JP2010126411A - Exhaust gas treatment method for cement firing equipment and treatment system therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment system for cement firing equipment which can securely prevent the deposition and solidification of dust accompanied by an extraction gas by the minimum gas introduction without increasing a heat load in the cement production equipment. <P>SOLUTION: A gas extraction duct 10 connected to the gas exhaust duct 2b of the kiln inlet part 2 in a cement kiln 1 and extracting an extraction gas is formed by a single tube. The treatment system is also provided with a cooling means having: a cooling gas introduction duct 25 opening to the inside of the gas extraction duct 10, and, by blowing a gas for cooling to the circumferential direction of the gas extraction duct 10, while cooling the extraction gas, forming the swirling flow of the extraction gas to the axial direction; and a gas feeding means feeding the gas for cooling to the cooling gas introduction duct 25. Also, the connection part between the gas extraction duct 10 and the gas exhaust duct 2b is provided with stirring means 26a to 26d for an extraction gas blowing a gas to the circumferential direction of the gas extraction duct 10 and also on the side of the gas exhaust duct 1b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment method and treatment system for a cement firing facility using a chlorine bypass that suppresses an increase in the chlorine concentration in the system of the cement firing facility.

  In recent years, in order to solve the problem of waste disposal, various types of waste have been used as part of cement raw materials or part of heating fuel in cement kilns. However, in particular, when waste such as synthetic resin is introduced into the cement kiln as part of the fuel, a volatile chlorine component is generated during combustion. Such a chlorine component is accompanied by the exhaust gas discharged from the cement kiln and is sent to the upstream preheater. However, if the ambient temperature becomes lower than the melting point as it is transferred to the upper stage of the preheater, it is condensed. Then, it adheres to the cement raw material, is sent again into the cement kiln, and evaporates again as the ambient temperature rises.

  As described above, the chlorine component taken into the system of the cement firing facility is repeatedly circulated and evaporated in the cement kiln and the preheater, and the chlorine component generated from the newly input waste is added thereto. As a result, the concentration of the preheater is increased due to the coating, and the stable operation is hindered, and the quality of the manufactured cement clinker is adversely affected.

  Therefore, for example, in Patent Document 1 below, a process of extracting a part of the kiln exhaust gas from the kiln, a process of cooling the extracted exhaust gas to below the melting point of the chlorine compound, and dust in the exhaust gas are coarsened by a classifier. A kiln exhaust gas treatment method comprising a process of separating powder and fine powder, and a process of returning the separated coarse powder to the kiln and sending the fine powder to the downstream side of the classifier, wherein the extraction amount of the kiln exhaust gas The ratio is more than 0% and 5% or less, the separation particle size in the classifier is 5 μm to 7 μm, and the amount of fine powder delivered is 0.1% or less of the kiln production amount. A kiln exhaust gas treatment method using chlorine bypass has been proposed.

  By the way, as described in the following Patent Document 2, in the above-mentioned chlorine bypass, when cooling the extracted exhaust gas below the melting point of the chlorine compound, in the extraction duct (probe) connected to the rising duct for the kiln exhaust gas As a result of rapid cooling of the extracted exhaust gas to 600 to 700 ° C. or less, volatile components such as chlorine are condensed in the fine powder portion of the dust entrained in the exhaust gas. It is known that high fine powder can be effectively discharged out of the system.

  Therefore, in this document, a double pipe structure probe (bleeding duct) having an inner pipe and an outer pipe is connected to the exhaust duct, and a part of the exhaust gas is extracted through the inner pipe, A cooling gas is supplied to the fluid passage between the outer pipe and the cooling gas is guided inward of the tip of the inner pipe to be mixed into the exhaust gas. An exhaust gas cooling method in the formed chlorine bypass has been proposed.

  However, in the exhaust gas cooling method, a horizontal portion is formed on the probe at the connection portion with the rising duct. In addition, at the tip of the probe (the connection part), a part of the exhaust gas flowing from the rising duct and the inner pipe and the outer pipe flow in the direction opposite to the flow of the exhaust gas and are supplied to the tip part. Since the cooling gas to be mixed is mixed, stagnation of the mixed gas is generated at the tip portion, and the flow velocity is slowed down.

  As a result, dust having a relatively large particle size among the dusts mainly composed of cement raw materials containing chlorine components entrained in the exhaust gas is formed with the horizontal portion as the operating time elapses. As a result of accumulating at the tip of the probe having a slow flow rate and eventually solidifying and generating coaching, the cross-sectional area of the bleed duct becomes small, and there is a possibility that the exhaust gas cannot be bleed smoothly.

  Therefore, if the flow rate of the cooling gas is increased to prevent the stagnation of the mixed gas, the exhaust gas system from the kiln exhaust gas duct to the pre-heater is maintained at a negative pressure, so the temperature is low. The cooling gas rises and flows into the preheater from the duct, and as a result, there arises a problem that a heat amount is lost in the preheater. In addition, it is conceivable that the supply pipe for supplying the cooling gas to the fluid passage between the inner pipe and the outer pipe is brought close to the connecting portion, but usually a thick heat insulating material is applied to the outer surface of the rising duct. Therefore, it is practically difficult to avoid the stagnation of the mixed gas at the tip.

