SU945849A1 - Regulator - Google Patents

Description

(54) REGULATOR

one

The invention relates to automatic control and regulation and can be used to build temperature control systems for heat exchangers of oxygen plants, in particular, a unit of nitrogen regenerators.

The nitrogen regenerator unit contains three regenerators. At each time, one of the regenerators passes a direct (working) gas flow (Q, Q. Qi) which cools and heats the nozzle of the regenerator, another - the reverse gas flow and the third - non-balanced jj (loop) gas flow ( Qp). Both reverse and loop gas flows cool the nozzle of the regenerators and prepare it for cooling the direct flow gas. Every three minutes the regenerators are switched, i.e. The switching cycle consists of three periods: working, reverse and loop left. At the end of the working periods, the temperature (T,, T, Tj) of the cooled gas at the outlet of the regenerators is measured. Pressure (P) and flow rate gas flow, loop gas flow rate are also measured.

In addition, regenerators are subject to the influence of uncontrolled disturbances, which significantly change their properties of the regenerator switching cycle.

The characteristic of the regenerator on the channel has a non-linear appearance. In the working range of variation of the flow rate and pressure of the gas passing through the regenerator, the model of the regenerator through the channel L f-DT, Qj, dT and DR dT can be taken as a prolortional link. The inertia from cycle to cycle can be neglected.

The control actions are the forward flow and loop loop flow rates for each regenerator. The purpose of control is to stabilize the temperature; cooled gas at the end of operating periods, subject to the maximum possible flow rates of the direct flow gas. Known regulators are known, by means of which the regulation of the temperature regime of heat exchangers is carried out only by changing the amount of gas in the loop flow l. The disadvantage of these regulators is that they do not provide a high degree of stabilization of the temperature of the cooled gas at the outlet of the regenerators at its maximum possible flow rates. The closest to the proposed technical entity is a controller that contains the first extrapolator and the first comparison unit connected in series, the first low frequency filter, the inverse object model and the second comparison unit, the second input of which is connected to the output of the first delay block t2j. The aim of the invention is to improve the accuracy of stabilizing the temperature of a gas at its maximum possible consumption. The goal is achieved by the fact that the controller contains the first setter, the second and third delay blocks, the smallest value selection block, the first switch connected in series, the fourth delay block, the second switch, the third comparison block, the first scaling block, the fourth comparison block, the third the switch, the fourth switch, the fifth unit of comparison, the second low-pass filter, the second scaling unit and the subtractor, the second setter, successively connected, the sixth unit of comparison, the third filter, The frequency and the third scaling unit, connected in series by the second extrapolator, the fourth scaling unit and adder, the output of which is connected to the input of the first delay unit, the output of the second comparison unit through the serially connected subtractor, the first extrapolator, the first switch, the second delay unit and the smallest value selection unit are connected to the second inputs of the adder and the third unit compared, the second output of the fourth switch is connected to the input of the first comparison unit, the output of the first Atchik connected to the second inputs of the fourth and fifth vttokov comparison, the output of the third magnetruya unit connected to the third p.xorow vpas ggatel, the second output of the first switch through the third delay unit connected to the second inputs of the unit of the smallest value and the second switch, the output of the fourth delay connected to the third input of the smallest selection unit; the first input of which is connected to the third input of the second switch; the output of the third low-frequency filter is connected to the input of the second extrapolate pa. The drawing shows a block diagram of a temperature control unit for heat, exchangers, for example, a unit of nitrogen regenerators. In black, the same designations are used: TfC-f T (l), T (i) is the temperature of the cooled gas at the outlet of the first, second, and third regenerators, respectively; T - set the temperature of the cooled gas; P ({) is the flow pressure of the gas; 71 - signal about the end of each period; f, (1) - loop gas flow rate; Q (i), Qy (iy, Q (i) is the flow rate of the direct flow gas, respectively, for the first, second and third regenerators. The temperature control of the heat exchanger of 1X devices, for example, the nitrogen regenerator unit, contains the fourth switch 1, the first unit 2 compares , first low-pass filter 3, inverse object model 4, second comparison block 5, calculator 6, first delay block 7, first extrapolator 8, first switch 9, second 10, third 11 and fourth 12 delay blocks, selection block 13 the smallest value, the adder 14, the first master 15, Fifth comparison unit 16, second low-frequency filter 17, second scaling unit 18, second setting unit 19, sixth comparing unit 20, third low-frequency filter 21, third scaling unit 22, second extrapolator 23, fourth scaling unit 24, second switch 25 , the third comparison unit 26, the first scaling unit 27, the fourth comparison unit 28, the third switch 29. The controller works as follows. After the end of each working period, for example, in the first regenerator, using the fourth switch 1, the signal J on one of the inputs of the first comparison unit 2 signals the temperature T (i) of the cooled gas at the outlet of the first regenerator, and on one of the inputs of the fifth block 16 Comparison

