SU1429933A3 - Method of producing allyl chloride - Google Patents

Abstract

The method involves chlorinating propylene with chlorine and separating the reaction products by rectification wherein the reaction is initiated by introducing into the reaction zone propylene and nitrogen at a rate of at least 20% by weight of the required rate of chlorine, chlorine is then introduced into the reaction zone at a rate up to 60% of the required rate, and after the rate of supply of chlorine has reached 66%, the supply of nitrogen is stopped and the nitrogen in the reaction zone is withdrawn through the rectification system for separation of hydrogen chloride product, reflux of the hydrogen chloride being maintained until the refluxing vapours contain at least 95% by volume of hydrogen chloride. This reduces the amount of carbon and tar compounds usually formed during starting and stopping this type of process.

Description

j- The invention relates to an improved method for producing allyl chloride, which is an intermediate in the production of epichlorohydrin and glycerin.

The aim of the invention is to accelerate the stabilization of the operating parameters of the reactor and distillation column 1, and the reduction of the formation of coal and tar-like products in the reaction zone;

 Example. The unit for the helium allyl chloride was filled with dried propylene with a maximum humidity of 5 ppm before the start-up, forced circulation of propylene with an intensity of 10,500 kg / h i Regulated heater in furnace 1, temperature of propylene fed to the reactor 3 through mixer 2, maintained at 270 ° C. After cooling in i heat exchangers 4 and 5, propylene undergoes partial condensation in heat exchangers 6 and is divided into two phases D tank 7, in which the liquid level is 50% of the filling. The gas phase is automatically (independently), and the liquid phase, when fed to the pump 8, enters column 9, in the distillation tank of which the level of liquid propylene is about 50% of the filling.

The vapors obtained at the top of this column are injected into the compressor 10 and condensed in the exchanger 11. Liquid propylene flows into the reservoir .12, in which the level is about 50% of the filling, and then returns to the top of the column. Heat is supplied to this column from an evaporator 13, through which a decoction is circulated by means of a pump 14. A portion of the decoction is sent to column 15, in which distillation level is about 50% of the filling.

The vapors obtained at the top of the column are subjected to partial condensation in the heat exchanger 16, from where the condensate flows into the tank 17, in which the level is about 50% of the filling. The non-irrigated part of the propylene is recycled in the reactor system. Maintaining the temperature of the propylene leaving the furnace 1 at the level of 270 C, start the correct start of the installation by feeding

50

y d

0

with

nitrogen flow through pipeline B in the amount of 650 kg / h, which amounts to 2Г wt.% of the chlorine flow in the steady state plant, and after 10-30 s by feeding chlorine into the mixer 2 through pipeline C with a given flow rate 1300 kg / h (42% of the flow in steady state operation).

At the same time, the flow of nitrogen and chlorine continued for 20 s, and after reaching the chlorine flow rate of 2100 kg / h (67.7% of the flow in the steady state operation), the nitrogen flow closes the temperature of chlorine in the reactor system when the temperature rises 5 minutes. propylene leaving furnace 1 at the inlet to mixer M-2 reaches value In reactor 3, the temperature rises to 460 ° C, and the temperature of propylene leaving from heat exchanger 4 reaches 275 ° C, B E.TO time through pipe A start feeding dried propylene to an amount to maintain the circulation rate of propylene at 10,500 kg / Cho After the reactive mixture leaving the heat exchanger 4, is cooled in the heat exchanger 5, and then subjected to partial condensation in the exchanger 6 and separated into two phases in the tank 7 The gas phase is independent, and the liquid phase when pumped by pump 8 enters column 9. The vapors obtained at the top of the column are injected in compressor 10 and subjected to partial condensation in an exchanger 11

After 1-2 minutes have elapsed since the introduction of chlorine, the temperature at the top of the column decreases, which is evidence of the occurrence of hydrogen chloride in the vapor

