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Quit Stalling! Avoid Heat Exchanger Stalling with Armstrong International
WEBVTT Kind: captions Language: en
00:00:06.430 well hello my name is Randy Waldron with 00:00:09.22000:00:09.230 Armstrong International and today we 00:00:11.37900:00:11.389 want to take a few minutes to clarify 00:00:14.07000:00:14.080 some issues that are common problems in 00:00:17.89000:00:17.900 heat exchanger drainage throughout a 00:00:20.71000:00:20.720 multiple of different industries we're 00:00:23.92000:00:23.930 lucky enough today to have a working 00:00:28.68900:00:28.699 model of a glassy exchanger that most 00:00:33.04000:00:33.050 process engineers don't actually get to 00:00:35.17000:00:35.180 see what happens inside the piping or 00:00:37.03000:00:37.040 inside the heat exchange equipment so 00:00:39.45900:00:39.469 what we're going to do is kind of run 00:00:40.93000:00:40.940 you through the system that we have and 00:00:42.76000:00:42.770 then we'll go through some different 00:00:44.44000:00:44.450 variables that take place in the process 00:00:46.66000:00:46.670 loop that will hopefully allow you to 00:00:51.16000:00:51.170 troubleshoot systems better evaluate 00:00:54.27900:00:54.289 potential issues that they have and come 00:00:57.76000:00:57.770 up with intelligent solutions to solve 00:01:00.34000:01:00.350 their problems to start off with to let 00:01:03.61000:01:03.620 you know what we have is we have a glass 00:01:05.49900:01:05.509 shell and tube heat exchanger in this 00:01:08.26000:01:08.270 case we have a process fluid coming in 00:01:12.31000:01:12.320 in this case which is water flowing 00:01:16.06000:01:16.070 through the tubes we have the process in 00:01:19.71900:01:19.729 the tubes and the steam in the shell the 00:01:23.08000:01:23.090 water coming in on the right hand side 00:01:25.06000:01:25.070 as you can see is a variable flow we 00:01:29.10900:01:29.119 have the ability to vary that flow just 00:01:32.44000:01:32.450 like you would see a different process 00:01:34.14900:01:34.159 demand on any kind of heat exchanger the 00:01:37.21000:01:37.220 beauty about the lesson we're going to 00:01:38.64900:01:38.659 learn today is that heat exchange 00:01:41.53000:01:41.540 equipment the variables we're going to 00:01:43.74900:01:43.759 talk about are common whether you're 00:01:47.28900:01:47.299 heating air or whether you're heating 00:01:49.66000:01:49.670 glycol or ethylene okay the variables 00:01:54.39900:01:54.409 that we're going to point out are always 00:01:56.67900:01:56.689 areas that can change within the system 00:01:59.95000:01:59.960 and when those changes take place they 00:02:03.52000:02:03.530 have different effects on both the 00:02:05.92000:02:05.930 equipment itself and the downstream 00:02:07.74900:02:07.759 equipment like our traps like our pumps 00:02:09.88000:02:09.890 and the other products that we made we 00:02:14.17000:02:14.180 are feeding the shell side of this heat 00:02:16.47900:02:16.489 exchanger with saturated steam 00:02:19.93000:02:19.940 we're coming off of a 50 pound header 00:02:25.93000:02:25.940 dropping down coming through one of our 00:02:29.35000:02:29.360 control valves where the control valve 00:02:34.04000:02:34.050 has the ability to modulate the steam 00:02:37.64000:02:37.650 flow based on the process demand we have 00:02:41.89000:02:41.900 inherently built in a control panel over 00:02:45.62000:02:45.630 here that allows us to stroke this valve 00:02:48.68000:02:48.690 and simulate different process variables 00:02:51.94900:02:51.959 within the loop we come up we feed the 00:02:56.03000:02:56.040 top side of the exchanger over here on 00:02:58.82000:02:58.830 the right-hand side and that's where the 00:03:02.24000:03:02.250 steam comes in to the top side of the 00:03:04.01000:03:04.020 shell 00:03:05.74000:03:05.750 we then of course have the condensate 00:03:08.09000:03:08.100 outlet coming right out the bottom in 00:03:12.65000:03:12.660 the case that we have right now the 00:03:14.75000:03:14.760 scenario that we're simulating is 00:03:17.09000:03:17.100 strictly going from the exchanger over 