DE2905574C2 - Process for the production of vinyl chloride from acetylene and hydrogen chloride - Google Patents

Description

25th

The main patent 28 20 776 relates to a process for the production of vinyl chloride from Acct> len and hydrogen chloride. On the one hand, the acetylene is obtained in a highly concentrated form by wet gasification of carbide; on the other hand, the hydrogen chloride is only present in the feed gas in a comparatively small proportion of about 50% by volume. This feed gas is supplemented by combustion gases that are obtained by reducing combustion of a fuel with a low hydrogen content, largely, ie 90-95% by volume, contain carbon dioxide, have a temperature of about 1240 ^° C. and are then used for the pyrolysis of chlorine-containing metal compounds will.

The main patent accordingly provides a process for the production of vinyl chloride by reacting dry acetylene with hydrogen chloride, the latter in a diluted form with a proportion of approx. 50 Vol .-% is contained in the feed gas The implementation is on the one hand with through wet gasification of carbide obtained acetylene and on the other hand with by pyrolysis of a chlorine-containing metal compound, preferably Magnesium chloride dihydrate, by means of hot, by reducing combustion of a fuel with low hydrogen content and mostly (90-95% by volume) carbon dioxide (CO2) containing Combustion gases obtained hydrogen chloride carried out.

The process is carried out in such a way that the CO2 content saturates that of the carbide gasification accumulating milk of lime is sufficient.

The high temperature of the carbon dioxide gas used for pyrolysis can, however, only under completely extreme and specific operating conditions can be achieved. Instead of such a high heat capacity with the fuels mentioned in the main patent Bringing the combustion gases obtained into the pyrolysis of magnesium chloride dihydrate can be a the same result according to the present additional invention more expediently by burning a reaction-related The amount of coke in the reaction furnace can be achieved with oxygen or air, but the amount of COr that occurs is not sufficient to reduce the amount of coke Transferring milk of lime from carbide gasification completely to Ca carbonate. That's why this will Carbon dioxide deficit due to carbon dioxide additionally fed into the synthesis gas stream after the pyrolysis reaction balanced.

The amount of coke to be burned is therefore after that required for the pyrolysis of the magnesium chloride dihydrate Measure the amount of heat.

It is advisable to mix the dihydrate well with finely divided coke, whereupon in the oxygen or Air flow, both the combustion and the pyrolysis reaction takes place according to the following equations:

2 C + 2 O ₂ = 2 CO ₂ + 2 x 94.0 kcal

MgCl ₂ X 2 H ₂ O + (2 CO ₂ ) = MgO + H ₂ O + (2 HCl + 2 CO ₂ ) - 52.5 kcal

For 1 kg of dihydrate, about 400 kcal should be consumed for full conversion. According to the reaction equation one mole of dihydrate produces two moles of hydrogen chloride using 52 j kcal.

If an equimolar mixture (HCl + CO2) is produced should be what is to be striven for as a technological requirement. then theoretically there is an excess of heat of (2 χ 94.0 - 523) kcal = 135J kcal per mole.

During the pyrolysis, according to the reaction * equation at most * a part of the required amount of carbon dioxide, namely 52.5: (2 94.0) = 28% can be obtained. In reality, however, this proportion is only just under 10%. since the reaction temperature is optimal only at 600 ° C.

Thus, in order to meet the heat requirements of the pyrolysis reaction to cover, an amount of coke is needed that is only about 10% of the carbon dioxide required for the Syngas corresponds. The rest must then are supplied to produce an equimolar gas mixture with a composition HCI + COj. before all about - as already mentioned - one for the transfer, the one with the acetylene! . «Division accruing Milk of lime to have a sufficient amount of carbon Λ oxide in the synthesis gas in Ca carbonate.

The course of the method according to the invention is shown in the attached example for a performance of lOOOOOVS / a 100,000 tons of vinyl chloride per year evident.

example

For an output of 100,000 tonnes of vinyl chloride per hour, approx. 7300 kg = approx. 4500 Nm ^{3 of} hydrogen chloride are required. For this performance the magnesium chloride dihydrate consumption (MgCl ₂ χ 2 H ₂ O) is:

730Ox 131.3 / 70.96 = approx. 13 600 kg / pc.

At the same time, 4500 NmVSt carbon dioxide are used, Of which, however, a part of only 4500 χ 0.279 = approx. 1250 NmVSt in the pyrolysis furnace by burning Coke with 125ONmVSt oxygen or 6250 NmVSt

Air, to deliver the amount of heat required to carry out the exothermic reactions of dehydration and hydropyrolysis, is generated. The remainder of carbon dioxide required for processing the amount of lime milk produced during acetylene production, ie 4500-1250 = 3250 NπA'St, is fed to the reaction gas from other raw material sources after the pyrolyse. For 1 Nm ^J CO ₂ , 0.54 kg of carbon C are required , so for the above output approx. 675 kg / pc of carbon.

Then feeding to the pyrolysis furnace 13 600 kg / h Magnesium chloride dihydrate, 675 kg / h coke and 1,250 NmVSt oxygen or air NmVSt 6250 and performs the pyrolysis reaction from approximately 600 ⁰ C. The gas composition after pyrolysis is as follows (in NmVSt):

oxygen air Hydrogen chloride
Carbon dioxide
nitrogen 4500
1250 4500
1250
5000 Total 1 5750 10750 Additional CO2 3250 3 250 Total 2 9000 14000 Reaction gas, Vo! .-% - HC! 50.0 32.0

After the pyrolysis furnace, 3250 NmVSt carbon dioxide are added to the reaction gas. The reaction gases are cleaned afterwards, cooled, whereby the heat utilization takes place, and dried.

The hydrochloric acid that separates out during the drying process is usually distilled and the dry one Hydrogen chloride added to the reaction gas The reaction gases contain Vttn 50.0 (oxygen combustion) or 32.0% by volume (air combustion) hydrogen chloride and are fed into the vinyl chloride synthesis.

The advantages to be gained by carrying out the reaction according to the present invention can be as follows are listed:

Compact construction of the system, better heat conduction (= smaller heat losses) and reduction of Demands on the material quality of the materials used for apparatus construction, are caused by this Advantages in investment and operating costs.

Claims (1)

Claim: Process for the production of vinyl chloride from acetylene and hydrogen chloride, according to patent 28 20 776 the acetylene is obtained in a highly concentrated form by wet gasification of carbide, the hydrogen chloride only with a comparatively small proportion of about 50 vol .-% in the Feed gas is present and the associated combustion gases through reducing combustion a fuel with a low hydrogen content can be obtained, for the most part (90-95% by volume) Contain carbon dioxide, and preferably for the pyrolysis of chlorine-containing metal compounds Magnesium chloride dihydrate are used, characterized in that the two combustion gases for pyrolysis by burning one at the same time as pyrolysis reaction-related amount of coke generated in the reaction furnace and the additional amount of carbon dioxide required fed to the synthesis gas stream after the pyrolysis reaction