一种新型气力式给煤粉装置的研制与实验

在分析总结几种气力式给粉装置的基础上,针对煤粉低尘燃烧技术工程开发中遇到的给粉量不均匀、不稳定等问题,设计了一种直立螺旋-气固喷射器小型给粉装置,该给粉装置巧妙地组合了螺杆与喷射器两个部件,结构简单,控制方便。实测数据结果表明,该装置满足小型煤粉燃烧器供煤量的要求,研制的产品达到了实用化水平。     

Co-production of hydrogen and carbon black from solar thermal methane splitting in a tubular reactor prototype

This study addresses the solar thermal decomposition of natural gas for the co-production of hydrogen and carbon black (CB) as a high-value nano-material with the bonus of zero CO₂ emission. The work focused on the development of a medium-scale solar reactor (10 kW) based on the indirect heating concept. The solar reactor is composed of a cubic cavity receiver (20 cm-side), which absorbs concentrated solar irradiation through a quartz window by a 9 cm-diameter aperture. The reacting gas flows inside four graphite tubular reaction zones that are settled vertically inside the cavity. Experimental results in the temperature range 1740-2070 K are presented: acetylene (C₂H₂) was the most important by-product with a mole fraction of up to about 7%, depending on the gas residence time. C₂H₂ content in the off-gas affects drastically the carbon yield of the process. The effects of temperature and residence time are analyzed. A preliminary process study concerning a 55 MW solar chemical plant is proposed on the basis of a process flow sheet. Results show that 1.7 t/h of hydrogen and 5 t/h of CB could be produced with an hydrogen cost competitive to conventional steam methane reforming.     

Simultaneous production of hydrogen and carbon nanotubes from cracking of a waste cooking oil model compound over Ni-Co/SBA-15 catalysts

Hydrogen is considered an ideal energy carrier. However, the use of fossil fuels to produce hydrogen depletes natural resources and causes environmental problems. Therefore, there is an urgent need to find alternative raw materials and technologies for the production of hydrogen. Waste cooking oil (WCO) is a renewable energy source that has emerged as a potential raw material for hydrogen production. This study describes the production of hydrogen and carbon nanotubes (CNTs) by catalytic cracking of a WCO model compound (WCOMC) performed in a lab-scale fixed bed using Ni-Co/SBA-15 catalysts. The phase, structure and reduction properties of the catalyst were analysed by using different characterisation methods. The effects of the nickel-cobalt metal content and the reaction temperature on both the hydrogen production and the quality of the CNTs were investigated. The deposited carbonaceous products were characterised to analyse their external appearance, internal structure, oxidation stability and graphitisation degree. The results indicated that the catalyst containing 20% Ni and 30% Co showed the highest activity. When reaction temperature was 800°C, the instantaneous volume fraction of hydrogen was close to 43.5 vol% and the content of hydrogen in the gas product was close to 66.5 vol%. A few multi-walled CNTs having a small diameter and some CNTs with an open-topped structure were deposited on 10%Ni-40%Co/SBA-15 and 30%Ni-20%Co/SBA-15, respectively. Thermogravimetric analysis and Raman spectroscopic analysis indicated that all CNTs showed high oxidation stability and a high degree of graphitisation.     

Competition between first and second generation technologies: Lessons from the formation of a biofuels innovation system in the Netherlands

The support of sustainable energy innovations has become a dominant topic on the political agenda of many countries. Providing this support remains difficult, since the processes constituting such innovation trajectories are poorly understood. To increase insight in such processes, this paper takes the historical development of biofuels in the Netherlands as the topic of study. Special attention is paid to the simultaneous development of two technology generations within the field: a first generation (1G) and a second generation (2G) of biofuels. A critical question asked is whether deployment programmes for a 1G technology may have positive effects on the development of later generations. Two archetypical support strategies are identified: one is to keep investing in R&D concerning 2G technology, where the expected outcome is a fast move from one technology generation to the other. The other strategy is to focus on learning-by-doing in the 1G technology. In that way progress can be made in 1G technologies but the effects on 2G technologies are uncertain. We apply a Technological Innovation System perspective to analyse the strategies followed and their effects. From the results we draw lessons of relevance for practitioners who aspire to understand and influence emerging energy technologies.     

