Have you noticed decreased efficiency from your heat exchanger or circulation heater? So much so that your process is now operating out of acceptable temperature, pressure drop or flow range? You are most likely having significant fouling issues.
The most common reasons heat exchangers don’t provide the heat transfer rate they were designed for or have increased pressure drop from occlusion, is what we call fouling. Fouling is the buildup of sediments, mineral calcification and/or debris from the process that settles onto the surface area of a heat exchanger or circulation heater.
During the design stage, Thermal Products will inquire about specific process media makeup and the cooling or heating media. Thermal Products will ask you about the suspended solids, mineral content, and chemical content along with the typical needs of flow rate, heat load and temperatures in and out of the heat exchanger. With the provided information the Thermal Products design engineers will take into account the appropriate fouling factor to maximize the lifespan of the heat exchanger or preventative maintenance interval, reducing unexpected costs for the plant. The fouling factor essentially increases the surface area, over and above what is needed in order to perform the required heat load duty.
What are the different types of fouling?
Scaling is one of the most common types of fouling. Minerals and Salts commonly found in natural waters have a lower solubility in warm water than cold. Therefore, when cooling water is heated during the cooling process, particularly at the tube wall or plate wall, these dissolved salts will crystallize on the surface in the form of scale.
Thermal Products will design a heat exchanger or circulation heater with a lower tube temperature or watt density respectively, reducing the tube wall or element temperature. The Thermal Products design engineers will also look at process velocities through the heat exchanger or circulation heater, as slower velocities can exacerbate the problem.
This is noticed typically in the use of cold well water or open cooling tower applications.
Sedimentation, is the depositing of dirt, sand, rust, and other small debris and is most common when fresh water is used. This type of fouling typically leads to the heat exchanger or circulation heater becoming impacted and will completed occlude the flow, if left untreated. This can be controlled to a degree by the heat exchanger design through velocity control, but need to be careful as increasing the velocity too much will lead to erosion of your tubes or elements. Thermal Products will also design and offer upstream filtration or straining equipment to assist in removal of this type of debris before it gets to the heat exchanger or circulation heater.
If your process is sensitive, Thermal Products can design a closed-loop heating or closed-loop cooling process to eliminate the issues of sedimentation fouling completely.
Biological/Organic growth material typically occurs in marine, chemical, or bioorganic applications and can cause considerable damage if allowed to build up. Thermal Products can design a heat exchanger or circulation heater that can be resistant to biological fouling or organic fouling using different materials and design considerations.
Chemical Reaction Coking appears in oil heating applications, where the heat exchanger tubes or circulation heater elements are too hot. When the oil comes in contact, it burns the oil and deposits the resulting hydrocarbon on the heating surface. If left and the situation is not corrected, it will lead to premature failure of the heat exchanger or circulation heater. All oils are susceptible to Coking, but at a wide range of temperatures, dependent on the oil type.
As in mineral Scaling, Thermal Products will require the type of oil used so we can determine its flash point, thermal conductivity, specific heat and specific gravity so we design the proper heat exchanger or circulation heater.
Heat Exchanger and Circulation heater design are far more involved than looking at fouling, but it is an important factor to include when performing the design.
Any fouling, left untreated will result in the failure of that heat exchanger or circulation heater. The failure can be catastrophic in some cases.
As touched on earlier, Thermal Products can reduce the fouling possibilities greatly, by “closing the loop” if fouling is a chronic problem for your process. Thermal Products can design a Chiller, Closed loop cooling, closed loop heating or offer fired process heaters to perform the heating or cooling as your process dictates.
Contact any member of the Thermal Products team to discuss your process needs.
A Gas Compression company needed to reduce the noise level of their package by 20 dba measured at 3 meters from the core of the machine. The air temperature within the sound enclosure must remain at ambient temperature while accounting for 1,900,000 btu/hr heat rejection from the electric motors and compressor cores. The customer also needed the interior of the enclosure to be lighted with electrical outlets. Customer also required alarms notifying them of a gas leak.
This project required a complete sound enclosure measuring 30 ft long by 21ft wide and 12 ft high which encompassed the entirety of the gas compressor skid package. The design of the enclosure walls was required to be 4” thick with an inner perforated metal wall and an outer solid steel skin. We designed the inner mineral wool density to handle the noise reduction.
• Sound enclosure
• (2) doors
• (1) intake plenum and silencer
• (1) exhaust fan
• (4) light fixtures
• (4) light switches
• (1) gas detection system
The enclosure was designed with (1) 12,000 cfm exhaust fan with intake silencer and a 3HP explosion proof motor. To maintain ambient temperature inside the enclosure there needed to be an air flow switch and thermostats to control the fan operating and at what speed. Included was a gas detection system encompassing 4 individualized sensors wired back to a centralized enclosure alarm system tied to the customer’s main system. (2) light fixtures were mounted to the interior of the roof and (2) mounted above each of the (2) entry doors. Each door also had a light switch mounted to the entry point.
