Propylene refrigerant user disconnected!
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This post was last edited by liaifeng on 2018-7-28 07:29. In our olefin separation unit, a low-pressure interlock has been installed on the gas side of the condenser at the top of the high-pressure depropanization tower; if the pressure drops below 0.46 MPa, the shut-off valve will activate, cutting off the Propylene gas flow to the condenser and preventing it from reaching the third stage of the Propylene refrigeration compressor What is the reason for setting it~!
It is to prevent, when the propylene refrigerant vapor enters the second-stage suction tank, the pressure in the condenser from dropping too low suddenly, which could cause surge in the compressor’s fourth stage, or to prevent liquid phase from entering.
If my analysis is correct, the condensate temperature in your high-pressure depropanization tower must be a bit higher. But your pipelines/equipment might be made of carbon steel, or for other reasons ； Below 0.46 MPa(G), the temperature of hydrocarbon condensates falls below 0°C. Specific details can be discussed; QQ: 737268613
We carry out high-pressure depropanization; the top condenser uses an 7°C propylene coolant, and there is a two-stage suction tank (-24°C) in the high-pressure tower! It is used when the ethylene specific gravity in the reaction gas compressor is high! However, when the pressure at the outlet of the high-pressure depropanization condenser is low, the condenser is taken out of service, and the valve for suction in the reverse second stage is also closed
I’m not quite sure; I just want to ask, is the pressure in the propylene three-stage suction tank 0.6 MPa? Can 0.46 of propylene enter a tank with a capacity of 0.6?
This interlock is generally used in Condition 3, that is, it is activated when the E/P value is low. In my opinion, under Condition 3, if the pressure of the propylene refrigerant drops to 0.45 MPa, the temperature provided by this refrigerant will be around 0°C. Under such conditions, all of the propylene in the vapor phase at the top of the tower may condense, resulting in no propylene in the feed to the fourth stage; this can lead to a disruption in the subsequent system, overload of the distillation system, or liquid entrainment in the compressor. The above are my personal opinions; I welcome insights from experts.
What’s most important to consider is the material used for the pipelines. If you take a closer look at the PID diagram, the gas pipelines on the propylene side are made of A2A material, while the main pipeline leading to the suction tank is made of A1D material. A1D is ordinary carbon steel, whereas A2A is low-temperature carbon steel. The low-pressure interlock is installed to prevent the low temperatures resulting from low pressure from causing the material to become unsuitable for use. :)Personal opinion.
The main purpose of this cascaded design is to protect the pipelines; the user pipelines for the third stage of your propylene plant should be made of carbon steel, rather than low-temperature steel. When E/P is high, in order to meet the refrigerant demand of the high-pressure tower, the valve of the second stage of the propylene unit is opened to enable the high-pressure tower condenser to produce refrigerant at a lower temperature. And since this pipeline is not a low-temperature steel pipeline, interlocks are used to impose restrictions
Your answers are all correct, Floors 6, 7, and 8: lol:lol:lol
This chain is primarily used to protect the pipes on the process side as well as the depropanization reflux tank; the material used on the process side is carbon steel. It is not designed to protect the propylene refrigerant side; that side is made of low-temperature carbon steel. Refer to the patent holder’s chain of documents.