SU1518632A1 - Method of monitoring the process of loose materials drying - Google Patents

Abstract

This invention relates to the automation of drying processes. The purpose of the invention is to improve the quality of control. For this, the maximum hygroscopic humidity W _{mg of the} bulk material is preliminarily determined (for example, by a dynamic method of obtaining sorption isotherms), the temperatures T _mto and T _{mtc of the} heat transfer fluid are _measured at the wet thermometer at the entrance and exit of the drum 1 by means of sensors 2 and 3 T _m of the material after drying by the sensor 4 and its humidity W ₀ to drying sensor 5. The resulting data is input to the calculation unit 6, where the calculated final humidity W _k, which is then compared in the comparing unit 8 with the quantities th predetermined desired moisture content W _of dried material defined setter 9. The signal from the comparing unit 8 is used as the state information of the drying process. 2 Il.

Description

± -2.

The invention relates to methods for controlling the drying process of bulk materials and can be used in chemical and other industries to create control systems for the drying of bulk materials.

The purpose of the invention is to increase the quality of control.

FIG. 1 is a block diagram of a system for implementing a method for monitoring the process of drying bulk materials; in fig. 2 - the algorithm of the computing device.

The system for implementing the method of monitoring the drying process of dry materials contains a drying drum 1, heat transfer temperature sensors for a wet thermometer 2 and 3, respectively, at the inlet and outlet of drum 1, the temperature sensor 4 of the dried material, the computing device 6, the setpoint 7 of critical humidity, comparison unit and unit 9 of the desired moisture of the finished dried material.

The method for controlling the process of drying loose materials (for example, drying ammonium nitrate) is implemented as follows.

Measure the drying parameters: the temperature of the coolant on the wet thermometer at the inlet and outlet of the bar

ban 1 and T by means of sensors 2 and 3, temperature of nitrate after drying T by means of sensor 4, humidity of nitrate before drying Wo by means of sensor 5, and the obtained information is fed to the input of computational device 6. Pre-measured laboratory hygroscopic humidity W and this value is set by the setting unit 7. It has been shown that the values of U are practically equal to the values of the critical humidity. The information from the output of the setting device 7 is fed to the input of the computing device 6, where, in accordance with the algorithm shown in FIG. 2, the value of the final moisture content of the nitrate is calculated after drying

W,

to

which is then compared on the block

comparison with the value given by the desired moisture content of the dried saltpeter W, set by the setting device 9. The signal from the output of the comparison unit 8 is used as information on the state of the drying process.

Determination of maximum hygroscopic humidity VJ | It is possible to carry out the dynamic method of obtaining sorption isotherms, while for nitrate within one batch the value of W |, f. turns out to be constant. Since the dynamic method of obtaining sorption isotherms involves the determination of the moisture content of the material, average in volume, at equilibrium of the surrounding moist gas with the actual surface of the body, i.e. under conditions similar to the dynamic equilibrium between the gas and the material in real dryers, the values of W obtained, as noted above, are actually equal to the values of the critical humidity.

It is shown that the final humidity W is related to the critical humidity of UkrI and the critical temperature by the ratio

-C (); (one).

where C is a proportionality coefficient depending on the material properties (in particular, for ammonium nitrate, 015). To determine the received

expression

T fW -W I + T -W-In MTK-O MTO.

MTO K (

(Wa- -U-W.ln

five

Since the desired value of W is contained in both expressions (1) and (2), their joint solution is necessary, which is carried out as shown in FIG. 2 algorithm.

The algorithm implements a method of numerical solution of equations, known as the method of dividing a segment into halves.

For this, the parameters of the drying process T Т T, T,, W, are fixed. Due to the fact that the value of W | makes sense only within the limits of 0 W, then the initial values of the intermediate variables W and the reduced value of the parameter Witp is assigned. At the same time, WY is the value of the parameter W with test, and the value of W is correcting for checking the e1-: value of W. Based on the assigned value of W and the values of drying parameters T, T ", T, W, according to dependences (1) and (2), the values of T and W, are calculated. By the value of V, a check is performed for compliance of the tested value W with the true value of W, for which the correction value is halved and the value Wcp is assigned to it, after which W is compared with. If Wf, W, then the new value of W is reduced compared to V by the value of

w:

CP

what if

vv v

g

then new value

Wi is increased by w compared to W, after which the calculation process is repeated. So do until the value of W

pore

ij. will not be equal to the value of W. In this case,

Claims (1)

Invention Formula The method of controlling the drying process of bulk materials by measuring the temperature of the drying agent and the moisture content of the material before and after drying, characterized in that, in order to improve the quality of control, the maximum hygroscopic moisture content of the material is preliminarily measured, the temperature of the dried material, determine the critical the rank W is assigned the calculated material temperature, calculate The value of W, which is then compared in Comparison Unit 8 with a given value of the required final moisture content of saltpeter W ,. Fixation of the admitted parameters) T%, Tmto, .WKp Wr VV / cp // Wc / 7 ) Tlflr ,, ,,  (Sh-, p) .r-Cn; n - Wfp C {Tn-Tff,) cp cp / Issuance ina K -Wn Editor V.Kovtun Fig t Compiled by S.Polnsky Tekhred L. Serdyukova Order 6593/44 Circulation .593 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 the value of the current final humidity, compare the obtained value with the set value and, based on the comparison results, judge the state of the drying process. Proofreader O. Tsiple Subscription