CN-122017120-A - Brine alkali excess analysis method and analysis system

CN122017120ACN 122017120 ACN122017120 ACN 122017120ACN-122017120-A

Abstract

The invention relates to the technical field of chemical industry and discloses a brine alkali excess analysis method and an analysis system, wherein the analysis method comprises the steps of adopting a standard acid titration unit to titrate brine, and obtaining the alkali excess in the brine according to the standard acid volume consumed by titration to a target titration point; the target dropping point at least comprises a first dropping point with the pH value of 7.6-8.5, a second dropping point with the pH value of 3.9-4.5 and a third dropping point between the first dropping point and the second dropping point, and the titration speed U 3 from the third dropping point to the third dropping point is controlled to be larger than the titration speed from the first dropping point and/or the second dropping point. According to the invention, by setting a plurality of dropping points and controlling the titration speed in a sectionalized manner, the speed is reduced in a key end point area to improve the judgment precision, the speed is increased in a non-key interval to shorten the detection time, the excessive titration is avoided, the detection period is effectively compressed, and the detection precision and the efficiency are both realized.

Inventors

MEI JIAN
HUANG DONGMEI
CHEN KAI
LI XUEFENG
ZHAO XUEYAO
CHENG JIE
CHENG HAILIN
SONG YUPING

Assignees

万华化学(宁波)氯碱有限公司

Dates

Publication Date: 20260512
Application Date: 20260105

Claims (10)

1. A brine alkali excess analysis method is characterized by comprising the following steps: Titrating the brine by adopting a standard acid titration unit, and obtaining the over-alkali amount in the brine according to the standard acid volume consumed by titrating to a target titration point; the target dropping point at least comprises a first dropping point with the pH value of 7.6-8.5, a second dropping point with the pH value of 3.9-4.5 and a third dropping point between the first dropping point and the second dropping point; The titration speed U 3 to the third drop point is controlled to be greater than the titration speed to the first drop point and/or the second drop point.
2. The method for analyzing the brine over-alkali amount according to claim 1, wherein the target drop point further comprises an initial drop point with a pH value of 9.8-10.5, and the titration speed U Initially, the method comprises for titration to the initial drop point is controlled to be larger than the titration speed for titration to the first drop point and/or the second drop point; Preferably, the titration speed U Initially, the method comprises is controlled to be greater than the titration speed U 3 .
3. The method for analyzing the salt water alkali excess according to claim 1 or 2, wherein the next titration is carried out after the interval of time t Spacing of is set after each titration to a target titration point; Preferably, the interval setting time t Spacing of is 0.32-2 times of the titration time corresponding to the titration to one target titration point.
4. A method for analyzing the excess alkali of brine according to any one of claims 1 to 3, wherein, before starting the titration, if bubbles exist in the liquid storage pipeline of the standard acid titration unit, the standard acid titration unit is controlled to empty the bubbles first and then perform the titration.
5. The method for analyzing the brine over-alkali according to claim 4, wherein the titration comprises the steps of injecting brine into the reaction vessel, and controlling a standard acid titration unit to inject standard acid into the reaction vessel for titration; the step of evacuating the bubbles comprises controlling the standard acid titration unit to inject standard acid into the reaction vessel before injecting brine into the reaction vessel, and discharging the standard acid from the reaction vessel.
6. A method for analyzing the salt water alkali amount according to any one of claims 1 to 5, wherein the reaction vessel for titration is connected with a water washing unit, and if the salt water contains insoluble impurities, the water washing unit is controlled to feed water into the reaction vessel to wash the reaction vessel before starting titration.
7. A method for analyzing the amount of brine over alkali according to any one of claims 1 to 6, wherein the reaction vessel for titration is controlled to be washed with brine before the titration is started.
8. A brine-over-alkali analysis system controlled by the analysis method according to any one of claims 1 to 7, comprising: The device comprises a reaction container, a standard acid titration unit and a brine input unit, wherein the standard acid titration unit and the brine input unit are communicated with the reaction container; The controller is electrically or communicatively connected with the standard acid titration unit and the brine input unit; The controller controls the brine input unit to input brine to be detected into the reaction container, controls the standard acid titration unit to inject standard acid into the reaction container to titrate the brine to be detected, and obtains the over-alkali amount in the brine according to the standard acid volume consumed by titrating to a target titration point.
9. The brine overbased analysis system of claim 8, wherein the reaction vessel is connected with a water washing unit, and the water washing unit is connected with the controller; The controller controls the water washing unit to feed water into the reaction vessel to wash the reaction vessel.
10. The brine alkali amount analysis system according to claim 8 or 9, wherein the reaction vessel is connected with a liquid discharge unit, and the controller is connected with the liquid discharge unit and used for controlling the liquid discharge unit to discharge the liquid in the reaction vessel; preferably, a stirring device is arranged in the reaction container.

