Retractable arm coal powder sampling device

I. Overview

Retractable arm coal powder sampling device, designed for coal powder sampling on the primary air conveying pipeline of a positive pressure straight blowing coal powder system. During the daily operation of the coal mill, the wear of the grinding components, changes in coal type and size, and variations in coal powder fineness can significantly affect the boiler's combustion efficiency, increasing power generation costs. Therefore, regular sampling and testing of coal powder fineness are necessary. When the coal powder fineness exceeds the designed value, timely adjustments or replacements of the coal mill grinding components or the adjustment of the separator's deflection door opening are required to achieve the desired coal powder fineness.

II. Product Features and Structural Forms

This product utilizes compressed air as its power source to create a vacuum in the sampling tube, separator, and sampling bottle, thereby aspirating coal powder for sampling purposes. It also employs compressed air to sweep the sampling tube to prevent clogging. The equipment is equipped with a pressure regulating valve for compressed air, which can adjust the pressure and flow of the compressed air to control the sampling speed and achieve uniform sampling, ensuring the coal powder collected is representative. The sampling tube features an integrated arm design, which keeps the tube vertically concealed outside the coal powder pipeline when not in use, avoiding the impact of the coal powder airflow on the tube, significantly extending the tube's service life. The integrated arm-type coal powder sampling device mainly consists of the following components:

Sample Tube — Extends into the coal powder pipeline, with the sampling port facing the direction of the coal powder airflow. The coal powder enters the sampling device through it. Sampling is multi-point sampling.

2. Sampling Bottle - For concentrating and storing coal powder samples separated by the cyclone separator, for calibration purposes.

3. Cyclone Separator – Separates solid-gas mixtures, with coal powder being thrown to the wall by the rotating air stream due to gravity, and then falling into the ash collector. The separated gas rises along the central path to the top and is discharged through the top exhaust outlet. It is then suctioned by the ejector and re-injected into the coal powder pipeline, achieving separation of coal powder and gas.

4. Quick-connect coupling for easy assembly.

5. Intake short pipe — for connecting compressed air.

6. Air Compressor Control Valve - Controls the on/off of compressed air.

7. Pressure Regulating Valve for Compressed Air – Adjusting this valve controls the pressure and flow rate of compressed air, governing the speed of sampling. It enables uniform sampling speed.

8. Suction Pump for Sampling — Driven by compressed air, it creates negative pressure in the sampling tube, cyclone separator, and sampling bottle, allowing the coal powder to smoothly enter the cyclone separator for solid-gas separation.

9. Blow-off Valve – Compressed air enters the coal powder pipeline through this valve.

10. Sampling Handle – Operating this handle will extend or retract the sampling tube.

11. Sampling Valve — Open or close this valve to control sampling or blowback of the sampling tube to prevent clogging.

12. Shell Body – Installed on the coal powder pipeline, the sampling tube is concealed within when no sampling is taking place.

III. Working Principle

1. Sampling Principle

The concealed arm type fixed coal powder sampling device is developed by utilizing the principles of negative pressure suction and cyclone separation to extract the gas-powder mixture from the coal powder pipeline and achieve solid-gas separation. During the sampling process, the sampling tube is extended into the coal powder pipeline, with all valves in the open position. As compressed air passes through the exhaust pipeline and the ejector vacuum pump, the jet action inevitably creates negative pressure in the cyclone separator, sampling tube, and sampling bottle components, prompting the gas-powder mixture in the coal powder pipeline to flow into the sampling device through the sampling tube. The gas-powder mixture undergoes solid-gas separation in the cyclone separator, with the separated coal powder falling into the sampling bottle below the separator, and the gas being suctioned back into the coal powder pipeline by the compressed air. The entire operation process does not produce pollution in the workplace. Before sampling, adjusting the pressure regulating valve for the compressed air allows for isokinetic sampling, ensuring that the collected coal powder sample is representative. (The compressed air pressure is generally not more than 0.1 Mpa.)

