|Title of Invention||
"METHOD FOR PRODUCING NITROGENOUS-POTASH FERTILIZER"
|Abstract||The invention relates to the methods for producing nitrogenous-potash fertilizers based on carbamide and potassium chloride. The method consists in the following: potassium chloride is mixed with carbide in a blender, the mixture heated and granulated. For mixing 1.66-9.9 mass % of potassium chloride is chosen of and carbamide is fed into the blender in the form of a fusion cake. Granulation is performed by means of prilling in the gas flow inside a granulation tower. The nitrogenous-potash fertilizer produced in this way comprises K20 1-5.94 mass % and N 41.4-45.2 mass %.|
|Full Text||Pertinent art
This invention relates to the methods for producing nitrogenous-potash granulated fertilizers based on carbamide and potassium chloride and can be used in chemical industry.
State of art
There is a known method of producing granulated nitrogenous-potash fertilizers by means of mixing pulverized potassium chloride with 15-18 mass % of carbamide followed by water-free granulation of the mixture in a plate granulator at 116 - 180 °C and cooling the produced granules by air (SU 966087, C 05 D 1/02, 1982).
The main disadvantage of this method is rather high hygroscopic property of the product.
There is a known method of producing granulated nitrogenous-potash fertilizers wherein the obtained carbamide granules during cooling are powdered by pulverized potassium chloride at a temperature of carbamide granules fed for cooling (115-125 °C) for the purpose of reducing the granulated product hygroscopic property (SU 1084262, C 05
D 1/02, 1984). 10 - 12 mass % of the pulverized potassium chloride is fed for powdering. The main disadvantage of this method is its reduced operating reliability since a repeated granulation (cooling) of the granules results in accumulation of potassium chloride on the granulator plate and in interruption of the process.
There is also a known method of producing granulated nitrogenous-potash fertilizers which comprises producing the mixture of potassium chloride and carbamide and/or ammonium nitrate, granulation of the mixture, carbamide and/or ammonium nitrate proportion of the finished product being 10-50 mass %, which in terms of N makes up 4.6 - 23.0 mass % of N for carbamide (FR 1476296, C 05 D 1/02, 1966).
Granulation is performed in a granulating and drying drum. The main disadvantage of the method is that the produced granulated nitrogenous-potash fertilizer has insufficient nitrogen content, and granules have non-uniform composition by volume.
There is also a known method of producing nitrogenous-potash fertilizer, which comprises mixing of carbamide with potassium chloride, heating of the mixture to carbamide fusion and granulation of fertilizer (RU 2100326, C 05 D 1/00, 1997). In the known method 35-90% of carbamide is taken. The fertilizer granules produced by the known method have an increased strength. However the used granulation method, which consists in cooling of the heated mixture on a cooled metal surface, requires an additional stage of grinding the formed cake to granules with the average size of 1-4 mm. This impairs the reliability and, hence, output of the method.
The most similar to this invention by technical essence and by an accomplished effect is the method of producing nitrogenous-potash fertilizer, which consists in mixing of potassium chloride with carbamide in a blender, heating of the mixture and its granulation (SU 347324, C 05 D 1/02, 1972). In the known method carbamide is taken in the amount of 10 - 30 mass %, which in terms of N makes up 4.6 - 13.8 mass % of N. K20 content is 42.0 - 54.0 mass %.
The main disadvantage of the method being the closest counterpart is its impaired operating reliability (see definition of the term "reliability"
according to GOST and its characteristics in Table represented at the end of this description) due to the increased number of failures of the plant wherein the known method is realized.
Another disadvantage of the method being the closest counterpart is rather high potassium content of the produced fertilizer, which hampers the granulation and also impairs the operating reliability of the method.
The main technical task aimed at by this invention is improvement of the operating reliability of the method through cutting down the time of delays due to failures, increasing the time between failures, which both provide an increase in the method output.
The technical effect of the invention is increasing the time between failures of the equipment wherein the method is realized and producing a fertilizer with K20 mass % of 1 to 5.94.
