Process Engineering Equipment Handbook Episode 3 Part 6 ppsx

Cyclone inlet section. As the mist-laden gas enters the separator, the entrained liquids and solid particles are subjected to centrifugal force. The gas enters the cyclone tube at two points, designated A, and sets up a swirling motion. Solid and liquid particles are thrown outwardly and drop from the tube at point B. The swirling gas reverses direction at the vortex C and rises through the exit portion of the tube, designated D. See Fig. S-21. Separators S-17 FIG. S-20 Horizontal with horizontal lower barrel and vertical configuration. (Source: Peerless.) Mist extractor inlet section (alternate for some applications). As the gas enters the vane unit, it is divided into many vertical ribbons (A). Each ribbon of gas is subjected to multiple changes of direction (B) as it follows its path through the vanes. This causes a semiturbulence and rolling of the gas against the walls of the vanes (C). The entrained droplets are forced to contact the vane walls where they impinge and adhere to the vane surface (D). This liquid then moves into the vane pockets (E) and out of the gas stream. It is then drained by gravity into the liquid reservoir. The collected liquid can then be disposed of as desired. See Fig. S-22. Final separation element. The final separation section consists of one or more cylindrical coalescing elements mounted vertically on support tubes. The gas and fine mists pass from the inside to the outside of the elements. In passing through the coalescing elements, the entrained mist particles diffuse and impinge on the closely spaced surfaces of the element and are agglomerated into larger liquid droplets. The larger liquid droplets emerge on the outer surface of the coalescing element and run down the sides of the element to the liquid collection chamber. The gas, free of liquid particle entrainment, rises and passes out of the separator through the upper gas outlet nozzle. Design features. Replacement of the final separation elements can be made with a minimum of time and effort through the use of a full opening O-ring or float ring closure. The primary separation elements (vane-type mist extractor or cyclone section) are completely maintenance-free and self-cleaning, with no replacement or moving parts to cause shutdown. The absolute separator could be guaranteed to remove 100 percent of all liquid particles above 3 microns; and, depending on design conditions, it will remove up to 99.98 percent of all particles less than 3 microns. This efficiency is maintained throughout the entire flow range to design capacity. S-18 Separators FIG. S-21 Cyclone operation filter/separator. See text for key to components. (Source: Peerless.) FIG. S-22 Mist extractor section. (Source: Peerless.) The normal pressure drop through the final separation elements is limited by design to 5 in of water column or less. The pressure drop across the primary section will depend on operating conditions and the type of separation elements used. See Figs. S-23 and S-24. Vane-type separator Line separators are designed and fabricated to conform fully to all current ASME requirements and are usually furnished in carbon steel for most industrial applications; however, units can be fabricated in part or entirely from stainless steel, Monel, or other special alloy materials. See Figs. S-25 and S-26. See also Table S-2. Although standard units are designed for 275- and 720-psi working pressure (412.5- and 1080-lb test pressure), vessels can be furnished in virtually unlimited Separators S-19 FIG. S-23 Mist particle removal chart. (Source: Peerless.) TABLE S-2 Vane-Type Separators Body Diameter (O.D.) 6 5 / 8 ≤ 8 5 / 8 ≤ 12 3 / 4 ≤ 14≤ 16≤ 18≤ 20≤ In and out line sizes 2≤ 3≤ 4≤ 6≤ 8≤ 10≤ 12≤ A Face-to-face 17≤ 20≤ 24≤ 26≤ 30≤ 34≤ 38≤ B Approximate overall height 36≤ 38≤ 47≤ 49 1 / 2 ≤ 52 1 / 2 ≤ 60≤ 63≤ C Body length, seam-to-seam 29≤ 30≤ 36≤ 38≤ 40≤ 46≤ 48≤ D Top head seam centerline inlet and outlet 4 1 / 2 ≤ 4 1 / 2 ≤ 8 1 / 2 ≤ 9≤ 9≤ 11≤ 11≤ G Lower head seam to bottom of base 12≤ 12≤ 18≤ 18≤ 18≤ 18≤ 18≤ -0- Liquid capacity (gal.) 2 3 / 4 3 3 / 4 8 1 / 4 11 1 / 16 14 7 / 8 21 21 7 / 8 -0- Pressure drop (in, H 2 O) 12–13 12–13 8–10 8 6–8 6 5 NOTES : 1. All dimensions are ± 1 / 4 ≤. 