00:01:00.250 even though it's 93 million miles away 00:01:03.00000:01:03.010 the Sun is capable of producing 00:01:04.89000:01:04.900 temperatures in excess of a hundred and 00:01:07.50000:01:07.510 thirty degrees Fahrenheit here on earth 00:01:09.33000:01:09.340 it provides the heat needed to support 00:01:12.33000:01:12.340 life and to continue many natural cycles 00:01:15.59000:01:15.600 we get the sun's heat by a process 00:01:18.27000:01:18.280 called radiation that's just one way 00:01:21.21000:01:21.220 that heat energy can move from one place 00:01:23.52000:01:23.530 to another here at the plant we use two 00:01:26.76000:01:26.770 processes to transfer heat in heat 00:01:28.74000:01:28.750 exchangers conduction and convection 00:01:32.69000:01:32.700 using a heat exchanger like this one 00:01:35.21900:01:35.229 makes our operations more energy 00:01:37.23000:01:37.240 efficient during this program we'll 00:01:40.02000:01:40.030 discuss two topics heat transfer 00:01:42.63000:01:42.640 specifically conduction and convection 00:01:44.40000:01:44.410 and heat exchangers the factors 00:01:47.60900:01:47.619 affecting their efficiency design use 00:01:50.13000:01:50.140 and maintenance as you know warm 00:01:53.04000:01:53.050 materials tend to lose heat to cooler 00:01:55.32000:01:55.330 ones when the materials are in direct 00:01:57.71900:01:57.729 contact with one another the process of 00:02:00.54000:02:00.550 heat transfer is called conduction 00:02:02.74900:02:02.759 another way to transfer heat is by 00:02:05.28000:02:05.290 convection this is caused by a change in 00:02:08.55000:02:08.560 fluid density that sets up currents the 00:02:11.69900:02:11.709 following example will illustrate both 00:02:13.47000:02:13.480 processes if a metal container of hot 00:02:16.94900:02:16.959 water is touching another filled with 00:02:18.90000:02:18.910 cold water the temperatures of both will 00:02:21.44900:02:21.459 change because of heat transfer the 00:02:24.06000:02:24.070 greater the temperature difference the 00:02:25.77000:02:25.780 faster the transfer takes place in this 00:02:28.59000:02:28.600 example the heat is carried through the 00:02:30.27000:02:30.280 metal walls by conduction the cold water 00:02:33.47900:02:33.489 closest to the wall absorbs the heat 00:02:35.43000:02:35.440 directly from the metal and increases in 00:02:38.07000:02:38.080 temperature this warm less dense water 00:02:41.40000:02:41.410 rises and is replaced by cooler water 00:02:44.00900:02:44.019 then a convection current transfers heat 00:02:47.34000:02:47.350 to all parts of the water this transfer 00:02:50.49000:02:50.500 results in a change in temperature for 00:02:52.50000:02:52.510 both containers conduction and 00:02:55.08000:02:55.090 convection take place almost 00:02:56.81000:02:56.820 simultaneously to move heat from one 00:02:59.13000:02:59.140 fluid to another in conduction an 00:03:02.37000:03:02.380 important factor affecting the rate of 00:03:04.44000:03:04.450 heat transfer is the type of conductor 00:03:06.81000:03:06.820 used conductors vary widely in their 00:03:09.72000:03:09.730 ability to transfer heat as you may 00:03:12.33000:03:12.340 expect 00:03:13.14000:03:13.150 metals are better conductors than glass 00:03:15.11900:03:15.129 or wood materials let's see how 00:03:18.21000:03:18.220 conduction and convection work together 00:03:20.25000:03:20.260 in a simplified heat exchanger because 00:03:23.58000:03:23.590 of the difference in temperatures the 00:03:25.53000:03:25.540 heat from hot oil inside the tube is 00:03:27.86900:03:27.879 conducted through the tube wall to the 00:03:30.17900:03:30.189 