CN110885064A - System and method for producing cement clinker and sulfuric acid by using calcium sulfate - Google Patents
System and method for producing cement clinker and sulfuric acid by using calcium sulfate Download PDFInfo
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- CN110885064A CN110885064A CN201811053062.3A CN201811053062A CN110885064A CN 110885064 A CN110885064 A CN 110885064A CN 201811053062 A CN201811053062 A CN 201811053062A CN 110885064 A CN110885064 A CN 110885064A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/74—Preparation
- C01B17/745—Preparation from sulfates
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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
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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
- C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
- C04B7/44—Burning; Melting
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Abstract
The invention discloses a system for producing cement clinker and sulfuric acid by calcium sulfate, which comprises an N-grade kiln-row cyclone preheater and an M-grade kiln-row cyclone preheater, wherein the N-grade kiln-row cyclone preheater at least comprises two types of cyclone preheaters, one type is a cyclone cylinder for cement industry, and the other type is a lower exhaust cyclone separator; the M-level furnace row cyclone preheater comprises a lower exhaust cyclone separator; wherein N represents the stage number of a certain stage of the kiln row cyclone preheater, and is any natural number which is more than or equal to 3 and less than or equal to 7; m represents the stage number of the cyclone preheater of a certain stage of the furnace row, and M is any natural number which is more than or equal to 2 and less than or equal to 5. The invention also discloses a method for producing cement clinker and sulfuric acid by using the calcium sulfate. The invention realizes the smooth and stable operation of the whole production line with low resistance, high efficiency, low kiln tail frame height, less investment and low energy consumption by the combined connection of the two cyclone preheaters with different structural forms.
Description
Technical Field
The invention relates to the technical field of producing portland cement clinker and sulfuric acid by calcium sulfate, in particular to a system and a method for producing cement clinker and sulfuric acid by calcium sulfate.
Background
The suspension preheating predecomposition technology is the core of a novel dry-process cement production technology and is also a key technology for producing silicate cement clinker and byproduct sulfuric acid by calcium sulfate. The method is characterized in that gas-solid heat exchange and mass transfer in the accumulation state in the original rotary kiln are transferred into a suspension preheater to be carried out, so that the drying, preheating and decomposition processes of materials are rapidly completed in the suspension state outside the kiln.
In 1986, German Luqi corporation developed a technology for preparing sulfuric acid and co-producing cement by using an energy-saving type calcium sulfate thermal decomposition method through a circulating fluidized bed, and a pilot test was carried out to change the production mode that the conventional reduction decomposition of calcium sulfate and the calcination of cement are carried out in a long kiln into the production of sulfur dioxide gas by using the reduction decomposition of calcium sulfate in the circulating fluidized bed, and the calcination of cement into cement clinker is carried out in a short kiln, but no industrial application example is seen so far.
The preheating and predecomposition system consists of a suspension preheater and a decomposing furnace, wherein the suspension preheater adopts a cyclone, and a connecting air pipe and a discharging pipe between each stage of cyclone as a heat exchange unit. The suspension preheaters currently used in industry are generally combined by five-stage or six-stage cyclone preheaters from top to bottom in series, and the height of a civil structure (a preheater tower) is in direct proportion to the stage number of the preheaters. The heat recovery efficiency of the preheater increases with the number of stages of the cyclone, but the increase in the number of stages increases the tower of the cyclone preheater. Along with the continuous large-scale of the pre-decomposition kiln device, the height of the suspension preheater, the heat exchange pipeline and the support frame of the decomposition furnace of the pre-decomposition kiln exceeds 100 meters, so that the energy consumption for lifting materials, the steel consumption of a kiln tail frame and the civil engineering investment of the kiln tail are increased.
With the increasingly mature suspension preheating and pre-decomposition technologies, the length-diameter ratio of the decomposing furnace also tends to rise. The height of the outlet of the decomposing furnace of the existing device is far higher than the height required by the last-stage suspension preheater material entering the kiln, and in order to reduce the height of a frame of the suspension preheater, a method of additionally arranging a gooseneck (U-shaped pipe) between the outlet of the top of the decomposing furnace and the last-stage suspension preheater is adopted at present, and the downward turning back of the gooseneck is utilized to reduce the arrangement elevation of the last-stage suspension preheater. Meanwhile, the waste gas pipe of the C1 stage suspension preheater is also a gooseneck.
