combustion environment using DTF

combustion environment using DTF

04 By-products discussions and conclusions reached by the working group for the small-scale protocol. In principle, the group decided that a method si...

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04 By-products discussions and conclusions reached by the working group for the small-scale protocol. In principle, the group decided that a method similar to that used for sampling PAHs in stack gas would be appropriate. The main elements of the system would be an isokinetic probe for sample extraction, a heated filter for particulate collection, a water condenser and a series of impingers, containing cooled solvent to collect the organic contaminants. The group felt that the method should include both gravimetric and chromatographic determinations of the concentration of organic contaminants. Dichloromethane was selected by the group as the solvent that would be used for all aspects of the method. However, at this stage, there remains some uncertainty over this selection. To resolve this and other uncertainties a programme of work is described that will progress the protocol to a stage where procedures could be started to adopt it as a European and US standard. The report is structured in three sections. Section 1, the Working Group Report, documents the discussions of the working group and wider meeting. Section 2 is a draft protocol. The protocol is necessarily in a preliminary form at present but will be updated successively as a result of further work and consultations. Section 3 contains calculations for typical equipment items and procedures.

04

BY-PRODUCTS TO FUELS

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02lOO391 A study on the slagging behavior of coal ash in gasification/combustion environment using DTF Kim. Y. er al. Preur. Svm~. - Am. chemical Sot.. Div. Fuel chemical. 1999, 44, (3) 721y724. ’ . The purpose is to determine ash slagging behaviour for the optimum ash removal in actual coal gasifier as well as combustor. DTF (drop tube furnace) was utilized for entire experiment to simulate real time and temperature history of coal particle. Pulverized particles of three different coal samples (Alaska, Cypurus and Datong) were injected into DTF with different experimental conditions. The slag samples deposited at the top of sample collector by the particle action of impacting and agglomerating. The formation shape of each deposited slag is related with physical properties of original ash such as ash fusion temperature, viscosity and surface tension. Phase diagram of main components of ash, i.e. SiOz-CaO-AIzOs system are analysed to determine ash fusion behaviour with different composition of the system. Shape of slag formation represents different behaviour with gasification and combustion environment and also is effected by chemical composition of coal ash. 02/00392 Activated carbon from some agricultural wastes under action of one-step steam pyrolysis Alaya, M.N. et al. J. Porous Mater, 2000, 7,, (4), 509-517. A one-step steam pyrolysis scheme was applied, in the range 600-700”, for the production of activated carbons from five lignocellulosic materials. The products were characterized by NJ77 K adsorption for evaluating their surface area and pore volume. Simple carbonization at 700” resulted in poor adsorbing carbons whereas porosity was remarkably enhanced under action of steam. Carbon precursors derived from date palm wastes (branches, leaves and date pits) proved feasible raw materials that produced good adsorbing carbons. Rice husks and barbecue charcoal developed porosity to a lower extent, due to the inherent ash content. All obtained carbons were essentially microporous due to the limited gasification. Steam is suggested to play a double role: it promotes both the release of volatiles with partial devolatilization, and enhances carbon formation. 02iOO393 Active flue gas condensation at a biomass district heating plant Podesser, E., Bayer, H. VTT Tied., 2000, 2024, Partl/l-Partl/58. Heat recovery from flue gas in biomass furnaces of district heating plants increases efficiency because of high water content of wood chip and bark fuels. Due to the water content of the biofuel, the lower heating value is normally = 50% of that of dry wood. If the flue gas is cooled to = 30”, large quantities of heat (30-50% of the furnace capacity) can be recovered by condensation. If the temperature of the flue gas is 70”. the heat recovery is 10%. If the heat pump is used, the low temperature condensation heat recovered from the flue gas can be raised from 30” to the temperature of the district heat return level. For this purpose, a resorption heat pump with a mech. compressor must be used due to the high coefficient of performance. The mechanical compression unit is powered either by a grid-connected electric motor or by a flue gas powered bio-Stirling engine. A mechanical run resorption heat pump is the best option and the advantages of the

related to fuels

resorption heat pump are discussed. The dust content (ash), CO, NOz and organic hydrocarbons are reduced. The refrigerant used (ammonia) is environmentally friendly. The amortization time is 4-6 years.

