CN203771392U - Circulating fluidized bed boiler - Google Patents

Abstract

The utility model discloses a circulating fluidized bed boiler. A high-temperature flue gas control area and an low-temperature alkali metal condensing area are sequentially arranged along the flowing direction of flue gas in a hearth, wherein a flue of the hearth is connected with the flue gas sides of the high-temperature flue gas control area and the low-temperature alkali metal condensing area; the flue gas side of the low-temperature condensing alkali metal area, an outlet of the hearth and an inlet of the working medium side of the high-temperature flue gas control area are sequentially connected; an outlet of the working medium side of the high-temperature flue gas control area is connected with a gas-solid separation device; a solid particle outlet of the gas-solid separation device is connected with a returning mechanism; an outlet of the returning mechanism is connected with the bottom of the hearth; an alkali metal slag condenser is arranged in the low-temperature alkali metal condensing area; a working medium on the working medium side of the alkali metal slag condenser is a low-temperature cooling medium; a flue gas heater is arranged in the high-temperature flue gas control area; a working medium on the working medium side of the flue gas heater is low-alkali-metal-content/alkali-metal-free low-temperature flue gas discharged from the outlet of the hearth; the alkali metal slag condenser has a replaceable structure, and can be disassembled for cleaning or replaced after alkali metal in the flue gas condenses in the alkali metal condenser.

Description

Circulating fluidized bed boiler

technical field

The utility model relates to the technical field of coal-fired fluidized bed boilers, in particular to a circulating fluidized bed boiler for burning coal with high alkali metal content based on flue gas temperature gradient heat exchange.

Background technique

my country is a country rich in coal resources, and Xinjiang Zhundong is an area rich in coal resource reserves. Xinjiang Zhundong has huge coal reserves, low mining cost, good coal reactivity, and easy to burn out. However, due to the history of coal formation and the special local natural and geographical environment, the content of alkali metals such as sodium in Zhundong coal is generally high. Alkali metals in coal are an important factor that causes heat transfer surface contamination during coal combustion in boilers. Therefore, the combustion and utilization of high-alkali metal coals are greatly restricted. At present, the utilization of high-alkali metal coal mainly adopts the method of blending coal with weak pollution, but this control method can only slow down the pollution, and cannot fundamentally solve the problem. Therefore, it is of great practical significance and economic value to eliminate the problem of fouling on the heating surface of boilers caused by high-alkali metals during the combustion process of high-alkali metal coal for improving its combustion utilization.

A circulating fluidized bed boiler applied to high-sodium coal and biofuels (patent publication number 202938288U), within the range of the condensation temperature of alkali metals in the flue gas, the steam-cooled wall heat exchange surface is used instead of the convective heat exchange surface to reduce the The degree of condensation of alkali metals on convective heating surfaces within the temperature range. A flue gas recirculation boiler system (Patent Publication No. 203162930U) that uses fuel with high sodium and potassium content. Through the flue gas recirculation device, the temperature of the flue gas at the entrance of the mixing smoke chamber is reduced, so that the alkali metals in the flue gas are solidified in the mixing smoke chamber , to reduce ash slagging in the convective heating area of sublimation ash. A boiler thermal system that uses fuel with low ash melting point and high sodium and potassium content (patent publication number 202581381U). By increasing the radiation heat exchange area and reducing the furnace outlet temperature, alkali metals in the flue gas are condensed at the furnace outlet, reducing the amount of alkali metals Condensation on convective heating surfaces. There are certain defects in the above-mentioned patents: the heat exchange between the subsequent convective heat exchange surface and the flue gas is reduced by reducing the temperature of the flue gas.

The utility model is based on the precipitation and condensation rules of alkali metals in coal under different temperature conditions found in the combustion and heat exchange experiments of coals containing high alkali metals. Alkali-free flue gas, use the high-temperature zone to raise the temperature of low/alkali-free low-temperature flue gas, recover heat, and overcome the shortcomings of the above-mentioned patents. It can not only solve the problem of slag condensation on the heat exchange surface of the boiler, but also can greatly utilize the heat of fuel combustion, and flexibly arrange the heat exchange surface, which is conducive to the enlargement of the boiler.

Contents of the invention

The utility model overcomes the above-mentioned shortcomings of the prior art, and provides a circulating fluidized bed boiler for burning high-alkali coal based on temperature gradient heat exchange.

The technical scheme of the utility model is as follows:

The circulating fluidized bed boiler is characterized in that: a flue gas high-temperature control area 2 and an alkali metal low-temperature condensation area 3 are sequentially arranged in the furnace 1 along the flue gas flow direction,

The flue of the furnace 1 is connected to the flue gas side of the flue gas high temperature control zone 2 and the flue gas side of the alkali metal low temperature condensation zone 3,

The inlets on the flue gas side of alkali metal low-temperature condensation zone 3 and the working medium side of flue gas high-temperature control zone 2 are connected.