2. Base support is optional. 3. Vessels stocked with design pressure of 275 psig 150# RF and 720 psig 300# RF. 4. Vessels equipped with these accessory fittings: A. 2, 3 / 4 ≤ 6,000# gauge glass connections. B. 2≤ 3,000# equalizer connection. C. 2≤ 3,000# drain connection (1 1 / 2 ≤ on 6 5 / 8 ≤ and 8 5 / 8 ≤ O.D. sizes). D. 2, 1≤ 3,000# high-level shut-down connections on 14≤ O.D. and larger sizes. E. 2≤ 3,000# vent connection (1 1 / 2 ≤ on 6 5 / 8 ≤ and 8 5 / 8 ≤ O.D. sizes). FIG. S-24 Absolute separator. (Source: Peerless.) S-20 FIG. S-25 Vane-type separator performance curves. (Source: Peerless.) FIG. S-26 Vane-type separator (external). (Source: Peerless.) S-21 S-22 Separators ratings for greater pressures if required (pressures in the 20,000-lb range are not uncommon). Vertical gas separators These vessels employ many physical means to separate the liquids from gases in addition to the mist extractor. Foremost among these various separation forces are: impingement, centrifugal force, gravitational force, and surface tension. See Fig. S-27. Inlet baffle. Of prime importance to the separation is the inlet impingement baffle, which acts to eliminate heavy slugging problems set up by excess amounts of liquid in the stream. See Fig. S-28. As the slugs of liquid come into contact with the baffle, they are deflected at an angle and are broken up by a hooked vane attached to the edge of the baffle. This breaking up of the slugs causes them to drop out of the stream and to the bottom of the separator. The baffle is made of extra thick material to protect against excess erosive wear. Rise to mist extractor. Having removed a majority of the entrained liquid or slugs, the gas flow continues its travel to the mist extractor that is above the inlet baffle. During this travel, a centrifugal and gravitational action takes place that separates more of the entrained liquid. The distance the vapor (gas and liquid) must rise to enter the mist extractor aids in the separation by supplying time necessary to permit coalescing or the forming of small droplets into larger drops that have a greater rate of fall than the upward velocity of the gas. By this method, maximum separation, using impingement, centrifugal motion, and gravity, has been obtained with a minimum pressure drop. This settling effect, utilized in the vertical gas separator, removes all but a very small portion of the liquid. This remaining liquid continues to rise toward the gas outlet in the form of a fine spray. To solve this final separation problem, the mist extractor is used. Mist extractor. The mist extractor combines maximum scrubbing area with an absolute minimum pressure drop. It utilizes the forces of impingement, centrifugal motion, and surface tension to obtain its high efficiency. See Fig. S-29. The path of the gas through the unit is constantly bending, causing the impingement of the liquid droplets against the walls of the vane, separating some of the entrained mist. Centrifugal force aids by throwing the heavier liquid droplets out of the main gas stream and impinging them on the scrubbing surface. The entrained liquid, after coming into contact with the metal surface and other liquid droplets of the vane unit, is coalesced and adheres to the vane surface by utilizing the forces of surface tension. Gravity and impact of the gas stream then drives the droplets into the pockets provided at each turn of the vane where they roll down out of the gas stream. After going through the complete process of scrubbing and separation, the gas finally reaches the outlet opening of the separator clean and dry. Liquid control. The large liquid reservoir is adequate to store incoming slugs of liquid during the time required