Frick Screw Compressors Pt. 2

Hello. I'm Joe Kullis, engineering fellow with Johnson Controls Industrial Refrigeration. Today, we'll be speaking about our second basics compressor show on screw compressors in refrigeration and we'll talk cover the topics of economizers and side loads, some energy-saving features, and then package features of the of the frick compressor package. So we'll start off with dichotomizers and side loads. One advantage that a screw compressor has over a reciprocating compressor is this ability to have a secondary suction port that can be used to draw additional vapor into the machine. And we'll talk about this really in two ways as an economizer. Economizer uses that secondary suction port to sub-cool liquid that's going to the evaporator from the condenser, essentially giving colder liquid to the expansion valve that goes through the evaporator. Side load is a little bit different. A side load is a secondary evaporator. Where we feed the evaporated vapor from that back to the Economizer port on the machine So that's the two ways that we use this software. So the Economizer port is really just a hole. That's machined into the side of a compressor casing. It's it's located to provide a pressure of approximately one point six times the absolute suction pressure and then that becomes a secondary suction port. Two ways this is piped can be seen here. The top one is maybe the simplest. So our compressor is symbolized by this device on the far right. Vapor comes out of the evaporator, the cold part of the system is drawn through the compressor, pushed to the condenser and then back to the expansion valve. In a normal system. And then what happens with an economizer system is a portion of that condenser liquid is fed to a secondary evaporator which could be a dock load in many cases. If you've got a cold room, quite often there'll be a dock load where food is held before it's loaded onto trucks, so it's at a higher evaporating temperature than the conventional evaporator. And then that vapor from the secondary evaporator would be drawn into the economizer report. So secondary load, economizer piping is a little different. We take that condenser liquid that's coming from all the gas that's been compressed. We take it through an expansion valve and partially expand it into a flash economizer vessel and that some portion of the vapor that flashes will be, will draw them back to the economizer port on the compressor that drops the pressure in this vessel and it makes the liquid colder. So eventually essentially we're refrigerating a liquid or a portion of the liquid that comes from the condenser to feed to the expansion device going to the evaporator. Colder liquid makes more refrigeration effect. So that's the the purpose of the economizer. Economizer is a special case of a side load evaporator, but part of the condensed liquid is evaporator to cool the remainder of the condensed liquid. So here we can run through the numbers as an example. So we can see I've got seventeen degree minus seventeen degree evaporator, hundred pounds a minute coming out of the evaporator to the compressor. And then we all have eighteen pounds a minute coming vapor coming off of the flash economizer. And can see it on the these are PH diagrams. So we have pressure on this axis and we have enthalpy. Which is a measure of the energy per pound in the vapor that's being compressed. So we can follow what happens in the evaporator is along the bottom portion of line, a compressor will take it from the suction pressure up to the discharge pressure and then the condenser is on the stop portion. So that's in single stage compression. We can see in this case, again, the hundred pounds a minute is going through the compressor. In the single stage system. The enthalpy difference, which is what provides the cooling, in this case, is 458 BTUs per pound, and then that will provide 229 tons of refrigeration. So that's kind of our starting point. Now when we add the economizer cycle, on the pH diagram, we've still got the evaporator at the same place, we've still got all the vapor coming out of it that's taken through compressor. But now we got this new sideboard. So the flash vessel is in this area, the vapor is going to the economizer port and the sub cooled liquid now is colder, and then that's fed down to the to the conventional TX valve on the evaporate. So look at the numbers on that. Start out with our 100 lbs/minute coming from the low side evaporator. The ancillary difference is the same we showed before, 458 pounds, but now we've got this edition of 19 lbs/minute coming into the condomizer port. And we have a larger enthalpy difference on the sub cooled liquid. So we we will get more tonnes refrigeration effect per pound of vapor for this cold liquid coming to the low side evaporator. So we'll look at the numbers. Now, it's at 273 three tons of refrigeration. Which is a 19% increase in evaporator tons that the same evaporator mass flow, remember it's cold or liquid coming in. So we'll look at the mass flows now on the molar diagram. So there's a hundred pounds a minute through the low side evaporator. Nineteen pounds a minute through the economizer line. They are combined in the compressor, the two separate streams, and so we deliver 119 lbs/minute to the