阅读说明：本技术 一种用于制丙烯腈的四效蒸发器 (Four-effect evaporator for preparing acrylonitrile ) 是由 石喆 李大伟 孙文生 林港 陆玲 袁亮 王泽亮 唐伟强 于 2019-09-05 设计创作，主要内容包括：本发明涉及一种用于制丙烯腈的四效蒸发器,包括依次串联设置的一效蒸发器、二效蒸发器、三效蒸发器和四效蒸发器；所述一效蒸发器底部设置有用于其底部溶液循环换热的一效换热器,所述二效蒸发器底部设置有用于其底部溶液循环换热的二效换热器,所述三效蒸发器底部设置有用于其底部溶液循环换热的三效换热器,所述四效蒸发器底部设置有用于其底部溶液循环换热的四效换热器；所述二效换热器、所述三效换热器、所述四效换热器为浮头式换热器。通过采用浮头式换热器,能够便于换热器管束抽出后,对换热器外壁的清洗更加彻底。尤其是针对制丙烯腈装置四效蒸发器在运行过程中,阻止了二、三、四效换热器被聚合物粘连堵塞,保证了其正常运行。(The invention relates to a four-effect evaporator for preparing acrylonitrile, which comprises a one-effect evaporator, a two-effect evaporator, a three-effect evaporator and a four-effect evaporator which are sequentially connected in series; the bottom of the first-effect evaporator is provided with a first-effect heat exchanger for circulating heat exchange of a solution at the bottom of the first-effect evaporator, the bottom of the second-effect evaporator is provided with a second-effect heat exchanger for circulating heat exchange of the solution at the bottom of the second-effect evaporator, the bottom of the third-effect evaporator is provided with a third-effect heat exchanger for circulating heat exchange of the solution at the bottom of the third-effect evaporator, and the bottom of the fourth-effect evaporator is provided with a fourth-effect heat; the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger are floating head heat exchangers. Through adopting floating head heat exchanger, can be convenient for the heat exchanger tube bank take out the back, more thorough to the washing of heat exchanger outer wall. Particularly, the device prevents the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger from being blocked by polymer adhesion in the operation process of the four-effect evaporator of the acrylonitrile production device, and ensures the normal operation of the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger.)

1. A four-effect evaporator for preparing acrylonitrile is characterized by comprising a first-effect evaporator (11), a second-effect evaporator (12), a third-effect evaporator (13) and a four-effect evaporator (14) which are sequentially connected in series;

the bottom of the first-effect evaporator (11) is provided with a first-effect heat exchanger (111) for circulating heat exchange of solution at the bottom of the first-effect evaporator, the bottom of the second-effect evaporator (12) is provided with a second-effect heat exchanger (121) for circulating heat exchange of solution at the bottom of the second-effect evaporator, the bottom of the third-effect evaporator (13) is provided with a third-effect heat exchanger (131) for circulating heat exchange of solution at the bottom of the third-effect evaporator, and the bottom of the fourth-effect evaporator (14) is provided with a fourth-effect heat exchanger (141;

the two-effect heat exchanger (121), the three-effect heat exchanger (131) and the four-effect heat exchanger (141) are floating head heat exchangers.

2. The four-effect evaporator for producing acrylonitrile as claimed in claim 1, wherein wire mesh defoamers (15) are respectively arranged inside one ends of the first-effect evaporator (11), the second-effect evaporator (12), the third-effect evaporator (13) and the four-effect evaporator (14) adjacent to a top head.

3. The four-effect evaporator for producing acrylonitrile as claimed in claim 2, characterized in that the distance h between the upper end of the wire mesh demister (15) and the connecting position of the top head and the evaporator satisfies: h is less than 800 mm.

4. The four-effect evaporator for producing acrylonitrile as claimed in claim 3, characterized in that the distance h between the upper end of the wire mesh demister (15) and the connecting position of the top head and the evaporator satisfies: h is more than or equal to 200mm and less than 800 mm.