The cynanchum paniculatum of Nanjing university of industry is indicated in the text of the research on gas flow law test and numerical simulation in the gooseneck of oxygen decomposition furnace and waste gas pipeline: the "gooseneck" has a rather limited contribution to the increase of the retention time of the materials in the decomposing furnace for the new cement production line, and the effect is not ideal. The exhaust gas pipe and the gooseneck gas flow field are similar, and the resistance of the exhaust gas pipe and the gooseneck gas flow field is respectively equivalent to that of a cyclone preheater. The large resistance will result in the increase of the power consumption of the high temperature fan and higher operation cost.
In order to solve the problem caused by the overhigh frame of the cement preheater, the invention CN102954699A in China discloses a transverse arrangement design of the cement preheater, and the cyclone cylinder in a suspension preheater system adopts transverse arrangement to replace the vertical arrangement adopted at present. The pipeline between adjacent preheaters is designed in a U shape, raw materials are added from the position near the bottom of the U shape, and are blown away under the action of hot airflow in the pipeline and are brought to the next stage of cyclone. But the resistance of the "U" shaped duct is comparable to the resistance of a cyclone preheater. Resulting in a doubling of the resistance of the entire preheating system. The air pressure of a high-temperature fan of a kiln system is increased more, the large fan is difficult to manufacture, the power consumption is obviously increased, and no industrialized device is applied until now.
In conclusion, the system for producing cement clinker and sulfuric acid by using calcium sulfate in the prior art has the defects of overhigh support frame of the cyclone preheater, high civil engineering investment cost, high system running resistance and high energy consumption.
Disclosure of Invention
The invention aims to solve the technical problem of providing a system and a method for producing cement clinker and sulfuric acid by calcium sulfate, which have the advantages of low investment, low energy consumption, capability of arranging more stages of cyclone preheaters and high heat energy utilization rate.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a system for producing cement clinker and sulfuric acid by calcium sulfate comprises an N-grade kiln-row cyclone preheater and an M-grade kiln-row cyclone preheater, wherein the N-grade kiln-row cyclone preheater at least comprises two types of cyclone preheaters, one type of cyclone preheater is a cyclone cylinder for cement industry, and the other type of cyclone preheater is a lower exhaust cyclone separator; the M-level furnace row cyclone preheater comprises a lower exhaust cyclone separator; wherein N represents the stage number of a certain stage of the kiln row cyclone preheater, and is any natural number which is more than or equal to 3 and less than or equal to 7; m represents the stage number of the cyclone preheater of a certain stage of the furnace row, and M is any natural number which is more than or equal to 2 and less than or equal to 5.
Preferably, at least P stages in the N-stage kiln row cyclone preheater are lower exhaust cyclone separators, and the value range of P is as follows: 1 ≦ P ≦ N-1.
Preferably, the kiln row cyclone preheater positioned at the top end in the N-stage kiln row cyclone preheater is a lower exhaust cyclone separator, and at least one stage in the other kiln row cyclone preheaters is the cyclone cylinder for the cement industry.
Preferably, M is 2, and the 2-stage series cyclone preheaters are all lower exhaust cyclone separators.
The system for producing cement clinker and sulfuric acid by using calcium sulfate further comprises a reduction furnace, a rotary kiln, a scattering dryer, an air flow dryer, a clinker cooler, a furnace row exhaust fan and a dust collector; wherein, a discharge pipe of the cyclone preheater of the 1 st-stage kiln array is connected with an air inlet pipe of the cyclone preheater of the 1 st-stage kiln array, and an air outlet is connected with a kiln exhaust fan; an air outlet pipe of the 1 st-level kiln row cyclone preheater is connected with a dust collector; a discharge pipe of the N-stage kiln row cyclone preheater is connected with the reduction furnace, and an air inlet pipe of the N-stage kiln row cyclone preheater is connected with a smoke chamber at the tail of the rotary kiln; among other kiln row cyclone preheaters at all levels, the air outlet of the kiln row cyclone preheater is connected with the air inlet of the previous level through an air inlet pipe, and the discharge port is connected with the air inlet pipe of the next level through a discharge pipe;
an air outlet of the reduction furnace is connected with the M-th-level furnace row cyclone preheater, and a discharge pipe of the M-th-level furnace row cyclone preheater is respectively connected to the reduction furnace and the rotary kiln through a material distributing valve; the other furnace rows of the furnace rows are sequentially connected with each other according to the sequence of the Mth-stage furnace row cyclone preheater, the Mth-1 st-stage furnace row cyclone preheater, the scattering dryer, the airflow dryer and the 1 st-stage furnace row cyclone preheater; the kiln head of the rotary kiln is connected with a clinker cooler.
