovery device that recovers heat from exhaust gas discharged from a fluidized bed combustion furnace or a fluidized bed gasification and melting furnace that combusts waste, and this The present invention relates to a waste incineration facility provided with such an energy recovery device together with a fluidized bed combustion furnace or a fluidized bed gasification melting furnace.

Conventionally, most waste such as municipal waste is disposed of by landfill or incineration.
In addition, when incinerating a waste containing a combustible organic substance, conventionally, disposal by a stalker furnace, a fluidized bed type combustion furnace, or a fluidized bed type gasification melting furnace has been performed (the following Non-Patent Document 1). reference).
In recent years, waste incineration facilities where waste is incinerated have been required to supply thermal energy and electric energy to the surrounding area in addition to the function of processing waste. Heat recovery from exhaust gas from combustion furnaces has been performed by boilers equipped with a super heater.

A heat recovery apparatus such as a boiler attached to such a waste combustion furnace is generally more effective in effectively utilizing the recovered heat if it can increase the temperature and pressure of water vapor.
However, with such a boiler, for example, if high temperature steam exceeding 400 ° C. is to be obtained, the heat transfer tubes constituting the super heater may be in a high temperature state in the exhaust gas.
And as shown in the following patent document 1 (for example, refer to paragraph 0003 etc.), the heat exchanger tube of a high temperature state is easy to be corroded by the hydrogen chloride etc. which are contained in waste gas.

JP 09-159132 A

“High-temperature corrosion of waste incinerator boiler” Kenichi Yukawa, Research and Development Center for Metallic Materials, “Corrosion and Corrosion Protection Association”, “Materials and Environment” 1997-Vol. 46No. 1 (pages 3-7)

From the above, when trying to obtain high-temperature steam, unless a heat transfer tube made of a special material is used, the lifetime of the super heater may be extremely shortened.
That is, the conventional energy recovery apparatus has a problem that it is difficult to obtain high-temperature steam without using a heat transfer tube made of a special material.
In addition, for this reason, it is difficult to recover energy efficiently in conventional waste incineration facilities.

  The present invention has been made in view of the above problems, and provides an energy recovery device capable of obtaining high-temperature steam while suppressing the use of a heat transfer tube made of a special material, and efficiently recovers energy. It is an object to provide a waste incineration facility that is easy to perform.

  As a result of intensive studies by the inventor in order to solve the above problems, exhaust gas generated from a fluidized bed combustion furnace or fluidized bed gasification and melting furnace is usually corrosive compared to exhaust gas discharged from a stalker furnace or the like. The present invention has been completed by finding that the corrosion of the heat transfer tube is suppressed by bringing the exhaust gas having low and high corrosivity into contact with the exhaust gas having low corrosivity under specific conditions.

  That is, an energy recovery apparatus according to the present invention for solving the above-described problem is an exhaust gas passage through which exhaust gas obtained by burning waste by a fluidized bed combustion furnace or a fluidized bed gasification and melting furnace flows. A super heater having one or more heat transfer tubes provided in the exhaust gas flow path and extending in a direction crossing the flow direction of the exhaust gas, and recovering heat from the exhaust gas by water vapor flowing through the heat transfer tubes. It is an energy recovery apparatus to be performed, wherein the super heater has the heat transfer tube through which water vapor of 450 ° C. or higher flows, and the exhaust gas flowing through the exhaust gas flow path has the heat transfer tube through which water vapor of 450 ° C. or higher flows. The average temperature at the position where is arranged is 550 ° C. or less, and the average flow velocity is 3.0 m / s or less.

  Moreover, the waste incineration equipment according to the present invention for solving the above problems includes a fluidized bed combustion furnace or a fluidized bed type gasification melting furnace for burning waste, the fluidized bed type combustion furnace or the fluidized bed type. A waste incineration facility comprising an energy recovery device for recovering heat from exhaust gas discharged from a gasification melting furnace, wherein the energy recovery device is provided in the exhaust gas channel through which the exhaust gas flows, and in the exhaust gas channel And a super heater having one or more heat transfer tubes extending in a direction intersecting with the flow direction of the exhaust gas, and recovering heat from the exhaust gas with water vapor circulated in the heat transfer tube, In addition, the super heater has the heat transfer tube through which water vapor of 450 ° C. or higher flows, and the exhaust gas flowing through the exhaust gas flow path is provided with the heat transfer tube through which water vapor of 450 ° C. or higher flows. It is characterized in that the average temperature is the average flow velocity at 550 ° C. or less of the exhaust gas at the position is not more than 3.0 m / s.

