The method of producing dichloroethane

 

(57) Abstract:

The invention relates to a method for producing dichloroethane, which finds use as a solvent and intermediate for obtaining vinyl chloride. The method of producing dichloroethane by chlorination of ethylene in the liquid medium of the reaction products in multiple reaction zones under the parallel reagents with recycling of the reaction mass from the upper reaction zone at the bottom due to the natural circulation of the reaction mass, which consists in the fact that the selection of the circulating reaction mass is carried out several upper reaction zones with the input of the circulating reaction mixture in at least two reaction zones. The safe way to exercise and is characterized by a high intensity. 2 Il.

The invention relates to a method for producing dichloroethane, which finds use as a solvent and intermediate for obtaining vinyl chloride.

To obtain dichloroethane in the manufacturing method of a gaseous chlorination of ethylene with gaseous chlorine in the liquid reaction products, consisting mainly of dichloroethane. The process is carried out at the boiling temperature of dichlorethane allotment of zavisimosti from the pressure and amount of inert gases in chlorine and ethylene (patent 2929852, 260-660, 1960).

The closest analogue of the present invention is applicable to the production of dichloroethane. The chlorination process is carried out in the environment of the reaction products in the presence of ferric chloride, which is formed due to corrosion of equipment or injected in the form of a solution in dichloroethane from the cube column as a product of corrosion of pipelines and devices, in multiple reaction zones under the parallel reagents with recycling of the reaction mass from the top of the reaction zone at the bottom due to the natural circulation of the reaction mass. The reaction unit is a column filled with liquid and reaction by-products are separated in height by 7 reaction zones through 6 partitioning / tube sheet plates with the living section 36%. A reactor equipped with an external circulation pipe, which connects the upper and lower reaction zones (Fig. 1).

Natural circulation of the reaction mass from the upper zone at the bottom is due to the difference in specific gravities gas-filled reaction mass in the column and free gas from the reaction mass in the circulation pipe (Technologist. the regulations are made. dichloroethane, , Sterlitamak, 1990).

The process is performed at a pressure above reacto the ONU and the conclusion of the reaction product in the form of vapor together with inert gases and unreacted ethylene and chlorine from the steam space at the top of the reaction zone (flow 3). In the upper reaction zone is maintained at a constant level of the liquid reaction mass by entering part of the condensed vapors dichloroethane in the lower reaction zone (stream 4) because of thermal balance of the amount of exhaust from the top of dichloroethane vapor significantly exceeds the amount synthesized in the reactor dichloroethane.

The disadvantage of this method of producing dichloroethane is a risk of combustion and explosion of the gas mixture of chlorine and ethylene at the termination of circulation in case of lowering of the liquid level in the upper zone below the level selection circulating reaction mass. Cessation of circulation leads to the formation of gas cushions under partitioning plates. The formation of gas cushions" - free zones from the liquid phase, is due to the fact that the circulating flow 5 by one to two orders of magnitude larger flow of condensate 4, and at the termination of circulation mechanical entrainment of fluid from the lower zone to the upper slightly exceeds the value of the thread 4. Under partitioning plate is formed a zone free from liquid such height at which establishes the equilibrium: the entrainment of the liquid becomes equal to the parish.

The formation of zones free from liquid to avoid when large volumes of gas cushions".

Under the current method of producing dichloroethane to ensure conditions of safety, taking into account the possibility of reducing the level due to the failure of the regulatory system-level or system failure flow 4 the process is conducted at a high altitude layer of liquid above the level of the selection circulating reaction mass and large living sections of the partitioning plates. Large living section of the plates in the range of 10 - 40% at low gas velocities through the holes in the plates provides the "failure" of liquid through the plate from the overlying zone in the underlying. Thus the flow of fluid from the upper zone to the underlying ("failure") compensates for mechanical ablation with the underlying zone in overlying, height and volume of the gas cushion decreases and reduces the danger of explosion. Work at low gas velocities through the holes in the plates, due to the need to have a large living section of the plates, reduce the overall speed of the process, as the speed of the process of synthesis of dichloroethane is determined by the rate of mass transfer.

The task of the invention is the provision of safe conditions for obtaining dichloroethane by chlorination of ethylene in the liquid reaction products with simultaneous intensification proteca reaction products in multiple reaction zones under the parallel reagents with recycling of the reaction mass from the top of the reaction zone at the bottom due to the natural circulation of the reaction mass in the selection of the circulating reaction mass from multiple upper areas with the input of the circulating reaction mixture in at least two reaction zones.

