Steam Heater for Drum

Is this some sort of theoretical question? With out knowing temperatures involved, as well as every other aspect of this system and environment including heat load and btu supply, no answer can be found....

Yancheng Laiyuan electric equipment co. ltd supply industrial electric heaters

www.china-laiyuan.com/

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What is a 30 MegaTesla drum?

Tks for your response,

MT = Metric Tonne, good try Mega Tesla drum ????

Tks

Further to DHAYANANDHAN's excellent post there are some worrying aspects to to your posts

MT is Mega Tesla as a unit. Metric tonnes are shown as t (or occasionally te). The easy way to remember if a unit should have a capital is if it is the named after a person.

When quoting pressures it is always useful to quote absolute or gauge. As an engineer in oil and gas fields I would always assume gauge. This leads into the second point of learning how to use steam tables and also some standard knowledge.

I would have thought it common knowledge that 15psi absolute is approximately atmospheric pressure and that at atmospheric pressure water boils at 100°C. So I am not sure how you achieve the 60°C limit to which you refer.

The generation of these steam pressures is important because of the degree of superheat in the steam will effect the temperature.

125 psig Saturated Temp 178°C, 125 psia Saturated Temp 173°C

15 psig Sat Temp 121°C, 15 psia Sat Temp 100°C

However if they are both generated from letting down 250 psig steam (Tsat = 207°C) then the temperature if the steam is not properly desuperheated could be much higher than the saturated temps given.

It is normal to have at least a small amount of superheat in steam systems to prevent cold spots in the piping causing condensation.

Further questions would be

is the 30t mass the mass of steel for the vessel? This is for determining the total thermal duty. What are the contents of the vessel? (even if it is just nitrogen there is a thermal load)

Is the coil in good thermal contact with the vessel? Or is the coil inside the vessel and heats the vessel contents?

Why is 60°C so important?

Is the vessel well insulated?

If thermal connection is poor / insulation is poor then its likely to be necessary to use 125psiX steam to overcome these limitations.

If the heating process is carried out everyday then it is important to cut the time down as much as possible and so using the 15psiX steam for the initial heat makes sense. If this heating process is only carried out once per annual run then the time frame is less important and the lower pressure steam could be used.

How are you proposing to control the steam flow? Having two controlled heating fluids foes have some cost in terms of piping and control valves but this would seem to be a small cost compared with such a large vessel.

regards

Simon

When you drop the pressure to 15psi steam, the heat transfer rate (coil to process fluid) will drop proportionately, and you will not maintain the desired temperature.

2. When reaching 60 Deg , switch the supply to 15psi system such that it will never goes above 60Deg C ( Safety process specification).

I am not practiced enough to calculate the correct steam pressure to maintain the required process temperature, with a great level of confidence. I have seen similar process problems solved by trial-and-error in the past, by very keen process operators.