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Category Archives: Power Generation

 An Overview of Coal based Integrated Gasification Combined Cycle (IGCC) Technology

 

September 2005

 

Ola Maurstad

Massachusetts Institute of Technology
Laboratory for Energy and the Environment

 

Introduction

The integrated gasification combined cycle (IGCC) produces electricity from a solid or liquid fuel. First, the fuel is converted to syngas which is a mixture of hydrogen and carbon monoxide. Second, the syngas is converted to electricity in a combined cycle power block consisting of a gas turbine process and a steam turbine process which includes a heat recovery steam generator (HRSG). The combined cycle technology is similar to the technology used in modern natural gas fired power plants.

Coal based IGCC plants are still not fully commercial. A number of demonstration plants with electric output up to 300 MW have been built in Europe and the US, all with financial support from government. The motivation for pursuing this technology is the potential for better environmental performance at a low marginal cost. This is especially true for mercury removal and CO2 capture. In order to compete with conventional pulverized coal plants under current environmental regulation, the main challenges facing the IGCC technology today are capital cost and availability.

 

Download this paper at :

http://lfee.mit.edu/public/LFEE_2005-002_WP5.pdf

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FINAL TECHNICAL REPORT

STRAW GASIFICATION FOR CO-COMBUSTION IN LARGE CHP-PLANTS

ERK5 – CT – 1999 – 0004

 

PREFACE

This is the final report of the STRAWGAS-project “Straw gasification for co-combustion in large CHP-plants”. The report covers process validation of the gasification and gas cleaning tests that were carried out in 2000 and the design study of a 100 MWth gasifier. Process validation and design study covers gasification of 100% straw and a fuel mix of straw and wood.

The project partners Foster Wheeler Energia Oy and ENERGI E2 A/S (former Elkraft Power Company) have executed the major part of the project with VTT Energy (Finland) and TK energi (Denmark) as valuable sub-suppliers. The project has received substantial economical support from the European Commission.

The experimental research consisted of 3 main tasks:

• The capability of the developed feeding system to feed loose straw into the gasifier
• The optimal process conditions and additives for gasifying loose straw
• The capability of the selected gas cleaning system to make the gas suitable for cocombustion
in large CHP-plants

In the design study a full-scale straw gasification plant of 100 MWth and the integration with an existing large CHP plant was investigated. The practical solutions of all unit operations
were developed. The budget for a complete plant was calculated and consequently the overall project economy was assessed. The result of the process validation and design
study can be the technical and economical basis for a decision to built a demonstration plant.

This project was carried out in the period from April 2000 to May 2001.

 

 

Link to this paper at :

http://www.gastechnology.org/webroot/downloads/en/IEA/IEASTRAWGAS.pdf

STATUS OF BIOMASS GASIFICATION FOR POWER PRODUCTION

SPLIETHOFF, Hartmut

IFRF – Combustion Journal – 1999 – 2001

ABSTRACT
The most commonly used gasification technologies are fixed bed and fluidized bed gasifiers. Fixed bed gasifiers are employed in the low-capacity range of some MWth, fluidized bed installations, typically in the range above 5 MWth.

The gas produced in the gasifier can be used in various ways for electricity production or for the production of process heat. The systems differ with respect to efficiency, costs, and demand on the gas quality. Engines are suited for electric capacities between ca. 50 kWe and 10 MWe in connection with atmospheric fixed-bed gasifiers. From a capacity of about 5 MWe gas turbines, often in combination with a fluidised bed gasifier, are an alternative. In order to avoid fouling and deposits in the engine, the gas should be to a large degree tar- and dust-free. The requirements for fuel cells are more stringent, however a clear concept about allowed concentrations in the product gas is not yet available.

The gasifiers available on the market today exceed the indicated values by far when operated without gas cleaning. The removal of both tar and particles is therefore a requisite. The use of the product gases for thermal purposes does not make such high demands on the quality regarding tar and dust content. So for those applications it is not necessary to provide for a special gas cleaning.

Link to this paper at : http://www.journal.ifrf.net/library/november2001/200109spliethoff.pdf

Future prospects for production of methanol and hydrogen from biomass

System analysis of advanced conversion concepts
by ASPEN-plus flowsheet modelling

Carlo N. Hamelinck
André P.C. Faaij

 

 September 2001, Report NWS-E-2001-49

ISBN 90-73958-84-9

 

Abstract
Technical and economic prospects of the future production of methanol and hydrogen from biomass have been evaluated.
A technology review, including promising future components, was made, resulting in a set of promising conversion concepts.
Flowsheeting models were made to analyse the technical performance. Results were used for economic evaluations. Overall energy efficiencies are around 55 % HHV for methanol and around 60 % for hydrogen production. Accounting for the lower energy quality of fuel compared to electricity, once-through concepts perform better than the concepts aimed for fuel only production. Hot gas cleaning can contribute to a better performance. 400 MWth input systems produce biofuels at 8 – 12 US$/GJ, this is above the current gasoline production price of 4 – 6 US$/GJ. This cost price is largely dictated by the capital investments. The outcomes for the various system types are rather comparable, although concepts focussing on optimised fuel production with little or no electricity co-production perform somewhat better. Hydrogen concepts using ceramic membranes perform well due to their higher overall efficiency combined with modest investment. Long term (2020) cost reductions reside in cheaper biomass, technological learning, and application of large scales up to 2000 MWth. This could bring the production costs of biofuels in the 5 – 7 US$/GJ range. Biomass-derived methanol and hydrogen are likely to become competitive fuels tomorrow.

 

Link to this paper at :

http://www.senternovem.nl/mmfiles/26624_tcm24-124168.pdf

Energyplexes for the 21st century: Coal gasification for co-producing hydrogen, electricity and liquid fuels

Kei Yamashita, Leonardo Barretob

Energy 30 (2005) 2453–2473

 

Abstract

This paper illustrates the role that integrated energy systems, also known as ‘energyplexes’, could play in supplying energy demands in the long term. These systems could enable a multi-fuel, multi-product strategy with both economic and environmental benefits. They could increase the adaptability and robustness of energy-services companies in the marketplace, providing them with flexibility in meeting demands in different market segments while achieving lower production costs and, reducing the risks of reliance on a single feedstock. In addition, with the possibility of achieving high conversion efficiencies and low polluting emissions and facilitating carbon capture, they could deliver high-quality energy services in a cost-effective way while meeting stringent
environmental requirements. Their potential is highlighted here using the case of coal-fired, synthesis-gas-based gasification systems that allow co-producing hydrogen, electricity and liquid fuels, i.e. Fischer–Tropsch liquids and methanol, and could be a key building block in a clean-coal technology strategy. Co-production, also known as poly-generation, strategies may contribute to improve the economics of the system and exploit potential synergies between the constituent processes. However, the technical feasibility and economic viability of poly-generation schemes have to be examined carefully on a case-by-case basis.

Download this paper at :

http://www.iiasa.ac.at/Publications/Documents/RP-05-005.pdf