JP3376943B2 - A method for preventing black liquor cake from sticking to the black liquor jet nozzle insertion opening. - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a black liquor recovery boiler for recovering chemicals used for kraft pulp production by burning black liquor produced during kraft pulp production.
It is an invention relating to cleaning of an insertion opening of a black liquor injection nozzle provided in a furnace wall of a boiler.

[0002]

2. Description of the Related Art Black liquor produced in a cooking process during kraft pulp production is concentrated and then burned in a recovery boiler in order to recover chemicals used for cooking and use the black liquor as a heat source. At that time, if the black liquor is in a state of poor combustion in the recovery boiler, the recovery rate of chemicals and heat sources will decrease and
Since many problems such as pollution will occur, black liquor must be uniformly supplied into the recovery boiler so as to prevent combustion failure. Therefore, the black liquor is supplied by a method of spraying it into the boiler with an injection nozzle.

However, when black liquor is sprayed into the boiler by the injection nozzle, unburned floating black liquor adheres to the tip of the nozzle. Since the temperature inside the boiler is high, the adhered black liquor dries and forms black liquor meal, which gradually grows and grows. Eventually, the grown black liquor lees deposits block the injection holes of the nozzles and hinder the injection of black liquor. As a result, there are many problems such as poor combustion, a low chemical recovery rate, a low heat source recovery rate, and the emission of environmental pollutants along with the flue gas. As a countermeasure, Japanese Patent Publication No. 3-681
No. 53 devised a spray device shown in 2a of FIG.

[0004]

The spray device shown in FIG. 1 at 2a is characterized in that pressurized steam having a degree of wetness is sprayed to the tip of the black liquor injection nozzle, that is, in the vicinity of the black liquor injection hole. Is. That is, the black liquor meal is intended to be softened and removed by blowing pressurized steam having a degree of wetness onto the black liquor meal. However, by using the above device, it is possible to suppress the growth of black liquor meal around the injection holes of the black liquor injection nozzle, but it is not possible to prevent the growth of black liquor meal growing from around the opening into which the nozzle is inserted. There is a problem.

If the growth of the black liquor lees growing around the opening for inserting the nozzle is not prevented, the opening will eventually be closed, and the cleaning around the nozzle injection hole and the replacement of parts will also be hindered. Moreover, the black liquor cake solidifies solidly, and once fixed,
It cannot be removed easily even with a hammer. The present invention is
The above problems are solved.

[0006]

The present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of the present invention. In the figure, N is a black liquor jet nozzle, and 2a and 2b are pressurized vapor jet nozzles. The pressurized steam injection nozzle 2a is installed so as to inject pressurized steam in the direction of the black liquor injection hole of the black liquor injection nozzle, and the pressurized steam injection nozzle 2b is located above the black liquor injection nozzle and is located above the boiler. The black liquor injection nozzle insertion opening H provided in the furnace wall D is installed so as to inject pressurized steam toward the inner peripheral surface of the furnace wall.

The steam injected by this apparatus is a pressurized steam having a wetness. As the pressurized steam having a wetness, for example, a pressurized steam obtained by adding water to the pressurized steam is used. You can Pressurized steam with no wetness is inferior to the pressurized steam with wetness in suppressing the growth of black liquor lees. Therefore, it is desirable to increase the amount of water added to the pressurized steam to increase the wetness as much as possible. However, if the amount of water is increased, the amount of energy will be lost correspondingly.
Further, it is necessary to suppress the injection amount to the minimum necessary amount because the excessive injection of the pressurized steam having the degree of wetness causes energy loss.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION When observing the growth process of black liquor meal that grows around the furnace wall of the opening for inserting the black liquor injection nozzle, it is found The non-combustible material begins to grow from the inner surface of the furnace near the opening,
Then, it reaches the inner peripheral surface of the furnace wall of the opening shown by the diagonal lines in FIG. 2 or FIG. Then, as shown by the hatched lines in FIG. 3, the growth on the upper part of the opening and the left and right inner peripheral surfaces is fast, and only a small amount of black liquor lees is found on the lower part of the black liquor injection nozzle.

