JPH01260212A - Master fuel change over device for multifuel boiler - Google Patents

Abstract

PURPOSE:To diversify the type of master fuel and extend the application range to a boiler, by providing the order of priority to each kind of fuel so that they may be a master fuel and further establishing both an upper limit point and a lower limit point which constitute the requirements for fuel change over. CONSTITUTION:A change over device 9 transmits a flow rate signal of fuel type A to a lower limit monitor 41, a pressure signal of the fuel A to an upper and lower limit monitor 47 and a temperature signal of the fuel A to an upper and lower limit monitor 48. Furthermore, master control signals of B, C, and D types of fuel are respectively transmitted to NOT circuits 44, 45, and 46, and priority No. 1 and other requirements are transmitted where the change over requirements are decided by an AND circuit 42. More specifically, the flow rate of the fuel A which ranks as No. 1 in priority, deviates from a specified range, a logic signal of 0 will be output from the upper and lower limit monitor 41, thereby turning the output of the AND circuit 42 into 0. Then, the signal transmitted from the switch over device 9 changes over the fuel demand to A fuel demand. When the A type fuel is separated from the master fuel, the AND circuit 42 equivalence becomes 1 and the B type fuel carries out pressure control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a master fuel switching device for a multi-fuel boiler.

[Conventional technology]

In the DAIGE, which uses multiple types of fuel, the main steam pressure is always controlled using one type of fuel, and switching to another type of fuel is performed manually each time. For example, in FIG. 3, a steam pressure signal 31 is sent to a subtracter 32, and this is used with a set value to create a control difference signal. The controller (PI) sends an operation signal corresponding to the control signal.
The boiler master signal is created by adding this signal and the main steam flow rate signal, which is a preceding signal, by the adder 34.

The fuel demand is obtained by subtracting the total fuel flow rate by the subtractor 35, and the signal is switched by the manual switch 36 and sent to each fuel operating end 39 via the controllers 37 and 38 for each fuel. This is a set value signal.

[Problem to be solved by the invention]

In general, in power plants that use a variety of fuels, it is necessary to diversify the master fuel, expand the range of operation of the daisy, and improve the efficiency of the entire system. Master fuel switching is manual.
In addition, the conditions for the main master fuel required a sufficient amount of fuel to correspond to changes in the main steam pressure, and a stable supply of fuel flow rate, pressure, temperature, etc. was required, and advanced experience was required. . Furthermore, when switching the main master fuel, it is necessary to judge the above matters each time, and there is a problem that the fuel that can be used as the master fuel is inevitably limited.

An object of the present invention is to provide a master fuel switching device for a multi-fuel boiler that can solve the above conventional problems.

[Means to solve the problem]

The master fuel switching device for a multi-fuel boiler according to the present invention includes:
In a multi-fuel mailer, means for setting a priority order for each stray fuel that can become a master fuel, means for setting upper and lower limit points that are conditions for fuel switching for each master fuel, and and means for automatically switching to the next master fuel when the fuel reaches the upper limit or lower limit point.

[Effect]

According to the present invention, a certain upper and lower limit point is set for each fuel that can be used as a master fuel, a priority order for becoming a master fuel is set in advance, and when the upper and lower limits are reached, the Next, by switching to the selected master fuel, automatic switching becomes possible in response to diversification of the master fuel, and the range of operation of the boiler using various fuels is expanded.

〔Example〕

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. 1 is the steam pressure signal, which is sent to the set value 2 and the subtractor 3.
Create a control deviation signal using An operation signal corresponding to the control signal is created by a controller (PID system) 4, and this signal and a main steam flow rate signal 5, which is a preceding signal, are added together by an adder 6 to obtain a boiler master signal. The result obtained by subtracting the total fuel flow rate 7 using a subtractor 8 is the fuel demand, and this signal is a set value signal for various fuel operation terminals. In FIG. 1, 9 to J2 are switchers between fuel demand and various fuel set values, 13 to 16 are fuel set values for various fuels,
Reference numerals 17 to 20 indicate various fuel controllers, and 21 to 24 indicate various fuel operation terminals. For the sake of explanation, the fuel at the operating end 21 is assumed to be fuel A, and the fuels at the operating ends 22, 23, and 24 are assumed to be fuel B, C, and D, respectively.

The operation of the above embodiment of the present invention will be explained.

First, determine the priority order when using various fuels as a master fuel. (For example, the order is A fuel → B fuel → C fuel → D fuel). Next, switching conditions for each switch 9 to I2 are determined. For example, the conditions for the master fuel, such as the flow rate, pressure, and temperature of fuel A, are created using the logic shown in FIG.

The switch 9 sends the A fuel flow rate signal to the upper and lower limit monitor 4.
The A fuel pressure signal is sent to the upper/lower limit monitor 47, the A fuel temperature signal is sent to the upper/lower limit monitor 48, and the signals B, C, and D
The fuel master control signals are connected to NOT circuits 44, 45, respectively.
46, the priority number 1 and other conditions are sent, and the switching condition is determined by the palm circuit 42. For example, in FIG. 2, if the flow rate of fuel A, which has the first priority, is out of a certain range, the upper and lower limit monitor 41 outputs a logic signal of O, and the output of the AND circuit 42 becomes 0.

Then, the signal of the switch 9 switches from fuel demand to A fuel demand.

In addition, when the A type fuel is disconnected from the master fuel, the A fuel master control of the 3 type fuel logic similar to that shown in Fig. 2 for the B fuel is excluded, so the AND circuit 42 equivalent of the B type fuel is
Tona fiB type fuel performs pressure control.

For the various fuels C and D below, the master fuel is automatically switched using the same logic as above.

〔Effect of the invention〕

According to the present invention, by automatically switching the master fuel of a multi-fuel boiler, it is possible to diversify fuels and expand the range of operation.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a fuel control circuit in an embodiment of the present invention, Fig. 2 is a diagram showing a low knock that determines the master fuel switching condition in an embodiment of the present invention, and Fig. 3 shows a conventional example. It is a diagram. 9-12...Switcher, 13-16...Fuel setting value,
17-20...Controller.

Claims (1)

[Claims] In a multi-fuel boiler, means for setting priorities for various fuels that can become master fuels, means for setting upper and lower limit points that are conditions for fuel switching for each master fuel, A master fuel switching device for a multi-fuel boiler, comprising means for automatically switching to the next-ranked master fuel when the upper limit or lower limit point is reached.