FR2526788A1 - PROCESS FOR PURIFYING CRUDE 1,2-DICHLORETHANE - Google Patents

Abstract

1,2-DICHLORETHANE PURIFICATION PROCESS. HYDROGEN CHLORIDE, ETHYLENE, OR HYDROGEN AND ETHYLENE CHLORIDE, ARE INTRODUCED IN ONE OR MORE POINTS OF THE SYSTEM IN WHICH CRUDE 1,2-DICHLORETHANE CONTAINING OXYGEN IS PURIFIED, TO PREVENT CURRENTS OF MATERIALS IN THE SYSTEM FROM ENTERING THE FLAMMABILITY INTERVAL.

Description

PROCESS FOR THE PURIFICATION OF RAW 1,2-DICHLORETHANE

  The invention relates to a method for purifying the

1,2-dichloroethane crude.

  1,2-dichloroethane is frequently obtained in a reactor from which at least one stream of crude 1,2-dichloroethane comprising flammable substances, non-flammable substances and oxygen is extracted. The stream of 1.2 is then introduced. crude dichloroethane in a purification system, from which the purified 1,2-dichloroethane and one or more streams of other products are extracted. The presence of oxygen in the crude 1,2-dichloroethane stream causes problems in the production system. purification, because, as the crude 1,2-dichloroethane separates into different streams of different products, oxygen generally

  concentrated in one or more streams containing concentrations

  high concentrations of flammable substances Unless special precautions are taken in the design

  and the exploitation of the purification system, the composi-

  tion of these currents, which is in the system of purification

  fication, risk of taking values falling within

the flammability range.

  The object of the invention is to solve the problem

  above, diluting one or more currents in the purification system so that they do not enter

  in the flammability range.

  The invention will be better understood in view of the description

  below and the attached drawing, which represents a schematic

  only one embodiment of the invention.

  The invention provides an improvement to the process in which raw 1,2-dichloroethane comprising flammable substances, non-flammable substances and oxygen is introduced into a purification system.

  from which purified 1,2-dichloroethane is extracted and one or more

  current products of other products

  the invention consists in introducing into the purification system

  cation, at one or more points, hydrogen chloride, ethylene, or hydrogen chloride and ethlylene, to ensure that at least one product stream in the purification system do not enter

the inflammability interval.

  The different substances are called flammable or non-flammable depending on whether they burn or not, after they have been

  mixed with oxyvaene or air in proportions

  tible to be encountered in everyday activities, and

  The 1,2-dichloroethane is itself inflamed

  mable Among the other flammable substances that can be

  to be found in processes for the purification of 1,2-dichloro-

  ethane, mention may be made of hydrogen, ethylene, acetylene, ethane, ethyl chloride, 1,1-dichlorethylene,

  trans-dichloroethylene, cis-dichloroethylene and 1,1-

  Examples of non-flammable substances that may be mentioned include nitrogen, hydrogen chloride, carbon dioxide, chloroform,

  carbon tetrachloride, trichlorethylene, perchlor-

  ethylene, water, 1,1,2-trichloroethane, symmetric tetra-

  chloroethane, pentachloroethane and various high molecular weight substances containing a significant amount of chlorine and collectively referred to as "taro" These lists

  substances are in no way exhaustive.

  raw 1,2-dichloroethane which can be purified by

  according to the invention may contain all the substances

  these listed above, or just a few of them

  They can also contain non-toxic substances

listed above.

  Although different substances which are themselves considered flammable may be present in a current in the purification system, it should not be automatically concluded that the current is in the flammable range. The position of a current given by report

  the flammability range depends on several parameters

  very, and in particular its composition, its temperature

  and its pressure If the molecules of inflammatory substances

  in a mixture containing substances

  flammable, oxygen and, optionally, substances

  these non-inflammable, are so far apart from each other that those inflamed by a medium of inflammation do not transmit inflammation to the other molecules closest, the mixture is said too "poor" to ensure combustion, and it does not When the molecules of flammable substances or flammable and non-flammable substances are so close to one another that they suppress the oxygen necessary for combustion, the

  mixture is said to be too "rich" and it does not burn

  between the poorest composition and the richest composition that can burn after ignition are said to fall within the flammability range. Between the lower limit and the upper limit of the flammability range, there are different phases, from combustion

slow and fast burning.

  In most cases where temperature variations

  The main parameter is the composition of the product. However, when the pressure variations are very important, the effects of the pressure must be taken into account. This is not within the flammability range for low pressure, but enters the flammability range if it is compressed at a higher pressure. Similarly, when temperature changes are significant,

  to better take into account the effects of temperature.