By injecting pressurized steam to an unnecessary part,
Not only is it a waste of steam, but it also reduces the energy efficiency of the boiler to a small extent.Therefore, a pressure with a degree of wetness is applied mainly to the inner peripheral surface of the furnace wall excluding the lower part of the black liquor injection nozzle at the opening. It is desirable to inject steam.

Further, as described above, the black liquor lees first start to grow from the inner surface of the furnace near the opening, and gradually reach the inner peripheral surface of the furnace wall of the opening, so that the inner peripheral surface of the opening is Then, the injection should be limited to a portion as close to the inner surface of the furnace as possible to suppress the growth of the black liquor lees in this portion. Pressurized steam injected toward the space of the opening has almost no effect of suppressing the growth of the black liquor lees and has only the opposite effect of losing energy. Therefore, depending on the shape of the opening, as shown in FIG. It is desirable to use an injection nozzle having an injection pattern in which most of the injected pressurized steam is concentrated in the peripheral portion and hardly injected in the central portion.

Alternatively, instead of the nozzle 2b, an inverted U-shaped pipe matching the shape of the black liquor jet nozzle insertion opening is used.
Install an appropriate number of pressurized steam injection holes facing diagonally outward, especially on the inner peripheral surface of the left and right of the opening of the furnace wall where black liquor cake grows fast and the upper part of the furnace as much as possible. It is advisable to inject the pressurized steam having a high degree of wetness, concentrating on the portion close to the inner surface of (1) (hatched portion in FIG. 3).

[0012]

EFFECTS OF THE INVENTION By injecting pressurized steam having a degree of wetness to the inner peripheral surface of the furnace wall of the black liquor injection nozzle insertion opening, the black liquor injection nozzle insertion opening is prevented from being blocked by the black liquor lees. it can. The inventions of claims 2 and 3 are inventions in which pressurized steam having a degree of wetness is particularly concentrated in a portion where the black liquor lees grow fast to reduce the steam required for the injection and reduce the energy loss of the boiler. .

[Brief description of drawings]

FIG. 1 is a sectional view of a black liquor jet nozzle insertion opening.

FIG. 2 is a perspective front view of a black liquor injection nozzle insertion opening.

FIG. 3 is a perspective front view of a black liquor jet nozzle insertion opening.

FIG. 4 is an explanatory diagram of an injection pattern

[Explanation of symbols]

2a Pressurized steam injection nozzle 2b Pressurized steam injection nozzle D furnace wall H opening N black liquor injection nozzle

Front Page Continuation (72) Inventor Hideki Sugimoto 505-1 Pulpcho, Asahikawa City, Hokkaido Inside Asahikawa Mill of Nippon Paper Industries Co., Ltd. (56) Reference JP-A-1-229890 (JP, A) Actual Kaihei 6-30642 ( (58) Fields investigated (Int.Cl. ⁷ , DB name) D21C 11/12 F23J 3/00

Claims (3)

(57) [Claims] 1. A pressurized steam having a degree of wetness is injected onto the inner peripheral surface of the furnace wall of a black liquor injection nozzle insertion opening provided on the furnace wall of a black liquor recovery boiler in a kraft pulp manufacturing plant. Cleaning method for black ink jet nozzle insertion opening. 2. Pressurized steam having a degree of wetness is injected to the left and right and the upper part of the inner peripheral surface of the furnace wall of the black liquor injection nozzle insertion opening provided in the furnace wall of the black liquor recovery boiler in a kraft pulp manufacturing plant. A method for cleaning a black liquor jet nozzle insertion opening, which is characterized in that: 3. A pressurized steam having a degree of wetness is injected to the inner peripheral surface of the furnace wall of the black liquor injection nozzle insertion opening and in the vicinity of the inner surface of the furnace. The method for cleaning the black liquor injection nozzle insertion opening described in.