Lpg Production

[betulk]

Hello everyone I have to design lpg production with my group for design project . We decided to use natural gas as a feed and process is turboexpander process. How we can obtain lpg from this demethanizer bottom product. I know that we have use deethanizer debutanizer depropanizer. But I can't find properties of this columns for references to obtain lpg. And is depropanizer column necessary for lpg? Or are there any lpg processes for higher selectivity?

 

[waross]

Hello everyone I have to design lpg production with my group for design project .

LPG, Liquid Propane Gas.
Start with propane. Compress and remove the heat of compression until it condenses (liquifies).
Did you mean LNG? Liquid Natural Gas?
Compress and chill methane until it liquifies. Keep cold.
Methane can not be liquified nor kept liquid at normal temperatures.
It must be both compressed and cooled in order to become Liquid Natural Gas.
Use the temperature/pressure charts for methane.
If hydrogen is present it may have to be vented off.

 

[georgeverghese]

If your focus is on LPG production from natural gas, then do you need to produce a methane only stream from demethanizer as shown in diagram ? Instead, you can operate a de ethanizer without de methanizer, which will give you a sales gas stream with C1 and C2, while NGL will contain C3 and heavier. This concept will also allow a high dp in the feedgas to enable the operation of a expansion turbine to generate the low temp required at the de C2 column top for reflux.

Note that the operation of demethanizer will not allow the downstream operation of deC2 with expander since deC1 NGL pressure is only 24bar.
The configuration of the deC2 unit can be made similar to what you have now for de C1 column, which should then give you high recovery of C3plus.

From the bottoms product of the deC2 column, you can set up a single downstream LPG column than should give you an overhead LPG stream (minimal C2 + C3 + small quantity of iC4 and nC4), while the rest goes down into bottoms as stabilised condensate with TVP of 12-13psia max at 100degF. If you cannot get TVP of 12psia for bottoms product, then 2 columns may be necessary - deC3 and deC4 - this will depend on the quantity of iC5 in the feedstream to the LPG column.

LPG column can be operated at say 10-12barg, which should enable water cooling at ovhd condensor to give you an almost 100% liquid LPG stream. The deC2 column can be operated at say 20-25barg.