ADVANTAGE OF THE INVENTION According to this invention, since the corrosion by the exhaust gas of the heat exchanger tube which distribute | circulates high temperature steam is suppressed, the heat recovery apparatus which can obtain high temperature steam can be provided, suppressing use of the heat exchanger tube of a special material. .
Moreover, according to this invention, the waste incineration equipment which can perform energy recovery efficiently can be provided.

The block diagram which shows schematic structure of the waste incineration equipment which concerns on one Embodiment of this invention. The schematic arrangement figure which showed an example of arrangement | positioning of the heat exchanger tube in an exhaust gas flow path. The graph which shows the result of having evaluated the thinning of the steel pipe in the actual waste incineration equipment.

Below, embodiment which concerns on the waste incineration equipment of this invention is described.
First, as shown in FIG. 1, the waste incineration facility 1 of the present embodiment is discharged from a fluidized bed gasification melting furnace 10 for burning waste and the fluidized bed gasification melting furnace 10. And an energy recovery device 20 that recovers heat from the exhaust gas.
In addition, the waste incineration facility 1 of the present embodiment uses the temperature reducing tower 30 for further lowering the temperature of the exhaust gas after heat recovery by the energy recovery device 20 and the exhaust gas after passing through the temperature reducing tower 30. A bug filter 40 for removing fly ash contained therein is further provided.

The fluidized bed gasification melting furnace 10 of the present embodiment introduces the waste A, pyrolyzes the organic matter contained in the waste A, and discharges the exhaust gas B containing a flammable gas, and the waste A Is contained in the exhaust gas B inside by introducing the exhaust gas B exhausted from the gasification furnace 11 and the exhaust gas B exhausted from the gasification furnace 11. And a melting furnace 12 that discharges the ash contained in the exhaust gas B as molten slag D.
The waste incineration facility 1 of the present embodiment is configured to supply the exhaust gas E discharged from the melting furnace 12 to the energy recovery device 20 before dust removal with a bag filter or the like, and the exhaust gas E is directly recovered by energy recovery. It is configured to be supplied to the device 20.

  In the following, the exhaust gas E discharged from the melting furnace 12 is referred to as “second exhaust gas”, and the exhaust gas B discharged from the gasification furnace 11 to the melting furnace 12 is referred to as “first exhaust gas”. There is a division.

The gasification furnace 11 is provided with a fluidized bed (not shown) in which a fluid medium such as silica sand is deposited, and when the fluidized bed is fluidized, a gas containing oxygen such as air is supplied to the furnace. It is configured to be supplied from the bottom.
In the gasification furnace 11, for example, combustible waste as waste A is introduced, and the combustible waste is partially burned at a temperature of 450 to 600 ° C. in a fluidized bed fluidized by combustion air supplied from the bottom of the furnace. To be used.
In such an operation state, char including ash and carbonized solids and combustible gas are generated in the gasifier 11 by gasification of the waste A.
These combustible gases and char are sent from the gasification furnace 11 to the melting furnace 12 in a form contained in the first exhaust gas B.

For example, silica sand having an average particle diameter of 0.5 mm to 1.0 mm is circulated and supplied to the fluidized bed of the gasification furnace 11 as the fluidized medium.
The incombustible material C in the waste is discharged from the lower part of the furnace together with the silica sand, the discharged incombustible material and the silica sand are separated by a classifier or the like, and the separated silica sand is supplied again to the fluidized bed.

In the melting furnace 12, the combustible gas contained in the first exhaust gas B sent from the gasifier 11 is burned by combustion air supplied separately, and the carbon in the char is combusted with the combustion of the combustible gas. Minutes are also burned.
In the melting furnace 12, the temperature in the furnace becomes a high temperature of, for example, 1250 ° C. to 1350 ° C. due to the heat generated by the combustion, so that the ash content in the char is melted.