Preferably, a heat exchanger is further arranged between the 1 st-stage kiln row cyclone preheater and the dust collector; and a connecting air pipe of the 1 st-level kiln row cyclone preheater is connected with a heat exchanger, and the heat exchanger is connected with an air inlet of the dust collector through a fan.
Preferably, the dust collector is a bag type dust collector.
Preferably, a gas pipeline is connected between the reduction furnace and the heat exchanger, and a control valve is arranged on the gas pipeline.
The invention also provides a method for producing cement clinker and sulfuric acid by using calcium sulfate, and the system for producing cement clinker and sulfuric acid by using calcium sulfate comprises the following steps:
(1) drying and dehydrating: after scattering calcium sulfate raw materials, drying the calcium sulfate raw materials by an airflow dryer and an M-level furnace row cyclone preheater;
(2) preheating, reduction and decomposition: the dried calcium sulfate raw material is preheated through an N-grade kiln cyclone preheater in turn, the preheated calcium sulfate material enters a reduction furnace (15), pulverized coal and/or natural gas are added, and the oxygen content of combustion is controlled to generate CO and H2One and/or two of the components are used as reducing agents to carry out reduction reaction to obtain gas-solid mixture; the chemical reaction formula in the process is as follows:
CaS04+4CO=CaS+4C02
CaS04+4H2=CaS+4H2O
(3) and (3) calcining and cooling: after gas-solid separation of the gas-solid mixture, introducing the gas into a scattering dryer to dry the calcium sulfate raw material, and calcining the solid material in a rotary kiln to obtain SO2And the cement clinker is stored and sold outside after being cooled by a clinker cooling machine. The chemical reaction formula in the process is as follows:
CaS+2O2=CaS04
3CaS04+CaS=4Ca0+4S02
CaS+O2=Ca0+S02
preferably, when the reduction reaction of calcium sulfate is performed in step (2), calcium sulfate accounting for 36% -98% of the total sulfur content in calcium sulfate is reduced to calcium sulfide by controlling the reducing agent.
The invention has the beneficial effects that:
(1) the lower exhaust cyclone separator is matched with the cyclone cylinder for the cement industry for use, and the discharge port and the gas outlet of the lower exhaust cyclone separator are arranged at the bottom, while the gas outlet of the cyclone cylinder for the cement industry is arranged at the top and the discharge port is arranged at the bottom; through the cyclone with above-mentioned two kinds of forms use that combines, can reduce kiln tail frame height, and then reduce kiln tail frame and use steel volume and civil engineering investment, traditional "U" shape structural design modes such as "gooseneck" are compared to above-mentioned compound mode simultaneously, and system resistance is little, and the energy consumption is low, can arrange the cyclone preheater of more progression, and heat utilization rate is high.
(2) Calcium sulfate is dried by the waste heat of the reducing furnace in a suspension state through an airflow dryer, so that the heat energy utilization rate is improved.
(3) The calcium sulfate reduction reaction in the reduction furnace generates carbon dioxide and carbon dioxide generated by burning fuel for providing heat required by the reaction, the carbon dioxide is separated from the rotary kiln flue gas from the decomposition furnace and does not enter the rotary kiln flue gas containing sulfur dioxide for acid making, and the volume ratio concentration of the sulfur dioxide in the rotary kiln flue gas is improved. The rotary kiln flue gas exchanges heat with gas needing to enter the reduction furnace through the heat exchanger, so that the waste heat of the rotary kiln flue gas is more fully recovered, and the energy consumption is saved.
(4) The cloth bag type dust collector has high dust collection efficiency and creates better conditions for sulfuric acid purification and conversion.
(5) The kiln is in an oxidizing atmosphere state, so that the influence of produced CO, hydrocarbon and sulfur hydride on a sulfuric acid conversion system when the weak oxidizing atmosphere is controlled by the traditional process can be eliminated.
(6) When solid coke is not used as a reducing agent and raw materials of phosphogypsum, desulfurized gypsum, fluorgypsum and the like of which the main components are calcium sulfate are used, the traditional procedures of grinding, drying and storing raw materials are avoided, and the production flow is short.
