Circulating fluidized bed boiler furnace having bottom-inserted secondary air pipe

Abstract

The invention provides a circulating fluidized bed boiler furnace having bottom-inserted secondary air pipes. An air-distribution plate, which is used for providing primary air, is arranged on a bottom of the furnace. A side-inserted secondary air pipe is disposed on a water-cooling wall of a side wall of the furnace above the air-distribution plate. The air-distribution plate is provided with a plurality of the bottom-inserted secondary air pipes which vertically pass through the air-distribution plate. Through arrangement of the plurality of the bottom-inserted secondary air pipes, which vertically pass through the air-distribution plate, on the air-distribution plate on the bottom of the furnace, secondary air can be directly fed into a central zone of the furnace, thereby enhancing a mixing performance between the secondary air in the circulating fluidized bed boiler furnace and a main flow, improving an oxygen-supplement situation in the central zone in an upper part of the furnace and increasing a combustion efficiency.

Description

technical field [0001] The invention relates to a circulating fluidized bed boiler structure, in particular to a circulating fluidized bed boiler furnace with a bottom inserted secondary air pipe. Background technique [0002] The primary air of the traditional circulating fluidized bed boiler 9 is supplied from the air distribution plate 91 at the bottom of the furnace, and the secondary air is arranged on the water-cooled wall surface 92 of the furnace side wall above the air distribution plate 91, such as image 3 As shown, the secondary air pipe 93 is arranged on the water-cooled wall surface 92 . For small-capacity industrial boilers, this arrangement of secondary air can basically meet the needs of fuel combustion in the furnace, but as the boiler capacity increases, the cross-sectional area of ​​the furnace also increases accordingly, and it is difficult for the secondary air to inject into the upper furnace cross-section. In the central area, a central oxygen-poor zo...

AI Technical Summary

Problems solved by technology

But this application has the following disadvantages: 1) after the air distribution plate at the bottom of the furnace is designed as a ring, the floor area of ​​the boiler increases; 2) the design of the polygonal, elliptical, and circular furnace section leads to an increase in the cost of the water-cooled wall; 3) inside the furnace The stability of gas-solid two-phase flow has not been verified by engineering practice, and there are certain application risks

But this application has the following disadvantages: 1) The part where the upper secondary air pipe is inserted into the furnace intersects with the main flow direction in the furnace, which is easy to wear and fall off, and the fallen pipe may hinder the bed material fluidization and furnace slagging; 2) The bed material particles It is easy to reverse into the primary air insertion pipe, causing blockage in the bottom air chamber; 3) For circulating fluidized bed boilers with a large cross-sectional area, the insertion depth of the secondary air pipe (0.81.5 meters) still cannot meet the oxygen supply in the center of the furnace 4) The static pressure at the outlet of the primary air insertion pipe is low, and the primary air pressure is too high in comparison, which is not conducive to energy saving of the fan; 5) The primary air volume of the insertion pipe cannot be adjusted, which affects the uniformity of the air distribution plate Not verified by engineering

However, this application has the following disadvantages: 1) The cross heating panel must communicate with the water-cooled wall, which is a part of the furnace water-cooled wall, so it is limited by the layout of the water-cooled wall pipes, and cannot be flexibly arranged based on the combustion conditions in the furnace, and cannot be applied to existing boilers. Renovation; 2) Since the cross-screen vertically runs through the entire boiler furnace, if the cross-sectional area of ​​the cylindrical air duct at the lower part of the cross-screen is small, the strength of the heating surface will be insufficient, and transverse fracture and damage will easily occur during operation, resulting in shutdown of the unit; 3) Two The secondary air outlet is opened at the let-off pipe on the wall of the cylindrical air duct, which is consistent with the setting method of the secondary air outlet of the traditional water-cooled wall, which is prone to reverse flow of bed material and block the air duct; 4) If the cross-section of the cylindrical air duct at the lower part of the cross screen is large, Then it is equivalent to the technology of the invention application with the aforementioned publication number CN102147106A; 5) the transition zone between the cross screen and the cylindrical air duct is prone to eddy currents, which leads to aggravated wear of the local heating surface

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