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 Heater shell heating through the bath Pressure drop in gas 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 Carbon built-up to lower the freezing point).

Hotspots often occur in direct fire-tube heaters Furnace gas heating as a result Pressure drop in gas of carbon build up on the fire side of the tubes. If left unchecked this build up can be a source Forced draft heat exchanger of process fluid degradation and may lead to ruptures, explosions and leaks.

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

Variety of applications:

1.     Gas dew point heating: Water expansion tank high-pressure natural Process fluid degradation gas heating upstream pressure regulation stations preventing condensation phenomena Process fluid degradation 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 Process fluid degradation super-heating upstream gas turbines.

4.     Gas heating Gas condensate downstream low temperature storages.

5.     Hydrate prevention.

6.     Viscosity Combustion stream reduction: Crude oil heating treatments to facilitate degassing and dewatering.

FARAN’s Indirect Bath Heaters main parts:

-       Main body

-       The coil or tube bundle Gas condensate

-       The water Indirect glycol heater expansion tank

-       The fuel Water expansion tank feed line

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

-       The fire-tube

-       Chimney

-       Burner management Combustion stream system panel

-       Skid frame Heat exchanger and service platform

-       Insulation

The heater shell Forced draft heat exchanger 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 Indirect water heater thermal expansion due to the temperature increase. Level gauges and transmitters advise when additional Heater shell water or hot medium is required and give alarms in case of overfilling.

Forced draft Vs Combustion stream natural draft:

Natural draft burner relies on a stack to create negative pressure at the burner inlet, Process fluid degradation which induces as much air as is required for combustion. These heaters are popular for remote Forced draft heat exchanger 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 Indirect glycol heater with a combustion air fan. High velocities in small bore fire tube reduce the dead gas film region Gas station pressure drop along the fire walls. This results in a reduced tube areas compared to their large bore counterparts, Pressure drop in gas therefore, overall heater size is minimized creating a significantly smaller footprint while offering Carbon built-up superior burner control compared to natural draft style heaters.

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