JPS631105B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle device for supplying powdered materials to be incinerated, which is suitable for incinerating materials containing low melting point substances in a fluidized bed furnace.

Collected ash (hereinafter abbreviated as EP ash) recently discharged from the exhaust gas of various combustion devices including boilers
The amount of EP ash is enormous, and various methods have been proposed for its disposal.
Incineration is attracting attention because it reduces the volume of ash and makes effective use of its retained heat. Incineration of EP ash is difficult because it contains substances with low melting points such as ammonium sulfate, but incineration using a swirling spouted bed furnace is attracting particular attention because of its good incineration efficiency. Figure 1 shows the method of incinerating powder (hereinafter the term EP ash is used to represent the powdered material to be incinerated containing low melting point substances) in this swirling fluidized bed furnace, and shows the inside of the EP ash transport pipe 10. The pneumatically transported EP ash is ejected into the fluidized bed 5 by a powder supply nozzle (EP ash supply nozzle) 11 inserted through the furnace wall of the swirling spouted bed furnace 1 . This fluidized bed 5 performs a complex flow that combines a swirling flow and a jet flow using the fluidizing air supplied from the perforated plate 2 at the bottom of the bed and the riser pipe 14 in the center, and mixes well with the EP ash. Incinerate. However, in this swirling spouted bed furnace, accidents often occur in which the EP ash supply nozzle becomes clogged, which increases the discharge pressure of the blower that transports the EP ash to the supply nozzle, eventually causing the equipment to shut down. . Here, the inventors conducted the following experiment and confirmed the problem.

First, the swirling spouted bed furnace that will be used has an inner diameter of 600 mm.
The furnace body was equipped with four powder (EP ash) supply nozzles. The temperature inside the swirling spouted bed furnace is
EP ash was supplied at 650°C, and by continuous operation in this state, the degree of blockage of the EP ash supply pipe and changes in the blower discharge pressure were confirmed. Under this condition, one week after starting to supply EP ash into the furnace, the discharge pressure of the blower increased from the initial 2800 mm water column to 3600 mm.
mm water column, the furnace operation was stopped and the blockage of the powder (EP ash) supply nozzle was investigated. As a result, two of the four supply nozzles are blocked, and the temperature at the tip of the supply nozzle at this time is approximately
It turned out that the temperature was 400℃.

The purpose of this invention is to eliminate the above-mentioned drawbacks of the prior art, eliminate blockage of the powder (EP ash) supply nozzle,
An object of the present invention is to provide a nozzle device that enables continuous operation of a powder (EP ash) incinerator such as a swirling spouted bed furnace.

In short, this invention reduces the cross-sectional area of a part of the powder (EP ash) passage in the nozzle to make it a ventilate type, thereby increasing the linear velocity of the powder (EP ash) ejection and reducing the nozzle for low melting point substances generated by temperature rise. This prevents blockage.

This invention will be explained below.

First, the inventors conducted various studies including the experiment described above, and found that the causes of nozzle clogging were the following two points. One is that the high-temperature fluidized medium particles in the fluidized bed are flowing back into the powder (EP ash) supply nozzle due to complicated flow within the bed, and the powder (EP ash) is mixed in the supply nozzle. The temperature of the ash increased as it came into contact with the ash. Another reason is that the temperature of the nozzle wall increases due to heat transfer in the fluidized bed (as is known, heat transfer in the fluidized bed is very good). Due to the above two reasons, ammonium sulfate [(NH ₄ ) ₂ SO ₄ ], which is one of the low-melting substances contained in EP ash, is heated to over 250℃, which is its decomposition temperature, in the supply nozzle, and the following equation It was found that acidic ammonium sulfate (NH ₄ HSO ₄ ) was produced, and as a result, powdered EP ash and fluidized medium adhered to and solidified in the supply nozzle, causing a blockage.

