CS205690B1 - Method of control and ending the charging chemical processus - Google Patents

Description

The invention relates to the objective and optionally automatic control and termination of chemical reactions, especially in industrial production. Its principle lies in a new way of monitoring and evaluating the temperature changes of the reaction mixture caused by the reaction heat.

Hatching, sometimes automated chemical processes usually involve chemical reactions, the course of which can be clearly defined in advance. If the concentration and the quality of the starting and auxiliary substances are known, the individual components can be dosed accurately or automatically and, according to predetermined conditions, can be dosed accurately or automatically and the reaction can be terminated according to a fixed program. However, if the quality or concentration of the raw materials fluctuates, or if the prescribed reaction conditions, such as temperature or pH, cannot be met precisely, the reaction time varies in addition to the quantity of the feed components. Not only the performance of the production equipment, but also the yield and quality of the product often depend on its observance, which are further influenced by the accuracy of dosing. In these cases, it is necessary to continuously evaluate the composition of the reaction mixture and, based on the obtained results, to control and possibly terminate the process. For automatic production, continually operating analyzers are suitable. However, devices of this type developed so far allow only a small part of the chemical reactions to be monitored (see, for example, U.S. Pat. Nos. 120,137 and 128,404J.) It is well known that chemical reactions are accompanied by greater or lesser thermal effects. For example, it is possible to apply flow-through enthalpiometry to allow automatic analysis of reaction mixtures with feedback to the production process, and an iabiabatic flow reactor with dosing dependent on temperature changes of the reaction mixture. A number of factors prevented the wider application of thermometric methods in this area, especially in the control of discontinuous processes, and the thermal changes associated with most chemical reactions are relatively small, so that the temperature drop of the reaction mixture These changes manifest and which can be measured and evaluated are, on a technological scale, significantly influenced by changes caused by heat exchange with the environment, the course of side and subsequent reactions, as well as 1 reactions of auxiliaries, eg neutralization, further dissolution or excretion of reactants and reactants. products. The above disturbing effects were in many cases managed to eliminate the method, which is the subject of MS. aut. osv. No. 205,687 and wherein process control signals are derived from a decrease in temperature change during the course of the reaction. However, this procedure does not allow the automatic determination of the equivalence point, i.e., the dosing of reactants of inaccurately defined concentrations in an equivalent ratio where the process requires it.

According to the invention, it has been found that said deficiency is easily remedied and chemical

The 3,690 processes according to the above formulated requirements are objectively controlled and terminated in a manner that consists in adding to the at least one reactant a continuously defined rate of or. intermittently at doses of a defined size of one or more reagents and continuously or at predetermined time intervals, measure the amount of temperature change of the reaction mixture corresponding to a defined amount of reagent added, achieving a predetermined amount of temperature change or reaching a predetermined difference or proportion subsequent temperature changes, or a sudden change in rate of temperature change, is used as a signal to adjust reaction conditions, e.g., temperature, pH, or reagent concentration, and / or to change the rate of dose interruption and / or terminate the process. In controlling and terminating a number of processes, it is advantageous for the rate of temperature change to be determined by automatically deriving the reaction mixture temperature over time.

The main advantage of the process according to the invention is that the proposed process can be used to objectively control and terminate even those chemical reactions for which no suitable analyzers are available yet, allowing automatic dosing of reactants 1 of inaccurately defined concentrations therein, where the technological process requires it.

The above process can be used to objectively control and terminate a number of chemical processes, often 1 where the reaction mixture needs to be cooled or heated during the reaction. It is preferred that the reaction proceeds rapidly enough, i.e., usually not more than 1 to 3 hours. Its use to some extent limits the sometimes insufficiently reducible excretion of the reaction products during the controlled process.

For measuring temperature changes according to the invention, temperature sensors with non-linear characteristics (signal processing within a narrow temperature range) and with a certain long-term instability of parameters can be used (pairs of measurements are evaluated in a relatively short time interval). Thus, for example, thermostats which are sufficiently sensitive and exhibit only a negligible delay can be advantageously used. A relatively simple electronic device can also be used to evaluate the measured values.

The process according to the invention is explained in more detail below by means of several examples, which, however, are not intended to limit or limit the scope of the invention, particularly as regards the type of chemical reactions for which monitoring, control and termination may be employed. Unless otherwise stated, the solutions or suspensions described are characterized by molar concentrations, the amounts being given in parts by volume.

Example 1

A 0.5 d aniline hydrochloride solution containing ca

1.2 equivalents of free hydrochloric acid.

After cooling to 10 ° C, 96 d. Of 5 M 25 ° C warm sodium nitrite solution is added. After stirring for 1 minute, the remaining amount of the above-mentioned pseudo-agent is to be admitted periodically at 20 s intervals in portions of 0.4 d. The dosing is terminated when the temperature rise in the reactor corresponding to a single dose, i.e. 0.4 d. Sodium nitrite solution, is less than 0.03 ° C. After another 30 seconds, the diazotization is complete. The final temperature of the reaction mixture is about 23 ° C, the temperature difference corresponding to 0.4 d of sodium nitrite solution is about 0.05 ° C during diazotization. The whole process is preferably controlled automatically.