(7) Short process flow and easy reaction atmosphereHigh control, reduction and decomposition efficiency and SO2The flue gas concentration is high.
Drawings
Fig. 1 is a schematic structural diagram of the present invention when N is 6 and M is 2.
In the figure, 1-2 nd-stage kiln row cyclone preheater, 2-1 st-stage kiln row cyclone preheater, 3-kiln row waste gas exhaust fan, 4-1 st-stage kiln row cyclone preheater, 5-4 th-stage kiln row cyclone preheater, 6-airlock valve, 7-heat exchanger, 8-3 rd-stage kiln row cyclone preheater, 9-dust collector, 10-5 th-stage kiln row cyclone preheater, 11-6 th-stage kiln row cyclone preheater, 12-2 nd-stage kiln row cyclone preheater, 13-material distributing valve, 14-coal powder feeding port for reduction furnace, 15-reduction furnace, 16-calcium sulfate feeding device, 17-scattering dryer, 18-rotary kiln, 19-clinker cooler, 20-pneumatic dryer, 21-smoke chamber, 22-gas pipeline, 23-airlock valve.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in FIG. 1, a system for producing cement clinker and sulfuric acid from calcium sulfate comprises a multi-stage kiln train cyclone preheater and a multi-stage kiln train cyclone preheater; the multi-stage kiln row cyclone preheater comprises a 2 nd-stage kiln row cyclone preheater 1, a 1 st-stage kiln row cyclone preheater 4, a 3 rd-stage kiln row cyclone preheater 8, a 4 th-stage kiln row cyclone preheater 5, a 5 th-stage kiln row cyclone preheater 10 and a 6 th-stage kiln row cyclone preheater 11 from top to bottom in sequence so as to form a 6 th-stage kiln row cyclone preheater; the multi-stage furnace row cyclone preheater is a 2-stage furnace row cyclone preheater consisting of a 1 st-stage furnace row cyclone preheater 2 and a 2 nd-stage furnace row cyclone preheater 12 from top to bottom in sequence. Wherein, between each stage of cyclone preheater, the air outlet of the next stage of cyclone preheater is connected with the air inlet of the previous stage through an air inlet pipe, and the discharge port of the next stage of cyclone preheater is connected with the air inlet pipe of the next stage of cyclone preheater. Taking the 2 nd-level kiln row cyclone preheater 12 as an example, the air outlet of the 2 nd-level kiln row cyclone preheater 12 is connected to the air inlet of the 1 st-level kiln row cyclone preheater 2 through an air inlet pipe, and the discharge outlet of the 2 nd-level kiln row cyclone preheater 1 is connected to the air inlet pipe of the 3 rd-level kiln row cyclone preheater through a discharge pipe.
In the present embodiment, the 1 st-stage kiln-row cyclone preheater 4, the 2 nd-stage kiln-row cyclone preheater 1, the 4 th-stage kiln-row cyclone preheater 5, the 1 st-stage kiln-row cyclone preheater 2, and the 2 nd-stage kiln-row cyclone preheater 12 are all lower-discharge cyclone preheaters, and the remaining kiln-row cyclone preheaters and the kiln-row cyclone preheaters are cyclone cylinders for cement industry. Wherein, the air outlet and the discharge outlet of the lower exhaust cyclone preheater are both arranged at the bottom of the cyclone preheater, and the air inlet is arranged at the side part of the cyclone preheater; the air outlet of the cyclone cylinder for the cement industry is arranged at the top of the cyclone preheater, and the discharge port is arranged at the bottom of the cyclone preheater.
Of course, the system for producing sulfuric acid and cement clinker from calcium sulfate in the invention can be freely combined by the multi-stage kiln-train cyclone preheater and the multi-stage kiln-train cyclone preheater, for example, the kiln-train cyclone preheater in the invention is not limited to 6 stages, and can also be 3 stages, 4 stages, 5 stages or 7 stages; the train cyclone preheater is not limited to 2 stages, but may be 3 stages, 4 stages or 5 stages. The combination only needs to meet the requirement that the multi-stage kiln cyclone preheater at least comprises two types of cyclone preheaters, one type is a cyclone cylinder for cement industry, and the other type is a lower exhaust cyclone separator; the multi-stage furnace row cyclone preheater comprises a lower exhaust cyclone separator.
