Device and method for refining byproduct 1, 2-dichloropropane of 3-chloropropene device by combining rectification, chlorination and adsorption

Abstract

The invention discloses a refining device and a refining method for a byproduct 1, 2-dichloropropane of a 3-chloropropene device. According to the device, a light component removal tower, a chlorination reaction kettle, a heavy component removal tower and an adsorption tower are combined, so that a dichloropropene compound which is difficult to separate from 1, 2-dichloropropane is reacted with chlorine, and a saturated chlorinated compound heavy component which is easy to separate from the 1, 2-dichloropropane is formed, so that the 1, 2-dichloropropane is purified, and the byproduct 1, 2-dichloropropane of a 3-chloropropene device is obtained. The purity of 1, 2-dichloropropane is greater than or equal to 99.9%, and dichloropropene 1t is remained; and the economic value of the product is improved, the extractive distillation technology has the effects of saving energy and reducing consumption, and the method has a wide industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of purification of chemical by-products, and specifically relates to a device and method for refining 1,2-dichloropropane produced as a by-product of a 3-chloropropylene device. In particular, the device utilizes a combination of distillation, chlorination and adsorption technology to ensure that the purity of the 1,2-dichloropropane produced as a by-product of the 3-chloropropylene device reaches ≥99.9%, and the residual dichloropropylene is less than 100 ppm. Background Art

[0002] 1,2-Dichloropropane is an excellent organic solvent and chemical intermediate. It can be used to prepare paints, inks, diluents and PVC adhesives. It can replace xylene and other benzenes to make benzene-free banana water, thinner, polyurethane diluents, etc. It is also the main raw material for pesticide emulsifiers, lubricants, flame retardants, plasticizers, oilfield demulsifiers, detergents, non-ionic surfactants, etc. At the same time, dichloropropane is also an important raw material for fine chemical products such as cosmetics and medicines. It can also be used as a raw material for the production of tetrachloropropene in industry. However, the use of 1,2-dichloropropane as a raw material for the production of tetrachloropropene requires that the dichloropropene content must be below 100ppm.

[0003] Industrial devices for preparing 3-chloropropene by high temperature method often produce a large amount of by-product DD mixture (mixture of dichloropropane and dichloropropene), whose main components are 1,2-dichloropropane, cis-1,3-dichloropropene, trans-1,3-dichloropropene, 2,3-dichloropropene and 3,3-dichloropropene, etc. DD mixture After separating 1,3-dichloropropene from DD mixture, it becomes crude 1,2-dichloropropane, whose main components are 1,2-dichloropropane (75-85%, by weight percentage, the same below), 1-chloropropane (1-3%), 1-chloropropene (2-4%), 2-chloropropene (1-3%), 1,5-hexadiene (2-4%), cis-1,3-dichloropropene (4-6%), 2,3-dichloropropene (2-8%), 3,3-dichloropropene (4-6%), etc. Practice has shown that due to the small relative volatility of 3,3-dichloropropene, 2,3-dichloropropene and 1,2-dichloropropane, it is difficult and energy-intensive to separate them using ordinary distillation.

[0004] In summary, how to achieve high-precision purification of 1,2-dichloropropane, a byproduct of 3-chloropropene, through a simple and low-cost process is a severe challenge. The present invention uses a combination of distillation, chlorination and adsorption technology to obtain a high-purity product with a dichloropropene content of <100ppm and 1,2-dichloropropane ≥99.9%, saving energy consumption and improving the application value of the product. Summary of the invention

[0005] In view of this, the present invention proposes a new separation idea that can effectively make the by-product 1,2-dichloropropane of the 3-chloropropene device reach high purity. The method has good separation effect, and the final 1,2-dichloropropane purity is ≥99.9%, and the residual dichloropropene content is <100ppm.

[0006] One of the purposes of the present invention is to provide a purification device for 1,2-dichloropropane produced as a by-product of a 3-chloropropene device.

[0007] The second object of the present invention is to provide a method for refining 1,2-dichloropropane which is a by-product of a 3-chloropropylene unit.

