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I would like to ask the experts here a few questions regarding the PID diagram below: 1. What is the purpose of installing a flow-limiting orifice plate on this waste discharge pipe? 2. Why is a heating pipe needed for this waste discharge pipeline? 3 Why is it necessary to define different pressure grades for the pipes at the end of the sewage pipeline? Why not use the same pressure throughout?
The screenshot you took is really too blurry
Then, there is also a flow-limiting orifice plate at the very front
The function of a flow control orifice plate is generally to ensure that the pipeline is filled with liquid. As for insulation, is this pipeline above ground level? If it contains water, heating is necessary to prevent freezing. There is a high possibility that this branch pipe is connected to the main sewage pipeline
Will this flow-limiting orifice plate serve to limit flow and stabilize pressure? . How should this filling of the pipe with the liquid phase be understood? May I ask you another question? This pipeline carries LNG through a filter, with the output coming from the bottom of the filter. With heat tracing, it seems to be the situation you mentioned
First, let me show you the contents of our design documents: a validated orifice plate that ensures the pipe remains filled with liquid when the product flow reaches the designed level, thereby preventing pipeline vibration caused by two-phase flow. Furthermore: The explanation of flow control orifice plates on Baidu: 1. In situations where the pressure of the process material needs to be reduced. 2. When a large pressure drop is required upstream and downstream of a valve in a pipeline, in order to reduce fluid erosion on the valve, an orifice plate can be connected in series upstream of the valve, provided that throttling through the orifice plate does not result in the formation of a gas phase. 3. Places where the fluid needs to flow in small quantities and continuously, such as the flushing pipes of pumps, the bypass pipes of hot standby pumps (low-flow protection pipes), analysis sampling pipes, etc. 4. Areas where pressure reduction is needed to reduce noise or wear, such as vent systems. It seems to be similar to points 3 and 4 in Baidu’s explanation, right?
Let me share my understanding; I’m not very familiar with LNG, so it might not be correct. The waste pipe seems to run from the branch pipes to the main pipe; the equipment upstream of the branch pipes should have higher pressure. The waste pipe probably leads to discharge tanks, which are usually at atmospheric pressure. Installing a flow control orifice plate in this area can help reduce the pressure difference between the main pipe and the branch pipes. Additionally, providing heating for the waste pipe is likely a standard practice