Demonstration plant for biomass gasification and power generation ~ Mechanical Engineerz

Demonstration plant for biomass gasification and power generation

Sanya Timber Factory is a large-scale timber processing enterprise that locates in Sanya, Hainan Island of China. Now in this factory there are two product lines imported from

Sweden

for 30,000m³ shaving plank and 40,000m³ mid-density fibre, and other workshops. About 100 tons wood waste is produced every day, which includes 35 tons wood powder, 10 tons leftover material, 10 tons sieving waste and 45 tons all kinds of bark. Due to the complicated sorts of timber waste, some of the wastes are used and others are disposed which causes some severe problems of storage and pollution. On the other hand, timber processing is a high electricity consumption activity; this factory needs power about 5000 kW and the cost is up to ten million RMB per year. So to convert the wood waste into electricity for the factory’s self-consumption through biomass gasification-power generation technology has favourable conditions of environmental protection and energy conservation.

Objectives

Turn waste into wealth and improve the economic benefit.

Description of the activity

The main equipment of a biomass gasification-power generation system includes a gasifier, a purifying tube, water scrubbers, a blower, generators, a waste-water treatment pool, a biomass conveyer and feeder, etc. The following is the flow diagram.


	Barriers that were identified/overcome

After overcoming the shortages in technology, according to the status of accomplished MW scale biomass gasification-power generation plants and the electricity consumption characteristics of the timber mill, this plant can reach the operation objectives as follows:

1. The total capacity is 1200 kW; the average load for long-term operation should reach almost 85% of the designed capacity.

2. The system failure rate is less than 10%; the operation shutdown rate is less than 10%.

3. The total utilisation rate is up to 70%.

Critical success instruments and their impact

Design, planning and management

1. Main equipment and system configurations

2. Power production and electricity distribution

In order to get the utmost out of the generation facility and according to practical situation of the power load distribution, the produced electricity will be distributed in the following manner:

1. Dividing the electricity output of the biomass power plant into two parts, each part is provided by three parallel gas engines and the total output of each part is 600 kW.

2. The power load of the timber factory which can be substituted is separated from the total load and equipped with bi-directional switch; it can make use of not only the electricity produced by the biomass power plant but also the outside power grid.

3. Dividing the electricity load of the timber factory that can be substituted into three parts, the capacity of each part is 500-600 kW, so the biomass power plant can keep higher operation ratio.

3. Technical specifications

According to the status of accomplished MW scale biomass gasification-power generation plants and the electricity consumption characteristics of the timber mill, this plant can reach the operation objectives as follows:

1. The total capacity is 1200 kW; the average load for long-term operation should reach 85% of the designed capacity.

2. The system failure rate is less than 10%; the operation shutdown rate is less than 10%.

3. The total utilization rate is about 70%.

4. The consumption of raw material is 1.2 kg/kWh(dry); it is totally 30 tons each day.

4. Land and employee requirement

According to practical considerations, the total area of this plant is about 1500 m².

Gasifier workshop: 300 m²

Gas engines workshop: 300 m²

Biomass storage field: 600 m²

Waste-water pool: 300 m²

The total number of staff, including 3 administrators, is about 25 persons. They are divided into three groups to work in turn. Among each group, 2 persons are in charge of the gasifier, 4 persons are in charge of electricity production, one person distributes electricity.

Partnership

Guangzhou Institute of Energy Conversion of CAS cooperated with Sanya Timber Factory to invest together, and established a joint-stock company, which is a legally independent body; and the rights and interests of both sides are decided by its contribution to the biomass power plant. It has been agreed upon that the Institute shares 62.8% stock and the Factory 37.2% stock (according to the contract regulation.).

Potential for further application

Base on the current price of biomass wastes (10 USD/t) in

China

, the electricity production cost in this project is around 0.02 USD/kWh . The economic return from this demonstration project will reach about 0.3 million USD/year, and all capital investment will be paid back in about 3 years.

When the demonstration plant operates under designed conditions, about 10 thousands tons of biomass wastes will be utilized every year. Consequentially, with the advantage of no CO₂release, more than 10 thousands tons of CO₂ can be avoided. And comparing with coal combustion, a great deal of flue gas, such as NOx and SO₂ can be alleviated. In the long term, the environmental benefit from the application of biomass gasification and generation technology will be much more obvious.

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Wednesday, February 2, 2011