WO2012053058A1 - Cement clinker manufacturing method - Google Patents
Cement clinker manufacturing method Download PDFInfo
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- WO2012053058A1 WO2012053058A1 PCT/JP2010/068376 JP2010068376W WO2012053058A1 WO 2012053058 A1 WO2012053058 A1 WO 2012053058A1 JP 2010068376 W JP2010068376 W JP 2010068376W WO 2012053058 A1 WO2012053058 A1 WO 2012053058A1
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- slaked lime
- cement clinker
- exhaust gas
- raw material
- cement
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/36—Manufacture of hydraulic cements in general
- C04B7/364—Avoiding environmental pollution during cement-manufacturing
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/36—Manufacture of hydraulic cements in general
- C04B7/38—Preparing or treating the raw materials individually or as batches, e.g. mixing with fuel
- C04B7/42—Active ingredients added before, or during, the burning process
- C04B7/421—Inorganic materials
- C04B7/424—Oxides, Hydroxides
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- the present invention relates to a method for manufacturing a cement clinker, and more particularly to a method for manufacturing a cement clinker in a cement clinker manufacturing facility such as a cement kiln facility with SP (suspension preheater) or a cement kiln facility with NSP (new suspension preheater).
- a cement kiln facility with SP suspension preheater
- NSP new suspension preheater
- incinerators that treat municipal waste and other general waste and industrial waste associated with business activities tend to generate dioxins, which are harmful substances, from exhaust gas.
- Dioxins are repeatedly decomposed and re-synthesized at 150 to 500 ° C.
- Dioxin suppression measures have been shown to sufficiently burn at a high temperature of 800 ° C or higher, not to make the incinerator into a reducing atmosphere, and to increase the exhaust gas cooling rate at 500 ° C or lower. ing.
- the kiln exhaust gas is decarbonated by a counter current from the bottom of the kiln kiln at about 1,000 ° C., decarboxylated by countercurrent, reaches about 400 ° C. in the upper stage of the cyclone, and water is supplied by a boiler. Because it is rapidly cooled by generating evaporation and heated steam, it is cooled to about 250 ° C at the boiler outlet, so the cooling rate from about 400 ° C to about 250 ° C is high. Compared with the incinerator to process, generation
- CO 2 emitted from raw fuel consumption and power consumption in a cement plant is formed from CO 2 from thermal decomposition of limestone in raw materials, combustion of coal in fuel, power consumption due to energy. Since CO 2 is a global warming gas, it is an important technique to reduce energy from consumption of these raw fuels and power consumption.
- a cement clinker manufacturing facility in a cement plant performs exhaust heat power generation by exchanging heat between a preheater 110 having a plurality of cyclones 103a, 103b, 103c, and 103d and a kiln exhaust gas from the preheater 110, as shown in FIG.
- the main part is a boiler 106 for waste heat power generation and a kiln 101 for firing the blended raw material into a cement clinker.
- the mixed raw material charged into the upper cyclone 103a forms counterflow with the exhaust gas from the kiln 101 by the preheater 110 at the upper stage of about 400 ° C., is heat-exchanged and decarboxylated, and enters the kiln 101 at about 1,000 ° C. Introduced and fired into cement clinker.
- the kiln exhaust gas is about 1,000 ° C. in the kiln kiln bottom 112, and while passing through the cyclones 103a to 103d, the mixed raw material is cooled while decarbonating by countercurrent, and about 400 in the uppermost cyclone 103a.
- the organic chlorine compounds of dioxins are repeatedly decomposed and re-synthesized in the exhaust gas, and are contained in the kiln exhaust gas. ing.
- Patent Document 1 In Japanese Patent Application Laid-Open No. 2004-244308 (Patent Document 1), (A) exhaust gas from a cement manufacturing apparatus is treated using a dust collecting means to collect dust containing an organic chlorine compound, while the dust collecting means And a step of discharging the exhaust gas after the treatment by (B), and (B) introducing at least a part of the collected dust into a place of 800 ° C. or higher in the cement manufacturing apparatus. A method for treating exhaust gas from a manufacturing apparatus is described.
- Patent Document 2 discloses a method for reducing an organochlorine compound in a cement manufacturing apparatus, in the middle of supplying exhaust gas from the upper part of a preheater to a raw material pulverization process section. A method is described in which a single exhaust gas branch pipe is used for separation, and this is put into the lower stage of the preheater that becomes 800 ° C. or higher during normal operation of the cement production facility. Thus, it is said that if organic chlorine compounds such as dioxins and PCBs contained in the exhaust gas are thermally decomposed, the amount of organic chlorine compounds discharged from the cement production facility can be reduced as compared with the prior art.
