Interactions Between Potassium and Sulfur Species in a Coal-Fired Magnetohydrodynamics System

The interactions between potassium and sulfur-containing species are unique, yet important, phenomena for a coal-fired magnetohydrodynamics (MHD) system. An in-depth understanding of such phenomena will help in the future design of MHD systems. This paper deals with the modeling of potassium and sulfur interactions in DOE's Coal-Fired Flow Facility (CFFF), located in Tullahoma, Tennessee.     

Investigation of Nitrogen-Bearing Species in Catalytic Steam Gasification of Poultry Litter

Abstract

The production of broiler chickens has become one of the largest sectors in U.S. agriculture, and the growing demand for poultry has led to an annual production growth rate of 5%. With increased demand for poultry, litter management has become a major challenge in the agriculture industry. Although the catalytic steam gasification has been accepted as a possible and feasible method for litter management, concern has been expressed about the presence of nitrogen and phosphorus containing species in the fuel gas and/or in the final solid residue. The possible release of phosphorus as phosphine gas in the fuel gas can have an adverse impact on the environment. Similarly, possible release of ammonia from the nitrogen containing species is also not acceptable. Hence, under partial U.S. Department of Agriculture support, a study was conducted to examine the fate and the environmental impact of the nitrogen- and phosphorus-containing species released during catalytic steam gasification of poultry litter. From various preliminary tests, it was concluded that most (～100%) of the phosphorus would remain in the residue, and some (20–70%) of the nitrogen would end up as ammonia in the fuel gas. The effects of temperature, catalyst loading, and type of catalyst on ammonia liberation were studied in a muffled furnace setup at atmospheric pressure. The fraction of nitrogen released as ammonia was found to decrease with an increase in temperature during pyrolysis and steam gasification. It also decreased with an increase in catalyst loading.     

Investigation of nitrogen-bearing species in catalytic steam gasification of poultry litter

The production of broiler chickens has become one of the largest sectors in U.S. agriculture, and the growing demand for poultry has led to an annual production growth rate of 5%. With increased demand for poultry, litter management has become a major challenge in the agriculture industry. Although the catalytic steam gasification has been accepted as a possible and feasible method for litter management, concern has been expressed about the presence of nitrogen and phosphorus containing species in the fuel gas and/or in the final solid residue. The possible release of phosphorus as phosphine gas in the fuel gas can have an adverse impact on the environment. Similarly, possible release of ammonia from the nitrogen containing species is also not acceptable. Hence, under partial U.S. Department of Agriculture support, a study was conducted to examine the fate and the environmental impact of the nitrogen- and phosphorus-containing species released during catalytic steam gasification of poultry litter. From various preliminary tests, it was concluded that most (approximately 100%) of the phosphorus would remain in the residue, and some (20-70%) of the nitrogen would end up as ammonia in the fuel gas. The effects of temperature, catalyst loading, and type of catalyst on ammonia liberation were studied in a muffled furnace setup at atmospheric pressure. The fraction of nitrogen released as ammonia was found to decrease with an increase in temperature during pyrolysis and steam gasification. It also decreased with an increase in catalyst loading.     

Catalytic gasification of coal using eutectic salts: recovery,regeneration, and recycle of spent eutectic catalysts

Catalyst recovery studies were conducted for gasified chars produced from steam gasification of Illinois #6 coal catalyzed with two different catalyst systems. A ternary (43.5 mol% Li2CO3-31.5 mol% Na2COr-25 mol% K2CO3) and a binary (29 mol% Na2CO3-71 mol% K2CO3) eutectic catalyst system were used for gasifying coal. Various extraction schemes, such as water extraction, H2SO4 extraction, and acetic acid extraction, were evaluated with respect to their extraction efficiencies. Effects of major process variables, such as solvent-to-char ratio, mixing time, temperature, and concentration, on the extraction efficiency were evaluated. A process schematic for the entire catalyst recovery, regeneration, and recycle scheme was developed and the preliminary process economics were determined based on these extraction schemes. H2SO4 extraction was found to be the most desirable. It also turned out to be more attractive than a once-through throwaway system.     

Preliminary economic analysis of poultry litter gasification option with a simple transportation model

Several environmental issues are related to the disposal of poultry litter. In an effort to provide a more environmentally friendly alternative than landfill disposal or spreading as a soil amendment, work has been carried out previously at the University of Tennessee Space Institute (UTSI). This past UTSI work was concentrated on developing a catalytic steam gasification concept to produce energy from poultry litter. In the past UTSI studies, preliminary design and economics for a stationary, centralized gasification plant capable of processing approximately 100 ton/day of poultry litter were developed. However, in this preliminary design the economic impact of transporting litter to a centralized gasification plant location was not addressed. To determine the preliminary impact of transporting the poultry litter on the overall economics of this energy conversion plant design, a simple transportation model was developed. This model was used in conjunction with the earlier plant design prepared at UTSI to determine the economic feasibility of a centralized, stationary poultry litter gasification plant. To do so, major variables such as traveling distance, plant feed rate (or capacity), fluctuations in the sales price of the product gas (that means value of the energy), population density of poultry farms, impact of tipping fees, and cost of litter were varied. The study showed that for plant with a capacity of 1000 ton/day to be able to withstand several changes in economic conditions and sustain itself, the poultry farm density would need to be approximately 0.3 houses/mi2. Smaller plants would need either a higher energy price or some kind of subsidy to be economically feasible.     

