Anaerobic digestion of semi-solid organic waste: biogas production and its purification

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  • out to increase the use of methane as well by the mines and external users. The actual and designed activities of JSW SA in the range of utilization of methane from the coal beds are presented.

    Transport, storage

    02/01400 Hydrogen storage in carbon nanotubes Cheng, H-M. et al. Carbon, 2001, 39, (10), 1447-1454. Hydrogen is the cleanest, sustainable and renewable energy carrier, and a hydrogen energy system is expected to progressively replace the existing fossil fuels in the future, the latter are being depleted very fast and causes severe environmental problems. In particular, one potential use of hydrogen lies in powering zero-emission vehicles via a proton exchange membrane fuel cell to reduce atmosphere pollution. To achieve this goal feasible onboard hydrogen storage systems have to be developed. The recent discovery of the high and reversible hydrogen storage capacity of carbon nanotubes makes such a system very promising. In this overview, theoretical predictions and experimental results on the hydrogen uptake of carbon nanotubes and nanofibres are summarized, and it is noted that, in order to accelerate the development of carbon nanotubes and nanofibres as a practical hydrogen storage medium in fuel cell-driven vehicles, many efforts have to be made to reproduce and verify the results both theoretically and experimentally, and to investigate their volumetric capacity, cycling characteristics and release behaviour.

    Economics, business, marketing, policy

    02/01401 Energy relations of gas estimated from flare radiation in Nigeria Ede, P.N. and Johnson, G.A. International Journal of Energy Research, 2001, 25, (1), 85-91. Nigeria is one of the major petroleum producers in the world. It flares an average of 22 billion cubic metres of gas annually as a by-product of petroleum exploitation. This practice is inimical both to the environ- ment and a waste to the economy. There are over 300 flares sites in the country and for this study 10 were monitored. Measurements were taken over a period of 24 h for each of the flares to determine the energy flux. The heat radiation was measured with a non-contact thermometer mounted on tripod 50 m from the flare. When the product of the measurement was converted into other energy equivalents for the flared gas it is observed that the flared gas is greater than the total electric power generated in the country for any given period even at 30 per cent fuel conversion. This paper proposes that other options for gas utilization be explored to check the trend.

    Derived gaseous fuels

    02/01402 A process for recovering hydrocarbons from a carbon containing material Kean, P.E. PCT Int. Appi. WO 01 40,406 (CI. CI0G1/00), 7 Jun 2001, AU Appl. 1999/4,357, 30 Nov 1999. 19. This paper reviews a process for recovering hydrocarbons from coal or oil shale. The process involves the steps of: forming a pulp of finely divided coal or oil shale in a first reaction bed, adding concentrated sulfuric acid to this first reaction bed, while controlling the temperature of this first reaction bed to produce a hydrocarbon mixture, and then deacidifying the hydrocarbon mixture.

    02/01403 Anaerobic digestion of semi-solid organic waste: biogas production and its purification Lastella, G. et al. Energy Conversion and Management, 2002, 43, (l), 63-75. The main objective of the present experimental investigation was to evaluate the effects of using different bacteria inocuiums at identical technical settings on the anaerobic digestion process for the treatment of semi-solid organic waste available from the orthofruit market. As a possible means to improve the biogas production, as well as reduce their pollution potential, the idea of using recycled digested sludge from the reactor, along with the orthofruit waste, while operating the reactor at maximum retention period has been applied. Purification of

    03 Gaseous fuels (derived gaseous fuels)

    the biogas produced was done by means of CO 2 adsorption, resulting in a higher Ch4/CO2 ratio and, thus, improving its use as fuel for power generation.

    02/01404 Civil synthetic fuel Wang, F. Faming Zhuanli Shenqing Gongkai Shuomingshu CN 1,301,805 (CL C10L1/04), 4 Jul 2001, Appl. 99,127,170, 29 Dec 1999. 4. (In Chinese) The synthetic fuel is composed of light hydrocarbon 80-95% and an emulsion-breaking agent 5-8%. The light hydrocarbon has an apparent density of 0.631 g/cm s at 20 . The fuel is low in toxicity and pollution, but high in calorific value.

