JP2007277448A - Treatment process of tar sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process of treating tar sludge that can stably operate a coke oven, retain strength of coke, and can prevent environmental deterioration caused by benzene volatilization. <P>SOLUTION: The process comprises the steps of condensing tar sludge a1 separated from coal tar generated in the coke oven to have a solid concentration of ≥90% and discharging the tar sludge thus obtained on a coal feed conveyor 2 so that the tar sludge "a" can be coated with coal "c" being carried on the coal feed conveyor. Also, the condensed tar sludge having a solid concentration of ≥80% may be discharged to be sandwiched by the coal "c" and returned coal "c1". <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for treating tar meal.

The coke oven gas generated in the coke production process is cooled, and the agglomerated tar content is introduced into the tar cadenta together with the cooling water and the pulverized coal and pulverized coke accompanying the coke oven gas. Separated.
Further, the separated tar is separated into tar and tar residue by a centrifuge. This tar cake is composed of sludge content of 40-50% and 50-60% tar content consisting of coal fine powder, fine coke and semi-coke coke powder, etc. It has unique properties.

  For this reason, tar tar is difficult to handle, and in most cases it is disposed of, but tar tar itself emits a foul odor, which can be a source of pollution regardless of whether it is landfilled or incinerated. Therefore, tar waste disposal is extremely difficult. In view of this, several techniques have been proposed for recycling tar bags in an easy-to-handle form without disposing them.

  For example, Patent Document 1 discloses a process A in which tar soot separated from tar generated from a coke oven is diluted to a solid content of 60% or less, and a tar having a solid content of 90% or more by sedimentation or centrifugation of the diluted tar and tar soot. Disclosed is a method for treating tar soot comprising Step B for separating the soot and recovered tar and Step C for purifying the obtained recovered tar by centrifugation. The refined recovered tar is mixed with tar soot and used as a raw material for step A or step B. Further, the tar meal (solid content of 90% or more) produced in the processes B and C is charged into a coke oven through a coal blending tank. Centrifugation in step C is preferably performed at 2000 G or more, and the recovered tar ash (ASH) is preferably 0.2% or less.

Patent Document 2 discloses a method for treating tar cake that is introduced into a coke oven after kneading an oil adsorbent into the tar cake and pelletizing it. The pelletized tar is added to the raw coal and introduced into the coke oven. The oil adsorbent is preferably pulverized coal, coke powder, or dust collection dust around the coke oven.
Further, Patent Document 3 discloses that the tar cake is subdivided by discharging and dropping the tar cake from the perforated plate onto the coal being conveyed by a coal conveyor belt conveyor (hereinafter also referred to as a coal feeding conveyor) to the coke oven. Disclosed is a method for treating tar soot, which is added to coal and subjected to carbonization in a coke oven. The preferred minimum pore diameter of the perforated plate is 30 mm or less.

Further, in Patent Document 4, the tar meal separated from coal tar generated from the coke oven is concentrated so that the solid content concentration is 80% or more, and the obtained tar meal is crushed or pulverized. A method for adding tar soot to a coke oven charging coal that is discharged onto a coal feeding conveyor (preferably on the coal being delivered by the coal feeding conveyor) is disclosed. The preferred maximum particle size of the tar cake after pulverization or pulverization is 50 mm or less. It is recommended that tar mill after pulverization or pulverization be discharged directly without using a conveying device. For this purpose, the pulverizer or pulverizer is a vertical type, and the tar pallet discharge port is arranged directly above the coal feeding conveyor. It is good to do.
Japanese Unexamined Patent Publication No. 7-188671 JP-A-9-40968 JP-A-9-158181 Japanese Patent Laid-Open No. 10-60451

  As in Patent Document 1, in a method in which tar soot concentrated by a centrifugal separator or the like (solid content of 90% or more) is charged into a coal blending tank and mixed with coal and returned to a coke oven, tar contained in tar soot Due to the influence of moisture, the mixing of coal and tar cake becomes non-uniform, and there is a problem that leads to insufficient strength of coke produced in a coke oven (see Patent Document 4). On the other hand, as in Patent Documents 2 to 4, in the method of adding tar soot onto coal being delivered by a coal conveyor, coal and tar soot are uniformly mixed, and the above-mentioned problem of insufficient coke strength arises. Absent.

