Monday, April 1, 2013

Biomass plant design


The traditional way of generating electricity from biomass is in most cases based on the direct combustion and the production of steam, which drives a steam turbine, like it is in coal power plants. This technology is now very sophisticated and allows the use of several types of starting materials. Its disadvantage is that it requires relatively high investment costs per unit of output, the overall production efficiency is low, and also provides opportunities for further improvement.

Producing electricity by biomass gasification is a new method. Rather than direct combustion of biomass, gasification process is utilized and the subsequent burning of the gas in the gas turbine. The advantage of this technology is much higher efficiency, because in gasification to 65-70% of the energy contained in the biomass is converted into combustible gas. Investment costs for the construction of gas turbines are relatively low and there are also significant opportunities to improve technology. Although the method provides several advantages gasification is not yet sufficiently developed for it to be able to be used widely.
Plants with biomass gasification consists of the following components:

  •   Apparatus for transport and fuel
  •   Gasification reactor vessel
  •   Gas cleaning and mixing system
  •   Turbine respectively. combustion engine


What is biomass


Biomass is plant or animal organic material suitable for industrial and energy use. In terms of energy productin, plant biomass - phytomass is very important. Everything growing in the fields or woods is chemically preserver solar energy.

Biomass for energy occurs mainly as waste in industrial, construction, forestry, agricultural and livestock production as well as residential municipal waste. Wood and wood waste can be used directly in boilers for heating the heat carrier heating system and hot water or steam. Wood waste can be compressed and briquetted. The agricultural and livestock production creates large quantities of waste such as straw. Biomass can be used not only for heating but also for gasification and combustion in gas cogeneration units for power generation. Liquid and gaseous forms of biomass (ethanol, methanol, wood gas, biogas) can also be used to power motor vehicles. Its use reduces dependence on countries from primary sources imported from abroad reduces the burden on the environment, contributing to the reduction of CO2 emissions, reducing emissions from burning fossil fuels, to better appreciate domestic raw materials and so on. The great advantage of biomass is that it is renewed annually at a purposeful cultivation can be almost inexhaustible source of raw materials and energy.

All the fossil fuels that we consume today (coal, oil, natural gas) are essentially ancient biomass, which is changed by pressure, temperature and chemical reactions to these concentrated sources of energy. However, the process takes millions of years, so we consider these non-renewable fuels. Fossil fuels affects the environment by burning them in the atmosphere of the receiving agents that are millions of years old "preserved" under the surface. Unlike the burning of fresh biomass in terms of greenhouse gas neutral. The combustion of biomass, the oxygen from the air combines with the carbon in plant and generates carbon dioxide and water, and carbon dioxide is a substance of the new entry biomass.

Due to the different forms of biomass varies the energy it contains. Energy content of dry product (moisture content 15 to 20%) is around 14 MJ.kg-1. Completely dry biomass may therefore be in terms of energy content compared to coal, which has a calorific value of 10 to 20 MJ. kg-1 in brown coal and about 30 MJ.kg-1 for black coal. At the time of collection, however, biomass contains significant amounts of water, ranging from 8 to 20% for straw, 30 to 60% in fresh wood, while for coal is about 2 to 12%. Chemical composition of biomass, however, makes it a much more environmentally friendly fuel as coal. Biomass in comparison has lower sulfur coal. The ash content in the burn is also lower than in the case of coal, the ash also does not contain toxic metals.