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    Optimization of the refrigeration plants operation



    Years ago one PLC manufacturer wrote in his manual that every experienced operator can tune up their PLC. Not everybody were happy with these PLCs.
    Right now several end users believe that their operators should take couple days energy efficiency courses and they will be able to optimize operation of their refrigeration plants. It would be interesting to hear from end users, contractors, designers, consultants about this issue. Who should optimize operation of the refrigeration plants?



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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Segei
    Right now several end users believe that their operators should take couple days energy efficiency courses and they will be able to optimize operation of their refrigeration plants.
    I had a reply from one end-user that said all of his people took an certified energy manager course and they know what to do to save energy now.

    There is more to a refrigeration system than going to a class for a few days and understanding what to do. This makes as much sense as tuning PLC's!

    Quote Originally Posted by Segei
    Who should optimize operation of the refrigeration plants?
    Someone who understands how they work....

    There are so many people (energy managers) running around trying to reduce head pressure 10 psi and think they have a done a good days work.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    I found that many end users believe that they can save energy. Unfortunately, many people don't realise that this issue is very complicated. It is easy to pick up the low hanging fruits and save 5-10% of energy. However, in energy savings every next step will be harder and harder. I believe that operators can do initial step of energy savings, but they need outside help to continue this process.

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    Re: Optimization of the refrigeration plants operation

    Hi, Segei

    Quote Originally Posted by Segei View Post
    Years ago one PLC manufacturer wrote in his manual that every experienced operator can tune up their PLC. Not everybody were happy with these PLCs.
    Right now several end users believe that their operators should take couple days energy efficiency courses and they will be able to optimize operation of their refrigeration plants. It would be interesting to hear from end users, contractors, designers, consultants about this issue. Who should optimize operation of the refrigeration plants?
    With all my respect to a few or even less operators, the best they can do is to take care and switch off all surplus bulbs to save some energy this is the very first step... good and proved.

    ... again we are coming back to the age of "snake oil" where some "a..hole-energy manager" is selling certified courses, classes lasting a couple of days about energy savings ... it is not bad to educate people, but within few days is not possible to learn that matter .... it is too complicated..


    ... I am still learning how to optimize operation of the refrigeration plant and being in business for three decades (maybe I'm not learning fast enough?)... many times is not possible to save anything due to very poor project design ...

    IMHO ... optimization should start from "idea" to build up refrigeration plant ... engage people knowing what they are doing ...

    Best regards, Josip

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Josip
    ... again we are coming back to the age of "snake oil" where some "a..hole-energy manager" is selling certified courses, classes lasting a couple of days about energy savings ...
    Yes, this is now starting here too. Some people are beginning to think they make a lot of money selling this service. It is the samething done many years ago with energy saving control systems.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    Operators run the plants. They have done that for years. However, there is huge difference between regular operation and efficient operation. I would compare these operations with car driving. Regular operation is driving at steady speed, sometimes stop and drive again. Efficient operation is a car racing. Car(plant) should designed and built for maximum performance. Driver should be qualified to drive this car and win the race.

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    Re: Optimization of the refrigeration plants operation

    Driver should be qualified to drive this car and win the race.
    That's true I agree. Unfortunately, most owners do not know what is required or what it does. They depend on those who have the best sales pitch or those that offer large promises. Neither offer any warranty on benefits delivered.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    I can save you massive amounts of energy in your manufacturing facility..... it's dead easy ...... Turn it all of and don't produce anything

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by HallsEngineer View Post
    I can save you massive amounts of energy in your manufacturing facility..... it's dead easy ...... Turn it all of and don't produce anything
    Surprisingly, I heard this response from cold storage engineering manager. However, it isn't typical response.
    The typical are:
    - I talked to the operators and we are fine. 99.9% of the plants aren't fine.
    - Energy savings are expensive. This is wrong. If you do it right, it is cheap and sometimes is free.
    - Our plant wasn't designed for efficient operation. Wrong. Operation of majority(99.9%) plants can be improved.
    ...........
    Unfortunately many people are closed to new approaches and to new ideas. They prefer to run the plants the same way as 20 years ago. However, the time are changing.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Segei
    They prefer to run the plants the same way as 20 years ago. However, the time are changing.
    Yes, just wait until the Cap & Trade legislation passes for reducing CO2. Then when energy costs go up about 50-100% then you will see people start to take energy conservation seriously.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    I understand Europe already has their own version of cap and trade (licensing of carbon emissions). USA politicians swear they are not going to make the same mistakes... LOL
    Last edited by Gary; 09-06-2009 at 07:41 PM.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Gary
    USA politicians swear they are not going to make the same mistakes...
    yeah, right. You don't believe that do you?
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    In many industries people very concerns about efficiency. They try to use every opportunity to save energy(fuel). Just read that japanese to save fuel will reduce weight of cutlery for their air planes. In refrigeration......We are fine???

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by US Iceman View Post
    yeah, right. You don't believe that do you?
    Not for a heartbeat.

