Compression power requirements for Oxy-fuel CO2 streams in CCS

N K Daud,N Nasuha,S Martynov,H Mahgerefteh

doi:10.1088/1757-899x/702/1/012059

Abstract

CO2 compression systems are commonly designed assuming negligible amount of impurities in CO2 fluid, it is of practical interest to evaluate the impact of impurities in oxy-fuel streams on the compression power requirements. Compared to more traditional postcombustion and pre-combustion capture methods, oxy-fuel technology produces a CO2 stream with relatively high concentration of impurities that may require partial or a high level of removal and whose presence can be expected to increase the costs of CO2 compression. Four types of compression technologies employed include four-stage compressor with 4 intercoolers, single-stage supersonic shockwave compressor, three-stage compressor combined with subcritical liquefaction and pumping and three-stage compressor combined with supercritical liquefaction and pumping. The study depicts that decrement of the impurities content from 15 to 0.7%v/v in the CO2 streams reduced the total compression power in the compression system. The study also concludes that three-stage compressor combined with subcritical liquefaction and pumping can potentially offer higher efficiency than four-stage compressor with 4 intercoolers for almost pure CO2 streams. In the case of raw oxy-fuel mixture, that carries relatively large amount of impurities, subcritical liquefaction proved to be less feasible, while supercritical liquefaction efficiency is only marginally lower than that in the four-stage compressor with 4 intercoolers.

Highlights

In future Carbon Capture and Sequestration (CCS) projects, CO2 captured from large industrial emission sources will be purified and compressed for long-term sequestration in geological formations
Four types of compression technologies employed include four-stage compressor with 4 intercoolers, single-stage supersonic shockwave compressor, three-stage compressor combined with subcritical liquefaction and pumping and three-stage compressor combined with supercritical liquefaction and pumping
The study concludes that three-stage compressor combined with subcritical liquefaction and pumping can potentially offer higher efficiency than four-stage compressor with 4 intercoolers for almost pure CO2 streams

Summary

Introduction

In future Carbon Capture and Sequestration (CCS) projects, CO2 captured from large industrial emission sources will be purified and compressed for long-term sequestration in geological formations. In order to ensure single-phase transportation of CO2 via pipelines, the pipeline pressures need to be maintained in the range from 85 to 150 bar [1], i.e. above the critical pressure of the fluid, which in case of pure CO2 is 73 bar. At such pressures the fluid can be either in dense-phase state, at temperatures below the pseudo-critical temperatures (the temperature at which the heat capacity reaches its maximum) or in supercritical phase at temperatures above the pseudo-critical temperatures.

Methods

Results

Conclusion