The flue gas high temperature control area 2 working fluid side outlet is connected to the gas-solid separation device 4 , the solid particle outlet of the gas-solid separation device 4 is connected to the feeding mechanism 5 , and the outlet of the feeding mechanism 5 is connected to the bottom of the furnace 1 .

An alkali metal slag coagulator 8 is arranged in the alkali metal low-temperature condensation zone 3, and the working medium on the side of the alkali metal slag coagulator 8 is a low-temperature cooling medium 6,

A flue gas warmer 7 is arranged in the flue gas high temperature control area 2, and the working medium on the side of the flue gas warmer 7 is low-temperature flue gas with low/alkali-free metal content from the furnace outlet.

The alkali metal slag coagulator 8 is a replaceable structure, and it can be disassembled, cleaned or replaced after the alkali metal in the flue gas is condensed in the alkali metal slag coagulator 8 .

The temperature of the flue gas high-temperature control zone 2 is 550-950°C, and the temperature of the alkali metal low-temperature condensation zone 3 is 250-650°C.

The flue gas produced by coal combustion passes through the flue gas side of the flue gas warmer arranged in the flue gas high temperature control area, the flue gas side of the alkali metal slag condenser arranged in the alkali metal low temperature condensation area, the furnace outlet, and the flue gas warmer. The working medium side, the gas-solid separation device, and finally reach the heating surface at the rear of the boiler.

The utility model proposes a circulating fluidized bed boiler based on temperature gradient heat exchange for burning coal containing high alkali metal components. Through temperature partitioning, the alkali metal in the flue gas is condensed on the alkali metal slag coagulator in the low-temperature condensation zone. . The low/alkali-free low-temperature flue gas in the alkali metal low-temperature condensation zone is heated through the flue gas high-temperature control area to obtain low/alkali-free high-temperature flue gas, and the clean high-temperature flue gas with low/alkali-free content is passed to the other convection of the boiler heating surface.

The utility model has the advantages of solving the problem of contamination of the heating surface when burning coals containing high alkali metal components, and at the same time greatly utilizing the heat of coal combustion.

Description of drawings

Fig. 1 is a working principle diagram of the present utility model;

Figure 2a shows the arrangement of the flue gas high-temperature control area and the alkali metal low-temperature condensation area of the utility model

Structural form in the furnace

Figure 2b shows that the flue gas high temperature control area of the utility model is arranged in the furnace, and the alkali metal low temperature

The structure in which the condensation zone is arranged outside the furnace outlet

Fig. 3a Arrangement form of flue gas alkali metal slag coagulator and flue gas warmer arranged in the same direction of working fluid side process

Figure 3b Arrangement of flue gas alkali metal slag cinder and flue gas warmer arranged in cross-flow of working fluid side flow

Detailed ways

Below in conjunction with accompanying drawing, overall structure of the present utility model is described in further detail.

In the figure: 1-furnace, 2-flue gas high temperature control zone, 3-alkali metal low temperature condensation zone, 4-gas-solid separation device, 5-returning mechanism, 6-low temperature cooling medium, 7-flue gas warmer, 8 - Alkali metal cinders.

As shown in Figure 1, the utility model technical scheme is as follows:

The circulating fluidized bed boiler is characterized in that: a flue gas high-temperature control area 2 and an alkali metal low-temperature condensation area 3 are sequentially arranged in the furnace 1 along the flue gas flow direction,

The flue of the furnace 1 is connected to the flue gas side of the flue gas high temperature control zone 2 and the flue gas side of the alkali metal low temperature condensation zone 3,

The flue gas side of the alkali metal low-temperature condensation zone 3, the outlet of the furnace, and the inlet of the working medium side of the flue gas high-temperature control zone 2 are connected in sequence,

The flue gas high temperature control area 2 working fluid side outlet is connected to the gas-solid separation device 4 , the solid particle outlet of the gas-solid separation device 4 is connected to the feeding mechanism 5 , and the outlet of the feeding mechanism 5 is connected to the bottom of the furnace 1 .

An alkali metal slag coagulator 8 is arranged in the alkali metal low-temperature condensation zone 3, and the working medium on the side of the alkali metal slag coagulator 8 is a low-temperature cooling medium 6,

A flue gas warmer 7 is arranged in the flue gas high temperature control area 2, and the working medium on the side of the flue gas warmer 7 is low-temperature flue gas with low/alkali-free metal content from the furnace outlet.

The alkali metal slag coagulator 8 is a replaceable structure, and it can be disassembled, cleaned or replaced after the alkali metal in the flue gas is condensed in the alkali metal slag coagulator 8 .

