CN1289443C - Method and apparatus for producing calcium ammonium nitrate using by-product calcium nitrate of nitrate phosphatic fertilizer - Google Patents
Method and apparatus for producing calcium ammonium nitrate using by-product calcium nitrate of nitrate phosphatic fertilizer Download PDFInfo
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Abstract
The present invention relates to a technical method of producing ammonium nitrate calcium using side products of rough calcium nitrate solutions of nitrophosphate fertilizers, which comprises the following steps: filtered solutions of rough calcium nitrate react with gas ammonia in a pipe type reactor, ammonium calcium nitrate is formed, the pH value is regulated to be five, and the ammonium calcium nitrate is evaporated, expanded and evaporated in a flash way; gases and liquids are separated under negative pressure; the generated slurry, atomizing air, the crystal seeds of the ammonium calcium nitrate and fluid gases simultaneously enter a granulating machine of a fluid bed of a revolving drum to be used for coating and granulation, and the granules of the ammonium calcium nitrate are prepared. The present invention uses the granulation technology of the fluid bed of the revolving drum to be used for coating and granulation, the cooling efficiency is enhanced by the fluid bed, and the size of the granules of the ammonium calcium nitrate can be adjusted. The present invention has the advantages of favorable sphericity, large compressive strength, difficult formation of blocks and favorable product property.
Description
Technical Field
The invention relates to a production method of calcium ammonium nitrate, in particular to a process method for producing calcium ammonium nitrate by using a nitric phosphate fertilizer byproduct crude calcium nitrate liquid. The invention also relates to a device for implementing the method.
Background
Calcium ammonium nitrate, also known as ammoniated calcium nitrate, has a molecular formula of 5Ca (NO)3)2·NH4NO3·10H2O, the molecular weight is 1080, the nitrogen content is 15.5 percent, more than ninety percent of the total weight is nitrate nitrogen, and the rest is ammonium nitrogen, and the water-soluble calcium oxide content is 25 percent. The calcium ammonium nitrate is mainly used as a fertilizer, and mainly contains nitrate nitrogen and water-soluble calcium oxide, so that the calcium ammonium nitrate has the advantages of quick acting, high utilization rate, easy absorption by crops, suitability for calcium-loving crops and the like, and is particularly suitable to be used as a foliar fertilizer to be sprayed on fruits, vegetables, melons and fruits.
The European is rich in acid soil, and a plurality of countries originally have devices for producing calcium nitrate fertilizer by reacting nitric acid and limestone, such as Norway produces nitric acid by an electric arc method in the early twentieth century and then produces the calcium nitrate product. With the large-scale growth of the industry of the frozen nitrophosphate fertilizer in Europe, the by-product calcium nitrate can be economically processed into calcium ammonium nitrate for sale, so that the calcium ammonium nitrate is widely produced in Europe as early as the middle of the 20 th century.
The most original method for preparing calcium ammonium nitrate by using calcium nitrate as by-product of frozen nitrophosphate fertilizer as raw material is to feed the crystal of calcium nitrate tetrahydrate filtered out in filtering procedure into stirring tank, heat and melt it with steam, then add ammonia gas to neutralize the nitric acid in calcium nitrate melt until pH is equal to4, simultaneously adding nitric acid and ammonia to ensure that the molar ratio of calcium nitrate to ammonium nitrate is 5: 1, and then evaporating and concentrating to ensure that the water content of the molten liquid is reduced from 30 percent to 15-16 percent and Ca (NO) is added3)2∶NH4NO3∶H2Adjusting O (molar ratio) to 5: 1: 10, discharging the melt on a cooling roller to obtain 5Ca (NO)3)2·NH4NO3·10H2O a crystalline flake product. A disadvantage of this product is its extreme hygroscopicity.
