A 3-chloropropylene device combined with rectification, chlorination and adsorption produces 1,2-dichloropropane refining device and method

Abstract

The application discloses a refining device and method for 1,2-dichloropropane by-produced in a 3-chloropropylene device. The device combines a light-removing tower, a chlorination reaction kettle, a heavy-removing tower and an adsorption tower, so that dichloropropylene compounds which are difficult to separate from 1,2-dichloropropane react with chlorine to form saturated chloro-compounds heavy components which are easy to separate from 1,2-dichloropropane, thereby purifying 1,2-dichloropropane, and the purity of 1,2-dichloropropane by-produced in the 3-chloropropylene device is greater than or equal to 99.9%, and the residual dichloropropylene is less than 100 ppm, the economic value of the product is improved, the energy-saving and consumption-reducing effect of the extractive distillation technology is achieved, and the device has a wide industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of chemical by-product purification technology, specifically relating to a purification apparatus and method for 1,2-dichloropropane by-product from a 3-chloropropene plant. In particular, by utilizing a combination of distillation, chlorination and adsorption techniques, the purity of 1,2-dichloropropane by-product from the 3-chloropropene plant reaches ≥99.9%, with residual dichloropropene <100ppm. Background Technology

[0002] 1,2-Dichloropropane is an excellent organic solvent and chemical intermediate. It can be used to formulate paints, inks, thinners, and PVC adhesives. It can replace xylene and other benzene compounds in the production of benzene-free banana oil, thinner, and polyurethane thinners. It is also a major raw material for pesticide emulsifiers, lubricants, flame retardants, plasticizers, oilfield demulsifiers, detergents, and nonionic surfactants. Dichloropropane is also an important raw material for cosmetics and pharmaceuticals. Industrially, it can also be used as a raw material for the production of tetrachloropropene. However, when using 1,2-dichloropropane as a raw material for the production of tetrachloropropene, the dichloropropene content must be below 100 ppm.

[0003] Industrial plants that produce 3-chloropropene using the high-temperature method often generate a large amount of byproduct DD mixture (a 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. After separating 1,3-dichloropropene from the 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%), and 3,3-dichloropropene (4-6%). Practice has shown that, due to the very low relative volatility of 3,3-dichloropropene, 2,3-dichloropropene, and 1,2-dichloropropane, separation by ordinary distillation is difficult and energy-intensive.

[0004] In summary, achieving high-precision purification of 1,2-dichloropropane, a byproduct of 3-chloropropene plants, through a simple and low-cost process is a significant challenge. This invention utilizes a combination of distillation, chlorination, and adsorption techniques to obtain a high-purity product with a dichloropropene content of <100 ppm and 1,2-dichloropropane content of ≥99.9%, saving energy and increasing the product's application value. Summary of the Invention

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

[0006] One of the objectives of this invention is to provide a purification apparatus for 1,2-dichloropropane byproduct of a 3-chloropropene plant.

[0007] The second objective of this invention is to provide a purification method for 1,2-dichloropropane, a byproduct of a 3-chloropropene plant.

[0008] According to one aspect of the present invention, a purification apparatus for 1,2-dichloropropane byproduct of a 3-chloropropene plant is provided, comprising a light-light removal tower, a chlorination reactor, a heavy-light removal tower, and an adsorption tower;

[0009] The light-weight removal tower is provided with a gas outlet at the top for discharging gaseous substances, a feed inlet in 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 reactor is located downstream of the light-light product removal tower. The top of the chlorination reactor is provided with a discharge port for discharging the chlorinated product. The bottom of the chlorination reactor is provided with a feed port and a gas inlet, which are connected to the liquid outlet at the bottom of the light-light product removal tower via pipelines for receiving materials from the light-light product removal tower. The gas inlet is used to introduce chlorine gas into the chlorination reactor.

[0011] The heavy component removal tower is located downstream of the chlorination reactor. The heavy component removal tower has a feed inlet in the middle, which is connected to the discharge outlet of the chlorination reactor through a pipeline to receive materials from the chlorination reactor. The heavy component removal tower has a discharge outlet at the top to discharge purified 1,2-dichloropropane. The heavy component removal tower has a heavy component residue discharge outlet at the bottom to discharge heavy component residue.

