JP6503925B2 - Method of manufacturing cement clinker - Google Patents

Description

  The present invention relates to a method for producing a cement clinker which prevents thermal damage to firebricks from a fire zone exit to a cooling zone from a firing zone outlet in a rotary kiln concurrently with firing of a cement raw material.

FIG. 3 shows a conventional cement production facility. In the figure, reference numeral 1 denotes a rotary kiln for firing a cement material.
The rotary kiln 1 has the upstream and downstream ends of a cylindrical kiln body 1a rotatably supported via support rollers (not shown) in the rear end housing 2 and the front housing 3, respectively.

  Here, as shown in FIG. 4, the kiln main body 1a is one in which the refractory bricks 1c are laid along the inner surface of the steel cylindrical shell 1b, and the inner diameter d is 3 to 7 m and the total length is 60 to 120 m. It was formed in Then, the kiln main body 1a is inclined downward at a gradient of about 3/100 from the upstream side to the downstream side, and is rotated at a speed of about 1 to 3 times per minute.

  Further, as shown in FIG. 3, the buttocks housing 2 is disposed continuously to the lowermost stage of the preheater 5 for preheating the cement raw material, and the weir front housing 3 is mounted on the end wall 3a of the kiln main body 1a. A main burner 6 is provided which jets fuel toward the interior to heat the interior, and a clinker cooler 4 is provided below the end wall 3a.

  The main burner 6 is disposed at a position substantially coaxial with the rotation center C of the kiln body 1a in the end wall 3a, and the pulverized coal and petroleum coke powder, which are the main fuel, together with primary air is approximately the rotation center of the kiln body 1a. By blowing upstream toward the part C, the main flame F1 is spouted along the substantially rotation center C.

  In order to produce the cement clinker in the cement production facility having the above-described configuration, the cement raw material preheated in the preheater 5 is introduced into the kiln main body 1 a through the buttocks housing 2. Then, the cement raw material is burned at a high temperature to become a cement clinker in the process of being sent downstream as indicated by arrow Y in the figure as the kiln body 1a rotates, and is sent to the clinker cooler 4.

  Then, in the clinker cooler 4, it is sent to the downstream side while being rapidly cooled by the cooling air A. On the other hand, the air A heated by cooling the cement clinker is supplied to the front housing 3 and used as a secondary air for combustion of the main burner 6 and becomes a high temperature flue gas from the kiln main body 1a. It is supplied to the preheater 5 as a heat source for preheating of the cement material through the butt housing 2.

  At this time, the inside of the above-mentioned kiln main body 1a can be divided into a calcining zone, a transition zone, a calcining zone, and a cooling zone from the upstream side according to the situation where the cement raw material is heated. The raw material becomes a high temperature of about 1450 ° C. and is fired to cement clinker under the atmosphere.

  By the way, in the above-mentioned conventional method for producing cement clinker, in the firing zone in the kiln body 1a, a clinker coating layer made of a melt of cement clinker is thickly formed on the surface of the refractory brick under high temperature atmosphere. In addition to the low temperature in the cooling zone, the clinker coating layer becomes thin due to the influence of the secondary air flow. As a result, there is a problem that the amount of wear and tear of the firebrick 1c in the cooling zone is larger than the amount of wear and tear on the firebrick 1c in the firing zone.

  For this reason, the main fire pot F1 of the main burner 6 has been shortened, and by raising the temperature in the range from the firing zone outlet to the cooling coal, a measure has been taken to increase the adhesion amount of clinker coating. The problem is that the thermal NOx of the

  Therefore, the inventors of the present invention have previously provided a sub-burner separately from the main burner for heating the inside of the rotary kiln in Patent Document 1 below, and the sub-burner causes the downstream end of the rotary kiln to go upstream from the downstream end. We propose a method for forming a clinker coating layer in the rotary kiln cooling zone characterized by forming a clinker coating layer in the above range by heating only the range of 0 to 1.0 times or 0 to 5 m of the inner diameter of the rotary kiln. did.

  According to the above method, the temperature of the cooling zone downstream of the baking zone can be increased, and as a result, the melt of cement clinker in the cooling zone is increased to adhere to or permeate the refractory bricks on the inner surface of the cooling zone, Since the clinker coating layer can be formed thick, the effect of being able to reduce the amount of wear and tear of refractory bricks and the like can be obtained.

  However, in the above method, there is also a disadvantage that the energy consumption unit increases, and the improvement thereof is desired.

Japanese Patent Application Publication No. 2003-238219

  The present invention has been made in view of the above circumstances, and effectively protects refractory bricks in the range from the firing zone outlet to the cooling zone without increasing NOx in the exhaust gas or increasing the energy consumption rate. It is an object of the present invention to provide a method of producing a cement clinker capable of producing a coating which can be used to prevent thermal damage to refractory bricks.

