CN2711537Y - Compact distributed circulating fluidized bed boiler - Google Patents

Abstract

The utility model relates to a compactly arranged circulating fluidized bed boiler, which relates to the structural design of an integrally arranged circulating fluidized bed boiler. The utility model comprises a combustion chamber, a separator and a tail shaft. The separator adopts a square separator and is composed of a membrane wall; the separator is arranged between the combustion chamber and the tail shaft, and a wall of the separator is shared with the combustion chamber. One wall, and the other side shares a wall with the tail shaft; or the separator is symmetrically arranged on both sides of the combustion chamber, one wall of the separator shares a wall with the combustion chamber, and the adjacent side shares a wall with the tail shaft. Different numbers of separators can be used depending on the boiler capacity. On the one hand, the utility model has compact layout, small volume, increased heat exchange surface, reduced heat loss, and improved boiler efficiency; on the other hand, it reduces the complexity of the sealing and expansion system, and enhances the stability and reliability of boiler operation; and The amplification effect is superior, especially suitable for medium and large circulating fluidized bed boilers.

Description

A Compact Circulating Fluidized Bed Boiler

technical field

The utility model relates to a circulating fluidized bed boiler, in particular to a structural design of an integrally arranged circulating fluidized bed boiler.

Background technique

The circulating fluidized bed boiler includes several main parts such as the combustion chamber, the separator and the tail shaft, and their overall layout is directly related to the floor area of the boiler. Keeping the overall layout of circulating fluidized bed boilers similar to traditional large and medium-sized pulverized coal boilers in the "∏" layout has always been the direction of research and development of circulating fluidized bed boilers.

At present, most circulating fluidized bed boilers are mainly arranged in the form of connecting flue between the combustion chamber, the separator and the tail shaft. The circulating fluidized bed boiler with a high temperature adiabatic cyclone separator built with materials is arranged as a "horizontal E" type overall. There are some problems in this arrangement, mainly because the cyclone is bulky, the steel consumption is high, the floor area is large, and the boiler cost is high; the cyclone lining is thick, refractory materials and masonry requirements are high, the consumption is large, and the cost High; long start-up time and prone to failure during operation; the sealing and expansion system is complex, and the stability and reliability of the expansion joints before and after the separator are the main problems. The medium-temperature separation technology developed by Babcock Company of Germany arranges a large number of heating surfaces on the upper part of the combustion chamber, which reduces the temperature and volume of the flue gas at the entrance of the cyclone, and the volume and weight of the cyclone are reduced, so To a considerable extent, it overcomes the defects of the adiabatic cyclone technology and improves its operational reliability. In this technology, a large number of heating surfaces need to be arranged on the upper part of the combustion chamber to reduce the temperature of the flue gas at the outlet of the combustion chamber. It needs to be arranged in a tower type, the combustion chamber is relatively high, and the steel consumption is large, which increases the cost of the boiler. The shell of the water (steam)-cooled cyclone separator designed by Foster Wheeler in the United States is made of bent and welded water-cooled or steam-cooled tubes. The high-temperature insulation layer of the heat-insulating cyclone is canceled and replaced by a curved surface made of a heating surface and its inner side. Covering the pins with a thin layer of high-temperature wear-resistant castable can better solve the problem of anti-wear inside the cyclone. The overall layout is similar to that of Luqi Company, but its production process is complicated and the manufacturing cost is high.

In order to overcome the high manufacturing cost of the water (steam) cooling cyclone, the Finnish company Ahlstrom proposed a new design concept, as shown in Figure 1. It adopts a square separator 2. The separation mechanism of the separator is essentially the same as that of the circular cyclone. The shell still adopts the water (steam) cooling tube wall type, but it is unique because of the planar structure of the cylinder. The biggest difference between it and the conventional circulating fluidized bed boiler is that it adopts a square gas-solid separation device. The wall of the separator is part of the water circulation system on the wall of the combustion chamber, so there is no thermal expansion joint between it and the combustion chamber. At the same time, the square separator can be arranged close to the combustion chamber, so that the volume of the whole circulating bed boiler is greatly reduced, and the arrangement is very compact. In addition, to prevent wear, the water-cooled surface of the square separator is covered with a thin refractory layer, which allows the separator to function as a heat transfer surface and enables faster boiler start-up and cooling rates. Due to the saving of a large amount of insulation and refractory materials, and the reduction of heat loss, the efficiency of the boiler is improved and the actual cost is reduced. However, the separator 2 and the tail shaft 4 are arranged on the front and rear sides of the combustion chamber 1, and the connecting flue 3 between the outlet of the separator and the tail shaft is arranged on the top of the combustion chamber 1. This arrangement has disadvantages in terms of further enlargement of the boiler. Certain flaws. With the further improvement of steam parameters, it is necessary to increase the convection heating surface (such as panel superheater and reheater) in the combustion chamber. The passage 3 merges into the upper header, so there are big problems in the sealing of the flue passage and the wear of the heated tube bundle.

