Application Study Of The Dry Gas Seal In The Gas Screw Compressor Of The Crude Distillation Units

LG75·1.0-1screw compressor is key equipment for Beijing Yanshan petrochemical refinery company. In order to improve the operation stability and reliability of equipment, and ensure the safe and stable operation, extend the maintenance period of whole units or equipment, improve the operation level and economic benefits, this paper focuses on some problems of LG75·1.0-1gas screw compressor contributed by the original mechanical seal. The investigation will change the gas screw compressor mechanical seal into the dry gas seal, in order to completely solve the problem of the screw shaft normal operation of long period safe compression. Analyzing of existing problems and comparing the commonly used method of screw compressor shaft seal, the clarified the mechanical seal into the dry gas seal of the feasibility and superiority further. Also, process parameters and several typical structures of dry gas seal are analyzed. At last double end face seal of with back-to-back dry gas seal structure was selected as the screw compressor seal. Based on this, the paper studies the main factors affecting the performance of the dry gas seal and carries out the related test and field application test. The main works and contributions are as follows:1. Based on the actual situation of LG75·1.0-1, the paper considers the structure of gas screw compressor and related knowledge about seal manufacturing factory to design a set of feasible solution for the compressor dry gas seal. Then, the structure and installation method are determined. Also, the static and dynamic tests were carried out to ensure the performance of the seal at operation conditions. Leakage at operation conditions of sealing was monitored in the test process. The test results indicates that the dry gas seal is reasonable. 2. Investigate the performance of dry gas seal theoretically. In this thesis, characteristics of dry gas seal structure and balance of axial force are investigated. Also, effects of pressure, temperature, film thickness on the performance of the dry gas seal are studied by experimental method. According to the experimental results, the operation parameters suitable for this seal are determined such as the pressure, temperature and leakage flow rate.3. According to the determined operation condition, auxiliary control system suitable for the dry gas seal is designed providing the guarantee for the stable operation of sealing. Auxiliary system designing includes seal gas selection, structure design and control parts, design a set of reliable assistant system is very important for stable operation of dry gas seal in long period.The actual operating conditions at the production site indicate that the dry gas seal can be operated stably. Also, the dry gas seal auxiliary control system is reliable. The parameters have reached the design requirements. Practice has proved that the seal of LG75·1.0-1gas compressor was successfully changed to dry gas seal, which provides a guarantee for the safe and stable operation of the screw compressor, and sealing technology expands the application of dry gas seal.