    On the other hand, I am heavily invested in Chinese solar stocks. Just because I hate the rules and the rulemakers doesn't mean I can't play to win.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Segei View Post
    In many industries people very concerns about efficiency. They try to use every opportunity to save energy(fuel). Just read that japanese to save fuel will reduce weight of cutlery for their air planes. In refrigeration......We are fine???
    No we are not, but I think you already knew that didn't you.

    Most industrial refrigeration systems are a huge waste of investment. Most are designed like the same systems in 1950. They use a lot of energy and most people think that is the way they have to be....

    Absolutely horrible.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    It seems we are getting off the subject here. The key word is "optimization". Optimization will generally result in energy reduction, but energy reduction doesn't necessarily result in optimization.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Gary View Post
    It seems we are getting off the subject here. The key word is "optimization". Optimization will generally result in energy reduction, but energy reduction doesn't necessarily result in optimization.
    The way I see this is... Optimization is a method of determining the best performance/most capacity for the lowest operating cost during any condition.

    I think Segei may have some input also.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Gary View Post
    It seems we are getting off the subject here. The key word is "optimization". Optimization will generally result in energy reduction, but energy reduction doesn't necessarily result in optimization.
    For existing plants typically 2 ways to save energy.
    1. Optimize operation of these plants. It means choose the best set points, operating strategies and implement these points and strategies. Very often we don't know the optimum set points and sometimes we don't know how to implement these set points(if we know them). So we need just knowledge of determination and implementation. However, this part of energy savings can give us 70-80% of total energy savings and very often payback is 1-2 months.
    2. VFDs(compressors, condenser fans, evaporator fans). Without optimization VFDs can give us 20-30% of total energy savings.
    Compressor VFDs will help us to recover losses related to part load operation. How great are these losses? If you have poor design and poor operation, a lot of energy can be recovered. Very good payback. If you have good design and good operation, it is nothing to recover. Very long payback....

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    Re: Optimization of the refrigeration plants operation

    It would be good to get some input from end users? Do we have end users in this forum?

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    Re: Optimization of the refrigeration plants operation

    Recently, talked to end user engineering manager. He mentioned that they work with big engineering company to improve efficiency of their plants. I have a question. What is the optimum number of heads to optimize a refrigeration plant? Any ideas.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Segei View Post
    What is the optimum number of heads to optimize a refrigeration plant? Any ideas.
    If none of them have very much experience doing this, who knows how many people it will take. People are fascinated with large engineering companies. All those engineers have to know something...

    I wonder how the end user qualified them to do this investigative study?
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by US Iceman View Post
    If none of them have very much experience doing this, who knows how many people it will take. People are fascinated with large engineering companies. All those engineers have to know something...

    I wonder how the end user qualified them to do this investigative study?
    I found that many good designers have little knowledge about optimization. One experienced engineer said that energy saving PLCs are nice toys for rich companies.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by US Iceman View Post
    If none of them have very much experience doing this, who knows how many people it will take. People are fascinated with large engineering companies. All those engineers have to know something...

    I wonder how the end user qualified them to do this investigative study?
    Unfortunately, I don't see input from end users. Silence is one of several typical responses from these people. Everybody claims that they are interested in energy savings. However, some of them refuse to accept free information others don't want to accept free energy savings... How you can be interested in something but refuse to accept that? This is just beyond my understanding.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Segei
    How you can be interested in something but refuse to accept that?
    Energy saving projects are apparently more psychological than technically feasible. Although it might be a combination of both.

    Some refuse to listen to different ideas if the concept is something they have not heard before. What's worse is when they have tried something new and it did not work. This is usually the result of someone not understanding how refrigeration systems work and balance under varying conditions.

    On the other hand, a lot of people have a huge fear of the unknown. Something like this: If it is such a good idea, what are more people not doing it. Or, "I don't want to be responsible for a bad mistake.

    From a money idea, you have to justify projects on ROI or payback. These are usually very short terms allowed (33-50% or 2-3 years). The other part of this is people need to look at all costs, not just equipment and first costs.

    It is a complicated battle which has to be fought on multiple fronts.

    On top of this, there are new experts running around selling black boxes or magical fixes who do not understand refrigeration systems. Because of this a lot of people are cynical about what is possible and what is not!
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    I fully agree with you, the place where i come from we had the same issue the manager basically would check whats happening in the plant room and if we obeying orders a little later in the day the operators would have temperature problems ? don't run all the compressors..... how stupid.

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    Re: Optimization of the refrigeration plants operation

    Many people are closed to new ideas or to new approaches. They run plants for many years at certain set points and operating strategies. They think that it isn't possible to save energy without huge capital investment. This is wrong. Why don't ask questions? People just try to hide from the problem. However, some people start to ask questions. Energy savings is a new direction in industrial refrigeration. Just a few people can do it properly. Ask questions. Do some tests. This is the way to go.

