RAJ Hot Air Generators are tailor-made to suit individual requirements. The units are self-contained, ready to install immediately after power supply is given.

RAJ Direct Fired Hot Air Generator:
The combustion chamber is enclosed in a concentric shell with suitable lining. The fresh air from dynamically and statically balanced blower is fed to the chamber tangentially. The air envelopes the combustion chamber and absorbs the radiant heat from its surface and then mixes with completed combustion gases in a conical chamber.


Hot air, thus generated is let out from Hot Air generator at controlled temperature to the process. Most of the times the combustion chamber is refractory lined. The thermal efficiency is almost 100% with proper insulation and air temperature can be up to 1100 deg.C.

RAJ Indirect Fired Hot Air Generator:

The Combustion Chamber is made out of SS 316 to withstand high temperatures. The combustion is completed within the chamber. Hot gases, after complete combustion are passed through Tube Heat exchanger, comprising of second & third pass.

The systems are available with Light fuel oil and/or Gas fired, backed by fully automatic burners.

Fresh Air from atmosphere is fed onto the surface of combustion chamber through a statically & dynamically balance blower. The shape of passage ensures to form an envelope on the combustion chamber to extract maximum heat, thus higher heat transfer efficiency. The air continues to pass through outer surface of heat exchanger, gaining heat & is collected at the other end of hot air generator. The generation of hot air is within minutes of its start.

Indirect fired hot air generator types are:

These consist of a bank of fin tube radiators. The process air passes over the fin tubes through which either steam or thermic fluid flows. Thus indirect heating of air takes place. Temperatures from 250 to 300 deg. C are achievable depending upon the steam and thermic fluid temperatures. The material of construction of tubes is either carbon steel or stainless steel depending upon process requirement. The mounting of these heaters can be either horizontal or vertical.

Design Aspects

Features of RAJ Hot Air Generators:

Hot Air Generator - Solid Fuel Fired

Raj solid fuel fired hot air generators are offered in vertical or horizontal designs, either as standard models or tailor-made models to match customer's specifications and applications. Designed in DIRECT and INDIRECT heating types, these systems are practically free from any maintenance and are highly efficient.
Direct systems find their applications in high temperature drying, whereas the indirect systems are used where pure air is required for drying. The design is compact & hence space saving. Units are designed for continuous round the clock operation. Air temperature up to 350 degree C is possible in indirect type and 800 degree C in direct type air heaters.

Characteristics of RAJ Solid Fuel Fired HAG

  • The payback period will be 2 to 10 months against oil/gas fired or electrical Hot Air Generators.
  • Multiple pass design, less space,Maximum Efficiency.
  • Very High Thermal Efficiency up to 85% due to perfect combustion, minimal radiation loss & higher heat transfer area.
  • Less maintenance due to minimum usage of refractory in furnace, Horizontal & Vertical design, easy access for maintenance.
  • Less pollution by using Dust Collectors.
  • PLC based completely automated operation to control the temperature accurately.
  • Option of direct & indirect firing available.

  • Fuel:Bagasse, Coal, Wood, Agro Waste, Husk Etc.

  • Capacity:20,000 Kcal/hr to 50, 00,000 Kcal/hr

  • Material of Construction :Carbon Steel/SS 304/ SS 316.