生物制氢反应系统的启动负荷与乙醇型发酵

采用连续流搅拌槽式反应器(CSTR),以糖蜜废水为底物,研究了COD容积负荷对生物制氢反应系统启动过程中形成的乙醇型发酵产氢能力的影响。研究表明,在污泥接种量不小于6.24 gVSS/L、启动负荷为7.0 kgCOD/m3.d、水力停留时间(HRT)为6 h、系统pH、氧化还原电位(ORP)分别在4.0~4.3、-440~-470mV之间等条件下,可在30 d内完成乙醇型发酵菌群的驯化,实现生物制氢反应系统的快速启动。由不同启动负荷(3.0、7.0、10.0 kgCOD/m3.d)条件下形成的乙醇型发酵菌群,在相同的运行条件下其产氢能力存在着差异。当系统容积负荷为30 kgCOD/m3.d时,由启动负荷为7.0 kgCOD/m3.d条件下驯化形成的乙醇型发酵菌群比由启动负荷为3.0 kgCOD/m3.d条件下驯化形成的乙醇型发酵菌群产氢能力高56%。     

浅谈柴油机的低负荷性能

本文首先分析了柴油机低负荷问题的严重性,必须引起人们高度重视。然后从柴油机低负荷工况工作机理出发,分析了柴油机低负荷运转产生的问题的原因,并用国内外成功事例阐述了解决的途径和技术措施。供柴油机工作者参考。     

燃油燃气锅炉低负荷运行技术

对65t／h燃油燃气锅炉低负荷运行技术瓶颈进行了剖析,重点介绍了锅炉低负荷运行时所采取的技术措施,并首次提出了“当量饱和蒸汽压力”概念。     

柴油机低负荷性能的研究

本文介绍柴油机在低负荷运转时的工作特点和带来的问题（柴油机低负荷工作时性能不稳、工作不可靠、经济性恶化）及国内外为改善低负荷性能所采取的措施和效果。还介绍了为改善１９０系列柴油机低负荷性能所进行的研究工作和所取得的成果。     

工业锅炉低负荷运行的原因分析及解决措施

工业锅炉低负荷运行情况普遍存在,不仅会造成工业锅炉运行安全性、经济性下降,而且对环境污染的影响也已得到广泛的认知。从工业锅炉容量选配、供热热负荷变化的角度,对引起工业锅炉低负荷运行的原因进行了分析,并提出相应的解决措施。     

燃煤电厂低负荷脱硝性能提升技术综述

简要介绍和总结了解决低负荷脱硝问题的可行技术,同时提出了提升低负荷脱硝性能可采用烟温提升、更换宽温催化剂和SO3脱除技术3种技术方案.烟温提升方案存在能耗高的问题;宽温催化剂处于示范应用阶段,可靠性和稳定性还需实践检验;SO3脱除技术是一种解决低负荷脱硝问题的新思路.     

采用可变技术提高发动机低速低负荷时的性能

本文详细介绍了在发动机上应用的几种可变技术.探讨了如何采用可变技术以减少换气损失或将汽油机工况点转移,从而改善发动机在低速低负荷时的动力性和经济性.     

可再生能源制氢系统制氢电源研究

利用风电、光伏发电等可再生能源电力的制氢系统是未来制备氢能的发展方向,而制氢电源是制氢系统的核心部件.传统的基于晶闸管整流电路的制氢电源(下文简称为"晶闸管制氢电源")存在功率因数低、谐波大,延迟长等缺点.针对这一问题,本文采用PWM整流器作为制氢电源(下文简称为"PWM制氢电源"),把逆变电路中的SPWM调制和数字控...     

190舰用柴油机低负荷性能改进

本文介绍了柴油机低负荷运行的特点及解决途径,并介绍了为改善1 90舰用柴油机低负荷性能所进行的改进工作和所取得的效果。     

An integrated system for hydrogen and methane production during landfill leachate treatment

The patent-pending integrated waste-to-energy system comprises both a novel biohydrogen reactor with a gravity settler (Biohydrogenator), followed by a second stage conventional anaerobic digester for the production of methane gas. This chemical-free process has been tested with a synthetic wastewater/leachate solution, and was operated at 37 °C for 45 d. The biohydrogenator (system (A), stage 1) steadily produced hydrogen with no methane during the experimental period. The maximum hydrogen yield was 400 mL H₂/g glucose with an average of 345 mL H₂/g glucose, as compared to 141 and 118 mL H₂/g glucose for two consecutive runs done in parallel using a conventional continuously stirred tank reactor (CSTR, System (B)). Decoupling of the solids retention time (SRT) from the hydraulic retention time (HRT) using the gravity settler showed a marked improvement in performance, with the maximum and average hydrogen production rates in system (A) of 22 and 19 L H₂/d, as compared with 2–7 L H₂/d in the CSTR resulting in a maximum yield of 2.8 mol H₂/mol glucose much higher than the 1.1–1.3 mol H₂/mol glucose observed in the CSTR. Furthermore, while the CSTR collapsed in 10–15 d due to biomass washout, the biohydrogenator continued stable operation for the 45 d reported here and beyond. The methane yield for the second stage in system (A) approached a maximum value of 426 mL CH₄/gCOD removed, while an overall chemical oxygen demand (COD) removal efficiency of 94% was achieved in system (A).     

