Heat Exchangers 61 Table 3-3 Tube Materials Sweer Senice Glycol, MEA, and Sulfinol Temperatures above ~20°F, A-2 14 ERW or A- 1 79 (seamless) -50°F to -21°F, A-334 Grade 1 - 1 50°F to -5 1 °F, A334 Grade 3 Sour ami Low Temperature 304 SS Brackish Water 90/10Cu-Ni 70/30 Cu-Ni Use higher nickel content the more brackish the water Sizing The required heat duty, film coefficients, conductivity, etc. for a shell- and-tube heat exchanger can be calculated using the procedures in Chap- ter 2, Approximate U-values are given in Table 2-8. In the basic heat transfer equation it is necessary to use the log mean temperature difference. In Equation 2-4 it was assumed that the two flu- ids are flowing counter-current to each other. Depending upon the con- figuration of the exchanger, this may not be true. That is, the way in which the fluid flows through the exchanger affects LMTD. The correc- tion factor is a function of the number of tube passes and the number of shell passes. Figures 3-10 and 3-11 can be used to calculate a corrected LMTD from the formula. where Tj = hot fluid inlet temperature, °F T 2 = hot fluid outlet temperature, °F T 3 = cold fluid inlet temperature, °F T 4 = cold fluid outlet temperature, °F AT] = larger temperature difference, °F AT 2 = smaller temperature difference, °F LMTD = log mean temperature difference, °F F = correction factor (text continued on page 64) 62 Design of GAS-HANDLING Systems and Facilities Figure 3-10. LMTD correction factors. (From Gas Processors Suppliers Association, Engineering Data Book, 9th Edition.) Heat Exchangers 63 Figure 3-11. LMTD correction factors. (From Gas Processors Suppliers Association, Engineering Data Book, 9th Edition.) 64 Design of GAS-HANDLING Systems and Facilities (text continued from page 61) To size a shell-and-tube exchanger, first the duty is calculated. Then it is determined which fluid will be in the shell and which in the tube, and a heat* transfer coefficient assumed or calculated. A choice is made of the number of shell and tube passes to get a reasonable LMTD correction factor (F), and a corrected LMTD as calculated from Equation 3-1. Next, a tube diameter and tube length are chosen. The number of tubes required is calculated by: where N = required number of tubes q = heat duty, Btu/hr U = overall heat transfer coefficient, Btu/hr-ft 2 -°F LMTD = corrected log mean temperature difference, °F L = tube length, ft A' = tube external surface area per foot of length, ft 2 /ft (Table 2-1) From Table 3-4 it is then possible to pick a shell diameter that can accommodate the number of tubes required. Please note that Equation 3- 2 calculates the total number of tubes required and not the number of tubes per pass. Similarly, Table 3-4 lists the total number of tubes and not the number per pass. There are fewer total tubes in the same diameter exchanger for more passes of the tube fluid because of the need for parti- tion plates. There are fewer tubes for floating head than fixed head designs because the heads and seals restrict