for opening the liquid valve. The volume of the vessel is large enough to allow the gas to break out of the solution and to escape the liquid in the bottom of the separator. Separators S-23 FIG. S-27 Vertical gas separator. (Source: Peerless.) S-24 Separators Line separators The vane-type line separator offers efficient separation of entrained liquids from a gas or vapor stream. This separator design has been used successfully for over 25 years in chemical plants, refineries, natural gas pipelines, and all types of industrial processing plants where efficient liquid-gas separation has been required. See Figs. S-30 and S-31. These separators incorporate the vane-type mist extractor as the separating element. This unit offers a number of operating characteristics not found in other types of separators: ᭿ 100 percent removal of all entrained droplets 8–10 microns and larger ᭿ Extremely low pressure drop—less than 6 in of water column ᭿ Small housing requirement for ease of installation and economy ᭿ Flat efficiency curve with no decrease in efficiency from rated capacity down to zero flow FIG. S-29 Mist extractor. (Source: Peerless.) FIG. S-28 Interbuffer—vertical gas separator. (Source: Peerless.) Separators S-25 FIG. S-30 Line separator installation. (Source: Peerless.) Principle of operation. The vane unit is the heart of the separator (see Fig. S-32). As the gas enters the vane unit, it is divided into many vertical ribbons (A). Each ribbon of gas is subjected to multiple changes of direction (B) as it follows its path through the vanes. This causes a semiturbulence and rolling of the gas against the walls of the vanes (C). The entrained droplets are forced to contact the vane walls where they impinge and adhere to the vane surface (D). This liquid then moves into the vane pockets (E) and out of the gas stream where it is drained by gravity into the liquid reservoir. The collected liquid can then be disposed of as desired. It is significant to note that the liquid drainage in the vane-type mist extractor differs from the drainage in other impingement-type mist extractors, in that vane drainage occurs with the liquid out of the gas flow and at a right angle to the direction of flow through the separator. The individual vane corrugations, depth and size of the liquid pockets, and the vane spacing are critical features of the vane-type mist extractor. Many years of testing and operating experience eventually arrive at optimum dimensions and spacing. The slightest variation in any one of these three features will materially decrease the capacity and performance of this type of separator. Efficiency and capacities. The vane-type line separator (see Fig. S-33) will remove all of the entrained liquid droplets that are 8–10 microns and larger. The efficiency of the unit decreases on droplet sizes less than 8 microns as shown on the chart. In order to separate these smaller droplets, the separator must be preceded by an agglomerating or coalescing device to increase the size of the droplets so that they can be removed by the mist extractor. Several types of agglomerating devices are available. Some of these are capable of achieving efficiencies as high as 99 1 / 2 percent removal of 1 micron size droplets. [...]... (L3 - L1 ) - RB (L3 - L2 ) Ë D1 4¯ { } where K1 = K2 = (L3 - L2 )3 (L3 - L1 ){(L3 - L1 )2 - (L2 - L1 )2 } (L2 + L2 )(L3 + L1 ) - (L2 + L2 )(L2 + L1 ) 3 1 2 1 4{(L3 - L1 )2 - (L2 - L1 )2 } L3 - L2 + K3 = L3 - L1 + 2 kv D1 (L - L2 )2 4 EI 2 2 kv D1 {3( L3 + L1 )2 - (L2 - L1 )2 } 12 EI k D2 1 L4 Ê L3 - L4 ˆ + v 1 {4 L3 - (L2 + L2 )(L2 + L1 )} 3 2 1 Ë 2 ¯ 48 EI K4 = 2 kD L3 - L1 + v 1 {3( L3 - L1 )2 - (L2... 