Current-equalizing pneumatic heat exchanging bed

Abstract

The invention is a current-equalizing pneumatic heat exchanging bed for a circulating fluidized bed boiler (CFBB), comprising a feed bin 1, a high-temperature bin 2, a current-equalizing bin 3, a heat exchanging bin 4, a low-temperature bin 5, a wind box 16 of each bin and the bottom part thereof, an air distributor 15, a hood 14, an air duct 18 and a wind speed control device 19 to form an independent and operable integral. The shunting ratio of circulating ash can be controlled by adjusting wind speed of each bin, part of circulating ash directly goes back to a furnace 20, and the other part thereof goes back to the furnace 20 after being cooled by a heating surface 6. The invention uses a pneumatic method for realizing shunting and controlling of the circulating ash, has the advantages of wide adjusting range, evenly heat exchanging, no abrasion and tube explosion and mechanical fault, and is applicable to large-scale circulating fluidized bed boiler (CFBB).

Description

technical field [0001] The invention relates to the technical field of circulating fluidized bed boilers, in particular to a flow-equalizing pneumatic heat exchange bed for circulating fluidized bed boilers. Background technique [0002] Circulating fluidized bed boiler is a clean coal utilization technology that is widely used at present. With the increase of circulating fluidized bed boiler capacity, there are common problems such as limited space in the furnace, insufficient arrangement of heating surfaces, and serious wear of the panel heating surface in the furnace. For technical problems, the best solution is to arrange an external bed in the heat circulation loop between the separator and the furnace, transfer a part of the heat carried by the circulating ash to the external bed, and adjust the amount of circulating material between the return valve and the external bed The ratio, control the combustion temperature in the furnace, and adjust the steam parameters. The...

AI Technical Summary

Problems solved by technology

The existing well-run large circulating fluidized bed boilers at home and abroad are all equipped with external beds. For example, the technology of French ALSTOM company adopts the external bed with conical valve control. The principle of this control method is to separate the high-temperature cyclone separator. Part of the ash is sent back to the furnace through the return valve, and part of the ash is sent back to the furnace through the heat exchange between the external bed and the internal heating surface. The amount of ash sent to the external bed is controlled by a cone valve. The stem and body of the conical valve are cooled by water, which has a complex structure and high cost. Since the conical valve works in a high temperature and high ash concentration environment for a long time, it is very easy to wear and tear, and the maintenance workload is large. In addition, due to space constraints, the external bed is heated Generally, the layout of the surface is relatively tight, the maintenance space is small, and problems such as vibration, local wear, and pipe burst are prone to occur during operation. In addition, this arrangement requires the external heat exchange bed to occupy a certain height, which is restricted by the structure of the separator and return valve. Restrictions often make the height of the lower standpipe of the separator lower, and it is difficult to form a sufficient material seal, which affects the separation efficiency and the stable operation of the external circulation loop

[0003] In existing patents, there are external beds that do not use mechanical control, such as a compact split flow ash return heat exchanger, which can be learned from the utility model patent specification 00238546.5. It is known that this compact split flow ash return heat exchanger The high-temperature heat exchange bed and the low-temperature heat exchange bed need to arrange two sets of different heating surfaces. Due to space constraints, the length of the heat exchanger is relatively large and cannot provide sufficient maintenance space; The strength will be affected in the high temperature environment; the high temperature ash entering the heat exchange bed is easy to flow by itself; especially the air volume of the low temperature return chamber, the low temperature heat exchange bed and the high temperature heat exchange bed needs to be adjusted in sequence to realize the shunt flow control of the ash, and the response time is long , Ash shunt, regulation characteristics are not good

Images