Water Chilling

Hi, all:)
I was recently asked to look at a water chilling plant in a Brewery, I have some pictures of the plant. On it is fitted a WRV 321 Howden compressors with a retrofit plate heat-exchanger for cooling the oil. I thought I would post this as it isn't to often you see a rubbered plate as an oil cooler.
I will post again when time permits with the photo. Nice big screw, must be the biggest I have ever seen on water chilling, 3300volt motor fitted, not often seen in these parts.
Regards. Andy.:D

Andy

Can't wait for the pictures! - how do you check the running current on a 33,000v motor?

Hi, Frank:)
How do you check the motor current on a 3.3kv motor? Very carefully I would say. Well it's not as bad as it first appears, the main control panel is adjacent to the screw pack, with a separate high voltage section next to it. This high voltage section has the star delta starters in it and an ampere meter fitted on the panel door, everything is as a 415v system except the starters which are segregated.
Must post those photos, possibly tonight.
Regards. Andy.:)

Hi, Marc:)
even the offers of large quantities of money could not entice me to look into one of thoses starter panels:p
At last I have my photo to post, mostly just shows the oil cooler, which is a big beast, compressor top left and motor top right.
Regards. Andy.:)

Alright Andy
Alfa Laval plate heat exchanger ? if you ever have to strip one Andy make sure the rubber seals are in good nick and clean also it is torqued up to the correct spec!!!
Regards Dave

Rubberized plate? Clearly, Dave knows what you mean, but just what is a rubberized plate exchanger? Are we talking about rubber gaskets between the plates? Also, Andy, looking at the picture... what is the shiny pipe on the upper left?

Hi Dan:)
rubbered plate, yep rubbers keeping the plates sealed and the oil and glycol apart. The big shinny thing is a dairy industry type strainer, to catch the bits in the glycol circulation lines.
Kind Regards. Andy:)

Andy,
I have seen a few plate heat exchangers on screw packages in australia mostly are a welded plate design.
Some are liquid cooled but most are water cooled from the condensers or a cooling tower, but Iv'e never come across one that is cooled using glycol.
I have come across one with rubber gaskets, the heat exchanger was a left over from an upgrade and was slightly oversized but with the water valves throttled it does the job untill someone opens the water valves 100% and the compressor faults in the middle of the night, never during working hours but whats new.

Regarding the 3.3Kv switch gear you rack it out to work on it so its not too bad but the spring drives for the contactors scare the shxt out of you when they pull in
Regards Dave

Hi Quinton:)
the oil is cooled by a glycol solution for frost protection. Glycol/water mix is circulated thru a second coil in the evaporative condenser. Oil coolers are more commonly shell and tube, but always cleanable. Rubbered, semi welded plates are often used on chiller for evaporator, the semi refers to the fact that they wouln't have any rubbers on the refrigerant side, only the process side.
Dave:)
those contactors sure do keep you on your toes, even though the voltage would dictate smaller contactors for the load they are always generously sized.
Regards. Andy:)

Andy,
In Australia we don't have any problems with the water freezing in the evaporative condensers execpt in a couple of areas, but theres not any industrial refrigeration in theses areas.

Hi Quinton:)
not much fun being an anti-freeze salesman in Australia then:D :D
Regards. Andy:)

Andy,
no not much fun at all but then again anti boil is very popular

Hey Andy, Yeah you wanna mind that 3.3kv motor. I've actually worked on chillers with 6.6kv accross the line and when they rack in all hell breaks loes in my shorts. Usually you wanna get high tension guys to check it out with glow sticks which look like 10ft match sticks. as regards your plate exchanger pray you never have to clean it. will take you weeks to put it back together
Regards maco

Heya Andy,

What kind of heat exchanger is that. It looks like an Alfa Laval plate heat exchanger, those little things are extremely efficient!

Hi Industrial Tech :)
yep alfalaval, semi-welded plate, works very well as an oil cooler.
Kind Regards, Andy. :)

Maco :)
6.6 or 3.3 kv, I suppose it is just what tapping is taken off the transfomer, both would be common. What I am finding now is that mostly the votage is stepped down to 415v, where in the past 3.3/6.6 kv was used, must be the lower voltage motors are catching up with effeciencies and that anybody can work on them, without major safety implications.
Kind Regards. Andy. :D

Hey Andy :)
Yeah your right alot of motors are now downsized on voltage now for safety but also VSD drives are becoming more popular on industrial chillers. A VSD will only work of a 415v supply. These drives are unbelieveably efficient. I have one customes with three 800 ton machines with vsd drives and when they are running at full capicity the machine is the same as a 55 kw motor. It is costing the customer more to run his chilled water pumps than it is to run his machine
Regards Maco

Quote:

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Originally Posted by maco

Hey Andy :)
A VSD will only work of a 415v supply. These drives are unbelieveably efficient. I have one customes with three 800 ton machines with vsd drives and when they are running at full capicity the machine is the same as a 55 kw motor. It is costing the customer more to run his chilled water pumps than it is to run his machine
Regards Maco

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I think as we say in Ireland you have hit the nail on the head. We have just sold a job, 1500kW -3 deg C glycol, with inverter driven compressors (240kW absorbed). The inverters are fitted to ensure proper/quick temperature control and high part load COP. The glycol system has no secondary pumps, purely to save on the enormous costs associated with the extra pumps used in a traditional system. The glycol system is a 10" n.b ring main with one running pump, this pump supplies the ring main in series with the evaporator, dramatically cuting down on pmp power and pumping losses :)
Our next goal with this customer on an other site is to reduce the pumping cost agian by using volitile CO2 instead of glycol, CO2 pipe sizes and pump drive motors are much smaller.
Kind Regards. Andy :)

Hi :)
there is ofcourse two compressor and again for the higher COP, reciprocating compressors have been used. The higher recip COP is partially a better selection match at full load and the fact that they do not lose much effeciency when under part load, along with the fact that they are not over compressing during low head operations as a screw compressor would be.
Regards. Andy :D