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

Abstract

The invention relates to a device and a method for refining 1, 2-dichloropropane as a byproduct of a 3-chloropropene device by combining rectification, polymerization and adsorption. 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, the light component removal tower, the polymerization reactor, the heavy component removal tower and the adsorption tower are combined, dichloropropene impurities which are difficult to separate are subjected to polymerization reaction to generate a polydichloropropene polymer, and due to the fact that the boiling point difference between the polymer and dichloropropane is large, the polymer is easy to separate and purify, refining and purification of 1, 2-dichloropropane are successfully achieved. The purity of final 1, 2-dichloropropane is greater than or equal to 99.9%, and the content of residual dichloropropene is 1t; and the total weight is 100 ppm. Meanwhile, the dichloropropene polymerization process is mild in condition, low in equipment requirement, simple in flow and beneficial to expanded production.

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, polymerization 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, polymerization 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, which removes the dichloropropene impurities that are difficult to separate by polymerization, and can effectively make the 1,2-dichloropropane produced as a by-product 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 polymerization 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 materials;

[0010] The polymerization reactor is located downstream of the light-removal tower, and is provided with a feed port, an initiator inlet, and a discharge port. The feed port is connected to the liquid outlet at the bottom of the light-removal tower through a pipeline for receiving materials from the light-removal tower, the initiator inlet is used for adding initiator, and the discharge port is used for discharging materials after polymerization reaction;

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

[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 polymerization reactor 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, and a packing support and a liquid distributor are arranged in the tower.

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

[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 by the reboiler and partially refluxed to the light-removal tower to maintain the material balance in the tower, and the rest is transported to the polymerization reactor through a pipeline.

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

[0020] Preferably, the polymerization reactor is provided with an agitator for maintaining the uniformity of dispersion of materials in the polymerization reactor.

[0021] Preferably, the discharge port at the top of the de-weighting tower is connected to a condenser for cooling and discharging 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 refluxing a portion of it 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.

[0022] Preferably, the polymer residue discharge port at the bottom of the de-weighting tower is connected to a reboiler for vaporizing the discharged liquid material, and part of the material partially vaporized 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.

[0023] Preferably, a cooler is provided on the pipeline connected to the polymer residue discharge port at the bottom of the deweighting tower, for cooling the material containing the polymer residue.

[0024] 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.

[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] 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:

[0027] 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;

[0028] 2) the material after being treated by the light-removal tower enters the polymerization reactor, and an initiator is added thereto, and the dichloropropylene compounds undergo polymerization reaction at a certain temperature and pressure, thereby forming a polymer residue that is easily separated from 1,2-dichloropropane;

[0029] 3) the material containing polymer residue after the reaction in the polymerization reactor enters the de-weighting tower, is refluxed at a certain temperature, and the polymer residue is discharged from the bottom outlet of the de-weighting tower, and the purified 1,2-dichloropropane is discharged from the top outlet of the de-weighting tower and enters the adsorption tower;

[0030] 4) In the adsorption tower, unreacted dichloropropylene compounds are further removed by adsorption of the adsorbent.

[0031] Preferably, the crude 1,2-dichloropropane contains, by weight percentage, 75-85% of 1,2-dichloropropane, 1-3% of 1-chloropropane, 2-4% of trans-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 1,1-dichloropropene, 4-6% of 3,3-dichloropropene, etc.

[0032] Preferably, the light component includes one or more of 1-chloropropane, 1-chloropropylene, 2-chloropropylene, 1,5-hexadiene and the like.

[0033] 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.

[0034] Preferably, the initiator used in step 2) is selected from one or more of ethylaluminum, butyl lithium, benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, and persulfate.

[0035] Preferably, the amount of the initiator in step 2) accounts for 0.1-5% of the total mass of the feed.

[0036] Preferably, in step 2), the polymerization reaction temperature is 45° C. to 55° C., and the reaction time is 3.5 h to 4.5 h.

[0037] Preferably, the number of theoretical plates of the deweighting tower in step 3) is 25-35, the feed position is the 18th to 23rd theoretical plates, the tower top temperature is 85-100° C., the pressure is 95-105 kPaA; and the operating reflux ratio is 1-6.

