Pulverized coal boiler with membrane type water cooling screen structure in hearth

Abstract

The invention discloses a pulverized coal boiler with a membrane type water cooling screen structure in a hearth, which comprises the hearth and a tail flue, a water cooling wall is arranged on the inner wall of the hearth, a platen superheater is arranged at the inlet of the tail flue at the upper part of the hearth, a tail heating surface is arranged in the tail flue, and a water cooling screen is arranged at the front part of the platen superheater at the upper part of the front wall of the hearth. The upper portion of the water-cooling screen is connected with a boiler barrel through an ascending pipe, the boiler barrel is connected with a descending pipe, the bottom of the descending pipe is connected with a header, the header is connected with the lower portion of the water-cooling screen, and the platen superheater and the tail heating surface are communicated with the boiler barrel through pipelines respectively. The water-cooling evaporation screen is additionally arranged on the basis of a traditional pulverized coal boiler steam-water system, and the purposes of expanding the evaporation heating surface and increasing the evaporation capacity are achieved. And the hearth area is reduced under the same evaporation capacity, and the cost is saved. And the evaporation capacity of the pulverized coal boiler is improved safely and efficiently at low cost. The requirement of the market for boiler load improvement is met, energy and capital consumption is effectively reduced, and the energy utilization rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of pulverized coal boilers, and in particular to a pulverized coal boiler with a furnace inner membrane type water-cooled screen structure, which can be applied to the design of a natural circulation pulverized coal boiler and the expansion and reconstruction of a pulverized coal boiler. Background Art

[0002] In today's energy field, the ever-increasing demand for energy consumption and the environmental damage caused by the unreasonable energy structure have brought severe challenges to China. As a key facility widely used in the power industry, the implementation of the design optimization and transformation of pulverized coal furnaces has far-reaching significance for the realization of a sustainable energy development strategy. With the development of the economy and society and the improvement of people's living standards, the workload of thermal power plants has gradually increased, and many existing pulverized coal furnaces cannot meet the demand for increased heat load. At present, the increase in the heat load of pulverized coal boilers at home and abroad is mainly carried out by increasing the furnace area and transforming the burner. Since the pulverized coal furnace burns in a circular manner with four corners, the furnace layout is close to a square. Traditionally, to increase the furnace area, it is necessary to expand the furnace cross-sectional area or increase the furnace height, which occupies a large area and is costly. Summary of the invention

[0003] In order to solve the above technical problems, the present invention designs a pulverized coal boiler with a furnace membrane water-cooled screen structure. A water-cooled evaporation screen is added to the traditional pulverized coal boiler steam-water system to achieve the purpose of expanding the evaporation heating surface and increasing the evaporation capacity. The furnace area is reduced at the same evaporation capacity, saving costs. The evaporation capacity of the pulverized coal boiler is increased safely, efficiently and at low cost. Through this transformation, the market demand for increased boiler load is met, the consumption of energy capital is effectively reduced, and the energy utilization rate is improved.

[0004] The present invention adopts the following technical solution: A pulverized coal boiler with a membrane-type water-cooled screen structure in the furnace comprises a furnace and a tail flue, a water-cooled wall is arranged on the furnace wall in the furnace, a screen-type superheater is arranged at the inlet of the tail flue in the upper part of the furnace, a tail heating surface is arranged in the tail flue, a water-cooled screen is arranged on the upper part of the front wall of the furnace in front of the screen-type superheater, the upper part of the water-cooled screen is connected to a boiler drum through an ascending pipe, the boiler drum is connected to a downcomer, the bottom of the downcomer is connected to a header, the header is connected to the lower part of the water-cooled screen, the screen-type superheater and the tail heating surface are connected to the boiler drum through pipelines respectively.

[0005] Preferably, the boiler drum is connected to a water supply pipe.

[0006] Preferably, the boiler drum is connected to the water-cooled wall via a water-cooled wall downcomer.

[0007] Preferably, the water cooling screen is composed of a plurality of flat steels and a plurality of pipes, the plurality of pipes are arranged side by side, and the plurality of pipes are fixedly connected by welding the flat steels.

[0008] Based on the traditional pulverized coal boiler, the present invention adds a water cooling screen on the upper part of the front wall of the furnace and the front part of the screen superheater, thereby expanding the evaporation heating surface of the furnace. The water cooling screen is centrally led out of the downcomer to the separately arranged converging header for water supply, and then introduced into the boiler drum from the header. After the furnace is expanded by adding the water cooling screen, the operation effect is ideal.

[0009] The present invention can be effectively applied to the design of natural circulation pulverized coal boilers, and can also be applied to the expansion and transformation of pulverized coal boilers. If the evaporation capacity of traditional pulverized coal boilers is to be increased, the amount of fuel brought in will increase, which will lead to an increase in the amount of flue gas. If the evaporation heating surface of the original furnace is kept unchanged, the flue gas temperature at the furnace outlet will increase, which will lead to excessive water spraying of the superheater. The present invention adopts the method of adding a water-cooled screen to expand the evaporation heating surface of the furnace, avoiding the problems of high furnace outlet temperature and excessive water spraying of the superheater. In order to reduce the risk of coking and pipe bursting, the water-cooled screen is designed to have a safer water circulation structure than the conventional water-cooled screen, with independent water supply and steam outlet pipes, and arranged on the upper part of the front wall of the furnace. In order to reduce the impact of the addition of a water-cooled screen on the flow of flue gas, instead of using a whole piece of flat steel welded to the pipe as a screen, several sections of shorter flat steel are welded to the pipe respectively, which increases the rigidity of the tube screen while reducing the impact of the tube screen on the flow field.

