SPECIALISTS
Ludell takes pride in having a staff of heat transfer engineers capable of designing shell and tube heat exchangers for any application. For this reason, we call ourselves SPECIALISTS.
CONSTRUCTION
Some of the more common types of construction are illustrated with brief comments on their advantages, disadvantages, and applications. These are some of the basic styles; it should be kept in mind that certain features of one type may be incorporated into another if the application demands it. A 3 letter TEMA designation specifies the front head, shell, and rear head, respectively.
The following outlines the broad scope of design and materials available in Ludell Shell and Tube Heat Exchangers.
CODES AND STANDARDS
Any Ludell Heat Exchanger can be designed in accordance with:
- Commercial Standards
- ASME Code for Unfired Pressure Vessels Standards
- TEMA Standards (Tubular Exchanger Manufacturers Association)
DESIGN RATINGS
Most Ludell Heat Exchangers may be designed for any temperature or pressure rating. However, most common and most economical designs are up to 150 psig and 350°F.
MATERIALS OF CONSTRUCTION
Ludell Heat Exchangers may be fabricated of any combination of workable materials necessary for any application. Some typical materials are carbon steel, stainless steel, cast iron, admiralty, muntz metal, brass, cupro nickel, aluminum, or silicon bronze.
FLOW ARRANGEMENTS AND HEAD DESIGNS
Ludell Heat Exchangers may be designed for any number of tube passes from single pass, true counterflow, to as many as eight passes. This is accomplished with the use of either cast or flanged heads with either screwed or flanged connections. Some typical head designs and nozzle arrangements are shown on the illustrated units. Cast or fabricated B type heads are readily available.
Shell side flow may be multi-passed through the use of cross and/or longitudinal baffles as required. Shell side connections may also be either screwed or flanged and located as desired.
TUBE SIZES AND MATERIALS
Non-fouling applications may use small tubes with close tube spacing allowing for the maximum amount of heat transfer surface in a given package. Severe fouling applications require large tubes with wider tube spacings. For this reason, Ludell offers tubes in the following sizes to meet any application: 3/8", 5/8", 3/4", 1", 1 1/4", and 1 1/2".
These tubes are available in any gauge or material with admiralty, stainless steel, or cupro nickel being the most common.
For special applications tubes may be furnished with external fins. These special applications are usually with gases which have a low rate of heat transfer. This low rate of heat transfer is offset by providing the maximum amount of heat transfer surface through the use of finned tubes.
TYPICAL APPLICATIONS OF LUDELL SHELL AND TUBE HEAT EXCHANGERS
- Air Aftercoolers
- Air Intercoolers
- Caustic Coolers
- Chemical Solution Heaters and Coolers
- Condensate Coolers
- Diesel Engine Jacket Water Coolers
- Diesel Engine Lube Oil Coolers
- Feed Water Heaters
- Fuel Oil Heaters
- Gas Heaters and Coolers
- Laundry Water Heaters
- Machine Tool Oil Cleaners
- Magnetic Coupling Coolers
- Swimming Pool Heaters
- Torque Converter Coolers
- Transformer Oil Coolers
- Waste Water Heat Reclaimers
Different Model Diagrams and Descriptions
Straight Tube Fixed Bundle (Type BEM)
This is generally the most economical type design. However, the shell side fluid must be non-fouling since the tube bundle cannot be removed. This can be offset by either designing with sufficient fouling allowance or providing for chemical cleaning. The inside of the tubes is easily cleaned by removing heads.
Fixed Bundle with Expansion Joint (Type BEM)
Similar to Type BEM, except this exchanger can be used where severe temperature differentials exist which dictate the necessity of a unit free to expand and contract.
Fixed Bundle with Continuous Tube Type (Type LCT)
With the exclusive patented continuous tube feature this type of exchanger can be used for applications where severe plugging would normally occur, such as in laundry, textile, or paper mill applications. The continuous tube feature with a backflushing arrangement allows Ludell to firmly guarantee that such plugging will never occur. Because of "stacked" design the unit can be expanded as required by the addition of more sections. Design is based on pure counterflow of fluids for most efficient heat transfer. Temperature approaches as close as 3° can be economically achieved for certain applications.
Fixed Bundle with Hinged Doors (Type AEL with hinged covers)
Similar to Type BEM, but with its quick opening hinged doors, this unit can be used on applications requiring frequent manual cleaning of the inside tube surfaces.
Fixed Bundle Double Tube Sheet (Type BEM)
Its most common application is where absolutely no mixing of the fluids occur, such as might happen through the expanded tube joint in a single tube sheet.
Floating Head Pull Through Design (Type AET)
A floating bundle heat exchanger but the tube bundle may be removed for cleaning of the outside tube surfaces without disturbing the shell cover or floating head. Note that its construction limits it to multipass applications.
Floating Bundle with Weep Ring (Type AEW)
Design allows for bundle to be removed for inspection, cleaning, or maintenance. Floating design allows bundle to expand and contract for sever temperature differentials. Bleed holes in the weep ring will leak if there is any leakage through the packing immediately indicating the need for service. However, in most cases this leakage can easily be corrected by drawing up in the flange bolts without disturbing either the exchanger or the piping. Usually limited to low or medium pressure service.
Floating Bundle O-Ring Design (Type AEP)
This design is similar to Type AEW and construction is less costly than Type AEW, but Type AEP doesn't have a "bleeding" feature.
U-Bundle Design (Type BEU)
Perhaps the most inexpensive type of heat exchanger. Because only on end of the tube bundle is restrained, the unit is free to expand and contract on severe temperature differential service. Most common use is for heating applications where steam is the heating medium. Tube side fluid must be non-fouling since inside tube surfaces cannot be manually cleaned but bundle is removable for cleaning of the outside tube surfaces.
U Bundle Suction Heater (Type BEU suction heater)
Uses a U-Bundle for suction heating applications. Generally used to preheat, with steam or hot water, highly viscous fluids such as tar or oil so they may be pumped from a storage tank. Heating medium is circulated inside the tubes while the viscous fluid is sucked across the outside of the tubes and into the pump. The design allows the tube bundle to be easily removed for cleaning of the outside tube surfaces.