Introduction

Glass Heat Exchangers are  generally available in tow major categories; Coil type and Shell & Tube type. Like any other Heat Exchangers, they can be used for variety of Shell & Tube type. Like any other Heat Exchangers, they can be used for variety of applications, namely, Condensation, Cooling, Heating, Boiling and suitable combinations of the above. The selection of equipment depends upon the type of application, heat load, availability of heating/cooling media etc. 

In all types of glass Heat Exchangers the heat transfer is through the wall of the glass tube. The heat transfer co-efficient can be of a moderate order because of low wall thickness. With 1.5 mm thick walled tubes, the wall heat transfer co-efficient is about 725 Kcals/hr m^{2 o}C and we can obtain an overall heat transfer co-efficient for steam condensation with water cooling as about 550 Kcals/hr m^{2 o}C.

the allowable pressure inside the tubes can be vacuum to 3 kg/cm² while that on the domes as well as on the shell depends upon the size of the shell corresponding to the values mentioned in Technical Specifications. The Heat Exchangers can safely be used up to 150^o C with the limitations of Thermal Shock up to 120^o C and temperature gradient across the wall less than 50^o C.

The shell side pressures on Metallic Shell & Tube heat exchangers can be as high as 2.5 kg/cm. For higher pressure requirement up to 4 kg/cm² , the PTFE tube sheets need redesigning and can be made on special request.

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Coil Condensers, Information

Composed completely of glass, coil heat exchangers are typically used as vapor condensers and liquid coolers. They are usually designed and installed as an integral part of a vertical column. To provide a reliable corrosion resistant internal seal, the coil battery is sealed to the jacket, creating a single unit. Boilers and immersion heaters are also available in this all-glass coil design.

Other Designs
We also offer glass cascade coolers, bayonet and jacketed-type heat exchangers. For further information on these special application models, please contact us.

Shell & Tube Heat Exchangers
We also offer a wide range of shell and tube heat exchangers ranging from 13.5 to 505 sq. ft., all capable of modular expansion. For further information on these units go to the heat exchanger page, or contact us.

Technical Data
Heat Transfer in Condensers
The heat transferred in coil condensers con be considered generally as 55 Btu/hr-ft2-°F for any unit. This figure may vary from 10 to 72 Btu/hr-ft2-°F depending on the fluids involved and the operating conditions.

The heat transfer coefficient also varies with the size of the condenser. The following table gives an indication of the performance of condensers at atmospheric pressure, using water as a coolant in the coils (inlet temperature 68 F) and steam condensing in the jackets. These figures do not show the maximum performance of the units but are a general indication of typical working conditions.

Condenser Catalog Reference Surface Area ft2 Water Flow Rate lbs/hr Steam Condensed lbs/hr GHE1.5 2 1540 15 GHE2 3.5 2200 25 GHE3 3.5 2200 25 GHE4 5 3300 40 GHE6/10 10 3500 70 GHE6/15 15 3300 110 GHEU9A 25 6600 198 GHEU12/25 25 6000 175 GHEU12/40 40 10400 282 GHEU450/60 60 11000 435 GHEU450/80 80 9300 585 GHEA600 120 14300 850

Applications

Coil heat exchangers are an all-glass design. There are no internal sealing problems, as the coil is welded into the jacket forming a one-piece unit. This design is a practical means of packing a large amount of heat transfer surface into a small volume.

Notes on the use of coil type condensers

1. Condensers should never be used without an adequate flow of coolant through the coils. Do not allow the coolant to become heated to boiling point.
2. Condensers should never be used with steam in the coil.
3. Take care to arrange the coolant supply in such a way as to avoid water hammer. Be certain that there is a uniform, continuous supply of coolant. (For HE 600 condensers, the fitting of an anti-water hammer device is recommended.)
4. Coolant control valves should always be turned on and off slowly, particularly when air is present in the line. Coolant should be allowed to drain freely to a point as close as practicable to the heat exchanger. Brine in a closed circuit can be used as coolant provided that suitable precautions against hammer are taken.
5. We recommend a maximum gauge pressure of 40 psig in the coils.
6. Adequate flexible hose should be used for connecting the condenser to the water main to assure that stresses are not transmitted to the glass.
7. If a condenser is to be out of service for a period of time. drain the coils. In winter suitable precautions should be taken to prevent freezing of any water remaining after draining.
8. Condensers can be mounted in a series to provide larger surface areas.