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    Re: Optimization of the refrigeration plants operation

    Some years back our legislators, in their infinite wisdom, decided they could just simply mandate A/C efficiency levels.

    The easiest way to achieve the efficiency targets was to decrease latent heat removal. It takes energy to remove moisture from the air. Consequently, the mold took over and we got sick buildings in humid areas.

    Saving energy isn't always a good thing.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Gary
    Saving energy isn't always a good thing.
    If I turn this around just a bit, I would add: Trying to save energy which results in unintended consequences is just plain dumb. This is like you example or that of benji. Turning off compressors to save energy is not good either.

    Energy reduction (& associated costs for it) has to be accomplished in a manner which allows the refrigeration system to meet its intended duty with no negative impact.

    One of the major issues is what I call the cookie-cutter syndrome. Everyone wants to use the same approach on any application. These prescriptive approaches are not always helpful and do not produce the anticipated results. Then energy conservation gets a bad name.

    I had a conversation with someone who basically implied if you were not a Certified Energy Manager, you did not understand the problems and were of no use to them.

    BS (large male cow excrement) was almost my reply...
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Gary View Post
    Some years back our legislators, in their infinite wisdom, decided they could just simply mandate A/C efficiency levels.

    The easiest way to achieve the efficiency targets was to decrease latent heat removal. It takes energy to remove moisture from the air. Consequently, the mold took over and we got sick buildings in humid areas.

    Saving energy isn't always a good thing.
    We can find several examples of stupid energy savings. This confirms that this is very complicated issue. Any energy savings should be (can be) done without any compromise to the safety and to the production. Operators can't optimise operation of the plant.One example. Many penthouse evaporator coils don't defrost properly. Bottom of the coils have ice. Instead of understanding this issue, operator installed the heater at the bottom of the coil. Simultaneous defrosting of all coils in this penthouse will solve this issue. Sometimes knowledge and experience can be helpful.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by US Iceman View Post
    If I turn this around just a bit, I would add: Trying to save energy which results in unintended consequences is just plain dumb. This is like you example or that of benji. Turning off compressors to save energy is not good either.

    Energy reduction (& associated costs for it) has to be accomplished in a manner which allows the refrigeration system to meet its intended duty with no negative impact.

    One of the major issues is what I call the cookie-cutter syndrome. Everyone wants to use the same approach on any application. These prescriptive approaches are not always helpful and do not produce the anticipated results. Then energy conservation gets a bad name.

    I had a conversation with someone who basically implied if you were not a Certified Energy Manager, you did not understand the problems and were of no use to them.

    BS (large male cow excrement) was almost my reply...
    I agree that every refrigeration plant should has custom approach. Every plant is unique(in industrial refrigeration) and energy savings approach should be unique as well. Many people believe that hot gas defrosting can't be done at condensing pressure lower than 110psig. This is wrong. Typically I do defrosting at 100psig or lower. You should know how to balance hot gas supply, hot gas condensation and condensate draining. It isn't simple as it may looks. However, it is rewarding. 1psig of lower head pressure can save a few thousand dollars per year. Ask questions and do testing for your plant.
    I'm laughing about about a Certified Energy Manager. This person has no clue how energy saved in industrial refrigeration. These are two sides of energy savings. Electrical and refrigeration. Electricalower factor, VFDs, high efficiency motors and etc. Refrigeration: optimum head pressure, optimum suction pressure, optimum defrosting and etc. Electrical can give just 20-30% of total energy savings, but they require huge capital investments. Refrigeration can dive us 70-80% without huge capital investments. Many people have no idea about refrigeration energy savings.
    Last edited by Segei; 30-06-2009 at 05:19 PM.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Segei
    I'm laughing about about a Certified Energy Manager. This person has no clue how energy saved in industrial refrigeration.
    I know that and you know that, but it is a top secret apparently because no one else knows it!

    Quote Originally Posted by Segei
    Many people have no idea about refrigeration energy savings.
    Ohhh, but they know about float the discharge pressure.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    OK, I'll ring in.

    End Users reach a certain scale where they don't have expertise but every man presnet thinks his job is valuable...So he gives up taking any investigation or chances himself, and hires an expert to tell the boss what he wants to hear.

    I hope I'm the first expert hired. Cause telling the boss after he spent the money that he wasted it only makes him mad..It don't make me any form of hero.

    And thats whats wrong with the optimizing business.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by sterl View Post
    ... telling the boss after he spent the money that he wasted it only makes him mad..It don't make me any form of hero.
    Yeah, it's a perception & trust problem.

    No one likes to be perceived as the bearer of bad news, especially the guy who had the idea.

    And it's difficult to gain someone's trust especially the guy who holds the purse strings for the money.

    Telling someone the idea did not provide the anticipated results after the money is spent is not a way to gain trust or for them to have a healthy perception of you.

    Going into a job after a project has fizzled is a mine field of emotions. More than anything, one of the primary concerns with optimization is for the level of understanding to be elevated so that the owner understand the benefits and how they are achieved. If they understand what you are proposing and the reasons for it it is easier to explain how you anticipate accomplishing the tasks.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by sterl View Post
    OK, I'll ring in.

