奶牛粪半连续全混式沼气发酵经验数学模型的研究

一、前言在沼气工程的工艺设计中,如何确定工艺参数是一个重要而又复杂的问题。了解在一定温度、进料浓度和滞留期条件下可能得到什么样的发酵效果,可以为优化设计提供依据,也可预测系统性能。沼气发酵的数     

车库型干法沼气工程高效自控系统的设计

阐述了车库型干法沼气工程的利弊,基于对此类工程的深入分析探讨,设计出一套高效可行的自动监控系统,通过系统与工程的结合,完全可解决车库型干法沼气工程主要的技术难题,为干法沼气工程在我国的引入及开展提供了相关的参考依据.     

干式厌氧发酵制沼气工艺方案设计及设备研究

沼液处理问题是目前沼气工程发展的主要障碍。文章从我国干式厌氧发酵研究的需要出发,设计了干式厌氧发酵制沼气工艺方案,主要包括工艺流程设计、厌氧反应系统物料平衡和热量平衡计算、主要单元工艺技术参数选择与确定等,为我国干式厌氧发酵研究提供了科学参考。     

大中型沼气工程技术讲座(一)厌氧发酵及工艺条件

建造大中型沼气工程,运用厌氧消化技术处理生产、生活污水及有机废弃物是促进城乡经济建设的持续发展,实现能源环保双重效益的重要手段。为此本刊从本期开始连载吉林省能源研究所高级工程师田晓东等撰写的大中型沼气工程技术讲座。本讲座从理论和实践相结合的角度,涉及厌氧发酵及工艺条件、工艺流程设计、发酵容器的设计、前处理及输配系统、工程启动及运行和工程应用实例等内容。     

大型热电肥联产沼气发电工程分析

从工艺流程、技术参数、运行状况以及效益分析等方面对现今国内畜禽场规模最大的沼气发电工程进行技术分析。运行表明,通过全混式厌氧发酵（CSTR）两级工艺,纯鸡粪进行厌氧发酵沼气发电是确实可行的;该工程的成功既解决了鸡粪污染,又产生了巨大的经济社会效益,对实现畜禽粪便综合利用具有良好的示范效果,并可为同类型沼气发电工程设计和建设提供参考。     

论太阳能与车库型干法沼气工程的完美结合

结合传统太阳能热利用工程与德国车库型干法沼气工程,设计出利用太阳能为沼气工程增温的太阳能沼气系统,并以高寒地区哈尔滨为例,对系统进行了初步估算。结果表明,车库型干法沼气工程适合与太阳能热利用工程实现一体化,结合太阳能热利用工程后该系统年可节约标煤159.6t,同时为系统的稳定运行提供了能源保障。     

3MW集中式热电肥联产沼气工程设计与建设

山东民和牧业股份有限公司利用所属23家养殖场的鸡粪和污水作为沼气发酵原料,投资建设大型畜禽养殖场集中式沼气发电工程.原料经水解除砂工艺将鸡粪中的砂砾除去,保证发酵效率;采用中温(38 ℃)发酵工艺,产沼气30 000 m3/d;采用高效率低运行成本的生物脱硫工艺,将沼气中的H2S含量降至200×10-6以下;经净化的沼气在双膜干式贮气柜中贮存,供给热电联产的发电机组使用.发电量60 000 kWh/d,机组余热用于冬季发酵系统自身增温;发酵后的沼液用作周围葡萄、苹果及玉米地的有机肥料.项目实现了温室气体减排84882tCO2当量.文章介绍了该沼气发电工程的工艺特点和技术要点,为同类型沼气发电工程设计和建设提供参考.     

全国沼气集中供气工程技术研讨会在杭召开

国家计委资源节约与综合利用司近日在杭州召开了全国沼气集中供气工程技术研讨会,会议就沼气集中供气工程的土建设计、安装施工、发酵工艺、仪表规范化及日常管理等问题进行广泛的技术交流和理论探讨。代表们一致认为,沼气集中供气工程具有显著的能源效益,随着商品经济的发展,它将逐步成为沼气     

浙江援助摩洛哥沼气工程新进展

1.ATLAS村沼气发电工程主要设备:80m~3和100m~3沼气池各一只,50m~3气柜一只,沼气脱硫塔,8kW沼气一柴油发电机.发酵原料为牲畜粪,发酵温度30±1℃(用太阳能加温),年平均产气率超过0.5m~3/(m~3·日),脱硫塔可除去沼气中90%的H_2 S.沼气-柴油发电机设计节油率为60%～70%,实测已达82%-84%. 此工程可为该村24户村民提供晚上5小时照明和看电视用电及白天4小时抽水用     

城市有机垃圾车库式干发酵技术

城市有机垃圾处理和资源再生利用已成为我国建设资源节约型和环境友好型社会中迫切需要解决的问题。欧洲国家中以德国为代表的车库式干发酵技术(Garage-type dry anaerobic digestion)已经成熟,可进行规模化的沼气生产。文章着重介绍了车库式干发酵沼气工程的技术要点,并以德国Loock TNS工艺和黑龙江宾县车库式干发酵项目为例,介绍了有机垃圾车库式干发酵喷淋回流、系统密封等关键技术,以期为我国车库式干发酵工程的工艺设计提供参考。     

