UA33681C2 - Method for production of ammonium nitrate and tubular reactor for exothermic reactions - Google Patents

Abstract

Invention relates to the technology of production of ammonium nitrate lye on chemical equipment and it may be used for production of fertilizers. Neutralization of 50-56 per cent by weight of nitric acid by ammonia is made in tubular reactor under pressure of (6-7)102 kPa at the temperature of 170-180 °C in the flow of carrier solution, for example 64-75 per cent by weight of alkali solution of ammonium nitrate that is circulating in closed circuit: reactor - heat-exchanger - pump - separator - reactor. Evaporation of ammonium nitrate solution using heat of neutralization of carrier solution circulating from neutralization stage. Tubular reactor for exothermic reactions is additionally equipped with distribution chamber and device for liquid supply that together with a pipe is connected in tube space. The device includes a vertical cylindrical shell, inlet chamber limited by a cover with connecting pipe, and mixing chamber formed by transfer cone, shell and tube plate in which vertical tubes are fixed by one end.

Description

Description of the invention

The invention belongs to the field of production of ammonium nitrate liquors (lyes) on chemical equipment, it can be used in the production of mineral fertilizers.

A method of obtaining ammonium nitrate is known, which includes the neutralization of 40-6095 nitric acid with ammonia at a temperature of 180-1907С in volume ratios of 1: 2-1: 20 to pH - 6.0: 6.5, evaporation of the resulting ammonium nitrate solution under vacuum from a concentration of 24-4495 to 60-6595. The method is used for the decomposition of organic impurities contained in the by-products of caprolactam production, it allows 70 to convert unstable forms of nitrate compounds into a stable form, foaming at the evaporation stage is reduced. |1.

A.s. USSR Mo 490750, MKV СО1С 1/18, overprint. 05.11.75 BV Mo 41).

The method does not provide for the use of heat of neutralization, and a finished product of low concentration is obtained.

There is a known method of obtaining a solution of ammonium nitrate and water vapor, which includes the neutralization of unconcentrated nitric acid (57-6095) preheated to 1357"C with ammonia from Her - 135727 at an elevated pressure of 2-8.5KG/cm? (or (2-6, 5) 2102kPa| ii - 170-190 with the production of juice vapor and a diluted solution of ammonium nitrate, which are further evaporated by throttling to atmospheric pressure or by blowing with a flow of preheated original ammonia, the formation of water vapor in the heat exchanger by evaporation of water due to the heat of the neutralization reaction. The heat exchanger is placed in in the neutralization zone, the juice vapor after neutralization is directed to the heating of the starting reagents. The method is carried out according to a scheme that includes heat exchangers, a reactor-neutralizer with a boiler-utilizer installed in the middle, a juice vapor evaporator, a throttling device, an apparatus for cleaning the juice vapor by pseudorectification, a concentrator, supply lines initial/intermediate reagents and release of product streams allows the production of water vapor with PRESSURE (9-12) x 102 kPa, and juice vapor when using unconcentrated nitric acid. The resulting solution of ammonium nitrate is used for the production of liquid complex nitrogen-containing fertilizers or granular o) ammonium nitrate in fluidized bed granulators. (2. Academy of Sciences of the USSR Mo1372853, MKV СО1С 1/18, printed on November 30, 1984).

The disadvantages of the known method are: obtaining 9095 ammonium nitrate; reducing the safety of the process by installing a recovery boiler in the middle of the reactor and introducing a steam-ammonia mixture into the reactor. "-- zo The well-known reactor of catalytic processes with an exothermic effect contains a case with end caps, technological fittings, heat exchange elements, made in the form of coaxially located pipes of different lengths, which are fixed in a pipe grid, which has perforations for uniform distribution along the cross-section of the apparatus, " o heat carriers enter the pipes from separate distribution chambers, exits from the common one, the ratio of the lengths of the pipes of the heat exchange elements is 2: 1-3: 1. The reactor is used in the petrochemical and oil refining industry to carry out processes in the stationary catalyst layer. FROM. Application of the Russian Federation Mo so 93039632, IPC VO1) 8/06, printed. 27.06.96, BV Mo 183).

