CA1141143A - Process for condensing solids and apparatus for carrying out said process - Google Patents
Process for condensing solids and apparatus for carrying out said processInfo
- Publication number
- CA1141143A CA1141143A CA000345778A CA345778A CA1141143A CA 1141143 A CA1141143 A CA 1141143A CA 000345778 A CA000345778 A CA 000345778A CA 345778 A CA345778 A CA 345778A CA 1141143 A CA1141143 A CA 1141143A
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- CA
- Canada
- Prior art keywords
- reactor
- process according
- heating
- condensed
- housing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/38—Condensed phosphates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J10/00—Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor
- B01J10/005—Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor carried out at high temperatures in the presence of a molten material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/18—Stationary reactors having moving elements inside
- B01J19/1887—Stationary reactors having moving elements inside forming a thin film
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/38—Condensed phosphates
- C01B25/40—Polyphosphates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/18—Details relating to the spatial orientation of the reactor
- B01J2219/182—Details relating to the spatial orientation of the reactor horizontal
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a process for condensing solids, which tend to sinter and/or coalesce during the condensa-tion, in a reactor while supplying heat in which the contents of the reactor are mixed and pressed against the reactor wall in a thin layer and the condensed hard layer so obtained is peeled off the reactor wall and returned to the inside of the reactor.
The present invention provides a process for condensing solids, which tend to sinter and/or coalesce during the condensa-tion, in a reactor while supplying heat in which the contents of the reactor are mixed and pressed against the reactor wall in a thin layer and the condensed hard layer so obtained is peeled off the reactor wall and returned to the inside of the reactor.
Description
The present inven-tlon relates to a process for condens-ing solids, particularly phosphates which tend to sinter and/or coalesce during condensation, in a xeactor while supplying heat, and an apparatus for use in said process.
Processes of this type are, for example, the condensa-tion of acid alkali, alkaline earth or heavy metal monophosphates or ammonium metal monophosphates to the corresponding polyphos-phates, as for example, the condensation of monosodium monophos-phate to disodium diphosphate and further to Maddrell salt or trimetaphosphate, the condensation of disodium monophosphate to tetrasodium diphosphatç, the condensation of lithium-monophos-phates to the corresponding di- and polyphosphates, and the con-densation of monocalcium and monomagnesium monophosphates via the diphosphates to the corresponding polyphosphates.
Examples of the reaction of heavy metal monophosphates include (a) the production of alumlnium tripolyphosphate or aluminium metaphosphate from aluminium monophosphate and (b) the condensation of zinc, manganese or copper diphosphate from the correspondin~ monophosphates. Further examples include the pro-duction of boron phosphate by condensation of boric acid with ammonium phosphate and the formation of ammonium polyphosphate from urea phosphate or the product.ion of melamine polyphosphates.
The coalescing of the products also causes considerable difficulties in the condensation of urea to cyanuric acid and in the formation of phosphorus nitride oxide or phosphorus nitride sulphide. These difficulties lie in that the final product adhering to the reactor wall inhibits heat transfer and thus decisively affects the degree of reaction.
German Offenlegungsschrift 1,~42,016 discloses a method and an apparatus for carrying out high-temperature pro-cesses at temperatures above 300C.
In this method the starting product is heated, in a screw extruder having one or several screw shafts, primarily by mechanical internal frictional work to such an extent that it is converted via a viscous-pasty state into a less viscous mass, to which the required heat is supplied externally by direct heat transfer. This apparatus is generally unsuitable for carrying out condensation reactions since the mixing effect is too small and the reaction thus is incomplete.
Furthermore, German Offenlegunysschrift 1,557,119 and 2,012,294 discloses mixing machineshaving cylindrical or trough-shaped housings fitted with mixers as well as with kneading bars and/or disc-shaped mixing elements. Only processes in which a temperature of approximately 350C is not exceeded can be carried out in these mixing machines.
In contrast thereto, by means of the process according to the invention and with the apparatus according to the invention condensations can be carried out at temperatures of up to approx-imately 700C when the reactor contents are pressed against the reactor wall in a thin layer after the mixing and the condensed (hard) layer is then detached from the reactor wall and returned to the inside.
According to the present invention therefore there is provided a process for condensing solids, which tend to sinter and/or coalesce during the condensation, in a reactor while supplying heat in which the contents of the reactor are mixed and pressed against the reactor wall in a thin layer and the condensed hard layer so obtained is peeled off the reactor wall and returned to the inside of the reactor.
The present invention also provides an apparatus for condensing solids, whibh tend to sinter and/or coalesce during the condensation, in a reactor while supplying heat, said appara-tus comprising a heatable reactor housing having an internal star-shaped mixing tool with paddles, at least one paddle being a peeling knife disposed at a small interval from the wall of the reactor housing.
