阅读说明：本技术 一种聚酰胺用精盐连续浓缩工艺 (Continuous concentration process of refined salt for polyamide ) 是由 赵风轩 梁法锋 钱江 陈发挥 余爱平 于 2020-07-27 设计创作，主要内容包括：一种聚酰胺用精盐连续浓缩工艺,采用的浓缩系统包括精盐预热器、精盐蒸发器、精盐汽提塔,精盐汽提塔位于精盐预热器的下方,位于精盐蒸发器的上方,浓缩过程为：精盐溶液经精盐预热器预热,由进料管、汇集管进入精盐蒸发器蒸发,得到汽态物料,经物料管进入精盐汽提塔中,其中的大分子组分被截留,小分子组分以及水蒸汽由蒸汽管进入精盐预热器,大分子组分经循环管,在重力作用下,部分返回至精盐蒸发器,形成循环,部分经浓缩物料排料管连续排出,得到浓缩后的精盐,固含量为60-90wt％。本发明工艺简单、操作方便,用于对聚酰胺用盐溶液进行连续浓缩得到精盐,精盐浓缩成本低,且可有效避免出现结晶、结垢现象,是生产高品质聚酰胺的保障。(The utility model provides a polyamide is with continuous concentrated technology of refined salt, the concentrated system of adoption includes refined salt pre-heater, refined salt evaporimeter, refined salt stripper, and the refined salt stripper is located the below of refined salt pre-heater, is located the top of refined salt evaporimeter, and the concentration process is: the refined salt solution is preheated by a refined salt preheater, enters a refined salt evaporator through a feeding pipe and a collecting pipe to be evaporated to obtain a vaporous material, enters a refined salt stripping tower through a material pipe, macromolecular components are intercepted, micromolecular components and water vapor enter the refined salt preheater through a steam pipe, part of the macromolecular components return to the refined salt evaporator through a circulating pipe under the action of gravity to form circulation, and part of the macromolecular components are continuously discharged through a concentrated material discharging pipe to obtain concentrated refined salt, wherein the solid content of the concentrated refined salt is 60-90 wt%. The method has simple process and convenient operation, is used for continuously concentrating the salt solution of the polyamide to obtain the refined salt, has low concentrated salt cost, can effectively avoid the phenomena of crystallization and scaling, and is a guarantee for producing high-quality polyamide.)

1. A continuous concentration process of refined salt for polyamide is characterized in that: the following concentration system was used for the concentration,

the concentration system comprises a refined salt preheater (1), a refined salt evaporator (2) and a refined salt stripping tower (3), the refined salt stripping tower (3) is positioned below the refined salt preheater (1) and above the refined salt evaporator (2),

the bottom of the refined salt evaporator (2) is provided with a collecting pipe (4) extending downwards, the hollow lower part of the refined salt stripping tower (3) is communicated with the hollow upper part of the refined salt evaporator (2) through a material pipe (5), the bottom of the refined salt stripping tower (3) is connected with the collecting pipe (5) through a circulating pipe (6), the circulating pipe (6) is also provided with a concentrated material discharging pipe (7) and is provided with a first valve (a) for controlling the opening and the closing,

the material outlet of the refined salt preheater (1) is connected with the collecting pipe (4) through a feeding pipe (8) and is positioned above the downstream end of the circulating pipe (6), the heat medium inlet of the refined salt preheater (1) is connected with the top of the refined salt stripping tower (3) through a steam pipe (9),

the concentration step is as follows:

1) the refined salt solution formed by mixing dicarboxylic acid and organic diamine is preheated by a refined salt preheater and enters a refined salt evaporator through a feeding pipe and a collecting pipe;

2) the heat medium used by the refined salt evaporator is saturated process steam, the pressure is 0.5-1.5MPaG, the refined salt solution is evaporated in the refined salt evaporator to obtain a vaporous material, the pressure is 0.1-0.5MPa, and the vaporous material enters a refined salt stripping tower through a material pipe;

3) the macromolecule components in the steam-state materials in the refined salt stripping tower are intercepted and are collected to the lower hollow part of the refined salt stripping tower, and the micromolecule components and water vapor in the macromolecule components enter a refined salt preheater through a steam pipe to be used as a heat medium;

4) and part of macromolecular components gathered at the hollow lower part in the refined salt stripping tower return to the refined salt evaporator through a circulating pipe under the action of gravity to form circulation, and part of macromolecular components are continuously discharged through a concentrated material discharge pipe to obtain concentrated refined salt, wherein the solid content is 60-90 wt%.

