JP2010042971A - Method for controlling operation of cement manufacturing apparatus and cement manufacturing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling the operation of cement manufacturing apparatus and a cement manufacturing apparatus capable of enhancing the removal efficiency for chlorine by a simple method. <P>SOLUTION: The method for controlling the operation of cement manufacturing apparatus comprising a chlorine by-path system 13 for removing chlorine by extracting a part of the waste gas from the end 3a of a kiln 3, comprises measuring the molar ratio of K<SB>2</SB>O in the alkali of a cement clinker, and adjusting the potassium content in the cement raw material by changing the mixture ratio of a clay containing large amount of potassium or the like based on the measuring result. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an operation control method for a cement manufacturing apparatus including a chlorine bypass system for extracting a chlorine content by extracting a part of exhaust gas from a kiln bottom of a kiln and a cement manufacturing apparatus capable of performing the operation control.

Chlorine bypass system prevents cyclone clogging and coating troubles in the preheater and kiln as the chlorine component contained in the cement raw material and kiln fuel circulates and concentrates in the closed system of the kiln and preheater. In order to prevent this, it is a system in which a part of exhaust gas is extracted from the kiln bottom of the kiln to remove chlorine from the system.
In this chlorine bypass system, in order to increase the removal efficiency of chlorine, Patent Document 1 proposes a method of reducing the rotational speed of the kiln, and Patent Document 2 proposes a method of adjusting the temperature of the raw material in the kiln. Patent Document 3 describes a method in which potassium is added to a raw material and the purity of potassium chloride recovered by a chlorine bypass system is increased.
JP 2006-16216 A JP 2007-176716 A Japanese Patent No. 3933509

However, the method for reducing the rotational speed of the kiln and the method for adjusting the temperature in the kiln are not practical because they require a significant change in operating conditions. Moreover, the method for increasing the purity of potassium chloride is not expected to promote the effect of the chlorine bypass system.
This invention is made | formed in view of such a situation, and it aims at providing the operation control method and cement manufacturing apparatus of a cement manufacturing apparatus which can raise the removal efficiency of chlorine with a simple method.

An operation control method for a cement manufacturing apparatus according to the present invention is an operation control method for a cement manufacturing apparatus including a chlorine bypass system for extracting a chlorine content by extracting a part of exhaust gas from a kiln bottom of a kiln. It is characterized by measuring the molar ratio of K ₂ O therein and adjusting the amount of potassium in the cement raw material based on the measurement result.

In order to promote the concentration of chlorine, the method of increasing the amount of alkali in the raw material is effective, but if the amount of alkali in the cement is high, an alkali-aggregate reaction occurs and concrete deteriorates. The alkali content R ₂ O (= Na ₂ O + 0.658 K ₂ O) is defined by JIS as 0.75% or less. For this reason, the alkali content cannot be increased more than necessary, but the present applicant can increase the molar ratio of K ₂ O in the alkali even when the alkali content is 0.75% or less. It has been found that chlorine concentration can be promoted. In the present invention, by measuring the molar ratio of K ₂ O and adjusting the amount of potassium in the cement raw material according to the molar ratio, the chlorine concentration is promoted and the chlorine removal efficiency is increased. It is a thing.

In the operation control method of the cement production apparatus of the present invention, it is preferable to adjust the amount of potassium so that the molar ratio of K ₂ O in the alkali is 0.6 or more and 0.8 or less.
In a cement clinker in a normal cement factory, the molar ratio of K ₂ O to alkali is about 0.5, and by making this 0.6 or more, the raw material containing the kiln (the raw material immediately before being put into the kiln) The chlorine concentration can be increased by 20% or more, and in the chlorine bypass system, a large amount of chlorine can be removed even with a small amount of bypass, and the chlorine removal effect can be improved. On the other hand, the reason why the molar ratio of K ₂ O is set to 0.8 or less is that it is impossible to remove sodium unless it exceeds 0.8. It is.

Further, in the operation control method of the cement manufacturing apparatus of the present invention, the molar ratio of SO _{3 to} alkali in the cement clinker is further measured, and the amount of sulfur in the kiln fuel is adjusted based on the measurement result. May be.
The chlorine concentration of the kiln-containing raw material increases as the molar ratio of SO _{3 to} alkali decreases. Therefore, the amount of sulfur in the fuel is adjusted by measuring the SO ₃ molar ratio in the cement clinker and using a low-sulfur kiln fuel.

