Material addition issue

Material metering pumps are widely used in industrial production processes due to their ability to precisely control flow rates. Regarding the two material metering pumps you mentioned, although they display different pressures and flow rates, it is possible to achieve a stable process of convergence and mixing through certain methods. Here are several methods and considerations that can be used to implement this process: 1. Pressure balancing device: A pressure balancing device, such as a pressure reducing valve or a backpressure valve, can be used to increase the pressure of the low-pressure fluid so that it can merge with the high-pressure fluid. In this way, the device can adjust the pressure of the low-pressure material to bring it close to that of the high-pressure material, thereby enabling them to merge. 2. Control valve: By installing a control valve at the outlet of the high-head metering pump, it is possible to reduce the total flow rate or pressure flowing into the mixer, thereby facilitating the entry of material with a low head. 3. Static mixer design: The internal design of the static mixer helps to balance the pressure difference between the two fluids, facilitating uniform mixing without relying on external pressure. The design of the mixer must allow fluids at different pressures to mix within it without causing excessive pressure loss. 4. Process control system: There may be an automatic or semi-automatic process control system that monitors and regulates these pumps and valves to ensure a balance between flow rate and pressure. Such a system can adjust parameters such as pump speed and valve opening in real time, thereby ensuring flow stability. 5. Elastic storage elements: Pressure tanks or elastic pipeline elements may be used in the process to buffer pressure fluctuations, ensuring that the pressure of the fluid remains relatively stable before it enters the mixer. Achieving such process stability usually requires meticulous engineering design and process control. If there is still a significant mismatch in the flow rates of the two pumps, further process adjustments may be required. Of all these possibilities, the most important is to ensure that the materials are fed into the mixer at a constant flow rate and under appropriate pressure, and then to ensure uniform mixing in the high-shear screw environment. In practical operation, more technical details and specific adjustments may be involved. If problems arise, it may be necessary to analyze and optimize various aspects such as process design, equipment selection, and control strategies. .

It can be calculated using Bernoulli’s equation; basically, it’s sufficient that the pressure at the screw area is low

As long as the inlet pressure of the 400rpm screw pump is low, 0.5 bar or 0.7 bar should suffice; the pressure upstream should be the same, and the pressure at the junction point is also the same

I’m quite familiar with Bernoulli’s equation, but I don’t know how to calculate it. Could you please help?

That’s how it is, but I just can’t understand it

This post was last edited by A pot of green tea_fRoaP on 2023-12-9 at 15:58. Whether fluid can be pumped from a low-pressure pipeline into a high-pressure one depends not only on pressure but also on kinetic energy. It is sufficient that the static pressure energy + kinetic pressure energy of the fluid in the pipe with lower pressure is greater than the static pressure energy + kinetic pressure energy of the fluid in the pipe with higher pressure. Another scenario is that the pressure at the connection point of the two pipes is low, as pressure is released at the screw equipment

Thank you. Regarding your answer, I have two points to make: 1. The flow rate of high-pressure liquids is ten times that of low-pressure ones; with the same pipe diameter, the flow velocity is also ten times higher. Therefore, the mechanical energy of high-pressure liquids is much greater than that of low-pressure liquids. 2. Let’s imagine a simple scenario. A pressurized balloon with two holes, one large hole (in the direction of pressure release via the screw). With a small opening (in the direction of the low-pressure pipeline), the air in the balloon should flow in both directions; it can’t flow back

The pressures upstream are different; after mixing, the pressures become equal. Before mixing, the pressure drops are not identical. In my opinion, the pressure is the same at the point of mixing. If the ends of the injection tube can be explained clearly, then this issue becomes simple.