DE1619707A1 - Process for the evaporation of decomposable substances - Google Patents

Description

Jiixa IMPERIAL CHSfICAL INDUSTRIES LIMITED, London S.W. Great Britain,

concerning procedures eur evaporation of sersetelichon substances.

Priorities February 21, 1966 and January 30, 1967 Great Britain

The invention relates to an improved method mn Evaporation τοη substances that tend to calibrate when heated quickly JKU eerseteen.

At present, many industrially important chemical reactions, particularly organic chemical reactions, take place in the Execution of the phase “A common requirement for such reactions is to have one or more participants in the reaction

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the introduction of the same into the reaction & cne to vaporize " Here, heat is transferred from another medium to the material to be evaporated. Such a heat transfer process can be direct or indirect *

In the first case a hot liquid, a vapor or a gas in contact with the cash register of the material to be vaporized brought, where it is e.g. conducted over or into the mass The heat-emitting medium thus comes into direct contact Contact with the au evaporating material and mix also usually associated with this. Examples of devices of this type are the bubbler vaporisers.

In the second case, the heated material does not come into contact with the tu evaporating material, but it gives up its heat to a solid, usually of metal existing container from which is immersed in the material to be evaporated or containing it wherein the heat indirectly through the Mediation of a thermally conductive third body is transmitted. Devices of this type are the sleeve and tube evaporators. This also includes flash evaporators, in which the material to be evaporated is dripped or sprayed onto a heated, inert heat-supplying surface, expediently a metal plate, which is kept at a temperature such that a very rapid heat transfer and consequent rapid evaporation takes place.

Trots of the multitude of sur vaporizers available and evaporation processes still present considerable difficulties in achieving satisfactory results Evaporation of thermally unstable substances, in particular of thermally unstable organic substances with a relatively high boiling points such substances decompose

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often during the evaporation process, with tarry, resinous or racy deposits on the heat exchange surfaces leave behind which deposits are very poor thermal conductors and thus the heat exchange process seriously affect and worsen the effectiveness of the rasoh vaporizer. In this description substances, which tend to a pyrolytic decomposition, whereby they have disruptive tar-like, resinous or carbon-containing decomposition products lifer », conveniently referred to as" heat-decomposing "substances.

You have difficulty in evaporation from warm sea saltichen Substances in conventional evaporators are obvious »The Heat exchange surfaces are quickly contaminated and the heat transfer decreases. They remove viscous deposits also represents a serious cleaning problem «.

The present invention overcomes these difficulties avoided by using a different type of heat transfer surface is used, through which the substance to be evaporated heat is fed.

In accordance with the present invention, there is provided an improved method for vaporizing a thermally decomposing organic substance, which is liquid at room temperature, proposed, which is characterized in that the Substance in the liquid state introduced or applied to a fluidized bed or a fluidized bed made of finely divided material which is at a temperature that causes rapid thermal decomposition and, consequently, rapid evaporation of the Brings about substance.

Requires a more specific and developed form of the invention

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serves the fluidized bed or the fluidized bed, in or on which the heat-decomposing material is passed, not only to vaporize the heat-decomposing material, but also to cause a reaction in which the vaporized heat-decomposing material with other reactants entering the Fluidized bed is introduced, a chemical reaction enters into · For example, the gas or the steam, which to the Fluidization of the particulate material can be used, a Her reactant, and / or the fluidized Fluidized bed material can also act as a catalyst for the Serve reaction.