The above-said task, with technical effect being achieved, is accomplished in the method of producing nitrogenous-potash fertilizer, which comprises mixing of potassium chloride with carbamide in the blender, heating of the mixture and its granulation, for mixing 1.66-9.9 mass % of potassium chloride being chosen, carbamide being fed into the blender in the form of a fusion cake, granulation being performed by prilling in the gas flow inside the granulation tower.
Furthermore, the fertilizer granules are collected from the above-said gas flow by liquid jets.
Further, a ratio between a velocity head of each liquid jet and a velocity head of gas flow is maintained within the range of 3650 to 9980.
A variation of the invention is possible, when an aqueous solution of the produced fertilizer is used as the liquid.
Furthermore, the mass ratio of potassium in the aqueous solution and in the gas flow is maintained within 22-250.
The nitrogenous-potash fertilizer produced by this method contains K20 1-5.94 mass %, N 41.4 - 45.2 mass %.
The main distinctive features of the proposed method consist in the fact that 1.66 - 9.9 mass % of potassium chloride is chosen for mixing, carbamide is fed into the blender in the form of a fusion cake, and granulation is performed by means of prilling.
Additional distinctive features of the proposed method consist in the following: the produced fertilizer granules are collected from the gas flow by liquid jets, preferably by the aqueous solution of the produced fertilizer. The ratio between a velocity head of each liquid jet and that of gas flow is maintained within the range of 3650 to 9980, and the mass ratio of potassium in aqueous solution of the fertilizer and in the gas flow is maintained within the range of 22 to 250. By velocity head is meant the ratio of W p/2 where W and p are flow velocity and flow density, respectively.
This invention satisfies the condition for patentability as to novelty, since in the prior art there is no engineering solution, whose essential features are in complete coincidence with all features contained in the independent claim of the invention. The invention also satisfies the condition for patentability as to an inventive level, since the engineering solutions, whose distinctive features are aimed at solution of the technical problem aimed at by this invention have not been found out in the prior art.
The embodiment of the invention
An essence of the present invention is explained in terms of the following example.
99.7 - 99.8 mass % of carbamide in the form of a fusion cake and potassium chloride powder are fed into the blender at a rate of 54.1 to 59 t/h and 1 to 5.94 t/h respectively at 132 - 140 °C. Potassium chloride concentration of the mixture is 1.66 - 9.9 mass percent. Granulation is performed by means of prilling. For this purpose the mixture is fed into the granulating tower, which has a diameter of 10960 mm and a height of 68 m. A height of flying of the granules is 62 m. 530 000 to 600 000 m3/h of air are supplied into a tower from the bottom. The produced nitrogenous-potash fertilizer has the following composition (mass %): K20 1 - 5.94, N 45.2 - 41.4, H20 no more than 0.25. This fertilizer has no less than 93% of granules with a size of 1 - 4 mm, up to 5% of granules with a size below 1 mm. The average hourly output is 60 t/h.
After the granulation the fertilizer particles are collected from the gas flow by jets of the fertilizer aqueous solution. The collection is performed in 40 cleaners evenly spaced in the outer annular jacket mounted around the tower top. Each cleaner represents a pipe with an inside diameter of 750 mm and a height of 1250 m. At the top of a pipe there is a nozzle, which supplies radial jets of fertilizer aqueous solution, directed perpendicular to the pipe axis. An inside diameter of the nozzle outlet is 14 mm. The gas flow (the air) containing the fertilizer particles enters the annular jacket through the ports made at the top of the tower. Then it is distributed over the pipes wherein it flows from top to bottom. When the gas flow comes in contact with radial jets of the fertilizer aqueous solution, an efficient cleaning of the gas flow from fertilizer particles takes place. The cleaned gas flow is discharged into the atmosphere.
The ratio between a velocity head of the jet and a velocity head of the gas flow is taken to be 3650 - 9980. A rate of circulating aqueous solution of the fertilizer is 600 m /h.