[0010] The beneficial effects of the present invention are as follows: (1) The present invention has a wide range of applications and can be applied to various types of pulverized coal boiler designs and pulverized coal boiler expansion and transformation, solving the problem of increased outlet flue gas temperature and excessive superheater water spray caused by increased fuel volume in traditional pulverized coal boilers. It can reduce the outlet flue gas temperature and control the water spray volume; (2) By directly adding a water-cooled screen, compared with traditional pulverized coal boilers of the same size, the evaporation heating surface is greatly increased, the floor space is reduced, and the cost is reduced; (3) The water circulation of the present invention is safer than that of conventional water-cooled screen structures, and the layout position is more reasonable, which can effectively improve the problems of coking and pipe bursting; (4) The pipe screen does not use a whole piece of flat steel welded to the pipe, but has gaps between several pieces of flat steel to allow the flue gas to circulate, which is conducive to a uniform flow field. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 This is a schematic diagram of the structure of the water cooling screen in the present invention; In the figure, 1. water supply pipe, 2. boiler drum, 3. downcomer, 4. water-cooled screen, 5. riser, 6. screen superheater, 7. furnace, 8. rear heating surface, 9. water-cooled wall downcomer, 10. pipe, 11. flat steel. DETAILED DESCRIPTION

[0012] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Example: Figure 1As shown, a pulverized coal boiler with a membrane-type water-cooled screen structure in the furnace comprises a furnace 7 and a tail flue, a water-cooled screen is arranged on the furnace wall in the furnace, a screen-type superheater 6 is arranged at the entrance of the tail flue in the upper part of the furnace, a tail heating surface 8 is arranged in the tail flue, a water-cooled screen 4 is arranged at the upper part of the front wall of the furnace in front of the screen-type superheater, a boiler drum 2 is connected to the upper part of the water-cooled screen through an ascending pipe 5, a downcomer 3 is connected to the lower part of the water-cooled screen, a header is connected to the lower part of the water-cooled screen at the bottom of the downcomer, and the header is connected to the lower part of the water-cooled screen, and the screen-type superheater and the tail heating surface are connected to the boiler drum through pipelines. The boiler drum is connected to the water supply pipe 1. The boiler drum is connected to the water-cooled wall through a water-cooled wall downcomer 9.

[0013] The present invention adds a water-cooled screen 4, which is arranged on the upper part of the front wall of the furnace 7 and in front of the screen superheater 6. When the boiler is running, the feed water enters the boiler drum 2 from the water feed pipe 1, and part of the water enters the water-cooled wall from the downcomer 3 through the water-cooled wall downcomer 9, and part of the water is led out to a separate converging header and enters the added water-cooled screen 4. The steam-water mixture in the water-cooled screen then enters the boiler drum from the riser 5. The steam in the boiler drum enters the screen superheater 6 through the pipe system, and then enters the rear heating surface 8 to complete the steam-water cycle. By adopting the technical solution of the present invention, designers can provide a higher quality pulverized coal furnace design or expansion and reconstruction plan, saving furnace volume and construction costs under the same evaporation conditions, and reducing coking and pipe bursting problems.

[0014] like Figure 2 As shown, the water-cooled panel is composed of a plurality of narrow flat steels 11 and a plurality of tubes 10, which are arranged side by side and fixedly connected by welding of the flat steels, so that the flue gas can flow out from the gaps between the tube rows, reducing the influence of the tube panel on the flue gas flow field and reducing the shaking of the tube panel caused by the flue gas flow.

[0015] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A pulverized coal boiler with a furnace membrane water-cooled screen structure, comprising a furnace and a tail flue, a water-cooled wall is arranged on the furnace wall in the furnace, a screen superheater is arranged at the entrance of the tail flue on the upper part of the furnace, and a tail heating surface is arranged in the tail flue, wherein: A water-cooled screen is arranged on the upper part of the front wall of the furnace in front of the screen-type superheater. The upper part of the water-cooled screen is connected to the boiler drum through an ascending pipe, the boiler drum is connected to a downcomer, the bottom of the downcomer is connected to a header, the header is connected to the lower part of the water-cooled screen, and the screen-type superheater and the rear heating surface are connected to the boiler drum through pipelines respectively.

2. A pulverized coal boiler with a furnace membrane water-cooled panel structure according to claim 1, characterized in that: The boiler drum is connected to a water supply pipeline.

3. The pulverized coal boiler with a furnace membrane water-cooled panel structure according to claim 1 is characterized in that: The boiler drum is connected to the water-cooled wall through a water-cooled wall downcomer.

4. The pulverized coal boiler with a furnace membrane water-cooled panel structure according to claim 1 is characterized in that: The water cooling screen is composed of a plurality of flat steels and a plurality of pipes. The plurality of pipes are arranged side by side and are fixedly connected by welding the flat steels.

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