SU1695273A1 - Device for controlling mass flow rate of mixed products - Google Patents

Abstract

The invention relates to automatic control systems and is intended for use in those industries whose technological cycles provide for the consumption of liquid products in a given mass ratio. The purpose of the invention is to improve the accuracy and quality of regulation with a change in the mass flow ratio in a wide range. It is achieved by including in each of the n channels the mass flow calculator, the subtraction unit and the multiplication unit of the codes providing the error error signals and transforming them into corners, and the control command generator, which, based on the average angular velocity of the drive, establishes the required duration of the control action for the adjustment of the actuator to the calculated angle Yes. The unit for the flow rate of the first channel is the unit for the overall performance of the technological object, and the units for the other channels calculate the required mass flow rates of the corresponding products according to the specified ratios between them. Measuring information from the turbine flow transducers and temperature sensors enters the computer through frequency-code converters and scaling blocks, respectively. Pulse counters, a frequency divider, an RS trigger, an And element and a block of time intervals provide the necessary sequence of activation of the functional elements of the device in each control cycle. 2 hp f-ly, 5 ill. cl

Description

The invention relates to automatic control systems and can be used in various industries where it is necessary to supply the consumer with liquid products in a predetermined mass ratio,

The purpose of the invention is to improve the accuracy and quality of regulation while changing the mass flow ratio in a wide range.

Fig, 1 shows a functional diagram of the device; in fig. 2 - functional diagrams of the frequency-code converter and the mass flow calculator; in fig. 3 shows flow control devices for the first and the nth control channels; in fig. 4 is a diagram of the formation of control commands; in fig. 5 is a plot of the duration of the control command versus the magnitude of the error signal, which explains its principle of operation.

oh oh cl

Yu

sj

Sl

The device contains n control channels according to the number of mixed products in technological object 1, each of which includes an actuator (flow controller) 2 with drive 3, a turbine flow converter (TPD) 4, a temperature sensor 5, a frequency-code converter 6 scaling unit 7, mass flow calculator 8, subtraction blocks 9 and multiplying 10 codes, control command generator 11 and flow master 12, counters 13 and 14 pulses, frequency divider 15, RS flip-flop 16, AND 17 and time block 18 , part otorrhea m input generator 19 of reference frequency f0, the switch element 20, switch 21 and frequency divider 22.

Each of the converters 6 frequency-code in the simplest version contains (Fig. 2) two counters 23 and 24 pulses, register 25, RS-flip-flop 26, element 27 and element 28 of the delay 28.

The calculators 8-1., 8-p have the following functional elements: blocks 29 and 30 of code division, blocks 31-34 of multiplying codes, adders 35 and 36 codes, register 37, block 38 of code subtraction, blocks 39-41 of memory, counters 42 and 43 pulses, RS-grigger 44, elements And 45 and 46, and elements 47 and 48 of the delay.

Flow meter 12-1 in the proposed embodiment contains (Fig. 3) switching elements 49-1 .., 49-d and two groups of memory elements 50-1 ... 50-d, 51-1 ... 51-d . Unit 12-2 implements, for example, the code multiplication function, while the remaining unit 12-3 ... 12-n circuits include code multiplication blocks 52 and 53, adders 54 codes, memory blocks 55, delay elements 56 and are made up of to the calculation of the required mass consumption of liquid products in each of the channels Z ... n regulation by the ratio:

m {3 ... n) i az., n mil ± bz. l mp (n-i) i, (1) where TCs, t (s ... n) are the current values of the mass consumption of products in the first, third and subsequent control channels:

... () i - similarly for the 2nd ... (p-1) -th channels;

az ... n, b3 ... n - coefficients of proportionality,

The construction of drivers 11-1 ... 11-p control commands is determined by the TIPRMI of the actuators 3 used to control the actuators 2-1 ... 2-p. The schematic of the former shown in FIG. 4, is composed with reference to an electromechanical actuator, taking into account the conversion of the selected error signals and the pulse-width form, and contains

two subtractive counters 57 and 58 pulses, a block 59 of code comparison, a programmable frequency divider 60, keys 61-63, elements AND 64-66, two RS-flip-flops 67 and 68, and element NE 69.

As scaling blocks 7-1 ... 7-P, standard instruments can be used to convert the measuring signals UT of temperature sensors 5-1 to 5-n into the physical dimension of the parameters Ti ... Tn.

The device worked as follows.

It is preliminarily adjusted its circuit elements for the modes of operation that ensure the specified mass flow rates of the liquid products in all channels and the required performance of the object 1.