Then, the molten ash becomes molten slag D and is discharged from a spout (not shown) provided at the bottom of the melting furnace 12, and then rapidly cooled by cooling water and solidified.
The second exhaust gas E discharged from the melting furnace 12 is heat recovered by the energy recovery device 20 and reduced in temperature, then processed by the temperature reducing tower 30 and the bag filter 40 and discharged outside the system. The

The energy recovery apparatus 20 in the present embodiment has a boiler flue 21 as an exhaust gas passage through which the second exhaust gas E circulates.
In the following, the upstream side in the flow direction of the second exhaust gas E in the boiler flue 21 is referred to as “upstream side” or “front side”, and the downstream side in the flow direction of the second exhaust gas E in the boiler flue 21 is referred to as “downstream”. May be referred to as “side” or “back side”.

The energy recovery apparatus 20 in the present embodiment includes a super heater configured by one or more heat transfer tubes provided in the boiler flue.
The heat transfer tube is for transferring the heat of the second exhaust gas E flowing through the boiler flue 21 to the water vapor flowing through the heat transfer tube to obtain high-temperature and high-pressure water vapor. General-purpose products such as stainless steel pipes made of materials such as “SUS309S” and “SUS310S” and “STBA12” which is a low alloy steel pipe material for general boilers can be adopted.
That is, as the heat transfer tube of the present embodiment, a tube formed of general-purpose steel such as “SUS309S”, “SUS310S”, or low alloy steel can be adopted.

The energy recovery apparatus 20 in the present embodiment has a super heater 22a including a heat transfer tube through which water vapor of 450 ° C. or higher flows, and further includes two super heaters 22b and 22c in addition to the super heater.
One of the three super heaters (hereinafter “first super heater 22a”) is for obtaining water vapor at 450 ° C. or higher.
In the energy recovery device 20 of the present embodiment, another superheater (hereinafter referred to as “second superheater 22b”) is disposed on the upstream side of the first superheater 22a and downstream of the first superheater 22a. Another super heater (hereinafter, “third super heater 22c”) is also disposed on the side.
These super heaters 22a, 22b, and 22c are provided in the energy recovery device 20 in a state where the flow paths of water vapor are connected to each other.

  The energy recovery device 20 of the present embodiment is a device for heating water introduced from outside the system by exhaust gas downstream of the third super heater 22c as a device for preheating water vapor supplied to the super heater. It further comprises a charcoal unit 23, a boiler drum 24 for separating water into steam, and an evaporator 25 for heating the water flowing down from the boiler drum 24 and returning it to the boiler drum 24 as steam. Yes.

  In the energy recovery apparatus 20 of the present embodiment, the saturated steam obtained by the boiler drum 24 is supplied to the third super heater 22c to become superheated steam, and then this superheated steam is used as the second super heater 22b and the first super heater. It moves in order of the heater 22a, and it is comprised so that water vapor | steam of 450 degreeC or more may be finally obtained in this 1st super heater 22a.

FIG. 2 is a schematic arrangement diagram showing the arrangement of the heat transfer tubes constituting the three super heaters in the boiler flue, and the boiler flue 21 and the super heaters 22a, 22b, The state which looked at the cross section which cut | disconnected 22c from the direction shown by the block arrow Y of FIG. 1 is shown.
As shown in this figure, all the heat transfer tubes constituting the super heaters 22a, 22b, and 22c of the present embodiment have a common extending direction, and the flow direction of the exhaust gas (FIG. 2). Extending in a direction intersecting the arrow Z).
More specifically, all the heat transfer tubes are arranged in the boiler flue so as to be substantially orthogonal to the flow direction Z of the exhaust gas.
Each super heater is composed of a total of 24 heat transfer tubes, six in the length direction (exhaust gas distribution direction) of the boiler flue 21 and four in the width direction. They are arranged in an aligned state in the length direction.
Furthermore, the energy recovery device 20 of the present embodiment includes the most downstream heat transfer tube b6 of the second super heater 22b and the most upstream heat transfer tube of the first super heater 22a arranged on the most upstream side of the boiler flue 20. a1 is aligned in the length direction of the boiler flue 21, and the most downstream heat transfer tube a6 of the first super heater 22a and the most upstream heat transfer tube c1 of the third super heater 22c are in the boiler flue 21. The heat transfer tubes are arranged so as to be aligned in the length direction.