In the sixties of the last century, the Dutch-Tamca company develops an oil immersion granulation process specially for calcium ammonium nitrate, and the granulation equipment is a vertical conical bottom circular oil tank which is filled with mineral oil and contains a very small amount of calcium ammonium nitrate seed crystals and paraffin, a rotating basket with holes is arranged above the oil tank, calcium ammonium nitrate melt liquid is sprayed to the oil tank with the temperature of 45-50 ℃ through the rotating basket, and then is cooled and solidified into granules when meeting the calcium ammonium nitrate seed crystals, the discharged heat is taken away by the oil, the mineral oil is circularly cooled, the calcium ammonium nitrate collected at the conical bottom is put into a centrifugal machine and is made into a finished product after being dried, and a small amount of finished product is ground and is continuously supplemented into the circulating mineral oil as the seed crystals. The oil-immersed pelleting process is characterized in that the product is not easy to absorb moisture and agglomerate, but has the defects of small production capacity, difficult large-scale production, small product granularity, unadjustable granularity, and limited application range due to the mineral oil, such as incapability of being used for nutrient solution of soilless culture.
In the early stage, Norweghai Delu company used a disc granulator to produce calcium ammonium nitrate, in which a large amount of return material was loaded on a rotating disc with an inclination angle, and a calcium ammonium nitrate melt was sprayed on the surface of the tumbling return material particles to grow the return material continuously, and then the return material was sieved, classified and cooled to obtain a finished product, and fine particles and crushed large particles were circulated to the disc granulator as return material. The process has the characteristics of adjustable particlesize, large equipment occupation, small production capacity and poor operating environment.
Later, to accommodate large-scale production, Hadelu corporation developed a tower spray granulation technique for scale production above the 20-million ton scale. The tower type spraying granulation process is characterized in that calcium ammonium nitrate molten liquid is pumped into a feeding trough of a granulation tower, and is pumped into a plurality of groups of nozzles at the top of the granulation tower through a spraying pump, meanwhile, dry air is blown into calcium ammonium nitrate seed crystals at the nozzles, the molten liquid is discharged from the nozzles to form liquid drops with a certain size, the liquid drops fall from the top of a tower with the height of dozens of meters, the liquid drops are cooled by the counter-current dry air and then crystallized into granules, the liquid drops are discharged from the bottom of the tower, and then the granules are. The process features high productivity, small product particles, unadjustable particle size, and high equipment investment, and is only suitable for large-scale production.
02146785.4, commonly filed by China petrochemical company Limited and Qinghua university, provides a rotary drum fluidized bed granulation technique, wherein the rotary drum fluidized bed is provided with folding shoveling plates uniformly distributed on the inner wall of a rotary drum, a fluidized bed is arranged at the center of the rotary drum along the axial direction, seed crystal particles are continuously added from a feeding end of the rotary drum, the shoveling plates on one hand enable the particle materials at the bottom of the rotary drum to be shoveled into the fluidized bed, after being fully cooled, the particle materials flow down from one side of the spraying direction of a slurry nozzle along an overflow port to form a continuous and uniform material curtain, on the other hand,the particle materials are moved from an inlet end to an outlet end, a slurry pipe extends into the rotary drum along the axial direction of the rotary drum, a plurality of nozzles are arranged on the side surface of the material curtain along the axial direction of the rotary drum, and are provided with atomizing air, the nozzles atomize the slurry into liquid drops, the, Solidifying, dropping the increased particles to the bottom of the rotary drum, and then making the particles into the fluidized bed again, repeating the above processes to ensure that the particles grow up gradually in the spiral advancing process, wherein the fluidized bed has the function of cooling to take away latent heat and sensible heat of crystallization. The granulating technology of the rotary drum fluidized bed belongs to melt granulation, namely the feed liquid has no redundant moisture, drying and dehydration are not needed after granulation, the whole granulating process is coating granulation, and the particles are coated layer by layer and cooled layer by layer, so that the product particles have better sphericity, adjustable size and high compressive strength, and can produce large-particle products which are not easy to agglomerate. However, the technology is only applied to urea production at present and cannot be popularized and implemented in other fields. Because the physicochemical property of the calcium ammonium nitrate is greatly different from that of the urea, the granulation technology cannot be directly applied to the granulation production of the calcium ammonium nitrate.
Disclosure of Invention
The invention aims to provide a novel process method for producing calcium ammonium nitrate by using a byproduct calcium nitrate of a nitrophosphate fertilizer and a production device suitable for the process method.
