controlling liquid supply between reciver>IP>LP pots

[mattmechanic]

Hey all.... while dealing with my other issues I noticed the way my system has been set up is as follows:
liquid receiver greater then 50% dump to IP pot until level reaches 45%
IP Pot greater then 55% dump to LP pot until 45%

now with my very limited ammonia experience this sounds very odd to me as there is no way the IP or LP pots can fill if they are in fact at a low level and require more liquid they must first wait until the pots upstream are satisfied.

if you had a constant load the correct amount of ammonia in the system this would be fine but in a production facility with rapid load changes this set up doesn't seem to work well...

so my question is : is this a standard way of doing things? how do you guys have your plant set up?
or simply did some one get it ass about?

cheers!

[RANGER1]

Hey all.... while dealing with my other issues I noticed the way my system has been set up is as follows:
liquid receiver greater then 50% dump to IP pot until level reaches 45%
IP Pot greater then 55% dump to LP pot until 45%

now with my very limited ammonia experience this sounds very odd to me as there is no way the IP or LP pots can fill if they are in fact at a low level and require more liquid they must first wait until the pots upstream are satisfied.

if you had a constant load the correct amount of ammonia in the system this would be fine but in a production facility with rapid load changes this set up doesn't seem to work well...

so my question is : is this a standard way of doing things? how do you guys have your plant set up?
or simply did some one get it ass about?

cheers!

It's normal for your type of system.
Liquid receiver small but big enough for thermosyphon oil cooling for screws.
Low temp accumulator hold all the excess liquid & is usually quite big.
The system is critically charged to a certain degree, as on your 6 monthly defrost, it also has to have enough capacity in LT accumulator
to hold the liquid pumped out of all the plates.
In some cases it can't hold it, so plate room is raised to approx +10 C with liquid still circulating.
It's a wier or overflow type system & should work trouble free, liquid receiver
& intercooler levels should never be low or starved.

[mattmechanic]

Ranger thanks for your input, however I want to run a floating suction for energy reasons and time of day metering, I cannot do this as when I lift my suction all my liquid sits in the plates as it becomes colder than my LP pot and I have low level alarms...
I would like to be able to feed liquid when required and go away from it needing to be so critically charged if possible?

[RANGER1]

Ranger thanks for your input, however I want to run a floating suction for energy reasons and time of day metering, I cannot do this as when I lift my suction all my liquid sits in the plates as it becomes colder than my LP pot and I have low level alarms...
I would like to be able to feed liquid when required and go away from it needing to be so critically charged if possible?

Matt, you are currently suffering poor product temps, running suction to high as it is, now you want power savings!

Add some ammonia see what happens, minimum amount though.
System SHOULD be able to run with plates full of liquid & pumps run OK
I think you need to get some advice though on your situation.
What's Milmeq say?

Keeping compressors fully loaded, may be VSD on one machine, no air in system, VSD on condenser fans, after that limited in what you can do if plant generally well maintained.

[mattmechanic]

Ranger, product temp issue has been resolved due to a number of issues adding up from lack of maintenance
VSDs are currently being installed on compressors and condenser fans
aswell as a new air/water purger
however I wish to float the suction to match my load and time of day metering

[sterl]

You want to float the LP suction or the intermediate?

I know nothing about your load & duty profiles but if the plant is dominated by those plate freezers you would be better off pursuing flywheeling, banking and load shedding than floating the LP suction. You will never be able to get LT capacity at elevated suction pressure to synchonize with production demand unless the politics and economics there are a whole lot different than the other continents....

Now IP has some opportunities: A eutectic bank is one of them. Even an ice bank will help with the low stage superheat and high stage economize....

[RANGER1]

If all your meat or product is frozen, only then you could float suction.
Usually plates progressively get filled & there is always something that was put in last that requires the -40 suction. If product left in, say over the weekend, maybe float suction then.
Who knows how the place is run!

[Magoo]

As per Ranger1
Floating suction control seems to be the catch phrase from all the energy saver wannabees .
The last plate loaded governs the total cycle. Unless of course you want to compromise quality.
Plates are designed for as fast as possible contact freezing product, full contact hard out freezing to maintain quality, basically snap freezing.
Where is your plant located in Australia, seems to be mid interior Queensland.
magoo

[RANGER1]

Matt,
If you are out there, if you are installing VSD on compressor motor/s are you installing new motor to suit or modifying existing motor/s?
Also have compressors been serviced or overhauled?

[mattmechanic]

well I have the suction floating at the moment and it appears to be working well and saving a bucket load of $$

the existing motors are being modified ranger
cheers

[RANGER1]

well I have the suction floating at the moment and it appears to be working well and saving a bucket load of $$

the existing motors are being modified ranger
cheers

Matt everything else had lack of maintenance,
have you checked out compressors.
Use only Frick oil filters & single staged economiser,
that was using slide valve for control 30000hrs max.
Slide valve guides wear, goodbye tips on rotors.

Be careful mixing oils as well.