cooler liquid in the shell the hot oil 00:03:32.81900:03:32.829 becomes cooler while the cool water 00:03:35.28000:03:35.290 absorbs heat in this heat exchanger the 00:03:39.80900:03:39.819 fluids are being pumped through the 00:03:41.28000:03:41.290 vessel this causes turbulence a 00:03:43.77000:03:43.780 disturbance and flow turbulence results 00:03:47.00900:03:47.019 in a faster more efficient flow of 00:03:49.05000:03:49.060 energy velocity also influences the rate 00:03:54.05900:03:54.069 at which heat moves between two fluids 00:03:56.22000:03:56.230 of different temperatures water that 00:03:58.47000:03:58.480 travels too quickly can absorb enough 00:04:00.53900:04:00.549 heat the optimum velocity represents the 00:04:03.42000:04:03.430 most efficient heat transfer another 00:04:06.17900:04:06.189 consideration for efficiency is the area 00:04:08.69900:04:08.709 of contact the greater the surface area 00:04:11.55000:04:11.560 the more heat will be transferred to 00:04:13.58000:04:13.590 ensure a large surface area most heat 00:04:16.77000:04:16.780 exchangers have a system of tubes inside 00:04:18.99000:04:19.000 the liquid in these tubes is referred to 00:04:21.47900:04:21.489 as tube side flow another liquid is 00:04:24.96000:04:24.970 directed through the space around the 00:04:26.76000:04:26.770 tubes this is called the shell side flow 00:04:29.33900:04:29.349 by having many tubes more heat can be 00:04:32.49000:04:32.500 transferred so far we've discussed 00:04:35.70000:04:35.710 conduction heat transfer by direct 00:04:38.31000:04:38.320 contact convection heat transfer by 00:04:41.18900:04:41.199 current movement and several factors 00:04:43.46900:04:43.479 that influence the efficiency of heat 00:04:45.24000:04:45.250 exchangers including temperature 00:04:47.49000:04:47.500 difference conducting material fluid 00:04:50.61000:04:50.620 turbulence fluid velocity and surface 00:04:53.25000:04:53.260 area in addition to these another factor 00:04:56.49000:04:56.500 that affects efficiency is the direction 00:04:58.35000:04:58.360 of flow you'll learn about this factor 00:05:00.62900:05:00.639 in the workbook stop the tape and turn 00:05:03.27000:05:03.280 to workbook period 1 be sure to complete 00:05:05.96900:05:05.979 all the self teaching frames as directed 00:05:11.96000:05:11.970 in this section of the program you will 00:05:15.56000:05:15.570 learn about heat exchanger design 00:05:17.29000:05:17.300 including flow arrangements because tube 00:05:20.84000:05:20.850 heat exchangers are the most prevalent 00:05:22.40000:05:22.410 the program addresses problems that 00:05:24.89000:05:24.900 arise when using tube heat exchangers 00:05:27.02000:05:27.030 and solutions to these problems 00:05:29.45000:05:29.460 there are several designs for heat 00:05:31.58000:05:31.590 exchangers in addition these designs are 00:05:34.34000:05:34.350 varied as necessary depending upon the 00:05:36.47000:05:36.480 characteristics of the process fluid in 00:05:38.62000:05:38.630 general there are plate and tube heat 00:05:41.66000:05:41.670 exchangers each transfers heat from one 00:05:44.42000:05:44.430 fluid to another this is a plate heat 00:05:48.05000:05:48.060 exchanger note its form and size as its 00:05:52.19000:05:52.200 name implies it's made of corrugated 00:05:54.26000:05:54.270 plates the plates are held together with 00:05:56.99000:05:57.000 an external pressure plate that can be 00:05:58.97000:05:58.980 moved for maintenance and cleaning 00:06:01.30000:06:01.310 internally fluids enter each plate 00:06:04.04000:06:04.050 compartment the flow is set up so that 00:06:06.50000:06:06.510 the