Cosmo Powertech Private Limited

Coal Hot Gas Mode Biomass Gasifier is the simplest and most efficient configuration for utilization of gasifiers for thermal (heating) applications. In this mode, the gas is exited from gasifier at such temperature that volatile constituents in gas (tars) remain in vapour form till the gas reaches the burner(s). To minimize condensation during transit, gas is conveyed through an insulated pipeline. Coarse dust particles are removed in preliminary dust catching equipment such as settlers and cyclones. Fine dust is difficult to remove and gets carried along with the gas. Water consumption is minimal in this mode. Despite removal of coarse particles and insulation of pipeline, small amounts of dust & tar continuously keep settling in the gas pipeline and passages. This requires to be cleaned periodically. Generally, online cleaning provisions are made to achieve uninterrupted long duration operation. Non-stop round-the-clock operations extending to 3-4 months are common in well designed ‘Hot Gas Mode’ gasifier configurations.

The energy content in hot gas (including sensible heat and energy of tar vapour) is of the order of 1450-1550 kcal/Nm3.
(After cooling & removing tar from the gas of ‘hot gas mode’ configuration, the measurable calorific value would report in the range of 1150 – 1250 kcal/Nm3)

The hot gas efficiencies are of the order of 80-85%. Higher flame / furnace temperatures are achieved with ‘hot gas’ as compared to that with ‘cold gas’.

Advantages & Suitability----

• Higher efficiency, higher flame temperatures

• Water treatment issues do not arise

• Minimal water usage

• Suitable to be used where gasifier can be close-coupled with utilization equipment (furnace, kiln, etc.), i.e when gasifier can be installed close to furnace / kiln and gas can be conveyed through a short pipeline

• Suitable only when minor fine dust has no effect on quality of product being heated

Updraft Multi Fuel Biomass Gasifiers are air-blown (air+steam) and operate at near atmospheric pressure. The output gas contains 40-45% combustible constituents mainly in the form of CO, H2, CH4, condensable volatiles and balance inert gases consisting of CO2 & N2. This gas is called producer gas and hence such gasifiers are also known as ‘producer gas plants’.

Fuel is fed through the top of the gasifier while gasifying medium is blown through the bottom. Gases rise upwards countercurrent to the fuel path. Producer gas exiting through the top of the fuel bed carries with it the moisture of fuel, particulate matter (dust) and condensable volatiles (tars). While the gasifier is used in “hot gas mode”, the temperature of output gas is maintained such that tar remains in vapour form and gets burnt at the burner. While the gasifier is used in “cold-clean gas mode”, the temperature of output gas is maintained as low as possible so that most of the sensible heat of gases is absorbed by fuel bed. The output gas is then cooled & cleaned before being sent to user equipment.

Ash is in granular form and comes out of gasifier in wet condition. It does not fly around and can be removed from the site conveniently.

Acceptable Fuels----

Wide variety of carbon containing solid fuels can be gasified in COSMO updraft gasifiers that include biomass, coal and wastes.

with following limitations:

Brown coals, which easily crumble into powder form, are difficult to use as they diminish the porosity of fuel bed, adversely affecting smooth operation of gasifier.

Waste materials can also be gasified. However, they need to be tested in our pilot plant to arrive at appropriate design & operating conditions.

Capacity Range----

300 kWth to 10,000 kWth (10 MWth) in single reactor modules

(Equivalent to 25 to 875 litres/hour oil substitution)
With parallel installation of multiple gasifiers, any capacity is feasible.

Installations having capacities in the range of 50 – 100 MWth at single location are common.