JP2009168336A - Combustion control method and device for liquid fuel combustion apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential pressure control method and device for spray vapor pressure and oil pressure supplied to a fuel oil burner, producing no soot and moreover making no noise in a furnace such as a boiler. <P>SOLUTION: Differential pressure between vapor pressure and oil pressure (=spray steam pressure-oil pressure) in the fuel oil burner to the change of load (the amount of fuel oil used) of the furnace such as the boiler is controlled to about 0.035-0.06 MPa until the load of the furnace becomes about 25% of the total output from the starting of the furnace, and then control is performed to gradually raise the differential pressure until the boiler load is about 50% of the total output so that the differential pressure reaches a predetermined value when the boiler load is 50% and maintains the predetermined value until the boiler load becomes 100%. Thus, burner combustion control eliminating the generation of soot and noise can be performed by controlling vapor pressure according to a load factor from the starting of the fuel oil burner up to 100%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to combustion control of a liquid fuel combustion apparatus such as heavy oil.

  Conventionally, in a combustion apparatus such as a boiler using liquid fuel such as heavy oil as fuel, vapor is supplied to the liquid fuel burner together with the liquid fuel as a spray medium of the liquid fuel, and fine droplets of the liquid fuel are supplied from the liquid fuel burner into the combustion apparatus. Sprayed and burned.

In a conventional liquid fuel burner such as heavy oil, as shown in FIG. 5 (a), the spray vapor pressure is not limited regardless of the amount of liquid fuel supplied (= burner load), that is, even if the amount of liquid fuel supplied increases. As shown in FIG. 5B, the vapor pressure is constant and the fuel supply pressure is increased as the liquid fuel supply amount (= burner load) increases. A method of performing differential pressure constant control for controlling the amount of spray vapor so that the differential pressure (spray vapor pressure-fuel supply pressure) is constant has been implemented.
JP 2007-101073 A

  Regardless of the control method of the constant vapor pressure and the constant differential pressure control method, if the amount of spray vapor is too large compared to liquid fuel in the burner low load range, the excessively supplied steam compared to liquid fuel As a result, the combustion becomes unstable, and there is a potential to generate slight combustion vibration, which causes noise. Further, when the amount of vapor is too small in the high burner region as compared with the liquid fuel, there is a problem that the droplet diameter of the fuel becomes coarse and soot is generated.

  FIG. 1 is a curve showing the relationship between the amount of vapor and the average particle size of droplets (droplets of a mixed fluid of liquid fuel and water), but when the amount of vapor is small, the average particle size of the droplets is large As the amount of vapor increases, the average particle size of the droplets decreases. When the average particle size of the droplets is large, the amount of vapor is small, so that the combustibility of the liquid fuel is deteriorated and soot is easily generated. On the other hand, if the average particle size of the droplets becomes smaller, the flammability of the liquid fuel will be improved, so that it will be difficult for soot to occur. Since the fuel becomes diluted and the combustion becomes unstable, minor combustion vibrations are likely to occur, and if combustion vibrations occur, noise will be caused.

  Accordingly, an object of the present invention is to provide a method and an apparatus for controlling the differential pressure between the spray vapor pressure supplied to the liquid fuel burner and the liquid fuel pressure, in which no soot is generated and no noise is generated in a furnace such as a boiler. It is.

The problems of the present invention are solved by the following means.
According to a first aspect of the present invention, there is provided a liquid fuel burner combustion control method for supplying liquid fuel and steam for spraying liquid fuel to a liquid fuel burner of a boiler. The differential pressure between the spray vapor pressure in the burner and the supply pressure of liquid fuel (= spray vapor pressure-liquid fuel pressure) is measured between the start-up of the boiler and the load until the boiler load reaches a predetermined full output value. It is a combustion control method of a liquid fuel burner that performs control so as to prevent generation.

  According to a second aspect of the present invention, there is provided a combustion control method for a liquid fuel burner in which liquid fuel and steam for spraying liquid fuel are supplied to the liquid fuel burner of the boiler. The differential pressure between the vapor pressure and the liquid fuel pressure in the burner (= spray vapor pressure-liquid fuel pressure) is 0.035 to 35% until the boiler load reaches about 25% of the total output from the start-up of the boiler. The pressure is controlled to about 0.06 MPa, and then the differential pressure is gradually increased until the boiler load reaches about 50% of the total output, and when the boiler load reaches 50%, the differential pressure is controlled to a predetermined value. This is a combustion control method for a liquid fuel burner that performs control to keep the differential pressure constant until the boiler load reaches 100%.

