JPS61250557A - Method for evaluating coal combustion characteristics - Google Patents

Abstract

PURPOSE:To evaluate the combustion characteristics of coal by using a small amount of a coal sample, by supplying fine powdery coal to a preheated combustion furnace along with air in a specific ratio and stopping preheating after the start of combustion to perform the analysis of exhaust gas and the measurement of the unburnt coal component of the dust in the exhaust gas. CONSTITUTION:Fine powdery coal is supplied to the hopper 5 of a coal supply part 1 and supplied to a preheated combustion furnace in an introducing amount of 100-300g/h along with primary air 6 and secondary air 7. Because the introduced fine powdery coal is immediately burnt, a preheating heat source is cut off and, on and after, the combustion of fine powdery coal is succeeded without heating from the outside. Further, tertiary air 8 is supplied to a combustion part 2. The total amount of primary, secondary and tertiary airs 6, 7, 8 is adjusted to 1.1-1.3 times the amount perfectly burning the fine powdery coal. The exhaust gas generated by combustion is guided to an analyser 4 through a filter to analyze the composition thereof and a part thereof is sent to a cyclone 11 while cooled by a cooling part 10 and the unburnt component in collected dust is burnt in an electric furnace to perform quantitative analysis. By this method, combustion characteristics can be sufficiently evacuated by using about 1kg of a sample.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for evaluating coal combustion characteristics, and more particularly to a method for evaluating combustion characteristics using a relatively small amount of coal.

[Prior art]

In recent years, the use of coal as an energy source to replace oil has once again been attracting attention.

By the way, in order to evaluate the combustion characteristics of coal, normally the coal is crushed into pulverized coal, and the pulverized coal is fed into a combustion test device in an amount of 50 kg/h to 2 t/h to evaluate the combustion characteristics. Ta.

However, when receiving inquiries from overseas, the amount of coal samples that can be obtained is limited to 1 to 2 kg, making it impossible to conduct combustion tests using large amounts of coal as in the past. It was desired to establish a method for evaluating combustion characteristics using

[Purpose of the invention]

The present invention was made in view of the above-mentioned current situation, and an object of the present invention is to establish a method for evaluating combustion characteristics using a relatively small amount of coal.

[Structure of the invention]

To achieve the above object, the present invention supplies pulverized coal together with air at a rate of 100 to 300 g/h to a preheated combustion furnace, and after the start of combustion of the pulverized coal, preheating is stopped and the pulverized coal is combusted. The present invention is characterized by continuing the combustion, analyzing the exhaust gas generated by the combustion, and collecting dust in the exhaust gas to measure the unburned coal content in the dust.

The type of coal used in the present invention may have any degree of carbonization as long as it is normally used for combustion, including bituminous coal and sub-bituminous coal.

Lignite 1 petroleum pitch, petroleum coke, etc. can be used. These coals are pulverized and carbonized into powder prior to evaluation of combustion characteristics.

The degree of pulverization is usually such that the amount passing through a 200 mesh sieve is 70% to 90%. If the particle size of the pulverized coal is less than 70% passing through a 200 mesh sieve, there will be a large amount of unburned coal, and if the amount passing through a 200 mesh sieve exceeds 90%, the pulverized coal supply amount will become unstable, which is not preferable.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 shows an example of a combustion test device used in the present invention, and this device includes a coal supply section 1. Combustion part 2
．． Ash sump 3. and an analyzer 4.

First, the pulverized coal is supplied to the hopper 5 of the coal supply section 1, and -
Pulverized coal is quantitatively introduced into the combustion section 2 together with large air 6 and secondary air 7.

The amount of pulverized coal introduced here is usually 100 to 300 g/
h, preferably 150 to 200 g/h; if the amount of pulverized coal introduced is less than 100 g/h, the temperature inside the furnace will tend to become low, and if it exceeds 300 g/h, the combustion time will be shortened, resulting in unburned coal. There is a tendency for the amount to increase.

Note that the amount of pulverized coal introduced is quantified using, for example, a screw feeder.

Also, - the total amount of large air 6, secondary air 7, and tertiary air 8 to be described later is adjusted to be 1.1 to 1.3 times the amount to completely burn the carbon content of the pulverized coal introduced. be done.

On the other hand, the combustion section 2 is preheated by heating, for example, with an electric furnace 12, and is maintained at a temperature at which the introduced pulverized coal is immediately combusted.

The preheating temperature varies depending on the type of pulverized coal and the amount introduced, but
Usually it is 1200-1250°C. Since the pulverized coal introduced into the preheated combustion section 2 is immediately combusted, the heat source for preheating is turned off and the combustion of the pulverized coal is continued without external heating.

Note that tertiary air 8 is further supplied to the combustion section 2. Usually, the combustion section 2 is cylindrical, and has a diameter of 80 mm and a length of 1.000 am, for example.

An ash sump 3 is provided at the bottom of the combustion section 2, and collects relatively large particles that can be separated by gravity from the exhaust gas generated by combustion.

On the other hand, the exhaust gas is led to the analyzer 4 via the filter 9 and its composition is analyzed.
021NO2 etc. are measured.

In addition, as an analysis needle, for example, zirconia 202,
Non-dispersive infrared CO2, CO, SO2 meter, chemical type N
An Ox meter or the like is used.

A part of the exhaust gas is cooled in the cooling unit 10, for example, water-cooled, and then sent to the cyclone 11, where dust in the exhaust gas is collected. The unburned content in the dust is quantified by burning it in an electric furnace.

In Figure 1, P is a pressure needle and F is a flow meter.

T indicates a thermometer, respectively.

〔Effect of the invention〕

As described above, according to the present invention, pulverized coal is supplied together with air at a rate of 100 to 300 g/h to a preheated combustion furnace, and after the start of combustion of the pulverized coal, preheating is stopped and the pulverized coal is In addition to continuing the combustion of coal and analyzing the exhaust gas generated by this combustion, the dust in the exhaust gas is collected and the unburned coal content in the dust is measured, so a coal sample of about 1 kg is enough to evaluate the combustion characteristics. be able to. 50kg/
A result is obtained that has a correlation with the result of the conventional evaluation method which required an amount of h~2 t/h.

Next, the following example shows that the method of the present invention described above is useful as a method for evaluating combustion characteristics.
− will be clarified in comparison with the results of the evaluation method using unitary coal samples.

〔Example〕

Using the same coal, a comparative combustion test was conducted between the method of the present invention and a conventional test furnace with a coal feed rate of 100 kg/h and 2 t/h. Figure 2 shows the combustion efficiency and NOx characteristics when the air ratio is changed.

Furthermore, the relationship between the furnace volume load, combustion efficiency, and NOx characteristics is shown in FIG.

As is clear from these Figures 2 and 3, the method of the present invention (〇-〇) and the 100 kg/h method (△-△
) and the 2 t/h method (x-x), a good correlation is seen both quantitatively and in terms of trends.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the combustion test device used in the present invention, Fig. 2 is a diagram showing the relationship between changes in air ratio, combustion efficiency, and NOx characteristics, and Fig. 3 is a diagram showing the relationship between furnace volume load and combustion efficiency. FIG. 1... Supply section, 2... Combustion section, 4... Analyzer, 1
1...Cyclone.

Claims (1)

[Claims] Pulverized coal and air are placed in a preheated combustion furnace at 100 to 30
After the combustion of the pulverized coal starts, preheating is stopped and the combustion of the pulverized coal is continued, and the exhaust gas generated by the combustion is analyzed and the dust in the exhaust gas is collected. A method for evaluating coal combustion characteristics, comprising measuring the unburned coal content in the dust.