What Is a Plate Heat Exchanger?
Plate Heat Exchanger is a device that uses multiple plates to transfer heat between two fluids.
Thin plates with complex pressed shapes are used to achieve high heat transfer performance. Features include being extremely lightweight and compact in size. In addition, the design can be easily changed by replacing the plates, enabling the construction of flexible heat exchange systems.
Continuous use of the system deteriorates thermal efficiency due to contamination and other factors. Plate Heat Exchangers are compact and portable, making it easy to disassemble and clean them for the purpose of restoring thermal efficiency. Many users prepare and install a spare unit for operation during cleaning.
Uses of Plate Heat Exchangers
Plate Heat Exchangers are used in many industrial fields due to their characteristics.
1. Energy Industry
In the energy industry, plate heat exchangers are used in oil coolers and gas processing. Engine oil and gear oil heat up during operation and are cooled by Plate Heat Exchangers. In addition, cooling towers for exhaust gas treatment are cooled by Plate Heat Exchangers because the waste liquid heats up.
2. Chemical Plants
This equipment is also used in many chemical plants. Temperature control is very important to control chemical reactions. Plate Heat Exchangers can slow down or accelerate the reaction rate by raising or lowering the temperature of the reactants.
Other applications include the marine industry and air conditioning systems. In the marine industry, plate heat exchangers are used in desalination plants, and in air conditioning systems, plate heat exchangers are used to cool circulating water in cooling towers.
Principle of Plate Heat Exchangers
In a Plate Heat Exchanger, several flat metal plates called plates are stacked on top of each other. Two fluids flow between them. The surface of the plates has fine protrusions, which increase the surface area of the plates and improve the heat transfer coefficient.
One fluid is channeled to one side of the plate and the other fluid is channeled to the other side of the plate. As the fluid passes between the plates, it touches the plate surfaces and exchanges heat. The cooling medium fluid absorbs heat and the heating medium fluid releases heat.
Types of Plate Heat Exchangers
There are two main types of Plate Heat Exchangers
1. Bracing Plate Heat Exchanger
Plate Heat Exchanger in which fluids of different temperatures flow between laminated plates. Heat can be exchanged even at not so high temperature differences. The greatest advantage of this method is its small size compared to other heat exchangers.
However, its disadvantage is that it is difficult to disassemble, resulting in poor maintenance performance. Since high turbulence performance can be achieved in the plates, the heat transfer coefficient is high. It is also possible to automatically clean the inside using turbulence.
2. Gasket Plate Heat Exchanger
This is a Plate Heat Exchanger in which the plates are separated by a rubber gasket. The main feature of this heat exchanger is that it can be disassembled as a whole. It has a structure in which the plates are bolted together.
Since the structure is to stack heat transfer plates, the heat transfer area can be changed to any desired area by increasing or decreasing the number of heat transfer plates. It is characterized by very high maintainability, relatively small size, and high efficiency of heat exchange.
Other Information on Plate Heat Exchangers
Plate Heat Exchanger Maintenance
Maintenance of Plate Heat Exchangers often proceeds in the following order
- Visual inspection for cracks
- Disassembly and gasket removal
- After rinsing with water, chemical cleaning and further rinsing with water
- After installation of gasket, assembly
- Liquid flow test
During the rinsing process, the gaskets are physically cleaned by jet washing and brushes. Chemical cleaning generally uses nitric acid to remove adhered scale, followed by neutralizing cleaning with caustic soda. Finally, the chemical solution is rinsed off with water.
Since concentrated nitric acid and caustic soda are used in chemical cleaning, there is a high risk of inhaling toxic nitrous acid gas or sustaining chemical injuries from the chemicals. Therefore, it is performed by technicians with knowledge of chemical substances.
Since wastewater is also difficult to treat, in most cases, maintenance is outsourced to specialized contractors or manufacturers. Major manufacturers also prepare maintenance services as a product.