The process method for producing calcium ammonium nitrate by using the byproduct calcium nitrate of the nitrophosphate fertilizer comprises the following steps:
1) pumping the byproduct coarse calcium nitrate liquid from the nitrophosphate fertilizer device into a filter press, and continuously filtering;
2) the filtrate obtained by filtering and gas ammonia are proportionally introduced into a tubular reactor to generate neutralization reaction to generate calcium ammonium nitrate;
3) the calcium ammonium nitrate solution enters at least two neutralization stirring tanks connected in series, gas ammonia is introduced, and the pH value of the calcium ammonium nitrate solution is adjusted to be about 5;
4) preheating the adjusted calcium ammonium nitrate solution in the last step, introducing the preheated solution into an evaporator, and heating the preheated solution to a boiling point for evaporation;
5) the evaporated gas-liquid mixture enters an evaporation separator, the gas-liquid mixture expands and flashes at the evaporation separator, and gas-liquid separation is realized under negative pressure;
6) the evaporated liquid gathered at the bottom of the evaporation separator automatically flows into a granulation feeding groove to form slurry for granulation, and the evaporated gas is cooled by a condenser and then recovered;
7) the slurry from the granulation feeding groove, atomizing air, the calcium ammonium nitrate seed crystals and fluidizing gas enter a rotary drum fluidized bed granulator simultaneously, the atomized air is used for atomizing the slurry, the atomized slurry is coated on the surface of the calcium ammonium nitrate seed crystals for granulation, and the fluidized gas is used for cooling and fluidizing the slurry to prepare calcium ammonium nitrate particles;
8) the prepared calcium ammonium nitrate particles are lifted to a double-layer vibrating screen by a bucket elevator, the sieved qualified particle size calcium ammonium nitrate particles enter a drum fluidized bed cooler, and a qualified product is obtained after cooling;
9) after being crushed by a roller crusher, the sieved large-particle calcium ammonium nitrate and the sieved small-particle calcium ammonium nitrate return to a rotary drum fluidized bed granulator to be used as seed crystals for re-granulation.
In the steps, when the crude calcium nitrate liquid is pumped into the continuous filter press, the inlet pressure of the filter press is 0.1-0.3 Mpa, the operating temperature is 60-90 ℃, the pressure less than 0.1Mpa and the operating temperature less than 60 ℃ can cause the reduction of the filtering capacity, and when the pressure is more than 0.3Mpa and the operating temperature is more than 90 ℃, the energy consumption of the system can be increased.
And the proper reaction temperature for the neutralization reaction of the filtrate and the gaseous ammonia in the tubular reactor is 70-110 ℃. When the reaction temperature is lower than 70 ℃, the reaction speed is too slow, and when the reaction temperature is higher than 110 ℃, the gas ammonia is escaped, and the loss is increased.
The evaporator for heating and evaporating the calcium ammonium nitrate solution has the operating temperature of 150-155 ℃ and the pressure of 0-minus 0.02 Mpa. Too low an operating temperature or too high a pressure will result in a lower concentration of the vaporized vapor-liquid mixture material which is not conducive to expansion flash in the vaporization separator, and similarly, if too high an operating temperature or too low a pressure will result in a higher concentration of the vaporized vapor-liquid mixture material which is not conduciveto expansion flash. After the evaporated gas-liquid mixture enters the evaporation separator, the gas-liquid mixture is expanded and flashed under the negative pressure of-2 kPa to realize gas-liquid separation.
The operation temperature in the drum of the rotary drum fluidized bed granulator suitable for granulating the calcium ammonium nitrate is 50-90 ℃, if the temperature is reduced, the area of the fluidized bed needs to be increased, so that the investment is increased, but the temperature is too high and is close to the melting point of the calcium ammonium nitrate, so that the operation difficulty is also caused. The proper operation pressure in the drum of the rotary drum fluidized bed granulator is-100 to-500 Pa and is more than-100 Pa, which is easy to cause dust in the equipment to be blown out and pollute the environment, and is less than-500 Pa, thus increasing the power consumption of the equipment.
During granulation, slurry and atomized air enter a rotary drum fluidized bed granulator at the temperature of 120-140 ℃ and the pressure of 0.2-0.4 Mpa, and when the temperature is lower than 120 ℃, the temperature is close to the solidification temperature of materials, so that the materials are easy to crystallize, and a nozzle is blocked; the pressure less than 0.2Mpa will directly affect the atomizing effect of the atomizing air.
