RU1806317C - Method for automatic control of parallel operating drying units - Google Patents

Abstract

Usage: chemical industry, mineral fertilizer industry. SUMMARY OF THE INVENTION: The difference deviations of humidity on each unit in comparison with the set ones and their total value are determined. The ratio of the change in the total consumption of material to the total value of the difference deviations is determined, and the consumption of the starting material and fuel consumption for each drying unit are additionally adjusted by the value of the product of the obtained ratio by the difference deviations. 1 il ,, 3 tablets ate

Description

The invention relates to a technique for controlling the drying process on several units operating in parallel in the production of potash fertilizers and can be used in other industries

The purpose of the invention is to improve the quality of control and stabilization of humidity of the final product.

The drawing shows a structural diagram that implements the proposed method.

The device comprises a dryer 1 with a furnace 2 and a mixing chamber 3. distribution conveyor 4, hopper 5, feeder 6. collecting conveyor of the dried product 7. primary air flow sensor 8, actuator 9 with a regulating body 10, secondary air flow sensor 11, actuator 12 with a regulating organ 13, a temperature sensor 14 in the mixing chamber, a pressure sensor 15 in the furnace, an actuator 16 with a regulating body 17, a sensor 18 for the flow of raw material to the dryer, an actuator 19 with a regulating organ anom 20, a level sensor 21 in the hopper 5, an actuator 22 with a regulator 23, a fuel consumption sensor 24, an actuator 25 with a regulator 26, sensors 27 of the total flow and humidity 28 of the source material, sensor 29 of the total humidity of the dried material, sensor 30 the temperature of the dried material at the outlet of the dryer, a microprocessor controller 31, an adapter 32, a computing device 33.

The method for controlling the drying units is as follows. The signals from all sensors are fed to the inputs of the microprocessor controller 31

with

oh oh

00

s

(hereinafter IPC) connected to the computing device 33 through an adapter 32. The IPC Algoblocks 31 are adjusted in accordance with the algorithms selected from the IPC library. Actuators 9, 12, 16, 19,22.25 are connected to the output of the IPC. The flow rate of the primary air measured by the sensor 8 using the actuator 9 and the regulator 10 changes the IPC depending on the fuel consumption signal measured by the sensor 24. The flow rate of the secondary air measured by the sensor 11 using the actuator 12 and the regulator 13 changes IPC depending on the temperature signal in the mixing chamber 3, measured by the sensor 14. IPC performs pressure stabilization in the furnace 2, measured by the sensor 15, acting on the actuator 16 and the regulating body 17. In numeral device 33 to the temperature signal of the dried material, the measured sensor 30, the current value is determined by the formula humidity dried material

Wic bo - bifTi0) 2 + b2Tic,

where Wic is the current moisture value of the dried material at the outlet of the 1st drying unit,%;

T (s - temperature of the dried material at the outlet of the i-ro drying unit, ° С;

bo, bi, ba are the coefficients determined experimentally; for drying the potassium chloride concentrate, they are respectively equal to 1.556; 0.0001; 0.0219,

Using the signals of the total consumption of the material measured by the sensor 27, its moisture content from the sensor 28, the consumption of material and fuel into each drying unit from the sensors 18, 24, set by W3 ° and the calculated Wjc of the moisture value of the dried material, the problem of controlling parallel-running drying units is solved. comprising minimizing the overall fuel consumption and stabilizing the moisture content of the dried product by the formula.

QT j. Q (w-wf)

1 1 (100-Wf) Ki

where Qcl is the total fuel consumption for drying units, tp;

QI is the consumption of the source material in the 1st drying unit, t / h;

W is the moisture content of the starting material,%;

KI - coefficient characterizing the ratio of the amount of evaporated moisture to the fuel consumption of the 1st drying unit.

Its KI value is determined during operation for each dryer at humidity values of the dried concentrate close to a predetermined value.

Expression (1) should provide processing of the total consumption of the source material 10. p

Qo X Q RI preset value wet V

the dried product at the outlet of each drying unit.

W3c-wЈ

The solution of expression (2) with the indicated restrictions allows obtaining optimal values of material and fuel consumption for each drying unit.

Formed in the computing device 33 optimal control signals through., The adapter 32 are received

25 directly to the first inputs of the MPK31 algoblocks, which perform PID control of the initial material and fuel consumption for each drying unit, in the algoblocks, the calculated and current values are compared30 and in case of mismatch of signals, the algoblocks give control actions on the actuators 19, 25 that affect regulatory bodies 20, 26, until

35 times and in that direction, until the current values of expenses become equal to the calculated ones. Next, in the computing device 33, the set and calculated by the formula (1) current humidity values are compared

40 dried material for all operating drying units.

AWic W3c-Wic, Д W2c W3C - W2Cl ..., AWic W3c-W (; (3)

After calculating the values of the difference deviations, their total value is determined by the formula

45

Ј D Wc D Wtc + A W2C + ... + D N (4)

about

When the total consumption of the starting material changes, its increment ± D Q is redistributed among the drying units depending on the value of the product of the ratio of the change in the total consumption

material DO to the total value of difference deviations Wc

(5

the value of the difference deviations, L Wi ° according to the formulas

AQi 5Q-AWic, A W2C, .... AQ (- 5 Q AWic, (6)

where AOi, AQ2, .... A Qi is the change in the cost of the starting material by 1,2, ..., 1st drying units.