  However, it has been found that there is the following problem in the method of adding tar soot on coal being delivered by a coal conveyor. That is, if the coal charged in the coke oven contains a lot of moisture, the operation of the coke oven becomes unstable, so that the coal has a moisture content of 5 by a CMC (coal humidity control device) before being discharged to the coal feeding conveyor. The humidity is adjusted to ˜6%, so the temperature of the coal on the CMC exit side is about 90-100 ° C. On the other hand, tar + moisture contained in tar meal contains aromatic compounds such as benzene to some extent, and especially benzene has a boiling point of 80 ° C, which is lower than the temperature of coal on the CMC exit side. When tar soot is added onto coal being delivered by a conveyor, there is a problem that benzene contained in the tar soot volatilizes and the environment deteriorates.

  An object of the present invention is to solve the above-mentioned problems, and to provide a method for treating tar soot capable of maintaining the operation of a coke oven stably, ensuring the strength of coke, and preventing environmental deterioration due to benzene volatilization. And

The present invention concentrates tar soot separated from coal tar generated from a coke oven so that the solid content concentration is 90% or more, and the obtained tar soot is placed on the coal feeding conveyor. The tar soot treatment method is characterized in that it is discharged so as to be covered with coal being delivered. Here, the coal feeding conveyor refers to a belt conveyor for delivering coal to a coke oven.
Further, the present invention concentrates the tar soot separated from coal tar generated from the coke oven so that the solid content concentration is 80% or more, and pre-lays the obtained tar soot on a coal feeding conveyor. A method for treating tar soot, characterized in that the coal is discharged so as to be covered with coal being delivered by the coal conveyor. The “pre-coaled coal” described above may be normal coal or return coal. Here, the return coal refers to coal that has been spilled and recovered from the coal feeding conveyor, or coal that has been recovered when leveling during coal charging into the coke oven.

  Moreover, in this invention, it is preferable to manage the temperature of the coal which coat | covers the said tar soot to less than 90 degreeC. More preferably, it is less than 80 ° C.

  According to the present invention, coal and tar cake are uniformly mixed without fouling the belt of the coal conveyor, coke strength can be secured, operation of the coke oven is kept stable, and benzene volatilized from the tar cake is It is shielded by coal to prevent its release into the atmosphere and prevent environmental degradation.

  In the present invention, the tar meal dispensed onto the coal feeding conveyor must have a solid content concentration of 90% or more. When the solid content concentration is less than 90%, the belt adheres to the belt of the coal feeding conveyor when it is dispensed onto the coal feeding conveyor, and the belt becomes dirty, resulting in increased costs and operational troubles. However, when paying off tar coal on coal laid in advance on a coal feeding conveyor, the tar rice cake has only to pass through the layer of coal laid in advance and adhere to the coal feeding conveyor. The concentration may be 80% or more.

  As a method for concentrating tar soot to a solid content concentration of 80% or more or 90% or more, the method described in Patent Document 1 can be preferably used. Further, tar soot concentrated to a solid content concentration of 80% or more or 90% or more may be dispensed as it is, or it is dispensed after kneading the oil adsorbent by the method described in Patent Document 2 and pelletizing it. Alternatively, it may be discharged and dropped from the perforated plate by the method described in Patent Document 3, or may be discharged after being crushed or ground by the method described in Patent Document 4.

  FIG. 1 shows a specific example of a method for discharging concentrated tar soot onto a coal feeding conveyor and paying off so that the coal being delivered is covered with the coal feeding conveyor. As shown in the figure, in a so-called junction portion configured to drop the coal c onto the lower coal transport conveyor 2 from the upper coal transport conveyor 1, in the coal feed path of the lower coal transport conveyor 2, What is necessary is just to make it discharge | pay tar tar a to the position of the B point upstream from the position of the A point from which the coal c falls, for example via the tar dredging pipe 3. Tar 滓 a discharged to the position of point B is conveyed by the coal feeding conveyor 2, and when it reaches the position of point A, it is covered with falling coal c. Reference numeral 5 denotes a coal scattering prevention cover for preventing the falling coal from scattering.

  Further, FIG. 2 shows a specific example of a method of discharging the concentrated tar cake on the coal previously laid on the coal feeding conveyor, and dispensing the tar cake with the coal being delivered by the coal feeding conveyor. . In this example, return coal was used as “pre-coaled coal”. As shown in the figure, in the junction part similar to FIG. 1, in the coal feeding path of the lower coal feeding conveyor 2, at the point B point upstream from the point A point where the coal c falls, For example, tar 滓 a may be discharged through the tar culvert piping 3, and return charcoal c1 may be discharged to the position of point C upstream from the position of point B, for example, via the return charcoal hopper 4. . Tar 滓 a discharged to the position of point B is discharged to the position of the upstream point C and falls on the return coal c1 laid on the coal feeding conveyor 2, When it reaches the point A, it is covered by the falling coal c. That is, the tar cocoon a is delivered to the coke oven while being sandwiched between the lower return coal c1 and the upper coal c.

