Fuel Gas Cleaning Research Articles

High-temperature fuel gas cleaning and removal of alkalis using molten slag

Fuel gas cleaning is an important step in the development of coal-based combined cycle technologies. By integrating hot gas cleaning facilities in the combined cycle power plant, higher operating temperatures can be achieved. Research is being carried out at the Institute of Ferrous Metallurgy, Technical University of Aachen, to develop a process for gas cleaning at temperatures above 1300°C using a venturi scrubber with molten slags as sorbents. This process offers simultaneous removal of particulate matter and alkali vapours in the gas stream. The present paper deals with the particulate removal tests, with major emphasis on investigations carried out to study the reaction between molten slags of various compositions and alkali vapours. These investigations included thermochemical calculations as well as an experimental reaction study.

In Situ Fourier Transform Infrared Characterization of Sulfur Species Resulting from the Reaction of Water Vapor and Oxygen with Zinc Sulfide

Steam is utilized as a diluent in the regeneration of zinc-based hot gas desulfurization sorbents used in fuel gas cleanup. Therefore, the effect of water vapor on the interaction of zinc sulfide (ZnS) with oxygen at 823, 873, and 923 K was studied using Fourier transform infrared (FTIR) spectroscopy. When ZnS at 823 K was exposed to oxygen, sulfate (SO42-) was the most prominent species observed at oxygen pressures greater than 5 × 10-2 Torr while sulfite (SO32-) was the major species observed during the water vapor exposures. When ZnS at 823 K was exposed to an equimolar mixture of water vapor and oxygen, sulfite and sulfate were the most prominent products but the intensity of the sulfite peak was more than that of the sulfate. The sulfur species formed during the water vapor and oxygen exposures at both 873 and 923K were similar to those at 823 K, but the relative intensities of the peaks corresponding to these sulfur species were different. At all three temperatures, the presence of water vapor enhan...

Kinetics of HCl reactions with calcium and sodium sorbents for IGCC fuel gas cleaning

Experiments for HCl sorption by calcium and sodium sorbents have been carried out with simulated gases of compositions typical for “air-blown” and “oxygen-blown” IGCC fuel gases. The concentration of CO 2 affects the behaviour of HCl sorption by Ca-sorbents but does not influence the performance of Na-sorbents in the temperature range 300–600°C. The sorbent particle size has a slight effect on HCl sorption by Na 2CO 3 in the range 90–250 μm. The optimum temperature for the reaction was found to be between 400 and 500°C. This has been attributed to a combination of reaction kinetics and sintering. A mathematical model has been developed to simulate gas solid reactions in fixed beds. The coefficient of gas diffusion through the product layer (NaCl) was obtained at 300–600°C.

Advanced Hot Gas Cleaning System for Coal Gasification Processes

The United States electric industry is entering a period where growth and the aging of existing plants will mandate a decision on whether to repower, add capacity, or do both. The power generation cycle of choice, today, is the combined cycle that utilizes the Brayton and Rankine cycles. The combustion turbine in a combined cycle can be used in a repowering mode or in a greenfield plant installation. Today’s fuel of choice for new combined cycle power generation is natural gas. However, due to a 300-year supply of coal within the United States, the fuel of the future will include coal. Westinghouse has supported the development of coal-fueled gas turbine technology over the past thirty years. Working with the U.S. Department of Energy and other organizations, Westinghouse is actively pursuing the development and commercialization of several coal-fueled processes. To protect the combustion turbine and environment from emissions generated during coal conversion (gasification/combustion) a gas cleanup system must be used. This paper reports on the status of fuel gas cleaning technology and describes the Westinghouse approach to developing an advanced hot gas cleaning system that contains component systems that remove particulate, sulfur, and alkali vapors. The basic process uses ceramic barrier filters for multiple cleaning functions.

An assessment of laser holography for the measurement of fine gasborne particles

Laser holography offers an accurate means of measuring the size, concentration and velocity of fine particles suspended in gas streams and therefore has a novel potential use in studies of hot fuel gas cleaning methods. A theoretical analysis of holographic image resolution principles was carried out in order to apply the technique to examination of particles emanating from a coal gasifier. Laboratory bench tests using an in-line system show that fine particles down to 2 μm in a simulated off-gas line can be recorded for analysis. The effect of a hot gas environment on background noise and size resolution is also discussed. Some results of the hot gas tests are presented and compared with results obtained using a laboratory particle sizer on samples collected isokinetically. Size distributions measured holographically show good agreement with laboratory results.