plates with hot liquid alternate 00:06:08.48000:06:08.490 with those containing cooler liquids 00:06:10.66000:06:10.670 large surface areas and the natural 00:06:13.52000:06:13.530 turbulence caused by the corrugated 00:06:15.26000:06:15.270 metal plates allow for efficient heat 00:06:17.57000:06:17.580 transfer plate heat exchangers may be 00:06:21.47000:06:21.480 used because of the specific demands put 00:06:23.81000:06:23.820 on the system by the characteristics of 00:06:26.00000:06:26.010 the process chemicals for example for a 00:06:28.85000:06:28.860 highly corrosive chemical that must be 00:06:30.95000:06:30.960 cooled a titanium plate heat exchanger 00:06:33.74000:06:33.750 may be best another type of heat 00:06:36.23000:06:36.240 exchanger and the most common is the 00:06:38.42000:06:38.430 tube heat exchanger its design consists 00:06:41.65900:06:41.669 of a set of metal tubes carrying one 00:06:44.42000:06:44.430 fluid and the space around those tubes 00:06:47.09000:06:47.100 known as the shell carrying another 00:06:49.10000:06:49.110 fluid as we'll see the internal 00:06:51.89000:06:51.900 arrangement of the tube heat exchanger 00:06:53.72000:06:53.730 is critical for efficient heat transfer 00:06:57.04000:06:57.050 to increase the amount of heat transfer 00:06:59.90000:06:59.910 the tube side fluid can be put through 00:07:02.24000:07:02.250 the exchanger more than once to do this 00:07:04.82000:07:04.830 a channel baffle is built into the head 00:07:07.13000:07:07.140 of the exchanger this baffle or 00:07:09.98000:07:09.990 partition directs the flow through half 00:07:12.23000:07:12.240 of the tubes in one direction and 00:07:13.97000:07:13.980 through the other half in the opposite 00:07:16.15900:07:16.169 direction 00:07:18.40000:07:18.410 here is a channel head baffle that 00:07:20.80900:07:20.819 directs the tube side fluid through the 00:07:22.79000:07:22.800 exchanger two times every time the hot 00:07:25.82000:07:25.830 fluid makes a pass through one channel 00:07:27.32000:07:27.330 it gives up more heat increasing the 00:07:30.23000:07:30.240 number of tube side passes improves the 00:07:32.27000:07:32.280 efficiency of an exchanger the shell 00:07:36.20000:07:36.210 side flow can also be changed to produce 00:07:38.68900:07:38.699 high efficiency as these longitudinal 00:07:41.20000:07:41.210 baffles force the shell side fluid to 00:07:44.02900:07:44.039 flow back and forth over the tube bundle 00:07:46.39900:07:46.409 with each pass shell side fluid absorbs 00:07:49.30900:07:49.319 more heat another arrangement involves 00:07:52.55000:07:52.560 segmental baffles they can be cut 00:07:55.12900:07:55.139 vertically or horizontally and they're 00:07:57.35000:07:57.360 positioned to face in alternate 00:07:58.87900:07:58.889 directions these baffles will allow the 00:08:01.67000:08:01.680 fluid to flow across the tubes a number 00:08:04.18900:08:04.199 of times and keep the fluid turbulent 00:08:06.52900:08:06.539 the more turbulence the more energy is 00:08:09.26000:08:09.270 transferred segmental baffles can direct 00:08:12.49900:08:12.509 the flow to be horizontal or vertical 00:08:14.32000:08:14.330 depending upon the fluid being used if 00:08:17.05900:08:17.069 the liquid is dirty the sediment will 00:08:19.99900:08:20.009 often build up behind a horizontal 00:08:22.01000:08:22.020 baffle this decreases efficiency by 00:08:24.95000:08:24.960 blocking the flow if the force of the 00:08:28.39900:08:28.409 fluid entering the shell is too great 00:08:30.55000:08:30.560 impingement baffles may be used these 00:08:33.50000:08:33.510 baffles direct flow to the sides of the 