Shell-and-Tube Heat Exchanger: Select the Right One

When manipulating a shell-and-tube exchanger India, one of the first hurdle is to take decision about which fluid should go on the shell side and which on the tube side. So, let's look at some rules-of-thumb for several key factors, realizing such uneven guidelines won't cover all cases.

High pressure. Put a high-pressure fluid on the tube side. This will minimize exchanger cost. The smaller tube diameter has a higher pressure rating for the same metal thickness compared to the larger diameter shell.

Fouling. A fluid with a propensity to foul normally should go on the tube side. Cleaning straight tubes normally is easier than cleaning the shell — even if a relatively large tube pitch or a square tube pattern is used to make the shell side easier to clean. However, the exchanger configuration considerably influences the choice. Using a fixed tubesheet mandates putting a clean fluid on the shell side; unless expected fouling is easily detached by chemical cleaning, the fixed tubesheet makes the shell side impossible to clean. In contrast, U-tubes are more difficult than straight tubes to clean. So, sending a in general fouling service through the shell side may be better if fouling reduction steps, such as installation of helical baffles, are suitable.

Expensive materials. Put a corrosive fluid on the tube side. That way, only the tubes, tubesheets, heads and channels will need exclusive corrosion-resistant alloys. In contrast, a corrosive fluid on the shell side requires the entire exchanger to use the materials.

Low pressure drop. The fluid should go on the shell side. An appropriate combination of baffle cut, spacing and type (segmental, double segmental, rod-baffle, etc.) can accommodate nearly any pressure-drop requirement. Services under vacuum almost always are on the shell side because of pressure drop sensitivity.
Vapor services. Because a vapor normally has a higher volume and lower heat-transfer coefficient than a liquid, assign it to the shell side. This reduces pressure drop for a given volume and typically provides a higher heat-transfer coefficient.

Condensing services. A condensing fluid most frequently goes on the shell side — but the choice demands careful evaluation. If the shell-side velocity is low enough, the vapor and liquid can separate inside the exchanger. The liquid dropping out makes the vapor leaner, reducing the temperature required to get more liquid to condense from the remaining vapor. For relatively pure mixtures, this effect is unimportant.

For wide-condensing-range mixtures, make certain the overall flow pattern inside the exchanger keeps the liquid and vapor mixed. This may necessitate having the shell-side fluid leave from the bottom (forcing the liquid and vapor to mix) or determine the choice of baffling inside the exchanger (horizontal versus vertical or 45° baffle cut).
Viscous services. Here, the tradeoffs are difficult. A viscous fluid on the tube side tends to have high pressure drop and low heat transfer. That favors shell-side allocation. However, high pressure drop on the shell side can prompt significant flow bypassing around baffles, reducing heat transfer. A shell side with a high pressure drop also may suffer from vibration damage; shell-side modifications (assuming the user is aware of the need for them) can reduce such damage.

Solidifying services. Usually avoid a shell and tube exchanger for any service with a high risk of solidification or freezing. However, if you must use such an exchanger, I suggest putting the fluid with a risk of solidification in the tubes. If the fluid solidifies, you usually can pull out the tube bundle and replace it. In contrast, if the solid is on the shell side, it's often impossible to remove the tube bundle. The entire exchanger may require replacement.

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Lets Know More About Plate Heat Exchangers India

A plate heat exchangers India, is considered to be a kind of exchanger that uses metal plates to transport heat between two fluids. This is a major benefit over a conventional exchanger in which the fluids are uncovered to a much larger surface area because the fluids spread out over the plates. This facilitates the transfer of heat, and greatly increases the speed of the temperature change. Plate heat exchangers India are now common and very little brazed versions are used in the hot-water sections of millions of combination boilers. The lofty heat transport efficiency for such a small physical size has increased the domestic hot water (DHW) flow rate of combination boilers. The small plate exchanger has made a great impact in domestic heating and hot-water. Bigger commercial versions use gaskets between the plates, whereas minor versions tend to be brazed.
The perception behind a exchanger is the utilization of pipes or other containment vessels to heat or cool one fluid by transport of heat between it and another fluid. In the majority of cases, the exchanger consists of a coiled pipe containing one fluid that passes through a division containing another fluid. The walls of the pipe are usually made of metal, or some other substance with a high thermal conductivity, to facilitate the interchange, whereas the outer casing of the larger chamber is made of a plastic or layered with thermal insulation, to discourage heat from evasion from the exchanger.

The plate heat exchanger (PHE) was invented and introduced by Dr Richard Seligman in 1923 and revolutionized methods of indirect heating and cooling of fluids. Dr Richard Seligman founded APV in 1910 as the Aluminium Plant & Vessel Company Limited, a specialist fabricating firm supplying welded vessels to the brewery and vegetable oil trades.
Welded, semi-welded and brazed heat exchangers are used for heat exchange between high-pressure fluids or where a more solid product is required. In place of a pipe passing through a division, there are instead two alternating divisions, usually bony in depth, separated at their largest surface by a corrugated metal plate. The plates used in a plate and frame heat exchanger are obtained by one piece pressing of metal plates. Stainless steel is a commonly used metal for the plates because of its ability to withstand high temperatures, its strength, and its corrosion resistance.

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