June 01, 2019

Direct & Indirect Heating Burner Solutions from Saint-Gobain

As an important process in many production lines, industrial heating continues to challenge producers in a wide array of industries, including steel and aluminium production, ceramic manufacturing, chemical processing, and glass making.  As these producers look for ways to push their industrial heating processes to higher temperatures and outputs, they are faced with new challenges related to efficiency, throughput, emissions, and maintenance which could be managed through custom built solutions such as, Ceramic Single Ended Radiant Tubes, Ceramic Recuperators, Ceramic Burner Nozzles, Ceramic Flame Tubes, and performance enhancing Ceramic Radiant Tube Inserts for industrial heating applications. Industrial heating can be broken down into two main categories: direct and indirect heating.

Direct Heating

Direct fire, similar to what one might see with a gas stove-top or propane grill, directs the flame and combustion directly into the chamber where products are being processed.  Because all of the energy is being transferred into the production chamber or furnace, direct heating processes are often seen as more efficient and capable of reaching higher temperatures.  However, direct fire heating has the downside of introducing the products of combustion (CO2, H2O and potential amounts of CO, NOx, and sulfides). While some processes can tolerate these combustion products, many processes require a controlled atmosphere within the furnace and must rely on indirect heating.

Indirect Heating

Indirect heating is when heating fuel (i.e. natural gas, oil, etc.) is burned inside of a “heat exchanging element” (i.e. radiant tube, muffle, etc.), suspended within the furnace where product is being processed. The products of combustion are isolated from the atmosphere of the furnace.  The energy released by this combustion must then be transferred, typically through a mixture of convection and radiation, from the heat exchanging element into the furnace chamber and product the furnace is processing.  While this process decreases the overall efficiency of the process, it is necessary to control the furnaces’ atmosphere to ensure product quality.

Saint-Gobain & Industrial Heating

Saint-Gobain Performance Ceramics and Refractories offers a number of innovative solutions that help in both direct and indirect heating processes. For direct heating applications, Saint-Gobain Performance Ceramics & Refractories offers recuperators and burner nozzles that can be found in the following applications:

  • Metal melting, refining, and casting

For indirect heating applications, Saint-Gobain’s offerings can be expanded to include radiant tubes, radiant tube inserts, flame tubes and diffusers, and exhaust-gas recirculation devices, in addition to recuperators and burner nozzles. 

Some of the applications that make use of indirect heating are:

  • Steel coating (i.e. galvanizing, aluminizing)
  • Metal annealing and heat treatment

As an expert in the production and supply of high-quality ceramic products, Saint-Gobain can offer many benefits over competing alloy products used in the same applications, including:

  • Higher application temperatures
  • Better resistance to thermal wear
  • Higher resistance towards chemically aggressive materials
  • Lower maintenance costs
  • Smaller weight and mass

And as one of the top 100 innovators worldwide with a core focus on customer centricity, we strive to deliver value through:

  • Material knowledge and innovation
  • Design & engineering
  • 3D modeling & simulation
  • Prototyping
  • Manufacturing of complex shapes and geometries

Our Products and Solutions

Saint-Gobain Performance Ceramics & Refractories's Burner Solutions focus on Innovation through Sustainability and are committed to delivering our customers and partners savings and value by:

  • Increasing their processes throughput
  • Reducing their energy consumption
  • Lessening their environmental impact
  • Extending their component lifetime and reducing maintenance costs

Ceramic Radiant Tubes

Saint-Gobain’s ceramic radiant tubes can withstand application temperatures of up to 1,380ºC / 2,500ºF and can input up to twice as much energy as alloy radiant tubes into users’ furnaces.  Available for straight and single-ended applications.
Radiant Tube Inserts (SpyroCor®)
Saint-Gobain’s radiant tube inserts can be easily retrofitted into existing radiant tubes to improve efficiency and bolster the amount of heat that the radiant tube is putting into the furnace chamber.  By implementing these inserts, users can experience energy savings of up to 15% or throughput improvements of up to 5%. Available for simple installation in straight, U-type, W-type, and tri-type radiant tubes. Also applicable in P-type and double-P-type radiant tubes.
Saint-Gobain produces recuperators that are integrated into burner systems for both direct- and indirect-heating applications. Recuperators serve to recycle energy by removing it from the waste gasses leaving the furnace and heating the gasses being put into the furnace via the burner. Traditional ceramic recuperators allow for efficiencies of up to 75% in more sophisticated burners systems.
Traditional ceramic recuperators allow for efficiencies of up to 75% in more sophisticated burners systems.

Saint-Gobain also possesses a heat exchanger technology, enabled by its AMASIC-3D® manufacturing platform that allows recuperators and burner systems to exceed 80% efficiencies.  Known as HeatCor, the unique twisted-channel design enables surface areas of up to 3x more than traditional recuperators that fit the same footprint.

Exhaust Gas Recirculation (NoxBuster®)

By inducing exhaust gas recirculation within the radiant tube, NOxBuster® reduces the generation of NOx emissions by up to 50%.
Burner Nozzles
With the recent acquisition of AMASIC-3D®, which includes 3D printing capabilities, Saint-Gobain is able to offer burner nozzle designs of novel configurations and innovative designs.
Flame Tubes/Diffusers
Flame tubes (also called diffusers) act as a guide for the flow of combustion and combustion gasses in single-ended radiant tube applications.  
A special type of flame tube, modified and developed for use in non-single-ended radiant tube applications, such as U-tubes and W-tubes, that protects the radiant tubes from concentrated ‘hot spots’ and dissipates the heat over a larger area, leading to better radiant tube temperature uniformity and possibly increasing the life of the radiant tube
SpyroCor® for Immersion Heating
A newer application for the SpyroCor® technology where the same efficiency boosting technology has been modified for use in single-ended radiant tubes that are used in immersion heating of molten metals and liquid baths. By opting for the SpyroCor® design over traditional designs, users can get more heat out of their immersion tubes, resulting in higher throughputs and reduced energy consumption.