Kelly Thambimuthu

NOx and SO2 emissions from O2/CO2 recycle coal combustion

Abstract Capturing CO 2 from conventional coal-fired power plant is very costly because of its relatively dilute concentration in the flue gas. One option to reduce the cost of gas separation is to increase CO 2 concentration in the flue gas by eliminating nitrogen before combustion and by recycling part of the flue gas. This scheme is known as O 2 /CO 2 recycle combustion. The present work focuses on the implications of O 2 /CO 2 recycle combustion on NO x and SO 2 emissions. Two main types of experiments were performed: combustion in once-through O 2 /CO 2 mixtures and experiments with recycled flue gas. Combustion in air was performed as a base case. For each experiment, NO x and SO 2 were measured at several locations along the reactor and the experimental results are presented in this paper.

Technologies for capture of carbon dioxide

Publisher Summary About 85% of the worlds commercial energy needs are currently supplied by fossil fuels. A rapid change to non fossil energy sources would result in large disruption to the energy supply infrastructure, with substantial consequences for the global economy. This chapter reviews the technologies that could be used to capture CO2 from use of fossil fuels. It identifies the main opportunities for capturing CO2 which are power generation, other large energy consuming industries and production of carbon-free energy carriers. The three main overall methods of capturing CO2 in power plants: post combustion capture, oxy fuel combustion, and pre-combustion capture are described. It also describes the various CO2 separation techniques that could be used and their current development status. The impacts of different CO2 capture technologies on the thermal efficiencies and costs of power plants are summarized based on recent studies carried out by process technology developers and plant engineering contractors.

A comparative study of refinery fuel gas oxy-fuel combustion options for CO2 capture using simulated process data

Publisher Summary This chapter highlights the large scale industrial greenhouse gas (GHG) emitters, mainly coal-fired power plants, refineries and other chemical plants are compelled in the near future to reduce their GHG emissions, especially carbon dioxide. This would be in accordance with the Kyoto protocol that is currently awaiting international ratification. Carbon dioxide, a major component of greenhouse gases, could be captured and isolated from different industrial flue gas streams by installing a CO2 capture and treatment plant. Once CO2 is captured, it can be stored permanently in suitable geological storage sites and/or used for coal-bed methane, enhanced oil recovery, or utilized for many other commercial applications. This chapter presents the application of oxy-combustion and CO2 capture to two refinery fuel gases with given compositions. The simulation results are presented for four different combustion modes, including the air case as the baseline and three oxy-fuel combustion cases. It shows that oxy-fuel combustion is a possible and viable approach for CO2 capture from refinery fuel gases. A cost analysis is also performed to find out the estimated CO2 capture and avoidance costs for each case. The CO2 avoidance cost was found to be approximately 3cents to 4.5cents per kg of CO2, excluding the transport and storage costs.

Oxy-fuel coal burner design: From CFD modeling to pilot scale testing

Publisher Summary This chapter focuses on a sequence of combustion tests performed on the Vertical Combustor Research Facility of the CANMET Energy Technology Centre to calculate the performance of a burner design optimized for oxy-fuel combustion of coal. In addition, the chapter evaluates burner and combustor design concepts for lower NOx during O2 firing based on recommendations made by CFD modeling. The tests are carried out with a high volatile lignite coal at a heat input of 0.21 MWth, with both air firing and oxygen firing. The flue gas compositions are monitored during the tests and extensive flame probing is conducted. All tests are executed using a high volatile lignite coal. Extensive flame sampling, including temperature and major species, is conducted and radial and axial measurements are performed. As a result, the new burner emitted considerably lower NOx compared to previous ones. This test made it possible to bring NOx emissions to below 0.15 lb/MBTU while firing in O2/RFG mode. Results confirmed the superiority of the current design by considerably decreasing NOx formation during oxygen firing of the coal while maintaining excellent fuel burnout.

- In-Situ Gasification, Enhanced Methane Recovery and CO 2 Storage in Deep Coal Seams

Publisher Summary This chapter examines the feasibility of combining a process known as in-situ or underground gasification with enhanced methane recovery to increase the permeability of coal seams, to extract energy and ultimately to store CO2 in seams that are too deep to mine. Enhanced gas recovery is a process whereby the extraction of methane from coal seams is increased through the injection of gas to displace the methane adsorbed in the seam.Large quantities of gases are produced during coalification. The amount of coal gas contained within a seam is dependent upon the coal rank, as gas generation varies with the degree of coalification. Underground gasification is a means of extracting coal through its conversion into a gaseous source of energy directly within the coal seam by injection of steam and air or oxygen. Permeability issues that affect gasification can be addressed through the use of a number of linking techniques that also have the potential to be applied to enhanced gas recovery. The order in which gasification and enhanced gas recovery occur is important to the success of process combinations, as any carbon dioxide stored within the seam will dissociate from the coal matrix when exposed to the temperatures necessary for gasification. A highly concentrated environment of carbon dioxide would also have significant impact on gasification, requiring greater thermal or pure oxidant input.

Canadian Initiatives on CO2 Capture and Storage: Towards Zero Emissions from Fossil Fuels

Publisher Summary The capture, geological storage, and/or utilization of CO 2 represent an attractive option to reduce greenhouse gas emissions in Canada. With CO 2 capture, co-incidental benefits arising from the removal of a number of secondary air pollutants generated from the utilization of fossil fuels provide additional opportunities to address a number of associated air pollution control issues. As a result, several of Canadian federal, provincial government and industry-supported initiatives are currently underway aimed at achieving these goals. This chapter describes several projects that have been undertaken to characterize the CO 2 storage potential geological sinks and for the development and deployment of storage/utilization and capture technologies for achieving near zero emissions of CO 2 and other atmospheric pollutants from fossil fuel use. Since the negotiation of the 1997 Kyoto Protocol, Canada has been working diligently towards its ratification. The target is to reduce annual greenhouse gas emissions to a level of minus 6% by 2008–2012 relative to the 1990 level, which is estimated to have been the equivalent of 601 Mt of CO 2 . The federal government provided further recognition of the importance of emissions reducing potential of capture and storage technologies in October 2000 in its National Implementation Strategy on Climate Change adopted by ministers.