For this:

1. In blocks 40-1, 40-2 and 40-3 of the memory of calculators 8-1 ... 8-n, coefficients Ai ... n, B-i ... n, CI ... R approximations are entered the flow characteristics of TFR 4-1 ... 4-p, in the general form written by equations of the 2nd degree:

Q (1 ..n) i AL. n F (i, .n) i2 Bi ... n F (i ... n) i, (2) where Q (1 .. n) i is the current value of the volumetric flow rate of the liquid product in the corresponding channel 1 .. .P regulation with a measuring signal frequency equal to F (i, .n) i.

2. In blocks 41 of the memory of these calculators read the values of densities p p) l ° g

mixable products at a temperature of 0 ° C and their coefficients A (1 .., G1) of volume expansion.,

3. The elements 50-1 ... 50-d of the memory of the assignment-j of the pick 12-1 record the values of the mass flow rates of the leading product, which must be maintained in the process of technological work and equal, for example, m, mi-m. ., mi-d. In the memory elements 51-1 ... 51-d, the other fugs enter the coefficients Krni, Kmii ... Kmd of the ratio of products entering the object 1 through pipelines of the first and second channels and equal to the ratio of their mass consumption.

„, GP2 - I ..GL2

Km - {-; Kt II

II

Km III

mi -i ta - in

GP2

etc

(3)

mi -in

where I, II, III ,,. d-conditional designations of operating modes of the technological object 1.

4, B blocks 55 of master setters 12-3 ... 12-P read the coefficients az ... n, L3 ... n relations (1), which determine the mass consumption of products in the channels Z ... n, respectively.

5. According to the consumption characteristics m i ... n f (cti ... n) of the actuators 2-1., 2-n, the coefficients K (1 ... n) are determined

 gears, meaning the angles of rotation of their throttling elements to change the consumption of products, for example, by 1 kg / s. In general, these characteristics have some non-linearity and depend on the magnitude of the pressure under which the products enter the feed pipelines (as a rule, pressure fluctuations do not exceed + 10-10%). Therefore, to estimate the Kev (1 ... n) coefficients, their average values are used, which have practically no effect on the accuracy and quality of the adjustment.

Data on coefficients Ko. (1 ... p) is written in the settings of blocks 10-1.,. 10-n multiplication codes.

6. The adjustment of each of the formers 11-1 ... 11-p is made by the average angular velocity VCp of rotation of the output shaft of the respective drive and the selected duration of the Hz adjustment cycle.

During the Hz time, the throttling elements of the actuator are rotated by an angle D (c) equal to

Aa (c) TC (4)

The code value of this angle is equivalent to the number of pulses MHz, read from the contents of the counter 57 during the time Hz. On the other hand, for the same period of time, the generator 19 generates N pulses of the reference frequency f0:

N Hzto. (five)

Then the coefficient is Kdel. frequency division by block 60 will be equal to

N tz f o f o

Mts

to - | h

. - tt

TC Vcp V,

wed

GCHISLO IMP.,

degree (6)

It means the number of pulses by which the contents of counter 57 decrease in the time required for the drive 3 to rotate the output shaft by a single angle, i.e. at 1 degree

The values of coefficients obtained from relation (6). for each of the control channels, they are recorded in a programmable memory of frequency dividers 60.

The setting of the counter 58 corresponds to the additional duration tp min of the control pulses necessary to compensate for the time of the driving of the drive 8.

In the initial state, the counters 13 and 14 are cleared, the element And 17 is closed, the switching element 20 of the block 18 is open. In converters x 6-1 ... 6-p, calculators x 8-1 ... 8-P and driver x 11-1 ... 11-n counters 23. 24, 42, 43, 57 and 58 and registers 25 and 36 are also set to zero, And elements 27, 45, 36, 64-66 are closed, keys 61-63 are open. Throttling elements of the actuators 2-1 ... 2-p are rotated by the angle Cnach (1 .p), selected based on the expected second expenditures of the mixed products at the beginning of the technological cycle. The switching element 49-1 of the setting device 12-1 is closed, the others are open and the mass flow rate of the leading product and the coefficient Kmi are generated at its outputs and must be provided in the first operation mode of the object 1. There is no information at the outputs of the other functional units of the device.

