A process for online treatment of fractionating column tray plugging

Abstract

The process method for online treatment of the blockage of the fractionating tower tray realizes the flushing of the upper tray of the fractionating tower, reduces the whole tower pressure difference of the fractionating tower, eliminates the blockage of the tray by dirt or polymer, solves the liquid flooding of the upper tray of the fractionating tower, effectively cuts and separates products, ensures the quality of the side line products of the fractionating tower, avoids the shutdown and maintenance of the device, and produces considerable economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical production, in particular to a process method for online treatment of plugging of trays of a fractionating tower. BACKGROUND

[0002] The fractionating tower is a tower type vapor-liquid device for distillation, and is widely used in petrochemical devices. In the use process of the fractionating tower, due to treatment of external residual liquid and light and heavy contaminated oil, deterioration of raw material properties, scaling of the fractionating tower or polymer plugging of the trays, full tower pressure drop of the fractionating tower is increased, liquid flooding of the upper trays of the fractionating tower, separation effect is deteriorated, and the final boiling point of the overhead product is out of standard. Currently, the treatment is performed by means of cleaning the trays of the fractionating tower in the device shutdown maintenance mode, and the cost is too high. SUMMARY

[0003] In order to solve the technical defects existing in the prior art, the present application provides a process method for online treatment of plugging of trays of a fractionating tower, which fully utilizes the existing process flow, and under the premise of no shutdown maintenance, tows into the fractionating tower plugging section to flush the trays with toluene and heavy aromatic hydrocarbons, so that the scale or polymer of the fractionating tower trays is dissolved and carried out by the product, the pressure drop of the fractionating tower is reduced, the liquid flooding of the trays is solved, the normal production of the fractionating tower is restored, the final boiling point of the product is ensured to be qualified, and the enterprise benefit is increased.

[0004] The technical solution adopted by the present application is as follows: a process method for online treatment of plugging of trays of a fractionating tower, comprising the following steps:

[0005] (1) After the heavy aromatic hydrocarbons are pressurized, they are sent to the 11th tray of the fractionating tower through the light contaminated oil back refining line and the rich absorption oil line, the heavy aromatic hydrocarbons enter the 11th tray of the fractionating tower for mass transfer and heat transfer, and then descend to the diesel oil collecting tank layer by layer after being carried by the liquid phase reflux in the tower, the solubility of the heavy aromatic hydrocarbons is utilized to dissolve the gum in the scale on the trays, and the scale is dispersed by the liquid phase reflux, and then is carried out by the diesel oil;

[0006] (2) After the frequency of backwashing of the diesel oil filter returns to normal and the impurities in the diesel oil before the filter are obviously reduced, the flushing of the 11th to 14th trays of the fractionating tower by the heavy aromatic hydrocarbons is stopped;

[0007] (3) After the toluene is pressurized, it is sent to the 11th tray of the fractionating tower through the light contaminated oil back refining line and the rich absorption oil line, the toluene enters the 11th tray of the fractionating tower for mass transfer and heat transfer, and then rises to the 1st tray at the top of the fractionating tower layer by layer after being gasified and carried by the gas phase reflux, the solubility of the toluene is utilized to dissolve the gum in the scale on the trays, and the scale is dispersed by the liquid phase reflux, and then descends to the diesel oil collecting tank layer by layer after being carried by the diesel oil;

[0008] (4) After the frequency of backwashing of the diesel oil filter returns to normal and the impurities in the diesel oil before the filter are obviously reduced, and the pressure drop of the fractionating tower top and bottom decreases to the normal value, the flushing of the 1st to 11th trays of the fractionating tower by the toluene is stopped, and the treatment of plugging of the fractionating tower trays is completed.

[0009] The step (1) further comprises that after the heavy aromatic hydrocarbon establishes the liquid level through the light oil tank, the heavy aromatic hydrocarbon is pressurized by the light oil pump and then input into the light oil recycling line→rich absorption oil line→11th tray of the fractionating tower.

[0010] The flow rate of the heavy aromatic hydrocarbon input in the step (1) is 10 t / h.