the use of space. U-tubes have the lowest number of tubes because of the space required for the tightest radius bend in the U-tube bundle. Once the number of tubes is determined, the flow velocity of fluid inside the tubes should be checked, using the criteria set forth for flow in pipes in Chapter 8 of Volume 1. Heat Exchangers 65 DOUBLE-PIPE EXCHANGERS A double-pipe exchanger is made up of one pipe containing the tube fluid concentric with another pipe, which serves as the shell. The tube is often finned to give additional surface area. The double-pipe exchanger was developed to fit applications that are too small to economically apply the requirements of TEMA for shell and tube exchangers. Double-pipe exchangers can be arranged as in Figure 3-12 such that two shells are joined at one end through a "return bonnet," which causes the shell-side fluid to flow in series through each of the two shells. In this configuration, the central tube is bent or welded into a "U" shape, with the U-bend inside the return bonnet, The principal advantage to this con- figuration is that a more compact exchanger can be designed, thus sim- plifying installation. A variation of the U-tube exchanger is the hairpin style of exchanger. In the hairpin exchanger, multiple small tubes are bent into a "U" shape in place of the single central tube. This variation allows for more surface area to be provided in the exchanger than would be obtained with a sin- gle tube. U-tube exchangers may be designed with or without fins. The advantages of double-pipe exchangers are that they are cheap and readily available, and because of the U-tube type of construction, thermal expansion is not a problem. Double-pipe exchangers are normally designed and built in accordance with the applicable requirements of TEMA. Thus, they can be applied to most services encountered in oil and gas production facilities as long as the required surface area can be fit into the physical configuration of the exchanger. Although they can be built in almost any size, double-pipe exchangers are most frequently used when the required surface area is 1,000 ft 2 or less. PLATE-AND-FRAME EXCHANGERS Plate-and-frame exchangers are an arrangement of gasketed, pressed metal plates aligned on carrying bars and secured between two covers by compression bolts. The pressed metal plates are corrugated in patterns to provide increased surface area, to direct the flow in specific directions, and to promote turbulence. The plates are gasketed such that each of the (text continued on page 72) on next pagf) Table 3-4 (Continued) Heat Exchanger Tube Count 1 Shdl I.D. (Inches) 5.047 6.065 7.981 10.02 12.00 13.25 15.25 17.25 19.25 21.25 23.25 25.00 ! 