Plate type heat exchanger
Transcript of Plate type heat exchanger
PLATE HEAT EXCHANGER
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another.
They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing and sewage treatment.
In heat exchangers, there are usually no external heat and work interactions.
Common examples of heat exchangers are shell-and- tube exchangers, automobile radiators, condensers, evaporators,
air preheaters, and cooling towers.
Types Of Heat Exchangers
Double pipe heat exchanger
Shell and tube heat exchanger
Plate heat exchanger
Plate and shell heat exchanger
Plate fin heat exchanger
Spiral heat exchangers
What is a plate type heat exchanger?It’s a type of Heat Exchanger which consists of many corrugated stainless-steel sheets separated by polymer gaskets and clamped into a steel frame
•Plate heat exchangers transfer heat by placing thin, corrugated metal sheets side by side and connecting them by gaskets.
•Flow of the substances to be heated and cooled takes place between alternating sheets allowing heat to transfer through the metal sheets.
Parts & Their Function
1. FrameThe frame is made up of thick steel
pressure retaining parts, the fixed cover and the movable cover,
that when pulled together with the tightening bolts form the pressure retaining structure for the plates / plate pack .
The carrying bar and guide bar act as a carrier and guide to both the plates and the movable cover
The heat exchanger plates, which make up the heat transfer surface, are clamped between two plates of steel with the use of the tightening bolts.
The heat exchanger construction allows a plate heat exchanger to be easily opened for inspection and cleaning.
Each plate has a gasket that produces a sealing and channel system through the entire plate pack in which the two heat exchanging media flow in a counter-current direction.
The circular portion of the gasket stops the fluid from going across the heat transfer plate and sends it to the next open channel.
The remaining portion or field gasket directs the opposing fluid across the heat transfer surface.
4. Flow Arrangement
The heat transfer plates with gaskets are arranged in an alternating pattern of left hand flow and right hand flow to direct the fluids in an opposing direction within the heat exchanger.
The completed assembly of all the plates and gaskets is called the “plate pack.”
Why Plate Heat Exchanger?
High heat transfer areaHigh heat transfer coefficientCompact and has lower floor space requirements.By increasing the number of plates the area of heat
exchange can be increasedMost suitable type heat exchangers for lower flow
rates and heat sensitive substances.Multiple duties can be performed by a single unit
Classification of Plate Heat Exchanger
Gasketed plate heat exchangers (plate and
frame heat exchangers)
Brazed plate heat exchangers
Welded plate heat exchangers
1. Plate and frame heat exchangers
Plate and Frame Heat Exchanger
Most common type of PHEConsists of plates and gasketsMaterials: stainless steel, titanium and non-metallicOperation limits:
- temperatures from -35°C to 220°C
- pressures up to 25 bar
- flow rate up to 5000 m3/h
2. Brazed Plate Heat Exchanger (PHE)
Brazed Plate Heat Exchanger
Operates at higher pressures than gasketed unitsMaterials: stainless steel, copper contained brazeOperating limits:
- From -195°C to 200°C- Pressures up to 30 bar
It is impossible to clean. The only way is by applying chemicals.
3. Welded Plate Heat Exchanger (PHE)
Welded Plate Heat Exchanger
Plates welded together to increase pressure and temperature limitsMaterials: stainless steal and nickel based alloys. Can be made
with copper , titanium or graphiteOperation Limits:
- temperature limits depend on the material
- can tolerate pressures in excess of 60 bar
BENEFITS OFFERED BY PLATE HEAT EXCHANGERS
Lightweight: The PHE unit is lighter in total weight than other types of heat exchangers because of reduced liquid volume space and less surface area for a given application.
High-viscosity applications: Because the PHE induces turbulence at low fluid velocities, it has practical application for high-viscosity fluids
Saves space and servicing time: The PHE fits into an area one-fifth to one-half of that required for a comparable shell and tube heat exchanger. The PHE can be opened for inspection, mainte- nance.
Lower liquid volume: Since the gap between the heat transfer plates is relatively small, a PHE contains only low quantities of process fluids. The benefit is reduced cost due to lower volume
Lower cost: PHEs are generally more economical than other types of equivalent duty heat exchangers due to the higher thermal efficiency and lower manufacturing costs.
Quick process control: Owing to the thin channels created between the two adjacent plates, the volume of fluid contained in PHE is small; it quickly reacts to the new process condition
and is thereby easier to control.
LIMITATIONS OF PLATE HEAT EXCHANGERS
The maximum allowable working pressure is also limited by the frame strength and plate deformation resistance. Commonly stated limits have been 300°F (149°C) and 300 psi
Because of the narrow gap between the plates, high liquid rates will involve excessive pressure drops, thus limiting the capacity.
Large differences in fluid flow rates of two streams cannot be handled.
The gaskets cannot handle corrosive or aggressive media. Gaskets always increase the leakage risk The standard PHEs cannot handle particulates that are larger than
Particulate fouling or siltingSolid particles are deposited on the heat transfer
Deposition and growth of organism on surfacesChemical reaction fouling
Arises from reactions between constituents in the process fluids
Freezing or solidification foulingOccurs when the temperature of a fluid passing
through a heat exchanger becomes too low
ConclusionPlate heat exchangers are available in a wide variety of
configurations to suit most processes heat transfer requirements.
The advantages of PHEs, and associated heat transfer enhancement techniques, extend far beyond energy efficiency.
Lower capital cost, reduced plant size, and increased safety are typical of the benefits arising from the use of PHEs.
Plate heat exchangers can replace some normal size heat exchangers bringing advantages and performance.