JP2944969B2 - Heat transfer tube arrangement method for refuse incineration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement of heat transfer tubes in a refuse incineration plant for preventing corrosion of a heat recovery heat transfer tube in a refuse incineration plant by molten salt and for increasing the amount of heat recovery. It is about the method.

[0002]

Because of the Related Art In waste contains salt or chlorinated plastic, the burning garbage, chloride and hydrogen chloride gas (NaCl, KCl, CaCl _2, etc.) occurs, these chloride When an object melts beyond its melting point, there is a problem that a liquid (molten salt) adheres to a heat transfer tube (superheater or air heater) and causes corrosion. The melting point of NaCl is 8
The melting point of KCl is 770 ° C, and the melting point of CaCl ₂ is 772 ° C.

[0003] In a waste heat boiler in which refuse is burned to generate steam, the superheater tube is corroded by molten salt, so that a superheated steam of 500 ° C or more cannot be produced as in a coal-fired boiler. However, the temperature was about 300 ° C. (see the description of FIG. 2 described later).

[0004] In order to cope with the above-mentioned problem of corrosion, materials that are resistant to corrosion are currently being developed. However, if the corrosion by molten salts is to be imparted to a high-grade corrosion-resistant material, the material cost is increased. There's a problem. JP-A-57-778
No. 06 describes a method of providing a corrosion-resistant refractory material in a short bend portion of a short-bend portion of a boiler superheater tube / reheater tube in order to prevent high-temperature corrosion due to molten salt. Further, Japanese Patent Publication No. 60-45764 discloses that the inside of a short bend portion of a boiler superheater tube / reheater tube is covered with a protective material, and the combustion ash of the short bend portion is dropped and dropped, thereby causing a local high temperature. A method for preventing corrosion is described.

[0005]

According to the corrosion prevention methods described in these publications, local corrosion of the short bend portion of the heat transfer tube is prevented to some extent, but the corrosion progresses except for the short bend portion, and the short Since the bend portion is covered with a refractory material or a protective material, there is an inconvenience that the heat transfer area corresponding to the covered portion is reduced and the heat recovery amount is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a method in which the temperature of a combustion exhaust gas is high and chloride is molten, and the surface temperature is low and corrosion is difficult to proceed. Installing heat tubes, for example evaporators or / and economizers,
Reduce the temperature of the combustion exhaust gas to 700 ° C or less,
After making Cl and CaCl ₂ solid below the melting point, a superheater or / and a high-temperature air preheater is installed to perform heat exchange, thereby eliminating corrosion of the heat transfer tubes and increasing the amount of heat recovery. To provide a method of arranging heat transfer tubes.

[0007]

Means for Solving the Problems To achieve the above object, a method for arranging heat transfer tubes in a refuse incineration plant according to the present invention provides a method for disposing an evaporator in a refuse incineration plant provided with a refuse incinerator and a waste heat boiler. 1 and evaporator 2
From the low area, economizer, evaporator 1, superheater, evaporator 2
And the fluid outlet of the evaporator 1 is connected to the evaporator 2
Connect to the fluid inlet and save fluid to the economizer, evaporator 1, evaporator
2. The evaporator 2 is passed in the order of the superheater, and the evaporator 2 in which the surface temperature is lower than the melting point of the chloride and the corrosion hardly progresses is arranged in a high temperature region where the chloride in the exhaust gas from the refuse incinerator is molten. The temperature of the flue gas is reduced to a temperature below the melting point of chloride, and the chloride solidifies to a solid state , drastically reducing the corrosiveness of the flue gas.
After the rows of heat exchanger by placing the superheater through which high temperature fluid than the fluid in said evaporator 2 in this temperature range Ukoto
This prevents corrosion of the evaporator 2 and the heat transfer tube of the superheater, and may cause high-temperature corrosion due to molten salt.
It is configured to effectively utilize the high temperature region that cannot be used to increase the amount of heat recovery.

[0008] In the heat transfer tube arrangement method described above, high Yutakaiki is the temperature range of 700 to 1500 ° C., the temperature range for installing the superheater at a temperature range of 550 to 700 ° C..

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications. FIG. 1 shows a heat exchange state between flue gas and a fluid inside a heat transfer tube in the case of a heat transfer tube arrangement method in a waste incineration plant according to a first embodiment of the present invention, and FIG. 2 shows a heat transfer tube arrangement in a conventional waste incineration plant. 3 shows a heat exchange state between the flue gas and the fluid inside the heat transfer tube in an example of the method. Originally,
As shown in FIG. 2, the heat recovery is based on the counter flow, and in a region where the temperature of the flue gas is high, a superheater (super heater) is used.
ter, SH), and then in the middle temperature region where the temperature of the combustion exhaust gas is lowered, an evaporator (evaporator, EVA)
Is installed, and economizers (economizer,
ECO and air preheater are installed to reduce energy loss.