In addition, in the exhaust gas cooling method, since the probe has a double-pipe structure, the operation is stopped, and the dust adhered and deposited on the inner wall surface of the inner pipe is manually destroyed and blown away. However, there is a problem in that it is difficult to insert a tool such as an air rod, iron spatula, or bar for working into a desired location in the inner tube because the outer tube is obstructed.
Japanese Patent No. 3318714 JP-A-11-35355

  The present invention has been made in view of such circumstances, and it is ensured that dust accompanying the extraction gas is deposited and solidified in the extraction duct by introducing a minimum amount of gas without increasing the heat load in the cement manufacturing facility. It is an object of the present invention to provide an exhaust gas treatment system for cement firing equipment that can be prevented.

  In order to solve the above-mentioned problem, the invention described in claim 1 is characterized in that a part of exhaust gas containing dust discharged from a cement kiln for firing cement raw material and sent to a preheater for preheating the cement raw material is used as extraction gas. An exhaust gas treatment system for a cement firing facility for extracting and removing chlorine compounds contained in the extracted gas, wherein the exhaust gas treatment system is connected to an exhaust duct at the bottom of the preheater or the kiln bottom of the cement kiln. An extraction duct for extracting the extraction gas; a cooling means for cooling the extraction gas extracted from the extraction duct to a melting point of a chlorine compound or less; and the dust having a predetermined particle size or more from the extraction gas cooled by the cooling means. A solid-gas separation means for separating the gas and the extracted gas from which the dust having a predetermined particle size or more is separated in the solid-gas separation means A dust trapping means for collecting and removing fine dust particles having a predetermined particle size or less, and an induction fan provided on the downstream side of the dust trapping means for sucking the extraction gas. The cooling means is formed by a pipe, and the cooling means opens into the extraction duct and blows cooling gas in the circumferential direction of the extraction duct, whereby the extraction gas swirls in the axial direction while cooling the extraction gas. And a supply means for supplying the cooling gas to the cooling gas introduction duct, and gas is supplied to the connection portion between the extraction duct and the exhaust duct. The extraction gas is stirred in the direction and is blown toward the exhaust duct.

  According to a second aspect of the present invention, in the first aspect of the present invention, the stirring means is disposed at intervals along the circumferential direction of the extraction duct, and the gas is swirled by the extraction gas. It has the same circumferential direction as that of the flow, and has a plurality of gas supply pipes ejected to the exhaust duct side.

  Furthermore, the invention described in claim 3 is the side wall of the exhaust duct according to claim 1 or 2, wherein the gas is blown toward the exhaust duct side below the connection part of the extraction duct. A second stirring means is provided.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the extraction gas flow rate adjusting device is provided on the inlet side of the solid gas separation means, and the dust trapping means. And a chlorine concentration detection device for detecting the chlorine concentration of the fine dust collected by the inside of the bottom part of the preheater or the kiln bottom of the cement kiln and in the vicinity of the connection part of the extraction duct, Dispersing means for dispersing the cement raw material in the exhaust gas is provided, driving means for adjusting the amount of the cement raw material dispersed by the dispersing means, temperature detecting means for detecting the temperature of the extraction gas, and temperature detection A first controller for controlling the driving means based on the temperature detected by the means to maintain the temperature of the extraction gas in a range of 950 ° C to 1150 ° C; Based on the detection signal of the chlorine concentration detection means, even if the chlorine concentration of the fine dust collected by the bag filter deviates from the range of 5 to 20% by the control by the first control device, The predetermined amount in the solid gas separation means is controlled by controlling the amount of the extraction gas sucked by the attraction fan and / or the flow rate adjustment device of the extraction gas so that the chlorine concentration of the fine dust is in the range of 5 to 20%. And a second control device that adjusts the particle size within a range of 12 μm to 30 μm.

  The invention according to claim 5 is the invention according to claim 4, wherein the solid-gas separation means is a cyclone classifier and the dust trapping means is a bag filter. Is.

  Further, the invention according to claim 6 is the invention according to claim 4 or 5, wherein the dispersing means is disposed below the outlet of the raw material chute for feeding the cement raw material from the preheater to the kiln bottom. It is a dispersion plate that is provided so as to be able to move in and out directly below the drop, and disperses the cement raw material falling from the drop in the exhaust gas.

  In the invention according to any one of claims 1 to 6, a cooling gas is blown into the extraction duct from the cooling gas introduction duct, and a swirling flow of the extraction gas is formed in the extraction duct in the axial direction. The dust extraction in the extraction duct can be prevented while cooling the extraction gas.

  In addition, the connection part between the extraction duct and the exhaust duct is provided with a stirring means for the extraction gas that blows gas toward the exhaust duct in the circumferential direction of the extraction duct. In this case, the swirling flow of the extraction gas can be generated. Therefore, even in the vicinity of the connection portion of the extraction duct where the cooling air introduction duct is difficult to arrange with the exhaust duct, the dust having a relatively large particle size is blown away by the swirling flow, thereby being fixed and cured on the inner wall. Can be prevented.

As a result, it is possible to reliably prevent the dust accompanying the extraction gas from being accumulated and solidified in the extraction duct by introducing a minimum amount of gas without increasing the heat load in the cement manufacturing facility.
In addition, even if dust is accumulated in the extraction duct, there is an advantage that maintenance work is facilitated because the extraction duct is formed of a single pipe.