00:03:20.63000:03:20.640 to some type of steam trap whether that 00:03:24.74000:03:24.750 be an F and T trap that we have at the 00:03:26.78000:03:26.790 top a thermostatic trap that we have in 00:03:29.87000:03:29.880 the middle the IB trap or at the bottom 00:03:33.89000:03:33.900 a northeast height trap we have the 00:03:39.56000:03:39.570 ability in this system to open another 00:03:43.31000:03:43.320 motorized valve that allows us to feed 00:03:45.74000:03:45.750 our pumping trap system now that we've 00:03:49.64000:03:49.650 kind of laid out what our piping 00:03:50.99000:03:51.000 arrangement is let's talk about some of 00:03:54.02000:03:54.030 the problems that we commonly incur with 00:03:58.00900:03:58.019 exchangers one is variable flow rates as 00:04:02.41000:04:02.420 we look at right now what the condensing 00:04:05.27000:04:05.280 rate is you can notice that as you see 00:04:09.59000:04:09.600 the liquid going through the tubes 00:04:11.33000:04:11.340 you'll see that there's continual amount 00:04:14.30000:04:14.310 of bubbles that travel through those 00:04:17.27000:04:17.280 tubes 00:04:17.96000:04:17.970 that's entrained air in the actual 00:04:21.83000:04:21.840 process flow okay one reason it's so 00:04:25.52000:04:25.530 important to get it out over here with 00:04:28.76000:04:28.770 our ball float air vent on the process 00:04:30.77000:04:30.780 side of the 00:04:31.35000:04:31.360 livvie what we're going to do now is I'm 00:04:36.83900:04:36.849 basically going to increase a little bit 00:04:42.60000:04:42.610 of pressure on the bundle you'll note 00:04:45.36000:04:45.370 that right now the gauge is showing an 00:04:48.62900:04:48.639 outlet pressure on the heat exchanger of 00:04:52.11000:04:52.120 five pounds let me take a minute to 00:04:56.15900:04:56.169 emphasize the importance of where 00:04:59.49000:04:59.500 pressures are taken as we try to 00:05:02.54000:05:02.550 troubleshoot these systems the inlet 00:05:06.71900:05:06.729 pressure that spent to a heat exchanger 00:05:08.93900:05:08.949 is normally always dependent on what the 00:05:13.40900:05:13.419 process flow is telling this control 00:05:15.68900:05:15.699 valve then it needs however what affects 00:05:21.20900:05:21.219 all of this equipment down here whether 00:05:25.80000:05:25.810 it's steam traps 00:05:26.99900:05:27.009 whether it's pumping traps is the actual 00:05:31.08000:05:31.090 outlet pressure of the exchanger the 00:05:35.12900:05:35.139 outlet pressure varies based on how much 00:05:40.55900:05:40.569 process flow we're trying to heat how 00:05:44.36900:05:44.379 much surface area we have to achieve 00:05:49.01900:05:49.029 that heat transfer and also by how much 00:05:56.77900:05:56.789 back pressure we have here that affects 00:06:00.80900:06:00.819 the total throughput of any of this 00:06:04.29000:06:04.300 equipment so we have to understand what 00:06:08.21900:06:08.229 those variables are to make a proper 00:06:11.39900:06:11.409 determination of why we have issues or 00:06:13.70900:06:13.719 have potential issues okay as we go 00:06:17.90900:06:17.919 through the traps we see that we have 00:06:20.18900:06:20.199 five pounds on the inlet and right now 00:06:22.82900:06:22.839 we're going to zero PSIG on the outlet 00:06:26.49000:06:26.500 side that's because we're going to drain 00:06:29.33900:06:29.349 as we continually try to help our 00:06:32.76000:06:32.770 customers optimize these systems we know 00:06:35.57900:06:35.589 that hot ton and sayd is worth a lot of 00:06:38.73000:06:38.740 money 00:06:39.17000:06:39.180 so typically we always try to recommend 00:06:42.29000:06:42.300 capturing this Commons 00:06:45.00000:06:45.010 but when we start capturing condensate 00:06:48.01000:06:48.020 that also creates other issues for us 00:06:50.14000:06:50.150 okay 00:06:51.45000:06:51.460 like back pressure in low pressure 00:06:55.33000:06:55.340 systems back pressure is one of the most 00:06:58.87000:06:58.880 common problems that we incur when we 00:07:04.78000:07:04.790 try to evacuate condensate from a steam 00:07:07.06000:07:07.070 space what we're going to do now is I'm 00:07:11.92000:07:11.930 