The device is put into operation after supplying products to the object 1 of the closure of the switching element 20 of block 18. This opens the key 21, and the voltage pulses from the output of the generator 19 of the reference frequency f0 begin to flow to the corresponding inputs of the 6-1 ... 6p converters, the formers 11 -1 ... 11-p and through the dividers 22 and 15 frequencies - to the inputs of the clock pulses of the calculators 8-1 ... 8-p and the counting input of the counter 13, respectively. The latter establishes a predetermined sequence.

the inclusion of the calculators 8-1 ... 8-p. I will organize a sequence of measuring cycles of duration ta. Within one cycle, the current value of the mass flow is calculated for each of the control channels and averaged results are obtained. For the calculations, the code information generated by the converters 6-1 .6-p is used. The principle of their operation is based

It is necessary to measure the duration of the periods 7i ... l of following the measurement pulses by counting the number of pulses qi. .n of the reference frequency f0 excited by the generator 19 during this time interval

one

qi. .n f 1 ... n TO

Ft ... n

fo.

In order to increase the accuracy of measurement, the accumulation of pulses of the reference frequency f0 is carried out over several periods, for example, 0 i periods. Inverter 6 for the time interval rt. N selects the code. Wherein

F / h- Sfo kF (7)

i- (i ... n) i KODF (i ... n) i KOD F (i ... n) i where Kp Sfo is the constant coefficient recorded in the memory of blocks 39.

The calculation of the mass flow rate, for example, the leading product, is carried out according to the command signals generated at the first output of the counter 13. At the same time, the Rc-value is read into the calculator 8-1

yes, and its trigger 44 is set to one state, opening element 45 and activating counter 42. The latter establishes the necessary sequence for switching on elements of computer 8-1, modifying the state of its circuit as follows:

- on the first clock pulse, unit 29 converts the FU code to the frequency Rc of the measuring signal TPR 4-1 by the ratio

(T);

- at the second and third clock pulses, blocks 31 and 32 of multiplying the codes and adder 35 convert the frequency Rc into the physical dimension of the parameters using the pouring characteristic (2) TPD 4-1

Qli AiFu2 + BiFu + Ci, where AI, 81, Ci are the approximation coefficients read from memory block 40;

-for the fourth and fifth pulses, the result obtained is written to register 37 using an adder 36;

- at the same time, on the fourth and fifth clock pulses, blocks 33 and 38 calculate the actual density p of the leading product at the temperature Tc measured by block 7-1 in accordance with the known equation:

p i -P (i) o ° c TTi i; (8)

- when the counter 42 is filled, a pulse signal is excited at its last output, by which another counter 43 is transferred to one state, and after a time interval equal to the setting of delay element 47 and sufficient for stable switching of counter 43, resetting the RS flip-flop si of the element Both 45 and counter 42;

- in addition, at the command of the delay element 47, block 30 divides the contents of register 37 by the number of 43 pulses read by the counter (in this case by 1), and the result block 34 multiplies by p i,

micp.i Qiipn; (9)

- when the second and subsequent command signals from counter 13 enter the calculator 8-1, it determines the current values in a similar way. It has a volumetric flow rate, accumulates the obtained results in register 37, averages them each time using block 30 and then calculates the micp by the ratio (9);

- by filling the counter 43 (after reading the z-pulse into it), the element E 46 is opened, as a result of which the voltage pulse generated at the output of the delay element 48 passes to the clock output of the calculator and to the inputs

reset the register 37 and the counters 43, returning them to their original state.

Similarly, the averaged values of the mass flow rates are determined.

m2cp.j, mscp.j ... gppsr.dl j-ro measuring cycle other computers on the information received at their inputs with TPD 4-2 ... 4-n from the outputs of the scaling blocks 7-2 ... 7 -P.

The end of the measuring cycle is fixed by calculating 8-n: a voltage pulse is excited at its synchronizing output, which sets the triggers to one state and opens

element 17, the start-up of the counter 14. The latter distributes the voltage pulses fc over the clock inputs of the remaining functional units of the device, providing the following execution sequence

calculations for adjustment of control channels:

- the first impulse is addressed to the 12 -... 12-p thuya control units, where it activates blocks 52 and 53 umnoheni

and the time interval is equal to the setpoint of delay elements 56 - blocks 54, these blocks determine the mass second expenses m {3 ... n) j products for which the control channels can be adjusted, start from third, dp of the measured expenses micp.j ... mncp.j, etc. (one):

fi (3 ... n) j az .n micpj t Lz psngg (n-i) j;

- with the trailing impulse arrives at the clock input of the pickers 12–2, which by this command calculates the tuning value of the mass flow maj of the product entering object 1 through the second channel:

GP2 Kmi micpj: (10)

- the third clock pulse triggers blocks 9-1 ... 9 - .P, by means of which the error signals Dm (1 ..n) j are calculated as the difference between the tuning and measured mass flow rates in the corresponding control channels:

A rrr.j tn - m-icpj, Arrt2j - maj - rri2cpj, ..., Amnj rrinj - mncpj;

- on the fourth clock pulse, blocks 10-1.,. 10-p translate error signals

in angles Aa (Y..n) j correction actuators 2-1.,. 2-n:

A "ij Kai Arm j, A" 2j Ko. Am2j, ...