00:08:35.71900:08:35.729 exchanger which reduces internal erosion 00:08:38.30000:08:38.310 in addition the fluid contacts more 00:08:41.18000:08:41.190 surface area and increases efficiency 00:08:45.10000:08:45.110 despite careful design considerations 00:08:48.05000:08:48.060 there are some problems that occur 00:08:49.94000:08:49.950 whenever two fluids with different 00:08:51.92000:08:51.930 temperatures run through the same piece 00:08:54.01900:08:54.029 of equipment this is because metal 00:08:56.56900:08:56.579 expands and contracts in length because 00:08:59.18000:08:59.190 of changes in the temperature even under 00:09:01.73000:09:01.740 normal operating conditions this natural 00:09:04.16000:09:04.170 process will stress certain parts of the 00:09:06.31900:09:06.329 exchanger in a fixed tube sheet 00:09:09.07900:09:09.089 exchanger the tubes and tube sheets are 00:09:11.60000:09:11.610 permanently attached or fixed to the 00:09:14.00000:09:14.010 shell of the exchanger whatever these 00:09:16.37000:09:16.380 parts expand and contract the tube 00:09:18.88900:09:18.899 joints undergo stress eventually this 00:09:21.76900:09:21.779 stress may cause leaks to develop at the 00:09:23.87000:09:23.880 tube joints 00:09:26.26900:09:26.279 there are basically three designs that 00:09:28.69900:09:28.709 deal with the possibility of leakage 00:09:31.78000:09:31.790 thumb fix tube sheet exchangers the tube 00:09:35.32900:09:35.339 bundle is anchored between double tube 00:09:37.30900:09:37.319 sheets if a leak does occur the fluid 00:09:40.61000:09:40.620 flows into the space between the tube 00:09:42.61900:09:42.629 sheets and can be safely drained from 00:09:44.90000:09:44.910 the exchanger this design may lessen the 00:09:49.22000:09:49.230 effect of a leak but it cannot lessen 00:09:51.61900:09:51.629 the stress that thermal expansion puts 00:09:53.68900:09:53.699 on the tubes a fixed tube sheet 00:09:56.32900:09:56.339 exchanger can only be used where the 00:09:58.36900:09:58.379 temperature difference between the two 00:09:59.86900:09:59.879 fluids is small the next example is a 00:10:03.47000:10:03.480 tube bundle from a you tube exchanger in 00:10:05.92900:10:05.939 this type the tubes are free to expand 00:10:08.92900:10:08.939 because they're only attached at one end 00:10:10.97000:10:10.980 of the tube sheet so a you tube 00:10:13.00900:10:13.019 exchanger can handle fluids that vary 00:10:15.13900:10:15.149 greatly in temperature although the you 00:10:17.80900:10:17.819 tube bundle can be removed from the 00:10:19.48900:10:19.499 shell the bends in the tubes hinder 00:10:22.34000:10:22.350 internal inspection and cleaning a third 00:10:27.98000:10:27.990 type of exchanger is designed to allow 00:10:30.19900:10:30.209 both thermal expansion and easy 00:10:32.48000:10:32.490 maintenance because only one tube sheet 00:10:35.38900:10:35.399 is fixed while the other floats 00:10:36.98000:10:36.990 horizontally this is called a floating 00:10:39.37900:10:39.389 head exchanger the tubes are free to 00:10:42.23000:10:42.240 expand and contract in response to the 00:10:44.90000:10:44.910 temperature changes without stressing 00:10:46.75900:10:46.769 the joints and the bundle and floating 00:10:49.22000:10:49.230 head can be removed for cleaning and 00:10:51.23000:10:51.240 inspection when necessary this cutaway 00:10:54.07900:10:54.089 view of a floating head exchanger shows 00:10:56.21000:10:56.220 you one disadvantage of its design there 00:10:59.17900:10:59.189 is a clearance space between the shell 00:11:01.06900:11:01.079 and tubes it's needed so that the bundle 00:11:04.00900:11:04.019 can be removed for