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

Abstract

The utility model discloses a pulverized coal fired 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 an 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 upper part of the front wall of the hearth and positioned at the front part of the platen superheater. 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 utility model relates to the technical field of pulverized coal boilers, in particular to a pulverized coal boiler with a furnace inner membrane type water-cooling screen structure, which can be applied to the design of natural circulation pulverized coal boilers and the expansion and transformation of pulverized coal boilers. Background Art

[0002] In today's energy sector, the ever-increasing demand for energy consumption and the environmental damage caused by an unreasonable energy structure have brought severe challenges to China. As a key facility widely used in the power industry, the design optimization and transformation of pulverized coal boilers have far-reaching significance for achieving 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 boilers cannot meet the demand for increased heat load. At present, the main methods of increasing the heat load of pulverized coal boilers at home and abroad are to increase the furnace area and modify the burner. Since pulverized coal boilers burn in a four-corner cut-circle manner, 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. Utility Model Content

[0003] To address the above technical issues, this utility model designs a pulverized coal-fired boiler with a furnace membrane-type water-cooled screen structure. This adds a water-cooled evaporator screen to the traditional pulverized coal-fired boiler's steam-water system, expanding the evaporation heating surface and increasing evaporation capacity. While maintaining the same evaporation capacity, this reduces the furnace area and saves costs. This achieves a safe, efficient, and cost-effective increase in evaporation capacity from pulverized coal-fired boilers. This modification meets market demand for increased boiler load, effectively reduces energy capital consumption, and improves energy utilization.

[0004] The utility model adopts the following technical solutions:

[0005] A pulverized coal boiler with a furnace membrane-type water-cooled screen structure comprises a furnace and a tail flue, a water-cooled screen is provided on the furnace wall in the furnace, a screen-type superheater is provided at the inlet of the tail flue on the upper part of the furnace, a tail heating surface is provided in the tail flue, a water-cooled screen is provided on the upper part of the furnace front wall 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, the screen-type superheater and the tail heating surface are connected to the boiler drum through pipelines respectively.

[0006] Preferably, the boiler drum is connected to a water supply pipe.

[0007] Preferably, the boiler drum is connected to the water-cooled wall via a water-cooled wall downcomer.

[0008] Preferably, the water cooling screen is composed of multiple flat steels and multiple pipes, the multiple pipes are distributed side by side, and the multiple pipes are fixedly connected by welding the flat steels.

[0009] This new utility model expands the furnace's evaporative heating surface by adding a water-cooling screen to the upper portion of the furnace's front wall, in front of the screened superheater. Downcomers direct water from the water-cooling screen to a separate, integrated header, where it is then introduced into the boiler drum. This expansion of the furnace's capacity with the addition of this water-cooling screen demonstrates excellent performance.

[0010] 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 from the superheater. The present invention expands the evaporation heating surface of the furnace by adding a water-cooled screen, avoiding the problems of high furnace outlet temperature and excessive water spraying from 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 conventional water-cooled screens, has independent water supply and steam outlet pipes, and is 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 welding a whole piece of flat steel to the pipe to form a screen, several shorter sections of flat steel are welded to the pipe separately, which increases the rigidity of the tube screen while reducing the impact of the tube screen on the flow field.

[0011] 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 spraying caused by increased fuel volume in traditional pulverized coal boilers. It can reduce outlet flue gas temperature and control water spraying volume; (2) By directly adding a water-cooled screen, the evaporation heating surface is greatly increased compared with traditional pulverized coal boilers of the same size, reducing floor space and reducing costs; (3) The present invention is safer in water circulation than conventional water-cooled screen structures, and its layout is more reasonable, which can effectively improve problems such as coking and tube bursting; (4) The tube screen does not use a whole piece of flat steel welded to the tube, but has gaps between several pieces of flat steel for flue gas circulation, which is conducive to a uniform flow field. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the utility model;

[0013] Figure 2 This is a structural diagram of the water cooling screen in the utility model;

[0014] In the figure, 1. water supply pipe, 2. boiler drum, 3. downcomer, 4. water-cooled plate, 5. riser, 6. platen superheater, 7. furnace, 8. rear heating surface, 9. water-cooled wall downcomer, 10. pipe, 11. flat steel. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0016] Example: Figure 1 As shown, a pulverized coal-fired boiler with a membrane-type water-cooled panel structure in the furnace includes a furnace 7 and a tail flue. Water-cooled panels are installed on the furnace wall. A panel superheater 6 is installed at the tail flue entrance in the upper part of the furnace. A tail heating surface 8 is installed in the tail flue. A water-cooled panel 4 is installed on the upper part of the furnace front wall, in front of the panel superheater. The upper part of the water-cooled panel is connected to the boiler drum 2 via a riser 5. The boiler drum is connected to a downcomer 3. The bottom of the downcomer is connected to a header, which is connected to the lower part of the water-cooled panel. The panel superheater and the tail heating surface are connected to the boiler drum via pipelines. The boiler drum is connected to a water supply pipe 1. The boiler drum is connected to the water-cooled wall via a water-cooled wall downcomer 9.

[0017] The utility model 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 through the water feed pipe 1, and part of the water enters the water-cooled wall through the water-cooled wall downcomer 9 from the downcomer 3, and part of it is led out to a separate junction box and enters the added water-cooled screen 4. The steam-water mixture in the water-cooled screen then enters the boiler drum through 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, completing the steam-water cycle. By adopting the technical solution of the present invention, designers can provide higher-quality pulverized coal furnace design or expansion and modification solutions, saving furnace volume and construction costs under the same evaporation conditions, and reducing coking and pipe bursting problems.

[0018] like Figure 2 As shown, the water-cooled panel is composed of multiple narrow flat steel bars 11 and a number of tubes 10. The tubes are arranged side by side and connected securely by welding the flat steel bars. This allows flue gas to flow out through the gaps between the tube rows, reducing the impact of the panel on the flue gas flow field and minimizing panel sway caused by flue gas flow.

[0019] The embodiment described above is only a preferred solution of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A pulverized coal boiler with a furnace membrane water-cooled panel structure, comprising a furnace and a tail flue, wherein a water-cooled panel is provided on the furnace wall, a panel superheater is provided at the inlet of the tail flue on the upper part of the furnace, and a tail heating surface is provided in the tail flue, wherein: A water-cooled screen is provided on the upper part of the front wall of the furnace in front of the screen 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 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 pipe.

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 type water-cooled panel structure according to claim 1 is characterized in that: The water cooling screen is composed of multiple flat steels and multiple pipes. The multiple pipes are distributed side by side and are fixedly connected by welding the flat steels.

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