In the operation control method of the cement manufacturing apparatus of the present invention, when measuring the molar ratio of SO _{3 to} alkali in the cement clinker, the molar ratio of SO _{3 to} alkali is 0.4 or more and 0.85 or less. The amount of sulfur should be adjusted.
Even if low sulfur kiln fuel is used, it is difficult to reduce SO _{3 in} cement clinker to 0.4% or less. Therefore, the molar ratio is set to 0.4 or more, and fuel such as low sulfur coal is used. It is particularly effective when the SO ₃ in the clinker is reduced to 0.60% or less and the molar ratio of SO ₃ is set to 0.85 or less.

The operation control method for a cement manufacturing apparatus according to the present invention is an operation control method for a cement manufacturing apparatus including a chlorine bypass system for extracting a chlorine component by extracting a part of exhaust gas from a kiln bottom of a kiln. It is characterized in that the molar ratio of SO _{3 to} the alkali in it is measured and the amount of sulfur in the kiln fuel is adjusted based on the measurement result.

In relation to the SO ₃ concentration and the chlorine concentration of the kiln filled in the raw material, under the knowledge that since the chlorine concentration increases the SO ₃ concentration is reduced, it is effective to increase the chlorine concentration if suppress the SO ₃ circulates The SO ₃ molar ratio with respect to the alkali was measured, and the sulfur content in the kiln fuel was adjusted based on the measurement result.
In the operation control method of the cement manufacturing apparatus of the present invention, as described above, the amount of sulfur may be adjusted so that the molar ratio of SO _{3 to} alkali is 0.4 or more and 0.85 or less.

The cement production apparatus of the present invention is a material supply capable of supplying a cement raw material containing potassium in a cement production apparatus having a chlorine bypass system for extracting a part of exhaust gas from a kiln bottom of a kiln to remove chlorine. And a K ₂ O molar ratio measuring means for measuring the molar ratio of K ₂ O in the alkali in the cement clinker, and is measured between these raw material supply means and the K ₂ O molar ratio measuring means. Further, a potassium content adjusting means for adjusting the amount of potassium content in the cement raw material according to the molar ratio of K ₂ O is provided.
Adjustment of the amount of potassium in the cement raw material may be performed by changing the mixing ratio of clay containing a large amount of potassium.

The cement manufacturing apparatus further includes fuel supply means capable of supplying a fuel containing sulfur, and SO ₃ molar ratio measuring means for measuring the molar ratio of SO _{3 to} alkali in the cement clinker. between the supply means and the SO ₃ molar ratio measuring means, sulfur adjusting means may be configured to provided to adjust the amount of sulfur in the kiln fuel in accordance with the molar ratio of the measured SO _3.
Adjustment of the amount of sulfur in the kiln fuel can be achieved by using coal, which is a low sulfur fuel, instead of coke, or changing the mixing ratio of these.

Further, the cement manufacturing apparatus of the present invention is a fuel supply means capable of supplying a fuel containing sulfur in a cement manufacturing apparatus including a chlorine bypass system for extracting a chlorine content by extracting a part of exhaust gas from a kiln bottom of a kiln. When, along with and the SO ₃ molar ratio measuring means for measuring the molar ratio of SO ₃ in the alkali in the cement clinker is provided, between these fuel supply means and the SO ₃ molar ratio measuring means, the measured of SO ₃ Sulfur content adjusting means for adjusting the amount of sulfur content in the kiln fuel according to the molar ratio is provided.

According to the present invention, the control of adjusting the potassium content in the cement raw material from the molar ratio of K ₂ O in the alkali in the cement clinker, or adjusting the sulfur content in the kiln fuel from the molar ratio of SO _{3 to} the alkali, respectively. By carrying out alone or in combination, the concentration of chlorine in the kiln-containing raw material can be promoted without increasing the alkali content to a value higher than the JIS specified value, thereby improving the efficiency of chlorine bypass. Therefore, in the chlorine bypass system, a sufficient amount of chlorine can be removed with a small amount of gas extraction, or a large amount of chlorine can be removed with the same extraction amount.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cement manufacturing apparatus according to this embodiment. The cement manufacturing apparatus includes a cement raw material supply means 1, a preheater 2, a cement kiln 3, a clinker cooler 4, and the like.
The cement raw material supply means 1 supplies powder raw material obtained by pulverizing and mixing cement raw material to the preheater 2, and as the raw material for cement, limestone, silica, clay, iron oxide raw material, etc. are mixed at an appropriate ratio. And industrial waste is mixed as part of the raw material.

  The preheater 2 has a plurality of cyclones 5a to 5d connected to each other in the vertical direction, and the gas discharged from the cement kiln 3 in the process of dropping the powder raw material supplied to the uppermost cyclone 5a. Is used to preheat powder raw materials. The lowermost cyclone 5 d is connected to the cement kiln 3, and is configured such that the powder raw material preheated to a predetermined temperature by the preheater 2 is continuously fed into the cement kiln 3. Further, between the lowermost cyclone 5d and the upper cyclone 5c, combustion exhaust gas is introduced from the kiln bottom 3a of the cement kiln 3 to the lower end and supplied from a fuel supply line (not shown) inside. There is provided a calcining furnace 6 provided with a combustion apparatus for fuel such as coal.

