CN212941540U

CN212941540U - A system for nitrotoluene melt crystallization

Info

Publication number: CN212941540U
Application number: CN202020591419.XU
Authority: CN
Inventors: 鲍辉; 刘强; 张天鹏; 何强; 黄培合; 张俊; 王天杨
Original assignee: Hubei Dongfang Chemical Industry Co ltd
Current assignee: Hubei Dongfang Chemical Industry Co ltd
Priority date: 2020-04-20
Filing date: 2020-04-20
Publication date: 2021-04-13
Anticipated expiration: 2030-04-20

Abstract

The utility model discloses a system for be used for nitrotoluene melt crystallization, including crystallizer, finished product groove, mother liquid groove and sweat groove, the entrance point intercommunication of crystallizer has the raw materials input pipeline to the exit end of crystallizer is respectively through the inside intercommunication in pipeline and finished product groove, mother liquid groove, sweat groove, the utility model relates to a chemical production technical field. This a system and method for nitrotoluene melt crystallization sets up discharge valve through crystallizer from circulating water pipeline top and is used for the gaseous emission in the self-circulating water system, arranges respectively to mother liquor groove, sweat cistern and finished product groove according to crystallizer discharge material purity, this processing system easy operation, strong to the process controllability of crystallization and sweating, and crystallization and sweating process are even stable, have greatly improved production yield and production efficiency, be applicable to the melt crystallization technology of trades such as petrochemical and medicine, effectively improve production yield and production efficiency, optimize operating environment.

Description

A system for nitrotoluene melt crystallization

Technical Field

The utility model relates to a chemical production technical field specifically is a system for nitrotoluene melt crystallization.

Background

Nitrotoluene is a colorless or light yellow crystal, nitrotoluene is usually produced by a melt crystallization mode, rectification is a process widely applied to organic matter separation, but the separation difficulty of a traditional mode (negative pressure rectification separation) is high, a rectification tower with high separation efficiency is needed, products meeting market requirements are obtained through a high reflux ratio, the quality is unstable, the energy consumption is high, the cost for further improving the quality is high, the cost is high, high-quality competitive benefits are difficult to obtain, the melt crystallization process is adopted for supplement, the separation difficulty is reduced, the product quality is improved, and the process and operation defects of the negative pressure rectification method can be made up to the maximum extent.

However, the melt crystallization process conventionally used has the following disadvantages: in the crystallization process, the water temperature at a water inlet end is lower, the water temperature at a water outlet end is higher, and the temperature difference between the water in and out is larger, (the temperature difference between the inlet and the outlet of the crystallizer reaches more than 2-3 ℃), so that the water temperatures of different areas in the crystallizer are different, and the crystallization and sweating are uneven in the two processes, so that the production yield is lower; secondly, the crystallizer directly introduces external circulating water to cool the crystallizer, so that the temperature of the cooling water cannot be adjusted, the temperature is lower, and as the temperature of the circulating water is far lower than the solidification point of the material, when the circulating water is introduced into the crystallizer, the material close to the heat exchange tube is rapidly crystallized, but the material with high solidification point (higher purity) is crystallized firstly, and the material with low solidification point is crystallized later; when sweating, the materials with low solidifying point close to the heat exchange tube are melted firstly, and countless cavities are formed around the heat exchange tube, so that the heat exchange efficiency is gradually reduced in the sweating process due to low gas heat exchange efficiency.

SUMMERY OF THE UTILITY MODEL

Technical problem to be solved

To the not enough of prior art, the utility model provides a system for nitrotoluene melt crystallization has solved that traditional melt crystallization's mode exists: the water temperatures of different areas in the crystallizer are different, and the crystallization and sweating processes are both uneven, so that the production yield is low and the heat exchange efficiency in the sweating process is gradually reduced.

(II) technical scheme

In order to achieve the above purpose, the utility model discloses a following technical scheme realizes: a system for nitrotoluene melt crystallization comprises a crystallizer, a finished product groove, a mother liquid groove and a sweat groove, wherein a raw material input pipeline is communicated with an inlet end of the crystallizer, an outlet end of the crystallizer is respectively communicated with the interiors of the finished product groove, the mother liquid groove and the sweat groove through pipelines, an outlet end of the crystallizer is communicated with a circulating pump through a pipeline, an inlet end of the circulating pump is communicated with a circulating water feeding pipeline, a circulating water inlet valve group is arranged inside the circulating water feeding pipeline, an outlet end of the circulating pump is communicated with a circulating water returning pipeline, a circulating water outlet valve is arranged inside the circulating water returning pipeline, an outlet end of the circulating pump is communicated with a heat exchanger, an outlet end of the heat exchanger is communicated with a condensed water pipeline, a drain valve group is arranged inside the condensed water pipeline, and an inlet end of the heat exchanger, and a steam valve group is arranged inside the steam pipeline.