In order to solve the above-mentioned subject, the invention according to claim 1 introduces a cement material from the above-mentioned heel end into a rotary kiln in which a cylindrical kiln main body is rotatably provided between a heel front housing and a heel end housing. The fuel is spouted from the main burner provided on the end wall of the front housing to the center of the cross section of the kiln body while being transferred to the front side of the front housing to heat the inside and fire the cement raw material. In the method of producing a cement clinker according to the present invention, the cement clinker is sent to the clinker cooler from the clinker outlet of the rotary kiln to cool the cement clinker, and at least coal ash is contained from the feed pipe provided on the end wall and SiO ₂ 50 to 65% by weight, 17 to 30% by weight of Al ₂ O _{3, 4} to 17% by weight of Fe ₂ O ₃ , N The above clinker is a powder wherein a is in the range of 0.5 to 2.0% by weight in terms of Na ₂ O, and Al ₂ O ₃ / Fe ₂ O ₃ is prepared in the range of 1.2 to 3.2. It is characterized in that it jets toward the inner wall of 0 to 5 m from the mouth toward the inner side of the inner wall of the kiln main body.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the powder is sprayed from the feeding pipe at a speed of 20 to 30 m / s.

  The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the powder is mixed with one or more of copper slag, waste gypsum board and construction sludge in addition to the coal ash. It is a feature.

  The invention according to claim 4 is characterized in that, in the invention according to any one of claims 1 to 3, 5 to 20% by weight of copper slag is mixed with the coal ash.

In the invention described in claim 1, comprising at least coal ash, and the SiO ₂ 50-65 wt%, the _Al 2 _{O 3} 17 to 30 wt%, 4 to 17 weight _Fe 2 _{O 3} % And Na in the range of 0.5 to 2.0% by weight in terms of Na ₂ O, and Al ₂ O ₃ / Fe ₂ O ₃ (weight ratio) was blended in the range of 1.2 to 3.2 The powder is similar in composition to the cement clinker, and can form a liquid phase at a lower temperature than the cement clinker to produce a good quality coating.

  Therefore, the low melting point powder prepared in this manner is placed in the range of 0 to 5 m from the clinker outlet toward the buttocks side from the feeding pipe provided adjacent to the main burner on the end wall of the front housing. By spraying toward the inner wall of the kiln body, the amount of coating on the surface of the refractory brick in the range from the above-mentioned firing zone outlet to the cooling zone can be increased more than before, and as a result, the thermal damage of the refractory brick in the relevant range You can prevent.

Here, in the above powder, it is important to adjust Al ₂ O ₃ / Fe ₂ O ₃ (hereinafter, also abbreviated as IM) to a range of 1.2 to 3.2, and the upper limit value in particular is 3. It is more preferably 0 or less, and most preferably 2.0 or less.

  Moreover, it is preferable that the injection speed from the injection pipe of the said powder is a speed | rate of the range of 20-30 m / s like invention of Claim 2. By the way, it is preferable that the coating formed on the surface of the refractory brick by the above-mentioned spray of powder is continuously sprayed to maintain the effect in order to periodically separate from the surface.

  Also, the above powder can be prepared with coal ash alone, but as long as it has the above component composition, for example, as in the invention according to claim 3, in addition to the above coal ash, copper slag, waste gypsum One or more of the board and construction sludge may be mixed and adjusted.

  Furthermore, in the invention according to claim 4, by mixing 5 to 20% by weight of copper slag with the above-mentioned coal ash, it becomes possible to adjust the melting point and to increase the adhesion amount of the coating. At this time, if the above-mentioned copper slag to be mixed is adjusted to a particle size which satisfies the particle size distribution of the fine aggregate, it is possible to easily carry out the introduction from the introduction pipe, which is preferable.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows the cement manufacturing equipment used for one Embodiment of this invention. It is a figure which shows the injection | throwing-in position of the powder in the said embodiment, (a) is a II-II line view of FIG. 1, (b) is a side view of (a). It is a schematic block diagram which shows the cement manufacturing equipment used for the manufacturing method of the conventional cement clinker. FIG. 4 is a cross-sectional view of the kiln body of FIG. 3;

  Hereinafter, based on FIG. 1 and FIG. 2, one Embodiment of the manufacturing method of the cement clinker which concerns on this invention is described. In addition, about the part which is the same as what was shown in FIG. 3 and FIG. 4 about the structure which concerns on a cement manufacturing installation, the description is simplified using the same code | symbol hereafter.

