PHE and Horizontal Surge Drum

[gwapa]

Dear All
For a Soft Drink planta
This will be a new installation

There will be 8 flooded Amoniac Plate Heat Exchanger (PHE) cooling water to 2ºC

Each PHE have 250 Tr (880 kW) so the installed capacity will be 2000Tr (7040kW)

The plant woud like to install just one surge drum for all PHE (2 m diameter x 5 m long)

The surge Drum will be located at 6 m high over the PHE

The idea is to use just one liquid pipe to feed all PHE(slopped 1%) and one pipe for each PHE to return the two fase ammonia to a main manifold located over the surge drum .
The Manifold will be 1% slopped down to the surge drum

The ammonia make up will come from the tank reciever

The evaporation temperature will be -1ºC


With all this information I appreciate your very kind expirence to adivice any problem that you could preview

Thanks
Gwapa

[RANGER1]

Gwapa,
We normally use PHE as a pre- cooler for majonier type carbonator.

Is that what you are doing?

If flow stops in 1 PHE water will freeze, have you got anything to prevent a freeze up
in this situation?

[gwapa]

Ranger1
Yes They are using amonia in the carbocooler, but the want to elimnate the amonia from the proceses area and locate it in the Room Machineries
So we will use product vs Chill water in carbocooler and the exiting ammonia PHE will be moved to the room machinery to chill water
The room is not to big so they want to use just one separator for all PHE
The freezer point is very good point I think we could have a hot gas line in each PHE and automatic shut off valves
What do you think??
Thanks
Gwapa

[Josip]

Hi, Gwapa

Dear All
For a Soft Drink planta
This will be a new installation

There will be 8 flooded Amoniac Plate Heat Exchanger (PHE) cooling water to 2ºC

Each PHE have 250 Tr (880 kW) so the installed capacity will be 2000Tr (7040kW)

The plant woud like to install just one surge drum for all PHE (2 m diameter x 5 m long)

The surge Drum will be located at 6 m high over the PHE

The idea is to use just one liquid pipe to feed all PHE(slopped 1%) and one pipe for each PHE to return the two fase ammonia to a main manifold located over the surge drum .
The Manifold will be 1% slopped down to the surge drum

The ammonia make up will come from the tank reciever

The evaporation temperature will be -1ºC


With all this information I appreciate your very kind expirence to adivice any problem that you could preview

Thanks
Gwapa

What size is that liquid pipe down to feed all PHEs?

Can you upload a hand drawing with connection of main liquid header to each PHE and return lines connected to main suction header?

Best regards, Josip

[polarpodge]

if you are bringing the water down to -1 i presume there will a gylcol storage tank also your chill water side, the 3 PHEs are they fed off a single primary circulation header or on individual pumpsets.

[RANGER1]

Ranger1
Yes They are using amonia in the carbocooler, but the want to elimnate the amonia from the proceses area and locate it in the Room Machineries
So we will use product vs Chill water in carbocooler and the exiting ammonia PHE will be moved to the room machinery to chill water
The room is not to big so they want to use just one separator for all PHE
The freezer point is very good point I think we could have a hot gas line in each PHE and automatic shut off valves
What do you think??
Thanks
Gwapa

Yes you could do that & instal a normally open solonoid for hot gas.

Have never seen a system on carbo-cooler like this though.

[josei]

...With all this information I appreciate your very kind expirence to adivice any problem that you could preview

Thanks
Gwapa

"The pressure drop that occurs through a plate heat exchanger is relatively high and the pumping system should be considered". What about PD and pumps?

