Water Chilling

[Industrial tech]

Heya Andy,

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

[Andy]

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

[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.

[maco]

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

[Andy]

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

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

[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