SU1066623A1 - Method of controlling the process of evaporation in concentrating evaporator plant - Google Patents

Abstract

METHOD OF MANAGING THE PROCESS OF PACKING IN THE CONCENTRATING SHLPARY BATTERY OF ALUMINUM PRODUCTION BY STABILIZING THE RELATIONSHIPS OF THE UNITS AND THE HEATING STEAM SOLUTIONS AND HEATING STEAM IMPACT ON THE FLOW OF THE ORIGINAL SOLUTION WITH CORRECTION BY DIFFUSION. the density of the initial solution, characterized in that, in order to reduce the consumption of heat energy by increasing the accuracy of stabilizing the evaporated solution density, the level of the evaporated solution in the buffer tank after the battery and the evaporated solution from this tank are measured, the level increment is determined at each control step and compensate for the change in the level by an additional proportional change in the heating steam flow rate, determine the increment of the rate of change in the level and the increment (L of the solution flow rate from the buffer tank, and at zero increment: the solution flow rate corrects the ratio of the flow rates of the initial solution and the heating steam by a value proportional to the rate of change in the level in the buffer capacitance of the bone. yes and riaJ / m ffMft / t and to co

Description

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This invention relates to the control of technological processes in non-ferrous metallurgy and, in particular, to the production of alumina from nepheline raw materials.

A known method of controlling an evaporation battery provides for stabilization of the evaporated solution density, in which the cost ratio of the initial solution and heating steam is adjusted for the density of the evaporated solution after the first case flJ.

The closest to the invention in its technical essence and the achieved result is a method of controlling the evaporation process in a concentrating evaporation battery by stabilizing the ratio of the flow rates of the initial solution and the heating steam depending on density, temperature and the ratio of salt concentration of the initial solution 2.

The disadvantage of the method is a control error, which occurs due to a significant transport delay in the solution flow channels and the vapor density of the evaporated solution.

This error increases due to a change in the dynamic characteristics of the object, for example, when the heat transfer surfaces of the apparatus become overgrown during the operational period.

The aim of the invention is to reduce the consumption of heat energy by increasing the accuracy of stabilizing the density of the evaporated solution.

The goal is achieved by the fact that according to the method of stabilizing the ratio; the cost of the initial solution and steam heating effect on the flow rate of the initial solution with correction for the deviation of the density of the initial solution, additionally measure the level of the evaporated solution in the buffer tank installed after the battery, and the flow of the evaporated solution from this capacity, determine the level increment on each control step and compensate for the level change with an additional proportional change in the heating steam flow rate, determine the increment of the rate of change in the level and the increment of the solution flow rate from the buffer At a zero value of the solution flow rate, the ratio of the flow rate of the initial solution and the heating steam is adjusted in proportion to the increment in the rate of change of the level in the buffer tank.

The drawing shows a block diagram of a control system implementing the control method.

The evaporation battery 1 control system, after which the buffer tank 2 is installed, consists of a task solution generation unit 3 for the initial solution flow, the inputs of which are connected to the initial solution density meter 4 and the heating steam consumption meter 5 connected to the heating steam consumption regulator 6 , and the output of block 3 is connected to the regulator 7 of the flow rate of the initial solution connected to the meter 8 flow rate of the initial solution, block 9 forming a task for the flow of heating steam, the inputs of which are connected to the meter 10 in b ferric tank 2 and density meter 4, and the output is connected to the controller b of the unit 11 for correcting the ratio of the flow rate of the initial solution and the heating steam, the inputs of which are connected to the meter 12 for the evaporated solution flow at the outlet of the buffer tank 2, density meters 4 and level 10 and block 9, and the output of block 11 is connected to blocks 3 and 9.

The system operates as follows.

According to the results of measurements of the input density and the heating flow rate of the unit 3, in accordance with the set ratio of the flow rates of the solution and the steam, it forms the flow rate of the initial solution and transmits it as a task to the flow controller associated with the flow meter 8.