[0012] The adsorption tower is located downstream of the de-weighting tower. The top of the adsorption tower is provided with a feed inlet, which is connected to the discharge outlet of the de-weighting tower via a pipeline for receiving material from the de-weighting tower. The bottom of the adsorption tower is provided with a discharge outlet for discharging the purified 1,2-dichloropropane final product after adsorption treatment.

[0013] Preferably, the light-weight removal tower is a packed tower, and the tower is equipped with packing support, liquid distributor, redistributor and demister.

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

[0015] Preferably, the deweight removal tower is a packed tower, and the tower is equipped with packing support, liquid distributor, redistributor and demister.

[0016] Preferably, the adsorption tower is a molecular sieve packed tower, and the tower is equipped with packing support and liquid distributor.

[0017] Preferably, the gas outlet at the top of the light-weight 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 returning a portion of it to the light-weight removal tower to maintain the material balance within the tower, while the other portion is discharged from the system through a pipeline.

[0018] Preferably, the liquid outlet at the bottom of the light-weight removal tower is connected to a reboiler for vaporizing the discharged liquid substance. After passing through the reboiler, part of the liquid substance discharged through the liquid outlet is vaporized and returned to the light-weight removal tower to maintain the material balance inside the tower, and the remainder is transported to the chlorination reactor through a pipeline.

[0019] Preferably, the chlorination reactor is equipped with a heat exchange jacket for introducing condensate to control the temperature of the chlorination reactor.

[0020] Preferably, the chlorination reactor is equipped with a stirrer to maintain the uniformity of material dispersion within the chlorination reactor.

[0021] Preferably, the chlorination reactor is equipped with a chlorine gas distributor to ensure uniform reaction.

[0022] Preferably, the chlorination reactor is equipped with a Venturi jet pump to mix unreacted chlorine gas with the feed chlorine gas, thereby achieving complete utilization of the chlorine gas.

[0023] Preferably, the outlet at the top of the deweighting 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 returning a portion of it to the deweighting tower to maintain the material balance within the tower, while the remainder is transported to the adsorption tower via pipeline.

[0024] Preferably, the discharge port of the heavy component residue at the bottom of the deweighting tower is connected to a reboiler for gasifying the discharged material. Part of the material further gasified by the reboiler is returned to the deweighting tower to maintain the material balance in the tower, and the remainder 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 operate alternately to ensure the continuous operation of the entire device.

[0026] Preferably, valves and pumps can be installed on each pipeline of the refining unit for the byproduct 1,2-dichloropropane from the 3-chloropropene unit to control the material flow rate and volume.

[0027] According to another aspect of the present invention, a method for purifying 1,2-dichloropropane, a byproduct of a 3-chloropropene plant, is provided, the method comprising:

[0028] 1) The crude 1,2-dichloropropane byproduct of the 3-chloropropene unit is fed into the light component removal tower. The light components are removed by reflux treatment at a certain temperature. The light components are discharged through the gas outlet at the top of the light component removal tower.

[0029] 2) The material after being treated by the light-light tower enters the chlorination reactor, where dichloropropene compounds that are difficult to separate from 1,2-dichloropropane react with chlorine gas under certain temperature and pressure to form a heavy component of saturated chlorinated compounds that are 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-heavy tower. The heavy components of saturated chlorinated compounds in the material are removed by reflux treatment at a certain temperature. The heavy components are discharged through the heavy component residue outlet at the bottom of the de-heavy tower. The purified 1,2-dichloropropane is discharged from the top outlet of the de-heavy tower and enters the adsorption tower.

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

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

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

[0034] Preferably, in step 1), the number of theoretical trays in the light-light removal tower is 50 to 70, the feed position is located at the 20th to 40th theoretical tray, the operating conditions are atmospheric pressure, the operating reflux ratio is 1 to 3, and the tower top temperature is 30 to 37.4°C.

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

[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, in step 3), the theoretical number of trays in the deweighting tower is 50-80, with the feed position on the 20th-40th theoretical tray. The operating conditions are atmospheric pressure operation and a reflux ratio of 0.4-2. The tower top temperature is 85-96℃.

[0038] Preferably, the light-weight removal tower in step 1) is a packed tower, and the packing is a small metal Baur ring packing, a metal corrugated packing, or a metal wire mesh corrugated packing, preferably a metal wire mesh corrugated packing.

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

[0040] Preferably, the adsorption tower has an internal temperature of 40–50°C and an internal pressure of 10–30 kPaG, and is filled with an adsorbent, which is 3A, 4A, 5A or 13X molecular sieve.