- Patent Document 3 discloses (A) a step of flowing exhaust gas generated in the cement manufacturing process into the preheater, and (B) heating provided in the preheater. And a step of enlarging a region of 800 ° C. or higher in the preheater by means. A method for treating an exhaust gas of a cement manufacturing apparatus is described.
- Patent Document 4 As a method for producing cement, exhaust gas discharged from the upper part of a suspension preheater of a cement firing facility is used for drying cement raw material in the raw material grinding step. In the cement manufacturing process, after the exhaust gas discharged is separated into purified exhaust gas and dust collection dust with a dust collector, the purified exhaust gas is released into the atmosphere and the dust collection dust is sent to the upper part of the suspension preheater as part of the cement raw material.
- step (A) A part of the dust collection dust is discharged from the circulation path of the cement clinker manufacturing process, and (B) the dust collection dust discharged by the process (A) is introduced into the heating device,
- step (C) in step (C), in step (B), in step (C), in step (C) Rapidly cooled collected dust is returned to the circulation path of the cement clinker manufacturing process, describes the preparation method of the cement, characterized in that a step of entering fed again suspension preheater upper as a cement raw material.
- Patent Document 5 describes (A) a process of generating exhaust gas containing hydrogen chloride in a cement manufacturing process using a cement raw material containing chlorine, and (B) process (A). At least one calcium compound selected from CaO and Ca (OH) 2 is introduced into the exhaust gas containing hydrogen chloride generated in the above at a point upstream of the exhaust gas of the dryer or pulverizer, and the calcium compound and the exhaust gas And a process for producing calcium chloride, which is a neutralized product of hydrogen chloride therein, and a method for treating exhaust gas from a cement production apparatus. In this method, the amount of hydrogen chloride in the exhaust gas is reduced by neutralizing hydrogen chloride into calcium chloride, which is a solid component.
- the input amount of CaO or Ca (OH) 2 per equivalent of hydrogen chloride in the exhaust gas should be 1.0 to 10 equivalents.
- Patent Documents 1 to 4 all require significant and expensive process changes, and the effect of reducing dioxin organochlorine compounds is uncertain. According to the method described in Patent Document 5, such a large-scale process change is not required, and the calcium compound reduces the amount of hydrogen chloride in the exhaust gas, thereby generating residual organic pollutants such as dioxins. Although it is said to be suppressed, the reduction effect of dioxin organochlorine compounds is not clear, and there is still room for improvement.
- an object of the present invention is to provide a method for producing a cement clinker capable of effectively suppressing the concentration of dioxins (DXN S ) in exhaust gas without significantly changing the process. .
- the present inventor has added dioxin in exhaust gas from a cement clinker manufacturing facility when slaked lime having a predetermined terminal sedimentation rate is added to a cyclone through which exhaust gas in a predetermined temperature range passes.
- concentration of the class (DXN S ) was significantly reduced.
- the present invention provides a cement clinker manufacturing method in a cement clinker manufacturing facility including a pre-heater having a plurality of cyclones and a rotary kiln, wherein slaked lime having a terminal sedimentation rate of 0.5 to 10 cm / sec is discharged from exhaust gas.
- This is a method including a step of putting in a cyclone having an exhaust gas temperature of 350 to 500 ° C. at the outlet.
- the slaked lime is added so that the amount of slaked lime is 20 to 200 kg per 1 ton of cement clinker.
- the slaked lime is charged into the uppermost cyclone.
- the slaked lime is supplied to a raw material crushing and drying machine after being mixed with a cement preparation raw material or in parallel with the preparation raw material. It is fed into the uppermost cyclone through the supply line.
- the ratio of the terminal sedimentation rate of the slaked lime to the terminal sedimentation rate of the cement clinker preparation raw material is 0.5 to 1.5.
- the slaked lime is slaked lime that is by-produced when acetylene is generated from calcium carbide.
- the concentration of dioxins (DXN S ) in exhaust gas can be effectively suppressed without significant process changes.
- concentration of the dioxins in the waste gas of a cement clinker manufacturing facility can be suppressed to 20 ng / m ⁇ 3 > N or less, for example.
- FIG. 1 is a system diagram of a cement clinker manufacturing facility according to an embodiment of the present invention.
- the cement clinker manufacturing facility is a cement kiln facility with an NSP (New Suspension Preheater), and as shown in FIG. 1, a rotary kiln 101, a preheater 110, a waste heat power generation boiler 106, a kiln IDF 105, a raw material pulverization It comprises a dryer 107, a stabilizer 108, and an electric dust collector 109.
- NSP New Suspension Preheater
- the pre-heater 110 connects four cyclones (first-stage cyclone 103a, second-stage cyclone 103b, third-stage cyclone 103c, fourth-stage cyclone 103d), calcining furnace 102, and these arranged in the vertical direction.