maintenance the shell 00:11:07.00900:11:07.019 side liquid will tend to flow through 00:11:08.99000:11:09.000 this space an area that offers little 00:11:11.24000:11:11.250 resistance when this happens efficiency 00:11:14.05900:11:14.069 decreases because the shell side fluid 00:11:16.12900:11:16.139 does not come into contact with enough 00:11:18.59000:11:18.600 tube surface we've covered a lot of 00:11:22.85000:11:22.860 material in this section dealing with 00:11:24.82900:11:24.839 the internal flow arrangements and 00:11:26.60000:11:26.610 problems that may occur to summarize 00:11:29.62900:11:29.639 there are several types of baffles that 00:11:31.93900:11:31.949 affect flow channel head longitudinal 00:11:35.74000:11:35.750 segmental and impingement 00:11:39.16000:11:39.170 expansion and contraction cause stress 00:11:41.84000:11:41.850 this can be managed in several ways with 00:11:45.37900:11:45.389 the double tube sheet to collect leaks 00:11:47.53000:11:47.540 with a u-tube exchanger to allow for 00:11:50.36000:11:50.370 expansion and the floating head 00:11:53.05900:11:53.069 exchanger which makes cleaning and 00:11:55.06900:11:55.079 inspection easy to review this 00:11:58.40000:11:58.410 information and to learn more about heat 00:12:00.31900:12:00.329 exchanger design stop the tape and turn 00:12:02.93000:12:02.940 to workbook period 2 in discussing heat 00:12:06.35000:12:06.360 exchangers thus far we've examined 00:12:08.66000:12:08.670 factors that affect their efficiency and 00:12:10.79000:12:10.800 we've looked at design issues in this 00:12:13.40000:12:13.410 final segment we'll cover specific 00:12:15.37900:12:15.389 applications and general maintenance the 00:12:18.55900:12:18.569 heat exchangers we've seen up to now 00:12:20.09000:12:20.100 have all been used to heat a process 00:12:22.46000:12:22.470 liquid in some instances however the 00:12:25.40000:12:25.410 purpose of heat exchange is to remove 00:12:27.62000:12:27.630 heat from a fluid that requires cooling 00:12:30.10000:12:30.110 suppose we wanted to convert steam 00:12:32.32900:12:32.339 generated by one process into feed water 00:12:35.30000:12:35.310 for another process to do this a shell 00:12:38.78000:12:38.790 and tube exchanger can be used as a 00:12:40.55000:12:40.560 condenser this cutaway will show how the 00:12:43.93900:12:43.949 condenser works water enters the space 00:12:47.24000:12:47.250 between the head of the shell and the 00:12:49.18900:12:49.199 adjacent tube sheet and flows through 00:12:51.62000:12:51.630 the tubes to the opposite end steam 00:12:54.35000:12:54.360 enters at the top of the shell and flows 00:12:56.26900:12:56.279 down and between the condensers tubes 00:12:58.74900:12:58.759 when the steam is cooled it condenses to 00:13:01.75900:13:01.769 water and falls into the hot well at the 00:13:04.10000:13:04.110 bottom of the condenser air also may be 00:13:07.37000:13:07.380 used to cool steam here a fan blows air 00:13:10.67000:13:10.680 across tubes that carry steam although 00:13:13.73000:13:13.740 not as efficient as water the air 00:13:15.67900:13:15.689 absorbs heat from the steam and the 00:13:17.68900:13:17.699 steam condenses an air cooled system may 00:13:21.11000:13:21.120 be used if water is scarce another 00:13:25.37000:13:25.380 application for heat exchangers is as a 00:13:27.74000:13:27.750 reboiler reboilers are used in systems 00:13:30.82900:13:30.839 that heat and vaporize hydrocarbons this 00:13:36.07900:13:36.089 one is a kettle type reboiler it is 00:13:38.78000:13:38.790 simply a shell and tube exchangers 00:13:40.85000:13:40.860 surrounded by an enlarged shell that 