Light magnesium carbonate production device and method based on resource utilization
阅读说明：本技术 一种基于资源化利用的轻质碳酸镁生产装置及方法 (Light magnesium carbonate production device and method based on resource utilization ) 是由 王德喜 崔玮琳 周士海 刘文涛 高倩楠 范丽华 刘波 于 2021-09-30 设计创作，主要内容包括：本发明的一种基于资源化利用的轻质碳酸镁生产装置及方法,属于化工技术领域,所述装置包括消化罐、碳化罐、热解罐、闪蒸罐、卧式双鼓离心机、空心桨叶干燥机、气流磨、气流分级机；原料为低品位氧化镁,经两级串联连续消化、碳解、热解反应,均采用新型射流搅拌器,高速射流混合搅拌,强化了传热、传质,提高了气、液、固混合搅拌效果；消化、碳化、热解反应、干燥过程产生的低压水蒸汽经MVR产生二次水蒸汽为辅助加热源,综合节能36％；氧化镁提取率大于90％,轻质碳酸镁中氧化镁含量大于46.5％,副产品超细含镁碳酸钙为高分子材料的添加剂。本发明工艺流程简单,连续操作,自动化程度高,资源循环利用,环境友好,实现低品位氧化镁资源的合理利用。(The invention relates to a light magnesium carbonate production device and a light magnesium carbonate production method based on resource utilization, belonging to the technical field of chemical industry, wherein the device comprises a digestion tank, a carbonization tank, a pyrolysis tank, a flash tank, a horizontal double-drum centrifuge, a hollow blade dryer, an airflow mill and an airflow classifier; the raw material is low-grade magnesium oxide, and is subjected to two-stage series continuous digestion, carbonization and pyrolysis reactions, a novel jet flow stirrer is adopted, high-speed jet flow mixing stirring is carried out, heat transfer and mass transfer are enhanced, and gas, liquid and solid mixing stirring effects are improved; the low-pressure water vapor generated in the processes of digestion, carbonization, pyrolysis reaction and drying generates secondary water vapor through MVR as an auxiliary heating source, so that the energy is comprehensively saved by 36%; the extraction rate of magnesium oxide is more than 90%, the content of magnesium oxide in light magnesium carbonate is more than 46.5%, and the byproduct of superfine magnesium-containing calcium carbonate is an additive of a high molecular material. The method has the advantages of simple process flow, continuous operation, high automation degree, cyclic utilization of resources, environmental friendliness and realization of reasonable utilization of low-grade magnesium oxide resources.)
1. The utility model provides a light magnesium carbonate apparatus for producing based on resource utilization which characterized in that: the system comprises a digestion tank I, a digestion tank II, a carbonization tank I, a carbonization tank II and a flash tank which are connected in sequence, wherein the flash tank comprises the flash tank I and the flash tank II, and the pyrolysis tank I and the pyrolysis tank II are arranged between the flash tanks I, II; the flash tanks I, II are respectively connected with a centrifuge I, II; the digestion tank I, II is used for carrying out digestion reaction on materials; the carbonization tank I, II is used for carrying out carbonization reaction on the digestion slurry; the flash tank I is used for carrying out flash evaporation on the carbonized slurry; the centrifuge I is used for carrying out solid-liquid separation on the carbonized slurry after flash evaporation; the pyrolysis tank I, II is used for carrying out pyrolysis reaction on the magnesium bicarbonate filtrate obtained by solid-liquid separation; the flash tank II is used for carrying out flash evaporation on the pyrolysis slurry; the centrifugal machine II is used for carrying out solid-liquid separation on the flash-evaporated pyrolysis slurry to obtain a light magnesium carbonate filter cake;
wherein the stirrers arranged in the digestion tank I, the digestion tank II, the carbonization tank I, the carbonization tank II, the pyrolysis tank I and the pyrolysis tank II are all jet stirrers; CO of the carbonizer I2The gas inlet is connected with CO of the carbonization tank II and the pyrolysis tank I, II2A gas outlet, namely CO discharged from the carbonization tank I through the carbonization tank II and the pyrolysis tank I, II2The gas is reaction gas;
the device also comprises a compressor, wherein the input end of the compressor is connected with the flash tank I, II, the dryer I, II, the output end of the compressor is connected with the digestion tank I, II, and the compressor is used for collecting steam generated by the flash tank I, II and steam generated by the dryer I, II for drying filter cakes, and then boosting the pressure and raising the temperature into secondary water steam which is used as a heat source of the digestion tank I, II.
2. The light magnesium carbonate production device based on resource utilization according to claim 1, characterized in that: the device also comprises a dryer I, II, an air flow mill I, II, an air flow classifier I, II, a steam condensation water tank and a mother liquor and washing water tank; the dryer I, the jet mill I and the jet classifier I are used for drying, grinding and classifying filter cakes obtained by solid-liquid separation to obtain byproducts; the dryer II, the jet mill II and the jet classifier II are used for drying, grinding and classifying the light magnesium carbonate filter cake obtained by solid-liquid separation to obtain a product light magnesium oxide; the heat sources of the carbonization tank I, II, the pyrolysis tank I, II and the dryer I, II are raw steam;
the gas discharge pipeline of the carbonization tank I is also provided with a cooler for cooling CO discharged by the carbonization tank I2A gas; the pyrolysis tank I, II uses an airflow classifier I, II and air separated by an airflow mill I, II as an auxiliary heat source, and an air heater is arranged on an air transmission pipeline;
the input end of the steam condensate water tank is connected with the dryer I, II, the output end of the steam condensate water tank is connected with the centrifuge I, II and the digestion tank I, and the steam condensate water is used for collecting steam condensate water formed in the drying process after raw steam is introduced into the dryer I, II, and the steam condensate water is collected into the steam condensate water tank after air is heated by the air heater and is used as washing water of the centrifuge I, II and ingredient water of the digestion tank I;
the input ends of the mother liquor and washing water tank are connected with a centrifuge II, the output end is connected with a digestion tank I and used for collecting the mother liquor and washing water centrifuged by the centrifuge II, and the mother liquor and the washing water are cooled by the cooler to remove CO discharged by the carbonization tank I2The gas enters a digestion tank I as the ingredient water of the digestion tank I.
