Advantages and disadvantages of using flow meters, high-level tanks + weighing modules, and metering pumps for feed measurement in fine chemical production
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Dear engineers: There are many methods for liquid metering in fine chemical production. It is measured by a flow meter, and a sight tank along with a weighing module are used; nowadays, metering pumps are being utilized more and more often. Could we discuss the advantages and disadvantages of each of these methods, as well as what considerations should be taken into account when using them? For example, when adding liquid materials, a sump is used along with a weighing module for measurement; 400 liters are added per hour. If there are multiple reaction vessels, multiple sumps are required, and the raw materials also need to be pumped from larger storage tanks. However, by using a metering pump with DCS for remote control of the feed volume, and by pumping directly from the large storage tank, a significant amount of time can be saved along with reduced equipment costs.
Accurate measurement by a flowmeter requires continuous operation; intermittent operation results in significant errors. Using a sump with weighing for measurement is generally quite accurate, but it is time-consuming and requires a lot of work. Metering by metering pumps is feasible, but it seems to be mostly used in continuous production areas.
Yes, the reason I proposed this discussion is that I have recently wanted to change the dosing method for the level gauge in the company from a drip system to a metering pump. Let’s see if anyone has similar operating conditions, and what issues need to be taken into account when using metering pumps.
There are load cells and secondary weighing devices, as well as gas cylinders and mass flow meters
Generally, the following factors are considered: continuous dropwise addition or batch processing, requirements for measurement accuracy, properties and toxicity of the materials, flow rate, production management, site layout, and measurement reliability
Use a high-level tank as a fake level gauge; install a mass flow meter and a control valve for the discharge process, add a pressure sensor at the pump outlet for the discharge pump, and use weighing as an auxiliary reference. By implementing interlocked automatic control, accuracy can be improved.
A mass flow meter + pump + control valve enable high-precision control.
I recommend using a skid-mounted integrated metering solution, which consists of a gear pump, a mass flow meter, and a control system – offering high precision and stability in control. The advantages and disadvantages of metering pumps are quite obvious; if your requirements for measurement accuracy are not high, a metering pump will suffice.