27.00 29.00 ; 3i.oo 33.00 35.00 37.00 39.00 42.00 45,00 48.00 5 1 ,00 54.00 60,00 3/4" O.D. Tubes on 1 5/ 1 6" A Piteh 3/4- O .D. Tubes on ! " A Pilch Fixed T Tube Sheet No. of Passes 1 19 25 52 85 126 147 206 268 335 416 499 576 675 790 806 1018 1166 1307 1464 1688 1943 2229 2513 2823 2 14 20 48 76 114 140 196 252 326 397 480 558 661 773 875 ton 1137 1277 1425 1669 1912 2189 2489 4 12 16 36 68 100 128 176 234 302 376 460 530 632 736 858 976 1098 1242 1386 1618 1878 2134 2432 2792 2752 3527 1 3477 3414 Outside Packed Floating Head No. of Passes 1 10 19 38 70 109 130 187 241 313 384 469 544 643 744 859 973 1118 1253 1392 1616 1870 2145 2411 2733 3400 2 10 18 36 66 98 126 176 236 298 368 449 529 616 732 835 959 1093 1224 1359 1602 1833 2107 2395 2683 3359 4 4 12 28 56 92 112 160 220 276 344 430 500 600 704 812 926 1054 1184 1318 1552 1800 2060 2344 2642 3294 1 — ' ' "U"-Tube No. of Passes 2 3 7 16 28 56 57 83 110 145 180 220 253 307 360 415 477 538 609 683 800 927 1061 1205 1366 1699 j 4 2 4 12 26 40 52 74 102 134 170 1 Shell 210 244 290 342 402 458 520 592 662 776 900 1032 1178 1334 1668 l.D, (Inches) 5.047 6.065 7.981 10.02 12.00 13.25 15.25 17.25 19.25 21.25 23.25 25.00 27.00 29.00 31.00 33.00 35.00 37.00 39.00 42.00 45.00 48,00 51,00 54.00 60.00 Fixed Tube Sheet No. of Passes ! 14 22 42 71 106 130 184 237 296 361 434 507 596 689 790 906 1031 1152 1273 1485 1721 1968 2221 2502 3099 2 14 19 38 68 102 124 169 228 290 354 420 489 585 679 775 891 1003 1134 1259 1461 1693 1941 2187 2465 3069 4 8 16 36 60 92 114 160 212 272 336 408 476 562 660 756 860 976 1090 1222 1434 1650 1902 2134 2414 3010 Outside Packed Floating Head No. of Passes ] 10 19 37 61 92 121 163 212 268 335 416 475 556 653 756 859 978 1106 1218 1426 1652 1894 2142 2417 2990 2 6 14 30 56 90 110 152 202 262 330 395 466 554 642 734 848 959 1081 1208 1399 1620 1861 2101 2379 2957 . 4 4 12 28 48 76 100 140 188 244 308 380 452 528 620 720 818 932 1054 1174 1376 1586 1820 2060 2326 2906 "U"-Tube No, of Passes 2 3 5 14 28 43 53 74 100 127 157 194 226 269 316 366 419 475 537 600 703 816 935 1061 4 2 4 12 22 36 48 68 92 120 150 184 216 262 306 354 404 458 520 582 682 792 916 1038 1198 1170 | 1496 1468 | (table continued on next page) Table 3-4 (Continued) Heat Exchanger Tube Count (table on ne\l fmsffi 3/4" O.D. Tubes on 1 " C Pilch 3/4" O,D. Tubes on 1 " Pilch Shell I.D. (Inches) 5.047 6.065 7.981 10.02 12.00 13.25 15.25 17.25 19.25 21.25 23.25 25.00 27.00 29.00 31.00 33.00 35.00 37,00 39.00 42.00 45.00 4X00 51 00 M HO nOOO Fixed Tube Sheet No. of Passes 1 12 21 37 61 97 112 156 208 250 316 378 442 518 602 686 782 896 1004 1102 12X3 1484 1701 1928 "•154 2683 2 12 16 34 60 88 112 148 196 249 307 370 432 509 596 676 768 868 978 1096 1285 1472 169! 4 12 16 32 52 88 112 148 188 244 296 370 428 496 580 676 768 868 964 1076 1270 1456 1670 1904 ! 1888 •^Px j 2106 i 2650 2o^6 Outside Packed Floating Head No. of Passes 1 12 16 32 52 81 97 140 188 241 296 356 414 482 570 658 742 846 952 1062 1232 1424 1636 1845 2 6 16 28 52 78 94 132 178 224 280 344 406 476 562 640 732 831 931 1045 1222 1415 1634 1832 2080 | 206f 4 4 12 24 52 76 88 124 172 216 276 332 392 468 548 640 732 820 928 1026 1218 1386 1602 1818 2(W4 i i 25X2 :56(- i J55n "U"-Tube No. of Passes 2 3 4 12 22 34 45 64 88 112 138 170 200 236 277 320 362 418 470 524 till 710 812 «26 1042 1298 4 2 4 10 20 