3. The resource utilization-based light magnesium carbonate production method based on the device of claim 2 is characterized in that: the method specifically comprises the following steps:
(1) raw materials of magnesium oxide, mother liquor, washing water and steam condensate water enter a digestion tank I, and secondary steam is directly heated for digestion reaction;
(2) feeding the digestion slurry in the digestion tank I into a digestion tank II, and directly heating by using secondary water vapor to continue the digestion reaction;
(3) feeding the digestion slurry in the digestion tank II into the carbonization tank I, and simultaneously sucking CO discharged from the carbonization tank II2CO discharged by gas, pyrolysis tank I and pyrolysis tank II2Gas, with raw steamHeating for carbonization reaction;
(4) feeding the carbonized slurry in the carbonization tank I into a carbonization tank II, and simultaneously introducing fresh CO2Gas, directly heating by using raw steam to continuously carry out carbonization reaction;
(5) feeding the carbonized slurry in the carbonization tank II into a flash tank I, and flashing to obtain low-pressure water vapor;
(6) feeding the carbonized slurry after flash evaporation in the flash evaporation tank I into a centrifuge I, and carrying out centrifugal separation to separate a magnesium-containing calcium carbonate filter cake and a magnesium bicarbonate filtrate;
(7) feeding the magnesium bicarbonate filtrate separated by the centrifuge I into a pyrolysis tank I, and simultaneously carrying out pyrolysis reaction on sucked hot air and raw steam;
(8) feeding the pyrolysis slurry in the pyrolysis tank I into the pyrolysis tank II, and simultaneously continuously carrying out pyrolysis reaction on the sucked hot air and the generated steam;
(9) feeding the pyrolysis slurry in the pyrolysis tank II into a flash tank II, and flashing to obtain low-pressure water vapor;
(10) feeding the pyrolysis slurry after flash evaporation in the flash tank II into a centrifuge II for centrifugal separation, feeding the separated mother liquor and washing water into a mother liquor and washing water tank, and cooling CO discharged from the carbonization tank I by a cooler of the carbonization tank I2Then entering a digestion tank I; and centrifuging by a centrifuge II to separate out a light magnesium carbonate filter cake.
4. The production method of light magnesium carbonate based on resource utilization according to claim 3, characterized in that: in the step (1), the digestion temperature of the digestion tank I is 80-85 ℃, the pressure is 0.35MPa, the digestion reaction time is 0.5-1 h, and the solid-liquid mass ratio is 1: (27-30), sucking secondary water vapor through a jet flow stirrer to directly heat and digest the slurry; in the step (2), the digestion temperature of the digestion tank II is 85-90 ℃, the pressure is 0.3MPa, and the digestion reaction time is 0.5-1 h; the secondary water vapor is sucked by a jet flow stirrer to directly heat the digestion slurry.
5. The production method of light magnesium carbonate based on resource utilization according to claim 3, characterized in that: what is needed isThe carbonization temperature of the carbonization tank I in the step (3) is 90-93 ℃, the pressure is 0.275MPa, and the carbonization reaction time is 1-1.5 h; raw steam, CO discharged from carbonization tank II and pyrolysis tank I, II2Sucking the mixture into a carbonization tank I through a jet flow stirrer; in the step (4), the carbonization temperature of the carbonization tank II is 93-96 ℃, the pressure is 0.25MPa, the carbonization reaction time is 1-1.5 h, and the raw steam and fresh CO are2Sucking into a carbonization tank II through a jet flow stirrer.
6. The production method of light magnesium carbonate based on resource utilization according to claim 3, characterized in that: in the steps (5) and (9), the flash temperature of the flash tank I, II is 80 ℃, the operation is adiabatic, and the flashed vapor enters a compressor.
7. The production method of light magnesium carbonate based on resource utilization according to claim 3, characterized in that: in the step (7): the pyrolysis temperature of the pyrolysis tank I is 105-110 ℃, the pressure is 0.25MPa, and the pyrolysis reaction time is 1-1.25 h; raw steam and hot air are sucked into the pyrolysis tank I through the jet flow stirrer; in the step (8): the pyrolysis temperature of the pyrolysis tank II is 110-115 ℃, the pressure is 0.20MPa, and the pyrolysis reaction time is 1-1.25 h; raw steam and hot air are sucked into the pyrolysis tank II through the jet flow stirrer.
8. The production method of light magnesium carbonate based on resource utilization according to claim 3, characterized in that: in the steps (6) and (10), the centrifuge I, II is a horizontal double-drum centrifuge, specifically a horizontal double-drum spiral discharge centrifuge, the outer drum of the centrifuge I, II is 2400rpm, the inner drum is 2410rpm, the retention time of the materials in the centrifuge is 5min, and the temperature of the magnesium calcium carbonate filter cake and the magnesium carbonate filter cake is 70 ℃; mother liquor and washing water separated by the centrifuge II enter a mother liquor and washing water tank, and the mother liquor and the washing water cool CO discharged from the carbon decomposition tank 12Then enters a digestion tank I.
9. The production method of light magnesium carbonate based on resource utilization according to claim 3, characterized in that: the step (6) further comprises: feeding the magnesium-containing calcium carbonate filter cake into a dryer I through a spiral conveyor, and drying the filter cake with raw steam; feeding the dried magnesium-containing calcium carbonate into an air flow mill I for grinding; feeding the ground magnesium-containing calcium carbonate powder into an airflow classifier I for classification, obtaining finished magnesium-containing calcium carbonate powder after classification, and packaging and delivering the finished magnesium-containing calcium carbonate powder; the step (10) further comprises: feeding the light magnesium carbonate filter cake into a dryer II through a spiral conveyor, and drying the light magnesium carbonate filter cake by using raw steam; feeding the dried light magnesium carbonate powder into an airflow mill II for grinding; and (4) grading the ground light magnesium carbonate powder in an airflow grader II to obtain the finished light magnesium carbonate powder, and packaging and leaving the factory.
