JPH04199B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a combustion apparatus for a rotary kiln. More specifically, the present invention relates to an improvement in a combustion air supply system for a rotary kiln combustion apparatus, particularly in a primary air supply system.

(Prior Art) A combustion air supply device for a conventional combustion device for a rotary kiln has a combustion air supply device for a rotary kiln.
While supplying about 90% of the amount of air required for actual combustion as secondary air with hot air of about 800℃,
The remaining 10% is supplied to the combustion equipment using cold air from the atmosphere as primary air. According to this combustion air supply system, as much as 10% of outside air is used as primary air, which increases the amount of hot air discharged from the clinker box, resulting in poor thermal efficiency.

Therefore, a technology has been proposed to reduce the amount of primary air used by converting the primary air into warm air.
No. 2565). This combustion air supply system
As shown in the figure, a heat exchange tube 103 made of heat-resistant steel is provided in a clinker box 102 downstream of a rotary kiln 101, and outside air or air at about 200° C. is supplied as primary air to a combustion device 104 through the tube 103. This is how it was done.
The primary air is heated by radiation within the clinker box 102 and is supplied after being heated to a temperature of 300 to 500°C. This allows the amount of primary air to be reduced to about 2% of the actual amount of air, but in reality, the fuel is fed into the combustion chamber at an appropriate speed to achieve stable ignition or appropriate atomization and mixing/diffusion of the fuel. Therefore, in practical terms, it has to be kept at about 4 to 5%. However, the hot air inside the clinker box 102 can be used as secondary air by about 5 to 6% more than when the above-mentioned outside air is simply supplied, and the amount of exhaust heat can be reduced.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 59-46414, in order to reduce the amount of outside air used, hot air in the clinker box 202 is extracted, mixed with outside air, and then pressurized by a fan 203 and sent to the combustion device 204. There is also a system shown in Figure 3 that supplies

(Problem to be solved by the invention) However, in the case of the primary air supply system shown in Fig. 2, even if the amount of primary air used is as low as about 4 to 5%, all of it is outside air or about 200℃. Since the air is at a low temperature, the excess air (hot air) inside the clinker box must be discharged, so there is room for improvement in terms of thermal efficiency. In addition, equipment costs are high because a large amount of heat-resistant steel tubes 103 are used for the heat exchanger, and the tubes 103 are subject to wear and scale due to use under hot air and collision with hard clinker particles, resulting in high maintenance costs. There is. Furthermore, clinker box 1
Heat exchange tube 103 piped inside 02
This makes maintenance of the clinker box difficult.

On the other hand, in the case of the primary air supply system shown in Fig. 3, which uses the hot air inside the clinker box as the primary air, even if you try to pressurize the air that has become high temperature by mixing the hot air and outside air with a fan and supply it to the combustion equipment, the air Since the fan cannot be rotated at high speed because it is easily damaged by the clinker particles contained in it, pressure is reduced.
It can only produce 200mmAq to 300mmAq, and requires 25 to 30% of the actual amount of primary air. For this reason, the proportion of the amount of primary air having a relatively low temperature increases, which actually lowers the thermal efficiency.

Therefore, the present invention provides a primary air supply device for a rotary kiln combustion device that can reduce the overall amount of primary air, further reduce the amount of outside air used for the primary air, and increase the amount of hot air used in the clinker box. The purpose is to provide

Structure of the Invention (Means for Solving Problems) In order to achieve the above object, the primary air supply device of the present invention boosts the pressure of outside air and then injects it into the ejector, and utilizes the jetting speed of this outside air. The hot air inside the clinker box is sucked and supplied to the combustion device, and the hot air inside the clinker box is pressurized to a relatively high pressure while remaining relatively high temperature, and can be supplied as primary air, reducing the amount of outside air used in the primary air volume. I try to do that.

(Example) The configuration of the present invention will be described in detail below based on an example shown in the drawings.

In the primary air supply device of the present invention, an ejector 5 is connected to a clinker box 2 installed on the downstream side of the rotary kiln 1 via a dust collector 4, and the ejector 5 is installed on the downstream side of the rotary kiln 1. The blower 6
The outside air is pressurized and injected into the ejector 5, and its ejection speed is used to supply hot air in the clinker box 3 as primary air.

