Hot Oil Heater - Natural Gas or Electric Heating? 1

[dlefin]

I am in the process of designing a new plant that requires a hot oil heater for process heating. I am trying to determine which is more cost effective to heat hot oil - natural gas or electricity? Plant is in TX. I estimate the heat load to be around 2,000,000 BTU / hr. Temperature of the hot oil will be maintained at 400 oF.

 

[pmover]

determine cost of energy input (electricity vs. gas vs. oil vs. etc.) and assume an efficiency of the heater. my SWAG is that natural gas is the better choice (barring any environmental issues) for the duration of the plant/equipment.
certainly, the supply of resources will need to be addressed, but then again, location is in texas where there is an abundance of energy supply.
-pmover

 

[Montemayor]

dlefin (Mechanical):

Take it from another Texan: this is a no-brainer. A direct fired heater with natural gas as fuel beats an electrical resistance heater everytime - and by a big margin.

There is no environmental issue in Texas, except a permit to fire. At a heat load of 2 MMBtuh, I would not hesitate to commence my engineering and planning based on using Natural gas. However, if you were working under me in Process design, I would require an economic calculation to justify the decision based on fuel and total operating and Capital costs.

There is no "abundance" of Natural gas (in Texas or any other US state); however, when you have to burn Natural gas to produce the electricity anyway, it doesn't take much brain cells to figure out that if there is no Natural gas, there is no electricity anyway! I presume you are going to heat a DowTherm fluid or something similar. Good Luck.

Art Montemayor
Spring, TX

 

[25362]

If, as Art Montemayor rightly suggests, you carry out an overall plant economic (including "what ifs&quot balance, is it possible to also consider steam process heating (only if there is available steam) as an alternative in the study ? The total steam duty would be around 1 ton/h and you may allow yourself a lower steam temperature (and lower steam pressure) for the heating purpose, especially if the heated material is temperature sensitive.

 

[Montemayor]

25362:

I don't think you can achieve the 400 oF oil temperature that dlefin proposes by using conventional steam utility pressures and boilers. You'd have to go as high as 300+ psig or higher, rather than the conventional 150 - 200 psig range. However, your point is a great addition to the list of competitive heating methods is such a level of steam supply exists. If it does exist, I suspect it would win out as the winning candidate.

Art Montemayor
Spring, TX

 

[dlefin]

Gentlemen, Thank you for your response to my question. My gut feel told me that gas was the right way to go as well. Steam is not an option - the plant manager would never buy into a steam boiler.

This is my first time using this forum. I am very impressed with how this works.

 

[TD2K]

Umm, no. If you don't have steam already on site, steam is pretty much of a no-go for a heat requirement this size.

 

[chicopee]

If you use electricity, you may be able to get a discount rate from the utility company. Otherwise NG is more economical "ounce for ounce".

 

[25362]

To Art Montemayor and others, I'm well aware of the limitations you mentioned, however when a hot thermal oil needs 400F to achieve the heating duty you can easily use steam with a 100 F lower (saturation) temperature for the same purpose. That's the beauty of it. But, as I said, it should be already available, better even, with the possibility of returning the condensate.

An added benefit: if the material heated is thermally sensitive, you may protect it by keeping metal skin temperatures low enough.

This is a subject that only dlefin can tell when doing the full economic analysis.

 

[25362]

Thank you for the undeserved star. There is another possibility that dlefin could include in his techno-economic analysis, and that is direct electric "process" heating without the use of an intermediary hot oil. My experience with this type of heating has been quite satisfying, especially with delicate stratifying heat-sensitive two-phase flows on the process side. All depends on the design "quality" of the heating units.

 

[ITP]

As a German supplier for Thermal oil systems, we would like you to consider even other issues. The capacity of the heater is rather small which keeps the investment for electrical thermal oil heater on an acceptable level. Using a gas fired heater, one should not forget that more equipment and space is needed. You need a gas burner, ducting and a stack. You probably have annual emission tests and require more spare parts such as flame sensors, ignition electrodes, gas soelnoid valves etc. An electrical thermal oil heater can be installed even within buildings very close to the consumer, which saves piping. Here in Europe electrical thermal oil heaters are seldom used as the costs/kWh are too high. Other countries where power is cheaper due to water power plants etc. can run these systems more economical. A major issue is the reliability - a burner can fail due to various reasons (solenoid valve, ignition electrodes, fan etc.) It is unusual to keep all these spare parts in stock which means that your down time can be quite long. For an electrical thermal ol heater, one only need a spare heating rod and some electrical parts. The first investment does not matter so much. Important is that one can operate the system with a minimum staff and down time, as down time will normally cause you the real problems - production loss, order delays etc. If you would like to go more in detail, please visit our webpage

http://www.maxxtec.com

or drop us a line

Stefan

 

[CraigTiras]

I'd heat it directly with an electric process heater. Go to

http://www.integraheat.com

for more information and sizing /selection.