In ‘Cold-clean Gas Mode’, gas exiting from the gasifier is cooled and cleaned before being conveyed to the utilization equipment. Since the gas is to be cooled, it is attempted to utilize most of the sensible heat of gas within the gasifier reactor. Therefore, the gas is taken out of gasifier at minimum possible temperature.
Calorific value of cold gas is higher as it contains larger fractions of hydrocarbons. It would be in the range of 1250 – 1400 kcal/Nm3. Total energy content in cold gas would be lower than that in hot gas. The gasifier reactor efficiency is higher as compared to ‘hot gas mode’ due to internal heat utilization. But overall system efficiency would be lower as sensible heat of gas is lost when it is cooled.
INDIRECT TYPE POLLUTION-FREE TAR SEPARATION
In this innovative gas cooling & tar separation system, gas is cooled through indirect water circulation. Tar is separated through centrifuging. Water and gas do not come in contact. So, there is no phenolic water generation – no water pollution.Tar comes out through the bottom of the separator and is collected. Almost 90% tar is separated in this simple process. Separated tar can be either collected for use/sale or recirculated back to the gasifier. For removal of residual tar, if the application so desires, electrostatic precipitators are employed.
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