CN114249657A - Method for continuously preparing DCB - Google Patents
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- CN114249657A CN114249657A CN202111494554.8A CN202111494554A CN114249657A CN 114249657 A CN114249657 A CN 114249657A CN 202111494554 A CN202111494554 A CN 202111494554A CN 114249657 A CN114249657 A CN 114249657A
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Abstract
The invention provides a method for continuously preparing DCB, which is realized by a circulating device, wherein the circulating device comprises a reaction kettle and a dispersion pump which are sequentially communicated, and the dispersion pump can continuously transfer reaction liquid in the reaction kettle so as to disperse and crush viscous materials generated in the transposition reaction process, thereby strengthening the mixing effect, quickening the reaction and having better selectivity and stability of the reaction; meanwhile, the preparation method can continuously carry out transposition reaction, improves the efficiency of preparing DCB and effectively reduces energy consumption.
Description
Technical Field
The invention relates to the technical field of organic pigment synthesis, in particular to a method for continuously preparing DCB.
Background
3, 3' -dichlorobenzidine, abbreviated as DCB, is an important intermediate for producing a yellow organic pigment of the dichlorobenzidine series, and the yellow series pigment produced by using the same as a raw material accounts for about 25% of the total yield of the organic pigment, and the organic pigment is widely applied to coloring of ink, paint, rubber and plastics, production of pigment printing slurry, pigment dyeing slurry and the like.
The preparation of DCB takes ortho-nitrochlorobenzene as a raw material, obtains a toluene solution of DCB reducing substances through hydrogenation reaction, and then carries out transposition reaction with hydrochloric acid to obtain DCB mixed slurry.
In industry, the equipment used for transposition reaction is mainly an intermittent glass lining reaction kettle, and it is worth one thing that when the transposition reaction is carried out, the generated DCB hydrochloride is difficult to dissolve in toluene and slightly soluble in high-concentration hydrochloric acid and water, so that after the reaction is carried out to a certain degree, the viscosity of the reaction liquid is gradually increased, and along with crystallization, the reaction is not uniform, the reaction time is too long, and by-products are increased, thereby influencing the conversion rate and selectivity of the reaction. Meanwhile, in order to achieve the production target, a plurality of reaction kettles are carried out simultaneously, and the power consumption of equipment is also large.
Disclosure of Invention
One purpose of the invention is to provide a method for continuously preparing DCB, which can disperse and crush viscous materials generated in the process of transposition reaction, accelerate the reaction and have better selectivity and stability; the preparation method can continuously carry out transposition reaction, improves the efficiency of preparing DCB and effectively reduces energy consumption.
In order to achieve the above objects of the present invention, the present invention provides a method for continuously preparing DCB by a circulation device comprising a reaction vessel and a dispersion pump which are connected in sequence, each dispersion pump being provided with at least two regulating valves for circularly transferring a reaction solution in the reaction vessel and controlling a volume of the reaction solution in the reaction vessel, respectively.
Specifically, the circulation device includes: the device comprises a first-stage reaction kettle, a first-stage dispersion pump, a second-stage reaction kettle, a second-stage dispersion pump and a reaction liquid receiving tank, wherein the first-stage dispersion pump is arranged between the first-stage reaction kettle and the second-stage reaction kettle and is used for circularly transferring reaction liquid in the first-stage reaction kettle, controlling the volume of the reaction liquid in the first-stage reaction kettle and transferring part of the reaction liquid in the first-stage reaction kettle into the second-stage reaction kettle; the second-stage dispersion pump is arranged between the second-stage reaction kettle and the reaction liquid receiving tank and used for circularly transferring the reaction liquid in the second-stage reaction kettle, controlling the volume of the reaction liquid in the second-stage reaction kettle and transferring part of the reaction liquid in the second-stage reaction kettle into the reaction liquid receiving tank.
Wherein, a primary circulation regulating valve and a primary transfer regulating valve for controlling the communication state are respectively arranged between the primary dispersion pump and the primary reaction kettle and between the primary dispersion pump and the secondary reaction kettle; and a secondary circulation regulating valve and a secondary transfer regulating valve for controlling the communication state are respectively arranged between the secondary dispersion pump and the secondary reaction kettle and between the secondary dispersion pump and the reaction liquid receiving tank.