Flexible power generation scenarios for biogas plants operated in Germany: impacts on economic viability and GHG emissions

Biogas plants enable power to be generated in a flexible way so that variable, renewable energy sources can be integrated into the energy system. In Germany, the Renewable Energy Sources Act promotes flexible power generation in biogas plants. Two existing biogas plants in flexible operation were analyzed with respect to economic viability and greenhouse gas (GHG) emissions to assess the feasibility of flexible operation. To do this, a biogas technology simulation model was developed to reproduce the technical design of both biogas plants and to link this design with twelve flexibilization scenarios. The evaluation of the economic viability is based on a discounting method of investment appraisal. For assessing the level of GHG emissions, the life cycle assessment method has been applied. The results show that the profitability of flexibilization is contingent upon premium payments promoting flexibility and direct sales resulting from a higher electrical efficiency of new or additionally installed combined heat and power units. Overall, with respect to profitability, the results of the flexible power generation scenarios are dependent upon the properties of the technical plant, such as its power generation and gas storage capacities. Relative GHG emissions from flexible biogas plants show significantly lower values than for referenced fossil gas–steam power stations. Among the various scenarios, the results reveal that the level of GHG emissions especially depends on the number of operating hours of the additional combined heat and power unit(s). The results of the analyzed biogas plants showed no direct correlation between GHG emissions and the economic benefits. Overall, a flexible power generation of biogas plants may improve the economic viability as well as result in lower GHG emissions in comparison with a conventional base load operation. © 2016 The Authors. International Journal of Energy Research published by John Wiley & Sons Ltd.     

Fuel processing of biogas for small fuel cell power plants

Biogas has a huge potential as fuel for fuel cell power plants. In the present work developments in fuel processing of biogas for a phosphoric acid fuel cell power plant to be located in rural India are described. Experimental work including steam reforming and shift conversion of biogas and methane has been carried out in a laboratory development unit. It is confirmed that biogas is not only a useful fuel but also that the carbon dioxide in biogas has a positive effect on methane conversion. The biogas fuel cell power plant will give a high electrical efficiency on the small scale of biogas units.     

Results from an industrial size biogas-fed SOFC plant (the DEMOSOFC project)

The EU-funded DEMOSOFC project aims to demonstrate the technical and economic feasibility of operating a 174 kW_e Solid Oxide Fuel Cell (SOFC) in a wastewater treatment plant. The fuel for the three SOFC modules (3 × 58 kW_e) is biogas, which is available on-site from the anaerobic digestion of sludge collected from treated wastewater. The integrated biogas-SOFC plant includes three main units: 1) the biogas cleaning and compression section, 2) the three SOFC power modules, and 3) the heat recovery loop. Main advantages of the proposed layout are the net electric efficiency of the SOFC, which is in the range 50–55%, and the near-zero emissions. A specific focus of the demonstration project is the deep and reliable removal of harmful biogas contaminants. The presented work is related to the design of the SOFC system integrated into the wastewater treatment plant, followed by the analysis of the first results from the plant operation. We analyzed the biogas yearly profile to determine the optimal SOFC capacity to install that is 3 SOFC modules. The rational is to maintain high the capacity factor while minimizing the number of shutdown per year (due to biogas unavailability). First results from plant operation are also presented. The first SOFC module was activated in October 2017 and the second in October 2018. The measured SOFC efficiency from compressed biogas to AC power has always been higher than 50–52%, with peaks of 56%. Dedicated emissions measurements have been performed onsite during December 2017. Results on real biogas operation show NO_x < 20 mg/m³, SO₂ < 8 mg/m³ (detection limits for the instrument) and PM lower than ambient air values.     

Study of MW-scale biogas-fed SOFC-WGS-TSA-PEMFC hybrid power technology as distributed energy system: Thermodynamic,exergetic and thermo-economic evaluation

Advanced biogas power generation technology has been attracting attentions, which contributes to the waste disposal and the mitigation of greenhouse gas emissions. This work proposes and models a novel biogas-fed hybrid power generation system consisting of solid oxide fuel cell, water gas shift reaction, thermal swing adsorption and proton exchange membrane fuel cell (SOFC-WGS-TSA-PEMFC). The thermodynamic, exergetic, and thermo-economic analyses of this hybrid system for power generation were conducted to comprehensively evaluate its performance. It was found that the novel biogas-fed hybrid system has a gross energy conversion efficiency of 68.63% and exergy efficiency of 65.36%, indicating high efficiency for this kind of hybrid power technology. The market sensitivity analysis showed that the hybrid system also has a low sensitivity to market price fluctuation. Under the current subsidy level for the distributed biogas power plant, the levelized cost of energy can be lowered to 0.02942 $/kWh for a 1 MW scale system. Accordingly, the payback period and annual return on investment can reach 1.4 year and about 20%, respectively. These results reveal that the proposed hybrid system is promising and economically feasible as a distributed power plant, especially for the small power scale (no more than 2 MW).     

