Multistage separation circulating fluidized bed boiler for pure combustion of high-alkali high-chlorine coal and operation method

Abstract

The invention discloses a multistage separation circulating fluidized bed boiler for pure combustion of high-alkali high-chlorine coal and an operation method. The boiler comprises a hearth consistingof a hearth dense-phase area and a hearth dilute-phase area, wherein the hearth is divided into a first hearth flow, a second hearth flow and a third hearth flow; a first water-cooling U-shaped separator is arranged in the first hearth flow; a second water-cooling U-shaped separator is arranged at the connection transition part of the first hearth flow and the second hearth flow; a third water-cooling U-shaped separator is arranged in the third hearth flow; thick-wall light pipe buried pipes are distributed in the hearth dense-phase area; and a groove-shaped separator and a cyclone separatorare arranged at the outlet of the third hearth flow. According to the multistage separation circulating fluidized bed boiler for pure combustion of high-alkali high-chlorine coal, particles in smoke are efficiently separated through the multistage water-cooling U-shaped separators in the hearth, sodium salt compound steam of the smoke is condensed and separated out, and the operation temperature of the hearth is controlled between 750 DEG C and 820 DEG C, so that the problem that the boiler is forced to shut down due to contamination and slag bonding of the heating surface of the pure combustion of high-alkali high-chlorine coal of the boiler can be effectively solved, and long-term, safe and stable operation of the pure combustion of high-alkali high-chlorine coal of the boiler is realized.

Description

technical field [0001] The invention relates to a boiler, in particular to a multi-stage separation circulating fluidized bed boiler purely burning high-alkali and high-chloride coal and its operation method. Background technique [0002] Coal resources in Xinjiang account for 2 / 5 of China's total coal reserves, as high as 2.19 trillion tons, ranking first in the country. 95% of the total resources in the region are concentrated in Zhundong, Tuha and other places. Only Zhundong Coalfield has proven reserves of 213.6 billion tons of coal resources, and Shaerhu Coalfield has proven reserves of coal resources of 90 billion tons. Zhundong and Shaerhu coals have high volatile content (more than 30%), medium calorific value (14MJ / kg-19.5MJ / kg), low ash content (below 10%), low sulfur content (0.2%-0.3%), etc. Advantages, but the raw coal is lumpy, easily crushed and weathered, easily ignited and spontaneously combusted, high moisture (more than 20%), low ash melting point (softe...

AI Technical Summary

Problems solved by technology

[0009] 1. Contamination and slagging of the convection heating surface at the tail;

[0010] 2. The ash melting point is low (ST temperature is not higher than 1180°C), the furnace combustion area is contaminated and coked, and the bed material is stuck and agglomerated;

[0011] 3. High-alkali and high-chlorine coal has less ash content (less than 10%) and is easily broken (fine powder with a particle size of less than 1mm accounts for 40%). Therefore, the bed material will continue to decrease. After a period of time, if the bed material is not added in time material, the gray balance will be destroyed, and it will be difficult for the boiler to continue to operate normally

[0012] In addition, due to the high concentration of fly ash and the extremely fine particle size of the fly ash (less than 150um accounts for 60%), the efficiency of the cyclone separator is reduced, and a large amount of fly ash is brought into the tail heating surface, which intensifies the slagging of the tail heating surface, Dust accumulation, wear and tear

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