Selection issues for flowmeters
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On the pipeline sections of the unit where the boundary zone enters, the flow rate of the solvent injection line is usually low under normal conditions; however, it increases significantly when solvents need to be added or during startup, often reaching more than 10 times the normal flow rate. Yet the minimum flow rate is only 1/10 of the normal value. What type of flow meter would be suitable for cumulative measurement in such cases? Since solvents are generally expensive, high flow rates cannot be ignored. Using a dual-metering system isn’t appropriate either. I’ve been encountering this problem frequently lately. Please help!
I’m not sure what the requirements are regarding accuracy; if accuracy isn’t a major concern, metal floats could be considered, provided they have a high range ratio. Of course, low viscosity is also a factor to consider. Accumulation is only a function of secondary instruments and has nothing to do with field instruments.
If the medium has low viscosity and a relatively uniform consistency, a turbine flowmeter can be used; it offers a wide range of flow measurement capabilities and good accuracy. However, its accuracy decreases over time with prolonged use, although imported turbines tend to be of better quality.
The range ratio of elliptical gear flow meters can reach 20:1, with an accuracy of up to 0.5; however, the flow rate cannot be too low, as this will affect the measurement accuracy. You can consult relevant manufacturers for more information.
I think the scraper flow meter is better, as it provides accurate measurement
Our company has encountered a similar problem as well: in intermittent distillation, the flow rates for the product stream and the reflux stream vary widely, ranging from dozens of liters per hour to several hundred liters per hour. The solvent is non-conductive, so we plan to use metal rotameters with remote transmission and accumulation functions. There will be one meter with a larger range and another with a smaller range, each installed on the reflux and product pipelines respectively; the pipelines will be switched based on the flow rates. This approach helps meet the process requirements while also saving costs.
My measurement ratio has reached 1:100; since it involves some auxiliary devices, dual-line measurement is not used to keep costs down. However, accuracy is required for the measurement values. Metal tube float flowmeters, which are used when the medium’s viscosity is high, do not meet these requirements
I haven’t heard of any instrument that can meet your requirements; maybe I’m not well-informed, but I think that if such an instrument does exist, it certainly won’t be cheap! Moreover, the performance is not necessarily very stable. Therefore, I suggest measuring in segments; you need to change your perspective on costs! :L :L
I have a headache too! This device requires very little funding, yet everything related to it is expensive; moreover, the technology used involves flow rates that are extremely high, which is a real headache! ! ! !
When a solvent is added or during startup, the flow rate is quite high, often more than 10 times the normal flow rate; yet the minimum flow rate is only 1/10 of the normal flow rate. I haven’t heard of any instrument that can meet your requirements! The recommendations are as follows: 1. Use a container as a measuring tank, or employ a weighing method, to handle the addition of solvent or the high flow rates during startup. 2. Additionally, use two flow meters. Are chemical plants afraid they can’t afford a flow meter? 3. Discuss with the process team to reduce the amount of solvent added or the high flow rate at startup! ! !