CN106632236A - Method for continuously removing heavy aromatics from solvent online - Google Patents

Abstract

The invention discloses a method capable of continuously removing heavy aromatics in a solvent online: 1) taking out the solvent less than 2% of the total poor solvent circulation in the recovery tower for online removal of heavy aromatics; 2) combining the solvent taken out with the solvent in the recovery tower The water taken out is mixed; 3) the mixture is passed through the static separation of the primary separator and the secondary separator; 4) the solvent is taken out and the new solvent is separated from the primary separator and the secondary separator and injected into the wet solvent tank, and the secondary The deheavy component oil separated by the separator is sent to the heavy component collection tank; 5) The new solvent in the wet solvent tank is injected back into the recovery tower through the pump. The continuous on-line deweighting of benzene hydrogenation solvent ensures the quality of solvent and product, and greatly reduces the solvent consumption. The continuous on-line deweighting can replace the original regeneration tower system, thereby reducing the consumption of heat transfer oil and gas. After the system is in operation, regardless of the stability of the system operation, the economic benefits are remarkable, especially the potential environmental protection benefits.

Description

A method capable of continuously removing heavy aromatics in solvents online

technical field

The invention relates to the field of coal chemical industry.

Background technique

In the liquid-liquid extraction process using sulfolane as a solvent, it plays an important role in the coal chemical benzene hydrogenation industry. The use of sulfolane liquid-liquid extraction for aromatics extraction can obtain higher aromatics yield and product quality. However, the deterioration of sulfolane in industrial operation has always been a prominent problem that plagues the extraction process of aromatics.

Sulfolane deteriorates during the extraction process, which reduces its extraction ability. The main manifestations are darker color of sulfolane, lower pH value, inclusion of heavy aromatics and some colloids in the solvent to form deposits, and increased solvent loss. In normal industrial-scale production, in addition to the absolutely tight airtightness of the operating system, the continuous on-line removal of impurities by sulfolane solvent is an urgent process, otherwise there will be no high-quality solvent, which will affect the normal production of the benzene hydrogenation system, greatly affecting the product yield and quality.

Contents of the invention

The technical problem to be solved by the invention is to realize a method capable of continuously removing heavy aromatics in a solvent online.

In order to achieve the above object, the technical scheme adopted in the present invention is: a method capable of continuously removing heavy aromatics in the solvent online:

1) Take out the solvent less than 2% of the total lean solvent circulation in the recovery tower to remove heavy aromatics online;

2) mixing the solvent taken out with the water taken out in the recovery tower;

3) the mixture is passed through the static separation of the primary separator and the secondary separator;

4) Take out the solvent, separate the new solvent from the primary separator and the secondary separator, and inject it into the wet solvent tank, and send the heavy component oil separated by the secondary separator into the heavy component collection tank;

5) The new solvent in the wet solvent tank is pumped back into the recovery tower.

The solvent removed in 1) accounts for 1% of the total lean solvent circulation.

The water taken out of the recovery tower in 2) is obtained by the following method: the oil gas and water vapor stripped in the recovery tower are transported to the oil-water separation tank through the condenser, and the separated water is transported to the pipeline mixer and mixed with the solvent taken out .

The weight ratio of the solvent taken out in the above 2) to the water taken out of the recovery tower is 10:1.

The de-heavy component oil in the heavy component collection tank is pumped to the cleaning oil tower of the oil depot loading system, and the de-heavy oil in the cleaning oil tower is regularly sent to the coal tar distillation system by tanker.

Based on the continuous detachment equipment of the method capable of continuously removing heavy aromatics in the solvent on-line, the lean solvent outlet of the recovery tower is connected to a lean solvent pump through a pipeline, and the lean solvent pump transports the lean solvent to a pipeline mixer, and the recovery tower is set above The pipeline collects the stripped oil gas and water vapor and transports them to the condenser, and the condenser transports the mixed liquid to the oil-water separation tank. The separated water outlet of the oil-water separation tank is connected to a water pump through a pipeline, and the water pump transports the separated water to the pipeline. Mixer, the liquid outlet of the pipeline mixer is separated through the static separation of the primary separator and the secondary separator, and the bottom boots of the primary separator and the secondary separator are discharged into the wet solvent tank in the tank area , the deheavy component oil separated from the top of the secondary separator is sent to the heavy component collection tank, and the wet solvent tank passes the new solvent pump to the recovery tower.

