A glycol pre-dehydrator column apparatus and method of use thereof

Abstract

The application discloses a kind of ethylene glycol predehydration tower device and its use method, belong to ethylene glycol dehydration technical field, including for the predehydration of ethylene glycol aqueous solution ethylene glycol predehydration tower, it is characterized by: in the ethylene glycol predehydration tower from top to bottom installation mist pad, spraying device, first elastic tray, second elastic tray, third elastic tray and fourth elastic tray, wherein, first elastic tray, second elastic tray, third elastic tray and fourth elastic tray are identical in structure, and the passage of flexible valve as vapor-liquid outlet is provided in the elastic tray, and the opening degree of flexible valve is automatically adjusted according to the change of vapor-liquid flow, and it also has downcomer, for the liquid of upper tray is introduced to the tray of lower part, the condensate of upper tray is introduced to the tray of lower part and gas phase is contacted and mixed, solve the technical problems that the operation flexibility of ethylene glycol predehydration tower is low and the predehydration effect is poor, mainly applied to ethylene glycol predehydration.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ethylene glycol dehydration, and particularly relates to an ethylene glycol pre-dehydration tower device and a use method thereof. BACKGROUND

[0002] With the continuous growth of China's economy and the acceleration of urbanization process, the demand for ethylene glycol in the chemical industry is increasing. The method of producing ethylene glycol by hydration of ethylene oxide is the most commonly used method in the industry at present. The hydration reaction is to add ethylene oxide and water into the reactor in a proper proportion to generate ethylene glycol under high temperature and high pressure. In the process of producing ethylene glycol, in order to facilitate further vacuum dehydration of ethylene glycol, it is necessary to carry out a pre-dehydration treatment on ethylene glycol. In this process, the dehydration efficiency and the operation flexibility of the operation tower are particularly important. The lower the dehydration efficiency, the greater the material loss of the device. A small operation flexibility range will increase the load of the device and greatly increase the cost of energy consumption, which is not conducive to the development of enterprises. At present, the optimization process of energy consumption and material consumption of chemical production devices is accelerating. In order to maximize the benefits, the applicant found that through certain technical improvement, the operation flexibility of the pre-dehydration tower can be expanded, the chemical oxygen demand of waste water can be effectively reduced, and the amount of reflux condensate can be greatly reduced, thereby reducing the use of steam and saving costs.

[0003] 202311476493.1 discloses a method for dehydrating ethylene glycol aqueous solution, which comprises the following steps: first, modifying cationic resin with metal ions to obtain modified cationic resin; second, flowing ethylene glycol aqueous solution and excess butyl aldehyde through a packed tower filled with modified cationic resin and reacting for a period of time; wherein the butyl aldehyde serves as both a reactant and an extractant; and finally, after the reaction for a period of time, performing static separation, using modified cationic resin as a catalyst, hydrolyzing the extract phase at a certain temperature, then distilling and recovering butyl aldehyde to obtain concentrated ethylene glycol aqueous solution.

[0004] The above device needs to use a large amount of butyl aldehyde and has low dehydration efficiency and operation flexibility. Therefore, how to improve the pre-dehydration effect and operation flexibility of the ethylene glycol device is an urgent task. SUMMARY

[0005] The purpose of the present application is to provide an ethylene glycol pre-dehydration tower device and a use method thereof, so as to solve the technical problems of low operation flexibility and poor pre-dehydration effect of the ethylene glycol pre-dehydration tower.

[0006] The technical problem is solved by the following technical scheme: a kind of ethylene glycol predehydration tower device and its using method, including the ethylene glycol predehydration tower for the predehydration of ethylene glycol aqueous solution, it is characterized in that: in the ethylene glycol predehydration tower, from top to bottom, mist pad, spraying device, first flexible tray, second flexible tray, third flexible tray and fourth flexible tray are installed, wherein the structure of first flexible tray, second flexible tray, third flexible tray and fourth flexible tray is the same, flexible tray has float valve as the passage of vapor-liquid outlet, float valve automatically adjusts opening according to the change of vapor-liquid flow, also has downcomer, for the liquid of upper tray is introduced to the lower tray, the condensate of upper tray is introduced to lower tray and gas phase is contacted and mixed.