The clinker box 2 is usually placed on the downstream side of the rotary kiln 1 so as to cover the opening of the kiln 1, and is provided so as to introduce outside air from the floor 15 to cool the clinker. Floor part 15
serves as a passage for cooling air and rotary kiln 1
It is a frame with a grate-like structure that is convenient for supporting the clinker falling from the ground and discharging the cooled clinker to the outside.It is generally made of highly heat-resistant metal such as cast iron, which is the same as the grate. It is formed in the structure of

The dust collector 4 includes gravity dust collection, inertial dust collection, centrifugal dust collection, wet cleaning dust collection, filtration dust collection, electrostatic dust collection,
Sonic dust collectors and the like can be used, but dry dust collectors such as centrifugal dust collectors and electric dust collectors are preferred, and cyclones are generally used. This cyclone 4
The outlet of the clinker box 2 is connected downstream of the outlet of the clinker box 2, and is provided to smoothly return the collected clinker particles into the clinker box 2 without scattering them again. Of course, the clinker particles may not be returned to the clinker box 2 in some cases. On the other hand, the exhaust port of the cyclone 4 is connected to an ejector 5, and is piped in such a manner that it is sucked by outside air injected into the ejector 5. The blower 6 that blows outside air into the ejector 5 is usually 3000 to 6000 mm.
AQ's Roots blower is used. Further, a valve 9 is provided in the flow path 14 between the ejector 5 and the cyclone 4 to open the flow path 14 to the atmosphere as necessary to allow outside air to be introduced. This valve 9 usually employs a solenoid valve that is easy to control, and is connected to the primary air supply channel 11 in order to keep the temperature of the primary air constant regardless of fluctuations in the temperature of the hot air extracted from the clinker box 2. It opens and closes to introduce the necessary amount of outside air under the control of a temperature indicator control (TIC) 8 that outputs a control electric signal based on the measured value of a thermocouple 7 installed. Thereby, even if the temperature of the extracted hot air fluctuates significantly due to an increase or decrease in the amount of clinker falling from the rotary kiln 1, the temperature of the primary air can be controlled within a suitable range, for example, 400 to 500°C.

According to the primary air supply device of the present invention configured as described above, primary air is supplied as follows. In addition, this primary air supply device is designed so that the temperature of the air that has exchanged heat with the clinker in clinker box 2 is
In the case of 600 to 1000 degrees Celsius, the case where hot air of 400 to 500 degrees Celsius is supplied as primary air is given as an example.

First, the roots blower 6 is operated to inject outside air (about 20℃) in an amount equivalent to about 2 to 2.5% of the actual air amount into the ejector 5 at a relatively high pressure of 3000 to 6000 mmAq, and the injection speed is utilized. A portion of the hot air (600 to 1000°C) inside clinker box 2 is extracted. The hot air drawn out from the clinker box 2 drops clinker particles in the cyclone 4 in an amount of about 2 to 3% of the actual air volume, and is sucked into the ejector 5. The outside air ejected from the ejector 5 and the hot air from the clinker box 2 at a temperature of 600 to 1000°C drawn into this jet are mixed to become hot air at a temperature of 400 to 500°C and supplied to the combustion device 3 as primary air.
The primary air amount at this time is 4 to 5% of the actual air amount. In addition, since the fire will not be stable if the temperature fluctuates greatly, it is constantly measured with a thermocouple 7, and is kept constant by controlling the opening of the valve with the TIC 8 and making the amount of outside air introduced in front of the ejector 5 variable. controlled within range. In addition, the wind pressure of primary air is about 1000 mmAq.

Effects of the Invention As is clear from the above description, the primary air supply device of the present invention uses an ejector that blows out outside air at a relatively high pressure to suck air after heat exchange in the clinker box and supply it as primary air to the combustion device. Since the primary air is supplied at high pressure and temperature, the amount of primary air used can be reduced to 4 to 5% of the actual amount of air. Moreover, 2 to 3 of the primary air amount
% is the relatively high temperature air inside the clinker box, and since about 97% to 98% of the actual air amount is used as combustion air, including the amount used as secondary air in the kiln burner, the system The amount of hot air discharged to the outside is reduced, improving thermal efficiency.

Although the primary air supply system of the present invention requires an ejector and a cyclone, it is less expensive than the conventional primary air supply system that requires a large number of relatively expensive and heat-resistant heat exchange tubes installed in a complicated manner inside the clinker box. This reduces equipment costs, and since the equipment is located outside the clinker box, maintenance is easy and the equipment has a long lifespan.

[Brief explanation of drawings]

FIG. 1 is a principle diagram showing an example of a primary air supply device for a combustion apparatus for a rotary kiln according to the present invention.
FIG. 2 is a principle diagram showing an example of a conventional primary air supply device. FIG. 3 is a principle diagram showing an example of another conventional primary air supply device. 1...Rotary kiln, 2...Clinker box, 3...Combustion device, 4...Cyclone, 5...
Ejector, 6... Roots blower, 10, 11, 1
2, 13, 14...Piping.

Claims (1)

[Claims] 1. An ejector that injects outside air at relatively high pressure using an attached blower is connected to a clinker box installed downstream of the rotary kiln, and the ejector is connected to a combustion device installed downstream of the rotary kiln. , a combustion apparatus for a rotary kiln, characterized in that air after heat exchange in the clinker box is sucked by outside air injected into the ejector, and is supplied to the combustion apparatus as primary air at a relatively high temperature and high pressure. Primary air supply device.