ISO9001质量管理体系在多缸柴油机装配试车涂装项目中的应用

介绍了某多缸柴油机装配试车涂装项目工程。依据ISO9001(2000)标准，将质量管理体系应用于该项目中，确保了供应商在设计、制造、安装和服务阶段都符合规定的质量要求。     

教务管理系统开发实例

介绍了一种简单的教务管理系统的设计和实现方法,该教务管理系统由Borland公司的C++Builder 6.0与微软公司的SQL相结合实现教务管理的。本系统具有如下特点:精确查询功能,关键字查询,相关数据的增删,浏览等。是C++Builder 6.0的程序开发部分及与数据库相连接部分的介绍。     

More than food or fuel. Stakeholder perceptions of anaerobic digestion and land use; a case study from the United Kingdom

Anaerobic digestion (AD) is of growing importance within the UK as it can make an important contribution to the countries energy and climate change targets. With the growth of the sector, discussions about competing land uses are likely to increase. For a better understanding of the synergies between agricultural land, its role and bioenergy the perception of the different stakeholders will play an important role. The perception of stakeholders related to AD, feedstock and energy crop production was investigated through interviews and a stakeholder workshop. The results indicated that from an AD operator and feedstock producer perspective, on-farm AD is more an additional activity integrated into existing agricultural systems than a renewable energy technology. The risk of a shift in agricultural practices and large areas to grow energy crops for AD is seen as low for the UK. Nonetheless, land use and related challenges need to be considered as the demand for AD feedstocks increases with the fast growth of the sector. Considering the synergies between bioenergy and agriculture as well as the motivations and benefits perceived by stakeholders will play an important role in a successful policy design to provide the required emission reduction in both sectors without subverting sustainability.     

Influence of undulating wall heat and mass flux on MHD natural convection boundary layer flow from a vertical wall

Current study expounds an unsteady magnetohydrodynamic natural convective flow along a vertical wall in presence of variable transverse magnetic field. Small amplitude undulation in wall heat flux and wall mass flux are imposed at the vertical wall to generate the boundary layer flow. The flow governing equations are divided into sets of steady and unsteady equations and then transformed into the similarity and nonsimilarity equations, respectively, by introducing stream function formulations. The sets of nonsimilarity equations are solved numerically by using three different techniques, namely, perturbation solution technique, asymptotic solution technique and implicit finite difference technique applied, respectively, for lower, higher, and all frequencies (ξ). Results are illustrated in connection with the amplitude and phase angles of shear stress, wall temperature, and concentration against the frequency (ξ) for wide ranges of physically significant parameters. Likening of the results obtained by above mentioned numerical methods are presented in every figure and table. Results reveal that the amplitude of undulating shear stress and wall temperature dwindle and the amplitude of wall concentration increases due to increment in Prandtl number (Pr). Besides, on incrementing Schmidt number (Sc) the amplitude of undulating shear stress and wall concentration dwindle and the amplitude of wall temperature increases. Results also reveal that on incrementing magnetic parameter (M) the amplitude of transient shear stress dwindles while the amplitude of transient wall temperature and concentration increase.     

Cell growth and hydrogen production on the mixture of xylose and glucose using a novel strain of Clostridium sp. HR-1 isolated from cow dung compost

