2800 ton steam turbine, 134. can it run all winter with low load?

[Nabrxx]

This unit is a new installation, this is the first winter season it will see. My coworkers seem to be hung up on a chilled water sp of 42 and they like their condenser water above 80. When they run this way, the hot gas bypass is open nearly constantly. I come on shift and raise the chilled water sp to 45 and lower the condenser water sp to 70. The machine purrs like a kitten at 30 percent load and an outside air temp of 36. Will I be able to run this unit into the single digit OATs ? Thanks all, this is my first post.

 

[MechEngNCPE]

Better be careful upping the chilled water setpoint like that if it serves any controlled spaces, any high humidity alarms going off?

 

[KiwiMace]

There is nothing wrong with what you are doing as long as it meets the needs of the facility, after all this is what reset is all about. You are probably saving a lot of power too.

Reduced load in a chiller is supposed to be met with colder condenser water - just look at the AHRI 550/590 rating conditions your chiller would have been tested to:
100% Load - 85degF CW
75% Load - 75degF
50% Load - 65degF
25% Load - 65degF

Note that the chiller doesn't care what is happening outside, only what the evap and cond water temperatures are. If you can give the chiller it's expected CW temps at reduced load you should not have a problem supplying the normal chilled water setpoint.

 

[RobsVette]

I assume this is a York YST? We are installing alot of these in the 2800 ton range.

If its a York chiller the answer to your question is "yes"

The reason you can do this on the York chiller is that they use a modulating expansion valve, so the valve can open further to accomodate colder condenser water temperatures. This does 2 things;

You will remove a major amount of head from the compressor and your steam consumption should go way down.

You will also pull a stronger vacuum on the back end of your steam turbine with the colder condernser water. You will get more energy out of the steam by doing this.

If its not a York chiller, just make sure that it has a variable orifice plate and you will be fine.

At a previous installation, we had a 2000 ton york electric chiller running with about 250 tons using 65 degree entering condenser water in the dead of winter. Power consumption was minimal with this arrangement (chiller had a 4160 volt VFD)

Can you share with us where this installation is and what kind of equipment you have?

 

[Nabrxx]

The machine in question is a York MAXE. We are in new York at a 10 million sq ft campus pushing roughly a million gallons of chilled water. There are various levels of tech throughout the system with different advances being simply added to the system. I come from an area of our business ( financial, critical space) where knowledge is king and tracking your energy is simply another part of the job...here half the crew has only a few hundred hours on their licenses and the 30 year vets don give a shit. I am trying not to be a jerk, but it kills me to see the waste at this facility. I'm trying to slowly bring these guys along to run the equipment properly and I just wanted to be sure I wasn't crazy as the disparity between what I believed and what they believed was so large. Thanks for the confirmation here guys...these guys were running 90 deg condenser water to the machine with a chwsp of 42 with a steam consumption of 23000 lbs of steam per hour. After I changed the set points to 67 cw and 45 chw...the steam went down to nearly 11000. We make our own steam here and after some math that steam savings translated to 50 gallons of oil....PER HOUR not being burned...guess what the next guy on shift did? He put the chiller back to the prior setting...obviously there is no informed oversight here with our managers either. Pretty lame set up but it pays the bills and I'm getting my high pressure time. Later guys.

 

[RossABQ]

Put the system on PLC controls that optimize the system for efficiency, and lock out the morons that don't deserve their licenses.