00:13:42.82900:13:42.839 accommodates vapor let's examine the 00:13:45.53000:13:45.540 system 00:13:46.59000:13:46.600 this system includes a distillation 00:13:48.54000:13:48.550 tower a furnace and a kettle type 00:13:51.50900:13:51.519 reboiler the furnace heats oil which is 00:13:54.87000:13:54.880 pumped through the tubes of the reboiler 00:13:57.68000:13:57.690 meanwhile liquid isobutane flows from 00:14:01.13900:14:01.149 the bottom of the distillation column 00:14:02.51900:14:02.529 into the shell of the reboiler the heat 00:14:05.61000:14:05.620 from the oil is transferred through the 00:14:07.41000:14:07.420 tube walls and vaporizes some of the 00:14:10.01900:14:10.029 isobutane the isobutane vapors are then 00:14:13.55900:14:13.569 channeled into the distillation column 00:14:15.35000:14:15.360 these vapors provide the heat needed for 00:14:18.50900:14:18.519 distillation to take place the isobutane 00:14:21.66000:14:21.670 vapors lose heat condense and fall to 00:14:24.93000:14:24.940 the bottom of the tower starting the 00:14:26.79000:14:26.800 cycle again coolers are heat exchangers 00:14:30.56900:14:30.579 - as the name implies coolers lower the 00:14:33.99000:14:34.000 temperature of the liquid or vapor in 00:14:36.53000:14:36.540 the next example kerosene is being 00:14:39.32900:14:39.339 cooled before going to storage cooling 00:14:42.66000:14:42.670 water passes through the exchanger twice 00:14:44.93900:14:44.949 while the kerosene makes only a single 00:14:47.51900:14:47.529 pass as the kerosene moves through the 00:14:50.30900:14:50.319 exchanger it releases some of its heat 00:14:52.55900:14:52.569 to the water the baffles keep the flow 00:14:55.07900:14:55.089 of the kerosene turbulent ensuring 00:14:57.30000:14:57.310 maximum contact between the kerosene and 00:14:59.79000:14:59.800 the tubes with this contact ensured the 00:15:02.37000:15:02.380 kerosene is cooled efficiently and can 00:15:04.94900:15:04.959 then be stored safely the final 00:15:07.80000:15:07.810 application that we'll look at is one 00:15:09.62900:15:09.639 that converts waste heat into valuable 00:15:11.97000:15:11.980 steam the heat exchanger used for this 00:15:14.75900:15:14.769 purpose is called a waste heat reboiler 00:15:17.38900:15:17.399 let's look at a diagram of a typical 00:15:19.92000:15:19.930 waste heat system the main components 00:15:23.63900:15:23.649 are a steam drum a waste heat boiler and 00:15:27.90000:15:27.910 a distillation column water from the 00:15:31.94900:15:31.959 steam drum is sent through the tubes of 00:15:34.07900:15:34.089 the waste heat boiler while hot oil from 00:15:36.30000:15:36.31000:15:37.62000:15:37.630 moves through the shell as water absorbs 00:15:41.63900:15:41.649 heat from the oil part of it is 00:15:43.67900:15:43.689 vaporized and turns to steam the steam 00:15:46.37900:15:46.389 carries small droplets of water through 00:15:48.87000:15:48.880 the boiler this mixture of steam and 00:15:52.13900:15:52.149 water droplets flows up into the steam 00:15:54.44900:15:54.459 drum here the two fluids are separated 00:15:57.36000:15:57.370 from one another 00:15:58.23000:15:58.240 the steam is sent to the plant steam 00:16:00.84000:16:00.850 system while the water is channeled back 00:16:03.26900:16:03.279 to the boiler as you know all the 00:16:07.88900:16:07.899 equipment involved in these applications 00:16:09.92900:16:09.939 requires periodic maintenance for this 00:16:12.62900:16:12.639 reason will now discuss some basic 00:16:14.51900:16:14.529 operating problems and how to handle 00:16:16.50000:16:16.510 them fouling is a common and destructive 00:16:19.71000:16:19.720 