  Here, the stirring means can be configured by arranging a plurality of gas supply pipes at intervals along the circumferential direction of the extraction duct, as in the invention described in claim 2. . At this time, if the gas supply pipe is provided so that the gas is in the same circumferential direction as the swirling flow of the extraction gas and jetted to the exhaust duct side, in the vicinity of the inlet from the exhaust duct to the extraction duct, This is suitable because a swirling flow of the extraction gas can already be formed.

  Further, in addition to the agitation means, as in the invention according to claim 3, the second agitation in which gas is blown toward the exhaust duct side wall of the exhaust duct and below the connection part of the extraction duct By providing the means, dust having a relatively large particle size, which tends to stray from the exhaust duct side into the bleed duct, can be pushed back to the exhaust duct side to suppress the inflow into the bleed duct. As a result, the particle size distribution of the dust introduced from the bleed duct can be mainly composed of a relatively small one that easily condenses chlorine compounds.

  By the way, when the chlorine bypass which has the structure of Claim 1 was used, this inventor etc. also examined the influence which the chlorine concentration and the particle size of a fine dust have on handling property.

  First, although the average particle | grains of cement raw material powder are distributed from the maximum 200 micrometers to the minimum several micrometers, they are about 20 micrometers-about 30 micrometers in general. Therefore, when the classification particle size of the dust from the extraction gas is set to 10 μm or less, most of the dust finally collected from the extraction gas becomes chlorine particles, which are mixed with ultrafine cement raw material powder. Conceivable.

  Therefore, when the classified particle size is 10 μm or less, in addition to the rapid increase in chlorine concentration, the collected fine dust becomes cotton-like, resulting in extremely deteriorated handling properties and clarification of chlorine components. As a result, it has been found that coaching that causes blockage and clogging of equipment is likely to occur. It has also been found that if the chlorine concentration in the fine powder dust is suppressed to 20% or less, adhesion of fine powder dust and clogging due to coating can be prevented in the conveyance process.

  Next, the extraction gas from the cement kiln is cooled to below the melting point of the chlorine compound, the dust having a particle size of about 25 μm or more is separated from the extraction gas by a cyclone type classifier, and then the fine dust having a particle size of about 25 μm or less by a bag filter. When collecting the cement raw material actively in the extraction gas to change the dust concentration in the extraction gas and seeing the effect on the chlorine concentration of the fine dust. As shown, it was confirmed that the chlorine concentration decreased as the dust concentration increased.

  Further, if the cement raw material is positively dispersed in the exhaust gas from the extracted cement kiln, the dust concentration in the extraction gas increases and the temperature of the exhaust gas decreases. Then, it was found that this relationship is generally proportional as shown in FIG.

  Therefore, from FIG. 5 and FIG. 6, as shown in FIG. 7, the dust concentration in the extracted gas is adjusted by adjusting the temperature of the extracted gas by dispersing the cement raw material, and finally collected fine dust It came to the knowledge that the chlorine concentration of can be easily controlled. And it became clear by the said confirmation test that in order to make the said chlorine concentration into 20% or less which does not affect the handling property mentioned above, the temperature of extraction gas should just be made into 1150 degreeC or less.

  Further, when separating the coarse dust from the extracted gas by the cyclone classifier, if the classification particle size is reduced, the particle size of the fine dust is reduced, so that the chlorine concentration in the fine dust is also increased. However, when the classification particle size is set to 10 μm or less as described above, most of the dust finally collected from the extraction gas becomes chlorine particles, and the chlorine concentration rapidly increases thereby. More preferably, if the adjustment is made within a range of 12 μm or more, the chlorine concentration can be suppressed to 20% or less as long as the temperature of the extraction gas is set to 1150 ° C. or less.

  Therefore, according to the invention according to any one of claims 4 to 6, chlorine in the system is collected by collecting and removing fine dust dust having a high chlorine concentration contained in the extraction gas by the dust trapping means. It is possible to prevent the concentration from increasing. In addition, by dispersing the cement raw material in the exhaust gas at the bottom of the preheater where the extraction gas is extracted or the kiln bottom of the cement kiln, the temperature of the extraction gas is easily maintained in the range of 950 ° C to 1150 ° C. The chlorine concentration of the fine dust finally collected can be reduced to 20% or less.

  For this reason, while being excellent in the handling property of the said fine powder dust, the chlorine component contained in the said fine powder dust during conveyance does not have a possibility that problems, such as obstruction | occlusion and clogging, may arise, and can operate stably.

  In addition, since the classification particle size in the solid-gas separation means may be adjusted within a range of 12 μm to 30 μm, for example, a general-purpose cyclone classifier can be used as the solid-gas separation means, which may increase the equipment cost. Nor.

  Here, the temperature of the extraction gas is set to 950 ° C. or more, and as a result, the chlorine concentration in the fine dust is set to 5% or more. When the cement raw material is dispersed in the exhaust gas so that the temperature of the extraction gas becomes 950 ° C. or less, This is because the heat loss becomes large and the economy is inferior, and the dust gas dust concentration becomes excessively high. As a result, the volume of fine dust that is finally collected and removed becomes large, which is inconvenient.

  Further, the classification particle size in the solid-gas separation means is set to 12 μm to 30 μm, as described above, if the classification particle size is less than 12 μm, the ratio of chlorine particles in the fine dust rapidly increases, and as a result, the chlorine in the fine dust This is because it is difficult to suppress the concentration to 20% or less. On the other hand, if the classified particle size exceeds 30 μm, the amount of fine dust to be finally disposed increases, which is uneconomical.

