Heat Exchanger & Column Design interview questions

1. A.tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
2. B.extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length
3. C.packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value
4. D.three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head

Answer + AI explanation with Pro

1. A.Fouling factor
2. B.Tray vs packing
3. C.Weeping and dumping
4. D.TEMA designation

Answer + AI explanation with Pro

1. A.TEMA designation — tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
2. B.TEMA designation — three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head
3. C.TEMA designation — packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value
4. D.TEMA designation — extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length

Answer + AI explanation with Pro

1. A.trays suit high liquid rates, fouling and large diameters; structured packing gives lower pressure drop and higher capacity for vacuum and low-liquid-load services
2. B.fixed tubesheet is cheapest but needs an expansion joint and cannot be shell-side cleaned; U-tube absorbs expansion but tube insides are hard to clean; floating head allows both
3. C.packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value
4. D.multiplier below 1 applied to counter-current LMTD for multi-pass or cross-flow exchangers; designs with F under about 0.75 need more shells in series

Answer + AI explanation with Pro

1. A.LMTD correction factor F
2. B.TEMA designation
3. C.HETP
4. D.Kettle vs thermosiphon reboiler

Answer + AI explanation with Pro

1. A.LMTD correction factor F — multiplier below 1 applied to counter-current LMTD for multi-pass or cross-flow exchangers; designs with F under about 0.75 need more shells in series
2. B.LMTD correction factor F — extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length
3. C.LMTD correction factor F — three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head
4. D.LMTD correction factor F — vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations

Answer + AI explanation with Pro

1. A.extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length
2. B.multiplier below 1 applied to counter-current LMTD for multi-pass or cross-flow exchangers; designs with F under about 0.75 need more shells in series
3. C.kettle gives a full theoretical stage and handles wide-boiling mixtures but costs more; thermosiphon relies on density-driven circulation with typically 10–25% vaporisation
4. D.three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head

Answer + AI explanation with Pro

1. A.Fouling factor
2. B.Weeping and dumping
3. C.Tray vs packing
4. D.TEMA designation

Answer + AI explanation with Pro

1. A.Fouling factor — three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head
2. B.Fouling factor — fixed tubesheet is cheapest but needs an expansion joint and cannot be shell-side cleaned; U-tube absorbs expansion but tube insides are hard to clean; floating head allows both
3. C.Fouling factor — tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
4. D.Fouling factor — extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length

Answer + AI explanation with Pro

1. A.tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
2. B.vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations
3. C.fixed tubesheet is cheapest but needs an expansion joint and cannot be shell-side cleaned; U-tube absorbs expansion but tube insides are hard to clean; floating head allows both
4. D.multiplier below 1 applied to counter-current LMTD for multi-pass or cross-flow exchangers; designs with F under about 0.75 need more shells in series

Answer + AI explanation with Pro

1. A.LMTD correction factor F
2. B.Kettle vs thermosiphon reboiler
3. C.Tray vs packing
4. D.Fixed vs U-tube vs floating head

Answer + AI explanation with Pro

1. A.Fixed vs U-tube vs floating head — extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length
2. B.Fixed vs U-tube vs floating head — vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations
3. C.Fixed vs U-tube vs floating head — tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
4. D.Fixed vs U-tube vs floating head — fixed tubesheet is cheapest but needs an expansion joint and cannot be shell-side cleaned; U-tube absorbs expansion but tube insides are hard to clean; floating head allows both

Answer + AI explanation with Pro

1. A.three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head
2. B.trays suit high liquid rates, fouling and large diameters; structured packing gives lower pressure drop and higher capacity for vacuum and low-liquid-load services
3. C.vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations
4. D.packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value

Answer + AI explanation with Pro

1. A.Tray vs packing
2. B.Fouling factor
3. C.HETP
4. D.Fixed vs U-tube vs floating head

Answer + AI explanation with Pro

1. A.Tray vs packing — packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value
2. B.Tray vs packing — trays suit high liquid rates, fouling and large diameters; structured packing gives lower pressure drop and higher capacity for vacuum and low-liquid-load services
3. C.Tray vs packing — multiplier below 1 applied to counter-current LMTD for multi-pass or cross-flow exchangers; designs with F under about 0.75 need more shells in series
4. D.Tray vs packing — extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length