The fluidizing gas can be a gas or a vapor which is inert to the substance to be vaporized, e.g. Air, nitrogen, carbon dioxide, hydrogen, hydrogen chloride, chlorine or even a vaporized organic substance such as ferrochlorethylene. In some cases the gas or the steam -> be one that serves as a diluent in a subsequent chemical reaction to which the vaporized heat-decomposing substance is to be subjected

On the other hand, as already indicated, the fluidizing gas can also be a component of the chemical reaction system. 3o can, for example, if the heat-decomposing substance is a To be subjected to chlorination, the fluidizing gas is to be chlorine and the process can be carried out in such a way that a partial or complete reaction of the chlorine with the heat-decomposing substance takes place. So can a fluidized bed with a suitable temperature can be used for a · evaporation of the heat-decomposing substance and a partial To achieve reaction between this and the chlorine, and the vaporized outflowing gases can be fed to a further reaction zone, where a further reaction between the

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Chlorine and the vaporized, heat-decomposing substance takes place » Serious processes can conveniently be carried out when the fluidized particulate material is one that is not catalytically active. The following Reaction of the chlorine with the evaporated heat-decomposable Substance can be carried out in the presence or absence of a catalyst. Such processes in which an evaporation and a reaction of chlorine with the heat-decomposing substance takes place in a fluidized bed according to the invention, are optionally carried out in such a way that the Chlorine is diluted with an inert gas suitable for the particular chlorination reaction envisaged. For example, the chlorine can be diluted with hydrogen chloride or nitrogen. The heat-decomposing substance can also be used in liquid form, in a stream of chlorine-containing oas are injected, which then flows on to fluidize the Hasse of the particulate fluidized bed, where then a partial or complete reaction takes place.

In another case, a gas such as chlorine which is ultimately to serve as a component of the reaction system may be included such conditions, such as temperature conditions in the Fluidized bed can be used that it serves essentially as an inert gas. In this case there may be a premature reaction in the evaporator can be avoided or kept low by keeping the evaporation temperature at a value below that at which a reaction occurs to a substantial extent. In a subsequent stage, the chlorine and the Vaporized wäxnesereetzliche substance for example under higher Tea temperature conditions in the absence of a catalyst or in In the presence of a catalyst such as activated carbon impregnated with sodium sulfate.

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A wide variety of inert materials intended for use as a particulate fluidized bed can be used of conventional materials, such as sand, aluminum oxide or silicon dioxide, (in particular the microspheroidal forms of these substances, such as the highly abrasion-resistant microspheroidal silicon dioxide), glass, metals, metal carbides, silicon carbide, high-density carbons and numerous other inert materials.

If, as already indicated, it is desired to use the fluidized bed not only as an evaporator, but also dasu, to cause a chemical reaction, then the fluidized heat exchange material can serve both as a heat exchange medium and as a catalyst for the reaction. In these In some cases, the heat exchange material itself can have a catalytic activity, or it can consist of one of the conventional ones Catalyst supports, such as talc, diatomite, carbon, silicon dioxide, aluminum oxide and the like, which are impregnated with catalytically active agents, e.g. with oxidation or chlorination catalysts.

However, the common feature of all these embodiments of the invention is, as is readily apparent, the use a heat exchange medium in the form of a particulate Fluidized Bed · There are several important advantages of working with this method, which will now be discussed.

The first and most obvious advantage is the well-known high heat dissipation and uniformity of temperature control that can be achieved through the use of a fluidized bed; this is generally known and does not require any further detailed explanation.

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The "broad point is that this new evaporation process avoids in a very simple manner the difficulties associated with the use of a fixed and often relatively poorly accessible heat exchange surfaces occur · The latter surface is quickly contaminated and the device must then be taken out of service as long as the water exchange surface is cleaned, a «job that itself brings with it many difficulties due to the aging of the degrees. Yes, the opposite ee in the new form of an evaporator .light, all or part of the heat exchange material for cleaning to remove without interrupting the work of the evaporator. QevUneohtenfalle came the operation continuously designed (such as, for example, by using the "standpipe" provision, which is often used in a fluidized bed mode of operation in the Petroleum refining industry is used), using a rope of the heat exchange material continuously drained, cleaned (occasionally by heating in air to remove the tarry, resinous or carbonaceous deposits) and is returned to the evaporator.