[0008] According to one aspect of the present invention, the present invention provides a refining device for 1,2-dichloropropane produced as a by-product of a 3-chloropropylene device, comprising a light removal tower, a chlorination reactor, a heavy removal tower and an adsorption tower;

[0009] The de-lightening tower is provided with a gas outlet at the top for discharging gaseous substances, a feed inlet at the middle of the tower body for receiving raw materials, and a liquid outlet at the bottom of the tower for discharging liquid substances;

[0010] The chlorination reaction kettle is located downstream of the light-removal tower, and a discharge port is provided at the top of the chlorination reaction kettle for discharging the chlorinated product. A feed port and a gas inlet are provided at the bottom of the chlorination reaction kettle, which are connected to the liquid outlet at the bottom of the light-removal tower through a pipeline for receiving materials from the light-removal tower, and the gas inlet is used to introduce chlorine into the chlorination reaction kettle;

[0011] The deweighting tower is located downstream of the chlorination reactor, a feed port is provided in the middle of the deweighting tower, which is connected to the discharge port of the chlorination reactor through a pipeline, and is used to receive materials from the chlorination reactor, a discharge port is provided at the top of the deweighting tower, and is used to discharge purified 1,2-dichloropropane, and a heavy component residue discharge port is provided at the bottom of the deweighting tower, and is used to discharge the heavy component residue;

[0012] The adsorption tower is located downstream of the deweighting tower. The top of the adsorption tower is provided with a feed port, which is connected to the discharge port of the deweighting tower through a pipeline for receiving materials from the deweighting tower. The bottom of the adsorption tower is provided with a discharge port for discharging the purified 1,2-dichloropropane final product after adsorption treatment.

[0013] Preferably, the light-removal tower is a packed tower, in which a packing support, a liquid distributor, a redistributor and a demister are arranged.

[0014] Preferably, the chlorination reaction kettle is a stirred tank reactor.

[0015] Preferably, the deweighting tower is a packed tower, in which a packing support, a liquid distributor, a redistributor and a demister are arranged.

[0016] Preferably, the adsorption tower is a molecular sieve packing tower, in which a packing support and a liquid distributor are arranged.

[0017] Preferably, the gas outlet at the top of the light-removal tower is connected to a condenser for condensing the discharged gaseous material into liquid. More preferably, the condenser is connected to a reflux tank for temporarily storing the condensed liquid material and refluxes a part of it to the light-removal tower to maintain the material balance in the tower, and the other part is discharged from the system through a pipeline.

[0018] Preferably, the liquid outlet at the bottom of the light-removal tower is connected to a reboiler for vaporizing the discharged liquid substance. The liquid substance discharged through the liquid outlet is partially vaporized after passing through the reboiler and refluxed to the light-removal tower to maintain the material balance in the tower, and the rest is transported to the chlorination reactor through a pipeline.

[0019] Preferably, the chlorination reaction kettle is provided with a heat exchange jacket for introducing condensed water to control the temperature of the chlorination reaction kettle.

[0020] Preferably, the chlorination reaction kettle is provided with a stirrer for maintaining the uniformity of dispersion of materials in the chlorination reaction kettle.

[0021] Preferably, the chlorination reaction kettle is provided with a chlorine distributor to ensure uniform reaction.

[0022] Preferably, the chlorination reaction kettle is provided with a Venturi jet pump for mixing unreacted chlorine with feed chlorine to achieve complete utilization of chlorine.

[0023] Preferably, the discharge port at the top of the de-weighting tower is connected to a condenser for condensing the purified 1,2-dichloropropane. More preferably, the condenser is connected to a reflux tank for temporarily storing the condensed purified 1,2-dichloropropane, and a portion of it is refluxed to the de-weighting tower to maintain the material balance in the tower, and the rest is transported to the adsorption tower through a pipeline.

[0024] Preferably, the heavy component residue discharge port at the bottom of the de-weighting tower is connected to a reboiler for gasifying the discharged material, and a portion of the material further gasified by the reboiler flows back to the de-weighting tower to maintain the material balance in the tower, and the rest is discharged from the system through a pipeline.

[0025] Preferably, there is at least one adsorption tower, more preferably at least two; when there are two or more adsorption towers, the adsorption towers are operated alternately to ensure continuous operation of the entire device.

[0026] Preferably, valves and pumps may be provided on each pipeline of the refining device for the by-product 1,2-dichloropropane of the 3-chloropropene device to control the material flow rate and flow rate.

[0027] According to another aspect of the present invention, the present invention provides a method for refining 1,2-dichloropropane produced as a by-product of a 3-chloropropylene unit, the method comprising:

[0028] 1) The crude 1,2-dichloropropane by-product of the 3-chloropropylene unit is transported into the light-removal tower, and the light components in the crude product are removed by reflux treatment at a certain temperature, and the light components are discharged through the gas outlet at the top of the light-removal tower;

[0029] 2) the material after being treated in the light-removal tower enters the chlorination reaction kettle, wherein the dichloropropylene compounds that are difficult to separate from 1,2-dichloropropane react with chlorine at a certain temperature and pressure to form a saturated chlorinated compound heavy component that is easy to separate from 1,2-dichloropropane;

[0030] 3) the material containing saturated chlorinated compounds after the reaction in the chlorination reactor enters the de-weighting tower, and is refluxed at a certain temperature to remove the heavy components of saturated chlorinated compounds in the material, and the heavy components are discharged through the heavy component residue discharge port at the bottom of the de-weighting tower, and the purified 1,2-dichloropropane is discharged from the discharge port at the top of the de-weighting tower and enters the adsorption tower;

[0031] 4) In the adsorption tower, unreacted dichloropropylene compounds are further removed by adsorption of the adsorbent.