Each super heater is configured to circulate water vapor from the upstream side to the downstream side or from the downstream side to the upstream side inside the heat transfer tubes arranged in alignment in the width direction and the length direction. The steam is configured to be able to be heated by heat exchange with the exhaust gas, and is configured to circulate steam at substantially the same temperature through the heat transfer tubes adjacent in the width direction.
The energy recovery device 20 of the present embodiment supplies the steam supplied from the boiler drum 24 to the most downstream (sixth) heat transfer pipe c6 of the third super heater 22c, and this steam is sent to the boiler flue upstream. The fifth heat transfer tube c5 and the fourth heat transfer tube c4 are sequentially moved and heated to discharge from the most upstream heat transfer tube c1, and then the steam is transferred to the most upstream side of the second super heater 22b. The steam is introduced into the heat pipe b1, and this water vapor is sequentially moved to the downstream heat transfer pipe b2 and further to the downstream heat transfer pipe b3 for heating, and the most downstream heat transfer pipe in the second super heater 22b. It is used to discharge from b6 as steam having a high temperature.
In addition, the energy recovery device 20 of the present embodiment is configured such that, for example, 380 ° C. steam discharged from the most downstream heat transfer tube b6 of the second super heater 22b is located on the downstream side of the first super heater 22a. Is introduced into the most downstream heat transfer tube a6, and the water vapor is sequentially moved to one upstream heat transfer tube a5 and further one upstream heat transfer tube a4 of the heat transfer tube a6 to be heated. It is used to take out water vapor at 450 ° C. or higher from the most upstream heat transfer tube a1 of the first super heater 22a.

And the energy recovery apparatus 20 of this embodiment normally distribute | circulates 400 degreeC or more water vapor | steam in the 3-4th heat exchanger tubes a1-a3 (a1-a4) from the upstream of the 1st super heater 22a.
Further, the energy recovery device 20 of the present embodiment normally has a surface of the heat transfer tube a1 (hereinafter also referred to as “final heat transfer tube”) through which water vapor of 450 ° C. or higher flows during operation for recovering heat from exhaust gas. The temperature is the highest among all the heat transfer tubes arranged in the boiler flue.
The surface temperature of the heat transfer tube is preferably 520 ° C. or less, more preferably 500 ° C. or less, and more preferably 480 ° C. or less, in order to prevent the heat transfer tube from being corroded by the second exhaust gas. It is particularly preferred.
The surface temperature of the heat transfer tube can be obtained, for example, by performing heat transfer calculation from the exhaust gas temperature around the heat transfer tube and the steam temperature in the heat transfer tube, and various coefficients necessary for the heat transfer calculation are “German FDBR”. Values described in “Handbook” and “Thermophysical property collection of fluids edited by the Japan Society of Mechanical Engineers” can be adopted.

And in order to make the surface temperature of the last heat exchanger tube a1 into the above temperature, the said 2nd waste gas which flows through the inside of the said boiler flue is the average temperature (550 degrees C or less) in the position where this last heat exchanger tube a1 was distribute | arranged ( Daily average temperature), and an average flow velocity (daily average flow velocity) of 3.0 m / s or less is preferable.
Moreover, in order to exhibit the effect which suppresses that the last heat exchanger tube a1 corrodes more notably, the average temperature of the 2nd waste gas in the position where the said last heat exchanger tube a1 was arrange | positioned is 540 degrees C or less. The temperature is preferably 530 ° C. or lower.
The average flow rate of the second exhaust gas at the position where the final heat transfer tube a1 is disposed is preferably 2.5 m / s or less, and preferably 2.0 m / s or less.
If the average temperature of the second exhaust gas at the position where the final heat transfer tube a1 is disposed is excessively lowered, or the average flow rate of the second exhaust gas is excessively decreased, water vapor of 450 ° C. or higher is obtained. For this reason, there is a risk that the overall scale of the energy recovery device 20 may be excessive.
Therefore, the average temperature of the second exhaust gas at the position where the final heat transfer tube a1 is disposed is preferably 460 ° C or higher, more preferably 470 ° C or higher, and particularly preferably 480 ° C or higher. preferable.
The average flow velocity of the second exhaust gas at the position where the final heat transfer tube a1 is disposed is preferably 1.2 m / s or more, more preferably 1.4 m / s or more. It is particularly preferably 6 m / s or more.