5. The four-effect evaporator for producing acrylonitrile as claimed in claim 4, characterized in that the distance h between the upper end of the wire mesh demister (15) and the connecting position of the top head and the evaporator satisfies: h is more than or equal to 300mm and less than or equal to 700 mm.

6. The four-effect evaporator for producing acrylonitrile as claimed in claim 5, characterized in that the distance h between the upper end of the wire mesh demister (15) and the connecting position of the top head and the evaporator satisfies: h is more than or equal to 400mm and less than or equal to 600 mm.

7. The four-effect evaporator for the production of acrylonitrile according to any one of claims 1 to 6, characterized in that the end of the four-effect evaporator (14) adjacent to the top head is also internally provided with a lift cap tray (16).

8. The four-effect evaporator for the production of acrylonitrile according to claim 7, characterized in that the lift cap tray (16) is located below the wire mesh demister (15).

9. The four-effect evaporator for the production of acrylonitrile according to claim 8, wherein the distance L between the lift cap tray (16) and the connection location of the top head and the four-effect evaporator (14) is such that: l is less than or equal to 1500 mm.

10. The four-effect evaporator for the production of acrylonitrile according to claim 9, wherein the distance L between the lift cap tray (16) and the connection location of the top head and the four-effect evaporator (14) is such that: l is more than or equal to 800mm and less than 1500 mm.

11. The four-effect evaporator for the production of acrylonitrile according to claim 10, wherein the distance L between the lift cap tray (16) and the connection location of the top head and the four-effect evaporator (14) is such that: l is more than or equal to 850mm and less than or equal to 1300 mm.

12. The four-effect evaporator for the production of acrylonitrile according to claim 11, wherein the distance L between the lift cap tray (16) and the connection location of the top head and the four-effect evaporator (14) is such that: l is more than or equal to 900mm and less than or equal to 1100 mm.

13. The four-effect evaporator for the production of acrylonitrile according to claim 7, characterized in that the lower side of the riser cap tray (16) is further provided with a liquid leakage head (161).

14. The four-effect evaporator for producing acrylonitrile as claimed in claim 13, characterized in that the weep head (161) is a bent pipe in the shape of a hook, one end of which communicates with a weep hole on the lift cap tray (16), and the other end of which is a free end extending in a bent manner toward the lift cap tray (16).

Technical Field

The invention relates to the field of chemical industry, in particular to a four-effect evaporator for preparing acrylonitrile.

Background

The production technology of acrylonitrile at home and abroad mainly adopts a propylene ammoxidation method. The process is developed for more than 50 years, and the process technology is mature. Since the advent, there has been no major improvement in the process, mainly aiming at the research of novel catalysts and the development of novel fluidized bed reactors, and simultaneously developing the process technology improvement aiming at the purposes of energy saving, consumption reduction, environmental protection and the like to improve the efficiency of the device. The propylene ammoxidation method has the advantages of easily obtained raw materials, simple process, stable operation, convenient product refining, low product cost and the like.

In the four-effect evaporation unit in the existing domestic acrylonitrile production device, a gas-phase product separated by an evaporator contains a large amount of polymers due to liquid foam carried by high flow velocity, so that a two-effect heat exchanger, a three-effect heat exchanger and a four-effect heat exchanger are easy to block, the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger need to be cleaned once every 3-6 months, and when the heat exchanger is cleaned, the four-effect evaporation unit stops operating, so that the long-period stable operation of the device is influenced.

Disclosure of Invention

The invention aims to provide a four-effect evaporator for preparing acrylonitrile, which solves the problem of frequent maintenance.