  The cement kiln 3 is a substantially cylindrical rotary kiln provided so as to be rotatable around an axis, and is disposed in a state where the axis is slightly inclined with respect to the horizontal direction. A preheater 2 for preheating the cement raw material is provided on the left side of the kiln bottom 3a in the drawing, and a burner 7 for heating the inside is provided on the right side of the kiln 3b in the drawing. The combustion gas generated by burning the fuel supplied from the fuel supply means 8 with the burner 7 flows toward the kiln bottom 3a opposite to the flow of the cement raw material. The cement raw material supplied from the kiln bottom 3a gradually increases in particle size as it approaches the kiln front 3b side, and grows to a certain particle size when it reaches the kiln front 3b. And is taken out from the front of the kiln 3b as a clinker. Further, a clinker cooler 4 for cooling the clinker obtained by the cement kiln 3 is provided in the front kiln 3b.

  A chlorine bypass pipe 11 is connected to a duct for sending the exhaust gas from the kiln bottom 3a of the cement kiln 3 to the lowermost cyclone 5d, and a part of the exhaust gas extracted by the chlorine bypass pipe 11 is removed from the rear bag filter 12 is provided with a chlorine bypass system 13 that removes the chlorine content.

Analyzing means 14 for analyzing the components in the cement clinker via the clinker cooler 4 is provided. The analyzing means 14 includes alkali measuring means 15 for measuring the alkali content R ₂ O in the cement clinker, and K ₂ O molar ratio measuring means 16 for measuring the molar ratio of K ₂ O in the alkali {K ₂ O / (K ₂ O + Na ₂ O)} and the molar ratio of SO ₃ to the alkali {SO ₃ / (K SO ₃ molar ratio measuring means 17 for measuring ₂ O + Na ₂ O)}.
Moreover, between this analysis means 14, the raw material supply means 1, and the fuel supply means 8, the potassium content adjustment means 18 which adjusts the potassium content in a cement raw material based on an analysis result, and the sulfur content in a fuel are adjusted. Sulfur content adjusting means 19 is provided. The potassium content adjusting means 18 operates the raw material supply means 1 so as to supply, for example, a large amount of clay containing a large amount of potassium among cement raw materials. Further, the sulfur content adjusting means 19 operates the fuel supply means 8 so as to supply, for example, a large amount of coal in the kiln fuel. Or these adjustment means 18 and 19 instruct | indicate to use more raw materials containing much potassium content, and fuel containing more sulfur contents, and an operator operates the raw material supply means 1 or the fuel supply means 8 based on the instruction | indication. You may do.

A method for producing a cement clinker using the cement production apparatus configured as described above will be described.
First, when a cement raw material mixed with limestone, silica, clay, iron oxide raw material or the like is supplied to the uppermost cyclone 5a of the preheater 2 by the cement raw material supply means, the cement raw material is indicated by a solid arrow in the figure. Then, as it falls sequentially to the lower cyclones 5b to 5d, it is preheated by the high-temperature exhaust gas from the cement kiln 3 rising from below, and finally introduced into the kiln bottom 3a of the cement kiln 3 from the lowermost cyclone 5d. Is done.

  And in this cement kiln 3, in the process gradually sent from the kiln bottom 3a side to the kiln front 3b side, it is heated and burned by the combustion exhaust gas from the burner 7, and becomes a cement clinker. Next, the cement clinker that has reached the front of the kiln 3b falls into the clinker cooler 4 and is sent to the right in the figure, as indicated by arrows in the figure. At this time, it is cooled to a predetermined temperature by the air supplied into the clinker cooler 4 and finally taken out from the clinker cooler 4.

By the way, the chlorine content contained in the cement raw material is volatilized mainly as alkali chlorides such as KCl and NaCl in a high temperature (about 1400 ° C.) atmosphere in the cement kiln 3, and the exhaust gas is the kiln bottom of the cement kiln 3. When the cement raw material is circulated from 3a to the preheater 2, it is cooled by preheating the cement raw material, and the chlorine content contained in the exhaust gas again moves to the cement raw material side. As a result, the chlorine content is transferred to the cement kiln 3 and the preheater 2. The phenomenon of circulating in the system is generated, and the chlorine concentration in the system gradually increases due to the chlorine content newly introduced into the system from the combustion exhaust gas or the cement raw material.
Therefore, a part of the exhaust gas is periodically or continuously extracted from the chlorine bypass pipe 11 and cooled to recover the chlorine content as an alkali chloride in the subsequent bag filter 11, thereby increasing the chlorine concentration in the system. To prevent it.

