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1.
城市有机生活垃圾高温厌氧转化生物质能研究   总被引:5,自引:0,他引:5  
在国内外已有的研究基础上,对城市有机生活垃圾的高温厌氧(批量)消化工艺实验进行了初步探索,研究了在55℃的高温条件下累积产气量与消化时间的关系,C/N比与产气量的关系,消化过程中pH值变化,并研究了垃圾高温发酵实验过程中沼气中的CH4和CO2的含量变化,其中甲烷含量最高可达75.3%。实验结果表明,城市生活垃圾高温消化的降解效果较好,产气量较高,启动时间短。  相似文献   

2.
厨余垃圾厌氧消化制取甲烷的影响因素研究   总被引:1,自引:1,他引:0  
介绍我国厨余垃圾的现状及潜在危害,从垃圾性质(自身底物成分、C/N、颗粒大小)、工艺条件(温度、pH值、搅拌强度、添加金属离子、添加载体、接种量、挥发性脂肪酸含量)及工艺流程(预处理、消化气回流、先产氢再甲烷化、间断/连续式消化、干发酵后堆肥工艺及混合物料发酵工艺)等方面,综述了影响厨余垃圾厌氧消化的因素及优化厌氧消化的工艺条件,指出提高我国厨余垃圾厌氧消化技术需要解决的问题及今后的研究方向,并对我国城市生活垃圾综合处理提出合理性建议.  相似文献   

3.
采用高温厌氧消化处理方法对城市生活有机垃圾进行了中试试验研究.其有机垃圾产气量73.4m3/t,产气速率0.52m3/m3.d,COD去除率48.8%.结果表明,高温厌氧消化处理是城市生活有机垃圾较好的处理方式之一.有机垃圾不仅可以得到处理,最大限度地减少其污染环境;同时,还可以产生一定的经济效益和巨大的环境效益.这种垃圾处理方式值得应用和推广.  相似文献   

4.
干式厌氧发酵技术现状与国内应用项目简介   总被引:1,自引:0,他引:1  
针对当前农业、工业及城市排放中的大量高浓度有机固体废弃物须要进行无害化处理和资源化利用的问题,文章从生物无害化处理的角度对当前的应用技术进行了探讨。从厌氧消化项目示范角度分析了国内外干式厌氧发酵技术工艺研究现状,并结合当前干法发酵工艺及反应器开发的进展,列举了在国内稳定运行的3个干式发酵案例,对各发酵工艺的优缺点进行了阐述。通过对干式厌氧技术及应用现状的阐述与分析,为干式厌氧发酵技术的发展及实际应用提供借鉴和指导。  相似文献   

5.
生物质垃圾作为城市生活垃圾最主要的组成部分,给传统的生活垃圾处理处置方式造成许多不利的影响。干法厌氧凭借其单位容积产气量高、需水量少、单位容积处理量大、消化后的沼渣不需脱水即可作为肥料等优点,成为生物质废弃物处理中比较热门的工艺,也是未来生物质废弃物处理处置的风向标[1]。在国内外对生物质干法厌氧消化研究的基础上,利用干法厌氧消化中试实验装置,进行了以生物质废弃物为原料,以厌氧污泥和猪粪为接种物的干法厌氧消化实验。实验中物料的含固率在20%左右,接种比例在26%左右,温度控制在35℃左右。  相似文献   

6.
以城市生活垃圾和污水厂剩余污泥为消化原料,在中温(35℃)条件下,采用序批式厌氧消化方式,研究了生活垃圾和剩余污泥不同混合比例下的厌氧消化产气性能,以及不同原料配比对厌氧消化过程及消化效率的影响。按照生活垃圾和剩余污泥VS比分别为1∶0(R1),2∶1(R2),1∶1(R3),1∶2(R4)和0∶1(R5),试验设置了5个试验组。研究结果表明:两种物料混合后有助于提高消化效果和产气性能,其中,当城市生活垃圾和剩余污泥VS比为2∶1时,系统厌氧消化效果最好,VS去除率为35.98%,单位VS产气量为348.84 m L/g,产气中甲烷含量为53.8%,消化时间较单纯生活垃圾厌氧消化缩短了9 d。说明一定比例的生活垃圾和剩余污泥联合厌氧消化是提高厌氧消化效率的有效途径。  相似文献   