- the cement clinker blending raw material generally contains limestone, clay, silica stone, and iron base, and in addition, wastes such as main ash generated from incineration of municipal waste and foundry sand may be appropriately added.
- the raw material for cement clinker preparation is pulverized, mixed, and dried by the raw material pulverization dryer 107.
- the cement clinker blended raw material is fed into the preheater 110 from the first-stage cyclone 103a through the blended raw material supply line 104, the high temperature discharged from the rotary kiln 101 in order along the solid line in FIG.
- the mixed raw material is preheated while exchanging heat with the exhaust gas.
- the calcining furnace 102 the preheated cement clinker preparation material is calcined.
- the number of cyclones can be increased or decreased as appropriate.
- the cement clinker blended raw material charged into the rotary kiln 101 at about 1000 ° C. gradually moves toward the outlet through the rotary kiln 101 and the temperature rises to about 1400-1500 ° C.
- the blended raw material is fired during this time to produce a cement clinker.
- exhaust gas of about 1000 ° C. is discharged from the kiln kiln bottom 112.
- Dioxins (DXN S ) are contained in the exhaust gas.
- the exhaust gas proceeds in order along the dotted line in FIG. 1 through the rising duct 111, the calcining furnace 102, and the cyclones 103 a to 103 d extending right above the kiln kiln bottom 112, and then toward the kiln IDF fan 105. During this time, the exhaust gas is cooled by heat exchange.
- the exhaust gas outlet of the lowermost fourth-stage cyclone 103d is 820 to 870 ° C.
- the exhaust gas outlet of the third-stage cyclone 103c is 730 to 790 ° C. It becomes 590 to 650 ° C. at the exhaust gas outlet of the first stage cyclone 103b and 350 to 500 ° C.
- the exhaust gas outlet of the uppermost first cyclone 103a is further cooled by the latent heat of evaporation when water is evaporated by the exhaust heat power boiler 106, It is cooled to about 340 ° C. at the outlet of the boiler 106. Further, the air is sucked into the kiln IDF 105, the amount of heat for drying is consumed by the raw material crushing and drying machine 107, the temperature is adjusted and humidified by the stabilizer 108, the dust is collected by the electric dust collector 109, and then exhausted from the chimney.
- slaked lime having a terminal sedimentation rate of 0.5 to 10 cm / sec is used in a cyclone having an exhaust gas temperature of 350 to 500 ° C. at the exhaust gas outlet.
- the inlet temperature of the first-stage cyclone 103a is about 590 to 650 ° C., and the outlet temperature is 350 to 500 ° C. Therefore, the exhaust gas passing through the first stage cyclone 103a is in a temperature range where dioxins are easily re-synthesized.
- slaked lime undergoes a dehydration reaction (endothermic reaction) by the following formula: Ca (OH) 2 ⁇ CaO + H 2 O at a temperature of 400 to 500 ° C., and the generated water loses its latent heat by evaporation, thus lowering the temperature. Therefore, when slaked lime is added to the first-stage cyclone 103a in which the exhaust gas outlet temperature is in the above range, the slaked lime is dehydrated in the cyclone so that a rapid cooling effect is generated and the resynthesis of dioxins can be suppressed. .
- the exhaust gas temperature at the exhaust gas outlet of the cyclone into which the slaked lime is charged is preferably for the reason of ensuring the durability of the iron of the plant constituting the cyclone and the boilers after the cyclone, the kiln IDF, the stabilizer, the raw material crushing dryer, the electric dust collector, It is 440 degrees C or less.
- the cyclone at the lower stage of the kiln or preheater is protected by a refractory, but the material constituting the plant after the first stage cyclone is often iron, and the yield point of iron is 440 ° C. .
- the lower limit of the exhaust gas temperature consideration is given to the point of suppressing the generation of dioxins and the point of performing high-pressure steam recovery in the boiler. That is, as described above, it is better to increase the cooling rate at 400 to 250 ° C. in order to suppress the generation of dioxins. If exhaust gas is sent into the boiler at a very low temperature, the generation of dioxins due to rapid cooling in the boiler is suppressed. The effect may not be obtained sufficiently. Further, it is known that the high-pressure steam recovery of the boiler can generate the power generation energy in the turbine as the temperature rises. Furthermore, as described above, the dehydration reaction of slaked lime is likely to proceed at 400 to 500 ° C. Accordingly, since it is not appropriate to set the exhaust gas outlet temperature of the cyclone to a temperature that is excessively lower than 400 ° C., the temperature is preferably 370 ° C. or higher, and more preferably 390 ° C. or higher.