125,000 130 ,000 135 ,000 145,000 0 63 , 000 1 26, 000 161 ,000 182,000 0 48,000 1 06, 000 1 36 ,000 147,000 0 11 25 32 35 NOTES 1 The percentage saving relates to the total installed cost of a fully supported system This is £425,000 made up from a stack cost of £110,000 plus 90 tons of steel at 3, 500 per ton 2 The stack manufacturing cost includes fabrication and design by an acoustic equipment manufacturer 3 All... AB vo = ws 3 (x 4 + 2 KLo xo + Ao L3 x + Bo L4 ) sin mt o o 24 EI o Bo = where 12 EIk L3 o Ao = Bo 2L + 2K - 1 Lo - L and in section BC vo = where ws (x 4 - 4 Lx 3 + 6 L2 x 2 + AL3 x + BL4 ) sin mt 24 EI L 4 Lo + L B = Bo = Ê o ˆ Ë L¯ L -L o 3 L Ê 2L ˆ A = Ê o ˆ Bo + 3 - 4k Ë L¯ Ë ¯ Lo - L Equating the maximum values of the kinetic and bending strain energies, putting p ws = rpDt and I = D 3 t , the... ¯ Í Ë Lo - L ¯ ˙ Î ˚ and Y= 104 26 12 1 + A+ B + A 2 + AB + B2 45 15 5 3 Lo ˆ 9 1 1 4 2 5 - 12 K 2-k 1 2 2 +Ê ¯ - K+ K + Ao + Bo + Ao + Ao Bo + Bo Ë L 9 2 7 15 5 3 { } For a fixed foundation k = 0 and these expressions can be simplified with the fundamental frequency for transverse vibration being given by 1 Ê Lo ˆ 5 (6 - 15 K + 10 K 2 ) 1 3. 6 ED g 6 L ¯ fo = ◊ 104 26 A 1 2 Ê Lo ˆ 9 1 1 4 5 - 12 K 1... requirements of ASTM A 36 with a minimum yield strength of 36 ,000 psi High-strength plate shall conform to, or at least be equal to, the requirements of ASTM A572-Gr 50 or 60 , ASTM A607-Gr 50, 60 , or 70 2 Steel sheet shall conform to, or at a minimum shall be equal to, hot-rolled quality per ASTM A570 Gr 40 with a minimum yield strength of 40,000 psi Minimum thickness shall be 12 gauge (nominal 2 .65 mm) B Rolled... rates Stacks S -33 Design Parameters The following base design parameters are defined as an example: Lower stack connection Upper stack termination Freestanding stack length Turbine type Nominal power output Exhaust gas mass flow Power turbine gas exit temperature Design wind speed Material of construction 59.1 m above sea level 83. 5 m above sea level 10 m Coberra 64 62 23 MW 90 kg/s 475°C 53 m/s Stainless... and S -34 Stacks FIG S -38 Stack idealization for steady wind load (Source: Altair Filters International Limited.) introduce the boundary conditions in the resulting displacement function This yields four simultaneous equations that may be solved to give the individual reactions in the form: RA = K2 K3 - K1K4 w K3 - K1 RB = K4 - K2 w K3 - K1 RC = wL4 - RA - RB and V= L 1 wL4 Ê L3 - 4 ˆ - RA (L3 - L1... weight reduction of 1 56 tons This equates to a saving of 35 percent when compared with the total installed cost of the fully supported exhaust system S -32 Stacks FIG S - 36 Exhaust stack showing alternative support arrangements (Source: Altair Filters International Limited.) FIG S -37 Relationship of free stack length to weight saving (Source: Altair Filters International Limited.) TABLE S -3 Net Cost Savings... accordance with the recommendations of BSI (a British standard) CP3, Chapter V, Part 2 (1972) Typical values for an offshore environment are a design wind speed of 53 m/s, which for a 2-m-diameter exhaust stack corresponds to a drag force of w = 3. 6 kN/m For a stack mounted on pinned supports at three discrete levels as shown in Fig S -38 the support reactions are not statically determinate It is necessary... grade 31 6 L was chosen as the most suitable to meet all the project requirements Choice of Design Philosophy A typical design for an offshore gas turbine exhaust system is shown in Fig S - 36 The exhaust ducting is surrounded on all sides by a substantial steel framework Upright structural members would typically be 254 mm ¥ 254 mm ¥ 73 kg/m universal column and horizontal members 457 mm ¥ 191 mm ¥ 67 kg/m . 12≤ A Face-to-face 17≤ 20≤ 24≤ 26 30 ≤ 34 ≤ 38 ≤ B Approximate overall height 36 ≤ 38 ≤ 47≤ 49 1 / 2 ≤ 52 1 / 2 ≤ 60 ≤ 63 C Body length, seam-to-seam 29≤ 30 ≤ 36 ≤ 38 ≤ 40≤ 46 48≤ D Top head seam centerline inlet. Saving (£) (£) Saving 0 110,000 0 0 0 5 125,000 63 , 000 48,000 11 10 130 ,000 1 26, 000 1 06, 000 25 15 135 ,000 161 ,000 1 36 ,000 32 20 145,000 182,000 147,000 35 NOTES 1. The percentage saving relates to. L kD EI LLLLL LL kD EI LL LL v v 4 43 4 1 2 3 3 2 2 1 2 21 31 1 2 31 2 21 2 1 248 4 12 3 = - Ê Ë ˆ ¯ +-+ () + () {} -+ - () () {} K LL kD EI LL LL kD EI LL LL v v 3 32 1 2 22 2 31 1 2 31 2 21 2 4 12 3 = -+ - () -+