In order to realize the aim, the invention provides a four-effect evaporator for preparing acrylonitrile, which comprises a first-effect evaporator, a second-effect evaporator, a third-effect evaporator and a four-effect evaporator which are sequentially connected in series;

the bottom of the first-effect evaporator is provided with a first-effect heat exchanger for circulating heat exchange of a solution at the bottom of the first-effect evaporator, the bottom of the second-effect evaporator is provided with a second-effect heat exchanger for circulating heat exchange of the solution at the bottom of the second-effect evaporator, the bottom of the third-effect evaporator is provided with a third-effect heat exchanger for circulating heat exchange of the solution at the bottom of the third-effect evaporator, and the bottom of the fourth-effect evaporator is provided with a fourth-effect heat;

the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger are floating head heat exchangers.

According to one aspect of the invention, wire mesh defoamers are respectively arranged inside one ends of the first-effect evaporator, the second-effect evaporator, the third-effect evaporator and the fourth-effect evaporator, which are adjacent to the top end socket.

According to one aspect of the invention, the distance h between the upper end of the wire mesh demister and the connecting position of the top seal head and the evaporator meets the following requirements: h is less than 800 mm.

According to one aspect of the invention, the distance h between the upper end of the wire mesh demister and the connecting position of the top seal head and the evaporator meets the following requirements: h is more than or equal to 200mm and less than 800 mm.

According to one aspect of the invention, the distance h between the upper end of the wire mesh demister and the connecting position of the top seal head and the evaporator meets the following requirements: h is more than or equal to 300mm and less than or equal to 700 mm.

According to one aspect of the invention, the distance h between the upper end of the wire mesh demister and the connecting position of the top seal head and the evaporator meets the following requirements: h is more than or equal to 400mm and less than or equal to 600 mm.

According to one aspect of the invention, the end of the four-effect evaporator adjacent to the top head is also internally provided with a lift cap tray.

According to one aspect of the invention, the lift cap tray is located below the wire mesh demister.

According to one aspect of the invention, the distance L between the lift cap tray and the connection location of the top head and the four-effect evaporator is such that: l is less than or equal to 1500 mm.

According to one aspect of the invention, the distance L between the lift cap tray and the connection location of the top head and the four-effect evaporator is such that: l is more than or equal to 800mm and less than 1500 mm.

According to one aspect of the invention, the distance L between the lift cap tray and the connection location of the top head and the four-effect evaporator is such that: l is more than or equal to 850mm and less than or equal to 1300 mm.

According to one aspect of the invention, the distance L between the lift cap tray and the connection location of the top head and the four-effect evaporator is such that: l is more than or equal to 900mm and less than or equal to 1100 mm.

According to one aspect of the invention, the lower side of the lift cap tray is further provided with a weep head.

According to one aspect of the invention, the weep head is a curved tube in the shape of a hook, one end of which is in communication with a weep opening on the lift cap tray and the other end of which is a free end that extends in a curved manner towards the lift cap tray.

According to the scheme of the invention, the floating head type heat exchanger is adopted, so that the outer wall of the heat exchanger can be cleaned more thoroughly after the heat exchanger tube bundle is drawn out. Particularly, the device prevents the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger from being blocked by polymer adhesion in the operation process of the four-effect evaporator of the acrylonitrile production device, and ensures the normal operation of the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger.

According to one scheme of the invention, the liquid foam entrained in a vapor phase in an evaporator can be effectively intercepted by arranging the wire mesh demister or the gas lifting cap tray, so that the polymer entering a downstream heat exchanger is reduced. The measure can effectively improve the operation time of the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger, and reduce the maintenance frequency of the on-line heat exchanger, thereby reducing the occurrence of unstable production operation caused by the maintenance of the heat exchanger.

Drawings

FIG. 1 schematically shows a block diagram of a four-effect evaporator for the production of acrylonitrile according to one embodiment of the present invention;

FIG. 2 is a schematic representation of a wire mesh demister installation configuration according to an embodiment of the present invention;

figure 3 schematically illustrates a lift cap tray installation configuration according to one embodiment of the present invention.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship that is based on the orientation or positional relationship shown in the associated drawings, which is for convenience and simplicity of description only, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, the above-described terms should not be construed as limiting the present invention.