In addition, under the condition that the requirement on the separation efficiency of the calcium sulfate is not particularly high, for example, the separation efficiency of the calcium sulfate is less than eighty percent, horizontal type cyclone preheaters with lower resistance can be used in the cyclone preheaters of the 3 rd, 4 th and 5 th kiln rows to replace lower exhaust cyclone preheaters, the height of a kiln tail frame can still be reduced, the steel consumption and the civil engineering investment of the kiln tail frame are further reduced, and meanwhile, the system resistance is small.
The key points of the invention are as follows: on the basis of the existing system for producing cement clinker and sulfuric acid by using calcium sulfate and producing cement clinker by using calcium carbonate, the lower exhaust cyclone separator is matched with the cyclone cylinder for the cement industry for use, and because the discharge port and the air outlet of the lower exhaust cyclone separator are both arranged at the bottom, and the air outlet of the cyclone cylinder for the cement industry is arranged at the top and the discharge port is arranged at the bottom; by combining the two types of cyclone separators, the number of stages of the cyclone preheater can be increased for the existing production line under the condition of not increasing the height of the kiln tail frame; or reduce kiln tail frame height on newly-built device, and then reduce for the kiln tail frame steel volume and civil engineering investment, above-mentioned compound mode compares traditional "gooseneck" etc. "U" shape structural design modes simultaneously, and system resistance is little, can arrange the cyclone preheater of more progression, and heat utilization rate is high. The invention is not only suitable for producing cement clinker and sulfuric acid by using calcium sulfate; and is suitable for producing cement clinker by using calcium carbonate, when the cement clinker is produced by using calcium carbonate, the stage number of the kiln-row cyclone preheater is the same as that of the kiln-row cyclone preheater, and the process of scattering by a scattering dryer can be cancelled.
The system for producing cement clinker and sulfuric acid by using calcium sulfate further comprises a reduction furnace 15, a rotary kiln 18, a scattering dryer 17, an airflow dryer 20, a clinker cooler 19, a furnace row exhaust fan 3, a feeding device 16 and a dust collector 9, wherein a wind locking valve 23 is arranged on a connecting pipeline of a feed opening of each stage of the kiln row cyclone preheater and the furnace row cyclone preheater; wherein, a discharge pipe of the cyclone preheater 2 of the 1 st-stage kiln row is connected with a connecting air pipe of the cyclone preheater 4 of the 1 st-stage kiln row, and an air outlet is connected with a kiln row exhaust fan 3; a connecting air pipe of the 1 st-level kiln row cyclone preheater 4 is connected with an air inlet of a dust collector 9; a discharge pipe of the 6 th-stage kiln row cyclone preheater is connected with the reduction furnace 15, and an air inlet pipe of the 6 th-stage kiln row cyclone preheater is connected with a smoke chamber 21 at the kiln tail of the rotary kiln 18; an air outlet of the reduction furnace 15 is connected with a 2 nd-level furnace row cyclone preheater; a discharge pipe of the 2 nd-stage furnace row cyclone preheater is respectively connected to a reduction furnace 15 and a rotary kiln 18 through a material distributing valve 13, and an air outlet pipe is connected with an air inlet of a scattering dryer 17; the scattering dryer 17 is provided with a feeding device 16, and a discharge hole of the scattering dryer is connected with an airflow dryer 20; the airflow dryer 20 is connected with a 1 st-stage furnace row cyclone preheater; between the other kiln row cyclone preheaters of each stage and the kiln row cyclone preheaters, the air outlets of the kiln row cyclone preheaters and the kiln row cyclone preheaters of the stage are connected with the air inlet of the previous stage through air inlet pipes, and the discharge openings are connected with the air inlet pipe of the next stage through discharge pipes; the kiln head of the rotary kiln 18 is connected with a clinker cooler 19.
Preferably, a heat exchanger 7 is further arranged between the 1 st-stage kiln row cyclone preheater 4 and the dust collector 9; and a connecting air pipe of the 1 st-level kiln row cyclone preheater 4 is connected with a heat exchanger 7, and the heat exchanger 7 is connected with an air inlet of a dust collector 9 through a fan. As a further preference, the dust collector 9 is a bag type dust collector.
