JPH035665A - Boiler water temperature controller - Google Patents

Abstract

PURPOSE:To allow the controller to simplify the whole system by allowing the controller to input a signal in regard to steam pressure impressed in a steam pressure controller to provide a temperature signal operation means by means of performing operation of a specific equation so as to impress a temperature signal obtained by said means in a temperature controller. CONSTITUTION:When a boiler is ignited, the temperature of boiler water increases along with time and steam pressure also heightens therewith. A temperature sigal operation means 5 is allowed to calculate a temperature signal (T) from an input stem pressure signal (P) with the use of an equation (I) to impress the temperature signal (T) in a temperature controller 43. The temperature controller 43 is allowed to output an operation signal as a boiler master signal to control boiler water temperature so that the increase rate of the temperature signal (T) is performed in that set by an increase rate setting means 45 until it reaches a boiler water temperature set value, for instance, 55 deg.C/hr or 110 deg.C/hr. For this reason, a plurality of temperature detectors for detecting the boiler water temperature become useless and the whole system is made simple in constitution.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a control device for can water temperature in a drum boiler, and more specifically, to a device for controlling can water temperature in a drum boiler, and more specifically, to a device for controlling can water temperature in a drum boiler without using a temperature sensor for measuring can water temperature. , relates to a device capable of controlling the can water temperature of a drum boiler.

<Prior Art> FIG. 3 is a functional block diagram showing an example of a conventional canned water temperature control device.

In the figure, LA and IB are pressure detectors that detect the main steam pressure of the boiler, and the two pressure detectors IA and IB are used by being switched by a switch 20 depending on the respective pressure range. 11.12 is a converter that converts the current signal from the pressure detector into a voltage signal, and also converts it into a standardized voltage signal of, for example, 4 mV to 20 mV.

2 is a steam pressure regulator which inputs a signal from a pressure detector selected by switch 20 and controls the main steam pressure to be equal to the set main steam pressure PS.

31 is a temperature detector that detects the temperature of the main steam, and 32 is a flow rate detector that detects the flow rate of the main steam. Each of these detectors is installed in a pipe line through which the main steam is output. For example, a thermocouple is used as the temperature detector 31, and a signal from the thermocouple is sent to the mV/voltage signal converter 10. The signal is applied to a divider 34 via a converter 12 and a linearizer 33. This divider 34 is adapted to correct the flow signal from the flow sensor 32 applied via the transducer 11.12 by the temperature signal. 35 is a dead time compensation circuit which receives the signal from the divider 34 as input.

Reference numeral 30 denotes an adder that adds the signal from the steam pressure regulator and the flow rate signal passed through the dead time compensation circuit 35. The signal from this adder 30 passes through a switch 40 and becomes a mask signal for the boiler.

4 is a block for controlling the temperature of canned water, and includes a plurality of temperature detectors 41a and 41b for detecting the temperature of canned water.

41c. 42 is each temperature detector 41a.

43 is a temperature controller that inputs the average can water temperature signal from the calculator 42; 44
45 is a setting means for setting the target value of canned water temperature; 45 is a setting means for setting the rate of increase in canned water temperature; 46 is a limiting circuit for the output signals from each of these means, and the signal from here is sent to the temperature controller. 43 as a setting signal. Depending on the boiler type, the limit value for the temperature rise rate of canned water is 55°C/hr for natural circulation boilers, and 110°C/hr for forced circulation boilers. The rate of increase becomes the limit value.

In the device configured in this way, when controlling the main steam pressure and steam flow rate, the switch 40 selects the signal on the adder 30 side and outputs this as a mask signal, and when controlling the canned water temperature, the switch 40 is turned on. A signal from the temperature controller 43 is selected and output as a mask signal.

<Problems to be Solved by the Invention> The temperature of canned water varies within a range of 0 to 350°C, and also varies depending on the installation location of the temperature detector. For this reason, in the conventional device, in order to obtain an accurate canned water temperature, a plurality of temperature detectors are installed at different locations, resulting in a problem that the overall configuration becomes complicated.

The present invention has been made in view of these problems, and provides canned water temperature control that eliminates the need to install multiple temperature detectors, that is, eliminates the need for the configuration shown in the shaded area in FIG. The purpose is to provide equipment.