  Further, as described above, as the cement raw material that is dispersed in the exhaust gas and increases the dust concentration in the extraction gas, the cement raw material that is introduced into the kiln bottom through the raw material chute from the lowest stage of the preheater is used. For example, it is not necessary to significantly change existing equipment, and since the temperature of the cement raw material is high, it is necessary to disperse a relatively large amount to adjust the temperature. The chlorine concentration of the fine dust can be easily reduced to 20% or less.

  Further, in parallel with the dispersion of the cement raw material charged from the raw material chute to the kiln bottom, the cement raw material at 600 ° C. to 700 ° C. in the preheater and the temperature before being conveyed to the preheater are 50 ° C. to 100 ° C. When raw materials of cement as low as ℃ are supplied for temperature adjustment in the kiln bottom, these cement materials are much lower in temperature than the cement material from the material chute. By dispersing in a small amount, the temperature of the extraction gas can be efficiently reduced.

  On the other hand, in this case, since the dust concentration in the extraction gas with respect to the temperature of the extraction gas is relatively low, the chlorine concentration of the fine dust tends to be high. Therefore, by adjusting the predetermined particle size in the solid-gas separation means to a larger particle size within a range of 12 μm to 30 μm, and in the inventions according to claims 3 to 5, the fine dust is controlled by a second controller. The chlorine concentration can be reduced to 20% or less by adjusting the predetermined particle size in the solid-gas separation means so that the chlorine concentration in the range is 5 to 20%.

  Further, in the invention according to any one of claims 4 to 6, the temperature of the extraction gas is increased by dispersing the cement raw material, that is, the dust concentration in the extraction gas is increased more than before, and finally the chlorine concentration of the fine dust. Therefore, the accumulation of dust on the inner wall of the bleed duct is likely to occur.

  However, since the dust deposited on the inner wall remains as a powder mainly composed of cement raw material, it can be easily blown away by the gas from the dust removal nozzle. As a result, in the inventions according to claims 4 to 6, a remarkable dust removal effect can be obtained particularly by the dust removal nozzle.

1 to 4 show an embodiment of an exhaust gas treatment system for a cement firing facility according to the present invention.
First, a cement manufacturing facility provided with the exhaust gas treatment system will be described with reference to FIG. 1. In the figure, reference numeral 1 denotes a cement kiln for firing cement raw materials. The cement kiln 1 is a rotary kiln provided so as to be rotatable around an axis, and includes a kiln butt housing 2a for supporting the rotary portion and a rising portion (exhaust duct) 2b at the left end in the figure. A kiln bottom 2 is provided.

  A preheater 3 for preheating the cement raw material is provided on the upstream side of the kiln bottom 2, and a main burner for heating the inside is provided in front of the right kiln (not shown) in the drawing. Is provided.

  Here, the preheater 3 is composed of a plurality of (for example, four) cyclones arranged in series in the vertical direction, and the cement raw material is supplied to the uppermost (fourth) cyclone 3a. A raw material chute 4 is connected to the bottom of the cyclone 3a to send the internal cement raw material to the kiln bottom 2 of the cement kiln 1.

  On the other hand, an exhaust pipe 5 for supplying the combustion exhaust gas discharged from the cement kiln 1 to the lowermost cyclone is connected to the rising part 2b of the kiln bottom part 2, and is discharged from the upper part of the uppermost cyclone. Exhaust exhaust gas is exhausted through an exhaust line by an exhaust fan.

And the exhaust gas treatment system called a chlorine bypass is attached to the cement manufacturing equipment which consists of the said structure.
This processing system is for extracting a part of exhaust gas containing dust discharged from the cement kiln 1 and sent to the preheater 3 as extraction gas, and removing chlorine compounds contained in the extraction gas. In the figure, reference numeral 10 denotes an extraction duct that is connected to a rising portion (rising duct) 2b of the kiln bottom 2 of the cement kiln 1 and extracts the extracted gas.

  And in this processing system, the cooling means 11 which cools the extraction gas in the extraction duct 10 to below melting | fusing point of a chlorine compound, and the cyclone type which isolate | separates dust more than predetermined particle size from the extraction gas cooled by this cooling means 11 A classifier (solid gas separating means) 12, a bag filter (dust capturing means) 13 for collecting and removing fine dust accompanying the extracted gas from which dust of a predetermined particle size or more has been separated in the cyclone type classifier 12; An induction fan 14 is provided on the downstream side of the bag filter 13 and sucks the extracted gas.

  Here, as shown in FIGS. 2 to 4, the bleed duct 10 is a single pipe having an inner diameter of 600 mmφ to 1000 mmφ, and a horizontal portion 10a that is substantially horizontal is formed in the vicinity of the connection portion with the rising portion 2b. A rising portion 10 b is formed from the horizontal portion 10 a toward the cyclone type classifier 12. In addition, the code | symbol 24 in a figure is the heat insulating material constructed in the outer periphery of the standup | rising part 2b. A cooling means 11 is provided at the horizontal portion 10 a of the bleed duct 10.

