SU1446103A1 - Method of producing dry-process phosphoric acid - Google Patents

Abstract

This invention relates to a process for the production of thermal phosphoric acid used for the production of fertilizers and feed phosphates. The aim of the invention is to reduce the content of phosphoric anhydride in the gases leaving the hydration stage. The molten phosphorus from the metering devices in the amount of 2.6 t / h is fed to the nozzle of the combustion tower. Phosphorus burning is carried out at a factor. Those of excess air with 2. Semides type 380% circulating phosphoric acid with a temperature of 380 is served in a bowl located in the upper part of the combustion tower, and in an amount of 220 m V4 - to the nozzles located in the middle part of the tower. 8 m- / h acid from the hydration stage with a concentration of 45% HjPO and a temperature of 50 ° C are also fed to the bowl. Gases with a temperature of 100 ° C, containing phosphoric anhydride in the amount of 71 g / m, are fed from the combustion tower to the hydration tower. The gas flow velocity in the contact zones of the hydration tower is maintained at 16 m / s. The first in the course of the gas the lower contact zone is irrigated with adenic acid to 35 ° C with phosphoric 45% acid, and the top, second in the direction of the gas, the contact zone is irrigated with water. The consumption of acid and water supplied to the contact zones is 1.60 m / h each, taking into account their circulation, which, when the diameter of the contact zone is 0.85 m, corresponds to an irrigation density of 280 m / m-h. Phosphoric anhydride is captured at a rate of 99.99% by weight. Phosphoric anhydride in exhaust gases is 2.2 mg / m. The goal is achieved while maintaining the velocity of gases during hydration 16-22 m / s and the density of irrigation with circulating phosphoric acid. and water in 180 - ZOOmVm h. 2 Table. 9 (L 4 and 00

Description

The invention relates to the technology of production of thermal phosphoric acid, used as a feedstock in the preparation of fertilizer, technical and feed phosphates.

The aim of the invention is to reduce the content of phosphoric anhydride in the waste gases from the hydration stage.

The molten phosphorus from the dosing units in the amount of 2.6 t / h is fed to the nozzle of the combustion tower. Phosphorus is burned at an excess air ratio of / 2. Seven type 380 percent circulating phosphoric acid with a temperature of 380 is fed to the bowl located in the upper parts of the combustion tower, and in the amount of 220 - at the nozzles, located in the middle part of the tower. The bowl also serves 8 m / h acid from the hydration stage with a concentration of 45% and a temperature of 50 ° C. Gases with a temperature of 100 ° C, containing phos-. Formate anhydride in the amount of 71 g / m, are fed from the combustion tower to the hydration tower in the amount of 21,000. The gas flow velocity in the contact zones of the hydration tower is maintained at 16 m / s. Pervy along the gas flow, the lower contact zone is irrigated with chilled to phosphoric 45% acid, and the upper, second gas flow, contact zone is irrigated with water. The consumption of acid and water supplied to the contact zones is 160, taking into account their circulation, which, when the diameter of the contact zone is 0.85 m, corresponds to an irrigation density of 280. The degree of trapping of phosphoric anhydride is 99.99% by weight, the content of phosphoric anhydride in exhaust gases is 2.2 mg / m1: According to the known method of ipocTb gases at the hydration stage, 0.84 m / s.

Consumption of water, O, 08–0.1 kg / m of gas (or 1.68), circulating flow rate, phosphoric acid, 3-5 kg / m (or 100). The content of phosphoric anhydride in exhaust gases from the hydration stage is 18.19 mg / m.

Table I shows the dependence of the content of phosphoric anhydride in the exhaust gases, depending on the velocity of the gases.

Table 2 presents the dependence of the content of phosphoric anhydride in the exhaust gases depending on the density of the irrigation of gases.

Thus, using the proposed method of producing phosphoric acid allows reducing the content of phosphoric anhydride in the exhaust gases to 2.2-14, Omg / m due to the proposed mode of introduction of the process in the second stage, resulting in an additional 14-20 t / g 75% phosphoric acid. In addition, the use of the proposed method eliminates the need to build high exhaust pipes to provide the required value; MPC in the surface layer, as well as the construction and operation of electric precipitators to trap the phosphoric acid of the phosphoric acid, which cost up to 30% of the estimated the cost of a circulating 2 tower system for the production of phosphoric acid with a capacity of 2.5-3 t / h according to Pi05. The operating costs for the maintenance of equipment are reduced by 10-15%, and the course of electric power - by 8 kW, h / t phoskisloty.

Claims (1)

Invention Formula A method of producing thermal phosphoric acid, which involves burning elemental phosphorus, followed by cooling the resulting gases and hydrating phosphoric anhydride first with circulating phosphoric acid, and then with water, so as to reduce the content of phosphoric anhydride in the waste water. from the stage of hydration to gases, circulating phosphoric acid and the gas is supplied in an amount that provides irrigation density of 180-300 and gases are fed at a speed of 16-22 m / sL 99.89 99,975 99,997 99,993 99.9865 99,976 99,959 99,935 87.1 17,8 2.2 5.0 9.6 14.0 29.0 46.1 83.5 47.5 28.4 18.5 12.0 5.8 2.2 2.0 1.8 VNIIPI Order-670/27 Random polygons Ave, Uzhgorod, st. Project, 4 99,882 99,933 99,960 99,974 99,983 99,992 99,997 99,9971 99,9973 99,9975 Circulation 446 Subscription