[gwapa]

[Josip][/What size is that liquid pipe down to feed all PHEs?]
We have not select the pipe diameter . I think that it should be selected with a speed of 1 m/s or lower
I do not know upload the drawing

[Josei][ I am think that it will work as a thermosiphon but 8 PHE working with one tank. It will work as the oil cooler of compressors]
gwapa

[Josip]

Hi, gwapa

[Josip][/What size is that liquid pipe down to feed all PHEs?]
We have not select the pipe diameter . I think that it should be selected with a speed of 1 m/s or lower
I do not know upload the drawing

[Josei][ I am think that it will work as a thermosiphon but 8 PHE working with one tank. It will work as the oil cooler of compressors]
gwapa

to upload a drawing (JPG, PDF up to 100Kb) click on attachments (paperclip icon) in the first row ....

hope this will help

Best regards, Josip

[gwapa]

8 PHE.jpg

Josip
The sketch is just the basic idea We have to make some engineering . What do you all could advise?
The suction temperature will be 0,5ºC. We will have 6 m high so the temperature inside each PHE will be a little higher
gwapa

[RANGER1]

Gwapa,
Water at these temps would be very susceptible to instantaneous freezing.
Suggest to use glycol in this circuit.

Why do you need so many PHE?

Could you not have 1 or 2 PHE with a ring main going out to carbocoolers with auto shut off valves,with maybe a mixing 3 way valveto control outgoing temp by bypassing PHE.

[josei]

Gwapa,
Water at these temps would be very susceptible to instantaneous freezing.
Suggest to use glycol in this circuit.

With semi welded PHE no damage will be caused if freezing occur.

[RANGER1]

With semi welded PHE no damage will be caused if freezing occur.

josei,
Loss of production would be a problem though!

[gwapa]

Dear Friends
I am wondering how to control the water temperture
IF you have just one separator tank for each PHE The temperatura water control would be easy
So how would be the water temperature cotrol with just one tank???
appreciate tour comments
GWAPA

[RANGER1]

If you had 1 PHE on surge drum you could use water temp & Back pressure regulator BPR.
In your case it could only be BPR unless some body has a better idea?

[gwapa]

Ranger1
It is not so easy to control 8 PHE with just one BPR
IF you select a BPR for 8x250=2000TR it will be a big valve
But what will happen as long one PHE is working? You will need a very small one
Gwapa

[mad fridgie]

A proportinal hot gas injection valve on each PHE inlet

[mad fridgie]

Just read all posts, SST -1C, water required 0.5C,

Keep the water velocity high, will not freeze.

Presume comp loads and unloads, so worry is speed of unloading, possible freezing and loading if load is very quick.

Install large water buffer to take slack in load times

Install hot gas valve in main suction line, to cover unloading times.

And for added protection large suction valve, (closes if the pot pressure drops below a pre-determined set point)

One presumes you have isolation for service or when a PHE is not in service.

[RANGER1]

Gwapa,
Can you explain why you need so many PHE as well as why water not glycol can be used in this system.
If power failure or pump hicup water mat freeze.

[gwapa]

[RANGER1]Can you explain why you need so many PHE as well as why water not glycol can be used in this system.
If power failure or pump hicup water mat freeze.[/]

As I mentioned before the plant want to get the amoniac rid of production area.
Existen 5 PHE (amomia flooded) in the carbocooler. We are going to replace those with chill water/ product
The PHE existing flooded PHE we will move to thr room machinere to generate the chill water.
Beside that the Soft drink plant produce a lot of other product ,juice,Gatorade etc
They use in the juice pasteurization system chill water too.
For the above facts the plant do not want to use water/propelin glycol solution

Now , in the room machineries there are enought room to install 8 PHE each with its own separation tank. So we thought in use just one tank.

[gwapa]

mad fridgie

SST -1C, water required 0.5C, May be the best SST=0,5ºC water =2ºC

Keep the water velocity high, will not freeze. How much is a high speed?

Presume comp loads and unloads, so worry is speed of unloading, possible freezing and loading if load is very quick.There are a mxture of compresor ,screw and recip

Install large water buffer to take slack in load times OK

Install hot gas valve in main suction line, to cover unloading times. could you go deeper ??