In addition, if the second exhaust gas has an average temperature and flow rate as described above, there is a low risk of corroding the final heat transfer tube a1, but even if temporarily the temperature and flow rate become excessively high. There is a possibility that the surface temperature of the final heat transfer tube a1 is raised to make the final heat transfer tube a1 susceptible to corrosion.
Therefore, the maximum temperature of the second exhaust gas during the operation period of the energy recovery device 20 is preferably 660 ° C. or less, and more preferably 650 ° C. or less.
Further, the maximum flow velocity of the second exhaust gas during the operation period of the energy recovery device 20 is preferably 5.0 m / s or less, and more preferably 3.0 m / s or less.
And the highest ultimate temperature on the surface of the final heat exchanger tube during the operation period of the energy recovery apparatus 20 is preferably 580 ° C. or less, and more preferably 570 ° C. or less.
In addition, when the total operation days of the energy recovery device 20 are 100%, the total number of days that the second exhaust gas exceeds the above average temperature and average flow rate is preferably 40% or less, and 30% The following is more preferable.

  The temperature of the second exhaust gas can be obtained by inserting a sheath thermocouple into the boiler flue. The flow rate of the second exhaust gas can be obtained from the superficial velocity, and can be obtained by dividing the exhaust gas flow rate per unit time by the cross-sectional area of the boiler flue 21.

Here, the temperature of the second exhaust gas at the position where the final heat transfer tube a1 is arranged is adjusted by the amount of heat recovered by the second super heater 22b in addition to the method of adjusting the combustion conditions in the melting furnace 12, for example. Can do.
That is, the temperature of the exhaust gas reaching the first super heater 22a can be lowered by performing a large amount of heat recovery with the second super heater 22b provided on the upstream side of the first super heater 22a.
The amount of heat recovered by the second super heater 22b can be adjusted by the temperature of water vapor introduced into the second super heater 22b.

If the amount of water vapor introduced into the third super heater 22c is increased in order to increase heat recovery in the super heater, the amount of water vapor flowing through the second super heater 22b or the first super heater 22a will also increase. As a result of the speed of water vapor passing through these super heaters (22a, 22b) being accelerated, it is not possible to secure sufficient time for heat exchange with the exhaust gas, and water vapor of 450 ° C. or higher from the final heat transfer tube a1. It may be difficult to remove.
In that case, a decelerating mechanism for taking out a part of the water vapor in the middle of the water vapor path to the final heat transfer tube a1 and reducing the water vapor passage speed may be provided. For example, the water vapor obtained by the third super heater 22c The energy recovery device 20 is further provided with a speed reduction mechanism 26 for taking a part of it before the second super heater 22b, so that the temperature of the water vapor in the second super heater 22b and the first super heater 22a is sufficiently increased. That's fine.
Further, water may be sprayed on the exhaust gas upstream of the final heat transfer tube a1 to reduce the temperature by evaporation.

  Further, the flow rate of the second exhaust gas at the position where the final heat transfer tube a1 is disposed, for example, in addition to the method of adjusting by the temperature reduction condition of the second exhaust gas upstream of the final heat transfer tube a1, for example, (2) The energy recovery device 20 is provided with a bypass path 27 that takes a part of the exhaust gas out of the boiler flue upstream from the final heat transfer pipe a1 and then returns the exhaust gas into the boiler flue at a position downstream of the final heat transfer pipe a1. Can also be adjusted.

