6 replies to this topic

[Hami]

Dear all,

 

I want to calculate the temperature growth height in fuel storage tank. diameter of tank is 46 m  and  the height is 13 m. this tank would be heated by immersed coil. the hot water temperature which flows through coils is 164C. the initial temperature of gasoline in tank is -5C.

 

 

any help would be appreciated

Sincerely

Edited by Hami, 13 January 2014 - 01:18 AM.

[Art Montemayor]

 

Your proposed design or problem is described or designed in an illogical and abnormal manner.

 

This is a very large storage tank.  It is not practical to depend on natural circulation within such a large inventory and expect to control the temperature with accuracy – as is probably required in your gasoline storage.  What is usually done for such an application is that an external pump and hot water heater are used to circulate the gasoline in the tank.  This method is much better and easier to control the tank’s temperature.

 

Your description of using hot water at 164 ^oC is not practical.  For water to be at 164 ^oC it would have to be at least at 6.84 barA pressure – and that is at the saturated state.  Why would anyone do that when you can use steam instead and obtain a higher heating efficiency because of the higher heat transfer coefficient?  I think you mean steam instead.

 

What do you mean by “temperature growth height”?  This is an unsteady state heating problem and what you probably mean to state is that you want to know when the contents will reach a certain temperature.  Is that correct?

 

Also state if this is an assigned homework problem to you and what effort and work input you have done to date.  If you need help on how to solve this problem (when properly described), you should submit your calculations and work done by you so that our member can comment and help you find the method and way of solving this problem.

 

[latexman]

Hami,

 

Take a look at Chapter 18 in Process Heat Transfer by Donald Q. Kern.

[Hami]

Dear Art,

 

Our Combined Cycle Power Plant is located in region which the average of minimum temperature in winter is (-5.3 °C).  It consists of two Gas turbine sets, two HRSGs and a STG.  Fuel oil will be utilized as a backup fuel, when natural gas is not available for the gas turbines.

 

In this section gas oil supply system is designed to supply gas oil to two gas oil storage tanks via fuel oil transferring trucks and the unloading system, and will be transferred to the gas turbines and auxiliary consumers by forwarding pumps and auxiliary pumps, respectively.

 

To maintain the fuel oil temperature above the pour point temperature, the fuel oil is heated to 10 °C above the pour point (-6.67 °C) according to the recommendation of the GTG manufacturer, 6 °C is considered for engineering margin.  Therefore the temperature of fuel oil will be 9 °C.

 

The heating of tanks is maintained by coils.  The required steam for heating a tank is:

Mass flow steam = 5.1 t/h

h₁ = Enthalpy of superheated steam @ 4.5 bar, 164 °C = 2780.0 KJ/Kg

h₂ = Enthalpy of condensate @ 4 bar, 143.62 °C = 604.67 KJ/Kg

If we want to maintain the 9 ^oC for the gasoline in tank, it should be heated for 96 hour.  After 96 hours I want to find the temperature of fuel oil in different sections.  Suppose that I divided tank in 10 layers.  Now what is the average temperature of these 10 layers?

 

Thank you for your help

Sincerely

 

[JMW]

Gasoline and gas oil are quite different, of course and since this is a practical problem rather than theoretical perhaps a practical solution is better?

Most tank storage facilities have some form of temperature sensor on a tape which will allow you to dip the tanks and actually measure the temperature at various levels. The same is true for water fuel interface devices and density and viscosity measurements. Modern dipping sensors will allow you to profile the tank contents quickly and accurately - or at least, accurately at the point of access for dipping.

[Hami]

Dear JMW,

 

Tank you for your suggestion. But I have to estimated temperature growth layer by analytical solution. I think I should model the tank in Fluent software.

 

Gasoline and gas oil are quite different, of course and since this is a practical problem rather than theoretical perhaps a practical solution is better?

Most tank storage facilities have some form of temperature sensor on a tape which will allow you to dip the tanks and actually measure the temperature at various levels. The same is true for water fuel interface devices and density and viscosity measurements. Modern dipping sensors will allow you to profile the tank contents quickly and accurately - or at least, accurately at the point of access for dipping.

[latexman]

"But I have to estimated temperature growth layer by analytical solution.  I think I should model the tank in Fluent software."

 

Yes, CFD seems to be your best option.