Research and Solution on the Reasons of High Exhaust Gas Temperature of Nitrogen Press

1 Fault Overview Three months after the nitrogen turbine compressor was officially put into operation, the four-stage exhaust gas temperature continued to rise, approaching the interlocking shutdown value.

2 Fault judgment (1) The single-stage four-stage exhaust gas temperature is high, reflecting that there is no problem in the working condition of the entire circulating water system; (2) After detecting the inlet and outlet water temperature of the cooler, the inlet water 23, the drainage 42 The temperature difference of 19 has exceeded the standard of designing the inlet and outlet water temperature of 14, and it is preliminarily judged that there is insufficient cooling water in the four-stage cooler; (3) the infrared temperature measuring gun is used to check the temperature value of the inlet gasket of the stage cooler of the stage is 23 5, The temperature of the volute in the vicinity of the water flow direction is about 24, such a small temperature deviation, indicating that there is leakage of the door type rubber pad, and part of the cooling water is bypassed from the water inlet to the water return port.

3 failure mechanism analysis

(1) The circulating water supply pressure is low or the water supply temperature is too high to meet the nitrogen cooling requirements of the compressor. The relevant data is transferred from the DCS. The circulating water supply pressure of this stage is 0 35 MPa, and the water supply temperature is 23 (design requirements: pressure > 0 30 MPa, temperature < 33). The circulating water supply fully meets the working conditions.

(2) The tube bundle of the cooler of the compressor is easy to block the structure of the compact arrangement. The CENTAC compressor cartridge cooler is located in the middle of each compression stage. The cooler is annular, the water flows outside the tube, nitrogen flows inside the tube, and nitrogen flows countercurrently to the water. There are fins in the tube, nitrogen passes through the tube, and the cooling water flows in the opposite direction while outside the tube. Such a structure has a very high heat exchange efficiency. The tube bundle is compactly arranged, and the gap between the shells is narrow (no more than 2 mm), causing sludge, impurities, suspended matter, etc. in the circulating water to accumulate and be stuck in the shell. The water quality conditions of the circulating cooling water of the factory are compared with the water supply requirements of the compressor as follows: (a) The total hardness is indicated by CaCO 3 to be less than 100 PPM (actual value 480 PPM); (b) The acid is 6 0 8 0 PH range (actual value 8 89); (c) suspended matter does not exceed 50 PPM (actual value 85 PPM); (d) langelier saturation index should be between + 5 0 + 1 0 (the factory does not do this data statistics). In general, the CENTAC compressors should be soft, clean and free of corrosive ingredients. Compared with the measured values ​​of the circulating water indicators and the equipment demand values, the water quality conditions obviously cannot meet the water supply requirements of the compressor. The high suspended solids cause the cooler shell to clog. The normal life cycle of the compressor cooler is shortened. To this end, a Y-type filter is installed on the circulating water main pipe of the compressor. However, due to water quality, the filter is too dense to clean the filter twice or more every week, and the circulating water is severely cut off; Not filtered.

(3) The door type rubber gasket for sealing at the inlet port of the cooling water of the compressor cooler is faulty.

The built-in cooler of the CENTAC compressor uses a door-type sealing gasket to separate the inlet side and the drain side of the cooling water at the inlet port of the cooling water. The door type gasket is glued to the cooler in the original design with synthetic glue. The interface is on the outer casing. The main faults are as follows: (a) the seal is ineffective due to uneven contact surface during installation; (b) after running for a period of time, due to the impact of water pressure, the door seal gasket moves and the seal fails.

4 disintegration verification

After disintegration in February 2009, it was found that more than one-half of the inlet gate gaskets of this class of coolers were washed away by water, resulting in seal failure; at the water inlet of the cooler, the circulating water cooling between the bundles was observed. Tower filler residue, micro flocs, etc., have white scale at the outlet of the cooler.

5 solutions

5 1 Cooling tube bundle easy-blocking treatment The compact arrangement of the tube bundle for the cooler of the compressor, and the water quality is insufficient to meet the long-term normal operation of the equipment, redesigning the cooler for the return water line for online backwashing The higher temperature cooler, our factory is backwashed online by implementing a 4-stage cooler. The operation mode before and after the transformation is roughly as follows: (A) Before the transformation, the circulating cooling water enters the cooler through the V1 stop valve, and returns from the V2 back to the return water main pipe; (B) After the transformation, when the exhaust temperature of the stage continues to rise (Generally, it rises to about 4 under the alarm). When the V1 and V2 valves are closed, the V3 and V4 valves must be opened, and the synchronization must be maintained.

The important significance of this transformation is that the equipment can realize the online backwashing of the cooler without stopping the machine. The test has certain effects, which can provide sufficient time for the equipment management personnel to organize the equipment maintenance and the production dispatcher to arrange the production organization. However, in the process of achieving backwashing, the compressor turns into the same direction cooling due to the change of the original gas and water reverse cooling mode, which will increase the exhaust gas temperature and the possibility of causing high temperature interlocking parking. . Therefore, our factory arranged an online backwashing in May 2009. Before the backwashing, the compressor was unloaded by the nitrogen user with a reduced nitrogen content. The backwashing was carried out in the unloading condition. The backwashing time was 1 h. The valve is switched to the normal flow direction. After loading, observe the exhaust temperature of each stage. It can be seen that the exhaust temperature of the NO. 4 cooler after backwashing is reduced by 5. The temperature of other exhaust gases is not obvious, and the online backwashing has certain Effect.

5 2-door type rubber pad failure treatment For the failure of the door type rubber gasket seal failure, the modification of the cooler inlet and outlet port type port avoids the operation of the door type rubber pad. A stainless steel strip frame with a width of 10 mm and a thickness of 3 mm is spot-welded on the outer edge of the door type rubber pad to limit the movement and running position of the door type rubber pad in three directions. Up to February 2009, according to this plan, after the operation, there is no failure phenomenon of the door type rubber pad running position, and the effect is obvious.

6 Conclusion C125M X5N 2 type centrifugal turbine nitrogen pressure machine has a high exhaust temperature problem has been plagued by users with poor circulating water quality, which is the bottleneck of Ingersoll Rand's high efficiency built-in gas cooler. To cure this failure, we must work hard on the study of circulating water quality. Since February 2009, the factory has strengthened the monitoring of circulating water quality, requiring water treatment manufacturers to submit water quality reports on a one-week cycle, and optimize water treatment plans in different seasons, and the circulating water quality is improving day by day. In the process of solving the high exhaust speed failure of the compressor exhaust temperature, this breakthrough has broken through the previous concept of not going to import and export equipment.

It is concluded that as long as it is in line with science, it should be courageous to study, explore and actively solve it. This successful attempt provided an important reference experience for the other 4 sets of Ingersoll Rand nitrogen presses and other companies in the same industry, which has the promotion significance.

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