The invention described in claim 3 is supplied from a steam pipe provided with a differential pressure control valve for adjusting a supply amount of steam for spraying liquid fuel, a liquid fuel pipe for supplying liquid fuel of a predetermined pressure, a steam pipe, and a liquid fuel pipe. A liquid fuel burner that burns steam and liquid fuel, and a combustion control device for the liquid fuel burner that adjusts the amount of steam and liquid fuel supplied to the liquid fuel burner, and detects the flow rate of liquid fuel supplied to the liquid fuel burner A liquid fuel flow detector, a vapor pressure detector for detecting the spray vapor pressure of the vapor supplied to the liquid fuel burner inlet, a liquid fuel pressure detector for detecting the supply pressure of the liquid fuel supplied to the liquid fuel burner, A differential pressure calculator for calculating a differential pressure (c) which is a difference between a detected pressure value (a) detected by the vapor pressure detector and a detected pressure value (b) detected by the liquid fuel pressure detector, and a flow rate of liquid fuel supplied to the burner ( A function generator for setting the differential pressure (c ₀₎ of the proper vapor pressure corresponding to the liquid fuel pressure and liquid fuel pressure to the liquid fuel flow rate (x) based on), the calculated difference by the differential pressure calculator The pressure (c) is input as a measured value, and the differential pressure controller that inputs the differential pressure setting value (c ₀ ) installed by the function generator, and the differential pressure measured value obtained by the differential pressure controller An opening controller for the differential pressure control valve that controls the amount of spray vapor supplied to the burner of the liquid fuel by determining the opening of the differential pressure control valve based on the deviation between (c) and the differential pressure set value (c ₀ ). It is a combustion control apparatus of the liquid fuel burner provided.

  According to the present invention, the vapor pressure is adjusted so that the vapor pressure supplied to the liquid fuel burner becomes a predetermined differential pressure with respect to the liquid fuel pressure with respect to the liquid fuel pressure required to supply the predetermined amount of liquid fuel. It is possible to control the amount of vapor (vapor pressure) according to the amount of liquid fuel, and it is possible to adjust the vapor pressure so that the differential pressure enters the shaded portion shown in FIG. 4 according to the boiler load.

  In this way, according to the present invention, burner combustion control can be performed by eliminating the generation of noise and noise by controlling the vapor pressure in accordance with the load factor from the start of the liquid fuel burner to the boiler load of 100%.

Embodiments of the present invention will be described with reference to the drawings. The case where heavy oil is used as the liquid fuel will be described below.
In this embodiment, a case where heavy oil is used as the liquid fuel will be described. FIG. 2 shows the configuration of a combustion control device for a heavy oil fired boiler, and FIG. 3 is a graph showing the relationship between burner load (heavy oil supply amount), heavy oil supply pressure (hydraulic pressure), and steam pressure of the heavy oil fired boiler. 4 is a graph illustrating the concept of differential pressure control between the spray vapor pressure and heavy oil pressure supplied to the liquid fuel burner of the heavy oil fired boiler.

  The differential pressure control of the conventional heavy oil burner, as shown by the dotted line vapor pressure and solid line oil pressure in Fig. 3, is the boiler (burner) load (fuel supply) from the boiler startup to the boiler rated full power operation. Vapor pressure (dotted line) and hydraulic pressure (solid line) so that the differential pressure (= spray vapor pressure-hydraulic pressure) between the spray vapor pressure in the steam pipe and the oil pressure in the heavy oil pipe that is supplied to the heavy oil burner in response to changes ) Are set so as to be arranged in parallel at equal intervals. In this embodiment, the curve is shown by a thick alternate long and short dash line between the curves indicating the change in vapor pressure (dotted line) and hydraulic pressure (solid line) in FIG. Control is performed to increase the steam pressure sequentially from the boiler startup along the curve.