condenser. So as we said, we got 19% more tons. 19% more mass flow on the high side of the system. Only nine percent more absorb power. That's kind of the magic of economizers. Subcooling has a a big benefit in this and also because we don't have to compress that 119 lbs of vapor, all the way from suction pressure to discharge pressure, it takes less energy to do it, less power to compress that that side stream. So that's where we get the boost in efficiency economizers. You can plot the efficiency gain in percent based on evaporating temperature and I put three different refrigerants in slide. So ammonia which is probably what we're most interested in at twenty degrees Fahrenheit. You could expect about a five percent gain in efficiency, real gain inefficiency. At minus forty, if it's single stage, can be about twelve, thirteen percent gaining efficiency. And as we look at some of the other gases like R22 which no one is too interested in anymore, the gains were higher. There's more benefit from sub cooling and five zero seven was probably the most gain in any of the gases that we commonly sold giving as much as forty percent increase in efficiency on an economized cycle. So very big, very big gain on some of those refrigerants, but of less interest as GWP concerns have made it harder to use those gases. Economomizers can also be used in combination with a variable speed drop. So we talked about variable speed in in our basics one session. But the advantage with the VFD is the slide route can stay at full load. And that means the economizer pressure stays at the same place all the time. Normally when you unload the slide valve, the economizer pressure would drop. So at some point with the slide valve, the economizer becomes ineffective and will often close it. And not use it all the way down the part load curve. But the VFD, because we never open the the economizer thread, might say to suction pressure, it can be used at all the time, all the time. So we can get the same efficiency boost at all the way down the part load curve by combining a VFP minimize. These curves are maybe a little busy, but this is horsepower per ton on the y axis. So a higher number is worse, the lower number is better, and tons on the bottom axis. So there's two curves here that are slide valve. Let me show you turn this on. So the slide route were the two top curves. So one is economized, slight album change with brown marks, and the blue mark is a non economized, slight out machine. So the first thing you'll notice is the full load point, you get a lot more tons. And also a better energy point, so it's a lower in horsepower per ton at the full load point, just using the slide valve. Now when we add in the impact of a variable speed drive. We get first off, we get a a big improvement here. This is minus forty to ninety So this is a very high compression ratio case. This is probably the highest advantage you would ever see from an economizer So it shows the potential of the technology. But when we look at a variable frequency drive, with and without economizer. So now the non economized curves are these red line. And the economizer curve with the VSD is the purple line. And you can see there is always an efficiency gain all way up and down the parload curve combining a BFT with an economizer. So that's a that's a big plus from an energy usage standpoint. On the on ammonia, it's approximately a sixteen percent of course, power per tonne improvement achieved at all speeds by turning on the economizer with a BFT. So let's talk a couple other options for saving energy. One is we went through slides that talked about how machines work and suction pressure and discharge pressure and how BI is important to know and consider. When we're choosing our compressors. And we calculate the ideal BI based on what's going on in our system. So we have to know evaporating temperature and the pressure in the evaporator, and then what are condensing temperature and pressure are so that we all know what is the ideal volume ratio to run a machine at. But now when we introduce economizers, that changes things a bit because we've got this additional vapor that's coming into these threads that have already entrapped and closed and beginning the compression process and we're packing more mass into those threads so the pressure is increased And if we don't account for that extra mass flow in the machines, discharge port location would be calculated wrong. So the the standard BI calculations do not account for the added volume that comes from an economizer. I might also point out if you're running a simple fixed VI machine, a non frick machine that doesn't have variable volume ratio. It's very likely that it will not be running as efficiently as you would think when you're using economizers or cyclones. Economizer BI control was something that was introduced by Fricked. We had fully patented this and built it into our quantum panel. And on machines with high, side loads or large condimizer loads, the standard BI calculation really isn't enough because it doesn't account for the supercharging. So you basically turn on the quantum economizer BI control, and it'll calculate based on the extra mass that it's expecting to come in. From the economizer and and adjust the BI typically down lower. So