13 replies to this topic

[dhns]

Dear sirs,

Could any one please explain about the Natural Gas-dew point control,

what is the need to control the dew point for Natural Gas?

If am selling that natural gas, in that point of view what is the relation
with the dew point.

if any notes regarding that please notify the same,

anticipated kind thanks,

[ethylene]

hi

my understanding on natural gas dewpoint.

Natural gas normally transported in pipeline at high pressure. If the surrounding temp is low enough, liquid may formed by condensation of high molecular weight HC. To avoid this, the gas is dewpointed which heavies is removed by reducing temperature and separate the liquid formed to achieve lower dewpoint at pipeline operating pressure.Typical dewpointing method include turbo-expander process and mechanical refrigeration.

[ankur2061]

dhns,

A very nice article on dew-point & moisture control at the following link is available:

http://www.iceweb.co.....ent Paper.doc.

Read, learn and enjoy!

Regards,
Ankur.

[Art Montemayor]

dhns:

I am glad you brought this subject up. I am presently marking up some erroneous equipment specifications and concepts on how to transport, treat, dehydrate, and maintain natural gas in a Pipeline quality condition in order to distribute it nation-wide for sales and an expected profit. I am currently slated to go into a meeting tomorrow morning at 10 am to try to convince some very aged and educated engineers on what they are doing wrong. I am on my second bottle of wine and I may need a new red pen before I get through marking up all this documentation in front of me. It is truly sad that some engineers just don’t get the “picture” yet.

Natural Gas-dew point control is a requirement because:

1. Pressurized natural gas in contact with liquid water will form solid hydrates. These hydrates will clog and plug up pipelines, valves, and any transport equipment;
2. Any liquid water in natural gas pipelines will cause corrosion and eventual failure of transport equipment;
3. Any excess water in a natural gas pipeline is a freezing threat to the transport of the gas.
4. Water content in natural gas decreases its heating value.

There is a definite need to control the dew point for Natural Gas because without it the gas can’t be successfully and continuously transported and distributed when it is needed. Here, the dew point is that of water - not of other hydrocarbons as erroneously stated by ethylene. As stated above, solid hydrates of methane will form and corrosion will appear.

If you are in the business of selling natural gas, the dew point of the same natural gas is very important to control and maintain because if you don’t, you won’t be able to transport the gas and sell it successfully. If you can’t sell the gas, then you can’t raise any revenue to justify your investment. The end result is that you will go bankrupt. I think this more than enough reason for you to take an interest in protecting your investment by drying the natural gas to a safe dew point and controlling it there. – Don’t you?

[dhns]

Dear sirs,

Thanks for your delicious reply for my doubt,

once again thanks for mr. art to lighted the correct raw resons, behind the dew point controlling of natural gas.

thanks,

[Padmakar Katre]

[size=4][font="Times New Roman"]dhns:

I am currently slated to go into a meeting tomorrow morning at 10 am to try to convince some very aged and educated engineers on what they are doing wrong. I am on my second bottle of wine and I may need a new red pen before I get through marking up all this documentation in front of me. It is truly sad that some engineers just don’t get the “picture” yet.

Dear Art,
Indeed one of the nicest replies by you.

[Qalander (Chem)]

Splendid focused Reply! Dear Art.

[Muneeb]

In case you need to calculate/estimate the dew point temperature for your natural gas compositions at their given Pressure, you can use this online calculator at this link:

http://www.chemsof.com/flash/flash.htm

it can caculate the dew P, T, and Bubble P, T as well.

[ethylene]

Dear Art

Thank you for enlighten me. Could you please further explain why there is specification for hydrocarbon dewpoint in some natural gas pipeline.

[shan]

To avoid two phase flow, low point accumulation (slug forming), and higher BTU/SCF.

[NGL Licensor]

Hi

Dew point control is to provide a sales gas quality that meets HD dew point and water dew point specifications

The process scheme mainly depends on:
- Feed gas composition and conditions
- Sales gas product conditions and battary limit conditions
- Onshore or offshore
- Ambient conditions

If you can drop the answers for the above then you may expect a realstic answer

Thx

AF.King

<!--quoteo(post=30889:date=Jul 15 2009, 01:26 AM:name=Art Montemayor)--><div class='quotetop'>QUOTE (Art Montemayor @ Jul 15 2009, 01:26 AM) <a href="index.php?act=findpost&pid=30889"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->[size=4][font="Times New Roman"]dhns:

<b>I am currently slated to go into a meeting tomorrow morning at 10 am to try to convince some very aged and educated engineers on what they are doing wrong. I am on my second bottle of wine and I may need a new red pen before I get through marking up all this documentation in front of me. It is truly sad that some engineers just don’t get the “picture” yet.</b><!--QuoteEnd--></div><!--QuoteEEnd-->

Dear Art,
Indeed one of the nicest replies by you.

It's really bad to hear this that even these people are still learning.So what is the use of seniors....

[kkala]

It's really bad to hear this that even these people are still learning.So what is the use of seniors....

Well, to be senior does not mean you know everything, even in your own narrow field. Knowledge is so broad nowadays. Of course it sounds strange that these old engineers do not know the significance of moisture in natural gas. But did all of us know it? After all these may not be involved in gas operation / design, but in pipeline construction or general design. However this is not the main point I want to express.
The point is that even seniors should seek learning in order to face the ever changing situations. Experience may create background, knowledge, confidence; but you should first learn and understand the new situation before you act. Then every task will most probably need additional knowledge that has to be gained. Seniors should have known how to learn and do it in a more systematic and calmer way. Apart from assessing a critical decision, also a sort of gained knowledge.
What if this desire to learn stops? You may have been too old, at least as an engineer.
Personally I have met several "officers" not having adequate knowledge. Judgment on them depends on their behavior in front of missing knowledge; it strikes mainly in case of arrogance.
Note: In the above "you" means "one" or "everybody".

[kkala]

If my previous post had caused negative feedback to marlindaniel post (newbie), I am sorry for it and do not agree to it personally. My intention (shown in my post) was merely to point out that senior engineers, or even experts, need to learn continuously.
I understand from previous posts that you do not know who sent the negative feedback. This should change in my opinion.

Edited by kkala, 14 March 2010 - 04:28 AM.