Thermal Products Advantages:
Thermal Products can offer an initial sound study completed to ensure you receive a properly designed sound enclosure. Every enclosure is factory assembled to ensure form, fit and function. Your enclosure can either ship assembled or in a kit disassembled. Our enclosures can either be finished with our in-house powder coat, galvanized steel or stainless steel. Although our enclosures are quite easy to assemble with the proper equipment, we do offer and perform onsite assembly from our trained factory assembly team.
When a local Biodiesel company decided to grow their process, there were several capacity challenges that they faced. Thermal Products Inc. was consulted to help address the process cooling system utilized during the reclamation of methanol from the vegatable oil recycling process. We designed a cooling tower and pump skid from Advantage Engineering and condensers from API Heat Transfer's Plate Heat Exchanger and Shell and Tube Exchanger groups.
The collected vegetable oil waste from area commercial kitchens and food process plants is heated, broken down, and cleaned with an alcohol based fluid. One of the results of this process is the by-product, Methanol. Reclaiming methanol is both environmentally sound and cost effective. The cooling challenge was that both vegetable oil and methanol reach high temperatures of 260F during the process. Once separated, the methanol vapor must be condensed back to a liquid, stored, and readied for reuse.
Thermal Products designed and offered an Advantage Engineering 45 ton evaporative cooling tower to provide a top end of 85F cooling water to an API Heat Transfer Shell and Tube exchanger that was designed to condense the Methanol to an inital 100F. This was achieved by the steady year round 85F water temperature that the tower could provide to a pump tank station combination.
The Methanol at 100F still needed to be at a final temperature of 60F. Due to limitation of a cooling tower to provide 85F water during the summer months, a "trim" 15 ton water cooled chiller from Advantage Engineering, was provided to supply 50F chilled water to the API Heat Transfer plate and frame exchanger to reach the desired Methanol temperature of 60F.
With high energy costs being a real challenge to process plants and their ability to be competitve, Thermal Products designed a hydrid process cooling system to have the majority of the heat load handled by an inexpensive open cooling tower and pump skid system. Thermal Products then designed the "trim" cooling system for summer operation with the use of a small water cooled chiller.
Employing the provided hydrid process cooling system not only cut capital costs for the equipment, but the operation costs were much lower than they would have been if just employing a refrigerant chiller for the entire heat load.
High Temperature Vacuum Air to Air Heat Exchanger
Thermal Products was asked to design a custom air-to-air heat exchanger designed to cool 2,346 ACFM air from 750F to 194F at a negative pressure of 10.1” hg. The design ambient air temperature of 149F created a very tight approach temperature that we needed to overcome. The Maximum Noise level required was 85 dba at the heat exchanger. Maximum pressure drop required was .12” HG.
Installation location is in the upper housing of vacuum crane for loading and offloading ships and barges. Overall size and weight was critical to the design.
Thermal Products designed and built the above/below custom air-to-air heat exchanger. The overall construction was from carbon steel with the Heat Exchanger Coil manufactured for cleanability for the extremely dusty environment. The coil was manufactured with a stainless steel inner tube and an aluminum extruded fin. The extruded fin allows our customer to clean the coils with high pressure water as part of the preventative maintenance routine.
Thermal Products used a low noise Aluminium fan that was manually adjustable to achieve the noise requirements.
Engineered solutions to industrial applications is what Thermal Products shines at. Contact us today with your custom needs.
TEMA stands for “Tubular Exchangers Manufacturers Association” and is a set of standards that were developed by leading shell and tube manufacturers. These standards define the style of heat exchanger and the machining and assembly tolerances. One of the advantages of selecting a shell & tube manufacturer that builds to TEMA specifications is that the end-user is assured that they will receive and install a piece of equipment that is built to certain specification’s and criteria.
There are 3 major TEMA classifications, which are as follows;
TEMA C – General Service
TEMA B – Chemical Service
TEMA R – Refinery Service
TEMA C is the least restrictive and most widely used. TEMA B and TEMA R are similar in requirements and typically require features like, confined gaskets joints, spiral wound gaskets along with some greater minimum thicknesses on some parts.
TEMA designations refer to portions of the unit that make up the complete heat exchanger. IE: TEMA Type BEM would have the “B” representing the front head, the “E” the core or middle section and M representing the rear head designs.
The figure below is helpful in visualizing each segment.
TEMA Designs Available:
Straight Tube and Fixed Tube Sheet: Types BEM, AEM, NEN, etc
This design is the simplest design and most economical in most cases. The tube sheet is welded to the shell and heads are bolts to the tube sheet.
• Less costly than removable bundle designs
• Capable of multiple pass designs
• Shell side can only be cleaned by a chemical solution
• No ability to absorb thermal expansion between the outer shell and tube bundle
Removable Bundle and Externally Sealed Floating Tube sheet: Type AEW, BEW
This design allows for the tube bundle to be removed for inspection and cleaning. With Basco’s OP design, the head can be removed for inspection of the interior of the tubes, without releasing the pressure on the shell side process.
• Floating tube sheet allows for Thermal Expansion
• Shell side can be inspected and mechanical cleaned
• Tube bundle can be replaced or repaired without breaking the piping on the shell side.
