Multi-Stage Wet Gas Compressor Design for Corrosion and Cost Control
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Solution Overview
Problem
Existing plants for compressing CO2-rich gas streams with high water content face high costs due to the need for stainless steel compressors to prevent corrosion, which limits the use of less expensive materials.
Innovation Solution
A plant design with multiple compression stages, where exchangers connected to a cooling water circuit include a device for creating a pressure drop at the outlet, allowing the use of carbon steel instead of stainless steel, and incorporating a stainless steel exchanger in the last stage to manage condensation and corrosion effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stainless steel compressors are used to prevent corrosion from wet CO2 condensation, then corrosion resistance is improved, but plant cost increases
Solution Approach 1:
The patent applies different material qualities to different locations in the compression system. Carbon steel is used for exchanger shells where condensation risk is lower, while stainless steel is used for the final stage exchanger and compressor components where condensation and corrosion risk is highest. This local differentiation of material quality resolves the contradiction by providing corrosion resistance only where necessary, reducing overall plant cost while maintaining reliability in critical areas.
Solution Approach 2:
The compression system is divided into multiple stages, with each stage's exchanger shell treated as a separate component with potentially different material specifications. The patent segments the system into N-1 initial stages using carbon steel and a final stage using stainless steel, allowing independent material selection for each segment based on local corrosion risk, thus resolving the cost versus reliability contradiction.
2Temperature
If exchangers are connected in series to the cooling water circuit, then temperature control is improved, but pressure drop increases
Solution Approach 1:
The patent introduces a water circulation pump as an intermediary device to overcome the pressure drop caused by series connection of exchangers. The pump provides the necessary pressure boost to maintain cooling water flow through multiple exchangers connected in series, thereby achieving good temperature control without being limited by natural pressure losses in the circuit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces costs by avoiding condensation and allowing the use of less expensive materials while maintaining effective corrosion prevention, thereby lowering the overall cost of the compression plant.
Implementation Method 1
each compression stage comprises a compression means and an exchanger connected directly or indirectly to a cooling water circuit C
Implementation Method 2
the exchangers not connected in series to the cooling water circuit comprise, at their cooling water outlet, a device that makes it possible to create a pressure drop
Data Source
AI summary
A method and apparatus for compressing a gas flowing comprising at least 0.1 vol % water, include a compressor containing N compression stages, in which each compression stage includes a compressing means and an exchanger directly or indirectly connected to a water-coolant circuit; and in which at least a first exchanger and a second exchanger, in first and second consecutive or non-consecutive compression stages, are connected in series to the water-coolant circuit. The exchangers, which are not connected in series to the water-coolant circuit, include at their water-coolant output a pressure drop device.