By violating this principle, in the present invention, a heat exchanger, such as an evaporator, which should originally perform heat exchange in a medium temperature range is installed in a high temperature range, and the temperature of the combustion exhaust gas falls, and chlorides solidify to form a liquid. High-temperature steam is obtained by placing a superheater in an area where solidification and corrosiveness have been drastically reduced, and the exergy loss is slightly larger than that of the countercurrent type, but the energy recovery rate due to high-temperature steam recovery is increased. Is much less than.

[0011] In FIG. 2, a little above the melting point T ₆ of chloride becomes a (e.g., 70 to 100 ° C.) lower the temperature T ₅ less, corrosion of the heat transfer tube by the molten salt is reduced. Conversely, higher temperature range than T ₅ will be referred to as corrosion zone. T
₅ When the deployable superheater to a high temperature region, the high-temperature corrosion by molten salt occurs, conventionally, superheater (SH) has been installed in the region of low temperature from T _5. As shown in the conventional example of FIG.
O), an evaporator (EVA), when arranged in this order superheater (SH), the T ₅ below the exhaust gas temperature, the hatched portion in FIG. 2 is overheated up to about 300 ° C. can not be available.

On the other hand, as shown in FIG.
Lowering the exhaust gas temperature by installing a EVA2 before (hot side) of dividing the A) to the EVA1 and EVA2 superheater (SH), the gas enthalpy drop between T ₅ -T ₄ can be used in the superheater , Around 500 ° C. That is, the economizer (ECO), evaporator 1
(EVA1), superheater (SH), evaporator 2 (EVA2)
And the outlet of EVA1 is connected to the inlet of EVA2, the temperature of the internal fluid of the heat transfer tube of EVA2 is lower than the internal fluid of the heat transfer tube of SH.
Even it is installed in a high exhaust gas region temperature than T _5, EVA
The surface of the heat transfer tube 2 is cooled by the internal fluid, and the adhered molten salt is immediately solidified and solidified to suppress the progress of corrosion. For this reason, a high-temperature region (shaded portion in FIG. 2) which could not be used conventionally because there was a risk of high-temperature corrosion due to molten salt can be effectively used, and the amount of heat recovery increases.

[0013]

As described above, the present invention has the following effects. (1) Install a heat exchanger , such as an evaporator, in the high temperature area, which used to exchange heat in the middle temperature area, and use a superheater in the temperature area where the exhaust gas temperature dropped, chlorides became solid, and corrosiveness decreased sharply. Since the heat exchanger that exchanges heat in the high temperature range is installed, high temperature corrosion due to molten salt can be prevented. (2) Originally heat exchange in medium temperature range like evaporator in high temperature range
A heat exchanger that should
An area where the solidification has changed from a liquid to a solid and the corrosiveness has been dramatically reduced.
Since the superheater is located in the
Has been used since there is a risk of hot corrosion due to molten salt.
High temperature area that could not be used can be used effectively, and heat recovery
The amount increases.

[Brief description of the drawings]

FIG. 1 is a diagram showing a heat exchange state between combustion exhaust gas and a fluid inside a heat transfer tube in the case of a method for arranging heat transfer tubes in a refuse incineration plant according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a heat exchange state between combustion exhaust gas and a fluid inside a heat transfer tube in an example of a method for arranging heat transfer tubes in a conventional refuse incineration plant.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Chitoku Kumagai 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Inside the Akashi factory (56) References JP-A-8-94002 (JP, A) JP Hei 8-145304 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F22B 1/18

Claims (2)

(57) [Claims] In a refuse incineration facility provided with a refuse incinerator and a waste heat boiler, an evaporator (1) and an evaporator (1) are provided.
(2) divided into low-temperature areas, economizers and evaporators
(1), superheater, and evaporator (2)
The fluid outlet of the evaporator (1) is connected to the fluid inlet of the evaporator (2).
Connect the fluid and save the fluid, evaporator (1), evaporator
(2), was flowed through in the order of superheater, a high temperature zone where chloride incinerator outlet combustion exhaust gas is melted, the surface temperature of corrosion progress hardly evaporator at below the melting point of the chloride (2) The temperature of the flue gas is lowered to the temperature range below the melting point of chloride, and the chloride solidifies to form a solid .
After dramatically reduced, this said evaporator temperature region (2) rows of heat exchanger by placing a superheater that flows high-temperature fluid than the fluid in Ukoto, evaporator (2) and superheater Prevents corrosion of heat transfer tubes and prevents high-temperature corrosion caused by molten salt.
Effective use of high temperature range that could not be used as it was
To, heat transfer tubes disposed method in waste incinerators, characterized in that to increase the heat recovery amount. Wherein a temperature range of high temperature range is 700 to 1500 ° C., the heat transfer tube arrangement method in waste incineration facility according to claim 1, wherein the temperature range is a temperature range of 550 to 700 ° C. for installing the superheater.