| Customized: | Customized |
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| Certification: | CE, ISO, RoHS |
| Sectional Shape: | Square |
| Material: | Stainless Steel |
| Transport Package: | Wooden Case |
| Specification: | Stainless Steel |
| Customization: |
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Audited Supplier Gasket plate and frame heat exchangers are among the most efficient designs so they are also among the most common designs in processing systems. Gaskets between plates guide the flow of product and heating/cooling fluids through alternating channels.
As hot fluids pass over the plates, heat transfers from the hot to the cold side, decreasing the temperature of the hot side and raising the temperature of the cold side.
Key to efficient operations, heat exchangers must maintain sufficient fluid velocity across plates to transfer heat while also controlling pressure drops that can disrupt operation.
Systems typically employ plate and frame heat exchangers for pasteurization, raw milk cooling, and CIP (cleaning-in-place) heating. Given their suitability for products with low to mid viscosity and few to no particulates, plate heat exchangers are also commonly used for beverage, beer, wort, eggs, sauces, and most dairy processing.
In milk processing, chilled milk is heated from, for example, 4 °C to a pasteurization temperature of 72 °C and held at that temperature for 15 seconds and then chilled to 4 °C again.
Heat always transfers from warmer substances to colder ones, so during pasteurization, heat exchangers use heat from the pasteurized milk to warm the cold milk, which saves heating and refrigeration energy. The process is called regenerative heat exchange or heat recovery, typically reaching 90% and achieving up to 95% heat recovery from pasteurized milk. Recovery is lower for higher-fat products such as cream and ice cream mix. Regeneration has a positive impact on energy savings, capital costs, and efficient operation. Heat transfer occurs rapidly when the temperature differential is high
The design of the corrugated plates creates a large but compact total surface area for transferring heat. The heat transfer area of the plates features a herringbone pattern that creates high turbulence which increases heat transfer and aids cleaning during CIP.
The plate distribution area ensures an even flow of fluid over the entire plate to maximize heat transfer. An optimized flow distribution also reduces uneven temperature zones that contribute to fouling.
While the narrow flow path of plate heat exchangers creates efficient heat exchange, the narrow path also limits its ability to process fluids to those with low to medium viscosity and few suspended particles that can result in fouling from particulates getting caught on plate contact points.
For fluids that contain particles, two solutions are available:
Both allow particles to pass through while minimizing fouling.
Instead of transferring heat through parallel plates, shell and tube heat exchangers transfer heat between a bundle of tubes surrounded by a large shell vessel. Fluids that run through the tubes exchange heat with fluids that run over the tubes contained by the shell.
Because the diameter of tubes is typically greater than the gap between plates in plate heat exchangers, shell and tube exchangers are suited to applications in which product is more viscous (resistant to flow), or contains high-density particulates. Maximum particle size depends on tube diameter. Tubular heat exchangers can typically run longer between cleanings than plate heat exchangers in ultra-high-temperature applications.
The basic shell and tube principle moves product through a bundle of parallel tubes with heating fluid between and around the tubes.
A concentric tubular heat exchanger features tubes of different diameters positioned concentrically inside of each other, which is especially efficient in heating or cooling because heating/cooling fluids flow on both sides of the product tubes. Product tubes can be sized to meet the requirements for viscosity and particulates. A concentric tube is especially suited to high- viscosity non-Newtonian fluids whose viscosity changes under pressure (shampoo, nail polish, ketchup).
As with other heat exchanger designs, shell and tube exchangers are set up to have product and heating/cooling fluids flow in opposite directions. For example, cold product fluid travels from right to left in the heat exchanger while the warming fluid travels from left to right over the product tubes. The counter-flow configuration takes advantage of maximized temperature differences for more efficient heat transfer.
One manufacturer's Pharma-line of shell and tube heat exchanger operates at pressures of up to 10 bar and operating temperatures of 150°C
Heat exchangers with double tube sheets make leaks easy to spot because they appear at the joint in the outer tube plate. The heating fluid is sealed in the shell by the first tube sheet and the second tube sheet seals the product. In the event of a leak, the leakage of either fluid is easily visually detected.
Shell and tube heat exchangers are especially effective in the pharmaceutical industry where product hygiene and demand for isolating products from heating/cooling fluids are especially high. To meet the industry's demands, high-quality tubular heat exchangers control microbe growth and prevent cross-contamination.
Some of the newest tube-in-tube designs for pharmaceutical applications feature high shear force and turbulence to maintain efficient transfer of heat while reducing bio-film.
Smaller, lighter-weight heat exchangers designed for tighter spaces can be effective substitutes for larger tube heat exchangers. They feature the same hot and cold fluid flows through alternating channels that create high turbulence for high heat transfer efficiency, while using 50-80% less heat transfer area
The many processes involved in manufacturing food, chemicals, pharmaceuticals, cosmetics, health and beauty products all require reliable heat transfer that prevents fouling from viscous and sticky products. In those processes, scraped surface heat exchangers are the right choice.
Their ability to process fluids with a high number of particulates or high viscosity make them more efficient in those applications.
Typical processing applications:
They're designed specifically for gentle product handling to avoid interference with product quality and consistency.
Scraped surface exchangers are typically mounted vertically. Inside, an electric motor turns a rotor fitted with scraping blades. To prevent damage to product, rotors and product move through the heat exchanger in the same direction, with product entering at the bottom and exiting at the top.
Scraped surface heat exchangers are common in the food and personal care industries. Ensuring continuous production requires uniform heat transfer, but the consistency or content of some food products hinders efficient heat transfer. Scraped-surface heat exchangers meet the need for efficiency by keeping product off the walls and in the mix where it belongs.