[0032] Preferably, the crude 1,2-dichloropropane contains, by weight percentage, 75-85% of 1,2-dichloropropane, 1-3% of 1-chloropropane, 2-4% of 1-chloropropene, 1-3% of 2-chloropropene, 2-4% of 1,5-hexadiene, 4-6% of cis-1,3-dichloropropene, 2-8% of 2,3-dichloropropene, 4-6% of 3,3-dichloropropene, etc.

[0033] Preferably, the light component includes one or more of 1-chloropropane, 1-chloropropylene, 2-chloropropylene, 1,5-hexadiene and the like.

[0034] Preferably, the lightness removal tower in step 1) has 50 to 70 theoretical plates, the feed position is located at the 20th to 40th theoretical plates, the operating conditions are normal pressure, the operating reflux ratio is 1 to 3, and the tower top temperature is 30 to 37.4°C.

[0035] Preferably, the dichloropropylene compound in step 2) is selected from one or more of cis-1,3-dichloropropylene, 2,3-dichloropropylene and 3,3-dichloropropylene.

[0036] Preferably, the saturated chlorinated compound in step 2) is selected from one or more of 1,1,2,3-tetrachloropropane and 1,2,2,3-tetrachloropropane.

[0037] Preferably, the deweighting tower in step 3) has 50 to 80 theoretical plates, the feed position is at the 20th to 40th theoretical plate, the operating conditions are normal pressure operation, the reflux ratio is 0.4 to 2, and the tower top temperature is 85 to 96°C.

[0038] Preferably, the lightness removal tower in step 1) is a packed tower, and the packing is a small metal Bauer ring packing, a metal corrugated packing, a metal wire mesh corrugated packing, preferably a metal wire mesh corrugated packing.

[0039] Preferably, the deweighting tower is a packed tower, and the packing is a small metal Bauer ring packing, a metal corrugated packing, or a metal wire mesh corrugated packing, preferably a metal wire mesh corrugated packing.

[0040] Preferably, the temperature in the adsorption tower is 40-50° C., the pressure in the tower is 10-30 kPaG, and the adsorbent is filled therein, and the adsorbent is 3A, 4A, 5A or 13X molecular sieve.

[0041] Preferably, the purity of the 1,2-dichloropropane product finally subjected to adsorption treatment in the adsorption tower is ≥99.9%, and the residual dichloropropylene is <100 ppm.

[0042] Beneficial Effects

[0043] The device according to the present invention utilizes a combination of a light removal tower, a chlorination reaction kettle, a heavy removal tower and an adsorption tower to react dichloropropene compounds that are difficult to separate from 1,2-dichloropropane with chlorine, thereby forming a saturated chlorinated compound heavy component that is easy to separate from 1,2-dichloropropane, thereby purifying 1,2-dichloropropane, making the purity of 1,2-dichloropropane produced as a byproduct of a 3-chloropropene device ≥99.9%, and the residual dichloropropene <100ppm, thereby improving the economic value of the product, and the extraction and distillation technology plays a role in energy saving and consumption reduction, and has a wide prospect for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 It is a schematic diagram of the structure of the refining device according to the present invention.

[0046] Among them, T101 is a light removal tower, T102 is a heavy removal tower, T03 and T104 are adsorption towers, R101 is a chlorination reactor; E101 and E102 are top condensers of each tower, E103 is a heat exchanger, E111 and E112 are bottom reboilers, P101, P102, P103, P104 and P105 are power pumps for each stream of materials, and S101 and S102 are reflux tanks. DETAILED DESCRIPTION

[0047] Hereinafter, the present invention will be described in detail. Before describing, it should be understood that the terms used in this specification and the appended claims should not be interpreted as being limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention on the basis of the principle that the inventor is allowed to appropriately define the terms for the best interpretation. Therefore, the descriptions presented here are only preferred examples for illustrative purposes and are not intended to limit the scope of the present invention, so that it should be understood that other equivalents or improvements can be obtained therefrom without departing from the spirit and scope of the present invention.

[0048] In this document, the terms "include", "including", "have", "contain" or any other similar terms are open conjunctions, which are intended to cover non-exclusive inclusions. For example, a composition or product containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or product. In addition, unless otherwise explicitly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and A and B are both true (or exist). In addition, in this document, the interpretation of the terms "include", "including", "have", and "contain" should be considered to have been specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of".

