JPS59129305A - Boiler main steam pressure control system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a boiler automatic control device that can maintain a predetermined pressure according to the load even when the distance between the boiler and the equipment that consumes the steam generated by the boiler (hereinafter referred to as load) is long. This is related to the main steam pressure control method for boilers that reliably supplies steam of 100% to 100% of the load.In general, boilers supply high quality (constant pressure, constant temperature) steam to the load regardless of load fluctuations. is required to be supplied.

Conventionally, the main steam pressure control of such a boiler has been performed using the following methods 1) and 2.
), each of which has the following problems.

1) Method based on boiler outlet steam pressure detection This is a control method based on the steam pressure generated at the boiler outlet, so if the distance between the boiler and the load becomes long, the steam pressure fluctuations on the load side due to load fluctuations will cause the steam pressure at the boiler outlet to increase. It takes time for the change to be detected as a pressure change, which delays the compensatory action on the boiler side for the change in load-side steam pressure, making it difficult to maintain the load-side steam pressure.

2) Receiver pressure sensing method, i.e. for distributing steam to multiple negative 4tlI;
When installing a receiver (1-Yu tank) to collect steam from other steam generation sources, there is a method to detect the pressure of the receiver, but in this case too, if the distance between the boiler and the receiver is long, the receiver pressure This causes hunting (repeated overshifting), making it difficult to stably supply steam to the load connected to the receiver.

For this reason, 1. Currently, it is common to monitor the steam pressure on the load side and to manually intervene by an operator based on advance notice of load fluctuations.

The present invention has been made in view of the above, and an object of the present invention is to provide a boiler main steam pressure control system that can stably supply a predetermined amount of steam to the load without delay in control even when the distance between the boiler and the load is large. This is the purpose.

The feature is that the boiler main steam pressure control system has a deviation calculation means for calculating the deviation between the boiler outlet steam pressure and its set value, and a pressure adjustment means for performing a predetermined e31irj calculation based on the deviation. The present invention is characterized in that means is provided for detecting fluctuations in load-side steam pressure due to fluctuations in steam pressure, and the control system is controlled in advance based on the output from the means.

Embodiments of the present invention will be described below with reference to the drawings. 1st
3 to 3 are block diagrams showing implementation sequences of the present invention.

First, FIG. 1 will be explained. INI, IN2
are the boiler outlet steam pressure and load side steam pressure signals, respectively. 1.1 is a hll difference calculator, and the baud f and Kawauchi given by the setters S1 and S2, respectively.

Generates a deviation signal between the set signal on the load side and the actual steam pressure. Reference numeral 2 denotes a function generator, which performs the following calculations using the load side deviation signal as input.

b) If the deviation signal is within the allowable upper and lower limit values for the load (variable settings), the pressure will be ``0''.

) If the deviation signal is outside the above tolerance range, a positive or negative value is output depending on the percentage of deviation. This signal is calculated as a boiler outlet side deviation signal by the correction calculator 4, and the PID calculator 5 executes advance correction control in the form of predicting fluctuations in the steam pressure at the boiler outlet due to fluctuations of negative 1i. Note that between the function generator 2 and the correction calculator 4,
0 or 0U in which the multiplier 3 for adjusting the correction width is inserted
T1 is a control output after PID calculation, and is connected to a lower control system.

FIG. 2 shows a method in which the correction calculation is performed on the pressure setting side at the boiler outlet, in contrast to the method shown in FIG. 1 in which the correction calculation is performed on the deviation signal on the boiler outlet side. In addition, in the same figure as well as in FIG. 1, it is possible to perform a deflection correction calculation on the boiler output steam pressure signal.

FIG. 3 shows a control mode selection changeover device for the method shown in FIG. 1, which selects both simple boiler outlet pressure control without advance correction control and load side pressure control, and control mode commands IN3, l: When N4 is “ON”, all a
side, when it is 'OFF', selects the b side signal.IN3 is the load side pressure control mode command, and the signal switch 6.6 selects the a side of the switch based on this signal (in addition, the signal switch 6.6 selects the a side of the switch.
This is a dedicated PID calculator for the 1-boiler outlet pressure control mode and the load-side pressure control mode, and since the control parameters change based on dead time and response delay, it is designed to deal with such fluctuations. ing. IN4 is a correction control mode command, and the signal switch 6 selects the a side of the switch based on this signal to perform advance correction control. In addition,
Signal IN3.

If both IN4s are OFF, the control mode will be based on the signal switching outlet pressure.

As described above, according to the present invention, when the distance between the boiler and the load connected to it is long, fluctuations in the steam pressure on the load side are detected, and if the fluctuation range is within the allowable range,
If the main steam pressure is normally controlled using the boiler outlet steam pressure, but the allowable range is exceeded, the main steam pressure control system performs advance correction control based on the percentage of the exceeded range. This has the advantage of quickly compensating for fluctuations and making it possible to supply steam stably with respect to the load.

The present invention is applicable not only to boilers (steam generators) but also to pressure control of V-equipment systems that supply gas and liquid at a constant pressure in the general industrial field.

[Brief explanation of drawings]

1 to 3 are block diagrams showing embodiments of the present invention. Description of symbols 1.1... Deviation calculator, 2... Function generator, 3... Multiplier, 4... Correction calculator, 5, 5 ...PID outlet pressure setting device, S2
...Load side pressure setting device representative Patent attorney Akio Namiki Patent attorney Kiyoshi Matsuzaki wc1 Figure 2 Ot/Tl

Claims (1)

[Scope of Claims] l) A boiler main body comprising boiler-side calculation means for calculating the deviation between the boiler outlet steam pressure and its set value, and pressure adjustment means for performing predetermined adjustment calculations based on the deviation. In the steam pressure control method, there is provided a load-side calculation means for calculating the deviation between the steam pressure on the load side that consumes steam emitted from the boiler and its set value, and a predetermined value according to the deviation output from the calculation means. The boiler side is controlled in advance by predicting load fluctuations by providing a function generator that outputs an output, and correcting the deviation output from the boiler side calculation means based on the output of the function generator. Boiler main steam pressure control method. 2. The boiler main steam pressure control method according to claim 1, wherein the boiler side steam pressure set value is corrected based on the output of the function generator.