[0011] The step (3) further comprises that after the toluene establishes the liquid level through the light oil tank, the toluene is pressurized by the light oil pump and then input into the light oil recycling line→rich absorption oil line→11th tray of the fractionating tower.

[0012] The flow rate of the toluene input in the step (3) is 5 t / h.

[0013] The beneficial effects of the present application are that the present application provides an online treatment process for the clogging of the fractionating tower tray, through the design of a specific process flow and operation, the upper tray of the fractionating tower is washed, the pressure difference of the whole fractionating tower is reduced, the scaling or polymer clogging of the fractionating tower tray is eliminated, the liquid overflow of the upper tray of the fractionating tower is solved, the product is effectively cut and separated, the quality of the side product of the fractionating tower is ensured, the device is avoided from being shut down for maintenance, considerable economic benefits are generated, and through the online treatment of the clogging of the fractionating tower tray, the scale on the tray is effectively removed, the continuous production process and equipment of the device are not affected, the operability is strong, under the premise of not shutting down for maintenance, the toluene and heavy aromatic hydrocarbon are introduced into the clogging section of the fractionating tower to wash the tray, so that the scale or polymer on the fractionating tower tray is dissolved and carried out by the product, the pressure drop of the fractionating tower is reduced, the liquid overflow of the tray is solved, the normal production of the fractionating tower is restored, the qualified terminal boiling point of the product is ensured, and the enterprise benefits are increased. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is the process flow diagram of the technical scheme of the present application.

[0015] Figure 2 It is the pressure difference diagram of the top and bottom of the fractionating tower before and after the heavy aromatic hydrocarbon and toluene washing. DETAILED DESCRIPTION

[0016] The technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the present application.

[0017] Embodiment 1 process flow

[0018] The technical scheme comprises the following specific steps:

[0019] 1. Light oil tank collects heavy aromatics, establishes liquid level, through light oil recycling line → rich absorption oil line → 11 tray of fractionating tower;

[0020] 2. Heavy aromatics follow the liquid phase reflux of fractionating tower, from 11 tray to diesel oil collecting tank, through diesel oil pump to send out device;

[0021] 3. Light oil tank collects toluene, establishes liquid level, through light oil recycling line → rich absorption oil line → 11 tray of fractionating tower;

[0022] 4. Toluene follows the gas phase reflux of fractionating tower, from 11 tray to the top of fractionating tower, through air cooling, water cooling cooler, then through crude gasoline pump to send out device.

[0023] Example 2 Heavy aromatic rinse

[0024] Light oil tank collects heavy aromatics to establish liquid level, starts light oil pump, gives pressure to heavy aromatics, then through light oil recycling line → rich absorption oil line → 11 tray of fractionating tower, controls heavy aromatic flow 10 t / h, heavy aromatics enter 11 tray of fractionating tower to carry out mass transfer and heat transfer, then follow the liquid phase reflux in tower, drop to diesel oil collecting tank layer by layer, using the solubility of heavy aromatics, dissolves gum in scale on tray, eliminates the scale setting characteristics, is scattered after being rinsed by liquid phase reflux, then is taken out by diesel oil;

[0025] Diesel oil filter backwash frequency returns to normal, after the impurities in diesel oil before filter are obviously reduced, stops heavy aromatic rinse 11-14 tray of fractionating tower.

[0026] Example 2 Toluene rinse

[0027] Light oil tank collects toluene to establish liquid level, starts light oil pump, gives pressure to toluene, then through light oil recycling line → rich absorption oil line → 11 tray of fractionating tower, controls toluene flow 5 t / h, toluene enters 11 tray of fractionating tower to carry out mass transfer and heat transfer, then follows the gas phase reflux to rise to 1 tray layer by layer, using the solubility of toluene, dissolves gum in scale on tray, eliminates the scale setting characteristics, is scattered after being rinsed by liquid phase reflux, then drops to diesel oil collecting tank layer by layer, is taken out by diesel oil;

[0028] Diesel oil filter backwash frequency returns to normal, after the impurities in diesel oil before filter are obviously reduced, stops toluene rinse 1-11 tray of fractionating tower after the top and bottom pressure of fractionating tower decreases to normal value.

[0029] Example 3

[0030] The operation parameters of fractionating tower are shown in Table 1.