From this point on, for about 20 minutes in the reflux tank 12, the level of the liquid is maintained and pipeline D is exhausted with such intensity that at the top of the column a constant pressure of about 0.16 Sh is maintained. Then the reflux tank 12 is completely empty. they are filled to a level that ensures stable adjustment of the operation of the column only after reaching 95% hydrogen chloride in the vapor from the column, which corresponds to a peak temperature of about -71 ° C. The decoction from the column circulates through the evaporator. 14 Part broth feeds column 15,

The vapor obtained at the top of column 15 and containing propylene and a small amount of hydrogen chloride is partially condensed in an exchanger 16o. They drain into tank 17, from where the liquid phase flows as a reflux to the top of the column, and the gas phase returns to the reactor system and undergoes recirculation. The decoction from the column, which is a raw allyl chloride, is circulated through the evaporator. 18 using a pump 19. Part of the decoction feeds the column 20,

The vapors obtained at the top of the column 20 and containing light chlorinated C3 derivatives and a small amount of alkyl chloride are condensed in an exchanger 21, they flow into tank 22, from where part of the liquid returns to the column as a reflux, and the remainder is withdrawn through line E to the outside . A decoction from the column, containing allyl chloride and heavy chlorine derivatives СЗ, circulates through the evaporator 23 by means of a pump 24о. Part of the decoction feeds the column 25

The vapors obtained at the top of column 25 and which are pure allyl chloride undergo condensation in an exchanger 26 and drain into reservoir 27, from where part of the liquid returns to the column as a reflux, and the remainder is withdrawn through line F to the outside of the installation. The broth obtained in the column, containing heavy chlorinated C3 derivatives and a small amount of allyl chloride, is circulated through the evaporator 28 by means of a pump 29 Excess broth is removed through the pipeline G to the outside of the plant After 2 hours from the moment chlorine is released into the reactor system, the upper columns 9 are reached temperature from -74 to -75 ° C, and in the distillation still of this column is from -28 to -30 ° C. Under these conditions, the top product of the column contains hydrogen chloride: is over 98.5% by volume, and lower product - less than 0.4 masd Because they correspond to the stable operation of the reactor.

After several hours, the flow of chlorine is gradually increased to the optimum value of 3100 kg / h with the achievement of

in the reactor, the temperature is 485 ° C. Under these conditions, it carries out the synthesis of allyl chloride by feeding through the pipeline A fresh propylene in an amount of about 1,800 kg / h and discharging through the pipeline D hydrogen chloride in the amount of 1400 kg / h when kept in the stream about 99% HC1, and

0 also through the pipeline - allyl chloride in an amount of about 2600 kg / h with a content in the stream of about 98.5% CjHjClo The content of 2-chloropropane in the broth of the column 9 is lower than 0.7 wt%,

5 and in the decoction column 15 is in the range of 1.5-2.5 wt.%

TabLo shows the course of changes in the parameters of the reactor system and the column for the separation of hydrogen chloride.

Q during the launch of the installation carried out by the proposed method

PRI mme R 2. The process is conducted in a similar, logical way, but the introduction of chlorine begins “10 seconds after the introduction of nitrogen.

5 The results of the experiment are shown in Table 2. The notation for the graph in Table 2 is the same as in Table 1,

 Stable operation of the reactor and in this case is achieved within

0 2 h

PRI me R 3 (comparative). The process is carried out as in example 1, but without prior input of nitrogen into the system and without emptying the tank.

& reflux columns when reaching a concentration of 95% of serviceable,%. After 2 hours, the concentration of .HCl at the top of column 9 is 81.2% by volume, i.e., 17-18% lower than that which corresponds to

0 steady state operation, the cube of column 15 contains 20.25% 2-chloropropane, 60.45% allyl chloride and 13.36% coal and tar-like products. In parallel, the reaction system is started up in accordance with the invention. After 2 hours, the HC1 content at the top of the column is 99.5%, which corresponds to a stable operation of the column, B

The Q of the column 15 contains 1.25% 2-chloropropane, 80.73% allyl chloride, and 1.74% coal and tar-like products.