there's two ways of putting this in the quantum panel one, if it is a fairly normal economizer with the expected flow, just for cooling the liquid, you might say. Those values are pretty well known. We can just put in expected economizer pressure in the quantum panel as a single number and and that would be sufficient to recalculate the v I. If it's a side load like some of these have locations where the condomizer is being used to carry a dock, let's say, instead of another compressor. In those cases, the side loads can get pretty large, and there's a lot of mass flow coming into the economizer port. We will offer a pressure transducer installed on the economizer. To tell the quantum panel what the actual measured pressure is and adjust to the correct BI based on that. We look at how much this could be off. How much could the volume ratio be off when the economizer is running. I've got two different examples. This one is a forty ton side load at 74 PSI and on an RMB 117, so we got 150 PSI discharge, and we would say what volume ratios should be running, while the the blue line is if you were just adjusting the BI based on suction conditions, you know, it might have me up at four and a half BI here. When we turn on the BI control, it will recalculate down to about 3.6, 3.7 BI, and that difference saves energy, saves money. So the ideal that BI is now the green line, but we need the economizer BI control turned on. In order to gain that advantage. Now here's one that's a little more extreme. This is kind of the max side load case. Where we would have let's say a dock load coming into a machine where the flow may not be known so well, can be quite large sometimes. And this is where we'd we would use a pressure transducer on the side port. But again, if we only look at suction pressure and discharge, we might be up at 4.7 BI, 4.8 BI. But accounting for that extra mass flow would drive us all the way down to 2.6 BI. So there can be very significant energy savings on a large siloed application that really that really needs this economizer BI adjustment to get back to the ideal BI position. This can amount to quite a bit when we look at a machine over its one year of operation. So again the numbers are given the bottom for what the assumptions are. And in this case, we could save from $52,000/year down to maybe $4000/year depending upon size of the load and size of the compressor and all that. Well, this is based on a 177 size machine. But there is significant savings to be had from economizer BI Control. We call that power mizer and basically in the setup, you'll just have a couple simple numbers that have to be imported into the panel, and it'll do the calculations to make the adjustment, or you have to tell it that you're using external pressure transducer, and then it would it would read that and I make the adjustment based on that. So that's, again, just part of the setup in the panel. If we do pipe the transducer, it's it's quite simple. It's just the pressure transducer on the anonymized report. That's that's feeding to the feeding that signal to the quantum panel. So it knows how what the current pressure is from a, let's say, a large side load in some cases. And we do factory assemble that. We can set it up in the quantum panel before it leaves. And make it very simple. So I wanted to talk just a little more about packages. We have our food and beverage line, basically the RWF, which is sort of our bread and butter. We've got thirteen standard models, six super speed models, which go above 3600 RPM -- Mhmm. -- for using the VSD for additional capacity. Our RXF is our small compressor family. There's eleven models there. And then the HPS, which is our smaller high pressure machine, there's three models there. And those are VSD only. And we talked a little about starters and VSDs. We will package mount starters and VSDs. That's a option that we sell. There's a few reasons to do that. One is it's better electrical integrity the motor leads are kept very short, right, out of the motor straight into the panel, so there's not a lot of noise generated on those lines. To interfere with other things in the plant. That's very compact design to reduce engine room space, as a door and door, to make servicing easy. You don't have to put on your special gear. To open a door because it's just a very small low voltage area that you can use to service the drives. And there's additional options for voltage detection and safties within the system and they're completely factory wear and tested prior to shipment. Which also reduces risk on the startup. I wanted to talk about a few other features of our packages Most of you would know that we use motor adapters on all of the RWF and the RXF family. So we basically are bolting the motor and the compressor together by a very stiff mounting arrangement that's bolted onto the compressor. This simplifies installation and maintenance. We use a deflange, motor mount, to bolt the motor directly to the compressor, eliminates the need for hot in cold alignment, bad installation, and forever. This is not something that you have to go check. We machine it very tightly so that the correct alignment between the compressor and motor is assured by the machining tolerances. And knowing that it's in a line all the time, it reduces