The flow rate signal Q (i) of the direct flow gas in the first regenerator. Similarly, by signal 3, the first 2 and fifth 16 comparison units are signaled about the temperature of the cooled direct-flow gas, on the second and third regenerators.

From the signal T ;, (-i) in the first comparison unit 2, the signal T is subtracted from a predetermined temperature of the cooled gas. The signal about the difference obtained through the first low-frequency filter 3, in which the useful component of this signal is extracted, is fed to the inverse model 4 of the object through the channel, the change in the gas flow rate of the looped flow AQp - the change in the temperature of the cooled gas. DT without delay. The inverse model 4 of the object is represented as a proportional link. At the output of the inverse object model 4, a signal is received on the adjustment of the loop gas flow rate during the (i -1) th control period. Subtracting the correction signal in the second comparison block 5 from the signal from the output of the first delay delay 7, i.e. From the signal about the flow rate Qn (1-1) of the petpay flow gas in the (fl) -oM control period, we get a signal about the estimate of the ideal flow rate of the loop flow gas. In other words, we get the signal about the flow rate Q (-il) control period to obtain a cooled gas temperature equal to a predetermined value.

. The value of Q (-5-1) is obtained for the conditions of the actual pressure P and the flow rate of the direct flow gas at the -i th control cycle. Further, the Q J, (i-l) values are recalculated based on the conditions of the baseline, in particular, the mean pressure and maxi ". Maximum possible direct flow gas flow. To do this in block 5

Comparison of the forward flow signal Q (4), for example, on the first regenerator, subtracts the signal on the maximum possible flow from the first setter 15. The signal from the output of the fifth comparison unit 16 through the second low-frequency filter 17, in which the useful component of this signal goes to the second scaling unit 18, where it is multiplied by a conversion coefficient. Thereby, the increments of the flow rate of the direct flow gas are converted into equivalent temperature effect increments of the flow

loop gas flow. In the comparative block 2O, the signal about the measured pressure P () of the gas is subtracted from the signal about the base gas pressure coming from the output of the second setter 19. The signal from the output of the sixth block 20 of the comparison passes through the third low-frequency filter 21, in which the useful component is of this signal, to the third scaling unit 22, where it is multiplied by the conversion factor and, thus, recalculated in loop gas flow increments. In the subtractor 6, the signals about the gas flow increments of the loop flow coming from the output of the second 18 and third 22 scaling units are subtracted from the signal 9j (-i-l). At the output of the subtractor 6, a signal is obtained about the ideal flow rate of the loop gas, calculated by calculation from the condition of the maximum flow rate and the base pressure of the direct flow gas. This signal reflects the effects of uncontrolled disturbances acting on the control object.

Claims (2)