When worth integratively, above governing valve is automatic regulating valve, can the automatic control flow of material. Preferably, the first-stage reaction kettle and the second-stage reaction kettle are both provided with a radar liquid level meter which monitors the volume of liquid in the reaction kettle in real time and feeds information back to the corresponding automatic regulating valve so as to control the flow of materials and the volume of the materials of the first-stage reaction kettle and the second-stage reaction kettle.
Furthermore, a DCB reducing substance toluene solution input pump and a hydrochloric acid solution input pump are arranged at the feed end of the first-stage reaction kettle, and each input pump can input liquid into the reaction kettle according to a preset flow.
Furthermore, the first-stage dispersion pump and the second-stage dispersion pump are special viscous material dispersion pumps and are titanium material pumps or fluoroplastic pumps.
Further, the liquid volumes of the first-stage reaction kettle and the second-stage reaction kettle are 8-10m3。
Specifically, the method for preparing the DCB by the above circulation device comprises the steps of:
the method comprises the following steps: adding a certain amount of 15-25% hydrochloric acid into the first-stage reaction kettle, starting stirring, opening a first-stage circulation regulating valve, starting a first-stage dispersion pump, and keeping a first-stage transfer regulating valve closed;
step two: injecting a DCB reducing matter toluene solution and 30-35% hydrochloric acid into the first-stage reaction kettle at the same time according to a preset flow;
step three: monitoring the liquid level in the first-stage reaction kettle, opening a first-stage transfer regulating valve when the liquid level in the first-stage reaction kettle reaches a first preset liquid level, wherein the first preset liquid level is 60-80%, and controlling the liquid level in the first-stage reaction kettle (11) to be kept at 60-80%;
step four: monitoring the liquid level in the secondary reaction kettle, opening a secondary circulation regulating valve and starting a secondary dispersion pump when the liquid level in the secondary reaction kettle reaches a second preset liquid level, wherein the second preset liquid level is 10-20%, and the secondary transfer valve is kept closed;
step five: when the liquid level in the secondary reaction kettle reaches a first preset liquid level, a secondary transfer regulating valve is opened, the materials are conveyed to a reaction receiving tank, and the volume of the liquid in the secondary reaction kettle is controlled to be kept at 60-80% of the total volume.
Further, in the first step, 2m of the reaction solution is added into the first-stage reaction kettle in advance320% hydrochloric acid solution.
Further, in the step one, the flow rate of the liquid circularly transferred from the primary dispersion pump to the primary reaction kettle is 50-100m3/h。
Further, in the second step, the flow rate of the DCB reducing substance toluene solution entering the first-stage reaction kettle is 800-1000kg/h, and the flow rate of the hydrochloric acid entering the first-stage reaction kettle is 950-1200 kg/h.
Further, in the second step, the mass ratio of 2, 2' -dichlorohydrazobenzene to toluene in the toluene solution of the DCB reduction product was (1-2): 1.
Further, in the second step, the temperature in the first-stage reaction kettle and the second-stage reaction kettle is controlled to be 30-35 ℃.
Further, in the fourth step, the flow rate of the liquid circularly transferred from the second-stage dispersion pump to the second-stage reaction kettle is 50-100m3/h。
The invention has the beneficial effects that:
1. the preparation method provided by the invention can realize continuous feeding and continuous discharging, the reaction is continuously carried out, the reaction time is short, the conversion rate is good, and the reaction selectivity and the stability are good.
2. The preparation method provided by the invention can continuously carry out transposition reaction, replaces a batch reaction mode, simplifies the process flow of DCB transposition reaction, and improves the efficiency of DCB preparation.
3. The preparation method provided by the invention has the advantages of small volume of the adopted reaction kettle, small quantity and low energy consumption.
4. The preparation method provided by the invention is carried out in a closed circulating system, prevents the toluene liquid from evaporating, and reduces the emission of organic pollutants.
Drawings
FIG. 1 is a process flow diagram for the preparation of DCB in accordance with the present invention.
Description of reference numerals:
11. a first-stage reaction kettle; 12. a second-stage reaction kettle; 21. a first-stage dispersion pump; 22. a secondary dispersion pump; 31. a reaction liquid receiving tank; 41. a hydrochloric acid input pump; 42. a DCB raw material input pump; 51. a primary circulation regulating valve; 52. a primary transfer regulating valve; 61. a secondary circulation regulating valve; 62. a secondary transfer regulating valve; 71. a primary radar level gauge; 72. a secondary radar level gauge; 81. a first-stage stirrer; 82. a secondary stirrer; 91. a primary temperature control unit; 92. and a secondary temperature control unit.
