Das Projekt "Coal gasification - waste heat utilization" wird vom Umweltbundesamt gefördert und von Krupp Koppers durchgeführt. Objective: Development and test operation of a new waste utilization system (radiation boiler) and of further new components for pressurized entrained flow gasification (PRENFLO). The new components besides the radiation boiler were a candle filter (dry dedusting of PRENFLO raw gas), a fly ash recycle system, a catalytic COS hydrolysis and a raw gas desulfurization system (MDEA process). General Information: The partial oxidation of solid fuels according to the entrained-flow principle (PRENFLO process) is an exothermic process, approx. 20 per cent of the gross calorific value of the fuel being converted into sensible heat. Utilization of this large quantity of heat released is indispensible for the energetically optimum of the PRENFLO process in industrial-scale applications. The raw gas leaves the gasifier at a temperature of approx. 1400 deg. C, highly laden - about 160 g/m3 (24 bar) with small molten or doughy ash particles. The heat utilization concept realized to date at Krupp Koppers comprises the cooling of raw gas at the outlet of the gasifier with quench gas to temperatures of less than 1000 deg. C resulting in higher heat losses at temperatures below 250 deg. C. The hot gas quenching can be avoided by using the new waste heat utilization system for dust-laden PRENFLO raw gas with high optical density. It is based on a radiation boiler with built-in heat exchange elements, the arrangement of which takes account of the temperature and flow profile of the hot raw gas leaving the reactor. Results from the operation of a 48 t/d PRENFLO plant with regard to slag separation in the gasifier, effectiveness of mechanical dedusting devices, decoupling of radiation boiler from gasifier to take account of the vibrational properties (mechanical cleaning device for heat exchangers), and theoretical investigations on heat exchange for optically dense fluids indicated the possibilities of preventing energy losses by quench gas cooling of raw gas. Optimization of the system with regard to the spacing of the heat exchange elements, the cleaning and the geometry of the system result in lower overall height and anticipate efficiency improvements if the system is applied in a CC-power plant. The dry dedusting of PRENFLO gas allows fly ash recycling to the gasifier, thereby a total slagging of the coal ash and a total carbon conversion can be achieved. A high effective filtering system reduces heat losses with the raw gas, when hot dedusted gas from the filter is recycled as quench gas. A candle filter and a pneumatic fly ash recycle system was planned, built and tested. For the desulfurization of the PRENFLO gas a catalytic COS hydrolysis (conversion of COS to H2S) and a H2S absorber (MDEA process) were installed in the test plant to proof the reliability of these process stages for PRENFLO gas in a wide range of operating conditions and to take account of the gas and solid traces in the gas to be treated. Testing and optimization of the waste heat...
Das Projekt "Utilization of industrial waste and especially petrochemical residues for power generation with low emissions" wird vom Umweltbundesamt gefördert und von Mineralöl-Raffinerie Dollbergen GmbH durchgeführt. Objective: The purpose of the project is to demonstrate a low-emission combustion unit to burn petrochemical wastes, such as distillation bottoms, light boiling petrol residues, heavy oil fractions, acid tars and PCB-containing waste oil. General Information: The concept is based on a proprietary combustion system combined with a two step, dry flue gas treatment system and an existing boiler. The combustor is composed of a high swirl, substoichiometric combustion chamber, followed by an after combustion chamber, to which secondary air is added ensuring a residence time of 0.3 s. and 1200 deg. C. The particular geometry, together with the flow pattern lead to a complete combustion, with low formation levels of NOx, CO and dioxins. The flue gas is desulphurized by injection of crushed limestone, together with recirculated flue gas to reduce the temperature to a level of 1100 - 1150 deg. C. After heat recovery, lime powder and steam are added for HCI removal. Finally, the flue gas is cleaned using bag filters. Achievements: The plant started full operation on September 1988. The burner capacity was varied between 120-450 kg oil/h while for all tests the combustion air supplied was 125. The operating temperature of the furnace was in the range of 1150-1250 deg. C and this was controlled by recycling of flue gases. The flue gases purification system was modified considerably and it was concluded that hot gas desulphurization was not needed while for HCl removal a combination of limestone and steam injection in the dechlorination reactor proved efficient and resolved all operational problems of solids, (CaCl2) accumulation. No problem was encountered with the bag filter. Emission measurements for dust, CO, SO2, HCl and total carbon are performed continuously while emission measurements for inorganic halogen compounds (HF, phosgen), BTEX-aromatics, chlorinated hydrocarbons, PCB and PCDD are performed periodically. The table below summarizes some of the results obtained. It was also formal that no significant amounts of phosgene BTEX-aromatics, chlorinated hydrocarbons and polychlorinated Biphenyles are emitted by the installation and these were always well below the limits set by TA Luft. However the emissions of dioxines and furnaces were always close to the limits specified by TA Luft and although the limits were rarely exceeded the contractor plans to continue development work in this area. Nevertheless, it can be concluded that from the emissions point of view, the furnace chamber system with swirl has proved to burn waste oils successfully. During the demonstration period which ended on 31.12.1989, the demonstration plant fulfilled almost 80 per cent of the planned capacity of waste oils combustion and about 50 per cent of the targeted energy savings. The reduced capacity was due to technical optimation at the flue gas purification system while the reduced energy savings were due to the utilization of an existing old type radiation boiler instead..