How to save the maintenance cost of air compressor

1. Introduction

There are 8 screw air compressors in the power plant of a Chemical Co., Ltd. in Jiangsu Province, which are responsible for the supply of instrument air, dust removal air, power air, gas for secondary desulfurization and nitrogen generation in the four plants of coal preparation, coking, purification and power. Although they are auxiliary systems, once there is a problem in gas supply, it will affect the production system of the whole company. Therefore, the stable operation of the air compressor is very important Yes. And the maintenance cost of air compressor is the cost that must be paid. How to reduce the maintenance cost of air compressor becomes the primary problem. Among the 8 screw air compressors, 1 and 2 are produced by a company in Shanghai, and 3, 4, 5, 6, 7 and 8 are produced by a company in Beijing, but their working principles are basically the same, and the service life of vulnerable spare parts is slightly different. This paper takes an air compressor of a company in Beijing as an example to discuss how to reduce the maintenance cost by establishing a planned maintenance mode for the air compressor and improving the filter element.

2. Establishment of planned maintenance mode for air compressor

In the daily troubleshooting of air compressor, the most common failure is the high exhaust temperature and large oil consumption, and the most common cause of high exhaust temperature is the blockage of oil filter element, the overtime use of air compressor oil and the dirty or blocked surface of cooler, the most common cause of large oil consumption is the rupture of oil fine separator element. The oil filter element and the oil fine separator element belong to the vulnerable spare parts of the air compressor. In addition, the air filter element and the air compressor oil need to be replaced regularly.

(1) The recommended operation time of air filter element is 1500h, and it needs to be cleaned regularly. Generally, it needs to be purged once every 2-4 weeks, and the air source below 2kg should be used for purging.

(2) It is recommended to replace the oil filter element after 3500h operation, or when the filling pressure is lower than 0.25MPa.

(3) It is recommended to replace the oil separation filter element after 5000h operation, or if the oil differential pressure exceeds 0.055mpa, it is recommended to replace it.

(4) It is recommended to run the air compressor oil for 2000h for sampling analysis and decide whether to replace it according to the test results.

3. Improvement of filter element of air compressor

3.1 Improvement of air filter element of air compressor

Before the air enters the system, it passes through the air filter first, so the quality, filtering accuracy and convection area of the air filter element directly affect the service life of the unit oil system (including oil filter element, oil separation element), bearings, rotors and other head equipment.

The filter of the air compressor filters out all the fine dust and particles from the outside, which is the first protective filter element of the air compressor. In order to prolong the service life of other vulnerable spare parts of the air compressor, after searching the data and consulting the manufacturer, we changed the original air filter with the filtering accuracy of 10 μ m to the air filter with the filtering accuracy of 3 μ M. The accuracy is changed. In order not to affect the convection area and gas production, the original air filter is lengthened by 20cm, and the corresponding installation parts are lengthened. After put into use, the service life of air compressor oil filter element is obviously prolonged.

3.2 improvement of oil filter element

The oil filter can filter the impurities in the internal oil system of the air compressor to protect the unit. It is the second filter element of the air compressor. The average service life of the built-in oil filter element is about 1000h. The service life of air filter is improved after improvement, but there are still oil filter blockage, oil injection pressure drop, resulting in the increase of unit temperature and exhaust temperature.

In order to further extend the service life of the oil filter, we read a large number of data, learn from other types of oil filters, and finally change the original one built-in oil filter to two external oil filters in parallel. The price of one built-in oil filter is about 1660 yuan, and the price of two external oil filters is about 1440 yuan. The cost of the improved oil filter does not increase, but the service life is greatly improved. At present, the service life of the oil filter used by the operating units has exceeded 2000 hours, and the maximum service life has reached 6000 hours. There is no oil injection pressure drop phenomenon, and the effect is very good.

3.3 influence of two kinds of filter elements of air compressor after improvement

The fine oil separator is a device for separating the residual oil in the compressed air. With the increase of unit operation time, there will be slime on the surface of the filter element of the oil fine separator, which will gradually increase the differential pressure of the oil, and the power consumption of the unit will also increase with the increase of the differential pressure of the oil. Moreover, if the oil differential pressure is too large, the filter element of the oil fine separator will be damaged and the oil content of the compressed air will be high, which will not only lose the oil in the unit, but also cause the alumina of the follow-up equipment dryer and the carbon molecular sieve of the nitrogen generator to be poisoned due to the high oil content of the air inlet.

If the oil filter element of the air compressor is newly replaced, its oil differential pressure is 0.01-0.02mpa, and the oil filter element has been running for about 2000h, its oil differential pressure is 0.03-0.04mpa, the power consumption of the air compressor with the new oil is low, and the power consumption of the air compressor running for a long time is high. Therefore, the oil differential pressure of the filter element of the oil fine separator should not be too high, nor should it be damaged. It needs more than 8000 yuan to replace one oil filter element. It is very meaningful to extend its service life properly to reduce the maintenance cost of the air compressor.

The use of air compressor coolant directly affects the quality of the whole unit, and the price is expensive. It is more meaningful to extend the service life of air compressor coolant.

After the air filter and oil filter of the air compressor are improved, the service life of the oil filter is not only prolonged, but also the service life of the filter element of the oil fine separator and the coolant of the air compressor. The average service life of the filter element of the oil fine separator and the coolant of the air compressor before the transformation of the filter element of the air compressor is about 4000H.

After the improvement of air compressor filter element, the oil separation filter element of each unit has now exceeded 5000h, without the increase of oil differential pressure and the damage of oil separation, which has not affected the power consumption of air compressor and the quality of subsequent air source; the service time of air compressor coolant has also exceeded 5000h, and all indexes of sampling analysis results have not exceeded the standard, so it can continue to be used.

4. Conclusion

According to the annual expenses incurred before and after the improvement of vulnerable spare parts of air compressor, ensuring that the air filter element is not damaged can extend the service life of oil, oil and oil filter, protect the parts in the unit from damage, and the price of air filter is cheap. The replacement cycle of air filter is fixed to replace after the operation of 1500h, so the maintenance cost of this part of air filter is relatively fixed. By consulting the maintenance record, the average number and cost of parts replacement per year for each equipment before improvement, it is found that after improvement, the service life of oil filter is calculated as 3500h, and the service life of oil and coolant is calculated as 5000h, the number and cost, in which half a barrel is required for every time of coolant replacement.

The annual maintenance cost of the air compressor before the transformation is 318706.2 yuan, and the annual maintenance cost of the air compressor after the transformation is 208143 yuan. It is estimated that the annual maintenance cost of the equipment can be saved by 110563.2 yuan after the improvement of the air compressor filter element is calculated.