Cold smoke recirculation unit heat transfer oil recovery bypass flue gas heat system and control method

Abstract

The invention discloses a heat conduction oil recovery bypass flue gas heat system of a cold smoke recirculation unit, comprising a bypass flue gas cooling device, a recirculation cold smoke heating device, a closed circulation oil pump, a heat conduction oil replenishment system, and an adjustment baffle door , the air preheater and the boiler body; the first inlet of the bypass flue gas cooling device communicates with the exhaust port through the adjustment baffle door, and the first outlet of the bypass flue gas cooling device communicates with the smoke outlet of the air preheater ;The bypass flue gas cooling device is in circulation communication with the recirculation cold smoke heating device; The second outlet of the smoke heating device is connected, the output end of the closed circulation oil pump is connected with the second inlet of the bypass flue gas cooling device; the output end of the heat transfer oil replenishment system is connected with the eighth pipeline, which is used to provide supplementary heat transfer oil circulation medium ; The smoke inlet of the air preheater communicates with the smoke outlet of the boiler body.

Description

technical field [0001] The invention relates to the field of unit efficiency improvement, in particular to a heat conduction oil recovery bypass flue gas heat system and control method of a cold smoke recirculation unit. Background technique [0002] Flue gas recirculation is a common method used to regulate the outlet steam temperature of the reheater when burning ashless fuel or low ash fuel. At present, the large-scale coal-fired units that use flue gas recirculation to adjust the outlet steam temperature of the reheater are mainly secondary reheat units. The double reheat unit is an advanced coal-fired power generation technology that is internationally mature, efficient, and low-pollution. It has good economic benefits and environmental protection characteristics, and has broad development prospects in my country. [0003] Cold smoke recirculation is to draw part of the cold flue gas (temperature is about 70-150 ℃) from the dust collector or induced draft fan with a re...

AI Technical Summary

Problems solved by technology

According to the second law of thermodynamics, heat changes from high-grade sensible heat of furnace flue gas to high-grade sensible heat of feed water and low-grade sensible heat of condensate water, and there is a certain irreversible loss of energy work ability, and the overall utilization efficiency of flue gas sensible heat limited

Therefore, it is unreasonable to use the existing air preheater bypass flue system to recover the excess flue gas heat of the cold smoke recirculation unit

[0008] (2) The flue gas exchanges heat with the low-pressure condensate and high-pressure feedwater in the bypass flue, which is equivalent to the parallel operation of the condensate heat exchanger and the low-pressure heater, and the parallel operation of the feedwater heat exchanger and the high-pressure heater. The water side system The design is more complicated; at the same time, the flow / temperature of feed water, the flow / temperature of condensate, and the flow / temperature of bypass flue gas are all system variables, and the automatic control operation is more complicated

When the cold smoke is sprayed into the furnace from the cold ash hopper at the lower part of the boiler, due to the large temperature difference between the temperature of the cold smoke and the temperature of the furnace, the stable combustion conditions of the boiler are easily affected, which affects the combustion of fuel.

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