JPS5830500B2 - Combustion control device and control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion control device that controls the temperature of a combustion chamber to a predetermined value, and more particularly to a combustion control device that prevents disturbances due to combustion transient phenomena when the furnace load changes.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment, in which heavy oil, which is fuel, is passed through a pipe 2 to a burner (not shown) in a combustion chamber 1, and is fed to a pipe 3.
Combustion air is supplied through.

Then, both are combusted within the combustion chamber 1. A temperature detector 4 is provided within the combustion chamber 1, and this temperature detector 4 measures the temperature within the combustion chamber 1 and applies a temperature detection signal to a temperature controller 5.

A predetermined temperature signal α is input to the temperature controller 5 as another input, and the temperature controller 5 compares the temperature detection signal with the predetermined temperature signal α and outputs a temperature adjustment signal.

The predetermined temperature signal α is a signal proportional to a predetermined temperature that is desired to be constant in the combustion chamber 1.

The temperature adjustment signal is applied to a fuel flow controller 6 and a multiplier 7.

The coefficient unit 7 multiplies the temperature control signal by the air-fuel ratio α and applies an air flow control reference signal to the air flow controller 8.

The piping 3 is provided with an air flow transmitter 9 that outputs a signal A proportional to the combustion air flow rate and an air control valve 10 that adjusts the air flow rate.

The air flow signal A from the transmitter 9 is applied to the controller 8, and the controller 8 compares the air flow signal A with an air flow control reference signal and outputs the air flow control signal to the control valve 10 for adjustment. The degree of opening and closing of the valve 10 is adjusted.

Further, the air flow signal A is applied to the comparator 11 as its own power.

Further, the pipe 2 is provided with a fuel flow rate transmitter 12, which outputs a signal proportional to the fuel flow rate.

This fuel flow signal is applied to a fuel flow controller 6 and a coefficient unit 13 that multiplies a predetermined air-fuel ratio α.

The signal B multiplied by the air-fuel ratio α from the coefficient unit 13 is sent to the comparator 11
is added to the comparator 11 as an input input.

Comparator 11 compares signals A and B and applies an output to fuel flow rate controller 6 at a predetermined time.

The fuel flow controller 6 uses the temperature adjustment signal from the temperature controller 5 as a fuel flow adjustment reference signal, compares it with the fuel flow signal from the transmitter 12, and outputs the fuel flow adjustment signal to the fuel flow adjustment valve provided in the pipe 2. Add to 14.

Therefore, the opening/closing degree of the control valve 14 is adjusted by the fuel flow rate control signal.

The comparator 11 is related to the fuel flow controller 6 as follows.

That is, when the air flow rate signal A and the signal B obtained by multiplying the fuel flow rate signal by a predetermined air-fuel ratio are B<,A, the comparator 11 does not output a signal, and therefore the fuel flow rate controller 6 adjusts the fuel flow rate as described above. The signal is compared with the adjustment reference signal and a fuel flow rate adjustment signal is output to the control valve 14.

When B>A, the fuel flow rate adjustment signal immediately before B>A is held, and the valve 14 is adjusted using this constant value, that is, the valve 14 is maintained at a constant opening/closing degree.

Therefore, in a normal combustion state, when a temperature change occurs in the combustion chamber 1, the temperature controller 5 obtains a temperature adjustment signal, controls the fuel flow controller 6 and the control valve 14, and also controls the predetermined air-fuel ratio. In addition to the air flow rate controller 8, the control valve 10 is controlled by multiplying the air flow rate controller 8.

This means that the predetermined air-fuel ratio is determined so that the theoretical air flow rate signal obtained by multiplying the fuel flow rate by the predetermined air-fuel ratio and the actually measured air flow rate signal are larger under normal combustion conditions. by.

This predetermined air-fuel ratio takes a value within a theoretical air-fuel ratio range.

When the load in the combustion chamber 1 changes rapidly, the air flow rate is insufficient compared to the fuel flow rate, so the theoretical air flow rate signal becomes larger than the measured air flow rate.

This resulted in the generation of black smoke and a decrease in combustion efficiency, but since the actual measured air flow rate is locked to the fuel flow adjustment signal just before it becomes smaller, the air flow rate is adjusted at a predetermined air-fuel ratio relative to the fuel flow rate. can be kept.

That is, if the load in the combustion chamber 1 suddenly changes, black smoke will occur due to lack of air, but in order to prevent this, the fuel flow rate is maintained as a constant fuel flow rate and air flow rate control is performed.

Conventionally, various combustion control devices have been devised and implemented in order to maintain a constant temperature within a combustion chamber.

