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    Two process refrigeration systems working together and load control?

    Hello,
    We are planning to install a second refrigeration plant. It will work with the other one, sharing the same vapor, liquid and hot gas lines. It is a propane refrigerant system. Has anyone worked or is working on a similar system? What are some of the things to note? I can not find much info
    through process books. The part I'm trying to work through is the controls. One system is three centrifugal compressors the other system will be two screw 1600 hp. They'll be two hundred meters apart, with the chilling trains between. The new system will have all the vessels and condensers of its own. So far as control, on suction pressure or one base load and the other swing. Caution or question, is receiver levels balance? There is no hot gas BP around the CW condenser, or will be. On thing I have found out is our new receiver pressure will be 1300-1400 kPag (winter-summer).
    For simplicity I only put down two chillers. The duty in the existing system is 4500KW @-15, which does fluctuate in the summer and winter. The new addition it will
    change to 10000KW @-25.
    Thank you,
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    Re: Two process refrigeration systems working together and load control?

    Richard,
    Looks interesting, just a few questions & comments to clarify to start things off.


    1/You have a S&T condenser on one & air cooler on the other, so discharge lines probably should no be commoned up, others may disagree.
    2/economiser suction pressure from each system will vary because different type of compressor with different pressures, so probably also keep separate. If not pressure regulator on each economiser port of each compressor, as well as non return valves.
    This would also affect pump discharge pressures if not common economiser suction.
    3/ question how do pumps work, as pumping refrigerant out to chiller, do they have their own level control, or is it liquid overfeed returning liquid/vapour back to economiser?

    Liquid receiver levels could be controlled by having level sensor/probe on each.
    Common up liquid feed lineto economisers, each having non return valve & solenoid.
    If one liquid receiver level reaches upper limit set off level sensor, then it would have preferential feed over lower level liquid receiver.
    Or if level in receiver to low it would feed from other receiver.
    Correct charge of refrigerant important, as well if chiller/s to be turned off for whatever reason liquid would end up in liquid receivers, meaning liquid receivers have to be big enough to hold any excess.
    Control valves or solenoid valves would operate accordingly to maintain level in economisers.

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    Re: Two process refrigeration systems working together and load control?

    Hi, RichardB777

    welcome to RE forums ... maybe you can tell us a little more about yourself, later ... here .. http://www.refrigeration-engineer.co...p?72-New-to-RE

    Quote Originally Posted by RichardB777 View Post
    Hello,
    We are planning to install a second refrigeration plant. It will work with the other one, sharing the same vapor, liquid and hot gas lines. It is a propane refrigerant system. Has anyone worked or is working on a similar system? What are some of the things to note? I can not find much info
    through process books. The part I'm trying to work through is the controls. One system is three centrifugal compressors the other system will be two screw 1600 hp. They'll be two hundred meters apart, with the chilling trains between. The new system will have all the vessels and condensers of its own. So far as control, on suction pressure or one base load and the other swing. Caution or question, is receiver levels balance? There is no hot gas BP around the CW condenser, or will be. On thing I have found out is our new receiver pressure will be 1300-1400 kPag (winter-summer).
    For simplicity I only put down two chillers. The duty in the existing system is 4500KW @-15, which does fluctuate in the summer and winter. The new addition it will
    change to 10000KW @-25.
    Thank you,
    very interesting project ... definitely not simple to solve...

    I am working for many years with similar systems, but all of them are custom made and unfortunately you cannot find a lot of info on the WWW ... With all my respect, what I saw many times are copy&paste projects with the same mistakes from day one ... this is refrigeration plant within petrochemical plant and approach must be from refrigeration point with best possible COP...

    I must admit I am a little bit lost between your numbers ... OK, English is not my mother tongue and maybe within translation something is lost ... anyhow, i believe you can put some light on the "gray" zones ...

