11 replies to this topic

[navneet2109]

Hello to all,

 

I am a new process engineer in industr. My company is basically equipment manufacturing and I am the only process engineer here. So thats why needed help. i am working on new project of Lpg storage installation. This include lpg from ship to tank to truck loading.

I have 2 questions right now as follows

 

1) i have gone through some old project in which BARREL PUMP is mentioned. Barrel pump come on what classificaton?? can I use any other pump??

 

2) As on utility portion client told us to use hydraulic valve so that Instrument air will not be needed in utilty..

I dont know what that mean??

 

3) client is asking that insulation of pump suction line is required or not. I told them insulation is not needed because i designed that way. i use the criteria for line sizing of pump suction are:

Velocity: 0.5 - 1.2 m/sec

press drop: less than 0.1 kg/cm2  ( per 100m)

I just wanted to know that am i right here???

 

 some data:

Capacity: 5000MT ( two spherical tank of capacity 2500MT  

pump capacity: 120 m3/hr

location : Nigeria

If any other data required i can give.

 

with regards

Navneet

Edited by navneet2109, 01 June 2016 - 12:54 AM.

[S.AHMAD]

Hi Nav

Normally LPG is stored at ambient temperature under pressure. If that is so then insulation is not required.

 

What important is that the minimum storage level should be sufficient to prevent cavitation. Last but not least, consider water flooding to prevent BLEVE.

 

Hope the above helps.

 

S.ahmad

Edited by S.AHMAD, 03 June 2016 - 08:37 AM.

[navneet2109]

Respted S.Ahmad,

Thank you for your reply. sorry for reply late as i was very very busy in this project because this is my first project in which I am the only process engineer involve. I have to study lots so that i can complete this project efficiently.

 

Your answer is valuable to me.

I have said the same thing to the client that insulation is not required, but still they need it.

there is one more question:

 

LPG is transfer from ship to spherical storage vessel. A portable compressor is required to transfer remaining vapour from ship to vessel.

 

Is their any calculation to know that how much volume of vapor generates in ship after transfer of all liquid??? 

 

I am thinking of using reciprocating compressor so the input required is temp, press, and volume..

 

ship data:-  temp- ambient,   press: 8 -17 kg/cm2g

tank data:-  temp- ambient,   press: 5 -14 kg/cm2g

Edited by navneet2109, 24 June 2016 - 04:53 AM.

[fallah]

 

I have said the same thing to the client that insulation is not required, but still they need it.

 

 

Navneet,

 

If the LPG is stored at ambient temperature, the spherical tank should either be insulated or to be equipped with sunshade...and the outgoing suction line should also be insulated...
 

[navneet2109]

Sir, Naser Fallah

 

How about using of water spray protection over entire surface of sphere????

 

Warm regards 

Navneet

[fallah]

 

How about using of water spray protection over entire surface of sphere????

 

 

Navneet,

 

Water spray system is mostly among mitigation systems; hence it should be used regardless of the sphere either equipped with sun shade or with cold insulation which both are to be considered to adjust operating temperature...

 

[Napo]

Navneet2109,

 

You can review the API Standard 2510: Design and Construction of LPG Installations.

 

Napo.

[navneet2109]

Dear Fallah Sir & Ahmad sir,

 

I have a question again..

 

my spherical LPG storage Design temperature is -42/50 deg C and design pressure is 5 to14 kg/cm2 g.

 

What could be the reason in which LPG temperature reduce to minus level (lets say -25 deg see) while the working temperature is ambient???

I asked to my senior level who told me this design criteria. I asked them too but i was not satisfied by his answer. He told me because of boiling point of propane..

But how temperature reduce to such drastic level while working is ambient.

Please help me

 

Regards 

Navneet

Edited by navneet2109, 29 June 2016 - 05:14 AM.

[fallah]

 

my spherical LPG storage Design temperature is -42/50 deg C and design pressure is 5 to14 kg/cm2 g.

 

What could be the reason in which LPG temperature reduce to minus level (lets say -25 deg see) while the working temperature is ambient???

I asked to my senior level who told me this design criteria. I asked them too but i was not satisfied by his answer. He told me because of boiling point of propane..

But how temperature reduce to such drastic level while working is ambient.

 

 

Navneet,

 

In a pressurized spherical LPG storage tank at ambient temperature, there might be a case within which the pressure in the tank be reduced to atmospheric pressure, say, by inadvertent depressurization hence the corresponding temperature can be reduced to around -42 C for a while before to be in equilibrium with ambient temperature after receiving ambient heat.

Therefore the tank may be subject to -42 C as boiling point of propane at atmospheric pressure then considering this temperature as design temperature of such spherical tank is reasonable...
 

[S.AHMAD]

Dear Nav

 

If you are considering insulation for protection from sun light overheating my suggestion you must consider CUI that is corrosion under insulation. If I remember  correctly there is one special type of paint that has some quality of insulation plus corrosion protection characteristic for corrosion under insulation.

 

Regards

 

S. Ahmad

[S.AHMAD]

http://www.polyguard...resentation.pdf

 

Attached Files

•  CUI Presentation.pdf   2.41MB   58 downloads

[Babu Prasad]

Pls give your operating conditions data of LPG storage and Ship storage . .

 

1) In general most of storage pumps provided with barrel type to eliminate vapor lock as storage condition may vary and generates lot of vapor.

 

2) Hydraulic valve is sufficient if your plant is not equipped with instrument air system to operate control valve

 

3) Insulation of suction line may help to avoid vapor generation to save the pump from vapor lock ( cavitation) alternatively Mr. Ahmed idea about special type of painting is good solution

 

As Mr. Fallah rightly said propane stored at high pressure , if storage get depressurized due to any reason while unloading or flaring , the liquid propane will get vaporize by taking surrounding temperature, in that case your storage vessel temp will drop to the extent of -45 deg C so the vessel must be designed to handle the low temperature to avoid brittleness of metal.

Edited by Babu Prasad, 14 October 2016 - 07:02 PM.