Desalted Crude Oil Side Draw Heat Exchanger (TEMA AES) for Petrochemical Industry
| Type | Description | Mnemonic / Visual Concept | Key Advantages | Key Disadvantages | Best Applications |
| A | Channel and Removable Cover | A = Access | Easiest to clean the inside of the tubes. You only need to remove the flat cover without disconnecting the tube-side piping. | More flanged joints (two), increasing the potential risk of external leakage under high pressure. Higher manufacturing cost. | Services with highly fouling tube-side fluids that require frequent mechanical cleaning (brushing). |
| Features two flanged joints; the channel cylinder and the flat cover are independent. | |||||
| B | Bonnet (Integral Cover) | B = Bonnet | Fewer flanged joints mean better sealing performance, lighter weight, and lower cost. | To clean the inside of the tubes, the entire bonnet must be disconnected and removed from the piping. | Clean tube-side fluids, high-pressure services, or applications where frequent internal cleaning is not required. |
| The channel and cover are fabricated as a single piece (domed head), leaving only one flanged joint. | |||||
| C | Channel Integral with Tubesheet | C = Combined | Eliminates the flanged joint between the tubesheet and channel, minimizing external leakage risks under extreme pressure. | Higher cost; if the tube bundle fails, it cannot be pulled out as a single assembly for complete replacement. | High-pressure, hazardous, lethal, or toxic fluids where tube-side mechanical cleaning is still necessary. |
| The channel is welded or forged integrally with the tubesheet, but the flat cover is removable. | |||||
| N | Channel Integral with Tubesheet and Cover | N = No Flanges | Most compact design with the lowest risk of external leakage (near zero). Highly resistant to extreme pressure. | Mechanical brushing is impossible. Can only be cleaned using chemical circulation (Chemical Cleaning). | Severely hazardous, lethal, explosive, or ultra-high pressure services with extremely clean fluids. |
| The cover, channel, and tubesheet are completely welded together into a single rigid structure. |
| Type | Description | Mnemonic / Visual Concept | Key Advantages | Key Disadvantages | Best Applications |
| E | One-Pass Shell | E = Everyday (Standard) | The most classic, simple, and cost-effective design. Offers flexible baffle configurations. | High pressure drop (resistance) when handling massive volumetric flow rates or gases. | The most common choice for general liquid-to-liquid heat transfer with moderate temperature differences. |
| One inlet and one outlet. Fluid flows along the shell length guided by baffles. | |||||
| F | Two-Pass Shell with Longitudinal Baffle | F = Flip (Divided Flow) | Forces the shell-side fluid into two passes, achieving true counter-current flow. Maximizes MTD and efficiency. | The internal longitudinal baffle requires high manufacturing precision; risk of thermal bypassing/leakage across the baffle under high pressure differentials. | Applications requiring high thermal efficiency, close temperature approaches, or a pure counter-current flow pattern. |
| Features an internal longitudinal baffle that forces the fluid to travel back and forth. | |||||
| G | Split-Flow | G = Grand Split | Splits the flow to significantly reduce shell-side pressure drop. Ideal for phase-change services. | More complex internal structure and piping layout. | Commonly used for reboilers or services involving partial condensation. |
| Central inlet split into two streams by a horizontal baffle, exiting at the ends. | |||||
| H | Double Split-Flow | H = Huge Split | Offers an even lower pressure drop than the G-shell and provides highly uniform heat transfer coefficient distribution. | Complex fabrication and internal baffle alignment, resulting in higher costs. | Large-duty reboilers or evaporation processes requiring minimized pressure drop. |
| An upgraded version of the G-shell, using multiple baffles to split the flow into four streams. | |||||