going to slowly valve out this 00:07:15.90900:07:15.919 atmospheric mouth and we're going to 00:07:20.86000:07:20.870 slowly as you can see start to build up 00:07:23.23000:07:23.240 level in the condensate return piping as 00:07:27.42000:07:27.430 you see the condensate being drained 00:07:31.89000:07:31.900 through the trap the differential 00:07:36.76000:07:36.770 initially on this trap was five pounds 00:07:39.73000:07:39.740 we had five pounds on the outlet of the 00:07:41.83000:07:41.840 heater coming into the trap 00:07:43.80000:07:43.810 we had zero PSIG at the drain right now 00:07:49.63000:07:49.640 what we've just done by valving in the 00:07:52.48000:07:52.490 condensate header is we're slowly 00:07:54.88000:07:54.890 inducing back pressure on the trap we're 00:07:59.26000:07:59.270 inducing the back pressure by allowing 00:08:00.90900:08:00.919 the liquid head to generate look at the 00:08:03.27900:08:03.289 level down the level is almost to the 00:08:05.83000:08:05.840 top 00:08:06.45000:08:06.460 but remember one PSI for every two feet 00:08:09.54000:08:09.550 there's a foot there's a foot there's a 00:08:12.85000:08:12.860 foot there's a foot so we're slowly 00:08:16.60000:08:16.610 cutting back on the differential across 00:08:19.02900:08:19.039 this trap by generating that amount of 00:08:22.18000:08:22.190 liquid head the other thing we always 00:08:26.56000:08:26.570 have to remember is not only do we have 00:08:29.80000:08:29.810 liquid head in the vertical rise but we 00:08:33.21900:08:33.229 also have the pressure that exists in 00:08:36.57900:08:36.589 the condensate header itself that we run 00:08:40.14000:08:40.150 usually in an overhead return scenario 00:08:44.13000:08:44.140 what we want to do now is I want to 00:08:48.37000:08:48.380 slowly actuate a valve that will allow 00:08:52.66000:08:52.670 us to observe 00:08:55.07000:08:55.080 our pumping track system and how we can 00:08:59.06000:08:59.070 optimize those exchangers by allowing 00:09:02.66000:09:02.670 them to run in the lowest possible 00:09:04.10000:09:04.110 pressure again as steam experts we all 00:09:08.99000:09:09.000 understand that the latent heat content 00:09:11.60000:09:11.610 in lower pressure steam gives us a lot 00:09:15.26000:09:15.270 more heat value per pound then does the 00:09:18.14000:09:18.150 higher pressure steam so what it makes 00:09:21.41000:09:21.420 sense for us to do is to run those 00:09:24.41000:09:24.420 exchangers at the lowest possible 00:09:26.45000:09:26.460 pressure to optimize their performance 00:09:29.41000:09:29.420 okay what we wanted to do was continue 00:09:32.60000:09:32.610 and show you what we've done to actually 00:09:36.07000:09:36.080 equalize our pumping system into the 00:09:39.80000:09:39.810 outlet pressure of an exchanger what we 00:09:43.01000:09:43.020 wanted to show is graphically show you 00:09:45.23000:09:45.240 that our ability to continually drain an 00:09:49.87000:09:49.880 exchanger regardless of its condensing 00:09:53.00000:09:53.010 rate regardless of its outlet pressure 00:09:55.84000:09:55.850 regardless of all of those variables 00:09:58.25000:09:58.260 that we just discussed that can cause 00:09:59.96000:09:59.970 issues if we engineer the downstream 00:10:03.32000:10:03.330 side of these exchanges correctly we can 00:10:06.17000:10:06.180 ensure that we never corrode the tube 00:10:08.96000:10:08.970 bundles because we always keep the 00:10:12.35000:10:12.360 surface area dry on the exchange that's 00:10:16.19000:10:16.200 a very very large value to all of our 00:10:18.77000:10:18.780 customers regardless of the heat 00:10:22.01000:10:22.020 transfer setup whether it's an air coal 00:10:23.87000:10:23.880 or a heat exchanger or reboiler okay 00:10:27.41000:10:27.420 what we've done was we actuated the 00:10:29.90000:10:29.910 valve on the outlet of the exchanger 00:10:32.39000:10:32.400 that allows us to free drain down into a 00:10:37.10000:10:37.110 closed-loop pump track scenario we 00:10:42.80000:10:42.810 realized that now we have products that 00:10:46.51000:10:46.520 incorporate both the pump and the trap 00:10:50.09000:10:50.100 together however for