ABSTRACT Microwave regeneration of adsorbents facilitates the recovery of volatile organic compounds (VOCs) by decoupling the bed heating from the stripping gas. This makes possible the creation of a highly-concentrated regeneration effluent from which the VOCs can be recovered by condensation at near-ambient temperatures. The economic feasibility of two novel microwave-regenerated adsorption systems was evaluated by systematically comparing the capital and operating costs of the proposed systems with 10 conventional VOC control technologies. The microwave systems were found to have similar capital and operating costs to conventional steam regeneration systems and, therefore, may present an attractive alternative for recovering water-miscible solvents. In general, the cost of the microwave subsystem is a relatively small component of the overall system costs, and the microwave power requirements are within the range of commercially available generators, even for large emission streams. 相似文献
Previous articles in this series discussed the equipment costs of control devices, gas conditioning equipment, hoods, ductwork, and dampers. In this article, the discussion will concern the fans and associated components required to convey the gas stream from the initial pollutant source to the control device. 相似文献
The information in this paper is directed to those concerned with controlling SO2 emissions from power plants, and particularly with retrofitting controls onto existing plants. The paper describes an FGD system based on the dolomitic lime process and the scrubber design that have proved successful at the Colstrip plant in eastern Montana. A single scrubber vessel sized to treat all the gas from a 350-MWe coal-fired unit combines the functions of prequenching, absorption, washing, mist elimination, and recycle storage. Downflow Injection of gas along the vessel centerline and regulation of gas flow by the wash tray make the gas velocity uniform and permit scaling up to this large size. A high concentration of dissolved alkalinity in the scrubbing slurry provides rapid absorption and permits low L/G—40 gal/1000 acf—when coal with 2.5% sulfur is burned. Complete oxidation of sulfite makes gypsum of wallboard quality and the process can discharge clarified liquor low in COD if necessary to control chlorides. Since only the single scrubber vessel and the recycle pumps must be located close to the back end of the boiler, the system is particularly well suited for retrofit applications. 相似文献
Section 812 of the Clean Air Act Amendments (CAAA) of 1990 requires the U.S. Environmental Protection Agency (EPA) to perform periodic, comprehensive analyses of the total costs and total benefits of programs implemented pursuant to the CAAA. The first prospective analysis was completed in 1999. The second prospective analysis was initiated during 2005. The first step in the second prospective analysis was the development of base and projection year emission estimates that will be used to generate benefit estimates of CAAA programs. This paper describes the analysis, methods, and results of the recently completed emission projections. There are several unique features of this analysis. One is the use of consistent economic assumptions from the Department of Energy's Annual Energy Outlook 2005 (AEO 2005) projections as the basis for estimating 2010 and 2020 emissions for all sectors. Another is the analysis of the different emissions paths for both with and without CAAA scenarios. Other features of this analysis include being the first EPA analysis that uses the 2002 National Emission Inventory files as the basis for making 48-state emission projections, incorporating control factor files from the Regional Planning Organizations (RPOs) that had completed emission projections at the time the analysis was performed, and modeling the emission benefits of the expected adoption of measures to meet the 8-hr ozone National Ambient Air Quality Standards (NAAQS), the Clean Air Visibility Rule, and the PM2.5 NAAQS. This analysis shows that the 1990 CAAA have produced significant reductions in criteria pollutant emissions since 1990 and that these emission reductions are expected to continue through 2020. CAAA provisions have reduced volatile organic compound (VOC) emissions by approximately 7 million t/yr by 2000, and are estimated to produce associated VOC emission reductions of 16.7 million t by 2020. Total oxides of nitrogen (NO(x)) emission reductions attributable to the CAAA are 5, 12, and 17 million t in 2000, 2010, and 2020, respectively. Sulfur dioxide (SO2) emission benefits during the study period are dominated by electricity-generating unit (EGU) SO2 emission reductions. These EGU emission benefits go from 7.5 million t reduced in 2000 to 15 million t reduced in 2020. 相似文献
The global diversity of human languages is a remarkable feature of our species, which requires a capacity for rapid vocal learning. Given that primate alarm calling systems have played an important role in the language origin debate, identifying geographic variation in primate alarm calls and understanding the underlying causal mechanisms are important steps to help uncover evolutionary precursors to language. This study investigates geographic variation in the alarm bark of the widely distributed African green monkey (Chlorocebus). To quantify geographic variation in spectral and temporal call structure, acoustic analysis was used to compare the adult male barks of green monkeys (Chlorocebus sabaeus) and two subspecies of vervet (Chlorocebus pygerythrus pygerythrus and Chlorocebus pygerythrus hilgerti). Playback experiments were also carried out to test whether adult male vervets would distinguish between the barks of own-group males, unknown conspecific males and green monkey males. Acoustic analysis showed that, whilst similar in overall structure, the barks of green monkeys could be distinguished from vervet barks with a high degree of accuracy; the barks of vervet subspecies could also be discriminated, although to a lesser degree. Males responded most strongly to unknown conspecific males’ barks, and exhibited responses typical of leopard-avoidance and territorial defence. Taken together, these findings indicate that variation in alarm calls can be best explained by phylogenetic distance, and that intra- and inter-species differences are relevant during social interactions. Moreover, barks may function as an alarm and display call, which could explain the observed sexual dimorphism in barks in this genus. 相似文献
We present an assessment of the plausible Paris-aligned fair share nett cumulative carbon dioxide (CO2) quota for an example nation state, the Republic of Ireland. By Paris-aligned, we mean consistent with the Paris Agreement adopted at the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change, at Paris, France, in December 2015 (UNFCCC 2015). We compare and contrast this quota with both the aspirations expressed in the current Irish National Policy Position and current national emission projections. The fair share quota is assessed as a maximum of c. 391 million tonnes of carbon dioxide (MtCO2), equal to 83 tonnes of carbon dioxide (tCO2) per capita, from 2015, based on a precautionary estimate of the global carbon budget (GCB) and specific interpretation of global equity. Given Ireland’s high current CO2 per capita emission rate, this would correspond to sustained year-on-year reductions in nett annual CO2 emissions of over ??11% per year (beginning as of 2016). By contrast, the CO2 mitigation target indicated in the National Policy Position corresponds to nett annual reduction rates in the range of only ?4.7% per year (low ambition) up to a maximum of ??8.3% per year (high ambition), and projections based on current and immediately planned mitigation measures indicate the possibility, instead, of sustained increases in emissions at a rate of the order of +?0.7% per year. Accordingly, there is a large gap between Paris-aligned ambition and current political and policy reality on the ground, with a significant risk of early emergence of “CO2 debt” and tacit reliance on rapid deployment of currently speculative (at a relevant scale and feasible cost) negative CO2 emission technologies to actively remove CO2 from the atmosphere. While the detailed policy situation will clearly differ from country to country, we suggest that this methodology, and its CO2debt framing, may be usefully applied in other individual countries or regions. We recommend that such framing be incorporated explicitly into a global mitigation strategy via the statements of nationally determined contributions required to be submitted and updated by all parties under the Paris Agreement processes.