Correspondingly, the suitable operation temperature in the drum of the rotary drum fluidized bed cooler is 30-50 ℃, and the operation pressure is-100 to-500 pa. If the operating temperature in the drum is greater than 50 ℃, the product tends to cake.
A large amount of granulation waste gas generated by the rotary drum fluidized bed granulator and the rotary drum fluidized bed cooler is recycled and dedusted by the super gravity deduster.
The device for realizing the method comprises the following steps:
two filter presses, one is opened and the other is prepared for intermittent work, and the filter presses are used for continuously filtering the byproduct coarse calcium nitrate liquid from the nitrophosphate fertilizer device;
a filtrate tank for collecting filtrate filtered by the filter press;
a tubular reactor, wherein the filtrate from the filtrate tank and gas ammonia are proportionally introduced into the tubular reactor for neutralization reaction to generate calcium ammonium nitrate;
at least two neutralizing and stirring tanks which are sequentially connected in series behind the tubular reactor and are used for receiving the calcium ammonium nitrate solution generated by the reaction of the tubular reactor, introducing gas ammonia and adjusting the pH value of the calcium ammonium nitrate solution to about 5;
an evaporator for receiving the calcium ammonium nitrate solution from the neutralizing and stirring tank and evaporating the calcium ammonium nitrate solution into a vapor-liquid mixture;
a preheater installed before the evaporator for heating the calcium ammonium nitrate solution;
an evaporation separator for receiving the vapor-liquid mixture from the evaporator and performing expansion flash evaporation to realize gas-liquid separation under negative pressure;
a granulation feeding groove for collecting the evaporation end liquid collected at the bottom of the evaporation separator to form the granulation slurry;
a condenser for cooling and recovering the evaporation gas generated by the evaporation separator;
a rotary drum fluidized bed granulator, wherein slurry, atomizing air, ammonium calciumnitrate crystal seeds and fluidizing gas simultaneously enter the rotary drum fluidized bed granulator for coating and granulation;
a screening device which comprises a bucket elevator arranged at the discharge port of the rotary drum fluidized bed granulator and a double-layer vibrating screen positioned behind the bucket elevator and is used for screening out calcium ammonium nitrate granules with qualified granularity;
a drum fluidized bed cooler, wherein the screened qualified granularity calcium ammonium nitrate granules enter the drum fluidized bed cooler to be cooled to obtain a product;
a roller crusher for crushing the large granular calcium ammonium nitrate sieved by the double-layer vibrating mesh screen; and
and the return channel is used for feeding the crushed large-particle calcium ammonium nitrate and the small-particle calcium ammonium nitrate back to the rotary drum fluidized bed granulator together.
The device of the invention can also comprise a super gravity dust remover which is used for recovering and removing dust from the granulation waste gas generated by the rotary drum fluidized bed granulator and the rotary drum fluidized bed cooler.
The continuous filter press adopted by the invention has low equipment price and high production capacity, and is particularly suitable for filtering coarse calcium nitrate; the adopted tubular reactor has the advantages of small volume and low energy consumption; the slurry evaporation adopts a once-through evaporator, and the evaporation efficiency is obviously higher than that of other types of evaporators.
Particularly, the invention introduces the granulation cooling technology of the rotary drum fluidized bed into the production granulation process of calcium ammonium nitrate, utilizes the special nozzle and the shoveling plate arranged in the rotary drum fluidized bed to ensure that calcium ammonium nitrate slurry is atomized and then sprayed on a seed crystal particle curtain falling in the drum to form coating granulation, and simultaneously starts from strengthening heat transfer strength according to the characteristic of larger heat release of calcium ammonium nitrate crystallization, utilizes the fluidized bed to take away latent heat and sensible heat of crystallization, and improves cooling efficiency. Because the calcium ammonium nitrate granules are coated layer by layer and cooled layer by layer, the prepared granules have better sphericity, adjustable product granule size, high compressive strength, difficult caking and high production efficiency of granulation equipment.
By adopting the process method and the production device, the production process of the calcium ammonium nitrate has the advantages of low investment, small occupied area, low energy consumption, simple operation and excellent product performance.
