Please submit some method to calculat the steam consumption for jacketed line(for example sulfur line).

Dear Mohammed,

Please see the following post for calculating the heat loss through an insulated pipe. Naturally the sulfur pipe is jacketed and also insulated:

http://www.cheresources.com/invision/index...?showtopic=6248

Once you have calculated q as per the equation given in the above post, calculate the steam requirement as:

m = q/H

where m = steam flow rate in lb/h

q = heat loss in Btu/h

H = Enthalpy @saturation pressure in Btu/lb (e.g. H= 1179.3 Btu/lb @ 50 psig)

Note: For your case the Di for the pipe will be the OD of the jacket pipe and the Do will be Di + 2*insulation thikness.

Hope this helps.

Regards,
Ankur

I'm not sure it's obvious, but you treat the pipe jacket (or steam piping) as if it is "the line", and you calculate heat losses from it. Essentially, you have no heat loss or gain to/from the inner (sulfur) line. The steam in the jacket maintains the inner temperature by eliminating heat losses. Steam consumption is then based on replacing the ambient heat loss.

Daer Doug,

I worked in a company where jacketed piping was the norm rather than an exception. I must have done dozens of calculations for heat loss from jacketed piping and equipment. This is the only method I know and it is based on Fourier's law of conductivity. Also, this calculation method was approved by the process licensor.

I would love to know if there is any other method for calculating the mass flow of a heating medium whose sole function is to replenish heat lost to its surroundings due to a temperature gradient beween the process and the surroundings.

Anticipating your reply.

With Regards,
Ankur.

My apologies, Ankur. for not being clear. I am not suggesting a new method for calculating the heat losses from a jacketed pipe. The point I was attempting to make was that the transfer of heat from the jacket fluid to/from the (innermost) process fluid should be minimal (negligable). My experience has the process fluid entering the piping at a good temperature. From that point on, you are not attempting to heat or cool the process fluid; you merely want to avoid heat losses. Since the pipe containing the process fluid is totally contained within the jacket, it quickly reaches the jacket fluid's temperature. Using a condensible fluid like steam, the temperature throughout the jacketed pipe is constant. Steam consumption would then be utilized to balance the heat lost to the environment. Sorry for contributing to any confusion.
Doug