Brief Discussion on Monitoring of Safety Protection Device of Mine Air Compressor

Brief Discussion on Monitoring of Safety Protection Device of Mine Air Compressor

In the process of monitoring and inspecting the safety of air compressors in mining enterprises, the author found that more than 90% of the equipment was not equipped or not fully equipped with the temperature and pressure protection devices that should be configured. Research and analysis of the functions of each device and related regulations, and aim at various problems that may exist in the installation and use of the equipment.

This article discusses how to modify the original system by adding a series of electrical components or mechanical accessories at a specific location to meet the safety requirements, and then exclude the air compressor system from being affected by high temperature or high pressure. Of various accidents. In addition, this method can also prevent repeated investment and waste of funds. In order to ensure that the assembled safety protection equipment can function effectively and reliably, the article explains the relevant detection methods to improve the operability of the monitoring and inspection work and ensure that the detection data is true and reliable.

Mine air compressors are commonly used in mining enterprises to provide power for various construction and production machinery. However, in long-term use, due to technical and management issues, the investment in them is insufficient at the initial stage. The auxiliary equipment is not complete. In addition, a series of safety protection facilities supporting it also have varying degrees of lack, resulting in certain defects in the equipment. With the extension of the equipment’s use time, there are also some irregularities in use and improper maintenance during use, resulting in serious aging of the equipment. Production accidents caused by the above reasons are very common.

According to the relevant regulations on production safety, the air compressor is a major equipment for mining production, and it needs to be compulsory for regular safety inspections to ensure that the equipment can operate safely and reliably. In order to be able to do a good job in the safety inspection of mining air compressors, the relevant supervision department has established a series of inspection standards for safe production, and made detailed specifications and explanations on inspection methods and other content.

1 Existing problems

The first is pressure control. The equipped pressure release equipment is not perfect. Most of the equipment in use only has air bag safety valves without pressure relief valves. Secondly, more mining companies use piston air compressors, only the most The basic step-down start control loop is not equipped with the temperature, exhaust pressure and other safety protection devices that should be equipped; again, some large companies use screw air compressors with intelligent control systems, which can be automatically controlled, but there is no air bag The function of over-temperature protection still has potential production safety hazards.

Finally, due to the widespread inspection work, most mining companies renovate old equipment. At the same time, some electrical control equipment manufacturers are also conducting research, development and production of air compressor comprehensive protection equipment. However, because the complete sets of devices mostly use single-chip microcomputers for centralized control, the cost of the equipment is relatively high, which cannot match the price of ordinary air compressors.

In addition, some manufacturers of newly-developed equipment do not have a comprehensive understanding of the relevant requirements of the standard and the environmental conditions used, resulting in the products developed not being mature enough, and the usage rate is relatively low. Judging from the actual situation of the purchase and use of the device by a few companies, the main problems of the equipment include: there is no ability to protect the air bag from over-temperature, and the host and sensor are easily damaged or fail.

2 Modification method of existing situation

2.1 Pressure control protection device　

The pressure regulating device is a kind of equipment that the air compressor performs overpressure control when the exhaust pressure is too high. When the final exhaust pressure is higher than the rated pressure value, the control equipment will take certain actions to prevent the pressure Continuous increase. The pressure control device can effectively prevent the damage of the air compressor induced by overload and at the same time prevent the explosion induced by overpressure.

The pressure release equipment includes a safety valve installed on the air bag, a pressure relief valve installed on the air compressor and the air bag exhaust pipe, and the oil cut-off protection is required to be able to automatically be able to automatically when the pressure cycle oil pressure is lower than the specified standard value parking. As a result, the air compressor can be effectively prevented from exploding due to overpressure or overload.

　2.2 Over-temperature protection

The water-cooled air compressor can automatically stop when the cooling water is interrupted. The wind-drum over-temperature protection can ensure that it can automatically stop when the temperature inside the wind-drum is higher than 120°. Oil temperature over-temperature protection means that it can stop automatically when the temperature inside the crankcase is higher than 80°. Exhaust over-temperature protection requires the compressor to stop automatically when the compressor exhaust temperature is higher than the standard value. According to the functional requirements of each safety protection device, the problematic air compressor can be modified appropriately. For equipment without a pressure relief valve, the pipeline from the outlet of the air compressor to the first stop valve of the air bag pipeline or the outlet of the air bag can be appropriately modified. It is necessary to ensure that the diameter of the air outlet pipe is smaller than that of the pressure relief valve, and the pressure released by the pressure relief valve is greater than the pressure during normal operation of the safety valve. Generally, bursting discs are selected for pressure relief valves. In order to avoid premature damage to the bursting discs due to fatigue and other problems, its operating pressure is generally required to be between 1.25 and 1.4 times the maximum working pressure of the air compressor.

For screw air compressors that are not equipped with air bag over-temperature protection, they can be technically modified appropriately based on the above principles. Generally, it is necessary to install a temperature sensor on the air bag and connect it to the intelligent control of the air compressor In the system or integrated protection equipment.

For newly-purchased equipment, before the formal installation and operation, both the manufacturer and the equipment user must have a comprehensive understanding of the relevant requirements in the standard, and at the same time rigorously design and assemble the equipment based on the standard requirements to avoid The newly installed equipment has problems such as incomplete auxiliary equipment or parts, and incomplete safety equipment. 3 Safety protection device inspection method

According to the requirements of relevant regulations, various protection devices need to automatically act after the equipment reaches the specified standard value to achieve the safe operation of the protection equipment. For example, the standard value of the safety valve is less than or equal to 1.1Pe. Once the standard value is exceeded, the safety valve will automatically vent to release the pressure. The specified value of the wind envelope ultra-stable protection does not exceed 120 degrees. Once the specified value is exceeded, the equipment will stop operating.

When testing the temperature protection devices of lubricating oil over-temperature, air bag over-temperature, exhaust over-temperature and cooling function, the temperature sensing element can be taken out from the air compressor system and put in the auxiliary equipment oil. In the tank, the air compressor is started, the oil tank is heated manually to increase the oil temperature, and the oil temperature is measured with a standard temperature measuring instrument. At the same time, pay attention to observe the action behavior of the air compressor when the temperature reaches the standard value. If the air compressor does not operate when the temperature reaches the specified value or the operating temperature is higher than the specified standard value, then all can be determined as unqualified .

When testing pressure regulating devices and safety valves, first calculate the pressure value of each device when it is operating, and then replace the pressure gauge of the original machine with a standard pressure measuring instrument, and make the air compressor load and load manually. Pressurize and depressurize the discharged lubricating oil at the same time, and record the data measured by the standard instrument at this time. When the standard value is reached, check the change status of the valve and the air compressor system to ensure the reliability of the pressure protection equipment. If it reaches the specified standard value, if the protection device does not act, it will be deemed unqualified. When checking the exhaust pressure overpressure protection or oil cut protection, you can also manually pressurize the sensor in the same way, and then record the pressurization value while observing the actual situation of the air compressor.

Generally, the detection of the pressure relief valve is mainly to check the bursting pressure of the rupture disc, and a special set of devices in the laboratory can be used for testing. In addition, certain calculations are needed to determine whether the measured data can meet the requirements. In addition, the rupture disc should be replaced on time and regularly in actual use.

In actual work, the author has used the above methods to carry out a series of technical transformations on the air compressor. From the actual effect, the above methods are relatively simple to operate, temperature and pressure switches are easy to buy, and the cost is low. Realize the transformation. At the same time, the safety inspection and inspection method carried out in the transformation process has proved to be relatively simple and easy to operate through practical application, which can not only meet the requirements of standard testing, but also effectively improve the efficiency of inspection work.