10. The production method of light magnesium carbonate based on resource utilization according to claim 9, characterized in that: in the steps (6) and (10), the drying machine I, II is a hollow blade drying machine, the drying heat source is raw steam, the raw steam is respectively introduced into a jacket of the hollow blade drying machine I, II and the hollow blades, and condensed water of the raw steam is collected in a steam condensed water tank after heating air; drying the water vapor generated by the filter cake, and heating and boosting the water vapor by a compressor to be used as secondary water vapor; the temperature in the dryer I, II is 135 ℃ to 140 ℃, the pressure is 0.313MPa to 0.361MPa, and the material retention time is 0.75h to 1.5 h; the temperature of the discharged water vapor is 135-140 ℃, and the pressure is 0.313-0.361 MPa; the temperature of the condensed water of the steam discharged by the jacket of the dryer I, II and the hollow blade is 135-140 ℃, and the temperature of the dried material discharged by the hollow blade dryer I, II is 135-140 ℃.
Technical Field
The invention belongs to the field of chemical equipment, and particularly relates to a light magnesium carbonate production device and method based on resource utilization.
Background
The light magnesium carbonate is produced through digestion, carbonization and pyrolysis of magnesia. Digestion reaction and carbonization reaction generally adopt a tank reactor and mechanical stirring, and pyrolysis reaction generally adopts a tank reactor and mechanical stirring or tubular reactor. The preparation method has the disadvantages that the kettle type reactor transfers heat through a jacket or an inner coil pipe, and the heat exchange efficiency is low; the heat loss of the heat exchange process of the water vapor and the heavy magnesium water is more. Heavy magnesium water is easy to scar on the surface of the pyrolyzer in the pyrolysis process, the heat transfer efficiency of the pyrolyzer is reduced, the heat exchange efficiency of the pyrolyzer is low, the operation period is short, continuous production cannot be realized, and the system cannot stably run for a long period. In the method, the energy consumption of the digestion reaction, the carbonization reaction and the pyrolysis reaction is large and accounts for more than 80% of the energy consumption of the whole process, and the cost is increased due to the increase of the energy consumption, so that the method is not beneficial to industrial production.
The art is eagerly looking for a low energy consumption process for preparing light magnesium carbonate, which can overcome the above technical problems.
Disclosure of Invention
Aiming at the engineering problems and the market demand and overcoming the problems in the prior art, the invention provides the light magnesium carbonate production device and the method which have simple process flow, continuous operation, high automation degree, resource recycling and environmental protection and are used for realizing the reasonable utilization of low-grade magnesium oxide resources in light-burned magnesium, and simultaneously recovering CO generated by pyrolysis reaction2The MVR technology is utilized to recover heat generated in the carbonization reaction, the pyrolysis reaction and the drying process, and the energy consumption is greatly reduced.
In order to achieve the purpose, the invention adopts the following technical scheme:
a light magnesium carbonate production device based on resource utilization comprises a digestion tank I, a digestion tank II, a carbonization tank I, a carbonization tank II and flash tanks which are sequentially connected, wherein each flash tank comprises a flash tank I and a flash tank II, and a pyrolysis tank I and a pyrolysis tank II are arranged between the flash tanks I, II; the flash tanks I, II are respectively connected with a centrifuge I, II; the digestion tank I, II is used for carrying out digestion reaction on materials; the carbonization tank I, II is used for carrying out carbonization reaction on the digestion slurry; the flash tank I is used for carrying out flash evaporation on the carbonized slurry; the centrifuge I is used for carrying out solid-liquid separation on the carbonized slurry after flash evaporation; the pyrolysis tank I, II is used for carrying out pyrolysis reaction on the magnesium bicarbonate filtrate obtained by solid-liquid separation; the flash tank II is used for carrying out flash evaporation on the pyrolysis slurry; the centrifugal machine II is used for carrying out solid-liquid separation on the flash-evaporated pyrolysis slurry to obtain a light magnesium carbonate filter cake;
wherein the stirrers arranged in the digestion tank I, the digestion tank II, the carbonization tank I, the carbonization tank II, the pyrolysis tank I and the pyrolysis tank II are all jet stirrers; CO of the carbonizer I2The gas inlet is connected with CO of the carbonization tank II and the pyrolysis tank I, II2A gas outlet, namely CO discharged from the carbonization tank I through the carbonization tank II and the pyrolysis tank I, II2The gas is reaction gas;
the device also comprises a compressor, wherein the input end of the compressor is connected with the flash tank I, II, the dryer I, II, the output end of the compressor is connected with the digestion tank I, II, and the compressor is used for collecting steam generated by the flash tank I, II and steam generated by the dryer I, II for drying filter cakes, and then boosting the pressure and raising the temperature into secondary water steam which is used as a heat source of the digestion tank I, II.
Further, the apparatus further comprises a dryer I, II, an air mill I, II, an air classifier I, II, a steam condensate water tank and a mother liquor and wash water tank; the dryer I, the jet mill I and the jet classifier I are used for drying, grinding and classifying filter cakes obtained by solid-liquid separation to obtain byproducts; the dryer II, the jet mill II and the jet classifier II are used for drying, grinding and classifying the light magnesium carbonate filter cake obtained by solid-liquid separation to obtain a product light magnesium oxide; the heat sources of the carbonization tank I, II, the pyrolysis tank I, II and the dryer I, II are raw steam;
the carbonization tank I gas discharge pipeline is also provided with a coolerA cooler for cooling CO discharged from the carbonization tank I2A gas; the pyrolysis tank I, II uses an airflow classifier I, II and air separated by an airflow mill I, II as an auxiliary heat source, and an air heater is arranged on an air transmission pipeline;
the input end of the steam condensate water tank is connected with the dryer I, II, the output end of the steam condensate water tank is connected with the centrifuge I, II and the digestion tank I, and the steam condensate water is used for collecting steam condensate water formed in the drying process after raw steam is introduced into the dryer I, II, and the steam condensate water is collected into the steam condensate water tank after air is heated by the air heater and is used as washing water of the centrifuge I, II and ingredient water of the digestion tank I;
the input ends of the mother liquor and washing water tank are connected with a centrifuge II, the output end is connected with a digestion tank I and used for collecting the mother liquor and washing water centrifuged by the centrifuge II, and the mother liquor and the washing water are cooled by the cooler to remove CO discharged by the carbonization tank I2The gas enters a digestion tank I as the ingredient water of the digestion tank I.