Here, in the energy recovery device 20 of the present embodiment, the flow rate of the second exhaust gas is low, and the second exhaust gas is prevented from strongly hitting the final heat transfer tube a1, so that the corrosion of the final heat transfer tube a1 is suppressed.
As a result, it is possible to prevent the useful life of the super heater from becoming extremely short even if a generally easily available steel pipe such as SUS309S, SUS310S, or STBA12 as described above is adopted as the final heat transfer pipe a1.
Also, these steel pipes are available in various diameters and wall thicknesses on the market, and those with the required specifications are easy to obtain. Even when replacement of all or part is required, it is possible to quickly respond to such a request.

As described above, in the present embodiment, a plurality of heat transfer tubes through which water vapor exceeding 400 ° C. is circulated in the first super heater 22a are aligned in the exhaust gas distribution direction, and these are aligned in the exhaust gas distribution direction. Is arranged in.
Such a heat transfer tube through which water vapor exceeding 400 ° C. is usually corroded more easily than a heat transfer tube through which water vapor below 400 ° C. is flowed.
However, in the first super heater 22a of the present embodiment, these heat transfer tubes are arranged and arranged so that the upstream heat transfer tubes function as wind shields for the downstream heat transfer tubes, thereby suppressing corrosion.
In conventional super heaters, when a plurality of heat transfer tubes are arranged in the direction of exhaust gas flow, they are arranged in a zigzag because they are easy to exhibit excellent heat exchange efficiency. The heat pipes are arranged along the flow direction of the second exhaust gas to make the windbreak effect more remarkable.

However, no matter how the heat transfer tubes are arranged, if there is a large distance between them, it is difficult to expect a windbreak effect.
For example, it is preferable to provide an externally accessible space between each super heater, and the most upstream heat transfer tube a1 of the first super heater 22a and the most downstream heat transfer tube of the second super heater 22b. The center-to-center distance L2 between b6 and the center-to-center distance between the most downstream heat transfer tube a6 of the first super heater 22a and the most upstream heat transfer tube c1 of the third super heater 22c is secured to about 500 mm to 1000 mm. However, it is difficult to expect a windbreak effect if there is a large gap between the heat transfer tubes.
Therefore, for example, if the heat transfer tube has a diameter of 35 mm to 50 mm, the distance between the heat transfer tubes adjacent in the flow direction of the second exhaust gas (center-to-center distance L1) should be 100 mm or more and 170 mm or less. Is preferred.

  That is, when the energy recovery apparatus of this embodiment includes at least two heat transfer tubes arranged in alignment along the flow direction of the exhaust gas, the exhaust gas in the flow direction downstream of the two heat transfer tubes. The first heat transfer tube provided on the side and the second heat transfer tube provided on the upstream side in the exhaust gas flow direction are arranged such that the center-to-center distance is not less than 100 mm and not more than 170 mm. Either one of the heat transfer tubes is a heat transfer tube through which water vapor of 450 ° C. or higher flows, or another heat transfer tube through which water vapor of 400 ° C. or higher and lower than 450 ° C. flows. This is preferable in terms of preventing corrosion of the heat transfer tube.

Further, if the second heat transfer tube has a smaller diameter than the first heat transfer tube, a sufficient windbreak effect cannot be expected. Therefore, the second heat transfer tube has a thickness larger than that of the first heat transfer tube. It is preferable to have.
The quality of the second exhaust gas E introduced into the energy recovery device 20 may change depending on the contents of the waste A introduced into the gasification furnace 11.
In suppressing the corrosion of the final heat transfer tube a1, it is preferable that the second exhaust gas E has a concentration of a corrosive component equal to or lower than a predetermined level.
Specifically, the concentration of HCl in the second exhaust gas E introduced into the energy recovery device 20 is preferably 1000 ppm or less, and more preferably 500 ppm or less.
Note that the lower limit value of the HCl concentration in the waste combustion exhaust gas is usually about 5 ppm.
Further, the second exhaust gas E preferably has a SOx concentration of 100 ppm or less, and preferably 50 ppm or less.
The lower limit of the SOx concentration in the waste combustion exhaust gas is usually about 1 ppm.
Furthermore, since the second exhaust gas E contains a large amount of dust, it may adhere to the heat transfer tube and reduce the heat exchange efficiency. Therefore, the dust concentration is preferably 20 g / Nm ³ or less, and preferably 10 g / Nm. more preferably ³ or less, and particularly preferably 5 g / Nm ³ or less.
In addition, the lower limit of the dust concentration in the waste combustion exhaust gas is usually about 0.5 g / Nm ³ .