  The amount of hydrogen chloride, or ethylene, or hydrogen chloride and ethylene, which is introduced into the purification system can be varied within wide limits. This parameter depends on the design of the system. of purification considered and the composition, pressure and temperature of the different currents in the circuit If one or more currents, in the absence of dilution according to the invention, is in the range of flammability , hydrogen chloride, ethylene, or hydrogen chloride and ethylene can be introduced in at least the amount which will ensure that the

  current does not enter the flammability range.

  If, in the absence of dilution according to the invention, one or more currents are at certain times in the flammability range, because of the fluctuations which normally occur in the purification system, the hydrogen, ethylene, or

  hydrogen chloride and ethylene, in at least the amount

  This ensures that the current does not enter the flammability range, notwithstanding the fluctuations. Similarly, if one or more currents, in the absence of dilution according to the invention, are found from time to time in the flammability range due to fluctuations which, although non-normal, are reasonably likely to occur in the purification system, can be introduced hydrogen chloride, ethylene, or

  hydrogen chloride and ethylene, at least the amount

  which will prevent the current from entering the

  flammability range, notwithstanding fluctuations; in other words, hydrogen chloride, ethylene, or hydrogen chloride and ethylene can be introduced in an amount to provide a safety margin of safety.

  In this case, the quantity of hydrogen chloride,

  lene or hydrogen chloride and ethylene, is superior

  than an "insignificant" quantity The maximum quantity

  introduced with hydrogen chloride, ethylene, or chlorine

  However, it is only limited by the practical possibilities of the purification process. For example, when a condensation is used in the process of purification. downstream of the point of introduction of the diluent, the quantity of hydrogen chloride, ethylene, or hydrogen chloride and ethylene introduced shall not be so large as to raise the dew point to a temperature at which condensation is ineffective The point or points of introduction of hydrogen chloride, ethylene, or hydrogen chloride and ethylene into the system can be varied within wide limits.

  However, in general, these points are

  forward, or upstream of the zone or zones o, in the absence of dilution, flammability poses a problem or could become a problem. From a total point of view, in the context of the invention, the distance upstream can be considered

  but to maintain a low burden on the equi-

  upstream, it is preferred that this distance be small.

  When introduced and hydrogen chloride and ethylene, they can be introduced in the form of a mixture, or

  in the form of separate currents.

  The use of hydrogen chloride, ethylene, or hydrogen chloride and ethylene as a diluent according to the invention is particularly desirable because

  can often use as a load for other reactions.

  a stream comprising a flammable substance, oxygen and, if present, hydrogen chloride, which is removed from the purification system.

  often send a current of this kind to an oxy-

  In a representative way, the current can

  be sent to an oxychlorination process in which the

  The lene undergoes oxychlorination to give 1,2-dichloroethane.

  The use of hydrogen chloride as a diluent according to the invention is particularly preferred. In fact, hydrogen chloride is non-flammable and, moreover, it is often found as a by-product of other reactions. example in an integrated production unit

  of vinyl chloride, hydrochloric acid may be used

  gene as a by-product of the pyrolytic decomposition of 1,2-dichloroethane to vinyl chloride,

  as a diluent in the purification system of 1,2-

dichloroethane according to the invention.

  From a very general point of view, the crude 1,2-dichloroethane stream (s) containing a flammable substance, a non-flammable substance and oxygen, which are introduced into the purification system, can come from any Amongst the representative sources, those in which ethylene is subjected to oxychlorination in a packed column in a fluidized bed or in reactors in the liquid phase, those in which ethane undergoes oxychlorination, and those in which the reaction is carried out.

  ethylene on chlorine containing a contaminating amount

  oxygen phase in the liquid phase or in the vapor phase

  example L F Albright, "Manufacture of Vinyl Chloride".

  Chemical Engineering, April 10, 1967, pages 219-224 and 226, and the

  U.S. Patent Nos. 3,427,359 and 3,679,373, which relate to

  chlorination See also U.S. Patent Nos. 1,231,123, 2,043,932, 2,029,231, 2,245,776, 2,356,785,2393,367 and 2,601,322, which

  chlorination in the liquid phase and / or in the

  Preferably, the method according to the invention is used.

  in combination with a process where the ethylene is reacted

  and chlorine containing a contaminating amount of oxy-

  In the liquid phase, the gene is used to produce at least one stream of crude 1,2-dichloroethane. The liquid-phase chlorination reaction is most preferably carried out in the presence of ferric chloride. US Pat.

  Nos. 2,356,785 and 2,393,367 mentioned above.

  As used herein, the term "oxychlorination", unless otherwise indicated, is used in its broadest sense and includes processes in which chlorinated hydrocarbons are produced by the reaction (1) of hydrocarbons and / or hydrocarbons. chlorine, (2) oxygen, and (3)

  hydrogen chloride and / or chlorine, in the presence of a catalyst

  The reaction catalysts of the Deacon type are described in US Pat. No. 3,679,373.

and in other sources.

