[0018] The present invention will be described in detail below with reference to the drawings and specific embodiments.
[0019] Such as figure 1 As shown, the p-xylene storage system based on inert gas protection in the embodiment of the present invention includes: a pressure vessel for storing inert gas 1, a p-xylene storage tank for storing liquid p-xylene, a buffer tank 3, and a condenser 4 In this embodiment, the inert gas stored in the pressure vessel 1 is argon, and the pressure vessel 1 is connected to the paraxylene storage tank 2 and the buffer tank 3 through the gas pipeline, and the pressure vessel 1 is connected to the paraxylene storage tank 2 Air compressors 6 are installed on the gas pipelines connected to the buffer tank 3, which can deliver the inert gas-argon in the pressure vessel 1 to the xylene storage tank 2 and the buffer tank 3, respectively. The para-xylene storage tank 2 is connected to the upper part of the condenser 4 through a centrifugal pump 5 through a gas pipeline. When in use, the mixed gas above the liquid level in the para-xylene storage tank 2 is pumped out into the condenser for processing. For condensation, the lower part of the condenser 4 is connected to the buffer tank 3, and the liquid obtained after the condenser 4 and the inert gas that has not been condensed enter the buffer tank. The buffer tank 3 is also connected to the para-xylene storage tank 2 through the gas pipeline and the liquid pipeline, respectively. The gas pipeline connecting the buffer tank 3 and the para-xylene storage tank 2 is provided with an air compressor, which exits through the condenser. The inert gas from the pressure vessel can be added to the upper part of the paraxylene storage tank through an air compressor after being mixed with the inert gas from the pressure vessel in the buffer tank.
[0020] In this embodiment, the paraxylene storage system based on inert gas protection further includes an inert gas detector placed in the environment outside the paraxylene storage tank 2 to detect whether there is a leak of inert gas in the environment.
[0021] The buffer tank 3 is also provided with a slag discharge port, and the slag discharge port is connected to a slag storage tank through a pipeline. The p-xylene storage tank 2 is used to store liquid p-xylene. Since the liquid p-xylene stored in the p-xylene storage tank 2 is likely to contain a small amount of impurities such as methanol, after the p-xylene storage tank is used for long-term storage of p-xylene, There will be a large amount of gaseous p-xylene and a small amount of methanol gas in the upper space in the p-xylene storage tank, that is, above the liquid level. After the mixed gas is condensed by the condenser, there will be a very small amount of liquid residue containing methanol and other impurities. Into the buffer tank, by setting the slag discharge port in the buffer tank 3, the slag can be discharged through the slag discharge port, and the discharged slag can be collected through the slag storage tank, so that the final stored The purity of p-xylene has been further improved.
[0022] The embodiment of the present invention is based on the inert gas protection paraxylene storage process, which is carried out as follows:
[0023] Step 1. Provide a paraxylene storage system based on inert gas protection;
[0024] The paraxylene storage system based on inert gas protection includes: a pressure vessel for storing inert gas 1, a paraxylene storage tank for storing liquid paraxylene 2, a buffer tank 3, and a condenser 4; in this embodiment The inert gas stored in the pressure vessel 1 is argon, and the absolute pressure in the pressure vessel storing the inert gas is controlled to be 0.1-10 MPa. The pressure vessel 1 is connected to the paraxylene storage tank 2 and the buffer tank 3 through the gas pipeline. The pressure vessel 1 is equipped with an air compressor 6 on the gas pipelines connected to the paraxylene storage tank 2 and the buffer tank 3. The xylene storage tank 2 is connected to the upper part of the condenser 4 through the centrifugal pump 5 through the gas pipeline, and the lower part of the condenser 4 is connected to the buffer tank 3. The buffer tank 3 is also connected to the opposite through the gas pipeline and the liquid pipeline. The xylene storage tank 2 is connected, and an air compressor 6 is provided on the gas pipeline connecting the buffer tank 3 and the para-xylene storage tank 2.
[0025] Step 2: Pass the inert gas in the pressure vessel 1 through the air compressor 6 through the gas pipeline to the upper part of the paraxylene storage tank 2; in the embodiment of the process, the inert gas in the pressure vessel 1 is argon The argon in the pressure vessel 1 is transported to the upper part of the paraxylene storage tank 2 by an air compressor at an absolute pressure of 0.1-3.4Mpa. This pressure cannot reach the argon, so the argon is stored in paraxylene. The inside of the tank always exists in gaseous form on the top of the para-xylene storage tank 2. Therefore, if there is a leak in the para-xylene storage tank, argon will leak first, instead of the para-xylene storage tank in the traditional process Gaseous p-xylene above the liquid level.
[0026] Step 3. Regularly pump out the mixed gas above the liquid level in the paraxylene storage tank 2 through the centrifugal pump 5. The extracted mixed gas enters the condenser 4 through the gas pipe for condensation, and then the liquid paraxylene obtained after condensation And the unliquefied argon enters the buffer tank 3. The liquid p-xylene from the buffer tank 3 flows back to the p-xylene storage tank through the liquid guide pipe. The argon from the condenser is in contact with the pressure The argon in the container is mixed in the buffer tank first, and then replenished to the upper part of the paraxylene storage tank through the air guide pipe using an air compressor.
[0027] In step 3, the mixed gas above the liquid level in the para-xylene storage tank is pumped out through a centrifugal pump every 1-12 hours and enters the condenser for condensation.
[0028] Among them, in the above step 3, the argon gas from the condenser and the argon gas from the pressure vessel are mixed in a buffer tank at a volume ratio of 1:10-10:1, and then supplemented by an air compressor through the air guide line To the upper part of the para-xylene storage tank (above the liquid level in the para-xylene storage tank), the absolute pressure of 0.1-3.4 Mpa is added to the para-xylene storage tank.
[0029] As a preferred mode of the paraxylene storage process based on inert gas protection in the embodiment of the present invention, in step 1, the provided paraxylene storage system based on inert gas protection further includes placing in the environment outside the paraxylene storage tank 2 The inert gas detector is used to detect whether there is a leak of inert gas in the environment. In step 2, after the inert gas in the pressure vessel is passed into the upper part of the p-xylene storage tank through the air compressor through the gas pipe, the xylene storage tank 2 is judged according to the status of the argon gas detected by the inert gas detector Air leakage, so as to avoid para-xylene leakage to cause unnecessary harm to the operator.
[0030] The buffer tank of the storage system can be further improved. The buffer tank 3 of the storage system is provided with a liquid slag discharge port, and at the same time, the liquid slag discharge port is connected to a liquid slag storage tank through a pipeline. After the condenser condenses the mixed gas, a very small amount of liquid slag containing methanol and other impurities will appear and enter the buffer tank. By setting a liquid slag discharge port in the buffer tank 3, the liquid slag can be removed through the liquid slag discharge port. emission.
[0031] The paraxylene storage process based on inert gas protection provided by the present invention adopts an argon protection process. Since argon is an inert gas, it is an ideal protective gas. When argon is passed into the paraxylene storage tank, the container As the internal pressure increases, the partial pressure of argon increases, and the partial pressure of gases such as methanol will drop, preventing it from reaching the explosive limit. The argon pressure is controlled at an absolute pressure of 0.1-3.4Mpa, which reduces the explosion limit of p-xylene and makes the equipment operation safer. Moreover, the process of the present invention recycles argon, innovatively avoids the inevitable environmental pollution caused by inert gas emissions, and has good promotion value and economic benefits.
