Feasibility of sending vapour to a liquid line and vice versa

[enlightenme]

Dear all,

I am doing a project in which we are inter connecting lines by providing hot tappings. There is a total no of 4 flow lines going parrellel to each other.(in the order- 1 gas line and 1 liquid line then 1 gas line and followed by a liquid line) And we are connecting the liquid line to liquid line(LPG) and the Gas Line ( MOGAS) to gas line. But the client has asked us whether a connection between the interconnecting line is possible.(ie interconnecting liquid to liquid line and gas to gas line) Does anyone have any idea regarding this matter. The flow direction can reciprocate. Pls see attachment.

Is this idea feasible.Kindly give a feed back!

Regards

Enlightenme

 

[zdas04]

They are just pipes, of course it is possible to interconnect them.

On the other hand, two phase flow is a tough problem that people try very hard to avoid. A liquid interacts with itself and the flow environment in a reasonably predictable way. Same with a gas. Add the interactions between the liquid and the gas and the combined fluid reaction to flow becomes too complicated to reliably predict. One thing that always happens is that the delivery pressure will be lower (i.e., the parasitic pressure drop will be higher) with two-phase flow than with two (or four) single-phase lines. This may not be a problem in your application, but it often is a major problem. Also, in two single-phase lines the risk of a "slug" of liquid being accelerated by a gas is high and the slug arrival can be exciting.

David

 

[BigInch]

Most equipment deigned for liquid will accept a "slug" of gas, but not much equipment designed for gas will readily accept a slug of liquids.

Slugs of liquids often travel around with large forces, so be careful where and to what you are sending them.

I wouldn't think you would want to make those connections without having some very particular knowledge and specific analysis of the systems ability to do such things.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[DubMac]

Very intriguing and complicated flow profiles to consider indeed.

I would assume compressors moving the gas and pumps moving the fluid?? Would think one of the biggest challenges would be to keep the pressures of each line identical before combination so as to not pump one back into the other.

It may not be practical at all for your situation, but has multiphase pumping been a part of your team's discussion at all?

One of the few truly cutting edge technologies the pumping industry has embarked upon in years. Leistritz and Bornemann are at the forefront I believe. Just wondering.

 

[enlightenme]

Hii all,

We are talking abt interconnecting Mogas( at oper. press 6.4 barg and LPG with oper. press. 19.5 barg.)

We had Design Review yesterday and the client have decided to scrap this interconnection because we told them its not feasible. But I just wanted to know if such a connection can be possible? And what are the risks associated with such a connection?

 

[BigInch]

another... mixing and contamination of one product with another.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[mbt22]

I would normally see MOGAS as being a liquid (motor gasoline = petrol). Not really a two-phase flow problem, but design conditions, contamination and making sure you don't send LPG to a vessel not rated for it.

Matt