CN203286556U - Circular suspended heat exchange screen of circulating fluidized bed boiler - Google Patents

Abstract

Circulating fluidized bed boiler furnace ring-shaped suspended heat exchange panel, including suspended panel superheater, reheater, and water-cooled panel panels, the panels are composed of pipes and fins for circulating heat medium, several The screens are surrounded to form a ring-shaped or semi-circle-shaped single-group suspension screen, and the screens are fully or partially connected.

Description

Circulating fluidized bed boiler furnace ring-shaped suspended heat exchange screen

Technical field:

The utility model relates to a novel suspended heat exchange panel structure, which is suitable for a suspended panel heat exchanger in the hearth of a large-scale circulating fluidized bed boiler. the

Background technique:

With the increase of circulating fluidized bed boiler capacity, the area of heating surface that needs to be arranged in its main circulation loop (furnace, separator and return system loop) increases, and the arrangement of panel heating surface on the upper part of the furnace is a common design. the

At present, the suspended panel heat exchangers of circulating fluidized bed boilers are mostly monolithic parallel arrangements in structure, and are arranged in the upper area of the furnace in the form of wing walls. With the increase of boiler capacity, especially when the boiler is developing towards supercritical and ultra-supercritical parameters, large circulating fluidized bed boilers often need to arrange more and longer suspension screens to meet the boiler steam parameters. and load requirements. the

At this time, if these suspended heating surfaces all adopt the method of suspending screens on the furnace roof, firstly, the distance between the sheets will be too small, which will affect the heat absorption of the heating surface; It is easy to shake during operation, easy to produce bending deformation, and cause wear; in addition, the increase in the length of the screen will also increase the working fluid flow in the single-chip screen, making the tube screen prone to overheating, and the large height difference of the long screen is also easy The phenomenon of uneven heating will affect the service life of the suspended screen. the

Research by Zhejiang University has shown that for a large circulating fluidized bed boiler furnace, the concentration and velocity of particles suspended on the surface of the heat exchange screen in the upper part of the furnace are smaller than those at the wall of the water-cooled wall, which makes the heat transfer efficiency of the heat transfer screen higher than that of the same The area of the water wall is low. If the same amount of heat needs to be absorbed, the area of the screen must be larger. the

In circulating fluidized bed boilers, the particle concentration and velocity on the heat transfer surface are the key factors affecting the heat transfer coefficient of the heat transfer surface. The particle concentration and velocity on the surface of the heat exchange screen are relatively small, which means that its heat transfer coefficient is relatively small, and more heat exchange surfaces need to be installed to absorb the same amount of heat. Therefore, in the limited upper space of the furnace, it is necessary to ingeniously design and form a heat transfer screen that conforms to the gas-solid fluid characteristics of a large circulating fluidized bed furnace, ensures a certain screen spacing, high strength, and low wear, so as to meet the requirements of large-scale circulating fluidized bed boilers. The requirement to arrange more heating surfaces in the main circulation loop. At the same time, it overcomes the problems of heat transfer efficiency, stiffness and life caused by the large and long monolithic screen. the

In order to even the air flow in the upper part of the furnace, the applicant Zhu Zhenjin proposed a method of arranging a partition wall at a certain angle to the furnace wall in the pulverized coal furnace (patent number 99226485.5), which solved the problem of uneven heat flow of the air flow to a certain extent. The patent proposes that the characteristics of the gas-solid flow field in the pulverized coal boiler and the gas-solid flow field in the circulating fluidized bed furnace are different. the

Therefore, a heat transfer screen is disclosed that can conform to the gas-solid fluid characteristics of a large circulating fluidized bed furnace, ensure a certain screen spacing, high strength, and low wear, and can reduce the length of the suspension screen and increase the strength of the suspension screen. 1. It is very necessary to enhance the heat transfer effect of the suspension screen. the

Invention content:

The utility model aims to overcome the problems of heat transfer efficiency, rigidity and service life caused by the large and long suspension heat exchange screen monolithic screen of the existing large-capacity circulating fluidized bed boiler, and provides a more suitable for the current large-capacity circulating fluidized bed boiler. The suspended heat exchange screen of the chemical bed boiler enables more heating surfaces to be arranged in the main circulation loop, which can make better use of the furnace space, meet the requirements of the boiler steam parameters and load, increase the utilization rate of the furnace space, and reduce the The height of the furnace increases the strength of the suspended heat exchange screen to avoid overheating and increase its service life. the

The circulating fluidized bed boiler furnace ring-shaped suspended heat exchange panel described in the utility model includes a suspended panel superheater, a reheater, and a panel of a water-cooled panel. The heating medium is composed of tubes and fins, and several of the screens are surrounded to form a ring-shaped or semi-circle-shaped single-group suspension screen, and the screens are fully or partially connected. the

Preferably, the semi-circular single-group suspension screen is surrounded by 3 pieces to form a "匚" shape, and the ring-shaped single-group suspended screen is formed into a "mouth" shape by 4 pieces. the

Preferably, the "匚"-shaped single-group suspension screen is suspended on the upper part of the furnace of the circulating fluidized bed boiler, and the direction of the "匚"-shaped opening faces the rear wall of the furnace, or the front wall, or the left and right walls, or the peripheral water cooling of the furnace. wall. the

Further, when the "匚"-shaped opening is arranged in the direction of the anti-separator, there is a gas-solid outflow outlet 3 on the upper part of the "匚"-shaped heat exchange surface, and the ratio of the opening height h of the gas-solid outflow outlet 3 to the height H of the suspended heat exchange panel The range of h/H is 0-1. the

Or, preferably, the "port"-shaped single-group suspension screen is suspended on the upper part of the circulating fluidized bed boiler furnace, and the upper part of the "port" heat exchange surface is opened with a gas-solid flow outlet 3, and the opening height h is the same as that of the suspension heat exchange screen. The range of the height H ratio h/H is 0-1. the

Further, the opening on the top of the "mouth" heat exchange surface faces the rear wall of the furnace, or the front wall, or the left and right walls, or the peripheral water-cooled wall of the furnace. the

The distance between the "匚" and "mouth" shaped suspension screens in the furnace is less than 1/2W from the front wall of the boiler furnace, and W represents the depth or width of the furnace. the

Furthermore, the arrangement of the single-group suspension screen in the furnace is a single-piece and "匚" shape staggered interval arrangement, or a single-piece type and "mouth" shape staggered interval arrangement, or "匚" shape and "mouth" shape Arrangement in staggered intervals, or single-piece, "匚"-shaped, and "匚"-shaped three staggered intervals. the

The utility model has the advantages of adapting to the suspension heat exchange panel of the current large-capacity circulating fluidized bed boiler, so that more heating surfaces can be arranged in the main circulation loop, the furnace space can be better utilized, and the boiler steam parameters and requirements can be satisfied. At the same time, it can increase the utilization rate of the furnace space, reduce the height of the furnace, enhance the strength of the suspended heat exchange screen, avoid overheating, and improve its service life. the

Description of drawings

Fig. 1 is a partial three-dimensional schematic diagram of the utility model

Figure 2 is a schematic diagram of the screen enclosing method of the present invention

Figures 3a, 3b, 3c and 3d are respectively one of the basic layout forms of the utility model in the furnace

Figures 4a and 4b are schematic diagrams of ring-shaped suspended heat exchange panels with windows around the tubes

Figures 5a and 5b are schematic diagrams of the layout of traditional single-piece suspended heat exchange panels.

