Instrument, forced circulation evaporation chamber
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Two pressure gauges are used to measure the pressures at the top and bottom of the forced-circulation evaporation chamber (as there is a certain height difference); a level gauge is connected to these two pressure instruments, and it is interlocked with the feed valve. What is the principle behind displaying the liquid level?
One end of the differential pressure transmitter is connected to the liquid phase, and the other end is connected to the gas phase. Assume that the space above the container is filled with dry gas at a pressure of p. Then, p1 = p + ρ gH and p2 = p. It follows that Δp = p1 − p2 = ρ gH, where H is the height of the liquid level; ρ is the density of the medium; g is the acceleration due to gravity; and p1 and p2 are the pressures in the positive and negative chambers of the differential pressure transmitter, respectively. When the density of the medium being measured is known, the differential pressure measured by the differential pressure transmitter is proportional to the liquid level height; this allows the measurement of the liquid level height to be converted into a measurement of differential pressure.
Δp = p1 − p2 = ρgH; generally, it is a double-flange differential pressure level gauge, and the pressure gauge is used to measure the pressure in the separator, which has nothing to do with the liquid level