How to deal with inaccurate liquid level in the vacuum tank of a steam turbine condenser

Master, we use a two-out-of-three voting method to measure the liquid level, with three differential pressure transmitters used for this purpose. Previously, all three transmitters showed consistent readings; but in the last two days, only one of them has started to show slightly different values. We’re not sure how to adjust it so that its readings return to normal

I’ve used floats and tuning forks. I’ve never used differential pressure, considering negative pressure conditions. Is it an ABB capillary?

The level gauges used for measuring the liquid level in the turbine condensers at our site are electric float type gauges; differential pressure sensors are not suitable for use in vacuum environments. They may work fine at first, but over time their accuracy decreases and they tend to break down easily.

I’m not sure if electric contact level gauges are a viable option, but in our thermal power generation operations, we use differential pressure transmitters for measuring the level in condensers, and we haven’t encountered any problems with that. Are balance tanks being used?

This post was last edited by lotos1987 on 2015-6-24 22:25. As mentioned above, it’s rare to hear of inaccuracies in the measurement of condenser liquid levels in the power industry. http://www.21ic.com/app/test/201205/124025.htm, a paper for reference.

Our company has 3 turbines used for power generation. The level gauges used in the condensers are flange-type differential pressure transmitters; they functioned well for over a year at first, after which electric remote-transmission magnetic float level gauges were installed, and those have been in use for nearly 10 years now, showing great stability； There are 2 additional turbines used to drive compressors. An electric float level gauge was originally used, but it experienced significant fluctuations during testing; it was replaced with an electric remote-transmission magnetic float level gauge, which has been in use for nearly 8 years without any problems. Upon analysis, the turbine used to drive the compressor experiences frequent fluctuations in the vacuum level of the condenser due to large variations in the compressor’s operating conditions during production. In such conditions, the diaphragm box of a flanged differential pressure transmitter – which is designed to withstand only positive pressures and not negative ones – suffers from a significant reduction in sensitivity and accuracy, leading to fluctuations and even damage. The generator, driven under stable operating conditions with minimal fluctuations in the liquid level, experiences an extended service life.

Sir, our factory’s double-effect concentrator operates at a negative pressure of 0.08, and a magnetic float flap level gauge is used for level monitoring. However, the level varies significantly whether vacuum is applied or not; we’re not sure why! Please advise, expert