Aanj Kn "Amnj;

- the fifth pulse is addressed to the clock input of the driver 11-1 and switches its circuit elements to the following state:

-In counters 57 and 58, the code values of the angle A угла ij and the settings tp mini are recorded, respectively.

-block 59 compares the angle of Bowers j with the fixed deadband of Dazn and with Doi j. a larger absolutely absolute value A 3n, forms at its output an electrical signal that opens element AND 64 to pass a clock to the S input of the trigger 68;

the trigger 68 is set to one and opens, respectively, element 65 and 66 (depending on the sign of the error signal Ami), and then one of the keys 62 or 63, connects the corresponding input of the drive 3-1 to the supply bus UY;

-drive 3-1 rotates the throttling elements of the actuator 2-1 in the direction of opening or closing, changing the second consumption of the leading product;

- after the time interval equal to the minimum required duration tpmin of the control command, the output of the counter 58 excites a signal that zeroes the frequency divider 60 and sets the trigger 67 to the single state of the key 61;

- pulses from the output of divider 60, for example, start coming in and subtracting the input of counter 57, gradually reducing its content to zero or a certain final value, depending on the value of the correction angle C for j;

-if Doi j; less than Doi4 (4), then C1-etch 57 is zeroed until the end of the adjustment cycle and the pulse signal generated at its output returns the trigger 68, turns off the elements 65, 66, 62, 63 and provides the drive input 3- one;

-If L 1 j exceeds Dat c, then the contents of counter 57 are not read to zero and the restructuring of the actuator 2-1 continues in the next cycle, but already relative to the new correction angle (, n-1) calculated by blocks 8-1. , 10-1 with a change in second consumption of the leading product, etc.

The sixth and subsequent sync pulses, excited at the outputs of the counter 14, alternately start the shapers 11-2., .11-n, tune the actuators 2-2 .., 2-n at the angles Doi j ... D On j is similar to the above.

By filling the score of the IC 14, it is reset and reset to the initial state of the RS flip-flop 16.

and

To increase the accuracy of the flow rate and the volume flow rate, in each of the 6-1 ... 6-p converters, RS trigger 26 and element 27 are included in the circuit, through which

5 iogap-lzovano filling counter 24 strictly on the front edges of the measuring impulses FI .. p. namely, the first pulse ri p written to counter 23 sets in one state the trigger 26,

10 opens element 27 and thus connects the output of the generator 19 of reference frequency f0 to the counting input of the counter 24. After passing S pulses of the measuring frequency FL, FL. At the overflow output of the counter 2C, a signal is triggered which translates — trigger 26 into the initial state, closing element AND 27. At the same time, the contents of counter 24 are written to register 2. Then the frequency measurement cycle

20 PI. N is repeated.

To change the performance of the object 1, the setting device 12-1 switches, for example, the switching elements 49-1 and 43 2 to activate the memory elements 25 50-2 and Y-2. At the outputs of this rear part, new values of the mass ratio and product ratio are set. equal, respectively, to JT or Ktz of the initial data, perceived by E-1, 10-1 blocks as the appearance of the error signal of the corresponding depth and polarity and recalculated into a correction angle code, which is then reflected by executive elements

35 2-1 Corresponding to the change in the mass flow rate of the leading product and the new value of the Km coefficient, the flow rate controllers of the second and second channels are rebuilt to fully compensate for all the resulting error signals.

The proposed device provides for the regulation of the mass consumption of several mixed products practically

45 for any dependencies between them and with the optimal duration of transient modes. At the same time, high accuracy and good quality of regulation are achieved in a wide range of mass changes.

