WO2009075608A2

WO2009075608A2 - Method for controlling caprolactam production

Info

Publication number: WO2009075608A2
Application number: PCT/RU2008/000755
Authority: WO
Inventors: Anatoly Petrovich Boldyrev; Victor Ivanovich Geracimenco; Anatoly Arcadevich Ogarcov; Sergey Vitalevih Ardamakov
Original assignee: Joint Stock Company Kuibyshevazot
Priority date: 2007-12-10
Filing date: 2008-12-08
Publication date: 2009-06-18
Also published as: RU2007145679A; WO2009075608A3; RU2366651C1; WO2009075608A9

Abstract

The invention relates to caprolactam production methods and can be used for processing benzol and phenol, cyclohexane, cyclohexanol and cyclohexanone followed by subsequent oximation and transformation of cyclohexanonoxime into caprolactam. The combination of an oxidation method for transforming benzol into caprolactam and a method for producing caprolactam according to a phenolic procedure makes it possible to increase the productivity and improve the quality of caprolactam. The combined method allow to use benzol and phenol taking into account the preproduction phase and the caprolactam delivery to customers.

Description

The method of controlling the production of caprolactam

The alleged invention relates to methods for

caprolactam and may find application in the processing of ben¬

ash, phenol, cyclohexane, cyclohexanol, cyclohexanone with

subsequent oximation, isomerization of cyclohexanone -

Xima and shipment of caprolactam to the consumer.

A known method of controlling the process of obtaining caprolac

tam, in which the pH of the reaction medium is adjusted in

a reactor with a correction for the flow rate of the product rearrangement.

To increase the yield of caprolactam, the concentration is measured

ammonium sulfate and acidity rearrangement and correction

They control the supply of ammonia water and gaseous ammonia to the reaction

torus. (Aut. Testimonial Xe 1648946, B C 07 D 201, G 05 D 27/00 dated 05.24.89)

The downside of management is the limited ability

increase caprolactam performance. A known industrial method for producing caprolactam with the processing of cyclohexanone into caprolactam. The benzene feedstock is subjected to hydrogenation, oxidation, rectification, and then cyclohezanone is sent to oximeting. The obtained cyclohexanone oxime is sent for isomerization for rearrangement, and then the organic layer (lactam oil) and the inorganic layer (ammonium sulfate) are separated in a sump, and sent to a neutralizer for purification of caprolactam whole, or for extraction with organic solvents. (Edited by V. Ovchinnikov and V. P. Rushinsky, “Production of caprolactam”, M. Chemistry 1977, Chapters 2,3,9).

The disadvantage of production is the low quality of caprolactam and low productivity when used only in the scheme of one benzene.

The closest is a method for controlling the process of producing caprolactam, including distillation columns, producing cyclohexane by oxidation of benzene and directing cyclohexanone rectified to an oximeting unit, pegging and neutralization reactors, and then to a caprolactam isolation and purification unit. Cyclohexanone rectified They are controlled by changing the temperature conditions in the columns, and the acidity of the rearranged product is regulated by the supply of oleum.

(Pat. RF JVB 2043340 dated 09/10/95, C 07 D 201/04, G 05 27/00)

The disadvantage is the low productivity of the installation and the deterioration of the quality of caprolactam by microimpurities when using benzene as a monomer. In addition, the total load, the load distribution by monomers for the first and second lines are not taken into account, the caprolactam load for consumers is not taken into account.

The objective of the proposed invention is to increase productivity and improve the quality of caprolactam, as well as expanding the scope.

The problem is solved in that in the method of controlling the production of caprolactam from benzene, carried out in a unit with one production line, including units for the hydrogenation of benzene and hydrogen, oxidation of cyclohexane with oxygen, rectification of cyclohexanone, oxidation of hydroxylamino sulfate, rearrangement of cyclohexanone oxime oximenoxime and mixer caprolactam, which are interconnected by pumps,

