Hidden arm coal powder sampling device

1、 Overview of Hidden Arm Coal Powder Sampling Device
The hidden arm type coal powder sampling device is a specialized equipment for sampling coal powder on the primary air supply pipeline of a positive pressure direct blowing coal powder system. In the daily operation of the coal mill, the wear of the grinding parts, changes in coal type and block size, and significant changes in coal powder fineness will directly affect the combustion efficiency of the boiler and increase power generation costs. Therefore, regular sampling and testing of coal powder fineness is necessary. When the coal powder fineness exceeds the design value, the grinding parts of the coal mill should be adjusted or replaced in a timely manner, or the opening of the separator should be adjusted to achieve the design requirements for coal powder fineness.

The accurate control and analysis of coal powder fineness in coal-fired boilers in power plants is of great significance for the safe and economical operation of boiler units. At present, the application of positive pressure direct blowing powder production systems in large units is increasing. Due to the fact that the coal powder at the outlet of the coal mill is directly sent to the furnace for combustion by positive pressure primary air, daily coal powder sampling is very difficult. The self spraying method is generally used, which has poor sampling accuracy and is often difficult to seal properly, resulting in coal powder leakage. The working environment is poor and the labor intensity is high. Huaneng Power Auxiliary Equipment has decades of experience in theoretical testing and engineering application research of gas-solid two-phase flow. The latest developed rotary arm coal powder sampling device can conveniently achieve constant velocity sampling of coal powder in positive pressure direct fired powder production systems. Its biggest feature is multi-point simultaneous constant velocity sampling, which makes the collected powder samples representative, with good repeatability of multiple sampling, simple operation, and no coal powder leakage. It greatly improves the working environment and reduces labor intensity. It is currently the most ideal device for daily coal powder fineness analysis sampling in positive pressure direct fired powder production systems for power plant boilers internationally.

The rotary arm coal powder sampling device, as shown in the attached figure, mainly consists of a sampling tube installed at the center of the shell on the coal powder pipeline and an external extraction and separation device. The sampling tube can rotate around the support axis. When sampling, rotate it to a position perpendicular to the pipeline, so that the nozzle installed on the sampling tube is facing the coal powder airflow; After sampling, return the sampling tube to a parallel position with the pipeline, avoid coal powder airflow, and prevent wear and tear; Using compressed air blowing can prevent coal powder from entering the center of the shell and sampler and causing blockage, ensuring reliable operation without maintenance.   

2、 Performance characteristics of hidden arm coal powder sampling device
Multi point simultaneous isokinetic sampling, convenient and fast, with good representativeness of sampling; Fixed installation on the coal powder pipeline, rotating to the measurement plane during sampling. The sampling gun is usually placed outside the coal powder airflow, with low wear and long service life; Compressed air blowing is used to avoid clogging of the sampler.

3、 The main components of the hidden arm coal powder sampling device
The device components include: sampling head, sampling tube, purge valve, sampling valve, external handle, separator, air valve, sample collection bottle, pressure gauge, sealed chamber, etc.
1. Sampling head: placed in the coal powder pipeline during sampling, with the sampling hole facing towards the direction of coal powder airflow, and the gas powder mixture entering the sampling device through the sampling hole;
2. Sampling tube: The gas powder mixture taken by the sampling head is transported to the cyclone separator through the sampling tube;
3. Blow valve: Before and after each sampling, open the blow valve to use compressed air to blow the sampling pipeline to prevent it from being blocked by coal powder;
4. Sampling valve: When sampling, adjust this valve to draw air from the separator through the negative pressure formed by the compressed air discharged from the outlet, so that the coal powder in the air duct enters the sampling device through the sampling hole;
5. Separators: for solid gas separation, the separation process is as follows: coal powder is thrown onto the inner wall of the separator by the rotating airflow, and falls into the sample collection bottle due to its own gravity; The gas flows down the wall from top to bottom, then rises in the middle to the top, and is discharged through the outlet;
6. Sample collection bottle: Collect and store solid coal powder samples separated by the separator,
7. Pressure gauge: displays pressure data of air pressure regulating valve;

4、 Working principle of hidden arm coal powder sampler

1. Sampling working principle: The hidden arm fixed coal powder sampler is successfully developed by using negative pressure suction and cyclone separation principles to extract the gas powder mixture from the coal powder pipeline and perform solid gas separation. During the sampling process, the sampling tube is extended into the coal powder pipeline, and all valves are in the open state. When compressed air passes through the injector and extractor from the exhaust pipeline, its jet action will inevitably cause negative pressure in the cyclone separator, sampling tube, sampling bottle and other components, prompting the gas powder mixture in the coal powder pipeline to enter the sampler along the sampling tube. The gas powder mixture undergoes solid gas separation in the cyclone separator, and the separated coal powder falls into the sampling bottle below the cyclone separator. The gas is then sucked by compressed air and sent back to the coal powder pipeline. The entire operation process does not cause pollution to the workplace. Adjusting the compressed air pressure regulating valve before sampling can achieve constant velocity sampling, making the extracted coal powder samples representative. The compressed air pressure generally does not exceed 0.1Mpa.

2. Anti blocking measures: During the use of the equipment, compressed air can be used to blow the sampling tube to prevent it from being blocked by coal powder.

3. Anti wear measures: When not sampling, the sampling tube is hidden in the outer shell and placed outside the coal powder pipeline. When sampling, pull the sampling lever and unfold the sampling tube in the coal powder pipeline. The sampling port should face the coal powder airflow, and all valves should be opened to start sampling. After sampling is completed, pull the sampling lever to hide the sampling tube in the outer shell and place it outside the coal powder pipeline to avoid the erosion of the sampling tube by the coal powder airflow and achieve the purpose of anti-wear.

5、 Ordering Notice for Hidden Arm Coal Powder Sampler
Provide the diameter of the coal powder pipeline for designing the length of the sampling gun.
 

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