[0007] Process condensate water pipeline and clean condensate water pipeline converge to supply liquid to the spraying device, process condensate water pipeline and clean condensate water pipeline are arranged with the same first delivery pump, first flow meter and first flow valve, first gate valve is installed on the converging pipeline of clean condensate water pipeline and process condensate water pipeline, feed pipeline is introduced from the outside to ethylene glycol aqueous solution to be added from the middle of ethylene glycol predehydration tower, process condensate water pipeline and clean condensate water pipeline send condensate water in process condensate water pipeline and clean condensate water pipeline to spraying device by first delivery pump, wherein the first delivery pumps of process condensate water pipeline and process condensate water pipeline can be opened at the same time, the flow and delivery of each pipeline are measured by first flow meter and first flow valve, and the liquid supplement of ethylene glycol predehydration tower is met by using multiple condensate sources.

[0008] Ethylene glycol aqueous solution is introduced from the bottom of ethylene glycol predehydration tower, reheated by tower kettle reboiler, and then refluxed into ethylene glycol predehydration tower, tower kettle reboiler is heated by steam pipeline, 0.5Mpa steam is connected to steam pipeline to heat tower kettle reboiler, second gate valve, second flow meter and second flow valve are arranged on steam pipeline, pressure relief pipeline is connected to the upper part of ethylene glycol predehydration tower, second pressure gauge and flow rate controller are arranged on pressure relief pipeline, pressure relief pipeline is used to connect low-pressure steam generated by ethylene glycol dehydration, the discharge speed of low-pressure steam is controlled by second pressure gauge and flow rate controller, low-pressure steam is used for heat tracing of tower kettle reboiler to maintain the temperature of tower kettle reboiler and reduce the steam consumption of tower kettle reboiler, and low-pressure steam can also be used for pipeline heat tracing in the plant area, and the condensate water generated by heat tracing is recycled.

[0009] The bottom of the ethylene glycol predehydration tower is connected to the first drainage funnel through the drainage pipeline, and the branch pipeline connected to the second delivery pump is connected to the drainage pipeline.

[0010] Further, the pressure difference between the upper part of the first flexible tray and the lower part of the fourth flexible tray is greater than 10kpa.

[0011] Further, the ethylene glycol pre-dehydration tower is provided with a first thermometer and a second thermometer, the first thermometer displays gas phase temperature, and the second thermometer displays liquid phase temperature.

[0012] Further, the second conveying pump is also connected with the ethylene glycol pre-dehydration tower bottom filter through a conveying pipeline, the conveying pipeline is sequentially provided with a first pressure gauge, a third gate valve and a fourth gate valve, the upper portion of the ethylene glycol pre-dehydration tower bottom filter is connected with a third water drain funnel through a tower top pipeline, the tower top pipeline is provided with a fifth gate valve, and part of the liquid filtered through the ethylene glycol pre-dehydration tower bottom filter is sent to a dehydration tower for vacuum complete dehydration, and the other part is introduced into ethylene glycol downstream through the third water drain funnel.

[0013] The lower portions of the first water drain funnel, the second water drain funnel and the third water drain funnel are converged and then sent to ethylene glycol downstream.

[0014] Further, the total water inflow of the clean condensate water and the process condensate water is 15% to 30% of the ethylene glycol inflow, steam with a proportion of 20% to 35% of the ethylene glycol inflow is used to heat the tower bottom reboiler, the temperature of the tower bottom liquid is above 140 DEG C, the low-pressure steam flow rate of the ethylene glycol pre-dehydration tower top is 40% to 60% of the sum of the total water inflow and the inflow, and the pressure difference between the upper portion of the first flexible tray and the lower portion of the fourth flexible tray is 10-11 mpa.

[0015] Compared with the prior art, the present application has the following advantages: through the combination of multiple flexible trays, the operation flexibility of the ethylene glycol pre-dehydration tower is expanded, on the other hand, according to the flow rate of the ethylene glycol aqueous solution and the amount of the condensate water, the tower top steam discharge speed and discharge amount of the pressure relief pipeline are adjusted, the pressure difference between the upper portion of the first flexible tray and the lower portion of the fourth flexible tray is maintained, the pre-dehydration capacity of the ethylene glycol is improved, the content of the tower top organic matter is less than 0.02 wt%, and the production cost is low due to the more reasonable structure, so the present application is suitable for overall promotion and application. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a process flow chart of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to 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 of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0018] In the description of the invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] Example 1:

