If you have your own or work in a food processing plant, you might know that your refrigeration system accounts for around 30% -70% of electricity bills. What probably you don’t know is that this could go up to 50% more than your need.
Any good news? Yes! Fridge plants from reliable refrigeration equipment suppliers can be optimized. They can significantly save your bills with little capital expenditure.
Know the Problem
Refrigeration equipment is rarely designed, installed, maintained, or operated as it should be to ensure manufacturing demands are met while minimizing energy consumption.
Normally, refrigeration plants are designed to optimally operate for two weeks per year. They are produced to run at 32 degrees Celsius; condensing temperature. The rest of the 10 months are a waste of money.
The issue arises when your contractor or refrigeration equipment manufacturers is called out at 3 a.m. for cooling adjustment at one side and invariably minimizes the suction-pressure on the compressor.
This resolves the initial issue; however, it leaves you with a 10 percent power penalty. The plant might operate at this low level of suction pressure for months before you realize it. In the meantime, all you get is enhancing energy bills and a failure to achieve your energy KPI’s.
Fridge plants; especially two-stage low-temperature plants are quite complex. But with dynamic controls and fine-tuning, savings can be significant.
The following 5-step approach shows you how.
Energy Saver 1 – Know Your Plant
Take your time to observe how your plant works.
• Are the compressors going up and down regularly?
• Is the plant’s slide valve regularly opening and closing
• Are the refrigerator’s compressors continually swapping over?
• Are two compressors running at half capacity i.e. load sharing?
• Are compressors on a short cycle i.e. is one compressor kicking off a couple of times within an hour?
These essential factors can increase the amount of energy drastically of your refrigerator plant.
1. Operate fridge plants on fixed suction pressure
2. Use the control system that optimally sequences compressors i.e. 2nd compressor should only come at 80% load on the lead compressor
3. Use signal (feed forward) from process to turn off and turn on compressors prior to major loads turning on and off
4. Make sure the glycol pumps’ control is not aggravating load fluctuations on your plant. Consider VSD control to alleviate raw on-off control
5. Make sure liquid levels present in surge drums are sufficiently damped and well-controlled
Energy Saver 2 – Discover Your Pressure Point
Refrigeration equipment has to touch cooling loads at different temperatures. However, many factories use the same temperature or suction pressure every time whether the plant needs it or not.
In an environment of a brewery, the plant running on an ammonia or glycol system has to meet the below-mentioned main cooling loads:
• Wort cooling to 14 degrees
• Fermentation vessels at circa 21 degrees
This system will continuously run at (-4) degree glycol and (-7) degree suction temperature despite many breweries brew during the week. While the fermentation load is a mere weekend requirement.
By controlling the system dynamically; the glycol temperature can shoot up through a couple of degrees to meet this load. This saves energy between 10-20% easily, while no extra cost has to be borne by your business!
Energy Saver 3 – Relieve The Strain
As we know that refrigeration plants are installed in a way that the engineer doesn’t receive a callout on the hottest day when your plant can’t make its cooling capacity. Head pressure remains too high for different unnecessary reasons:
• have to get heat into the plant’s hot glycol for defrosting
• have to get heat through to a heat recovery system onto the compressor discharge
Best for production. Should be avoided for energy consumption. However, it doesn’t need to be a compromise.
A head pressing factor can be decreased significantly on most plants, saving a great deal of energy. Decreasing head pressure from 10 bar to 8bar on a smelling salts plant can save 30% in energy. At whatever point conceivable head pressing factor can and ought to be floated down to the minimum level.