| J | Divided-Flow | J = Joint (1-in/2-out or 2-in/1-out) | Reduces the pressure drop to approximately 1/8 of an E-shell, allowing massive gas volume throughput. | Requires piping connections at both ends of the shell, complicating external piping layouts. | Large-volume gas cooling or vacuum condensers where pressure drop must be strictly minimized. |
| Typically enters at the center and exits at both ends (inverted T-shape). | |||||
| K | Kettle Type Reboiler | K = Kettle (Enlarged Shell) | Provides an integrated vapor-liquid separation space. Vapor rises smoothly while liquid is boiled below, preventing liquid entrainment. | The oversized, kettle-shaped shell is bulky, consumes more material, and is expensive. | Distillation tower reboilers, evaporators, and waste heat boilers in chemical plants. |
| The tube bundle sits in the lower section, while the upper shell features a distinct enlarged vapor space. | |||||
| X | Cross-Flow | X = Cross- (Pure Cross Flow) | Fluid passes straight through without bending, resulting in virtually zero pressure drop (no baffle resistance). | High risk of flow-induced tube vibration; requires a massive impingement plate at the inlet. | Large-scale power plant condensers, geothermal power, or ultra-high velocity gas condensation. |
| Fluid enters across the entire top length and exits through the bottom, flowing perpendicularly over the tubes. |
| Type | Category | Mnemonic / Visual Concept | Thermal Expansion Solution | Bundle Removable? | Key Pros & Cons / Best Applications |
| L | Fixed Tubesheet | Mirrors Front Head 'A' | Rigid design. If the temperature difference is large, an expansion joint (bellows) must be added to the shell. | No | Pros: Very easy to remove the flat cover and clean the tube inside; economical. |
| Features a flanged flat cover. The tubesheet is welded directly to the shell. | |||||
| M | Fixed Tubesheet | Mirrors Front Head 'B' | Rigid design. Requires a shell expansion joint for high temperature differentials. | No | Pros: Fewer flanged joints, better high-pressure sealing than Type L. |
| Features an integral bonnet (domed head). The tubesheet is welded to the shell. | |||||
| N | Fixed Tubesheet | Mirrors Front Head 'N' | Rigid design. Requires a shell expansion joint for high temperature differentials. | No | Pros: Lightest weight, absolutely zero risk of external flange leakage. |
| Completely welded on both ends; no large-diameter body flanges. | |||||
| P | Packed Floating Head | P = Packed (Inside Packing) | The tubesheet slides freely, perfectly absorbing thermal expansion. | Yes | Critical Flaw: Packing degradation can cause internal fluid intermixing (cross-contamination) between tube and shell sides. |
| The rear tubesheet slides inside the shell, sealed by a soft packing ring. | |||||
| W | Packed Floating Head | W = Warning Lantern Ring | The tubesheet slides freely, perfectly absorbing thermal expansion. | Yes | Pros: Any leakage drains out through the weep holes, preventing internal cross-contamination. |
| The tubesheet slides, but features a tell-tale weep hole between the tube/shell packings. | |||||
| S | Floating Head | S = Split Ring | The rear head floats freely inside the shell cover, eliminating thermal stress. | Yes | Pros: The refinery workhorse. Allows thorough mechanical cleaning of both tube inside and outside. |
| The classic floating head. The floating head cover is secured to the tubesheet using a split backing ring. | |||||
| T | Floating Head | T = Total Pull-Through | The rear head floats freely inside the shell cover, eliminating thermal stress. | Yes | Pros: Fastest bundle extraction; drastically reduces maintenance downtime. |
| The floating head cover diameter is smaller than the internal shell diameter. | |||||
| U | U-Tube | U = U-Tube (Bending) | The bent end hangs completely free, allowing unhindered thermal expansion. | Yes | Pros: Eliminates half the tubesheets, headers, and flanges. Highly cost-effective and exceptional for high pressure. |
| Tubes bend 180 degrees. No rear head or rear tubesheet exists. | (Immediate pull from the front side) | Cons: U-bends cannot be cleaned mechanically. Tube-side fluid must be extremely clean and non-fouling. |
