Pressure-Drop Chamber Layout for High-Pressure Reciprocating Compressors
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Solution Overview
Problem
Reciprocating compressors face limitations in achieving high discharge pressures due to high differential pressures across piston rod pressure packings, especially with dry packings, which restrict the maximum allowable discharge pressure.
Innovation Solution
Incorporating a pressure-drop chamber between the gas compression cylinder and the crosshead guide, purged with process gas at a pressure lower than delivery pressure and higher than ambient pressure, to divide the differential pressure across piston rod pressure packings, reducing the maximum pressure differential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the discharge pressure is increased to achieve high compression ratio, then the compression performance is improved, but the differential pressure across piston rod pressure packing increases causing seal degradation
Solution Approach 1:
The pressure differential across the piston rod sealing system is segmented into multiple stages by introducing intermediate pressure chambers. The first pressure chamber is maintained at an intermediate pressure between the compression chamber pressure and atmospheric pressure, dividing the total pressure differential into two smaller differentials that the sealing system must withstand, thereby reducing seal contact pressure and preventing degradation while maintaining high discharge pressure capability
2Manufacturing precision
If dry pressure packing is used to prevent contamination, then gas purity is improved, but the maximum allowable discharge pressure is limited due to high differential pressure
Solution Approach 1:
The sealing system is divided into multiple sealing stages corresponding to multiple pressure chambers. Each sealing stage operates at a lower differential pressure, allowing dry pressure packing to maintain effective sealing without excessive contact pressure that would limit maximum discharge pressure, while still preventing gas contamination
Solution Approach 2:
Intermediate pressure chambers are introduced as mediator elements between the high-pressure compression chamber and the atmospheric pressure environment. These chambers create stepped pressure zones that reduce the differential pressure across each sealing interface, enabling dry pressure packing to function effectively at higher discharge pressures while maintaining gas purity
Data Source
Figure 1
Figure 2
AI summary
The reciprocating compressor (1) comprises a compressor frame (3), a crankshaft (5) and a connecting rod (7), connecting the crankshaft (5) to a crosshead (9). A piston rod (17) connects a piston (15) to the crosshead (9). The piston reciprocates in a gas compression cylinder (13). At least one pressure-drop module (33) is positioned between the gas compression cylinder (13) and a crosspiece guide (11). The piston rod (17) extends from the gas compression cylinder (13) through a pressure-drop chamber (35) of the pressure-drop module (33). Also disclosed herein is a method of operating a reciprocating compressor (1).