RU2279401C2 - Hydroxylamine sulfate production process - Google Patents

Abstract

FIELD: industrial organic synthesis.

SUBSTANCE: hydroxylamine sulfate (starting material in production of caprolactam) production process comprises: preparing reaction mixture of ammonia, oxygen, and water steam; catalytically oxidizing ammonia at pressure above 0.3 MPa; stabilizing composition of nitrose gas via hydrogenation of silver-manganese catalyst; concentrating nitrose gas by means of water steam condensation; combining concentrated nitrose gas with hydrogen and mixture of sulfuric acid, distillate produced in nitric acid condensate concentration, a part of secondary steam condensate produced during concentration of hydroxylamine sulfate, and catalysate remaining after catalytic hydrogenation of nitric acid contained in concentrated nitric acid condensate; catalytically hydrogenating nitric acid; and synthesis of hydroxylamine sulfate. Invention is characterized by that, (i) for concentration of nitric acid condensate to weight percentage of nitric acid 8%, heat of water steam condensation proceeding during concentration of nitrose gas is used; and (ii) hydroxylamine sulfate solution is concentrated to weight percentage 38% using heat of condensation of distillate vapors produced during concentration of nitric acid condensate in distillation column.

EFFECT: reduced power consumption at the same specific intake of raw materials.

1 dwg, 1 tbl

Description

The invention relates to the chemical industry, and in particular to a method for producing hydroxylamine sulfate used in the production of caprolactam.

In the production of hydroxylamine sulfate (HAC), concentrated nitrogen monoxide is required, the production of which by catalytic oxidation of ammonia in the presence of water vapor is inevitably accompanied by the formation of dilute solutions of nitric acid. Disposal of dilute nitric acid solutions results in significant capital and operating costs.

A known method of producing a HAS, including the preparation of a reaction mixture of ammonia, oxygen and water vapor, catalytic oxidation of ammonia, stabilization of the composition of nitrous gas by hydrogenation on a silver-manganese catalyst, its two-stage concentration by condensation of water vapor [see US Pat. RF №2045471, IPC ⁶ С 01 В 21/14, op. 10/10/1995, Bull. No. 28]. At the first stage of concentration of nitrous gas, about 70% of the condensate containing nitric acid with a mass fraction of up to 0.3% is isolated, and at the second stage, nitric acid with a mass fraction of up to 5-6% is formed. The condensate of the first stage is directed to the dilution of sulfuric acid. The condensate of the second stage after evaporation to 40-45 wt.% Is heated to 300 ° C and mixed with the main stream of nitrous gas entering for stabilization, and water vapor is sent to prepare a mixture of ammonia, oxygen, steam.

The specified method allows you to utilize dilute solutions of nitric acid, providing waste-free technology for the production of gas, but is difficult to manage and not sufficiently reliable in operation. In addition, in the process of two-stage condensation of water vapor contained in a nitrous gas, the heat generated in this process is irrevocably lost.

The closest in technical essence and the achieved effect to the claimed is a method for producing hydroxylamine sulfate, including the preparation of a reaction mixture of ammonia, oxygen and water vapor, catalytic oxidation of ammonia, stabilization of the composition of nitrous gas by hydrogenation on a silver-manganese catalyst, concentration of nitrous gas due to condensation of water vapor , mixing concentrated nitrous gas with hydrogen, a mixture of sulfuric acid, water, condensate of the first concentration stage n troznogo gas catalyzate after the catalytic hydrogenation of nitric acid, nitric acid, catalytic hydrogenation, and synthesis GAS [see. EPO application No. 945401, IPC ⁶ C 01 B 21/14, op.29.09.1999 - prototype]. In this case, a two-stage concentration of nitrous gas is also carried out. It differs from the above in that the condensate of the second stage of concentration of nitrous gas is hydrogenated in the presence of a platinum catalyst. The resulting catalysate containing nitric acid with a mass fraction of more than 0.45% is also used to dilute sulfuric acid. Thus, non-waste technology for producing GAS is achieved. As in the above method, the heat generated during the condensation of water vapor nitrous gas is lost irrevocably. In addition, the oxidation of ammonia at a pressure close to atmospheric, leads to the necessity of compression of nitrous gas, which increases the cost and complicates the management and regulation of the process of production of gas.

