Integrated method of producing vinyl chloride

 

(57) Abstract:

The invention relates to the production of vinyl chloride. The method is carried out by pyrolysis of hydrocarbons2obtaining equimole mixture of acetylene and ethylene. The mixture hydrochloric and separating the resulting vinyl chloride. The remaining mixture glorious in 1,2-dichloroethane, which paralizuet into vinyl chloride and hydrogen chloride. Hydrogen chloride recyclist on phase hydrochlorination of acetylene. It is preferable to use as the feedstock oxidation product of a combination of methane or metadatareader gas. The technical result is increased productivity, reduction of energy consumption. 2 C.p. f-crystals, 2 tab.

The invention relates to the petrochemical and oil-refining industry and, more specifically, to an integrated process for the preparation of vinyl chloride.

The vinyl chloride is used as the monomer for polyvinyl chloride and Sinton for the synthesis of functional derivatives of various organic compounds.

There is a method in which a raw material for producing vinyl chloride are gaseous hydrocarbons obtained by cracking liquid hydrocarbon oil in an electric degrade acetylene and ethylene in a ratio of ~3:1. The hydrochlorination of acetylene is carried out at a temperature of 120-180oAnd atmospheric pressure in the presence of chlorides of barium and mercury on activated carbon. The resulting vinyl chloride is separated from the rest of the raw stream. The remaining mixture is subjected to chlorination to obtain aliphatic chlorides, including 1,2-dichloroethane (hereinafter EDC). EDC then subjected to pyrolysis to obtain additional quantities of vinyl chloride and hydrogen chloride, returned to the stage hydrochlorination of acetylene.

Using this process requiring mixture of acetylene and ethylene leads to the fact that the process of obtaining vinyl chloride is not balanced on chlorine and hydrogen chloride. For full conversion of acetylene to vinyl chloride required additional node that is not covered in this process, site preparation hydrogen chloride combustion of chlorine in hydrogen. In addition, gas electrocoating contain a significant amount of diene and higher acetylenes, which poison the catalyst hydrochlorination. Increasing the concentration of these undesirable impurities to an acceptable amount (< 0,01%) requires cumbersome purification systems, significantly more expensive price target Preece, balanced for hydrogen chloride and chlorine produced in the manner described in the patent of England 1149798, CL 5 E [2]. This mixture is produced by pyrolysis of light oil having a boiling range 30-140oWith or heavy hydrocarbon feedstock with initial boiling point 190oWith and the subsequent purification of the resulting pyrogas. The pyrolysis is performed by the introduction of the above raw material is heated to 1600-2300oWith steam at a pressure of 10 kg/cm2up to 200 mm/Hg.

From the obtained pyrogas separate coke, carbon black, tarry substances and hydrocarbons WITH3and above, then emit a mixture of acetylene and ethylene. Abgas containing methane, carbon oxides and hydrogen is used as fuel for steam-heated in the first stage.

A mixture of acetylene and ethylene is subjected to interaction with hydrogen chloride at a temperature of 180oC and a pressure of 6 kg/cm2in the presence of mercury chloride on activated carbon, and separating the resulting vinyl chloride. The remaining gas glorious at a temperature of 30-40oC and a pressure of 5.5 kg/cm2. Resulting EDC paralizuet at a temperature of 500oC and a pressure of 7 kg/cm2produce vinyl chloride and hydrogen chloride; the latter returns to the stage hydrochloridecan the place of the usual 10-12%) due to the reduction of the oxides of carbon. However, the process is quite complicated in terms of technology. Thus, superheated steam used at the stage of pyrolysis of petroleum hydrocarbons, get in regenerative furnaces in periodic mode. Initially, the furnace is heated flue gases and then passed through steam. Such an option of a superheated steam requires the use of special expensive fittings, providing work for the switching of threads at high temperatures. Furthermore, the efficiency of these furnaces is low, and the resulting steam is constant temperature. This leads to the formation of pyrogas variable composition and, ultimately, to the instability of the hydrochlorination reactor.