Another point is that the constant movement and friction to which the individual particles of the fluidized heat transfer medium are subject to the system to a certain extent make self-cleaning * That on the particles due to a Pyrolytically «decomposition of the substances to be evaporated deposited material tends to be abraded in the layer and to be divided up so that it does not build up to such an extent that I form stubborn layers of stubborn material. In some cases where the decomposition process carbon is charred and the carbon is rubbed off the particles by the friction in the layer, the carbon, provided that it is calibrated in its density from the heat exchange material

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differs from the latter, for example with the help of a Cyclones become old separated. The layer can thus be made self-cleaning in some cases.

It is emphasized that the invention is applicable to the evaporation of a "wide variety of heat-decomposing materials and can be used in conjunction with and to facilitate a variety of gas-phase chemical reactions. In particular, the present process is useful for the evaporation and gas-phase chlorination of a chlorinated hydrocarbon feed." , which contains 1 to 4 carbon atoms in the molecule and which, if it contains 2 to 4 carbon atoms, can be saturated and / or unsaturated. Mixtures of chlorinated hydrocarbons, such as those used as residues in the production of trichlorethylene, vinyl chloride and others chlorinated Hydrocarbons obtained by known processes can also be used in the process according to the invention. Such chlorinated hydrocarbon mixtures which contain unsaturated chlorinated hydrocarbons, such as, for example, unsaturated oxo compounds such as tetrachlorobutadiene and pentachlo rbutadiene, when heated in standard evaporators have a particularly strong tendency to separate polymeric and tarry material _o Saturated chlorinated hydrocarbons such as tetrachloroethane and 1,2-dichloroethane are also heat-decomposable, especially if they are contaminated with carbon tetrachloride or chloroform, and can be used in methods according to the invention can be used. The temperature used in the present process is at least that temperature which is sufficient to vaporize the heat-decomposing substance, and it changes with the decomposition of the substances mentioned. a chlorination reaction takes place

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chlorinated Kolilenwaaeerstoffbeschickung of the type described, temperatures in the range from 150 to 750 ⁰ C are used. At the lower temperatures within this range, if chlorine is used as the fluidizing grass, evaporation of the chlorinated hydrocarbons occurs, while at increasing temperatures, for example 200 to 450 ^° C., a partial N. A wise reaction takes place with the formation of an intermediate product mixture, and if the temperature is increased further, then a complete reaction occurs, whereby a final product is obtained which, according to the particular reaction conditions used, contains carbon tetrachloride and peroethylene.

The invention is hereinafter referred to as evaporation and the Qaaphase chlorination of water-decomposing aliphatic chlorinated hydrocarbons are described, but it must be pointed out it should be pointed out that these are illustrative only and that the invention in no way relates to evaporation of this class of substances, or the application to the evaporation process in connection with the gas phase chlorination of these substances is limited.

The following examples explain the invention and limit it but in no way one.

example 1

The device consisted of a heat-resistant glass container of 35 ora length and 7.5 can in diameter, which could be heated from the outside with the help of an electrical device. A sintered glass pane was attached to the underside of the evaporator, which served to carry a 20 cm deep sand sheet with a particle size of 75 to 150 μm. Stioketoff and

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Chlorine at room temperature was introduced into the underside of the tube (maintenance of the glass pane), whereby the sand was fluidized. A liquid mixture of chlorinated hydrocarbons was passed at a temperature of 50 ^° C. onto the top of the layer. The effluent gas was condensed to recover the organic material. Five experiments were carried out under the conditions given in Table I. The feed rate of the liquid mixture of chlorinated hydrocarbons was 2.46 1 / et in all experiments.

Table I.

Try B-Ho. Speed of the
Fluidization gases Shift temperature 1
2
3
4th
5 / Min N _2/10 R
/ Min C1 _2/10 R
/ Min C1 _2/10 R
C1 ₂ / 1O Rl / min
C1 ₂ / 1O Rl / min 175 ⁰ C - 210 ⁰ C
17O ⁰ C - 185 ⁰ C
210 ⁰ C
235 ⁰ C - 260 ⁰ G
21O ⁰ C - 235 ⁰ C.

The organic feed was analyzed by gas phase chromatography analyzes what was also done with the recovered organic material that left the fluidized bed after condensation. The results in which the concentration of the component the loading and the recovered material in weight? » are shown in Table II.