The production of ammonium nitrate does not require the presence of a catalyst and a perforated pipe grid. Conducting the process in heat exchange elements, which are made in the form of concentrically located pipes of different lengths, makes the reaction zone elongated and inefficient in terms of using the heat of the exothermic reaction - "20 neutralization." The closest in technical essence and the result that is achieved is the method of obtaining ammonium nitrate, which includes the neutralization of 60-6595 nitric acid (i - 30"C) with ammonia (Ii - 10"C) at a temperature of 180-1857C and pressure above the saturated vapor pressure of 5-babs.bar./ or (5-6)x102kPa, evaporation of the formed ammonium nitrate solution using the heat of the solution that circulates from the neutralization stage, in the formed ammonium nitrate solution, before evaporation, the pressure is reduced to the evaporation pressure , the amount of circulating solution is selected d) under the condition of maintaining the imposed temperature and pressure regimes of the neutralization stages. The method is carried out according to a scheme that includes a reactor, which is made in the form of a continuous apparatus with an internal overflow device, a remote device consisting of a pipeline and a refrigerator, connected to the upper part for regulation

Ф of pressure in the reactor, pipelines, reducing valve, evaporator (single or multistage), steam evaporator, 5p pumps, hydraulic valves, capacity, condenser, header, vacuum pump, heat exchanger for obtaining heating

So steam, heat exchangers for heating ammonia and nitric acid, washer (single or multi-stage). (4. - M Patent of the USSR Mo 1367853, MKV СО1С 1/18, printed 15.01.88. BV Mo2 - prototype of the method).

Disadvantages of the prototype of the method are as follows: - the circuit along which the ammonium nitrate solution circulates includes an evaporator (single/multistage) and a heat exchanger for obtaining heating steam, that is, 2 additional devices. - the evaporator allows the use of excess heat, but only if there are 2 or more stages, iF) which complicates the design, prolongs the circulation of the solution along the circuit; co - the use of nitric acid of 60-6595 concentration at a pressure of (5-6) "102kKPa leads to a decrease in the coefficient of useful use of the heat of neutralization and a decrease in steam pressure. 60 The closest in design is a reactor for heterogeneous catalysis, which contains a vertical cylindrical body with end caps, technological nozzles for the input and output of material flows, internal reaction tubes placed along and attached to the upper and lower perforated tube boards, with concentrically installed central tubes, which are perforated along the entire length and blocked at the ends in the direction of the gas flow, the inlet and outlet chambers are placed, respectively, above and below the tube boards and are limited by end caps, the spaces between the reaction tubes and the central tubes are filled with solid catalyst particles. |5. Ass. USSR Mo1699584, MKI VO1)8/06, printed on 12/23/91. BV Mo47-prototype reactor).

Disadvantages of the reactor prototype are as follows: - the placement of central tubes along the entire length in the reaction tubes leads to an unjustified increase in the metal capacity of the structure, a decrease in the efficiency of the neutralization process due to the leakage of ammonia that did not react with nitric acid, and a deterioration in the quality of the finished product; - it is necessary to install an additional apparatus for cooling ammonium nitrate after the reactor.

The basis of the invention is the task of improving the method of obtaining ammonium nitrate and the tubular reactor for carrying out exothermic reactions by neutralization with ammonia at a temperature, under the pressure of /o nitric acid, which is supplied in the flow of the coolant solution, reducing the pressure in the formed ammonium nitrate solution to the pressure evaporation, evaporation of this solution using the heat of neutralization from the solution, which circulates from the neutralization stage in a closed circuit, which, together with the structural elements of the tubular reactor, eliminates the consumption of additional heat at the evaporation stage, ensuring long-term, safe operation in the optimal technological mode with the achievement of high concentration finished product.