For example, an alkaline component may be introduced into the gasification furnace 11 or the melting furnace 12 to adjust the corrosive component in the second exhaust gas to a certain level or less, thereby further protecting the energy recovery device 20.
The temperature reducing tower 30 and the bag filter 40 on the downstream side of the energy recovery device 20 as described above are not particularly limited, and those used in conventional waste incineration facilities can be adopted.
Furthermore, the waste incineration facility of this embodiment may be provided with devices other than those exemplified above as necessary.

The energy recovery device of the present embodiment can obtain high-temperature steam without using a heat transfer tube made of a special material, and the high-temperature steam can be converted into electric energy by using it as a power source for a steam turbine. At the same time, it can be effectively used as a heat source.
In addition, in this embodiment, although the aspect which heat-recovers from the waste gas from a fluidized bed type gasification melting furnace is illustrated, the energy recovery apparatus of this embodiment is a simple flow which is not equipped with a melting furnace etc. It can also be used in combination with a floor-type combustion furnace.
In the present invention, the method of using the recovered high-temperature steam is not particularly limited, and conventionally known technical matters can be appropriately employed.
That is, the present invention is not limited to the above examples.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

Install steel pipes made of SUS310S and SUS309S, which are generally available stainless steel, and steel pipe “STBA12” made of low alloy steel for a certain period of time in a waste heat boiler that is an energy recovery device for actual waste incineration equipment. The thinning of these steel pipes was investigated.
The survey was conducted at two different waste incineration facilities (both facilities equipped with fluidized bed gasification and melting furnaces, hereinafter referred to as “facility A” and “facility B”).
Moreover, the steel pipe used as a sample was prepared with a total of four steel pipes made of SUS310S and one “STBA12” and two steel pipes made of SUS309S.
In addition, when the thickness of these steel pipes was measured, it was about 5 mm.
In each case, two steel pipes made of SUS309S are arranged in two locations, upstream and downstream in the exhaust gas flow direction, and adjusted so that the flow rate of the exhaust gas hitting each steel pipe is about 2 m / s. In addition, high-temperature air was circulated in the pipe so that the pipe surface temperature was about 480 ° C.
A temperature measurement probe using a sheathed thermocouple was installed near the steel pipe installed in the waste heat boiler, and a thermocouple was attached to the surface of the steel pipe to monitor the exhaust gas temperature and the steel pipe surface temperature during the survey period.

The installation of the steel pipe and the temperature monitoring were carried out separately at facility A and facility B, respectively.
Note that the first temperature monitor at facility A was 87 days, and the second temperature monitor was 95 days.
The first temperature monitor at facility B was 99 days, and the second temperature monitor was 73 days.
The tube surface temperature (period average value and maximum temperature during period) and exhaust gas temperature (period average temperature and maximum temperature during period) during the temperature monitoring period are shown in Table 1 below.

In addition, hydrogen chloride (HCl) concentration and sulfur oxide (SOx) concentration were measured in the vicinity of the steel pipes arranged at each facility.
The maximum and minimum values of the measured HCl concentration and SOx concentration are shown in Table 2 below.
Here, the aforementioned Non-Patent Document 1 describes that the exhaust gas from the stalker furnace contains HCl at a concentration of 1400 ppm and SO _{2 at a} concentration of 65 ppm at most.
In comparison, the exhaust gas in facilities A and B had a low concentration of corrosive gas as shown in Table 2 below.

After each monitoring for about 3 months, the amount of thinning of each steel pipe was measured. As a result, the amount of thinning from the beginning was 0.1 mm or less, and corrosion was sufficiently suppressed even at STBA12, as with SUS steel pipes. I found out that
Further, similar monitoring was continued at both facilities A and B, and after about 6 months, the thickness reduction of the steel pipe was measured again.
The result is shown in FIG.
As can be seen from this figure, the thinning amount of the steel pipe was slight even after about 6 months.
From this, it can be seen that according to the present invention, an energy recovery device capable of obtaining high-temperature steam without using a heat transfer tube made of a special material can be provided.