Preferably, a gas pipe 22 is connected between the reduction furnace 15 and the heat exchanger 7, and a control valve is provided on the gas pipe 22. The heat of the rotary kiln flue gas is exchanged with the gas needing to enter the reduction furnace 15 through the heat exchanger 7, so that the waste heat of the rotary kiln flue gas is more fully recovered, and the energy consumption is saved.
Preferably, an air pipe (not shown) may be connected to the outlet pipe of the 2 nd-stage cyclone preheater 12, and a control valve may be provided on the air pipe. By adopting the design, the residual carbon monoxide in the reduction furnace 15 is fully and completely combusted through the introduced air, so that the combustion heat release of the carbon monoxide is fully utilized, and the harm of the carbon monoxide to the subsequent process steps is eliminated.
The system for producing cement clinker and sulfuric acid by using calcium sulfate in the embodiment is a method for producing cement clinker and sulfuric acid, and the method comprises the following process steps:
(1) drying and dehydrating: adding a calcium sulfate raw material into a scattering dryer 17 through a feeding device 16, dispersing under the action of a hammer head of the scattering dryer, simultaneously mixing with hot gas from a 2 nd-stage furnace row cyclone preheater 12, standing for a short time, sequentially entering an airflow dryer 20 and a 1 st-stage furnace row cyclone preheater 2 so as to remove free water and crystal water in the calcium sulfate raw material, performing gas-solid separation in the 1 st-stage furnace row cyclone preheater 2, and introducing the gas into a furnace row waste exhaust fan 3 through a pipeline to be discharged into a waste gas treatment system;
(2) preheating, reduction and decomposition: the steps are as followsThe material obtained by separation in the step (1) enters a cyclone preheater 4 of a kiln row of the level 1, after the material is heated and separated by the cyclone preheater 4 of the kiln row of the level 1, the gas enters a heat exchanger 7 through a pipeline for further cooling, then the gas is sent into a dust collector 9 through a fan to remove most of dust, and then the gas is sent into a sulfuric acid purification system for producing sulfuric acid, the material obtained by separation is preheated through the cyclone preheaters of the kiln row of the level 5 in sequence, the preheated calcium sulfate material finally enters a reduction furnace 15, pulverized coal and/or natural gas is added into the reduction furnace 15 through a pulverized coal adding port 14 for the reduction furnace, and the oxygen content generated by combustion is controlled to generate CO and H2One and/or two of the components are used as reducing agents to carry out reduction reaction to obtain gas-solid mixtures such as calcium sulfide, unreacted calcium sulfate and unreacted gas;
(3) and (3) calcining and cooling: after the gas-solid mixture is subjected to gas-solid separation by the cyclone preheater 12 of the 2 nd-stage furnace row, the gas is introduced into the scattering dryer 17 to dry the calcium sulfate raw material, and the solid material enters the rotary kiln 18 to be calcined to prepare SO2And the cement clinker is stored and sold after being cooled by the clinker cooler 19.
Preferably, in the step (2), during the reduction reaction of calcium sulfate, the reducing agent is controlled to reduce calcium sulfate accounting for 36% -98% of the total sulfur content in the calcium sulfate into calcium sulfide, so that the material is calcined in the rotary kiln under wider control conditions, and meanwhile, the excess of the calcium sulfate is ensured, so that sulfur dioxide with higher concentration can be obtained.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.
Claims (10)
1. A system for producing cement clinker and sulfuric acid by calcium sulfate comprises an N-grade kiln-series cyclone preheater and an M-grade kiln-series cyclone preheater, and is characterized in that: the N-stage kiln row cyclone preheater at least comprises two types of cyclone preheaters, one type is a cyclone cylinder for cement industry, and the other type is a lower exhaust cyclone separator; the M-level furnace row cyclone preheater comprises a lower exhaust cyclone separator; wherein N represents the stage number of a certain stage of the kiln row cyclone preheater, and is any natural number which is more than or equal to 3 and less than or equal to 7; m represents the stage number of the cyclone preheater of a certain stage of the furnace row, and M is any natural number which is more than or equal to 2 and less than or equal to 5.
2. The system for producing cement clinker and sulfuric acid from calcium sulfate according to claim 1, wherein: at least P stages in the N-stage kiln row cyclone preheater are lower exhaust cyclone separators, and the value range of P is as follows: 1 ≦ P ≦ N-1.