  Oxygen in the 1,2-dichloride stream

  raw ethane can come from any origin Although oxygen can be introduced voluntarily or not

  in crude dichloroethane after the formation of 1,2-

  dichloroethane, the oxygen usually comes from feedstock introduced into one or more reactor systems producing 1,2-dichloroethane It may be for example the result of incomplete conversion of oxygen in oxychlorination reactions producing

  1,2-dichloroethane by the reaction of ethylene, chlorine

  hydrogen and oxygen Oxygen can also be

  present as a contaminant in the chlorine used

  used to chlorinate ethylene to give 1,2-dichloroethane in liquid phase reactions and / or

in the vapor phase.

  The contaminating amount of oxygen in the crude 1,2-dichloroethane stream can vary within wide limits, but is usually between a value substantially greater than zero and about 0.5% by weight of the current. about 0.01 and about 0.3% by weight of the stream and, in a manner

  representative, it ranges from about 0.02 to about

  0.2% by weight of the "substantially greater than zero" current is understood to mean at least the amount which, in the absence of dilution with hydrogen chloride, ethylene, or hydrogen chloride and ethylene according to the invention, would lead to one of the following situations: (1) to ensure that at least one stream of materials in the 1,2-dichloroethane purification system enters

  the flammability range; or (2), because of

  that occur or are reasonably sus-

  can occur in the purification system, to ensure that at least one stream of materials in the 1,2-dichloroethane purification system enters the flammability range. In other words,

  is a quantity greater than a negligible quantity.

  This is when oxygen is present in the form of a

  contaminant in the chlorine used to produce 1,2-

  By the chlorination of ethylene, the process according to the invention provides a particular advantage. Chlorine can be produced in several ways, some of which introduce more significant amounts of oxygen into the chlorine than others. of view

  chlorine is usually obtained by the elec-

  trolysis of an aqueous solution of an alkali metal chloride, usually sodium chloride Without wishing to be bound by any theory, it is believed that most of the molecular oxygen found in the electrolytic chlorine is obtained by electrolysis of a small part of the water in the aqueous solution The amount of molecular oxygen contaminating the chlorine depends on many variables, in particular the

  concentration of the electrolyte, the temperature of the electri-

  trolyte, the pH of the electrolyte, the voltages and the

  Even in the last few years, the use of graphite anode cells has been phased out and replaced by cells using dimensionally stable anodes. Dimensionally stable anodes are usually stopping coated or partially electrocatalytic electroconductive coating containing a platinum group metal or a metal oxide of a group of

  platinum See, for example, United States patents

  No. 3,654,188, 3,778,307, 3,876,517, 3,948,751 and 3,956,097. The use of cells using dimensionally stable anodes has a disadvantage because they often tend to produce chlorine containing amounts of oxygen. contaminant greater than many of the cells previously used at the scale

industrial.

  Chlorine can also be obtained from hydrogen chloride and oxygen by the Deacon process. See, for example, U.S. Patent Nos. 85,370, 2,312,952, 2,577,808, and 3,114,607. contain

  contaminating amounts of oxygen as a result of the conversion

  incomplete oxygen introduced into the process.

  There is yet another process for the production of chlorine, the electrolysis of hydrochloric acid.

  for example, U.S. Patent No. 3,129,152.

  It can create a contamination of the chlorine by oxygen due to the electrolysis of a part of the water, or for

other reasons.

  The list of oxygen-contaminated sources of chlorine presented above is by no means exhaustive, but is given by way of example. Many other processes for the production of chlorine are known, and many of them give a tainted chlorine by

  low amounts of oxygen Even a chlorine that initiates

  It does not contain oxygen, or contains little oxygen, subsequently undergoes contamination by oxygen, for example because of an air leak in the circuit.

  chlorine can also be considered as a source.

  The contaminating amount of oxygen in the chlorine can vary widely, but is

  usually between a value significantly higher than

  less than about 5% by weight of the total composition containing chlorine and oxygen. It is often from about 0.05 to about 2% by weight of the total composition comprising chlorine and oxygen and In a representative manner, it is between about 0.1 and about 1.5% by weight of this total composition. Other substances besides chlorine and oxygen can also be found in the total composition. are present in small amounts By "substantially greater than zero" is meant here at least the amount which, in the absence of dilution with hydrogen chloride, with ethylene, or with hydrogen chloride and the ethylene according to the invention, would lead to the following phenomena (1) to ensure that at least one stream of substances in the subsequent purification system of 1,2-dichloroethane enters the flammability range; or (2) because of fluctuations occurring or reasonably likely to occur in the purification system,

  ensure that at least one stream of materials is

  In other words, it is an amount greater than a negligible amount. 1 O To reduce the concentration of oxygen in contaminated chlorine, whatever its origin, it has often been done by liquefying the chlorine, removing oxygen

  gaseous and, usually, by vaporizing the purified chlorine.

