Carbon dioxide recovery from flue gases of a conventional coal-fired power plant by low-temperature distillation

Abstract

To reduce the emissions of carbon dioxide to the atmosphere, carbon dioxide can be recovered from flue gases of power plants and stored. In this chapter, we examine the feasibility and costs of recovering carbon dioxide from the flue gases of a conventional coal-fired power plant using a low-temperature distillation method. This kind of plant is chosen because of the high concentration of carbon dioxide in the flue gases, which reduces the energy consumption per tonne of carbon dioxide recovered.

To distil the carbon dioxide, the flue gases are compressed to a pressure of about 200 kPa and cooled down to a temperature around minus 110°C. Under these conditions carbon dioxide solidifies. The solid carbon dioxide is collected and liquefied by heating it to 10°C. The cleaned flue gases are heated up by the incoming flue gases and expanded before they are released to the atmosphere.

According to our study, recovering 90% of the carbon dioxide from the flue gases by distillation will result in a decrease of the energy conversion efficiency of the power plant by 11%, namely from 41 to 30%. The specific carbon dioxide emission will decrease from 0.80 to 0.11 kg/kWh. If the system is used in a 600 MW_e coal-fired power plant, the carbon dioxide recovery will lead to a 60% increase in electricity production costs, namely from 3.7 to 6.0 ¢/kWh. The recovery costs are calculated at 32 US$ per tonne carbon dioxide avoided.

Before the method of low-temperature distillation can be implemented in a power plant, the technology for handling solid carbon dioxide in a heat exchanger needs to be improved.