us to graphically 00:10:53.21000:10:53.220 and visually allow you to see what takes 00:10:58.46000:10:58.470 place in these processes we wanted to 00:11:01.07000:11:01.080 keep this separate so you can see what 00:11:04.82000:11:04.830 happens with the traps and how the pumps 00:11:07.55000:11:07.560 were 00:11:08.12000:11:08.130 in conjunction with the traps right now 00:11:11.09000:11:11.100 you'll see the outlet pressure of the 00:11:12.62000:11:12.630 exchangers at five pounds like it has 00:11:14.90000:11:14.910 been no different we have five pounds 00:11:18.08000:11:18.090 coming in we have five pounds coming 00:11:20.45000:11:20.460 around and we have five pounds that 00:11:24.53000:11:24.540 should be coming right to the steam trap 00:11:26.36000:11:26.370 okay and remember this this is critical 00:11:30.35000:11:30.360 it's a common mistake that even some 00:11:33.71000:11:33.720 seasoned veterans may I don't care what 00:11:36.68000:11:36.690 pressure you feed that exchanger what 00:11:39.74000:11:39.750 matters to us is what's on the outlet of 00:11:44.03000:11:44.040 that exchanger okay we can see that we 00:11:48.50000:11:48.510 have a float and thermostatic trap on 00:11:50.84000:11:50.850 the downstream side of the pump this 00:11:53.30000:11:53.310 trap is installed so that if the outlet 00:11:58.04000:11:58.050 pressure of this exchanger coming 00:12:01.16000:12:01.170 through the system exceeds the back 00:12:04.10000:12:04.110 pressure that we have trying to lift 00:12:06.92000:12:06.930 this condensate and get into the header 00:12:09.76000:12:09.770 we would have steam flowing all the way 00:12:13.16000:12:13.170 through this if we had no steam trap as 00:12:16.75000:12:16.760 you see now we have about eight feet of 00:12:21.83000:12:21.840 lift roughly that's about four pounds 00:12:25.21000:12:25.220 right on the outlet we're at about four 00:12:27.83000:12:27.840 pounds so you can see through the flow 00:12:33.65000:12:33.660 indicator that we have no flow through 00:12:36.65000:12:36.660 the trap into the vertical rise into the 00:12:39.59000:12:39.600 header we're currently at what we term 00:12:44.39000:12:44.400 as a stall condition but in essence the 00:12:49.85000:12:49.860 technical term for it is there is lack 00:12:52.61000:12:52.620 of differential pressure there is no 00:12:54.65000:12:54.660 pressure difference if anything we have 00:12:58.70000:12:58.710 more back pressure than we have inlet 00:13:01.88000:13:01.890 pressure to the trap so regardless of 00:13:05.42000:13:05.430 how big this trap is when there's no 00:13:08.75000:13:08.760 difference in pressure to push liquid 00:13:11.21000:13:11.220 through it this trap will not operate 00:13:14.18000:13:14.190 correctly on this 00:13:16.53000:13:16.540 so what we're doing is we're continually 00:13:19.62900:13:19.639 condensing in the exchanger you'll see 00:13:22.50900:13:22.519 that we're at four pounds and four 00:13:23.98000:13:23.990 pounds what I'm going to do now is 00:13:27.69900:13:27.709 slowly modulates the steam control valve 00:13:32.88900:13:32.899 to decrease the amount of steam flow to 00:13:37.90000:13:37.910 the exchangers because we're going to 00:13:40.38900:13:40.399 drop this outlet pressure and we want to 00:13:43.29900:13:43.309 demonstrate to you that this system 00:13:46.60000:13:46.610 allows the exchanger to run at either 00:13:49.41900:13:49.429 five pounds a hundred pounds or in a 00:13:54.00900:13:54.019 negative pressure because there goes the 00:13:57.79000:13:57.800 pump I believe it just cycled you can 00:14:01.41900:14:01.429 see now that there is flow coming in to 00:14:04.96000:14:04.970 the trap and as we slowly start to build 00:14:10.50900:14:10.519 pressure in the pump body you'll see the 00:14:14.79900:14:14.809 pressure slowly build here as that 00:14:17.41000:14:17.420 happens we will continually pump liquid 00:14:20.46000:14:20.470 into and out of the trap and into the 00:14:23.71000:14:23.720 header and we should as the pressure 00:14:27.24900:14:27.259 bills in the pump we should see a flow 00:14:35.23000:14:35.240 through the vertical rise here but note 00:14:38.11000:14:38.120 