  The cooling means 11 includes a cooling air (gas) introduction duct 25 provided in the horizontal portion 10 a of the extraction duct 10, and a cooling fan (supply means) (not shown) that supplies cooling air to the cooling air introduction duct 25. And an auxiliary cooling unit including a stirring unit and a second stirring unit, and the temperature of the bleed gas is set to the melting point of the chlorine compound (600 to 700 ° C.) by the cooling air. ) It cools to the following. Here, the cooling air introduction duct 25 is provided at the upper part of the horizontal portion 10 a of the extraction duct 10, and the opening is arranged so as to blow cooling air along the circumferential direction of the extraction duct 10.

  In addition, on the side wall of the rising portion 2b and on the peripheral edge of the opening of the extraction duct 10, there is an extraction gas stirring means for blowing air (gas) in the circumferential direction of the extraction duct 10 and toward the rising portion 2b. Is provided. As shown in FIGS. 2 and 3, the agitation means includes air (gas) supply pipes 26 a to 26 d arranged at a total of four locations along the circumferential direction of the extraction duct 10, that is, the upper and lower portions and both side portions. And a blower fan (not shown) for supplying air to the air supply pipes 26a to 26d.

  Note that the air supply pipes 26a to 26d provided at these four locations are directed in the same direction as the cooling air introduction duct 25 provided in the extraction duct 10, that is, in the same circumferential direction as the swirling flow of the extraction gas. It is provided so as to blow out air toward the 2b side.

  By the way, when the swirl flow is generated in the rising pipe 2b in the vicinity of the inlet of the extraction duct 10 by the air supply pipes 26a to 26d, the downward flow shown in the right half of FIG. It is hindered by the flow of the exhaust gas rising in the rising portion 2b, and the flow velocity gradually decreases. And the speed becomes the slowest at the bottom of the swirl flow. And in the part where the flow velocity of this swirling flow is slow, dust having a relatively large particle size among the dust in the exhaust gas easily strays into the extraction duct 10 and easily accumulates on the inner wall.

  On the other hand, the upward flow shown in the left half of FIG. 3 of the swirling flow is promoted by the flow of the exhaust gas rising in the rising portion 2b, and the flow velocity gradually decreases. And the speed becomes the fastest at the top of the swirl flow.

  Therefore, as schematically shown in FIG. 3 by the lengths of the arrows, the flow rate of the swirling flow is slow in the present embodiment, and the air supply pipes arranged on the right side and the bottom in FIG. The amount of air blown out from 26a, 26b is set to be larger than the amount of air blown out from the air supply pipes 26d, 26c arranged on the left side and top bottom portion in FIG. Thereby, in the part where the speed of the swirl flow is slow, dust having a relatively large particle size among the dust in the exhaust gas is prevented from staying and straying into the extraction duct 10.

  Further, as shown in FIG. 2, the amount of air blown out from the air supply pipes 26a to 26d into the rising portion 2b is agitated while swirling only the exhaust gas in the vicinity of the inlet of the extraction duct 10 and extracted as it is. The amount introduced into the duct 10 is set.

  Further, as shown in FIGS. 2 and 4, an air blowing pipe 27 having a horizontally long opening is provided on the side wall of the rising portion 2 b and below the connection portion of the extraction duct 10. The air blowing pipe 27 and a blower fan (not shown) that supplies air to the air blowing pipe 27 constitute second stirring means for blowing air toward the rising portion 2b.

  In the air blowing pipe 27, the horizontally long opening is divided into a plurality of (five in the figure) outlets 28a to 28e in the horizontal direction, and the air volume can be adjusted for each of the outlets 28a to 28e. It has become. And in this embodiment, the quantity of the air which blows off from the blower outlets 28a and 28b located under the part where the speed of the swirl flow becomes slow is the blower outlet located under the part where the speed of the swirl flow becomes fast. 28d, set to be larger than 28d,

  As a result, dust having a relatively large particle size staying in the portion where the speed of the swirling flow is slowed is pushed back into the rising portion 2b and is accompanied by the rising flow of the exhaust gas. In addition, the amount of air blown out from the air blowing pipe 27 into the rising portion 2b is also set to an amount that only agitates the exhaust gas near the inlet of the extraction duct 10 and introduces it into the extraction duct 10 as it is. Has been. The cyclone classifier 12 is provided at the upper end of the rising portion 10b of the bleed duct 10.

  A flow rate adjusting valve 15 whose opening degree can be adjusted by a motor 15a is interposed at the inlet of the extraction gas in the cyclone classifier 12. On the other hand, a return pipe 16 is connected to the bottom of the cyclone classifier 12 to return the separated dust having a predetermined particle size or more to the kiln bottom 2 again.

Further, on the suction side of the attracting fan 14, a flow rate adjusting valve 17 whose opening degree is adjustable by a motor 17a is interposed.
A dispersion plate (dispersing means) 18 for dispersing the cement raw material in the exhaust gas is provided in the kiln bottom 2.

  The dispersion plate 18 is a plate-like member formed in a shape such as a square, an ellipse, or a polygon. The plate surface is horizontal and directly below the drop 4 a of the raw material chute 4. It is provided so that it can be moved in and out. This dispersion plate 18 is for dispersing the cement raw material falling from the drop opening 4a in the exhaust gas in the kiln bottom 2, and at the base end portion, the dispersion plate 18 is made to appear and drop to form the drop opening 4a. A drive motor (driving means) 19 is provided for adjusting the amount of cement raw material to be dispersed by changing the area located immediately below.