[0049] In this article, all features or conditions defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible secondary ranges and individual values ​​within the range, especially integer values. For example, the range description of "1 to 8" should be deemed to have specifically disclosed all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., especially secondary ranges defined by all integer values, and should be deemed to have specifically disclosed individual values ​​such as 1, 2, 3, 4, 5, 6, 7, 8, etc. within the range. Unless otherwise specified, the above interpretation method applies to all contents of the entire present invention, regardless of whether the range is broad or not.

[0050] If the quantity or other numerical value or parameter is expressed as a range, a preferred range or a series of upper and lower limits, it should be understood that all ranges consisting of any upper limit or preferred value of the range and the lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0051] In this document, under the premise of achieving the purpose of the invention, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0052] In order to clarify the present invention, parts irrelevant to the description are omitted in the drawings, and the same or similar components are denoted by the same reference numerals throughout the specification.

[0053] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and thus the present invention is not necessarily limited to those shown in the drawings.

[0054] Throughout the specification, when it is mentioned that a certain element is “connected” to another element, it includes not only “direct connection” but also “indirect connection” between other components. In addition, when it is mentioned that a certain element “includes” a certain component, it means that the element may further include other components rather than excluding other components, unless explicitly described to the contrary.

[0055] The terms “first”, “second” and the like used herein are used to explain various constituent elements, and they are used merely for the purpose of distinguishing one constituent element from another constituent element.

[0056] Furthermore, the terms used herein are only used to explain exemplary embodiments and are not intended to limit the present invention. Singular expressions also include plural expressions thereof, unless otherwise clearly indicated in the context. Terms such as "comprising", "equipped with" or "having" used herein are used to specify the existence of practical characteristics, numbers, steps, constituent elements or combinations thereof, and should be understood as not excluding the possibility of adding or existing one or more other characteristics, numbers, steps, constituent elements or combinations thereof.

[0057] Also, if a layer or an element is referred to as being formed “on” or “over” a “layer” or “element,” this means that each layer or element is formed directly on the layer or element, or other layers or elements may be formed between layers, bodies, or substrates.

[0058] The following is combined with Figure 1 , a detailed description is given of the refining process of 1,2-dichloropropane produced as a by-product of the 3-chloropropene unit according to the present invention.

[0059] like Figure 1 As shown, the refining device for 1,2-dichloropropane produced as a by-product of a 3-chloropropylene unit according to the present invention includes a light removal tower T101, a chlorination reactor R101, a heavy removal tower T102 and adsorption towers T103 and T104.

[0060] The de-lightness tower T101 has a gas outlet at the top for discharging gaseous substances, a feed inlet at the middle of the tower body for receiving raw materials, and a liquid outlet at the bottom of the tower for discharging liquid substances;

[0061] The chlorination reactor R101 is located downstream of the light-removal tower T101. The top of the chlorination reactor R101 is provided with a discharge port for discharging the chlorinated product. The bottom of the chlorination reactor R101 is provided with a feed port and a gas inlet. The feed port is connected to the liquid outlet at the bottom of the light-removal tower T101 through a pipeline for receiving materials from the light-removal tower T101. The gas inlet is used to introduce chlorine into the chlorination reactor R101.

[0062] The deweighting tower T102 is located downstream of the chlorination reactor R101. A feed inlet is provided in the middle of the deweighting tower T102, which is connected to the discharge port of the chlorination reactor R101 through a pipeline, and is used to receive materials from the chlorination reactor R101. A discharge port is provided at the top of the deweighting tower T102, and is used to discharge purified 1,2-dichloropropane. A heavy component residue discharge port is provided at the bottom of the deweighting tower T102, and is used to discharge heavy component residue;

[0063] Two adsorption towers, namely T103 and T104, are arranged, and the two towers are operated alternately and are located downstream of the deweighting tower T102. The tops of the adsorption towers T103 and T104 are provided with feed ports, which are connected with the discharge port of the deweighting tower T102 through pipelines for receiving materials from the deweighting tower T102. The bottoms of the adsorption towers T103 and T104 are provided with discharge ports for discharging the purified 1,2-dichloropropane final product after adsorption treatment.

[0064] Preferably, the lightness removal tower T101 is a packed tower, in which a packing support, a liquid distributor, a redistributor and a demister are arranged.

[0065] Preferably, the chlorination reaction kettle R101 is a kettle-type stirred reactor.

[0066] Preferably, the deweighting tower T102 is a packed tower, in which a packing support, a liquid distributor, a redistributor and a demister are arranged.

