How A Biomass Power Station Works

 

Biomass

Biomass grows up to 10 million seedlings a year in nursery. They will generate 30 MW of electric power by growing the seedlings into trees, processing the timber logs into woodchips, and burning them during a biomass power station.

Biomass Power Plant

Trees enter the woodchipper from the left, woodchips are lit to heat the boiler, from which the high-pressure steam then drives the turbine,spins a generator to make electricity.

Process

The seedlings are planted over 16,000 hectares of plantations to grow for 5 to 8 years to mature into trees. While the trees grow they absorb from the atmosphere Carbon Dioxide through the process of photosynthesis. Mature trees are harvested, debarked, and loaded as tree logs onto trucks. Tree logs are then transported to a centrally located power station site.

Tree logs are processed on site into wood chips to fuel our biomass power station . Wood chips are channelled into the combustion chamber through a conveyor system and burned to heat water in the boiler. The burning wood chips release stored CO2 back to the atmosphere, remaining ash is employed as plantation fertiliser and for construction .

Under high temperatures of the heat, the water in the boiler becomes high pressure steam that is used to spin the turbine, and the turbine drives the generator.

Biomass Fuel

The generator creates electricity which flows into the grid to power residential, commercial, government, and little industry customers.

Our biomass power generation carbon cycle is neutral. The amount of carbon absorbed by growing trees equals the quantity released through burning the biomass wood chips. But by establishing plantations on underutilised grasslands, Biomass has an overall positive effect, as each tree may be a small additional carbon sink.

Technology

The combustion of solid fuels has been the mainstay of steam and power production for over 150 years. it is only relatively recently. That oil and gas were available in sufficient quantities to justify use in power stations. Coal overtook wood in its use due to the much higher energy density but wood fired boilers are still in widespread use worldwide (including countries like Indonesia, Philippines and Fiji), and particularly where sustainable wood sources are available. Burning of biomass is therefore not a replacement technology, but in recent years the burning technology has been designed to make the best use of a sustainable resource.

Biomass will combust woodchip fuel in its biomass power station using conventional steam cycle technology and use well-tested and trialled travelling-grate biomass boiler technology. The plant is meant to combust woodchips by conveying and blowing the woodchips onto a travelling grate within the boiler.  

The spent steam from the turbine is condensed in a condenser cooled with water from a cooling tower using grey water, extracted under license, from local boreholes and treated process-effluent. The condensate is then recycled to the boiler.

Hot flue gas is skilled a mechanical cyclone then cleaned further in an electrostatic precipitator to get rid of ash and particulates within the gas stream, before venting to the atmosphere via a tall (40m) stack. Ash and any effluent sludge will be collected and used as a plantation fertiliser.

Design

There has been a development of combustion technology and boiler design to realize the combined goals of upper efficiency and skill to burn fuels set during a regulatory framework which demands ever reducing emission levels.   Fixed-bed or grate combustion is that the traditional technology for burning solid fuels. There are different grate technologies which are primarily distinguished by the sort of grate movement (horizontal, vibrating, travelling, rotating grate) and by the sort of fuel feed mechanism (spreader stoker or underfeed).Biomass will use a travelling grate with a spreader feed system.

The fuel burns out over a particular time releasing its energy into the flue gas. With continuous fuel feeding, combustion will occur in various sections of the grate. Primary air supply is split into sections to be ready to adjust the precise air amounts to the precise air requirements of the zones. The speed of the travelling grate system is dependent on the furnace temperature which is constantly monitored.   From the grate, the semi-combusted gases are led into the most combustion chamber, where secondary air is added. This results in complete blow out of the combustion gases.

The hot flue gasses then pass through to the superheater, evaporator and economiser section of the boiler. The steam is employed to mechanically turn a turbine, which successively spins a generator to supply electricity.

Construction

The biomass boiler and turbine are the key elements in making an efficient and reliable power station . Other equipment referenced (and called balance of plant) include an electrostatic precipitator (used for taking ash out of the gas stream), and cooling towers to chill the steam after passing through the turbine then be ready to reuse the specially processed water.