Drawings
FIG. 1 is a process flow diagram for producing calcium ammonium nitrate from a byproduct calcium nitrate of a nitrophosphate fertilizer.
Detailed Description
The specific process for producing calcium ammonium nitrate by using the byproduct calcium nitrate of the nitrophosphate fertilizer is shown in figure 1, wherein a crude calcium nitrate solution with the temperature of 80 ℃ from a crude calcium nitrate storage tank of the nitrophosphate fertilizer device is pumped into a filter press 1 through a filter press feeding pump under the pressure of 0.2 Mpa. Filtering by a filter press 1 to remove about 1% of acid insolublesubstances in the crude calcium nitrate solution, returning the concentrated phase after filter pressing to a crude calcium nitrate storage tank, and automatically flowing the filtrate into a filtrate tank 2.
If the analysis shows that when the acid concentration in the crude calcium nitrate solution in the crude calcium nitrate storage tank exceeds 3.0 percent, in order to ensure that the mol ratio of the product calcium ammonium nitrate is approximate to 5: 1: 10, a proper amount of CaCO needs to be added into the filtrate tank 23Powder to neutralize excess nitric acid therein, the reaction formula is as follows:
the filtrate in the filtrate tank is pumped into the tubular reactor 3 by a filtrate pump, and simultaneously, according to the raw material composition content in the filtrate, the gas ammonia is also introduced into the tubular reactor 3 under the control of a flow ratio regulating valve, so that the gas ammonia and the nitric acid in the filtrate are subjected to neutralization reaction in the tubular reactor 3 at the temperature of 70-110 ℃, and the reaction formula is as follows:
two neutralizing agitation tanks 4 and 5 are sequentially connected behind the tubular reactor 3, the calcium ammonium nitrate solution which is obtained after the reaction in the tubular reactor 3 enters the neutralizing agitation tanks 4 and 5 which are connected in series, and the gas ammonia amount which enters the neutralizing agitation tanks 4 and 5 is adjusted by a pH value automatic analyzer, so that the calcium ammonium nitrate solution in the neutralizing agitation tanks 4 and 5 finally reaches about pH value 5, and Ca (NO) in the calcium ammonium nitrate solution3)2∶NH4NO3∶H2O satisfies the molar ratio of 5: 1: 10. The temperature of the calcium ammonium nitrate solution in the neutralizing agitation tanks 4, 5 rises to about 80 c due to the exothermic reaction of gaseous ammonia with nitric acid.
The pH-adjusted calcium ammonium nitrate solution in the neutralizing and stirring tanks 4, 5 overflows and flows into an evaporation feed tank 6 under the action of gravity, is pumped out by an evaporation feed pump, is pumped into a calcium ammonium nitrate solution heat exchanger 7, exchanges heat with the hot calcium ammonium nitrate solution from the granulation feed tank 11 at about 135 ℃, then enters a preheater 8, further heats the calcium ammonium nitrate solution by using a condensate of medium-pressure saturated steam introduced into an evaporator 9 after heating and evaporating the calcium ammonium nitrate solution as a heat source, and finally enters the evaporator 9 after the temperature of the calcium ammonium nitrate solution is raised from 100 ℃ to about 130 ℃.
The method comprises the steps of using medium-pressure saturated steam as a heat source in an evaporator 9, heating a calcium ammonium nitrate solution to a boiling point of 154 ℃ by adjusting the medium-pressure steam quantity to evaporate, enabling a steam-liquid mixture generated by evaporation to flow out of the evaporator 9 and enter an evaporation separator 10, performing expansion flash evaporation in the evaporation separator 10, and performing gas-liquid separation, wherein the pressure in the evaporation separator 10 is-2 kPa.
The evaporated liquid collected at the bottom of the evaporator-separator 10 after the evaporation and separation flows into the granulation feeding tank 11, and at this time, the composition of the molar number of the calcium ammonium nitrate solution in the granulation feeding tank 11 is about 5: 1: 10, andthe temperature is about 135 ℃. Pumping the solution by a granulating feeding pump, firstly passing through a calcium ammonium nitrate liquid heat exchanger 7, exchanging heat with cold calcium ammonium nitrate solution from an evaporation feeding groove 6, reducing the temperature to 122 ℃, and sending the solution to a rotary drum fluidized bed granulator 12 for granulation.