Preferably, the heat exchanger, the steam pipeline and the condensed water pipeline form a self-circulation system, and the heat source adopts low-pressure steam, and the pressure is selected to be 0.1-0.8MPa, preferably 0.2-0.5 MPa.

Preferably, when the inlet pipeline of the circulating pump is installed, the two pipelines are both connected to the inlet pipeline of the circulating pump, and the distance between the joints of the two pipelines is 0.1-3m, preferably 0.3-1 m.

Preferably, the highest position of the circulating water feeding pipeline and the circulating water returning pipeline is 0.1-3m, preferably 0.2-0.6m higher than the top end of the circulating pump pipeline when the circulating water feeding pipeline and the circulating water returning pipeline are installed.

Preferably, the outlet end of the heat exchanger is provided with an exhaust valve, and the exhaust valve is used for exhausting gas in the system.

Preferably, the outlet end of the heat exchanger is provided with a thermometer, and the thermometer is used for monitoring the temperature of the inlet water of the crystallizer.

Preferably, the outlet end of the crystallizer is provided with a sampling valve, and the sampling valve is used for detecting the production condition of the crystallizer.

(III) advantageous effects

The utility model provides a system for be used for nitrotoluene melt crystallization. Compared with the prior art, the method has the following beneficial effects:

the working method of the system for nitrotoluene melt crystallization comprises the steps that S1, the melt crystallization system mainly comprises a crystallizer, a heat exchanger, a circulating pump, a regulating valve group, a thermometer, an exhaust valve, a mother liquor tank, a sweat liquor tank and a finished product tank, wherein the heat exchanger, a steam pipeline and a condensed water pipeline form a self-circulation system; s2, heating the self-circulation system through a heat exchanger by using low-pressure steam, controlling the temperature of a steam outlet through a steam valve set, directly introducing circulating water into the heat exchanger for heat exchange through the self-circulation system, and controlling the temperature through a circulating water inlet valve set; s3, the circulating water inlet pipeline is higher than the top end of the crystallizer self-circulating water pipeline and then is connected to the water outlet pipeline of the crystallizer downwards, and the circulating water return pipeline is led upwards to the crystallizer self-circulating water pipeline from a position higher than the circulating water inlet and then is connected to the circulating water return pipeline downwards so as to ensure that the self-circulating water pipeline is full; s4, in the heating process, excess water is discharged to a circulating water return system due to the fact that the water in the self-circulation system expands when heated, and in the cooling process, the water in the self-circulation system shrinks due to cooling, and insufficient water is automatically supplemented by the circulating water return system; s5, an exhaust valve is arranged at the top end of a self-circulation water pipeline of the crystallizer and used for discharging gas in a self-circulation water system, and the gas is discharged into a mother liquid tank, a sweat liquid tank and a finished product tank respectively according to the purity of the material discharged by the crystallizer.

Drawings

FIG. 1 is a system flow chart of the present invention for nitrotoluene melt crystallization.