    Your existing system is about 4,5MW working @-15*C (1,91barg)...
    new system will change all to total of 10MW !?!, but second system will work @-25*C (1,03barg) that means you are planing to install two (2) screw compressors (I suppose) each with electric motor of 1600 hp (1190kW)...

    I am not sure how you plan to connect two refrigeration systems with different suction pressures to the same chiller trains (maybe I misunderstood something?) ... you can install back pressure valves, but that is not easy to control ... you have two control loops (loop within loop) and then that became a problem ...

    What type of economizer you are planning to use (probably open flash - because you have refrigerant recirculation pumps) ... probably better will be S&T type economizer ...

    In general regulation of refrigeration system is the best with refrigerant pressure ... temperature signal is too slow ...

    I do not understand your question regarding receiver levels? You can level them with pumps and check valves, but with lot of level controls and of course lot of problems...

    What type of oil cooler you are going to use?
    What type of refrigerant condensers you are going to use ... air, water or EC?

    I believe you can give us answers in a simple way ... without your good description we are blind.

    Sorry, about so many questions, but to be able to give some suggestion i.e. help we need to know "idea" of your system quite good.

    Best regards, Josip

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    Re: Two process refrigeration systems working together and load control?

    Thank you for you input gents, here are some answers to you questions.

    Unit One (Existing)
    System is about 4,5MW working @set-point of -15C hydrocarbon dew-point (recovery)
    The condenser is a water cooled S&T directed to its own receiver.
    The economizer is a flash gas sep, vapors off to the inter-stage scrubber before going back to compression.
    We are adding the three pumps on the liquid line to the chillers, each having its own temp & level control valve. The addition of the pumps are part of the upgrade.
    The receiver is designed to hold must of the charge of the system.

    Unit Two (upgrade)
    Will increase our system combined to 10MW @ set-point of -25C hydrocarbon dew-point
    (Improved recovery)
    Two (2) screw compressors 1600 hp each with engine driver 1680 hp, the KW duty varies.
    In short in winter 2330KW to summer 1825KW for each compressor, summer a higher Evaporator temp & pressure.
    The economizer will be a flash gas type with vapors PC to inter-stage on the screw compressors. Three pumps on the liquid line to the chillers.
    The condensers will be air aerial, two fans VFD controlled on each one. They are tied together so discharge gas flow through either.
    The receiver is designed to take most of the charge.
    The oil cooling for the compressors is supplied be CLO/CLOW Plate & Frame Cooler with glycol coolant, with a three way thermostatic control valve for each comp.

    The piping lines that will be shared between the two units, vapor suction, liquid propane supply and hot gas vapor supply.

    We do run our compressors (unit one) on suction pressure control and monitor discharge flow. With the addition of two more it should be the same? The only thing we run on temperature control is the chillers, temp set-point CAS to level valve.

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    Re: Two process refrigeration systems working together and load control?

    Hi, RichardB777

    so the project is solved i.e. designed ... thanks for your explanation ....

    Quote Originally Posted by RichardB777 View Post
    Thank you for you input gents, here are some answers to you questions.

    Unit One (Existing)
    System is about 4,5MW working @set-point of -15C hydrocarbon dew-point (recovery)
    The condenser is a water cooled S&T directed to its own receiver.
    The economizer is a flash gas sep, vapors off to the inter-stage scrubber before going back to compression.
    We are adding the three pumps on the liquid line to the chillers, each having its own temp & level control valve. The addition of the pumps are part of the upgrade.
    The receiver is designed to hold must of the charge of the system.

    Unit Two (upgrade)
    Will increase our system combined to 10MW @ set-point of -25C hydrocarbon dew-point
    (Improved recovery)
    Two (2) screw compressors 1600 hp each with engine driver 1680 hp, the KW duty varies.
    In short in winter 2330KW to summer 1825KW for each compressor, summer a higher Evaporator temp & pressure.
    The economizer will be a flash gas type with vapors PC to inter-stage on the screw compressors. Three pumps on the liquid line to the chillers.
    The condensers will be air aerial, two fans VFD controlled on each one. They are tied together so discharge gas flow through either.
    The receiver is designed to take most of the charge.
    The oil cooling for the compressors is supplied be CLO/CLOW Plate & Frame Cooler with glycol coolant, with a three way thermostatic control valve for each comp.