According to the results of periodic level measurements in the buffer tank 2 and the input density, block 9 forms a matching additive for the heating steam consumption and transmits it to the flow controller 6 as an adjustment task for the steam consumption. This reference in the controller is compared with the measured value of the steam flow.

According to the results of measuring the flow rate of the solution at the outlet of the buffer tank, unit 11 adjusts the ratio of the flows of the solution and steam by changing the coefficient a in the ratio of costs. The new value of the transfer coefficient in blocks 3 and 9, the formation of a new value of the coefficient is made by comparing the level increments in the buffer before and after adding the matching additive to the pair, the numerical value of which and the measured value of the input density (meter 4) are also used when generating the new value of .

Example. Evaporation takes place in a 3-cell battery.

The density of the initial solution is 1.20, the specified density of the evaporated solution, 1.32 is the consumption of the initial solution Q 133, the proportionality coefficient K 5 is the uncorrected coefficient a 2m /. The flow rate of the solution at the output of the buffer tank level. In order to match the performance of the battery with the adjacent redistribution, the flow rate of the initial solution Q 133 is set. Accordingly, the heating consumption OUT 8X -m 1 1.32-1.20 ,2 t-, i, 32-i25 t / h. Periodically control the level of the evaporated solution in the buffer tank and determine the level increment at each control step. For clarity of illustration, the usefulness of the proposed method does not consider below the operation of the circuit for correcting the flow of the initial solution from the measured density of the evaporated solution .25 At time t ,,, and then at time tt .At, the levels of the solution in the buffer tank are measured, and therefore , definitely the increment of the levels of HI H (t, + -ut} - H (t) 4t 5 min. 0.0833 h;) 4.5 m; H (t) 4 m; DC 0.5 m; G: 0 5 6 m / h At 0.0833 Correction correction of the heating steam flow in connection with the unbalance of the flow of the solution. p n uro. 4 con nous and fit equal to the genre. at ° OUTPUT JI J -.Sjb 32 - f, 20 K LN 1 2, 32 - f FIt New heating steam consumption. Q, n + uQn 25-5.6 19.4 t / h. The rate of change of the supernatant solution in the buffer tank after the change in steam consumption is determined. According to the results of the automatic control, it was found that the change in the level of Li is 0.05 m per lit 0.0833 h LC 0.5 (, (3, - 0, - °) The compensated value of the balance imbalance in increments of changes in the level of Buffer capacity K (t - TT) 5 (0.6-6) l t. .y -27.0 m 7h ultiplicative correction - coefficient a. -. in mhRvk -27.0 "p, .- -5.6 1 , 32-1.20. About 3. 4, / New consumption of the solution P -1 p ol./8YX ii 1.8 19.4 X 6p rtlTif Yeek-Rvh 1.3.2-1 93 1.32-1.20 Thus, as a result of the improvement, according to this method, we find conditions that ensure the subdeal of a given density value. laziness increases NOSTA upanogo stabilization fluid density and, as a consequence, the specific consumption of heat zhaet 0.04 Gcal.

Claims (1)

METHOD FOR CONTROLLING THE EVAPORATION PROCESS IN A CONCENTRATING VAPOR · BATTERY of alumina production of the feeds of the initial solution and heating steam by influencing the flow rate of the initial solution with a correction for the deviation • density of the initial solution, characterized in that, in order to reduce heat consumption by increasing the accuracy of stabilization of the density of the evaporated solution, additionally measure the level of one stripped off solution in the buffer tank after the battery and the consumption of one stripped off solution from this tank, determine the level increment at each control step, they compensate for the level change with an additional proportional change in the flow rate of the heating steam, determine the increment of the rate of change of the level and the increment of the flow rate of the solution from the buffer tank, and at a zero value of the increment in the flow rate of the solution, the ratio of the flow rates of the initial solution and the heating steam is adjusted in proportion to the increment of the rate of change buffer level yes N0 00