Detailed Description
In order that the above objects, features and advantages of the present invention will become more readily apparent, there will now be described in detail specific embodiments thereof with reference to the accompanying drawings, but it is to be understood that the description is only for the purpose of further illustrating the features and advantages of the present invention, and not for the purpose of limiting the invention as claimed.
The following detailed description of embodiments of the invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer", "front", "back", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that are conventionally arranged when the products of the present invention are used, and are used only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements to be referred to must have specific orientations, be constructed in specific orientations, and operate, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise specifically stated or limited, the terms "mounted," "disposed," "connected," and the like are used in a broad sense, and for example, "connected" may be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, and a communication between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The first embodiment is as follows:
in this embodiment, the DCB is prepared by a recycling apparatus, and as can be seen from the process flow diagram of fig. 1, the recycling apparatus for preparing DCB comprises: the system comprises a first-stage reaction kettle 11, a first-stage dispersion pump 21, a second-stage reaction kettle 12, a second-stage dispersion pump 22 and a reaction liquid receiving tank 31, wherein the first-stage reaction kettle 11 and the second-stage reaction kettle 12 are respectively provided with a first-stage radar liquid level meter 71, a second-stage radar liquid level meter 71, a first-stage stirrer 81, a second-stage stirrer 82, a first-stage temperature control unit 91 and a second-stage temperature control unit 92; the feeding end of the first-stage dispersion pump 21 is connected with the discharging end of the first-stage reaction kettle 11, and the discharging end of the first-stage dispersion pump 21 is connected with the feeding ends of the first-stage reaction kettle 11 and the second-stage reaction kettle 12; the feed end of second grade dispersion pump 22 is connected with the discharge end of second grade reation kettle 12, the discharge end of second grade dispersion pump 22 is connected with the feed end of second grade reation kettle 12 and reaction liquid receiving tank 31, wherein, be equipped with one-level circulation governing valve 51 and one-level transfer governing valve 52 on the pipeline between the discharge end intercommunication one-level reation kettle 11 of one-level dispersion pump 21 and the second grade reation kettle 12 respectively, be equipped with second grade circulation governing valve 61 and second grade transfer governing valve 62 on the official track between second grade reation kettle 12 of discharge end intercommunication of second grade dispersion pump 22 and the reaction liquid receiving tank 31 respectively.
Preferably, the first-stage circulation regulating valve 51, the first-stage transfer regulating valve 52, the second-stage circulation regulating valve 61 and the second-stage transfer regulating valve 62 are all automatic regulating valves, and when the radar liquid level meter monitors the volume of liquid in the reaction kettle in real time, information can be fed back to the corresponding automatic regulating valves to automatically control the flow of materials and the volume of the materials in the first-stage reaction kettle 11 and the second-stage reaction kettle 12.
Preferably, the primary temperature control unit 91 and the secondary temperature control unit 92 are both jacket layers disposed on the outer layers of the primary reaction kettle 11 and the secondary reaction kettle 12, and have a water inlet and a water outlet, preferably, the water inlet is disposed at the lower end of the reaction kettle, and the water outlet is disposed at the upper end of the reaction kettle, so that the cooling water can cool the reaction kettle well.
Preferably, the first-stage dispersion pump 21 and the second-stage dispersion pump 22 are both special viscous material dispersion pumps, and are titanium material pumps or fluoroplastic pumps.
Further, a DCB raw material input pump 42 and a hydrochloric acid input pump 41 are provided at the feed end of the primary reaction tank 11, and preferably, the input pumps are metering pumps capable of inputting liquid into the primary reaction tank 11 according to a preset flow rate.
