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 Combustion stream 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 Heating efficiency Indirect water heater of heating process fluids to higher temperatures) or a mixture of water and glycol (used in colder climates Tube-fire heater to lower the freezing point).

Hotspots often occur in direct fire-tube heaters Natural draft heat exchanger as a result Indirect water heater 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 Carbon built-up indirect bath heater Carbon built-up s achieve around 50-55% heating efficiency. 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 Gas condensate fluxes are required.

Variety of applications:

1.     Gas dew point heating: Water expansion tank high-pressure natural Indirect glycol heater gas heating upstream pressure regulation stations preventing condensation phenomena Pressure drop in gas 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 Forced draft heat exchanger super-heating upstream gas turbines.

4.     Gas heating Combustion stream downstream low temperature storages.

5.     Hydrate prevention.

6.     Viscosity Furnace gas heating reduction: Crude oil heating treatments to facilitate degassing and dewatering.

FARAN’s Indirect Bath Heaters main parts:

-       Main body

-       The coil or tube bundle Water expansion tank

-       The water Process fluid degradation expansion tank

-       The fuel Indirect glycol heater feed line

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

-       The fire-tube

-       Chimney

-       Burner management Burner water bath system panel

-       Skid frame Indirect glycol heater 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) Gas station pressure drop 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 Tube-fire heater thermal expansion due to the temperature increase. Level gauges and transmitters advise when additional Carbon built-up water or hot medium is required and give alarms in case of overfilling.

Forced draft Vs Heater shell natural draft:

Natural draft burner relies on a stack to create negative pressure at the burner inlet, Water expansion tank which induces as much air as is required for combustion. These heaters are popular for remote Pressure drop in gas 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 Process fluid degradation 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, Heating efficiency therefore, overall heater size is minimized creating a significantly smaller footprint while offering Process fluid degradation superior burner control compared to natural draft style heaters.

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