DESCRIPTION OF SYMBOLS 1 Waste incinerator 10 Fluidized bed type gasification melting furnace 11 Gasification furnace 12 Melting furnace 20 Energy recovery apparatus E Exhaust gas

Claims (7)

An exhaust gas passage through which exhaust gas obtained by burning waste by a fluidized bed combustion furnace or a fluidized bed gasification melting furnace flows;
A super heater having one or two or more heat transfer tubes provided in the exhaust gas flow path and extending in a direction crossing the flow direction of the exhaust gas;
An energy recovery device in which heat recovery is performed from the exhaust gas by steam flowing through the heat transfer pipe,
The super heater has the heat transfer tube through which water vapor of 450 ° C. or higher flows, and the heat transfer tube is made of general-purpose steel,
The exhaust gas flowing through the exhaust gas flow path is an energy recovery device having an average temperature of 550 ° C. or less and an average flow velocity of 3.0 m / s or less at a position where the heat transfer tube through which water vapor of 450 ° C. or higher flows. A first superheater that is the superheater provided with the heat transfer tube through which water vapor of 450 ° C. or higher flows;
A second super heater provided upstream of the first super heater in the flow direction of the exhaust gas;
And at least three super heaters including a third super heater provided downstream of the one super heater in the flow direction of the exhaust gas, and
Three super heaters are connected to each other,
The water vapor at 450 ° C. or higher is further heated by the second super heater, and the water vapor heated by the second super heater is heated by the heat exchange with the exhaust gas by the third super heater. The energy recovery apparatus according to claim 1, wherein the energy recovery apparatus is manufactured by further heating with a first super heater. The energy recovery device according to claim 1 or 2, wherein the average flow velocity of the exhaust gas is 1.6 m / s or more and 2.0 m / s or less. The exhaust gas flow path is provided with at least two heat transfer tubes arranged in alignment along the flow direction of the exhaust gas,
Of the two heat transfer tubes, the first heat transfer tube provided on the downstream side in the exhaust gas flow direction and the second heat transfer tube provided on the upstream side in the exhaust gas flow direction have a center distance of 100 mm or more and 170 mm. It is arranged so that
The first heat transfer tube is the heat transfer tube through which water vapor of 450 ° C or higher flows, or a heat transfer tube through which water vapor of 400 ° C or higher and lower than 450 ° C separate from the heat transfer tube. The energy recovery device according to any one of the above. A fluidized bed combustion furnace or fluidized bed gasification melting furnace for burning waste, and an energy recovery device for recovering heat from exhaust gas discharged from the fluidized bed combustion furnace or the fluidized bed gasification melting furnace Waste incineration facilities,
The energy recovery device is
An exhaust gas passage through which the exhaust gas flows;
A super heater having one or two or more heat transfer tubes provided in the exhaust gas flow path and extending in a direction crossing the flow direction of the exhaust gas;
Heat is recovered from the exhaust gas by steam circulated in the heat transfer tube, and
The super heater has the heat transfer tube through which water vapor of 450 ° C. or higher flows, and the heat transfer tube is made of general-purpose steel,
The exhaust gas flowing through the exhaust gas flow path is a waste incineration facility having an average temperature of 550 ° C. or less and an average flow velocity of 3.0 m / s or less at a position where the heat transfer tube through which water vapor of 450 ° C. or higher flows is arranged . A first super heater which is the super heater having a heat transfer tube through which water vapor of 450 ° C. or higher flows;
A second super heater provided upstream of the first super heater in the flow direction of the exhaust gas;
The energy recovery device includes at least three super heaters including a third super heater provided downstream of the one super heater in the flow direction of the exhaust gas.
In the energy recovery device, the three super heaters are connected to each other,
The water vapor at 450 ° C. or higher is further heated by the second super heater, and the water vapor heated by the second super heater is heated by the heat exchange with the exhaust gas by the third super heater. The waste incineration facility according to claim 5, which is produced by further heating with a first super heater. The waste incineration facility according to claim 5 or 6, wherein the average flow velocity of the exhaust gas is 1.6 m / s or more and 2.0 m / s or less.

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