And for added protection large suction valve, (closes if the pot pressure drops below a pre-determined set point)Remember we will have just one pot for all 8 PHE

One presumes you have isolation for service or when a PHE is not in service.[/QUOTE]

[mad fridgie]

mad fridgie

SST -1C, water required 0.5C, May be the best SST=0,5ºC water =2ºC

Keep the water velocity high, will not freeze. How much is a high speed?

Presume comp loads and unloads, so worry is speed of unloading, possible freezing and loading if load is very quick.There are a mxture of compresor ,screw and recip

Install large water buffer to take slack in load times OK

Install hot gas valve in main suction line, to cover unloading times. could you go deeper ??

And for added protection large suction valve, (closes if the pot pressure drops below a pre-determined set point)Remember we will have just one pot for all 8 PHE

One presumes you have isolation for service or when a PHE is not in service.

[/QUOTE]

Water velocity, 2.2m/s, but you take into cosideration the design of the PHE, pump requirements

Hot gas quite simple, hot gas taken after the oil sep system, in then injected into the main suction stream, to ensure that the hole pot pressure does not fall below a predetermined point. by which time the comps should have unloaded (pressume suction driven unloading)

Suction safety, is really that sudden, rapid response. So if the whole pot drops in pressure then all 8 PHE can freeze. Think of it this way, your plant is running 100% capacity, you suddenly loose total water flow to all the PHEs, the plant will not respond quickly enough, even with a hot gas valve to stop freezing, shut the main suction. no freeze. Ok plant goes out on LP, but you have a problem any way.

[Rajkumar]

Make sure the each ammonia Plate heat exchanger should have same pressure drop on liquid as well as wet return circuit.

[josei]

8 PHE.jpgThe sketch is just the basic idea We have to make some engineering . What do you all could advise?.The suction temperature will be 0,5ºC. We will have 6 m high so the temperature inside each PHE will be a little higher.gwapa

gwapa , this kind of systems require some head of liquid above PHE , but 6 m (18 ft) is out of standard of design and operation of a thermosiphon loop . Take a look at attachemnt here that I selected about basic PHE loop from handbook of these systems design and operation. Any add info can contact by PM

[Sandro Baptista]

...you suddenly loose total water flow to all the PHEs, the plant will not respond quickly enough, even with a hot gas valve to stop freezing, shut the main suction. no freeze. Ok plant goes out on LP, but you have a problem any way.[/QUOTE]

Economic solution: install water flow switch if the water flow falls the compressors stop. Even during a while it will be evaporation so you always should run with a evaporating temperature inside the plates of 0ºC, 0,5ºC despite the process water could be a +0,5ºC / +1ºC higher.

To control the water temperature in each evaporator plate you could use in each one an ICS40 or 50, one the feeding liquid line, with a CVT pilot. This pilot measure the the outlet water temperature (more expensive but maybe better it would be you use ICM-motorized with a temperature sensor connect it).
Because you have a big height of liquid (6 m) so no problems about feeding head loss. In fact you shall have attention not to feed excessively (and the ICS due to its head loss will help not to feed to much) because the excess of liquid have to rise again to the tank. If is to much liquid you will have hydrostatic penalties and the evaporating temperature inside the evaporator will rise and have oscillations.

As far I understood you have individual water pump systems grouping one or several plate heat exchanger, right? So for each plate heat exchaner or group of them you can use its ICS+CVT that I mentioned and also mount another pilot the EVM...so it would be an ICS with CVT+EVM pilots. By the way I'm talking about the DANFOSS valves.

Wherever the water flow that feed one of the plate exchanger groups stops (due to the process function) the pilot EVM close the ICS that feed the plate exchanger with R717. The water pumps can continue ON just for a while so ensuring the plate evaporator have no more liquid and so preventing the water inside the plate evaporator freezes (albeit the evaporating temperature is > 0ºC it is just a security manner).

Gwapa,

How is running this project? What did you decided to do about?