In this manufacturing method, as shown in FIG. 1, an input pipe 10 is provided on the end wall 3a of the front housing 3 provided with the main burner 6, and this is carried out simultaneously with the firing of the cement material in the rotary kiln 1. From the feeding pipe 10, containing at least coal ash, 50 to 65% by weight of SiO ₂ , 17 to 30% by weight of Al ₂ O _{3, 4} to 17% by weight of Fe ₂ O ₃ , Na in terms of Na ₂ O The rotary kiln 1 to the clinker cooler 4 are powders in the range of 0.5 to 2.0% by weight and prepared by blending Al ₂ O ₃ / Fe ₂ O ₃ (weight ratio) in the range of 1.2 to 3.2. To the inner wall of the kiln main body 1a in the range of 0 to 5 m from the clinker outlet to the buttocks side.

  The above powder is prepared by mixing coal ash with one or more of copper slag, waste gypsum board and construction sludge, etc. When adding copper slag to coal ash, 5 to 20 with respect to coal ash It is mixed in the range of weight%. Moreover, injection of the said powder from the injection tube 10 is performed at the speed | rate of 20-30 m / s. At this time, it is preferable to adjust the said copper slag mixed to the particle size which satisfies the particle size distribution of a fine aggregate.

  According to the method of manufacturing cement clinker having the above configuration, the above-mentioned powder sprayed from the feeding pipe 10 toward the inner wall of the kiln 1a has a component composition similar to that of the cement clinker and is liquid at a lower temperature than the cement clinker. In order to be able to form a phase to produce a high quality coating, by spraying from the clinker outlet toward the above buttocks side toward the inner wall of the kiln body 1a in the range of 0 to 5 m, The amount of coating on the surface of the refractory bricks in the range from the firing zone outlet to the cooling zone can be increased as compared with the prior art, so that the thermal damage of the ranged refractory bricks can be prevented.

  In order to verify the effects of the present invention, clinker coolers of the clinker at the charging positions (inner wall of the kiln body 1a), blowing amount and charging speed shown in Table 2 for each of the charges 1 to 3 of chemical composition shown in Table 1 The adhesion of the coating was confirmed by injecting from 0 to 5 m toward 0 to 5 m from the back to 4 side. FIG. 3 shows the particle size distribution of the mixed copper slag.

  Here, FIGS. 2 (a) and 2 (b) show the above-mentioned input positions A to D and the input range. That is, the vertical line L1 from the rotation center C, and the range in which 45 degrees are sequentially formed in the rotation direction of the kiln body 1a from the top of the kiln body 1a to the rotation direction C with respect to the vertical line L1 The inner walls of the kiln body 1a) are A to D, and are inserted into the range of 5 m or less toward the buttocks side from the falling edge of the clinker.

  From the results shown in Table 2, it was found that the coating adhesion is good when sprayed toward the inner wall of the kiln body 1a at position B or position C. This is because, when charged from position A, many fall down before they sufficiently adhere to the surface of the refractory brick 1c, and when charged into position D, the rotation of the kiln body 1a tends to rise, and so on It is estimated that it is difficult to secure enough time for

1 Rotary Kiln 1a Kiln Body 2 Ax Butt Housing 3 Ax Front Housing 3a End Wall 6 Main Burner 10 Insertion Tube

Claims (4)

The end of the front housing is introduced into the rotary kiln in which the cylindrical kiln body is rotatably provided between the front housing and the rear end housing, and the cement material is introduced from the rear end of the housing and transferred to the front side. Fuel is injected from the main burner provided on the wall toward the center of the cross section of the kiln body, and the interior is heated to fire the cement raw material, thereby forming a cement clinker, the cement clinker being the clinker outlet of the rotary kiln. In the manufacturing method of the cement clinker which sends to a clinker cooler and is cooled,
The above-mentioned end wall contains at least coal ash from the feeding pipe, and 50 to 65% by weight of SiO ₂ , 17 to 30% by weight of Al ₂ O _{3, 4} to 17% by weight of Fe ₂ O ₃ , Na _The above clinker is a powder having a range of 0.5 to 2.0% by weight in terms of ₂ O and prepared by blending Al ₂ O ₃ / Fe ₂ O ₃ (weight ratio) in a range of 1.2 to 3.2. A method of manufacturing a cement clinker, comprising: spraying from the falling port toward the buttocks end toward the inner wall of the kiln body in the range of 0 to 5 m.   The method for producing cement clinker according to claim 1, wherein the powder is sprayed from the feeding pipe at a speed of 20 to 30 m / s.   The method for producing cement clinker according to claim 1 or 2, wherein the powder is prepared by mixing one or more of copper slag, waste gypsum board and construction sludge in addition to the coal ash.   The method for producing cement clinker according to any one of claims 1 to 3, wherein 5 to 20 wt% of copper slag is mixed with the coal ash.

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