摘要 :
NRELs recent published report, Thermochemical Ethanol via Indirect Gasification and Mixed Alcohol Synthesis of Lignocellulosic Biomass (NREL/TP-510-41168), evaluated the techno-economics of a biomass gasification process to produc...
展开
NRELs recent published report, Thermochemical Ethanol via Indirect Gasification and Mixed Alcohol Synthesis of Lignocellulosic Biomass (NREL/TP-510-41168), evaluated the techno-economics of a biomass gasification process to produce synthesis gas (syngas) for ethanol synthesis. The thermochemical ethanol production process consists of five major process areas: feed handling and preparation, gasification, gas cleanup and conditioning, alcohol synthesis, and product separation. The report showed that the syngas cleanup and conditioning section, which consists of tar reforming and catalyst regeneration, syngas cooling and compression, and acid gas removal (AGR) operations, has the highest cost component of all the process areas, accounting for approximately 39% of the total installed plant cost (Table ES-1). As such, this process section has a significant impact on the overall thermochemical ethanol production economics. In NRELs current design, acid gas removal is performed by an MEA system (a chemical absorption process). NREL wishes to examine the applicability of other acid gas removal processes (e.g. physical absorption systems of Selexol and Rectisol) to the thermochemical ethanol synthesis design, and to develop a detailed acid gas removal process design in order to better assess its technical and economic impacts on the overall process.
收起
摘要 :
A sod-cutting machine was evaluated for its usefulness in the radiological reclamation of small lawn areas - some of which were confined by sidewalks, trees and buildings. Fallout conditions were simulated by contaminating lawn te...
展开
A sod-cutting machine was evaluated for its usefulness in the radiological reclamation of small lawn areas - some of which were confined by sidewalks, trees and buildings. Fallout conditions were simulated by contaminating lawn test areas with radio-traced sand. Nominal particle size ranges of 44-88 μ, 88-177 μ, 177-350 μ and 350-700 μ were used. This fallout stimulant was dispersed at nominal concentrations of 25, 50 and 100 g/ft2, respectively.
Reclamation effectiveness of sod cutting was dependent upon machine factors (blade depth), soil characteristics (moisture content) and fallout stimulant properties (mass loading). The least effective sod removal results were obtained in confined lawns with high moisture content and heavy rock concentrations. The best sod cutting and removal effectiveness results were obtained on more accessible lawns having less moisture content and only a light concentration of rocks. Stimulant particle size was found to have little, if any, effect upon reclamation performance either with respect to effort required or removal effectiveness achieved.
收起
摘要 :
The synthesis report will be of interest to transportation agency maintenanceengineers, managers, and operators and others involved with roadway snow and ice control including safety engineers, traffic engineers, and law enforceme...
展开
The synthesis report will be of interest to transportation agency maintenanceengineers, managers, and operators and others involved with roadway snow and ice control including safety engineers, traffic engineers, and law enforcement agency personnel. It presents information on the state of the practice in managing roadway snow and ice control considering both rural and urban locations. The document describes the developments that have occurred during the past 20 years to improve winter maintenance. The report of the Transportation Research Board discusses winter maintenance policies and provides examples for state, city, and county agencies. Included in the discussion of winter maintenance policies are issues such as: levels of service, public relations, liability for services, and experimenting with new policies. Additional information is included on estimating winter maintenance benefits and costs; personnel and management issues; weather information systems; and materials, equipment, and facilities for winter maintenance.
收起
摘要 :
During the past several years, much attention has been directed toward the acceptable removal of obsolete pavement markings. There are a number of methods available for marking removal including chemical paint removers, sandblasti...
展开
During the past several years, much attention has been directed toward the acceptable removal of obsolete pavement markings. There are a number of methods available for marking removal including chemical paint removers, sandblasting, high pressure water jet, grinding, hydroblasting and high temperature burning. Most of these methods have been used with some degree of success by State highway agencies. However, no one method appears to be superior for use under all conditions. The report is a summary of the available information on the methods to remove unwanted pavement markings. The report includes a brief description, and a discussion concerning the effectiveness, problems, and limitations of each method. Average costs for removal are also included.