Variant of receiving superheated steam in a continuous mode is also provided in this patent. To ensure continuous receive mode superheated steam is suggested to use the heat from the refractory oxides of aluminum or zirconium. For steam-heated to 2300o[2] the flue gas should have a temperature of not less than 2500oC. These temperature conditions can be achieved only in heat exchangers made of zirconium oxide (alumina can not withstand such temperatures). The use of such onychomycosis points of view because of the complexity and high cost.

Thus, it is achieved in this process some of the increase in output mix equimole of acetylene and ethylene to a balanced hydrogen chloride and chlorine production process vinyl chloride leveled technological inconvenience and high energy and capital costs, as well as the need to use unique equipment.

Known combined process of obtaining vinyl chloride from natural gas or gasoline (Industrial organochlorine products. Handbook Ed. by L. A. Osina /M "Chemistry", 1978, S. 62-65) [3].

In accordance with [3] raw materials for vinyl chloride is produced by pyrolysis of natural gas containing mainly methane. In this case, however, receive a mixture containing ~8-9% acetylene and <0.5% ethylene.

In addition to the impossibility of obtaining equimole mixture of acetylene and ethylene is required for the production of vinyl chloride in a balanced for hydrogen chloride and chlorine process, the process is characterized by a low yield of acetylene, almost complete conversion of natural gas.

To obtain equimole mixture of acetylene and ethylene gasoline or light oil wrap with a boiling point the temperature of the coolant is injected natural gas or vaporized naphtha. Get the sin quenched with water, cleaned of soot and komprimiert up of 0.71 MPa.

Purified sin, containing 8-10% of acetylene and ethylene, is mixed with hydrogen chloride in a ratio that provides 1-2% of the excess of acetylene against stoichiometric, and sent to the reactor tube filled with activated charcoal impregnated with 15% of mercuric chloride. The hydrochlorination is carried out at a temperature of ~130-180oC. the Degree of conversion of acetylene is close to 100%. From the reaction gas in the absorber, irrigated EDC, catch the vinyl chloride. From absorber reaction gas is sent to the chlorination reactor, filled with liquid EDC, which serves chlorine with 2-3% disadvantage against stoichiometric. As the catalyst used ferric chloride. The process is performed at a pressure of 0.51 MPa. In the reactor condensate formed EDC and the residual gases after the alkali treatment is used as fuel in the stages of pyrolysis gasoline and dehydrochlorinating EDC.

EDC after distillation purification is subjected to dehydrochlorination at a temperature of 550oC and a pressure of 1.01 MPa. From the reaction gases emit hydrogen chloride sent to recycling through the hydrochlorination of acetylene and liquid historical relation, than the previous, but its use is associated with a significant amount of oxygen, water vapor and fuel, which adversely affects the value of the obtained vinyl chloride.

Known integrated method of producing vinyl chloride in accordance with the United Kingdom patent 603099 C1 [4]. This method includes the following stages:

(1) cracking of propane or papasteriades gas 1200-1600oC;

(2) the allocation fraction containing ethylene and acetylene from the products of cracking;

(3) processing said fraction of hydrogen chloride in the hydrochlorination reactor at a temperature of 50-200oIn the absence of catalyst or in 50-180oWith the presence of a halide of antimony or bismuth as the catalyst, while the acetylene is selectively hydrochlorizide in the vinyl chloride;

(4) the separation of vinyl chloride from ethylene;

(5) the interaction of ethylene with chlorine in the chlorination reactor to obtain EDC;

(6) pyrolysis received EDC with the formation of vinyl chloride and hydrogen chloride;

(7) separation of vinyl chloride and hydrogen chloride, the subsequent return of hydrogen chloride in stage (3).