enemy of heat exchange a low velocity 00:16:22.43900:16:22.449 flow can start the build-up of deposits 00:16:24.66000:16:24.670 on internal surfaces these deposits can 00:16:27.62900:16:27.639 cause changes in temperature and 00:16:29.37000:16:29.380 pressure the deposits have several 00:16:32.46000:16:32.470 sources process fluids may contain solid 00:16:35.69900:16:35.709 sediments once they settle a restriction 00:16:38.69900:16:38.709 to the flow develops and the restriction 00:16:40.92000:16:40.930 then causes more settling corrosion is 00:16:44.87900:16:44.889 produced when the metal of the exchanger 00:16:46.74000:16:46.750 interacts chemically with the process 00:16:48.68900:16:48.699 stream these deposits can break free 00:16:51.17900:16:51.189 eventually and follow the exchanger 00:16:53.69900:16:53.709 tubes the warm exchanger provides a 00:16:56.85000:16:56.860 comfortable environment for the growth 00:16:58.29000:16:58.300 of certain organisms the tube surfaces 00:17:01.23000:17:01.240 may become contaminated with algae there 00:17:05.25000:17:05.260 are several ways to control fouling in a 00:17:07.74000:17:07.750 heat exchanger one way is to add 00:17:10.04900:17:10.059 dispersants these will prevent insoluble 00:17:13.02000:17:13.030 materials like dirt from forming solid 00:17:15.29900:17:15.309 deposits another control method is to 00:17:18.60000:17:18.610 add chemical inhibitors that will keep 00:17:20.52000:17:20.530 chemical reactions from taking place or 00:17:23.56900:17:23.579 antifouling can be added to the process 00:17:26.01000:17:26.020 streams these chemicals prevent 00:17:28.43900:17:28.449 biological growth after fouling has 00:17:33.45000:17:33.460 occurred removal methods depend on the 00:17:35.76000:17:35.770 type and severity of the deposits 00:17:37.68000:17:37.690 deposits on the outside of tubes can 00:17:40.44000:17:40.450 often be removed by hydro blaster a 00:17:42.84000:17:42.850 high-pressure stream of water that 00:17:44.90900:17:44.919 loosens and washes away the deposits 00:17:47.65900:17:47.669 streams of water or steam can also move 00:17:50.88000:17:50.890 the deposits from the inside of a tube 00:17:52.88900:17:52.899 if water and steam fail chemical 00:17:56.43000:17:56.440 cleaning may dissolve the deposits if 00:17:58.47000:17:58.480 however the deposits resist both 00:18:00.77900:18:00.789 chemical cleaning and hydro blasting the 00:18:03.57000:18:03.580 exchanger must be completely dismantled 00:18:05.85000:18:05.860 and the deposits scraped off at this 00:18:08.46000:18:08.470 point it may be best to retube the 00:18:10.59000:18:10.600 exchanger 00:18:11.58000:18:11.590 as always during shutdown and startup 00:18:14.46000:18:14.470 workers must follow safety precautions 00:18:17.12000:18:17.130 nitrogen and other inert gases are used 00:18:19.68000:18:19.690 to purge the exchanger of hydrocarbons 00:18:22.26000:18:22.270 and air these gases can get trapped 00:18:24.99000:18:25.000 inside the exchanger where they 00:18:26.61000:18:26.620 interfere with the heat transfer process 00:18:28.94000:18:28.950 these gases can be released by venting 00:18:32.19000:18:32.200 according to the procedure specific to 00:18:34.11000:18:34.120 your unit condensers are susceptible to 00:18:38.85000:18:38.860 problems caused by other gases as well 00:18:41.29900:18:41.309 one problem occurs when air leaks 00:18:43.91900:18:43.929 restrict the flow of water by causing 00:18:46.01900:18:46.029 vapor binding to eliminate vapor binding 00:18:48.93000:18:48.940 open the vent in the water exit line 00:18:51.44000:18:51.450 another problem is a reduction in 