Receiver Design

[Budi]

Hi, I am doing final year for chemical engineering and assigned to do a detail design of a receiver. This receiver thing is new to me and I have no idea how to start, then I came across this forum and hoping someone would help me or give me a suggestion how to start.

I guess first thing is, I need to find out how big my receiver will be, but I'm not quite sure how to find it out since my refrigeration cycle was done in HYSYS simulation.

Regards,

Budi

[NoNickName]

A liquid receiver is a simple vessel with two ports.
The inlet receives the broth (oil, refrigerant, foam, ecc) from the condenser and simply pours it into the liquid pool.
The outlet is getting liquid from the bottom of the vessel through a pick up pipe, to ensure liquid only is "fished".

The criteria for designing a receivers are: the safety pressure to which it will be subject, the volume required and the type of connections for inlet and outlet.

[Budi]

I see. Is it more like a vertical or a horizontal vessel? And how do I decide what type of connections and what are the choices available? Do you have any good sources for my references for this design?

Thanks a lot for the reply.

[NoNickName]

Vertical are widely more spread, but horizontal is also possible. For the connections, either welded lap joints or rotalock connections are used. Try with some receiver manufactuer website. Here in Italy frigomec is very common, but Onda is also a known producer.

[Brian_UK]

I see. Is it more like a vertical or a horizontal vessel? And how do I decide what type of connections and what are the choices available? Do you have any good sources for my references for this design?

Thanks a lot for the reply.

Ready made source here...

http://tinyurl.com/3xw4qh4

[Budi]

ok, thanks a lot. I will try to design it. I'll get back here if I'm stuck again. Thanks Brian, that was how I found this site, haha

[Budi]

Hi again. I'm a bit confused about the pressure I'm designing for. In a book, I read that in the receiver, there should be around 50-80% liquid and the rest is in vapour phase..

But at the outlet temperature and pressure of condenser (inlet of receiver), there shouldnt be any vapour forming. Do I specify the design pressure to be lower than it is? or do I design for a higher temperature? My output temperature from condenser is 33C and the plant is in tropical area. Therefore the temperature wont vary a lot thourghout the year.

Thanks

[Magoo]

Hi Budi.
in Australia and NZ, receiver vessels are classified as unfired pressure vessels and designed to BS5500 specification that includes design working temperature limits and design and testing pressure limitations. Any design has to be certified and approved before manufacture, then tested and issued with a design number and approval, then after manufacture tested and crowned, all material and welding procedures, and a mountain of paperwork envolved.

[NoNickName]

The liquid receiver can be almost empty or almost full... it doesn't matter what amount of refrigerant is inside.
Vapour is in equilibrium at the same pressure than liquid. It's called two-phase equilibrium.

[Budi]

Hi guys, now that I have finished the mechanical design for this receiver, I move on to the Piping & Instrumentation Diagram section. I need some advice on how to control the receiver. If i want to control the pressure by using pressure relief valve, or control the level by using a drain, the total refrigerant in my refrigeration system will be less. If i add a buffer tank or something, then the receiver would not serve its purpose right?

I'm trying not too change the refrigerant flow rate as it might affect the downstream process (duty required for other part of the plant)

Thanks for the helps

Regards,
Budi

[NoNickName]

No P&I or regulation required for a refrigerant receiver. You can't even regulate the pressure: it's a vessel.

[shieldcracker]

Budi, I don't know of any Refrigeration system that would control the receiver, there is nothing to control, it is just a storage receptacle for excess refrigerant in the system at a any time.

The refrigerant liquid level changes with time according to the operating condition of the system (ambient temp, refrigeration load, system displacement).That is why you have the receiver because if you have level of liquid refrigerant you can assure a the liquid line is being fed full liquid refrigerant.

The relief valve is just for safety in case the pressure within the receiver rises to a dangerous level. These valves vent to the atmosphere or to a secondary vessel.

Some times a pressure differential valve is installed from the between the compressor discharge and the receiver. This valve opens when the receiver pressure drops thereby pressurizing the receiver to a pressure = condensing pressure -differential pressure. This is done to assure that a minimum delta P will exist at the TXV.

[Budi]

yea, I'm really confused, that is exactly why we put a receiver there as an accumulator tank. I just dont know why my lecturer assigned me to do PID on the condenser before this receiver and this receiver tank.. And the condenser in my assignment is air cooled too.. So, there is really nothing to be controlled I guess.. Maybe I'll draw the piping there. so we dont even need a control valve?
do u think a pressure relief valve would be enough for that tank? I dont think level control or temperature control is necessary

Thanks a lot for the advice

[Brian_UK]

As previously said, you do not control the level in the receiver.

The refrigerant is simply stored there, in various quantities, while the system is running.

The condenser generates the liquid from hot vapour and it passes to the receiver for use later in the cooling process.

Air cooled condenser then perhaps add a fan speed control to stabilise the pressures?

[Budi]

alright, thank you very much for the helps!