  Furthermore, in this exhaust gas treatment system, a temperature detector (temperature detection means) 20 for detecting the temperature of the extraction gas is provided in the vicinity of the connection portion of the extraction duct 10 at the rising portion 2a of the kiln bottom 2. Is provided. And based on the detection signal from this temperature detector 20, the drive motor 19 is operated and the dispersion | distribution plate 18 is made to appear and retracts, The 1st control which maintains the temperature of extraction gas in the range of 950 degreeC-1150 degreeC. A device 21a is provided.

  Further, a detecting means 22 for detecting the amount of collected fine dust and a chlorine concentration detecting means 23 for detecting the chlorine concentration in the fine dust are installed at the bottom of the bag filter 13. When the detection signal from the chlorine concentration detection means 23 becomes a value less than 5% and when the value exceeds 20%, the motor 15a and / or the motor 17a is operated to adjust the flow rate. By opening and closing the valve 15 and / or the valve 17 and changing the flow rate of the extraction gas, the classification particle size in the cyclone type classifier 12 is adjusted within the range of 12 μm to 30 μm, and finally the chlorine concentration of the fine dust Is provided with a second control device 21b that performs control so as to be in the range of 5 to 20%.

  The second control device 21b performs inverter control of the suction amount by the induction fan 14 together with or in place of the control of the valves 15 and 17, thereby controlling the extraction gas in the cyclone type classifier 12. It can also be configured to adjust the flow rate. The entire control device 21 is configured by the first and second control devices 21a and 21b.

  In addition, the rising portion 2b includes a cement raw material of 600 ° C. to 700 ° C. from the third-stage cyclone and a raw material of cement as low as 50 ° C. to 100 ° C. before being transferred to the preheater 3. An introduction pipe (not shown) for introduction for temperature adjustment in the kiln bottom 2 is connected.

Next, the operation and effect of the exhaust gas treatment system for cement burning equipment having the above-described configuration will be described.
First, in this cement baking equipment, the cement raw material supplied to the first-stage cyclone of the preheater 3 from a supply pipe (not shown) from the cement kiln 1 that rises from below as it sequentially falls to the lower cyclone. It is preheated by the high-temperature exhaust gas and is finally introduced into the kiln bottom 2 of the cement kiln 1 through the raw material chute 4 from the lowermost cyclone 3a.

  And in this cement kiln 1, it is heated to about 1450 ° C. by the combustion exhaust gas from the main burner in the process of being gradually sent to the right side in the figure from the kiln bottom 2 side to the kiln front side. Become. Next, the clinker that has reached before the kiln is dropped into the clinker cooler and sent. At this time, it is cooled to a predetermined temperature by the air supplied into the clinker cooler and finally taken out from the clinker cooler.

At the same time, waste such as sewage sludge and plastic is introduced into the cement kiln 1 from the kiln bottom 2 side or from the kiln front side and used as a part of cement raw material or a part of heating fuel. Is done.
In the above-described cement clinker manufacturing process, 1% or more of the amount of exhaust gas discharged from the cement kiln 1 by the induction fan 14 continuously or intermittently is extracted from the kiln bottom 2 of the cement kiln 1 to the extraction duct 10. It bleeds as bleed gas through.

  At this time, the dispersion plate 18 is positioned below the outlet 4a of the raw material chute 4 to disperse the cement raw material falling from the raw material chute 4 in the exhaust gas, and at the same time, the temperature detector 20 is controlled by the first controller 21a. By operating the drive motor 19 so that the temperature of the bleed gas detected by the above is maintained in the range of 950 ° C. to 1150 ° C., the dispersion plate 18 is advanced and retracted below the outlet 4a of the raw material chute 4 and exhaust gas is discharged. Adjust the amount of cement raw material dispersed in.

  Concurrently with the dispersion of the cement raw material by the dispersion plate 18, the material is conveyed from the introduction pipe connected to the rising portion 2 b to the cement raw material of 600 ° C. to 700 ° C. from the third-stage cyclone or the preheater 3. The temperature of the kiln bottom part 2 can also be adjusted by introducing into the kiln bottom part 2 a cement raw material having a low temperature of 50 ° C. to 100 ° C. before being processed.

  Then, a part of the exhaust gas containing a relatively large amount of dust mainly composed of a cement raw material is extracted from the extraction duct 10 by the induction fan 14. Therefore, the cooling air is continuously sent from the cooling air introduction duct 25 in the circumferential direction of the extraction duct 10. As a result, the extraction gas is cooled to a desired temperature by the cooling air and becomes a swirl flow in the extraction duct 10 by the circumferential flow of the cooling air and the suction from the induction fan 14. It flows to the side.

  In parallel with this, air is blown from the air supply pipes 26 a to 26 d in the rising portion 2 b so that a swirling flow is formed in the vicinity of the opening of the extraction duct 10. Thereby, also in the connection part of the extraction duct 10, by forming the swirling flow of the extraction gas, the dust in the extraction gas is prevented from accumulating on the inner wall of the extraction duct.

  Further, air is supplied to the air blowing pipe 27, and air is blown into the rising portion 2b from the air outlets 28a to 28e. As a result, dust having a relatively large particle size, which tends to stray from the rising portion 2 b into the extraction duct 10, is pushed back toward the rising portion 2 b, and the inflow into the extraction duct 10 is suppressed. As a result, the distribution of the particle size of the dust introduced from the bleed duct 10 is mainly composed of a relatively small one in which the chlorine compound is easily condensed.