In the method [4] , as in [2], the cracking process is carried out in regenera the rata because the process does not use high-temperature superheated steam and raw material costs. However, the first stage of the process - the cracking of propane or papasteriades gas, carried out in regenerative furnaces, associated with the periodic regime, as it was shown by consideration of the method [2]. In addition to the low efficiency of such furnaces, and hence wasteful of fuel consumption is the inability to obtain raw materials for vinyl chloride of constant composition, which leads to unstable operation of the reactor hydrochlorination of acetylene.

In addition, obtaining equimole mixture of acetylene and ethylene in accordance with the method [4] is possible only with the use stage of the release of these gases from the products of cracking, i.e., using additional process units. The result is a concentrated mixture of acetylene and ethylene, the hydrochlorination of acetylene in which, because of ekzotermicheskie this reaction creates certain difficulties when securing a given temperature range.

The present invention, therefore, was the creation of a more technological and economical method of producing vinyl chloride.

The task, in accordance with us is onverse hydrocarbons with getting equimole mixture of acetylene and ethylene with the use of subsequent catalytic hydrochlorination of this mixture, absorption allocation of the resulting vinyl chloride, catalytic chlorination remaining mixture, separation and subsequent pyrolysis formed during the chlorination of 1,2-dichloroethane emitting obtained by pyrolysis of vinyl chloride and hydrogen chloride and the management of hydrogen chloride in phase hydrochlorination of acetylene, characterized in that equinology mixture of acetylene and ethylene is produced by pyrolysis of a mixture of hydrocarbons WITH2; to get equimole mixture of acetylene and ethylene pyrolysis is subjected to a mixture of hydrocarbons, C2any origin; in a preferred embodiment, the pyrolysis is subjected to a mixture of hydrocarbons WITH2the oxidation product of a combination of methane or metadatareader gas.

As a raw material for equimole mixture of acetylene and ethylene can also be used fraction of hydrocarbon, C2obtained by pyrolysis gasoline or broad fraction of light hydrocarbons (NGL). However, economically feasible to obtain this fraction oxidative combination of natural gas or other metadatareader mixtures.

The method in accordance with the present invention is simpler in Tehnologiya this stage (prototype - this is the stage (2)) was possible due to the fact that at the exit from the stage of pyrolysis of hydrocarbons2the sin is equinology mixture of acetylene and ethylene. The sin obtained in accordance with the present invention, contains much smaller than the cracking of propane or papastergiadis gases, the amount of resinous substances and higher acetylenic compounds, it can be used without any purification in the next stage of the process (3), i.e., hydrochloridebuy.

The proposed method for the preparation of raw materials for vinyl chloride not only reduces energy consumption at the stage of pyrolysis and subsequent stages, but also to increase the service life of the catalyst and mezhregionalnogo period of reactor operation, the hydrochlorination of acetylene. Use a diluted mixture of acetylene and ethylene in hydrochloridebuy reduces heat dissipation, ease of temperature control process to ensure the stable operation of the hydrochlorination reactor and the use of the catalyst tubes of larger diameter. Due to this increase, compared with the method of the prototype, the performance of the reactor.

Additional economic benefits in accordance with the present invention in comparison with obtaining such cracking of propane or papasteriades gas [4], so as to cook the same amount equimole mixture will need a smaller reactor size. When using reactors hydrochlorination of acetylene same size performance of the reactor in the present invention is much higher.

The invention is illustrated by the following examples of specific performance.

Example 1

A mixture of hydrocarbons WITH2with an ethylene content of not less than 60 vol.% the oxidation product of a combination of methane is subjected to pyrolysis in a stream of high-temperature medium at a temperature of 1400-1600oC. At the outlet of the reactor sin, containing equinology mixture of acetylene and ethylene, quenched and sent to the hydrochlorination, where the catalyst in the reactor tubes of acetylene get the vinyl chloride. In the next stage of the process, the vinyl chloride absorb the solvent, which is used as EDC. The gas mixture from the stage of absorption, mainly containing ethylene, directed at the stage of chlorination in EDC and subsequent pyrolysis of the received EDC into vinyl chloride and hydrogen chloride; the latter returns to the process at phase hydrochlorination of acetylene. The vinyl chloride from the stage of pyrolysis of EDC combined with obtained ovary product.

