JPS599281Y2 - Mixed combustion fuel control device - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a mixed combustion fuel control device.

In co-firing combustion equipment using gas fuel and liquid fuel, such as co-firing boilers with mixed gas (off gas) and heavy oil in petrochemical plants, situations may occur where the composition or flow rate of the mixed gas that is the fuel source fluctuates widely. Frequently.

In this case, it is necessary to promptly follow the amount of heavy oil supplied and smoothly control the fuel to ensure stable operation of the boiler.

The present invention has been devised in view of the above-mentioned circumstances, and provides a mixed combustion fuel control device, for example, a fuel control device that can be operated smoothly and stably in a mixed gas-heavy oil mixed combustion boiler.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the co-combustion fuel control system of the present invention.

The computing unit 1 uses the correlation between the amount of gas fuel, for example, the change in composition of the mixed gas fuel and the calorific value, to obtain a gas fuel flow rate value corrected to a specific gas calorific value standard.

The addition calculator 2 adds the gas fuel flow rate based on the specific gas calorific value calculated by the calculator 1, corrected based on the liquid fuel calorific value standard, and the liquid fuel flow rate which is the output of the liquid fuel flow rate measuring device 11. and calculate the total fuel consumption.

On the other hand, a total fuel flow rate controller 3 is provided to control and adjust the total fuel consumption amount, which is the output of the above-mentioned addition calculator 2, to a total fuel flow rate setting value determined according to the load of the boiler.

This output becomes the total fuel flow requirement value. The ratio of the gas fuel amount to the total fuel amount is set by the ratio setter 6, and the total fuel flow rate request value and the multiplier 7 are used as the gas fuel flow rate setting value.

The gas fuel flow rate controller 8 controls and adjusts the gas fuel flow rate to match the gas fuel flow rate set value.

In this way, the gas fuel flow rate value is controlled and adjusted to an arbitrarily set ratio by the ratio setting device 6.

On the other hand, for liquid fuel, an arithmetic unit 4 is provided which compares the gas fuel flow rate setting value and the gas fuel flow rate value from the total fuel flow rate request value, and subtracts the value of the low selector 9, which outputs the smaller one, from the total fuel flow rate request value.

This output becomes the liquid fuel flow rate setting value and is controlled and adjusted by the liquid fuel flow rate controller 5 so as to match the liquid fuel flow rate.

Therefore, according to the above structure, the flow rate of a gas fuel, such as a mixed gas, is converted to a specific gas flow rate based on the calorific value, and the mixed gas flow rate and the heavy oil flow rate, which are similarly converted to the calorific value basis of the liquid fuel, such as heavy oil flow rate, are added. The total fuel flow rate controller 3 adjusts the fuel flow rate to a set value determined by the load of the combustion device, such as a boiler.

The actual mixed gas supply amount is adjusted by the gas flow rate controller 3 to a predetermined ratio setting value of the mixed gas to the total fuel.

The heavy oil flow rate is normally adjusted to the heavy oil flow rate setting value obtained by subtracting the mixed gas setting signal from the total fuel request value, but if the actual mixed gas flow rate value decreases compared to the gas flow rate setting value, the low selector 9 The mixed gas flow rate value is directly output. The heavy oil flow rate setting value is increased by subtracting it from the total fuel requirement value.

In other words, even if the waste flow rate suddenly decreases, the flow rate signal does not go through the total fuel flow rate controller, which causes a time delay, and is first changed to the setting of the liquid fuel flow rate controller 5 via the low selector 9 without being corrected. By changing the value, the liquid fuel flow rate is temporarily increased by the amount that the gas flow rate has decreased.

After a short delay, the control loop via the total fuel flow rate controller comes into play, and at this stage, the original fuel control with correction of calorific value, etc. is performed.

If the gas flow rate suddenly increases, the latter control loop will be effective from the beginning.

In addition, in the boiler according to the present invention, it is important for safety that the reduction in gas flow rate be controlled promptly.

Therefore, even if the mixed gas supply amount and the mixed gas group suddenly change, the heavy oil supply amount smoothly follows and the stable operation of the combustion device can be maintained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a mixed combustion fuel control device according to the present invention. 1... Arithmetic unit, 2... Total fuel consumption adder, 3...
・Total fuel flow rate controller, 4...Total fuel flow rate subtractor, 5.
...Liquid fuel flow rate controller, 6...Gas fuel amount/total fuel amount ratio setting device, 7...Multiplier, 8...Gas fuel flow rate controller, 9...Low selector, 10... - Gas fuel flow rate measuring device, 11...Liquid fuel flow rate measuring device.

Claims (1)

[Scope of utility model registration request] A total fuel flow controller that controls and adjusts the total fuel consumption amount, which is the sum of the gas fuel flow rate and liquid fuel, to a total fuel flow rate set value determined by the load of the co-combustion device and outputs a total fuel flow rate request value, and a total fuel flow rate request value. a ratio setter that sets the gas fuel flow rate to a constant ratio, a gas fuel flow controller that sets the gas fuel flow rate based on the output of the ratio setter and controls and adjusts the gas fuel flow rate, and a gas fuel flow rate and a gas fuel flow rate. A low selector that compares the set values of and selects and outputs the smaller signal, a subtracter that subtracts the output of the low selector from the total fuel flow rate request value and outputs the liquid fuel flow rate request value, and an output of the subtractor. A mixed combustion fuel control device comprising a liquid fuel controller that controls and adjusts a liquid fuel flow rate.