  Next, the extraction gas that has risen in the rising portion 10b of the extraction duct 10 is cooled to the melting point (600 ° C. to 700 ° C.) or less of the chlorine compound in the cooler 11, and then sent to the cyclone type classifier 12 to 12 μm to Coarse dust is separated by the classified particle size within the range of 30 μm, and the coarse dust is returned to the kiln bottom 2 again from the return pipe 16.

  On the other hand, with respect to the extraction gas containing fine powder dust that is finer than the classification particle size and thus having a high chlorine concentration, the fine powder dust that is sent to the bag filter 13 and collected is collected and recovered to be removed from the extraction gas. Is done. Thereby, the raise of the chlorine concentration in the system of the cement kiln 1 and the preheater 3 is prevented. Then, the extracted gas from which the fine dust has been removed is sent from the exhaust side of the induction fan 14 to the exhaust gas line and exhausted.

The amount of fine dust collected by the bag filter 13 is detected by the detecting means, and the chlorine concentration detecting means 23 detects the chlorine concentration.
When the chlorine concentration of the fine dust deviates from the range of 5 to 20%, the second control device 21b operates the suction amount of the extraction gas by the induction fan 14 and / or the motors 15a and 17a. To adjust the opening degree of the valves 15 and 17. Thus, the chlorine concentration is controlled to be within the range of 5 to 20% again by increasing or decreasing the flow rate of the extraction gas flowing through the extraction duct 10 and adjusting the classification particle size in the cyclone classifier 12.

  Therefore, by maintaining the extraction temperature within the above-described range of 950 ° C. to 1150 ° C. by the first control device 21a, the chlorine concentration in the fine dust can be stably stabilized by the classification particle size in the cyclone type classifier 12 set in advance. Can be maintained within a range of 5 to 20%, the second control device 21b does not operate.

  As described above, according to the exhaust gas treatment system having the above-described configuration, when a part of the exhaust gas discharged from the rotary kiln 1 is extracted from the rising portion 2b of the kiln bottom 2, the extraction duct from the cooling gas introduction duct 25 is extracted. The cooling gas is blown into 10 to form a swirling flow of the extraction gas in the extraction duct 10 in the axial direction, thereby preventing the accumulation of dust in the extraction duct 10 while cooling the extraction gas. be able to.

  In addition, air supply pipes 26a to 26d for blowing air to the rising portion 2b side in the circumferential direction of the extraction duct 10 are provided at the connection portion between the extraction duct 10 and the rising portion 2b of the exhaust duct. Also, the swirling flow of the extraction gas can be generated in the vicinity of the connecting portion. Therefore, even in the vicinity of the connection portion of the extraction duct 10 where it is difficult to dispose the cooling air introduction duct 25, dust having a relatively large particle size is blown off by the swirling flow, so that the dust adheres to the inner wall of the extraction duct 10 and is hardened. Can be prevented.

  Further, since an air blowing pipe 27 for blowing air toward the rising portion 2b side is provided on the side wall of the rising portion 2b and below the connection portion of the extraction duct 10, the air is introduced into the extraction duct 10 from the rising portion 2b side. The dust having a relatively large particle size to be lost is pushed back to the rising portion 2b side to suppress the inflow into the extraction duct 10 and the distribution of the particle size of the dust introduced from the extraction duct 10 can be reduced. It becomes possible to make the main component a relatively small substance that easily condenses chlorine compounds.

  As a result, it is possible to reliably prevent dust accompanying the extraction gas from accumulating and solidifying in the extraction duct 10 by introducing a minimum amount of gas without increasing the heat load in the cement manufacturing facility.

  Further, by collecting and removing fine dust dust having a high chlorine concentration contained in the extraction gas extracted from the kiln bottom 2 by the bag filter 13, the chlorine concentration in the system including the cement kiln 1 and the preheater 3 is removed. Can be prevented from rising.

  Moreover, the first control device moves the dispersion plate 18 based on the temperature of the extracted gas, adjusts the amount of cement raw material dispersed in the exhaust gas of the kiln bottom 2 where the extracted gas is extracted, and adjusts the temperature of the extracted gas. Is maintained in the range of 950 ° C. to 1150 ° C., the chlorine concentration of the fine dust that has been finally collected can be easily reduced to 20% or less.

  For this reason, while being excellent in the handling property of the said fine dust collected in the bag filter 13, there is no possibility that the chlorine component contained in the said fine dust during conveyance may cause troubles, such as obstruction | occlusion and clogging, and stable. Operations can be performed.

  Moreover, since it is only necessary to adjust the classification particle size of the coarse dust returned from the bleed gas to the kiln bottom part 2 within a range of 12 μm to 30 μm, a general-purpose cyclone classifier or the like can be used, which may increase the equipment cost. Nor.

In the above embodiment, only the case where the extraction gas is extracted from the kiln bottom 2 of the cement kiln 1 has been described. However, the present invention is not limited to this, and the extraction gas is extracted from the exhaust pipe 5 in the preheater 3. May be.
In addition to the cyclone classifier 12 and the bag filter 13 described above, various types of solid-gas separation means and dust trapping means can be used.

  Further, as a driving means for the dispersion plate 18 and the valves 15 and 17, a driving source such as a hydraulic or pneumatic cylinder can be used in addition to the driving motor 19 and the motors 15a and 17a.

