CS210335B1 - Method of continuous preparation of the polycondensed ammonium phosphates and device for executing the same - Google Patents

Description

SUMMARY OF THE INVENTION The present invention relates to a process for the continuous preparation of a melt of polycondensated ammonium phosphates and an apparatus for carrying out this process.

Melted condensed ammonium phosphates of the formula:

Η / n + 2 / -ιη ^ ηθ3η + 1 is one of the basic starting materials for the preparation of concentrated liquid fertilizers, both clear and suspension.

Several methods for preparing a melt of condensed ammonium phosphates are currently known. The most sophisticated and widespread are methods based on atmospheric or pressure neutralization of phosphoric acids of different concentration and purity.

For the production of condensed phosphate melt, the most diverse types of reactors are used, in particular tubular structure reactors, the most widespread of which are the so-called reactors. T-reactors. These reactors are protected by a number of patents, for example, U.S. Pat. no. 2,985,513, 3,382,059,

464,808, 3,502,441; France. pat. no. 1,493,803; South African Pat. No. 67/5806; DOS 1 909 438

DOS 2,114,055, DOS 2,308,716; Swed. pat. No. 366 012; MS. 180 802 copyright certificate.

Of the T-reactors mentioned in the literature, the most popular is the Swift reactor.

Various modified tubular reactors have also been reported

Chem. Engíneering / 8 /, 60 1 2/1 972 /

Agric. Chem. (2), 12-16, 28, (1973)

Fert. Solutions (2), 44-54, 17, (1973)

Meline R. S .: Production of Hgh-Polyphosphate Liguid Fertilizer by Pipe Reactor Procese - XSMA, Prague 1974, Phosphorus and Potassium 90, 25 “30, (1977)

Chem. industry 28/53, 229-233,5 (1978).

While these types of tubular reactors have made substantial progress in the development of a melt production plant for condensed ammonium phosphates, they have some disadvantages, for example:

- do not allow the treatment of the highly contaminated extraction phosphoric acids associated with the foaming of the reaction mixture due to the organic matter content; with the formation of depressions of reactor cross-section and negatively affecting hydrodynamics and the like;

** inefficient use of non-fractional heat due to the course of molecular dehydration;

low efficiency mixing of reactants (relatively low flow turbulence);

- the need to dispense phosphoric acid under pressure;

increased demands on the corrosion resistance of the construction materials of the hot phosphoric acid dosing device;

- the operator's demands on the level of operational reliability of the equipment and the like.

These disadvantages are substantially eliminated by the manufacturing process and the apparatus of the invention.

A process for the continuous preparation of a melt of condensed ammonium phosphates according to the invention, by reacting phosphoric acid at a concentration of 50 to 70% ^P 2 ° 5 ^{and Ce} Pl ° ^{te 50 and} % ² $ ° ° ^C or a solution of ammonium dihydrogen phosphates in phosphoric acid The process according to claim 1, wherein the ammonia gas preheated prior to entering the reaction medium by the heat of the reaction mixture is dosed in a 10-15% excess over the amount of melt bound in the form of phosphates and condensed ammonium phosphates.

The specific gravity of the phosphoric acid-containing liquid reactant fed to the reaction medium is at least twice the mean specific gravity of the heterogeneous reaction mixture in the reaction mixture in the reaction medium. The reaction is carried out with stirring, characterized by a Reynolds criterion of Re * 1.5. 10 ^.

By efficient turbulent mixing of the reactants and the reaction mixture, as well as the continuous free flow of the phosphoric acid-containing liquid reactant into the reaction medium, particularly favorable conditions are created for simultaneous neutralization of the phosphoric acid and molecular dehydration of its ammonium salts resulting from this neutralization.

Said process for the continuous production of a melt of condensed ammonium phosphates by reaction of phosphoric acid not containing or containing chemically bonded ammonia with ammonia gas can advantageously be carried out on the apparatus according to the invention.

The apparatus for continuously preparing a melt of condensed ammonium phosphates according to the invention consists of a reactor having an inlet and an outlet, characterized in that the reactor 1 has an angle alpha of 0 ° ^ alpha <180 ° with the horizontal plane,

The reactor 1 is further provided with an inlet 2 passing through the reactor body through the outlet 3 inside the reactor body. The ratio of the lumen of the body of the reactor J_ raíeste the outlet 9 of the reactor 1 of the flat body lumen reactor «£ the place of supply 10 ^_" -2 2 £ _ of the reactor was equal to 5. 10 to 5. 10.