Answer + AI explanation with Pro

1. A.packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value
2. B.trays suit high liquid rates, fouling and large diameters; structured packing gives lower pressure drop and higher capacity for vacuum and low-liquid-load services
3. C.three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head
4. D.vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations

Answer + AI explanation with Pro

1. A.TEMA designation
2. B.HETP
3. C.LMTD correction factor F
4. D.Fouling factor

Answer + AI explanation with Pro

1. A.HETP — fixed tubesheet is cheapest but needs an expansion joint and cannot be shell-side cleaned; U-tube absorbs expansion but tube insides are hard to clean; floating head allows both
2. B.HETP — kettle gives a full theoretical stage and handles wide-boiling mixtures but costs more; thermosiphon relies on density-driven circulation with typically 10–25% vaporisation
3. C.HETP — multiplier below 1 applied to counter-current LMTD for multi-pass or cross-flow exchangers; designs with F under about 0.75 need more shells in series
4. D.HETP — packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value

Answer + AI explanation with Pro

1. A.vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations
2. B.extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length
3. C.tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
4. D.packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value

Answer + AI explanation with Pro

1. A.Tray vs packing
2. B.LMTD correction factor F
3. C.Fouling factor
4. D.Weeping and dumping

Answer + AI explanation with Pro

1. A.Weeping and dumping — multiplier below 1 applied to counter-current LMTD for multi-pass or cross-flow exchangers; designs with F under about 0.75 need more shells in series
2. B.Weeping and dumping — tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
3. C.Weeping and dumping — fixed tubesheet is cheapest but needs an expansion joint and cannot be shell-side cleaned; U-tube absorbs expansion but tube insides are hard to clean; floating head allows both
4. D.Weeping and dumping — three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head

Answer + AI explanation with Pro

1. A.fixed tubesheet is cheapest but needs an expansion joint and cannot be shell-side cleaned; U-tube absorbs expansion but tube insides are hard to clean; floating head allows both
2. B.vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations
3. C.three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head
4. D.packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value

Answer + AI explanation with Pro

1. A.Jet flooding
2. B.LMTD correction factor F
3. C.Tray vs packing
4. D.Weeping and dumping

Answer + AI explanation with Pro

1. A.Jet flooding — tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
2. B.Jet flooding — multiplier below 1 applied to counter-current LMTD for multi-pass or cross-flow exchangers; designs with F under about 0.75 need more shells in series
3. C.Jet flooding — kettle gives a full theoretical stage and handles wide-boiling mixtures but costs more; thermosiphon relies on density-driven circulation with typically 10–25% vaporisation
4. D.Jet flooding — vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations

Answer + AI explanation with Pro

1. A.kettle gives a full theoretical stage and handles wide-boiling mixtures but costs more; thermosiphon relies on density-driven circulation with typically 10–25% vaporisation
2. B.vapour velocity at which entrained liquid cannot flow down the column; trays are sized at about 80% of this limit using Fair or Souders-Brown correlations
3. C.packed height equivalent to one theoretical plate, typically 0.3–0.6 m for structured packing; packed height equals stages required times this value
4. D.tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit

Answer + AI explanation with Pro

1. A.Jet flooding
2. B.Kettle vs thermosiphon reboiler
3. C.Weeping and dumping
4. D.TEMA designation

Answer + AI explanation with Pro

1. A.Kettle vs thermosiphon reboiler — extra thermal resistance (about 0.0002–0.0005 m²K/W for cooling water) added to the clean coefficient to allow for deposits over the run length
2. B.Kettle vs thermosiphon reboiler — tray malfunction at low vapour rate where liquid leaks through the perforations instead of crossing the weir, which sets the turndown limit
3. C.Kettle vs thermosiphon reboiler — kettle gives a full theoretical stage and handles wide-boiling mixtures but costs more; thermosiphon relies on density-driven circulation with typically 10–25% vaporisation
4. D.Kettle vs thermosiphon reboiler — three-letter code for front head, shell and rear head types, for example AES meaning removable channel, single-pass shell and split-ring floating head

Answer + AI explanation with Pro