The inner wall of a rotary drum of the rotary drum fluidized bed granulator 12 is provided with folding shoveling plates which are uniformly distributed, the center of the inside of the rotary drum is provided with a fluidized bed along the axial direction, a slurry pipe extends into the rotary drum along the axial direction of the rotary drum, a plurality of nozzles are arranged on the side surface of the rotary drum which is axially vertical to a material curtain, and atomized air is connected to the inlets of the nozzles. The method is characterized in that calcium ammonium nitrate crystal seed particles from an electronic belt feeding scale are continuously added from a feeding end of a rotary drum, on one hand, the particle materials at the bottom of the rotary drum are shoveled into a fluidized bed by a shoveling plate, after the particle materials are fully cooled, the particle materials flow down along an overflow port from one side of a spraying direction of a slurry nozzle to form a continuous and uniform calcium ammonium nitrate material curtain, and on the other hand, the particle materials are gradually moved from an inlet end to an outlet end. The drum operation temperature of the drum fluidized bed granulator 12 is 70 ℃, the pressure is-300 pa, the calcium ammonium nitrate slurry with the temperature of 122 ℃ and the pressure of 0.35Mpa is conveyed by a granulation feeding pump and enters the drum through a slurry pipe, and meanwhile, the atomizing air heated to 122 ℃ by an atomizing air heater atomizes the calcium ammonium nitrate slurry into liquid drops at anozzle in the drum fluidized bed granulator under the pressure of 0.35Mpa, and the liquid drops are sprayed on a calcium ammonium nitrate particle curtain. The liquid drops collide with the moving particles, the particles are coated and solidified on the surfaces, the enlarged calcium ammonium nitrate particles fall to the bottom of the rotary drum, and are copied into the fluidized bed again, and the process is repeated, so that the calcium ammonium nitrate particles grow up gradually in the spiral advancing process. The atmospheric air pressurized by the granulation blower and filtered by the granulation fluidization air filter is introduced into the fluidized bed to take away latent heat and sensible heat of crystallization, so that the resulting particles are cooled.
The granulated calcium ammonium nitrate is discharged from a discharge port of a rotary drum fluidized bed granulator 12, is lifted by a bucket elevator 13, is added into a double-layer vibrating screen 14, large particles of the sieved calcium ammonium nitrate enter a roller type crusher 15 for crushing, and after being converged with small particles of the calcium ammonium nitrate crushed by the roller type crusher 15, the small particles of the sieved calcium ammonium nitrate are conveyed to a material returning hopper through a material returning belt conveyor and then to an electronic belt feeding scale to be metered and then sent to the rotary drum fluidized bed granulator 12 as calcium ammonium nitrate seed crystal particles.
The finished product of the qualified granularity calcium ammonium nitrate separated by the double-layer vibrating screen 14 automatically flows into a rotary drum fluidized bed cooler 16 with the temperature of 35 ℃ and the pressure of-300 pa, and cooling air filtered by a cooling air filter and pressurized by a cooling blower is introduced into the rotary drum fluidized bed cooler 16 to cool the finished product of the calcium ammonium nitrate. And the cooled finished calcium ammonium nitrate product automatically flows into a finished product hopper, and is weighed and packaged by a packaging machine and then is stored in a warehouse.
The three wastes generated in the production process are treated in the following modes:
the gas-phase secondary steam generated by the evaporation separator 10 enters a condenser 17, is condensed and cooled under the pressure of 0-0.02 Mpa, the temperature of the gas-phase secondary steam is reduced to 60 ℃, the gas-phase secondary steam automatically flows into a process condensate tank 18, and the non-condensable gas is directly discharged.