  The process of purification of chlorine consumes a strong

  energy, and the necessary equipment is expensive.

  It has been found that in a combined system in which

  used in conjunction with a subsequent purification system

  1,2-dichloroethane, a chlorine reaction system,

  (in the liquid phase) loaded with ethylene and chlorine

  With oxygen contaminating quantities, the chlorination system could usually withstand higher oxygen concentrations than usual, without undue side effects in the formation of 1,2-dichloroethane. focus in currents containing proportions

  flammable substances in the purification system.

  Downstream, the operation of a chlorination reactor system with increasing concentrations of contaminating oxygen is likely to penetrate a

  or several streams of the purification system in the

  In other words, it is usual-

  the purification system which imposes the constraint

  principal on the combined system.

  The invention ensures the safety of the handling of

  oxygen-containing streams in the system

  purification of 1,2-dichloroethane, which allows

  to use relatively larger quantities of oxy-

  contaminant gene in the chlorine introduced into the chlorination circuit. As a result, the process in which

  liquefies the chlorine to eliminate oxygen can be considered

  significantly reduced in terms of its applications, or even eliminated, which saves the energy otherwise spent for this purpose In addition, it is often possible to greatly reduce or even eliminate the capital goods needed for the system.

chlorine purification.

  There is limited data on the in flammability

  of the compositions that may be encountered in

  of a process for the purification of 1,2-dichloroethane.

  These results can be obtained, if necessary, using well-known techniques. See, for example, the general procedure of ASTM Standard Test Method E 681-79, which may be modified as necessary to be used.

  with oxygen and with large temperature fluctuations

  erosion and pressure See also Craven and Foster, "The

  Limits of Flammability of Ethylene in Oxygen, Air and Air

  Nitrogen Mixtures at Elevated Temperatures and Pressures, "Combustion and Flame, Volume X, Butterworths, London (1966), pages 95-100, which may be modified if necessary.

  general procedure In the absence of such relative data

  In order to have an initial estimate of the flammability ranges and / or the amounts of diluent to be introduced, the existing data for approximately similar compositions can be used. As ethylene is a main constituent of a few of the

  currents likely to penetrate into the inflammatory range

  mability in the purification system, we used the

  results from Craven and Foster, referenced above and

  ethylene-air-nitrogen, to obtain initial estimates of the amounts of hydrogen chloride diluent,

  ethylene, or hydrogen chloride and ethylene, to be introduced.

  The results of Craven and Foster were recalculated for flammable-oxygen-nonflammable material mixtures, curves were constructed in triangular coordinates,

  giving the lower flammability limits (recalculation

  have been extrapolated to cover

  all concentrations of flammable-oxygen

  Non-flammable material encountered in the different streams of the purification system The general method consisted first of all in defining the maximum permissible concentration of oxygen on the flammability curve, for a set of conditions at least as severe as in the process stream under consideration was then determined the amount of hydrogen chloride diluent, ethylene, or

  hydrogen chloride and ethylene, to be introduced by the

  which would reduce the concentration of oxygen to half of the previously determined maximum allowable concentration. The invention will be further illustrated with reference to the following description and the accompanying drawing, which presents an embodiment of the method according to the invention, drawing

  wherein the crude 1,2-dichloroethane produced by the oxy-

  chlorination of ethylene (see United States Patent No. 3,679,373 referenced above) and introduced through the pipe 1, is subdivided into two streams passing respectively through the pipe 2 and the pipe 4 The passing current by line 2 is introduced into the liquid phase chlorination reactor. Crude 1,2-dichloroethane

  is introduced into the reactor 10 via line 6.

  crude dichloroethane passing through line 6 is recycled from a circuit in which 1,2-dichloroethane undergoes pyrolytic decomposition to vinyl chloride

  for example, U.S. Patent No. 3,655,787.

  Ethylene is introduced via line 12 into the reaction

  10, in which the line 14 also introduces chlorine containing contaminating amounts of oxygen.

  and, via line 16, a current which will be described later.

  intermittently, as needed,

  ferric chloride by the pipe 8

  tative, this introduction is carried out by moving chlo

  ferric reaction from a tank filled with nitrogen, not shown, via the pipe 8, and sending it into the reactor 10 with a little liquid deviated from the pipe 2, driving 6 or driving

  During the course of the reactor 10, tars accumulate

  The liquid phase is thus intermittently sent through the pipe 18 to the Dopp recuperator 20. Steam 22 is sent via the pipe 24 and the condensate is withdrawn from the jacket. The steam from the recovery vessel 2 O is sent to the reactor 10 through line 28. From time to time tars and other nonvolatile materials are withdrawn through line 30.

  in particular ferric chloride.

