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View Subscription Details: Letter ( 10/09/2007 ) - HTML Format

Remote tuning up

Initial visit of a consultant to the refrigeration plant is the starting point of many energy efficiency projects. Out of province (state) visit can cost $ 2,000 to $ 5,000 to end user. Some consultants require several follow up visits.

I found that the majority (80% - 90%) of energy can be saved without visiting a refrigeration plant. Tuning up of the plant can be done by a consultant based on the information provided by the end user. This approach does not require any upfront investment. Chief engineer (supervisor) and consultant are two major players in this tuning up. Step by step improvement of set points and operating strategies can be done for the majority of refrigeration plants without any compromise to safety and production. I believe that tuning up of a refrigeration plant is the best way to save energy.

Example. Refrigeration plant operates at condensing pressure 150 psig. End user decided to optimize set points and save energy. The following steps were done:

1. Chief engineer contacted a consultant.

2. Consultant sent a simplified questionnaire to chief engineer.

3. Chief engineer filled up the questionnaire and sent it back to consultant.

4. Consultant reviewed this questionnaire and found that optimum set point of head pressure for this refrigeration plant at current outside conditions was 120 psig.

5. Consultant recommended to chief engineer to lower head pressure set point to 140 psig and suggested monitoring hot gas defrosting and liquid make up to intermediate pressure receiver.

6. Head pressure set point has been changed to 140 psig and operation of refrigeration plant was monitored for several days. Plant worked well. No adjustment required.

7. Consultant suggested reducing set point to 130 psig.

8. Chief engineer changed set point to 130 psig and found that the bottom of evaporator coils did not defrost properly. This factor will not reduce capacity of the coils, but this is the first sign of underdefrosting.

9. Consultant gave advice to chief engineer about adjustment of hot gas defrosting. Adjustment was done. Coils defrosted properly. Operation of refrigeration plant monitored for several days. Plant worked well.

10. Set point changed to 120 psig. No problem with hot gas defrosting, but liquid make up to intermediate receiver should be adjusted. Consultant advised the chief engineer about liquid make up adjustment. Adjustment was done. Operation of refrigeration plant was monitored for several days. Plant worked well.

11. This plant currently operates at optimum head pressure. For future operation consultant advises to chief engineer about optimum set points at different ambient conditions.

Similar approach to tuning up can be done for optimization of suction pressure, hot gas defrosting, condenser sequence, compressor sequence and etc.

I believe that the majority of refrigeration plants in North America can be tuned up by using this approach. Certainly, chief engineer and consultant should work as a team to get maximum energy savings.

I think that global warming is serious threat to our planet. Everybody who is concerned about this issue should participate in an effort to stop this warming. To contribute to this effort, I am starting a campaign of free initial tuning up of refrigeration plants for subscribers to this newsletter. Typically, this step will save 20%-30% of total possible energy savings or in the rage of $10,000-$40,000 annually.

Currently, I have more than 300 subscribers to this newsletter. I will try my best to help everybody. However, the number of the refrigeration plants per company, for free initial tuning up, can be limited. Everybody who is interested in this tuning up, please contact me. 


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