[0020] In one technical solution of the present invention, Figure 1 As shown, an ethylene glycol pre-dehydration tower device and a method of using the same include an ethylene glycol pre-dehydration tower 9 for pre-dehydrating an ethylene glycol aqueous solution, characterized in that a mist pad 8, a spray device 10, a first elastic tray 11, a second elastic tray 13, a third elastic tray 14, and a fourth elastic tray 16 are installed from top to bottom in the ethylene glycol pre-dehydration tower 9. The elastic trays have float valves as channels for vapor and liquid to be discharged. The float valves automatically adjust their opening according to changes in vapor and liquid flow rates. The elastic trays also have downcomers for draining liquid from the upper tray to the lower tray, and draining condensate from the upper tray to the lower tray for contact and mixing with the vapor phase.

[0021] The process condensate water pipeline 2 and the clean condensate water pipeline 3 are connected to supply liquid to the spray device 10. The process condensate water pipeline 2 and the clean condensate water pipeline 3 are arranged in the same manner and are both provided with a first delivery pump 5, a first flow meter 6 and a first flow valve 7. A first gate valve 4 is installed on the converging pipeline of the clean condensate water pipeline 3 and the process condensate water pipeline 2. The feed pipeline 40 introduces ethylene glycol aqueous solution from outside the boundary and adds it to the middle of the ethylene glycol pre-dehydration tower 9. The process condensate water pipeline and the clean condensate water pipeline use the first delivery pump to deliver the condensed water in the process condensate water pipeline and the clean condensate water pipeline to the spray device, wherein the first delivery pumps of the process condensate water pipeline and the process condensate water pipeline can be started at the same time, and the flow rate and delivery volume of each pipeline are respectively measured by the first flow meter and the first flow valve, and the multiple condensate sources are used to meet the liquid replenishment volume of the ethylene glycol pre-dehydration tower;

[0022] The ethylene glycol aqueous solution from the bottom of the ethylene glycol predehydration tower 9 is introduced into the tower kettle reboiler 20 after being heated, and then is refluxed into the ethylene glycol predehydration tower 9; the tower kettle reboiler 20 is heated by steam from the steam pipeline 41, and the second gate valve 17, the second flow meter 18 and the second flow valve 19 are arranged on the steam pipeline 41; the upper part of the ethylene glycol predehydration tower 9 is connected with the pressure relief pipeline 44, and the second pressure gauge 32 and the flow rate controller 33 are arranged on the pressure relief pipeline 44; the pressure relief pipeline is used for discharging low-pressure steam generated by the dehydration of ethylene glycol, and the discharge speed of the low-pressure steam is controlled by the second pressure gauge and the flow rate controller; the low-pressure steam is used for heating the tower kettle reboiler, so that the temperature of the tower kettle reboiler is maintained, and the steam consumption of the tower kettle reboiler is reduced; meanwhile, the low-pressure steam can be used for pipeline heating in the factory area, and the condensed water generated by the heating is recycled.

[0023] The bottom of the ethylene glycol predehydration tower 9 is connected with the first water drain funnel 21 through the liquid discharge pipeline 45, and the branch pipeline 46 is connected with the second delivery pump 23; the second delivery pump 23 is connected with the second water drain funnel 22 through the pipeline.

[0024] The ethylene glycol predehydration tower 9 is provided with the first temperature gauge 12 and the second temperature gauge 15; the first temperature gauge 12 displays the gas phase temperature, and the second temperature gauge 15 displays the liquid phase temperature.

[0025] The second delivery pump 23 is further connected with the delivery pipeline 47, and the delivery pipeline 47 is communicated with the ethylene glycol predehydration tower kettle filter 28; the first pressure gauge 24, the third gate valve 25 and the fourth gate valve 26 are arranged on the delivery pipeline 47 in sequence; the upper part of the ethylene glycol predehydration tower kettle filter 28 is connected with the third water drain funnel 29 through the overhead pipeline 48; the fifth gate valve 27 is arranged on the overhead pipeline 48; part of the liquid filtered by the ethylene glycol predehydration tower kettle filter 28 is sent to the dehydration tower for complete dehydration under vacuum, and the other part is introduced into the ethylene glycol downstream through the third water drain funnel 29.