shaft seal, failures, reduces motor bearing failures and that's really close. The motor tunnel is dialed to the compressor to get very given a very precise position, and then there's a pilot diameter on the motor as the motor is bolted to the tunnel that sure is the alignment on on that end of the arrangement. So we now have a motor and compressor bolted together in a very rigid assembly. And supported by a minimum number of contact points with the separator. Notice, we only use a single foot under many of these motors under the back end. So really the tunnel itself is providing the support for the the front feet, but you you have to do it that way in order to keep stress down on that drivetrain. This is not something that we introduced. We actually stole this idea from York who we were selling screw compressors too beginning about 1991. And we saw how they used this on their centrifugal machines, so we kinda copied it or the screw machines. So this is actually a Frick screw turned upside down with its suction flange bolted directly to an evaporator, and this is the deflange mount here and then we have a single-post support under the back of the motor foot. So they have been using that for many, many years in their air conditioning applications and then we saw how well it worked for them and we started to use it on refrigeration applications. Here's one of their centrifugal packages, and you'll see they use the same design. Here's the motor tunnel in this area. There's a single post support under the back end of the motor. Now this one has a six hundred horsepower, So one of the smaller ones, here's a 1750 horsepower motor again with the flange mount. So the tunnel is here. To bolt the two together, and there's their single post support under the back foot of the motor. So again, this is a design that's been well proven by York before we began to use it, and now we've been using it for a little over twenty years. You might wonder about access to shaft seal, these are still open drive machines. We're using disk type couplings and a cover. So you remove the access cover and then you can get in to remove the coupling hub and remove one hub in order to have the ability to service a shaft seal in place without having to remove the compressor. The proof of the pudding is in the warranty report card, you might say. So we introduced this quite a number of years ago. So this is actually two thousand and one. In two thousand and one, we were still shipping machines both flanged and foot mount although we're starting to shift over to more flange, and you look at the number of motor bearing claims that we had, we saw a ten to one reduction in motor bearing claims when we went to flange mount. And it's very similar also on shaft seal failures. So it really told us that even though we were asking for very tight alignment on foot mount motors, we weren't always getting it. And being able to bolt the two together assures that they'll be in alignment. A few other points on compressor packages. I wanted to talk a little about oil separators. So here we have compressor located here. We're mixing oil into the gas stream as it goes through the compressor. It's discharged against the head in the separator. And then through gravity, Most of the larger particles would drop out as it comes through the machine. And then we go through coalescing filters. The coalescing filter will take the last boiled smoke, the smallest oil particles, and coalesce them into larger droplet. That can drop to the bottom of the second stage of the coalesce and oil separator, giving relatively dry gas out to the plant. We say it's between two and five parts per million of oil left in the gas stream after it after it leaves the the wall separator. Coalescing filters play a very big part in getting good oil carryover. And one of the other features of the machine is that we have our own special, what we call, super coalescer, something that we developed a number of years ago, and also patented. And it allows higher velocity. So we can run the velocity about twenty percent higher through these coalesers than you can with a conventional coalescer. And in many cases, that allows energy saving because you can run the head pressure lower and not worry about blowing oil out of the separator. So that's kind of the purpose of the super coalescer is to be able to condense at lower pressures. So to give an example here, the way separators work is there will be an allowable velocity through the separator. A convoluted coalescer would allow a certain flow rate depending upon the density of the refrigerant coming through it. Super coalescers will allow essentially a higher velocity without curing over oil. So because we can run them a bit faster in velocity, then we can run the pressure a little bit. What does that mean in terms of efficiency? So if we look at the separator velocity limit, as a function of condensing pressure and suction temperature, we can draw a line that says If you try to go below the blue line with a conventional separator, you're gonna blow oil out. So when we then add in the line for super coalescers, we're able to go to lower condensing pressure without carrying over oil. So that difference in condensing pressure, that's what's keeping you from running your condenser lower is worth