The granulation exhaust gas from the rotary drum fluidized bed granulator 12 and the rotary drum fluidized bed cooler 16 firstly enters a cyclone separator, the separated fine particles are introduced into an underground tank, and the rest exhaust gas is pumped into a granulation induced draft fan, is pressurized and then enters a super gravity dust collector 19. The dust-containing air, granulation waste gas and acid gas from the filtering and neutralizing processes discharged by each fan also enter the super gravity dust collector 19, the process condensate pumped by the process condensate tank 18 also flows with the tail gas in parallel and enters the super gravity dust collector 19, after being processed by the super gravity dust collector at the rotating speed of 200-400 rpm, the gas-liquid mixture at the outlet is separated by the gas-liquid separator 20, the solution is sent back to the super gravity dust collector 19 by the circulating pump and continuously contacts with the waste gas in parallel flow, dust and acid mist are washed away, and the waste gas is discharged from the top of the gas-liquid separator 20. When the process condensate, in which the dust (fine material) and acid mist in the exhaust gas are dissolved, has a salt content of 23%, it is discharged to an underground tank.
After the tail gas is treated by adopting the supergravity dust removal technology, the dust content of all tail gas of the calcium ammonium nitrate device is less than or equal to 40mg/m after the tail gas is treated3And the emission standard is reached.
The fine particles separated by the cyclone separator and the process condensate with the salt content of 23 percent collected in the underground tank are pumped back to the evaporation feed tank 6 by the underground tank for continuous recycling.
Claims (10)
1. The process method for producing calcium ammonium nitrate by using the byproduct calcium nitrate of the nitrophosphate fertilizer comprises the following steps:
1) pumping the byproduct coarse calcium nitrate liquid from the nitrophosphate fertilizer device into a filter press, and continuously filtering;
2) the filtrate obtained by filtering and gas ammonia are proportionally introduced into a tubular reactor to generate neutralization reaction to generate calcium ammonium nitrate;
3) the calcium ammonium nitrate solution enters at least two neutralization stirring tanks connected in series, gas ammonia is introduced, and the pH value of the calcium ammonium nitrate solution is adjusted to be about 5;
4) preheating the adjusted calcium ammonium nitrate solution in the last step, introducing the preheated solution into an evaporator, and heating the preheated solution to a boiling point for evaporation;
5) the evaporated gas-liquid mixture enters an evaporation separator, the gas-liquid mixture expands and flashes at the evaporation separator, and gas-liquid separation is realizedunder negative pressure;
6) the evaporated liquid gathered at the bottom of the evaporation separator automatically flows into a granulation feeding groove to form slurry for granulation, and the evaporated gas is cooled by a condenser and then recovered;
7) the slurry from the granulation feeding groove, atomizing air, the calcium ammonium nitrate seed crystals and fluidizing gas enter a rotary drum fluidized bed granulator simultaneously, the atomized air is used for atomizing the slurry, the atomized slurry is coated on the surface of the calcium ammonium nitrate seed crystals for granulation, and the fluidized gas is used for cooling and fluidizing the slurry to prepare calcium ammonium nitrate particles;
8) the prepared calcium ammonium nitrate particles are lifted to a double-layer vibrating screen by a bucket elevator, the sieved qualified particle size calcium ammonium nitrate particles enter a drum fluidized bed cooler, and a qualified product is obtained after cooling;
9) after being crushed by a roller crusher, the sieved large-particle calcium ammonium nitrate and the sieved small-particle calcium ammonium nitrate return to a rotary drum fluidized bed granulator to be used as seed crystals for re-granulation.
2. The process as claimed in claim 1, wherein the crude calcium nitrate solution is introduced into the filter press at a pressure of 0.1 to 0.3MPa and at a temperature of 60 to 90 ℃.
3. The process of claim 1, wherein the reaction temperature of the tubular reactor is 70 to 110 ℃.
4. The process of claim 1, wherein the evaporator is operated at a temperature of 150 to 155 ℃ and a pressureof 0 to-0.02 MPa.
5. The process method as claimed in claim 1, wherein the operating temperature in the drum of the rotary drum fluidized bed granulator is 50-90 ℃, and the pressure is-100 to-500 pa.
6. A process according to claim 1, wherein the slurry is fed into a rotary drum fluid bed granulator with atomizing air at a temperature of 120 to 140 ℃ and a pressure of 0.2 to 0.4 MPa.
7. The process as claimed in claim 1, wherein the operating temperature in the drum of the rotary drum fluidized bed cooler is 30-50 ℃ and the pressure is-100 to-500 pa.
8. The process of claim 1, further comprising the steps of:
and recovering granulation waste gas generated by the rotary drum fluidized bed granulator and the rotary drum fluidized bed cooler through the super gravity dust remover and removing dust.