pipelines with sensors and valves for adjusting the consumption of benzene, hydrogen, cyclohexanone, hydroxylamine sulfate, oleum, an acid index sensor and a caprolactam pH meter, the unit additionally contains a second production line, including the units of hydroxylamine cyclosulfane oxylamoxylamino sulfate oximation and reagent formation, pumps and pipelines with sensors and flow valves of hydroxylamine sulfate, oleum, acidity sensor and pH meter prolactam, and also contains a block of hydrogenation of phenol and hydrogen with a pump, sensors and valves and the supply of cyclohexanol to the dehydrogenation block with a circulation circuit, including: a pump-block of dehydrogenation of cyclohexanol-rectification block-pump connected by pipelines; a benzene-phenol ratio device connected pipelines with units for the hydrogenation of benzene and phenol and oxygen oxidation and a dehydrogenation unit; a cyclohezanone distribution device for oxime blocks connected by pipelines to rectification blocks and through a mixing tank of cyclohexanone with oxime blocks; a device for dispatching crystalline and liquid caprolactam, connected by a pipe to a caprolactam mixer and a crystalline caprolactam concentrator and a liquid liquid container; in this case, the total load for the liquid is set; benzene-phenol reduction; distribution of cyclohexanone to the oxime blocks; shipment of crystalline and liquid caprolactam to the consumer and the flow rates of benzene, phenol, hydrogen, cyclohexanone, hydroxylamine sulfate, oleum are adjusted accordingly by acting on the corresponding valves.

In this case, the hydrogenation of benzene and hydrogen is carried out in two series-connected reactors and adjust the process temperature in the range 160 -230 ° C and pressure up to 0.8 MPa. with recirculation of exhaust gases. Hydrogenation of phenol and hydrogen is carried out in two series-connected reactors and adjust the process temperature in the range of 150 - 180 ° C and pressure up to 0.75 MPa with recirculation of exhaust gases. The oxidation of cyclohexane is carried out in two blocks of four reactors and the process temperature is adjusted in the range of 145-160 ° C and pressure up to 0.75 MPa. The dehydrogenation of cyclohexanol is carried out in five reactors and the process temperature is adjusted in the range 370-450 ⁰ C and pressure up to 0.065 MPa. The rectification of cyclohexanol and cyclohexanone is carried out in two reactors to obtain cyclohexanone rectified and the process temperature is adjusted in the range 120 -140 ° С and pressure up to 0 , 25MPa and circulation rate up to 20-30. Hydroxylamine sulfate is cyclohexanone oxidized using a countercurrent system with mixers in two reactors at a temperature of 55-80 ⁰ C and pressure up to ODMP when ammonium sulfate and pH-medium are supplied 4.5 -5, 7 and correct consumption of hydroxylamine sulfate with increasing water concentration over 4.5% of the mass. The rearrangement of cyclohexanone oxime to caprolactam is carried out in reactors at a temperature of 90-110 ° С and pressure up to 0, MPa when oleum is fed with correction with a deviation in the quality of caprolactam. Neutralization of caprolactam sulfate is carried out in the reactor with ammonia water up to 15 wt%, at a temperature of 50 ⁰ C and pressure 0, lMPa, and the purification of caprolactam is carried out with trichlorethylene and alkali and the caprolactam capacity is up to 180 t / year.

Studies on the production of caprolakiam showed that in order to increase productivity and obtain quality with specified parameters, it is necessary to use intermediate products — monomers, benzene and phenol, taking into account their characteristics.

At the stage of hydrogenation of benzene with the production of cyclohexane and subsequent oxidation, rectification and directing cyclohexanone to the oximation and rearrangement, there are problems with the purification of benzene from thiophene and other trace elements that affect the quality of caprolactam. In addition, there are problems associated with losses in Wastes from alkaline and acid-acid effluents of caprolactam are introduced, which also reduces the productivity of the installation.

At the stage of phenol hydrogenation to obtain cyclohexanol, dehydrogenation, rectification and directing cyclohexanone for oximation and rearrangement, there are no problems associated with the quality of microimpurities (for example, cyclohexene), and the plant productivity increases. It should be noted that phenol is more expensive than benzene, so benzene and phenol intermediates must be supplied to the unit in a certain ratio, taking into account the supply of benzene and phenol, with the technological preparation of caprolactam processing lines and taking into account the shipment of caprolactam to the consumer.