The invention also provides a light magnesium carbonate production method based on resource utilization, which specifically comprises the following steps:
(1) raw materials of magnesium oxide, mother liquor, washing water and steam condensate water enter a digestion tank I, and secondary steam is directly heated for digestion reaction;
(2) feeding the digestion slurry in the digestion tank I into a digestion tank II, and directly heating by using secondary water vapor to continue the digestion reaction;
(3) feeding the digestion slurry in the digestion tank II into the carbonization tank I, and simultaneously sucking CO discharged from the carbonization tank II2CO discharged by gas, pyrolysis tank I and pyrolysis tank II2Gas, directly heating by using raw steam to carry out carbonization reaction;
(4) feeding the carbonized slurry in the carbonization tank I into a carbonization tank II, and simultaneously introducing fresh CO2Gas, directly heating by using raw steam to continuously carry out carbonization reaction;
(5) feeding the carbonized slurry in the carbonization tank II into a flash tank I, and flashing to obtain low-pressure water vapor;
(6) feeding the carbonized slurry after flash evaporation in the flash evaporation tank I into a centrifuge I, and carrying out centrifugal separation to separate a magnesium-containing calcium carbonate filter cake and a magnesium bicarbonate filtrate;
(7) feeding the magnesium bicarbonate filtrate separated by the centrifuge I into a pyrolysis tank I, and simultaneously carrying out pyrolysis reaction on sucked hot air and raw steam;
(8) feeding the pyrolysis slurry in the pyrolysis tank I into the pyrolysis tank II, and simultaneously continuously carrying out pyrolysis reaction on the sucked hot air and the generated steam;
(9) feeding the pyrolysis slurry in the pyrolysis tank II into a flash tank II, and flashing to obtain low-pressure water vapor;
(10) feeding the pyrolysis slurry after flash evaporation in the flash tank II into a centrifuge II for centrifugal separation, feeding the separated mother liquor and washing water into a mother liquor and washing water tank, and cooling CO discharged from the carbonization tank I by a cooler of the carbonization tank I2Then entering a digestion tank I; and centrifuging by a centrifuge II to separate out a light magnesium carbonate filter cake.
Further, the raw material magnesium oxide in the step (1) is low-quality magnesium oxide obtained by classifying light-burned magnesium oxide, wherein the mass fraction of the magnesium oxide is 60% -65%, the balance is calcium oxide, and the mass proportion of particles with the particle diameter of less than 0.075mm in the low-quality magnesium oxide is 95%; the used raw steam is backpressure steam with 0.4MPa and 230 ℃ of a self-contained power plant; the raw steam mainly provides heat sources for carbonization reaction, pyrolysis reaction, a dryer I and a dryer II, steam condensate water is used as auxiliary ingredient water, and mother liquor and washing water are used as ingredient main water; the heat source of the digestion reaction is provided by secondary water vapor generated by the flash tank I, the flash tank II, the dryer I and the dryer II and subjected to Mechanical Vapor Recompression (MVR), namely, the pressure and temperature rise of a compressor; the temperature of the secondary steam is 221 ℃, and the pressure of the secondary steam is 0.15 MPa.
Further, the fresh CO2CO-containing gas recovered from light-burned magnesia2Mixed gas of CO2The volume fraction of the gas is 30-35%.
Further, in the step (1), the digestion temperature of the digestion tank I is 80-85 ℃, the pressure is 0.35MPa, the digestion reaction time is 0.5-1 h, and the solid-liquid mass ratio is 1: (27-30), sucking secondary water vapor through a jet flow stirrer to directly heat and digest the slurry; in the step (2), the digestion temperature of the digestion tank II is 85-90 ℃, the pressure is 0.3MPa, and the digestion reaction time is 0.5-1 h; the secondary water vapor is sucked by a jet flow stirrer to directly heat the digestion slurry.
Further, the carbonization temperature of the carbonization tank I in the step (3) is 90-93 ℃, the pressure is 0.275MPa, and the carbonization reaction time is 1-1.5 h; raw steam, CO discharged from carbonization tank II and pyrolysis tank I, II2Sucking the mixture into a carbonization tank I through a jet flow stirrer; in the step (4), the carbonization temperature of the carbonization tank II is 93-96 ℃, the pressure is 0.25MPa, the carbonization reaction time is 1-1.5 h, and the raw steam and fresh CO are2Sucking into a carbonization tank II through a jet flow stirrer.
Further, in the steps (5) and (9), the flash temperature of the flash tank I, II is 80 ℃, the operation is adiabatic, and the flashed vapor enters a compressor.
Further, in the step (7): the pyrolysis temperature of the pyrolysis tank I is 105-110 ℃, the pressure is 0.25MPa, and the pyrolysis reaction time is 1-1.25 h; raw steam and hot air are sucked into the pyrolysis tank I through the jet flow stirrer; in the step (8): the pyrolysis temperature of the pyrolysis tank II is 110-115 ℃, the pressure is 0.20MPa, and the pyrolysis reaction time is 1-1.25 h; raw steam and hot air are sucked into the pyrolysis tank II through the jet flow stirrer.
Further, in the steps (6) and (10), the centrifuge I, II is a horizontal double-drum centrifuge, specifically a horizontal double-drum spiral discharge centrifuge, the outer drum of the centrifuge I, II is 2400rpm, the inner drum is 2410rpm, the retention time of the materials in the centrifuge is 5min, and the temperature of the magnesium calcium carbonate filter cake and the magnesium carbonate filter cake is 70 ℃; mother liquor and washing water separated by the centrifuge II enter a mother liquor and washing water tank, and the mother liquor and the washing water cool CO discharged from the carbon decomposition tank 12Then enters a digestion tank I.