  Furthermore, if the temperature of the coal in the coated tar soot is controlled below 90 ° C. (more preferably below 80 ° C.), the volatilization amount of benzene is greatly reduced. One embodiment of this management is a method of operating the CMC under proper humidity control conditions in which the coal temperature on the CMC outlet side is less than 90 ° C. within a range where the moisture content of the coal does not exceed the allowable upper limit. It is done. One is a method in which tar soot is discharged downstream from an appropriate cooling point where the temperature of coal during coal feeding cools to 90 ° C in the coal feeding path of the coal feeding conveyor.

3 is used to separate the tar tar a1 separated from the coal tar generated from the coke oven into a recovered tar d and a concentrated tar tar a by a super decanter (centrifugal separator) 6. From the tar hopper a stored in the tar hopper 7, the tar hopper a was extruded into an iodine shape by an extruder 8.
(Comparative example)
In Comparative Example 1, the solid content of the concentrated tar soot a is 90%. The tar tar a thus extruded was discharged onto the coal (temperature of about 95 ° C.) being delivered by the coal feeding conveyor via the tar fire pipe 3 (not shown). At this time, a benzene concentration of 2 to 4 mg / Nm ³ was detected in the vicinity of the dispensed point. In addition, the tar cake a did not adhere to the coal feeding conveyor, the stability of the coke oven operation was not impaired, and the coke strength was at a sufficient level.

(Invention Example 1)
In Invention Example 1, the concentration of the solid content of the concentrated tar soot is 90%. As shown in FIG. 1, the extruded tar soot a is discharged onto the coal feeding conveyor 2 at the point B and coated with coal c (temperature of about 95 ° C.) as shown in FIG. Delivered to. At this time, the benzene concentration detected in the vicinity of the payout point was 0.5 to 0.7 mg / Nm ³ . In addition, the tar cake a did not adhere to the coal feeding conveyor 2, the stability of the coke oven operation was not impaired, and the coke strength was at a sufficient level.

(Invention Example 2)
In Invention Example 2, the concentration of the solid content of the tar tar a is 80%. As shown in FIG. 2, the extruded tar 滓 a is discharged onto the coal feeding conveyor 2 at the point B, as shown in FIG. 2, and the upper coal c (temperature is about 95 ° C.) and the lower return coal. Delivered to the coke oven in a sandwich with c1. At this time, the benzene concentration detected in the vicinity of the payout point was 0.5 to 0.7 mg / Nm ³ . In addition, the tar cake a did not adhere to the coal feeding conveyor 2, the stability of the coke oven operation was not impaired, and the coke strength was at a sufficient level.

(Invention Example 3)
In invention example 3, in the invention example 2, the position in the coal passage of point A, point B and point C is changed to a downstream position where the temperature of coal c at point A is about 85 ° C., otherwise Was the same as the invention example. At this time, the concentration of benzene detected in the vicinity of the dispensed point was less than 0.1 mg / Nm ³ . In addition, the tar cake a did not adhere to the coal feeding conveyor 2, the stability of the coke oven operation was not impaired, and the coke strength was at a sufficient level.

It is a schematic diagram which shows one example of embodiment of this invention. It is a schematic diagram which shows another example different from the previous appearance of embodiment of this invention. It is a schematic diagram which shows one example of a tar flaw processing apparatus.

Explanation of symbols

1, 2 Coal feeding conveyor 3 Tar tarp piping 4 Return coal hopper 5 Coal scattering prevention cover 6 Super decanter (centrifugal separator)
7 Tar hopper 8 Extruder
a Tar rice cake (concentrated tar rice cake)
a1 Tar dredging (tar tar separated from coal tar generated from coke oven)
c Coal
c1 Return charcoal
d Recovery tar

Claims (3)

  The tar cake separated from the coal tar generated from the coke oven is concentrated so that the solid content concentration is 90% or more, and the obtained tar cake is being delivered on the coal feeding conveyor by the coal feeding conveyor. A method for treating tar soot that is discharged so as to be covered with coal.   The tar soot separated from the coal tar generated from the coke oven is concentrated so that the solid concentration is 80% or more, and the obtained tar soot is put on the coal previously laid on the coal feeding conveyor. A method for treating tar cake, wherein the tar is disposed so as to be covered with coal being delivered by a charcoal conveyor.   The method for treating tar fouling according to claim 1 or 2, wherein the temperature of coal covering the tar fouling is controlled to be less than 90 ° C.

Images