Dry gas cleaning

Small biomass CHP plants will constitute the most promising route for CO_2 reduction, as they represent the major market perspective in terms of replication. The scope of this proposal is to develop and prove a complete gasification CHP small scale prototype. The innovative idea of the project is to develop a new dry gas cleaning and heat recovery system, which integrates all other plant components in a linked system. The dry cleaning concept, i.e. no waste water, intends to solve and liminate the tar problems associated with operation of biomass gasifiers. Gas cleaning includes a high temperature dust separation at the gasifier outlet followed by a very special regenerating counter-current tar condensing heat exchanger, which is operated alternately in two phases. The ultimate objective is to create a new generation of energy effective and environmentally environmental friendly gasification systems. Objective. The scientific objectives of this proposal concerns the set up and test of a new type og gas cleaning system. Adapted to biomass gasification CHP plants and the tentative definition of standards for engine tolerance towards for engine tolerance towards tar. The immediate objectives are: 1) design and construct a new tar condensing regenerative heat exchanger to provide a clean gas ready for combustion in an engine: 2) integrate and test the complete system including small scale downdraft biofuel fired gasifier of 250 kW_t_h capacity, dust separator, regenerative heat exchanger and generator for at least 500 hours; 3) modelling of the component design and analysis of tar behavior versus engines requirements; 4) economic evaluation of the process and environmental impact from a local and a global point of view. Description. The most essential part of the process is the gas cleaning. The gas cleaning includes a high temperature gas separation at the gasifier outlet, followed by a very special regenerating counter- current tar condensing heat exchanger, which is operated alternately in two phases. Change of phase correspond to a change of the flow direction as well as flow side. The hot gas is cooled by two separate air streams. Regeneration has the effect of decomposing the tar deposits at high temperature and returning the cracked tar products into the gasifier by means of preheated gasification air. The cooling air for feedstock drying is contaminated with cracked tar products. The produced gas is cooled to 10-20 deg C above the dewpoint, so no waste water is generated. The project concerns the development and testing of a new generation of dry cleaning and heat recovery device in connection with an already existing small scale open core down-draft biomass gasifier. The gas is burnt in a high compression/highly efficient gas engine producing power. The carburating and exhaust systems of the engine must be re-designed according to the gas quality and new identified operation strategies to ensure low emissions and high efficiency. The full device will be operated in order to test, optimize and document important relation such as technical viability, environmental impact, economics and define applicability related to fuel supply and integration into various national energy supply systems. The different WP are: WP1: gas cleaning and heat exchanger design and set up, WP2: carburation design and testing, WP3: testing and tar investigation , WP4: review of the results, WP5: economic analysis, environmental impact and modelling. Milestones. The first milestone is reached when the small scale plant is completely set up, with the different components carefully designed. The objective then is to prove that this small plant is able to run satisfactorily to confirm that our system allows to solve the problem of gas quality. The project success criteria is a 500 h operation of the small plant, as well as the adequation between the acceptable tars in the engine and the produced gas quality (remaining tars)