Production system of 3-nitrophthalic acid

Abstract

The utility model discloses a production system of 3-nitrophthalic acid, and belongs to the technical field of chemical intermediate production equipment. The production system of the 3-nitrophthalic acid comprises a reaction kettle, a gas cylinder, a first raw material tank, a second raw material tank, a first heat exchanger, a second heat exchanger, a third heat exchanger, a condensation tank and a filter. According to the production system, three heat exchangers are arranged to conduct three-stage heat exchange on reaction products, reaction waste heat is fully utilized to preheat reaction raw materials, meanwhile, effective cooling of the products is achieved, in addition, baffle plates are arranged in the heat exchangers, heat exchange elements are arranged on heat exchange pipes in the incident flow direction, and the heat exchange efficiency is improved. The heat exchange effect between products and raw materials is further enhanced, the heat exchange efficiency is improved, and the raw material temperature is effectively reduced. A certain height difference is set among the heat exchanger, the reaction kettle and the raw material tank, and the material is conveyed by utilizing the height among equipment, so that the use number of conveying pumps is reduced, and the energy consumption is further reduced. The system is simple in structure and easy to operate, can realize full cooling and separation of the product without using a large number of cold sources, and is a 3-nitrophthalic acid production system suitable for industrialization.

Description

TECHNICAL FIELD

[0001] The present application relates to a production system of 3-nitrophthalic acid, belonging to the technical field of chemical intermediate production equipment. BACKGROUND

[0002] 3-nitrophthalic acid is an important organic intermediate, mainly used for synthesizing chemical materials, dyes, crop protection agents and other substances. 3-nitrophthalic acid is usually prepared by oxidizing 3-nitrophthalene using different oxidation methods. At present, the main oxidizing agents include strong oxidizing agents such as nitric acid and potassium permanganate, as well as clean oxidizing agents such as air and oxygen. The oxidation method using nitric acid and potassium permanganate has relatively severe conditions, which generates a large amount of by-products, which is not conducive to the subsequent separation and purification of the product, and also causes serious corrosion to the equipment. The oxidation of 3-nitrophthalene to prepare 3-nitrophthalic acid using air or oxygen is usually carried out under the catalysis of a certain catalyst. This method is more suitable for industrial production because of its relatively mild conditions and environmental friendliness, and therefore is widely studied.

[0003] With the gradual maturity of the process of preparing 3-nitrophthalic acid by oxidizing 3-nitrophthalene using air or oxygen, new demands for production systems suitable for this method are put forward. In addition, this method usually reacts at a temperature of 100-200 ℃, and after the reaction is completed, the product is precipitated by cooling, and finally the target product is obtained by filtration. A large amount of cold energy is consumed during the cooling process of the product. How to effectively reduce the temperature to make the product completely precipitate while saving energy is a new problem for the production system. SUMMARY

[0004] Based on the deficiencies in the prior art, the present application provides a production system of 3-nitrophthalic acid. The three-stage heat exchange realizes sufficient cooling of the raw materials, and achieves the purpose of clean production, separation and purification of 3-nitrophthalic acid.

[0005] The technical scheme adopted by the present application is: a production system of 3-nitrophthalic acid comprises a reaction kettle, a gas cylinder, a first raw material tank, a second raw material tank, a first heat exchanger, a second heat exchanger, a third heat exchanger, a condensation tank and a filter, the gas outlet of the gas cylinder is connected to the gas inlet of the reaction kettle through the tube side of the first heat exchanger, the discharge outlet of the first raw material tank is connected to one of the feed inlets of the reaction kettle through the tube side of the second heat exchanger, the second raw material tank is connected to the other feed inlet of the reaction kettle through the tube side of the third heat exchanger, the discharge outlet of the reaction kettle is sequentially connected to the feed inlet of the condensation tank through the shell side of the first heat exchanger, the shell side of the second heat exchanger and the shell side of the third heat exchanger, and the discharge outlet of the condensation tank is connected to the feed inlet of the filter.

[0006] The shell side of the second heat exchanger is provided with a plurality of baffles, and a plurality of heat transfer enhancement elements are arranged on the heat exchange pipes of the second heat exchanger.