Further, the step (6) further comprises: feeding the magnesium-containing calcium carbonate filter cake into a dryer I through a spiral conveyor, and drying the filter cake with raw steam; feeding the dried magnesium-containing calcium carbonate into an air flow mill I for grinding; feeding the ground magnesium-containing calcium carbonate powder into an airflow classifier I for classification, obtaining finished magnesium-containing calcium carbonate powder after classification, and packaging and delivering the finished magnesium-containing calcium carbonate powder; the step (10) further comprises: feeding the light magnesium carbonate filter cake into a dryer II through a spiral conveyor, and drying the light magnesium carbonate filter cake by using raw steam; feeding the dried light magnesium carbonate powder into an airflow mill II for grinding; and (4) grading the ground light magnesium carbonate powder in an airflow grader II to obtain the finished light magnesium carbonate powder, and packaging and leaving the factory.
Further, in the steps (6) and (10), the dryer I, II is a hollow blade dryer, the drying heat source is raw steam, the raw steam is respectively introduced into the jacket of the hollow blade dryer I, II and the hollow blades, and the condensed water of the raw steam is collected in a steam condensed water tank after heating the air; drying the water vapor generated by the filter cake, and heating and boosting the water vapor by a compressor to be used as secondary water vapor; the temperature in the dryer I, II is 135 ℃ to 140 ℃, the pressure is 0.313MPa to 0.361MPa, and the material retention time is 0.75h to 1.5 h; the temperature of the discharged water vapor is 135-140 ℃, and the pressure is 0.313-0.361 MPa; the temperature of the condensed water of the steam discharged by the jacket of the dryer I, II and the hollow blade is 135-140 ℃, and the temperature of the dried material discharged by the hollow blade dryer I, II is 135-140 ℃.
Compared with the prior art, the light magnesium carbonate production device and method based on resource utilization have the beneficial effects that:
1. the raw material magnesium oxide is low-grade magnesium oxide with the mass content of 60-65%; the raw steam is backpressure steam of a self-prepared power plant, and the secondary steam is steam generated by digestion reaction, carbonization reaction, pyrolysis reaction and drying process and subjected to MVR; CO 22The magnesium is lightly burned and pyrolyzed and recovered, and the ingredient water is steam condensate water, mother liquor and washing water; the air required by pyrolysis is heated by steam condensate water separated by drying; the resources are effectively utilized, and the environment is protected.
2. The two-stage series continuous digestion, carbonization and pyrolysis kettle adopts a novel jet flow stirrer, and high-speed jet flow mixing and stirring are adopted, so that heat transfer and mass transfer are enhanced, the gas, liquid and solid mixing and stirring effect is improved, and the production efficiency is improved;
3. low-pressure water vapor generated in the processes of digestion reaction, carbonization reaction, pyrolysis reaction and drying generates secondary water vapor through MVR, the secondary water vapor is 0.15MPa and 221 ℃ as an auxiliary heating source, and the comprehensive energy conservation is 36%;
4. the extraction rate of magnesium oxide is more than 90%, the content of magnesium oxide in light magnesium carbonate is more than 46.5%, which is higher than the standard of GB/T27814-2011 high-grade products, and the byproduct, namely superfine magnesium-containing calcium carbonate, is an additive of a high polymer material.
Drawings
FIG. 1 is a schematic structural diagram of a light magnesium carbonate production device based on resource utilization;
FIG. 2 is a raw steam flow diagram of the production apparatus of the present invention;
FIG. 3 is a flow chart of steam condensate, carbon dioxide, mother liquor and washing water in the production apparatus of the present invention;
FIG. 4 is a diagram showing the flow of secondary steam and hot air in the production apparatus of the present invention;
reference numerals: 1. a digestion tank I; 1-1, a jet flow stirrer; 1-2, a power fluid pump; 2. a digestion tank II; 2-1, a jet flow stirrer; 2-2, a power fluid pump; 3. a carbonization tank I; 3-1, a jet flow stirrer; 3-2, a power fluid pump; 3-3, a cooler; 4. a carbonization tank II; 4-1, a jet flow stirrer; 4-2, a power fluid pump; 5. a flash tank I; 6. a horizontal double-drum centrifuge I; 7. a hollow blade dryer I; 8. performing jet milling I; 9. an air classifier I; 10. a pyrolysis tank I; 10-1, a jet flow stirrer; 10-2, a power fluid pump; 11. a pyrolysis tank II; 11-1, a jet flow stirrer; 11-2, a power fluid pump; 12. a flash tank II; 13. a horizontal double-drum centrifuge II; 14. a hollow blade dryer II; 15. b, jet milling II; 16. an air classifier II; 17 a compressor; 18 mother liquor and a washing water tank; 19. an air heater; 20. a fan; 21. a steam condensate tank.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
As shown in fig. 1 to 4, a light magnesium carbonate production device based on resource utilization comprises a digestion tank I1, a digestion tank II 2, a carbonization tank I3, a carbonization tank II 4 and a flash tank which are connected in sequence, wherein the flash tank comprises a flash tank I5 and a flash tank II 12, and a pyrolysis tank I10 and a pyrolysis tank II 11 are arranged between flash tanks I, II; the flash tank I, II is respectively connected with a horizontal double-drum centrifuge I, II (6, 13); the digestion tank I, II is used for carrying out digestion reaction on materials; the carbonization tank I, II is used for carrying out carbonization reaction on the digestion slurry; the flash tank I is used for carrying out flash evaporation on the carbonized slurry; the centrifuge I is used for carrying out solid-liquid separation on the carbonized slurry after flash evaporation; the pyrolysis tank I, II is used for carrying out pyrolysis reaction on the magnesium bicarbonate filtrate obtained by solid-liquid separation; the flash tank II is used for carrying out flash evaporation on the pyrolysis slurry; the centrifugal machine II is used for carrying out solid-liquid separation on the flash-evaporated pyrolysis slurry; obtaining light magnesium carbonate filter cake;
wherein, the stirrers arranged in the digestion tank I, the digestion tank II, the carbonization tank I, the carbonization tank II, the pyrolysis tank I and the pyrolysis tank II are all jet flow stirrers; CO of the carbonizer I2The gas inlet is connected with CO of the carbonization tank II and the pyrolysis tank I, II2A gas outlet, namely CO discharged from the carbonization tank I through the carbonization tank II and the pyrolysis tank I, II2The gas is reaction gas;
the device further comprises a compressor 17, the input end of the compressor is connected with the flash tank I, II, the dryer I, II is connected with the digestion tank I, II, the compressor is used for collecting steam generated by the flash tank I, II and steam generated by drying filter cakes by the dryer I, II, and then the collected steam is subjected to Mechanical Vapor Recompression (MVR), namely secondary water vapor is formed by pressure increase and temperature rise of the compressor and is respectively introduced into the digestion tank I, II to serve as a heat source of the digestion tank I, II.
