The total amount of secondary air of the boiler participates in the main protection of the boiler air volume, especially in the early stage of boiler start-up, when the furnace is purged, the air volume fluctuates greatly, which can easily lead to the interruption of the purging, and the long-term purging makes the furnace temperature drop rapidly and the ignition is difficult. Another phenomenon, I don't know if you have found it, the total amount of secondary air on the left and right sides of the furnace generally deviates by about 70t h, and some can even deviate by 200t h
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The total air volume on one side of the secondary wind is generally installed on the upper, middle and lower parts of three with a total of nine venturis, and the venturi pipes are drawn out to the upper part of the secondary air duct according to the flow direction of the secondary air to the high and low pressure sides, and the nine impulse pipes on the high and low pressure sides are summarized on a mother pipe, which is the layout of the total air volume measurement of the secondary air.
After inspection, three main problems were found: first, there was more ash accumulation at both ends of the venturi tube on the high and low pressure side pressure pipesSecond, the instrument joint connected between the secondary air total flow transmitter and the pressure pipeline adopts a high-pressure instrument joint, which has a small aperture and a small air intake during purging, which is difficult to ensure the purging effectThird, the pressure taking pipeline on the high and low pressure side of the venturi tube is connected to the mother pipe, and the active acceptance force is large, and there is air leakage.
This is a common problem of most of the secondary air total air volume measurement devices, if you simply rely on the regular purging of thermal workers, the workload is large, and the secondary air main protection needs to be withdrawn frequently, which affects the safe operation of the boiler. Therefore, it was simply transformed, and the pressure taking pipelines on the high and low pressure sides of the three secondary air total flow transmitters on one side were centrally arranged in the middle of the pressure taking pipes on the high and low pressure sides of the venturi tube, and the middle parts of the pressure taking pipes on the venturi side were evenly distributed on the pressure taking pipes on the high and low pressure sides of the venturi tube. This ensures that the entire mother pipe can be purged in place without dead angles during purging, and the ash in the mother pipe can be blown back into the secondary air duct during the blowing. The union is changed to an ordinary union with a large aperture, which increases the air intake volume of the pressure pipe of the purge transmitter and replaces the gasket at the leakage part, the effect is more obvious, but the deviation on both sides of the total secondary air volume still exists, but the range is greatly reduced compared with before.