 

Note: allowing a minimum pressure drop of 30 psi (2.1 bar) will result in the most efficient overall heat transfer.

Coil Condensers, 1

All 3-outlet coil units have tubes spaced equidistant from the face to the center of the nozzle (120° spacing)

Coil Condensers, 2

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Product Coolers

DN (mm) DN1 (mm) DN2 (mm) L (mm) * (psig) Cooling Surface (ft2) CatRef 100 25 25 550 35 3.5 GHEF1/3 150 25 25 550 25 5 GHEF1/5 150 25 25 750 25 10 GHEF1/10 Maximum operating pressure in coil battery is 30 psig. * - Maximum operating pressure in cooler jacket

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Immersion Heaters, Information

immersion heat exchangers are used to control exothermic reactions in glass vessels. In most applications cooling water is used in the coils, but they can also be used with steam. In the latter case, the coils must always be completely immersed in the liquid

The HEM 6 is used in our type R spherical vessels and the HEM 9 in type E vessels. They can also be used in cylindrical vessels with special 6" or 9" bottom outlets.

The HEM 9 has a central hole through the coil to which the extended type stirrer shaft can be fitted to provide thorough mixing action.

Heat Transfer

These values may be used to approximate the overall heat transfer coefficients and the maximum allowable thermal shock for both the HEM 6 and HEM 9.

Immersion Heaters

* through coils

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Boilers, Information

Heat Transfer in Boilers

The overall heat transfer coefficient for any 4", 6", 9" or 12" unit is generally about 70 Btu/hr-ft2-°F. This is based on 50 psig steam pressure in the coils, although it declines proportionately at lower pressures. The heat transferred for the 18" unit is approximately 54 Btu/hr-ft2-°F.

The table shows representative performance data of boilers, indicating the amount of water evaporated at atmospheric pressure, with steam in the coils at various pressures.

If the feed is cold, the evaporation rate will be approximately 85% of the figures shown.

Notes on the use of coil type boilers To avoid the possibility of steam hammer, the steam main should be adequately trapped. To clear the line of the very heavy condensate flow produced on startup, bypass valves must be fitted around the trap on the coil outlet. The control valve and pressure gauge should be near the heat exchanger. Flexible hose must be used on the coil inlet and outlet, and these hoses should have sufficient fall to avoid collection of condensate. Boiler type heat exchangers should not be fitted to the bottom of flasks or columns. They are designed to be mounted on an external circulatory loop. This assures a rapid unidirectional flow across the heating surface, which improves the heat transfer performance and promotes smooth operation. On startup, the steam should be admitted positively and progressively to the coil/battery to remove the condensate as it is formed. The bypass valve should be left open until a uniform flow of condensate and steam is being vented. The steam pressure should always be adequate to assure effective and smooth condensate removal. This pressure will vary according to conditions of use and size of heat exchanger. For example, with the HEB12/12 and HEB450 a minimum pressure of 30 psig will probably be required. The maximum recommended inlet steam pressure for all boilers is 50 psig.

Boilers, 1

Boilers, 2

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Flexible Hose Assemblies

Type of Service Flange Plate Drilling (mm) NPT Size of Male Hose Fitting (in.) CatRef Water 25 3/4 GWHA1/0.75 Water 40 1 GWHA1.5/1 Water 50 1 1/2 GWHA2/1.5 Steam 25 3/4 GSHA1/0.75 Steam 40 1 GSHA1.5/1

Use these flexible hose assemblies to connect glass heat exchangers to metal service water and steam piping. Assemblies come with flange plate drilled to mate with wither  ("86" ) or ("72" ) flange; a section of rubber hose to meet the service requirement; a male, threaded end fitting (NPT) to mate with standard threaded metal pipe; and suitable connectors.

SHELL & TUBE HEAT EXCHANGERS SINGLE PASS TYPE RGG

TYPE RMG / RPG

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