Energy savings

You can get "more efficient" motors - efficiency classes IE1, IE2 etc


A VSD drive may be an energy saving as the motor is never exactly matched to the load - so whilst you may want constant volume output from the air chargers, the actual volume you need may well be different to the motor/fan efficiency point which you are controlling with valves or dampers - so even if you are running a few Hz lower on the motor, there will be a saving in energy as you aren't throwing it away across the damper/valve


Is there a use for any recovered heat from the compressors, or means of making any air cooling/drying more efficient.


Basically, it's just a case of following the energy flow through the various conversion processes and grabbing any waste from "efficiency" for re use or another use.


As an example, we've recently been able to show a client big energy savings by changing from high temperature hot water (roughly 20 bar) as the inner charge for tyre moulding, to using super heated nitrogen for the same purpose - basically we heat the nitrogen from a waste stream off the exhausts of the electrical aero turbines. (basically aircraft engines bolted down and burning gas to provide electricity - gas is cheaper to import than electric)


Regards


OMS

i looked at using waste heat, but there isn't much use for it, using it for the furnaces was apparently too complex factoring in how they operate, even on a complete new system


we have cooling towers that just run star delta, I think having those on a VSD could work well, especially since the manufacturer now offers them with new towers. 


I have changed our hot water generators to natural gas at about 1.5p/kWh compared to almost 10p/kWh for electricity. 


I think we spend a lot on compressed air too, 67kW by rating

Focus on the compressed air - it's hugely expensive to produce and even minor leaks cost a lot of money


Look  at the quality you actually need and only condition to that, compressing is expensive and excessive filtering, drying and cooling is even more expensive - even a simple change to lower grade filters shaves off a lot of pascals  - as does a look at the pipework  - if it's crummy, then surface roughness adds a lot more pascals - reduce the pascals and you reduce the watts, and over time you reduce the watt/hours. Don't over dry it if you don't need it, ditto for cooling.


Think about adding some sensible dew point control on the compressor dryers - may add a bigger receiver and get at least part of the compressors running on VFD's rather than sliding valve control, or staging control


VSD's on the cooling towers are an instant saving.


Just keep in mind that making the big initial savings is easy and low cost - it's the last 20% is the hard part that costs real money


Regards


OMS

I know we have plenty of leaks, its hard work keeping on top of them


we don't dry the air, and the only cooler is an air-air heat exchanger on the compressor, no filters either. I keep the compressors serviced and maintained thoroughly. 


I think the cooling towers might be a good start, that wont involve every chuffing department across the globe. just need to find someone to talk to about it, maybe get some metering done first

Metering is always good - you can't manage what you can't measure


Regards


OMS

exactly, just what i keep saying, people guess stuff like this all the time, then when I come out with real measurements, they don't believe me!


my favourite question was 'whats this 3.14 you are using?' Pi, I said 'but why is it 3.14?'


in the end, they just put in their report 'John did some maths'

Well, I guess you can't fix stupid, can you - good luck, just don't underestimate the power of the hard of thinking when they get together  in groups


Regards


OMS

How is your Power Factor?

Be careful if trying to reduce the energy used by cooling towers. Cooling towers are usually installed to get rid of the heat from air conditioning chillers or similar equipment.

Any attempt to reduce energy used by the cooling towers may increase the temperature of the cooling water, and this may increase the energy used by the chillers.

Attempting to reduce the cooling tower consumption from say 25Kw to 20Kw is utterly pointless if the chiller now uses 500Kw instead of 450 Kw.

Except at times of low load or low ambient temperatures, it is generally a paying proposition to achieve the maximum possible air flow through cooling towers.

Before experimenting, meter the energy used by the chillers, as well as that used by tower fans and circulating pumps. Only make alterations if the TOTAL consumption drops.

"maybe get some metering done first " metering and recording thermometers.