Vince White

Chapter 13 – Development of the Sorption Enhanced Water Gas Shift Process

This chapter presents the development of a novel precombustion decarbonization technology referred to as the sorption enhanced water gas shift (SEWGS) process. This development program was supported through the precombustion subgroup of the CO 2 Capture Project (CCP). This technology is particularly attractive for decarbonizing gas turbine fuel, and hence provides opportunities for power generation with minimal CO 2 emissions, high power efficiency and potentially lower cost of capturing CO 2 for storage. The SEWGS process simultaneously converts syngas containing CO into H 2 and CO 2 and removes the CO 2 from the product hydrogen by adsorption. The system operates as a multi-bed pressure swing adsorption unit, with each bed packed with a mixture of shift catalyst and a high-temperature CO 2 adsorbent. Carbon in the feed gas in the form of CO and CO 2 are removed from the product gas by the CO 2 adsorbent, and after specific PSA process steps, rejected as relatively high-purity CO 2 for recovery. The product hydrogen produced during the feed step contains the excess steam from the reaction and any nitrogen from the syngas generation, and is at high temperature and feed pressure. This hot fuel mixture can be burned in gas turbines with higher turbine efficiency than with natural gas firing and substantially lower NO x formation.

The Oxyfuel Baseline: Revamping Heaters and Boilers to Oxyfiring by Cryogenic Air Separation and Flue Gas Recycle

This chapter presents the results of a feasibility study that involves the potential application of oxyfuel technology to a complete refinery system with multiple CO 2 emission points spread out over a large area. This involves a centralized oxygen supply system and a CO 2 recovery, purification, and compression facility. The study shows that primary effluent gas cooling, compression and drying is best decentralized to be close to the emission points and an intermediate pressure CO 2 stream can then be routed to a centralized collection point for final purification and compression to pipeline pressure. The CO 2 purification system can be designed to handle practical levels of air leakage into boilers and process heaters to produce a purity of CO 2 suitable for geological sequestration. The level of air leakage into boilers and heaters that are retrofitted for oxyfuel means that it is more economic to design the Air Separation Units (ASUs) for only 95% purity and reject the associated argon and nitrogen in the CO 2 inert gas removal system.

Development of a process for CO2 capture from gas turbines using a sorption enhanced water gas shift reactor system

Publisher Summary This chapter evaluates the performance of the K 2 CO 3 /I-ITC adsorbent (HTC) in the process test unit. The temperature dependence of the CO 2 capacities is characterized by a 10kcal/mole heat of adsorption. The CO 2 adsorption and desorption processes were evaluated in a fixed bed system and the data were used as basis for sorption enhanced water gas shift (SEWGS) process designs. The SEWGS concept was demonstrated with a vessel packed with hydrotalcite (HTC) and temperature shift reactor (HTS) catalyst. With no adsorbent, CO and CO 2 breakthrough once the void gases are displaced. When adsorbent is added, the CO 2 breakthrough is delayed, and the removal of CO 2 drives the CO to insignificant levels. Decarbonized product gas containing feed He and N 2 and additional H 2 formed via the reaction is produced at reaction pressure and temperature. A cyclic experiment was conducted which demonstrated that a stable product gas can be formed with 5 times less CO+CO 2 than in the feed. Power generation process designs have been generated for the CCP Norcap scenario utilizing SEWGS fuel gas decarbonization. The SEWGS processes use hydrotalcite as a high temperature CO 2 adsorbent. Economic evaluations indicate that this approach has potential for clean power production with CO 2 recovery for sequestration.

Oxyfuel conversion of refinery process equipment utilising flue gas recycle for CO2 capture

Publisher Summary This chapter discusses that the CO2 capture project (CCP) is a joint initiative to address problems of CO2 emissions that have the potential to cause climate change. Its objective is to provide significant reductions in CO2 capture and storage costs compared to existing technologies, by developing a range of technology options applied to several real world scenarios. The CCP sponsored feasibility study reported the application of oxyfuel technology on a refinery-wide basis at a typical European refinery. The chapter highlights the technical challenges and costs involved in converting process heaters and boilers to oxyfuel operation using todays commercially proven cryogenic oxygen generation technology and goes on to identify the cost reduction opportunities available from using the next generation of oxygen separation technology: ion transport membranes (ITMs). This new technology, which is integrated with gas turbines, results in a reduction of avoided CO2 cost of from 15% to 50% depending upon the level of integration with the current steam generation within the refinery site.

Revamping Heaters and Boilers to Oxyfiring—Producing Oxygen by Itm Technology

This chapter presents ion transport membranes (ITM) oxygen process, which is based on ceramic membranes that selectively transport oxygen ions when operated at high temperatures. Under the influence of an oxygen partial pressure driving force, the ITM achieves a high flux, high purity (99+ mol%) separation of oxygen from a compressed-air stream. By integrating the non-permeate stream with a gas turbine system, the overall process co-produces high purity oxygen, power, and steam if desired. The chapter investigates three cases; the base case is presented and costed and involves the supply of the complete oxyfuel system with installation and startup and includes all required utilities. In order to provide the hot air for the ITM oxygen process, two Siemens V94.2 combined cycle gas turbines are used and excess power is exported to the local electricity grid. Other cases also use two Siemens V94.2 gas turbines plus a heat recovery steam generator (HRSG) for producing steam.