JPS61136905A - Production of ammonium phosphate slurry and reactor used in this method - Google Patents

Abstract

PURPOSE:To produce the titled slurry without closing a mixing part for a long period by bringing liquid ammonia into contact with an aq. phosphoric acid soln. in the rectangular direction, heating and allowing them to react with each other. CONSTITUTION:Liquid ammonia is introduced into a mixing part 1 via a perforated pipe of a conduit 7 through a conduit 6 and also an aq. phosphoric acid soln. of >=40wt% P2O5 concn. is introduced in the tangential direction for a horizontal cylinder of the mixing part through a conduit 8 fitted to the downward tangential direction of the mixing part 1 and the mixture is heated at 120-180 deg.C by a heating part 5 of an outside part of horizontal tubular reactor wherein a slurry conveying part 2 of the same flat surface as the mixing part 1 is provided to a ceiling part and allowed to react with each other and the produced ammonium phosphate slurry is discharged through the conveying part 2. The continuous operation can be carried out for a long period by preventing the deposit of diammonium phosphate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for producing ammonium phosphate slurry using an aqueous phosphoric acid solution and liquid ammonia as raw materials.

(Prior art and its problems) Recently, a tubular reactor is sometimes used as a method for producing ammonium phosphate slurry.

The present inventors have already succeeded in developing a tubular reactor and put it into practical use (registration number 1183176). However, the concentration of phosphoric acid aqueous solution and the state of ammonia (liquid or gas)
Depending on the combination, crystal precipitation of diphosphoramine may cause blockage of the reactor, making stable operation impossible.

That is, when the concentration of the phosphoric acid aqueous solution is relatively low, a tubular reactor with an appropriate mixing section volume can operate stably even if one of the raw materials is liquid ammonia, but when the concentration of the phosphoric acid aqueous solution is P2O, 40 wt. %, crystal precipitation of diphosphoramine becomes severe and long-term continuous operation becomes impossible.

It is presumed that this clogging of the mixing section is caused by the following phenomenon.

■ Deterioration of dispersion of liquid ammonia ■ Reaction stagnation/decreased reaction heat generation ■ Temperature decrease due to vaporization of liquid ammonia ■ Decreased solubility of diphosphorous ammonium/crystal precipitation ■ Crystal solidification/clogging In such cases, as a method to prevent clogging, Typically, methods include adding a small amount of water to liquid ammonia, or intermittently blowing steam into the reactor body.

However, unless the purpose is to adjust the solid concentration of the ammonium phosphorus slurry produced, injecting water or steam directly into the reactor simply to prevent blockage is one of the advantages of using a tubular reactor. Considering that the purpose is to obtain a concentrated ammonium phosphorus slurry, it is not necessarily a preferable method (
・.

The present invention aims to solve the above-mentioned problems of the prior art.

(Means for Solving the Problems) The present inventors have conducted various studies regarding the above-mentioned problems to be solved, and have completed the method and reactor of the present invention.

That is, the present invention uses a phosphoric acid aqueous solution and liquid ammonia as raw materials, and has a mixing section at the front end, followed by a horizontal tubular slurry transport section that is smaller in diameter than the mixing section and whose ceiling surface is on the same plane as the mixing section. In a method for producing ammonium phosphate slurry using a reactor, liquid ammonia is fed from the front through a porous pipe inserted into the mixing section, and a phosphoric acid aqueous solution with a P2O5 content exceeding 40% by weight is fed into the mixing section. A method for producing ammonium phosphate slurry, which is characterized by introducing the ammonium phosphate slurry in a downward tangential direction from a conduit attached to the top or side, and causing the slurry to react while externally heating the mixing section, and the mixing section (1) and ceiling surface used in this method. In a horizontal tubular reactor for producing ammonium phosphate slurry, which consists of a slurry transport section (2) on the same plane as the mixing section, ammonia is transferred from the front end of the mixing section (1) to a large number of ammonia spout ports. Insert the inlet pipe (6), and attach the phosphoric acid aqueous solution inlet pipe (8) in a downward tangential direction from the top to the side of the mixing part, and then install the heating jacket (5) on the outside of the mixing part.
) is a horizontal tubular reactor.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a reaction apparatus used in the present invention. Liquid ammonia flows from the conduit (6) through the conduit (force) to the mixing section (
1), and the internal part of the conduit (7) is a perforated pipe with a large number of holes so that the liquid ammonia is uniformly dispersed in the mixing part. In order to improve the dispersion and mixing within the mixing section, it is better to give the ammonia outlet a direction that facilitates the distribution of the phosphoric acid aqueous solution, as shown in the enlarged view of FIG. 3, for example.

On the other hand, the phosphoric acid aqueous solution is introduced tangentially into the horizontal cylinder of the mixing section through a conduit (8) which is connected from the top to the side in the tangential direction toward the mixing H. The slurry can be mixed uniformly while being stirred, and at the same time, solids in the slurry can be prevented from settling on the bottom of the mixing section. Further, by attaching the conduit (8) downward from the top to the side, it is possible to prevent solid matter from being deposited in the phosphoric acid aqueous solution conduit when the operation is stopped.

The mixing section is provided with a heating jacket (5) through which steam is passed and heated to usually 120 to 180°C.

Naturally, the surface of the jacket is covered with a heat insulating material.

The ammonium phosphate slurry produced by the reaction between liquid ammonia and the phosphoric acid aqueous solution in the mixing section (5) then enters the transport section (2). Scaling in the circulation section is prevented by making the diameter of the transport section (2) smaller than that of the mixing section (1) and increasing the slurry flow rate. In addition, since a slot or a bushing nozzle is provided at the end of the transport section, the inside of the reactor is kept under pressure, so that the reaction is sufficiently carried out and the generation of water vapor within the reactor is suppressed. In this way, ammonium phosphate slurry is produced.