Wherein the device further comprises a hollow blade dryer I, II (7, 14), an air mill I, II (8, 15), an air classifier I, II (9, 16), a steam condensate water tank 21 and a mother liquor and wash water tank 18; the dryer I, the jet mill I and the jet classifier I are used for drying, grinding and classifying filter cakes obtained by solid-liquid separation to obtain byproducts; the dryer II, the jet mill II and the jet classifier II are used for drying, grinding and classifying the light magnesium carbonate filter cake obtained by solid-liquid separation to obtain a product light magnesium oxide; the heat sources of the carbonization tank I, II, the pyrolysis tank I, II and the dryer I, II are raw steam;
the gas discharge pipeline of the carbonization tank I is also provided with a cooler 3-3, and the cooler is used for cooling CO discharged by the carbonization tank I2A gas; the pyrolysis tank I, II uses the air classifier I, II and the air separated by the air mill I, II as auxiliary heat sources, and an air heater 19 and a fan 20 are arranged on an air transmission pipeline;
the steam condensate water tank has an input end connected with the dryer I, II and an output end connected with the centrifuge I, II and the digestion tank I and is used for collecting steam condensate water formed in the drying process after raw steam is introduced into a jacket of the hollow blade dryer I, II and hollow blades, and the steam condensate water is collected into the steam condensate water tank after air is heated by the air heater and is used as washing water of the centrifuge I, II and ingredient water of the digestion tank I;
the input ends of the mother liquor and washing water tank are connected with a centrifuge II, the output end is connected with a digestion tank I and used for collecting the mother liquor and washing water centrifuged by the centrifuge II, and the mother liquor and the washing water are cooled by the cooler to remove CO discharged by the carbonization tank I2The gas enters a digestion tank I as the ingredient water of the digestion tank I.
Wherein, the digestion tank I, the digestion tank II, the carbonization tank I, the carbonization tank II, the pyrolysis tank I, the power fluid pump (1-2, 2-2, 3-2, 4-2, 10-2, 11-2) arranged outside the pyrolysis tank II, the jet flow stirrer (1-1, 2-1, 3-1, 4-1, 10-1, 11-1) arranged in the digestion tank I, the digestion tank II, the carbonization tank I, the carbonization tank II, the pyrolysis tank I, the pyrolysis tank II consists of a plurality of jet flow devices and a coupling distributor, wherein the coupling distributor consists of a mixed liquid inlet pipe, a mixed liquid distribution cavity, a gas suction pipe, a gas distribution cavity and the like; the ejector adopts the venturi jet principle and consists of a power fluid inlet, a guide ring, a power fluid nozzle, a gas suction inlet, a mixing cavity, a diffusion cavity and a mixed liquid outlet; the circulating pump sucks the mixed liquid in the digestion tank when in operation, and the mixed liquid passes through the bladesAfter the pressure of the mixed liquid is increased, the mixed liquid is pumped into the mixed liquid distribution cavity through the mixed liquid inlet pipe, and the mixed liquid distributed by the distribution cavity enters each ejector through the mixed liquid inlet of each ejector. The power fluid passes through the nozzle to form high-speed fluid, at the moment, the kinetic energy of the fluid is maximum, the potential energy of the fluid is minimum, negative pressure is generated at the gas suction inlet, then the gas is sucked, the sucked gas is rapidly expanded in a negative pressure area and is beaten into micro bubbles by the power fluid, and the gas (water vapor and CO) in the mixing cavity2Hot air), water, magnesium oxide powder intensive mixing, the fluid carries out intensive mixing stirring in the mixed region to discharge with higher speed owing to energy exchange, increase the potential energy of mixed liquid to the maximum value through the diffusion chamber, be tangential direction directive tank bottoms, mixed fluid's dragging effect has more strengthened the mixing stirring effect. Gas is sucked into the digestion tank through the jet flow mixing stirrer, and high-speed jet flow of 300m/s can be generated in a gas-liquid mixing cavity of the jet flow mixing stirrer, so that the digestion reaction of water and the raw material magnesium oxide powder is facilitated;
when the production device is started, the digestion tank I adopts process water as ingredient water, the digestion tank I, II adopts raw steam as start-up steam (not shown in a start-up pipeline diagram) until the whole production device normally operates, the raw steam is also used as an auxiliary heating source of the digestion tank I, II when secondary steam is insufficient, all devices are connected through corresponding pipelines, and the pipelines in the attached drawings 1-4 are drawn according to the principle of vertical breaking and horizontal breaking when the pipelines are crossed on the diagram and are not actually crossed.
Example 2
The light magnesium carbonate production method based on resource utilization based on the device in the embodiment 1 comprises the following steps:
(1) 2000kg/h (feeding speed) of raw material low-quality magnesium oxide (the mass fraction of the magnesium oxide is 65%), mother liquor, washing water and 54045kg/h (feeding speed) of heating steam condensate water enter a digestion tank I; the digestion temperature of the digestion tank I is 80 ℃, the pressure is 0.35MPa, the digestion reaction time is 1h, and the solid-liquid mass ratio is 1: 30, secondary water vapor is sucked in by a jet flow stirrer at the temperature of 221 ℃, the pressure of 0.15MPa and the flow rate of 5000kg/h to directly heat the digested slurry.
(2) And feeding the digested slurry in the digestion tank I into a digestion tank II, wherein the digestion temperature of the digestion tank II is 85 ℃, the pressure is 0.3MPa, the digestion reaction time is 1h, secondary water vapor is 221 ℃, the pressure is 0.15MPa, and 1700kg/h of the digested slurry is directly heated by sucking the digested slurry through a jet flow stirrer.
