DE2053337A1 - Vinyl chloride - catalytic prodn from acetylene and hydrogen chloride while saving hot steam and cooling water - Google Patents

Abstract

Both circulation evaporators are connected to cycle of heat transfer agent which cools catalyst-packed reaction furnace for prodn. of vinyl chloride from C2H2 and HCl. Heat energy abstracted is used to heat distn. columns and only the residual excess energy of heat transfer agent is extracted in a cooler fed with cooling water, in process where crude vinyl chloride leaving reaction furnace is compressed, freed from inert gases and C2H2 in a first distn. column heated by circulation evaporator and sump prod. is transferred to a second distn. column heated by a circulation evaporator where pure vinyl chloride is separated by distn. from higher chlorinated 2C hydrocarbon-contg. sump.

Description

Process for the catalytic production of vinyl chloride process for the production of vinyl chloride from acetylene and hydrogen chloride using an aqueous hydrochloric acid solution of quenched-II chloride and / or copper-1 chloride as a catalyst are known. The German patent specification 1 106 311 also writes Also the addition of phosphine or phosphine to the catalyst solution. The processing of the crude vinyl chloride obtained in this way is carried out in the German Auslegeschrift 1 254 145 described in detail using a flow chart, welcties as a starting point and for a better understanding of the following to be described Invention as Figure i is added unchanged. According to Figure 1, the crude vinyl chloride, that with more highly chlorinated C2 hydrocarbons and unreacted acetylene is contaminated, compressed and introduced into a first distillation column (4), which is heated by a circulation evaporator (5). The separation takes place in (4) into one made of inert gases, non-condensed vinyl chloride and unreacted acetylene consists of a top product and a predominantly vinyl chloride and higher chlorinated product C2 hydrocarbons existing bottom product, which in a second, with a Circulation evaporator (22) heated distillation column (21) is withdrawn, in which pure vinyl chloride is distilled off overhead from this bottom product. I) ie te The temperature of the circulation evaporator (5) is, for example, 40 ° C., that of the circulation evaporator (22) e.g. 42 to 45 ° C. A further explanation of Figure 1 is within the framework present invention unnecessary; if necessary, use the German Auslegeschrift 1 254 143 approach.

The well-known conversion of acetylene and hydrogen chloride to vinyl chloride takes place under heat emission. Therefore, the reaction furnace must be filled with the catalyst solution be continuously cooled. It is now quite uneconomical, on the one hand that of a circulated heat transfer medium such as glycol or commercially available located so-called.

"Heat transfer oils", absorbed thermal energy by releasing it Destroy the cooling water, but on the other hand the two circulation evaporators (5) and (22) in Figure 1 for the degassing and purifying distillation of vinyl chloride with larger To feed quantities of heating steam.

The invention is now based on the object of a method for production Creation of vinyl chloride from acetylene and hydrogen chloride, in which the heat of reaction is used for degassing and distillation of the crude vinyl chloride.

This is achieved according to the invention in that the circulated Heat transfer medium that absorbs the heat of reaction in the reaction furnace, directly is passed into the circulation evaporator, where it is used for heating the columns required amount of heat is withdrawn.

The advantage of the invention is that on the one hand heating steam for the two circulation evaporators and on the other hand a corresponding amount of water can be saved for cooling the heat transfer medium.

The method of the invention will now be explained in more detail with reference to FIG. 2: The reaction furnace (1) contains the catalyst solution. The supply lines for acetylene and hydrogen chloride as well as the derivative for raw vinyl chloride were made for simplicity omitted because they are not in this context interested. The cross section of the reaction furnace (1) shows the Konstaktrohre (6), which from circulated heat transfer medium that flows around the furnace (1) leaves through the line (7). On line (7) there is an expansion vessel (15) for the heat transfer medium connected. The hot heat transfer medium is sucked in by the pump (2) and pushed into line (8), from where it corresponds through Branch lines into the circulation evaporators (5) and arranged parallel to one another (4) and cooler (5) can flow. There is a circulation evaporator (3) for heating the first distillation column (degassing column) (10) and circulation evaporator (4) for heating the second distillation column (11) determined. Time line (12) the entry of the compressed crude vinyl chloride into the distillation column (10). The amount of heat transfer medium flowing into the circulation evaporator (5) is in Regulated as a function of this column inlet (12). The more crude vinyl chloride in the unit of time flows into the column (10) through line (12), the more Heating energy is required for its degassing and the more hot heat transfer medium must consequently in the unit of time through the actuator (14) in the circulation evaporator (5) pour in.

In a similar way, the flow into the circulation evaporator (4) Amount of heat transfer medium as a function of the liquid level in the column (11) regulated. The more liquid there is in the pale of the column (11), the more heating energy is required for the distillation and the more hot Heat transfer medium must consequently in the unit of time by the actuator (16) flow into the circulation evaporator (4).

Another part of the hot available in line (8) Heat transfer medium, which is not used for heating the columns (10) and (11) is needed can through the cooler fed with cooling water (3) stream. The parallel flows of the heat transfer medium, which cooled the circulation evaporator (5) and (4) and leave the cooler (5) again, enter line (9), which opens into the cooling system (6) of the reaction furnace (1). The furnace inlet temperature is regulated with the help of the cooler (5). If the measured before the reaction furnace (1) Heat transfer medium temperature considered too high or too low to enter is felt in the reaction furnace (1), the actuator (18) becomes stronger as the case may be opened or sculossen, so in the unit of time more or less heat transfer medium can be cooled.