Means for Solving the Problems> The present invention for achieving the above-mentioned objects is provided with a steam pressure controller for controlling the main steam pressure of a boiler, and a temperature controller for controlling the boiler water temperature, and for each adjustment. In the canned water temperature control device which uses a signal from a meter as a master signal of the boiler, a signal related to the steam pressure P applied to the steam pressure regulator is input, and 1'-P"'X100, T: Canned water temperature (saturated steam temperature) P: Temperature signal calculating means for obtaining a canned water temperature signal T by calculating steam pressure is provided, and the temperature signal obtained by this calculating means is applied to the temperature controller. It is configured to do so.

Effects> The pressure range for controlling the can water temperature in a drum boiler is approximately 0 to 100 kg/am2g. In this range, the can water temperature T and the steam pressure P have the above-mentioned relationship.

The temperature signal calculation means uses this relationship to calculate a temperature signal from the steam pressure. This makes it possible to control the temperature of canned water without installing multiple temperature detectors.

<Example> Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, the same parts as those in FIG. 3 are designated by the same reference numerals, and their explanations will be omitted. In the present invention, in the block 4 for controlling the canned water temperature, a temperature signal calculation means 5 is provided which inputs the steam pressure signal P applied to the steam pressure regulator 2, and the temperature signal T obtained here is used to adjust the temperature. The configuration is such that the voltage is applied to a total of 43 signals.

This temperature signal calculation means 5 calculates, for the steam pressure signal P,
The temperature signal T is obtained by performing the calculation shown in the following equation.

T-P''

FIG. 2 is a diagram showing the operating state at startup.

Initially, the switch 40 selects the signal from the temperature controller 43.

In general, drum boilers use subcritical pressure (169, 56
6°C) region, and it is thought that there is virtually no use of vapor pressure in regions beyond this range. In the range up to the subcritical pressure region, the average can water temperature has a close relationship with the steam pressure P, and the relationship between the two can be expressed in the old style.

When the boiler is ignited, the temperature of the canned water rises over time, and the steam pressure also rises accordingly, as shown by the broken line in FIG. The temperature signal calculation means 5 calculates a temperature signal T from the input steam pressure signal P, and applies the temperature signal to the temperature controller 43. The temperature controller 43 receives this temperature signal T.
The operating signal is output as a boiler master signal so that the rate of increase of the canned water temperature increases at the rate of increase set by the rate of increase setting means 45, for example, 55°C/hr or 110°C/hr, until the canned water temperature target value is reached. Perform temperature control (part marked ■).

When the can water temperature reaches a temperature corresponding to the steam pressure, for example 70Kg/Cm2g, the switch 40 switches the steam pressure regulator 2
In addition to selecting the signal from , the ventilation pressure is controlled to be constant in order to ventilate and inject steam from the boiler into the turbine (part ■).

In addition, in the part (■), pressure increase control is performed to achieve the rated conditions of subcritical pressure (169° C., 566° C.).

<Effects of the Invention> As explained in detail above, according to the present invention, the temperature of canned water is determined by calculation using a steam pressure signal for steam pressure control, and the temperature of canned water is detected. This eliminates the need for multiple temperature detectors for temperature control, and allows for a simple configuration of the entire system.

[Brief explanation of drawings]

Fig. 1 is a functional block diagram showing one embodiment of the present invention;
The figure is a diagram showing the operating state at startup, and FIG. 3 is a functional block diagram showing an example of a conventional canned water temperature control device. IA, IB...Main steam pressure detector 2...Steam pressure controller 31...Temperature detector 32
...Flow rate detector 4...Canned water temperature control block 40...Switch 43...Temperature controller 44
Canned water temperature target value setting means 45 Canned water temperature increase rate setting means 5 Temperature signal calculation means

Claims (1)

[Claims] The boiler includes a steam pressure controller for controlling the main steam pressure of the boiler and a temperature controller for controlling the boiler water temperature, and uses signals from each controller as a master signal for the boiler. In the canned water temperature control device, a temperature signal calculation means is provided which obtains a canned water temperature signal T by inputting a signal regarding the steam pressure P applied to the steam pressure regulator and performing the following calculation. A can water temperature control device characterized in that a temperature signal T obtained by a calculation means is applied to the temperature controller. T=P^1^/^4×100 However, T: Canned water temperature (saturated steam temperature) P: Steam pressure