To control production, a method of the oxidative method for producing caprolactam from benzene and a scheme for producing caprolactam according to the phenolic scheme are proposed in order to increase productivity with improved properties of caprolactam

The essence of the invention is illustrated in the drawing, which shows a schematic diagram of caprolactam production control. Fig. 1 shows a production diagram, in Fig. 2 controllers for controlling the process, and in Fig. 3 a block diagram of the method 1-nococ of benzene supply with sensor 2 and valve 3; 4-block of hydrogenation of benzene (two reactors with temperature sensors, heat transfer compartments are definitely not shown); 4-a and 4-6 hydrogen sensor and valve; 5-ycipoive ratios of “benzene-phenol”, including valves 6,7,8,9 (adjustable stops, flaps) and 10, 11 (reserve valves); 12 - a block of oxidation of benzene with oxygen (air), connected by a pipe to a valve 8 (air supply pipe is conventionally not shown); 13- oxidation rectification unit (flow from the oxidation unit U, 14- phenol supply pump with a transmitter 15 and valve 16; a sensor and a valve for hydrogen supply 15-a, 15-b; 17-phenol hydrogenation unit connected by a pipeline to valve 9; 18 - a dehydrogenation unit of cyclohexanol (one of five reactors is shown); 19 - a rectification unit (flow from a dehydrogenation unit); a circulation circuit that includes a pump 20 "pump 20 - a dehydrogenation unit 18 - a rectification unit 19- a pump 20" connected by pipelines; 21- cyclohexanone distribution device for oxime blocks (first second line) including the valve 22, 23 and backup valve 24D5, United truboprovodomi capacity with mixing cyclohexanone 26.blokami rectification 13 and 19 with the sensor 27, the total flow rate of cyclohexanone; 28 - the first block of oximation (three reactors with recycling reagents) with flow sensors cyclohexanone 29 and valve 30; 31- second oximation unit with a flow sensor 32 and a valve 33; 34 is a block receiving pscroxylamine sulfate with a flow sensor 35 and a valve 36 to the first block of the oximation 28 and a flow sensor 37 and a valve 38 to the second block of the oxime 31; 39 - the first regrouping unit (a reactor with a refrigerator, a temperature sensor, alkali supply valves, trichlorethylene is certainly not numbered) with an oleum flow sensor 40, a valve 41 and an acidity sensor 42 (acidity is determined by laboratory method at the output of sensor 42);

43- second regrouping unit with an oleum flow sensor 44, a valve 45 and an acidity sensor 46;

47 - the first neutralization reactor with a pH meter 48 (sedimentation tank separation of lactam oil from ammonium sulfate is not shown); 49- second neutralization reactor with a pH meter of 50; 51.52 caprolactam feed pumps to caprolactam mixer 53; 54-CTBO device switching crystalline caprolactam to liquid caprolactam, including 55- crystalline caprolactam concentrator tama (day of sending caprolacgam in plastic bags); 56 - capacity of liquid caprolactam (for sending caprolactam in tanks); 57 - valve for supplying caprolactam to the consumer (cut-off), 58- valve for feeding crystalline caprolactam; 59- valve for supplying liquid caprolactam;

60-microcontrollers connected to the inputs of the sensors 2,4-aD5,15-a, 273323537,40,44,42,48,46,50 and the outputs of the valves 3,4-6, 16,15-630333638,41,45, By forming control loops Jpj at the output of the controllers, the control of caprolactam production processes is carried out by the “manual” operator.

The control method upon receipt of caprolactam is as follows.

- set the total caprolactam load; - set the ratio of benzene and phenol to the hydrogenation reactor; -set the distribution of cyclohexanone along the lines of oximation (first and second line);

- set the shipment of crystalline and liquid caprolactam to the consumer; - Correct the costs of benzene and phenol and operating parameters on the hydrogenation, oxidation, dehydrogenation and rectification units; adjust the costs and operational parameters of cyclohexanone and hydroxylamine sulphate on the oxime line;

- Correct the costs of oleum, alkali and trichlorethylene and operating parameters at the stage of isomerization and the conversion of cyclohexanone oxime in the units of rearrangement to caprolactam;

- Correct the costs of crystalline and liquid caprolactam for the consumer.

