35 research outputs found
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Development of advanced NO sub x control concepts for coal-fired utility boilers
CombiNO{sub x} is a NO{sub x} reduction process which incorporates three different NO{sub x} control technologies: reburning, selective non-catalytic reduction (SNCR), and methanol injection. Gas reburning is a widely used technology that has been proven to reduce NO{sub x} up to 60% on full-scale applications. The specific goals of the CombiNO{sub x} project are: 70% NO{sub x} reduction at 20% of the cost of selective catalytic reduction; NO{sub x} levels at the stack of 60 ppm for ozone non-attainment areas; Demonstrate coal reburning; Identify all undesirable by-products of the process and their controlling parameters; Demonstrate 95% N0{sub 2} removal in a wet scrubber. Before integrating all three of CombiNO{sub x}'s technologies into a combined process, it is imperative that the chemistry of each individual process is well understood. Pilot-scale SNCR tests and the corresponding computer modeling were studied in detail and discussed in the previous quarterly report. This quarterly report will present the results obtained during the pilot-scale advanced reburning tests performed on EER's Boiler Simulation Facility (BSF). Since methanol injection is a relatively new NO{sub x} control technology, laboratory-scale tests were performed to better understand the conditions at which methanol is most effective. The experimental set-up and results from these tests will be discussed
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Development of advanced NO[sub x] control concepts for coal-fired utility boilers
The complete CombiNO[sub x], process has now been demonstrated at a level that is believed to be representative of a full-scale boiler in terms of mixing capabilities. A summary of the results is displayedin Figure 5-1. While firing Illinois Coal on the Reburn Tower, Advanced Reburning was capable of reducing NO[sub x], by 83 percent. The injection of methanol oxidized 50--58 percent of the existing NO to N0[sub 2]. Assuming that 85 percent of the newly formed N0[sub 2] can be scrubbed in a liquor modified wet-limestone scrubber, the CombiNO[sub x], process has been shown capable of reducing NO[sub 2], by 90--91 percent in a large pilot-scale coal-fired furnace. There is still uncertainty regarding the fate of the N0[sub 2] formed with methanol injection. Tests should be conducted to determine whether the reconversion is thermodynamic or catalytic, and what steps can be taken (such as quench rate) to prevent it from happening
Measurement and Modeling of Particle Radiation in Coal Flames
This work aims at developing a methodology that can provide information of in-flame particle radiation in industrial-scale flames. The method is based on a combination of experimental and modeling work. The experiments have been performed in the high-temperature zone of a 77 kWth swirling lignite flame. Spectral radiation, total radiative intensity, gas temperature, and gas composition were measured, and the radiative intensity in the furnace was modeled with an axisymmetric cylindrical radiation model using Mie theory for the particle properties and a statistical narrow-band model for the gas properties. The in-flame particle radiation was measured with a Fourier transform infrared (FTIR) spectrometer connected to a water-cooled probe via fiber optics. In the cross-section of the flame investigated, the particles were found to be the dominating source of radiation. Apart from giving information about particle radiation and temperature, the methodology can also provide estimates of the amount of soot radiation and the maximum contribution from soot radiation compared to the total particle radiation. In the center position in the flame, the maximum contribution from soot radiation was estimated to be less than 40% of the particle radiation. As a validation of the methodology, the modeled total radiative intensity was compared to the total intensity measured with a narrow angle radiometer and the agreement in the results was good, supporting the validity of the used approach
Longitudinal changes in telomere length and associated genetic parameters in dairy cattle analysed using random regression models
Telomeres cap the ends of linear chromosomes and shorten with age in many organisms. In humans short telomeres have been linked to morbidity and mortality. With the accumulation of longitudinal datasets the focus shifts from investigating telomere length (TL) to exploring TL change within individuals over time. Some studies indicate that the speed of telomere attrition is predictive of future disease. The objectives of the present study were to 1) characterize the change in bovine relative leukocyte TL (RLTL) across the lifetime in Holstein Friesian dairy cattle, 2) estimate genetic parameters of RLTL over time and 3) investigate the association of differences in individual RLTL profiles with productive lifespan. RLTL measurements were analysed using Legendre polynomials in a random regression model to describe TL