02/00394 Adsorptive waste gas cleaning in cocombustion of sewage sludge in a brown coal-fired industrial power plant Wirling, J. et al. VGB Tech. Ver. Grosskraftn’erksbeir., / Tagungsber.] VGB-TB. 1999, 435, PaoerR6ii. PaoerR6/1-PaperR6/12. (In German) Hg is efficiently removed from the flue gas by in-flow adsorption on lignite coke which is subsequently separated by an electrostatic precipitator (together with By ash). Crude lignite and dewatered sewage sludge are burnt concomitantly in the circulating atmospheric fluidized-bed firing of a 275-MW (thermal) steam generator. The content of SOz (100-150 mg/m3) and Hz0 (30% per volume) in the flue gas is sufficient for an effective doping of the lignite coke with H2S04 as a prerequisite of chemical adsorption of Hg. A Hg balance of the power plant is given. The process does not enhance the elution potential of heavy metals from the fly ash.

02lOO395 Anticorrosion technology of exhaust heating for wet lime dust-removal and desulfurization in coal-fired power plant Guan, J., Zhu, H. Huanjing Baohu (Beijing), 1999, 12, 12-13. (In Chinese) The main features for flue gas wet lime dust-removal and desulphurization in coal-fired power plant and the applied anticorrosion technologies for flues were introduced. The anticorrosion of flues by steam-heating of low-temperature wet flue gas after desulphurization treatment to above the dew point was presented.

02/00396 Application of DAEM to simulation distillation of coal tar C2i, Z., Liu, X. Medan Zhuanhua, 2000, 23, (2), 3437. (In Chinese) The new elucidation of distributed activation energy (DAEM) was given in which not only an analytical expression of activation energy was obtained for the first time, but also the theoretical proof of Miura’s integration method in DAEM model was realized. The application of this new elucidation to simulation distillation of coal tar showed very identical activation energy values with those obtained by second order reaction kinetics. Together with the same analytic expression of activation energy obtained from the theoretical analysis of second order reaction kinetics, the applicability of DAEM model to second order reaction systems is proved theoretically and experiemntally.

02lOO397 Ash behavior in biomass fluidized-bed gasification Moilanen, A. et al. Impact Miner. Impurifies Solid Fuel Cornbust.. [Proc.

Eng. Found.

Conf. Miner. Maler Fuels],

1997, 555-567.

Characteristic data on ash behaviour can be obtained by laboratory tests and can be used for planning, for example, run conditions for tests with pilot or PDU equipment. Ash sintering can be much stronger in pressurized conditions than under atmosperic pressure. This phenomenon seems to be related to the silicate content in ashes: when the Si content was low the ash sintering was stronger in presurized conditions than in atmospheric conditions. The water-soluble constituents of straw (K, Ca) affect the relation of ash sintering and reactivity. Both bed agglomeration and deposit formation in the freeboard occurred in the tests carried out using straw with problematic ash.

02/00398 Ash deposition characteristics in pulverized coal reaction under high temperature conditions Naruse, I. er al. J. Chem. Erg. Jpn., 2000, 33, (3), 359-364. Ash deposition characteristics under high-temperature pulverized coal reaction conditions were studied by using a horizontal pulverized coal reactor with pre-combustor to produce high-temperature vitiated air. The ash deposition experiments were performed by inserting a watercooled tube into the reactor. Burning two types of coal with different melting temperature and ash content, and the ash deposition phenomena were visually and quantitatively elucidated. As a result, the quantity of ash deposition on the tube surface increases with an increase of the surface temperature. This is because the burning particles in the upper stream of the tube are radiatively cooled down under low temperature condition of the tube surface. Both the structure and quantity of ash deposition depend on coal types such as melting temperature and ash content. The deposition rate at the beginning of deposition, obtained by the peripheral width of deposition layer on the tube surface, is correlated as an Arrhenius-type equation since viscosity of the molten ash can be correlated as an Arrhenius-type equation. The ash deposition phenomena may relate to the viscosity of molten ash. Fuel and Energy Abstracts

January 2002

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