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Table II

CO

OD

co

UJ

CD

33

I. Attempt 1 Won
nenes
Mate
rial Attempt 2 <
Won
nenes
Mate
rial Attempt 3 i Oewon ^ -
nenes
Mate
rial 1 Attempt 4
j Qewon
nenee
Mate
rial Attempt 5 Won
nenes
Mate
rial I.
!
!
j
i Besohik
kung 0.4 I.
Soling
kung 0.6 Be »chlk-
kung 0.8 Loading
kung 0.5 Β ·· chik-
kung i
ι light fabrics 0.9 11.7 1.2 12.7 0.9 19.1 1.0 9.0 0.01 ■ CHCl = CCl ₂ 14.7 52.6 18.7 47.1 23.3 46.1 25.9 47.1 0.02 0.14 C ₂ Cl ₄ 52.2 0.9 48.4 0.9 49.0 0.4 48.7 0.4 0.03 as ymmo tris eheβ
CgHgClj, 0.7 0.6 0.9 0.4 0.4 0.3 0 _s 4 0.3 CHBr = CBr ₂ 0.4 1.3 0.4 1.8 0.3 0.9 0.3 0.9 symmetrical
C ₂ H ₂ Cl ₂ J 1.3 0.4 1.6 3.2 0.9 4.7 0.9 18.4 0.93 C ₂ HCl ₅ 0.4 27.5 0.5 28.7 0.8 23.7 0.9 19.9 0.64 0.08 ^C 2 ^Ci o 25.0 0.2 24.0 0.2 20.7 0.2 2O ₁₁ 2 0.2 0.62 ι high boiling point
'Substances incl. 0.2 4.1 0.2 4.4 0.2 3.5 0.2 3.5 4.2 4.1 3.5 3.5 0.02 GK ₂ CI CHCl ₂ 0.02 98.82 ! ^C 2 ^E 2 ^C1 4
. (symmetrical)
i 99.67

cn, CD CD

Be let su observe that in all experiments except the Trials 4 and 5 the material obtained did not differ noticeably from the Beechiokungeiomaterial during the trials 4 and 5 a certain conversion of triehloroethylene into pentachloroethane took place.

The liquid was thus evaporated, and after a running time of about 20 hours the sand acted as a plumbing medium still satisfactory, although carbon blackened it.

Example 2

The evaporator consisted of a heat-resistant glass tube 35 cm long and 7.5 cm in diameter, which was heated from the outside by an electrical device. At the bottom of the reactor was a perforated part which was used to support 400 g of microspheroidal silica with a particle size of 60 to 100 microns. Hydrogen chloride (at atmospheric pressure) was introduced at the bottom of the tube (below the perforated plate) at a rate of 25 to 50 liters per hour, causing fluidization of the silica particles. The temperature of the layer was kept in the range from 350 to 400 ^{° C. by setting the electrical heating device accordingly.}

A liquid mixture of chlorinated hydrocarbons was drawn on top of the layer at a rate of 200 g / st introduced o The composition of this mixture was approximately the following:

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O- and t-Diohloroethylene 3.8 Ji

OBCl, £ 0.8

OH ₃ CCl ₅ 0.1 %

CH ₂ CLCH ₂ Cl £ 10.6

CHCl-OCl ₂ 7.8 #

CH ₂ CLCHCl ₂ 6.4 *

CCl ₂ -CCl ₂ 28.7 #

^ CHCl ₂ .CHCl ₂ $ 25.9

Chlorinated Cj-hydrocarbons), including tetrachlorobutadiene, pentaohlorbutadiene and others ία ρ <ί

high-boiling chlorinated carbon- '* »^

Hydrogen and a small amount of colloidal carbon

Note : All percentages are expressed in weight.