The complexity of disposal, as a rule, is associated with a relatively low mass fraction of nitric acid in the condensate of the second stage. The consequence of this is a significant fluctuation in the concentration of the catalyst in the hydrogenation reactor, since it is continuously discharged from the reactor together with the catalyst, and is periodically returned to it from the filter. And since the performance of the reactor is proportional to the concentration of the catalyst, the amount of nitrogen monoxide entering the HAS synthesis stage also fluctuates, which complicates the regulation of the process.

The objective of the present invention is to improve the method of producing GAS by changing the scheme and process parameters together so as to reduce capital and energy costs for the manufacture of the product, as well as to simplify process control and regulation.

The problem is solved in that in a method for producing hydroxylamine sulfate, including the preparation of a reaction mixture of ammonia, oxygen and water vapor, catalytic oxidation of ammonia, stabilization of the composition of nitrous gas by hydrogenation on a silver-manganese catalyst, concentration of nitrous gas by condensation of water vapor, mixing concentrated nitrous gas with hydrogen, a mixture of sulfuric acid, catalysis after catalytic hydrogenation of nitric acid, catalytic hydrogenation of nitrogen acid and GAS synthesis, according to the invention, the catalytic oxidation of ammonia is carried out under a pressure of more than 0.3 MPa, the concentration of nitrous gas is carried out in a distillation column with the supply of nitrous gas to the boiler of the distillation column, where the nitric acid condensate is concentrated to a mass fraction of nitric acid up to 8% due to heat of condensation of water vapor during the concentration of nitrous gas, the heat of the gaseous distillate formed in this case is used to concentrate HAS to a mass fraction of 38%, and the distillate itself, and also a part of the secondary vapor formed during concentration of the HAS in the form of condensates is used to dilute sulfuric acid, nitric acid condensate with a mass fraction of nitric acid up to 8% is subjected to catalytic hydrogenation.

The implementation of the catalytic oxidation of ammonia under a pressure of more than 0.3 MPa eliminates the stage of compression of nitrous gas. This simplifies the coordination of the stages of the catalytic oxidation of ammonia and synthesis of HAS and automatic process control, significantly reduced capital costs.

Due to the use of heat of condensation of water vapor during the concentration of nitrous gas, the concentration of nitric acid condensate (ACC) and the HAC solution to the selected process parameters makes it possible to achieve a reduction in energy costs for the manufacture of the final product.

The implementation of the claimed method is illustrated by the diagram shown in the drawing.

The method is as follows.