profiles and genetic variance over age. The analyses were based on 1,328 repeated RLTL measurements of 308 female Holstein Friesian dairy cattle. A quadratic Legendre polynomial was fitted to the fixed effect of age in months and to the random effect of the animal identity. Changes in RLTL, heritability and within-trait genetic correlation along the age trajectory were calculated and illustrated. At a population level, the relationship between RLTL and age was described by a positive quadratic function. Individuals varied significantly regarding the direction and amount of RLTL change over life. The heritability of RLTL ranged from 0.36 to 0.47 (SE = 0.05â0.08) and remained statistically unchanged over time. The genetic correlation of RLTL at birth with measurements later in life decreased with the time interval between samplings from near unity to 0.69, indicating that TL later in life might be regulated by different genes than TL early in life. Even though animals differed in their RLTL profiles significantly, those differences were not correlated with productive lifespan (p = 0.954)
The design, assembly and testing of a shock tube for study of coal combustion kinetics
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An investigation to define the physical/chemical constraints which limit NO sub x emission reduction achievable by reburning
Reburning is a combustion modification technique which removes NO{sub x} from combustion products by using fuel as a reducing agent. Previous studies have shown that natural gas is more effective than coal as a reburning fuel Objectives of this program are to define the chemical and physical constraints which prevent the attainment of 80% NO{sub x} reduction with reburning and to test improved configurations for reburning as an advanced NO{sub x} control technique for coal-fired boilers. Bench scale studies are designed to screen the chemical and physical means for enhancing reburning efficiency. Subsequent pilot studies will evaluate the impacts of finite rate mixing on the effectiveness of the various concepts. The program consists of the following: bench scale studies on N{sub 2} formation in reburning zone and XN conversion in burnout zone; pilot scale studies; interpretation and generalization, and a final report. This quarterly report documents the progress of the pilot scale studies in this reporting period. 2 figs
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Development of advanced NO[sub x] control concepts for coal-fired utility boiler
Hybrid technologies for the reduction of NO[sub x] emissions from coal-fired utility boilers have shown the potential to offer greater levels of NO[sub x] control than the sum of the individual technologies, leading to more cost effective emissions control strategies. Energy and Environmental Research Corporation (EER) has developed a hybrid NO[sub x] control strategy involving two proprietary concepts which has the potential to meet the US Department of Energy's NO[sub x] reduction goal at a significant reduction in cost compared to existing technology. The process has been named CombiNO[sub x]. CombiNO[sub x] is an integration of three technologies: modified reburning, promoted selective noncatalytic reduction (SNCR) and methanol injection. These technologies are combined to achieve high levels of NO[sub x] emission reduction from coal-fired power plants equipped with S0[sub x] scrubbers. The first two steps, modified reburning and promoted SNCR are linked. It has been shown that performance of the SNCR agent is dependent upon local oxidation of CO. Reburning is used to generate the optimum amount of CO to promote the SNCR agent. Approximately 10 percent reburning is required, this represents half of that required for conventional reburning. If the reburn fuel is natural gas, the combination of reburning and SNCR may result in a significant cost savings over conventional reburning. The third step, injection of methanol into the flue gas, is used to oxidize NO to N0[sub 2] which may subsequently be removed in a wet scrubber. Pilot-scale tests performed at EER's 1 MMBtu/hr Boiler Simulation Facility (BSF) have demonstrated NO[sub x] reductions up to 92%. The program's next phase entails process scale-up to a 10 MMBtu/hr furnace also located at EER's Santa Anna test site
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National procurement of private-sector treatment for U.S. Department of Energy mixed low-level wastes
The cost of bringing DOE into compliance with the Federal Facilities Compliance Act may be dramatically reduced if the private sector treats DOE mixed low level waste. If the DOE clearly defines this market by using national procurement contracts, the private sector will be able to decide if investing in DOE waste treatment contracts is good business. DOE can structure the mixed waste treatment market to influence the profitability of the contracts and to influence the quality of private sector responses. National procurement contracts will incorporate advice from the private sector so that issues of concern to industry are adequately incorporated