- the slaked lime needs to have a terminal sedimentation rate of 0.5 cm / sec or more, and preferably 1 cm / sec or more. More preferably, it is 2 cm / sec or more, and still more preferably 4 cm / sec or more.
- the terminal sedimentation rate of slaked lime is preferably 10 cm / sec or less, and more preferably 7 cm / sec or less.
- the slaked lime charging point is not particularly limited as long as it can be charged into the cyclone.
- a dedicated supply line can be provided, and the slaked lime charging point is charged into the mixed raw material supply line 104 between the raw material crushing dryer 107 and the first-stage cyclone 103a.
- the raw material crushing and drying machine 107 can be charged.
- the raw material analyzer that controls the mixing of raw materials to control the composition of the clinker performs the combined batch analysis of the mixed raw materials and controls the raw material feeder according to the result. Forms the lime component of the clinker. Therefore, it is included in the blended raw material value, analyzed, and the supply amount as the lime raw material is controlled so that the fluctuation of the clinker composition is controlled less. It is preferable to be fed into the raw material crusher / dryer 107 after being mixed with the raw material or in parallel with the prepared raw material.
- the amount of slaked lime input will be described. As the amount of slaked lime having the predetermined terminal sedimentation rate decreases, the effect of reducing dioxins decreases.On the other hand, when the amount of slaked lime input increases too much, a large pressure loss occurs in the preheater. Driving may be difficult. Therefore, it is preferable to add the slaked lime to the blended raw material of the cement clinker so that the slaked lime is 20 to 200 kg (20 to 200 kg / tcl) per 1 ton of the cement clinker. More preferably, the slaked lime is added to the cement clinker preparation material so as to be 100 kg / tcl).
- slaked lime having a terminal sedimentation rate of 0.5 to 10 cm / sec it is convenient to use by-product slaked lime generated in the process of producing acetylene gas by the carbide method, which is also useful for effective utilization of resources.
- a chemical reaction in which acetylene is generated from calcium carbide can be represented by the following formula: CaC 2 + 2H 2 O ⁇ C 2 H 2 + Ca (OH) 2 .
- the terminal sedimentation rate of slaked lime can be adjusted by methods such as sieving, granulation and pulverization.
- the slaked lime does not form a sufficient swirl flow in the cyclone, and short pass and settle.
- the ratio of the terminal sedimentation rate of the added slaked lime to the terminal sedimentation rate of the cement clinker preparation raw material is preferably 0.5 to 1.5, and more preferably 0.7 to 1.3.
- the cement clinker blended raw material after passing through the raw material crushing and drying machine 107 is generally 0.2 to 15 cm / sec, typically 0.5 to 13 cm / sec, more typically 1 to 10 cm / sec. Having a terminal sedimentation rate of
- Example 1 Production of by-product slaked lime> Water was added to calcium carbide having a particle size of 4.0 mm or less to generate acetylene gas, and slaked lime with a terminal sedimentation rate of 0.5 to 15 cm / sec was by-produced. The water content of by-product slaked lime was 7 to 10% by mass, and the terminal sedimentation rate was 5 cm / sec. Table 1 shows the quality of the calcium carbide and the specifications of the acetylene generator, and Table 2 shows the amount of components of the obtained byproduct slaked lime. The particle size of calcium carbide was measured using a JISZ8801 metallic steel sieve.
- the terminal sedimentation rate was measured by the Andreazen pipette sedimentation method specified in JIS Z8821.
- the component amount was measured according to JIS R5202.
- the moisture content was measured with an infrared moisture meter (Model “FD-800” manufactured by Kett Science Laboratory).
- Example 2 Effect of terminal sedimentation rate of by-product slaked lime on dioxin concentration in exhaust gas> A cement blending raw material having the component composition shown in Table 3 and having a terminal sedimentation rate of 4 cm / sec was prepared.
- slaked lime with various terminal sedimentation rates produced by appropriately pulverizing the byproduct slaked lime with a terminal sedimentation rate of 5 cm / sec produced in Example 1 and commercially available slaked lime “Hishikar” (Ryoko Lime Industry) were prepared (Table). 4).
- Slaked lime “Hishikar” (Ryoko Lime Industry) used in the comparative example is used as a dioxin-suppressing adsorbent for general incinerators.
- the terminal sedimentation rate was measured by the Andreazen pipette sedimentation method specified in JIS Z8821.
- each of the slaked lime was supplied to the raw material crushing and drying machine 107 in parallel with the cement blending raw material, so that each unit of 50 kg / tcl was charged into the uppermost cyclone 103a.
- the inner diameter of each cyclone was 3 m.
- the concentration of DXN S is measured in accordance with “JIS K 0311 Analysis of Dioxins in Exhaust Gas”, and the concentration of organochlorine compounds in dioxins (PCDDs, PCDFs and DL-PCB) per 1 m 3 N of kiln exhaust gas (ng) / M 3 N).