2. The continuous concentration process of refined salt for polyamide according to claim 1, characterized in that: the collecting pipe (4) is connected with a process steam pipe (10), and a second valve (b) is arranged on the process steam pipe (10).

3. The continuous concentration process of refined salt for polyamide according to claim 1, characterized in that: and an inner tower part (31) is arranged at the inner hollow upper part of the refined salt stripping tower (3).

4. The continuous concentration process of refined salt for polyamide according to claim 3, characterized in that: the tower internal member (31) is a plate type tower internal member.

5. The continuous concentration process of refined salt for polyamide according to claim 4, characterized in that: the shell pass of the refined salt preheater (1) is a heat medium channel, and the shell pass of the refined salt preheater (1) is connected with the hollow upper part of the refined salt stripping tower (3) through a condensate return pipe (11).

6. The continuous concentration process of refined salt for polyamide according to claim 5, characterized in that: the condensate return pipe (11) is provided with a condensate extraction pipe (12) and a third valve (c) for controlling opening and closing.

7. The continuous concentration process of refined salt for polyamide according to claim 1, characterized in that: the vertical height of the collecting pipe (4) is 1.0-10 m.

8. The continuous concentration process of refined salt for polyamide according to claim 1 or 7, characterized in that: and a heating jacket is arranged on the outer wall of the collecting pipe (4).

9. The continuous concentration process of refined salt for polyamide according to claim 1, characterized in that: the dicarboxylic acid in the step 1) is any one or a mixture of succinic acid, glutaric acid and adipic acid, and the organic diamine is any one or a mixture of butanediamine, pentanediamine and hexanediamine.

10. The continuous concentration process of refined salt for polyamide according to claim 1, characterized in that: step 1) preheating at the temperature of 100-130 ℃.

Technical Field

The invention relates to the field of chemical industry, in particular to a continuous concentration process of refined salt for polyamide.

Background

The polyamide is mainly used for synthetic fibers, has the most outstanding advantages that the wear resistance is higher than that of all other fibers, is 10 times higher than that of cotton and 20 times higher than that of wool, and the wear resistance can be greatly improved by slightly adding some polyamide fibers into the blended fabric; when the stretch is extended to 3-6%, the elastic recovery rate can reach 100%; can withstand ten thousand times of bending without breaking. The strength of the polyamide fiber is 1-2 times higher than that of cotton, 4-5 times higher than that of wool, and 3 times higher than that of viscose fiber. However, polyamide fibers have poor heat resistance and light resistance and poor retention properties, and the resulting garments are not as stiff as polyester.

Polyamide is commonly known as Nylon (Nylon), and is called Polyamide in English, which refers to a high polymer with a main chain section containing a polar amide group (-CO-NH-), is a resin developed for fibers by DuPont in the United states at first, and is industrialized in 1939. The polyamide can be prepared by ring-opening polymerization of lactam, or polycondensation of diamine and diacid. Polyamide was initially used as a raw material for fiber production, and later, PA has been widely used as an engineering plastic in industry because of its advantages of toughness, wear resistance, self-lubrication, wide temperature range, etc. The PA can be widely used for replacing copper and nonferrous metals to manufacture mechanical, chemical and electrical parts, such as a fuel pump gear of a diesel engine, a water pump, a high-pressure sealing ring, an oil delivery pipe and the like. In the 50 th of the 20 th century, injection molded products are developed and produced to replace metals to meet the requirements of light weight and cost reduction of downstream industrial products. The PA has good comprehensive properties including mechanical property, heat resistance, abrasion resistance, chemical resistance and self-lubricity, has low friction coefficient and certain flame retardance, is easy to process, is suitable for being filled with glass fiber and other fillers for reinforcing modification, improves the performance and expands the application range.

The concentration of the salt solution obtained by salifying the dibasic acid and the dibasic acid is usually below 50 wt%, and the salt solution is used for further processing reaction to obtain a polyamide product after being concentrated. At present, the concentration is usually carried out in a heating and stirring mode, the concentration process is intermittent concentration, time is long, the concentration is difficult to control, and in addition, the phenomena of crystallization and scaling caused by overlarge concentration are easy to occur, so that the quality of the obtained product is seriously reduced.