[0038] Preferably, both the light-removal tower and the heavy-removal tower are packed towers, and the packings are small metal random packings, metal corrugated packings, metal wire mesh corrugated packings, preferably metal wire mesh corrugated packings.

[0039] 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.

[0040] Furthermore, the purity of the product 1,2-dichloropropane finally treated by adsorption tower is ≥99.9%, and the residual dichloropropylene is <100ppm.

[0041] The beneficial effects of the present invention are:

[0042] (1) The initiators that can be used in the present invention are ethyl aluminum, butyl lithium, benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, and persulfate, which have excellent performance, controllable and sufficient polymerization reaction, and a conversion rate of up to 99.4%.

[0043] (2) The process conditions for the polymerization of dichloropropylene are mild, the equipment requirements are low, the process is simple, and it is conducive to expanding production;

[0044] (3) The boiling point difference between the generated poly(dichloropropylene) and dichloropropane is large, and it is easy to separate and purify. The purified 1,2-dichloropropane has high purity.

[0045] The combination of distillation, polymerization and adsorption technology simplifies the separation process, reduces the difficulty of refining, saves energy, and improves the economic value of 1,2-dichloropropane, a by-product of the 3-chloropropylene unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] 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.

[0047] Figure 1 It is a schematic diagram of the structure of the refining device according to the present invention.

[0048] Among them, T101 is a light-removal tower, E101 is a top condenser of the light-removal tower, E102 is a reboiler in the bottom of the light-removal tower, R101 is a polymerization reactor, T102 is a heavy-removal tower, E103 is a top condenser of the heavy-removal tower, E104 is a reboiler in the bottom of the heavy-removal tower, E105 is a cooler, T103 and T104 are adsorption towers, and S101 and S102 are reflux tanks. DETAILED DESCRIPTION

[0049] 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.

[0050] 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".

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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-chloropropylene unit according to the present invention.

[0061] like Figure 1 As shown, the refining device for 1,2-dichloropropane produced as a byproduct of a 3-chloropropylene unit according to the present invention comprises a light removal tower T101, a polymerization reactor R101, a heavy removal tower T102 and adsorption towers T103 and T104;

[0062] 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 materials;

[0063] The polymerization reactor R101 is located downstream of the light-removal tower T101. The polymerization reactor R101 is provided with a feed port, an initiator inlet, and a discharge port. 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 initiator inlet is used for adding initiators, and the discharge port is used for discharging materials after polymerization reaction.

[0064] The deweighting tower T102 is located downstream of the polymerization reactor R101. A feed port is provided in the middle of the deweighting tower T102, which is connected to the discharge port of the polymerization reactor R101 through a pipeline, and is used to receive materials from the polymerization 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 polymer residue discharge port is provided at the bottom of the deweighting tower T102, and is used to discharge polymer residue after polymerization.

[0065] 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.

[0066] 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.

[0067] Preferably, the polymerization reactor R101 is a stirred tank reactor.

[0068] Preferably, the deweighting tower T102 is a packed tower, in which a packing support, a liquid distributor, a redistributor and a demister are arranged.

[0069] Preferably, the adsorption towers T103 and T104 are molecular sieve packing towers, and packing supports and liquid distributors are arranged inside the towers.

[0070] 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.

[0071] Preferably, the liquid outlet at the bottom of the light-removal tower T101 is connected to a reboiler E102 for vaporizing the discharged liquid substance. The liquid substance discharged through the liquid outlet is partially vaporized by the reboiler E102 and partially refluxed to the light-removal tower to maintain the material balance in the tower, and the rest is transported to the polymerization reactor R101 through a pipeline.

[0072] Preferably, the polymerization reactor R101 is provided with a heat exchange jacket for introducing condensed water to control the temperature of the polymerization reactor R101.

[0073] Preferably, the polymerization reactor R101 is provided with an agitator for maintaining the uniformity of dispersion of materials in the polymerization reactor R101.

[0074] Preferably, the discharge port at the top of the de-weighting tower T102 is connected to a condenser E103 for condensing and discharging the purified 1,2-dichloropropane. More preferably, the condenser E103 is connected to a reflux tank S102 for temporarily storing the condensed purified 1,2-dichloropropane and returning a portion of it to the de-weighting 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 polymer residue discharge port at the bottom of the deweighting tower T102 is connected to a reboiler E104 for vaporizing the discharged liquid material, and a portion of the liquid material partially vaporized by the reboiler E104 flows back to the deweighting tower T102 to maintain the material balance in the tower, and the rest is discharged from the system through a pipeline.