The signal from the output of the subtractor 6 goes to the first extrapop 8, made, for example, as a boosting link, where it is extrapolated to three calculation cycles (three periods). The extrapolated signal through the first switch 9, which operates according to: the signal L enters the second block 10 of the delay,. if the working period ended in the first regenerator, to the third delay unit 11, if the working period in the second regenerator ended, and to the fourth delay unit 12, if the working period in the third regenerator ended. From the outputs of the second 10, third 11 and fourth 12 blocks of the delay, the signals arrive at block 13 for selecting the smallest value, implemented, for example, in the form of a diode assembly. In block 13 for selecting the smallest value from the three signals, the signal with the smallest value is selected, on the basis of which the required gas flow rate of the loop flow is determined in the upcoming (-i + l) period by recalculating the smallest signal under the conditions of the expected gas flow of the forward flow . For this purpose, the output signal of the third low-frequency filter 21 is fed to the second extrapolator 23, where it is extrapolated for one period and then fed to the input of the fourth scaling unit 24, in which it is reduced by a conversion factor. The signal from the quarter output of the whole block 24 goes to one of the inputs of the adder 14, where it is summed with the signal from the output of the block 13 of the smallest selection. At the output of the adder 14, the signal about the required flow rate of loop gas for the upcoming period will be released. This signal arrives at the input of the first delay unit 7 and is one of the output signals of the controller. . Thus, the gas flow rate of the loop flow is calculated from the condition of the maximum flow rate of the direct flow gas at the potentially coldest regenerator, i.e. on that regenerator, for which the loop gas flow rate is the lowest. This loop gas flow rate is realized by the i.dl of the other two regenerators. The temperature of the cooled gas at their outlet is regulated by the flow rate of the direct stream gas. For this, the signals from the outputs of the second Yu, the third 11, and the fourth 12 delay blocks through the second switch 25, which operate on the signal U, arrive in the order of operation of the generators to one of the inputs of the third comparison unit 26. To the other input of the third comparator unit 26, a signal is output from the output of the smallest selection unit 13, which is subtracted from the signal of the P1 th reduced ideal loop gas flow rate. The difference signal is received at the first scaling unit 27, in which it is multiplied by a coefficient, as a result of which it is converted into a signal equivalent to the thermal effect of the increment of the flow rate of the direct flow gas. The signal obtained at the output of the first scaling unit 27 is subtracted in the fourth comparison unit 28 from the signal about the maximum possible gas flow rate of the loop flow received from the output of the first generator 15. The output signal of the fourth comparison unit 28 is fed to the input of the third switch 29, the output signals of which are fed to the inputs of the fourth switch 1 and are the output signals of the proposed controller for the required flow rates of the direct flow gas. When the temperature regulator of the heat exchangers is operating on the same cooler regenerator, the maximum possible flow rate of the gas is set, and the temperature of the cooled gas is regulated by changing) Loop flow rate of the loop loop. On two other regenerators of the cooled temperature. gas is controlled by varying the flow rate of the direct flow gas in the same control period, resulting in stabilization of the TON gas temperature at its maximum p The results of simulation modeling of control systems with known and proposed temperature controllers of heat exchangers show that using the proposed controller will reduce the variance of actual gas temperature deviations from the set by 15% and increase the efficiency of heat exchangers by 8%. This will give an economic effect on the order of 120 thousand rubles a year, not a single oxygen plant with an oxygen production of 6 5O million m per year. Claims of the Invention Regulator comprising a first ext - positioner and a serial first connected comparison serially, a first low frequency filter, an inverse object model and a second comparator unit, the second input of which is connected to the output of the first delay unit, characterized in that controller, it contains the first setting unit, the second and third delay blocks, the smallest value selection block, the first switch, the fourth delay switch, the second switch, the third comparison block the first scaling unit, the fourth comparing unit, the third switch, the fourth switch, the fifth comparing unit, the second low frequency filter, the second scaling block and the subtractor are connected in series to the second setpoint device, the sixth comparing unit, the third low frequency filter and the third scaling unit connected in series the second extrapolator, the fourth scaling unit and the adder, whose output is connected to the input of the first delay unit, the output of the second comparator unit through serially connected the subtractor, the first extrapolator, the first switch, the second delay block and the smallest value selection block are connected to the second inputs of the adder and the third comparison block, the second output of the fourth switch is connected to the input of the first comparison block, the output of the first setter is connected to the second inputs of the fourth and fifth blocks comparison, the output of the third scaling unit is connected to the third input of the subtractor; the second output of the first switch is connected through the third delay unit to the second inputs of the selection unit; the smallest vetgchiny minutes and the second switch, the fourth delay unit output is connected to the third input of the smallest value selecting unit, the first input of which is connected to the third input of the second switch, the output of the third low-frequency filter is connected to the input of the second extra-floor floor. Sources of information taken into account in the examination 1, Brodnsky V.M. and others. Production of oxygen. M., Metallurgists,. 1970, p. 366-367. 2. USSR author's certificate number 699490, cl. Q 05 B.11 / O1, 1978 (prototype).