Then, in the cement manufacturing apparatus having a chlorine bypass system 13, in order to increase its chlorine bypass efficiency, alkali content _R 2 _O in the cement clinker by the analysis means 14 (= K 2 O + 0.658Na 2 O), alkali _{K 2} O molar ratio of _{{K 2 O / (K 2} O + Na 2 O)}, the molar ratio of SO ₃ in the alkali _{{SO 3 / (K 2 O} + Na 2 O)} were respectively measured in the medium, the measurement result Based on this, the cement raw material or fuel components are adjusted.
Specifically, the alkali content R ₂ O is adjusted to be 0.75% or less, preferably 0.6% or less as defined in JIS. Further, the K ₂ O molar ratio {K ₂ O / (K ₂ O + Na ₂ O)} in the alkali is 0.6 or more and 0.8 or less, and the molar ratio of SO _{3 to} the alkali {SO ₃ / (K ₂ O + Na _2). O)} is adjusted to be 0.4 or more and 0.85 or less.
In this case, in order to adjust the K ₂ O molar ratio in the alkali, in the raw material supply means 1, clay, glass or other waste containing a large amount of potassium oxide or potassium in the cement raw material, mixing of chemicals such as potassium carbonate The ratio is adjusted, and by increasing the mixing ratio, the potassium content in the cement raw material can be increased and the K ₂ O molar ratio can be increased. Moreover, in order to adjust the molar ratio of SO _{3 to} alkali, the mixing ratio of coal is adjusted as a low-sulfur fuel, and the sulfur content in the kiln fuel is increased by increasing the ratio of coal to coke. Can be reduced to increase the SO ₃ molar ratio.
Thus, the kiln is controlled by controlling the K ₂ O molar ratio in the alkali and the molar ratio of SO _{3 to} the alkali within a predetermined range while suppressing the alkali content R ₂ O in the cement clinker. The chlorine concentration in the raw material can be promoted, and the chlorine bypass efficiency can be increased.

Next, the analysis performed in order to confirm the influence of the chlorine concentration to the raw material containing a kiln by such adjustment is demonstrated.
Here, a theoretical calculation that combines thermodynamic equilibrium calculation and process simulation techniques to calculate the volatilization and condensation of chlorine and sulfur in the kiln from their equilibrium vapor pressure and diffusion of gas boundary films and pores of clinker particles. A simple model was constructed and the circulation behavior was analyzed.

A. Circulation behavior of chlorine and sulfur
A-1 Profiles of chlorine and sulfur in raw material First, the profiles of SO ₃ concentration and Cl concentration in the raw material in the kiln are shown in FIG. In the figure, the horizontal axis indicates the distance from the kiln before the kiln. The SO ₃ concentration gradually increases as it goes from the raw material inlet (80 m) to the outlet (0 m) of the kiln, and has a maximum value in the vicinity of 20 m, so that condensation of sulfur occurs between 20 and 80 m. I understand. The maximum value of SO ₃ concentration is just under 6 percent and is greater than 4% at the kiln inlet. Moreover, it can be seen that the SO ₃ concentration rapidly decreases from around 20 m toward 0 m, and the volatilization of sulfur occurs in the firing zone.
On the other hand, the amount of chlorine condensed at 40 to 80 m is not large. This is considered to be because the vapor pressure of KCl (g) is still higher at 40 to 80 m than sulfur (where (g) attached to the component composition is the gas phase, (l) is the liquid phase, (s ) Indicates a solid phase). Further, the volatilization of Cl progresses from 35 m to 0 m, and it can be seen that the start of volatilization occurs from the kiln raw material inlet side, that is, from the low temperature as compared with SO ₃ . The chlorine concentration in the clinker is 70 ppm, about 40 times for the kiln feed and about 4 times for sulfur.
Next, FIG. 3 shows a profile for each form of SO _{3 in} the raw material. Sulfur is present as CaSO ₄ (s) on the raw material inlet side of the kiln and changes to CaSO ₄ (l) as the temperature increases.
On the other hand, the amount of K ₂ SO ₄ (l) or Na ₂ SO ₄ (l) is smaller than that of calcium salt, and further decreases on the kiln raw material outlet side. This occurs when K ₂ O and Na ₂ O migrate into the oxide liquid phase.