Techno-economic and environmental performances of glycerol reforming for hydrogen and power production with low carbon dioxide emissions

This paper is evaluating from the conceptual design, thermal integration, techno-economic and environmental performances points of view the hydrogen and power generation using glycerol (as a biodiesel by-product) reforming processes at industrial scale with and without carbon capture. The evaluated hydrogen plant concepts produced 100,000 Nm³/h hydrogen (equivalent to 300 MW_th) with negligible net power output for export. The power plant concepts generated about 500 MW net power output. Hydrogen and power co-generation was also assessed. The CO₂ capture concepts used alkanolamine-based gas–liquid absorption. The CO₂ capture rate of the carbon capture unit is at least 90%, the carbon capture rate of the overall reforming process being at least 70%. Similar designs without carbon capture have been developed to quantify the energy and cost penalties for carbon capture. The various glycerol reforming cases were modelled and simulated to produce the mass & energy balances for quantification of key plant performance indicators (e.g. fuel consumption, energy efficiency, ancillary energy consumption, specific CO₂ emissions, capital and operational costs, production costs, cash flow analysis etc.). The evaluations show that glycerol reforming is promising concept for high energy efficiency processes with low CO₂ emissions.     

Research on non-grid-connected wind power/water-electrolytic hydrogen production system

Hydrogen has been recognized as the most promising future energy carrier. At present, industrial hydrogen production processes are not independent of traditional energy resources, which could easily cause secondary pollution. China has abundant wind energy resources. The total installed capacity of wind power doubled every year in the last five years, and reached 26 000 MW by the end of 2009, but over 9880 MW wind turbines were not integrated into grid because of the peak shaving restraint. In this paper, wind power is directly used in water-electrolytic process by some technical improvements, to design non-grid-connected wind power/water-electrolytic hydrogen production system. The system all works properly, based on not only the wind/grid complementary power supply but also the independent supply of simulation wind power. The large-scale fluctuation of current density has little impact on current efficiency and gas quality, and only affects gas output. The new system can break through the bottlenecks of wind power utilization, and explore a diversified development way of large-scale wind power, which will contribute to the development of green economy and low carbon economy in China.     

Modeling of hydrogen production with a stand-alone renewable hybrid power system

Hydrocarbon resources adequately meet today’s energy demands. Due to the environmental impacts, renewable energy sources are high in the agenda. As an energy carrier, hydrogen is considered one of the most promising fuels for its high energy density as compared to hydrocarbon fuels. Therefore, hydrogen has a significant and future use as a sustainable energy system. Conventional methods of hydrogen extraction require heat or electrical energy. The main source of hydrogen is water, but hydrogen extraction from water requires electrical energy. Electricity produced from renewable energy sources has a potential for hydrogen production systems. In this study, an electrolyzer using the electrical energy from the renewable energy system is used to describe a model, which is based on fundamental thermodynamics and empirical electrochemical relationships. In this study, hydrogen production capacity of a stand-alone renewable hybrid power system is evaluated. Results of the proposed model are calculated and compared with experimental data. The MATLAB/Simscape^® model is applied to a stand-alone photovoltaic-wind power system sited in Istanbul, Turkey.     

Design,modelling and optimal power and hydrogen management strategy of an off grid PV system for hydrogen production using methanol electrolysis

Hydrogen used as an energy carrier and chemical element can be produced by several processes such as gasification of coal and biomass, steam reforming of fossil fuel and electrolysis of water. Each of these methods has its own advantage and disadvantage. Electrolysis process is seen as the best option for quick hydrogen production. Hydrogen generation by methanol electrolysis process (MEP) gained much attention since it guarantees high purity gas and can be compatible with renewable energies. Furthermore, due to its very low theoretical potential (0.02 V), MEP can save more than 65% of electrical energy required to produce 1 kg of hydrogen compared to water electrolysis process (WEP). Electrolytic hydrogen production using solar photovoltaic (PV) energy is positioned to become as one of the preferred options due to the harmful environmental impacts of widely used methane steam reforming process and also since the prices of PV modules are more competitive.In this paper, hydrogen production by MEP using PV energy is investigated. A design of an off grid PV/battery/MethElec system is proposed. Mathematical models of each component of the system are presented. Semi-empirical relationship between hydrogen production rate and power consumption at 80 °C and 4 M concentration is developed. Optimal power and hydrogen management strategy (PHMS) is designed to achieve high system efficiency and safe operation. Case studies are carried out on two tilts of PV array: horizontal and tilted at 36° using measured meteorological data of solar irradiation and ambient temperature of Algiers site. Simulation results reveal great opportunities of hydrogen production using MEP compared to the WEP with 22.36 g/m² d and 24.38 g/m² d of hydrogen when using system with horizontal and tilted PV array position, respectively.     