[0026] The lower parts of the first water drain funnel 21, the second water drain funnel 22 and the third water drain funnel 29 are converged and then are sent to the ethylene glycol downstream.

[0027] According to the technical scheme, the feed pipeline 40 is connected with the upstream raw material and is introduced into the ethylene glycol predehydration tower 9; part of the ethylene glycol aqueous solution in the ethylene glycol predehydration tower 9 is introduced into the tower kettle reboiler 20; the ethylene glycol aqueous solution is heated by the tower kettle reboiler 20 and is then sent back from the lower part of the ethylene glycol predehydration tower 9; the ethylene glycol aqueous solution is gasified after being heated.

[0028] The process condensate line 2 and the clean condensate line 3 send the condensate from the outside access to the spray device 10 through the first delivery pump 5, and the spray device 10 sprays the condensate in the glycol pre-dehydration tower 9. During the falling of the condensate, the liquid phase fully contacts the vapor phase of the glycol aqueous solution. When the gaseous glycol is cooled, the molecular heat motion gradually weakens, the distance between the molecules decreases, and the force between the molecules increases. The gaseous glycol gradually changes into liquid. The glycol in the high-temperature gas phase is condensed and releases heat. The condensate absorbs the heat released by the condensation of the gaseous glycol, the average kinetic energy of the molecules increases, the motion rate accelerates, the distance between the molecules gradually increases, and the condensate gradually changes into gas.

[0029] The water in the liquid phase condensate falling from the lower part of the first tray 11, the second tray 13, the third tray 14, and the fourth tray 16 is heated by the rising gaseous glycol, the water vaporizes and rises, the propylene glycol liquefies and falls, the gaseous phase is condensed and removed multiple times, and the liquid phase continuously vaporizes to realize the pre-dehydration of the glycol aqueous solution. The dehydrated glycol solution is sent to the downstream of the glycol through the first drainage funnel 21 from the drainage line 45. The first drainage funnel, the second drainage funnel, and the third drainage funnel are used to collect and separate the water phase. In the operation of the pre-dehydration tower, the mixture of glycol and water can produce dust. The drainage funnel is used to collect and separate the water phase to prevent the water phase from recontacting with the glycol mixture. By controlling the discharge of the water phase, the drainage funnel helps to maintain the liquid level in the tower and ensures the stability of the dehydration process. At the same time, the drainage funnel reduces the potential glycol in the water flowing out of the tower, maintains the purity of the glycol, and sends the glycol solution in the branch line 36 to the second drainage funnel. The glycol solution in the branch line 36 can also be sent to the glycol pre-dehydration tower kettle filter 28 through the second delivery pump 23. After being filtered by the glycol pre-dehydration tower kettle filter 28 to remove possible solid impurities, the glycol solution is sent to the dehydration tower for vacuum drying.

[0030] Example 2:

[0031] A glycol pre-dehydration tower device and its use method. Based on the glycol feed amount, the total water amount of the clean condensate and the process condensate is 15% to 30% of the glycol feed amount. The steam used for heating the kettle reboiler 20 is 20% to 35% of the glycol feed amount, which makes the temperature of the kettle liquid above 140℃. The low-pressure steam flow rate at the top of the glycol pre-dehydration tower 9 is 40% to 60% of the sum of the total water amount and the feed amount, which maintains the pressure difference between the upper part of the first flexible tray 11 and the lower part of the fourth flexible tray 16 at 10-11mpa.

[0032] By adopting the technical scheme, one embodiment of the present application is as follows: the total water quantity of the clean condensate water and the process condensate water is 25% of the ethylene glycol feed quantity, the steam quantity used for heating the column still reboiler 20 is 30% of the ethylene glycol feed quantity, the temperature of the column still liquid is above 140℃, the low-pressure steam flow rate at the top of the ethylene glycol predehydration tower 9 is 50% of the sum of the total water quantity and the feed quantity, and the pressure difference between the upper part of the first flexible tray 11 and the lower part of the fourth flexible tray 16 is 10.3 mpa;

[0033] Further statements of the above technical scheme are as follows: the feed quantity of the ethylene glycol aqueous solution raw material is 184 t / h, the total water quantity of the clean condensate water and the process condensate water is 7 t / h, the flow rate of the column still reboiler 20 is 1660 t / h, the steam pressure used for heating the column still reboiler 20 is 0.5 Mpa, the flow rate thereof is 65.3 t / h, the pressure difference between the upper part of the first tray 11 and the lower part of the fourth tray 16 is controlled to be 10.3 Kpa, the temperature of the column still liquid at the bottom of the ethylene glycol predehydration tower is 142℃, and the steam discharge quantity of the pressure relief pipeline is 97 t / h.