The ratio of the effective length of the reaction zone to the narrowest internal cross-section of the reactor body is 1.2 to 95. The ratio of the distance of the reactor inlet 10 from the point of the outlet 9 of the reactor. to the distance of the outlet 3 inside the reactor body from the location of the outlet 2 inside the reactor body 1 from the location of the reactor outlet 2 is equal to 0.5 to 1.5.

The spacing of the outlet 3 inside the reactor body 10 at the point of the outlet 2 of the reactor 6 equals at least half the effective length of the reaction zone.

The device for continuously preparing the melt of condensed ammonium phosphates according to the invention can be arranged such that the outlet 3 inside the reactor body 6 can be separated from the reactor inlet 10 by a baffle 4 and / or the reactor inlet 10 is provided with a liquid shutter 5 and the reactor 7 is provided, in whole or in part, with a packing 6 and / or an assembly 7 and / or comprises a static mixer 53.

Carefully sealed to the body of the reactor flows through the loose connection - inlet liquid reactant 10 21 Phosphoric acid concentration of 50-72% ^{of that Ρ 2θ5 and} Pl ° ^-C 50-290 DEG C., and the hot solution of ammonium hydrogen phosphate, phosphoric acid,

In the space above the mouth - the inlet of the phosphoric acid-containing liquid reactant, it comes into contact with the preheated ammonia gas 20, which is descending to the downstream part of the reactor through a feed tube through the feed tube coaxially through the reaction chamber. preheating the ammonia gas with the heat of the reaction mixture.

Unwanted mixing of the phosphoric acid-containing liquid reactant with ammonia gas outside the reaction space in the liquid-reactive inlet conduit is prevented or so that the ammonia gas outlet 3 is placed above the inlet-inlet of the phosphoric acid-containing liquid reactant or by a suitable baffled plate. and / or also suitably by infusing the liquid reactant through the liquid cap 5.

The reaction of ammonia gas with a phosphoric acid-containing liquid reactant releases neutralizing heat, which heats the reaction mixture to a temperature above 200 ° C.

In the case of simultaneous neutralization and molecular dehydration, the chemically bound (free) and partially molecular bound water released by the released neutralization heat evaporates due to the water vapor thus generated and the kinetic energy of the ammonia gas dosed in 10 to 150% excess over the amount in the melt formation, the reaction mixture is intensively stirred, the intensity of which may be characterized by the Reynolds criterion value Re = 1.5, 10 ^ ·

Since the volume of the reaction mixture is predominantly composed of a superheated gas mixture of water vapor and excess ammonia, its specific gravity is substantially lower than that of the feed phosphoric acid-containing liquid component.

This density difference allows the free flow of phosphoric acid-containing reactant into the reaction chamber of the reactor body as well as the upward flow (bottom-up) of the reaction medium through the reaction chamber.

The reaction mixture consisting of a melt of condensed ammonium phosphates, water vapor and excess ammonia 22 is continuously removed by the reaction mixture overflow.

In order to achieve the necessary residence time of the reaction mixture in the reaction space of the reactor body 1 under conditions suitable for optimum simultaneous neutralization of phosphoric acid and molecular dehydration of its ammonium salts resulting from neutralization. Suitably, the internal cross-sectional area of the reactor body at the overflow point of the reaction mixture (Fi) is heavier than the internal cross-sectional area of the reactor body at the orifice point - the inlet of the phosphoric acid-containing liquid component (F _o ).

In order to further increase the mixing intensity and to increase the reaction surface, it is advantageous to provide the reaction chamber of the reactor body V with a filling 6 and / or a T and / or a suitable static mixer 8. Method for producing a melt of polycondensated ammonium phosphates The invention has many advantages:

- production method and equipment is characterized by great operational reliability and is easy to operate and simple to shut down and no preparatory measures are necessary

- the apparatus allows the processing of P 2 O 3 bs ^and liquid liquids of varying purity and concentration within a wide range of 2 ^ 5

- the device operates at minimum energy requirements when dispensing the liquid reactant

- the device is simple and does not have rotating parts

The production method and the apparatus enable the preparation of a melt of condensed ammonium phosphates characterized by a high content of phosphorus bound in polycondensate ^{in a} form suitable for the production of concentrated liquid fertilizers as well as for the preparation of solid granular fertilizers.

The following examples illustrate but do not limit the invention in any way.

Example!

In a multi-stage continuous pilot pilot run on a vertically (90 °) reactor within the meaning of the invention, characterized by the following parameters:

- effective reaction zone length / reaction space / L = 500 mm

- the narrowest internal diameter of the reactor body S of 90 mm

- the ratio of the internal cross-sectional area of the reactor body at the overflow point of the reaction mixture (F ^) to the internal cross-sectional area of the reactor body at the mouth - phosphoric acid inlet / ^F 1 / ^F 1 ^{: F} 2 = ¹ was treated with correlation extraction acid.