    The piping lines that will be shared between the two units, vapor suction, liquid propane supply and hot gas vapor supply.

    We do run our compressors (unit one) on suction pressure control and monitor discharge flow. With the addition of two more it should be the same? The only thing we run on temperature control is the chillers, temp set-point CAS to level valve.
    I have some suggestion i.e. my approaching ...
    (to be clear all about .. I am not the brightest bulb in the box, but I saw too many mistakes )
    .... anyhow ...

    1. Installation of S&T economizer without refrigerant feeding pumps to chillers ... HP sub-cooled liquid within pipes and LP liquid&gas within shell ... no problem with pumps, shaft seals, electric motors ... make your life simple i.e. trouble free ...

    2. Condensers should be piped in parallel with common liquid outlet to receiver - take care about balance lines (you are in Canada and maybe is not bad idea to use louvers to reduce air flow during winter time ... VFD fans cannot run below 10-15Hz motor itself can overheat, bad lubrication of bearings ....

    3. Receiver would be big enough to collect almost all refrigerant charge.

    4. Compressor oil cooling will be the best to do by gravity with propane (need to recalculate the size of condenser to remove heat of oil coolers)... of course you can make it with glycol in case of heat recovery !?! ... PHE with 3-way thermostatic valve for each compressor ... no electronic temperature regulators ... for this you need to construct receiver with two outlets at different levels ... lower one for oil cooling ... and higher one for economizer&chillers

    5. Of course capacity regulation of screw compressor is much easier then centrifugal compressor ....

    6. I do not know about your production and requirements, but my approach will be with 3 compressors in parallel ... two running and one stand -by ... but wit PLC control you can run all of them by working hours ... of course with condenser only for two ...

    ... Still there is question how you are going to split suction pressure ... physically separate systems or with back pressure valve?

    All above is something like "thinking out loud" ... and lot of things are not visible, but definitely you new system can be designed and executed in a simple and economical way...


    Best regards, Josip

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    Re: Two process refrigeration systems working together and load control?

    Richard,
    Thanks for new information.

    You mention common lines for suction, discharge & liquid.
    Does it necessarily mean these lines will all be open & commoned up, or there for versatility etc.

    The existing system drive motors for compressors, are they sized for much higher discharge pressure if you run common discharge with new system.
    These compressors would also be derated if you do.

    If condensers common, particular attention to pipework due to different pressure drops through each heat exchanger, "p" or "s" traps with correct heights



    As Josip mentions common suctions at different pressures `15 & -25 deg C, how does that work?


    http://www.evapco.com/sites/evapco.c...brochure_2.pdf
    Last edited by RANGER1; 11-01-2017 at 08:39 PM.

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    Re: Two process refrigeration systems working together and load control?

    Hi,
    2. Condensers should be piped in parallel with common liquid outlet to receiver - take care about balance lines (you are in Canada and maybe is not bad idea to use louvers to reduce air flow during winter time. Yes in Canada, both screw comp discharge into a common line the flow T's to either condenser. The use louvers is a must here, top and sides.

    Receiver would be big enough to collect almost all refrigerant charge. What we can not store in the receiver, we can valve to sales gas compressor and sell. Better than flaring off.

    Compressor oil cooling. Glycol circulation is what they want? (Design Engineer)

    Production and requirements. Two in unit one and the two screw running full time.

    PLC control you can run all of them, I hope so lol, thats what I am trying to research.

    Split suction pressure ... physically separate systems or with back pressure valve? No splitting of lines or BP valves. That is one of my concerns is control. Unit one is run on suction pressure, then we will add Unit two, 200 meter away. (second PT and run off differential pressure?)