[0067] Preferably, the adsorption towers T103 and T104 are molecular sieve packing towers, and packing supports and liquid distributors are arranged inside the towers.

[0068] Preferably, the gas outlet at the top of the light-removal tower T101 is connected to a condenser E101 for condensing the discharged gaseous substance into a liquid state. More preferably, the condenser E101 is connected to a reflux tank S101 for temporarily storing the condensed liquid substance and refluxes a part of it to the light-removal tower T101 to maintain the material balance in the tower, and the other part passes through a discharge system.

[0069] Preferably, the liquid outlet at the bottom of the light-removal tower T101 is connected to a reboiler E111 for vaporizing the discharged liquid substance. The liquid substance discharged through the liquid outlet is partially vaporized by the reboiler E111 and partially refluxed to the light-removal tower T101 to maintain the material balance in the tower, and the rest is transported to the chlorination reactor R101 through a pipeline.

[0070] Preferably, the chlorination reaction kettle R101 is provided with a heat exchange jacket for introducing condensed water to control the temperature of the chlorination reaction kettle R101.

[0071] Preferably, the chlorination reaction kettle R101 is provided with a stirrer for maintaining the uniformity of dispersion of materials in the chlorination reaction kettle R101.

[0072] Preferably, the chlorination reaction kettle R101 is provided with a chlorine distributor to ensure uniform reaction.

[0073] Preferably, the chlorination reactor R101 is provided with a Venturi jet pump for mixing unreacted chlorine with feed chlorine to achieve complete utilization of chlorine.

[0074] Preferably, the discharge port at the top of the deweighting tower T102 is connected to a condenser E102 for condensing and discharging the purified 1,2-dichloropropane. More preferably, the condenser E102 is connected to a reflux tank S102 for temporarily storing the condensed purified 1,2-dichloropropane and returning a portion of it to the deweighting tower T102 to maintain the material balance in the tower, and the rest is transported to the adsorption towers T103 and T104 through pipelines.

[0075] Preferably, the heavy component residue discharge port at the bottom of the de-weighting tower T102 is connected to a reboiler E112 for vaporizing the discharged liquid material. A portion of the material partially vaporized by the reboiler E112 is refluxed to the de-weighting tower T102 to maintain the reaction balance of the material in the tower, and the rest is discharged from the system through a pipeline.

[0076] The refining method for 1,2-dichloropropane produced as a byproduct of a 3-chloropropylene unit using the refining device according to the present invention comprises the following steps: the crude 1,2-dichloropropane produced as a byproduct of the 3-chloropropylene unit is first fed into a lightness removal tower T101, wherein the number of theoretical plates of the lightness removal tower T101 is 50 to 70, the feed position is located at the 20th to 40th plate, the operating condition is normal pressure, and the operating reflux ratio is 1 to 3. The tower top temperature is 30 to 37.4°C, the tower bottom temperature is 100 to 105°C, and the pressure is 25 to 35KpaG. After the gas phase at the top of the lightness removal tower T101 is condensed, a part of it refluxes and re-enters the lightness removal tower T101, and the other part of the material is discharged through pump P101. In a typical implementation scheme, the light components 1-chloropropane, trans-1-chloropropene, 2-chloropropene, 1,5-hexadiene, etc. are removed from the top of the lightness removal tower T101. At the same time, water is also basically removed in this step, which prevents the hydrochloric acid produced in the subsequent chlorination process from affecting the product and equipment. A part of the bottom material of the lightness removal tower T101 is refluxed through the reboiler E111, and the other part is extracted through pump P105 and sent to the chlorination reactor R101 after cooling in the heat exchanger E103.

[0077] In a typical implementation scheme, the materials of the chlorination reactor R101 are mainly 1,2-dichloropropane (DCP), 3,3-dichloropropylene, 2,3-dichloropropylene and cis-1,3-dichloropropylene. The material from the bottom of the T101 tower is extracted by pump P105 and heat exchanged to 30°C in the heat exchanger E103 before entering the chlorination reactor R101 at the bottom. At the same time, another feed at the bottom of the reactor is chlorine gas, which is fully reacted in the chlorination reactor R101 after temperature control and is sent to the deweighting tower T102 from the top outlet of the chlorination reactor R101. During the chlorination reaction, the total feed flow rate is 1175Kg / h, and the chlorine flow rate is 126Kg / h. The chlorination reactor R101 has a built-in chlorine distributor and agitator. Stirring is always maintained during the reaction to ensure timely heat dissipation inside the solution and avoid uneven reaction caused by excessive local temperature, thereby triggering a series of side reactions. The chlorination reaction is an exothermic reaction, and the chlorination reactor R101 is equipped with a condensed water circulation cooling system. Excess chlorine is mixed with the feed chlorine through a venturi jet pump to achieve full utilization of chlorine. The reaction temperature is 32°C and the reaction residence time is 2h. If the reaction time is too long, serious dichloropropane substitution side reactions will occur, resulting in material loss. In a typical implementation scheme, 3,3-dichloropropene and cis-1,3-dichloropropene undergo chlorination addition to generate 1,1,2,3-tetrachloropropane, and 2,3-dichloropropene undergoes addition to generate 1,2,2,3-tetrachloropropane.