[0007] The reinforced heat exchange element comprises a spiral blade which is rotatably fixed on the heat exchange pipe.

[0008] The first raw material tank and the second raw material tank are arranged above the second heat exchanger and the third heat exchanger, the second heat exchanger and the third heat exchanger are arranged above the reaction kettle, the first heat exchanger is arranged below the reaction kettle, and the condensing tank is arranged below the third heat exchanger.

[0009] The production system of 3-nitrophthalic acid comprises a reaction kettle, a gas cylinder, a first raw material tank, a second raw material tank, a first heat exchanger, a second heat exchanger, a third heat exchanger, a condensing tank and a filter, a gas outlet of the gas cylinder is connected to a gas inlet of the reaction kettle through a tube side of the first heat exchanger, a discharge outlet of the first raw material tank is connected to one feeding inlet of the reaction kettle through a tube side of the second heat exchanger, the second raw material tank is connected to another feeding inlet of the reaction kettle through a tube side of the third heat exchanger, a discharge outlet of the reaction kettle is sequentially connected to a feeding inlet of the condensing tank through a shell side of the first heat exchanger, a shell side of the second heat exchanger and a shell side of the third heat exchanger, and a discharge outlet of the condensing tank is connected to a feeding inlet of the filter. The production system is provided with three heat exchangers to perform three-stage heat exchange on reaction products, reaction waste heat is fully utilized to preheat reaction raw materials, effective cooling of the products is realized, in addition, baffles are arranged in the heat exchangers, heat exchange elements are arranged on the heat exchange pipes in the direction of the flow, the heat exchange effect between the products and the raw materials is further strengthened, the heat exchange efficiency is improved, and the temperature of the raw materials is effectively reduced. A certain height difference is arranged between the heat exchanger, the reaction kettle and the raw material tank, the height difference between the equipment is utilized to convey the materials, the number of the conveying pumps is reduced, and the energy consumption is further saved. The system has simple structure and is easy to operate, can realize sufficient cooling and separation of the products without using a large amount of cold source, and is a production system of 3-nitrophthalic acid suitable for industrialization. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of the production system of 3-nitrophthalic acid.

[0011] Figure 2 It is Figure 1 It is an internal structure diagram of the heat exchanger.

[0012] In the figure, 1 is a reaction kettle, 2 is a first heat exchanger, 2a is a first conveying pump, 3 is a second heat exchanger, 3a is a baffle, 3b is a reinforced heat exchange element, 4 is a third heat exchanger, 5 is a gas cylinder, 6 is a first raw material tank, 7 is a second raw material tank, 8 is a condensing tank, 8a is a second conveying pump, and 9 is a filter. DETAILED DESCRIPTION

[0013] The application will be further described in detail in combination with the following embodiments, but the application is not limited to the following embodiments.

[0014] Figure 1 A structural schematic diagram of a 3-nitrophthalic acid production system is shown, which includes a reaction kettle 1, a gas cylinder 5, a first raw material tank 6, a second raw material tank 7, a first heat exchanger 2, a second heat exchanger 3, a third heat exchanger 4, a condensing tank 8 and a filter 9. The gas outlet of the gas cylinder 5 is connected to the gas inlet of the reaction kettle 1 through the tube side of the first heat exchanger 2. The outlet of the first raw material tank 6 is connected to one of the inlets of the reaction kettle 1 through the tube side of the second heat exchanger 3. The second raw material tank 7 is connected to the other inlet of the reaction kettle 1 through the tube side of the third heat exchanger 4. The outlet of the reaction kettle 1 is connected to the inlet of the condensing tank 8 in sequence through the shell side of the first heat exchanger 2, the shell side of the second heat exchanger 3 and the shell side of the third heat exchanger 4. The outlet of the condensing tank 8 is connected to the inlet of the filter 9 through the second conveying pump 8a.

