Dear All,
How much fuel consumption for PWHT Process of a spherical tank with diameter 22,5 m, 50 mm in thickness, which the process is following :
Heating a spherical tank from ambient temperature to 800 F. From 800 F, heating continues to 1100 F with heating rate 400 F / hour. Subsequently, the tank needs to be held at 1100 F for 2 hours. After that, cooling would be done at cooling rate 500 F / hour, to reach 800 F. From 800 F, the vessel may be cooled in still air.
I need to estimate, at least, the comparison of fuel consumption, between LPG and Diesel Fuel, excluding fuel consumption for vaporizer, blowing fan, or genset. Formulations or empirically formulas would be helpful.
Thank you so much.
S. Yusuf (Mech. Eng)
Not only do you not have enough information there, you do not have the right kind of information.
You need to estimate from flow rate and volume for the gas. In other words, how many burners and how hard are you pushing and for how long. Factor in the gas cost per CFH or CMH, etc. and you have your cost.
For deisel fuel I would have no idea.
22.5m? 50mm Thickness? Man you must have one huge oven. Do yourself a favor and use resistance heaters. Not only will it be more energy efficient - you need only heat the welded seams, but temperature control will be more precise.
No, John, Yussuf doesn't need to have a big oven.
For PWHT spheres, the sphere itself is transformed into an oven. It's covered with temporary insulation and a burner (or two) is stuck onto the bottom mandoor. The top mandoor is left open for the combustion gases to be released.
Then you light the burner up and control the combustion by controlling the temperature the metal is at. Of course, you need a number of temperature indicators (thermocouples) located in several points of the sphere to ascertain that no point is at a lower temperature than required.
Giovanni S. Crisi
Sao Paulo - Brazil
Hadn't seen that done, but it still seems to me that you would have quite a gradient from the area were heat is applied to opposite end. No?
Let me know your mailing address (through a private message, if you want) and I'll send you some literature showing how PWHT of spheres is carried out.
The material is in printed format, not electronic, so I can't send it to you by e-mail, just by priority air mail.
Giovanni S. Crisi
I would like to see that as well.
Can you mail it to China?
3.2
3.2,
Aren't you German? What the heck are you doing in China?
Of course I can mail it to China, provided I know the mailing address.
Can the postal service in China read addresses that are written in the occidental (Latin, to be precise) alphabet?
Giovanni S. Crisi
I am from Denmark, now stationed in Shanghai, China.
I will PM you my address.
3.2
Yusuf,
You want to compare GLP and diesel oil to see which one is cheaper.
Now, it's quite complicated to figure out the amount of fuel you're going to burn. So, if I were you I would proceed in a much simpler way.
First: How much is the calorific value of the GPL and diesel oil you're going to use? In other words, how many kilojoules (or BTU, or kilocalories) are released by the combustion of one kilogram (or one pound) of each fuel? Both being hydrocarbons, the lower calorific value applies.
Second: what's the price of one kilogram (or pound) of each fuel?
Third: now that you have both data on hand, it's easy to make a comparison as to which one is the most convenient.
Giovanni S. Crisi
Sao Paulo - Brazil
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