Utility model content

Aiming at the deficiencies and defects of the existing technology, the purpose and task of this utility model is to provide a new compact circulating fluidized bed boiler, which can not only further save costs, enhance operational reliability, reduce heat loss, Improve the efficiency of the boiler, and have a superior amplification effect, and can be applied to the enlargement of the circulating fluidized bed boiler.

The technical scheme of the utility model is as follows: a compactly arranged circulating fluidized bed boiler, including a combustion chamber, a separator and a tail shaft, the separator adopts a square separator, which is composed of a membrane wall, and is characterized in that: At least two separators are used; the separator is arranged between the combustion chamber and the tail shaft, one wall of the separator shares a wall with the combustion chamber, and the other side shares a wall with the tail shaft; or the separation The separator is symmetrically arranged on both sides of the combustion chamber, one wall of the separator shares a wall with the combustion chamber, and its adjacent side shares a wall with the tail shaft.

The technical feature of the utility model is that: a convection heating surface is arranged in the combustion chamber.

Compared with the prior art, the utility model has the following advantages and beneficial effects: on the one hand, the arrangement is compact, the volume is small, the heat exchange surface is increased, the heat loss is reduced, and the boiler efficiency is improved; on the other hand, the complexity of the sealing and expansion system is reduced , enhance the stability and reliability of boiler operation; and the amplification effect is superior, especially suitable for medium and large circulating fluidized bed boilers.

Description of drawings

Fig. 1 is a schematic diagram of the structural layout of a circulating fluidized bed boiler in which the separator adopts a square membrane wall in the prior art.

Fig. 2 is a schematic diagram of the arrangement structure of the medium-capacity boiler provided by the utility model.

FIG. 3 is a schematic cross-sectional view of FIG. 2 .

Fig. 4 is a schematic diagram of the layout structure of the utility model for large-capacity boilers.

FIG. 5 is a schematic cross-sectional view of FIG. 4 .

Detailed ways

Below in conjunction with accompanying drawing, describe concrete structure, work process and specific implementation of the present utility model in detail.

For the medium-sized circulating fluidized bed boiler, the layout adopted by the utility model is shown in Figure 2 and Figure 3. The structure is that the separator 2 is arranged between the combustion chamber 1 and the tail shaft 4, and the separator adopts a membrane-type wall square Structure, a wall of the separator 2 shares a wall with the combustion chamber, and its other side shares a wall with the tail shaft 4. The boiler adopts single-drum horizontal natural circulation, "∏" type layout, and the combustion chamber 1, square separator 2 and tail shaft 4 are arranged in sequence from the front of the furnace to the rear. The boiler adopts a membrane wall structure before the tail wrapping wall 6, which is connected as a whole, and a rigid platform is used to fix the center, so that the expansion and sealing of the boiler are well solved. The combustion chamber 1 is composed of a membrane-type water-cooled wall, and the front and rear walls of the lower part of the combustion chamber 1 shrink into a conical furnace bottom. The lower water-cooled wall of the combustion chamber 1 is welded with denser pins, and a thinner high-temperature wear-resistant material is laid. The outlet of the combustion chamber 1 is arranged with a square separator 2 composed of two membrane-type water-cooled walls. The front wall of the separator 2 is shared with the rear wall of the combustion chamber 1, and the inlet acceleration section of the separator 2 is bent by the rear wall of the combustion chamber 1. Formation; the rear wall of the separator 2 is also used as the front wall of the tail shaft 4, the screen water wall shrinks downward to form a hopper, the upward part is directly drawn out for hanging, and the other part is forward to the rear wall of the combustion chamber to form a separator The ceiling and the front wall of the exit flue 3; the water-cooled walls on both sides of the separator 2 extend upwards to form the side wall of the exit area; the air-cooled ceiling of the exit area of the separator 4 to the rear wall of the turning chamber is downwards as the rear wall of the tail shaft 4 , together with the steam-cooled side wall and separator rear wall, form a membrane wall wall 6, and the separator 2, outlet flue 3 and tail wall 6 are combined to form a whole, avoiding the use of expansion joints, and maintaining a compact layout , but also to ensure good sealing performance. A convective heat exchange surface 5 (water cooling screen and superheater screen) is arranged on the upper part of the combustion chamber.