2. Anti-blockage Measures

During equipment operation, compressed air can be used to blow clean the sampling tube to prevent it from being blocked by coal powder.

3. Abrasion Prevention Measures

When not sampling, the sampling tube is concealed within the housing, positioned outside the coal powder pipeline. To sample, pull the sampling operation lever to extend the sampling tube into the coal powder pipeline, with the sampling orifice facing the coal powder airflow direction. Open all valves to begin sampling. After sampling, pull the sampling operation lever to hide the sampling tube back within the housing, placing it outside the coal powder pipeline to prevent the coal powder airflow from washing over the tube, thereby achieving wear protection.

Section 4: Operating Procedures

1. Sample collection

Before sampling, all valves are closed; first, open the compressed air control valve 6; adjust the compressed air pressure regulating valve 7 according to the pressure gauge to reach the required pressure range. Pull the sampling operation lever 10; extend the sampling tube into the coal powder pipeline; open the flushing valve 9; open the sampling valve 11; start sampling for 2 to 4 minutes; close the compressed air control valve 6, the flushing valve 9, and the sampling valve 11; pull the sampling operation lever 10; hide the sampling tube in the housing 13; remove the sampling bottle 2; remove the coal powder sample and place the sampling bottle back in its original position, ensuring a tight seal at the connection.

2. Blow-off

Open the compressed air control valve 6; close valve 9 for blowdown; open valve 11 for sampling; compressed air will flush the sampling tube through valve 11.

V. Performance Features

1. The product is made entirely of stainless steel, featuring a clean, compact design with a long overall lifespan.

2. Simple structure, no mechanical moving parts, maintenance-free. Sampling is simple and convenient.

3. Employing multi-point, isokinetic sampling, the coal powder samples extracted are representative.

4. Compressed air blowing can be used to clean the sampling tube, preventing coal dust from blocking it.

5. Fixed securely on the coal powder pipeline, sealed tightly with no coal powder leakage, and does not pollute the working environment.

6. Place the sampling tube into the coal powder pipeline during use. After collecting the coal powder sample, it can be concealed outside the pipeline to avoid the scouring of the coal powder airflow, ensuring a long service life.

7. One person operation, with minimal labor intensity required.

Section 6: Installation Requirements

Provide compressed air of 0.4—0.6 MPa on-site.

2. The equipment is vertically mounted on the coal powder pipeline at the operating platform level of 1000-1500mm, featuring an installation hole of 500×40mm (length×width) (specific dimensions are calculated based on the coal powder pipeline parameters), and the fixed outer casing is焊接mounted with a flange.

Section 7: Order Instructions

Provide the diameter and wall thickness of the coal powder pipeline when placing an order.

2. Operation Method (Electric, Manual).

Section 8: Model Description

Model: MF-XXX, where MF denotes coal powder and XXX is the diameter of the coal powder pipeline

Section 9: Product Outline Diagram

Concealed Fixed Coal Powder Sampling Device Outline Diagram

1. Sampling Tube 2. Sampling Bottle 3. Cyclone Separator 4. Connecting Elbow 5. Steam Inlet Short Pipe 6. Compressed Air Control Valve 7. Compressed Air Pressure Reducing Valve 8. Injector Vacuum Pump 9. Blow-Down Valve 10. Sampling Operation Rod 11. Sampling Valve 12. Positioning Handwheel 13. Housing

Hidden type fixed coal powder sampling device installation diagram

1. Pressure Reducing Valve for Compressed Air 2. Cyclone Separator 3. Sampling Operation Rod 4. Connecting Swivel Fitting 5. Positioning Handwheel 6. Sampling Bottle 7. Hidden Sampling Tube 8. Enclosure Shell 9. Installation Flange 10. Multiple Sampling Points 11. Sampling Tube During Sampling 12. Coal Powder Pipeline