[0015] The shell side of the second heat exchanger 3 is provided with multiple baffles 3a. The heat exchange tubes of the second heat exchanger 3 are provided with multiple enhanced heat exchange elements 3b. The enhanced heat exchange elements 3b on different heat exchange tubes are arranged in a staggered manner. The enhanced heat exchange element 3b comprises a spiral blade and a fixing rod. The spiral blade is rotatably fixed on the heat exchange tube through the fixing rod. The enhanced heat exchange element 3b is arranged in the direction of the incoming flow of the material. The spiral blade rotates under the action of the flow rate of the material itself, so as to reduce the flow rate of the material and enhance the heat exchange. The first heat exchanger 2 and the third heat exchanger 4 have the same structure as the second heat exchanger 3. The first raw material tank 6 and the second raw material tank 7 are arranged above the second heat exchanger 3 and the third heat exchanger 4. The second heat exchanger 3 and the third heat exchanger 4 are arranged above the reaction kettle 1. The first heat exchanger 2 is arranged below the reaction kettle 1. The condensing tank 8 is arranged below the third heat exchanger 4. The material flows in and out under the action of gravity through the height difference between the devices, so as to reduce the use of conveying pumps. The outlet of the shell side of the first heat exchanger 2 is connected to the inlet of the shell side of the second heat exchanger 3 through the first conveying pump 2a. The position of the second heat exchanger 3 is higher than that of the third heat exchanger 4. The height difference is conducive to the flow of the heat exchange fluid from the second heat exchanger 3 to the third heat exchanger 4.

[0016] The working process of the 3-nitrophthalic acid production system is as follows. The reaction product in the reaction kettle 1 flows into the shell side of the first heat exchanger 2, the second heat exchanger 3 and the third heat exchanger 4 in sequence, respectively exchanges heat with the oxygen or air in the gas cylinder 5, the raw material in the first raw material tank 6 and the raw material in the second raw material tank 7, and then flows into the condensing tank 8 for further cooling and precipitation. After the product is precipitated, it is filtered in the filter to obtain the target product. The oxygen or air in the gas cylinder 5, the raw material in the first raw material tank 6 and the raw material in the second raw material tank 7 are preheated by absorbing the heat of the product, and then enter the reaction kettle to synthesize new products. The heat exchange and reaction process is repeated.

[0017] The above merely expresses the preferred embodiments of the present application, which are described in more detail and in a more specific manner, but should not be understood as limiting the scope of the patent of the present application. It should be noted that, for those of ordinary skill in the art, several modifications, improvements and substitutions can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A production system of 3-nitrophthalic acid, comprising a reaction vessel (1), a gas cylinder (5), a first raw material tank (6), and a second raw material tank (7), characterized by, It also comprises a first heat exchanger (2), a second heat exchanger (3), a third heat exchanger (4), a condensing tank (8) and a filter (9), the gas outlet of the gas cylinder (5) is connected to the gas inlet of the reaction kettle (1) through the tube side of the first heat exchanger (2), the outlet of the first raw material tank (6) is connected to one of the inlets of the reaction kettle (1) through the tube side of the second heat exchanger (3), the second raw material tank (7) is connected to the other inlet of the reaction kettle (1) through the tube side of the third heat exchanger (4), and the outlet of the reaction kettle (1) is connected to the inlet of the condensing tank (8) in sequence through the shell side of the first heat exchanger (2), the shell side of the second heat exchanger (3) and the shell side of the third heat exchanger (4), and the outlet of the condensing tank (8) is connected to the inlet of the filter (9).

2. The production system according to claim 1, characterized in that, The shell side of the second heat exchanger (3) is provided with a plurality of baffles (3a), and the heat exchange pipe of the second heat exchanger (3) is provided with a plurality of enhanced heat exchange elements (3b).

3. The production system according to claim 2, characterized in that, The enhanced heat exchange element (3b) comprises a spiral blade which is rotatably fixed on the heat exchange pipe.

4. The production system according to claim 3, characterized in that The first raw material tank (6) and the second raw material tank (7) are arranged above the second heat exchanger (3) and the third heat exchanger (4), the second heat exchanger (3) and the third heat exchanger (4) are arranged above the reaction kettle (1), the first heat exchanger (2) is arranged below the reaction kettle (1), and the condensing tank (8) is arranged below the third heat exchanger (4).

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