The set task is achieved by the fact that in the method of obtaining ammonium nitrate and the tubular reactor for carrying out exothermic reactions, the neutralization of nitric acid with ammonia is carried out at a temperature of 170-180" under pressure, reducing the pressure in the formed ammonium nitrate solution to the evaporation pressure, evaporating this solution with using the heat of neutralization from the solution that circulates from the neutralization stage along the circuit, the amount of circulating solution is selected under the conditions of maintaining the imposed temperature and pressure regimes of the neutralization stage, according to the method, the neutralization of 50-5 bmas.bo of nitric acid in the flow of the coolant solution is carried out in a tubular reactor under a pressure of (6-7)010 "kPa, for example, 64-75 mass.9 solution of lye (lye) of ammonium nitrate, which circulates in a closed circuit: reactor-heat exchanger-pump-separator--reactor.

The reactor contains a vertical cylindrical body with end caps, technological fittings and heat exchange elements, internal reaction tubes, which are placed along and attached to the tube boards, central perforated tubes are concentrically installed in the Ga reaction tubes, blocked at the ends along the gas flow, inlet and outlet chambers , limited by pipe boards and end caps, according to i) device, the central tubes of the reactor, fixed in the pipe board, are in the reaction pipes at (3-4)00,, the perforation area is equal to 1.57j0/4 at the perforation height (3- 4) P0, the diameters are connected by the ratio a: - 1-1.5-2.5, where O is the diameter of the reaction tubes, and is the diameter of the central tubes, the number of reaction zones, which is equal to the number of tubes, is determined by the productivity, the input of the reaction tubes flows are carried into the central tubes from the input chamber, into the reaction tubes from the distribution chamber formed by a shell, one end of which is installed with a gap above the end cover, the other and - attached to the reactor tube board, reactor. (O is additionally equipped with a fluid supply unit that connects the inter-tube and pipe spaces with a pipeline, contains a vertical cylindrical sleeve, an inlet chamber limited by a cover with a fitting and a mixing chamber formed by a transition cone, a sleeve and a pipe board, in which vertical tubes are fixed at one end tubes

Neutralization under pressure (6-7). 102kPa tubular reactor allows you to reduce the concentration of nitric acid from 57-6095, 60-65905 to 50-5695, increase the coefficient of useful use of the heat of neutralization, which eliminates ammonia overheating, reduce the aggressiveness of the acid and extend the service life of the reactor circulation of the solution-heat carrier with a concentration of 64-7590 along a closed loop: reactor-heat exchanger-pump-separator-reactor. o, c Heat exchange elements perform two functions: "» - each reaction tube works as a mini-reactor constructed as a pipe in a pipe; " - its main heat exchange function, regarding the removal of exothermic heat from the outer walls of the reaction tubes, which does not require an additional cooling device. Central tubes perforated at a height of (3-40) with a perforation area of 1.Bla/4 and inserted into the reaction tubes at (3-4).0 are necessary and sufficient conditions for full contact of gaseous and liquid phases without gas leakage.

Ha Cylindrical shell, the main structural element of the distribution chamber, ensures a uniform direction of flows in all reaction tubes, removing dynamic tension from the area of the central tubes.

Me In the liquid supply unit, a safe technological mode of mixing of liquid phases is achieved, which ensures

Ho) 20 stoichiometrically complete homogeneity of the resulting mixture.

The entire set of proposed technical methods and structural elements allows for a long time to work in an optimal technological mode, achieving a high yield of the finished product when using exothermic heat of neutralization in its own production at the residue stage - without third-party coolants. 29 The essence of the invention is explained by the drawings, where:

F! Fig. 1 shows a scheme for obtaining ammonium nitrate, Fig. 2 shows a longitudinal section of a tubular reactor for carrying out exothermic reactions. o Examples of specific execution of the method and comparative characteristics with analogues and prototype are presented in the table. 60 The diagram (Fig. 1) shows: P7 - tubular reactor, T2 - acid heater, (TZ - ammonia heater, as needed), NR - circulation pump, T4 - heat exchanger and C8 - separator of the 2nd stage, 05 - circulation separator,

T6 - heat exchanger and C7 - separator of the 1st stage, E9 - hydraulic valve.

