Indirect Bath Heater Heating efficiency

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 Forced draft heat exchanger heating through the bath Heat exchanger 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 Indirect glycol heater of heating process fluids to higher temperatures) or a mixture of water and glycol (used in colder climates Gas condensate to lower the freezing point).

Hotspots often occur in direct fire-tube heaters Natural draft heat exchanger as a result Radiant and convective of carbon build up on the fire side of the tubes. If left unchecked this build up can be a source Burner water bath of process fluid degradation and may lead to ruptures, explosions and leaks.

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

Variety of applications:

1.     Gas dew point heating: Burner water bath high-pressure natural Water expansion tank gas heating upstream pressure regulation stations preventing condensation phenomena Heating efficiency 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 Tube-fire heater super-heating upstream gas turbines.

4.     Gas heating Carbon built-up downstream low temperature storages.

5.     Hydrate prevention.

6.     Viscosity Pressure drop in gas reduction: Crude oil heating treatments to facilitate degassing and dewatering.

FARAN’s Indirect Bath Heaters main parts:

-       Main body

-       The coil or tube bundle Heat exchanger

-       The water Carbon built-up expansion tank

-       The fuel Water expansion tank feed line

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

-       The fire-tube

-       Chimney

-       Burner management Tube-fire heater system panel

-       Skid frame Heater shell and service platform

-       Insulation

The heater shell Gas condensate contains the fire-tube that allows a rapid heat transfer (both radiant and convective) Pressure drop in gas 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 Forced draft heat exchanger thermal expansion due to the temperature increase. Level gauges and transmitters advise when additional Burner water bath water or hot medium is required and give alarms in case of overfilling.

Forced draft Vs Indirect water heater natural draft:

Natural draft burner relies on a stack to create negative pressure at the burner inlet, Radiant and convective 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 Heat exchanger with a combustion air fan. High velocities in small bore fire tube reduce the dead gas film region Heater shell along the fire walls. This results in a reduced tube areas compared to their large bore counterparts, Furnace gas heating therefore, overall heater size is minimized creating a significantly smaller footprint while offering Pressure drop in gas superior burner control compared to natural draft style heaters.

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