The liquid was thus evaporated, and after the evaporator had been operated continuously in this way for a month, the silicon dioxide contained: only about 2 wt% carbon and still served as a completely satisfactory Liquid transfer medium, although it had turned black,

Example 3

The evaporator consisted of a nickel tube 4.4 cm in internal diameter and approximately 15 cm in length, which was connected to an electric Facility could be heated from the outside. On the bottom A perforated wedge was attached to the reactor, which served to carry 150 g of microspheroidal silicon dioxide with a cell size of 60 to 100 μm. The top of the pipe expanded and formed a large cylinder of 10 cm Inner diameter and 25 ora length, which is called Borehigungseone served. Chlorine was applied at a pressure of 4 to 8 atmospheres (changed from time to time during the duration of the experiment) on the underside

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The drilling maintained the plate with variable speeds τοπ 400 to 1000 g / st introduced, whereby the silicon dioxide particles were fluidized. The temperature of the layer was kept at approximately 400 ^° C:

A liquid mixture of chlorinated hydrocarbons was made aof the layer at a rate of 700 ms 1400 g / st directed. The composition of this mixture was approximately the following:

₄ 1.7 pounds

CHCl-CCl ₂ 19.5 %

CCl ₂ -CCl ₂ 61.0 #

CHCl ₂₀ CHCl ₂ 0.5 #

GHCl ₂ .CCl ₂ 0.7? 6

CCl ₃ .CCl ₃ 9.3 %

Chlorinated hydrocarbons ^) einsehließliöh Tetrachlorbutadien and) 6 9 & other high-boiling chlorinated coal) * * bons ")

Remark ; All parts are expressed by weight.

The liquid was thus evaporated and after the evaporator was operated continuously in this way 3 months, dae silica contained only 2 1/2 percent -. & Carbon and served still entirely satisfactory as a fluidizing, although it had become black.

Example 4

The gate direction consisted of a tubular metal reactor with an inner diameter of 30 cm and a length of 9 m (including the calming zone), from the outside with the help of an electrical

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Establishment could be called. A perforated part was attached to the underside of the reactor, which tied a layer on 640 kg of sand with a part size of 50 to 250 fi. Chlorine and. rarüekgeftihrter Perchlorathylendampf, vorerhitst to 17O ° C _V were introduced through a tube which was attached to the bottom of the reactor. A feed of liquid chlorinated hydrocarbon fuels was introduced through another pipe, which was attached to the underside of the reactor and led directly into the bed. These chlorinated hydrocarbons were vaporized in the bed, and the chlorine and the combined vapors flowed through the reactor at a rate of 15 cm / sec, thereby keeping the sand in a fluidized state.

The reaction conditions and the results obtained were as follows:

Reaction temperature 550 to 560 ° D

Contact time 54 seconds

Pressure 2 ata

Loading 44.5 i "chlorinated

Hydrocarbon residues (containing 0.6 # C, compounds) the approximate composition

55.5 5 * C £ \, repatriation

Molar ratio of Clg / charge residues 2.65

Weight of the remnants 34.5 kg / pc

Weight of C ₂ Cl ₄ 45.2 kg / st

Weight of Cl ₂ 41.0 kg / st

Leaking gas: organic matter 110 kg / h

HCl 4 kg / st

Cl ₂ 4 * 6 kg / st

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Molar ratio of Cl ,, / CCl ₄ im

outgoing gas 0.155 / 1

Composition of the liquid

organic product (Gewo-τΟ 59.5 CCl ₄ -

38.0 C ₂ Cl ₄ 2.5 C ₂ Cl ₆ 0.6 C ₄ Cl ₆ 0.2 C ₆ Cl ₆

ISs a hetto product of 97.9% by weight CCl _{4 was} obtained.

