Heat Exchangers
Conduction
The means of heat transfer through a solid, nonporous material resulting from molecular vibration.occur b/w closely packed molecules
Purpose of a fired heater
Heat large generators of hydrocarbons
Tube side
Refers to flow through the tubes of a shell-and-tube heat exchanger
Tank Farm
A collection of tank used to store and transport raw materials and products
Spiral heat exchangers are characterized by
A compact concentric design. Have two internal chambers
Channel head
A device mounted on the inlet side of a shell-and- tube heat exchanger that is used to channel tube-side flow in a multipass heat exchanger
Gauge Hatch
A door in a roof of an atmospheric tank that enables the content to be measure
Reboiler
A hear exchanger used to add heat to a liquid that was once boiling until the liquid boils again
Shell-and-tube heat exchanger
A heat exchanger that has a cylindrical shell surrounding a tube bundle. The most common style in industry. Designed for high flow rates in continuous operations (Two Independent pressure barriers)
Thermosyphon Reboiler
A type of heat exchanger that generates natural circulation as a static liquid is heated to its boiling point
Multipass heat exchanger
A type of shell-and-tube heat exchanger that channels the tube-side flow across the tube bundle (heating source) more than once
Heat transfer occurs primarily through
Conduction (first) and Convection (second)
Radiant heat transfer
Conveyance of heat by electromagnetic waves from a source to recievers
Baffles
Evenly spaced partitions in a shell-and-tube heat exchanger that support the tubes, prevent vibration, control fluid velocity and direction, increase turbulent flow, and reduce hot spots. Redirects flow.
Segmental Baffel
Evenly spaced, redirects flow,increase turbulence and surface area; Supports the tubes. (Purpose: heat transfer efficiency and reduce hotspot potential)
What's the center of an impeller called
Eye
Sensible heat
Heat that can be measured or sensed by a change in temperature
Disadvantage of multi pass vs single pass
Multi pass has more pressure drop
Impingement baffel
Perpendicular to the nozzle. Protects the tube from erosion
Types of Heat Exchangers
Pipe in pipe,
Cooling Tower
Rectangular device used to remove hear from water
The purpose of a Heat Exchanger
Recycles heat, Saves Money
Shell side
Refers to flow around the outside of the tubes of a shell-and-tube heat exchanger
Countercurrent/ counterflow
Refers to the movement of two flow streams in opposite directions
Parallel Flow
Refers to the movement of two flow streams in the same direction; for example, tube-side flow and shell-side flow in a heat exchanger; also called concurrent
Parallel Flow
Refers to the movement of two flow streams in the same direction; for example, tube-side flow and shell-side flow in a heat exchanger; also called concurrent. [the process flow goes through multiple exchangers at the same time]
Crossflow
Refers to the movement of two flow streams perpendicular to each other
Liquid moves from the bottom to top to
Remove or reduce trapped vapor in the system
Gases move from top to bottom to
Remove trapped or accumulated liquids
Correct tube leaks
Repairs, plugging tubes
Back washing
Reversing flow to remove build up of material do to fouling
Types of Baffels
Segmental, head partitions, longitudinal, impingement
Two types of welding you can do on pipes
Socket and butt welded
Pass/ head partitions
Splits the flow on the tube side making a multi pass
Longitudinal Baffels
Splits the tube shell side flow into two or more passes
Exchanger Fouling is mostly found in is
Water Coolers
Finns
A thin metal that Increase surface area
Tube sheet
A metal plate (to which the end of the tubes in a heat exchanger are fixed by rolling, welding, or both) Creates barriers between fluids and help supports tubes
Condenser
A shell-and-tube heat exchanger used to cool and condense hot vapors. (Uses water to clean)
Condenser
A shell-and-tube heat exchanger used to cool and condense hot vapors.(found overhead of towers) turns vapor into liquids
Kettle reboiler (Utube exchanger double pass)
A shell-and-tube heat exchanger with a vapor disengaging cavity, used to (create steam) supply heat for separation of lighter and heavier components in a distillation system and to maintain heat balance
Kettle reboiler
A shell-and-tube heat exchanger with a vapor disengaging cavity, used to supply heat for separation of lighter and heavier components in a distillation system and to maintain heat balance
Fixed head
A term applied to a shell-and-tube heat exchanger that has the tube sheet firmly attached to the shell. [single pass; fixed head, multipass]
Floating head
A term applied to a tube sheet on a heat exchanger that is not firmly attached to the shell on the return head and is designed to expand (float) inside the shell as temperature rises. [multipass or U-tube]
Floating head
A term applied to a tube sheet on a heat exchanger that is not firmly attached to the shell on the return head and is designed to expand (float) inside the shell as temperature rises. [multipass or U-tube] (designed for High temp differentials above 200)
Heat Exchanger
Allows a hot fluid to transfer heat energy to a cooler fluid through Conduction and Convection; Provides heating or cooling to a process
Advantage of floating head vs Utube exchanger
Both are used for High Temperature. You can access tubes and easy to clean and manage
Fouling
Buildup on the internal surfaces of devices such as cooling towers and heat exchangers, resulting in reduced heat transfer and plugging.
Fouling
Buildup on the internal surfaces of devices such as cooling towers and heat exchangers, resulting in reduced heat transfer and plugging. (Problem that stops an exchanger's ability to transfer heat)
Air-cooled heat exchangers
Do not require the use of a shell in operation. Primarily used in condensing operations( high level of heat is required) Fin Fan or radiator transfer liquid to gas
Plate and frame heat exchanger
Don't touch. Bolts hold together with gaskets in between conduction and convection. Frame smashes plate together. Efficient and Expensive. (arrangements of plates that forms passes)
Thermal expansion prevents a
Fixed head heat exchanger from exceeding this differential temperature. (Up to 200) best suited for condenser or heater operations
Heat Exchanger's effectiveness is linked to
Flow Rate (of each process stream); Temperature (differences b/w the 2 opposing streams); Cross-sectional area of the heat exchanger
Axial
Forces fluid a straight line
Double-Pipe Heat Excahnger
Has a pipe within a pipe (hairpin) The outside provides the shell, and the inner pipe provides the tube
Fouling can be reduced by
Increasing fluid velocity/Flow and lowering the temperature; Reversing Flow
Steam generator/boiler
Is specially designed to boil water and produce high, medium and low pressure steam
No Flow No Fire
Prevents thermal flow
3 ways Heat can be transfered through
Radiant, Conduction, and Convection
Turbulent flow
Random movement or mixing in swirls and eddies of a fluid. (Allows molecules of fluid to mix and absorb heat more readily)
Laminar flow
Streamline flow that is more or less unbroken; layers of liquid flowing in a parallel path
Laminar flow
Streamline flow that is more or less unbroken; layers of liquid flowing in a parallel path.(Promotes the development of static film, which acts as an insulator)
Differential pressure
The difference between inlet and outlet pressures; represented as delta p
Differential pressure
The difference between inlet and outlet pressures; represented as delta p. (How we know fouling exist)
Differential temperature
The difference between inlet and outlet temperature; represented as delta t.
Convection
The means of heat transfer in fluids resulting from currents.
Conduction
The means of heat transfer through a solid (nonporous material resulting from molecular vibration.occur b/w closely packed molecules)
Tubes are pushed into
Tube sheets and attached to the shell
Disadvantage of Utube bundle
Very difficult to inspect or clean.(only access one side)