    Existing system drive motors for compressors. No, unit one has its own condensers and receiver. Yes the two unit receivers will be at different pressures.

    15 & -25 deg C, how does that work? We process natural gas so we chill it through kettle style chillers C3 shell and gas tube. The temperature -15 chills the gas to drop out the C3+ hydrocarbons and free water (glycol injection). The colder the temp -25 the more C3+ which improves recovery = money.

    Thank you for the info on condensers. We are starting this project next month, but no-one as any info on a control strategy. From what I have researched I can not find an operation in service similar. So I am trying to learn, instead of being fed how it will run.


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    Re: Two process refrigeration systems working together and load control?

    Hi, Richard

    Quote Originally Posted by RichardB777 View Post
    Hi,
    2. Condensers should be piped in parallel with common liquid outlet to receiver - take care about balance lines (you are in Canada and maybe is not bad idea to use louvers to reduce air flow during winter time. Yes in Canada, both screw comp discharge into a common line the flow T's to either condenser. The use louvers is a must here, top and sides.

    Receiver would be big enough to collect almost all refrigerant charge. What we can not store in the receiver, we can valve to sales gas compressor and sell. Better than flaring off.
    Agree with you ... it is simple to use truck tankers to sell propane.

    Quote Originally Posted by RichardB777 View Post

    Compressor oil cooling. Glycol circulation is what they want? (Design Engineer)
    To design oil cooling with gravity feeding refrigerant is not simple (but most trouble free) and probably designer is not sure how to design it ... simple way is to use pumps for forced glycol flow ... what is OK but more expensive with more troubles in the future ...

    Quote Originally Posted by RichardB777 View Post

    Production and requirements. Two in unit one and the two screw running full time.
    Within "unit one-centrifugal" you have a spare compressor i.e. running 2 of 3...
    Within "unit two-screws" you will run two of two compressors, what about normal maintenance time ... you want to improve your production with lower suction point (-25*C) to get more gas i.e. income and now one compressor is off for maintenance - and your production is at 50% ... I am ...

    Quote Originally Posted by RichardB777 View Post

    PLC control you can run all of them, I hope so lol, thats what I am trying to research.

    The best is to use compressor controller designed for your compressor (which screws are you going to install?) and then use PLC - SCADA to monitor complete system...

    Quote Originally Posted by RichardB777 View Post

    Split suction pressure ... physically separate systems or with back pressure valve? No splitting of lines or BP valves. That is one of my concerns is control. Unit one is run on suction pressure, then we will add Unit two, 200 meter away. (second PT and run off differential pressure?)
    I am afraid this is not going to work ... why? ...recently we installed similar propane refrigeration plant with 3 screws (running 2 of 3) 3rd one is stand-by unit with S&T economizer ... system is working with 3 HE in parallel connection with different evaporating-suction pressure ...

    those are design values ...

    1. HE evaporating temp 3,5*C (4,28barg) duty 500kW (with BP regulating valve)
    2. HE evaporating temp -25,0*C (1,03barg) duty 1100kW
    3. HE evaporating temp 3,5*C (4,28barg) duty 2000kw (with BP regulating valve)

    finally suction pressure remain at 1,1 barg and suction temp about -8*C ... client is satisfied because system was performing good in conjunction with the complete system ...


    Quote Originally Posted by RichardB777 View Post
    Existing system drive motors for compressors. No, unit one has its own condensers and receiver. Yes the two unit receivers will be at different pressures.

