Evaluation and Analysis of Water Usage and Loss of Power in Plants with CO_2 Capture

摘要

The use of water is a critical aspect in the design, engineering and operation of any fossil-fuel-fired power plant and it is an important element in any environmental assessment and life cycle analysis. A large amount of water is needed to generate electricity from any fossil-fuel-fired power plant. This paper summarizes the results of a study carried out by Foster Wheeler for the IEA Greenhouse Gas R&D Programme (IEA GHG) with the purpose of evaluating the water usage in plants with and without CO_2 capture. The study focuses on the techno-economic evaluation of five different alternatives establishing, for each of them, the water usage and the possibility of reducing the water consumption in areas where availability of water could be limited. The study evaluates several alternative bituminous-coal-fired power plant configurations based on the following technologies: 1) Pulverised coal-fired power plant with ultrasupercritical steam cycle (USC-PC); 2) Pulverised coal-fired power plant with ultrasupercritical steam cycle using oxyfuel combustion; 3) IGCC using GEE quench-type gasifier. All cases are evaluated without and with capture of the CO_2. The CO_2 capture rate is assumed to be at least 85% of the total CO_2 emissions. In all cases the plant is located in an area where water supply could be severely limited and therefore special attention is paid to any possibility of reducing the water usage and consumption. Reference plants located in areas without water limitations, used as a basis for this study, are taken from reports already issued by IEA GHG R&D Programme, assessing the performance of power plants with and without CO_2 capture. Some of the reference reports have been developed by Foster Wheeler and some by other engineering companies. The following study objectives are pursued: 1) To establish a rigorous accounting of water usage throughout the different power plants and compare water usage in power plants with and without CO_2 capture, providing a breakdown of water consumption for each case. 2) To establish an acceptable methodology that can be used to compare water usage in power plants and provide a baseline set of cases and water loss data for assessing potential improvements and evaluating R&D programs. 3) To evaluate water usage and loss of power plants using oxyfuel, pre- or post combustion CO_2 capture technologies. 4) To assess and evaluate the performance, the costs and the potential impact on the water usage of power plants with CO_2 capture located in areas where water supply could be severely limited. The performance of the power plants is estimated based on the power plants that could be ordered today, including all the features needed to reduce the water consumption (e.g. maximization of air cooling, recycle of treated water to the process up to a zero discharge plant, etc).