00:18:54.06000:18:54.070 cooling capacity this can occur when non 00:18:57.14900:18:57.159 condensable gases are present in the 00:18:59.13000:18:59.140 process side of the condenser you can 00:19:01.71000:19:01.720 correct this type of problem by venting 00:19:03.72000:19:03.730 the process side of the condenser to 00:19:05.76000:19:05.770 release the trapped vapors leaks are 00:19:10.04900:19:10.059 another important maintenance concern 00:19:12.29900:19:12.309 whenever exchangers are down for 00:19:14.54900:19:14.559 cleaning they're almost always tested 00:19:16.59000:19:16.600 for leaks 00:19:17.22000:19:17.230 but before dismantling the exchanger 00:19:19.79900:19:19.809 there are some preliminary tests you can 00:19:21.75000:19:21.760 perform one simple way to test for 00:19:24.63000:19:24.640 leakage is to take a sample of the lower 00:19:26.78900:19:26.799 pressure fluid and check it for 00:19:28.38000:19:28.390 contamination if the fluids are very 00:19:31.13900:19:31.149 different in appearance like oil and 00:19:33.18000:19:33.190 water just looking at the sample should 00:19:35.82000:19:35.830 tell you if there's a leak this sample 00:19:38.46000:19:38.470 for example has a small amount of oil in 00:19:40.68000:19:40.690 the waterline a sure sign of a leak 00:19:43.37000:19:43.380 however if the fluids are very similar 00:19:45.93000:19:45.940 in appearance chemical testing may be 00:19:47.97000:19:47.980 needed to detect the results of a leak 00:19:49.83000:19:49.840 this must be done in the lab if neither 00:19:53.49000:19:53.500 the visual nor the chemical tests are 00:19:55.59000:19:55.600 conclusive a test using high-pressure 00:19:57.84000:19:57.850 water may be done this is called 00:20:00.44000:20:00.450 hydrostatic testing before it can be 00:20:03.24000:20:03.250 done the exchanger must be taken offline 00:20:05.37000:20:05.380 and drained if you're checking for tube 00:20:09.45000:20:09.460 side leakage the tubes are filled with 00:20:11.58000:20:11.590 water under pressure if the tubes or 00:20:14.25000:20:14.260 joints are leaking the water will be 00:20:16.32000:20:16.330 forced through the leak points into the 00:20:18.45000:20:18.460 shell 00:20:19.01900:20:19.029 if tests indicate a leak the exchanger 00:20:22.79900:20:22.809 must be partially dismantled to 00:20:24.51000:20:24.520 determine its 00:20:25.95000:20:25.960 to find a leaking tube the shell is 00:20:28.50000:20:28.510 filled with water under pressure this 00:20:31.11000:20:31.120 water will enter the tube at the point 00:20:33.02900:20:33.039 of the leak and then run out the tube 00:20:34.71000:20:34.720 end by watching the tube sheath you can 00:20:38.19000:20:38.200 often tell exactly which tube is leaking 00:20:40.73000:20:40.740 these procedures will help ensure proper 00:20:43.64900:20:43.659 operations and warn of problems before 00:20:46.16900:20:46.179 the situation gets out of hand in this 00:20:49.68000:20:49.690 program you've been introduced to two 00:20:51.81000:20:51.820 methods of transferring heat conduction 00:20:54.36000:20:54.370 and convection you've seen that heat 00:20:57.65900:20:57.669 exchangers can meet the plants needs 00:20:59.63900:20:59.649 efficiently depending on their design 00:21:02.00900:21:02.019 for both heating and cooling purposes 00:21:04.34000:21:04.350 you've also seen the importance of 00:21:06.77900:21:06.789 regular maintenance for the final review 00:21:09.77900:21:09.789 open your workbooks to period 3 thanks 00:21:13.28900:21:13.299 for watching
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Engineering company LOTUS®
Russia, Ekaterinburg, Lunacharskogo street, 240/12