a lot of energy. And that's a COP coefficient performance increase between 25-40%. So that can be very significant. And if you look at what that means in terms of three course power per ton at different temperatures, again, it's very very worse. One of the other differences with Frick packages, we believe in good filtration. We have developed our own SuperFilter II today, and we're believers that clean oil protects shaft seals and makes bearings last longer. It extends the seal life dramatically, extends the bearing life dramatically. When we look at L10 life, which is calculated bearing and compare it to attainable service life with clean oil. There's a very significant difference. And good filters make that make that difference effective like. All of our filters are full flow filters. So all the oil that comes out of the oil separator goes through the filters before it goes to the compressor. Not all of the screw compressor packages on the market are that some of them are only filtering, bearing oil. They don't filter the rest of the oil to the machine. So we're believers in very good I'm not particularly proud of where our industry came from. When I came into this industry, the standard filters that we bought and pretty much everybody else bought as well, you could rate them two ways. 99% capture would be called an absolute filter, call it absolute forty micron. The lower rating is a fifty percent particle capture rate, a nominal filter. If you don't ask somebody, if it's an absolute or nominal filter and you don't really know, the rating can be drastically different. But we were at about forty micron absolute filtration ratio until, I'm gonna say about twenty years ago, we decided that we needed to get cleaner. And we went to fifteen micron absolute filters. And that was a big deal. When we first started putting those in machines, people complaned because they weren't getting the same filter life. We put out a new package. They have to change filters pretty quickly after installation. But then once the oil was cleaned up and the construction dirt was out of the piping, then they didn't have to change the filters more often, and people started to get used to that. And about another, I'll say, ten to fifteen years ago, we dropped the filtration again, down to five micron absolute filters, and that's our standard filter today. We also increased the dirt holding capacity of the filters and we never heard anybody complain on the second step. So I think we kind of trained them when we went to the fifteen micron filters but today you're getting much cleaner oil based on the super filter ratings. So you'll have the question from manufacturers. How often do I need to replace my bearings or tear my machine apart and do the service, we really take the position that if you do oil analysis and use super filters, you're going to get a very long life. Out of your bearings and your seals, and then use oil and vibration analysis to tell you when you need to change oil and when you need to change bearings in a machine. The additional step beyond that is adding PHD continuous monitoring, onboard vibration monitoring to a machine, and then it will tell you when you need to tear a machine apart and replace bearings. PHD plus is our current on board vibration monitoring system that we sell. It's a it's a very nice system. This kind of replaced our old PHD that we've had for maybe twenty years and this has a lot of new features in it. It's it's able to provide much more much more information about bearing condition in machines. Has very precise calculations that are specific to the compressor model. So the PHD knows which bearings are in each machine. And it's looking at critical frequencies of all of those bearings and all the harmonics of the critical frequencies. So it will flag a bearing defect very early when damage starts to develop. It also has VSD speed input to the PhD. So if you have a VSD and you're going up and down in frequency range, that of course changes where the varying critical frequencies are but the PHD plus can track that. And it's also very consistent readings. It's focused on varying frequencies It has separate channels that are monitoring one times RPM and load passing with different limits. So it can tell a lot more than the original PHD system could and it's really a very nice system to say, when do I need to maintain my machine or place things? It has very reliable detection at 1x rotational speed. So let's say something goes out of balance, it'll pick that up. The 240x are in the 240 hertz, which is a 4x on most of the machines that would normally be liquid slugging. It can pick that up. And then also it has failed to save technology on the sensors. So if the sensor wiring is something wrong is detected, that would alarm and back to the panel, so you'll know that you've got a problem with the sensor. Couple other package features that I thought I'd mention. All Frick's precompressor packages today are built with internal mufflers. And they are refrigerant specific. So if you have ammonia muffler is different than an R22 muffler is different than an 5x7 muffler. And they basically are designed as broadband resonant tuned damping devices that damp the discharge pulsation. So they take a lot of the vibration out of the packages on Frick