The mass ratio of benzene to phenol, the distribution of cyclohezanone along the oxime lines and the shipment of caprolactam to the consumer are maintained between 70:30 and 65: 35%; 55:45 and 60: 40% and 40:60 and 50:50%, respectively. Consider numerical examples of the preparation of caprolactam

Example

We set the total load (from the controller 60), 20 t / h and distribute the weight ratio of 15 t / h to benzene and 5 t / h to phenol using device 5 (hung 6,7,8,9 open. Fans 10, 11 are closed). Pump 1 through the control circuit 23 feed heated benzene in the amount of 15 t / h and hydrogen 60 kg / g (circuit 2a behind) to the hydrogenation unit 4 into the pipe space. Depending on the supply of coal or petroleum benzene, we set the temperature to 160 ° C and adjust it depending on the concentration of sulfur contaminants (sensors temperatures, codensers for heat transfer α, and arcsecels for the limit values for benzene and hydrogen are not conventionally shown). Next, we supply cyclohexane to oxidation unit 12 (one reactor is shown, the other reactors are not shown), where we supply air oxygen through the pipeline. The main oxidation product is cyclohexanone oxides. An important parameter is the stay of the mixture in the reactor and the temperature. The output product — the oxidate contains cyclorecanol and other impurities that are removed by controlling the temperature within 180-200 ^° C or the residence time in the reactor when the load changes. To reduce losses at the oxidation stage, we adjust the process temperature to 190 ° C. Next, the oxidate is sent to the rectification unit 13.19 (together with the flow of block 18) to obtain the rectified cyclohexanone. Pump 14 through the control loop 15.16 feed heated phenol in an amount of 5 t / h and hydrogen 60 kg / g (kontypl5-aD5-b) to the hydrogenation unit 17 (one hydrogenation reactor is shown) into the tube space (condensers, evaporators, temperature and pressure sensors pair, cutoffs for limit phenol values are not conditionally shown). We set the temperature at 175 ° C to increase the reaction rate, selectivity of the process and to eliminate cyclohexane, cyclohexene water and other impurities. The resulting heated cyclohexanol sent to the dehydrogenation unit 18 (one reactor is shown, heat exchangers, refrigerators not shown). Dehydrogenation occurs at a temperature of 400 ⁰ C and a pressure of 0.7 MPa. To purify cyclohexanol (anon) and other impurities, we circulate according to the scheme “pump 20 — dehydrogenation unit 18 — rectification unit 19 — pump 20”. with a multiplicity of 20-30.3, then the mixture (flows from blocks 12 and 18) is fed to rectification blocks 13.19 to remove impurities (esters, acids, cyclohexanol and cyclohexanone). The flows of cyclohexanone rectified from the rectification unit 13, 19 are controlled by laboratory data and sent to the cyclohexanone (anon) distribution device 21 (valves 22 and 23 are open, and valves 24.25 are closed) through the mixing tank 26 and flow meter 27 to the oxime blocks. 55% of the mass is supplied to the first line, and 45% to the second line. (10.7 t / h 8.95 tAi) We control through the 29.30 control loop in the amount of 10, 7 t / h to oximeter 28, where ammonia water is also supplied in the amount of 2, 34 t / h (control loop is not shown) and hydroxylamine sulfate (HAC) from block 34 through the control loop 35, 36 in the amount of 44 t / h. The oximation reaction is carried out in two stages. At the first stage, an excess of anon is created, and at the second stage, an excess of GAS with reagent recycling. An important parameter is the pH of the reagents, which is maintained within 4.5-5.8 by gaseous ammonia. Depending on the moisture concentration in excess of OD% of the set, 4.5% is additionally fed to the second stage of the GAS. The distillation of anon and water, the addition of ammonium sulfate and the drying of cyclohexanone oxime (oxime) with the extraction of ammonium sulfate. Which is returned to production are not shown. Then, the oxime through mechanical filters in the amount of 11.7 t / h (95%, 3% by weight of the oxime, 4.5% by weight of water and up to 0.2% of anon) is sent to the oxime isomerization in caprolacrums to block 39. Two-stage rearrangement is carried out in the environment of oleum (23% of the mass.) supplied through the control circuit 40, 41. The reaction occurs at a temperature of 100 ⁰ C and atmospheric pressure (mixture recirculation, refrigerators, shut-off valves are not shown). An important parameter is the mixing of the components, the ratio of oximoleum, the temperature and the output acidity indicator (up to 60% of the mass), determined by the 42 sensor. Or according to laboratory analysis. Depending on the acidity readings, the oleum supply is adjusted to improve the quality of caprolactam in optical density. For example, up to 0.25 t / h with indicators of acidity of 57% of the mass. Next, caprolactam sulfate is neutralized in the reactor 47, where we feed ammonia water in the amount of 5.1 τ / h and we monitor the pH of the medium according to the readings of the sensor 48. (acidity is maintained within 59-61% by mass.) In the sump, the upper organic layer contains lactam oil (up to 60-70% of the mass, caprolactam ) and 3 & 42% ammonium sulfate, which is returned to the production for oximation and to the workshop for the production of crystalline ammonium sulfate. Then the mixture is sent to extraction with trichlorethylene (TCE) up to 8 kg / h and alkali up to 0.14 kg / g to improve the quality of caprolactam (stages are not shown conditionally). The resulting caprolactam in the amount of ll, 7t / h is directed by a pump 51 to a tank 53.