- the first stage cyclone 103a exit slaked lime collection efficiency is the sizing method that matches the dust in the gas at the exhaust gas outlet of the first stage cyclone 103a to the sizing characteristics shown in JIS Z 8814 "Low volume air sampler", and JIS Amount of slaked lime collected by K 0901 “Shape, size and performance test method of filter medium for collecting dust sample in gas” and added to first stage cyclone 103a after quantifying slaked lime in dust by X-ray diffraction It was calculated by dividing by.
- the average value of the pressure difference at each stage of the cyclone was obtained by calculating the cyclone outlet pressure-the cyclone inlet pressure for each of the cyclones 103a to 103d, and taking the average value as a measured value.
- the IDF power unit is calculated based on the amount of heavy oil required to produce 1 ton of clinker. Expressed as the difference to 1.
- By-product slaked lime (No. 1) has a terminal sedimentation rate of 5 cm / sec and is close to the terminal sedimentation rate of 4 cm / sec of the blended raw material, so that the average pressure difference at each stage of the cyclone is as small as -1.0 kPa, and the kiln
- the IDF outlet pressure was as low as -7 kPa and was within the normal operating range.
- the slaked lime “Hishikar” produced by pulverization method No. 4 has a terminal sedimentation rate of 0.1 cm / sec, which is significantly smaller than the terminal sedimentation rate of 4 cm / sec of the prepared raw material. For this reason, the average pressure difference value of each stage of the cyclone was as large as -1.25 kPa. Also, kiln IDF outlet pressure is as large as -8KPa, outside the normal operating range, the first stage collection efficiency of input slaked lime in the cyclone outlet as small as 5%, DXN S concentration in EP outlet 70 ng / m 3 N was high.
- the cause of the terminal sedimentation rate of slaked lime affecting the concentration of dioxins in the exhaust gas will be discussed below. From the exhaust gas inlet temperature and outlet temperature of the first stage cyclone, it can be understood that the temperature of 400 to 500 ° C. at which the dehydration reaction from slaked lime Ca (OH) 2 to quick lime CaO occurs is performed inside the first stage cyclone. . At this time, no. In No. 1, since the terminal sedimentation rate of the slaked lime was appropriate, the slaked lime particles swirled sufficiently in the first-stage cyclone, and sufficient heat exchange retention time was ensured in the cyclone, so that a high cooling effect was obtained. In addition, it is thought that the dioxin suppression effect was high.
- Example 3 Effect of input amount of by-product slaked lime on dioxin concentration in exhaust gas> The effect on the dioxin concentration in the exhaust gas when the input amount of the by-product slaked lime having a terminal sedimentation rate of 5 cm / sec obtained in Example 1 was changed was examined. Similarly to Example 2, in the cement clinker manufacturing facility having the configuration shown in FIG. 1, by-product slaked lime was charged into the upper cyclone 103a from the raw material crushing dryer 107 in various basic units, and the cement clinker manufacturing facility was operated.
- Concentration measurement of DXN S is carried out in compliance with the "analysis of dioxins JIS K 0311 in the exhaust gas" was evaluated as the concentration of organochlorine compounds dioxins per kiln exhaust 1m 3 N (ng / m 3 N).
- HCl in the exhaust gas was determined by “JIS K 0107 Method for analyzing hydrogen chloride in exhaust gas”.
- Byproduct hydrated lime DXN amount added by increasing the 0,2,5,10,20,50,200,300kg / tcl S is reduced, in particular, if the byproduct slaked lime is 20 kg / tcl more intensity It can be seen that the concentration of dioxins organochlorine compounds in the exhaust gas is reduced to 20 ng / m 3 N or less.
- the by-product slaked lime is a basic unit of 200 kg / tcl
- the basic unit of by-product slaked lime was excessive, the outlet temperature of the first-stage cyclone tended to increase. Since the yield point of the iron material constituting the first-stage cyclone is in the region of about 440 ° C., the basic unit of by-product slaked lime is appropriately 200 kg / tcl or less.
- Patent Document 5 CaO or Ca (OH) 2 is introduced into exhaust gas containing hydrogen chloride, the amount of hydrogen chloride in the exhaust gas is reduced, and the neutralized product is chloride. It is said that calcium is produced and as a result, the production of persistent organic pollutants such as dioxins is suppressed.
- the amount of slaked lime added increases, the amount of hydrogen chloride in the exhaust gas is not reduced, and the amount of hydrogen chloride in the exhaust gas does not depend on the amount of slaked lime added.