  The crude 1,2-dichloroethane exits the reactor 10 through the line 32 and is sent to a distillation column 34, below its lower plate. The column 34 is

  equipped with a reboiler 36, heated by the steam introduced

  by the pipe 38 The liquid coming from the bottom of the

  column 34 is sent to reboiler 36 through line 40.

  The vapor and the boiling liquid are withdrawn from the reboiler 36 through the pipe 42 and are introduced into the column 34 below the lower plate. Liquid is withdrawn from an intermediate plate of the column 34 and is sent via the pipe. 44 to a grinding column 46, on its head plate Column 46 is equipped with a

  reboiler 48, which is heated by steam introduced

  The liquid from the bottom of the column 46 is sent to the reboiler 48 via line 49.

  The steam and the boiling liquid are withdrawn from the reboiler 48 via line 51 and introduced into the

  column 46, below the lower plate 1,2-dichloride

  purified ethane is withdrawn from the bottom of column 46 by the

driving 52.

  The overhead vapor leaving the column 34 is combined with the line 54 and the overhead vapor leaving the column 46 through line 56 and introduced into the

  partial condenser 60 via line 58.

  If the current passing through line 54 and / or line 58 has a tendency to penetrate into the flammability range, it is possible, via line 62, to introduce at the top plate of column 34, to prevent current from entering flammability range, hydrogen chloride, ethylene, or chloride

of hydrogen and ethylene.

  A liquid is withdrawn from the bottom of column 34 through line 64 and subdivided into two streams, one passing through line 66 and the other through line 68 and thence to a distillation column 70 at level of an intermediate plateau The column 70 is equipped with a

  reboiler 72, which is heated by steam introduced

  The liquid from the bottom of the column 70 is sent to the reboiler 72 through the line 73. The reboiler 72 is drawn off the vapor and the boiling liquid through line 75 and introduced into the column 70 below. The bottom plate is withdrawn from the bottom of the column 70, through the pipe 76, a liquid stream consisting essentially of high-boiling products is introduced at the top plate of the column 70 1,2-dichloroethane crude passing by the pipe 4 The overhead of the column 70 is sent to the condenser 80 through the pipe 78 The condensate from the condenser 80 passes through the pipe 82 and is combined with the liquid passing through the pipe 66 to form the flow of

pipe liquid 16.

  The partial condenser 60 condenses a portion of the steam passing through the pipe 58. The condensate is withdrawn via line 84, combined with the liquid stream (which will be described later) passing through the

  pipe 86, and then introduced in the form of reflux the cou-

  The uncondensed steam is withdrawn from the partial condenser 60 through line 90 if the current passing through line 90 and / or the stream of line 98 (FIG. which will be described later) has a tendency to penetrate the flammability range, it will be possible to introduce into the partial condenser 60, via line 92, to prevent the current from entering the flammability range, hydrogen chloride , ethylene, or chloride

of hydrogen and ethylene.

  The steam passing through the pipe 90 is introduced into a water condenser 94 The condensate is withdrawn through line 96 The vapor is withdrawn through line 98 and introduced into line 100 The current passing through the

  line 100 is combined with the current (which will be described later

  thereafter) passing through the line 102, and the combined stream is fed into a refrigerated condenser 106 through the line 104 The condensate exits through line 108 The vapor exits through line 110 and is introduced into line 112 If the current passing through the 110 tends to penetrate the flammability range, can be introduced in the pipe 100, through the pipe 114, and to prevent the current to enter the range of flammability, hydrogen chloride, air ethylene, or

  hydrogen chloride and ethylene.

  The stream of vapor passing through line 112 is introduced into a refrigerated condenser 116 The condensate is withdrawn through line 118 The vapor exits through line 120 and is introduced into line 122 If the current passing through line 120 tends to penetrate in the flammability range, it is possible to introduce into line 112, via line 124, and to prevent the stream from entering the flammability range, hydrogen chloride, ethylene, or chloride

of hydrogen and ethylene.

  The steam passing through the pipe 122 is introduced into a compressor 126, where it is compressed, then it is withdrawn by the pipe 128 If the current in the compressor 126 and / or the current passing through the pipe 128 tends to penetrate in the flammability range, it is possible to introduce into line 122, via line 130, to prevent the stream from entering the flammability range, hydrogen chloride,

  ethylene, or hydrogen chloride and ethylene.