Example 5

The reactor beetand of an ⁿ Inconel "pipe Clnconel" is a registered trademark) of 5 om inside diameter and approximately 75 cm in length, which was equipped with a central thermocouple pocket. The pipe was connected by electrical equipment. At the bottom of the reactor, a sintered glass disc was placed, which served as a carrier for the sand with a particle size of 100 to 15Ou * The top of the reactor tube expanded to form a larger tube of 10 cm in inner diameter and 30 cm length, which served as a calming zone . Chlorine was introduced under pressure to the bottom of the reactor at a rate of 900 g / h, thereby fluidizing the sand. A liquid mixture of chlorinated hydrocarbons wurda with a temperature of 20 ⁰ C and a rate of 1200 g / atm into the reactor at a point approximately 3 cm above the disk inserted "The sand took in fluidiserten state, a 75 cm length of the reactor. The mixture had the following composition on the basis of mol / tool: 29 % 0 ^ 03.2, -28.4 $> CH ₂ CLCHCl ₂ O 28 # sym "and asym. C ₂ H ₂ Cl ₄ , 14» 6 % C4- Compounds including tetrachloro, Pentachloruad Hexaohlorbutadieuo

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Eb three experiments were carried out, a pressure of 3.5 ata prevailing in each case in the reactor. The first experiment was carried out with a contact time of 9.2 seconds and the second and third experiments with a contact time of 9.3 seconds. The contact time is expressed as all net reactor volumes assuming 60-6 void space formation in the belt. The other reaction conditions and the composition of the product are given in Table III.

Table III

Molars
Feed
retirement
hold
by Cig /
organi
ting
Fabrics Composition of the product $ mole / mole C ₂ Ci ₄ Byrne,
C ₂ H ₂ Cl ₄ C ₂ HCl ₅ ^C 2 ^C1 6 C ₄ Ci ₆ ReaJc-
tione-
temp. 1.55
1.57
1.59 C ₂ HCl ₅ 34.8
44.8
49.6 3.6
2.3
1.1
" 17.0
7.6
2.0 2.3
2.3
'1.8 16.5
15.7
19.0 400
450
500 25.9
27.3
26.7

The liquid was thus evaporated and a reaction occurred with the chlorine. After the device a month had been operated, the sand worked as fluidizing still fully satisfactory, even though he had turned black by carbon ₀

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Claims (1)

Patent claims: 1. Process for vaporizing a self by the action of heat Corrosive organic substance, which is liquid at room temperature, characterized in that the substance in the liquid state in a fluidized bed or a fluidized bed finely divided material is introduced or applied, which is present at a temperature that a rapid water decomposition and consequently causes rapid evaporation of the substance. * 2. The method according to claim 1 for evaporation and others Chlorination of a substance which tends to decompose when exposed to heat, characterized in that the process in the catfish is directed because & «in · partial or complete implementation of chlorine takes place with the substance in question. 3 · Method according to claim 2 for evaporation and others Chlorination of chlorinated residues, which are obtained in the production of chlorinated aliphatic hydrocarbons, characterized in that the residues in liquid »state in a fluidized bed of finely divided material introduced and the residues are reacted with chlorine at a temperature of 200 to 700 ° C, the residues off partially chlorinated aliphatic hydrocarbons with 1 to 4 carbon atoms and at least a major proportion by weight of those introduced into the fluidized bed, partially represent chlorinated aliphatic hydrocarbons. 4. The method according to claim 3, characterized in that the chlorinated residues used as a batch contain one or more unsaturated chlorinated hydrocarbons with 1 carbon atoms. BATH ORIGINAL 009883/1731 5. The method according to claim 4, characterized in that the chlorinated residues tetrachlorobutadiene and / or pentachlorobutadiene contain. 6. The method according to any one of claims 1 to 5, characterized in that that the fluidized bed is generated by a gas consisting of molecular chlorine. 7. The method according to any one of claims 2 "to 6, characterized in that that finely divided material is a catalyst for the conversion of chlorine " 8. Method naoh one of claims 1 to 7 _? characterized in that the finely divided material is an inert material. 9. The method according to one of claims 1 to 8, characterized in that the fluidized bed is kept at a temperature of 200 to 450 ° C. 10 * Method according to one of claims 1 to 9 »characterized in that that the vaporized material is fed to a further reaction zone in which the reaction between the Chlorine and the vaporized material is carried out in the presence or absence of a catalyst. . H. f IHCXt. D ¹ PL-IM *. ψ HKP DlPL-ING. β. ITA 009883/1731