JPH10288306A - Circulating fluidized bed boiler equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make heat transfer effective and reduce installation area of equipment. SOLUTION: This equipment comprises a falling particle type heat exchanger 102 to which high temperature particles and combustion gas are supplied from a furnace 101 forming a high speed fluidized bed and a fluidized bed type heat exchanger 103 to which the high temperature particles are supplied from the falling particle type heat exchanger 102. After effecting generation and superheating of steam and being reduced in temperature, the high temperature particles in the fluidized bed type heat exchanger 103 are supplied to the falling particle type heat exchanger 102 to carry out heat exchange with combustion gas to be increased in temperature and are circulated between the heat exchangers 102 and 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circulating fluidized-bed boiler.

[0002]

2. Description of the Related Art An example of a conventional circulating fluidized bed boiler is shown in FIG. In FIG. 2, in a furnace 201 of a high-speed fluidized bed, various fuels are burned.

[0003] Fluidized material, ash, and unburned fuel (hereinafter, referred to as fluidized material, etc.) discharged from the furnace 201 are separated from combustion gas in a cyclone 202, and the fluidized bed heat exchanger (Fluidized Bed) is used.
Heat Exchanger. Hereinafter, referred to as FBHE) 203, where steam is generated and overheated. The fluidized material and the like that have been cooled by the FBHE 203 and the high-temperature fluidized material that has bypassed the FBHE 203 are circulated and supplied to the furnace 201 again.

On the other hand, the combustion gas at about 850 ° C. separated from the fluidized material and the like by the cyclone 202 is heated by heating steam and air in a back path 204 comprising a rear superheater and an air preheater, which are tubular heat exchangers. The temperature drops to about 150 ° C. and is discharged from a chimney (not shown).

[0005]

In a conventional circulating fluidized-bed boiler, the furnace of a high-speed fluidized bed is a relatively dilute solid-gas two-phase flow having a heat transfer coefficient of about 150 kcal / m ² h ° C. and an FBHE.
Is a rich solid-gas two-phase flow with a heat transfer coefficient of 400 kcal / m ² h
On the other hand, the heat transfer coefficient is about 50 kcal / m ² h ° C. while the back path is a gas phase flow.

[0006] That is, since the heat transfer coefficient is small in the back path, there is a disadvantage that the heat transfer area becomes significantly larger than the exchanged heat amount, and it is necessary to improve this to reduce the installation area of the equipment. there were. In addition, the said exchange heat quantity is represented by the following formula.

The amount of heat exchanged = heat transfer rate × temperature difference × heat transfer area The present invention is intended to solve the above-mentioned problems.

[0008]

According to a first aspect of the present invention, there is provided a circulating fluidized bed boiler apparatus comprising: a falling particle type heat exchanger to which hot particles and combustion gas are supplied from a furnace forming a high speed fluidized bed; FBHE to which high-temperature particles from the heat exchanger are supplied. After the high-temperature particles in the FBHE generate and overheat steam to lower the temperature, the FBHE is supplied into the falling-particle heat exchanger to generate combustion gas and heat. It is characterized by exchange and circulation.

[0009] In the above, the high-temperature particles and the combustion gas, which are made of fluidized material and the like, which have flowed out of the furnace, flow into the falling-particle heat exchanger, and the high-temperature particles flow into the FBHE to generate steam and superheat. After the temperature is lowered, it is sent again into the falling particle type heat exchanger, and exchanges heat with the combustion gas to raise the temperature and circulate.

In the present invention, the heat held by the combustion gas is transferred to the solid particles by a falling particle type heat exchanger having a large heat transfer area and a high heat transfer coefficient. Since superheated steam is generated by being supplied to the FBHE with a high efficiency, a back path with a low heat transfer rate and a cyclone for separating particles and gas used in the conventional apparatus are not required, and the equipment can be made compact. Cost reduction becomes possible.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A circulating fluidized-bed boiler according to one embodiment of the present invention will be described with reference to FIG.