  The gas in line 128 can be

  treated as it may be judged good. However, as its main

  constituents are usually hydrochloric acid

  gene and oxygen, or ethylene and oxygen, or chloride

  of hydrogen, ethylene and oxygen, it will be possible

  introduce the current as part of the feed of an oxychlorination reactor system in which

  ethylene undergoes oxychlorination to produce 1,2-

  dichloroethane. The various condensates passing through lines 96, 108 and 118 are combined and introduced via line 132 into a heater 134, which is heated by the steam introduced via line 136. The heater 134 is

  used to vaporize hydrogen chloride and / or ethyl

  dissolved in the liquid passing through the pipe 132 The vapor exits the heater 134 through the pipe 102 The liquid

  is withdrawn from the heater 134 by the pipe 138 and introduced

The column 140 is equipped with a reboiler 142, which is heated by the steam introduced via the pipe 144. The liquid coming from the bottom of the column 140 is sent to the bottom of the column 140. Reboiler 142 via line 146 Steam and boiling liquid are withdrawn from reboiler 142 through line 148 and are then introduced into column 140 below the bottom plate. Liquid is withdrawn from the bottom of column 140 through line 86. and is combined with the liquid passing through line 84, as described above.

  head vapor exiting the column 140 through line 150.

  The partial condenser 152 ensures the condensation of a

  The condensate is withdrawn through the pipe 154 and introduced in the form

  a reflux at the top plate of the column 140.

  The non-condensed vapor is withdrawn from the partial condenser 152 through the line 156 and introduced into the condenser 158. The vapor from the condenser 158 is withdrawn through line 160 and can be used as desired;

  in a representative way, it is sent to an incineration

  The liquid leaving the condenser 158 is withdrawn by the pipe 162, and can be used as desired

  However, since the main constituents are usually

  chloroform, 1,1-dichloroethane, cis-dichloro-

  ethane, 1,2-dichloroethane, ethyl chloride, carbon tetrachloride and trans-dichloroethylene, the current can advantageously be used as part of the

17 2526788

  charge introduced into an oxychlora reactor system

  in which perchlorethylene and trihydric

  In this regard, US Pat. Nos. 3,256,352, 3,267,162 and 3,296,319, as well as GB Nos. 1,123,477 and 1,276,431. The various chlorinated methanes are advantageously separated during the purification of perchlorethylene and trichlorethylene. this way,

  it is not necessary to have a system designed to purify

  proud of the current passing through line 162 before introducing

  C 2 products in the oxychlorination reactor.

  For clarity in the presentation of the system,

  the figure does not represent different parts of the

  not essential to a full understanding of the invention.

  such as valves, pumps, flow indicators, pressure gauges, pressure reducers, temperature gauges, etc. It is understood that one can make various modifications to the system shown in the figure, without departing from the scope of the invention. For example, the different columns can be bubble columns, perforated tray columns, columns garnished or

  analogous equipment Sources of heat can be used

  other than steam Some of the equipment, piping and procedures can be modified.

  Its conduit 86 can be mounted as a food conduit.

  reactor 10, rather than at the junction of

  84 and 88, the residues can be withdrawn from

  boilers, rather than bottom of columns, partial condensers may be replaced by total condensers; condensers in series can be grouped together, or one can

  increase the number, you can skip the correction column

  46 The person skilled in the art may make any other modifications. The invention will be further illustrated without being in any way

  limited, by the examples below.

EXAMPLE I

  We performed a computer simulation of the systems

  chlorination and purification of the figure, with the excep-

  following statements, made in the simulation: () it was considered that the liquid passing through line 86 was introduced into the reactor 10, rather than being combined

  the flow of liquid passing through line 84 and introducing

  in column 34 by line 88; (2) it was considered that the Dopp recuperator was working continuously and not intermittently; and (3) the steam passing through line 78 was considered directly

  introduced into the reactor 10, without prior condensation

  In the simulation, no diluent was added to lines 92 and 124 Column 34 contained approximately

  real plateaux (and not theoretical ones), and the 'icuide

  pouring the pipe 44 was withdrawn from the column 34 at the twentieth plateau from the top The reflux ratio of the column 34, that is to say the ratio between the flow of the pipe 84 and the flow of the pipe 90, was 30.8 by weight Column 46 contained about

  19 actual trays Column 70 contained about 25

  and the liquid passing through the line 68 was introduced into the column 70 at the eleventh plateau from the top. The column 140 contained about real trays, and the liquid passing through the pipe

  138 was introduced in column 140 at the level of

  The eighth plateau from the top The reflux ratio of the 2 Z cooion: c 10, that is to say the ratio between the flow rate of the duct D 54 and the flow rate of the duct 156, was 15, 5

  Table 1 below presents the characteristics of

  currents passing through the different pipes, as determined by the simulation These results are,

  for the most part, presented with three decimals, independently

  the meaning of the figures after the decimal point The pressures and temperatures presented are nominal and have not been adjusted to take into account the effects of pressure drop across pipes and equipment, or heat transfer between the outside and the outside. the system, and conversely In many cases, the pressures and temperatures are given for currents which, in the street, has seen LQ 1 7 14 1 to 30 the 44th

46 76 56

62 64

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results presented.

EXAMPLE II

  A computer simulation of the systems was carried out

  chlorination and purification of the figure, except that in the simulation it was considered that the

  Dopp worked continuously and not internally

  Mitigation No diluent was added to lines 92, 124 and 130 as part of the simulation.