    End Users reach a certain scale where they don't have expertise but every man presnet thinks his job is valuable...So he gives up taking any investigation or chances himself, and hires an expert to tell the boss what he wants to hear.

    I hope I'm the first expert hired. Cause telling the boss after he spent the money that he wasted it only makes him mad..It don't make me any form of hero.

    And thats whats wrong with the optimizing business.
    If you can improve efficiency of the plant, you can claim that this is result of investment as well as input from consultant. Optimization of refrigeration plant operation can save energy without any investment. To please the boss, energy savings can be shared between investments and consultant. Everybody will be happy. One example. I know that one cold storage have spent $100,000 on sophisticated PLC. However, almost no energy savings have been achieved, because they didn't change set points. A consultant helped them to optimize set points and $50,000 were saved. He can claim that savings were possible, becuase of sophisticated PLC.
    Last edited by Segei; 01-07-2009 at 03:45 AM.

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    Re: Optimization of the refrigeration plants operation

    Gday Guys

    Can't remember if I have posted before, but I have been reading this forum for some time. I have to say, I am impressed with the answers given to many questions. Some really cluey blokes on here. I have used this forum as a resource on a number of occasions.


    Quote Originally Posted by US Iceman View Post
    Yeah, it's a perception & trust problem.

    No one likes to be perceived as the bearer of bad news, especially the guy who had the idea.


    This thread has been interesting reading. Optimisation has been a big part of my work over the past few months and I couldn't agree more US Iceman. Perception and trust.

    I think that part of the problem is that most end users do not understand enough about refrigeration to have the confidence to decide if an energy saving change to the system is worthwhile. Too much reaction of ' don't change anything, then it won't break down'.

    However it would seem that we are in for some big challenges with the advent of the carbon trading scheme etc. Our focus in the past ( feel free to correct me if I'm wrong here) has been more about performance and reliability than energy consumption. I think that a lot of our old ' rules of thumb' are about to go out the window.

    Is anyone here finding end users pushing for energy audits or optimisation requirements as yet ?

    Really interested to know, as I am predicting this will be bigger than our change from the faithfull three ( R12,
    22,502).

    Cheers
    'Pipe Benders ?' 'Never heard of 'em'

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    Re: Optimization of the refrigeration plants operation



    Quote Originally Posted by rooboy
    However it would seem that we are in for some big challenges with the advent of the carbon trading scheme etc. Our focus in the past ( feel free to correct me if I'm wrong here) has been more about performance and reliability than energy consumption. I think that a lot of our old ' rules of thumb' are about to go out the window.
    This might be a fun topic, if you want to start a new thread. I have been thinking about this also...

    What I'm afraid of if this cap & trade legislation gets passed into law is the number of experts who will suddenly appear to provide optimization services.
    If all else fails, ask for help.


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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by rooboy View Post
    Gday Guys

    Can't remember if I have posted before, but I have been reading this forum for some time. I have to say, I am impressed with the answers given to many questions. Some really cluey blokes on here. I have used this forum as a resource on a number of occasions.






    This thread has been interesting reading. Optimisation has been a big part of my work over the past few months and I couldn't agree more US Iceman. Perception and trust.

    I think that part of the problem is that most end users do not understand enough about refrigeration to have the confidence to decide if an energy saving change to the system is worthwhile. Too much reaction of ' don't change anything, then it won't break down'.

    However it would seem that we are in for some big challenges with the advent of the carbon trading scheme etc. Our focus in the past ( feel free to correct me if I'm wrong here) has been more about performance and reliability than energy consumption. I think that a lot of our old ' rules of thumb' are about to go out the window.

    Is anyone here finding end users pushing for energy audits or optimisation requirements as yet ?

    Really interested to know, as I am predicting this will be bigger than our change from the faithfull three ( R12,
    22,502).

    Cheers
    As I mentioned early, I think that many end users are closed to new approaches in energy savings. Many of them believed that nothing can be improved unless huge capital investment. This is wrong. Some of them claim that they had a consultant but he said that plant is fine. As you mentioned Rooboy, that energy savings is new direction in refrigeration and I think that not so many people can do it right. Find the right consultant. Ask questions. Test your plant.
    Regarding to the adjustments. I think these adjustments should be done step by step. Small step won't hurt the plant. If any concerns, reset it back ask somebody how to resolve the issue.

