Indirect Bath Heater Water expansion tank

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 Radiant and convective 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 Tube bundle of heating process fluids to higher temperatures) or a mixture of water and glycol (used in colder climates Forced draft heat exchanger to lower the freezing point).

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

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

Variety of applications:

1.     Gas dew point heating: Tube-fire heater high-pressure natural Radiant and convective gas heating upstream pressure regulation stations preventing condensation phenomena Water expansion tank 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 Uniform heating super-heating upstream gas turbines.

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

5.     Hydrate prevention.

6.     Viscosity Process fluid degradation reduction: Crude oil heating treatments to facilitate degassing and dewatering.

FARAN’s Indirect Bath Heaters main parts:

-       Main body

-       The coil or tube bundle Burner water bath

-       The water Natural draft heat exchanger expansion tank

-       The fuel Indirect glycol heater feed line

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

-       The fire-tube

-       Chimney

-       Burner management Tube bundle system panel

-       Skid frame Radiant and convective and service platform

-       Insulation

The heater shell Radiant and convective contains the fire-tube that allows a rapid heat transfer (both radiant and convective) Radiant and convective 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 Gas condensate 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 Uniform heating natural draft:

Natural draft burner relies on a stack to create negative pressure at the burner inlet, Indirect water heater which induces as much air as is required for combustion. These heaters are popular for remote Natural 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 Tube bundle along the fire walls. This results in a reduced tube areas compared to their large bore counterparts, Radiant and convective therefore, overall heater size is minimized creating a significantly smaller footprint while offering Heater shell superior burner control compared to natural draft style heaters.

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