The working process is as follows: After the primary air is preheated, it flows through the air cap installed on the water-cooled air distribution plate and enters the combustion chamber 1 to ensure the fluidization quality and the combustion in the dense phase area. After preheating, the secondary air enters the combustion chamber 1 from the coal-spreading air outlet and the secondary air outlets on both sides to supplement the combustion air and strengthen the turbulent mixing. A large amount of smoke generated by the combustion of fuel in the combustion chamber 1 carries materials through the inlet acceleration section of the separator 2 and then enters the square separator 2, where the smoke and materials are separated. The separated material returns to the combustion chamber 1 through the hopper, the material leg, and the ash return valve to realize circular combustion; the flue gas enters the outlet flue 3 of the separator 2 from the central cylinder of the separator 2, and flows through the exhaust pipe arranged in the tail shaft 4. Discharged after the low temperature superheater, economizer and air preheater. The slag with larger particle size produced after fuel combustion is discharged from the bottom of the combustion chamber 1 . The boiler feed water enters the steam drum after being heated by the economizer; the saturated water in the steam drum enters the water-cooled wall of the combustion chamber 1 and the lower header of the water-cooled wall of the separator 2 respectively through the centralized downcomer and the distribution pipe, and flows into the upper header after being heated and evaporated Then enter the steam drum; the saturated steam flows through the ceiling pipe, the tail rear wrapping wall, the tail side wrapping wall, enters the low-temperature superheater located in the tail shaft wrapping wall 6, adjusts the steam temperature through the spray desuperheater, and then flows into the arrangement The superheater at the top of the combustion chamber is heated to the rated parameters by the final stage superheater on the upper part of the tail shaft 4 after the second spray water cooling, and finally from the main steam valve to the main steam pipeline.

With the development of large-scale circulating fluidized bed boilers, when the boiler capacity is further increased, the size of each component will increase. At this time, the utility model can adopt the method shown in Figure 4 and Figure 5, and the position of the separator 2 From rear wall arrangement to opposite arrangement on both sides of combustion chamber, one wall of separator 2 shares one wall with combustion chamber 1, and its adjacent side shares one wall with tail shaft 4, that is, separator 2 shares one wall with combustion chamber 1 Its side wall membrane type water-cooled wall heat exchange surface, the outlet flue 3 formed by the extension of the heating surface of the separator 2 is connected to the tail shaft 4, and the tail shaft 4 shares part of the membrane type water-cooled wall heat exchange surface with the separator on the rear wall, and the same The "∏" type layout is guaranteed, and other structures and working methods are basically consistent with medium-sized boilers. It not only has all the advantages mentioned above, but also has a superior amplification effect when the number of separators is further increased.

Claims (2)

1. the CFBB of a compact arrangement comprises combustion chamber (1), separator (2) and tail vertical well (4), and described separator adopts square separator, is made of membrane wall, and it is characterized in that: described separator adopts two at least; Described separator arrangement between combustion chamber and tail vertical well, the shared face wall in a wall of separator and combustion chamber, the shared face wall of its another side and tail vertical well; Perhaps this separator is arranged symmetrically in the both sides of combustion chamber, the shared face wall in a wall of separator and combustion chamber, its adjacent one side and the shared face wall of tail vertical well.

2. according to the described CFBB of claim 1, it is characterized in that: be furnished with heat convection face (5) in the described combustion chamber.

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