JPS5933529B2 - Ammonium phosphate production equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for producing ammonium phosphate using gaseous ammonia and an aqueous phosphoric acid solution as raw materials.

Conventionally, as a method for producing ammonium phosphate, a method of neutralizing an aqueous phosphoric acid solution with ammonia gas in a neutralization tank has been commonly practiced.

On the other hand, a method using a tubular reactor is also known, and this method (1) allows for miniaturization of the device and is easy to start and start, (2) can be applied to a wide range of slurry concentrations.
3) It has features such as high reaction efficiency and low ammonia loss, but the problem with this method using a tubular reactor is how to mix and react the raw materials well, and various improvements have been made to the reaction mixing section. There is.

For example, in the case of manufacturing monoammonium phosphate (NH3/P205 molar ratio -1.0), rti, the solubility of ammonium phosphate is the lowest at NHa/P2O5 molar ratio -1.0, and it is susceptible to scaling, so the continuous operation time is (In actual operation, methods such as creating two trains or operating for a short period of time, then stopping the operation and cleaning the inside of the pipe, etc.) are used, which is a waste of equipment, time, and labor. There were many.

Additionally, a commonly used method is to gradually reduce the diameter of the tube toward the reactor outlet to efficiently mix the reaction materials. Although some growth suppression effect was observed, it was not satisfactory, and the continuous operation time of the device was extremely short.

The present invention aims to eliminate the drawbacks of the above-mentioned conventional apparatus when producing ammonium phosphate from gaseous ammonia and phosphoric acid aqueous solution using a tubular reactor. The phosphoric acid aqueous solution is introduced horizontally to the tube, and the phosphoric acid aqueous solution is introduced tangentially at high speed from around the anti-core heating zone, thereby improving the mixing of ammonia and phosphoric acid and increasing the reaction efficiency, resulting in extremely low ammonia loss. At the same time, the generated slurry that has been sufficiently mixed and reacted in the reaction mixing section is introduced into the enlarged pipe diameter section through the neck section to increase the mixing effect, and in the enlarged pipe diameter section, the flow rate is lowered and the scale is removed. By selectively adhering to this part, scale adhesion and growth are suppressed in other parts (slurry transport part), and steam is intermittently introduced from the reaction mixing part during continuous operation, especially to expand the pipe diameter. This invention relates to a device that prevents the growth of scale in the body as much as possible.

That is, the present invention provides, in order from the front end of a tubular reactor, a reaction mixing section having a gaseous ammonia introduction section, a phosphoric acid aqueous solution introduction section, and a steam introduction section in the tangential direction, a tube diameter enlarged section via a neck section, and a tube diameter expansion section. An apparatus for producing ammonium phosphate is provided, which comprises a slurry transport section having a smaller diameter than the enlarged section, curved downward, and having a tip serving as a spray nozzle.

With the equipment of the present invention, when the system is stopped, cleaning can be performed concentratedly on the enlarged pipe diameter section, where scale easily adheres, so restarting operation can be done with a short stoppage, and further operation can be achieved by replacing the enlarged pipe diameter section. It is also possible to shorten the stoppage time, and by intermittent introduction of steam, it is possible to prevent scale growth in the enlarged pipe diameter section as much as possible, thereby dramatically extending the continuous operation time. .

Generally, equipment that uses such a reaction method uses a method of steam cleaning when the operation is stopped or a method of continuously blowing steam, but in the former case, scale usually grows until it becomes impossible to operate. Because of this, the amount of steam required for cleaning is also undesirable, and in the latter case, the amount of steam consumed is extremely large due to continuous steam blowing, which is uneconomical and is not an industrially superior device. hard.

In the apparatus of the present invention, steam cleaning is preferably performed by blowing steam for about 30 seconds at intervals of 2 hours, and the blowing amount is 0.1klii'.
/It may be about 1 ammonium phosphate or more, and the blowing pressure is medium pressure (4-5 kg/crt) that can easily remove scale.
l) The above is preferable.

As shown in FIGS. 1 and 2, the apparatus of the present invention comprises a gaseous ammonia introduction pipe 1 located at the front end of a tubular reactor, followed by a phosphoric acid aqueous solution introduction pipe 3 and a steam introduction pipe 4 in the tangential direction. The mixing section 2 is followed by a tube diameter enlarged section 6 which continues via the neck section 5, and the tube diameter enlarged section 6 is followed by a diameter smaller than the tube diameter enlargement section 6 and curved downward.

It consists of a slurry transport section 7 whose tip is a spray nozzle 8.

Since the phosphoric acid aqueous solution introduction pipe 3 is located at right angles to the gaseous ammonia introduction pipe 1 and is provided in the tangential direction of the reaction mixing section 2, the phosphoric acid aqueous solution and gaseous ammonia are mixed vigorously and the reaction is carried out efficiently. .