packages. A couple of other features that we have. We're just this is kinda random package features at this point. Energy saving is heat recoveries. Coming more and more important. So you have oil cooler heat that can be reclaimed, either rejected to the atmosphere or reclaimed. But reclaiming that heat can save on your energy bill or gas bill. And as people are more and more concerned about their their green footprint. This can become more and more important as a way to show your sustaining your own plant by reducing your energy footprint. So we'll quite often sell a thermocycling cooler as the the primary oil heat rejection device, but if if you need the heat for let's say glycol slower warming or something like that, then you can use the primary oil cooler anytime you have a use for the heat. If you don't have a use for heat then you can dump it to the the thermocycling can cooler or even use it in a glycol cooler. I will talk a little bit about glycol oil cooling. So we have the heat that's coming out of compression that's in the oil cooler. That could be used to preheat municipal water that you need in your plant can be used for underfloor glycol heating to keep the ice from forming on the floors. If you can't use the heat, then we would have a fluid cooler or something like that typically on the roof. That we could carry that hot glycol two and reject the heat when it can't be used. And This also can save water because you're not putting load into your evaporative condenser when the oil cooler is rejected either to an air cooled drive or if you're using it for for glycol floor warming, so it can get some advantage there. Touch on the Quantum Control. We're using Quantum on all of our screw packages, most of our screw packages. And it's well proven at this point. We have all of these energy saving features that I talked about today built into the panel on many, many more. If you got BI control with the power miser, sequencing, the VSD controls, condenser control. There's lots of things in the quantum panel that are saving energy. Some cases like let's say the the economizer BI control, you gotta remember to turn it on. And and make sure the set point is correct, but then you can have significant savings from these features. And the last slide or last couple slides here, I thought just to mention that we have a long history. A product innovation in screw compressor packages at Frick. And I thought it's nice to just remind people some of these things, I won't dwell on them, but we've talked about the BI control, into friction bearings, which save energy, plate and ow coolers I didn't really talk about, but we went to these several years ago away from Shell in two and plate and shell coolers are wonderful. They just always eat so easily. Unlike shown tube coolers that often you'll struggle to get adequate feed and you're always playing with adjusting feed to the different coolers. If liquid can get into the cooler, it's kind of sucked up to the plates and through and provides a cool and very very nice quote coolers. We introduced Easy-Cool. We were the first with that. Motorized valve on the liquid injection system that's controlled by the quantum panel to adjust oil temperature. Mounted starters. We talked about PhD. I think we talked about most of these. So I'll skip on that. Some of the other firsts, this P drive now that we're package mounting that we have these, 5:1 turn down. I think we're still the only ones doing that in the market. No pumps or demand pumps only. We were able to offer that on almost all of our machines, which very few of our competitors do that. We don't talk about separator velocity very much. That's just a little feature in the quantum panel that looks at your combined condensing and evaporating temperatures and pressures and decides if you're getting close to carrying oil out of the separator. And if you are, it will it will protect things. It will basically unload the slide valve a little bit until you get through that condition to avoid curing oil over. And you might only have one or two days a year when you need that feature, but you can avoid over sizing an wall separator or it can avoid putting on carrying oil out of the oil separators. We talked about economizer BI optimization. I've never seen anyone else in the market offering that. Flangement motors, we're still about the only ones offering it. We have a few people copying us on that today, but we've had it, you know, for many, many years. Supercoalester. Clamping style hubs. They're not the cheapest way to install couplings, but most of our couplings are split hub so that when you install the coupling, first you clamp it to the shaft, then you tighten the set screw on the key, If you've ever tried to take a press fit hop off of a machine in the field, you will greatly appreciate clamp style hooks. It's so much easier to get these hubs off when you have to service a machine. Higher design work compression compressors and separators. We've introduced so many things over the years. And really, it's just a way of showing that we're in this for the long haul. And earning our customers' trust, and we hope to be here for a long time. Thank you very much. So we'll stop at that point. And if you've got any questions, hopefully we'll have provision to answer them.