Indirect Fired Recirculating Gas Heaters

Sigma Thermal and Munters Corporation

Sigma Thermal

A process bath heater allows a user to indirectly heat process liquids and gasses by submersing a process coil into a heated bath solution. Typical applications are natural gas heating, crude oil heating, amine reboiler, glycol reboiler, in-line liquid heating, and in-line gas heating. The bath solution is heated by a fire tube style burner submerged at the bottom of the heater vessel. Water-glycol mixtures are very common solutions for most low temperature heating applications, and can typically be used up to 250°F. In some special high temperature applications, salt melts can be used to meet the higher operating temperature requirements.

The following are process bath heater design features:

• Coil Configuration Flexibility: Coil flow path and metallurgy are engineered for each customer’s process requirements. Sigma Thermal has extensive experience in process coil design for multi-phase fluids, viscous hydrocarbons, suspended solids, and various gaseous mixtures.
• Fuel Source and Burner Flexibility: Standard or engineered burner configurations are available for use with both traditional and alternative fuel sources. Low emissions burners can be supplied to meet all emission requirements (e.g., Low NOx, Best Available Control Technology).
• Advanced Control Systems: Complete control systems are engineered to optimize system safety and performance. Sigma Thermal can supply simple and cost effective standard panels, as well as full process automation and PLC-based combustion control/BMS.

The Weir Bath Heater is a slight variation of a traditional water bath heater that does not utilize a process coil. This type of heater is most commonly used as a reboiler for amine and glycol solutions. The bath vessel contains a fire-tube and a weir at the end of the fire-tube. The process fluid is circulated through the bath vessel in direct contact with the fire-tube. After the process fluid is heated, it falls over the weir where the return line sends it back to the process user.

Munters Corporation

For process applications that require clean, heated air, Munters offers the ultra high efficiency VariMax™ indirect fired, recirculating gas heater that provides heated, contaminant-free process air while reducing operating costs.

Most indirect heaters lose 30% to 50% of heat energy through the exhaust stack; the VariMax™ heater can transfer 90% of the heat energy to process, providing recurring annual savings. In addition, the heater's rugged, heavy duty construction makes it a long-lasting heat source.

The VariMax™ IFRG indirect heater achieves extremely high efficiency levels by recirculating a hot air stream through a semi-closed loop. Traditional systems lose a tremendous amount of energy as the exhaust gases leave the heat exchanger after one pass. The VariMax™ IFRG keeps this energy in the system with the only significant energy loss being exhaust air bleeding from the recirculation loop to offset the incoming combustion air flow. The process air is heated to the desired set point as it passes through the primary heat exchanger. To further increase efficiency up to 95%, customers can add an optional second heat exchanger to capture the energy from the exhaust air and use it to preheat the incoming combustion air.