SU398932A1 - SYSTEM OF AUTOMATIC STABILIZATION OF TEMPERATURE1 AIR REGENERATORS INSTALLATION SYSTEMS - Google Patents

Description

one

The automatic temperature stabilization system can be used in the field of automatic control of the heat exchanger mode.

A known system for regulating the temperature of steam of regenerators, which equalizes the average temperatures of all devices with the subsequent regulation of the vapor pressure, which is a given average temperature.

The proposed system differs in that in it temperature sensors are connected to the inputs of shift moment regulators through an additionally installed push-pull discrete comparison element, the inputs of which are connected to the command device and to the controllers, and additionally installed a switch connected in series and a hydraulic resistance control device whose input connected to the output of the switching mechanism, and the output of the switch is connected to the input of the command device.

This makes it possible to improve the quality of regulation and provides automatic temperature stabilization in plants with groups of three regenerators.

FIG. 1 shows a diagram of the system of automatic, temperature stabilization of regenerators; in fig. 2 - system operation diagrams.

The system contains regenerators I-III, ..., 1g-III; switching mechanism 1, command electromechanical devices 2 and 3, switch 4, devices for monitoring 5 hydraulic resistance of regenerators, switching moment shift regulators 6, ..., 6, - and 7, ..., 7j, discrete elements of comparison 8, ..., B, measuring blocks 9, ..., 9, logical blocks 10, loop control flow controller

flow 11, flow regulator direct flow 12, the setting device 13, the throttle control bodies 14, ..., 14 ;, the switching valves 15 and temperature sensors 16, ..., 16g. With automatic stabilization of the temperature regime of the regenerators, three types of control circuits operate simultaneously. With the temperature equalization circuit in the group of regenerators, information about the temperature of the regenerators enters the discrete

comparison element 8.

The discrete element of comparison is triggered two times in each switching cycle by the signals received from the command electromechanical device at certain

predetermined moments of the cycle la and 2a. At the output of a discrete comparison element, during the period of its operation, signals are formed that are proportional to the difference between the actual and setpoint temperatures of one of the regenerators, which is taken as the reference, and the other two are compared. For example, if the reference is the third regenerator (see Fig. 2, where Qh and Qo are flow rates of the forward and reverse flows, respectively), then proportional (Ti-Gsh) signals are generated at times 2a, and (Hz-Gsh) at times la. The signals at the output of the discrete element of the comparison are generated alternately in one-tick cycle for the reference and one of the compared regenerators, and in the next step for the reference and the other of the compared regenerators. The output signal tcp duration is determined by the time required to work out the greatest possible mismatch by the corresponding motor of the command electromechanical device, and is determined by changing the signal duration 20 from its master part. As a result of the moment shift and the switches at points a and b, the ratios between the durations of the forward and reverse flows flowing through each of the regenerators 25 change, so that the differences between the set and actual values of the temperatures in each of the regenerators tend to zero with the proportional-integral control law . Regulation of the shift moment of re-30 key at two points provides equalization of temperatures between all regenerators of the group while maintaining the total duration of the cycle c. In order to select a reference regenerator, control of their hydraulic resistance is carried out. The hydraulic resistance is estimated according to the ratio of forward or reverse flow durations through each of the regenerators.40 The regenerator, the forward flow duration through which is the largest in this group or, respectively, the return flow duration is the smallest at a stable temperature, has a minimum hydraulic resistance of 45. A regenerator having a minimum hydraulic resistance is taken as a reference, and the shift of non-switching moment 50 of two other regenerators is controlled relative to it. The switching moment signals, which allow judging the duration of the forward and reverse flows through each of the regenerators, are fed to a hydraulic resistance control device, which can be used as an electric watch with automatic start and reset. Comparison of blow durations allows determining a regenerator with a minimum hydraulic resistance. 60 The signal that any of the regenerators have reached the minimum value of hydraulic resistance in their group enters the switch, which automatically switches the control circuits so that the switch 65 desired points of the cyclic diagram. With a circuit equalizing the average temperatures between pairs of regenerators, the average temperatures of the soil of the regenerators are equalized with respect to the "command group, i.e. the group with the throttle valve as wide as possible. With the full opening of the throttle valve of one of the groundwater, the information comes from the limit switch to the selection machine of the comaid group, which switches the temperature measurement circuit to provide a comparison mode relative to this group. For example, the regulatory body of the lth group is as open as possible. In this case, each of the (-1) -th group is compared with the -th group, and the regulating effect is applied to the compared groutz. Regulatory impact is received by the operator. In the case of full opening of the regulatory bodies of several groups of regenerators, a comparison is made with respect to that of which, the regulatory authority of which is fully opened last. In the process of long-term operation, the hydraulic resistances of the regenerators and, accordingly, the reverse flows change arbitrarily, so over time the regulator of any of the groups can become as open as possible, then the automatic selection of the command group switches the measurement circuit relative to this group of regenerators. For example, if the k-th group received a regulating action and its regulator was fully opened, sending information to the automatic selection of the "command group", then it becomes the "command group." With the overall temperature control loop, all signals proportional to temperature deviations from the given each regenerator are summed algebraically and the total signal goes to the loop flow regulator, which produces an effect on the loop loop regulator, thereby changing the temperature of all the regenerators, the subject invention An automatic temperature stabilization system for regenerators of an air separation unit, comprising a switching mechanism whose outputs are connected to the switching valves, and the input is connected to a control device; controllers of direct and loop flows, to the inputs of which temperature sensors are connected through serially connected measuring unit and logic unit, and outputs are connected to throttle regulating bodies; shift moment shift controls whose outputs are connected to the command

device, and setting devices, characterized in that, in order to improve the quality of control, in it temperature sensors are connected to the inputs of shift moment-shift controllers through an additionally installed push-pull discrete comparison element, the inputs (of which are connected to the command

6

The device and to the setters, and additionally installed are a series-connected switch and a device for controlling the hydraulic resistance, the input of which is connected to the output of the switching mechanism, and the output of the switch is connected to the input of the command device.