    15 & -25 deg C, how does that work? We process natural gas so we chill it through kettle style chillers C3 shell and gas tube. The temperature -15 chills the gas to drop out the C3+ hydrocarbons and free water (glycol injection). The colder the temp -25 the more C3+ which improves recovery = money.
    So, according to above, without splitting systems physically or without BP regulating valve it is not possible to maintain any of designed suction pressure ... I believe it will be somewhere in the middle .. i.e. -20*C or much higher in the moment when one compressor drops out - this is another problem with capacity control of centrifugal compressors what is more complex then with screws i.e. positive displacement compressors ... so changing both suction pressure (for unit one and for unit two) you change complete philosophy and working points ...

    I am in this job for almost 3 decades+ (and for sure I did not see all and still learning), but I never saw refrigeration plant running centrifugal compressors in parallel with screws ...

    Quote Originally Posted by RichardB777 View Post

    Thank you for the info on condensers. We are starting this project next month, but no-one as any info on a control strategy. From what I have researched I can not find an operation in service similar. So I am trying to learn, instead of being fed how it will run.

    We are here, trying to help whenever is possible, and whenever you are in doubt you can start with discussion ... there are no stupid questions ... answers can be


    Best regards, Josip
    Last edited by Josip; 23-01-2017 at 06:51 PM. Reason: change pressure for 1. HE

    It's impossible to make anything foolproof because fools are so ingenious...

    Don't ever underestimate the power of stupid people when they are in large groups.

    Please, don't teach me how to be stupid....
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    Re: Two process refrigeration systems working together and load control?

    Richard,
    The only way system is going to run as you describe is new suction set point of -25 deg C & with common discharge, all condensing pressures the same as well.
    As I suggested check drive motors have enough horsepower to run at new condition, as maybe was designed for lower condensing pressure.
    Also assume you are using Frick compressor with variable Vi control to suit new conditions.
    Can only suggest common liquid line with non return valve from each liquid receiver & control valve in each maintaining level balance.
    Each economiser vessel still would have is own level control makeup valve. Also consider any liquid locking between control valves, relief valves etc.
    If one receiver reaches an upper limit then liquid supply is shut off on other & it takes over to feed both economisers.
    Same if liquid level low in one receiver, it closes & other takes over as long as it has above minimum level.
    If If both receiver have an upper limit etc also alarm to show something is wrong.
    Liquid supply from pumps would have to separated, as economiser levels would be out of control.
    Liquid pumps could also be used as would have to try to deliver equal amount of liquid to avoid out of balance scenario.

    Economiser lines would have to have back pressure regulator as when machines unloaded economiser can go to suction pressure.
    Just my basic spin on things, realise it will be more complicated than that.
    Last edited by RANGER1; 12-01-2017 at 08:34 PM.

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    Re: Two process refrigeration systems working together and load control?

    Yes it is. Thank you for your input.

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    Re: Two process refrigeration systems working together and load control?

    Hi Josip,

    Thoughts;
    existing and new compressors receive propane vapours from a common header, where pressure is controlled within a normal range solely by the new compressorís suction pressure override control. The existing compressors will be maintained at full output capacity by means of an operator-controlled output setting, while the new compressor output will be modulated based on maintaining level in the accumulator vessel.

    Liquid level within the existing accumulator vessel will be maintained at an operator-selected setpoint by adjusting recycle valve position and propane pump speed. Liquid level within the new accumulator vessel will be maintained within a specified normal range by adjusting the new compressors output.

    Variations in chiller demand will be compensated for by adjustment of the new compressor package recycle valve and propane supply pumps as the immediate response to changes in supply line pressure. This will result in rising or falling accumulator liquid level and consequently adjustment of the new compressors output based on maintaining the accumulator level within the normal range as the secondary response

    Both the existing and new compressors receive propane vapours from a common header, where pressure is controlled by the new unitís suction pressure override control. The existing compressors will be maintained at full output capacity, while the new compressor will adjust output based on maintaining level in the accumulator vessel. If an imbalance of propane occurs where the existing accumulator vessel takes in more propane, this will be compensated for by the propane supply pumps. Conversely if an imbalance occurs where the new accumulator liquid level rises, this will be compensated for by the new compressor output.
    Existing compressors hot gas bypass control will be removed from the logic to allow suction header pressure to be controlled solely by the new compressors

    Liquid propane at different temps being mixed together in piping. Vapor break out??