this this is very important why is it 00:14:40.72000:14:40.730 important for the reservoir on a pumping 00:14:42.75900:14:42.769 trap because even though we are now in 00:14:46.17900:14:46.189 the pump out cycle of the pump which 00:14:48.97000:14:48.980 close the inlet check valve we're now 00:14:53.11000:14:53.120 still condensing the same rate of liquid 00:14:55.50900:14:55.519 in the heat exchanger we have to have an 00:14:59.28900:14:59.299 adequate reservoir to take the amount of 00:15:03.87900:15:03.889 liquid that we condensed in the 00:15:05.04900:15:05.059 exchanger and allow it to gather 00:15:07.23900:15:07.249 someplace while the pump is pumping the 00:15:10.62900:15:10.639 liquid out through the steam trap okay 00:15:13.94900:15:13.959 what you're going to see is the 00:15:17.19900:15:17.209 continual rays of level in the glass 00:15:20.87900:15:20.889 reservoir piping as we're trying to pump 00:15:25.05900:15:25.069 out through the trap and in 00:15:26.90000:15:26.910 the maternity header once we go through 00:15:30.62000:15:30.630 this pump-out cycle I will go ahead then 00:15:34.67000:15:34.680 and we'll go ahead and cycle the 00:15:36.26000:15:36.270 exchanger to go into vacuum and show you 00:15:39.41000:15:39.420 that it still basically allows you 100% 00:15:42.74000:15:42.750 turn down on the rates and the variables 00:15:46.36000:15:46.370 by allowing it to drain regardless of 00:15:48.98000:15:48.990 what that pressure is note that the 00:15:52.46000:15:52.470 steam pressure from the regulating valve 00:15:55.18000:15:55.190 going into the pump track system that we 00:15:59.51000:15:59.520 have it's set at about 8 pounds okay 00:16:04.93000:16:04.940 so we're building we're feeding about 8 00:16:08.63000:16:08.640 pounds into the pump note that now the 00:16:12.98000:16:12.990 pressure is up to about 6 just for you 00:16:17.09000:16:17.100 guys that are selling pumps all the time 00:16:18.77000:16:18.780 remember this typically the pump case 00:16:23.36000:16:23.370 pressure will never increase over about 00:16:28.25000:16:28.260 10 pounds of what your total bike 00:16:30.98000:16:30.990 pressure is where we're trying to pump 00:16:32.84000:16:32.850 the liquid to because by the time the 00:16:35.60000:16:35.610 pressure in the pump case builds to that 00:16:37.88000:16:37.890 level the liquids already gone it's 00:16:40.34000:16:40.350 already moving remember we had no 00:16:43.04000:16:43.050 differential pressure we were stalled 00:16:45.73000:16:45.740 we're inducing differential pressure now 00:16:49.07000:16:49.080 by the high pressure feed into the pump 00:16:53.41000:16:53.420 pressurizing up over the back pressure 00:16:57.16000:16:57.170 coming in pushing it out through the 00:17:00.11000:17:00.120 float trap and up into the header now 00:17:04.01000:17:04.020 the pump out cycle is a fairly long 00:17:07.94000:17:07.950 cycle in this demo simply because we 00:17:11.51000:17:11.520 wanted you to have the last drive 00:17:14.65000:17:14.660 typically the track downstream of your 00:17:17.93000:17:17.940 pump should be able to take the max 00:17:21.95000:17:21.960 condensate rate of the exchanger at a 00:17:24.17000:17:24.180 quarter-pound differential so you don't 00:17:26.57000:17:26.580 bottleneck the pump out cycle of the 00:17:29.66000:17:29.670 pump because what happens when we 00:17:32.06000:17:32.070 bottleneck the pump out cycle bottom 00:17:34.79000:17:34.800 line is it takes more reservoir because 00:17:37.82000:17:37.830 I have 00:17:39.13000:17:39.140 more time for this to continue 00:17:40.84000:17:40.850 condensing and I have to have a place 00:17:43.30000:17:43.310 for more of this condensate together so 00:17:47.50000:17:47.510 the function of the trap dictates what 00:17:51.34000:17:51.350 the reservoir is the motive pressure to 00:17:56.35000:17:56.360 the pumps dictate what the trap is so we 00:18:01.36000:18:01.370 have to take into consideration all of 00:18:02.98000:18:02.990 these things as we engineer a total 00:18:05.89000:18:05.900 condensate return solution for the 00:18:09.07000:18:09.080 exchanges
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