Expense ratios of oxygen, water vapor, fuel and hydrogen-containing gases, as well as other indicators of the pyrolysis process are given in table. 1, the subsequent stages of the process - in table. 2.

Example 2

Equinology mixture of acetylene and ethylene receive under the conditions of example 1 of hydrocarbons WITH2with ethylene content ~80 about. % isolated from pyrolysate gasoline or LPG. The remaining stages of the process is carried out analogously to example 1. The conditions and results of the implementation of the process of obtaining vinyl chloride are given in table. 1 and 2, respectively.

Example 3 (comparative)

Equinology mixture of acetylene and ethylene receive under the conditions of example 1, using as feedstock propane or propane-butane fraction containing propane not less than 60 vol.%. The volume of the reaction zone is 0.17 m3. The remaining stages of the process carried out analogously to example 1. The conditions and results of the implementation of the process of obtaining vinyl chloride are given in table. 1 and 2, respectively.

Example 4 (comparative)

Equinology mixture of acetylene and ethylene is produced from propane or propane-butane fraction with contents3is hydrocarbon of not less than 60%, in accordance with ways is it 15 seconds. From the resulting cracking of gas by rectification allocate equinology mixture of acetylene and ethylene. Further process steps carried out in accordance with the prototype. Conditions and results of the stage equimole mixture of acetylene and ethylene are given in table. 1.

Low productivity of the reactor at the stage of pyrolysis (table. 1) due to technological regime used in the method [4], providing a contact time of at least 15 seconds.

Conditions and results of subsequent stages of the process are given in table. 2.

Example 5 (comparative)

Natural gas containing ~ 94% methane is subjected to oxidative pyrolysis at a temperature of 1540oC. Indicators and the results of the process of oxidative pyrolysis of methane is given in table. 1, the subsequent processing stages of the pyrogas in the vinyl chloride - in table. 2.

As can be seen from the data table. 1 and 2, an integrated method of producing vinyl chloride in accordance with the invention (examples 1 and 2) allows not only to reduce the consumption of raw and auxiliary materials, but at the same time to improve the performance of the process at all stages.

In addition, simplified technology by obtaining raw DL is without any additional technological operations. The advantages of using this material appear at the subsequent stages, increases the productivity of the process for vinyl chloride with simultaneous reduction of its losses and loss of hydrogen chloride.

The present invention without substantial investment can be made in petrochemical plants producing vinyl chloride using the process, balanced on chlorine and hydrogen chloride. In the proposed process does not occur, as in the method prototype periodic excess hydrogen chloride and chlorine, requiring neutralization and subsequent treatment of wastewater from the products of neutralization or disposal. This significantly helps to improve the environmental friendliness of the process of obtaining vinyl chloride.

1. Integrated method of producing vinyl chloride, comprising pyrolytic conversion of hydrocarbons with getting equimole mixture of acetylene and ethylene, using subsequent catalytic hydrochlorination of this mixture, the absorption allocation of the resulting vinyl chloride, catalytic chlorination remaining mixture, separation and subsequent pyrolysis formed during the chlorination of 1,2-deflorated on phase hydrochlorination of acetylene, characterized in that equinology mixture of acetylene and ethylene is produced by pyrolysis of a mixture of hydrocarbons, C2.

2. The method according to p. 1, characterized in that the pyrolysis is subjected to a mixture of hydrocarbons, C2any origin.

3. The method according to p. 1 wherein the pyrolysis is subjected to a mixture of hydrocarbons, C2the oxidation product of a combination of methane or metadatareader gas.

 

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