Constant speed sampling method and sampling device of pulverized coal

Abstract

The invention discloses a constant speed sampling method and sampling device of pulverized coal. The sampling method comprises the following steps: measuring flow velocity of the pulverized coal in apulverized coal pipeline and the pulverized coal pumped into a sampling pipe by adopting an electrostatic speed measurement way, and regulating gas extraction pressure in the sampling pipe to ensure that sampling is carried out when the flow velocity of the pulverized coal is equal to that of the other pulverized coal; the sampling device comprises a negative pressure gas extraction mechanism forpumping the pulverized coal in the pulverized coal pipeline into an inner cavity of the sampling pipe, a gas extraction pipe, a sampling collection mechanism, an electrostatic speed measurement mechanism, and a PID (Proportional-Integral-Differential) adjustment mechanism, wherein a gas extractor is mounted between the gas extraction pipe and the sampling pipe; the sampling collection mechanism isused for collecting the pulverized coal which enters into the sampling pipe; the electrostatic speed measurement mechanism is used for measuring the flow velocity of the pulverized coal in the pulverized coal pipeline and the pulverized coal pumped into the sampling pipe; the PID adjustment mechanism is used for adjusting gas extraction pressure in the sampling pipe so that the flow velocity of the pulverized coal in the pulverized coal pipeline is equal to the flow velocity of the pulverized coal in the sampling pipe. The constant speed sampling method disclosed by the invention is suitablefor sampling the pulverized coal in a primary air pipe, accurate constant speed sampling is realized, sampling errors can be reduced, and sampling of the pulverized coal has representativeness; the sampling device has a simple structure and is convenient to operate.

Description

technical field [0001] The invention relates to the technical field of coal powder sampling, in particular to a constant-speed sampling method and a sampling device for coal powder. Background technique [0002] With the gradual improvement of the country's environmental protection and energy-saving requirements for thermal power generating units, large-scale units using direct blowing pulverization systems have been widely used. In the direct-blowing pulverization system, a coal mill has multiple pulverized coal pipelines at the same time, and the pulverized coal flow rate, concentration, and fineness of each pulverized coal pipeline are different, and these economic parameters always affect the power plant boiler. Therefore, real-time and accurate sampling of pulverized coal is required for measurement, so as to properly adjust and maintain the boiler equipment, improve the safety of the boiler and the economy of the power plant operation. Sampling of pulverized coal has ...

AI Technical Summary

Problems solved by technology

[0015] 1. The above constant-kinetic sampling method is established under the theoretical premise that the resistance is negligible, which is difficult to establish in reality;

[0016] 2. Since the first pressure measuring hole 2' and the second pressure measuring hole 3' are easily blocked, constant velocity cannot be achieved, which affects the accuracy of sampling;

[0017] 3. In fact, there is a speed difference in the 4' section of the pulverized coal pipeline, so the constant velocity process does not hold;

[0018] 4. Sampling on the plane formed by the first pressure measuring hole 2', the second pressure measuring hole 3' and the axis is parallel to the air flow line in the pulverized coal pipeline 4'. When sampling at other points, the sampling probe 1 ' presents a certain angle to the airflow in the pulverized coal pipeline 4', and the outermost point is 21°-23° to the airflow, resulting in sampling error;

[0019] 5. When sampling the horizontal pipe of the pulverized coal pipeline 4', if pulverized coal deposits occur, the sampling volume will seriously deviate from the actual distribution due to the suction and deposited pulverized coal, which will affect the representativeness of pulverized coal sampling;

[0020] 6. The structure of the sampling device is complex, and the design of automatic balance and purge is relatively complicated; the sampling time required for the test is very long and the workload is heavy

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