[0076] Optionally, a cooler E105 is provided on the pipeline connected to the polymer residue discharge port at the bottom of the deweighting tower T102 for cooling the material containing the polymer residue.

[0077] 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.

[0078] 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 the continuous operation of the entire device, for example Figure 1 As shown, it comprises two adsorption towers T103 and T104.

[0079] The method for refining 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:

[0080] (1) The crude by-product 1,2-dichloropropane (DCP) produced by the 3-chloropropene unit is sent to the light-removal tower T101. The number of theoretical plates of light-removal tower T101 is 50 to 70, the feed position is 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. The light components of the tower top gas phase are condensed by condenser E101 and enter the reflux tank S101, and then part of them are refluxed, and the rest are discharged from the system. The top discharge is light components, water and azeotropic DCP. The tower bottom temperature is 96 to 105°C, the pressure is 110 to 120 kPaA, and the operating reflux ratio is 1 to 5. A part of the bottom liquid phase is reboiled and refluxed by reboiler E102, and the rest is transported to the polymerization reactor R101.

[0081] (2) The polymerization reactor R101 receives the material from the light removal tower T101, and adds an initiator at the same time. The initiator can be one or more selected from ethyl aluminum, butyl lithium, benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, and persulfate. The amount of initiator accounts for 0.1-5% of the total mass of the feed. The reaction temperature is 45°C to 55°C, and the reaction time is 3.5h to 4.5h. After sufficient reaction, a DCP mixed liquid containing polydichloropropylene is obtained at the discharge port of the polymerization reactor R101. The product is analyzed by gas chromatography, and the conversion rate of dichloropropylene is 99.4%, and the boiling point of the generated polydichloropropylene is increased to above 200°C.

[0082] (3) The DCP mixed liquid containing polydichloropropylene is transported to the deweighting tower T102, which has a theoretical plate number of 25 to 35 and a feed position of 18 to 23 blocks. The top temperature of the tower is 85 to 100°C and the pressure is 95 to 105 kPaA. After the top gas phase is condensed by condenser E103, a high-purity DCP material with a content of ≥99.5% is obtained, a part of which is refluxed and the rest is sent to adsorption towers T103 and T104. The bottom temperature of the deweighting tower T102 is 165 to 180°C and the pressure is 108 to 124 kPaA; the operating reflux ratio is 1 to 6. Part of the material containing polymer residue discharged through the polymer residue discharge port at the bottom of the tower is reboiled and refluxed by the reboiler E104, and the other part is cooled and discharged from the system by the cooler E105.

[0083] (4) One of the adsorption towers T103 and T104 is used for adsorption while the other is used for adsorbent regeneration. The two towers are operated alternately. The adsorption towers T103 and T104 receive the top material of the deweighting tower T102. After being fully adsorbed by the adsorption towers T103 and T104, the purity of 1,2-dichloropropane in the outlet material reaches ≥99.9%, and the purity of dichloropropylene is <100ppm.

[0084] 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.

[0085] Example 1

[0086] 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, which is filled with corrugated wire mesh filler with 60 theoretical plates. The feed position is 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 light-removal tower T101 is condensed and part of it is refluxed, and the other part of the material is discharged from the system. Trace water, 1-chloropropane, 1-chloropropylene, 2-chloropropylene, and 1,5-hexadiene are removed from the top of the tower. The bottom of the tower discharges 1175Kg / h and enters the polymerization reactor R101.

[0087] The initiator in the polymerization reactor R101 is azobisisobutyronitrile, the initiator feed rate is 2 kg / h, the reaction temperature is 49° C., and the reaction time is 4 hours.

[0088] The material from the outlet of polymerization reactor R101 enters deweighting tower T102, which has 30 theoretical plates and the feeding position is the 20th theoretical plate. The tower top temperature is 94°C and the pressure is normal pressure. The tower bottom temperature is 168.8°C and the operating reflux ratio is 2. The top discharge is ≥99.5% high-purity 1,2-dichloropropane, which is sent to adsorption towers T103 and T104, and the polymer residue is discharged from the tower bottom.