Modeling and control design of hydrogen production process for an active hydrogen/wind hybrid power system

This paper gives a control oriented modeling of an electrolyzer, as well as the ancillary system for the hydrogen production process. A Causal Ordering Graph of all necessary equations has been used to illustrate the global scheme for an easy understanding. The model is capable of characterizing the relations among the different physical quantities and can be used to determine the control system ensuring efficient and reliable operation of the electrolyzer. The proposed control method can manage the power flow and the hydrogen flow. The simulation results have highlighted the variation domains and the relations among the different physical quantities. The model has also been experimentally tested in real time with a Hardware-In-the-Loop Simulation before being integrated in the test bench of the active wind energy conversion system.     

低负荷热水采暖系统循环动力的节能性分析

分析低负荷热网循环系统的水力工况,指出在流量一定的情况下,合理确定扬程不仅可以保证供热质量,也可避免大流量、低温差不合理运行的模式,有利于节能。     

Steady-state and dynamic modeling of biohydrogen production in an integrated biohydrogen reactor clarifier system

Steady-state operational data from the integrated biohydrogen reactor clarifier system (IBRCS) during anaerobic treatment of glucose-based synthetic wastewater at HRT of 8 h and SRT ranging from 26 to 50 h and organic loading rates of 6.5–206 gCOD/L-d were used to calibrate and verify a process model of the system developed using BioWin. The model accurately predicted biomass concentrations in both the bioreactor and the clarifier supernatant with average percentage errors (APEs) of 4.6% and 10%, respectively. Hydrogen production rates and hydrogen yields predicted by the model were in close agreement with the observed experimental results as reflected by an APE of less than 4%, while the hydrogen content was well correlated with an APE of 10%. The successful modeling culminated in the accurate prediction of soluble metabolites, i.e. volatile fatty acids in the reactor with an APE of 14%. The calibrated model confirmed the advantages of decoupling of the solids retention time (SRT) from the hydraulic retention time (HRT) in biohydrogen production, with the average hydrogen yield decreasing from 3.0 mol H₂/mol glucose to 0.8 mol H₂/mol glucose upon elimination of the clarifier. Dynamic modeling showed that the system responds favorably to short-term hydraulic and organic surges, recovering back to the original condition. Furthermore, the dynamic simulation revealed that with a prolonged startup periods of 10 and 30 days, the IBRCS can be operated at an HRT of 4 h and OLR as high as 206 gCOD/L-d without inhibition and/or marked performance deterioration.     

Thermodynamic analysis and assessment of a novel integrated geothermal energy-based system for hydrogen production and storage

In this paper, thermodynamic analysis and assessment of a novel geothermal energy based integrated system for power, hydrogen, oxygen, cooling, heat and hot water production are performed. This integrated process consists of (a) geothermal subsystem, (b) Kalina cycle, (c) single effect absorption cooling subsystem and (d) hydrogen generation and storage subsystems. The impacts of some design parameters, such as absorption chiller evaporator temperature, geothermal source temperature, turbine input pressure and pinch point temperature on the integrated system performance are investigated to achieve more efficient and more effective. Also, the impacts of reference temperature and geothermal water temperature on the integrated system performance are studied in detail. The energetic and exergetic efficiencies of the integrated system are then calculated as 42.59% and 48.24%, respectively.     

Performance assessment of an integrated PV/T and triple effect cooling system for hydrogen and cooling production

In this paper we study an integrated PV/T absorption system for cooling and hydrogen production based on U.A.E weather data. Effect of average solar radiation for different months, operating time of the electrolyzer, air inlet temperature and area of the PV module on power and rate of heat production, energy and exergy efficiencies, hydrogen production and energetic and exergetic COPs are studied. It is found that the overall energy and exergy efficiency varies greatly from month to month because of the variation of solar radiation and the time for which it is available. The highest energy and exergy efficiencies are obtained for the month of March and their value is 15.6% and 7.9%, respectively. However, the hydrogen production is maximum for the month of August and its value is 9.7 kg because in august, the solar radiation is high and is available for almost 13 h daily. The maximum energetic and exergetic COPs are calculated to be 2.28 and 2.145, respectively and they are obtained in the month of June when solar radiation is high for the specified cooling load of 15 kW.