  34 contained about 78 real (and not theoretical) trays, -

  and the liquid passing through the line 44 was withdrawn from the column 34 at the eighteenth plateau from the top. The reflux ratio of the column 34, i.e., the ratio between the flow in the pipe 84 and the flow rate in line 90 was 44.4 by weight. Column 46

  contained about 19 actual trays Column 70 contained

  about 24 actual trays, and the liquid passing through line 68 was fed into column 70 at

  of the eleventh plateau from the top column 140 contains

  About 35 actual trays were formed, and the liquid passing through line 138 was introduced into column 140 at the twentieth plateau from the top. The reflux ratio of column 140, i.e., the ratio of flow rate. in line 154 and the flow rate in line 156 was 16.2% by weight. The data relating to the currents passing through the different lines and determined by

  the simulation, are presented in Table 2.

  States are, for the most part, given with three decimal places, irrespective of the meaning of the digits after the decimal point. The pressures and temperatures presented are nominal and have not been adjusted to take into account the effects of pressure drop across pipes. and equipment, and heat transfer between the outside and the system, and conversely in many cases, pressures and temperatures are given for currents.

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  which, in practice, should have more pressure

  higher or lower before introduction into the equi-

  or their connection to other currents.

  from the data presented.

  The invention can be used in processes for the purification of 1,2-dichloroethane, operated independently or in combination with one or more other processes as described above. It is however particularly advantageous that one or more purification methods 1,2-dichloroethane according to the invention are

  integrated into a fully integrated complex of

  these chlorinated organics, for example a complex in

  which produces chlorine by electrolysis, 1,2-dichloro-

  ethane by chlorination and / or oxychlorination of ethylene, vinyl chloride by pyrolytic decomposition of

  1,2-dichloroethane, and perchlorethylene and trichloro-

  ethylene by oxychlorination of hydrocarbons and / or hydrocarbons

chlorinated carbides.

  Of course, the invention is not limited to the examples

  embodiments described above and shown, from which we can provide other modes and other embodiments, without departing from the scope of the invention.

Claims (24)

