Selection of concentration monitoring instruments
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Dear friends: We are also in the process of building a four-effect evaporation workshop. In the final stage of this process, the material is forced to circulate for evaporation. On the pipeline used for this material circulation, a device for detecting the concentration of the material is installed, so as to monitor its concentration in real time; control valves are then used to regulate the amount of material discharged. As shown in the attached diagram, the gauge points indicated by the red circles – in previous four-effect evaporation systems, we used sampling valves for sampling, and glass instruments such as refractometers, sugar meters, or Baumé meters for manual measurement. Now, this new workshop wants to install online monitoring instruments. Operating conditions: The temperature here is between 55 and 60 degrees, and the concentration is around 55–60%. We have not used this type of online concentration monitoring instrument. Please give me some advice. I would appreciate everyone’s advice; practical experience would be even better!
Could everyone give some advice? What should I do?
If necessary, a mass flow meter can be used; we have removed it as it isn’t very useful, and it’s easier to monitor the current of the circulation pump. The old workshop was demolished, and the new one wasn’t installed at all. It’s completely useless
There are tuning fork-type density meters; Rosemount makes one that I’ve used before and it works fine. There’s also an online refractometer that can be used for this purpose, but its performance wasn’t good when tested on our products
What is the process medium? Here are several principles used for measuring the concentration of acid, alkali, and salt solutions: 1. Ultrasonic method, from American companies FLEX and SENSOTECH; 2. Electromagnetic conductivity method
The core of a meter is the sensor; only with an appropriate sensor can measurements be taken. Mettler and Honeywell have the capability to carry out such comparisons, but they cannot measure all concentrations; it’s worth consulting them to find out
What you say is absolutely correct. For these less commonly used sensors, it is necessary to communicate more and seek advice frequently. Next month, we will first hold a meeting to discuss things with the process design team.
It mainly depends on the concentration of the substance you want to measure; different measurement methods have their respective applicable ranges, and providing more detailed information helps in making a decision.