The flow rate in the tail branch is insufficient; how to solve this?
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The main pipe is DN200, with 13 branch pipes attached to it; the first 12 of these are DN80 pipes, while the last branch pipe is DN100. There is now a device connected to this last DN100 pipe, which results in severe insufficient flow for that device. The solution I’m thinking of now is to install DN40 flow control orifice plates on the first twelve pipes in order to regulate the flow rate; this way, the flow rate allocated to the last branch pipe might be sufficient
I’m not sure how your piping system is arranged; it would be better to first calculate the pressure drop before taking any corrective actions. This approach is more scientific and cost-effective
Agree with the suggestion from the 2nd floor. Pipeline hydraulical calculations serve as the basis for implementing the renovation plan. For branch pipes, the distribution of pipe resistance should be reasonably allocated in accordance with the process requirements. Increasing the resistance of the upstream branch pipe is one possible solution, but can it meet the flow requirements of the upstream branch pipe? Additionally, through calculation, increasing the diameter of the tail pipe (reducing the Reynolds number and thus the pipe resistance) can also be considered as a solution. But regardless of the approach adopted, it is necessary to systematically calculate the pipeline resistance.
First, it is necessary to confirm that the total volume is sufficient (assuming the main pipeline remains unchanged). If the total volume is not enough, then even by modifying the pump, the water flow will not be sufficient. If it is determined that the problem lies in uneven distribution of flow, an approach involving water intake from the middle and extraction from both sides could be considered, as this would result in a more even distribution of water compared to before. If the size of the throttling orifice in the process can be determined, it can be adjusted accordingly. However, it is recommended to carry out calculations first; otherwise, the flow rate in each branch may still not meet the desired levels even after the modifications.
If pressure drop is not taken into account and only the cross-sectional area is considered, it seems that the main pipe used alongside the branch pipes is a bit too small; this can be adjusted by using valves based on the actual production needs, to determine whether the actual flow rate is sufficient. Otherwise, there is no point in discussing it
I think the flow rate and velocity in the main pipe do not match those in the branch pipes; the total cross-sectional area of the 12 80-mm diameter branch pipes is almost twice that of the main pipe, so how can there be any flow in the 100-mm diameter pipes? It is estimated that your main pipe flow rate is not very high either. Flow limiting should be one approach, but the flow rate needs to be calculated.
There is no room for \"maybe\" in this matter; fluid resistance must be calculated based on factors such as the medium, flow rate, pressure, temperature, and pipe conditions in order to arrive at a definitive answer. If the requirement for adjustment precision is not high and conditions permit, I believe it would be better to install stop valves on each branch pipe, allowing for flexible adjustments according to the situation during use.
This also depends on whether the flow rate of all those pipelines ahead is greater than the designed flow rate; in other words, there should be a margin to reduce the flow rate and thereby lower the pressure loss in the main pipeline. Otherwise, the pressure at the last pipeline will still not be sufficient. And there’s no need to install orifice plates; it can be done by adjusting the valve.
So, I would like to ask everyone, how is the flow area between the main pipe and the branch pipes calculated? ? ?