In this embodiment, the translocation reaction of DCB is performed by the above-mentioned circulation device, and a continuous reaction is used, and specifically, the method for preparing DCB comprises the following steps:
the method comprises the following steps: to 8m32m is added into a first-stage reaction kettle 113Starting the primary stirrer 81, opening the primary circulation regulating valve 51, starting the primary dispersion pump 21, and controlling the flow of the liquid injected into the primary reaction kettle 11 by the primary dispersion pump 21 to be 100m3/h；
Step two: simultaneously starting a DCB raw material input pump 42 and a hydrochloric acid input pump 41, simultaneously injecting a DCB reducing substance toluene solution and a 31% hydrochloric acid solution into the first-stage reaction kettle 11, and controlling the temperature in the first-stage reaction kettle 11 to be kept at 30-35 ℃ through a first-stage temperature control unit 91;
wherein the injection speed of the DCB reducing substance toluene solution is 800kg/h, and the injection speed of the hydrochloric acid solution is 1000 kg/h. And the mass ratio of the 2, 2' -dichlorohydrazobenzene to the toluene in the DCB reduced matter toluene solution is 2: 1.
Step three: monitoring the volume of the liquid in the first-stage reaction kettle 11 by a first-stage radar liquid level meter 71, and opening 8m communicated with the first-stage dispersion pump 21 when the volume of the reaction liquid reaches 70 percent3A primary transfer regulating valve 52 of the secondary reaction kettle 12 transfers part of the reaction liquid into the secondary reaction kettle 12, and regulates a primary circulation regulating valve 51 and the primary transfer regulating valve 52 to control the volume of the reaction liquid in the primary reaction kettle 11 to be kept at 60-80%; and the temperature in the secondary reaction kettle 12 is controlled to be kept at 30-35 ℃ by a secondary temperature control unit 92.
Step four: the volume of the liquid in the secondary reaction kettle 12 is monitored by a secondary radar liquid level meter 72, when the volume reaches 15%, the secondary circulation regulating valve 61 is opened, the secondary dispersion pump 22 is started, and the flow of the liquid injected into the secondary reaction kettle 12 by the secondary dispersion pump 22 is controlled to be 100m3/h；
Step five: when the volume of the liquid in the secondary reaction kettle 12 reaches 70%, the secondary dispersion pump 22 is opened to communicate with the secondary transfer regulating valve 62 of the reaction liquid receiving tank 31, the DCB slurry is received in the reaction receiving tank 31, and simultaneously, the secondary circulation regulating valve 61 and the secondary transfer regulating valve 62 are regulated to control the volume of the reaction liquid in the secondary reaction kettle 12 to be 60-80%.
During the continuous shift reaction, samples were taken from the line of the reaction liquid receiver tank 31 at different times and analyzed by high performance liquid chromatography, and the analysis data are shown in Table 1:
from the data, the main content of DCB in the slurry is DCB by sampling and analyzing at different times, and a small amount of unreacted raw material 2, 2-dichlorohydrazobenzene and partial DCB byproduct are found, so that the content of DCB, the content of residual raw material and the content of byproduct in the obtained DCB slurry are stable in different times in the process of continuously performing transposition reaction.
Example two:
in this example, the apparatus for preparing DCB was the same as the recycling apparatus used in the first embodiment, and a continuous reaction was performed, and specifically, the method for preparing DCB included the following steps:
the method comprises the following steps: to 8m32m is added into a first-stage reaction kettle 113Starting the primary stirrer 81, opening the primary circulation regulating valve 51, starting the primary dispersion pump 21, and controlling the flow of the liquid injected into the primary reaction kettle 11 by the primary dispersion pump 21 to be 100m3/h；
Step two: simultaneously starting a DCB raw material input pump 42 and a hydrochloric acid input pump 41, simultaneously injecting a DCB reducing substance toluene solution and a 31% hydrochloric acid solution into the first-stage reaction kettle 11, and controlling the temperature in the reaction kettle to be kept at 30-35 ℃ through a first-stage temperature control unit 91;
wherein, the injection speed of the DCB reducing substance toluene solution is 1000kg/h, and the injection speed of the hydrochloric acid solution is 950 kg/h. And the mass ratio of the 2, 2' -dichlorohydrazobenzene to the toluene in the DCB reduced product toluene solution is 1.5: 1.
Step three: monitoring the volume of the liquid in the first-stage reaction kettle 11 by a first-stage radar liquid level meter 71, and opening 8m communicated with the first-stage dispersion pump 21 when the volume of the reaction liquid reaches 70 percent3The first-stage transfer regulating valve 52 of the second-stage reaction kettle 12 transfers part of the reaction liquid into the second-stage reaction kettle 12, and regulates the first-stage circulation regulating valve 51 and the first-stage transfer regulating valve 52 to control the volume of the reaction liquid in the first-stage reaction kettle 11 to be kept at 60-80%, and controls the temperature in the second-stage reaction kettle 12 to be kept at 30-35 ℃ through the second-stage temperature control unit 92.