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    Re: Optimization of the refrigeration plants operation

    Ok, so how is this as a step for optimization. I have a new plant that was commissioned in February of this year. We have a spiral freezer that has only been in full service for two months. The freezer has four coils which are set up to defrost (hot gas) one at a time 1 or 2 times per shift each depending on length of shift. Problem: when coil B goes into defrost temp in freezer climbs 6-7C when the other coils defrost there is only 1-2C rise in temp. 6-7C temp increase means the product is not fully frozen so the metal detectors have a fit and reject product like crazy. The coils are run using a 600 hp screw with an economizer, set points are suction 12" Hg and discharge of 120 to 140 psi depending on outdoor weather conditions. To give us time we dropped the suction to 18" Hg so we run the freezer colder so the temp increase won't give us too much trouble. Of course that is not great for efficiency and you have more moisture loss from the product. Now why is that coil troublesome? We look at liquid supply, hot gas supply, backpressure valve etc. all for coil B and can find no problem. The issue? Some sod left the liquid supply line for coil A closed (A and B are top coils, C and D are bottom coils) so when B was in defrost no top coil was doing anything. Also the refrigeration mechanic who set this thing up left two of the suction stop valves 1/2 closed. The final result? The compressor which had been running at about 80% capacity on average is now running at about 65% capacity on average and the dwell time in the freezer is down to 70 minutes from 80. Now there was some question on this thread about end users. I guess as the chief operating engineer of this plant I would be considered an end user so how can I optimize my plant?

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by AmmoniaMike View Post
    Ok, so how is this as a step for optimization. I have a new plant that was commissioned in February of this year. We have a spiral freezer that has only been in full service for two months. The freezer has four coils which are set up to defrost (hot gas) one at a time 1 or 2 times per shift each depending on length of shift. Problem: when coil B goes into defrost temp in freezer climbs 6-7C when the other coils defrost there is only 1-2C rise in temp. 6-7C temp increase means the product is not fully frozen so the metal detectors have a fit and reject product like crazy. The coils are run using a 600 hp screw with an economizer, set points are suction 12" Hg and discharge of 120 to 140 psi depending on outdoor weather conditions. To give us time we dropped the suction to 18" Hg so we run the freezer colder so the temp increase won't give us too much trouble. Of course that is not great for efficiency and you have more moisture loss from the product. Now why is that coil troublesome? We look at liquid supply, hot gas supply, backpressure valve etc. all for coil B and can find no problem. The issue? Some sod left the liquid supply line for coil A closed (A and B are top coils, C and D are bottom coils) so when B was in defrost no top coil was doing anything. Also the refrigeration mechanic who set this thing up left two of the suction stop valves 1/2 closed. The final result? The compressor which had been running at about 80% capacity on average is now running at about 65% capacity on average and the dwell time in the freezer is down to 70 minutes from 80. Now there was some question on this thread about end users. I guess as the chief operating engineer of this plant I would be considered an end user so how can I optimize my plant?
    Regarding to mentioned coil. If you have a problem with cooling, first thing you check frost formation on evap. coils and evap. fans rotation. Most likely this coil had much less frost than other coils.
    Regarding to optimization. We need more information about your plant. Compressors, condensers(how many, models). Suction pressures. Temperatures in refrigerated rooms. Time(hrs) between defrosting. How do you control head pressure(PLC, pressurestats)? What kind of product do you freeze?...

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    Re: Optimization of the refrigeration plants operation