- total phosphorus content (determined by spectrophotometer): - acidity expressed as phosphorus content: - total iron content: 59.4% P ₂ O ₅ 54.5% P ₂ 0 ₅ 0.27% Fe - total aluminum content: 0.25% Al - Total magnesium content: 0.58% Mg - total fluorine content: 0.34% F

The acid was continuously metered through the metering pump in an average amount of about 80 kg H 2 to the atmospheric evaporator from where it flowed free through an aerated pipeline to the bottom of the reactor separated from the ammonia feed by a coaxial cylindrical septum.

Gaseous ammonia was fed from the evaporator through a set of rotameters in an average amount of 17.85 kg of NH 2 inlet pipe terminated by a separator rose to the bottom of the reactor.

The reaction of the partially concentrated phosphoric acid flowing into the reactor having an average concentration of 61.7% of total P2 ° 5 ^{and a} temperature of 140 to 145 ° C with ammonia gas, preheated by the reaction mixture heats the reaction mixture to 255 to 265 ° C. foaming due to the release of water vapor and unreacted ammonia,

The melt of polycondensated ammonium phosphates continuously flowing through the overflow in the upper part of the reactor body, in the form of a strongly foamed viscous liquid, was processed into an NP-liquid fertilizer.

The melt was characterized by the following average chemical composition:

- total nitrogen content; 11.42 N total phosphorus content: 64.12 P ₂ ° ₅

- the content of phosphorus bound in the orthoform; 28.92 P ₂ O ₅

- the content of phosphorus in the condensate,

zovana forma; 35.2% P ₂ O ₅ - phosphorus conversion from 1 to condensed * forms; 54,9% ~ maximum condensation degree represented in the melt: n = 3/4 • FOR D Μ E T V Y FINDINGS U 1. Continuous preparation method melt condensed phosphates ammonium reaction phosphoric acid o concentration 50 to 72Z ^P 2 ° 5 and temperature 50 to 290 ° C, or di-

Claims (3)

- the content of phosphorus in the condensate, zovana forma; 35.2% P ₂ O ₅ - phosphorus conversion from 1 to condensed * forms; 54,9% ~ maximum condensation degree represented in the melt: n = 3/4 • FOR D Μ E T V Y FINDINGS U 1. Continuous preparation method melt condensed phosphates ammonium reaction phosphoric acid o concentration 50 to 72Z ^P 2 ° 5 and temperature 50 to 290 ° C, or di- ammonium hydrogenphosphates in phosphoric acid with ammonia gas, characterized in that the ammonia gas preheated prior to entering the reaction medium by the heat of the reaction mixture is dosed at 10 to 150 ° C. in excess of the amount of ammonia bound in the melt in the form of phosphates and condensed ammonium phosphates, the specific gravity of the phosphoric acid-containing liquid reactant fed to the reaction medium is at least 2.0 times the mean specific gravity of the heterogeneous reaction mixture in the reaction medium. with stirring characterized by a Reynolds criterion value of Re $ 1.5. 10 ^. 2. Apparatus for the continuous preparation of a melt of condensed ammonium phosphates according to claim 1, comprising a reactor having an inlet and an outlet, characterized in that the reactor (1) has a horizontal alpha angle of 0 ° <alpha <180 °, is further provided with an inlet (2) passing through the reactor body (1) via an outlet port (3) within the reactor body (1), wherein a further ratio of the internal cross-sectional area of the reactor body (1) at the outlet (9) of the reactor (1) the reactor body cross-sectional area (1) at a site of ~ 2 2 te of the reactor inlet (10) is equal to 5.10 to 5.10, the ratio of effective reaction zone length to the narrowest internal section of the reactor body is 1.2 to 95 and (1) from the reactor outlet (1) to the reactor (1). the distance of the outlet (3) inside the reactor body (1) from the outlet location (9) of the reactor (1) is equal to 0.5 to 1.5, with the distance of the outlet (3) inside the reactor body (1) from the outlet location (9) (reactor) is equal to at least half the effective length of the reaction zone. 3. Apparatus for the continuous preparation of melt of condensed ammonium phosphates according to claim 2, characterized in that the outlet (3) inside the reactor body (1) can be separated from the inlet (10) of the reactor (1) by a partition (4) and / or 10) of the reactor (1) is provided with a liquid cap (5) and further optionally the reactor (1) is provided with a packing (6) and / or a built-in (7) and / or a static mixer (1) 8 /.