THERMIE BM./00017/96 Demonstration of a bed mixing dryer for wet biomass saving fuel in energy production

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Drying/Pretreatment : JOULE/THERMIE Programme : Solid Biofuels

	Type of Project	Shared Cost
	Contract No	BM./00017/96
	Total Cost	2,547,800 ECU
	EC Contribution	792,645 ECU
	Start Date
	Duration

Demonstration of a bed mixing dryer for wet biomass saving fuel in energy production

Objectives

The bed mixing dryer project aims :

• to reduce the cost and environmental impact of energy production
• to improve the reliability of the dryer technology
• to assist its application integration and penetration in the energy market
• to promote the use of the economically competitive technology using wet biomass as fuel for power/heat generation

The objective is to realise this demo project at a commercial scale based on innovative technologies. The dryer is designed to produce 6 MW_th district heat and the annual monetary value of energy saving is estimated to 3.8 MSEK/a. The estimated payback in years is 8.5 a.

Project Description

The project will advance and implement innovative new technologies, which have no commercial applications yet. The research and development stage has been completed. A pilot plant has been built inside the IVO Group in Kuusamo. The technology of the Bed mixing dryer is suitable for power plants utilising fluidised bed combustion for combined heat and power production (CHP) or solely power generation. The technology is patented by IVO in Finland and a patent application is pending in other countries, too.

The construction of the dryer is very simple, the idea is to utilise the heat of the hot bed material of the fluidised bed for drying the fuel and to recover the latent heat in the formed vapour. The possibility to utilise the energy used for drying makes the bed-mixing dryer profitable. The heat is transferred in direct contact between the hot bed material, the steam and the wet fuel, which means that no exchangers are required for the drying phase. The moisture of the fuel does not go through the boiler, which reduces the amount of flue gases. This reduces the size and investment costs of the boiler in new investments while the capacity of existing boilers can be increased.

Summary of the advantages and innovative aspects of the bed mixing dryer:

• high overall thermal efficiency due to the recovery of latent heat back to the process
• new plant: smaller boiler size when the amount of moisture in the boiler is reduced
• old plant: increased capacity
• simple construction when no heat exchangers are required for the drying phase
• significant savings in CO₂, NO_x, SO₂ emissions, because burning of other fuels is avoided by utilising wet biomass as fuel
• no risk of fire due to the inert atmosphere
• easy to control by changing the bed material flow

State of Advancement

Ongoing: The project is now in its design stage. The technical description of the process has been specified and approved by the partners and the authorities in Obrero and the functionality of the different components has been evaluated. In order to check the operation of the technical solutions, cold model tests have been run in the laboratory of IVO Technology Centre.

The condensate produced by the dryer has turned out to not be accepted to the city sewerage system in Obrero. Therefore huge investigations has been carried out to find out possible methods to clean the condensate. A concept has been developed and the contractors will have to agree upon details.

Contacts

Coordinator

• Ivo Int Ltd FINLAND