Crude circuit from wharf to Tank and Tank to Units is not insulated. I found seasonal feed temperature change affects on charge heater inlet temperature especially preheat train has been fouled after turnaround. its cost seems a lot.
Is the crude line insulation usual practice? Or do you think we'd better add one more exchanger with pinch study?
Answers
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09/03/2010
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Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Insulating the feed line will not do much good. The bulk of the heat loss is in transportation and storage of the crude. I have observed a 40-50F swing between winter and summer crude oil temperatures feeding the crude unit at inland refineries with cold winters. As others have mentioned a low pressure steam heater or some other waste heat source is probably the best way to offset the effects of these seasonal temperature swings.
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12/02/2010
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Celso Pajaro, Sulzer Chemtech, celso.pajaro@sulzer.com
Unless there is another reason than heat transfer insulating the crude line is rare, if you worry about low crude temperature at the inlet of the preheat, you could use a low pressure steam heat exchanger.
If you preheat train is fouled there are several options besides adding heat exchangers:
1. Antifouling additives (for some crude these additives are very effective.
2. Identify which exchangers are the ones that fouled the most; then, design facilities to take them out for off line cleaning.
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11/02/2010
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Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
I would perform an optimization study of the heat exchanger train in an attempt to justify adding exchanger surface area, and forget the insulation and possible tracing of the crude supply system.
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11/02/2010
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Alan Goelzer, Jacobs Consultancy, alan.goelzer@jacobs.com
In my opinion, all crude preheat trains should include a low-pressure steam preheater [one or two S&T exchangers] so that the crude temperature is brought up to 50C / 122F BEFORE entering the hot oil sources and cold oil sinks exchanger network.
In addition, I now recommend including "jet pump mixer systems using vertical in-line crude transfer pumps with low-pressure steam preheaters" on each large crude storage tanks, assuming that it is reasonable to bring low-pressure steam out to the crude storage tank farm.
It is not common to insulate crude transfer lines from crude receiving terminals and crude storage tanks. Marine shipment of crude oils in winter season and heat losses in the crude storage tank farm can bring crude temperatures down to perhaps 15C to 25C [both of which create challenges for oil-to-oil heat transfer].
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11/02/2010
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Raghavendra Sangam, Libra Techcon Ltd., rsangam0504@yahoo.co.in
Seasonal temperature changes must have been factored-in during the design of the unit. Check the design inlet temperature of the charge heater and compare with actual feed temperature over the past few months. Fouling may be due to change in flow properties of crude such as viscosity, pour point etc besides other crude charecteristics. At lower than design temperatures, some solids remain un-dissolved and deposit in the heat-exchangers. Detailed study of fouling w.r.t location inside the H.E, pattern and type of deposit is required.
However, if lower ambient temperature is more pre-valent which causes flow problems, consider providing heat tracing and insulation from tanks to the pre-heat train.
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