Indirect Bath Heater Furnace gas heating

Indirect bath heaters are mainly used in the oil and gas industry to heat process fluids. The mechanism takes place indirectly through a bath (utility bath) as opposed to heating directly by flame or furnace (direct fire-tube heaters).  The use of a bath promotes uniform heating and reduces the chance of hotspots. Due to the indirect nature of bath heaters the safety risks are much lower (combustible streams isolated) compared to direct fire-tube heaters, they can therefore be used in hazardous areas where safety is a concern.

The “indirect” name comes from the fact that a fire-tube is submerged in a bath that provides Gas station pressure drop heating through the bath Furnace gas heating medium to a submerged coil containing the process stream. Usually the bath fluid is water but depending on the climate and heating requirements it can also be oil (capable Forced draft heat exchanger of heating process fluids to higher temperatures) or a mixture of water and glycol (used in colder climates Radiant and convective to lower the freezing point).

Hotspots often occur in direct fire-tube heaters Carbon built-up as a result Water expansion tank of carbon build up on the fire side of the tubes. If left unchecked this build up can be a source Water expansion tank of process fluid degradation and may lead to ruptures, explosions and leaks.

Typically, FARAN’s Process fluid degradation indirect bath heater Pressure drop in gas s achieve around 50-55% heating efficiency Natural draft heat exchanger . This relatively low efficiency compared to direct fire-tube heaters is a result of the number of heat transfer steps involved. Typically Uniform heating indirect bath heaters are used where the flow rate of the process stream is low and operations Pressure drop in gas may be unattended, they could also be used to prevent coke formation on the tubes when low heat Gas station pressure drop fluxes are required.

Variety of applications:

1.     Gas dew point heating: Burner water bath high-pressure natural Indirect water heater gas heating upstream pressure regulation stations preventing condensation phenomena Gas station pressure drop due to Joule-Thompson effect.

2.     Heating of high-pressure natural gas upstream pressure regulation in order to prevent external icing formation.

3.     Fuel gas Water expansion tank super-heating upstream gas turbines.

4.     Gas heating Pressure drop in gas downstream low temperature storages.

5.     Hydrate prevention.

6.     Viscosity Radiant and convective reduction: Crude oil heating treatments to facilitate degassing and dewatering.

FARAN’s Indirect Bath Heaters main parts:

-       Main body

-       The coil or tube bundle Uniform heating

-       The water Combustion stream expansion tank

-       The fuel Indirect water heater feed line

-       Burner (gas type, oil type or bi-fuel)

-       The fire-tube

-       Chimney

-       Burner management Indirect water heater system panel

-       Skid frame Heat exchanger and service platform

-       Insulation

The heater shell Combustion stream contains the fire-tube that allows a rapid heat transfer (both radiant and convective) Combustion stream from the flame to the hot medium. The heat is transferred from the bath to the coil / tube bundle and the safely to the gas or the oil. The expansion tank allow the hot medium to be contained for the Radiant and convective thermal expansion due to the temperature increase. Level gauges and transmitters advise when additional Tube bundle water or hot medium is required and give alarms in case of overfilling.

Forced draft Vs Heating efficiency natural draft:

Natural draft burner relies on a stack to create negative pressure at the burner inlet, Combustion stream which induces as much air as is required for combustion. These heaters are popular for remote Water expansion tank locations and/or locations with limited or even no power supply available.

Forced draft heaters are ideal whenever there is a low emission requirement, utilizing small bore fire-tubes in conjunction Natural draft heat exchanger with a combustion air fan. High velocities in small bore fire tube reduce the dead gas film region Pressure drop in gas along the fire walls. This results in a reduced tube areas compared to their large bore counterparts, Water expansion tank therefore, overall heater size is minimized creating a significantly smaller footprint while offering Indirect glycol heater superior burner control compared to natural draft style heaters.

FARAN Process & Energy Tube-fire heater engineering company is able to design and manufacture different size of indirect water bath heater  which vary from 90 kW up to 10MW.