Step four: the volume of the liquid in the secondary reaction kettle 12 is monitored by a secondary radar liquid level meter 72, and when the volume reaches 15%, the secondary circulation regulating valve 61 is opened and the secondary circulation regulating valve is openedA secondary dispersion pump 22, and controlling the flow rate of the liquid injected into the secondary reaction kettle 12 by the secondary dispersion pump 22 to be 100m3/h；
Step five: when the volume of the liquid in the secondary reaction kettle 12 reaches 70%, the secondary dispersion pump 22 is opened to communicate with the secondary transfer regulating valve 62 of the reaction liquid receiving tank 31, the DCB slurry is received in the reaction receiving tank, and simultaneously, the secondary circulation regulating valve 61 and the secondary transfer regulating valve 62 are regulated to control the volume of the reaction liquid in the secondary reaction kettle 12 to be 60-80%.
During the continuous shift reaction, samples were taken from the line of the reaction liquid receiver tank 31 at different times and analyzed by high performance liquid chromatography, and the analysis data are shown in Table 2:
from the data, the main content of DCB in the slurry is DCB by sampling and analyzing at different times, and a small amount of unreacted raw material 2, 2-dichlorohydrazobenzene and partial DCB byproduct are found, so that the content of DCB, the content of residual raw material and the content of byproduct in the obtained DCB slurry are stable in different times in the process of continuously performing transposition reaction.
In order to fully illustrate the manner of continuous translocation reaction provided by the present invention, which enables the DCB to be produced well, the present invention was also compared with the manner of batch reaction.
Comparative example:
in the comparative example, the apparatus for preparing DCB was a reaction vessel equipped with a stirring device, a temperature control device and a hydrochloric acid dropping device, and the method for preparing DCB by the reaction vessel was:
to 8m35000kg of toluene solution of a DCB reducing substance is injected into the reaction kettle, wherein, 2, 2' -dichlorohydrido coupleThe mass ratio of the nitrobenzene to the toluene is 1.5:1, starting a stirrer, dropwise adding 6250kg of 31% hydrochloric acid solution into the reaction kettle, controlling the reaction temperature to be kept at 30-35 ℃ after dropwise adding of hydrochloric acid within 10 hours, and reacting for 30 hours after adding of the hydrochloric acid to reach the reaction end point.
Sampling the slurry in the reaction kettle for high performance liquid chromatography analysis, wherein the specific experimental data are as follows:
from the above experimental data, it can be known that, when the traditional batch reaction mode is adopted to prepare DCB, the reaction conversion rate is slightly lower than that of the continuous reaction mode, the unreacted raw materials are slightly higher than that of the continuous reaction mode, the generated DCB byproduct liquid is slightly higher than that of the continuous reaction mode, and the reaction end point can be reached in a longer time. In order to achieve the production target, a plurality of reaction kettles are required to be carried out simultaneously, the number of the reaction kettles is large, the energy consumption is high, and the generation time and cost are increased.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same, and although the present invention is described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or some or all of the technical features may be equivalently replaced, and the modifications or the replacements may not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A process for the continuous preparation of DCB, characterized in that it is carried out by means of a circulation device, in which,
the circulation device includes: a first-stage reaction kettle (11), a first-stage dispersion pump (21), a second-stage reaction kettle (12), a second-stage dispersion pump (22) and a reaction liquid receiving tank (31);
the liquid inlet end of the first-level dispersion pump (21) is communicated with the liquid outlet end of the first-level reaction kettle (11), the liquid outlet end of the first-level dispersion pump (21) is communicated with the liquid inlet ends of the first-level reaction kettle (11) and the second-level reaction kettle (12),
the communication pipelines of the primary dispersion pump (21), the primary reaction kettle (11) and the secondary reaction kettle (12) are respectively provided with a primary circulation regulating valve (51) and a primary transfer regulating valve (52) for controlling the communication state;
the liquid inlet end of the secondary dispersion pump (22) is communicated with the liquid outlet end of the secondary reaction kettle (12), the liquid outlet end of the secondary dispersion pump (22) is communicated with the liquid inlet ends of the secondary reaction kettle (12) and the reaction liquid receiving tank (31),