The signals AWic, AWac, .... A Wic and chipboard, AQ2, .... A QI come from the computing device 33 through the adapter 32 to the second inputs of the MPK31 algoblocks, which respectively carry out PID control of fuel consumption and the source material. After filtering and scaling neither of the above signals, algoblokoformi-; new control actions are applied to actuators 19, 25 and regulatory bodies 20, 26, which ensure a change in fuel consumption and source material, compensating for deviations of the current humidity values of the dried material from a predetermined value on each drying unit.

The control method was tested in industrial conditions on three parallel-running drum dryers on SOF 4 RU bp. Belaruskali.

The automation circuit is mounted on the basis of the microprocessor controller R-110 and the personal computer Videoton.

The total consumption Qo of cake concentrate varied from 190 to 210 t / h, and its moisture content varied from 7.5 to 8.2%.

Coefficients characterizing the ratio of evaporated moisture to fuel consumption Ki, K2, Kz were determined for each dryer drum with parameters close to optimal by the formula

K Qmi (W-Wh (100 - Wf) Q TI

where Qmi, W, Wi, QTI are respectively close to the optimum values of the feed rate of the starting material, its moisture content, moisture content of the dried material, fuel consumption by. 1st drying drum. The calculation data, determined taking into account the technical condition of the drums, are summarized in table. 1.

Substituting tabular values in the formula (7), we obtain Ki 6.41, K2 6.2, Kz 5.56.

The preset humidity value of the dried material L / s, taking into account the subsequent treatment with an anti-caking agent, was adopted 0.5%.

On the PC Videoton, the current humidity values Wic, Wac, L / ss at the output of each dryer drum were calculated according to

. formula (1) and the control actions on the flow rate control of cake concentrate Qi, 0.2, Oz, fuel QiT, Q.2T, Ozt BEFORE the increment and after the increment A Q of the load. AT

in case of a change in the load of the concentrate cake, redistribution of BS. for drying drums and fuel consumption adjustment was performed according to formulas З-б.

For three drying drums, the mathematical formulation of the problem has the form

QT Qi (W-WS) + Q2 (W-W§) + ° (100-W j) Ki (100-W5) K2

H Q3 (W-W§) (100-W5) K3

mln

(8)

fifty

55

subject to the limitations of Qi + 02 + Oz Qo and WsAO0 20 Wlc W2c Wa3.

The solution of the problem with equality type constraints (8) was carried out by the method of indefinite Lagrange multipliers, with the subsequent solution of the obtained nonlinear 5 equations on a personal computer using specially developed software, including the exchange program between the personal computer and the MPC.

According to the method of controlling parallel rising machines mounted in the prototype, the material consumption for each dryer drum is proportional to the coefficients KI, K2, KZ.

In both cases, the exchange between IPC and

35 PCs for transmitting the current value of the signals were carried out every 5 s. After averaging the signals on the PC, the calculated signal values were transmitted once every 5 minutes to the IPC algoblocks, which generate control actions on the regulating bodies of the changes in the flow rate of the concentrate cake and fuel.

As a result of tests according to the proposed and basic variants, the values of control actions were obtained that, due to the quality of control, ensure the minimum of the Oo function and stabilize the humidity of the dried concentrate.

The test results are summarized in table. 2,3.

In the table. Figure 2 shows the values of control actions, output humidity and target functions before increment and after increment of load A00 of 20 t / h with the proposed control method.

In the table. Figure 3 presents the control actions, output humidity and target functions according to the method specified in the prototype.

The total load applied to the drying drums in both methods was 190-210 t / h.

From a comparison of the results, table. 2.3 it follows that the control method distributes the consumption of the starting material and fuel and stabilizes the moisture content of the dried concentrate within a range close enough to the value of the set total output humidity, which achieves the required quality of the finished product by humidity and reduction of specific fuel consumption and

LHV-: 2Q ° i. ,

ЈQo2 SQoi + AQo

 12.435 11.370 -nnmnfiq -TOOT 900 + 100-0001065

tons of fuel; .. -

t of concentrate

Claims (1)

SUMMARY OF THE INVENTION A method for automatically controlling parallel-running drying units by changing the flow rates of starting material and fuel depending on the total consumption of material, the number of running units and the ratio of the amount of evaporated moisture to the corresponding fuel consumption for each drying unit, characterized in that, in order to improve control accuracy, measure the temperature of the dried material after each drying unit, which determine the moisture content of the dried material and for each unit, compare it with a predetermined humidity value, determine the value of difference moisture deviations and their total value, determine the ratio of the change in the total material consumption to the total value of the difference deviations and depending on the product of the ratio obtained by the difference deviations of each unit, additionally adjust the consumption of the starting material and fuel consumption for each drying unit. 3Q Table 1 170 8.11401461350,50,490,4260,856,452,80,670,650,6268,556,465,10,75 0,65 0,76 0,50,490,512,16 175 8.05142Y71360,460,50,4362,658,054,40,690,670,6469,858,067,20,7680,67 0,7860,50,482,222,22 1808.0144148 ТЗО0,480,510,40,5 20 64,459,755,90,800,680,6567,759,772,60,74 0,68 0,85 0,50,510,49 ..2,27 147 142 J24 0.5 0.46 0.38 132 150 140 0.4 0.52 0.45 Qo2 - 1000 66.2 61.4- 57.4 0.73 68 63 .59 0.75 C4Q - 100 0.7 0.67 66.2 66.4 72.4 0.73 0.764 0.847 0.5 0.5 0.482.34 0.72 0.69 72.2 6.1 66.8 0.83 0.73 0.82 0.49 0-, 51 0.492.38  -------------------------------- 1-Q, 37 Table Qo2T 12.435