Next, FIG. 4 shows the form of chloride in the raw material. In the vicinity of the raw material inlet of the kiln, the same amount of CaCl ₂ , KCl, and NaCl is decreased, but as the temperature rises, KCl and NaCl decrease and CaCl ₂ increases. That is, it can be seen that the cation corresponding to chlorine changes from K and Na to Ca. In addition, at 35 to 0 m, CaCl ₂ itself decreases due to the volatilization of Cl. Incidentally, the form of Cl volatilized in this area, since it is only KCl and NaCl as described later, when the CaCl ₂ is decreased _{CaCl 2 (l) + K 2} O (Na 2 O) (l) → 2KCl ( The reaction of (NaCl) (g) + CaO (l) has occurred.

Profile of chlorine and sulfur in A-2 gas FIG. 5 shows the profile of chlorine and sulfur in the gas. The gas containing sulfur was present as SO ₂ (g), the gas containing chlorine was present as KCl (g), NaCl (g), and HCl (g), and the other components were negligible amounts.
The SO ₂ concentration increases from 0 m to around 20 m, and it can be seen that SO ₂ is volatilized from the raw material. Since then, the concentration has gradually declined, and condensation to the raw material has occurred. The chloride concentration was KCl>NaCl> HCl, and the KCl concentration was about five times the NaCl concentration at the kiln outlet (80 m). The peak of the chlorine concentration was 50 to 60 m, which was on the low temperature side compared to sulfur.

B. Changes in SO ₃ / alkali oxide ratio Next, when the sulfur content of the coke of the burner was reduced from the basic simulation and when the K ₂ O and Na ₂ O concentrations in the raw material were changed, respectively, FIG. 6 shows the relationship between the SO ₃ / (K ₂ O + Na ₂ O) molar ratio and the SO ₃ and Cl concentrations of the raw material containing the kiln. In FIG. 6, the upper stage shows the SO ₃ concentration, and the lower stage shows the Cl concentration.
B-1 Change in Sulfur Content in Fuel When SO _{3 in} the clinker decreases from about 1.0% of the basic condition to 0.7% and 0.5% due to the change in sulfur content in the burner, SO ₃ / (K ₂ O + Na ₂ O) molar ratios are 1.53, 1.12 and 0.79, respectively, and the SO ₃ concentration of the kiln-containing material is 3.9%, 3.4% and 2.8%, respectively. While decreasing, the Cl concentration increases to 2,800 ppm, 4,300 ppm, and 7,200 ppm, respectively (indicated by a circle in FIG. 6).
The reason why the circulation behavior of sulfur and chlorine is changed by the change of SO _{3 in} the clinker will be discussed below.

B-1-a Changes in Kiln-containing Raw Material SO _{3 As described} in “A. Circulation Behavior of Chlorine and Sulfur”, sulfur is volatilized as SO ₂ and exists in the raw material as calcium sulfate or alkali sulfate and circulates. I found out that The volatilization of sulfate is represented by the formulas (1) to (3). Note that “molten salt” and “oxide” attached to the liquid phase components indicate the names of the liquid phases in which the respective components exist.

The reason why the increase in the sulfur content of the fuel will increase the SO ₃ concentration of the kiln-containing raw material, that is, the volatilization of SO _{2 in} the high temperature part will be examined. PSO ₂ is expressed as in equation (4), where the equilibrium constants in equations (1) to (3) are K ₁ , K ₂ , and K ₃ , respectively.

In this equation (4), it is assumed that the oxygen partial pressure PO ₂ is determined by the firing atmosphere and does not change with SO _{3 in} the clinker. Here, in order to increase PSO ₂ , it is necessary to increase the ratio of Ca, K, Na sulfate to oxide activity. Since sulfates exist only in molten salts that do not dissolve in the oxide solution, when SO _{3 in} the clinker increases, CaO and alkali oxides in the oxide solution are changed to sulfate by SO _3. Move into the molten salt. At this time, the concentration of CaO is high because C ₃ A and C ₄ AF are dissolved in the oxide solution, and even if part of the CaO changes to CaSO ₄ , the rate of decrease in concentration and activity is small, and aCaO is almost constant. while regarded as, alkali oxides _{would aK} 2 O decreases the density, ana ₂ O is reduced. When approaching the concentration 0 alkali oxides, alkali sulfate is not longer able to generate, the increase slowed, so that the CaSO ₄ is gradually increased instead.
Since aCaO can be regarded as almost unchanged, PSO ₂ is determined by aCaSO ₄ in the second term of equation (4). It can be seen that PSO ₂ increases as aCaSO ₄ increases with SO ₃ in the clinker.