The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.

As shown in fig. 1, according to one embodiment of the present invention, the four-effect evaporator for producing acrylonitrile of the present invention comprises a one-effect evaporator 11, a two-effect evaporator 12, a three-effect evaporator 13 and a four-effect evaporator 14, which are sequentially arranged in series. In this embodiment, the bottom of the first-effect evaporator 11 is provided with a first-effect heat exchanger 111 for circulating heat exchange of the solution at the bottom thereof, the bottom of the second-effect evaporator 12 is provided with a second-effect heat exchanger 121 for circulating heat exchange of the solution at the bottom thereof, the bottom of the third-effect evaporator 13 is provided with a third-effect heat exchanger 131 for circulating heat exchange of the solution at the bottom thereof, and the bottom of the fourth-effect evaporator 14 is provided with a fourth-effect heat exchanger 141 for circulating heat exchange of the solution at the bottom thereof.

As shown in fig. 1, according to one embodiment of the present invention, a first pipeline 112 connecting the first effect evaporator 11 and a first transfer pump 113 is arranged at the bottom of the first effect evaporator 11, the first transfer pump 113 and the first effect heat exchanger 111 are connected with a second pipeline 114, and the kettle liquid passing through the first effect heat exchanger 111 is returned back to the evaporator from the side line of the first effect evaporator 11. External low-pressure steam is input into the first-effect heat exchanger 111 through the third pipeline 117, exchanges heat with kettle liquid flowing through, and then is conveyed to the normal-pressure steam condensate tank. The upper part of the first-effect evaporator 11 is input into the recycling kettle liquid through a fourth pipeline 118.

As shown in FIG. 1, according to one embodiment of the present invention, the bottom of the second effect evaporator 12 is provided with a fifth pipeline 122 connecting the second effect evaporator 12 with a second transfer pump 123, the second transfer pump 123 is connected with the second effect heat exchanger 121 with a sixth pipeline 124, and the kettle liquid passing through the second effect heat exchanger 121 is recirculated from the side of the second effect evaporator 12 to the evaporator. A seventh pipeline 115 is led out of the first pipeline 112 to send part of the kettle liquid in the first pipeline 112 to the upper part of the second-effect evaporator 12. An eighth pipeline 116 is led out from the top of the first-effect evaporator 11 and communicated with the second-effect heat exchanger 121, so that the material flow output from the top of the first-effect evaporator 11 exchanges heat with the kettle liquid in the second-effect heat exchanger 121 and then is sent to the low-pressure steam condensate tank.

As shown in fig. 1, according to an embodiment of the present invention, a ninth pipeline 132 connecting the triple-effect evaporator 13 and a third transfer pump 133 is provided at the bottom of the triple-effect evaporator 13, the third transfer pump 133 and the triple-effect heat exchanger 131 are connected with a tenth pipeline 134, and the kettle liquid passing through the triple-effect heat exchanger 131 is recirculated from the side of the triple-effect evaporator 13 to the evaporator. An eleventh pipeline 125 is led out of the fifth pipeline 122 to send part of the kettle liquid in the fifth pipeline 122 to the upper part of the three-effect evaporator 13. A twelfth pipeline 126 is led out from the top of the second-effect evaporator 12 and communicated with the three-effect heat exchanger 131, so that the material flow output from the top of the second-effect evaporator 12 exchanges heat with the kettle liquid in the three-effect heat exchanger 131 and is sent to the low-pressure steam condensate tank.