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    Re: Two process refrigeration systems working together and load control?

    Quote Originally Posted by RichardB777 View Post
    Hi Josip,

    Thoughts;
    existing and new compressors receive propane vapours from a common header, where pressure is controlled within a normal range solely by the new compressorís suction pressure override control. The existing compressors will be maintained at full output capacity by means of an operator-controlled output setting, while the new compressor output will be modulated based also on operator control suction pressure set point & maintaining level in the accumulator vessel as secondary response.

    Liquid level within the existing accumulator vessel will be maintained at an operator-selected setpoint by adjusting recycle valve position and propane pump speed. Liquid level within the new accumulator vessel will be maintained within a specified normal suction pressure range by adjusting the new compressors output.

    Variations in chiller demand will be compensated for by adjustment of the new compressor package recycle valve and propane supply pumps as the immediate response to changes in supply line pressure. This will result in rising or falling accumulator liquid level and consequently adjustment of the new compressors output based on maintaining the accumulator level within the normal range as the secondary response

    Both the existing and new compressors receive propane vapours from a common header, where pressure is controlled by the new unitís suction pressure override control. The existing compressors will be maintained at full output capacity, while the new compressor will adjust output based on maintaining inlet pressure & level in the accumulator vessel. If an imbalance of propane occurs where the existing accumulator vessel takes in more propane, this will be compensated for by the propane supply pumps. Conversely if an imbalance occurs where the new accumulator liquid level rises, this will be compensated for by the new compressor output.
    Existing compressors hot gas bypass control will be removed from the logic to allow suction header pressure to be controlled solely by the new compressors

    Liquid propane at different temps being mixed together in piping. Vapor break out??
    Richard, to balance levels in liquid receivers, what is method for controlling propane pumps?
    Would they not run all the time, or on demand?
    Both systems have common propane pump discharge line don"t they?

    We have different ways of explaining things, but level control is separate to suction pressure control.
    Compressor output, or suction pressure set point is driven by chiller load & load from liquid level make up to accumulators.

    On new compressors do you have a lead/lag, or how do you control ourput/s

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    Re: Two process refrigeration systems working together and load control?

    Hi, Richard ...

    I am trying to give you some thoughts, but ... seems you are going to change some piping and probably valves within your old&new plant ... as I am an engineer and not a lawyer, it will be nice to upload some hand made scheme of your new plant where will be visible all changes ... in this way without drawing-scheme we can misinterpret some important points .... I cannot find any info what are you going to cool within your chillers ... I assume propane, but I can be wrong

    Quote Originally Posted by RichardB777 View Post
    Hi Josip,
    Thoughts;
    existing and new compressors receive propane vapours from a common header, where pressure is controlled within a normal range solely by the new compressorís suction pressure override control. The existing compressors will be maintained at full output capacity by means of an operator-controlled output setting, while the new compressor output will be modulated based on maintaining level in the accumulator vessel.
    You need to have some level of propane within both receivers -i.e. accumulator vessels (old&new) to be able to utilize your economizers and to feed chillers with liquid refrigerant. To work with chillers you need to maintain evaporating pressure i.e evaporating temperature by changing compressor capacity. By changing compressor capacity to maintain level within receivers - you cannot control chiller evaporating temperature i.e. capacity (or I misunderstood something) .... so all the liquid injected into chillers will be removed as a suction gas by compressors then sent to condensers and after condensing return into receivers ... for me the bigger problem will be how to control parallel work of your condensers ...


    Quote Originally Posted by RichardB777 View Post
    Liquid level within the existing accumulator vessel will be maintained at an operator-selected setpoint by adjusting recycle valve position and propane pump speed. Liquid level within the new accumulator vessel will be maintained within a specified normal range by adjusting the new compressors output.
    again, by changing compressor capacity (output) you change your suction set point and chillers will not work properly ...