To obtain 1 ton of hydroxylamine (GIAM) per hour in mixer 1, a reaction mixture of 681.5 kg / h of ammonia, 1711.3 kg / h of oxygen and 3352.4 kg / h of water vapor is prepared and sent to reactor 2, where platinum nets carry out vapor-oxygen conversion of ammonia under a pressure of more than 0.3 MPa (for example, 0.3-0.35 MPa). The resulting nitrous gas (NOx) is cooled in the boiler part of the reactor to a temperature of 260 ÷ 280 ° C, mixed in a mixer 3 with hydrogen and sent to a reactor 4 to stabilize the composition. Here, excess oxygen on a silver-manganese catalyst is hydrogenated into water. The stabilized nitrous gas is cooled to a temperature of 150 ° C in the boiler part of the reactor 4. The heat of the reactions of oxidation of ammonia and hydrogenation of oxygen is used to produce steam. The resulting nitrous gas then enters the boiler 5 of the nitric acid condensate distillation column 8, where it is concentrated by condensation of water vapor with the release of nitric acid condensate (ACC). The condensation heat of water vapor during the concentration of nitrous gas in the boiler 5 is used to concentrate in a distillation column 8 ACC from a mass fraction of 1.4% to a mass fraction of 8%. The gaseous distillate formed in this process, containing nitric acid with a mass fraction of up to 0.25%, enters the heat exchanger 9, where a GAS solution with a mass fraction of about 24% is supplied as a cooling liquid. The HAS solution heated by condensation of the water vapor of the distillate goes further to the separator 10, where water vapor is evaporated from the solution at a temperature of 85 ° C under vacuum. The concentrated solution contains HAS with a mass fraction of about 38%. Nitrous gas after the boiler 5 of the distillation column 8 enters the heat exchanger 6, where the residual water vapor is condensed to form nitric acid condensate with a mass fraction of 1.4% and the concentrated nitrous gas is cooled to 40 ° C, then it is purified from nitric oxide (IV) in a scrubber 7 and is fed to stage 14 of the synthesis of HAS in the amount of 1066.1 kg / h The condensed distillate with a mass fraction of nitric acid of 0.25%, as well as part of the secondary steam (VP) after the separator 10 and the condenser of the secondary steam 11 are sent to dilute concentrated sulfuric acid in stage 12, and the bottom residue from the distillation column 8 with a mass fraction of nitric acid 7, 8% in the amount of 660.7 kg / h (52.8 kg / h of nitric acid monohydrate) is fed to the liquid-phase hydrogenation unit 13 in the presence of a platinum catalyst. The resulting nitrogen monoxide in an amount of 23.6 kg / h in a mixture with hydrogen is sent to stage 14 of the synthesis of HAC, and the catalysis containing nitric acid with a mass fraction of about 0.5% is used to dilute sulfuric acid. Tail gases (CG) of HAS synthesis reactors are sent for incineration in a recovery plant 15.

The table shows data illustrating the operation of the GAS installation according to the claimed method and prototype.

As can be seen from the table, the specific costs of raw materials for the manufacture of the product are almost the same, however, in the present method, the stage of compression of nitrous gas is excluded and GAS is obtained with a mass fraction of 38% instead of 24.6% without additional energy costs; At the hydrogenation stage, nitric acid is used with a mass fraction of 8% instead of 3.56%, which simplifies the regulation of the process.

Table NH ₃ O ₂ H ₂ O NO from ap. 7 NO from mouth 12 NO in Art.14 H ₂ on the hydr.O ₂ H ₂ in Article 14 H ₂ mouth 13 ∑H ₂ % HNO ₃ in mouth 13 % GAS Unit. kg / h kg / h kg / h kg / h kg / h kg / h kg / h kg / h kg / h kg / h % % According to the prototype (application EPO No. 945401) 680 1707 3345 1071 21 1092 15,5 128.1 2.0 145.6 3.56 24.6 According to the claimed method 681.5 1711.3 3352,4 1066.1 23.6 1092 16.6 128.1 2,3 147 8 38

Claims (1)

A method for producing hydroxylamine sulfate (HAC), including the preparation of a reaction mixture of ammonia, oxygen and water vapor, catalytic oxidation of ammonia, stabilization of the composition of nitrous gas by hydrogenation on a silver-manganese catalyst, concentration of nitrous gas by condensation of water vapor, mixing concentrated nitrous gas with hydrogen, a mixture of sulfuric acid, catalysis after the catalytic hydrogenation of nitric acid, the catalytic hydrogenation of nitric acid and the synthesis of HAS, distinguishing Due to the fact that the catalytic oxidation of ammonia is carried out under a pressure of more than 0.3 MPa, the concentration of nitrous gas is carried out in a distillation column with the supply of nitrous gas to the boiler of the distillation column, where the nitric acid condensate is concentrated to a mass fraction of nitric acid up to 8% due to condensation heat water vapor during the concentration of nitrous gas, the heat of the gaseous distillate formed in this case is used to concentrate HAS to a mass fraction of 38%, and the distillate itself, as well as part of the formed ntrirovanii GAS vapor condensates as used for diluting sulfuric acid, nitric acid condensate from the weight fraction of nitric acid and 8% is subjected to catalytic hydrogenation.