Static & Dynamic Pressure

We measure static and dynamic pressure in the preheater downcomer duct or elsewhere. Can I know for what they stand for? Please explain for the sake of clear understanding.

Thanks.

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Re: Static & Dynamic Pressure

Static pressure can be measured at any point in a fluid (a gas or a liquid, in your case the preheater exit gas). You can measure static pressure in the atmosphere at your cement factory. In that case it is the “barometric” pressure and is dependent on the altitude of your cement factory above sea level. The higher your cement factory then the lower the weight of the atmosphere above it and the lower is the barometric or static pressure. The same applies to preheater exit gas

The dynamic pressure is the pressure created by the movement of a fluid. If you stand on your cement factory on a day with no wind you are only subjected to the static pressure of the atmosphere. However, if you stand on a windy day you will feel the wind pushing against you. That is the dynamic pressure created by the movement of the atmosphere. In the preheater exit duct the gases are being pulled through the induced draft fan so they exert dynamic pressure.

The dynamic pressure is a function of the density of the gas and the square of its velocity. The measurement you take is the static pressure and the total pressure. Total pressure – static pressure = dynamic pressure. From the dynamic pressure you can then calculate the gas velocity. From the velocity combined with the dimensions of the preheater exit duct you can calculate the preheater exit gas volume. 

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