    02/01405 Coaleaam methane recovery by vacuum swing adsorption Gomes, V.G. and Hassan, M.M. Sep. Purif. Technol., 2001, 24, (1-2), 189-196. Coalseam methane gas recovery using pressure and vacuum swing adsorption (PSA/VSA) processes were investigated both theoretical and experimental COz is more strongly adsorbed and also diffuses faster compared to methane and nitrogen in a carbon-based adsorbent. Hence such adsorbents are suitable for methane recovery. Carbon molecular sieve adsorbents were employed for testing the technical feasibility of the adsorption process. Numerical simulations indicate that the purity of methane gas recovered can be greater than 90% by switching from PSA to VSA operation. The effect of process cycle time, purge pressure and feed flow rates were investigated. Both model predictions and laboratory experiments show promising separation performance. This study shows that a relatively untapped source of methane from coalseam gas can be economically recovered for industrial applications.

    02/01406 Development of a high-temperature air-blown gasification system Plan, C.C.P. and Yoshikawa, K. Bioresource Technology, 2001, 79, (3), 231-241. Current status of high-temperature air-blown gasification technology development is reviewed. This advanced gasification system utilizes preheated air to convert coal and waste-derived fuels into synthetic fuel gas and value-added byproducts. A series of demonstrated, indepen- dent technologies are combined to form the fore of this gasification system. A high-temperature, rapid devolatilization process is used to enhance the volatile yields from the fuel and to improve the gasification efficiency. A high-temperature pebble bed filter is used to remove the slag and particulates from the synthetic fuel gas. Finally, a novel regenerative heater is used to supply the high-temperature air for the gasifier. Component development tests have shown that higher gasification efficiencies can be obtained at more fuel-rich operating conditions when high-temperature air is used as the gasification agent. Test results also demonstrated the flex-fuel capabilities of the gasifier design. Potential uses of this technology range from large-scale integrated gasification power plants to small-scale waste-to-energy applications.

    02/01407 Discussion of the measurement end control program for plasma coal cracking decomposition process Hou, L. et al. Meitan Zbuanhua, 2001, 24, (3), 65-69. (In Chinese) To the process of rich H2 high temperature plasma coal cracking decomposition to produce CzHz which have to two kinds aspect of industry process and typical research speciality, developed control system in which use advanced and cheap hardware configuration based industry control computer. Adapting advanced language application software was developed for the system in windows environment. Also proposed are some strategies and the main problems in the process of implementing the system are discussed.

    02/01408 Fischer-Tropsch and partial-oxidation processes for the production of hydrocarbons, electric power and carbon dioxide from synthesis gas and carbon-containing materials Bohn, M.S. and Benham, C.S.U.S. US 6,306,917 (CI. 518-700; C07C27/00), 23 Oct 2001, US Appl. 212,374, 16 Dec 1998. 13. This paper examines the apparatus and processes for producing power, liquid hydrocarbons and carbon dioxide from heavy feedstocks. This involves using a partial oxidation reactor to produce a synthesis gas, a Fischer-Tropsch reactor to convert the synthesis gas to hydrocarbon products and tail gases containing hydrogen and carbon dioxide, and a combined cycle plant to produce power from steam generated by recovering heat from the reactors and from combustible tail gases. By varying operating conditions and utilizing hydrogen for recycle to the Fischer-Tropsch reactor and/or hydrocracking wax products to produce lighter hydrocarbons, the process can selectively maximize the production of power, hydrocarbons or carbon dioxide; the Fischer- Tropsch reactor can be a slurry reactor and can employ an iron-based catalyst.

    Fual and Energy Abstracts May 2002 181

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