Corrugated Tubular Heat Exchangers

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Corrugated Tubular Heat Exchangers

HEAT EXCHANGERS for the 21st CENTURY

Heatex • Zwanenkade 146 • 2925 AV Krimpen aan den IJssel • Tel. 0180-55 16 88 • Fax. 0180-51 37 82 email: info@heatexchange.nl • www.heatexchange.nl

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Corrugated Tubular Heat Exchangers (CTHE)

Corrugated Tube Heat Exchangers are shell and tube heat exchangers which use corrugated tubes instead of plain tubes.

Development

Corrugated Tubes take the best features of both the plain tube and the plate heat exchanger. Corrugated tube is produced by indenting a plain tube with a spiral pattern.

• Plain tubes offer the best geometry to withstand pressure but the worst for heat transfer

due to rapid build-up of boundary layer.

• Plates in a plate heat exchanger induce local

turbulence to increase heat transfer coefficient but is limiting in terms of operating pressures and temperatures due to elastomer gaskets. Also, the relatively narrow gap limits its use to fluids without large fibres and particulates.

By choosing the depth, angle and width of the

indentation carefully, the rate of decrease in boundary layer resistance can exceed the rate of increase in pressure loss.

Types

There are three types of corrugated tubes -

HARD SOFT DIMPLED

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The type of corrugations are based on the following : Corrugation depth

Corrugation pitch Corrugation angle Number of starts

to provide the optimum design in terms of area, pressure drop, fouling, etc., for the particular application.

Why were Corrugated Tubes Developed ?

• To increase tube side heat transfer coefficients, with minimum increase in pressure loss. • To overcome disadvantages of other methods of artificial enhancing the heat transfer

coefficient, viz.,

o Increased resistance to fluid flow – increased pressure loss. o Unpredictable characteristics

o Difficult to design / manufacture / replace / service. o Difficult to clean.

o Low running reliability

• To have efficient heat transfer even in liquids with high viscosity, liquids with large fibres or

particulates .

The Technology

Corrugated Tubes were developed to incorporate best features of both the plain tube and the plate heat exchanger.

Corrugated tube is produced by indenting a plain tube with a spiral pattern. This imparts different flow regimes - spiral in the core and eddy’s at the periphery.

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The helical flow contributes to the situation that the fluid particles area alternatively in the vicinity of the tube wall and then in the main flow. Between the helical impressions, around the

circumference of the tube, secondary flow, typically in the form of eddies occur.

Increase in heat transfer coefficient brings the temperature of the tube wall closer to the temperature of the bulk fluid on the tube.

Fig. A

HYDRODYNAMIC THERMAL BOUNDARY LAYER

Fig. B

The roughness elements need to have a minimum height so as to influence the flow ( Fig. A ) and thus the heat transfer ( Fig. B ). To ensure that the heat transfer is improved by roughness elements, the flow must be influenced within the heat conduction layer.

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Concept

A new style of corrugated tube is boosting heat transfer threefold at low Reynolds number with pressure loss increased twofold.

• Corrugated tube is produced by indenting a plain tube with a spiral pattern. • No tube wall thinning takes place & no strength is lost.

• A smooth indented inner profile ensures easy cleaning.

• Turbulence is created at low fluid velocities to enhance the heat transfer in the tube. • Fouling on the tube surface is minimised.

• A wide range of diameters & styles are available.

Models

Corrugated Tube Heat Exchangers are produced in four configurations.

• B-type Series : Multi-tube for Industrial use

• Multi-tube Series : for food industry and pharmaceutical use • Mono-tube : for fluids containing particles and/or fibres • Triple-tube Series: for aseptic applications

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B-type Series

The B-type Series heat exchanger consists of a bundle of tubes within a common shell. Welded or expanded tube to tube-plate joints are available.

Designed to be pipe mounted.

Uses loose carbon steel backing flanges onto stainless steel collars. Fixed or de-mountable units are available.

A wide range of corrosion resistant materials are available.

A wide range of tube and shell diameters and tube counts are available. Can comply with TEMA and other pressure vessel codes where required.

Can be fitted with baffles and multi-pass headers to improve heat transfer efficiency to suit specific applications.

Features

• CORRUGATED TUBES & PLAIN SHELL. • FIXED TUBE SHEET.

• STD. TUBE SIZE : 18 / 25 mm, LENGTH 1.5 - 6 mtr. • MAT : AISI 304, AISI 316, Ti & NICKEL ALLOYS.

• MAX. WORKING PRESSURE : PROCESS SIDE 16 BAR G SERVICE SIDE 16 BAR G.

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Multi-tube type Series

This type consists of a bundle of tubes within a common shell. Welded tube to tube-plate joints.

The design allows all tube-side surfaces to be polished to pharmaceutical standards after manufacturing.

All areas which could harbour impurities or dirt are eliminated. Ideal for effective CIP cleaning.

Tube plate design allows vertically mounted units to drain fully. Fully welded de-mountable designs are available.

A wide range of different tube diameters, shell diameters & tube counts are available.

Features

• MULTIPLE TUBES IN A SHELL.

• CORRUGATED TUBE AS WELL AS SHELL. • SPECIAL TUBE SHEET.

• STD SIZES : 18 mm TUBES, SHELL UPTO 6. , 3 TO 6 METRE LENGTH. • MAT : AISI 304, AISI 316.

• MAX. WORKING PRESSURE : PROCESS 25 BAR G SERVICE SIDE 16 BAR G.

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Mono-tube Series

This type is a single pipe within another larger diameter pipe.

Ideally suited to heating or cooling most process liquids & gases containing particles or fibres.

They can designed to withstand very high pressures & temperatures in a wide range of corrosion resistant material.

They can be built to suit the individual clients requirements. Multiple units can be mounted in a common support structure. De-mountable as well as fully welded designs are available.

Features

• TUBE IN TUBE.

• CORRUGATIONS ON SHELL AS WELL AS TUBE.

• STD SIZES : 1. INNER TUBES TO 6. OUTER TUBES, 3 OR 6 METRE LENGTH. • MAT : AISI 304 & 316.

• MAX. WORKING PRESSURE : 16 BAR G AT 120 oC.

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Triple-tube Series

Triple tube type using a three corrugated tubes within each other.

Service media flows in the innermost and outermost tubes with the process media flowing in the annulus between them.

Ideally suited for aseptic applications.

Ideally suited to heating or cooling most process liquids & gases containing particles or fibres.

They can be designed to withstand very high pressures & temperatures in a wide range of corrosion resistant material.

Multiple units can be mounted in a common support structure. De-mountable designs are available.

Features

• TRIPLETUBE CORRUGATED HEAT EXCHANGER. • ANNULAR SPACE CONSTRUCTION.

• STANDARD SIZES :

• INNER TUBES 1. TO OUTER TUBES 6. • LENGTH - 3 OR 6 METRE.

• MAT : SS 304 & SS 316.

• MAX. WORKING PRESSURE : 16 BAR G AT 120 ° C.

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Design

HRS Spiratube can provide heat exchangers to a variety of National and International standards including :

• ASME VIII Division 1 • TEMA

• BS 5500

• AD Merkblatter

Advantages

• COMPACT SIZE.

• LOWER HEAT TRANSFER AREAS. • REDUCED FOULING.

• LOW MAINTENANCE COST. • HIGH RESPONSE TO CIP. • WIDE CHOICE OF MAT.

• UNIFORM THERMAL PROCESSING.

• MORE FLEXIBILITY IN ANNULAR SPACE SIZING. • LONG RUNNING TIMES.

• MONOTUBE SERIES CAN HANDLE LARGE PARTICLES UPTO 50 mm SIZE.