double tube

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DOUBLE TUBE COOLER

Industrial applications

www.bloksma.net

Safety-range heat exchangers


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Introduction

In case prevention of intermixing of fluids becomes an importantissue it is strongly recommended to use the Bloksma Double Tube(DT) safety cooler.

The Bloksma DT Safety cooler excludes the risk of intermixing offluids caused by leakage of the tubes.In case a leakage occurs, a detection system is activated whichenables the user to take adequate measures to avoid intermixingof fluids or leakage into the environment.

DOUBLE TUBE COOLER Industrial applications

Applications

- Transformer Oil coolers- Oil coolers where environmental or mechanical damage should

be avoided under all circumstances- Process Coolers

Principle

The principle of the Double Tube cooler is fairly simple. The singlewall between the 2 fluids is replaced by 2 walls with an intermedi-ate circuit. Any damage in one of the tube walls will result in afilling of the intermediate circuit. This filling is detected and resultsin an alarm signal.

As alternative for the Double Tube cooler the use of a secondarycircuit could be considered. This alternative however needs asecond heat exchanger. This secondary circuit needs conditionedcooling water, extra pumps, piping valves etc. The required heatexchangers are larger due to an adverse LMTD (LogarithmicMean Temperature Difference) and, as a consequence, more

expensive as well as in investment as operation.

Single tube Double tube

All design options used for single tube heat exchangers are alsopossible with the double tube construction, so different materialcombinations and cooler constructions are possible, depending onthe fluids used.


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Construction

To realize this principle of 2 walls with an intermediate circuit, aninner and an outer tube are assembled into one physical tube. Theouter tube is on the inside provided with longitudinal leak detectiongrooves. The inner tubes are mechanical bonded over the full lengthagainst the outer tube to ensure a perfect metallic contact. Also 2tube sheets on each side are used instead of one.The grooves are in open connection with the space between the twotube sheets.

In case of oil as primary fluid, an increased efficiency is obtained byusing externally finned outer tubes, resulting in a compact design.

The materials of the tubes can be different. The outer tube is pref-erably made of copper. In case contact between copper and coolingmedium is not allowed it will be possible to provide the tubes with atin (Sn) layer. It is obvious that the thermal calculation is also basedon the material-choice of the tubes.

The construction of the Double Tube cooler does not require spe-cific measures for the cooling system, such as a minimum operatingpressure.

Detection.

To detect any fluid in the intermediate space, leakdetection equip-ment is required. A special connection between the 2 tubeplates isprovided for mounting the leakage detector. The principle of theleakage detector is based on a change in capacity between 2 con-ductors. A switch, which is connected to the alarm system, is acti-vated. This leakage detector is normally included in the supply.


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Bloksma The Netherlands

Bloksma Heat ExchangersBloksma is known over the world as an innovative, dedicatedand reliable heat exchanger partner. For more than 80 yearsBloksmas success is based upon quality products, broad experi-ence, research & development and long term relationships withcustomers.

Sales support offices:

Bloksma-Fryer, France Bloksma-Asia, Singapore

Bloksma International, The Netherlands

Bloksma worldwide agent network Bloksma designs and manufactures its products to the higheststandards to ensure a long operational lifetime and durability. Ifrequired, the products can be quality assured by all main certifi-cation authorities. Bloksma provides a complete after sales ser-vice from supply of spare parts to inspection, maintenance andrepair.

Bloksma product range:

Compact plate fin oilcooler

Charge-air cooler

Box cooler

Oil & water heater

Water cooler

Steam condenser

Dump cooler

Compressor cooler

Repair service

Service and spare parts

For additional information visit our website: www.bloksma.net

Bloksma Heat ExchangersDraaibrugweg 15, NL-1332 AB AlmereP.O. Box 1003, NL-1300 BA AlmereThe Netherlands

T +31 36 549 23 00F +31 36 549 23 90

E [email protected] www.bloksma.net

double tube

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