B-1-b Changes in raw material Cl containing kiln Since the molten salt phase is composed of sulfate and chloride, when the sulfur content in the fuel decreases, it is described in “B-1 Change in sulfur content in fuel”. Thus, the molar fraction of CaSO ₄ decreases, and the molar fraction of KCl and NaCl relatively increases. As a result, the activity increases, volatilization of KCl and NaCl is promoted, and the Cl concentration of the raw material containing the kiln is considered to increase. FIG. 7 shows the molar flow rate ratio of Cl ⁻ with respect to the anion (Cl ⁻ + SO ₄ ²⁻ ) in the molten salt in the K _{5 to} K ₈ blocks when SO ₃ in the clinker is changed. _Here, the K 5 ~K ₈ block points to a specific area along the length of the kiln, by dividing the kiln from the entrance side of the raw material 8 blocks of _{K 1 ~K 8, K 1 ~K} 2 the (80～30M at a distance from the front kiln) _Kariyakitai, K 3 ~K ₅ (also 17～30M) desorption zone _a, K 6 ~K ₇ (also 2～17M) firing zone and cooling the _{K 8} It was considered a belt (also 0-2m).
It can be seen from FIG. 7 that as the SO ₃ in the clinker increases, the ratio of chlorine ions in the molten salt decreases.

B-2 Change in alkali concentration in raw material From FIG. 6, when the K ₂ O content of the basic condition in the raw material is increased from 0.39% to 0.71%, SO ₃ / (K ₂ O + Na ₂ O) The molar ratio drops from 1.53 to 1.09. At that time, the SO ₃ content of the kiln-containing material decreases from 4.0% to 3.4%, and Cl increases from 2,700 ppm to 6,900 ppm (indicated by x in FIG. 6). Also, when the basic condition Na ₂ O content in the raw material is increased from 0.26% to 0.47%, the SO ₃ / (K ₂ O + Na ₂ O) molar ratio decreases from 1.53 to 1.08. To do. At that time, the SO ₃ content of the kiln-containing material decreases from 4.0% to 3.7%, and Cl increases from 2,700 ppm to 3,900 ppm (indicated by Δ in FIG. 6).

Consider this phenomenon. When K ₂ O increases in Formula (2), the reaction proceeds to the left and the SO ₂ partial pressure decreases, but in addition, a change occurs in the sulfate to maintain Formula (4). That is, CaSO ₄ changes to K ₂ SO ₄ according to the equation (5). Similarly, Na ₂ SO ₄ changes to K ₂ SO ₄ .

Further, when Na ₂ O increases, CaSO ₄ and K ₂ SO ₄ change to Na ₂ SO ₄ . Since PSO ₂ is substantially proportional to aCaSO ₄ as described above, if K ₂ O or Na ₂ O increases, CaSO ₄ changes to K ₂ SO ₄ or Na ₂ SO ₄ and aCaSO ₄ decreases. As a result, PSO ₂ is lowered and sulfur circulation is suppressed.
If the circulation of sulfur is suppressed, as described in “Changes in raw material Cl containing B-1-b kiln”, the molar fraction and activity of KCl and NaCl are relatively increased, and the volatilization of chlorine is promoted. Will be. In particular, when K ₂ O increases, as described in “Profile of chlorine and sulfur in A-1 raw material”, CaCl ₂ (l) + K ₂ O (l) → 2KCl ( g) Since the reaction of + CaO (l) is promoted, it can be seen that the volatilization of KCl increases. In addition, Na 2 _O is compared to K _{2 O,} easily dissolved in the oxide liquid phase at elevated temperatures, whereas hardly volatilize, K 2 _O from the easily volatilized, increase in K 2 _O molar ratio of chlorine One of the reasons is to promote volatilization.
As mentioned above, the SO ₃ and Cl farming degree of the kiln-containing raw material can be arranged by the relationship between the molar ratio of SO ₃ and the alkali oxide. In particular, the Cl concentration is the ratio of K ₂ O and Na ₂ O in the alkali. You can see that it is affected.

On the other hand, FIG. 8 shows the relationship between the chlorine concentration of the kiln-containing raw material and the K ₂ O / (K ₂ O + Na ₂ O) molar ratio in the clinker calculated by process simulation when the chlorine amount per clinker is 70 ppm. It is. As calculation conditions, SO ₃ in the clinker is varied to 0.53, 0.75, 1.02%, and R ₂ O is varied to 0.52, 0.73%.
Since the molar ratio of K ₂ O / (K ₂ O + Na ₂ O) in a cement factory is about 0.5, this is made from clay, glass and other waste containing a large amount of potassium oxide or potassium, and chemicals such as potassium carbonate. It can be seen that the chlorine concentration of the raw material containing the kiln increases by 20% or more under any condition when the pressure is increased to 0.6, and the chlorine removal effect of the chlorine bypass can be improved. That is, by increasing the K ₂ O / (K ₂ O + Na ₂ O) molar ratio, a sufficient amount of chlorine can be removed by a small amount of gas extraction from the chlorine bypass pipe, or a large amount can be obtained even at the same extraction amount. It becomes possible to remove chlorine.
However, it is impossible to make the K ₂ O / (K ₂ O + Na ₂ O) molar ratio larger than 0.8 unless sodium is removed, and if it is carried out, wasteful separation costs will occur.