Figures 6a and 6b are schematic diagrams of the connection between screens

Figures 7a and 7b are schematic diagrams of annular headers. the

Detailed ways

Referring to attached drawing 1-7b:

The circulating fluidized bed boiler furnace ring-shaped suspended heat exchange panel described in the utility model includes a suspended panel superheater, a reheater, and a panel of a water-cooled panel. The heating medium is composed of tubes and fins, and several of the screens are surrounded to form a ring-shaped or semi-circle-shaped single-group suspension screen, and the screens are fully or partially connected. the

Preferably, the semi-circular single-group suspension screen is surrounded by 3 pieces to form a "匚" shape, and the ring-shaped single-group suspended screen is formed into a "mouth" shape by 4 pieces. the

Preferably, the "匚"-shaped single-group suspension screen is suspended on the upper part of the furnace of the circulating fluidized bed boiler, and the direction of the "匚"-shaped opening faces the rear wall of the furnace, or the front wall, or the left and right walls, or the peripheral water cooling of the furnace. wall. the

Further, when the "匚"-shaped opening is arranged in the direction of the anti-separator, there is a gas-solid outflow outlet 3 on the upper part of the "匚"-shaped heat exchange surface, and the ratio of the opening height h of the gas-solid outflow outlet 3 to the height H of the suspended heat exchange panel The range of h/H is 0-1. the

Or, preferably, the "port"-shaped single-group suspension panel is suspended on the upper part of the circulating fluidized bed boiler furnace, and the upper part of the "port" heat exchange surface is opened with a gas-solid flow outlet 3, and the opening height h is the same as that of the suspension heat exchange panel The range of the height H ratio h/H is 0-1. the

Further, the opening on the top of the "mouth" heat exchange surface faces the rear wall of the furnace, or the front wall, or the left and right walls, or the peripheral water-cooled wall of the furnace. the

The distance between the "匚"-shaped and "mouth"-shaped suspension screens in the furnace is less than 1/2W from the front wall of the boiler furnace, and W represents the depth or width of the furnace. the

Furthermore, the arrangement of the single-group suspension screen in the furnace is a single-piece and "匚" shape staggered interval arrangement, or a single-piece type and "mouth" shape staggered interval arrangement, or "匚" shape and "mouth" shape Arrangement in staggered intervals, or single-piece, "匚"-shaped, and "匚"-shaped three staggered intervals. the

The basic structure of the suspended heat exchange panel of the utility model is "匚" shape or "mouth" shape. As shown in Figure 2, a single group is formed by 3 or 4 single-piece suspended panel superheaters. Suspension screen, suspension screen 1 is composed of tubes and fins, the screen and the screen are connected by fins to form a "匚" or "mouth"-shaped ring-shaped suspension heat exchange screen, the upper end and the lower end A header or ring header 5 can be connected. The connection between the screens can be all connected together by fins as shown in Figure 6b, or as shown in Figure 6a, two adjacent pieces can be connected by fins at a certain distance. Compared with the original commonly used "丨" shaped suspension screen, both can increase the strength of the screen, making it less likely to be deformed during operation. the

In the "匚" or "口" shaped suspended heat exchange panel structure of the present utility model, a gas-solid flow window of an appropriate size can be set on the upper part of the heat exchange surface in the form of a coiled tube group, as shown in Figures 4a and 4b. Make the gas-solid flow flowing through the "匚" or "mouth" shaped suspended heat exchange panel flow out from the window. The ratio h/H of the height h of the window to the height H of the suspended heat exchange screen is in the range of 0-1. The direction of the window is generally towards the entrance of the separator, or towards the back wall of the furnace, or the front wall, or the left and right side walls. the

The layout of the utility model in the circulating fluidized bed furnace is shown in Figures 3a to 3d. The "匚", "口" and "丨" shapes can be arranged in the furnace at intervals. That is to say, all of them can be arranged as one of the first two structures, or the two structures can be arranged alternately, or a single piece/group of suspended screens can be arranged interspersed with the first two schemes. The distance between the "匚" and "口"-shaped suspension screens and the front wall of the boiler furnace is less than or equal to 1/2W, and W represents the depth or width of the furnace (Figure 3a to 3d). the