Thus, the proposed invention allows to reduce the deposition of coal and resinous products in the synthesis unit at the initial stage of the chlorinating process by 7.9 times and reduce the time required for stabilization.

parameters of the reactor and distillation column, up to 2 hours, whereas in the known method this time is not enough. The invention avoids the addition reaction of HC1 to propylene to form 2-l-lopropane. Formula

the invention

The method of producing allyl chloride by chlorination of propylene at 460-486 ° C with preliminary mixing of gaseous reactants in the mixing chamber using heat of reaction in the heat exchanger in the chlorination process and releasing hydrogen chloride from the reaction gases by rectification in a distillation column at a column bottom temperature of -28 ...- 30 ° C and the top of the column -74, .. -76 ° C, characterized in that, in order to accelerate the stabilization of the parameters of the reactor and the distillation column and to reduce the formation of coal and oloobraznyh products in the reaction zone at an initial stage of the process, through the mixing chamber, the reactor, heat exchangers, a rectifying column for hydrogen chloride vydele- nn and reflux tank of this column nitrogen is passed before entering the chlorine system.

180

270

During this time interval, the parameters quickly changed.

275

340

15 30

270-275 338-342 4GO-463 -25 to -47 -23 to - -28-30

-55

72

0

5 0 5 Q

moreover, the amount of nitrogen is 21% by weight of the amount of chlorine in the steady state operation of the reactor and the distillation column, chlorine input starts 10–30 s after the start of nitrogen start up, and the amount of chlorine increases from 42 to 67.7% by weight of steady state, after the amount of chlorine reaches 67.7 wt.% of the amount at steady state, nitrogen input is stopped, nitrogen is removed from the system through the air outlet of the reflux tank of the distillation column to separate hydrogen chloride, thus During the first 30 minutes, a reflux mixture of propylene and hydrogen chloride was kept in the reflux tank, after which all of the accumulating tank was directed to the top of the distillation column, then after reaching 95% by volume of hydrogen chloride in the vapors leaving the column, the tank was again filled with liquid reflux and keeping the o-j in the liquid state, simultaneously for 8 hours gradually increase the amount of chlorine entering the reactor from 67.7 to 100 wt.% of the amount corresponding to the steady state of the reactor and rectification oh

columns.

Table 1

 270

-thirty

-39

-thirty

oh oh oh

460

-20

-A2. -30 Not measuring -55

72

1429933

7 eight

Table 1 maintenance

1429933

/

Editor L.Gratillo

Compiled by S.Pov Kova Tehred M.Dndyk

Order 5149/58

Circulation 370

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d. A / 5

nineteen

2i

 29

Corrector OSKr.chvtsova

Subscription

Claims (2)