  That is, the boiler load is controlled so that the differential pressure is about 0.035 to 0.06 MPa until the boiler load reaches about 25% of the rated full power operation, and then the boiler (burner) ) The differential pressure is gradually increased until the load reaches about 50% of the total output, and when the boiler (burner) load reaches 50%, the differential pressure is any one of 0.05 to 0.15 MPa which is a predetermined value. Then, control is performed so that the differential pressure is set to any one of 0.05 to 0.15 MPa until the boiler load reaches 100%.

  When the graph of FIG. 3 is rewritten, the graph shown in FIG. 4 is obtained. From the time when the boiler is started up until the boiler (burner) load reaches about 25% of the total output, noise is generated if the differential pressure is within the range of 0.035 to 0.06 MPa indicated by the hatched portion in FIG. No soot is generated. Further, until the boiler (burner) load is about 25% to 50% of the total output, the differential pressure indicated by the hatched portion in FIG. 4 is in the range of 0.035 to 0.06 MPa to 0.05 to 0.15 MPa. Control is performed so as to approach the range, and thereafter, control is performed such that the differential pressure becomes a predetermined value within a range of 0.05 to 0.15 MPa until the boiler (burner) load reaches 100%.

  In this way, the steam pressure and hydraulic pressure in the heavy oil burner are adjusted by adjusting the steam pressure so that the differential pressure enters the shaded portion shown in FIG. 4 according to the boiler (burner) load (the differential pressure setting value is indicated by a black square). When the differential pressure is controlled, no noise is generated and soot is not generated. When the differential pressure reaches the upper side of the hatched portion shown in FIG. 4, noise is generated, and soot is generated if the differential pressure is present on the lower side of the hatched portion. The horizontal axis in FIG. 4 shows the amount of steam generated per hour (ton / hour) when using a boiler with an output of 10 tons / hour and the amount used per hour when A heavy oil is used as heavy oil. (L / hr) and the amount of spray vapor per hour (kg / hr) sprayed from the heavy oil burner are shown simultaneously.

FIG. 2 shows a control mechanism diagram of the differential pressure regulating valve for controlling the amount of spray vapor supplied to the heavy oil burner to which the fixed amount of heavy oil of the present embodiment shown above is supplied.
The differential pressure calculator 3 determines the steam pressure hydraulic pressure from the steam spray steam pressure signal (a) of the steam spray steam pressure detector 1 supplied to the burner inlet and the pressure signal (b) of the heavy oil pressure detector 2 supplied to the burner. The differential pressure (c) is calculated. The differential pressure (c = a−b) calculated by the differential pressure calculator 3 is input to the differential pressure controller 4 as a measured value.

On the other hand, the heavy oil flow rate (x) supplied to the heavy oil burner is detected by the heavy oil flow rate detector 5, and the difference between the vapor pressure and the hydraulic pressure with respect to the heavy oil flow rate (x) is detected by the function generator 6 based on the heavy oil flow rate (x). The pressure (c ₀ ) is set, and this differential pressure set value (c ₀ ) (value indicated by the black square in FIG. 4) is input to the differential pressure controller 4 as a set value. A deviation signal between the measured value (c = a−b) and the set value (c ₀ ) obtained by the differential pressure controller 4 is input to the PI controller 7 to perform PI calculation, and from the result, the differential pressure control valve 10 is opened. The amount of spray vapor supplied to the burner inlet is adjusted by determining the degree by the operating means 8.

  In this way, the steam pressure so that the steam pressure supplied to the heavy oil burner becomes a predetermined differential pressure with respect to the heavy oil pressure with respect to the heavy oil pressure necessary for supplying the predetermined amount of heavy oil by the differential pressure adjusting valve 10. The amount of steam (steam pressure) corresponding to the amount of heavy oil (heavy oil pressure) can be controlled, and the steam pressure can be adjusted so that the differential pressure enters the shaded portion shown in FIG. 4 according to the boiler load. .

  Thus, according to the present embodiment, burner combustion control can be performed by eliminating the generation of noise and noise by controlling the steam pressure in accordance with the load factor from the start of the heavy oil burner to the boiler load of 100%.

  According to the present invention, combustion control of environmentally friendly liquid fuel such as heavy oil can be performed, and thus industrial applicability is high. Moreover, since the above-mentioned useless consumption in the burner low load region is suppressed, there is an energy saving effect.

