JPS62255821A - Flow rate measuring method for pulverized coal - Google Patents

Abstract

PURPOSE:To accurately measure flow rate of pulverized coal by measuring the conveying air flow rate and concentration of the pulverized coal in the conveying air and calculating the flow rate of the pulverized coal according to those. CONSTITUTION:The coal is fed from a coal feeder 5 into a mill and pulverized. On the other side, the air is fed in the mill 2 by a fan 4 and turned reversely like an arrow in diagram in the mill and flowed to a conveying line 7 accompanied by the pulverized coal and the pulverized coal is fed to a boiler 1. In the above, the air quantity flowing in the mill 2 is measured by a flowmeter 8 and moreover, the concentration of the pulverized coal fed from the line 7 to the boiler 1 is measured by a concentration meter 9, by which the pulverized coal quantity can be measured. Since the air flow rate and the concentration of the pulverized coal are measured and the flow rate of the pulverized coal is calculated according to those by this measuring method, the flow rate of the pulverized coal can be accurately measured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pulverized coal flow measurement method for measuring the pulverized coal flow when supplying pulverized coal to a coal-fired boiler or the like.

[Prior Art] An example of a conventional method of supplying pulverized coal as fuel to a coal-fired boiler will be described with reference to FIG.

In FIG. 6, a is a coal-fired boiler, and b is a ball mill. Coal is supplied into the ball mill b from a coal supply device C, and the coal is pulverized by the rotation of the mill b. On the other hand, air preheated by an air preheater d is blown into the mill b by the air preheater d, and as shown by the dotted arrow in the figure, the air is reversed in the mill b and reaches the boiler a. The air is allowed to flow through mill b, and the air is used to collect 1 liter of pulverized coal in mill b.
I2 and is supplied to boiler a through line f.

In this boiler plant, the amount of air in fan e is controlled depending on the load of the boiler, and the amount of pulverized coal supplied from line f to boiler a is controlled.

[Problem to be Solved by the Invention 1] However, the amount of conveying air and the amount of pulverized coal do not have a fixed proportional relationship, and it is difficult to control the amount of pulverized coal.

Figure 5 shows the amount of pulverized coal supplied and air a relative to the boiler load.
and their ratios are shown.

As can be seen from the graph of FIG. 5, the amount of pulverized coal and the amount of air do not have a fixed proportional relationship, and it is difficult to control the amount of coal fed to the boiler based only on the amount of air.

Especially when starting and stopping the boiler or when the load changes, the amount of air and the amount of pulverized coal do not necessarily have a relationship like the graph in Figure 5, and it is difficult to control the amount of pulverized coal. Become.

Further, if the amount of pulverized coal supplied to the boiler can be measured regardless of the amount of air, there will be no problem, but it is difficult to measure the amount of pulverized coal transported by air.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a method for measuring the flow rate of pulverized coal that can measure the flow rate of pulverized coal when the pulverized coal is transported by air.

[Means and effects for solving the problem 1] In order to achieve the above object, the present invention measures the air flow rate and the concentration of pulverized coal in the air when pulverized coal is supplied to a boiler together with air. The pulverized coal flow rate is determined from the air flow rate and the pulverized coal concentration.The density of the pulverized coal being conveyed is detected using a phototube, etc., and this is used as the concentration, and the concentration is multiplied by the amount of conveyed air. By doing so, the pulverized coal flow rate can be determined.

[Example] An example of the pulverized coal flow rate recording method according to the present invention will be described below with reference to the accompanying drawings.

Figure 1 shows a boiler blunt to which the pulverized coal flow rate measuring method of the present invention is applied.
3 is a horizontal ball mill that crushes coal into pulverized coal; 3 is an air preheater that preheats the air that conveys the pulverized coal; and 4 is a fan.

Coal is supplied into the mill 2 from the coal supply device 5, and
The rotation of the mill 2 causes the balls in the mill 2 to pulverize the powder.

Air is blown from air preheater 3 by fan 4 to 1 line 6
The pulverized coal is supplied into the mill 2 via the pulverized coal, is reversed inside the mill 2 as shown by the arrow, and flows into the conveyance line 7 with the pulverized coal entrained.
Pulverized coal is supplied to boiler 1.

In this boiler blunt, a flow meter 8 for measuring the amount of air flowing into the mill 2 is connected to the blast line 6, and a concentration meter 9 for optically detecting the pulverized coal concentration in the conveying air is installed to the conveying line 7. It will be done.

As shown in FIG. 3, this densitometer 9 consists of transparent detectors 110 and 10 installed opposite each other on a conveyance line 7, with a light source 11 on one side and a light tube 12 on the other. ,
The finger where the light 13 from the light source 11 reaches the phototube 12 is detected as a change in current (or voltage), and this is taken as the pulverized coal concentration.

In the above, the amount of air flowing into the mill 1 by the fan 4 is measured with the flow meter 8, and the concentration of pulverized coal supplied from the conveying line 7 to the boiler 1 is measured with the densitometer 9, so that the amount of pulverized coal can be determined. Can be measured. In other words, as shown in the flow sheet of Fig. 2, the coal concentration is defined as the air ff1 (boiler air) and the detected current (voltage) from the phototube which is the concentration meter, and the amount of air and the coal concentration are multiplied by n. The amount of coal can be determined by

This will be explained using the timing chart shown in FIG.

In Fig. 4, the chart (△) shows the change in air volume, (B
) shows the change in coal concentration, (C) shows the change in phototube current (voltage), and (D) shows no change in coal boat.

When the boiler is stopped, there is no supply of pulverized coal, so the photocell 12
The maximum output is 1, but when the boiler 1 is started, the Noan 4 is driven and air is blown, and the coal and electricity values corresponding to the amount of air are detected. Thereafter, when the load on the boiler increases, the amount of air is increased to increase the amount of coal. When the amount of air is increased, the coal a degree increases, but there is no fixed proportional relationship with the air amount. Therefore, an accurate coal flow rate can be obtained.The present invention is not limited to horizontal ball mills, but can be used for other mills as well.

[Effects of the Invention] As is clear from the above detailed description, the present invention exhibits the following excellent effects.

(1) The flow rate of the conveyed air and the concentration of pulverized coal in the conveyed air are measured, and the flow rate of fine charcoal is determined accordingly, making accurate measurement possible.

(2) Since the flow rate of pulverized coal can be measured accurately, the amount of coal fed can be accurately controlled according to the load, such as when starting a boiler or when floating load changes.

[Brief explanation of drawings]

Figure 1 is a diagram showing a boiler blunt to which the pulverized coal flow meter 11 method of the present invention is applied, Figure 2 is a flow sheet diagram of the present invention, Figure 3 is a detailed diagram of the concentration meter of the present invention, and Figure 4 is FIG. 5 is a timing diagram of the present invention, FIG. 5 is a diagram showing the relationship between air flow and coal supply amount with respect to boiler load, and FIG. 6 is a dimensional diagram of a conventional example. In the figure, 1 is a boiler, 2 is a horizontal ball mill, 4 is a fan,
7 is a conveyance line, 8 is a flow meter, and 9 is a concentration meter. Patent Applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Representative Patent Attorney Nobuo Kinutani Figure 1 7-ta-i9 2...fr Kugetsu U A Te-j Remi) 4--Fan Figure 2 Figure 3 Figure 4 Figure 6

Claims (1)

[Claims] When pulverized coal is supplied to the boiler with air, the air flow rate is measured and the pulverized coal concentration in the air is measured.
A pulverized coal flow rate measuring method characterized by determining the pulverized coal flow rate from the air flow rate and pulverized coal concentration.