    Describing the entire system in one sitting will be very difficult but it is essentially three systems with one common high pressure side. The three systems are like this:
    Spiral freezer system is run by one RWF II 399 Frick 600 hp compressor set at 12" Hg suction: Glycol and water chiller system is run with a RXF 58 Frick 134 hp compressor set at 24 psig suction: Plant cooling is run using a RXF 68 Frick 165 hp compressor and a RXF 50 Frick 123 hp compressor set at 39 psig.
    The condenser for the complete system is a Frigid Coil/Imeco IDC 1200-2S evaporative condenser. Condensing pressure set by PLC based on relative humidity and temperature. I don't think I can go into the entire system at one go so I will break it down by system.
    The freezer system's compressor is set up as follows:
    suction pressure: 12" Hg
    suction temp (typical) -13F
    suction superheat (typical) 31F
    discharge pressure: between 120 and 160 psig (depending on weather)
    discharge temp (typical) 164F
    Discharge superheat (typical) 89F
    Oil pressure (typical) 114 psig
    oil temp (typical) 113F
    oil cooled by thermosyphon no pump
    compressor capacity (typical) 65%-80% (average about 70%)
    Compressor also hooked up to an economizer whose main duty is to cool liquid in a coil from the +25 recirculating vessel to -14F before going to -45F recirculating vessel. The liquid is pumped from the +25F recirculating vessel. The liquid in the economizer vessel is supplied from the HP receiver and the vapour is taken in by the 600 hp compressor. The suction line from the economizer is also supplied with a cross over 1 1/4" HA4AS, 1 1/2" FLGS set at 40 psig which goes to the suction of the +25F recirculating system (compressors for this side are set at suction of 39 psig).
    The liquid cooled in the economizer then goes to the -45F recirculating vessel. From there it is pumped to the spiral freezer which has 4 of 62 ton capacity coils. The freezer is maintained at -35F. The coils are set to defrost individually in this order A, C, B and D. Time intervals from start up are set at 90, 120, 150 and 180 minutes respectively and 35 minutes between unit defrosts. The defrost cycle is set to 10 minutes pumpdown, 2 minutes soft HG and 15 minutes HG (at 70 psig for the hot gas) and 5 minutes drying. C and D are the bottom two coils and A and B are the top coils. The freezer is an Aerofreeze 185 ton unit set at 4:1 recirculating ratio at -40F ET. This is getting pretty long so I will leave the rest of the system for another day
    As an aside the frost on the coil wasn't noticed by the operators because when freezing hot chicken from the oven the bare metal in the freezer tends to get frosted from all the steam comming off the chicken at the infeed of the freezer so it isn't readily noticable at that end. The real give away was the lack of frost on the suction valve on the roof that had no frost on it at all since the liquid valve was closed to that coil. Everyone was too busy looking at the valve assembly for coil B and no one looked at the other valve assemblies
    The guys were too focused on the problem with temperatures rising when B went into defrost and all assumed the problem was with that coil.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by AmmoniaMike View Post
    Describing the entire system in one sitting will be very difficult but it is essentially three systems with one common high pressure side. The three systems are like this:
    Spiral freezer system is run by one RWF II 399 Frick 600 hp compressor set at 12" Hg suction: Glycol and water chiller system is run with a RXF 58 Frick 134 hp compressor set at 24 psig suction: Plant cooling is run using a RXF 68 Frick 165 hp compressor and a RXF 50 Frick 123 hp compressor set at 39 psig.
    The condenser for the complete system is a Frigid Coil/Imeco IDC 1200-2S evaporative condenser. Condensing pressure set by PLC based on relative humidity and temperature. I don't think I can go into the entire system at one go so I will break it down by system.
    The freezer system's compressor is set up as follows:
    suction pressure: 12" Hg
    suction temp (typical) -13F
    suction superheat (typical) 31F
    discharge pressure: between 120 and 160 psig (depending on weather)
    discharge temp (typical) 164F
    Discharge superheat (typical) 89F
    Oil pressure (typical) 114 psig
    oil temp (typical) 113F
    oil cooled by thermosyphon no pump
    compressor capacity (typical) 65%-80% (average about 70%)
    Compressor also hooked up to an economizer whose main duty is to cool liquid in a coil from the +25 recirculating vessel to -14F before going to -45F recirculating vessel. The liquid is pumped from the +25F recirculating vessel. The liquid in the economizer vessel is supplied from the HP receiver and the vapour is taken in by the 600 hp compressor. The suction line from the economizer is also supplied with a cross over 1 1/4" HA4AS, 1 1/2" FLGS set at 40 psig which goes to the suction of the +25F recirculating system (compressors for this side are set at suction of 39 psig).
    The liquid cooled in the economizer then goes to the -45F recirculating vessel. From there it is pumped to the spiral freezer which has 4 of 62 ton capacity coils. The freezer is maintained at -35F. The coils are set to defrost individually in this order A, C, B and D. Time intervals from start up are set at 90, 120, 150 and 180 minutes respectively and 35 minutes between unit defrosts. The defrost cycle is set to 10 minutes pumpdown, 2 minutes soft HG and 15 minutes HG (at 70 psig for the hot gas) and 5 minutes drying. C and D are the bottom two coils and A and B are the top coils. The freezer is an Aerofreeze 185 ton unit set at 4:1 recirculating ratio at -40F ET. This is getting pretty long so I will leave the rest of the system for another day
    As an aside the frost on the coil wasn't noticed by the operators because when freezing hot chicken from the oven the bare metal in the freezer tends to get frosted from all the steam comming off the chicken at the infeed of the freezer so it isn't readily noticable at that end. The real give away was the lack of frost on the suction valve on the roof that had no frost on it at all since the liquid valve was closed to that coil. Everyone was too busy looking at the valve assembly for coil B and no one looked at the other valve assemblies
    The guys were too focused on the problem with temperatures rising when B went into defrost and all assumed the problem was with that coil.
    It isn't clear for me how economiser hooked up. Does it have level control or it has TXV?
    As far as I understand every coil in spiral freezer defrost every 2 hours. If it is true, you have clear over defrosting. You have 2 coils to freeze the product. One coil on defrost. Second coil(right after defrost) run for 30min to remove the heat of this coil defrost. Typically 90% of defrost heat goes to the freezer and you have to run this coil to remove this heat. Do you have any frost on the coil before defrosting? Probably, very little. That is why you didn't notice the poor operation of one coil.
    What is the settings of your condenser? Minimum allowable head pressure, wet bulb approach...
    By the way chicken should cooled before going to the spiral freezer, otherwise you waste a lot of energy. Do you have full production? Why compressor load just 70%? Do you have any storage room for the frozen chicken?