The tubular reactor (Fig. 2) for carrying out exothermic reactions contains a vertical cylindrical body 1 with end caps 2 and 3, technological fittings 4, 5, 6, 7, 8 and 9, reaction pipes 10, which are placed along and attached to the pipe boards 11,12, central tubes 13 with perforations 14 are installed in the reaction tubes 10 concentrically, blocked at the ends in the direction of the gas flow, one end is fixed in the tube board 15, the inlet and outlet chambers are limited by the tube boards 11,12 and end caps 2,3 , a distribution chamber 16 formed by a shell 17, one end of which is installed with a gap above the pipe board, the other is attached to the pipe board 11, fittings 5, 7 and 8, which connect the inter-pipe 18 and pipe 19 spaces of the reactor, united by a pipeline 20 into the fluid supply unit, which contains a cylindrical shell 21, a cover 22 with a fitting 7, a transition cone 23, an inlet chamber limited by a cover 22, a mixing chamber 24 formed by a cone 23, a shell 21 and a tube board 25, in which one vertical tubes 26 are fixed by ntem.

The method of obtaining ammonium nitrate using a tubular reactor for carrying out exothermic reactions 7/0 (examples 1-3) is carried out as follows: To fill the circulation circuit for heat recovery 64-7090 ammonium nitrate solution with a temperature of 140-143 from the separator C5 with a pressure pump (6-7). 102 kPa is supplied through the inlet fitting 4. inter-tube space 18 of the tubular reactor RI, outlet fitting 5, mixing chamber 24, pipeline 20, distribution chamber 16, reaction pipes 10 (16-25 pcs. Y - 80-125 mm), outlet chamber, fitting 9 of the outlet from the reactor to the suction of the circulation pump NZ. Then, circulating in a closed loop at 75, the solution of lye (lye) of ammonium nitrate is mixed with 50-5690 nitric acid (after the heater T2 with i - 50"С), which enters through the fitting 7 of the liquid supply unit, the inlet chamber, the vertical tubes 26 (8- 12 pcs. 2; - 20-32mm), in the mixing chamber 24, the mixture is sent from the distribution chamber 16 to the reaction zone of the reactor through the pipeline 20. At the same time, gaseous ammonia is supplied through the inlet fitting 6, under pressure (6-7).102 kPa (from - 30-907С through the technological pipeline of ammonia production, or after the TK heater) through the central tubes 13 (16-25 pcs. Y - 50-8Ω), through the perforation 14 (area 3000-7500mm), into the reaction zone with a height of 240-500mm . Ammonia neutralizes the acid circulating in the flow of the coolant solution with the release of excess heat, which is removed from the outer surface of the reaction tubes 10 by the ammonium nitrate solution circulating in the intertube space 18. The superheated solution with a concentration of 64-7595 and a temperature of 170-1807С along the tubes 10, through the outlet chamber, the fitting 9 enters the heat exchanger T4, giving part of the heat of the SM to evaporation, and the circulation separator 05. In the separator under pressure (1.5-2.03010 "kPa, the solution expands, Ge) boils, the resulting juice vapor is separated from the solution and enters for heating the heat exchanger 16 and the heater T2 of nitric acid (TZ - ammonia as needed), the excess juice steam is diverted to the network for internal needs. Part of the solution from the separator C5 enters the suction of the NZ pump, forming a circulation circuit: -Р1-74-С5-НЗ3-Р1-, and the product flow of the solution with a concentration of 72-75 95 enters T6b, then - the vapor-liquid mixture is separated in the separator 07 under P - Z00kPa. The juice vapor is discharged into the network, the solution with a concentration of 82-8595 enters the heat exchanger T4, then into the separator C8, where the juice vapor is separated at a pressure of 15576 and discharged into the network, the solution is fed into the melt evaporation apparatus, where it is concentrated to CO 99, 0-99.7956 and sent to granulation. The amount of gaseous ammonia required for co-neutralization is determined by the productivity of the tubular reactor, the amount of nitric acid is in

From the stoichiometric dependence on ammonia supplied to the reactor. and)

The pressure limits of the neutralization process are selected in the range of 600-700 kPa (table). The upper one is limited by the economic feasibility of obtaining ammonium nitrate of high concentration, necessary for its further use.