[0031] Table 1. Operation parameter list

[0032]

[0033] Tables 2 and 3 show the comparison of stabilized gasoline and diesel products from the fractionation side streams before and after flushing for heavy aromatics and toluene. According to the data in the tables, after flushing the fractionation tower trays using the process method of this invention, the final boiling point of the stabilized gasoline significantly decreased, meeting the control requirement of ≤175℃. Before flushing, the final boiling point of the stabilized gasoline was 186.7℃, and the initial boiling point of the diesel was 159.0℃, with a product overlap of 27.7℃. After flushing, the final boiling point of the stabilized gasoline was 169.0℃, and the initial boiling point of the diesel was 164.5℃, with a product overlap of 4.5℃, meeting the design requirement of 5℃ overlap.

[0034] Table 2 Coking Stabilized Gasoline

[0035]

[0036] Table 3 Coking Diesel

[0037]

[0038] The pressure difference between the top and bottom of the fractionation tower decreased significantly before and after flushing for heavy aromatics and toluene. See details. Figure 2 Before flushing, the average pressure difference between the top and bottom of the fractionation column was about 50 kPa, and after flushing, it was about 20 kPa. The average pressure difference between the top and bottom of the fractionation column decreased by 30 kPa, returning to the pressure difference value before the fractionation column trays were blocked.

[0039] Please note to all technical personnel: Although the present invention has been described according to the specific embodiments above, the inventive concept of the present invention is not limited to this invention. Any modifications that utilize the inventive concept will be included within the scope of protection of this patent.

[0040] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A process for online treatment of tray blockage in a distillation column, characterized in that, Includes the following steps: (1) After the heavy aromatics are pressurized, they are sent to the 11th tray of the fractionation tower via the light waste oil refining line → rich absorption oil line. After mass and heat transfer in the 11th tray of the fractionation tower, the heavy aromatics are refluxed with the liquid phase in the tower and descend to the diesel oil collection tank layer by layer. The solubility of heavy aromatics is used to dissolve the gum in the scale on the tray, eliminate the scale caking characteristics, and after being dispersed by the liquid phase reflux, they are carried out by the diesel oil. (2) After the backwashing frequency of the diesel filter returns to normal and the impurities in the diesel before the filter are significantly reduced, stop the heavy aromatics flushing of trays 11-14 of the fractionation tower. (3) After the toluene is pressurized, it is sent to the 11th tray of the fractionation tower via the light waste oil recycling line → rich absorption oil line. The toluene enters the 11th tray of the fractionation tower for mass and heat transfer. After vaporization, it rises layer by layer to the top 1st tray of the fractionation tower with the gas phase reflux. The toluene dissolves the colloid in the scale on the tray by utilizing the solubility of toluene, eliminating the scale caking characteristics. After being dispersed by the liquid phase reflux, it descends layer by layer to the diesel oil collection tank and is carried out by the diesel oil. (4) After the diesel filter backwashing frequency returns to normal and the diesel impurities in front of the filter are significantly reduced, and the pressure drop at the top and bottom of the fractionation tower drops to the normal value, stop flushing the trays of the fractionation tower 1-11 with toluene, and the tray blockage treatment of the fractionation tower is completed.

2. The process method for online treatment of distillation column tray blockage according to claim 1, characterized in that, The step (1) also includes establishing the liquid level of heavy aromatics in the light sludge tank, then pressurizing the heavy aromatics by the light sludge pump and inputting them into the light sludge refining line → rich absorption oil line → sent to the 11th tray of the fractionation tower.

3. The process method for online treatment of distillation column tray blockage according to claim 2, characterized in that, The flow rate of heavy aromatics input in step (1) is 10 t / h.

4. The process method for online treatment of distillation column tray blockage according to claim 1, characterized in that, Step (3) further includes establishing the liquid level of toluene in the light sludge tank, then pressurizing the toluene with the light sludge pump and inputting it into the light sludge refining line → rich absorption oil line → sent to the 11th tray of the fractionation tower.

5. The process method for online treatment of distillation column tray blockage according to claim 4, characterized in that, The toluene flow rate input in step (3) is 5t / h.

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