(3) Feeding the digested slurry in the digestion tank II into the carbonization tank I, and simultaneously sucking the CO discharged from the carbonization tank II and the pyrolysis tank I, II2A gas; the carbonization temperature of the carbonization tank I is 90 ℃, the pressure is 0.275MPa, the carbonization reaction time is 1.5h, the raw steam is 230 ℃, the pressure is 0.4MPa, 760kg/h (the introduction rate), and CO discharged by the carbonization tank II and the pyrolysis tank I, II2Is sucked into the carbonization tank I through a jet flow stirrer.
(4) Feeding the carbonized slurry in the carbonization tank I into a carbonization tank II, wherein the carbonization temperature of the carbonization tank II is 93 ℃, the pressure is 0.25MPa, the carbonization reaction time is 1.5h, the raw steam is 1000kg/h, and fresh CO is added2Gas 220kmol/h (feed rate, CO-containing recovered light-burned magnesia)2Gas, CO235% by volume) was sucked into carbonizer II via a jet stirrer.
(5) And (3) feeding the carbonized slurry in the carbonization tank II into a flash tank I, flashing low-pressure water vapor, wherein the temperature of the flash tank I is 80 ℃, performing adiabatic flash evaporation, and feeding the flashed vapor into a compressor.
(6) Feeding the carbonized slurry after flash evaporation in the flash evaporation tank I into a horizontal double-drum centrifuge I, and carrying out centrifugal separation to obtain a magnesium-containing calcium carbonate filter cake and a magnesium bicarbonate filtrate; the outer rotary drum of the centrifuge is 2400rpm, the inner rotary drum is 2410rpm, the retention time of the materials in the centrifuge is 5min, and the temperature of the magnesium-containing calcium carbonate filter cake is 70 ℃;
wherein:
(6-1) feeding the magnesium-containing calcium carbonate filter cake into a hollow blade dryer I through a spiral conveyor, and drying with raw steam at 300 kg/h; the temperature in the hollow blade dryer I is 140 ℃, the pressure is 0.361MPa, and the material retention time is 1.5 h; the discharged water vapor with the temperature of 140 ℃ and the pressure of 0.361MPa enters a compressor; the temperature of a jacket of the hollow blade dryer I and the temperature of condensed water of steam discharged by the hollow blades are 140 ℃, and the temperature of magnesium-containing calcium carbonate powder discharged by the hollow blade dryer I and dried is 140 ℃;
(6-2) feeding the dried magnesium-containing calcium carbonate into an air flow mill I for grinding;
(6-3) feeding the ground magnesium-containing calcium carbonate powder into an airflow classifier I for classification, obtaining a finished product of the magnesium-containing calcium carbonate powder after classification, and packaging and delivering the finished product.
(7) Feeding the magnesium bicarbonate filtrate separated by the horizontal double-drum centrifuge I into a pyrolysis tank I, wherein the pyrolysis temperature of the pyrolysis tank I is 105 ℃, the pressure is 0.25MPa, and the pyrolysis reaction time is 1.25 h; 2400kg/h of raw steam and hot air are sucked into the pyrolysis tank I through the jet flow stirrer; the hot air comes from the air classifier and the air separated by the air mill is heated by the air heater.
(8) Feeding the pyrolysis slurry in the pyrolysis tank I into a pyrolysis tank II, wherein the pyrolysis temperature of the pyrolysis tank II is 110 ℃, the pressure is 0.20MPa, and the pyrolysis reaction time is 1.25 h; 3000kg/h of raw steam and hot air are sucked into the pyrolysis tank II through a jet flow stirrer; the hot air comes from the air classifier and the air separated by the air mill is heated by the air heater.
(9) And feeding the pyrolysis slurry in the pyrolysis tank II into a flash tank II, flashing low-pressure water vapor, wherein the temperature of the flash tank II is 80 ℃, performing adiabatic flash evaporation, and feeding the flashed vapor into a compressor.
(10) Feeding the pyrolysis slurry after flash evaporation in the flash tank II into a horizontal double-drum centrifuge II for centrifugal separation, feeding the separated mother liquor and washing water into a mother liquor and washing water tank, and cooling CO discharged from the pyrolysis tank 1 by the cooler of the pyrolysis tank 12Then entering a digestion tank I; centrifugally separating a light magnesium carbonate filter cake by a horizontal double-drum centrifuge II; the outer rotary drum of the centrifuge is 2400rpm, the inner rotary drum is 2410rpm, the retention time of materials in the centrifuge is 5min, and the temperature of the magnesium carbonate filter cake is 70 ℃;
wherein:
(10-1) feeding a filter cake containing light magnesium carbonate into a hollow blade dryer II through a spiral conveyor, and drying the filter cake with 600kg/h of raw steam; the temperature in the hollow blade dryer II is 140 ℃, the pressure is 0.361MPa, and the material retention time is 1.5 h; the discharged water vapor with the temperature of 140 ℃ and the pressure of 0.361MPa enters a compressor; the temperature of the condensed water of the steam discharged by the jacket of the hollow blade dryer II and the hollow blades is 140 ℃, and the temperature of the magnesium-containing calcium carbonate powder discharged by the hollow blade dryer II and dried is 140 ℃;
(10-2) feeding the dried light magnesium carbonate powder into an airflow mill II for grinding;
(10-3) feeding the ground light magnesium carbonate powder into an airflow classifier II for classification, obtaining finished light magnesium carbonate powder after classification, and packaging and leaving a factory.
Example 3
The light magnesium carbonate production method based on resource utilization based on the device in the embodiment 1 comprises the following steps:
(1) 2189kg/h of raw material low-quality magnesium oxide (mass fraction 60%), mother liquor, washing water and 54045kg/h of heating steam condensate water are put into a digestion tank I; the digestion temperature of the digestion tank I is 85 ℃, the pressure is 0.35MPa, the digestion reaction time is 0.5h, and the solid-liquid mass ratio is 1: 27, secondary water vapor is sucked in by a jet flow stirrer at the temperature of 221 ℃ and the pressure of 0.15MPa at 5000kg/h to directly heat and digest serous fluid.
(2) And feeding the digested slurry in the digestion tank I into a digestion tank II, wherein the digestion temperature of the digestion tank II is 90 ℃, the pressure is 0.3MPa, the digestion reaction time is 0.5h, secondary water vapor is 221 ℃, the pressure is 0.15MPa, and 1700kg/h is absorbed by a jet flow stirrer to directly heat the digested slurry.
