SU567721A1 - Method of automatic control of process of production of monoethanoloamine sulphate - Google Patents

Description

one

The invention relates to the field of automatic control of chemical processes, in part of the process of preparing monoethanolamine sulphate, an initial product for the synthesis of ethyleneimine.

Monoethanolamine sulphate is prepared with imioethanolamine and sulfuric acid in the presence of water, with this, the ratio of initial reagents should correspond to stoichiometric (mol per mole).

The process for producing ethyleneimine proceeds in several stages.

The first stage is the production of monoethanolamine aqueous sulphate (SREA) by the interaction of weed acid and monoethane shamine (MEA) in the presence of certain amounts of water.

The second stage is the preparation of α-amino-egylsulfuric acid (AESC) by heating with the dehydration of SMEA.

The third stage is the preparation of a water alkali aqueous-alkaline solution of the sodium salt of AESK from the AESK.

The fourth stage is the preparation of ethyleneimine, which is separated from the reaction mixture by the method of rectification, by heating the aqueous-alkaline solution of the AESK sodium salt.

It has been proven that the yield of the intermediate product - AESC and, accordingly, of ethyleneimine - is significantly affected by the constancy of the composition and concentration, respectively, of the СМЭА and alkaline solution of sodium AEDC. When receiving SMEA it is necessary to maintain the molar ratio of MEA: O 1

(an excess of acid is not more than 0.5%) at a certain water content, and when preparing an aqueous-alkaline solution of the sodium salt of the AESC, it is necessary to maintain the molar ratio of the NaOH: AESK-2.5 (a deviation of tO, 1O is tolerated) and the specific concentration caustic reward in solution (0.1%).

Failure to comply with these conditions leads to a significant reduction in the output of the AESK and, accordingly, ethyleneimine, to an overestimation of the consumption of initial reagents, which is of particular importance in the large-scale production of ethyleneimine. It is known to maintain a constant composition of said target solutions using metering devices and flow and ratio controls. However, attempts to use existing technical means (flow controllers and ratios) did not allow to achieve the required precision of composition control, since the indicated affinities give an error on consumption of not less than-i 5.5%, which, if received, gives rise to the failure rate sulfuric acid — 3.5% (allowed ≤ 0.5%). In addition, specified; The means are absolutely not suitable for working in conditions of varying concentrations of the initial reagents. So for example, | a change in the concentration of sulfuric acid from 92% to 94% (permitted by GOST) increases the content of free sulfuric acid in SMEA from 0.5% to 2.5%. It is even more difficult to obtain an alkaline solution of sodium sapi AESK of a strictly defined situation due to the complexity of the dosage; firm about the crystalline ASC of variable particle size distribution. A method of automatic process control is known, consisting in varying reagent consumption depending on. of its density and the rate of change of the density value of l J. The use of this method for this process requires the use of starting reagents of a strictly defined concentration. Closest to the proposed automatic control method, which consists in controlling the costs of input products depending on the change in laiot of the product being withdrawn and the maximum and minimum values of its level S. - Process control by a known method does not allow improving the quality of the target product by changing the concentrations of the initial reagents. The purpose of the invention is to improve (the quality of the target product. To this end, in the known method, when adjusting the flow rate of one of the input products, sulfate conductivity is introduced mono-ethanol amine .In Fig. 1 is a schematic diagram of the automatic control; in Fig. 2 is a graph of the mineralized dependence of the density O-h of the electrical conductivity of the ES on the concentration MEA and sulfuric acid in aqueous solution; Fig. 3 is a plot of the molar ratio of the density and the electrical conductivity of O5} and aONSAESK and the concentration of A / AOH in an aqueous-alkaline solution of sodium ASC salt. The automatic control unit includes reactor 1, sensors 2 densities, conductivity sensor 3, flow sensors 4 and 5, regulators 6, 7, 8, 9 and 10, flow sensor 11, tanks 12 13: 14 source reagents, control valves 15, 16, 17, circulation pump 18c Example . Reactants-MEA, sulfuric acid and water, respectively, are fed to reactor 1 from tanks 12, 13 and 14, respectively. Signals from sensors 5 and 11 are sent to regulators 6, 8 and 10, respectively, and act on control valves 15 , 16 and 17, Sensors 2 and 3 measure, respectively, plotzosp and electrical conductivity of aqueous SMEA. When the density deviates from the specified value, the signal from sensor 2 is fed to rv-tugor 9, equipped with a differentiating prefix, which goes to the input of the correcting device of regulator 8 and changes the signal of the latter to control valve 17 IEA. The signal from sensor 3 goes to a regulator 7, equipped with a differentiating prefix, from which it comes to the input of a correction device 6 of the flow regulator 6 and changes the signal of the latter to a regulating valve 15 located on the sulfur supply line in a similar way. The deviation of the control parameters (density and electrical conductivity ) due to a change in the composition of the target solution and its concentration, there is a change in the flow rate of two of the initial p & ageites, which leads to the stabilization of these parameters and the composition of the target growth ora. During the continuous operation of the experimental unit for the preparation of aqueous MEAS by the described method for 48 hours, the concentration of MEAS according to periodic analyzes was 84.2 ± 0.5%, and the concentration of free sulfuric acid, respectively, 0.5 to, 3% at the use of initial reagents of variable concentration (MEA 90-97%,, 92-94%). Example 2. The initial reactants are continuously fed to the reactor 1 — a concentrated solution of caustic soda and water, respectively, from tanks 12 and 14, and crystalline AESK from tank 13 using a screw-type feeder. The signals from flow sensors 4 and 5, respectively, flow to controllers 6 and 8 and act on control valves 15 and 17. Sensors 2 and 3 located on the line

circulation, the density and the electrical conductivity of the alkaline aqueous solution of the sodium salt of the AESK are measured, respectively. When the density is declining from the specified value, the signal from the density meter 2 is shown on the regulator 9, equipped with a differentiating set-top box, which goes to the input of the adjusting device of the flow regulator 8 and changes the signal of the latter to; control valve 17 located on the water supply line to the reactor. The signal from 3 goes to the regulator 7, equipped with a differentiating prefix, from whom it comes to the input of the correction device: flow controller 6 and the signal of the latter to the regulating valve 15 located on the feed line of the caustic soda solution.

During the continuous operation of the pilot plant for the preparation of an aqueous-alkaline solution of an AZSK in the manner described, the molar ratio L / AOH: AESK according to periodic analyzes was 2.5 - 0.5, and the concentration of caustic soda 16.5 i 0.1%, time installation work 48 hours

The proposed method provides more precise regulation and improvement of the quality of target solutions, the ability to use initial components with variable concentration of the main substance, a significant decrease in the number and volume of technological equipment from highly alloyed steels, a reduction in the number of staff: an increase in the productivity of the pile and an increase in production capacity, an increase in final output product and improvement of economic indicators of the technological process nor egilenimina.

Claims (2)

 1. USSR author's certificate N9 ZZO176, kp. q- O5 D 27 / OO, 1969. 2. USSR author's certificate NI 421865, KIU QOSjp 27 / GS, 1972. ixj- . v J Cf19A o / / yaHaOHfi,)