SUMMARY OF THE INVENTION Method for producing allyl chloride by chlorination of propylene at 460-486 ° C with preliminary mixing of gaseous reagents in a mixing chamber using the reaction heat in a heat exchanger in 1 chlorination process and with the release of hydrogen chloride from the reaction gases by distillation in a distillation column at a temperature of the bottom of the column '· -28 ...- 30 ° С and the top of the column -74 ... -76 ° С, characterized in that, in order to accelerate the stabilization of the operating parameters of the reactor and distillation column and reduce b-; coal and tar products in the reaction zone at the initial stage of the process, nitrogen is passed through the mixing chamber, reactor, heat exchangers, distillation column for hydrogen chloride evolution and a reflux tank of this column before entering the chlorine system! wt.% of the amount of chlorine under steady-state operation of the reactor 5 and distillation column, the introduction of chlorine begins 10-30 seconds after the start of the nitrogen start-up, and the amount of chlorine increases from 42 to 67.7 wt.% of the amount with steady state re-mode, after when the amount of chlorine reaches 67.7 wt.% of the amount under the established nitrogen input mode, the nitrogen is removed from the system through the air outlet of the re-vacuum of the reflux distillation column to separate hydrogen chloride, while in the reflux tank for the first For 30 min, a liquid mixture of propylene and hydrogen chloride 2Q is stored, yes, after which the entire contents of the tank are sent to the top of the distillation column, then after reaching. 95% vol. of the content of hydrogen chloride 'in the vapors leaving the column 25b1, the tank is again filled with liquid reflux and retained; it in a liquid state, at the same time over 8 hours, gradually increase the amount of chlorine entering the reactor, from ed 67.7 to 100 wt.% the amount corresponding to the steady state operation of the reactor and distillation column. Table! Time 1 Nitrogen speed, kg / h • Chlorine speed, kg / h Temperature С, Н6 to Ф-1, * С Temperature С? Нс to М-2 ° C Temperature in R-3, ° C Temperature c. V-7, ° C Top temperature K-9, C Cube temperature K-9, ° C HC1 concentration at the top of K-9, vol. X 2 3 4 5 6 7 8 '10 - 0 0 180 270' 270 -30 -39 -30 0 0 Start 0 180 270 270 -30 -39 '-30 0 S with 650 0 180 270 270 -30 -39 -30 020 0 180 270 270 -30 -39 -39 0 30 Start 180 270 270-30. -3’9 -30 0 40 1300 '50 Stop 2100 During this period, the parameters quickly changed 1 mission 0 2300 5 kick' 2500 275 340 460 -28 -42. -30 Not measured 15 -. ’’ W _ | 1 ~ 270-275 338-342 <460-463 -25 to -47 -28 to, p. II, 11. Continuation of the table 1 ;; ~~ TT-p — p | ~ G ~ p G7 ~~ [Y ~~ p 45 i 0 2500 270-275 338-342 460-463 -25 to -28 -64 -28 ds -30 Not intended 1 h „I- - · -68 -I- 93 75 min -JI-„ and. -J> - -71. 95. : 90 min „p„ -75 -K-; m, s 105 min -II-. -76 -I * - 90t5 -.99.5 2 h -lf- - -Il- -74. dr -76 1 wlk. 4 4 _JI_ 2800 275-280 475.-d · 6 h 3000 -Ί, -II- 480 - - II— 8 h -I- 3100 483-486 - -I'— -Ί- 14 h 3100 - II— —Ί— .1 “bl and t'a 2 -i — ί — a. · Time Speed of nitrogent. kg / h CxopocTi chlorine kg / h Temperature С, Н (to Ф-1, ° C 'Sens temperature ”to М-2 ° C Temperature · and R-3,“ С Temperature in V-7, ° C Top temperature К "-9 ° C Cube temperature K-9, • s, HC1 concentration at the top of K-9 vol. X 1 2 3 4 5 6 7 8 9 10 - - 0 180 270 270 -30 -39 -39 0 0 Start 0 180 270 270 -30 -39 -30 0 10 о 650 Start 180 270 270 -30 -39 -30 0 20 650 1300 Ί t 30 Stop 2400 I During this period of time, the parameters quickly changed 1 MIN 0 2300 J * 5 min 0 2500 275 340 460 -28 -42 -30 Not measured 15 min _ <U m1 '·. 270-275 338-342 460-463 -25 to -28 -47 -28 to -30 30 min e · ** ·· .1 / _υ_ -55 72 45 Nii WH— • 'U • • С -J'- -II- -64 Not measured 1 h. -11— -68 fl'- 93 75 mn .1 / - ”1- -II- w, r— -71and || „95 90>“ n 0 2500 2 70-275 · 338-342 460-463 -25 to -28 -75 -28 to -30 98.5 105 kin „p_ —II— —n- -76 - * 1- 98.5 - 99.5 2 h -Ί- '-74 to -II- -II- 1 About Continuation of Table 2 ----- ² 1 and: Tz T-T-- _g - _t --- 1 ^{, about} 4 h 2800 275-280 475, - - 6 h 3000 W. ”- 480 8 h 3100 483-486 14 h _w ll _w 3100 h