When the process according to the invention is started, the "cooler" (5) Incidentally briefly pressurized with heating steam to the heat transfer medium heat up so that the reaction in the reaction furnace (1) starts. Then will immediately cooled, as vinyl chloride is formed in an exothermic reaction.

Finally, some of the available in line (8) hot heat transfer medium via a bypass (15) directly in line (9) stream. The actuator (17) located in the handle (15) is used to regulate the amount of heat transfer medium in the circle collecting line (7, 8, 9). This is the per unit of time in the cycle constant amount of the heat transfer medium pumped through the reaction furnace (1) held.

If one compares the flow diagram described in FIG. 2 with the flow diagram (Figure 1) of the German Auslegeschrift 1 254 145, so the local line correspond (12) the local line (5), the local circulation evaporator (5) and (4) the local one Circulation evaporators (5) or (22) and the local columns (10) and (11) the local ones Columns (4) and (21).

The invention relates only to a method of catalytic production of vinyl chloride from acetylene and hydrogen chloride in a catalyst-filled one Reaction furnace using a circulating liquid heat transfer medium is cooled, whereby the crude vinyl chloride flowing out of the reaction furnace is compressed, in a first distillation column of Inert gases and acetylene freed, the bottom product in a second, with a circulation evaporator transferred heated distillation column and there pure vinyl chloride from a more highly chlorinated C2 hydrocarbons containing sump distilled off, which thereby gekennzeichtiet is that the two circulation evaporators in the circuit of the heat transfer medium switches on and thus the heat transfer during cooling of the reaction furnace medium dissipated thermal energy used to heat the distillation columns There is only the excess heat energy of the heat transfer medium that remains as a result withdrawn from this in a cooler fed with cooling water.

Furthermore, the method of the invention can optionally additionally characterized in that a) The amount of per unit of time through the circulation evaporator the first distillation column flowing hot heat transfer medium in dependence Full of the amount flowing into the first distillation column per unit of time compressed raw vinyl chloride is regulated; the amount of per unit of time hot heat transfer medium flowing through the circulation evaporator of the second distillation column depending on the starid height of the second Distillation column sump to be distilled is regulated; c) the amount of per unit of time thereby the hot heat transfer medium flowing with cooling water fed to the radiator depending on the furnace inlet temperature of the heat transfer medium will; d) the two circulation evaporators and the Kilhier in parallel to each other are arranged in the circulation system of the heat transfer medium; e) the geiteinlleit Amount of the heat transfer medium pumped in the circuit through the reduction furnace is kept constant.

Example There is a system with two contact furnaces in which a maximum of 2 x 7000 kg / h vinyl chloride are produced köuneii.

Because of the variable activity of the catalyst, the ovens not with constant, but must be used during the start-up and run-down periods can be operated with reduced power. If you see a phase shift like this before that the contact change of the cincn ofeiis with the maximum power of the other together, continuous operation can be achieved with one average output of 7000 (kg / h) vinyl chloride.

The heat of reaction (24.6 keal per mole of vinyl chloride) is for the Plant 2.8 # 106 (keal / h). The heat requirement of the first distillation column (10) is provided that 20% of the bottom product is evaporated 0.1 # 106 (keat / h). For the heat requirement of the 2nd distillation column (11) results assuming the reflux ratio is 2.0, 1.5 # 106 (keal / h). At the cooling water in the cooler (5) is therefore the difference heat quantity 1.2 # 106 (keal / h) to dissipate. The amount of steam saved (5 atmospheres) is for both distillation columns (10) and (11) 5 100 kg / h. The same amount of heat (1.6 # 106 keal / h) corresponding The amount of cooling water saved is 320 m5 / h when heated by 5 ° C.

Claims (6)

Patent claims: 1) Process for the catalytic production of vinyl chloride from acetylene and hydrogen chloride in a catalyst-filled reaction furnace which is charged with a circulated, liquid heat transfer medium is cooled, wherein the crude vinyl chloride flowing out of the reaction furnace is compressed, in a first, with a circulation evaporator heated distillation column of inert gases and Freed acetylene, the bottom product in a second, heated with a circulation evaporator Transferred to the distillation column and there pure vinyl chloride from a higher chlorinated one C2 hydrocarbons containing bottoms distilled off, characterized in that that the two circulation evaporators in the circuit of the heat transfer medium switches on and thus the one in the cooling of the reaction furnace to the heat transfer medium dissipated thermal energy used to heat the distillation columns and only the remaining excess heat energy of the heat transfer medium this is removed again in a cooler fed with cooling water. 2) Method according to claim 1, characterized in that the amount that flowing through the circulation evaporator of the first distillation column per unit of time hot heat transfer medium depending on the amount of per unit of time compressed crude vinyl chloride flowing into the first distillation column is regulated. 3) Method according to claim 1 or 2, characterized in that the Amount of per unit of time through the circulation evaporator of the second distillation column flowing hot heat transfer medium as a function of the Level of the sump to be distilled out in the second distillation column is regulated will. 4) Method according to one of claims 1 to 3, characterized in that that the amount of per unit of time flowing through the cooler fed with cooling water hot heat transfer medium depending on the furnace inlet temperature of the heat transfer medium is regulated. 5) Method according to one of claims 1 to 4, characterized in that that the two circulation evaporators and the cooler are connected in parallel to each other Circulatory system of the heat transfer medium are arranged. 6) Method according to one of claims 1 to 5, characterized in that that the amount of heat transfer pumped per unit of time in the circuit through the reaction furnace is kept constant by means of