The mass ratio of potassium in the aqueous solution and in the gas flow is chosen to be within the range of 22 - 250.
Operating characteristics of the proposed method and those of the closest counterpart are shown in Table.
It should be noted that, when the concentration of potassium chloride KC1 is beyond the range specified in the first claim of the invention, the operating characteristics of the method reliability are essentially impaired. The experimental studies carried out by the authors have shown that with upper limit of KC1 concentration being exceeded, two undesirable phenomena occur. In the first place, the frequency of clogging of powder dispenser distributing a fusion cake of the fertilizer at the top of the tower increases. In the second place, the efficiency of gas flow cleaning from fertilizer particles essentially decreases, which results in more frequent clogging of outlet pipes discharging the gas flow from the jacket.
Hence the plant has to be stopped for cleaning more frequently. When the concentration of KC1 falls below the lower limit, an off-grade fertilizer is obtained. It has a reduced potassium content, namely, in terms of K2O the potassium content is below the required limit of 1 mass %. Similar undesirable phenomena also occur when the ratio between the velocity head of the jet and that of the gas flow is maintained below the lower limit, and when the mass ratio between potassium in the aqueous fertilizer solution and in the gas flow is maintained above the upper limit. When upper limit of the parameter as claimed in claim 3 is exceeded, and when the parameter as claimed in claim 4 are maintained below the lower limit, the method reliability goes down since for providing these conditions in the plant it is necessary to increase the pumping capacity or to increase the number of pumps, which perform circulation of the aqueous fertilizer solution fed for removal of fertilizer particles from the gas flow. In practice this results in impairment of the plant reliability due to the increase in the number of failures.
As it follows from the Table, the proposed method makes it possible to increase the mean time between failures 1.92 times, to reduce the number of failures 1.75 times, to cut down the mean time to restore 1.81 times. As a result, the total time of delays due to failures decreases 3.18 times. The average hourly output of the process increases 1.14 times.
The invention can be used most efficiently in chemical industry for producing granulated nitrogenous-potash fertilizers.
1 A method for producing nitrogen-potash fertilizer comprising:
mixing potassium chloride with carbamide, in a blender, said carbamide is in the form of fusion cake and the potassium chloride concentration of the mixture is 1.66-9.9 mass percentage; heating said mixture; and
granulating by means of prilling in the gas flow inside the granulation chamber to obtain nitrogen potash fertilizer.
2. The method for producing nitrogen-potash fertilizer as claimed in claim 1 wherein the produced fertilizer granules are collected from the above said gas flow by liquid jets.
3. The method for producing nitrogen-potash fertilizer as claimed in claims 1 or 2 wherein the ratio between a velocity head of each jet of liquid and that of the gas flow is maintained within the range of 3650-9980.
4. The method for producing nitrogen-potash fertilizer as claimed in claims 1 or 2 wherein the aqueous solution of the produced fertilizer is used as liquid.
5. The method for producing nitrogen-potash fertilizer as claimed in claims 1 & 4 wherein the mass ratio of potassium in the aqueous solution and in gas flow is maintained within the range of 22-250.
6. Nitrogen-potash fertilizer produced in accordance with the method as claimed in claims 1 -5.
7. Nitrogen-potash fertilizer produced as claimed in claim 6 which contains K20 1-5.94 mass percentage and N 41.4-45.2 mass percentage
8. A method for producing nitrogen-potash fertilizer substantially as herein described.
|Indian Patent Application Number||IN/PCT/2002/00696/DEL|
|PG Journal Number||03/2011|
|Date of Filing||12-Jul-2002|
|Name of Patentee||INTERNATIONAL VTI GROUP HOLDING BV|
|Applicant Address||VAN DE SPIEGELSTRAAT 9, 2518ES THE HAUGE, THE NETHTERLANDS|
|PCT International Classification Number||C05B 7/00|
|PCT International Application Number||PCT/RU00/00540|
|PCT International Filing date||2000-12-29|