SU606815A1 - Method of automatic control of carbonization process in soda production - Google Patents

Description

(54) THE METHOD OF AUTOMATIC CONTROL OF THE CARBONIZATION PROCESS IN THE PRODUCTION OF SODA only by the amount of carbon dioxide entering the carbo-column, i.e. unequally. The uniformity of the selection of the suckers from the carbocolon affects the next stage of the technological process, the calcination stage -i, which leads to an uneven supply of sodium bicarbonate for calcification. This causes an uneven release of carbon dioxide at the calcination stage, which is to be returned to the carbonation stage, and an uneven carbon dioxide supply to carbonization leads to an even greater instability of the technological process. Thus, the automatic control of the carbonization process by known parameters does not ensure the stability of the technological process under transition conditions. The aim of the invention is to increase the stability of the process in transient conditions. This goal is achieved by changing the selection of bicarbonate slurry on ri from carbocolonies, depending on the temperature distribution of the gas-liquid medium and the absorption part of the column. The temperature distribution in the absorption part of the column can be determined in various ways: by the ratio of the temperature of the top of the absorption part I of the column to the temperature of the reaction zone or by the mean temperature over the height of the absorption part of the column. In case of correction of the suspension selection by the ratio of the temperature of the top of the absorption part of the column to the temperature of the reaction zenes, it is advisable that the temperature of the top of the absorption part of the column be thoroughly adjusted by the temperature of the incoming liquid. Correcting the selection of sodium bicarbonate slurry not by the temperature of the top of the absorption part of the column, but by the temperature distribution in this part of the carbon tower allows eliminating noise (random temperature deviations, for example, due to the change in temperature of the incoming liquid), which could be superimposed on the correction signal . Figure 1 shows the scheme for implementing the method when adjusting the suspension selection according to the temperature distribution determined by n (3 the ratio of the temperature of the top of the absorption part of the column to the temperature of the reaction zone; figure 2 - the same as the average temperature value along the height of the absorption part of the column The method is carried out as follows. Carbon dioxide is distributed over carbonization columns 1 (one column is shown in the figures) by private systems for stabilizing gas flow rates in collectors 2 and 3 of the first and second pipes corresponding to The gas load in the first and second inlets is set by means of setting devices. The gas pressure in the collectors 2 and 3 of the first and second inlets is maintained by separate control systems.The suspension of the carbo-column is carried out depending on the output signal of the carbon dioxide supplied The output signal of the computing device 4 as a task is fed to the regulator 5 for removing the suspension from the carbone tower, to which a signal is sent as a correction signal l, proportional to the temperature distribution in the absorption part of the column. In a particular case, the correction signal is formed using the ratio (6) as the ratio of the temperature of the top of the absorption part of the column, measured by the sensor 7, to the temperature of the reaction zone; measured by sensor 8. In this case, it is expedient to additionally adjust the temperature of the top of the absorption part of the column to the temperature of the incoming liquid, which is measured with the help of sensor 9 of temperature. The signals from sensors 7 and 9 are received at block 10, which processes the error signal between the current and the set values of the temperature of the incoming liquid. The output signal of the unit 10 and the signal from the temperature sensor in the reaction zone are fed to the input of the ratio device 6, which processes the signal characterizing the temperature distribution in the absorption part of the column. The temperature distribution in the absorption part of the column can be determined in another way, for example, using temperature sensors 11, installed through a single point over the entire height of the absorption part of the column (see figure 2). Signals from sensors 11 proportional to the temperature at the corresponding point of the absorption parts of the column are fed to a computing device consisting of an adder 12 and a splitter 13. The computing device processes the signal proportional to the average temperature in the absorption part, which characterizes the distribution Definition temperatures. The signal processed by the computing device enters the controller 14, where it is compared with the specified one. The signal processed by regulator 14 is, in this particular case, a correction signal for regulator 5 for the removal of slurry. The suspension is taken either by the flow stabilization system 15, where the signal generated by the controller 5 is supplied as a program task, or the signal from the controller 5 is fed directly to the executing mechanism 16 (this possible communication is indicated by a dotted line).

An example. At the calcinia station, switching of apparatuses (calciners, soda furnaces) occurred, which led to a change in the amount of carbon dioxide entering the carbonization, respectively caused transient processes at the carbonization station until the device was switched on again.

Suppose the amount of carbon dioxide decreased. The transients, and therefore disturbances, entering the carbonization station for carbon dioxide consumption are until the control systems of the gas compression station: fill the carbon dioxide deficit for carbonization by adding additional gas to the mixing from the lime kiln separation.

These disturbances are perceived by the first gas intake stabilization system in manifold 2 and, accordingly, device 4 (see Fig. 1), which determines the amount of carbon dioxide supplied to the column.

The system of stabilization of the gas flow rate of the first input changes the position of the regulator in such a way as to bring the amount of carbon dioxide into the column in accordance with the task from the unit, and device 4 reduces the command signal to the slurry selection controller 5, which either comes as a programmer. set the controller 5, or acts directly on the actuator 16, reducing the selection of the suspension. :

During the transition process, during which, the system of stabilization of gas flow in manifold 2 results in the amount of carbon dioxide supplied to the column, fi according to the Task, a reduced amount of carbon dioxide enters the carbonization tower. This results in a decrease in the progressedness of the liquid, which start and form The sodium bicarbonate crystals in the reaction zone are lowered into the lower part of the column, which in turn leads to a change in the temperature distribution along the height of the absorption part of the column.

The change in temperature distribution in the upper absorption part of the column is sensed by sensors 7 and 8.

The signal from sensor 7 is supplied to block 10, which is processing the error signal between the current and setpoint temperatures. The output signal of the block 10 is fed to the controller 6 of the ratio of temperatures, where

also received a signal from the sensor 8 temperature in the reaction zone.

The regulator 6 processes the signal proportional to the temperature distribution in the absorption part of the column, which is fed to the selection controller 5 and additionally adjusts the selection of the suspension in such a way as to maintain the specified temperature ratio.

Maintaining a predetermined temperature ratio by influencing the suspension of suspension from the column leads to the fact that the angle of inclination of the temperature distribution curve along the height of the column is regulated.

When disturbed by the temperature of the incoming liquid (the fluctuation of the temperature of the incoming liquid is due to the switching of the columns from the washing mode to the carbonization mode), the amount of heat introduced by the liquid changes, which leads to a change in the temperature of the upper absorption part of the column and, accordingly, to a change in the slope of the temperature distribution.

The signal from the sensor 9 of the temperature of the incoming liquid enters the block 10 and changes the setting of the temperature of the upper absorption part of the column.

Thus, the temperature of the upper absorption part of the column and the reference change equidistantly, and since the output of block 10 varies depending on the error of signals proportional to the current and specified temperature, the output of this signal does not change, and the selection of the suspension remains unchanged, and the system establishes a new temperature distribution taking into account the heat introduced by the incoming fluid.

If the temperature of the upper absorption part of the column changes not depending on the heat introduced by the liquid, but depending on the heat released by the reaction, then the output signal of unit 10 is proportional to the magnitude of the mismatch between the new current and the set temperature of the top of the absorption part of the column 5 and the controller 5, additionally alters the withdrawal of the suspension from the column in such a way that the slope of the temperature distribution over the height of the column (and, consequently, temperature distribution remains unchanged ..

This generalized control parameter, such as the temperature distribution in the absorption part of the column, most reliably reflects the carbonization process, since, according to theory, the individual stages of the sodium bicarbonate crystal process are