- Patent Document 5 Japanese Patent Application Laid-Open No. 2007-90261
- Rotary kiln 102
- Calciner 103a First stage cyclone 103b Second stage cyclone 103c
- Third stage cyclone 103d
- Fourth stage cyclone 104
- Compound raw material supply line 105 Kiln IDF 106
- Boiler for waste heat power generation 107
- Raw material crushing and drying machine 108
- Stabilizer 109
- Electric dust collector 110
- Preheater 111
Abstract
Description
一般に、セメントプラントにおけるセメントクリンカー製造設備は、図1に示す通り、複数のサイクロン103a、103b、103c、103dを有するプレヒーター110、プレヒーター110からのキルン排ガスを熱交換して排熱発電を行う為の排熱発電用ボイラー106及び調合原料をセメントクリンカーに焼成する為のキルン101を主要部として構成される。上段のサイクロン103aに投入された調合原料は、上段約400℃のプレヒーター110でキルン101からの排ガスと向流を形成し、熱交換、脱炭酸され、約1,000℃で、キルン101へ導入され、セメントクリンカーに焼成される。キルン排ガスはキルン窯尻112で約1,000℃であり、サイクロン103a~dを通過する間に、調合原料を、向流により、脱炭酸させながら、冷却され、最上段のサイクロン103aで約400℃となり、排熱発電ボイラー106で水を蒸発、加熱蒸気を発生させる事により冷却され、ボイラー106出口で約340℃迄、冷却され、キルンIDF(Induced Draft Fan)105に吸引され、原料粉砕乾燥機107で乾燥用熱量を消費され、スタビライザー108で調温加湿され、電気集塵機109で集塵された後、煙突から排気される。 Hereinafter, the past technology will be described more clearly using actual examples.
Generally, a cement clinker manufacturing facility in a cement plant performs exhaust heat power generation by exchanging heat between a
消石灰の終末沈降速度の調整は、篩い分け、造粒及び粉砕などの方法により行うことができる。 As slaked lime having a terminal sedimentation rate of 0.5 to 10 cm / sec, it is convenient to use by-product slaked lime generated in the process of producing acetylene gas by the carbide method, which is also useful for effective utilization of resources. A chemical reaction in which acetylene is generated from calcium carbide can be represented by the following formula: CaC 2 + 2H 2 O → C 2 H 2 + Ca (OH) 2 .
The terminal sedimentation rate of slaked lime can be adjusted by methods such as sieving, granulation and pulverization.
粒度4.0mm以下のカルシウムカーバイドに、水を添加し、アセチレンガスを発生させ、終末沈降速度が0.5~15cm/secである消石灰を副生した。副産消石灰の水分量は7~10質量%であり、終末沈降速度は5cm/secであった。カルシウムカーバイドの品位及びアセチレン発生機の仕様を表1に、得られた副産消石灰の成分量を表2に示す。カルシウムカーバイドの粒度はJISZ8801金属性鋼篩を用いて測定した。終末沈降速度はJIS Z 8821に規定されるアンドレアゼンピペット沈降法により測定した。成分量はJIS R5202に準拠して測定した。水分量は赤外線水分計(ケット科学研究所製型式「FD-800」)にて測定した。 <Example 1: Production of by-product slaked lime>
Water was added to calcium carbide having a particle size of 4.0 mm or less to generate acetylene gas, and slaked lime with a terminal sedimentation rate of 0.5 to 15 cm / sec was by-produced. The water content of by-product slaked lime was 7 to 10% by mass, and the terminal sedimentation rate was 5 cm / sec. Table 1 shows the quality of the calcium carbide and the specifications of the acetylene generator, and Table 2 shows the amount of components of the obtained byproduct slaked lime. The particle size of calcium carbide was measured using a JISZ8801 metallic steel sieve. The terminal sedimentation rate was measured by the Andreazen pipette sedimentation method specified in JIS Z8821. The component amount was measured according to JIS R5202. The moisture content was measured with an infrared moisture meter (Model “FD-800” manufactured by Kett Science Laboratory).
表3に記載の成分組成を有し、終末沈降速度が4cm/secであるセメント調合原料を用意した。また、例1で製造した終末沈降速度5cm/secの副産消石灰を適宜粉砕して製造した種々の終末沈降速度の消石灰、及び市販の消石灰「ヒシカール」(菱光石灰工業)を用意した(表4参照)。比較例で用いた消石灰「ヒシカール」(菱光石灰工業)は、一般焼却炉のダイオキシン抑制吸着剤として使用されているものである。終末沈降速度はJIS Z 8821に規定されるアンドレアゼンピペット沈降法により測定した。 <Example 2: Effect of terminal sedimentation rate of by-product slaked lime on dioxin concentration in exhaust gas>
A cement blending raw material having the component composition shown in Table 3 and having a terminal sedimentation rate of 4 cm / sec was prepared. In addition, slaked lime with various terminal sedimentation rates produced by appropriately pulverizing the byproduct slaked lime with a terminal sedimentation rate of 5 cm / sec produced in Example 1 and commercially available slaked lime “Hishikar” (Ryoko Lime Industry) were prepared (Table). 4). Slaked lime “Hishikar” (Ryoko Lime Industry) used in the comparative example is used as a dioxin-suppressing adsorbent for general incinerators. The terminal sedimentation rate was measured by the Andreazen pipette sedimentation method specified in JIS Z8821.