The lower limit is the use of diluted nitric acid and obtaining juice vapor, the necessary parameters. "

The closed circuit -reactor-heat exchanger-separator-pump-reactor-, chosen with minimal capital costs, because the devices working in the known production of ammonium nitrate production are used. c) c Thus, the proposed method of obtaining ammonium nitrate and the construction of a tubular reactor for "" carrying out exothermic reactions allow the process of neutralization of nitric acid with gaseous "ammonia with the formation of ammonium nitrate lye (lye) in a sufficiently safe mode, because the reactor is a mini -reactors, the number of which is equal to the number of tubes, each of which is cooled by the circulating solution of liquors (alkalis), giving off the heat of the reaction in the circulation circuit to the residue of newly formed liquors (alkalis), and reducing the thermal stress of the tubes and dynamic load. (95) b

Claims (2)

The formula of the invention is 50 1. The method of obtaining ammonium nitrate in a reactor, which includes the neutralization of nitric acid with ammonia under pressure, at a temperature of 170-1807C, reducing the pressure in the formed ammonium nitrate solution to the evaporation pressure, evaporating this solution using the heat of neutralization from the solution, which circulates from the neutralization stage along the circuit, the amount of the circulating solution is selected under the conditions of maintaining the imposed temperature and pressure regimes of the neutralization stage, which is distinguished by the fact that the neutralization of nitric acid, which is supplied in the flow of a heat carrier solution circulating along a closed circuit, is carried out in a tubular reactor . eat) 2. The method according to claim 1, which differs in that the neutralization of 50-56 wt.95 of nitric acid is carried out under a pressure of (6-7)102 kPa in the flow of a coolant solution, for example, 64-75 wt.95 of a solution of lye (lyes) of ammonium 60 nitrate circulating in a closed circuit: reactor-heat exchanger-pump-separator-reactor. C. A tubular reactor for conducting exothermic reactions, which contains a vertical cylindrical body with end caps, process fittings and heat exchange elements, internal reaction tubes, which are placed along and attached to the tube boards, in the reaction tubes concentrically installed central perforated tubes, plugged at the ends by of the gas flow, the inlet and outlet chambers are limited by pipe boards and end caps, which differs in that the central tubes of the reactor are fixed in the pipe board, are in the reaction pipes at (3-4)00, the perforation area is 1.5- - a/4 at the height of the perforation (3-Д00О, the diameters are connected by the ratio 4:О - 1-1, 522.5, where: О is the diameter of the reaction tubes, а is the diameter of the central tubes, the number of reaction zones, which is equal to the number of tubes , is determined by the performance, the input of the reaction flows is carried out into the central tubes from the inlet chamber, into the reaction tubes - from the distribution chamber, the reactor is additionally equipped with a node n return of the liquid, which in the pile with the pipeline connects the inter-pipe and pipe spaces. 4. Tubular reactor according to item C, which is characterized in that the fluid supply unit contains a vertical cylindrical sleeve, an inlet chamber limited by a cover with a fitting and a mixing chamber formed by a transition cone 70, a sleeve and a tube board, in which vertical tubes are fixed at one end . 5. Tubular reactor according to claim 3, which is characterized by the fact that the distribution chamber is formed by a pipe, one end of which is installed with a gap above the end cover, the other is attached to the reactor tube board. с шчи 6) «- с (Се) со со - with . and? (95) (95) (22) o 50 - F) ime) 60 b5