The output port of the new solvent pump is connected to the input port of the rich solvent pump through a pipeline, and the pipeline is connected to the liquid outlet of the extraction tower through the first three-way valve, and the output port of the rich solvent pump is connected to the recovery tower through a pipeline.

The liquid outlet pipeline of the lean solvent pump is provided with a second three-way valve, one outlet of the second three-way valve is connected to the pipeline mixer, and the other outlet is connected to the extraction tower.

The advantage of the present invention is that in normal production, about 1% of the poor solvent circulation amount is continuously removed from heavy aromatics and impurities on-line, thereby ensuring the quality of the poor solvent entering the extraction tower, improving the extraction efficiency of the extraction tower, and increasing the concentration of aromatics and impurities. The separation efficiency of non-aromatics improves the quality of aromatics and non-aromatics and reduces the loss of poor solvents. At the same time, the heavy aromatics after de-weighting are comprehensively utilized and used in the cleaning oil tower during loading, which also solves the on-site escaping odor of the washing oil, and also solves the problem of oil washing clogging in the washing oil tower , Clean the excess de-heavy oil from the oil tower, and send it to the tar distillation system by tanker for recycling.

Description of drawings

The following is a brief description of the content expressed by each piece of accompanying drawing in the description of the present invention:

Figure 1 is a flow chart of the online continuous removal of heavy aromatics in solvents.

detailed description

As shown in Figure 1, the total lean solvent circulation (about 60 tons/h) at the poor solvent outlet, cut out 600kg/h (about 1%) solvent and enter the online weight removal system, and cut out 60kg from the outlet of the recovery tower water pump /h (ratio to solvent is 1:10) system process separation water is mixed in pipeline mixer, and then separated by the first-level separator and second-level separator, and the solvent is pumped from the bottom of the first-level and second-level separator The bucket is discharged into the wet solvent tank in the tank area, and the de-heavy component oil (abbreviated as de-heavy oil) separated from the top of the secondary separator enters the heavy component collection tank, and is pumped to the cleaning oil tower of the oil depot loading system. For the circulation of the oil cleaning tower and the absorption of the benzene gas loaded on the truck, the deheavy oil in the oil cleaning tower is regularly sent to the coal tar distillation system by tank trucks, and finally forms coal tar products.

This process will use the system's own process to separate water and mix it with a solvent before entering the system. The water balance will be established inside the system without additional soft water. Solvent on-line continuous excision weight loss and solvent replenishment form a dynamic balance, so that each tank, tower and flow are in a stable state.

The continuous on-line deweighting of benzene hydrogenation solvent ensures the quality of solvent and product, and greatly reduces the solvent consumption. The continuous on-line deweighting can replace the original regeneration tower system, thereby reducing the consumption of heat transfer oil and gas. After the system is in operation, regardless of the stability of the system operation, the economic benefits are remarkable, especially the potential environmental protection benefits.

Indirect benefits: During the operation of the regeneration tower, regular slag discharge is required. The slag contains not only sulfolane but also other polymers. Solid waste treatment is quite difficult and has an unpleasant smell. After online continuous deweighting, the deheavy oil is finally sold in the form of tar products, which has certain economic benefits.

direct benefit. The online continuous de-weighting system has achieved remarkable results in reducing costs and increasing efficiency.

Save about 12 tons of new sulfolane solvent every year. According to 19,000 yuan/t, the annual consumption of sulfolane solvent will be reduced, and the direct economic benefits of harvest will be: 12×1.9=22.8 (10,000 yuan/a).