In the circulating fluidized bed boiler apparatus according to the present embodiment shown in FIG. 1, primary air is supplied from the bottom and secondary air is supplied from the lower side, forming a high temperature fluidized bed therein and burning various fuels. Furnace 101, fluidized material (including ash, unburned fuel, etc.) discharged from the upper part of the furnace 101 and combustion gas are supplied from the lower part of the side, and the combustion gas is discharged from the upper part to remove the fluidized material. The falling-particle-type heat exchanger 102 discharged from the bottom and the fluidized material discharged from the heat exchanger 102 are supplied from the upper part, and a part of the fluidized material is discharged from the side to remove the fluidized material from the furnace 101. An FBHE 103 is provided which is supplied to the lower portion, discharges the remaining portion from the bottom portion, and supplies it to the upper portion of the falling particle type heat exchanger 102.

In the above description, the fluidized material and the combustion gas from the furnace 101, which forms a high-speed fluidized bed by burning various fuels, flow into the falling particle type heat exchanger 102. Since the superficial velocity of the falling-grain heat exchanger 102 is set lower than that of the furnace 101, the fluid material or the like flowing from the falling-grain heat exchanger 102 falls downward and flows into the FBHE 103, where only the combustion gas is discharged. Rises.

The fluidized material flowing into the FBHE 103 generates steam, overheats, and lowers the temperature. The falling particle type heat exchanger 10
In 2, the particulate fluid material or the like cooled by the FBHE 103 is supplied from above, heat exchange is performed with the combustion gas, and the high-temperature particulate fluid material or the like falls downward, Returning to the FBHE 103 again, it generates steam and overheats.

In this embodiment, a falling particle type heat exchanger is used in place of the back path in the conventional apparatus. However, compared with the tube type heat exchanger employed in the back path,
The falling particle heat exchanger has a surface area per volume of 100
Since the heat transfer coefficient is about twice as large, and the heat transfer coefficient is about twice as large, the size of the falling particle heat exchanger can be reduced as compared with the back path.

The solid particles heated at a high temperature in the falling particle type heat exchanger exchange heat with the FBHE. However, since the heat transfer coefficient here is about eight times as large as that of the back path, the heat transfer area of the FBHE increases. Is relatively small.

Further, in the falling particle type heat exchanger, 99% or more particles fall because the superficial velocity of the gas is lowered,
The amount of particles scattered with the gas can be suppressed, and a cyclone is not required.

[0018]

The circulating fluidized-bed boiler of the present invention has a falling-particle heat exchanger to which hot particles and combustion gas are supplied from a furnace forming a high-speed fluidized bed, and a high-temperature particle from the falling-particle heat exchanger. Is supplied.The high temperature particles in the fluidized bed heat exchanger generate steam, overheat and cool down, and then are supplied into the falling particle heat exchanger, where the combustion gas and heat are supplied. By exchanging the temperature and increasing the temperature, and circulating between the two heat exchangers, the heat of the combustion gas is transferred to the falling particle heat exchanger, which has a large heat transfer area and a large heat transfer coefficient, and heat transfer. Because it is used to generate superheated steam with a fluidized bed heat exchanger with a high rate, the back path with low heat transfer rate used in conventional equipment and the cyclone for separating particles and gas are not required, Equipment can be made compact and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of a circulating fluidized-bed boiler device according to one embodiment of the present invention.

FIG. 2 is a system diagram of a conventional circulating fluidized bed boiler.

[Explanation of symbols]

 101 Furnace 102 Falling particle type heat exchanger 103 Fluidized bed type heat exchanger

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shingo Kanehira 1-1-1 Wadazakicho, Hyogo-ku, Kobe-shi

Claims (1)

[Claims] 1. A falling-particle heat exchanger to which hot particles and a combustion gas are supplied from a furnace forming a high-speed fluidized bed, and a fluidized-bed heat exchanger to which high-temperature particles are supplied from the falling-particle heat exchanger After the high-temperature particles in the fluidized bed heat exchanger generate and overheat steam to lower the temperature, the heat is supplied to the falling particle heat exchanger to exchange heat with the combustion gas and circulate. And a circulating fluidized bed boiler device.