In the process of the present invention a salt or metallic melt is suitably used for the heat transfer, the haat being supplied to the condensed layer through the reactor wall by means of the melt. I'he heat is then returned to the inside of the reactor by peeling off this condensed la~er.
, 10 ., . ~
- 2a -When using a reactor provided with several heating pockets, it is possible to apply without any difficulty, differ-ent temperatures over the length of the reactor.
The reaction waste gases formed during the condensa-tion can be drawn off by suction and diluted with air. The reaction product carried along in the waste gases is separated and, when required, returned to the reactor.
The present invention will be further illustrated by way of the accompanying drawings in which:
Fig. 1 is a lateral view partially in longitudinal section of an apparatus for use in the process according to one embodiment of the present invention;
Fig. 2 is a plan view of the feed side of the apparatus of Fig. l; and Fig. 3 is à cross section-through the apparatus of Fig. 1.
Referring to the drawings, the apparatus comprises a reactor housing 1, which is trough-shaped and is suspended on cross bars 14 so as to be movable in the longitudinal direction, the crossbars 14 abutting against longitudinal bars 13 via friction bearings 15.
The reactor housing 1 comprises a rotary shaft 2 and paddles 3 on paddle supports 4 are secured to the shaft 2 in several planes. The paddles 3 are inclined with respect to the axis of the shaft 2 and thus cause the product in the reac-tor trough 1 to be conveyed axially. The upper end of the reactor housing 1 is provided with covers la. ~ stripper clamp 5, which cleans the shaft 2 and the paddle supports 4 from adhering product, is secured to the covers between two paddle planes.
An inlet 6 is provided for introducing the reaction components. The outlet 7 serves for discharging the reaction product. The shaft 2 is scaled with respect to the front-end , .
housing covers 9 by means of the stuffing boxes 10.
A paddle 3 with a knife 11 mounted thereon is disposed in each paddle plane. The knife 11 is used to peel off the con-densed layer from the reactor wall. An optimum heat transfer from the heating surface to the product is thus attained. The paddle knives 11 are so designed that only a minimum expenditure of energy is required for the cleansing process due to both the peeling action and the cutting effect.
Multiple-section heating pockets 12 are attached to the reactor housing l and are adapted to be charged with heating media having different temperatures. The heating pockets can also compensate for the variations of the thermal expansions of the reactor housing 1 and of the walls of the heating pockets 12.
For the absorption of the torsional forces of the reactor housing 1 abutments 16 consisting of two parts 16a and 16b are disposed on the bottom side of the housing 1, one part (16a) being secured -to the housing 1 and the other part ~16b) being secured tothe trough support strcture 16. The twoparts 16a and 16b are slidable towards each other in the longitudinal direction.
When carrying out the process the substance to be condensed is fed via the inlet 6 into the reactor housing 1 by means of a feed screw, conveyor belt or celled wheel gate. Care must be taken that the filling level of the reactor housing 1 is fully utilized corresponding to the prQduct concerned. Thus, for example, in the case of products having a strong tendency to foam it would be desirable to select a-filling height which extends only slightly above the shaft 2. The filling height is regulated by means of a dam 8 disposed in front of the outlet and by varying the speed of the shaft 2 or by varying the inclination of the paddles. In the first phase the material in the reactor housing 1 is pressed, in a thin layer, against the reactor housing wall, which is heated externally with hot molten salt.
.'13 By means of the peeling knife 11 ~ollowing in the paddle plane concerned the heated and partially condensed material is scraped off the walls of the reactor housin~ 1 and is mixed with the produc-t inside the reactor while heat is simultaneously trans-~erred by thepeeled material from the heated reactor wall to the inside.
The quantity of product fed in is so rated that this step is repeated until the reaction product in the last section in front of the outlet 7 has the reaction temperature at which the condensation is complete. The final product thus obtained is conveyed via the dam 8 to the outlet 7, from where it is dis-charged.
When carrying out the kind of reactions in which the temperature should be ~ariable during the reaction the heating jacket is divided into sectors, i.e., so-callea heating pockets, which can be charged with heating materials having different temperatures, so the temperature gradient can be adjusted.
The present invention will be further illustrated by ~ay of the following Examples.
~xample 1 A reactor according to the accompanying drawings which has a trough length of 320 cm is charged in one hour with 70 to 75 kg of a mixture consisting of 98.8 parts by weight of crystal-lized or spray-dried monosodium phosphate and 1.2 paxts of mono-ammonium phosphate. A 1% solutlon of the monosodium phosphate should have a pH value of 4.5. When maintaining the temperatuxe of the product :in the outlet at 355 to 3Ç0C which requires a temperature of 450 to 470C for the salt melt, a sodium poly-phosphate containing at least 98.5% of Maddxell salt is obtained.