The concentration ratio of chlorine is calculated by the following formula A from the chlorine concentration of the raw material containing the kiln in FIG. 8 and the chlorine concentration of 70 ppm in the clinker, and the chlorine removal rate when the extraction rate of the chlorine bypass is 2% is expressed by the formula B What was calculated | required in FIG. 9 is shown.
k = C1 / Cc-1 ... A
In this formula A, k: concentration rate (−), C1: chlorine concentration (ppm) of raw material containing kiln, Cc: chlorine concentration (ppm) in clinker.
R = bk / (bk + 1) ... B
In this formula B, R: chlorine removal rate (−), b: extraction rate (−), k: concentration rate (−).

From FIG. 9, when the K ₂ O / (K ₂ O + Na ₂ O) molar ratio increases from 0.5 to 0.6, the chlorine removal rate improves by 4 to 5% in difference and increases to 0.8. Then, it improves 11-15%, and it turns out that the effect which improves the removal rate of chlorine is large.
FIG. 10 shows the relationship between the chlorine concentration of the kiln-containing raw material and the SO ₃ / (K ₂ O + Na ₂ O) molar ratio in the clinker when the K ₂ O / (K ₂ O + Na ₂ O) molar ratio is 0.2 to 0.8. Is obtained from FIG. FIG. 11 shows the chlorine removal rate when the same calculation as in FIG. 9 is performed and the extraction rate of chlorine bypass is 2%.

Thus, SO ₃ / as _{(K 2 O + Na 2 O} ) molar ratio is small, increases the chlorine concentration of the kiln containing raw material, in order to improve the removal rate of chlorine, 0.5 _{R 2} O clinker normal The SO ₃ / (K ₂ O + Na ₂ O) molar ratio is reduced by reducing SO ₃ in the clinker to 0.60% or less by using a fuel such as coal of 0.55% or more and low sulfur. It is particularly effective to set it to 0.85 (= 0.60 / 0.55 × 0.775 (0.775 is a conversion coefficient)) or less.
In addition, R ₂ O is defined as 0.75% or less by Portland cement JIS, and even if low sulfur fuel is used, it is difficult to make SO ₃ in clinker 0.4% or less. Therefore, the minimum value of the SO ₃ / (K ₂ O + Na ₂ O) molar ratio is 0.4 / 0.75 × 0.775 = 0.41 (0.775 is a conversion coefficient).
As is apparent from the above description, according to the cement manufacturing apparatus of this embodiment, the K ₂ O / (K ₂ O + Na ₂ O) molar ratio and the SO ₃ / (K ₂ O + Na ₂ O) molar ratio in the cement clinker. Since the potassium content of the cement raw material or the sulfur content of the kiln fuel is adjusted based on the measurement results, the chlorine concentration of the raw material containing the kiln is promoted without increasing the alkali content in the cement clinker. A sufficient amount of chlorine can be removed by extracting a small amount of gas from the chlorine bypass pipe, or a large amount of chlorine can be removed with the same amount of extraction.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention. For example, in an embodiment, both the K ₂ O / (K ₂ O + Na ₂ O) molar ratio and the SO ₃ / (K ₂ O + Na ₂ O) molar ratio in the cement clinker are measured to determine the potassium content of the cement raw material or the kiln fuel. The sulfur content is adjusted, but only one of the K ₂ O / (K ₂ O + Na ₂ O) molar ratio or SO ₃ / (K ₂ O + Na ₂ O) molar ratio is measured, and the corresponding cement raw material Or you may make it adjust the component of a kiln fuel. In either case, the alkali content R ₂ O is 0.75% or less as defined by JIS, and without increasing the alkali content to 0.75% or more, K ₂ O / (K ₂ O + Na _{The 2} O) molar ratio and the SO ₃ / (K ₂ O + Na ₂ O) molar ratio are adjusted to be within a predetermined range.
Further, the alkali content of R _{2 O} in the embodiment has been adapted to measure the cement clinker, may be determined for cement materials.
Furthermore, although the adjustment of the potassium content is performed with the cement raw material, in addition to this, the adjustment with the kiln fuel containing an alkali may be used in combination. In addition, although the sulfur content is adjusted with kiln fuel, in addition to this, adjustment with a cement raw material containing a sulfur content may be used in combination.