The temperature of the flue gas high-temperature control zone 2 is 550-950°C, and the temperature of the alkali metal low-temperature condensation zone 3 is 250-650°C.

As shown in Figure 2, the flue gas high-temperature control area and the alkali metal low-temperature condensation area can be arranged in the furnace according to the method a, and the flue gas high-temperature control area and the alkali metal low-temperature condensation area can be arranged in the furnace; It is arranged inside the furnace, and the alkali metal low-temperature condensation zone is arranged outside the furnace.

As shown in Figure 3, the arrangement of the flue gas alkali metal slag condenser and the flue gas warmer can be arranged according to a method, and the working fluid side flow is arranged in the same direction; according to b method, the working fluid side flow is arranged crosswise.

Concrete working principle of the present utility model is:

After the fuel enters the main combustion zone, the alkali metal compounds in the coal are volatilized to generate flue gas with high alkali metal content. The flue gas produced by coal combustion passes through the flue gas side of the flue gas warmer arranged in the flue gas high temperature control area, the flue gas side of the alkali metal slag condenser arranged in the alkali metal low temperature condensation area, the furnace outlet, and the flue gas warmer. The working medium side, the gas-solid separation device, and finally reach the heating surface at the rear of the boiler.

When the flue gas enters the low-temperature condensation zone of the alkali metal, the working medium side of the alkali metal slag coagulator is fed with a low-temperature cooling working medium, and the cooling working medium can be air or water. By adjusting the flow and temperature of 1 cooling working fluid, 2 the position of alkali metal slag coagulator in the furnace, 3 the flue gas flow rate on the flue gas side, and 4 boiler operating parameters such as primary and secondary air ratio, bed temperature and other conditions, to achieve Alkali metal low temperature condensation zone temperature control. When the flue gas temperature drops to 650°C to 250°C, all the alkali metals in the flue gas condense on the surface of the slag coagulator, and the flue gas is a low-temperature flue gas with low/no alkali metal content.

The low-temperature flue gas with low/no alkali metal content passes through the furnace outlet and enters the working fluid side of the flue gas warmer in the high-temperature flue gas control area, where it exchanges heat with the high-temperature flue gas side working fluid. The temperature in the flue gas high temperature control area is adjusted by adjusting 1 the flue gas flow rate on the working medium side, 2 the position of the flue gas warmer in the furnace, 3 the flue gas flow rate on the flue gas side, and 4 boiler operating parameters such as primary and secondary air ratios, bed Temperature and other conditions are achieved.

The low-temperature flue gas with low/no alkali metal content is heated up by the flue gas warmer in the high-temperature control area, and the temperature rises to above 550°C to obtain high-temperature flue gas with low/alkali-free metal content. These low/alkali-free clean When the high-temperature flue gas is passed to other convection heating surfaces of the boiler, it can solve the problem of contamination of the heating surfaces when burning coals containing high alkali metal components. When the slagging degree on the surface of the alkali metal slagging device in the alkali metal low-temperature condensation zone is serious, the alkali metal slagging device can be disassembled, cleaned or replaced to avoid affecting the flue gas flow state in the convection flue and avoid affecting the normal operation of the boiler.

Claims (2)

1. CFBB, is characterized in that: in burner hearth (1), suitable flow of flue gas direction is provided with fume high-temperature control zone (2), alkali metal cryogenic temperature condensation district (3) successively,

The flue of described burner hearth (1) is connected with fume high-temperature control zone (2) fume side, alkali metal cryogenic temperature condensation district (3) fume side,

The import of alkali metal cryogenic temperature condensation district (3) fume side, fume high-temperature control zone (2) working medium side is connected,

Fume high-temperature control zone (2) working medium side outlet is connected with gas-solid separating device (4), and the outlet of gas-solid separating device (4) solid particle is connected with returning charge mechanism (5), and returning charge mechanism (5) outlet is connected with burner hearth (1) bottom;

In described alkali metal cryogenic temperature condensation district (3), arrange alkali metal crust block device (8), alkali metal crust block device (8) working medium side working medium is low-temperature cooling media (6),

In described fume high-temperature control zone (2), arrange flue gas heating device (7), flue gas heating device (7) working medium side working medium be from furnace outlet low/alkali metal-free content low-temperature flue gas,

Described alkali metal crust block device (8) is changeable type structure, disassembling cleaning or the replacing after alkali metal crust block device (8) condenses of the alkali metal in flue gas.

2. CFBB as claimed in claim 1, is characterized in that: described fume high-temperature control zone (2) temperature is at 550～950 ℃, and described alkali metal cryogenic temperature condensation district (3) temperature is at 250～650 ℃.