A capacity of 300 to 320 kg perhour is attained with a reactox whose trough has a length of 600 cm and a diameter of 70 cm.
Example 2 100 parts by weight of monosodium phosphate are thoroughly mixed with 1.5 parts by weight of sodium carbonate in a mixer. This premixture is continuously fed at a rate of 60 kg per hour via a proportioning chute and a feed screw or celled wheel gate into a reactor according -to the accompanying drawings which has a trough length of 320 cm. At salt-melt temperatures of 470 to 520C the temperatures of the product are between 380 and 440C. A sodium trimetaphosphate containing between 0.5 and 2~ of components insoluble in water, as measured in a 5~ sus-pension, is obtained. Traces of pentasodium tripolyphosphate could also be detected.
Example 3 ~ .
The reactor of the accompanying drawings is charged per ;~ hour with 30.6 kg of calcium hydroxide via a dosing feeder, for example, a conveyor-type weigh feeder, and with 66 litres of a 75% phosphoric acid via a spray device above the kneader shaft.
At a salt-melt temperature of 520C the temperature of the product at the outlet of the reactor is 280 -to 290C. A calcium pyrophos-pate showing a loss on ignition of 8.8% is obtained at a rate of 90 kg per hour.
Example 4 A laboratory reactor of the type of the accompanying drawings having a trough length of 80 cm and trough diameter of 18 cm is charged with 10 kg of monolithium ortho-phosphate at 150C.
After increasing the temperature of the heating medium to 400-420C, 6 to 7 kg of a lithium-ortho-phosphate solution produced from lithium hydroxide and a 75~ phosphoric acid are fed per hour by means of a dosing pump via a nozzle tube into the front end of the reactor. The lithium polyphosphate formed which is sparingly soluble in water leaves the reactor as a fluid product at a temperature of 320 to 350C.
.. ~ ' ~, .
~ :~ll L~ 3 Example 5 A mix-ture of 44.6~ of dicyanogen diamide, 37.7~ of phosphorus pentoxide and 17% o~ urea is produced, while excluding moisture. The reactor described in Example 1 is charged with 55 to 60 kg of this mixture perhour while excluding moisture.
At the same -time the hea~ing jacket of the reactor is kept at a : temperature of 250 to 260C at the feed side in the first third while the.other two thirds are charged with a heating medium having a temperature of 420 to 460C. A PNC compound, which is particularly suitable for rendering thermoplastic molding compounds such as polyamide, fire-retarding according to German Offenlegungs-schrift No~ 2,647,120, is obtained.
Example 6 5 kg of a mixture consisting of 35% by weight of boric acid and 65~ by weight of ammonium ortho-phosphate are fed per hour into a laboratory reactor (trough length 80 cm) whose heating jacket is kept in the front end at a temperature of 250C and in the rear end at the outlet at a temperature of 500C. The boron phosphate formed leaves the reactor at a temperature of 410 to 420C and has a water-soluble component below 2~. When using a larger reactor like that described in Example l`the production of a premixture can be dispensed with and boric acid and monoammonium phosphate, in a ratio by weight of 30:65 can be fed in simultan-eously via separate dosing feeders. The quantity which can be put through per hour i~ approximately 60 kg.
Example 7 For the productionof cyanuric acid the reactor des-cribed in Example 1 is used, its heating jacket is divided into three zones. Zone 1 at the inlet is kept at 160C and zone 2 at 260C. Zone 3 is charged with a salt melt at 360C. Along the cover there are provided four outlets through which ammonia formed during the condensation is drawn off and is passed on to a wet washer for absorption. The reactor is charged with urea in a quantity of 80 ]~ per hour. A speed of 12 r.p.m. is set at the shaft. The condensation product leaves the reactor at a tempera-ture of 290 to 305C and contains 97.6% of cyanuric acid.
Example 8 42.05 kg of melamine per hour are fed per hour via a screw into the reactor having a trough length of 320 cm and whose jacket is charged with a salt melt having a temperature of 340 to 370C. At the same time 43.55 kg of a 75% phosphoric acid per hour are fed in by means of a piston pump via a pipe having four nozzles. The water vapour formed leaves the reactor via two gas outlet pipes. The hea-ting temperature must be so adjusted that the melamine diphosphate formed has a temperature of 265 to 275C
prior to leaving the reactor.
