3 replies to this topic

[Miguel]

helo,

im simulating a glycol dehydration process, and im having trouble with sizing the regenerator i would like to know how to calculate the height of the regenerator and the packing

PD: i dont use striping gas

regards

[Art Montemayor]

Miguel:

Nobody in his right mind "calculates" the height of a Triethylene Glycol regenerator stripper tower. It is a waste of time. We, who have designed these units in the past, have a height that we use for the majority of all towers. It is 2 meters high. This only allows for the packing ( or the 3 or 4 bubble caps trays - if that is what you want to use). You still have to allow for the cooling coil at the top.

These units are so small that the practical problem is to construct them large enough to be able to weld them and maintain them in operation.

In my opinion, if you are going to use stripping gas to control the dew point you are simply not going to have a practical and workable design. Stripping gas is the major factor for regenerating the wet, rich TEG into lean TEG.

[Miguel]

thank you for your response, im a chemical engeenering student this subject is new for me, i read in JM. Campbell book that striping gas is recomended when you need a more efficient regeneration for highter glycol concentrations ( 98.5 higher) im working with a 98.5% concentration of glicol (on the limit) acording to the text its not necesary stripping gas , if im wrong please correct

thank you very much for your observations

regards

[Art Montemayor]

Miguel:

You have one of the basic books and information needed to learn about glycol dehydration of natural gas. John Campbell's books are among the most acknowledged expert sources for that information. You should also use the NGPSA Engineering Databook for your studies. Kohl & Nielsen’s important 5th Edition of “Gas Processing" is also an excellent source of design information.

However, you are not communicating very well. As an engineering student it is important to understand that you must first learn to define the BASIC PROBLEM. Your basic problem is drying natural gas. As an engineer you should know that this is not enough specific information. You need to know HOW MUCH DRYING you need to do. You also need to know AT WHAT CONDITIONS. You have failed to say anything about all this.

If you are planning to dry natural gas, it must be because you want to transport it by pipeline. Correct? There is a maximum water content that can be tolerated in the gas as it flows in the pipeline. Even in Venezuela, you must identify what that value is and then design to ensure that you don't even approach it. I suspect that value is approximately 7 lbs of water per MMScfd of natural gas. That means you must ensure your TEG (Tri Ethylene Glycol) unit drys the gas below that value. In order to ensure this, you MUST produce lean glycol in your regeneration that produces the desired dry gas coming out of the glycol contactor.

Your problem, then, is HOW TO PRODUCE THE NECESSARY LEAN TEG. You identify the % TEG required by referring to Campbell and NGPSA. There, you will find that you cannot produce the desired product without using stripping gas.