サイクロン各段の圧力差平均値は、サイクロン103a~dそれぞれについて、サイクロン出口圧力-サイクロン入口圧力を求め、その平均値を測定値とした。
キルンIDFファン効率[%]は次式に従って求めた。
キルンIDFファン効率[%]=風量[m3/min]/60[sec/min]×圧力[MPa]/軸動力[kW]×100
IDF動力原単位は、1トンのクリンカーを製造するのに必要な重油量に換算して、No.1に対する差として表示した。 The
The average value of the pressure difference at each stage of the cyclone was obtained by calculating the cyclone outlet pressure-the cyclone inlet pressure for each of the
The kiln IDF fan efficiency [%] was determined according to the following formula.
Kiln IDF fan efficiency [%] = air volume [m 3 / min] / 60 [sec / min] × pressure [MPa] / shaft power [kW] × 100
The IDF power unit is calculated based on the amount of heavy oil required to produce 1 ton of clinker. Expressed as the difference to 1.
この際、No.1では、投入した消石灰の終末沈降速度が適切であったため、消石灰粒子が1段目サイクロン内で充分旋回し、サイクロン内での十分な熱交換保持時間が確保されて高い冷却効果が得られたために、ダイオキシン類の抑制効果が高かったと考えられる。また、消石灰が高い捕集効率で回収されたために、キルンIDFに流入する消石灰の量が少なくなり、大きなIDF風量が得られ、IDF効率も高かったと考えられる。
これに対して、消石灰の終末沈降速度を小さくしていくと、消石灰粒子の1段目サイクロン内における保持時間が短くなり、冷却効果が低減してダイオキシン類の抑制効果が徐々に低下したと考えられる。また、消石灰の捕集効率が低下し、圧力損失やIDF効率が徐々に低下していったと考えられる。No.4ではその低下度合いが甚だしく、ダイオキシン類の濃度を目安である20ng/m3N以下にすることはできなかったと考えられる。 The cause of the terminal sedimentation rate of slaked lime affecting the concentration of dioxins in the exhaust gas will be discussed below. From the exhaust gas inlet temperature and outlet temperature of the first stage cyclone, it can be understood that the temperature of 400 to 500 ° C. at which the dehydration reaction from slaked lime Ca (OH) 2 to quick lime CaO occurs is performed inside the first stage cyclone. .
At this time, no. In No. 1, since the terminal sedimentation rate of the slaked lime was appropriate, the slaked lime particles swirled sufficiently in the first-stage cyclone, and sufficient heat exchange retention time was ensured in the cyclone, so that a high cooling effect was obtained. In addition, it is thought that the dioxin suppression effect was high. Moreover, since slaked lime was collected with high collection efficiency, the amount of slaked lime flowing into the kiln IDF was reduced, a large IDF air volume was obtained, and the IDF efficiency was also considered high.
On the other hand, when the terminal sedimentation rate of slaked lime is reduced, the retention time of slaked lime particles in the first-stage cyclone is shortened, the cooling effect is reduced, and the dioxin suppression effect is gradually reduced. It is done. Moreover, it is thought that the collection efficiency of slaked lime fell and the pressure loss and IDF efficiency fell gradually. No. In No. 4, the degree of decrease was so great that the concentration of dioxins could not be reduced to 20 ng / m 3 N or less, which is a standard.
例1で得られた終末沈降速度5cm/secの副産消石灰の投入量を変化させた場合の、排ガス中のダイオキシン類濃度等への影響について調べた。例2と同様に、図1に示す構成のセメントクリンカー製造設備において、副産消石灰を種々の原単位で原料粉砕乾燥機107から上段のサイクロン103aに投入し、セメントクリンカー製造設備を運転した。 <Example 3: Effect of input amount of by-product slaked lime on dioxin concentration in exhaust gas>
The effect on the dioxin concentration in the exhaust gas when the input amount of the by-product slaked lime having a terminal sedimentation rate of 5 cm / sec obtained in Example 1 was changed was examined. Similarly to Example 2, in the cement clinker manufacturing facility having the configuration shown in FIG. 1, by-product slaked lime was charged into the
排ガス中のHClは、「JIS K 0107排ガス中の塩化水素分析方法」により求めた。 Concentration measurement of DXN S is carried out in compliance with the "analysis of dioxins JIS K 0311 in the exhaust gas" was evaluated as the concentration of organochlorine compounds dioxins per kiln exhaust 1m 3 N (ng / m 3 N).