For the production of the melamine polyphosphate the melamine diphosphate is condensed with urea in a second step of the reaction. For this purpose the reactor is kept at a jacket temperature of180C in the first third while the restof theheating jacket ischarged with a saltmelt, which has a temperature of380C
during the condensation. A mixture of 107 kg of melamine diphos-phate and 15.5 kg of urea are fed in per hour by means of a pro-portioning chute. The speed of the reactor shaft should be 10 12 r,p.m, Example 9 The reactor described in Example 1 which is heated with a salt melthaving a forerun temperature of 440C, is filled with 120kg of aluminium tripolyphosphate. As soon as the filling reaches a temperature of 380C an aluminium ortho-phosphate solution, which has a temperature of 80 to 90C and is produced from aluminium oxide hydrate and a 75% phosphoric acid at 80 to 90C is sprayedin.
The ortho-phosphate solution fed-in via a piston pump is so pro-portioned that the temperature of the product at the outlet is 370 to 380C. ~t 600C the aluminium phosphate obtained showed a loss on ignition of 6.5%.
Aluminium metaphosphate is produced in a similar manner, but the heating temperature is adjusted to 540~ and the tempera~
ture of the product to 460C.
Example_lO
At a heating-bath temperature of 160C and a shaft speed of 12 r.p.m. the laboratory reactor is slowly filled with 3.25 kg of zinc oxide while simultaneously adding 10.45 kg of a 75% phos-phoric acid. The temperature of the heating medium in the zone facing the inlet is then increased to 250C and that of the fuel in the two zones facing the outlet to 450C, whereupon 6 to 8 kg of a solution of zinc ortho~phosphate Zn(H2PO4)2 obtained by feeding zinc oxide into a hot 75% phosphoric acid, are added.
The first 15 kg of zinc polyphosphate lea~ing the reactor are stirred into a paste with twice the quantity of zinc ortho-phos~
phate solution and also fed into the reactor. Of course, for the first filling the reactor can alsobe charged with 10 kg of zinc polyphosphate and the zinc-polyphosphate solution can be pumped in thereafter.
. ~ 9
Processes of this type are, for example, the condensa-tion of acid alkali, alkaline earth or heavy metal monophosphates or ammonium metal monophosphates to the corresponding polyphos-phates, as for example, the condensation of monosodium monophos-phate to disodium diphosphate and further to Maddrell salt or trimetaphosphate, the condensation of disodium monophosphate to tetrasodium diphosphatç, the condensation of lithium-monophos-phates to the corresponding di- and polyphosphates, and the con-densation of monocalcium and monomagnesium monophosphates via the diphosphates to the corresponding polyphosphates.
Examples of the reaction of heavy metal monophosphates include (a) the production of alumlnium tripolyphosphate or aluminium metaphosphate from aluminium monophosphate and (b) the condensation of zinc, manganese or copper diphosphate from the correspondin~ monophosphates. Further examples include the pro-duction of boron phosphate by condensation of boric acid with ammonium phosphate and the formation of ammonium polyphosphate from urea phosphate or the product.ion of melamine polyphosphates.
The coalescing of the products also causes considerable difficulties in the condensation of urea to cyanuric acid and in the formation of phosphorus nitride oxide or phosphorus nitride sulphide. These difficulties lie in that the final product adhering to the reactor wall inhibits heat transfer and thus decisively affects the degree of reaction.
German Offenlegungsschrift 1,~42,016 discloses a method and an apparatus for carrying out high-temperature pro-cesses at temperatures above 300C.
In this method the starting product is heated, in a screw extruder having one or several screw shafts, primarily by mechanical internal frictional work to such an extent that it is converted via a viscous-pasty state into a less viscous mass, to which the required heat is supplied externally by direct heat transfer. This apparatus is generally unsuitable for carrying out condensation reactions since the mixing effect is too small and the reaction thus is incomplete.
Furthermore, German Offenlegunysschrift 1,557,119 and 2,012,294 discloses mixing machineshaving cylindrical or trough-shaped housings fitted with mixers as well as with kneading bars and/or disc-shaped mixing elements. Only processes in which a temperature of approximately 350C is not exceeded can be carried out in these mixing machines.
In contrast thereto, by means of the process according to the invention and with the apparatus according to the invention condensations can be carried out at temperatures of up to approx-imately 700C when the reactor contents are pressed against the reactor wall in a thin layer after the mixing and the condensed (hard) layer is then detached from the reactor wall and returned to the inside.
According to the present invention therefore there is provided a process for condensing solids, which tend to sinter and/or coalesce during the condensation, in a reactor while supplying heat in which the contents of the reactor are mixed and pressed against the reactor wall in a thin layer and the condensed hard layer so obtained is peeled off the reactor wall and returned to the inside of the reactor.
The present invention also provides an apparatus for condensing solids, whibh tend to sinter and/or coalesce during the condensation, in a reactor while supplying heat, said appara-tus comprising a heatable reactor housing having an internal star-shaped mixing tool with paddles, at least one paddle being a peeling knife disposed at a small interval from the wall of the reactor housing.
