May 31, 2016

Combi Boilers | Combitherm-Three Pass Smoke Cum Water Tube Type Boiler

Combi Boilers – Combitherm: 

Combitherm boiler or is known among others as Combi boiler is a unique water cum smoke tube type design. It is the combination of both Water Tube Boiler and Smoke Tube Boiler where some tubes form the enclosed part of the external furnace in which water flows and rest of the tubes are placed in a shell in which flue gases flow.

Combitherm Boiler (Combi Boilers)

Combitherm Boiler (Combi Boiler) | Combination Boiler

Since the furnace is enclosed with the water tubes on 5 sides, it is the high-temperature zone where the radiation heat transfer takes place and the convection heat transfer takes place in a shell where water is filled in a shell and flue gases are flowing at high velocity in tubes.

Moreover, our membrane tubes design in case of Combitherm boilers/Combi Boilers is such that there are little or no losses to the environment and tubes also provide the high heat transfer area thereby increasing the radiation heat transfer.

Also Read: What is Combi Boiler?

Our shell in case of combitherm (Combi Boiler) is a 2 pass design to increase the residence time and at the same time keeping the velocity optimum to achieve high convective heat transfer. Our shell and water wall tubes provide large water & steam holding capacities to give the maximum advantage.

Combitherm (Combi Boilers)Working:

Water is fed to the boiler from a feed pipe connection. Firstly the water fills in the shell and then gets transported to the Bottom Header of water wall from the Down-comers welded to the Boiler Shell.

From here the water rises up in the tubes of water wall and gets thrown back to the boiler shell from the top header. As firing is done in the furnace, because of radiation the surface temperature of the water wall membrane rises and the water present in the tubes gets heated up and starts getting converted to steam.

Now this steam, being lesser dense (creating a natural circulation of steam-water in the system), rises up to the top header and gets to the Boiler Shell. The flue gas from the furnace (1st pass), traveling in the membrane, then enters the tube of Boiler Shell. In Boiler Shell flue gasses flow in the tube.

These Boiler Tubes are divided in 2 passes (2nd pass & 3rd Pass) where flow gas travel from both the passes and transfer heat to water through convective heat transfer. Steam coming from both the sides get collected at the top of the Boiler shell and then supplied through steam lines for the desired process application.

3 Pass Smoke Cum Water Tube Boiler design can burn a variety of fuels like Coal, Lignite, Rice Husk, Wood, Bagasse, Groundnut shells, and several other fuels thus providing you with lowest energy costs depending upon the fuel available in your area.

The large furnace grate area and furnace volume in case of Combitherm Boilers provide optimum time for fuel to get burnt. On the basis of fuel firing our Combitherm boilers can be divided into 2 types: Manual firing boiler and Automatic firing boiler.

When fuel feeding to the boiler is done manually generally in case of small capacity boilers where the amount of fuel fed to the boiler is generally less is said to be manual firing boiler and when fuel feeding is done automatically usually with the help of screw feeder, drum feeder, chain grate, pulsating grate etc. are said to be automatic firing boiler. Manual and automatic firing also depends upon the type of fuel.

Thermodyne has a vast experience in manufacturing Combi boilers that can burn almost all type of fuels.


  • The flexibility of fuels with choice of agro waste fuels
  • Combines the advantage of both water tube and smoke tube designs
  • High thermal efficiency and low operating costs
  • The higher degree of Equipment’s Reliability
  • Dependable quality of components like valves, pumps, safeties & instruments
  • Can be converted to liquid/gaseous fuels as well
  • Heat recovery unit may be offered for enhanced efficiency
  • Easy access for cleaning and inspection

Capacity Range:

Combi Boiler or Combitherm Boiler, Membrane water wall type boiler is available in capacities from 1 TPH to 15 TPH.


  • Coal,
  • Lignite,
  • Rice Husk,
  • Wood,
  • Bagasse,
  • Groundnut shells,
  • Petcoke, and several other Solid fuels

For More Video: Visit Our Channel

Also Read: Internal Furnace Top Feed Boilers

Our Other Industrial Boilers Products

Show Some ❤!