After the solvent quality is improved, the content of aromatics in non-aromatic products is reduced, and the yield of aromatics is increased. According to the price difference between aromatics and non-aromatic products, the direct economic benefits harvested are: the benzene content of non-aromatics in 2015 was 12% lower than the average in 2014. %, the output of non-aromatics is 1,500 tons, the benzene content of non-aromatics is reduced by 180 tons, the price difference between pure benzene and non-aromatics is 2,000 yuan/t (according to the price difference at that time), direct profit=180×0.2=36 (10,000 yuan/a)

After the online continuous deweighting system is running, the energy saving is remarkable. The regeneration tower reduces the heat consumption of the heat transfer oil, reduces the gas consumption of the heat transfer oil furnace, and can reduce the gas consumption by 50m3/h per hour. Calculated according to the gas price of Maanshan Iron and Steel 0.6 yuan/m3, the direct economic benefits harvested are: 50× 8000 (annual running time)×0.6÷10000＝24(10,000 yuan/a)

Therefore, after the operation of the continuous on-line de-weighting system and the shutdown of the regeneration system, the annual economic benefit is 828,000 yuan.

Claims (8)

1. A method capable of continuously removing heavy aromatics in the online solvent, characterized in that: 1) Take out the solvent less than 2% of the total lean solvent circulation in the recovery tower to remove heavy aromatics online; 2) mixing the solvent taken out with the water taken out in the recovery tower; 3) the mixture is passed through the static separation of the primary separator and the secondary separator; 4) Take out the solvent, separate the new solvent from the primary separator and the secondary separator, and inject it into the wet solvent tank, and send the heavy component oil separated by the secondary separator into the heavy component collection tank; 5) The new solvent in the wet solvent tank is pumped back into the recovery tower. 2. The method capable of continuously removing heavy aromatics in the solvent online according to claim 1, characterized in that: the solvent taken out in 1) accounts for 1% of the total lean solvent circulation. 3. the method for continuously removing heavy aromatics in the online solvent according to claim 2, characterized in that: the water taken out in the recovery tower in the 2) is obtained by the following method: the oil gas after stripping in the recovery tower The water vapor is sent to the oil-water separation tank through the condenser, and the separated water is sent to the pipeline mixer to mix with the solvent. 4. The method capable of continuously removing heavy aromatics in the solvent online according to claim 1, 2 or 3, wherein the weight ratio of the solvent taken out in 2) to the water taken out in the recovery tower is 10:1. 5. The method according to claim 4 capable of continuously removing heavy aromatics in the solvent on-line, characterized in that: the de-heavy component oil in the heavy component collection tank is pumped to the cleaning oil tower of the oil depot loading system, The de-heavy oil in the cleaning oil tower is sent to the coal tar distillation system by tank truck regularly. 6. The continuous detachment device based on the method for the online continuous removal of heavy aromatics in the solvent according to any one of claims 1-5, it is characterized in that: the poor solvent outlet of the recovery tower is connected to the poor solvent pump through pipelines, and the poor solvent The pump transports the poor solvent to the pipeline mixer, and a pipeline is set above the recovery tower to collect the stripped oil gas and water vapor and transport them to the condenser, and the condenser transports the mixed liquid to the oil-water separation tank, and the separated water in the oil-water separation tank The outlet is connected to a water pump through a pipeline, and the water pump transports the separated water to the pipeline mixer. The bottom bucket of the separator is discharged into the wet solvent tank in the tank area, and the deheavy component oil separated from the top of the secondary separator is transported to the heavy component collection tank, and the wet solvent tank is passed through the new solvent pump. Solvent to recovery tower. 7. The continuous detachment device according to claim 6, characterized in that: The output port of the new solvent pump is connected to the input port of the rich solvent pump through a pipeline, and the pipeline is connected to the liquid outlet of the extraction tower through the first three-way valve, and the output port of the rich solvent pump is connected to the recovery tower through a pipeline. 8. The continuous detachment device according to claim 7, characterized in that: the liquid outlet pipeline of the lean solvent pump is provided with a second three-way valve, one outlet of the second three-way valve is connected to the pipeline mixer, and the other is One outlet is connected to the extraction column.