In the process of the present invention a salt or metallic melt is suitably used for the heat transfer, the haat being supplied to the condensed layer through the reactor wall by means of the melt. I'he heat is then returned to the inside of the reactor by peeling off this condensed la~er.
, 10 ., . ~
- 2a -When using a reactor provided with several heating pockets, it is possible to apply without any difficulty, differ-ent temperatures over the length of the reactor.
The reaction waste gases formed during the condensa-tion can be drawn off by suction and diluted with air. The reaction product carried along in the waste gases is separated and, when required, returned to the reactor.
The present invention will be further illustrated by way of the accompanying drawings in which:
Fig. 1 is a lateral view partially in longitudinal section of an apparatus for use in the process according to one embodiment of the present invention;
Fig. 2 is a plan view of the feed side of the apparatus of Fig. l; and Fig. 3 is à cross section-through the apparatus of Fig. 1.
Referring to the drawings, the apparatus comprises a reactor housing 1, which is trough-shaped and is suspended on cross bars 14 so as to be movable in the longitudinal direction, the crossbars 14 abutting against longitudinal bars 13 via friction bearings 15.
The reactor housing 1 comprises a rotary shaft 2 and paddles 3 on paddle supports 4 are secured to the shaft 2 in several planes. The paddles 3 are inclined with respect to the axis of the shaft 2 and thus cause the product in the reac-tor trough 1 to be conveyed axially. The upper end of the reactor housing 1 is provided with covers la. ~ stripper clamp 5, which cleans the shaft 2 and the paddle supports 4 from adhering product, is secured to the covers between two paddle planes.
An inlet 6 is provided for introducing the reaction components. The outlet 7 serves for discharging the reaction product. The shaft 2 is scaled with respect to the front-end , .
housing covers 9 by means of the stuffing boxes 10.
A paddle 3 with a knife 11 mounted thereon is disposed in each paddle plane. The knife 11 is used to peel off the con-densed layer from the reactor wall. An optimum heat transfer from the heating surface to the product is thus attained. The paddle knives 11 are so designed that only a minimum expenditure of energy is required for the cleansing process due to both the peeling action and the cutting effect.
Multiple-section heating pockets 12 are attached to the reactor housing l and are adapted to be charged with heating media having different temperatures. The heating pockets can also compensate for the variations of the thermal expansions of the reactor housing 1 and of the walls of the heating pockets 12.
For the absorption of the torsional forces of the reactor housing 1 abutments 16 consisting of two parts 16a and 16b are disposed on the bottom side of the housing 1, one part (16a) being secured -to the housing 1 and the other part ~16b) being secured tothe trough support strcture 16. The twoparts 16a and 16b are slidable towards each other in the longitudinal direction.
When carrying out the process the substance to be condensed is fed via the inlet 6 into the reactor housing 1 by means of a feed screw, conveyor belt or celled wheel gate. Care must be taken that the filling level of the reactor housing 1 is fully utilized corresponding to the prQduct concerned. Thus, for example, in the case of products having a strong tendency to foam it would be desirable to select a-filling height which extends only slightly above the shaft 2. The filling height is regulated by means of a dam 8 disposed in front of the outlet and by varying the speed of the shaft 2 or by varying the inclination of the paddles. In the first phase the material in the reactor housing 1 is pressed, in a thin layer, against the reactor housing wall, which is heated externally with hot molten salt.
.'13 By means of the peeling knife 11 ~ollowing in the paddle plane concerned the heated and partially condensed material is scraped off the walls of the reactor housin~ 1 and is mixed with the produc-t inside the reactor while heat is simultaneously trans-~erred by thepeeled material from the heated reactor wall to the inside.
The quantity of product fed in is so rated that this step is repeated until the reaction product in the last section in front of the outlet 7 has the reaction temperature at which the condensation is complete. The final product thus obtained is conveyed via the dam 8 to the outlet 7, from where it is dis-charged.
When carrying out the kind of reactions in which the temperature should be ~ariable during the reaction the heating jacket is divided into sectors, i.e., so-callea heating pockets, which can be charged with heating materials having different temperatures, so the temperature gradient can be adjusted.
The present invention will be further illustrated by ~ay of the following Examples.
~xample 1 A reactor according to the accompanying drawings which has a trough length of 320 cm is charged in one hour with 70 to 75 kg of a mixture consisting of 98.8 parts by weight of crystal-lized or spray-dried monosodium phosphate and 1.2 paxts of mono-ammonium phosphate. A 1% solutlon of the monosodium phosphate should have a pH value of 4.5. When maintaining the temperatuxe of the product :in the outlet at 355 to 3Ç0C which requires a temperature of 450 to 470C for the salt melt, a sodium poly-phosphate containing at least 98.5% of Maddxell salt is obtained.
A capacity of 300 to 320 kg perhour is attained with a reactox whose trough has a length of 600 cm and a diameter of 70 cm.