[0078] The material at the top outlet of the chlorination reactor R101 enters the de-weighting tower T102. The filler in the de-weighting tower T102 is a metal wire mesh corrugated filler, the theoretical number of plates is 50 to 80, the feed position is located at the 20th to 40th plate, and the operating conditions are normal pressure operation reflux ratio 0.4 to 2. The top temperature is 85 to 96 ° C, the bottom temperature is 180 to 190 ° C, and the pressure is 25 to 35 KpaG. In a typical implementation scheme, after the top gas phase is condensed, a part of the reflux re-enters the de-weighting tower T102, and the other part of the material is extracted by pump P103 to obtain 1,2-dichloropropane with a purity of ≥99.5%. A part of the bottom material is refluxed through the reboiler E112, and the other part is a heavy component impurity, the main components of which are 1,1,2,3-tetrachloropropane and 1,2,2,3-tetrachloropropane. The 1,2-dichloropropane product at the top of the deweighting tower T102 is further passed through adsorption towers T103 and T104 to remove dichloropropylene impurities, thereby obtaining a dichloropropane product with a purity of ≥99.9%.

[0079] In a typical implementation scheme, the adsorption tower comprises two towers T103 and T104, one tower is used for adsorption, and the other tower is used for regeneration, and the two towers are used alternately in a cycle, wherein the adsorbent is 3A, 4A, 5A, 13X molecular sieve, the temperature in the tower is 40-50°C, the pressure in the tower is 10-30 kPaG, and the residual dichloropropylene content after adsorption is <100 ppm.

[0080] The following examples are only listed as examples of embodiments of the present invention and do not constitute any limitation to the present invention. It can be understood by those skilled in the art that modifications within the scope of the essence and concept of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0081] Example 1

[0082] The 3-chloropropene unit produces 1255 kg / h of crude 1,2-dichloropropane as a by-product, which is composed of 1,2-dichloropropane (80%, wt%, the same below), 1-chloropropane (1%), 1-chloropropene (2%), 2-chloropropene (1.5%), 1,5-hexadiene (2.1%), cis-1,3-dichloropropene (5%), 2,3-dichloropropene (3%), 3,3-dichloropropene (5%), and water (0.4%). It is first fed into the lightness removal tower T101. The packing of T101 is a corrugated metal mesh packing with 60 theoretical plates. The feed position is located at the 30th theoretical plate. The operating conditions are normal pressure, the operating reflux ratio is 2, the top temperature is 36°C, and the bottom temperature is 104°C. The gas phase at the top of the lightness removal tower T101 is condensed and first enters the reflux tank S101, and then a part of it refluxes, and the other part of the material is discharged through pump P101. Trace water, 1-chloropropane, 1-chloropropylene, 2-chloropropylene, and 1,5-hexadiene are removed from the top of the tower.

[0083] The bottom materials of the light removal tower T101 are DCP, 3,3-dichloropropylene, 2,3-dichloropropylene and cis-1,3-dichloropropylene. The bottom discharge of the light removal tower T101 is extracted by pump P105 and cooled to 30°C in the heat exchanger E103, and then sent to the bottom feed of the chlorination reactor R101. At the same time, another feed at the bottom of the chlorination reactor R101 is chlorine gas, which is fully reacted in the chlorination reactor R101 after temperature control, and then sent to the heavy removal tower T102 from the top outlet of the chlorination reactor R101. During the chlorination reaction, the total feed flow rate is 1175Kg / h, and the chlorine flow rate is 126Kg / h. The chlorination reactor R101 is equipped with a chlorine distributor and agitator. Stirring is always maintained during the reaction to ensure timely heat dissipation inside the solution and avoid uneven reaction caused by excessive local temperature, thereby triggering a series of side reactions. The chlorination reaction is an exothermic reaction, and the chlorination reactor R101 is equipped with a condensed water circulation cooling system. Excess chlorine is mixed with the feed chlorine through a venturi jet pump to achieve full utilization of chlorine. The reaction temperature is 32°C and the reaction residence time is 2h. If the reaction time is too long, serious dichloropropane substitution side reactions will occur, resulting in material loss. In a typical implementation scheme, 3,3-dichloropropene and cis-1,3-dichloropropene undergo chlorination addition to generate 1,1,2,3-tetrachloropropane, and 2,3-dichloropropene undergoes addition to generate 1,2,2,3-tetrachloropropane.