In the figure, 1-a crystallizer, 2-a finished product tank, 3-a mother liquid tank, 4-a sweat liquid tank, 5-a sampling valve, 6-a circulating pump, 7-a heat exchanger, 8-a hydrophobic valve group, 9-a steam valve group, 10-a thermometer, 11-a circulating water inlet valve group, 12-a circulating water outlet valve and 13-an exhaust valve.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1, an embodiment of the present invention provides a technical solution: a system for nitrotoluene melt crystallization comprises a crystallizer 1, a finished product tank 2, a mother liquid tank 3 and a sweat tank 4, wherein a sampling valve 5 is arranged at the outlet end of the crystallizer 1, the sampling valve 5 is used for detecting the production condition of the crystallizer, a raw material input pipeline is communicated with the inlet end of the crystallizer 1, the outlet end of the crystallizer 1 is respectively communicated with the interiors of the finished product tank 2, the mother liquid tank 3 and the sweat tank 4 through pipelines, a circulating pump 6 is communicated with the outlet end of the crystallizer 1 through a pipeline, an axial flow pump is selected as the circulating pump 6, the energy consumption is minimum under the condition of meeting the process requirement according to the characteristics of large flow and low lift of the axial flow pump, two pipelines are connected to an inlet pipeline of the circulating pump when circulating water enters and exits from the inlet pipeline of the circulating pump 6, the distance between the interfaces of the two pipelines is 0.1-3m, preferably 0.3-1m, and the highest position of a circulating water feeding pipeline and a circulating water, preferably 0.2-0.6m, the inlet end of the circulating pump 6 is communicated with a circulating water feeding pipeline, a circulating water inlet valve group 11 is arranged inside the circulating water feeding pipeline, the outlet end of the circulating pump 6 is communicated with a circulating water return pipeline, a circulating water outlet valve 12 is arranged inside the circulating water return pipeline, the outlet end of the circulating pump 6 is communicated with a heat exchanger 7, the heat exchanger 7 is used for improving the uniformity of the water inlet temperature of the crystallizer and ensuring the crystallization efficiency, the outlet end of the heat exchanger 7 is provided with an exhaust valve 13, the exhaust valve 13 is used for exhausting gas in the system and reducing the influence of the gas on the self-circulating system, the outlet end of the heat exchanger 7 is provided with a thermometer 10, the thermometer 10 is used for monitoring the water inlet temperature of the crystallizer 1 and preventing the influence of overhigh and overlow temperature on the crystallization process, the heat source adopts low-pressure steam, the pressure is selected to be 0.1-0.8MPa, preferably 0.2-0.5MPa, the outlet end of the heat exchanger 7 is communicated with a condensation water pipeline, a drain valve group 8 is arranged in the condensation water pipeline, the inlet end of the heat exchanger 7 is communicated with a steam pipeline, a steam valve group 9 is arranged in the steam pipeline, and the content which is not described in detail in the specification belongs to the prior art which is known by the technicians in the field.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides a system for nitrotoluene melt crystallization, includes crystallizer (1), finished product groove (2), mother liquor groove (3) and sweat cistern (4), the entrance point intercommunication of crystallizer (1) has raw materials input pipeline to the exit end of crystallizer (1) is respectively through the inside intercommunication of pipeline and finished product groove (2), mother liquor groove (3), sweat cistern (4), its characterized in that: the exit end of crystallizer (1) is passed through the pipeline intercommunication and is had circulating pump (6), the entrance point intercommunication of circulating pump (6) has the circulation water supply line to the inside of circulation water supply line is provided with circulating water inlet valve group (11), the exit end intercommunication of circulating pump (6) has the circulation return water pipeline to the inside of circulation return water pipeline is provided with circulation outlet valve (12), the exit end intercommunication of circulating pump (6) has heat exchanger (7), the exit end intercommunication of heat exchanger (7) has the condensation water pipeline to the inside of condensation water pipeline is provided with hydrophobic valve group (8), the entrance point intercommunication of heat exchanger (7) has the steam pipeline to the inside of steam pipeline is provided with steam valve group (9).

2. The system for nitrotoluene melt crystallization according to claim 1, wherein: the heat exchanger (7), the steam pipeline and the condensed water pipeline form a self-circulation system, and the heat source adopts low-pressure steam and is selected to be 0.1-0.8 MPa.

3. The system for nitrotoluene melt crystallization according to claim 1, wherein: when the inlet pipeline of the circulating pump (6) is installed, the two pipelines are connected to the inlet pipeline of the circulating pump, and the distance between the interfaces of the two pipelines is 0.1-3 m.

4. The system for nitrotoluene melt crystallization according to claim 1, wherein: the highest position of the circulating water feeding pipeline and the circulating water returning pipeline is 0.1-3m higher than the top end of the circulating pump (6) pipeline when the circulating water feeding pipeline and the circulating water returning pipeline are installed.

5. The system for nitrotoluene melt crystallization according to claim 1, wherein: an outlet end of the heat exchanger (7) is provided with an exhaust valve (13), and the exhaust valve (13) is used for exhausting gas in the system.

6. The system for nitrotoluene melt crystallization according to claim 1, wherein: the outlet end of the heat exchanger (7) is provided with a thermometer (10), and the thermometer (10) is used for monitoring the temperature of the inlet water of the crystallizer (1).

7. The system for nitrotoluene melt crystallization according to claim 1, wherein: the outlet end of the crystallizer (1) is provided with a sampling valve (5), and the sampling valve (5) is used for detecting the production condition of the crystallizer.