Example 2 100 parts by weight of monosodium phosphate are thoroughly mixed with 1.5 parts by weight of sodium carbonate in a mixer. This premixture is continuously fed at a rate of 60 kg per hour via a proportioning chute and a feed screw or celled wheel gate into a reactor according -to the accompanying drawings which has a trough length of 320 cm. At salt-melt temperatures of 470 to 520C the temperatures of the product are between 380 and 440C. A sodium trimetaphosphate containing between 0.5 and 2~ of components insoluble in water, as measured in a 5~ sus-pension, is obtained. Traces of pentasodium tripolyphosphate could also be detected.
Example 3 ~ .
The reactor of the accompanying drawings is charged per ;~ hour with 30.6 kg of calcium hydroxide via a dosing feeder, for example, a conveyor-type weigh feeder, and with 66 litres of a 75% phosphoric acid via a spray device above the kneader shaft.
At a salt-melt temperature of 520C the temperature of the product at the outlet of the reactor is 280 -to 290C. A calcium pyrophos-pate showing a loss on ignition of 8.8% is obtained at a rate of 90 kg per hour.
Example 4 A laboratory reactor of the type of the accompanying drawings having a trough length of 80 cm and trough diameter of 18 cm is charged with 10 kg of monolithium ortho-phosphate at 150C.
After increasing the temperature of the heating medium to 400-420C, 6 to 7 kg of a lithium-ortho-phosphate solution produced from lithium hydroxide and a 75~ phosphoric acid are fed per hour by means of a dosing pump via a nozzle tube into the front end of the reactor. The lithium polyphosphate formed which is sparingly soluble in water leaves the reactor as a fluid product at a temperature of 320 to 350C.
.. ~ ' ~, .
~ :~ll L~ 3 Example 5 A mix-ture of 44.6~ of dicyanogen diamide, 37.7~ of phosphorus pentoxide and 17% o~ urea is produced, while excluding moisture. The reactor described in Example 1 is charged with 55 to 60 kg of this mixture perhour while excluding moisture.
At the same -time the hea~ing jacket of the reactor is kept at a : temperature of 250 to 260C at the feed side in the first third while the.other two thirds are charged with a heating medium having a temperature of 420 to 460C. A PNC compound, which is particularly suitable for rendering thermoplastic molding compounds such as polyamide, fire-retarding according to German Offenlegungs-schrift No~ 2,647,120, is obtained.
Example 6 5 kg of a mixture consisting of 35% by weight of boric acid and 65~ by weight of ammonium ortho-phosphate are fed per hour into a laboratory reactor (trough length 80 cm) whose heating jacket is kept in the front end at a temperature of 250C and in the rear end at the outlet at a temperature of 500C. The boron phosphate formed leaves the reactor at a temperature of 410 to 420C and has a water-soluble component below 2~. When using a larger reactor like that described in Example l`the production of a premixture can be dispensed with and boric acid and monoammonium phosphate, in a ratio by weight of 30:65 can be fed in simultan-eously via separate dosing feeders. The quantity which can be put through per hour i~ approximately 60 kg.
Example 7 For the productionof cyanuric acid the reactor des-cribed in Example 1 is used, its heating jacket is divided into three zones. Zone 1 at the inlet is kept at 160C and zone 2 at 260C. Zone 3 is charged with a salt melt at 360C. Along the cover there are provided four outlets through which ammonia formed during the condensation is drawn off and is passed on to a wet washer for absorption. The reactor is charged with urea in a quantity of 80 ]~ per hour. A speed of 12 r.p.m. is set at the shaft. The condensation product leaves the reactor at a tempera-ture of 290 to 305C and contains 97.6% of cyanuric acid.
Example 8 42.05 kg of melamine per hour are fed per hour via a screw into the reactor having a trough length of 320 cm and whose jacket is charged with a salt melt having a temperature of 340 to 370C. At the same time 43.55 kg of a 75% phosphoric acid per hour are fed in by means of a piston pump via a pipe having four nozzles. The water vapour formed leaves the reactor via two gas outlet pipes. The hea-ting temperature must be so adjusted that the melamine diphosphate formed has a temperature of 265 to 275C
prior to leaving the reactor.
For the production of the melamine polyphosphate the melamine diphosphate is condensed with urea in a second step of the reaction. For this purpose the reactor is kept at a jacket temperature of180C in the first third while the restof theheating jacket ischarged with a saltmelt, which has a temperature of380C
during the condensation. A mixture of 107 kg of melamine diphos-phate and 15.5 kg of urea are fed in per hour by means of a pro-portioning chute. The speed of the reactor shaft should be 10 12 r,p.m, Example 9 The reactor described in Example 1 which is heated with a salt melthaving a forerun temperature of 440C, is filled with 120kg of aluminium tripolyphosphate. As soon as the filling reaches a temperature of 380C an aluminium ortho-phosphate solution, which has a temperature of 80 to 90C and is produced from aluminium oxide hydrate and a 75% phosphoric acid at 80 to 90C is sprayedin.