9. An apparatus for implementing the method of claim 1, the apparatus comprising:
two filter presses, one is opened and the other is prepared for intermittent work, and the filter presses are used for continuously filtering the byproduct coarse calcium nitrate liquid from the nitrophosphate fertilizer device;
a filtrate tank for collecting filtrate filtered by the filter press;
a tubular reactor, wherein the filtrate from the filtrate tank and gas ammonia are proportionally introduced into the tubular reactor for neutralization reaction to generate calcium ammonium nitrate;
at least two neutralizing and stirring tanks which are sequentially connected in series behind the tubular reactor and are used for receiving the calcium ammonium nitrate solution generated by the reaction of the tubular reactor, introducing gas ammonia and adjusting the pH value of the calcium ammonium nitrate solution to about 5;
an evaporator for receiving the calcium ammonium nitrate solution from the neutralizing and stirring tank and evaporating the calcium ammonium nitrate solution into a vapor-liquid mixture;
a preheater installed before the evaporator for heating the calcium ammonium nitrate solution;
an evaporation separator for receiving the vapor-liquid mixture from the evaporator and performing expansion flash evaporation to realize gas-liquid separation under negative pressure;
a granulation feeding groove for collecting the evaporation end liquid collected at the bottom of the evaporation separator to form the granulation slurry;
a condenser for cooling and recovering the evaporation gas generated by the evaporation separator;
a rotary drum fluidized bed granulator, wherein slurry, atomizing air, ammonium calcium nitrate crystal seeds and fluidizing gas simultaneously enter the rotary drum fluidized bed granulator for coating and granulation;
a screening device which comprises a bucket elevator arranged at the discharge port of the rotary drum fluidized bed granulator and a double-layer vibrating screen positioned behind the bucket elevator and is used for screening out calcium ammonium nitrate granules with qualified granularity;
a drum fluidized bed cooler, wherein the screened qualified granularity calcium ammonium nitrate granules enter the drum fluidized bed cooler to be cooled to obtain a product;
a roller crusher for crushing the large granular calcium ammonium nitrate sieved by the double-layer vibrating mesh screen; and
and the return channel is used for feeding the crushed large-particle calcium ammonium nitrate and the small-particle calcium ammonium nitrate back to the rotary drum fluidized bed granulator together.
10. The apparatus of claim 9, further comprising:
and the super gravity dust remover is used for recovering and removing dust from granulation waste gas generated by the rotary drum fluidized bed granulator and the rotary drum fluidized bed cooler.
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| CN101269997B (en) * | 2008-05-08 | 2012-02-08 | 爱沃(北京)农业技术有限公司 | Water-soluble calcareous fertilizer and preparation method thereof |
| CN101348401B (en) * | 2008-09-03 | 2011-07-13 | 山西省交城红星化工有限公司 | Preparation of calcium ammonium nitrate coated fertilizer |
| CN101565330B (en) * | 2009-06-01 | 2012-05-23 | 中国-阿拉伯化肥有限公司 | Method for producing potassium nitrate from nitric acid phosphate fertilizer by-product calcium nitrate |
| CN103121870A (en) * | 2011-11-21 | 2013-05-29 | 山西省交城红星化工有限公司 | Preparation technology of zeolite nitrate fertilizer |
| CN102924128B (en) * | 2012-07-04 | 2014-09-10 | 天脊煤化工集团股份有限公司 | Neutralization apparatus for nitric phosphate fertilizer production mother liquid ammonia neutralization process |
| CN103936466B (en) * | 2014-04-29 | 2016-01-13 | 天脊煤化工集团股份有限公司 | A kind of method and device producing calcium ammonium nitrate |
| CN109422549A (en) * | 2017-08-29 | 2019-03-05 | 贵州芭田生态工程有限公司 | Calcium ammonium nitrate particle preparation system and preparation method |
| CN107892310B (en) * | 2017-12-12 | 2023-10-24 | 天脊煤化工集团股份有限公司 | System and process for preventing porous ammonium nitrate from caking |
| CN112939632B (en) * | 2021-01-19 | 2022-12-02 | 宁夏润安微肥科技有限公司 | Calcium ammonium nitrate production system |
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