As shown in fig. 1, according to an embodiment of the present invention, a thirteenth pipeline 142 connecting the four-effect evaporator 14 and a fourth transfer pump 143 is provided at the bottom of the four-effect evaporator 14, the fourth transfer pump 143 and the four-effect heat exchanger 141 are connected to a fourteenth pipeline 144, and the residue passing through the four-effect heat exchanger 141 is recirculated from the side of the four-effect evaporator 14 to the evaporator. A fifteenth pipe 135 is led out from the ninth pipe 132 to send part of the bottom liquid in the ninth pipe 132 to the upper part of the four-effect evaporator 14. And a sixteenth pipeline 136 is led out from the top of the three-effect evaporator 13 and communicated with the four-effect heat exchanger 141, so that the material flow output from the top of the three-effect evaporator 13 exchanges heat with the kettle liquid in the four-effect heat exchanger 141 and is sent to the low-pressure steam condensate tank. A seventeenth pipeline 145 is led out from the thirteenth pipeline 142 to convey part of the kettle liquid to the subsequent working section, and an eighteenth pipeline 146 is led out from the top of the four-effect evaporator 14 to convey the material flow led out from the top of the four-effect evaporator 14 to the subsequent working section for treatment.

According to one embodiment of the present invention, the two-effect heat exchanger 121, the three-effect heat exchanger 131, and the four-effect heat exchanger 141 are floating head heat exchangers. In the present embodiment, the two-effect heat exchanger 121, the three-effect heat exchanger 131, and the four-effect heat exchanger 141 may be a hook-and-loop floating head heat exchanger or a removable floating head heat exchanger. Through adopting floating head heat exchanger, can be convenient for the heat exchanger tube bank take out the back, more thorough to the washing of heat exchanger outer wall. Particularly, the device prevents the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger from being blocked by polymer adhesion in the operation process of the four-effect evaporator of the acrylonitrile production device, and ensures the normal operation of the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger.

Referring to fig. 1 and 2, according to an embodiment of the present invention, wire mesh defoamers 15 are respectively disposed inside one ends of the first effect evaporator 11, the second effect evaporator 12, the third effect evaporator 13 and the fourth effect evaporator 14 adjacent to the top head. By arranging the wire mesh demister 15, liquid foam entrained in the vapor phase in the evaporator can be effectively intercepted, thereby reducing polymer entering a downstream heat exchanger. The measure can effectively improve the operation time of the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger, and reduce the maintenance frequency of the on-line heat exchanger, thereby reducing the occurrence of unstable production operation caused by the maintenance of the heat exchanger.

Referring to fig. 1 and 2, according to one embodiment of the present invention, the distance h between the upper end of the wire mesh demister 15 and the connecting position of the top head and the evaporator satisfies: h is less than or equal to 800 mm. Through the arrangement, the wire mesh demister 15 has enough distance to the top seal head, so that a small amount of foam can be effectively prevented from being delivered to the heat exchanger through the top seal head pipeline, and the long-time stable operation of the heat exchanger is further ensured.

Referring to fig. 1 and 2, according to one embodiment of the present invention, the distance h between the upper end of the wire mesh demister 15 and the connecting position of the top head and the evaporator satisfies: h is more than or equal to 200mm and less than 800 mm. Through the arrangement, the wire mesh demister 15 has enough distance to the top seal head, so that a small amount of foam can be effectively prevented from being delivered to the heat exchanger through the top seal head pipeline, and the long-time stable operation of the heat exchanger is further ensured.

Referring to fig. 1 and 2, according to one embodiment of the present invention, the distance h between the upper end of the wire mesh demister 15 and the connecting position of the top head and the evaporator satisfies: h is more than or equal to 300mm and less than or equal to 700 mm. Through the arrangement, the wire mesh demister 15 has enough distance from the top end socket, so that a small amount of foam can be effectively prevented from being delivered to the heat exchanger through the top end socket pipeline, and the long-time stable operation of the heat exchanger is further ensured.