a secondary circulation regulating valve (61) and a secondary transfer regulating valve (62) are respectively arranged on the communication pipelines of the secondary dispersion pump (22), the secondary reaction kettle (12) and the reaction liquid receiving tank (31);
the method comprises the following steps:
the method comprises the following steps: adding a certain amount of 15-25% hydrochloric acid into the first-stage reaction kettle (11), starting stirring, opening a first-stage circulation regulating valve (51), starting a first-stage dispersion pump (21), and keeping a first-stage transfer regulating valve (52) closed;
step two: injecting a DCB reducing substance toluene solution and 30-35% hydrochloric acid into the first-stage reaction kettle (11) according to a preset flow rate;
step three: monitoring the liquid level in the first-stage reaction kettle (11), and when the liquid level in the first-stage reaction kettle (11) reaches a first preset liquid level, opening a first-stage transfer regulating valve (52), wherein the first preset liquid level is 60-80% of the total volume of the reaction kettle, and controlling the liquid level in the first-stage reaction kettle (11) to be kept at 60-80% of the total volume;
step four: monitoring the liquid level in the secondary reaction kettle (12), opening a secondary circulation regulating valve (61) when the liquid level in the secondary reaction kettle (12) reaches a second preset liquid level, wherein the second preset liquid level is 10-20% of the total volume of the reaction kettle, starting a secondary dispersion pump (22), and keeping a secondary transfer regulating valve (62) closed;
step five: when the liquid level in the secondary reaction kettle (12) reaches a first preset liquid level, a secondary transfer regulating valve (62) is opened, materials are conveyed to the reaction receiving tank (31), and the volume of the liquid in the secondary reaction kettle (12) is controlled to be kept at 60-80% of the total volume.
2. The method for continuously preparing DCB according to claim 1, wherein in the first step, the flow rate of the primary dispersion pump (21) is 50-100m3/h。
3. The continuous DCB production method as claimed in claim 1, wherein in the first step, 2m of the catalyst is previously charged into the first reaction vessel (11)320% hydrochloric acid solution.
4. The method as claimed in claim 1, wherein in the second step, the flow rate of the DCB reducing agent toluene solution entering the first-stage reaction vessel (11) is 800-1000kg/h, and the flow rate of the hydrochloric acid entering the first-stage reaction vessel (11) is 950-1200 kg/h.
5. The method according to claim 1, wherein in step two, the mass ratio of 2, 2' -dichlorohydrazobenzene to toluene in the solution of DCB-reducing substance in toluene is (1-2): 1.
6. The continuous DCB production method according to claim 1, wherein the temperature in the primary reaction tank (11) and the secondary reaction tank (12) is controlled to be maintained at 30-35 ℃.
7. The continuous DCB production process as claimed in claim 1, wherein in step four, the flow rate of the secondary dispersion pump (22) is 50-100m3/h。
8. The continuous DCB production process of claim 1, wherein said primary reaction vessel(s) (C: (C))11) The total volume of the liquid can be 8-10m3(ii) a The total volume of the secondary reaction kettle (12) capable of containing liquid is 8-10m3。
9. The method for continuously preparing DCB according to claim 1, wherein said circulating means further comprises a hydrochloric acid input pump (41) and a DCB raw material input pump (42), said hydrochloric acid input pump (41) and said DCB raw material input pump (42) being in communication with a feeding end of said primary reaction tank (11).
10. The method for continuously preparing DCB according to claim 1, wherein said primary circulation regulating valve (51), said primary transfer regulating valve (52), said secondary circulation regulating valve (61), and said secondary transfer regulating valve (62) are all automatic regulating valves, and said primary reaction tank (11) and said secondary reaction tank (12) are respectively provided with a primary radar level gauge (71) and a secondary radar level gauge (72); the primary radar liquid level meter (71) monitors the liquid level in the primary reaction kettle (11) and is suitable for controlling the primary circulation regulating valve (51) and the primary transfer regulating valve (52); the secondary radar level gauge (72) monitors the liquid level in the secondary reaction vessel (12) and is adapted to control the secondary circulation regulating valve (61) and the secondary transfer regulating valve (62).
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2021
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