Claims (3)

50 expenses of all mixed products. Claim 1. Device for controlling mass flow rates of mixed products, containing a block of time intervals 55 the first and second pulse counters, the elements of the And and n control channels according to the number of mixed products, each of which includes a turbine flow controller installed in The product feed line in front of the actuator connected to the drive output is: flow adjuster, so that, in order to improve the accuracy and quality of control when changing the mass flow ratio in a wide range, the device. contains RS-trigger, frequency divider, in (each control channel - temperature sensors installed in the corresponding product supply pipeline before the turbine flow converter, scaling unit, frequency-code converter, mass calculator flow rate, code reading unit, code multiplication unit and control command driver, the RS flip-flop output connected to the first input of the element, the output of the frequency divider connected to the counting input of the first pulse counter, the first output of the block of time intervals to the inputs of the reference signals of all converters frequency code and control command drivers, second output with inputs of clock pulses of all calculators of mass flow, with input of frequency divider and through the second input of element I with counting input of second account Pulse ikka, the overflow output of which is connected with its zeroing input and with the RS input of the RSmger, the 3rd input of which is connected to the clock output of the mass flow calculator of the nth control channel, the outputs of the second pulse counter are connected to the clock inputs of the flow rate controllers, respectively starting with the second one, subtraction code blocks, code multiplication blocks and control command drivers, tact inputs of the mass flow calculators are associated with the corresponding outputs of the first pulse counter, the output is full and which is connected to its own input, and each control channel, the outputs of the turbine temperature converter and temperature sensor, respectively, through a frequency converter - code and a scaling unit are connected to the first and second information inputs of the mass flow calculator, the information output of the code subtraction unit in each through the multiplication unit, the control channel is connected to the information input of the control command generator, the other input of which is connected to the sign output of the subtraction unit to odes, the shaper outputs of the control commands in each control channel are connected to the corresponding control inputs of the drive, the first output of the flow master in each control channel is connected to the first informational input of the unit of codes, the second input of which is connected to the informational output YOU AND: LEU; ERG. mass flow of its channel ragun-p-1 vania, the second input of the multiplication unit in each control channel is connected by a t setpoint of the transfer coefficient, the second output of the flow setter of the first control channel is connected to the first input 0 setters for the flow rate of the second control channel, the second Elodod of which is connected to the first inputs of the flow controllers of the subsequent channels and to the information output of the mass flow calculator 5 of the first channel, and the second setpoint input of the flow rate of the nth control channel is connected to the information output of the mass flow calculator of the previous control channel. 0 2. The device of claim 1, wherein the calculator of the mass flow rate of each control channel contains two block division codes, four code multiplication blocks, two code adders. PR5 gist, code reading unit, five memory blocks, two pulse counters, two AND elements, RS flip-flop and two delay elements, the first input of the first code dividing unit being the first informative input of the calculator, the output of the code dividing unit is connected to the first input of the first multiplication unit; and the first and second inputs of the second multiplication unit. the outputs of blocks of multiplication of codes through a serially connected first and second adders of codes are connected to the bit inputs of the register, the output of which is connected to the first input of the second block of codes and the second input of the second 0- code adder, the output of the second code division block is connected via the third block multiplying unit to the information output of the calculator, the second information input of which is connected to the second input of the third block of code multiplication through serially connected fourth block multiplication codes and the first code multiplying block element and is connected to the counting input 0 of the first pulse counter, the outputs of which are connected to clock inputs, respectively, of the first code division unit, the first, second and fourth code multiplication units, code adders, code calculation unit and the register overwriting input, the overflow output of the first pulse counter is connected to the counting input of the second the pulse counter and through the first delay element to its zeroing input, to the R input of the RS flip-flop, to the project input of the second block of codes and the input of the second delay element, connected to the clock the input of the third multiplication unit and, through the second element I, with the outputs of zeroing the register, the second counter of the calculator's output pulse, the control input of which is connected via the S input of the RS flip-flop to the second input of the first And element, the output of the second pulse counter is connected to the second input of the second block of codes, the overflow output of the second pulse counter is connected with the second input of the second element I, the second input of the first block of code division is connected to the output of the first memory block, the third input of the second block and multiplying the code is connected to output of the second memory block, the third input of the first adder codes - yield flare third memory, a second input of the first Bloch Code multiplication is connected to the output of the fourth memory block, and the second inputs of the fourth code multiplication block and the code reading block are connected to the corresponding outputs of the fifth memory block. 3. Device pop, 1, characterized in that the flow control unit of the n-th control channel contains a memory block, a delay element, an adder and two code multiplication blocks, the first inputs of which are connected to the first and second inputs of the control devices, respectively, and the second inputs - with the corresponding outputs of the memory unit, the outputs of the multiplication units through the adder are connected to the output of the setter, the control input of which is connected to the clock inputs of the blocks of multiplying codes and through the delay element to the clock input of the adder. FIG. 2 1 Open Zahr About 1 . sign 7 jot