(NH ₄ ) ₂ SO ₄ →NH ₄ HSO ₄ +H ₂ O Based on the above results, FIG. 2 shows a side sectional view of a powder supply nozzle that does not cause blockage. The powder supply nozzle 20 has an end on the powder inflow side connected to the powder transport pipe 10 by a suitable connecting means such as a flange 20a. The powder passage of the powder supply nozzle 20 has a reduced section 21 whose cross-sectional area is gradually reduced from the powder inflow side.
a A minimum area part 21b following this reduced area 21a, and an enlarged part 21c following this minimum area part 21b and gradually opening toward the EP ash spouting end, making the entire area ventilated. .
In the powder passage of this nozzle, the inclination angle α of the reduced portion 21a is 40 degrees or less, preferably 25 degrees or less. This is based on experiments by the inventors and others, and at temperatures above 40 degrees,
This is because if the linear velocity of the minimum area portion 21b decreases due to a decrease in the output of the blower or the like and the fluid medium flows back into the nozzle, there is a risk that the minimum area portion 21b may become clogged. Next, the inclination angle β of the enlarged portion 21c is set to 20 degrees or less, preferably between 10 degrees and 15 degrees. The minimum area portion 21b is these reduced portions 21a.
and is connected to the enlarged portion 21c and arranged approximately at the center of the EP ash supply nozzle 20. In the powder supply nozzle 20 having the above configuration, when supplying powder with air, the fluid linear velocity of the minimum area portion 21b is preferably 100 m/s or more to prevent backflow of the fluid medium.
It is necessary to set the speed to 150m/s or more.
On the contrary, the linear velocity of the fluid at the ejection end of the enlarged portion 21c needs to be in the range of 20 m/s to 60 m/s. This is because if the velocity is less than 20 m/s, the EP ash, which is powder, cannot be ejected sufficiently into the fluidized bed, and conversely, if the velocity is more than 60 m/s, the ejecting velocity of the EP ash is too high, and the EP ash is ejected from the center of the furnace. This is because EP ash may concentrate in some areas or even penetrate the fluidized bed, making it impossible to spread the EP ash evenly. In other words, the area ratio between the minimum area portion 21b and the ejection end of the enlarged portion 21c is:
The linear velocity of the fluid in the minimum area portion 21b is
100 m/s, the linear velocity of the ejection end of the enlarged portion 21c is determined to be between 20 m/s and 60 m/s.

Furthermore, in order to prevent melting and adhesion of EP ash, it is desirable that the temperature of the nozzle is low, and when the nozzle body has a water-cooled structure, the effect of preventing clogging can be further enhanced.

The inventors conducted a performance test of the present invention using the powder supply nozzle configured as described above. The powder supply nozzle used in this test was the reduced part 21a.
A plurality of tubes were used in which the angle of inclination α of is 25 degrees, the linear velocity of the fluid in the minimum area portion 21b is 100 m/s, and the angle of inclination β of the enlarged portion is 14 degrees. When EP ash in the form of powder was supplied to the swirling spouted bed furnace in this state, the discharge pressure of the blower was 3000 mm water column. After one month of continuous operation, the discharge pressure of the blower was 3000 mm of water column, which was completely unchanged from when it started, and when the device was stopped and the powder supply nozzles were inspected, none were clogged, confirming the effectiveness of this invention. did it.

According to the present invention, as is clear from the above test results, the powder supply nozzle is not clogged with low melting point materials over a long period of time and can be operated continuously for a long period of time.

Furthermore, since the discharge pressure of the blower hardly increases, it does not put a burden on the equipment and is economical.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a swirling spouted bed furnace using a conventional powder supply nozzle, and FIG. 2 is a side sectional view of a powder supply nozzle according to the present invention. 20... Powder supply nozzle, 21a... Reduction part, 21
b...Minimum area part, 21c...Enlarged part.

Claims (1)

[Claims] 1 In a nozzle that sprays and supplies EP ash into a fluidized bed using an air flow, the powder passage formed in the nozzle body is made to have an inclination angle of 40 degrees or less from the powder inlet side, so that the cross-sectional area of the passage gradually decreases. It consists of a small section, a minimum area section with the smallest cross-sectional area, and an enlarged section where the inclination angle is 20 degrees or less and the passage cross-sectional area gradually increases toward the powder ejection end, and the cross-sectional area of the minimum area section and the enlarged section are When the linear velocity of the fluid passing through the smallest area part is 100 m/s or more, the linear velocity of the powder jetting end in the enlarged part is from 20 m/s to 60 m/s.
1. A nozzle device for supplying incinerated material to a fluidized bed furnace, characterized in that the nozzle body is formed so as to be in between and has a structure in which the nozzle body is water-cooled.