ENK5-2002-00675 Degradation of tarwater from biomass gasification

Contacts
Summary Information



To find similar Items, click on a keyword below:
Chemical Conversion : EESD (Energy, Environment and Sustainable Development) : Thermochemical Conversion

Proposal No:	ENK5-2002-00675
Date Prepared:	February 2004
Source:	European Bio-Energy Projects (EUR 20808)

Introduction

Biomass gasification product gas is often wet scrubbed to remove tar and particles before use in gas engines. Even for dry gas cleaning, it is necessary to perform cooling where contaminated water is produced. These effluents will result in environmental problems if they are not cleaned before being discharged into the urban network.

The DETAR project addresses the development and optimisation of a supercritical process for the cleaning of such effluents. In the project waste water, from an updraft gasification process, is used in cleaning experiments which are carried out at laboratory scale (2 kg/h unit) and pilot scale (60 kg/h Process Development Unit). In addition, the kinetic and transport models in the process are formulated, the cleaned water is characterised and a full-scale application is described economically/energetically/ environmentally. Finally the application of the technology, in connection with other gasification configurations and other gas-cleaning technologies, are evaluated based on literature information.

Activities

The DETAR project is carried out at three different scales:

• The Laboratory Scale Unit (LSU), a 2 kg/h system already in existence and financed by the Danish participants and in part by the Danish Energy Agency, will be used to establish basic parameters for various conditions (waste water retention time, temperature/pressure level and influence from added carbon catalyst).
• The Process Development Unit (PDU), to be designed and built for a capacity of 60 kg/h (financed in part by the Danish Energy Agency), will be used for the correlation with mathematical model/tools to be developed for optimisation and as a basis for up-scaling to full-scale application.
• A full-scale industrial implementation layout analysis using 1000 kg/h of waste water will be used to study the capital/operational cost and energetic/environmental impact of technology.

Using experimental data from the LSU/PDU, chemical analysis, kinetic/mathematical modelling and process simulation, it is intended to verify the industrial application of the SCWO/G process for waste water from updraft biomass gasification and (through literature studies) to extend the results to other gasification concepts and cleaning technologies.

Based on preliminary results obtained from the LSU, it has been verified that the SCWG of gasifier waste water will produce additional, high quality product gas for use in gas engines. Therefore it is the intention to verify that overall power efficiency can be improved and at the same time the environmental problems from effluents, inherent in most state-of-the-ar t approaches to biomass gasifier based Combined Heat and Power (CHP) may be solved.

Progress

DETAR was initiated 1 January 2003 and so far several experiments using the LSU have been carried out. The design of the PDU is well under way using information from the LSU experiments. In connection with the PDU design, preliminary dimensioning software has been devised parallel to the development of the full mathematical model.

Further, raw tar-water and cleaned water has been initially characterised and gas analysed, based on the LSU experiments. During the remaining part of 2003, the PDU will be built, the software improved and experiments using catalysts (e.g. carbon) will be carried out.

Impact and exploitation

A detailed chemical characterisation of tar-water from updraft biomass gasification (and compared to data available on other processes) will be carried out. The SCWO/G process will be optimised for biomass gasifier waste water from product gas clean-up.

Kinetic mechanisms and mathematical tools will be made available for process scale-up. Process full-scale characteristics will be evaluated and described. The use of the developed technology will considerably improve the market penetration of biomass gasification based CHP and therefore reduce energy production related CO₂ emission.

When biomass utilisation is increased in this way it will be possible to create local employment for the handling of the biomass fuel and also for the actual operation of the plant.