[0084] The material at the top outlet of the chlorination reactor R101 enters the deweighting tower T102, which is filled with metal wire mesh corrugated packing, with 60 theoretical plates, the feed position is the 30th theoretical plate, the operating conditions are normal pressure, and the operating reflux ratio is 0.5. The top temperature is 93°C and the bottom temperature is 185.7°C. The gas phase at the top of the tower is condensed and enters the reflux tank S102, and then part of it is refluxed, and the other part of the material is extracted through pump P103 to obtain 1,2-dichloropropane with a purity of ≥99.5%. The bottom of the tower is extracted as heavy component impurities, the main components of which are 1,1,2,3-tetrachloropropane and 1,2,2,3-tetrachloropropane.

[0085] The 1,2-dichloropropane product at the top of the deweighting tower T102 is further removed from the dichloropropylene impurities through the adsorption towers T103 and T104 to obtain a dichloropropylene product with a purity of ≥99.9%. The adsorbent is 5A molecular sieve, the temperature in the tower is 42.5°C, the pressure in the tower is 21kPaG, and the residual dichloropropylene content after adsorption is <100ppm.

[0086] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A refining device for 1,2-dichloropropane produced as a byproduct of a 3-chloropropylene unit, comprising a light removal tower, a chlorination reactor, a heavy removal tower and an adsorption tower; The de-lightening tower is provided with a gas outlet at the top for discharging gaseous substances, a feed inlet at the middle of the tower body for receiving raw materials, and a liquid outlet at the bottom of the tower for discharging liquid substances; The chlorination reaction kettle is located downstream of the light-removal tower, and a discharge port is provided at the top of the chlorination reaction kettle for discharging the chlorinated product. A feed port and a gas inlet are provided at the bottom of the chlorination reaction kettle, which are connected to the liquid outlet at the bottom of the light-removal tower through a pipeline for receiving materials from the light-removal tower, and the gas inlet is used to introduce chlorine into the chlorination reaction kettle; The deweighting tower is located downstream of the chlorination reactor, a feed port is provided in the middle of the deweighting tower, which is connected to the discharge port of the chlorination reactor through a pipeline, and is used to receive materials from the chlorination reactor, a discharge port is provided at the top of the deweighting tower, and is used to discharge purified 1,2-dichloropropane, and a heavy component residue discharge port is provided at the bottom of the deweighting tower, and is used to discharge the heavy component residue; The adsorption tower is located downstream of the deweighting tower. The top of the adsorption tower is provided with a feed port, which is connected to the discharge port of the deweighting tower through a pipeline for receiving materials from the deweighting tower. The bottom of the adsorption tower is provided with a discharge port for discharging the purified 1,2-dichloropropane final product after adsorption treatment.

2. The refining device according to claim 1, characterized in that: The light-removal tower is a packed tower, in which a packing support, a liquid distributor, a redistributor and a demister are arranged; Preferably, the chlorination reaction kettle is a kettle-type stirred reactor; Preferably, the deweighting tower is a packed tower, in which a packing support, a liquid distributor, a redistributor and a demister are arranged; Preferably, the adsorption tower is a molecular sieve packing tower, in which a packing support and a liquid distributor are arranged.

3. The refining device according to claim 1, characterized in that: The gas outlet at the top of the light-removal tower is connected to a condenser for condensing the discharged gaseous substances into liquid. More preferably, the condenser is connected to a reflux tank for temporarily storing the condensed liquid substances and refluxes part of the condensed liquid substances to the light-removal tower to maintain the material balance in the tower, and the other part passes through a discharge system. Preferably, the liquid outlet at the bottom of the light-removal tower is connected to a reboiler for gasifying the discharged liquid substance, and the liquid substance discharged through the liquid outlet is partially gasified and refluxed to the light-removal tower after passing through the reboiler to maintain the material balance in the tower, and the rest is transported to the chlorination reactor through a pipeline; Preferably, the chlorination reaction kettle is provided with a heat exchange jacket for introducing condensed water to control the temperature of the chlorination reaction kettle; Preferably, the chlorination reaction kettle is provided with a stirrer for maintaining the uniformity of dispersion of materials in the chlorination reaction kettle; Preferably, the chlorination reaction kettle is provided with a chlorine distributor to ensure uniform reaction; Preferably, the chlorination reaction kettle is provided with a Venturi jet pump for mixing the unreacted chlorine with the feed chlorine to achieve full utilization of the chlorine; Preferably, the discharge port at the top of the de-weighting tower is connected to a condenser for condensing the purified 1,2-dichloropropane. More preferably, the condenser is connected to a reflux tank for temporarily storing the condensed purified 1,2-dichloropropane, and a portion of it is refluxed to the de-weighting tower to maintain the material balance in the tower, and the rest is transported to the adsorption tower through a pipeline; Preferably, the heavy component residue discharge port at the bottom of the de-weighting tower is connected to a reboiler for gasifying the discharged material, and part of the material further gasified by the reboiler is refluxed to the de-weighting tower to maintain the material balance in the tower, and the rest is discharged from the system through a pipeline; Preferably, there is at least one adsorption tower, more preferably at least two; when there are two or more adsorption towers, the adsorption towers are operated alternately to ensure continuous operation of the entire device.