34 44 60 84 108 134 166 194 230 272 312 360 406 462 520 602 700 802 910 Shell ! l.D. (Inches) 5.047 6.065 7.981 10.02 12.00 13.25 15.25 17.25 19.25 21.25 23.25 25,00 27.00 29.00 31.00 33.00 35.00 37.00 39.00 42.00 4500 48 OT 51 00 HH2 1 i MOO i 1 1282 \ J W.OO Fixed Tube Sheet No. of Passes 1 12 21 37 61 97 113 156 208 256 314 379 448 522 603 688 788 897 1009 1118 1298 1500 1714 2 10 18 32 54 90 108 146 1% 244 299 363 432 504 583 667 770 873 983 1092 1269 1470 lh81 4 8 16 28 48 84 104 136 184 236 294 352 416 486 568 654 756 850 958 1066 1250 1440 1650 1Q« j i<)03 1 1868 217- .135 2'Wn l 2692 2»ol j 2h\2 Outside Packed Floating Head No, of Passes 1 12 16 32 52 81 97 140 188 241 300 359 421 489 575 660 749 849 952 1068 1238 1432 1644 1864 209X 2600 2 10 12 28 46 74 92 134 178 228 286 343 404 472 556 639 728 826 928 1041 1216 1407 1611 183" 1062 4 8 8 24 40 68 84 128 168 216 272 328 392 456 540 624 708 804 908 1016 1196 1378 1580 1804 2026 i Ii60 ; 2520 "U"-Tube No. of Passes 2 2 5 12 21 33 43 62 87 109 136 167 195 234 275 313 360 409 464 518 610 706 804 4 2 4 10 18 32 40 58 82 104 130 160 190 226 266 304 350 398 452 508 596 692 788 917 [ i)02 ' 1018 i )2t)2 j !2"2 Table 3-4 (Continued) Heat Exchanger Tube Count 1" O.D. Tubes on 1-1/4" A Pitch ]» O ,D» Tubes on M/4" a Pitch Shell I.D, (inches) 5.047 6.065 7.981 10.02 12.00 13,25 15.25 17.25 19.25 21.25 23.25 25.00 27.00 29.00 31.00 33.00 35.00 37.00 39.00 42.00 45.00 48.00 51.00 54.00 60.00 Fixed „ Tube Sheer No. of Passes 1 8 14 26 42 64 85 110 147 184 227 280 316 371 434 503 576 643 738 804 946 1087 1240 1397 1592 1969 2 6 14 26 40 61 76 106 138 175 220 265 313 370 424 489 558 634 709 787 928 1069 1230 1389 1561 1945 4 4 8 16 36 56 72 100 128 168 212 252 294 358 408 468 534 604 684 772 898 1042 1198 1354 1530 1 904 Outside Packed Floating Head No. of Passes 1 7 10 22 38 56 73 100 130 170 212 258 296 355 416 475 544 619 696 768 908 1041 1189 1348 1531 1906 2 4 10 18 36 52 72 98 126 162 201 250 294 346 408 466 529 604 679 753 891 1017 1182 1337 1503 1879 4 4 4 16 28 48 60 88 116 148 188 232 276 328 392 446 510 582 660 730 860 990 1152 1300 1462 1842 "U"-Tube No. of Passes 2 0 2 7 13 22 28 43 57 76 96 116 135 161 189 222 254 289 330 370 436 505 578 661 748 933 .„._,„ ,. IL ^ 4 0 2 4 12 18 26 38 52 68 88 no 128 152 182 212 246 280 316 356 418 490 562 642 726 914 Shell 1,0. (Inches! 5.047 6.065 7.981 10.02 12.00 13.25 15.25 17.25 19.25 21.25 23.25 25.00 27.00 29.00 31.00 33.00 35.00 37.00 39.00 42.00 45.00 48.00 51.00 54.00 60.00 Fixed Tube Sheet No. of Passes 1 9 12 22 38 56 69 97 129 164 202 234 272 328 378 434 496 554 628 708 811 940 1076 1218 1370 170! 