Description

Brine alkali excess analysis method and analysis system Technical Field The invention relates to the technical field of chemical industry, in particular to a brine over-alkali analysis method and an analysis system. Background In chlor-alkali production, sodium hydroxide (NaOH) and sodium carbonate (Na 2CO3) content in brine are important indicators reflecting the brine alkalinity level, wherein stable control of the excess alkali has important effects on electrolysis efficiency, ionic membrane life and product quality. At present, the monitoring of NaOH and Na 2CO3 content in industry mainly depends on manual analysis, the detection period is longer, the labor intensity is high, the real-time performance is insufficient, and the production state is difficult to reflect in time and the process adjustment is guided. Although some factories are equipped with online analyzers to replace manual detection, problems of long detection time consumption, insufficient result accuracy and the like still exist in actual operation, and especially under complex working conditions of high salt, high impurity, strong corrosion and the like, the adaptability and long-term stability of equipment are difficult to guarantee. These factors restrict the chlorine alkali industry from realizing high-efficiency automatic and lean production in the brine refining link, so an automatic detection scheme capable of stably operating under complex working conditions and monitoring the contents of NaOH and Na 2CO3 in real time with high precision and low cost is needed. Disclosure of Invention Therefore, the invention aims to overcome the defects of long detection period, high labor intensity, long detection time consumption, low accuracy, poor adaptability and insufficient long-term stability of the existing online analyzer in the prior art for manually detecting the excessive alkali amount, thereby providing a brine excessive alkali amount analysis method and an analysis system. According to an embodiment of the invention, in a first aspect, there is provided a brine over-alkali analysis method, comprising titrating brine with a standard acid titration unit, obtaining an over-alkali in the brine according to a standard acid volume consumed by titrating to a target point of titration; the target dropping point at least comprises a first dropping point with the pH value of 7.6-8.5, a second dropping point with the pH value of 3.9-4.5 and a third dropping point between the first dropping point and the second dropping point; The titration speed U 3 to the third drop point is controlled to be greater than the titration speed to the first drop point and/or the second drop point. According to the invention, by setting a plurality of dropping points in the titration process and adopting differentiated titration speeds in different titration stages, the titration speed can be reduced near the first dropping point and the second dropping point to ensure the accuracy of end point judgment, and meanwhile, the titration speed is increased in the process of titrating to the third dropping point, so that the analysis time of a non-critical stage is shortened. The technical scheme avoids overshoot errors caused by too high titration speed in a key end point area, reduces the whole detection period, realizes the compromise of detection precision and detection efficiency, and is suitable for automatic analysis and real-time monitoring of the salt water alkali excess under complex working conditions such as high salt, high impurity and the like. In some optional embodiments, the target drop point further includes an initial drop point with a pH value of 9.8-10.5, and the titration speed U Initially, the method comprises for titration to the initial drop point is controlled to be greater than the titration speed for titration to the first drop point and/or the second drop point; Preferably, the titration speed U Initially, the method comprises is controlled to be greater than the titration speed U 3. An initial dropping point with the pH value of 9.8-10.5 is introduced in the titration process, and higher titration speed than other stages is adopted in the stage, so that a sample rapidly approaches a key reaction zone from an initial state, the preparation time in the early stage is obviously shortened, and the overall analysis efficiency is improved. Meanwhile, by controlling the titration speed that U Initially, the method comprises is larger than U 3 and U 3 is larger than the first dripping point and the second dripping point, the lower speed can be kept in a critical end point interval to improve the end point judging precision, and the titration process is accelerated in a non-critical interval by utilizing the higher speed, so that the detection period is further compressed on the premise of not reducing the measurement precision, and the optimal balance of the analysis efficiency and the detection precision is realized. In some alternative em