Similarly, processes occur when anon is fed to the second line of oximation (45% of the specified load -8.95 t / h) in blocks 3134.43.49 using circuits 32 and 33: 37 and 38; 44 and 45; and an acidity sensor 46 and a PH meter 50. The device 21 is in the same position as when connecting the first oxime line. Received caprolactam in an amount of 9.9 t / h by pump 52 is sent to a tank 53, where it is mixed and sent in an amount of 21.6 t / h to a device 54 for switching crystalline caprolactam to liquid caprolactam. The distribution of caprolactam depends on the consumer. During storage caprolactam less than 15 days. from tank 56 we send caprolactam in the amount of 8.64 tons for transportation in tanks (valves 57, 59 open ^ valve 58 is closed). When storing capralactam more than 15 sug. we send caprolactam to the crystalline caprolactam concentrator 55 (valves 57 and 58 are open, and valve 59 is closed) The center represents a drum-type container where it is cooled to a temperature of 60 ⁰ C and is supplied to the consumer in the form of crystals for packing polyethylene bags in an amount of 12 ^ 6 tons.

Thus, combining the methods of the oxidative method for producing caprolactam from benzene and the method for producing caprolactam according to the phenolic scheme and adjusting the regimes at the stage of hydrogenation of benzene and oxidation, at the stage of hydrogenating phenol, dehydrogenating cyclohexanol with subsequent rectification β, also reducing the concentration of water at the stage of oximeting with subsequent correction according to the supply oleum at the stage of regrouping, we achieve an increase in productivity with the desired properties of caprolactam. At the same time, we increase the effective st to 20%, reduce the loss of caprolactam up to 10% and reduce the size of trace content in the final caprolactam.

The table below shows the indicators characterizing the quality of caprolactam and performance under load conditions 22t / hfφi mass ratio of benzene-phenol 70: 30%, load distribution on

Oximation lines 55 :: 45% and shipments to the consumer 40: 60%.

Tab.

Name of indicators proposed known installation installation

1. temperature correction in benzene hydrogenation units, 4 220 210 oxidations, 12 150 160 phenol hydrogenation 17 160 phenol dehydrogenation 18, ° С 470 rectification unit,

(circulation rate) 25

2. The deviation of indicators of the pH average,% 5

H. Temperature control accuracy, ° C 0.9 1.5

4 Caprolactam quality indicators. easily volatile and highly volatile, g-equiv / l cyclohexanone 0.09 0.12 cyclohexanol 0.103 0D1 esters 0.039 0.040 acids 0.016 0.017 relative change in permanganate number,% 2.5 10 moisture content during oxidation,% 4.45 5.5

5. The relative loss of caprolactam,% 10 35

6. Storage periods, cit. 15 12

7.Increase in profitability,% 20

As can be seen from the table, quality indicators and

Improved installation performance. Economic effect

amounts to ZOmln. rub per year. The method was introduced in 2007. at OJSC Kuibyshevazot.