It is a schematic block diagram which shows one Embodiment of the waste gas processing system of the cement baking equipment which concerns on this invention. It is a longitudinal cross-sectional view which expands and shows the connection part of the standup | rising part and bleed duct of FIG. It is a side view which shows typically the blowing flow volume of the air of the air supply pipe | tube of FIG. It is a side view which shows typically the blowing flow volume of the air from the blower outlet of FIG. It is a graph which shows the relationship between the dust concentration in the extraction gas in a cement baking equipment, and the chlorine concentration in the collected fine dust. It is a graph which shows the relationship between the temperature of the extraction gas in a cement baking equipment, and the dust density | concentration in extraction gas. It is a graph which shows the relationship between the temperature of the extraction gas obtained from the graph shown in FIG. 5 and FIG. 6, and the chlorine concentration in the collected fine dust.

Explanation of symbols

1 Cement kiln 2 Kiln bottom 2b Standing up (exhaust duct)
3 Preheater 3a Bottom cyclone 4 Raw material chute 4a Drop port 10 Extraction duct 11 Cooling means 12 Cyclone classifier (solid gas separation means)
13 Bag filter (Dust capture means)
14 Induction fan 16 Return pipe 18 Dispersion plate (dispersion means)
19 Drive motor (drive means)
20 Temperature detector (temperature detection means)
21a 1st control apparatus 21b 2nd control apparatus 25 Cooling air (gas) introduction duct 26a-26d Air (gas) supply pipe 27 Air blowing pipe 28a-28e Outlet

Claims (6)

Part of the exhaust gas containing dust discharged from the cement kiln that fires the cement raw material and sent to the preheater that preheats the cement raw material is extracted as the extraction gas, and the chlorine compounds contained in the extraction gas are removed. An exhaust gas treatment system for cement firing equipment for
An extraction duct connected to an exhaust duct at the lowermost part of the preheater or the kiln bottom of the cement kiln and for extracting the extracted gas, and cooling for cooling the extracted gas extracted from the extracted duct below the melting point of the chlorine compound Means, a solid-gas separation means for separating the dust having a predetermined particle size or more from the extracted gas cooled by the cooling means, and the dust having a predetermined particle size or more separated from the extracted gas from which the solid-gas separation means has been separated. A dust trapping means for collecting and removing fine dust having a predetermined particle size or less, and an induction fan provided on the downstream side of the dust trapping means for sucking the extracted gas;
The extraction duct is formed by a single tube, and the cooling means opens in the extraction duct and blows cooling gas in the circumferential direction of the extraction duct, thereby cooling the extraction gas in the axial direction. A cooling gas introduction duct for forming a swirling flow of the extraction gas, and an air supply means for supplying the cooling gas to the cooling gas introduction duct;
A cement firing facility characterized in that a connecting means between the extraction duct and the exhaust duct is provided with stirring means for the extraction gas that blows gas toward the exhaust duct in the circumferential direction of the extraction duct. Exhaust gas treatment system.   The agitating means is arranged at intervals along the circumferential direction of the extraction duct, and a plurality of the agitating means are jetted to the exhaust duct side in the same circumferential direction as the swirling flow of the extraction gas. The exhaust gas treatment system for a cement firing facility according to claim 1, comprising: a gas supply pipe.   3. The cement according to claim 1, wherein second agitation means for blowing gas toward the exhaust duct side is provided on a side wall of the exhaust duct and below a connection portion of the extraction duct. Exhaust gas treatment system for firing equipment. The pre-heater is provided with a flow rate adjusting device for the extracted gas on the inlet side of the solid gas separating means, and a chlorine concentration detecting device for detecting the chlorine concentration of the fine dust collected by the dust capturing means. Dispersing means for dispersing the cement raw material in the exhaust gas is provided in the lowermost part of the kiln bottom of the cement kiln and in the vicinity of the connection part of the extraction duct,
A driving means for adjusting the amount of the cement raw material to be dispersed by the dispersing means; a temperature detecting means for detecting the temperature of the extracted gas; and the driving means is controlled based on the temperature detected by the temperature detecting means. A first control device for maintaining the temperature of the extraction gas in a range of 950 ° C to 1150 ° C;
Based on the detection signal of the chlorine concentration detection means, even if the chlorine concentration of the fine dust collected by the bag filter deviates from the range of 5 to 20% by the control by the first control device, The predetermined amount in the solid gas separation means is controlled by controlling the amount of the extraction gas sucked by the attraction fan and / or the flow rate adjustment device of the extraction gas so that the chlorine concentration of the fine dust is in the range of 5 to 20%. The exhaust gas treatment system for a cement firing facility according to any one of claims 1 to 3, further comprising a second control device that adjusts the particle size within a range of 12 µm to 30 µm.   The exhaust gas treatment system for a cement firing facility according to claim 4, wherein the solid-gas separation means is a cyclone classifier, and the dust trapping means is a bag filter.   The dispersing means is provided below the outlet of a raw material chute for charging the cement raw material from the preheater into the kiln bottom, and is provided so as to be able to protrude and fall directly below the outlet, and the cement raw material falling from the outlet 6. The exhaust gas treatment system for a cement firing facility according to claim 4, wherein the exhaust gas is a dispersion plate that disperses the gas in the exhaust gas.

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