Referring to fig. 1 and 2, according to one embodiment of the present invention, the distance h between the upper end of the wire mesh demister 15 and the connecting position of the top head and the evaporator satisfies: h is more than or equal to 400mm and less than or equal to 600 mm. Through the arrangement, the wire mesh demister 15 has enough distance from the top end socket, so that a small amount of foam can be effectively prevented from being delivered to the heat exchanger through the top end socket pipeline, and the long-time stable operation of the heat exchanger is further ensured.

Referring to fig. 1 and 3, a lift cap tray 16 is also provided inside the end of the four-effect evaporator 14 adjacent the head, according to one embodiment of the present invention. In this embodiment, the plurality of gas-lifting caps permeable to gas are arranged on the gas-lifting cap tray 16 in an array manner, so that it is effectively ensured that the foam in the liquid is blocked by the gas-lifting caps, the foam is prevented from being sent to the heat exchanger, and the normal operation of the heat exchanger is ensured. In this embodiment, a liquid leakage head 161 is further disposed on the side of the lift cap tray 16 away from the lift cap, and the liquid leakage head 161 is a curved pipe having a hook shape, one end of which is communicated with the liquid leakage port on the lift cap tray 16, and the other end of which is a free end extending toward the lift cap tray 16. Through the arrangement, the liquid staying on the gas cap tray 16 can be timely discharged to the lower side, the normal work of the gas cap is prevented from being influenced by excessive liquid, the accumulation of foam on the gas cap tray 16 is also avoided, and particularly when the wire mesh demister 15 and the gas cap tray 16 are arranged simultaneously, the reduction of the foam amount flowing into the wire mesh demister 15 is facilitated, and the foam sent to the heat exchanger is further reduced. In addition, the liquid leakage head 161 is a hook-shaped bent pipe, so that the liquid below can be effectively prevented from directly flowing to the upper part of the lift cap tray 16 through the liquid leakage head 161, and the normal operation of the lift cap tray 16 is ensured.

Referring to fig. 1 and 2, according to one embodiment of the present invention, when both the wire mesh demister 15 and the lift cap tray 16 are provided in the evaporator, the lift cap tray 16 is located below the wire mesh demister 15.

According to one embodiment of the invention, the distance L between the riser cap tray 16 and the location where the head and four-effect evaporator 14 are connected is such that: l is less than or equal to 1500 mm. Through the arrangement, the lift cap tower tray 16 and the top seal head can have enough distance, a small amount of foam can be effectively prevented from being sent to the heat exchanger through the top seal head pipeline, and the long-time stable operation of the heat exchanger is further ensured.

According to one embodiment of the invention, the distance L between the riser cap tray 16 and the location where the head and four-effect evaporator 14 are connected is such that: l is more than or equal to 800mm and less than 1500 mm. Through the arrangement, the lift cap tower tray 16 and the top seal head can have enough distance, a small amount of foam can be effectively prevented from being sent to the heat exchanger through the top seal head pipeline, and the long-time stable operation of the heat exchanger is further ensured.

According to one embodiment of the invention, the distance L between the riser cap tray 16 and the location where the head and four-effect evaporator 14 are connected is such that: l is more than or equal to 850mm and less than or equal to 1300 mm. Through the arrangement, the lift cap tower tray 16 and the top seal head can have enough distance, a small amount of foam can be effectively prevented from being sent to the heat exchanger through the top seal head pipeline, and the long-time stable operation of the heat exchanger is further ensured.

According to one embodiment of the invention, the distance L between the riser cap tray 16 and the location where the head and four-effect evaporator 14 are connected is such that: l is more than or equal to 900mm and less than or equal to 1100 mm. Through the arrangement, the lift cap tower tray 16 and the top seal head can have enough distance, a small amount of foam can be effectively prevented from being sent to the heat exchanger through the top seal head pipeline, and the long-time stable operation of the heat exchanger is further ensured.

The foregoing is merely exemplary of particular aspects of the present invention and devices and structures not specifically described herein are understood to be those of ordinary skill in the art and are intended to be implemented in such conventional ways.

The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.