The reactor of the present invention is the most common and has the following types: It is equipped with a unique feature.

■Mixing part diameter: Transporting part diameter -3 to 5 ■Transporting part area Nislot cross-sectional area "ball 1.4 to 3" ■Transporting part length = 2rrL or more ■Surroundings of mixing part Comes with steam jacket ■Mixing part volume (horizontal cylindrical part) Relationship between the amount of liquid ammonia supplied and Generally 5US316
L is sufficient, but depending on the composition of the phosphoric acid aqueous solution, corrosion may be severe, so Hastelloy C alloy is used.

(Functions and Effects) The present invention provides a steam jacket (or electric heater) in the mixing section and performs auxiliary steam heating to promote the reaction between a highly concentrated phosphoric acid aqueous solution and liquid ammonia. Prevents crystal precipitation and enables long-term continuous operation.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

Example 1 This example is an example of manufacturing ammonium phosphate slurry using the following reaction device specifications and manufacturing conditions.

(1) Reactor specifications Mixing section: Inner diameter 200 gen. 1 Length 800 mal + (300ml inclined section) Volume (horizontal section) 25,120 cd Transport section: Inner diameter 62
5111φ Length 2500L Slot: 180X10L Material: SUS 316L (2) Operating conditions Phosphoric acid aqueous solution (P2O, 43% 5oln) Supply amount: 14
92 to 9/H (as Pro, ) liquid ammonia
=500 Yu/HN/P molar ratio: 1.4 Liquid a7 mo? -A supply load: 0.020 kgNH3
/cd-H reactor pressure: 1.2kg/c
d-G (Initial) Reactor outlet temperature: 131℃ (3) Results Continuous operation time 96.5H with Nisteam heating
None 5.5H Steam consumption: 75kg/H (3'q/crd・G
, i60'c) 90 Kcal/9 ・NH
s In this experiment, the reaction could be carried out for a long time without any problems of clogging of the mixing section or clogging of the entire apparatus.

Further, the amount of steam used for heating was extremely small, and approximately 1/3 of the latent heat of vaporization required to gasify liquid ammonia was sufficient.

Example-2 (1) Reactor specifications Mixing section: Inner diameter 250J+mφ Length 100100O! + (400zml slope)
Volume (horizontal part) 49,063 cIll Transport part: Inner diameter 75 * mφ Length 3150 l Slot: 240 x 13 ys * Material: SU
S 316L (2) Operating conditions Phosphoric acid aqueous solution (P2O, 41% 5oln) supply amount = 3
282) Cf/H (as P2O,) liquid ammonia: uookII/HN/P molar ratio
=1.4 Liquid ammonia supply load: 0.023kg■s/ad
・H reactor pressure: 1.7 to 9/cd-G
(Initial) Reactor outlet temperature = 129℃ (3) Results Continuous operation time with Nisteam heating 73.2I (〃
None 2.1H Steam consumption: 160 to 9/H (3kg/cd・
G, 160'C) 87 Kcal/kl?・NHs Even if the reactor size is increased and the reaction throughput is increased,
Similar to the results of Example-1, there was no clogging of the mixing section;
Continuous operation for a long time was possible, and the consumption of heating steam was small.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the reactor of the present invention, FIG. 2 is a perspective view of the external appearance of the reactor of the present invention, and FIG. 3 is an enlarged view of the liquid ammonia injection site. The symbols in the figure are as follows. 1. Mixing section 2, slurry transport section 3, slot 4, cleaning blind plug 5, heating jacket 6, liquid ammonia introduction pipe 7, liquid ammonia nozzle 8, phosphoric acid aqueous solution introduction pipe 9, cleaning steam introduction pipe 10, heating steam inlet pipe 11, drain discharge pipe 12, pressure gauge Patent applicant: Mitsui Toatsu Chemical Co., Ltd. Procedural amendment (voluntary) January 2, 1985) Japan Patent Office Commissioner Manabu Shiga 1, Indication of the case 1988 Patent Application No. 254232 2, Name of the invention: Method for producing ammonium phosphate slurry and reactor 3 used in this method, Relationship with the case of the person making the amendment Patent applicant address: 3-2-5 Kasumigaseki, Chiyoda-ku, Tokyo Issue name
Name (312) Mitsui Toatsu Chemical Co., Ltd. Corrected to "62.5u da".

Claims (1)

[Scope of Claims] 1) A horizontal slurry transporting section that uses an aqueous phosphoric acid solution and liquid ammonia as raw materials, has a mixing section at the front end, is smaller in diameter than the mixing section, and has a ceiling surface on the same plane as the mixing section. In a method for producing ammonium phosphate slurry using a type tubular reactor, liquid ammonia is introduced from the front through a porous pipe inserted into the mixing section, and P_2O_5
A phosphoric acid aqueous solution having a concentration of more than 40% by weight is introduced in a downward tangential direction from a conduit attached to the top to side of the mixing section,
A method for producing ammonium phosphate slurry, characterized by carrying out a reaction while externally heating a mixing part. 2) In a horizontal tubular reactor for producing ammonium phosphate slurry, which consists of a mixing section (1) and a slurry transport section (2) whose ceiling surface is flush with the mixing section, a large number of Insert the ammonia inlet pipe (6) with an ammonia spout, and attach the phosphoric acid aqueous solution inlet pipe (8) in a downward tangential direction from the top to the side of the mixing part, and then install the heating jacket (5) on the outside of the mixing part. A horizontal tubular reactor characterized by being equipped with.