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    Re: Optimization of the refrigeration plants operation

    Econimizer is set up this way:
    line goes in by pump from +25 recirculating vessel. In economizer this liquid goes into a coil is cooled to -14 then out to -45 recirculating vessel. The economizer is filled to 5% to 15% with HP liquid from HP receiver. The vapour from the vessel is sent to 600 hp compressor at the normal hook up for economizer (part way down screw) also if pressure gets too high in economizer a valve opens up at 40 psig to dump excess vapour into +25 system. The levels in all vessels is controled by solenoid openened and closed by PLC according to need for make up liquid.
    The defrost is set up with a point system. The first coil starts to defrost 90 minutes into production (this coil is closest to infeed and get more frost from chicken) after this coil defrosts there is a 35 minute wait before next one will defrost and so on. The way the point system works is that the lower number coils have less points than the higher number coils so the coil at 90 minutes would start timing down after its defrost. The coil that has the lowest number after the 35 minute wait after a coil defrosts gets to defrost next. The nice thing about using this system is that the coil nearest the infeed (it is set to 90 minutes) gets more defrosts and the coil furthest from the infeed gets the fewest defrosts. In an 8 hour shift the closet coil might get 3 defrosts and the coil furthest from the chicken infeed gets only 1 defrost. The coil next closest to the infeed gets 2 defrosts (it is set at 120) and the others gets 1 or 2 defrosts depending on how long the freezer is on. The system works pretty good. We aren't over defrosting.
    I agree with you that the chicken should be cooled a bit before going in but the system is continuous feed. The last plant I worked at we used Cryojet blowers to cool the chicken a bit before going in. That cut down on a lot of frost caused by steam from hot chicken. I'm working on getting that done here.
    The condenser pressure is set according to outside temperature and relative humidity for energy savings (still haven't had a chance to look at that one very closely). The theory being that on cool days in summer (20C or so) with low humidity the set point is at 120 psig. On a hot humid day (say 35C with 90% relative humidity) the set point goes to 160 psig. To maintain the pressure the condenser works by stages. Stage 1 is one pump on, stage 2 is 2 pumps on, stage 3 2 pump and 1 fan and stage 4 is 2 pump and 2 fan. I suppose we are using a wet bulb approach for determining condensing pressure.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by AmmoniaMike View Post
    Econimizer is set up this way:
    line goes in by pump from +25 recirculating vessel. In economizer this liquid goes into a coil is cooled to -14 then out to -45 recirculating vessel. The economizer is filled to 5% to 15% with HP liquid from HP receiver. The vapour from the vessel is sent to 600 hp compressor at the normal hook up for economizer (part way down screw) also if pressure gets too high in economizer a valve opens up at 40 psig to dump excess vapour into +25 system. The levels in all vessels is controled by solenoid openened and closed by PLC according to need for make up liquid.
    The defrost is set up with a point system. The first coil starts to defrost 90 minutes into production (this coil is closest to infeed and get more frost from chicken) after this coil defrosts there is a 35 minute wait before next one will defrost and so on. The way the point system works is that the lower number coils have less points than the higher number coils so the coil at 90 minutes would start timing down after its defrost. The coil that has the lowest number after the 35 minute wait after a coil defrosts gets to defrost next. The nice thing about using this system is that the coil nearest the infeed (it is set to 90 minutes) gets more defrosts and the coil furthest from the infeed gets the fewest defrosts. In an 8 hour shift the closet coil might get 3 defrosts and the coil furthest from the chicken infeed gets only 1 defrost. The coil next closest to the infeed gets 2 defrosts (it is set at 120) and the others gets 1 or 2 defrosts depending on how long the freezer is on. The system works pretty good. We aren't over defrosting.
    I agree with you that the chicken should be cooled a bit before going in but the system is continuous feed. The last plant I worked at we used Cryojet blowers to cool the chicken a bit before going in. That cut down on a lot of frost caused by steam from hot chicken. I'm working on getting that done here.
    The condenser pressure is set according to outside temperature and relative humidity for energy savings (still haven't had a chance to look at that one very closely). The theory being that on cool days in summer (20C or so) with low humidity the set point is at 120 psig. On a hot humid day (say 35C with 90% relative humidity) the set point goes to 160 psig. To maintain the pressure the condenser works by stages. Stage 1 is one pump on, stage 2 is 2 pumps on, stage 3 2 pump and 1 fan and stage 4 is 2 pump and 2 fan. I suppose we are using a wet bulb approach for determining condensing pressure.
    Many plants work pretty good but not efficient. It is better to see the picture of the coil before defrosting. I still believe that time between defrosts can be doubled and suction pressure can be increased. Do you have holding freezer? Do you have VFDs for compressors, fans? Your main compressor is loaded 70%. It isn't efficient especially with economizer.