The ortho-phosphate solution fed-in via a piston pump is so pro-portioned that the temperature of the product at the outlet is 370 to 380C. ~t 600C the aluminium phosphate obtained showed a loss on ignition of 6.5%.
Aluminium metaphosphate is produced in a similar manner, but the heating temperature is adjusted to 540~ and the tempera~
ture of the product to 460C.
Example_lO
At a heating-bath temperature of 160C and a shaft speed of 12 r.p.m. the laboratory reactor is slowly filled with 3.25 kg of zinc oxide while simultaneously adding 10.45 kg of a 75% phos-phoric acid. The temperature of the heating medium in the zone facing the inlet is then increased to 250C and that of the fuel in the two zones facing the outlet to 450C, whereupon 6 to 8 kg of a solution of zinc ortho~phosphate Zn(H2PO4)2 obtained by feeding zinc oxide into a hot 75% phosphoric acid, are added.
The first 15 kg of zinc polyphosphate lea~ing the reactor are stirred into a paste with twice the quantity of zinc ortho-phos~
phate solution and also fed into the reactor. Of course, for the first filling the reactor can alsobe charged with 10 kg of zinc polyphosphate and the zinc-polyphosphate solution can be pumped in thereafter.
. ~ 9
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for condensing solid materials which tend to sinter and adhere during condensation in a heated reactor, said apparatus comprising: a reactor housing having an exterior wall, means for heating the exterior wall of said reactor housing; at least one set of rotatable paddles disposed in the interior of said reactor housing for agitating solid material in said reactor housing, at least one paddle of each set being provided with blade means which passes closely adjacent the wall of said reactor hous-ing when said set of paddles is rotated for stripping sintered material from said reactor wall; duet means communicating with the interior of said reactor housing for withdrawing waste gases from said reactor housing; means for drawing waste gases through said duet means; and means for introducing atmospheric air into said waste gases to dilute said waste gases.
2. Apparatus according to claim 1, wherein said reactor housing is an elongated trough suspended from transverse beams supported by slide bearings on longitudinal beams so that said trough is freely movable in a longitudinal direction.
3. Apparatus according to claim 1, wherein said heating means comprises a plurality of separate external heating jackets disposed along the length of said reactor housing.
4. Apparatus according to claim 1, further comprising abutment means disposed adjacent the bottom of said reactor housing for absorbing the torsional forces of the reactor housing.
5. Apparatus according to claim 4, wherein said abut-ment means comprises two parts; one of said abutment parts being secured to the reactor housing and the other of said abutment parts being secured to the trough support structure; said two parts being longitudinally displaceable with respect to each other.
6. Apparatus according to claim 1, further comprising means in said reactor housing fox scraping adhering solid material from said rotatable agitating means.
7. A process for condensing solid materials which tend to sinter or adhere during condensation in a heated reactor com-prising the steps of: introducing a solid substance to be condens-ed into a reactor; heating the exterior wall of the reactor in order to heat the substance therein; agitating the material in the reactor and pressing the material in a thin layer against the reactor wall; said thin layer of material sintering and adhering to the reactor wall; stripping the sintered layer from the reactor wall; and returning the hot sintered material to the interior region of said reactor.
8. A process according to claim 7, wherein the solid material to be condensed is a phosphate material.
9. A process according to claim 7, wherein the material in the reactor is agitated by at least one set of rotating paddles disposed in the interior of the reactor and at least one paddle of each set is provided with knife means for stripping the sinter-ed material from the reactor wall.
10. A process according to claim 7, wherein the reactor is provided with at least one external heating jacket and is heated by passing a heating medium through said jacket.
11. A process according to claim 10, wherein said heating medium is a molten salt.
12. A process according to claim 10, wherein said heating medium is a molten metal.
13. A process according to claim 10, wherein said reactor is provided with a plurality of separate heating jackets disposed along the length thereof and different amounts of heat are supplied to different portions of the reactor along its length by supplying different temperature heating media to at least two of said jackets.
14. A process according to claim 7, further comprising the steps of withdrawing waste gases from the reactor; diluting the withdrawn gases with air; precipitating solid material entrain-ed in the diluted gases; and returning the precipitated material to the reactor.
15. A process according to claim 8, wherein said phos-phate material is selected from the group consisting of acidic alkali metal monophosphates, acidic alkaline earth metal monophos-phates, acidic heavy metal monophosphates and ammonium metal mono-phosphates.
