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Plate heat exchangers (I)

In this article we try to explain the operation and basic principles of plate heat exchangers. Being a widely used mechanical element, the operation of plate heat exchangers is of special interest to engineers, maintenance personnel, purchasing managers, heating and cooling installers, etc.
In the future we will break down the operation of plate heat exchangers according to their sector and application, but in this first approximation, we will focus on basic aspects of plate heat exchangers.
 
What is a plate heat exchanger?
 
Plate heat exchangers are mechanical devices that allow temperature exchange between fluid-fluid, fluid-gas or gas-gas. first plate heat exchanger Plate heat exchangers were invented and patented by Dr. Seligman in 1923, his first design being logically very basic and with logical pressure and temperature limitations. However, they were the beginning of modern plate heat exchangers. The first plate heat exchanger is on display at the Science Museum in the UK.
Currently, plate heat exchangers are used in many industrial and domestic applications, given the enormous variety of advantages they have: low relative cost, little space, high heat transfer, flexibility, number of manufacturers, etc.
It was without a doubt one of the inventions that have changed the industrial landscape over the years: plate heat exchangers.
 
 
What are the main parts of plate heat exchangers?
 
Let us illustrate with a diagram the main parts of plate heat exchangers with 1 single stage or section, on the understanding that there are, as we will see, plate heat exchangers with several stages and sections. Also indicate that, in this case, the diagram corresponds to a plate heat exchanger with a sealing gasket. In the classification of plate heat exchangers, you can see that there are other types.
 
Plate heat exchanger

 

 

The guide bars:

Distinguishing, you can see in plate heat exchangers an upper and a lower guide bar. The upper one guides and supports the set of plates, the lower one being more of a guiding function than a support for the set of plates of the plate heat exchangers.
 
Fixed and mobile platen:
 
In plate heat exchangers they allow the sustenance of the entire assembly. Designed and built in different versions to withstand up to 35 bar pressure, together with the plate pack.
 
The tightening bolts or screws of plate heat exchangers:
 
turnscrew Together with the rest of the components, its function is to allow the set of plates to be compacted. The number of tensioning screws and their diameter, together with the thickness of the plates, will safely determine the working pressure of the frame, without forgetting that the plates, as we will see later, have a lot to say in this regard. Except in very simple or small plate heat exchangers, they consist of a bearing and nut assembly on the fixed platen and a nut on the mobile platen side, thus facilitating their assembly and disassembly by reducing friction. VERY IMPORTANT: If you have to open your plate heat exchangers, make sure that the tensioning screws are perfectly clean and greased (solid industrial grease). Ask us about the ideal grease for your brand or ask us for the instruction manual for your plate heat exchangers.
 
The set of plates
 
heat exchange plates The plate heat exchanger is where its quality literally resides. The plate assembly of the plate heat exchanger performs on heat exchange and corrugated type, thickness, material, design, etc. will determine the efficiency, durability, capacity and goodness of the service. We will dedicate the next articles on plate heat exchangers to all aspects related to them. Not forgetting of course the gaskets or gaskets for your plate heat exchanger. A critical part that will deserve a thorough analysis. The gaskets or gaskets of your plate heat exchanger are the weakest part of your plate heat exchanger and therefore should be thoroughly analyzed in the following articles to help you in your decision making. Doubts so far? Contact us and we will gladly expand the information related to your plate heat exchanger.
 
 

Plate heat exchangers (II)

In this second part we will deal with a topic of vital importance in plate heat exchangers. As we mentioned before, the construction of the plates itself is of vital importance, since the performance and head loss of your exchanger depend on them. Depending on the manufacturer, there are different types of plate; In general terms, they are designed for the type of application, favoring heat transfer or minimizing load losses, that are suitable for CIP cleaning, that allow the passage of solid particles or fibers, etc.placas icp
The manufacture of the same is a determining factor since depending on the thickness, size, type of corrugated, different pressing pressures and steps are used, that is, the number of pressings until the finished plate is obtained. IMPORTANT: The indicated thickness of the plates of your exchanger is that of the raw material, that is, the stainless steel before being pressed, therefore, its plates really have a lower thickness since part of it is lost during pressing.
The presses used for pressing plates are hydraulic, and can reach pressures of up to 40-50,000 tons.
The molds or tools are made of hardened material and have a limited life time, so over time they must be rectified or replaced.
The plates have points of contact between them, that is, they support each other at different points on their surface. Depending on the corrugation of the same, there will be more or fewer contact points, and an indicative die may be 300 to 400 contact points for each square meter of plate. This figure varies depending on the factors mentioned.

PHE press

The thickness of the plates determines their mechanical strength substantially. E.g. A 0.7 mm thick plate has a mechanical resistance 80% higher than a 0.5 mm plate. This is important when deciding which plate is suitable for your application; working pressures, water hammer, pulsations, etc. The thickness does not influence the chemical attack on the plates. It is also important to know that the heat transfer has very little influence due to the thickness of the plate. That is, a thinner plate does not have much greater heat transfer than another of the same model and greater thickness. What is certain is that its mechanical resistance is significantly lower.
Keep these parameters in mind when choosing your exchanger since the savings in replacement plates is considerable.
The corrugated ones:
Each manufacturer has different types of corrugated. Due to the type used, thermal transfer is improved to the detriment of pressure drop or vice versa, that is, less transfer in favor of minimizing pressure drop. This depends on the engineer who performs the calculation of your exchanger, since each exchanger, except for standard applications, is calculated according to the application.
If you have questions or queries about your exchanger plates, contact us and we will gladly assist you.

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