Catalytic Gasification of Coal Using Eutectic Salts: Recovery,Regeneration, and Recycle of Spent Eutectic Catalysts

Abstract

Catalyst recovery studies were conducted for gasified chars produced from steam gasification of Illinois #6 coal catalyzed with two different catalyst systems. A ternary (43.5 mol% Li₂ CO₃ –31.5 mol% Na₂ CO₃ –25 mol% K₂ CO₃ ) and a binary (29 mol% Na₂ CO₃ –71 mol% K₂ CO₃ ) eutectic catalyst system were used for gasifying coal. Various extraction schemes, such as water extraction, H₂ SO₄ extraction, and acetic acid extraction, were evaluated with respect to their extraction efficiencies. Effects of major process variables, such as solvent-to-char ratio, mixing time, temperature, and concentration, on the extraction efficiency were evaluated. A process schematic for the entire catalyst recovery, regeneration, and recycle scheme was developed and the preliminary process economics were determined based on these extraction schemes. H₂ SO₄ extraction was found to be the most desirable. It also turned out to be more attractive than a once-through throwaway system.     

Improved Version of Anion-exchange Resin-based Desulfurization Process for Alkali Metal Sulfates

Abstract

Vehicle gaseous emissions (NO, CO, CO₂, and hydrocarbon [HC]) and driver’s particle exposures (particulate matter <1 μm [PM₁], <2.5 μm [PM_2.5], and<10 μm [PM₁₀]) were measured using a mobile laboratory to follow a wide variety of vehicles during very heavy traffic congestion in Macao, Special Administrative Region, People’s Republic of China, an urban area having one of the highest population densities in the world. The measurements were taken with high time resolution so that fluctuations in the emissions can be seen readily during vehicle acceleration, cruising, deceleration, and idling. The tests were conducted in close proximity to the vehicles, with the inlet of a five-gas analyzer mounted on the front bumper of the mobile laboratory, and the distance between the vehicles was usually within several meters. To measure the driver’s particle exposures, the inlets of the particle analyzers were mounted at the height of the driver’s breathing position in the mobile laboratory, with the driver’s window open. A total of 178 and 113 vehicles were followed individually to determine the gaseous emission factor and the driver’s particle exposures, respectively, for motorcycle, passenger car, taxi, truck, and bus. The gaseous emission factors were used to model the roadside air quality, and good correlations between the modeled and monitored CO, NO₂, and nitrogen oxide (NO_x) verified the reliability of the experiments. Compared with petrol passenger cars and petrol trucks, diesel taxies and diesel trucks emitted less CO but more NO_x. The impact of urban canyons is shown to cause a significant increase in the PM₁ peak. The background concentrations contributed a significant amount of the driver’s particle exposures.     

Anion-Exchange Resin-Based Desulfurization and Dechlorination of Spent Sorbent Material

Abstract

Emissions of acid gases such as SO₂ and HCI/CI₂ from energy conversion or waste incineration facilities are unacceptable. Under the various regulations, the emissions of such acid gases are regulated by the U.S. Environmental Protection Agency (EPA). Alkali metal sorbents can remove these acid gases more efficiently than the lime/limestone type sorbents used in the conventional flue gas desulfurization (FGD) systems. However, the resulting alkali metal sulfate and chloride are unsuitable for landfill disposal because they are water-soluble and can potentially leach into groundwater, altering the soil pH. Replacing the (virgin) sorbent material is expensive. Hence, it is desirable that the spent sorbent materials obtained from such emissions control systems be converted to sulfur- and chlorine-free forms, so that they can be reused. The weak-base, anionexchange resin-based desulfurization concept, developed and tested at the University of Tennessee Space Institute (UTSI), can also simultaneously remove sulfur- and chlorine- containing species from such spent sorbent materials. Under the U.S. Department of Energy’s (DOE) sponsorship, bench scale studies have been carried out at UTSI to evaluate the feasibility of removing sulfur- and chlorine-containing species using this resin-based concept. Efforts have also been made to enhance the candidate resins’ performance by carrying out the resin exhaustion step under CO₂ static pressure and by using suitable pH buffering agents, such as low-molecular weight organic acids. Preliminary cost estimates for a regeneration scheme employing reactivated alkali metal-based spent sorbent material using the ion-exchange resin-based concept seem attractive and comparable to currently available options. After further development, this low-cost, simple process can be easily integrated into alkali metal sorbent-based flue gas desulfurization and acid gas emission control systems.