HCl in the exhaust gas was determined by “JIS K 0107 Method for analyzing hydrogen chloride in exhaust gas”.
理論によって本発明が限定されることを意図しないが、これらの事から、本発明による排ガス中のダイオキシン類の有機塩素化合物の濃度の低減効果は、特開2007-90261号公報(特許文献5)に記述されている中和機構ではなく、むしろ、消石灰の脱水反応による1段目サイクロン103aにおける温度低下が影響しているものと考えられる。 In Japanese Patent Application Laid-Open Publication No. 2007-90261 (Patent Document 5), CaO or Ca (OH) 2 is introduced into exhaust gas containing hydrogen chloride, the amount of hydrogen chloride in the exhaust gas is reduced, and the neutralized product is chloride. It is said that calcium is produced and as a result, the production of persistent organic pollutants such as dioxins is suppressed. However, in the results of the present invention, even if the amount of slaked lime added increases, the amount of hydrogen chloride in the exhaust gas is not reduced, and the amount of hydrogen chloride in the exhaust gas does not depend on the amount of slaked lime added.
Although it is not intended that the present invention be limited by theory, the effect of reducing the concentration of organochlorine compounds of dioxins in exhaust gas according to the present invention is disclosed in Japanese Patent Application Laid-Open No. 2007-90261 (Patent Document 5). Rather than the neutralization mechanism described in 1), it is considered that the temperature drop in the first-
102 仮焼炉
103a 1段目サイクロン
103b 2段目サイクロン
103c 3段目サイクロン
103d 4段目サイクロン
104 調合原料供給ライン
105 キルンIDF
106 排熱発電用ボイラー
107 原料粉砕乾燥機
108 スタビライザー
109 電気集塵機
110 プレヒーター
111 ライジングダクト部
112 キルン窯尻部 101
106 Boiler for waste
Claims (6)
- 複数のサイクロンを有するプレヒーター及びロータリーキルンを備えたセメントクリンカー製造設備におけるセメントクリンカー製造方法であって、終末沈降速度が0.5~10cm/secである消石灰を排ガス出口における排ガス温度が350~500℃のサイクロン内に投入する工程を含む方法。 A cement clinker manufacturing method in a cement clinker manufacturing facility equipped with a pre-heater having a plurality of cyclones and a rotary kiln, wherein the exhaust gas temperature at the exhaust gas outlet is 350 to 500 ° C. with slaked lime having a terminal sedimentation rate of 0.5 to 10 cm / sec. A method comprising the step of introducing into a cyclone.
- セメントクリンカー1t当たり前記消石灰20~200kgとなる様に、前記消石灰が投入される請求項1に記載のセメントクリンカー製造方法。 The method for producing a cement clinker according to claim 1, wherein the slaked lime is added so that the slaked lime is 20 to 200 kg per 1 ton of cement clinker.
- 前記消石灰は最上段のサイクロンに投入される請求項1又は2に記載のセメントクリンカー製造方法。 The method for producing cement clinker according to claim 1 or 2, wherein the slaked lime is charged into the uppermost cyclone.
- 前記消石灰はセメント調合原料と混合してから若しくは調合原料と並行して原料粉砕乾燥機に供給され、セメント調合原料と共に調合原料供給ラインを通って最上段のサイクロンに投入される請求項1~3の何れか一項に記載のセメントクリンカー製造方法。 The slaked lime is supplied to a raw material crushing and drying machine after being mixed with a cement preparation raw material or in parallel with the preparation raw material, and is added to the uppermost cyclone through the preparation raw material supply line together with the cement preparation raw material. The cement clinker manufacturing method as described in any one of these.
- セメントクリンカー調合原料の終末沈降速度に対する、前記消石灰の終末沈降速度の比が0.5~1.5である請求項1~4の何れか一項に記載のセメントクリンカー製造方法。 The method for producing a cement clinker according to any one of claims 1 to 4, wherein a ratio of the terminal sedimentation rate of the slaked lime to the terminal sedimentation rate of the cement clinker preparation raw material is 0.5 to 1.5.
- 前記消石灰はカルシウムカーバイドからアセチレンを発生する際に副生する消石灰である請求項1~5の何れか一項に記載のセメントクリンカー製造方法。 The method for producing a cement clinker according to any one of claims 1 to 5, wherein the slaked lime is slaked lime produced as a by-product when acetylene is generated from calcium carbide.
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