[Q&A Question 241] 2017.08.29
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【Q&A Question 241】August 29, 2017: Why do reciprocating compressors with high compression ratios require multi-stage compression? (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) 1. Single-stage compression may result in an excessively high outlet temperature ； 2. Multi-stage compression enables inter-stage cooling and liquid removal ； 3. Multi-stage buffering to stabilize outlet flow and pressure ； 4. Multi-stage symmetric distribution to balance axial forces ； 5. Factors such as energy efficiency and safety: The way in which answers to daily activity-related questions are displayed is about to change. 2017 Q&A Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html Petrochemical Zone – “Creative Ideas for Energy Saving” campaign (the second phase is in full swing) http://bbs.hcbbs.com/thread-1666758-1-1.html (Source: Haichuan Chemical Industry Forum Website)
When a reciprocating compressor needs to compress gas to very high pressures and achieve a certain compression ratio, single-stage compression often results in the gas temperature rising too rapidly; the higher the single-stage compression ratio, the greater the rise in the temperature of the compressed gas. The gas inside the cylinder and the lubricating oil injected there undergo coking due to the high temperature, which affects the proper functioning of the gas valves and exacerbates the wear of the piston rings.
When a reciprocating compressor needs to compress gas to very high pressures and achieve a certain compression ratio, single-stage compression often results in the gas temperature rising too rapidly; the higher the single-stage compression ratio, the greater the rise in the temperature of the compressed gas. The gas inside the cylinder and the lubricating oil injected there undergo coking due to the high temperature, which affects the proper functioning of the gas valves and exacerbates the wear of the piston rings. The higher the temperature and pressure of the gas remaining in the clearance, the more volume the gas occupies after expansion, resulting in a decrease in volumetric efficiency. The power consumption is too high
Considering the performance of the compressor and the requirements of the process
When a reciprocating compressor needs to compress gas to very high pressures and achieve a certain compression ratio, single-stage compression often results in the gas temperature rising too rapidly; the higher the single-stage compression ratio, the greater the rise in the temperature of the compressed gas. The gas inside the cylinder and the lubricating oil injected there undergo coking due to the high temperature, which affects the proper functioning of the gas valves and exacerbates the wear of the piston rings. The higher the temperature and pressure of the gas remaining in the clearance, the more volume the gas occupies after expansion, resulting in a decrease in volumetric efficiency. The power consumption is too high
When a reciprocating compressor needs to compress gas to very high pressures and achieve a certain compression ratio, single-stage compression often results in the gas temperature rising too rapidly; the higher the single-stage compression ratio, the greater the rise in the temperature of the compressed gas. The gas inside the cylinder and the lubricating oil injected there undergo coking due to the high temperature, which affects the proper functioning of the gas valves and exacerbates the wear of the piston rings. The higher the temperature and pressure of the gas remaining in the clearance, the more volume the gas occupies after expansion, resulting in a decrease in volumetric efficiency. The power consumption is too high
A high compression ratio results in a high exhaust temperature, which is limited by the material of the equipment
When a reciprocating compressor needs to compress gas to very high pressures and achieve a certain compression ratio, single-stage compression often results in the gas temperature rising too rapidly; the higher the single-stage compression ratio, the greater the rise in the temperature of the compressed gas. The gas inside the cylinder and the lubricating oil injected there undergo coking due to the high temperature, which affects the proper functioning of the gas valves and exacerbates the wear of the piston rings. The higher the temperature and pressure of the gas remaining in the clearance, the more volume the gas occupies after expansion, resulting in a decrease in volumetric efficiency. The power consumption is too high.
1. Single-stage compression may result in excessively high outlet temperature； 2. Multi-stage compression enables inter-stage cooling and liquid removal ； 3. Multi-stage buffering to stabilize outlet flow and pressure ； 4. Multi-stage symmetric distribution to balance axial forces ； 5. Factors such as energy efficiency and safety
The higher the stage, the lower the compression ratio of that stage, the lower the exhaust temperature, and the safer it is
When the clearance coefficient remains constant, the higher the compression ratio, the greater the volume occupied by the expansion of the clearance gas in the cylinder, which reduces the amount of air that can be drawn in. When the volume coefficient is zero, the compression ratio reaches its maximum; the expansion of the gas fills the entire volume of the cylinder, making it impossible to draw in any air. When the compression ratio is high, using multi-stage compression has the advantage of reducing the exhaust temperature ； Reduce power consumption ； Improve the cylinder volume utilization rate and make the compressor’s structure more rational.