JP2000256979A - Method for preventing adhering of black liquor lees to black liquor injection nozzle-inserting opening - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove growing black liquor lees and prevent inconvenience of blockage, etc., by blowing pressurized steam having wetness into an opening part of a black liquor-injecting nozzle arranged on furnace wall of a black liquor-recovering boiler. SOLUTION: Pressurized steam having wetness is blown from pressurized steam-jetting nozzles 2a and 2b to peripheral surface in furnace wall of opening of a black liquor-jetting nozzle N arranged on furnace wall of black liquor recovering boiler for burning black liquor in production process of kraft pulp and recovering chemicals used in production of kraft pulp and to the left and right and upper part thereof and the neighborhood of inner face of the furnace to soften and remove the black liquor.

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 burning black liquor generated during kraft pulp production to recover chemicals used in kraft pulp production.
The invention relates to cleaning of an insertion opening of a black liquor injection nozzle opened on a furnace wall of a boiler.

[0002]

2. Description of the Related Art During the production of kraft pulp, black liquor generated in the cooking step is concentrated in order to recover the chemical used for cooking and to use the black liquor as a heat source, and then burnt in a recovery boiler. At that time, if black liquor is in a state of poor combustion in the recovery boiler, the recovery rate of chemicals and heat sources will decrease,
Since many problems such as the occurrence of pollution occur, the black liquor must be uniformly supplied into the recovery boiler to prevent poor combustion. For this reason, black liquor is supplied by spraying the inside of the boiler with an injection nozzle.

[0003] 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 inside of the boiler is at a high temperature, the attached black liquor dries to form black liquor cake, which gradually grows and grows. Eventually, the sediment of the grown black liquor plugs the injection holes of the nozzles and hinders the injection of black liquor. As a result, poor combustion occurs, causing various problems such as a decrease in the recovery rate of chemicals, a reduction in the recovery rate of the heat source, and emission of environmental pollutants together with smoke. As a countermeasure, Tokuhei 3-681
No. 53 has devised a spray device shown in FIG.

[0004]

The spraying device shown in FIG. 1A is characterized in that a pressurized steam having a degree of wetness is sprayed at the tip of a black liquor injection nozzle, that is, in the vicinity of a black liquor injection hole. It is. That is, by spraying pressurized steam having a degree of wetness onto the black liquor cake, the black liquor cake is softened and removed. However, by using the above apparatus, the growth of black liquor cake around the injection hole of the black liquor injection nozzle can be suppressed, but the growth of black liquor cake growing around the opening where the nozzle is inserted cannot be prevented. There is a problem.

[0005] Unless the growth of black liquor cake growing from around the opening into which the nozzle is inserted is prevented, the opening will eventually be closed, which will hinder cleaning around the nozzle orifice and replacement of parts. Moreover, the black liquor cake solidifies firmly, and once fixed,
Even if a hammer is used, it cannot be easily removed. The present invention
This is to solve the above problem.

[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 injection nozzle, and 2a and 2b are pressurized steam injection nozzles. The pressurized steam jet nozzle 2a is installed so as to jet the pressurized steam in the direction of the black liquid jet hole of the black liquid jet nozzle, and the pressurized steam jet nozzle 2b is located above the black liquid jet nozzle, It is installed so as to inject pressurized steam toward the inner peripheral surface of the furnace wall of the black liquor jet nozzle insertion opening H provided on the furnace wall D.

[0007] The steam injected by the present apparatus is pressurized steam having wetness. As the pressurized steam having wetness, for example, pressurized steam obtained by adding water to pressurized steam is used. Can be. Pressurized steam having no wetness is less effective in suppressing the growth of black liquor as compared with pressurized steam having wetness. Therefore, it is desirable to increase the amount of water to be added to the pressurized steam to increase the wettability as much as possible. However, if the amount of water is increased, energy is lost correspondingly.
Injecting the pressurized steam having the wetness more than necessary also results in energy loss, and therefore, it is necessary to minimize the injection amount.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Observation of the growth process of black liquor cake growing around a furnace wall at an opening for inserting a black liquor injection nozzle reveals that inorganic substances and the like in black liquor which cause black liquor cake are removed. The non-combustible material first begins to grow from the inner surface of the furnace near the opening,
Subsequently, it reaches the inner peripheral surface of the furnace wall at the opening indicated by oblique lines in FIG. 2 or FIG. Then, as shown by the diagonal lines in FIG. 3, the growth on the upper part of the opening and the inner peripheral surfaces on the left and right sides is fast, and the growth of the black liquor residue is very small at the lower part of the black liquor jet nozzle.

By injecting pressurized steam into unnecessary parts,
Pressurization that has a degree of wetness mainly toward the inner peripheral surface of the furnace wall excluding the lower part of the black liquor injection nozzle at the opening, because it not only wastes steam but also slightly reduces the energy efficiency of the boiler. It is desirable to inject steam.

As described above, the black liquor begins to grow from the inner surface of the furnace near the opening, and gradually reaches the inner peripheral surface of the furnace wall at the opening. Therefore, it is sufficient to limit the spraying to a portion as close to the inner surface of the furnace as possible, and to suppress the growth of black liquor cake in this portion. Pressurized steam injected toward the space of the opening has almost no effect of suppressing the growth of black liquor cake, and has only an adverse 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 such that 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 adapted to the shape of the black liquor injection nozzle insertion opening,
Install an appropriate number of pressurized steam injection holes in the diagonally outward direction.Especially, the furnace should be installed as far as possible on the left, right, and upper inner peripheral surfaces of the furnace wall opening where black liquor cake grows quickly. The pressurized steam having a high degree of moistness may be injected in a portion close to the inner surface (shaded portion in FIG. 3).

[0012]

By injecting pressurized steam having a degree of wetness into the furnace wall inner peripheral surface of the black liquor injection nozzle insertion opening, the black liquor injection nozzle insertion opening is prevented from being blocked by black liquor cake. it can. The inventions of claims 2 and 3 are inventions in which pressurized steam having wetness is injected particularly concentrated on a portion where black liquor cake grows fast, thereby saving steam required for the injection and reducing energy loss of the boiler. .

[Brief description of the drawings]

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

FIG. 4 is an explanatory view 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

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuhiro Morikawa 505-1 Pulp Town, Asahikawa City, Hokkaido Nippon Paper Industries Co., Ltd. Asahikawa Mill (72) Inventor Hideki Sugimoto 505-1 Pulp Town, Asahikawa City, Hokkaido Nippon Paper Corporation Asahikawa Mill Co., Ltd. F term (reference) 3K061 AA24 AC07 BA03 BA05 QC04 QC22 QC34 QC38 4L055 CC06 FA22

Claims (3)

[Claims] The present invention is characterized in that pressurized steam having a degree of wetness is injected into an inner peripheral surface of a furnace wall of a black liquor injection nozzle insertion opening provided on a furnace wall of a black liquor recovery boiler in a kraft pulp manufacturing plant. To clean the black liquor injection nozzle insertion opening. 2. Pressurized steam having wetness is injected to the left, right and upper portions of the inner wall of the furnace wall at the black liquor injection nozzle insertion opening provided on 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. 3. A pressurized steam having a degree of wetness is injected into an inner peripheral surface of a furnace wall at a black liquor injection nozzle insertion opening and near an inner surface of the furnace. 4. The method for cleaning a black liquor injection nozzle insertion opening according to item 1.