In dairy processing, products have high protein content that can foul exchangers. Fouling occurs when processed fluids stick to internal surfaces and build up over time, reducing efficiency, so part of a good hygiene program includes using equipment that stays clean for a long time and is easy to clean during CIP.
Fouling can increase pressure, so heat exchangers subject to fouling or scaling should be cleaned periodically. A light sludge or scale coating on the tube reduces its thermal efficiency. Since the difficulty of cleaning increases as scale thickness or deposits increase, operators should perform routine checks to catch fouling sources early.
In short, heat exchangers add value to pharmaceutical, food, and beverage operations in several unique ways
Heat exchangers heat the cleaning fluids that remove residues from systems components.
Heat exchangers create consistent temperatures for pasteurizing and CIP.
They heat water for effective rinsing of food production equipment (tanks and piping).
They can be placed on skids for small-footprint, flexible CIP equipment positioning.
Heat exchangers themselves are CIPable because their designs induce turbulence when systems maintain sufficient flow rate.
They transfer heat without contaminating the heated fluids.
Energy savings: regenerative heat transfer conserves energy by re-using heated fluids to heat fluids in repeatable cycles.
Liquid-to-liquid heat exchangers
A liquid-to-liquid heat exchanger is a device used to transfer heat from one liquid to another, usually by passing the two fluids close to each other but separated by a barrier. They are commonly used to make production more energy efficient.
In this article, we will explore the different types of liquid-to-liquid heat exchangers, plus applications and design considerations
Some typical applications of liquid-to-liquid heat exchangers are industrial processes such as oil refining and chemical manufacturing, as well as heating and cooling systems for buildings, power plants, and other facilities.
If you work in chemical processing, food and beverage processing, or HVAC, your process likely includes water, glycol, or oil. A liquid-to-liquid heat exchanger may be the right solution to heat or cool these liquids to dissipate unwanted heat from the process.
Pasteurisation involves heating milk to a temperature that kills bacteria. When pasteurisation is complete, the heat in the treated milk can be recovered through a liquid-to-liquid heat exchanger to preheat the cold milk and save energy. You can read more about how heat exchanges are used in milk processing in this handbook from Tetra Pak.
Many industries, including chemical manufacturing and electric power plants, produce high-temperature wastewater as a by-product. The heat in that liquid can be recovered and used in various ways (preheating the feed stream, for example) using a liquid-to-liquid heat exchanger. This cuts energy consumption, costs and environmental damage.
Several types of liquid-to-liquid heat exchangers are available, each with unique features and benefits. Here are some of the most common types of heat exchangers:
Shell and tube heat exchangers
Shell and tube heat exchangers are the most commonly used liquid-to-liquid heat exchangers. They consist of a series of tubes inside a cylindrical shell where one fluid flows through the tubes inside the shell while the second fluid of a different temperature flows around the outside of the tubes. This allows conduction between the materials, cooling one and heating the other as temperatures try to equalise.
Shell and tube heat exchangers are suitable for high-pressure and high-temperature applications. This makes them versatile and widely used solutions for heat transfer in many industries, including chemical processing, power generation, and oil and gas refining.
A spiral heat exchanger is a circular unit containing two concentric spiral flow channels, one for each fluid. One fluid enters the unit's centre and flows towards the periphery, and the other enters the unit at the periphery and moves towards the centre.
These heat exchange types are best suited for high-viscosity fluids and high-fouling applications. They also are low maintenance and have low operating costs.
Double tube heat exchangers resemble shell and tube designs but with the addition of a tube inside the nest. It provides a leak path in the event of a tube failure, avoiding costly contamination and production losses.
When designing a liquid-to-liquid heat exchanger, several factors must be considered, such as the type of fluids used, flow rates, temperature, pressure, fouling, corrosion and maintenance requirements.
In liquid-to-liquid heat exchangers, the properties of the two fluids, such as density, viscosity, thermal conductivity and specific heat, play an important role in the design. All these properties affect the heat transfer rate, pressure drop and overall efficiency of the heat exchanger.
The flow rate of the two fluids will determine the heat transfer rate and the pressure drop across the heat exchanger. Therefore, it is essential to ensure that the heat exchanger design is compatible with the mechanical characteristics of the system.
The two fluids' temperature and pressure impact the heat exchanger's design. That makes selecting materials that can withstand operating conditions essential to ensure the design meets the required safety standards.
Fouling and corrosion are significant factors that can impact the heat transfer rate and the lifespan of the heat exchanger. When designing a heat exchanger, it is vital to select materials resistant to fouling and corrosion where possible and incorporate sufficient material.
These heat exchangers can be designed with high surface area, counter-flow configurations, and optimised flow paths to increase energy efficiency. The energy efficiency of a specific liquid-to-liquid heat exchanger depends on factors such as its design, size, materials, and operating conditions.
When designing these heat exchangers, a manufacturer should make cleaning and maintenance easier to reduce the risk of contamination. Sterling TT certainly does. It's important you follow proper maintenance and cleaning procedures to ensure the heat exchanger operates safely and effectively.
As with all heat exchangers, liquid-to-liquid heat exchangers can hugely benefit your industrial and commercial applications.
Liquid-to-liquid heat exchangers efficiently transfer heat between the fluids and can help maintain the desired temperature while reducing the energy needed.
Liquid-to-liquid heat exchangers can be used for various applications and can handle different types of liquids and operating conditions. They can be made from a range of materials, including metals, plastics, and ceramics, allowing them to be used in environments where corrosion or other chemical reactions may occur.
Liquid-to-liquid heat exchangers can help to reduce the risk of contamination in industrial processes or other applications where purity is critical because they prevent direct contact between the fluids being heated or cooled.
At Sterling TT, we have over 100 years of experience designing and manufacturing heat exchangers for various industries. So, if you're looking for specialist heat exchange equipment, we are your expert.
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