2 6 12 20 38 56 66 90 124 158 191 234 267 317 370 428 484 553 621 682 811 931 1061 1202 1354 4 4 12 16 32 52 66 88 120 148 184 222 264 310 370 428 484 532 608 682 804 918 1040 1192 1350 1699 1 1684 Outside Packed Floating Head No. of Passes 1 5 12 21 32 52 61 89 113 148 178 216 258 302 356 414 476 542 602 676 782 904 1034 1178 1322 1654 2 4 6 16 32 52 60 84 112 144 178 216 256 300 353 406 460 530 596 649 780 894 1027 1155 1307 1640 4 4 4 16 32 44 52 80 112 140 172 208 256 296 338 392 460 518 580 648 768 874 1012 1150 1284 1632 __^ "IP-Tube No. of Passes 1 2 0 2 6 12 19 25 36 49 64 83 100 120 142 166 145 221 254 287 322 379 436 501 573 650 810 L „, ,_ 4 0 2 4 10 18 24 34 48 62 78 98 116 138 166 192 218 248 280 314 374 434 494 570 644 802 (table continued on next page) Table 3-4 (Continued) Heat Exchanger Tube Count 1 " O.D. Tubes on ! - 1 /4* O Pitch 1 - 1 /4" O,D. Tubes on 1 -9/16" A Shell I.D. (Inches) 5.047 6.065 7.981 10.02 12.00 13.25 15.25 17.25 19.25 21.25 23.25 25.00 27.00 29.00 31.00 33.00 35.00 37.00 39.00 42.00 4500 48,00 5100 34.00 hOOO Fixed Tube Sheet No. erf Passes I 8 12 24 37 57 70 97 129 162 205 238 275 330 379 435 495 556 632 705 822 946 2 6 10 20 32 53 70 90 120 152 193 228 264 315 363 422 478 552 613 685 799 Q22 1079 ; 1061 4 4 8 16 28 48 64 84 112 142 184 220 256 300 360 410 472 538 598 672 786 9J2 1052 1220 j 119') i tl/6 1389 j B59 [mo 1714 1 !69i ! 1064 Outside Packed Floating, Head No. of Passes 1 5 12 21 32 52 61 89 113 148 180 221 261 308 359 418 477 540 608 674 788 <JIO 1037 1181 ]4T7 2 4 10 18 32 46 58 82 112 138 174 210 248 296 345 401 460 526 588 654 765 885 1018 1160 4 4 8 16 28 40 56 76 104 128 168 200 236 286 336 388 448 508 568 640 756 866 1000 1142 1107 j 1292 1658 ! 162A j l:W4 "U"-Tube No. of Passes 2 0 2 5 12 18 25 35 48 62 78 100 116 141 165 191 220 249 281 315 372 436 501 %9 4 0 2 4 10 16 22 32 44 60 76 94 110 134 160 184 212 242 274 310 364 426 490 She!! I.D. (Inches) 5.047 6.065 7.981 10.02 12.00 13.25 15.25 17.25 19.25 21.25 23.25 25.00 27.00 29.00 31.00 33.00 3500 37.00 39.00 4200 45.00 -iS.OO 558 J , 51.QO 646 | 632 1 i 54.00 802 i 788 1 ' ftOM Fixed Tube Sheet No. of Passes 1 7 8 19 29 42 52 69 92 121 147 174 196 237 280 313 357 416 461 511 596 687 790 896 1008 1241 2 4 6 14 26 38 48 68 84 110 138 165 196 226 269 313 346 401 453 493 579 673 4 4 4 12 20 34 44 60 78 104 128 156 184 224 256 294 332 386 432 478 570 662 782 1 758 S" 7 ! j 860 494 [ 968 C'4* 1210 Outside Packed Floating Head No. of Passes ] 0 7 14 22 37 44 64 85 109 130 163 184 221 262 302 345 392 442 493 576 657 7% 859 2 0 6 14 20 36 44 62 78 102 130 152 184 216 252 302 332 183 429 479 557 640 745 Kit, 4 0 4 8 16 28 36 48 72 96 116 144 172 208 242 280 318 364 412 460 544 828 ~2« ^2 0^4 j ysg j «j4(, l!9M 1 195 1 > '?H I "U"-Tube No. of Passes 2 0 0 3 7 11 16 24 32 43 57 69 81 98 116 134 155 17K 202 226 267 313 560 41 1 46^ SB, 4 0 0 2 6 10 14 22 30 40 52 66 76 92 110 128 148 172 194 220 260 *06 3*»() 400 ! 4*a I 1 -TO i [...]... 28 37 18 26 34 49 62 70 48 60 68 21. 25 23.25 25.00 12 4 14 8 17 4 11 6 14 2 16 6 11 2 13 6 16 0 11 2 14 0 16 2 10 8 13 8 16 2 48 60 71 44 56 68 i 84 216 256 88 10 0 11 6 88 98 11 6 27.00 2.0 90 31. 00 209 238 275 202 232 2 64 19 2 232 2 64 19 1 2 21 2 61 188 215 249 10 4 12 8 15 6 18 4 208 244 85 10 0 11 4 82 96 11 0 296 332 370 282 332 370 13 6 15 6 17 4 13 4 14 8 17 4 33.00 35.00 37.00 3 14 359 4 01 307 345 387 300 3 34 380 300 3 41 3 84 286... 