16. A process according to claim 15, wherein said phos-phate material is condensed to a diphosphate.
17. A process according to claim 7, wherein said material is a mixture of boric acid and ammonium phosphate and the material is condensed to produce boron phosphate.
18. A process according to claim 8, wherein said material comprises urea phosphate and the material is condensed to form ammonium polyphosphate.
19. A process according to claim 7, wherein said material comprises urea and the material is condensed to cyanuric acid.
20. A process according to claim 8, wherein said mater-ial is selected from the group consisting of zinc monophosphate, manganese monophosphate and copper monophosphate and is condensed to the corresponding diphosphate.
21. A process according to claim 8, wherein said mater-ial comprises aluminum monophosphate and is condensed to a product selected from the group consisting of aluminum tripolyphosphate and aluminum metaphosphate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792907453 DE2907453A1 (en) | 1979-02-26 | 1979-02-26 | METHOD FOR CONDENSING SOLIDS, AND DEVICE FOR CARRYING OUT THE METHOD |
| DEP2907453.1 | 1979-02-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1141143A true CA1141143A (en) | 1983-02-15 |
Family
ID=6063933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000345778A Expired CA1141143A (en) | 1979-02-26 | 1980-02-15 | Process for condensing solids and apparatus for carrying out said process |
Country Status (5)
| Country | Link |
|---|---|
| US (2) | US4293526A (en) |
| EP (1) | EP0015006B1 (en) |
| AT (1) | ATE7684T1 (en) |
| CA (1) | CA1141143A (en) |
| DE (2) | DE2907453A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0094935A1 (en) * | 1981-11-30 | 1983-11-30 | GROVE, F.Allen | Structure for continuous-line coal desulfurizarion reaction |
| DE3820198A1 (en) * | 1988-06-14 | 1989-12-21 | Benckiser Knapsack Gmbh | USE OF CALCIUM DIHYDROGEN DIPHOSPHATE AS BACKUFFIC ACID FOR SLOWLY REACTIVE DRIVE SYSTEMS AND METHOD FOR THE PRODUCTION THEREOF |
| NL1009588C2 (en) | 1998-07-08 | 2000-01-11 | Dsm Nv | Polyphosphate salt of a high condensation 1,3,5-triazine compound, a process for its preparation and use as a flame arrester in polymer compositions. |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE764763C (en) * | 1934-06-17 | 1952-05-23 | Albert Ag Chem Werke | Production of polyphosphates or polyphosphate mixtures |
| DE818801C (en) * | 1948-10-02 | 1951-10-29 | Metallgesellschaft Ag | Process for the production of pyrophosphates, metaphosphates and polyphosphates |
| DE972118C (en) * | 1954-04-08 | 1959-05-27 | Chem Fab Budenheim Ag | Process for the production of condensed phosphates |
| US2883272A (en) * | 1955-09-13 | 1959-04-21 | Gen Electric | Apparatus for the continuous polymerization of organopolysiloxanes |
| GB1128802A (en) * | 1964-11-16 | 1968-10-02 | Occidental Res & Eng | Improvements relating to the ammoniation of phosphoric acids |
| DE1542151C3 (en) * | 1966-12-27 | 1975-07-17 | Bayer Ag, 5090 Leverkusen | Wiper for thin film reaction or evaporation tube |
| JPS5021992B1 (en) * | 1968-02-17 | 1975-07-26 | ||
| US3682091A (en) * | 1970-03-16 | 1972-08-08 | French Oil Mill Machinery | Rendering cooker |
| JPS5021514B2 (en) * | 1972-04-12 | 1975-07-23 | ||
| JPS5341676B2 (en) * | 1973-10-05 | 1978-11-06 |
-
1979
- 1979-02-26 DE DE19792907453 patent/DE2907453A1/en not_active Withdrawn
-
1980
- 1980-02-15 CA CA000345778A patent/CA1141143A/en not_active Expired
- 1980-02-22 AT AT80100893T patent/ATE7684T1/en active
- 1980-02-22 EP EP80100893A patent/EP0015006B1/en not_active Expired
- 1980-02-22 DE DE8080100893T patent/DE3067994D1/en not_active Expired
- 1980-02-22 US US06/123,754 patent/US4293526A/en not_active Expired - Lifetime
-
1981
- 1981-03-03 US US06/239,975 patent/US4343779A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ATE7684T1 (en) | 1984-06-15 |
| EP0015006B1 (en) | 1984-05-30 |
| US4293526A (en) | 1981-10-06 |
| EP0015006A3 (en) | 1980-10-15 |
| DE3067994D1 (en) | 1984-07-05 |
| EP0015006A2 (en) | 1980-09-03 |
| DE2907453A1 (en) | 1980-09-04 |
| US4343779A (en) | 1982-08-10 |
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