How should the spacing of NTIW-type baffle plates be determined?
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This post was last edited by 30dman on 2024-9-12 at 12:52. I’m encountering a problem while calculating vibrations and would like to ask for everyone’s advice. In fixed-tube-sheet heat exchangers, for process reasons, the fluid in the shell side enters and exits from the top. Due to the excessive pressure drop caused by the single-arch baffle, NTIW baffles were chosen; one support plate is added between each span, with the baffles and support plates arranged at equal intervals. Question 1: Flow direction of the shell-side fluid? Question 2: When calculating vibrations, what should be the spacing between baffle plates? Is it the original baffle spacing, or half of the original value? Flow direction of single-arch baffle
It should be half of the original value; the support plate also serves to support the heat exchange tubes
Question 1: The flow direction of the fluid in the shell side is usually perpendicular to that of the baffle plates, causing the fluid to flow through the gaps between the baffle plates one by one. Question 2: When calculating the vibrations, the addition of support plates reduces the effective length of each baffle section by half; therefore, the baffle spacing should be calculated as half of the original value. This allows for a more accurate representation of the resistance and pressure drop experienced by the fluid as it passes through the baffle, thereby enabling more precise prediction and control of vibrations. .
Answer 1: The flow direction of the shell-side fluid is the same as that in the second diagram. Answer 2: Calculated based on the original baffle spacing, the maximum unsupported span is still determined as per the second diagram. Although there are intermediate support plates for the heat exchange tubes in the middle, there are none at the edges; it is therefore necessary to ensure that the heat exchange tubes over these long spans are also analyzed using vibration calculations.
The baffle is NTIW, meaning no pipes are installed in the notched area
The baffle is NTIW, meaning no pipes are installed in the notched area
Returning to the essence of the regression problem, and considering the concern that pressure drops may exceed acceptable levels, why not use the spiral baffle technique, which can **reduce the requirements regarding pressure drops?
The design approaches of the other experts who came to learn*
Making spiral plates is a bit more troublesome:D
In these days after the holiday, regarding this issue, I think Question 1: What is the flow direction of the fluid in the shell side? With the NTIW-type baffle in use, the flow direction becomes more complex compared to that with a single arch-shaped baffle, but the overall flow pattern remains similar to that of the single arch-shaped baffle. Question 2: What should be the spacing between the baffles when calculating vibrations? Is it the original baffle spacing, or half of the original value? When performing vibration calculations, the cross-flow velocity is calculated based on the spacing between the baffles. The frequencies and amplitudes are determined using the spacing set for the NTIW baffles, which is half of the original baffle spacing. These are merely my personal opinions; I welcome further discussions from everyone