Distinctive features of the proposed method is the selection of the circulating reaction mass from multiple upper areas with the input of the circulating reaction mixture in at least two reaction zones.

The selection of the circulating reaction mass from multiple upper areas with the input of the circulating reaction mixture in at least two reaction zones, preferably in the middle and the bottom, allows you to preserve the natural circulation of the reaction mass during the fall of the liquid level in the upper circulating zone below the level selection circulating the reaction mixture from this reaction zone. The conservation of circulation ensures the safety of the process allows to process at higher speeds through the holes in the plates using a plate with a small living section that intensifies the process of chlorination by increasing the mass transfer coefficient. The increase of the coefficient of mass transfer due to increased circulating flow in the upper reaction zone due to the formation of at least two circulation paths.

In Fig. 1 shows a flow scheme of a known method of producing dichloroethane. The chlorination is carried out in multiple reaction to sasono. The reaction products in the form of vapor and unreacted gases are removed from the steam space of the upper zone (flow 3). Circulation of the reaction mass is carried out at the selection of the circulating flow from the upper reaction zone with putting it in the bottom of the reaction zone (flow 5).

In Fig. 2 depicts a flow chart of the proposed method of obtaining dichloroethane. The chlorination is carried out in multiple reaction zones, in this case 9, when the input ethylene (stream 1), chlorine (stream 2) and condensate dichloroethane (stream 4) in the lower zone. The reaction products in the form of vapor and unreacted gases are removed from the steam space of the upper zone (flow 3). Circulation of the reaction mass is carried out at the selection of the circulating flow both from the upper zone (stream 5) and multiple downstream areas (stream 6) from the input of the circulating flow in the lower zone (stream 7) and in one of the secondary zones (stream 8). Value stream 7 may be both more and less flow 5. When this is implemented at least two circulation circuit: General circulation loop, covering all the reaction zone, and local circulation loop, spanning several upper reaction zones.

Example 1. In industrial R is Academy plates with a vivid cross-section of 6% at the top and 16% in the lower part, continuously served in the lower reaction zone of chlorine (the chlorine concentration of 80%) in the number of 2120 nm/h and ethylene (ethylene concentration of 99.9%) in the number of 1825 nm/h of the Reaction mass circulate with a selection of 4 upper reaction zone and with input 1 and 6 of the reaction zone, counting from the bottom, as shown in Fig. 2.

The chlorination process is carried out at the boiling temperature of the reaction mass when the pressure at the top of the reactor to 0.11 MPa. The reaction products, mainly dichloroethane, in the form of vapor and unreacted gases away from the steam space of the upper zone, is cooled in the condenser, the condensate part return in the lower zone to maintain a constant liquid level in the reactor, the remaining condensate in the amount of 7500 kg/h supplied to the collector of finished product, the conversion of chlorine to 100% conversion of the ethylene - 93%, i.e., leakage of ethylene is 7% from the filed.

Example 2 (prototype). In the industrial reactor obtain dichloroethane diameter 3200 mm and a height of the fluid layer 9000 mm, divided into 9 zones / tube sheet plates with the living section 36%, continuously served in the lower reaction zone of chlorine (the chlorine concentration 80,5%) in the number 2108 nm/h and ethylene (ethylene concentration of 99.9%) in the number 2020 nm/H. the Reaction massig. 1.

The chlorination process is carried out at the boiling temperature of the reaction mass when the pressure at the top of the reactor to 0.11 MPa. The reaction products, mainly dichloroethane, in the form of vapor and unreacted gases away from the steam space of the upper zone, is cooled in the condenser, the condensate part is directed to a lower zone to maintain a constant liquid level in the reactor, the remaining condensate in the amount of 7500 kg/h supplied to the collector of the finished product. The conversion of chlorine to 100% conversion of the ethylene - 84%, i.e., leakage of ethylene is 16% of the filed.

Thus, obtaining dichloroethane proposed method allows to reduce the leakage of chlorine more than two times, while ensuring a more secure chlorination process.

The method of producing dichloroethane by chlorination of ethylene in the liquid medium of the reaction products in the presence of ferric chloride at the boiling temperature of the reaction mass in the several reaction zones with parallel reagents with recycling of the reaction mass from the upper reaction zone at the bottom of the reaction zone due to the natural circulation of the reaction mass, wherein the selection of the circulating reaction mass exercise is nnye zone.

 

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