The relationship figure of the amount of spray vapor | steam and the average particle diameter of a droplet (oil droplet) is shown with a liquid fuel burner. The block diagram of the combustion control apparatus of the heavy oil fired boiler of the Example of this invention is shown. The relationship figure of the burner load (liquid fuel supply amount) and the liquid fuel supply pressure (hydraulic pressure) of the combustion control apparatus of the heavy oil fired boiler of the Example of this invention is shown. The figure explaining the concept of the differential pressure control of the combustion control apparatus of the heavy oil fired boiler of the Example of this invention is shown. Relationship diagram (FIG. 5 (a)) and differential pressure (spray vapor pressure) of boiler load, vapor pressure, and fuel pressure when performing constant vapor pressure control with constant vapor vapor pressure in a liquid fuel burner with respect to a conventional boiler load FIG. 5B is a relationship diagram (FIG. 5B) of the boiler load, the steam pressure, and the fuel pressure in the case of performing the differential pressure constant control in which the fuel supply pressure is constant.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spray vapor pressure detector 2 Heavy oil pressure detector 3 Differential pressure calculator 4 Differential pressure controller 5 Heavy oil flow rate detector 6 Function generator 7 PI controller 8 Operating means 10 Differential pressure control valve

Claims (3)

In a combustion control method of a liquid fuel burner for supplying liquid fuel and steam for spraying liquid fuel to a liquid fuel burner of a boiler,
The difference between the spray vapor pressure in the liquid fuel burner and the supply pressure of the liquid fuel (= spray vapor pressure-liquid fuel pressure) in response to changes in the boiler load (liquid fuel supply amount). A combustion control method for a liquid fuel burner, characterized in that control is performed so as to prevent noise and soot from occurring until all output values are reached. In a combustion control method of a liquid fuel burner for supplying liquid fuel and steam for spraying liquid fuel to a liquid fuel burner of a boiler,
The difference between the vapor pressure and the liquid fuel pressure in the liquid fuel burner (= spray vapor pressure-liquid fuel pressure) in response to changes in the boiler load (liquid fuel supply amount) Until the pressure reaches 25%, the differential pressure is controlled to about 0.035 to 0.06 MPa, and then the differential pressure is gradually increased until the boiler load reaches about 50% of the total output. A combustion control method for a liquid fuel burner, characterized in that a control is performed so that the differential pressure becomes a predetermined value when it becomes%, and thereafter, the differential pressure is kept constant until the boiler load becomes 100%. Steam piping provided with a differential pressure control valve for adjusting the amount of steam supplied for liquid fuel spraying, liquid fuel piping for supplying liquid fuel of a predetermined pressure, steam supplied from the liquid piping and liquid fuel piping, and liquid fuel are combusted A liquid fuel burner and a combustion control device for a liquid fuel burner for adjusting a supply amount of steam and liquid fuel to the liquid fuel burner,
A liquid fuel flow detector for detecting a flow rate of liquid fuel supplied to the liquid fuel burner;
A vapor pressure detector for detecting the spray vapor pressure of the vapor supplied to the liquid fuel burner inlet;
A liquid fuel pressure detector for detecting the supply pressure of the liquid fuel supplied to the liquid fuel burner;
A differential pressure calculator that calculates a differential pressure (c) that is a difference between a detected pressure value (a) by the vapor pressure detector and a detected pressure value (b) by the liquid fuel pressure detector;
A function generator for setting a differential pressure (c ₀ ) between the liquid fuel pressure with respect to the liquid fuel flow rate (x) and an appropriate vapor pressure corresponding to the liquid fuel pressure based on the liquid fuel flow rate (x) supplied to the burner;
A differential pressure controller for inputting the differential pressure (c) calculated by the differential pressure calculator as a measured value and for inputting a differential pressure set value (c ₀ ) installed by the function generator;
The amount of spray vapor supplied to the burner of liquid fuel by determining the opening of the differential pressure control valve based on the difference between the measured differential pressure value (c) and the differential pressure setting value (c ₀ ) obtained by the differential pressure controller. Combustion control device for a liquid fuel burner provided with an opening controller of a differential pressure control valve for controlling the pressure.

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