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    Re: Optimization of the refrigeration plants operation

    We are looking at the defrost system. At this point the guys start the auto defrost cycling when the freezer is started. I believe we could hold off on starting the defrost till middle of the shift. I am trying to convince the company to do this but their argument is that this is how it is supposed to run. My argument is that if that was the case than why bother having the auto defrost cycle on a seperate start? It is a big waste of energy to start defrosting too early. A picture is a good idea, I will take one of all the coils just before the first coil goes into defrost. A picture could say plenty, good idea and thanks for that.
    We do have a holding freezer, it is in the old section of the plant and that is using R22. I am looking at replacing the R22 system in the old part of the plant but first I have to try and optimize the new NH3 system. It is only a couple of months old and still has some bugs to work out, especially in the DDC programming.
    There is no VFD on any of the compressors only capacity and volume valves for the screw. The freezer blowers are single speed. Converting the compressors to VFDs would be very expensive and since electricity if still fairly cheap in Canada the payback would be too long to be able to sell the bean counters on it. I'm sure when the carbon tax comes into effect one day the cost of electricity will be high enough to convince them to do it but at that point so many people will want it that the cost of converting to VFDs will jump up a lot too

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by AmmoniaMike View Post
    We are looking at the defrost system. At this point the guys start the auto defrost cycling when the freezer is started. I believe we could hold off on starting the defrost till middle of the shift. I am trying to convince the company to do this but their argument is that this is how it is supposed to run. My argument is that if that was the case than why bother having the auto defrost cycle on a seperate start? It is a big waste of energy to start defrosting too early. A picture is a good idea, I will take one of all the coils just before the first coil goes into defrost. A picture could say plenty, good idea and thanks for that.
    We do have a holding freezer, it is in the old section of the plant and that is using R22. I am looking at replacing the R22 system in the old part of the plant but first I have to try and optimize the new NH3 system. It is only a couple of months old and still has some bugs to work out, especially in the DDC programming.
    There is no VFD on any of the compressors only capacity and volume valves for the screw. The freezer blowers are single speed. Converting the compressors to VFDs would be very expensive and since electricity if still fairly cheap in Canada the payback would be too long to be able to sell the bean counters on it. I'm sure when the carbon tax comes into effect one day the cost of electricity will be high enough to convince them to do it but at that point so many people will want it that the cost of converting to VFDs will jump up a lot too
    This is major misconception in refrigeration that only VFDs can save energy. I estimate that VFDs(compressors, evap. fans, cond. fans) can save 20-30% of total energy savings. Optimization of a refrigeration plant operation can save 70-80%. This is just smart efficient operation.

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    Re: Optimization of the refrigeration plants operation

    The thing i found from experience, the weather changes everyday so does you running temps they change with ambient and humidity, so do the same with refrigeration components CONTROLS, VFD'S and so on its only logic dont you guys think so?

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    Re: Optimization of the refrigeration plants operation

    My biggest problem with any kind of consultant is their unwillingness to put their money where their mouth is...
    They're quick to tell you you're going to save 10% on your electricity bill every month, for a small capital outlay of $10000 or $100000...
    OK, sounds good, guarantee that. If we don't save 10% per month you refund us the capital outlay.
    And they disappear like... I dunno... stuff that disappears ;-P

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by subb-zero View Post
    The thing i found from experience, the weather changes everyday so does you running temps they change with ambient and humidity, so do the same with refrigeration components CONTROLS, VFD'S and so on its only logic dont you guys think so?
    When the weather change operating of evaporative condensers will change.Optimum set point should be readjusted. For example. Optimum wet bulb approach is 10degF. During the day wet bulb temp. is 75 degF so optimum head pressure will be 75+10=85degF or 150psig. During the night wet bulb drop to 60F and optimum head pressure will be 60+10=70F or 115psig. Capacity of evaporative condensers should be readjusted.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by RefrigNoob View Post
    My biggest problem with any kind of consultant is their unwillingness to put their money where their mouth is...
    They're quick to tell you you're going to save 10% on your electricity bill every month, for a small capital outlay of $10000 or $100000...
    OK, sounds good, guarantee that. If we don't save 10% per month you refund us the capital outlay.
    And they disappear like... I dunno... stuff that disappears ;-P
    I know that it isn't easy to find a good consultant. Majority of consultants are professional engineers(designers). To save energy they can redesign the refrigeration plant. Typically their suggestions require capital investment.
    I have different approach. Optimization of refrigeration plant operation doesn't require capital investment because it changes operation of existing plant. Right now I do remote tuning up of refrigeration plants. This approach is similar to our forum. People give me information about their plants and I suggest them how to change operation and energy will be saved. Energy can be saved for every refrigeration plant(industrial ammonia refrigeration) around the globe. Initial part of this tuning up is free. However, many people are sceptical to any new approach. It is easier to buy VFDs then try something new. Recently I saw one plant around 2000HP. It has VFDs for compressors, condenser fans, evaporator fans. Probably, they invested around $200,000 for these VFDs. However, this plant operated at 150psig of condensing pressure all year around. Reduction of this pressure to 120psig will save them more than all VFDs.

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    Re: Optimization of the refrigeration plants operation

    Quote Originally Posted by Segei View Post
    I know that it isn't easy to find a good consultant.
    That is so very true

    But it sounds like what you're doing will catch on, and we might even get some people like you here in the 3rd world eventually

    Good luck with your endeavors!

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