360 13 4 15 3 17 3 12 8 14 8 16 8 42 8 49 2 570 42 6 49 2 566 41 4 48 4 556 19 8 236 276 19 6 228 268 3.0 90 4. 0 20 45 .00 44 2 522 603 42 7 506 583 42 4 500 572 42 8 49 7 575 41 2 48 4 562 40 4 47 2 552 19 5 228 2 71 190 2 24 2 64 676 756 856 658 742 838 648 729 823 648 722 810 3 14 356 40 4 310 3 54 402 4. 0 80 51. 00 54. 00 682 777 875 669 762 857 660 756 850 660 743 843 648 728 822 640 716 812 309 3 54 4 01 302 346 392 10 70 j 10 54 10 42 ... 16 32 42 21 32 38 16 32 38 16 32 32 6 10 14 4 10 14 60 76 95 52 76 88 52 70 89 52 70 88 52 68 88 21 28 37 12 4 14 5 17 2 12 4 14 5 16 8 12 0 14 4 16 4 11 2 13 8 16 4 11 2 13 8 16 4 11 2 13 0 15 6 27.00 2.0 90 31. 00 210 2 41 272 202 2 34 268 202 230 268 19 3 2 24 258 18 4 2 24 256 33.00 35.00 3.0 70 310 356 396 306 353 387 302 338 3 84 296 336 378 39.00 4. 0 20 45 .00 44 2 518 602 43 8 518 602 43 4 502 588 48 .00 51. 00 54. 00 682 770... 862 6 81 760 860 6.0 00 10 84 10 .02 ' 12 .00 13 .25 se! h! 1 1ST (inches) Fixed Tube Sheet No of Passes 1 2 4 Outside Packed Floating Head No of Passes 1 4 2 "U"-Tube No of Passes 2 4 5 6 13 4 6 10 4 4 8 0 5 12 0 4 10 0 4 8 0 0 2 0 0 2 10 .02 12 .00 13 .25 24 37 45 20 32 40 16 28 40 21 32 37 18 28 34 16 28 32 6 10 13 6 10 12 18 28 34 15 .25 17 .25 19 .25 60 79 97 56 76 94 56 76 94 52 70 90 52 70 90 48 64 84 20... 3 -4 (Continued) Heat Exchanger Tube Count 1 - ! /4" O.D Tubes on 1 -9/ 1 6" D Pitch ! - 1 14" O.D, Tubes on 1 -9/ 1 6" O Pitch ' ! Fixed Tube Sheet No of Passes 1 2 4 4 6 6 12 12 24 22 37 34 45 42 4 4 4 12 15 .25 17 .25 19 .25 61 80 97 21. 25 23.25 25.00 Shell i.D (Inches) 5. 047 605 6 7.9 81 Outside Packed Floating Head No of Passes 1 2 4 "U"-T«be No, of Passes 2 4 0 6 12 0 6 12 0 4 12 0 0 3 0 0 2 16 32 42 ... 0 01 ) 50-50 ethyl glycol-water (rf = 002) 1 10 7.5 95 6.5 90 6.2 80 5.5 13 0 — 6 .1 110 — 5.2 10 5 — 4. 9 95 4. 4 Hydrocarbon Liquid Coolers Viscosity Cp 0.2 0.5 1. 0 2.5 4. 0 6.0 10 .0 Ux Ub 85 5.9 75 5,2 65 4. 5 45 3 .1 30 2 .1 20 1 4 10 0.7 Ub Ux Ub 30 2 .1 35 2 .4 45 3 .1 Ub Hydrocarbon Gas Coolers Temperature, CF 50 10 0 300 500 750 10 00 55 3.8 65 4. 5 75 5.2 u* 10 0 — 4. 7 90 _ 4. 2 7«5 3.5 55 2,6 ^ . Passes 1 5 12 21 32 52 61 89 11 3 14 8 18 0 2 21 2 61 308 359 41 8 47 7 540 608 6 74 788 <JIO 10 37 11 81 ]4T7 2 4 10 18 32 46 58 82 11 2 13 8 17 4 210 248 296 345 4 01 46 0 526 588 6 54 765 885 10 18 11 60 4 4 8 16 28 40 56 76 10 4 12 8 16 8 200 236 286 336 388 44 8 508 568 640 756 866 10 00 11 42 11 07 . Passes 1 7 8 19 29 42 52 69 92 12 1 14 7 17 4 19 6 237 280 313 357 41 6 4 61 511 596 687 790 896 10 08 12 41 2 4 6 14 26 38 48 68 84 11 0 13 8 16 5 19 6 226 269 313 346 4 01 45 3 49 3 579 673 4 4 4 12 20 34 44 60 78 10 4 12 8 15 6 18 4 2 24 256 2 94 332 386 43 2 47 8 570 662 782. Passes 1 0 5 12 21 32 37 52 70 90 11 2 14 0 16 2 19 1 2 21 2 61 300 3 41 3 84 428 49 7 575 660 743 843 10 49 2 0 4 10 18 28 34 52 70 90 10 8 13 8 16 2 18 8 215 249 286 330 372 41 2 48 4 562 648 728 822 4 0 4 8 16 28 32 48 64 84 10 4 12 8 15 6 18 4 208 244 280 320 360 40 4 47 2 552 640 716 812 10 29