    Quote Originally Posted by RichardB777 View Post
    Variations in chiller demand will be compensated for by adjustment of the new compressor package recycle valve and propane supply pumps as the immediate response to changes in supply line pressure. This will result in rising or falling accumulator liquid level and consequently adjustment of the new compressors output based on maintaining the accumulator level within the normal range as the secondary response
    ... changing capacity of supply propane pumps you change liquid level within chillers i.e. suction pressure what will cause compressor capacity change ... this can cause something what we call "hunting" and control in this way is very hard if not impossible ... being there


    Quote Originally Posted by RichardB777 View Post
    Both the existing and new compressors receive propane vapours from a common header, where pressure is controlled by the new unitís suction pressure override control. The existing compressors will be maintained at full output capacity, while the new compressor will adjust output based on maintaining level in the accumulator vessel. If an imbalance of propane occurs where the existing accumulator vessel takes in more propane, this will be compensated for by the propane supply pumps. Conversely if an imbalance occurs where the new accumulator liquid level rises, this will be compensated for by the new compressor output.
    again if you change screw compressor output i.e. capacity you'll change suction pressure what will affect both compressors centrifugal and screw ... I am not specialist for centrifugal compressor capacity control, because I have not any practical experience with - maybe you can control it in a good way, but I am afraid screws will come into "hunting" what is very common with to fast control ...


    Quote Originally Posted by RichardB777 View Post
    Existing compressors hot gas bypass control will be removed from the logic to allow suction header pressure to be controlled solely by the new compressors
    Liquid propane at different temps being mixed together in piping. Vapor break out??
    If level control within chillers will work correct in the return pipe i.e. common suction header you should have only propane vapor ... then you have suction drums in front of each compressor what will eliminate any drop of liquid propane within suction line ...

    Hope you can upload your new refrigeration scheme where we can see changes and accordingly give you some suggestion/s...


    Best regards, Josip

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    Re: Two process refrigeration systems working together and load control?

    To all who reads, not looking for a design.
    Just issues that may arise from your experience, in similar process or in refrigeration.
    Thank you
    R

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    Re: Two process refrigeration systems working together and load control?

    Hi, Richard ...

    Quote Originally Posted by RichardB777 View Post
    To all who reads, not looking for a design.
    Just issues that may arise from your experience, in similar process or in refrigeration.
    Thank you
    R
    please, do not take this in a wrong way .... we are not offering you design of your new plant neither force you to change your design ...

    .... but ....

    ... your approach to design&make a refrigeration system as introduced&showed to us is not good and we are trying to tell you that, but for some reason you do not like to accept that ...

    You must think about that RANGER_1 and me asking you so many questions are trying to help you .. if we did some mistakes in the past (due to trial&error) I have to tell you about to avoid it ... behind both of us there is almost 80 years of theoretical and practical experience within industrial refrigeration ... I believe there is something behind at least to hear ...

    I am sorry and I do apologize if I sounds rude, it was not my intention at all, but I am too old to say to somethings what is black it is white or vv.



    Best regards, Josip

    It's impossible to make anything foolproof because fools are so ingenious...

    Don't ever underestimate the power of stupid people when they are in large groups.

    Please, don't teach me how to be stupid....
    No job is as important as to jeopardize the safety of you or those that you work with.

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    Re: Two process refrigeration systems working together and load control?

    Hi Josip,

    Apologies if you thought I was meaning you gents were trying to design it and I felt threatened by that. What I meant by my comment was, there is lots of experienced people out there and when we read posts sometimes we think the originator is lazy and trying to do it the easy way lol. I appreciate yours and RANGER's comments. When this project was proposed to us, I tried to research a similar system and got nothing. I agree with your last line lol. I'll get a scheme up soon.
    Cheers
    R

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