[0034] The above description is only the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements without departing from the principles of the present application, and these improvements should also be considered as the protection scope of the present application.

Claims

1. A process for the predehydration of an aqueous ethylene glycol solution, comprising a predehydration column (9) for the predehydration of an aqueous ethylene glycol solution, characterized in that: The mist pad (8), the spraying device (10), the first flexible tray (11), the second flexible tray (13), the third flexible tray (14) and the fourth flexible tray (16) are installed from top to bottom in the ethylene glycol predehydration tower (9); The process condensate water pipeline (2) and the clean condensate water pipeline (3) are converged to supply liquid to the spraying device (10), the same first delivery pump (5), the first flow meter (6) and the first flow valve (7) are arranged on the process condensate water pipeline (2) and the clean condensate water pipeline (3), the first gate valve (4) is additionally arranged on the converging pipeline of the clean condensate water pipeline (3) and the process condensate water pipeline (2), and the feed pipeline (40) is introduced from the outside to introduce the ethylene glycol aqueous solution from the middle of the ethylene glycol predehydration tower (9); The ethylene glycol aqueous solution is introduced from the bottom of the ethylene glycol predehydration tower (9), heated by the tower kettle reboiler (20) and returned to the ethylene glycol predehydration tower (9), the tower kettle reboiler (20) is heated by steam from the steam pipeline (41), the second gate valve (17), the second flow meter (18) and the second flow valve (19) are arranged on the steam pipeline (41), the pressure relief pipeline (44) is connected to the upper part of the ethylene glycol predehydration tower (9), and the second pressure meter (32) and the flow rate controller (33) are arranged on the pressure relief pipeline (44). The bottom of the ethylene glycol predehydration tower (9) is connected with the first water drain funnel (21) through the liquid discharge pipeline (45), the branch pipeline (46) is connected to the second delivery pump (23) and connected with the second water drain funnel (22) through the pipeline.

2. A device for a glycol pre-dehydrator column according to claim 1, and method of use thereof, characterized by: The pressure difference between the upper part of the first flexible tray (11) and the lower part of the fourth flexible tray (16) is greater than 10 kpa.

3. A glycol pre-dehydrator tower apparatus and method of using the same according to claim 2, wherein: The ethylene glycol predehydration tower (9) is provided with the first temperature meter (12) and the second temperature meter (15), the first temperature meter (12) displays the gas phase temperature, and the second temperature meter (15) displays the liquid phase temperature.

4. A glycol pre-dehydrator column apparatus and method of using the same according to claim 3, wherein: The second delivery pump (23) is also connected with the ethylene glycol predehydration tower kettle filter (28) through the delivery pipeline (47), the first pressure meter (24), the third gate valve (25) and the fourth gate valve (26) are sequentially arranged on the delivery pipeline (47), the upper part of the ethylene glycol predehydration tower kettle filter (28) is connected with the third water drain funnel (29) through the tower top pipeline (48), the fifth gate valve (27) is arranged on the tower top pipeline (48), a part of the liquid filtered by the ethylene glycol predehydration tower kettle filter (28) is sent to the dehydration tower for vacuum complete dehydration, and the other part is introduced into the ethylene glycol downstream through the third water drain funnel (29); The lower parts of the first water drain funnel (21), the second water drain funnel (22) and the third water drain funnel (29) are converged and sent to the ethylene glycol downstream.

5. A device for a glycol pre-dehydrator column according to claim 1, and method of using the same, characterized by: The total water quantity of the clean condensate water and the process condensate water is 15-30% of the ethylene glycol feed quantity, the steam quantity for heating the tower bottom reboiler (20) is 20-35% of the ethylene glycol feed quantity, the temperature of the tower bottom liquid is above 140℃, the low pressure steam flow rate at the top of the ethylene glycol predehydration tower (9) is 40-60% of the sum of the total water quantity and the feed quantity, and the pressure difference between the upper part of the first flexible tray (11) and the lower part of the fourth flexible tray (16) is 10-11mpa.

Images