claims   1 Process in which at least one current is introduced   of crude 1,2-dichloroethane comprising inflam-   non-flammable materials and oxygen, in a purification system from which purified 1,2-dichloroethane and one or more streams of other products are withdrawn, characterized in that one or more purification system, to prevent the stream (s) of material in the purification system from entering the flammability range, hydrogen chloride, ethylene, or chloride of hydrogen and ethylene.   Process according to Claim 1, characterized in that the crude 1,2-dichloroethane originates, at least in   part, oxychlorination of ethylene, or chlorination of   ethylene in the liquid phase.   Process according to Claim 2, characterized in that the chlorination of ethylene in the liquid phase has been carried out   carried out in the presence of ferric chloride.   4 Process according to claim 1, characterized in that at least a part of the purified 1,2-dichloroethane   undergoes pyrolytic decomposition to vinyl chloride.   A process for purifying 1,2-dichloroethane, wherein ethylene and chlorine containing a contaminating amount of oxygen are reacted to produce at least one stream of crude 1,2-dichloroethane, which stream comprises flammable materials, non-flammable materials and oxygen, this stream being introduced into a purification system from which purified 1,2-dichloroethane and one or more streams of other products are withdrawn, characterized in that it consists in introducing into one or several points of the purification system, to prevent the flow (s) of products in the system   of purification to enter the inflam-   hydrogen chloride, ethylene,   Hydrogen chloride and ethylene.   Process according to Claim 5, characterized in that the reaction is a reaction in the liquid phase, and   particular is carried out in the presence of ferric chloride.   Process according to claim 5, characterized in   what the chlorine containing a contaminating amount of oxy-   The gene originates, at least in part, from the electrolysis of a   aqueous solution of an alkali metal chloride, in particular sodium chloride.   Process for the purification of 1,2-dichloroethane, characterized in that it comprises the steps of electrolyzing an aqueous solution of sodium chloride to produce chlorine containing a contaminating amount of oxygen; b reacting ethylene and at least a portion of the chlorine containing a contaminating amount of oxygen, in the liquid phase and in the presence of ferric chloride, to produce at least one stream of crude 1,2-dichloroethane   flammable materials, inedible materials flammable and oxygen;   c to introduce this current into a purification system   cation d to introduce into one or more points of the purification system, to prevent the entry of this or these currents in the purification system into the flammability range, hydrogen chloride, ethylene, or Hydrogen chloride and ethylene   e to extract from the purification system the 1,2-   purified dichloroethane; pyrolytically decomposing at least a portion of the purified 1,2-dichloroethane to vinyl chloride; deriving from the purification system a first stream containing hydrogen chloride and oxygen, or ethylene and oxygen, or hydrogen chloride, ethylene and oxygen; introducing said first stream into an oxychlorination reactor system in which the ethylene undergoes oxychlorination to give 1,2-dichloroethane; withdrawing from the purification system a second stream comprising chlorinated hydrocarbons; and introducing the second stream into an oxychlorination reactor system in which perchlorethylene and trichlorethylene are produced.   Process according to any one of the claims   1, 5 or 8, characterized in that hydrogen chloride, or hydrogen chloride and ethylene, is introduced at one or more points in the purification system. in part,   pyrolytic decomposition of 1,2-dichloroethane.   Process according to Claim 1, characterized in that the hydrogen chloride is introduced into the   purification system in one or more points.   11 Process according to claim 10, characterized in that the crude 1,2-dichloroethane originates, at least in   part, oxychlorination of ethylene, or chlorination of   ethylene in the liquid phase.   12 Process according to claim 10, characterized in that at least a part of the purified 1,2-dichloroethane   undergoes pyrolytic decomposition to vinyl chloride.   Process according to Claim 10, characterized in that the hydrogen chloride originates, at least in part,   pyrolytic decomposition of 1,2-dichloroethane.   Process according to claim 5, characterized in   that hydrogen chloride is introduced into the system   purification system in one or more points.   Process according to claim 14, characterized in   what the reaction is a reaction in the liquid phase.   Process according to any one of the claims   11 or 15, characterized in that the reaction takes place in presence of ferric chloride.   Process according to Claim 14, characterized in that the chlorine containing a contaminating quantity of oxygen comes, at least in part, from the electrolysis of an aqueous solution of the chloride of an alkali metal,   especially sodium chloride.   Process according to Claim 14, characterized in that the hydrogen chloride originates, at least in part,   pyrolytic decomposition of 1,2-dichloroethane.   Process according to claim 8, characterized in that the hydrogen chloride is introduced into the purification system at one or more points, the first stream comprising hydrogen chloride and oxygen,   or hydrogen chloride, ethylene and oxygen.   Process according to Claim 19, characterized in that the hydrogen chloride originates, at least in part,   pyrolytic decomposition of 1,2-dichloroethane.   Method according to claim 1, characterized in   that ethylene is introduced into the purification system one or more points.   Process according to claim 21, characterized in that the crude 1,2-dichloroethane originates, at least in   part, oxychlorination of ethylene, or chlorination of   ethylene in the liquid phase.   Process according to Claim 22, characterized in that the chlorination of the ethylene in the liquid phase is carried out   unrolled in the presence of ferric chloride.   Process according to Claim 21, characterized in that at least a part of the purified 1,2-dichloroethane   undergoes pyrolytic decomposition to vinyl chloride.   Method according to claim 5, characterized in   that ethylene is introduced into the purification system one or more points.   The method of claim 25, characterized in   what the reaction is a reaction in the liquid phase.   Process according to Claim 26, characterized in that the reaction is carried out in the presence of ferric chloride. Process according to Claim 25, characterized in that the chlorine containing a contaminating quantity of oxygen comes, at least in part, from the electrolysis of an aqueous solution of the chloride of an alkali metal,   especially sodium chloride.   29.Procédé according to any one of the claims   1, 5, 10, 14, 21, 25, characterized in that at least one stream of the other products, withdrawn from the purification system, comprises chlorinated hydrocarbons, the withdrawn stream being introduced into an oxychlorination reactor system in   which are produced from perchlorethylene and trichlorethylene.   ethylene and oxygen, or hydrogen chloride, ethylene and oxygen, the withdrawn stream is then introduced into an oxychlorination reactor system in which the ethylene undergoes oxychlorination to give 1,2-dichloroethane   30.-Process according to any one of the claims   1, 5, 10, 14, 21, 25, characterized in that at least one stream of the other products, withdrawn from the purification system,   comprises ethylene and oxygen, or hydrogen chloride   of ethylene and oxygen, the withdrawn stream is then introduced into an oxychlorination reactor system in   ethylene undergoes oxychlorination to give 1,2-   dichlorethane, 31.Procedé according to claim 8, characterized in that the ethylene is introduced at one or more points in the purification system, the first stream comprising ethylene and oxygen, or hydrogen chloride ,of ethylene and oxygen.   32.Procédé according to any one of claims 1   at 31, characterized in that the contaminating amount   oxygen is between a substantially higher value than   to zero and about 5% by weight, preferably about   0.05 and about 2% by weight, especially between   0.1% and about 1.5% by weight, based on the composi-   total including chlorine and oxygen.   33.Procédé according to any one of claims 1   at 32, characterized in that the contaminating amount of oxygen is between a value substantially greater than zero   and about 0.5% by weight, preferably between about 0.01 and 0.3%.   ron, and in particular between about 0.02 and 0.2% of the current 1,2 crude dichloroethane.