Disclosure of Invention

The invention aims to provide a continuous concentration process of refined salt for polyamide, which is simple in process and convenient to operate, is used for continuously concentrating salt solution for polyamide to obtain refined salt, is low in refined salt concentration cost, can effectively avoid crystallization and scaling phenomena, and is a guarantee for producing high-quality polyamide.

The technical scheme of the invention is as follows: a continuous concentration process of refined salt for polyamide adopts a following concentration system for concentration, wherein the concentration system comprises a refined salt preheater, a refined salt evaporator and a refined salt stripping tower, the refined salt stripping tower is positioned below the refined salt preheater and above the refined salt evaporator, the bottom of the refined salt evaporator is provided with a collecting pipe extending downwards, the hollow lower part of the refined salt stripping tower is communicated with the hollow upper part of the refined salt evaporator through a material pipe, the bottom of the refined salt stripping tower is connected with the collecting pipe through a circulating pipe, the circulating pipe is also provided with a concentrated material discharge pipe and is provided with a first valve for controlling opening and closing, the material outlet of the refined salt preheater is connected with the collecting pipe through a feeding pipe and is positioned above the downstream end of the circulating pipe, and the heat medium inlet of the refined salt preheater is connected with the top of the refined salt stripping tower through a steam pipe,

the concentration step is as follows:

1) the refined salt solution formed by mixing dicarboxylic acid and organic diamine is preheated by a refined salt preheater and enters a refined salt evaporator through a feeding pipe and a collecting pipe;

2) the heat medium used by the refined salt evaporator is saturated process steam, the pressure is 0.5-1.5MPaG, the refined salt solution is evaporated in the refined salt evaporator to obtain a vaporous material, the pressure is 0.1-0.5MPa, and the vaporous material enters a refined salt stripping tower through a material pipe;

3) the macromolecule components in the steam-state materials in the refined salt stripping tower are intercepted and are collected to the lower hollow part of the refined salt stripping tower, and the micromolecule components and water vapor in the macromolecule components enter a refined salt preheater through a steam pipe to be used as a heat medium;

4) and part of macromolecular components gathered at the hollow lower part in the refined salt stripping tower return to the refined salt evaporator through a circulating pipe under the action of gravity to form circulation, and part of macromolecular components are continuously discharged through a concentrated material discharge pipe to obtain concentrated refined salt, wherein the solid content is 60-90 wt%.

The collecting pipe is connected with a process steam pipe, and a second valve is arranged on the process steam pipe.

The inner hollow upper part of the refined salt stripping tower is provided with a tower inner part.

The tower internals are plate tower internals.

The shell side of the refined salt preheater is a heat medium channel, and is connected with the inner hollow upper part of the refined salt stripping tower through a condensate return pipe.

The condensate return pipe is provided with a condensate extraction pipe and a third valve for controlling opening and closing.

The vertical height of the header is 1.0-10 m.

And a heating jacket is arranged on the outer wall of the collecting pipe.

The dicarboxylic acid in the step 1) is any one or a mixture of succinic acid, glutaric acid and adipic acid, and the organic diamine is any one or a mixture of butanediamine, pentanediamine and hexanediamine.

Step 1) preheating at the temperature of 100-130 ℃.

The proportion of macromolecular components discharged in the step 4) is less than or equal to 0.1 percent;

adopt above-mentioned technical scheme to have following beneficial effect:

1. the invention relates to a continuous concentration process of refined salt for polyamide, wherein a used concentration system comprises a refined salt preheater, a refined salt evaporator and a refined salt stripping tower, and the refined salt stripping tower is positioned below the refined salt preheater and above the refined salt evaporator. The device comprises a refined salt preheater, a refined salt evaporator, a refined salt stripper and a refined salt stripper, wherein the refined salt preheater is used for preheating refined salt for polyamide, the refined salt evaporator is used for vaporizing the preheated refined salt for polyamide, and the refined salt stripper is used for intercepting the refined salt for polyamide and stripping and discharging small-molecular impurities in the refined salt. The bottom of the refined salt evaporator is provided with a collecting pipe extending downwards, the lower hollow part of the refined salt stripping tower is communicated with the upper hollow part of the refined salt evaporator through a material pipe, the polyamide entering the refined salt evaporator is vaporized by refined salt under the heating condition and enters the refined salt stripping tower through the material pipe, and after mass transfer, macromolecules are intercepted and collected in the refined salt stripping tower to obtain concentrated polyamide refined salt. The tower bottom of refined salt strip tower links to each other with the collection pipe through the circulating pipe, still is equipped with concentrated material row material pipe on this circulating pipe, and sets up first valve control switching, and it is great to collect the concentrated refined salt density in refined salt strip tower inside, under the action of gravity, returns the refined salt evaporimeter along the circulating pipe, carries out the evaporative concentration in succession, and simultaneously, the material row of accessible concentrate material pipe is arranged in succession and is expected, obtains the refined salt after the concentration, satisfies enterprise's actual demand. The material export of refined salt pre-heater pass through the inlet pipe with the collection pipe links to each other, and the polyamide refined salt after preheating in the inlet pipe continuously gets into the concentrated refined salt effect that the refined salt evaporimeter carries out evaporative concentration under gravity and circulating pipe return, does not need extra power device to accomplish the feeding promptly, still can effectively reduce the concentrated cost of refined salt, and realizes concentrating in succession, satisfies enterprise's actual demand. The heat medium inlet of the refined salt preheater is connected with the top of the refined salt stripping tower through a steam pipe, the vaporous micromolecules and the water vapor discharged from the refined salt stripping tower are used as preheating media to preheat the polyamide refined salt passing through the refined salt preheater, the utilization efficiency of the steam generated by the concentration of the refined salt is effectively improved, and the heat energy consumption of the refined salt evaporator is reduced.

2. The collecting pipe is connected with a process steam pipe, the second valve is arranged on the process steam pipe, the process steam enters the collecting pipe by opening the second valve, the circulating power of the refined salt evaporator can be effectively improved, the problem of shutdown maintenance caused by refined salt crystallization and scaling is avoided, the operation period of the concentration system can be effectively prolonged, the system maintenance frequency is reduced, and the cost and the product quality are influenced, and compared with the traditional interval concentration device (process), the energy conservation (steam consumption) is at least more than 30%.

3. The interior empty upper portion of refined salt stripper is equipped with tower internals, preferred adoption plate tower internals, the vapour-state material that refined salt evaporimeter generated gets into refined salt stripper back, through the mass transfer, macromolecule wherein is effectively intercepted, guarantee refined salt product yield, the organic matter emission of sewage has still been reduced, micromolecule steam and steam get into the refined salt preheater and regard as the hot medium, both make full use of concentrated used heat, high viscosity macromolecule gets into the refined salt preheater has effectively been avoided in addition, guarantee the long-time normal operating of refined salt preheater.

4. The shell side of the refined salt preheater is a heat medium channel, and is connected with the inner hollow upper part of the refined salt stripping tower through a condensate return pipe. The refined salt preheater exchanges heat with refined salt solution, and the condensed liquid is used as reflux liquid to complete the steam stripping function.

5. The vertical height of the collecting pipe is 1.0-10m, certain bubbles can be generated in the collecting pipe due to the addition of low-concentration refined salt liquid or the heating of a jacket, the circulation amount is greatly increased due to the action of the bubbles, the longer the collecting pipe is, the more sufficient the circulation power is, the larger the liquid amount is provided for the refined salt evaporator, the lower the steam pressure of the shell pass of the refined salt evaporator is, and the conditions of energy conservation and difficult occurrence of tube array blockage due to crystallization are represented.

6. The concentrated refined salt with a certain proportion is controlled to return to the refined salt evaporator to ensure that the refined salt evaporator does not crystallize and works normally, if the returned concentrated refined salt is too low, the conditions of local crystallization and gradual crystallization can occur, and further the situation is worsened to influence the production; too high a return of concentrated refined salt is difficult to design.

The following further description is made with reference to the accompanying drawings and detailed description.

Drawings

FIG. 1 is a schematic diagram of the connection of the concentration system of the present invention.

In the attached drawing, 1 is a refined salt preheater, 2 is a refined salt evaporator, 3 is a refined salt stripping tower, 31 is a tower internal part, 4 is a collecting pipe, 5 is a material pipe, 6 is a circulating pipe, 7 is a concentrated material discharging pipe, 8 is a feeding pipe, 9 is a steam pipe, 10 is a process steam pipe, 11 is a condensate return pipe, 12 is a condensate extracting pipe, a is a first valve, b is a second valve, and c is a third valve.

Detailed Description

In the invention, the device without a specific structure is generally conventional equipment in the chemical field, and the device without a specific installation and connection mode is generally conventional in the chemical field or is installed and connected according to the guidance suggestion of a manufacturer.