It can be seen from Figures 5a and 5b that compared with non-circular suspended heating panels, "匚" or "口" shaped suspended heating panels can arrange more heating surfaces in the same space of the circulating fluidized bed boiler furnace , the space in the furnace can be better utilized, and the average effective distance between the screens is increased, which eliminates the phenomenon of particles adhering to the screen wall and the speed being too small caused by too small screen spacing. In this way, the falling speed of the particles on the water-cooled wall surface 2 and the suspended screen wall surface 1 will increase compared with the previous ones, eliminating the negative factors that are unfavorable to the heat absorption of the heating surface, making it more consistent with the characteristics of the gas-solid fluid in the large-scale circulating fluidized bed furnace, and improving the heat transfer rate. Thermal efficiency. the

It can be seen from the basic structure of the utility model that the "匚" or "口" shaped suspended heating panel can be increased in width direction, that is, can be reduced in height direction. This can reduce the height difference of the single-chip screen and shorten the flow of working fluid in a single tube, thereby avoiding the occurrence of overheating and prolonging the service life of the screen. the

The content described in the embodiments of this specification is only an enumeration of the realization forms of the utility model concept, and the protection scope of the utility model should not be regarded as being limited to the specific forms stated in the embodiments, and the protection scope of the utility model also extends to Equivalent technical means that those skilled in the art can think of according to the concept of the utility model. the

Claims (8)

1. The ring-shaped suspended heat exchange panel of the circulating fluidized bed boiler furnace, including the panel of the suspended panel superheater, reheater, and water-cooled panel, is characterized in that: the said panel is composed of pipes for circulating heat medium Composed of fins, several of the screens are surrounded to form a ring-shaped or semi-circular single-group suspension screen, and the screens are fully or partially connected. 2. The heat exchange panel according to claim 1, characterized in that: the semi-circular single-group suspension screen is surrounded by three pieces to form a "匚" shape, and the ring-shaped single-group The suspended screen is formed into a "mouth" shape surrounded by 4 pieces. 3. The heat exchange panel according to claim 2, characterized in that: "匚"-shaped single-group suspension panel is suspended on the upper part of the furnace of the circulating fluidized bed boiler, and the direction of the "匚"-shaped opening faces the rear wall of the furnace, or The front wall, or the left and right walls, or the peripheral water wall of the furnace. 4. The heat exchange panel according to claim 3, characterized in that: when the "匚"-shaped opening is arranged toward the direction of the anti-separator, there is a gas-solid flow outlet 3 on the upper part of the "匚"-shaped heat exchange surface, and the gas-solid flow outlet 3. The ratio h/H of the opening height h to the height H of the suspended heat exchange panel ranges from 0 to 1. 5. The heat exchange panel as claimed in claim 2, characterized in that: the "mouth" shaped single-group suspension panel is suspended on the upper part of the circulating fluidized bed boiler furnace, and the upper part of the "mouth" heat exchange surface is opened with a gas-solid flow For outlet 3, the ratio h/H of the opening height h to the height H of the suspended heat exchange screen is in the range of 0-1. 6. The heat exchange screen according to claim 5, characterized in that: the upper opening of the "mouth" heat exchange surface faces the rear wall of the furnace, or the front wall, or the left and right walls, or the peripheral water wall of the furnace. 7. The heat exchange panel according to any one of claims 1-6, characterized in that: the distance b≤1/2W between the "匚"-shaped and "mouth"-shaped suspension panels and the front wall of the boiler furnace is arranged in the furnace , W represents the depth or width of the furnace. 8. The heat exchange panel according to claim 7, characterized in that: the arrangement of the single-group suspension panel in the furnace is a single-piece type and "匚" shape alternately arranged at intervals, or a single-piece type and "mouth" shape staggered interval arrangement, or "匚" shape and "mouth" shape staggered interval arrangement, or single-piece, "匚" shape, and "匚" shape three staggered interval arrangements.

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