In addition, a steam introduction pipe 4 is provided in the tangential direction in the reaction mixing section 2, and by intermittently blowing steam, the structure is such that scale adhering mainly to the enlarged part of the pipe can be efficiently removed. , it becomes possible to dramatically extend the continuous operation time.

The ammonium phosphate slurry that has been sufficiently mixed and reacted in the reaction mixing section 2 is introduced into the tube diameter enlarged section 6 through the neck section 5, where the flow rate decreases due to the enlargement of the tube diameter, so scale is selectively removed in this section. It becomes easier to adhere.

The slurry that has exited the expanded pipe diameter section 6 increases the flow velocity again in the scale transport section 7, which has a smaller diameter pipe, so that there is less scale adhesion in this section, and then from the spray nozzle 8 at the tip. It is sprayed into a known spray dryer and dried by the reaction heat and air to produce powdered ammonium phosphate.

In this reactor, scale is concentrated on the enlarged tube diameter section 6, and by making the enlarged tube diameter section 6 detachable, it is only necessary to replace or clean this section. Therefore, the operation stop time is extremely short.

In this reactor, it has been found that the following ratio relationship is preferable for the pipe diameters of each part in order to improve operational efficiency and prevent scale adhesion and growth.

■ Pipe diameter enlarged section 6/reaction mixing section 2-1 to 1.2■ Pipe diameter enlarged section 6/neck section 5 = 1.3 to 2.0■ Pipe diameter enlarged section 6/slurry transport section 7 = 1.3 ~2.0 (1) Slurry one-wheel feeder 7/spray nozzle 8 = 1.5-3.0 The present invention will be described in more detail below with reference to Examples and Comparative Examples.

In addition, the following manufacturing conditions were adopted for both the examples and comparative examples.

(1) Raw material supply amount is phosphoric acid aqueous solution (50% P2O5)42
50 kg/hr (as P 205), gaseous ammonia 1050 kg/hr.

(2) The ammonium phosphate produced is NHa/H3P
04 is powdered monoammonium phosphate (MAP) with a molar ratio of 1.

Example 1 The above raw materials were supplied to a reaction apparatus having the following specifications to continuously produce MAP.

Intermittent introduction of steam is carried out every 2 hours with medium pressure steam (4,5-5
This was done by injecting 0.24 kg/crA) for 530 seconds to a rate of 0.24 kg/MAP 1 t.

As a result of examining the state of scale adhesion in each part after 10 hours, 25 hours, and 50 hours, no scaling was observed in the reaction mixing part, neck, and spray nozzle, and no scaling was observed in the enlarged pipe diameter part and slurry transport part. Thickness as shown in mm)
There was scale attached to it.

Production was carried out using similar production conditions and reactor specifications.

After 10 hours, 20 hours, and 30 hours had elapsed, we examined the state of scale adhesion in each part. As a result, no scaling was observed in the reaction mixing part, neck part, or spray nozzle, and no scaling was observed in the enlarged pipe diameter part or slurry transport part. The thickness is as shown in Table 2 (mm)
) scale was attached.

After 50 hours had passed, the operation was stopped due to a significant decrease in capacity.

In this example, the temperature at the outlet of the reaction mixing section was 190 to 220°C, and the ammonia loss was 0.7! It was 9/MAP 1t.

Comparative Example 1 The diameter of the enlarged tube diameter section 6 is the diameter of the slurry transport section 7 (inner diameter 80.
7 mmφ) was the same as in Example 1, but after 30 hours, the performance deteriorated significantly and operation became impossible.

Comparative Example 2 Production was carried out in the same manner as in Comparative Example 1, except that steam injection was not performed, and other production conditions and reactor specifications were the same.

As a result of examining the state of scale adhesion after 1 hour, 5 hours, and 8 hours, we found that the thickness was as shown in Table 3.
) scale was attached.

Eight hours after the start of operation, the capacity deteriorated significantly and operation became impossible.

[Brief explanation of drawings]

FIG. 1 is a front view of the reaction apparatus of the present invention, and FIG. 2 is a sectional view taken along line AA in FIG.

Claims (1)

[Scope of Claims] 1. In order from the front end of the tubular reactor, a reaction mixing section having a gaseous ammonia introduction section, a phosphoric acid aqueous solution introduction section, and a steam introduction section in the tangential direction, a tube diameter enlarged section via a neck section, and An apparatus for producing ammonium phosphate, comprising a slurry transport section that has a smaller diameter than the enlarged pipe diameter section, is curved downward, and has a spray nozzle at its tip. 2. The ammonium phosphate manufacturing apparatus according to claim 1, wherein the pipe diameter enlarged portion is detachable. 3 The ratio of the diameters of each part is: ■ Expanded tube diameter section/reaction mixing section - 1 to 1.2 ■ Expanded tube diameter section/2 parts = 1.3 to 2.0 ■ Expanded tube diameter section/slurry transport section - The ammonium phosphate manufacturing apparatus according to claim 1 or 2, wherein the ratio of slurry single-wheel feeder/spray nozzle is 1.5 to 2.0.