Example 2

500 d. Of water, 80 d. Of 2.5 M sodium nitrite solution, and 240 d. Of 80 ° C warm about 0.8 M p-nitraniline hydrochloride solution containing from the tanks are charged into the reaction vessel over approximately 20 seconds. ca 4 equivalents of free hydrochloric acid. Immediately thereafter, at a constant rate of 0.5 d / s, the remaining amount of about 12 d. Of the above-mentioned aromatic amine solution is allowed to admit. The temperature of the reaction mixture is automatically read out at 1 second intervals and the differences of two immediately measured values are evaluated. When the difference between two successive differences reaches a predetermined value (at least 0.005 degrees Celsius), the p-nitraniline dosing is terminated, 0.8 d. Of 2.5 M sodium nitrite solution is added automatically, 15 seconds thereafter. M amidosulfonic acid solution and the process is terminated. The final temperature of the reaction mixture is about 38-40 ° C. Temperature difference corresponding to 0.5. d. The amine solution (admitted in 1 second varies as it depends on the temperature of the rinsing agent, ambient temperature, batch size, etc.). The difference between the differences, one measured before and the other after the equivalence point, is about 0.01 °. C.

Example 3

The process of diazotization of p-nitraniline proceeds as in Example 2, but the signal for terminating the amine dosing is a sudden change in the proportion of two successive temperature differences by a predetermined value.

Example 4

The diazotization of p-nitraniline is carried out as in Example 2. However, the temperature of the reaction mixture is measured continuously during the addition of the aromatic amine and is automatically derived over time. The sudden decrease in the rate of temperature change thus determined is a signal for the completion of the p-nitranine dosage.

Example 5

To a solution of 700 d. Water and 107 d. O-toluidine, a 5 M hydrochloric acid solution was added uniformly with stirring at 20 d. Per minute. The temperature of the reaction mixture, sensed continuously, is differentiated by electronic equipment over time. The sudden drop in the thus determined temperature grain velocity of 205690 ny (at about the same temperature of the starting components from about + 0.013 ° C / s to about -0.002 ° C / s) is used as a signal to terminate the neutralization. Example 6

To 1000 d. Of a 1 M solution of 1-phenyl-2,3-dimethyl-5-pyrazolone was added 200 d. Of a 3 M sulfuric acid solution and the resulting mixture was cooled. At 10 [deg.] C., 190 d. Of a 5 M sodium nitrite solution is allowed to cool. After stirring for 5 ml, the cooling is started pediodically in lmin without cooling. the remaining amount of nitrosating agent required (a total of about 10 dj) The dosing is terminated when the temperature rise corresponding to a single dose, i.e. 2 d. of sodium nitrite solution, is reduced by at least 0.1 ° C. The final temperature of the reaction mixture is approximately 11 [deg.] C. The temperature difference corresponding to 2 d of the nitrosating agent solution is approximately 0.2 [deg.] C. during the reaction.

Claims (2)

SUBJECT 1. A process for controlling and terminating seed chemical processes, characterized in that one or more reactants are added to at least one reaction component at a defined rate or intermittently in batches of defined size, and the amount of temperature change of the reaction mixture is measured continuously or at predetermined intervals. corresponding to a defined amount of reagent added, wherein a predetermined amount of temperature change is achieved or a predetermined difference is achieved Example 7 The reaction vessel was charged with 1250 d. Of a 0.4 M solution of 1-phenyl-3-methyl-5-pyrazolone-4-sulfonic acid mononatrium salt, 52 d. Of 10 M sodium hydroxide and 5 d. Of acetic acid. To the thus prepared azo component solution was added within 15 min. (about 91% of theoretical consumption) of a 0.45 M solution of benzenediazone chloride, optionally obtained as described in Example 1. After stirring for 5 minutes, it is calculated periodically in 1min. the required amount of the above diazolate (about 100 dj in total) The dosing is terminated when the temperature rise in the reactor corresponding to a single dose, i.e. 10 d. of benzenediazonium chloride solution, is less than 0.15 ° C. . reakění final temperature of the mixture is about 30 ° C, the temperature difference corresponding to 10 d. the solution diazolátky achieved during the coupling of about 0.03 ° C. the process is preferably automatically controlled. ⁴ OF THE INVENTION The proportion of successive temperature changes, or a sudden change in the rate of temperature change, is used as a signal to adjust the reaction conditions, e.g., temperature, pH or concentration of the reactants, and / or change the rate or interrupt the dosing and / or terminate the process. 2. The method of claim 1, wherein the rate of temperature change is determined by automatic derivation of the temperature of the reaction mixture over time.