(3) Feeding the digested slurry in the digestion tank II into the carbonization tank I, and simultaneously sucking the CO discharged from the carbonization tank II and the pyrolysis tank I, II2A gas; the carbonization temperature of the carbonization tank I is 93 ℃, the pressure is 0.275MPa, the carbonization reaction time is 1.5h, the raw steam is 230 ℃, the pressure is 0.4MPa, 760kg/h, CO discharged by the carbonization tank II and the pyrolysis tank I, II2Is sucked into the carbonization tank I through a jet flow stirrer.
(4) Feeding the carbonized slurry in the carbonization tank I into a carbonization tank II, wherein the carbonization temperature of the carbonization tank II is 96 ℃, the pressure is 0.25MPa, the carbonization reaction time is 1h, the raw steam is 1000kg/h, and fresh CO is added2Gas 270kmol/h (feed rate, CO content recovered from light-burned magnesia)2Gas, CO2Volume fraction 30%) was sucked into carbonizer II via a jet stirrer.
(5) And (3) feeding the carbonized slurry in the carbonization tank II into a flash tank I, flashing low-pressure water vapor, wherein the temperature of the flash tank I is 80 ℃, performing adiabatic flash evaporation, and feeding the flashed vapor into a compressor.
(6) Feeding the carbonized slurry after flash evaporation in the flash evaporation tank I into a horizontal double-drum centrifuge I, and carrying out centrifugal separation to obtain a magnesium-containing calcium carbonate filter cake and a magnesium bicarbonate filtrate; the outer rotary drum of the centrifuge is 2400rpm, the inner rotary drum is 2410rpm, the retention time of the materials in the centrifuge is 5min, and the temperature of the magnesium-containing calcium carbonate filter cake is 70 ℃;
wherein:
(6-1) feeding the magnesium-containing calcium carbonate filter cake into a hollow blade dryer I through a spiral conveyor, and drying with raw steam at 300 kg/h; the temperature in the hollow blade dryer I is 140 ℃, the pressure is 0.361MPa, and the material retention time is 1.5 h; the discharged water vapor with the temperature of 140 ℃ and the pressure of 0.361MPa enters a compressor; the temperature of a jacket of the hollow blade dryer I and the temperature of condensed water of steam discharged by the hollow blades are 140 ℃, and the temperature of magnesium-containing calcium carbonate powder discharged by the hollow blade dryer I and dried is 140 ℃;
(6-2) feeding the dried magnesium-containing calcium carbonate into an air flow mill I for grinding;
(6-3) feeding the ground magnesium-containing calcium carbonate powder into an airflow classifier I for classification, obtaining a finished product of the magnesium-containing calcium carbonate powder after classification, and packaging and delivering the finished product.
(7) Feeding the magnesium bicarbonate filtrate separated by the horizontal double-drum centrifuge I into a pyrolysis tank I, wherein the pyrolysis temperature of the pyrolysis tank I is 110 ℃, the pressure is 0.25MPa, and the pyrolysis reaction time is 1 h; 2400kg/h of raw steam and hot air are sucked into the pyrolysis tank I through the jet flow stirrer; the hot air comes from the air classifier and the air separated by the air mill is heated by the air heater.
(8) Feeding the pyrolysis slurry in the pyrolysis tank I into a pyrolysis tank II, wherein the pyrolysis temperature of the pyrolysis tank II is 115 ℃, the pressure is 0.20MPa, and the pyrolysis reaction time is 1 h; 3000kg/h of raw steam and hot air are sucked into the pyrolysis tank II through a jet flow stirrer; the hot air comes from the air classifier and the air separated by the air mill is heated by the air heater.
(9) And feeding the pyrolysis slurry in the pyrolysis tank II into a flash tank II, flashing low-pressure water vapor, wherein the temperature of the flash tank II is 80 ℃, performing adiabatic flash evaporation, and feeding the flashed vapor into a compressor.
(10) Feeding the pyrolysis slurry after flash evaporation in the flash tank II into a horizontal double-drum centrifuge II for centrifugal separation, feeding the separated mother liquor and washing water into a mother liquor and washing water tank, and cooling CO discharged from the pyrolysis tank 1 by the cooler of the pyrolysis tank 12Then entering a digestion tank I; centrifugally separating a light magnesium carbonate filter cake by a horizontal double-drum centrifuge II; the outer rotary drum of the centrifuge is 2400rpm, the inner rotary drum is 2410rpm, the retention time of materials in the centrifuge is 5min, and the temperature of the magnesium carbonate filter cake is 70 ℃;
wherein:
(10-1) feeding a filter cake containing light magnesium carbonate into a hollow blade dryer II through a spiral conveyor, and drying the filter cake with 600kg/h of raw steam; the temperature in the hollow blade dryer I is 140 ℃, the pressure is 0.361MPa, and the material retention time is 1.5 h; the discharged water vapor with the temperature of 140 ℃ and the pressure of 0.361MPa enters a compressor; the temperature of the condensed water of the steam discharged by the jacket of the hollow blade dryer II and the hollow blades is 140 ℃, and the temperature of the magnesium-containing calcium carbonate powder discharged by the hollow blade dryer II and dried is 140 ℃;
(10-2) feeding the dried light magnesium carbonate powder into an airflow mill II for grinding;
(10-3) feeding the ground light magnesium carbonate powder into an airflow classifier II for classification, obtaining finished light magnesium carbonate powder after classification, and packaging and leaving a factory.
In the light magnesium carbonate production method based on resource utilization, secondary water vapor generated by MVR is used as an auxiliary heating source, so that the energy is comprehensively saved by 36%; the extraction rate of magnesium oxide is more than 90%, the content of magnesium oxide in 2500kg/h light magnesium carbonate is more than 46.5%, which is higher than the standard of GB/T27814-2011 high-grade product, and 1420kg/h byproduct superfine magnesium-containing calcium carbonate is an additive of a high polymer material.
The technical idea of the present invention is described in the above technical solutions, and the protection scope of the present invention is not limited thereto, and any changes and modifications made to the above technical solutions according to the technical essence of the present invention belong to the protection scope of the technical solutions of the present invention.
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