Heat transfer technologies are highly valued within modern manufacturing. Heat transfer systems are present in a wide spectrum of industries and industrial processes. From beverage processing to oil and gas refinement, heat transfer processes play critical roles in production lines. The versatility of heat transfer technologies allows for a variable set of uses. Heat exchangers and other heat transfer systems have the compacity for cooling, heating, condensing and evaporating, allowing these systems an uncommon versatility.
Direct heat transfer systems are processes where the heat source and the product have direct contact. UHT or Ultra High Temperature treatment, a direct heat transfer method, is the use of steam to heat a product to 130 to 150 degrees Celsius. These heat transfer systems fall into two categories, injection and infusion. Injection based heat transfer is the integration of metered amounts of steam into a product. Infusion is forcing a product through steam to transfer heat directly. Both methods heat products rapidly with a very short holding time, to minimize chemical changes within the product. This process sterilizes the product within the UHT system, extending its stability. UHT treatment is often a key component of flavored milk, creams, soups, sauces, desserts, prepared fruit and dairy alternative production.
Scraped-surface heat exchangers, using indirect heat transfer, consists of a product flowing through a product tube, with the heating or cooling media flowing around that product tube through a “jacket”. The separation of heat or cooling media and product is the defining attribute of indirect heat transfer systems like scraped-surface heat exchangers. Scraped-surface heat exchangers are also defined by the rotating blades on the mutator shaft within the product tube. The mutator shaft and the blades rotate to remove product from the heat transfer wall, reducing the chance for fouling and enhancing heat transfer. Scraped-surface heat exchangers are often used in heating, cooling, crystallization, pasteurization, sterilization and gelatinization processes.
Scraped-surface heat exchangers are designed in three subtle variations. A scraped-surface heat exchanger with the mutator shaft mounted in the center of the product tube is a concentric scraped-surface heat exchanger. A concentric design is used for most applications. An eccentric design refers to a scraped-surface heat exchanger where the mutator shaft is mounted slightly off center in the product tube. Eccentric scraped-surface heat exchangers are used for more viscous or sticky products, as the eccentric design minimizes product build up on the shaft and maintains heat transfer efficiency. Lastly, an oval design is used to process extremely viscous products. Oval scraped-surface heat exchangers feature a product tube with an oval cross section that allows for additional blade movement to prevent product build-up on the shaft.
Plate Heat Exchangers are an indirect method of heat transfer consisting of metal plates bound and heated to transfer thermal energy across a much larger surface area than other types of heat exchangers. SPX FLOW heat transfer engineers develop plate heat exchangers specialized to the customer’s need. Custom plate heat exchangers often vary in the number of plates bound in the heat transfer system. Plate heat exchangers may also differ in the design of the thermal plates themselves. Different configurations etched into the plate influence the thermal hydraulic performance of the heat exchanger. For example, the corrugations or etchings on each plate may promote more turbulent product flow, decreasing fouling through higher product movement.
Plate heat exchangers are also designed with three separate flow directions, each ranging in how effective heat transfer occurs within the system. Plate heat exchangers utilizing a counter flow system direct two fluids in opposite directions separated by a plate. Counter flow plate heat exchangers allow for the highest rate of heat transfer. Concurrent flow plate heat exchangers direct fluids in one singular direction, leading to more even temperatures. Crossflow plate heat exchangers are the middle ground between the other two methods. The crossflow method streams fluids at 90-degree angles of one another.
Tubular Heat Exchangers are an indirect method of heat transfer consisting of tubes inside of tubes. There are many possible configurations of tubular heat exchangers, including double tube, triple tube, quadruple tube and multitube. Tubular heat exchangers are used in medium viscosity applications that may or may not contain particles and where fouling is not likely to occur. Their applications include beverages, drinking yogurts, vegetable purees, sauces, etc. with a variety of processes such as heating, cooling, pasteurization, sterilization, melting, and condensing.
Double Tube Tubular Heat Exchangers consist of two concentrically positioned tubes. The product flows inside the inner tube and the media/service fluid flows through the annular space between the inner and outer tubes. Triple Tube Tubular Heat Exchangers consist of three concentrically positioned tubes, with the product flowing through the annular space between the inner-most and outer-most tubes. Quadruple Tube Tubular Heat Exchangers feature four concentrically positioned tubes, with product flowing in the annular space between the second and third tubes. Multitube Tubular Heat Exchangers have several smaller diameter tubes aligned in parallel within a larger diameter outer shell. The product flows through the smaller diameter tubes.
Heat transfer for the dairy industry is centered around hygienic and efficient design. The pasteurization of milk and cheese products is vital to the elimination of microorganisms within dairy products. However, its often not possible to pasteurize all milk at reception, so many dairies implement thermalization. Thermalization is the process of pre-heating milk temporarily, to a point below pasteurization, to limit bacterial growth. A plate heat exchanger for thermalization specifically may vary highly from a plate heat exchanger for pasteurization. A thermalization based heat exchanger will hold the dairy product for a much shorter period of time. This is reflected in the design of a thermalization plate heat exchanger, ranging from fewer plates, wider corrugations and a concurrent flow direction to lessen heat transfer and heating longevity.
Heat exchangers for beverage processing, much like diary processing, are focused on the pasteurization of products. Juices require pasteurization for the sterilization of the juices for consumption. The challenge of designing a heat transfer system for juices is the careful process needed to retain the natural qualities of the beverage. Ensuring the taste, color and nutrients are retained post heat transfer is vital to modern beverage production.
Heat transfer is highly variable within the personal care industry due to the varying viscosities of personal care products. Because personal care applications such as lotions and creams are more viscous, heat transfer for this industry is typically addressed with Tubular or Scraped-Surface Heat Exchanger technology. Highly viscous products will be practically inoperable within a plate heat exchanger, while a thinner, more fluid products would benefit from a plate heat exchanger. In many cases a scraped surface heat exchanger is recommended due to the nature of many personal care creams and lotions.
Heat exchangers are vital to the refinement process of crude oil. Heat exchangers are utilized to “crack” the hydrocarbons that crude oil is composed of. “Cracking” is a thermal process to expose the hydrocarbons in crude oil to enough heat to cause a thermal decomposition reaction. The post processed crude oil can then be used to create polymers and fuels.
Heat exchangers for chemical processing must be designed intentionally to withstand aggressive chemicals. SPX FLOW custom designs heat exchangers for the heat transfer of aggressive chemicals, with a range of solutions. SPX FLOW ParaWeld is plates or a plate heat exchanger that are welded to pairs, for higher sustainability when processing chemicals. SPX FLOW application engineers can also design a heat transfer system with specifically resistant metals.