3. The system for producing cement clinker and sulfuric acid from calcium sulfate according to claim 1, wherein: the kiln row cyclone preheater positioned at the top end in the N-stage kiln row cyclone preheater is a lower exhaust cyclone separator, and at least one stage in the other kiln row cyclone preheaters is the cyclone cylinder for the cement industry.
4. The system for producing cement clinker and sulfuric acid from calcium sulfate according to claim 1, wherein: m is 2, and the 2-stage furnace row cyclone preheaters are all lower exhaust cyclone separators.
5. A system for producing cement clinker and sulfuric acid from calcium sulfate according to any one of claims 1 to 4, wherein: the device also comprises a reduction furnace (15), a rotary kiln (18), a scattering dryer (17), an air flow dryer (20), a clinker cooler (19), a furnace row exhaust fan (3), a feeding device (16) and a dust collector (9); wherein a discharge pipe of the cyclone preheater (2) of the 1 st-stage kiln row is connected with an air inlet pipe of the cyclone preheater (4) of the 1 st-stage kiln row, and an air outlet is connected with a kiln row exhaust fan (3); an air outlet pipe of the 1 st-level kiln row cyclone preheater (4) is connected with a dust collector (9); a discharge pipe of the N-stage kiln row cyclone preheater is connected with the reduction furnace (15), and an air inlet pipe of the N-stage kiln row cyclone preheater is connected with a smoke chamber (21) at the kiln tail of the rotary kiln (18); among other kiln row cyclone preheaters at all levels, the air outlet of the kiln row cyclone preheater is connected with the air inlet of the previous level through an air inlet pipe, and the discharge port is connected with the air inlet pipe of the next level through a discharge pipe;
an air outlet of the reduction furnace (15) is connected with an M-th-level furnace row cyclone preheater, and a discharge pipe of the M-th-level furnace row cyclone preheater is respectively connected to the reduction furnace (15) and the rotary kiln (18) through a material distributing valve (13); the other furnace rows of the different levels of the furnace rows are sequentially connected with each other according to the sequence of the Mth-level furnace row cyclone preheater, the Mth-1 st-level furnace row cyclone preheater, the scattering dryer (17), the airflow dryer (20) and the 1 st-level furnace row cyclone preheater (2); the kiln head of the rotary kiln (18) is connected with a clinker cooler (19).
6. The system for producing cement clinker and sulfuric acid from calcium sulfate according to claim 5, wherein: a heat exchanger (7) is also arranged between the 1 st-stage kiln row cyclone preheater (4) and the dust collector (9); and a connecting air pipe of the 1 st-stage kiln row cyclone preheater (4) is connected with a heat exchanger (7), and the heat exchanger (7) is connected with an air inlet of a dust collector (9) through a fan.
7. The system for producing cement clinker and sulfuric acid from calcium sulfate according to claim 6, wherein: the dust collector (9) is a cloth bag type dust collector.
8. The system for producing cement clinker and sulfuric acid from calcium sulfate according to claim 6, wherein: a gas pipeline (22) is connected between the reduction furnace (15) and the heat exchanger (7), and a control valve is arranged on the gas pipeline (22).
9. A method for producing cement clinker and sulfuric acid by calcium sulfate is characterized in that: a system for producing cement clinker and sulfuric acid from calcium sulfate according to claim 6, comprising the steps of:
(1) drying and dehydrating: after scattering calcium sulfate raw materials, drying the calcium sulfate raw materials by an airflow dryer and an M-level furnace row cyclone preheater;
(2) preheating, reduction decomposition: the dried calcium sulfate raw material is preheated through an N-grade kiln cyclone preheater in turn, the preheated calcium sulfate material enters a reduction furnace (15), pulverized coal and/or natural gas are added, and the oxygen content of combustion is controlled to generate CO and H2One and/or two of the components are used as reducing agents to carry out reduction reaction to obtain gas-solid mixture;
(3) and (3) calcining and cooling: after gas-solid separation of the gas-solid mixture, the gas is introduced into a scattering dryer (17) to dry the calcium sulfate raw material, and the solid material enters a rotary kiln (18) to be calcined to prepare SO2And the cement clinker is stored and sold after being cooled by a clinker cooler (19).
10. A method for producing cement clinker and sulphuric acid from calcium sulphate according to claim 9, characterised in that: and (3) reducing the calcium sulfate accounting for 36-98% of the total sulfur content in the calcium sulfate into calcium sulfide by controlling a reducing agent during the reduction reaction of the calcium sulfate in the step (2).
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