Investigation of green hydrogen production and development of waste heat recovery system in biogas power plant for sustainable energy applications

In this study, biogas power production and green hydrogen potential as an energy carrier are evaluated from biomass. Integrating an Organic Rankine Cycle (ORC) to benefit from the waste exhaust gases is considered. The power obtained from the ORC is used to produce hydrogen by water electrolysis, eliminate the H₂S generated during the biogas production process and store the excess electricity. Thermodynamic and thermoeconomic analyses and optimization of the designed Combined Heat and Power (CHP) system for this purpose have been performed. The proposed study contains originality about the sustainability and efficiency of renewable energy resources. System design and analysis are performed with Engineering Equation Solver (EES) and Aspen Plus software. According to the results of thermodynamic analysis, the energy and exergy efficiency of the existing power plant is 28.69% and 25.15%. The new integrated system's energy, exergy efficiencies, and power capacity are calculated as 41.55%, 36.42%, and 5792 kW. The total hydrogen production from the system is 0.12412 kg/s. According to the results of the thermoeconomic analysis, the unit cost of the electricity produced in the existing power plant is 0.04323 $/kWh. The cost of electricity and hydrogen produced in the new proposed system is determined as 0.03922 $/kWh and 0.181 $/kg H₂, respectively.     

Modeling of coupling gasification and anaerobic digestion processes for maize bioenergy conversion

This work estimates the advantages of using maize as fuel in a power plant composed of an anaerobic digester, a gasifier and an Internal Combustion (IC) engine. The digester is fed with maize grains, while, the remaining part of the plant, the stover, is gasified. Then biogas and syngas streams are both used as fuel into the engine. The performance of this plant was evaluated coupling gasification and anaerobic digestion mathematical models. Results of the proposed solution are compared with the performance of a 100 kW biogas power plant fed with the whole crop silaged. Results show that the overall energy yield of the improved solution is 39% higher than the conventional one fed with maize silage. This method will lead to the design of small and cheap digesters as a result of the increased conversion rate. In fact, the solution proposed fully converts the high cellulose-fiber parts of the maize plant that were tough to degrade in anaerobic digesters.     

Conclusions from the Representative of the European Parliament

This article describes a co-generation plant based on the biogas being produced from the waste of distillery plant and highlights the possible configuration in which the plant can be hybridized with auxiliary solar energy source having the advantage of using financial incentives in several countries. In hybridization, the solar heat is used for heating the boiler feed water. The solar heat-generating unit consists of line focus parabolic trough collector, heat transportation system and heat delivery unit such as heat exchanger. The simulation model of heat and mass transfer processes in the solar field as well as the balance of the system is developed to investigate the technological feasibility of the concept in terms of plant yield and matching of subsystems.     

Bioenergy recovery analysis from various waste substrates by employing a novel industrial scale AD plant

In this novel industrial scale case study, the bioenergy recovery based on sole and mixed cow-buffalo (CBM) and potato waste (PW) substrates has been analyzed in real time, i.e., on-site on a full-scale operational anaerobic digestion (AD) plant. The plant employed in this study is a novel design, consisting of tri-digesters connected via an underground upflow anaerobic sludge blanket (UASB) type lagoon allowing it to function as a continuous-flow reactor. The system has been further equipped with CSTR, microwave heating, gas scrubbers, compression, and storage systems. The highest energy recovery readings were 123.9 m³/1,000 kg, 77 m³/1,000 kg, and 151.6 kWh/1,000 kg in terms of biogas, bio-methane, and electricity generated, respectively, with 75:25 ratio of CBM:PW. Operating with 100% CBM, yields of 79.9 m³/1,000 kg, 47 m³/1,000 kg, and 95 kWh/1,000 kg were obtained. The percentage of recovery in bio-methane production increased on using the mixed substrates, but it was the lowest with a 25:75 ratio of CBM:PW. The electrical power generation efficiency was found to be significantly increased, but not distinctively with the plant aggregate power rating that was probably associated with the variable quality of biogas which was fed to the power generator. A linear regression analysis had shown a significant and positive correlation between the rate of VS removal and biogas yield.     

Design and performance evaluation of biogas stove for community cooking application

Matured biogas production technology has led to the development of a number of biogas appliances for lighting, power generation, and cooking. The most promising among them is the biogas stove, to meet the energy requirement for cooking application at domestic as well as at the community level. In this paper, an attempt has been made to design and develop a community biogas stove for baking chapatti (bread) or other food items on a hotplate for canteen or community purposes. The performance of the stove was evaluated by using a 25 m³ floating type biogas plant at Asha Dham Asharm, Udaipur, India. The gas consumption rating of the developed stove was 1 m³ (19 MJ/h) and the cooking efficiency of the stove was recorded to be about 43.96%.