[0089] The adsorbent in adsorption towers T103 and T104 is 5A molecular sieve, the temperature in the tower is 42.5°C, the pressure in the tower is 21 kPaG, the residual dichloropropylene content after adsorption is <100 ppm, and a dichloropropylene product with a purity of ≥99.9% is obtained.

[0090] 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 polymerization 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 materials; The polymerization reactor is located downstream of the light-removal tower, and is provided with a feed port, an initiator inlet, and a discharge port. The feed port is connected to the liquid outlet at the bottom of the light-removal tower through a pipeline for receiving materials from the light-removal tower, the initiator inlet is used for adding initiator, and the discharge port is used for discharging materials after polymerization reaction; The deweighting tower is located downstream of the polymerization reactor, a feed port is provided in the middle of the deweighting tower, which is connected to the discharge port of the polymerization reactor through a pipeline, and is used to receive materials from the polymerization reactor, a discharge port is provided at the top of the deweighting tower, and is used to discharge purified 1,2-dichloropropane, and a polymer residue discharge port is provided at the bottom of the deweighting tower, and is used to discharge polymer residue after polymerization; 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 polymerization reactor is a stirred tank 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; Preferably, the gas outlet at the top of the light-removal tower is connected to a condenser for condensing the discharged gaseous substances into liquid form. 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 by the reboiler and then partially refluxed to the light-removal tower to maintain the material balance in the tower, and the rest is transported to the polymerization reactor through a pipeline; Preferably, the polymerization reactor is provided with a heat exchange jacket for introducing condensed water to control the temperature of the polymerization reactor; Preferably, the polymerization reactor is provided with an agitator for maintaining the uniformity of dispersion of materials in the polymerization reactor; Preferably, the discharge port at the top of the de-weighting tower is connected to a condenser for cooling and discharging 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 polymer residue discharge port at the bottom of the de-weighting tower is connected to a reboiler for gasifying the discharged liquid material, and part of the material partially gasified by the reboiler is refluxed to the de-weighting tower to maintain the reaction balance of the material in the tower, and the rest is discharged from the system through a pipeline; Preferably, a cooler is provided on the pipeline connected to the polymer residue discharge port at the bottom of the deweighting tower, for cooling the material containing the polymer residue.

3. The refining device according to claim 1, characterized in that: Valves and pumps can be 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.

4. The refining device according to claim 1, characterized in that: The number of the adsorption towers is at least one, and more preferably at least two; when two or more adsorption towers are provided, the adsorption towers are operated alternately to ensure continuous operation of the entire device.

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 by the light-removal tower enters the polymerization reactor, and an initiator is added thereto, and the dichloropropylene compounds undergo polymerization reaction at a certain temperature and pressure, thereby forming a polymer residue that is easily separated from 1,2-dichloropropane; 3) the material containing polymer residue after the reaction in the polymerization reactor enters the de-weighting tower, is refluxed at a certain temperature, and the polymer residue is discharged from the bottom outlet of the de-weighting tower, and the purified 1,2-dichloropropane is discharged from the top outlet 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 trans-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 1,1-dichloropropene, 4-6% of 3,3-dichloropropene, etc.; Preferably, the light component includes one or more of 1-chloropropane, 1-chloropropylene, 2-chloropropylene, 1,5-hexadiene, etc.; 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.

7. The refining method according to claim 5, characterized in that: The initiator used in step 2) is selected from one or more of ethyl aluminum, butyl lithium, benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, and persulfate; Preferably, the amount of the initiator in step 2) accounts for 0.1 to 5% of the total mass of the feed; Preferably, in step 2), the polymerization reaction temperature is 45°C to 55°C, and the reaction time is 3.5h to 4.5h; Preferably, the number of theoretical plates of the deweighting tower in step 3) is 25-35, the feed position is the 18th to 23rd theoretical plates, the tower top temperature is 85-100° C., the pressure is 95-105 kPaA; and the operating reflux ratio is 1-6.

8. The purification method according to claim 5, characterized in that: The light-removal tower and the heavy-removal tower are both packed towers, and the packings are small metal random packings, metal corrugated packings, metal wire mesh corrugated packings, preferably metal wire mesh corrugated packings.

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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