7.
我国餐厨垃圾产量日益增加,其资源化处理越来越受到人们重视。两相厌氧消化工艺中水解酸化阶段和产甲烷阶段相对独立,具有更多的优势。本文介绍了两相厌氧消化工艺的发展过程和餐厨垃圾的特性,研究了国内外餐厨垃圾两相厌氧消化制沼气技术的进展情况,以期为我国餐厨垃圾的快速高效处理提供参考。  相似文献   

8.
我国城市生活垃圾厌氧消化处理的探讨   总被引:3,自引:0,他引:3  
分析了我国城市生活垃圾处理现状及存在问题,探讨了以厌氧消化技术为主的城市生活垃圾处理方式,为解决我国的城市生活垃圾问题提供参考。  相似文献   

9.
餐厨垃圾厌氧消化的工艺比选研究   总被引:3,自引:0,他引:3  
研究了餐厨垃圾两段法厌氧消化工艺与整体一段法的性能差异。两种工艺的累积产气量几乎不存在差异,产气率分别达到135.66L/kgVS和134.56L/kgVS。两种工艺相比,一段法的产气周期短,但是产气的稳定性不佳,在整个消化过程中产气量波动明显,规律性不明显。研究认为:对于餐厨垃圾的厌氧消化.整体一段法的产气周期短,工艺运行简单,应用到工业化生产上,一段法具有明显优势。  相似文献   

10.
水分选有机垃圾三种总固体厌氧消化产甲烷   总被引:1,自引:0,他引:1       下载免费PDF全文
以水分选城市生活有机垃圾(WS-OFMSW)为原料,采用35L厌氧反应器进行中温(30±2℃)批式厌氧消化,研究3种TSr分别为16.0%、13.5%和11.0%的样品对厌氧消化稳定性及性能的影响。结果表明,3种TSr均能实现稳定的产甲烷过程,pH自我恢复调节能力较强,在整个过程中没有产生挥发性脂肪酸抑制。较低的TSr有助于快速启动并缩短发酵周期,3种TSr厌氧消化分别于32、25和12d达到产气高峰。累积产甲烷量分别为273.1、283.0和313.7L·kgVS~(-1),平均甲烷浓度为64.6%、66.3%和65.7%。3种TSr厌氧消化的VS去除率分别为26.08%、35.76%和41.78%。通过该实验,获得相关的WS-OFMSW厌氧消化原始数据,为城市生活垃圾水分选技术的完善以及有机垃圾厌氧消化性能的提高指出了参考方向。  相似文献   

11.
Performance assessment of some ice TES systems   总被引:1,自引:0,他引:1  
In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.  相似文献   

12.
Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NOx) emissions, while producing lower emissions of carbon dioxide (CO2), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NOx emissions. High NOx emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NOx and CO2 emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.  相似文献   

13.
Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H2 yield. The results demonstrated that the optimal culture conditions for the highest H2 production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m?2 s?1. Under these conditions, the maximal H2 yield was 255 μmol mg?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H2 yield included decreased O2 content, enhanced algal growth, and increased H2ase activity and starch content of the combined system.  相似文献   

14.
The thermal decomposition of limestone has been selected as a model reaction for developing and testing an atmospheric open solar reactor. The reactor consists of a cyclone gas/particle separator which has been modified to let the concentrated solar energy enter through a windowless aperture. The reacting particles are directly exposed to the solar irradiation. Experimentation with a 60 kW reactor prototype was conducted at PSI's 90m2 parabolic solar concentrator, in a continuous mode of operation. A counter-current flow heat exchanger was employed to preheat the reactants. Eighty five percent degree of calcination was obtained for cement raw material and 15% of the solar input was converted into chemical energy (enthalpy).The technical feasibility of the solar thermal decomposition of limestone was experimentally demonstrated. The use of solar energy as a source for high-temperature process heat offers the potential of reducing significantly the CO2 emissions from lime producing plants. Such a solar thermochemical process can find application in sunny rural areas for avoiding deforestation.  相似文献   