A novel mesophilic hydrogen-producing bacterium was isolated from cow dung compost and designated as Clostridium sp. HR-1 by 16S rRNA gene sequence. The optimum condition for hydrogen production by strain HR-1 was pH of 6.5, temperature of 37 °C and yeast extract as nitrogen sources. The strain HR-1 has the ability to utilize kinds of hexose and pentose as carbon sources for growth and H₂ production. Cell growth and hydrogen productivity were investigated for batch fermentation on media containing different ratios of xylose and glucose. Glucose was the preferred substrate in the glucose and xylose mixtures. The high glucose fraction had higher cell biomass production rate. The rate of glucose consumption was higher than xylose consumption, and remained essentially constant independent of xylose content of the mixture. The rate of xylose utilization was decreased with increasing of the glucose fraction. The average H₂ yield and specific H₂ production rates with xylose and glucose are 1.63 mol-H₂/mol xylose and 11.14-H₂ mmol/h g-cdw, and 2.02 mol-H₂/mol-glucose and 9.37 mmol-H₂/h g-cdw, respectively. Using the same initial substrate concentration, the maximum average H₂ yield and specific H₂ production rates with the mixtures of 9 g/l xylose and 3 g/l glucose was 2.01 mol-H₂/mol-mixed sugar and 12.56 mmol-H₂/h g-cdw, respectively. During the fermentation, the main soluble microbial products were ethanol and acetate which showed trends with the different ratios of xylose and glucose.     

The effects of seed sludge and hydraulic retention time on the production of hydrogen from a cassava processing wastewater and glucose mixture in an anaerobic fluidized bed reactor

The potential for co-fermentation of a cassava processing wastewater and glucose mixture was studied in anaerobic fluidized bed reactors. The effects of different hydraulic retention times (HRTs) (10–2 h) and varying sources of inoculum are reported. The sludge from a UASB reactor that had been used to treat poultry slaughterhouse wastewater (SP) resulted in the highest yields of hydrogen (HY) and ethanol (EtOHY) of 1.0 mmol H₂ g⁻¹ COD (10 h) and 3.0 mmol EtOH g⁻¹ COD (6 h). The sludge from a UASB reactor used for the treatment of swine wastewater (SW) resulted in a maximum HY of 0.65 mmol H₂ g⁻¹ COD (6 h) and EtOHY of 2.1 mmol g⁻¹ COD (10 and 8 h). Methane was produced with a maximum production of 9.68 L CH₄ d⁻¹ L⁻¹. Based on phylogenetic analysis of 16S rRNA, bacteria and methanogenic archaea similar to Lactobacillus and Methanobacterium, respectively, were identified.     

Thermodynamic and exergoeconomic analysis of energy recovery system of biogas from a wastewater treatment plant and use in a Stirling engine

The aim of this research it is to show how the biogas biomethanisation from primary and secondary treatment of activated sludge from a wastewater treatment plant (WWTP), can be an alternative renewable energy option from fossil fuels, which offers competitive advantages and points out new horizons for the use of this fuel. This will allow to achieve some important priorities of energy plans in EU countries: to reduce the organic matter deposited in landfills and CO₂ emissions and to find viable solutions to minimize the environmental impact of sewage sludge (SS).This study analyses the biogas combustion and energy recovery processes from a thermodynamic, thermoeconomic and exergetic point of view.The results show that the boiler of the process is the main source of irreversibility and exergy destruction. Moreover, the energy and exergy economic value of exhaust gases from the combustion chamber, are significant and worthwhile to be exploited. For this reason, the present study explores the applicability and suitability of integrating a Stirling engine in such process. The study reveals that it is possible to create a small micro-cogeneration system which leads to sustainable waste management and energy savings in the treatment plant itself.     

Preparation of hydrogen from metals and water without CO2 emissions

Considering the high calorific value and low-carbon characteristics of hydrogen energy, it will play an important role in replacing fossil energy sources. The production of hydrogen from renewable energy sources for electricity generation and electrolysis of water is an important process to obtain green hydrogen compared with classic low-carbon hydrogen production methods. However, the challenges in this process include the high cost of liquefied hydrogen and the difficulty of storing hydrogen on a large scale. In this paper, we propose a new route for hydrogen storage in metals, namely, electricity generation from renewable energy sources, electrolysis to obtain metals, and subsequent hydrogen production from metals and water. Metal monomers facilitate large-scale and long-term storage and transportation, and metals can be used as large-scale hydrogen storage carriers in the future. In this technical route, the reaction between metal and water for hydrogen production is an important link. In this paper, we systematically summarize the research progress, development trend, and challenges in the field of metal to hydrogen production. This study aim to aid in the development of this field.