However, there is a large difference in waste time and time constant between the air flow control system and the fuel flow control system, and even if adjustment signals are applied at the same time, the air flow control system is delayed, resulting in insufficient combustion air and incomplete combustion. In particular, there was a risk that this would occur when the load within the combustion chamber fluctuated.

For this reason, some control methods have been found in which the amount of change in the temperature control output is compared with a predetermined value, and the fuel flow rate is forcibly delayed depending on the magnitude of the change.

However, with such a control system, temperature control is substantially delayed, and the dead time of the control system as a whole increases, making it impossible to prevent disturbances due to combustion load fluctuations.

Therefore, the object of the present invention is to eliminate this conventional drawback and
It is an object of the present invention to provide a control device and method that can control temperature changes without delay, prevent disturbances due to lack of air, and prevent generation of black smoke.

In the present invention, when controlling the fuel flow rate by using the temperature control signal obtained by comparing the temperature signal in the combustion chamber with the set temperature signal as the fuel flow control reference signal, the actually measured air flow rate and the predetermined air-fuel ratio are multiplied. The measured fuel flow rate is compared with the actual fuel flow rate, and when the latter becomes larger than the former, the fuel flow rate is adjusted using the reference signal immediately before the increase.

Therefore, even if the load inside the combustion chamber changes rapidly, it is possible to supply an air flow rate that maintains a predetermined air-fuel ratio relative to the fuel flow rate.
This has the effect that delays in combustion control due to wasted time can be prevented and temperature fluctuations can be reduced.

In addition, in the present invention, when the air flow rate is compared with the actually measured fuel flow rate multiplied by a predetermined air-fuel ratio and the latter becomes larger than the former, the fuel flow rate is determined using the fuel flow rate adjustment reference signal immediately before the increase. may be adjusted as in the other embodiments shown in FIGS. 2 and 3.

Another embodiment shown in FIG. 2 is a control device in which the same parts as those in the embodiment shown in FIG. The comparator 11 compares the fuel flow rate with the fuel flow rate, and when the fuel flow rate becomes larger, the fuel flow rate adjustment reference signal is made constant.

Still another embodiment shown in FIG. 3 is a control device in which the same parts are denoted by the same reference numerals, and the measured air flow rate is divided by the measured fuel flow rate and then compared with a predetermined air-fuel ratio.

Further, the present invention may be implemented by analog calculation or digital calculation using a microcomputer, and can be implemented with various modifications without changing the gist thereof.

[Brief explanation of the drawing]

Figure 1 is a block diagram of one embodiment of the present invention, Figures 2 and 3
The figures are block diagrams of other embodiments. 1... Combustion chamber, 2.3... Piping, 4.
... Temperature detector, 5, 6, 8 ... Controller, 9, 12 ... Transmitter, 11 ... Comparator, 10, 14 ... ... Valve, 15... Divider.

Claims (1)

[Claims] 1. In a combustion control method that measures the temperature inside a combustion chamber and performs combustion control based on a temperature adjustment signal obtained by comparing this temperature signal with a predetermined set temperature signal, the temperature adjustment signal is multiplied by a predetermined air-fuel ratio. The air flow rate is controlled by comparing the measured air flow rate as an air flow rate adjustment standard, the fuel flow rate is controlled by comparing the temperature adjustment signal with the measured fuel flow rate signal as a fuel flow rate adjustment reference signal, and a predetermined air flow rate is determined based on the measured air flow rate. A combustion control method characterized in that when the actually measured fuel flow rate multiplied by a fuel ratio increases, the fuel flow rate is adjusted using a fuel flow rate adjustment reference signal immediately before the increase. 2. In a combustion control device that controls a fuel flow rate and a combustion air flow rate based on a temperature adjustment signal from a temperature controller that compares a temperature signal from a combustion chamber with a set temperature signal, a fuel flow transmitter that detects the fuel flow rate; a first controller that compares the output of the transmitter with the temperature adjustment signal and outputs a fuel flow rate adjustment signal that controls a control valve that adjusts the fuel flow rate; an air flow rate transmitter that detects the air flow rate; a second controller that compares the output of the transmitter with a signal obtained by multiplying the temperature adjustment signal by a predetermined air-fuel ratio and outputs a fuel flow rate adjustment signal that controls a control valve that adjusts the air flow rate; a comparison device that compares the air flow rate and the measured fuel flow rate multiplied by a predetermined air-fuel ratio, and applies an output signal to the first controller when the latter is larger than the former, and an output signal from the comparison device; A combustion control device characterized in that when the first controller receives a fuel flow rate adjustment signal, the first controller adjusts the fuel flow rate using a fuel flow rate adjustment signal immediately before input.