15.
This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.  相似文献   

16.
液压系统常见的故障诊断及处理   总被引:2,自引:0,他引:2  
任何工程机械式液压设备使用时出现故障是不可避免的。但是怎样确定故障的原因及找到好的解决方法,这是使用者最关心的问题。讲述了液压系统常见的故障及其排除方法。  相似文献   

17.
Increasing awareness of environmental problems caused by the current use of fossil fuel-based energy, has led to the search for alternatives. Hydrogen is a good alternative and the cyanobacterium Anabaena sp. PCC 7120 is naturally able to produce molecular hydrogen, photosynthetically from water and light. However, this H2 is rapidly consumed by the uptake hydrogenase.This study evaluated the hydrogen production of Anabaena sp. PCC 7120 wild-type and mutants: hupL (deficient in the uptake hydrogenase), hoxH (deficient in the bidirectional hydrogenase) and hupL/hoxH (deficient in both hydrogenases) on several experimental conditions, such as gas atmosphere (argon and propane with or without N2 and/or CO2 addition), light intensity (54 and 152 ??Em−2s−1), light regime (continuous and light/dark cycles 16 h/8 h) and nickel concentrations in the culture medium.In every assay, the hupL and hupL/hoxH mutants stood out over wild-type cells and the hoxH mutant. Nevertheless, the hupL mutant showed the best hydrogen production except in an argon atmosphere under 16 h light/8 h dark cycles at 54 ??Em−2s−1 in the light period, with 1 ??M of NiCl2 supplementation in the culture medium, and under a propane atmosphere.In all strains, higher light intensity leads to higher hydrogen production and if there is a daily 1% of CO2 addition in the gas atmosphere, hydrogen production could increase 5.8 times, related to the great increase in heterocysts differentiation (5 times more, approximately), whereas nickel supplementation in the culture medium was not shown to increase hydrogen production. The daily incorporation of 1% of CO2 plus 1% of N2 did not affect positively hydrogen production rate.  相似文献   

18.
Trigeneration is defined as the production of three useful forms of energy—heat, cold and power—from a primary source of energy such as natural gas or oil. For instance, trigeneration systems typically produce electrical power via a reciprocating engine or gas turbine and recover a large percentage of the heat energy retained in the lubricating oil, exhaust gas and coolant water systems to maximize the utilization of the primary fuel. The heat produced can be totally or partially used to fuel absorption refrigerators. Therefore, trigeneration systems enjoy an inherently high efficiency and have the potential to significantly reduce the energy-related operation costs of facilities. In this paper, we describe a model of characterization of trigeneration systems trough the condition of primary energy saving and the quality index, compared to the separate production of heat, cold and power. The study highlights the importance of the choice of the separate production reference system on the level of primary energy saving and emissions reduction.  相似文献   

19.
La–Fe–B hydrogen-storage alloys were prepared using a vacuum induction-quenching furnace with a rotating copper wheel. The thermodynamic and kinetic properties of the La–Fe–B hydrogen-storage alloys were investigated in this work. The P–C–I curves of the La–Fe–B alloys were measured over a H2 pressure range of 10−3 MPa to 2.0 MPa at temperatures of 313, 328, 343 and 353 K. The P–C–I curves revealed that the maximum hydrogen-storage capacity of the alloys exceeded 1.23 wt% at a pressure of approximately 1.0 MPa and temperature of 313 K. The standard enthalpy of formation ΔH and standard entropy of formation ΔS for the alloys' hydrides, obtained according to the van't Hoff equation, were consistent with their application as anode materials in alkaline media. The alloys also exhibited good absorption/desorption kinetics at room temperature.  相似文献   

20.
The mineralogical composition of intraseam layers from Lofoi lignite deposits (northwest Greece) is the subject of the present study. The samples were examined by means of X-ray diffraction (XRD), thermo-gravimetric (TG/DTG) and differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectrometry. The clay minerals prevail in most samples, with illite-muscovite being the dominant phase, and kaolinite and chlorite being the other major clay components. No smectite was found. Quartz and feldspars, dominate in two cases. The studied materials are characterized as clays to clayey sands, showing significant similarities with the intraseam layers of the adjacent Achlada lignite deposits.  相似文献   

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