Claims

Formula of the invention l. A method for controlling the production of caprolacgam from benzene, carried out in a unit with one production line, including units for hydrogenation of benzene and hydrogen, oxidation of cyclohexane with oxygen, rectification of cyclohexanone, oxidation of hydroxylamine sulfate, rearrangement of the caprohexacylamine hydroxylamine, pumps, pipelines with sensors and valves for adjusting the flow rates of benzene, hydrogen, cyclohexanone, hydroxyls sulfate, oleum, alkali, trichlorethylene, an acidity sensor and a pH meter of caprolacgam, characterized in that the installation additionally contains a second production line, including hydroxylamine sulfate oxime oxime blocks, cyclohexanone oxime rearrangements in caprolactam and neutralization with ammonia, interconnected by pumps and pipelines with sensors and flow valves for hydroxylaminosulphate, oleum, alkali, trichlorostylene, an acidity indicator and a caprolactam pH meter, and also contains phenol and hydrogen hydrogenation unit with pump, sensors and valves and feed cyclohexanal α to a dehydrogenation unit with a circulation circuit, including: a pump — a dehydrogenation unit; cyclohexanolag rectification unit — a pump connected by pipelines; a benzene-phenol ratio device connected by pipelines to a benzene and phenol hydrogenation unit and oxygen oxidation and a dehydrogenation unit; a cyclohexanone distribution device for oxime blocks, connected by pipelines to rectification units and through a mixing tank of cyclohexanone with oxime blocks; a device for dispatching crystalline and liquid caprolactam, connected by a pipeline to a caprolactam mixer and a concentrator for crystalline caprolactam and a liquid caprolactam tank; while setting the total load on caprolactam; benzene-phenol ratio; distribution of cyclohexanone to the oxime blocks; shipment of crystalline and liquid caprolactam to the consumer and adjust the costs of benzene, phenol, hydrogen, cyclohexanone, insulphate hydroxypam, oleum, alkali and trichlorethylene, respectively, by acting on the corresponding valves.

2. The method according to claim 1, characterized in that the hydrogenation of benzene and hydrogen is carried out in two series-connected reactors and adjust the process temperature in the range of 160-230 ° C and a pressure of up to 0.8 MPa with circulation of exhaust gases.

Z. The method according to claim 1, characterized in that the hydrogenation of phenol and hydrogen is carried out in two series-connected reactors and the process temperature is adjusted in the range of 150-180 ° C and pressure up to 0.75 MPa with recirculation of the blowing gases.

4. The method according to claim 1, characterized in that the oxidation of cyclohexane is carried out in two blocks of four reactors and the process temperature is adjusted in the range of 145-160 ° C and pressure up to 0, 75 MPa

5. The method according to PL, characterized in that the dehydrogenation of cyclohexanol is carried out in five reactors and the process temperature is adjusted in the range of 370-450 ° C and pressure up to 0.065 MPa

6. A method according to claim 11, characterized in that the rectification of cyclohexanol and cyclohexanone is carried out in two reactors to produce cyclohexanone rectified and the process temperature is adjusted in the range of 120-140 ° C and pressure up to 0.25 MPa and with a circulation ratio of up to 20-30.

7. The PoIl method, characterized in that the oxime of cyclohexanone with hydroxylamine sulfate is carried out in a countercurrent system with a mixer in two reactors at a temperature of 55-80 ° C and a pressure of up to 0.01 MPa with a flow of ammonium sulfate and a pH of 4.5-5.7 and adjusting the consumption of ammonium hydroxylamine sulfate with increasing water concentration over 4.5% of the mass.

8. A method according to claim 1, in which the rearrangement of cyclohexanone oxime into caprolactam is carried out in reactors at a temperature of 90-110 ⁰ C and pressure up to 0.1 MPa when oleum is fed with correction when the quality of caprolactam deviates from the set one.

9. The way to pop. 1, characterized in that the neutralization of caprolactam sulfate is carried out in the reactor with ammonia water up to 15% of the mass, at a temperature of 50 ° C and a pressure of 0.1 MPa, and the purification of caprolactam is carried out with trichlorosthylene and alkali.

10. The method according to p. 1-9, characterized in that the caprolactam performance is up to 180J.