For SCR denitration, is the flue gas volume measured or calculated in the DCS?
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For SCR denitration, is the flue gas volume measured or calculated in the DCS? How can calculations be performed to minimize errors?
It is not impossible to measure the flue gas, but the readings will not be accurate; after all, the pressure here is low, making it difficult to obtain precise measurements. We use simulated calculations to determine the amount of flue gas.
It is measured, using a Pitot tube. A Pitot tube is also known as a “Pitot tube,” or a “velocity tube,” and is commonly referred to as an “air speed tube.” An instrument that calculates flow velocity by measuring the difference between the total pressure and the static pressure of a fluid. Planes also use it to measure flight speed. It has a simple structure, is easy to use and manufacture, and is inexpensive. With careful fabrication, strict calibration, and appropriate modifications, it can achieve high speed measurement accuracy within a certain range of speeds.
Have you calculated how large the deviation is between the pitot tube measurements and the calculations?
At a height of 30 meters above the ground on the power plant’s chimney, the internal cross-sectional area was accurately determined; the velocity was calculated using a Pitot tube, and the result was consistent with the estimates. The inaccuracy of the Pitot tube is due to the measurement position not being appropriate; for example, the length of the straight sections before and after it is insufficient ； Vortices are generated internally ； Calculate the internal cross-sectional area using the design drawings rather than conducting actual measurements ； Temperature and pressure are not measured simultaneously (for conversion and verification) ； The lack of actual measured water vapor content and the use of an empirical value (for example, it is empirically assumed that the water vapor content in catalyzed flue gas is 13%, while the actual measurement is 17%) leads to the misconception that the estimated value is accurate while the measured value is not; in fact, the measured value is more accurate. If necessary, adding a rectifying grid upstream of the measurement point can improve the measurement accuracy. An airplane uses a Pitot tube to measure its flight speed, and this method of measurement is highly accurate.
Will the fine catalyst powder in the flue gas affect the pitot tube?
No. But the measurement time is long, and any blockage has an impact.
Understood, I’ll ask the design institute what they think.