JPH0132406B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mixed coal/heavy oil combustion control device for a boiler plant that uses mixed coal/heavy oil as fuel, and in particular, to a mixed coal/heavy oil combustion control device that controls the combustion of a highly viscous mixed coal/heavy oil fuel in a stable manner at all times. Regarding equipment.

The prior art and its problems will be described with reference to FIGS. 1 to 4. Figure 1 shows a configuration diagram of the combustion equipment of a boiler plant that uses mixed coal and heavy oil as fuel. 1 is mixed coal heavy oil (hereinafter referred to as COM). COM is coal, oil
(heavy oil), mix (abbreviation)] A fuel injection pump,
The fuel injection pump 1 transports and pressurizes COM fuel to be supplied to the burner 6 of the boiler 5. Main pipe 23
The fuel flowing through is heated by the heater 22, passes through the main pipe flow rate control valve 7 and the sheath valve 8, and is combusted by the burner 6. In the burner 6, the fuel is combusted with steam injected from the spray steam pipe 9 via the spray steam flow rate control valve 10. 2 is a main pipe flow rate detector that detects the flow rate of fuel flowing through the main pipe;
3 is a main pipe pressure detector which similarly detects the pressure of the fuel, and 4 is a spray steam pressure detector which detects the pressure of the spray steam flowing through the spray steam pipe 9.

Figure 2 shows the header pressure PX- detected by the header pressure detector 3 when burning fuel in the configuration shown in Figure 1.
1 and the spray steam pressure PX-2 detected by the spray steam pressure detector 4, with the load as the horizontal axis. Here, the main pipe pressure PX-1 is equal to the spray steam pressure PX-2. It is always maintained at a constant differential pressure.

Figure 4 shows a control system diagram for conventional COM fuel combustion control. In the case of COM fuel, the fuel is a liquid like heavy oil, so the conventional heavy oil combustion control method is used as is for COM fuel. In Fig. 4, the main pipe flow rate detector 2
The COM fuel flow rate signal detected by the COM fuel flow rate signal and the signal that the flow rate request command 11 from the plant is sent via the function generator 12 are input to the subtractor 16 and subtracted, and the result of this subtraction is input to the proportional integrator 17. The output signal is proportionally integrated by the high signal selector 18,
The main pipe flow rate control valve 7 is controlled through the E/P converter 19. On the other hand, the difference between the main pipe pressure detected by the main pipe pressure detector 3 and the minimum pressure from the signal setting device 21 which sets the minimum pressure is detected by the subtractor 2.
0, and the result of this calculation is sent to the high signal selector 18.
This prevents the COM fuel pressure from falling below the minimum value required for stable combustion. In addition, the subtractor 13 , a proportional integrator 14, and an E/P converter 24 are provided to control the spray steam flow rate control valve 10.

As mentioned above, when COM fuel is combustion controlled using the same control method as heavy oil fuel, COM fuel is very viscous and its flow is not as smooth as that of heavy oil. In the conventional method shown in Fig. 4, which controls the main pipe pressure PX
There is a problem that -1 fluctuates as shown in FIG. 3, making combustion unstable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a COM combustion control device that solves the above-mentioned problems in the prior art and can perform stable combustion control even when using COM fuel.

In order to achieve the above object, the features of the present invention are as follows:
The structure is such that the flow rate of the COM fuel is directly controlled by the pressure of the main pipe through which the COM fuel passes. That is,
The COM flow rate is used as a precedent command so that the flow rate is predetermined by the plant command.
This command value is configured to be corrected so that the COM pressure becomes a determined pressure value.

An embodiment of the present invention will be described below with reference to the system diagram in FIG. In FIG. 5, 15 is a function generator;
25 is an adder, and the other components are the same as in the conventional example shown in FIG. Flow rate request command from the plant 1
1 is input to the adder 25 via the function generator 12, and the output of the adder 25 is applied to the main pipe flow rate control valve 7 via the E/P converter 19. is adjusted to a predetermined flow rate. On the other hand, the difference between the main pipe pressure PX-1 detected by the main pipe pressure detector 3 and the pressure signal that is converted into a pressure signal and sent out by the flow rate request command 11 passing through the function generator 15 is subtracted. A signal obtained by proportionally integrating the subtraction result by a proportional integrator 17 is added to an adder 25 and becomes a correction signal for flow rate control of the main tube flow rate regulator 7. Furthermore, as in the case of FIG. It is controlled by the signal that has passed through the subtracter 13, the proportional integrator 14, and the E/P converter 24 so that the differential pressure with respect to the pressure PX-2 is constant. According to the method of the embodiment shown in FIG. 5, the main pipe pressure PX-1 detected by the main pipe pressure detector 3 is directly applied to the control of the main pipe flow rate control valve 7, so that the main pipe pressure increases. It will no longer fluctuate.

As described above, according to the present invention, since the pressure in the main pipe through which COM fuel flows is stably controlled,
Combustion in the burner is stable and the optimum combustion required by the plant can be obtained.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a mixed coal heavy oil combustion equipment, Figure 2 is a diagram of the relationship between the header pressure, spray steam pressure, and load in Figure 1, and Figure 3 is an example of temporal fluctuations in the header pressure. 4 is a conventional control system diagram, and FIG. 5 is a control system diagram of an embodiment of the present invention. 1... Injection pump, 2... Main tube flow rate detector, 3
...Main tube pressure detector, 4...Spray steam pressure detector, 5...Boiler, 6...Burner, 7...Bus pipe flow rate control valve, 8...Shell cross section, 9...Spray steam piping, 10... Spray steam flow rate control valve, 11... Flow rate request command, 12, 15... Function generator, 13, 1
6,20...Subtractor, 14,17...Proportional integrator, 18...High signal selector, 19,24...E/
P converter, 21... Adder, 22... Heater, 2
3...Mother tube.

Claims (1)

[Claims] 1. In a mixed coal/heavy oil combustion control device that controls the combustion of a boiler in a thermal power plant that uses mixed coal/heavy oil, which is a mixture of pulverized coal and heavy oil, as fuel, the main pipe flow rate adjusts the flow rate of the main pipe that supplies mixed coal/heavy oil to the burner. a control valve; a main pipe pressure detector that detects the pressure of mixed coal heavy oil flowing through the main pipe; A main pipe flow rate control device that adjusts the main pipe flow rate control valve by correcting the flow rate command so that the pressure detected by the pipe pressure detector becomes the pressure determined by the plant command. Mixed coal heavy oil combustion control device.