4. The refining device according to claim 1, characterized in that: Valves and pumps can be selectively arranged on each pipeline of the refining device for the by-product 1,2-dichloropropane of the 3-chloropropylene device to control the material flow rate and flow rate.

5. A method for refining 1,2-dichloropropane produced as a byproduct of a 3-chloropropylene unit, the method comprising: 1) The crude 1,2-dichloropropane by-product of the 3-chloropropylene unit is transported into the light-removal tower, and the light components in the crude product are removed by reflux treatment at a certain temperature, and the light components are discharged through the gas outlet at the top of the light-removal tower; 2) the material after being treated in the light-removal tower enters the chlorination reaction kettle, wherein the dichloropropylene compounds that are difficult to separate from 1,2-dichloropropane react with chlorine at a certain temperature and pressure to form a saturated chlorinated compound heavy component that is easy to separate from 1,2-dichloropropane; 3) the material containing saturated chlorinated compounds after the reaction in the chlorination reactor enters the de-weighting tower, and is refluxed at a certain temperature to remove the heavy components of saturated chlorinated compounds in the material, and the heavy components are discharged through the heavy component residue discharge port at the bottom of the de-weighting tower, and the purified 1,2-dichloropropane is discharged from the discharge port at the top of the de-weighting tower and enters the adsorption tower; 4) In the adsorption tower, unreacted dichloropropylene compounds are further removed by adsorption of the adsorbent.

6. The refining method according to claim 5, characterized in that: The crude 1,2-dichloropropane contains, by weight percentage, 75-85% of 1,2-dichloropropane, 1-3% of 1-chloropropane, 2-4% of 1-chloropropylene, 1-3% of 2-chloropropylene, 2-4% of 1,5-hexadiene, 4-6% of cis-1,3-dichloropropylene, 2-8% of 2,3-dichloropropylene, 4-6% of 3,3-dichloropropylene, etc.; Preferably, the light component includes one or more of 1-chloropropane, 1-chloropropylene, 2-chloropropylene, 1,5-hexadiene and the like.

7. The purification method according to claim 5, characterized in that: The number of theoretical plates of the light removal tower in step 1) is 50 to 70, the feed position is located at the 20th to 40th theoretical plates, the operating conditions are normal pressure, the operating reflux ratio is 1 to 3, and the tower top temperature is 30 to 37.4° C.; Preferably, the dichloropropylene compound in step 2) is selected from one or more of cis-1,3-dichloropropylene, 2,3-dichloropropylene and 3,3-dichloropropylene; Preferably, the saturated chlorinated compound in step 2) is selected from one or more of 1,1,2,3-tetrachloropropane and 1,2,2,3-tetrachloropropane; Preferably, the deweighting tower in step 3) has 50 to 80 theoretical plates, the feed position is at the 20th to 40th theoretical plate, the operating conditions are normal pressure operation, the reflux ratio is 0.4 to 2, and the tower top temperature is 85 to 96°C.

8. The purification method according to claim 5, characterized in that: The light-removal tower in step 1) is a packed tower, and the packing is a small metal Bauer ring packing, a metal corrugated packing, a metal wire mesh corrugated packing, preferably a metal wire mesh corrugated packing; Preferably, the deweighting tower is a packed tower, and the packing is a small metal Bauer ring packing, a metal corrugated packing, or a metal wire mesh corrugated packing, preferably a metal wire mesh corrugated packing.

9. The purification method according to claim 5, characterized in that: The temperature in the adsorption tower is 40-50° C., the pressure in the tower is 10-30 kPaG, and the adsorbent is filled therein, and the adsorbent is 3A, 4A, 5A or 13X molecular sieve.

10. The purification method according to claim 5, characterized in that: The purity of the final product 1,2-dichloropropane after adsorption treatment in the adsorption tower is ≥99.9%, and the residual dichloropropylene is <100ppm.

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