Problems and Solutions in the Application of Coal Conveyor Belt Scales in Power Plants

In thermal power plants, fuel costs constitute the majority of production costs. To reduce production costs, accurate, reliable, and stable measurement and management of coal used for power generation are crucial aspects and measures.

Coal conveyor belt scales in power plants are measuring devices used to weigh coal for fuel in power generation. Their measurement accuracy directly affects the coal consumption calculation and usage statistics of the fuel department, thereby influencing the fuel costs and economic benefits of the power plant.

However, in practical applications, several issues arise in the measurement work of coal conveyor belt scales, including large errors, significant discrepancies in comparison results, unstable measurement results, large dispersion in test data, significant zero-point deviation fluctuations, and unstable belt speeds.

For instance, in one line of a power plant's coal conveyor belt scale, the onboard physical coal load was 40.5 tons, while the belt scale instrument displayed 38.24 tons. In another line, the onboard physical coal load was 45.6 tons, but the belt scale instrument showed 45.98 tons. Problems such as inaccurate and unstable measurements and significant comparison discrepancies severely undermine the credibility of coal conveyor belt scales and affect the economic benefits of power plants.

Therefore, it is essential to identify the factors affecting the measurement accuracy of coal conveyor belt scales and take measures to resolve them.

Analysis of Factors Affecting the Measurement Accuracy of Coal Conveyor Belt Scales

Generally, various factors can influence coal conveyor belt scales. A thorough on-site environmental inspection is necessary, and the main factors can be summarized as follows:

1. Insufficient Belt Emptying Time: The belt is not thoroughly cleared of coal, leading to repeated measurements and inflated results. Given the long conveying distances of coal conveyor belts in power plants, all residual coal on the belt must be completely cleared to ensure accurate measurement. The exact emptying time should be determined based on actual observations.

2. Irregular Coal Unloading: Drivers simply dump coal from their vehicles into the pit, resulting in significant spillage on the ground and grid plates, which does not reach the conveyor belt. This leads to a discrepancy between the coal conveyor belt scale measurement and the actual onboard coal quantity, with the scale reading being lower.

3. Uneven Coal Distribution: Uneven dumping of coal results in an uneven coal flow, with some areas having excessive coal and others having insufficient amounts, even exceeding the measuring range of the coal conveyor belt scale.

4. Improper Closure of Separation Baffles: The separation baffles at the front end of the conveyor belt may not close tightly, causing coal to leak onto another belt during transfer, severely affecting the measurement accuracy of the coal conveyor belt scale.

5. Other Factors Affecting Measurement Accuracy: Belt deviation, inflexible rotation of belt idlers, inaccurate onboard weighing systems, and issues with belt scale calibration, such as non-standard chain code weights, inaccurate specifications, and non-compliant lengths.

Solutions to Address Inaccurate Measurements in Coal Conveyor Belt Scales

1. Ensure Accurate and Compliant Physical Coal Loading:

   - Thoroughly empty the conveyor belt and confirm no residual coal remains before loading physical coal.

   - Supervise the unloading process and residual coal cleanup throughout the coal loading procedure to ensure all coal enters the belt.

   - Dump coal slowly to maintain a uniform distribution on the conveyor belt and stable instantaneous coal flow during conveyance.

   - Confirm with boiler maintenance personnel that the separation baffles are tightly closed to prevent coal leakage.

2. Ensure Correct and Standardized Calibration Devices and Methods:

   - Adopt highly accurate calibration methods, such as physical calibration and chain code calibration.

   - Maintain the chain code properly, ensuring its weight and specifications meet standards, the lowering length is confirmed by the manufacturer and complies with regulations, and the limit switch for lowering operates sensitively and without abnormalities.

   - Calibrate the coal conveyor belt scale regularly according to the manufacturer's recommended calibration cycle and follow standard operating procedures.

3. Other Measures:

   - Thoroughly inspect and address issues such as belt deviation and inflexible rotation of belt idlers. Install belt tensioning devices and regularly lubricate the idlers.

   - Strengthen management and supervision of onboard weighing systems for coal to ensure their accuracy.

Certainly, to guarantee the measurement accuracy and stability of coal conveyor belt scales in power plants, the prerequisite is the quality and performance of the belt scales themselves, along with their ability to adapt to on-site conditions. Additionally, correct and reasonable installation of the coal conveyor belt scales is essential.