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The valve settings of the third phase - the valve settings of the tower and heat exchanger tower are mainly in places where they should be set as little as possible. One is the gas phase outlet, lateral outlet and steam return pipe at the top of the tower, and the other is the reboiler at the bottom of the tower. But there are a few special ones who read page 487 in 20570.18. In addition, the valves of the tower should be arranged as close to the tower as possible. On the one hand, the force is taken by the tower to reduce external support, and on the other hand, it can overcome liquid accumulation. The valve setting of the heat exchanger is also designed to allow no addition, but it must be added if the process requires it, such as switching the heat exchanger, the utility pipeline of the heat exchange equipment, if the materials on both sides are installed on one side, the temperature needs to be adjusted artificially, etc. For steam heating equipment and water cooling equipment, the non-condensable gas exhaust valve and the shell side purge valve are the key points. The position is very important and the dead zone must be minimized. Let’s talk about multi-tube heat exchangers. Generally, tear holes are opened on the partitions to drain liquid. I didn’t know this before, so I was discouraged from multi-tube heat exchangers for a long time. It wasn’t until I had a project to make an 8-tube heat exchanger. After carefully studying the equipment drawings, I found out that tear holes are used to drain liquid (I believe many people are still in the dark, wake up~~~~ The wisdom of working people is infinite). The specifications for the inlet and outlet pipelines of air coolers say that shut-off valves are generally not added, but I personally feel that this is rarely the case, because many items of air coolers must be reserved, and as long as you prepare them, you have to add valves to switch. Air cooling is cleaned a lot in chemical plants, so most valves must be added. However, it is very important to arrange the air cooler pipelines symmetrically. For the valve setting of the container, if there are multiple inlets or outlets that need to be replaced, a valve should be installed at the pipe mouth. Install double valves where double valves should be installed, as mentioned above. The position of the discharge pipe of the container should be higher than the discharge pipe. Large cone-top and vault-top normal pressure storage tanks should be equipped with breathing valves when storing volatile materials. If possible, use a low-temperature condensation system to replace the breathing valve (there is really no such thing...). Except for the air compressor that sucks air from the atmosphere and does not have an inlet valve, all other compressors must be installed. If there is maintenance, an 8-shaped blind plate must be added. The reciprocating compressor is equipped with a bypass pipe and a connecting valve. The bypass pipe of the multi-stage reciprocating compressor can be connected step by step and connected with the inlet and outlet. The air compressor can add a branch pipe and valve directly upstream of the outlet valve, using the atmosphere as the connecting pipe. For centrifugal compressors, the size of the bypass should be greater than the load at the compressor surge point. I won’t go into details about auxiliary systems. For auxiliary systems, we now buy compressors that are directly matched or provide auxiliary system drawings. Compressor manufacturers know better than us how to configure these things (professional people do professional things, saving money and trouble). Pumps and positive displacement pumps can simply use inlet and outlet valves. However, if the positive displacement pump itself does not integrate a check valve, a check valve must be installed at the inlet. The inlet and outlet diversion filtration refers to the vane pump. ； The specifications for vane pumps mention many working conditions. I think most of the ones I encountered have to be set up in this order, inlet cutoff, diversion, filtration, reducer, pump, outlet reducer, pressure gauge, check valve, diversion, and shut-off valve. Here we talk about the drain valve. For centrifugal pumps, if there is one on the pump body, you don’t need to add it. If there is no large centrifugal pump, add it before the check valve. For small centrifugal pumps, add it after the check valve. (I think this is related to the pressure drop of the check valve. If a large pump is equipped with a large pipeline, the pressure difference of the check valve is also large, so the gas cannot be discharged, so it must be added in front of the check valve. ) The pump's connecting pipe and low-flow protection pipe, volumetric pump and vortex pump are equipped with inlet and outlet connecting pipes and connecting valves (to avoid holding back pressure during startup). When the centrifugal pump is operated under conditions that may be less than 20% of the rated flow rate, make a bypass and install a flow-restricting orifice plate. It is possible to set up a bypass when the flow rate is below 40% of the rated flow for a long time. When the pump operates at low flow rate for a long time or the flash evaporation phenomenon is obvious when passing through the orifice plate, the bypass should be directly returned to the upstream equipment, and the orifice plate should be as close as possible to the equipment. In addition, bypass valves are provided for heating pump, anti-condensation and high-pressure bypass. See the picture for details. That’s all for this issue, due to layout reasons. The next issue will talk about the types and selection of valves in detail, and continue to tell the story. There is a lot of content in this issue so I won’t give examples. If you have questions during recovery, I will give examples and tell stories when replying to your questions. In this age where stories are rampant, why worry about not having stories to listen to?