IIT Guwahati develops novel low-cost improved natural draft charcoal retort
Indian Institute of Technology, Guwahati researchers have developed a novel low-cost ‘Improved Natural Draft Charcoal Retort’ (INDCR) to address the technological and capital investment challenges of Indian charcoal makers.
Charcoal is widely used as a fuel for domestic and industrial heating applications. While most of the developed countries are producing industrial charcoal through the retort system, it was not available for Indian charcoal producers because of technological barriers and the need for higher capital investment.
NTPC Ltd’s new initiative wing for waste to energy projects had organised an open competition ‘Green Charcoal Hackathon 2020’, where IIT Guwahati innovators presented the INDCR. “Upon further evaluation and mentorship by the NTPC officials, the developed reactor has been given an opportunity to be demonstrated at the NTPC township of Ramagundam Thermal Power Station in Telangana to produce charcoal from Municipal Solid Waste (MSW) of five tonnes/day, a release from the IIT Guwahati said.
Dr Arun Kumar Chandrasekaran and Dr Senthilmurugan Subbiah, Professors in the Department of Chemical Engineering, IIT Guwahati, who were the lead innovators of the INDCR system, have filed for an Indian patent for the design of this innovative reactor. The reactor’s technical detail and its performance have been published in the reputed peer-reviewed journal aEnergy & Fuels Journal’ of the American Chemical Society.
Researchers from IIT Guwahati have chosen various biomasses such as Prosopis juliflora, Casuarina equisetifolia, Bambusoideae, Biomass briquettes, wood pellets and Refuse-Derived Fuel (RDF) briquettes from Municipal Solid Waste (MSW) as the input feedstock for charcoal making process.
The definition of good quality charcoal depends on its end-user. Hence, the retort reactor has been developed to be capable of producing charcoal in higher mass yield (34-42 per cent), versatile quality of fixed carbon (76-88 per cent), higher energy content (6400-7200 kcal/kg), minimal noxious emission (2.65 kg of CO2/kg of charcoal) and lesser carbonization time (4 hours).
Further, the reactor has the ability to control the process at any point in time during operation. It is user-friendly in terms of loading biomass/feedstock and unloading charcoal. Upon attainment of 270 degrees Celsius and upward, the volatile gases produced in the wood chamber, which are mainly low molecular weight organic volatile compounds are redirected back into the combustion chamber for complete burnout and liberated as complete combustion products.
The retort system operates in an environmentally friendly way with very low emissions of Carbon Monoxide, Carbon Dioxide, Hydrocarbons, and particulate matter. Further, the charcoal produced from the retort reactor was used as a fuel in barbeque & blast furnace heating applications and as a sorbent in pharmaceutical wastewater treatment, the release added.
Highlighting the unique aspects of the developed reactor, Dr Subbiah said, “The innovative reactor is proven to produce high-quality charcoal from a wide range of feedstock, and it’s designed to use its own feedstock as heating fuel. This reactor is portable to agricultural fields, and it is proven to convert all the agricultural waste to charcoal without the noxious gas emissions.”
The developed charcoal retort reactor was installed and tested at Paramakudi, Ramanathapuram district (Tamil Nadu) with the fabrication help of M/s Optima Heat Technologies, Paramakudi, Tamil Nadu.
The pilot-scale mobile charcoal production unit has 125 kgs of input loading capacity with the two-phase mode of operation. The demonstration of the whole research consumed two years with more than 60 field trials to ensure consistent yield and quality of charcoal.
Speaking about the technology transfer agreement between IIT Guwahati and Sanron Fuel Pvt. Ltd., New Delhi, and Samkitec Resources, Hyderabad, Dr Subbiah said, “This technology transfer will enable further research and development in IIT Guwahati to design a higher capacity reactor system to produce an industrial-grade charcoal irrespective of any input loading feed stock with a higher mass & energy yield and lower emissions.”