• Maximum surface area for specified shell diameter for a removable bundle
• Tube side passes are limited to one or two passes
• Packing material limits operational pressure and temperature
• Intercoolers and After coolers
• Coolers with water in tubes
• Jacket water coolers and Oil coolers
Removable Bundle, Outside Packed Head: Type BEP, AEP, etc.
This design allows for the easy removal, inspection and cleaning of the shell side circuit and shell interior without removing the floating head cover. Special floating tube sheet prevents intermixing of fluids. In most cases, straight tube removable bundles are a more costly design that U-tube designs.
• Floating tube sheet allows for differential thermal expansion between the shell and tube bundle
• The tube bundle can be repaired or replaced without disturbing shell piping
• Tubes can be serviced without disturbing the tube side piping on AEP designs
• Less costly than TEMA BES and BET designs
• Provides a large bundle area entrance reducing the need for entrance domes for proper fluid distribution
• Flammable or toxic liquids in the tube side circuit
• Good for high fouling fluids in the tube side circuit
Removable Bundle, Internal Split Ring Floating Head: Type AES, BES, Etc.
These designs are best for applications when frequent tube bundle removal is necessary. More favorable to thermal shock than AEW or BEW designs. This design is suitable for volatile or toxic fluids.
• Floating head design allows for thermal expansion
• Maximum surface area for specified shell diameter than a “pull through” designs like AET or BET
• Available to multiple passes on tube side
• Shell cover, split ring and floating head cover must be removed to remove the tube bundle, results in higher maintenance costs
• Chemical processing applications for toxic fluids
• Special gas intercoolers and after coolers
Removable Bundle, Pull Through Floating Head: Type AET, BET etc.
These designs are best for applications when frequent tube bundle removal is necessary as the floating head is bolted directly to the floating tube sheet. This allows the bundle to be pulled complete, with the head.
• Floating head allows for thermal expansion
• Shell side can be inspected or mechanically cleaned
• Provide a large shell side nozzle entrance area for proper distribution over the bundle
• Multiple tube side passes available
• Suitable for volatile or toxic fluids
• Chemical processing applications for toxic fluids
• General industrial applications requiring frequent cleaning
• Hydrocarbon fluid condensers
Removable Bundle, U-tube: Type BEU, AEU etc.
This design is best suited for maximum thermal expansion applications. Each tube has the ability to expand and contract independently. This design is suitable for high thermal shock applications. U-tube bundles are very economical.
• The U-tube design not only allows for differential thermal expansion between the shell and tube bundle, but also each tube individually.
• Shell side can be inspected and cleaned
• Least costly design for removable bundles
• Multiple tube side passes are available
• Capable of handling high thermal shock applications
• Bundle can be removed from one end for cleaning or replacement
• Oil, chemical and water heating applications
• Optimal for steam to liquid applications.
In northern climates “shut-downs” can wreak havoc on your process when cooling tower basins freeze and upon “start-up”, cannot flow water to cool your process.
Thermal Products offers Indeeco’s pre-engineered, UL Listed/CSA Approved package for freeze protecting cooling tower basins.
Heaters are pre-set at the factory with a set point of 45F and will fit all tower manufactures below.
The Advantages of the Indeeco Cooling Tower Basin Heater package are as follows:
Outmoded bulb and capillary control has been replaced with new patented solid-state technology which combines temperature control with low water level protection in a single solid-state device.
NEMA 4X Enclosure Most controls are factory wired inside a rugged NEMA 4X enclosure designed for wet, outdoor use. Pre-engineered designs up to 96 amps are available with stock and built-to-order listings, two circuit panels use a NEMA 4 enclosure.
Installation time and cost are reduced by replacing individually mounted temperature and liquid level control devices with one pre-engineered and assembled control package that requires only one probe to sense both water temperature and level.
Sensor Probe Specifications :
Sensor Probe : INDEECO probe assembly incorporating both temperature and liquid level sensors.
Probe is made out of 316 stainless steel to minimize corrosion. Probe can be installed vertically or horizontally.
Maximum Pressure Rating for Sensor Probe : 15 psi
Cord : 12-foot outdoor rated cord with PVC hub connector for installation through tower basin wall. Options include different cord lengths or cord suitable for total immersion.
Heat transfer manufacturer API Heat Transfer is aimed on advancing and testing the development of its air cooled, shell and tube, and plate products. They have installed a calorimetric air flow test lab which can simulate aitr flows to 30,000 scfm and air temperatures within engine compartments.
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There are 10 major factors one should consider when deciding between open coil, finned tubular and tubular heater construction types for process heaters. Within these ten factors, the first four are key. If one heater type dominates these four considerations with its benefits, chances are it’s the right choice. If there’s no clear winner among these first four, the other six variables must be considered to determine the best design for the application.
A cooling tower primarily uses latent heat of vaporization (evaporation) to cool process water. Minor additional cooling is provided by the air because of its temperature increase. Cooling tower selection and performance is based on water flow rate, water inlet temperature, water outlet temperature and ambient wet bulb temperature.
Electric circulation heaters offer an efficient, economical means of heating water, oil, air or other liquids and gases. Careful planning and attention to heating requirements are essential to ensure that the heater you select will provide optimal performance for your application and offer years of trouble-free operation.