收起
摘要 :
The 1984 Strategic Transportation Research Study identified snow and ice controlas one of six priority areas for research and development. As a result, snow and ice control became one of the key areas in the Strategic Highway Rese...
展开
The 1984 Strategic Transportation Research Study identified snow and ice controlas one of six priority areas for research and development. As a result, snow and ice control became one of the key areas in the Strategic Highway Research Program (SHRP) squared. Established by Congress in 1987, SHRP had a mission to increase the durability and safety of our Nation's roads and bridges. This report presents the preliminary findings of the economics analysis conducted by Texas Transportation Institute (TTI). It describes the objectives and accomplishments of the resarch conducted under SHRP on snow and ice control, as well as the products developed from that research. It also summarizes how State and local governments are using those products.
收起
摘要 :
This manual provides information for successful implementation of an effectivehighway anti-icing program. It is written to guide the maintenance manager in developing a systematic and efficient practice for maintaining roads in th...
展开
This manual provides information for successful implementation of an effectivehighway anti-icing program. It is written to guide the maintenance manager in developing a systematic and efficient practice for maintaining roads in the best conditions possible during a winter storm. It describes the significant factors that should be understood and must be addressed in an anti-icing program, with the recongition that the development of the program must be based on the specific needs to the site or region within its reach. The manual includes recommendations for anti-icing practices and guidance for conducting anti-icing operations during specific precipitation and weather events.
收起
摘要 :
Treated wastewaters both industrial and municipal may be considered as one of the principal contributors of nutrients. Until recently,removal of nutrients has not been considered as an objective of wastewater treatment nor has it ...
展开
Treated wastewaters both industrial and municipal may be considered as one of the principal contributors of nutrients. Until recently,removal of nutrients has not been considered as an objective of wastewater treatment nor has it been the goal of water quality regulations. The increasing fertilization of natural waters coupled with the increasing demand for surface waters has focused attention on nitrogen and phosphorus as major water pollutants. The extensive research conducted within the last several years has led to the development of new methods capable of removing a high fraction of nitrogen and phosphorus from wastewaters. Available techniques for nutrients removal were evaluated with regard to classification,cost,ease of operation,and efficiencies. Evaluation was based on an extensive search of the literature. (Author)
收起
摘要 :
This Study documents the current Virginia Department of Transportation's anti-icing practice so that development of a coordinated statewide plan for implementing anti-icing technology can be considered the researcher surveyed VDOT...
展开
This Study documents the current Virginia Department of Transportation's anti-icing practice so that development of a coordinated statewide plan for implementing anti-icing technology can be considered the researcher surveyed VDOT managers to determine who is using anti-icing technology. Based on the results, he conducted follow-up interviews. This report uses anecdotal survey information to assess the effectiveness of various anti-icing techniques used within VDOT.
收起
摘要 :
The use of zero valent iron, permeable reactive barriers (PRBs) for groundwater remediation continues to increase. AN exciting variation of this technology involves introducing anaerobic bacteria into these barriers so that both b...
展开
The use of zero valent iron, permeable reactive barriers (PRBs) for groundwater remediation continues to increase. AN exciting variation of this technology involves introducing anaerobic bacteria into these barriers so that both biological and abiotic pollutant removal processes are functional. This work evaluated the hypothesis that a system combining a mixed culture of sulfate reducing bacteria (SRB) with zero valent iron would have a greater cr(VI) removal efficiency and a greater total Cr(VI) removal capacity than a zero valent iron system without the microorganisms. Hence, the overall goal of this research was to compare the performance of these types of systems with regard to their Cr(VI) removal efficiency and total Cr(VI) removal capacity. Both batch and continuous flow reactor systems were evaluated.
收起