It is a flowchart which shows one Embodiment of the cement manufacturing apparatus which concerns on this invention. It is a graph showing the profile of the SO ₃ concentration and the Cl concentration in the raw materials in the kiln units. It is a graph showing a profile of each form of SO ₃ in the raw materials in the kiln units. It is a graph which shows the profile for every form of the chloride in the raw material in each part of a kiln. It is a graph which shows the profile of chlorine and sulfur in gas in each part of a kiln. _{SO 3 / (K 2 O +} Na 2 O) molar ratio and kiln-containing material of _SO 3 in the clinker, is a graph showing the relationship between the Cl concentration. Anions in the molten salt in the kiln within each block when varying the SO ₃ in the clinker ^{_{(Cl - + SO 4 2-)}} Cl for ^- is a graph showing the molar flow rate ratio. It is a graph showing the relationship between the _{K 2 O / (K 2 O} + Na 2 O) molar ratio in the chlorine concentration of kiln-containing raw materials and clinker. It is a graph showing the relationship between the _{K 2 O / (K 2 O} + Na 2 O) molar ratio and chlorine removal rate in the clinker. Is a graph showing the relationship between the _{SO 3 / (K 2 O +} Na 2 O) molar ratio and the concentration of chlorine in the kiln containing material in the clinker. Is a graph showing the relationship between the _{SO 3 / (K 2 O +} Na 2 O) molar ratio and chlorine removal rate in the clinker.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cement raw material supply means 2 Preheater 3 Kiln 3a Kiln bottom 3b In front of kiln 4 Clinker cooler 5a-5d Cyclone 6 Calciner 7 Burner 8 Fuel supply means 11 Chlorine bypass pipe 12 Bag filter 13 Chlorine bypass system 14 Analytical means 15 Alkali measuring means 16 K ₂ O molar ratio measuring means 17 SO ₃ molar ratio measuring means 18 Potassium content adjusting means 19 Sulfur content adjusting means

Claims (8)

An operation control method for a cement manufacturing apparatus including a chlorine bypass system for extracting a chlorine content by extracting a part of exhaust gas from a kiln bottom of a kiln,
A method for controlling operation of a cement production apparatus, comprising measuring a molar ratio of K ₂ O in an alkali in a cement clinker and adjusting an amount of potassium in a cement raw material based on the measurement result. The operation control method for a cement manufacturing apparatus according to claim 1, wherein the amount of potassium is adjusted so that the molar ratio of K ₂ O in the alkali is 0.6 or more and 0.8 or less. Furthermore, by measuring the molar ratio of SO ₃ in the alkali in the cement clinker, the measurement result based on the cement manufacturing apparatus according to claim 1, wherein adjusting the amount of sulfur in the kiln fuel Operation control method. The operation control method for a cement manufacturing apparatus according to claim 3, wherein the amount of sulfur is adjusted so that the molar ratio of SO _{3 to} alkali is 0.4 or more and 0.85 or less. An operation control method for a cement manufacturing apparatus including a chlorine bypass system for extracting a chlorine content by extracting a part of exhaust gas from a kiln bottom of a kiln,
An operation control method for a cement production apparatus, characterized in that a molar ratio of SO _{3 to} alkali in a cement clinker is measured, and an amount of sulfur in the kiln fuel is adjusted based on the measurement result. In a cement manufacturing apparatus equipped with a chlorine bypass system that extracts a portion of exhaust gas from the kiln bottom of the kiln to remove chlorine,
A raw material supply means capable of supplying a cement raw material containing potassium and a K ₂ O molar ratio measuring means for measuring the molar ratio of K ₂ O in the alkali in the cement clinker are provided. These raw material supply means and K ₂ A cement manufacturing apparatus characterized in that potassium content adjusting means for adjusting the amount of potassium in the cement raw material according to the measured molar ratio of K ₂ O is provided between the O molar ratio measuring means. . Furthermore, a fuel supply means capable of supplying a kiln fuel containing sulfur and an SO ₃ molar ratio measuring means for measuring a molar ratio of SO _{3 to} alkali in the cement clinker are provided. These fuel supply means and SO ₃ The sulfur content adjusting means for adjusting the amount of sulfur content in the kiln fuel according to the measured molar ratio of SO ₃ is provided between the molar ratio measuring means and the molar ratio measuring means. Cement production equipment. In a cement manufacturing apparatus equipped with a chlorine bypass system that extracts a portion of exhaust gas from the kiln bottom of the kiln to remove chlorine,
Fuel supply means capable of supplying a kiln fuel containing sulfur and SO ₃ molar ratio measuring means for measuring the molar ratio of SO _{3 to} alkali in the cement clinker are provided. These fuel supply means and SO ₃ molar ratio A cement manufacturing apparatus, characterized in that a sulfur content adjusting means for adjusting the amount of sulfur content in the kiln fuel is provided between the measuring means and the measured molar ratio of SO ₃ .

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