[0041] Preferably, the final product after adsorption treatment in the adsorption tower has a purity of ≥99.9% for 1,2-dichloropropane and a residual dichloropropene content of <100 ppm.

[0042] Beneficial effects

[0043] The apparatus according to the present invention utilizes a combination of a light-light residue tower, a chlorination reactor, a heavy residue tower, and an adsorption tower to react dichloropropene compounds, which are difficult to separate from 1,2-dichloropropane, with chlorine gas, thereby forming saturated chlorinated heavy components that are easily separated from 1,2-dichloropropane. This purifies 1,2-dichloropropane, resulting in a purity of ≥99.9% for the 1,2-dichloropropane byproduct of the 3-chloropropene unit and a residual dichloropropene content of <100 ppm. This improves the economic value of the product, and the extractive distillation technology achieves energy saving and consumption reduction, showing broad prospects for industrial application. Attached Figure Description

[0044] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the refining apparatus according to the present invention.

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

[0047] The present invention will now be described in detail. Before proceeding with the description, it should be understood that the terminology used in this specification and the appended claims should not be construed as limited to its general or dictionary meaning, but rather should be interpreted according to the meaning and concept corresponding to the technical aspects of the invention, based on the principle that the inventors are allowed to appropriately define the terms for the best interpretation. Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention. It should be understood that other equivalents or modifications can be obtained from it without departing from the spirit and scope of the invention.

[0048] In this document, the terms “comprising,” “including,” “having,” “containing,” or any other similar terms are open-ended conjunctions intended to cover non-exclusive inclusions. For example, a composition or article containing a plurality of elements is not limited to those listed herein, but may also include other elements not explicitly listed but typically inherent to the composition or article. Furthermore, unless explicitly stated to the contrary, the term “or” is inclusive, not exclusive. For example, the condition “A or B” is satisfied in any of the following cases: 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); A and B are both true (or exist). Moreover, in this document, the terms “comprising,” “including,” “having,” and “containing” should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as “composed of” and “substantially composed of.”

[0049] In this document, all features or conditions defined in the form of numerical ranges or percentage ranges are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual values ​​within those ranges, particularly integer values. For example, a range description of "1 to 8" should be considered as specifically disclosing all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly secondary ranges defined by all integer values, and should be considered as specifically disclosing individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise specified, the foregoing interpretation applies to all content throughout this invention, regardless of its scope.

[0050] If a 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 this document has specifically disclosed all ranges consisting of any upper or preferred value of that range and the lower or preferred value of that range, regardless of whether such ranges are separately disclosed. Furthermore, when a range of numerical values ​​is mentioned herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0051] In this document, numerical values ​​are to be understood as having a precision with significant digits, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover a range from 39.50 to 40.49.

[0052] To clarify the invention, parts irrelevant to the description have been omitted from the drawings, and throughout the specification, the same or similar parts are indicated by the same reference numerals.

[0053] Furthermore, for ease of explanation, the dimensions and thicknesses of each component shown in the accompanying drawings are arbitrarily illustrated; therefore, the invention is not necessarily limited to those shown in the drawings.

[0054] Throughout the specification, when it is said that an element is "connected" to another element, it includes not only "direct connection" but also "indirect connection" between other components. Furthermore, when it is said that an element "comprises" a part, it means that the element may further include other parts rather than exclude them, unless otherwise explicitly stated.

[0055] The terms “first,” “second,” etc., used in this article are used to explain various constituent elements, and they are only used for the purpose of distinguishing one constituent element from another.

[0056] Furthermore, the terminology used herein is for the purpose of explaining exemplary embodiments only and is not intended to limit the invention. Singular expressions also include their plural expressions unless otherwise expressly indicated in the context. Terms such as “comprising,” “equipped with,” or “having” as used herein are used to specify the presence of a practical characteristic, number, step, constituent element, or combination thereof, and should be understood to not exclude the possibility of the addition or presence of one or more other characteristics, numbers, steps, constituent elements, or combinations thereof.

[0057] Furthermore, if a layer or element is referred to as being formed "above" or "on top of" a "layer" or "element", it means that each layer or element is formed directly on that layer or element, or that other layers or elements may be formed between layers, bodies, or substrates.

[0058] The following is in conjunction with the appendix Figure 1 The present invention describes in detail the refining process for 1,2-dichloropropane byproduct of the 3-chloropropene plant according to the present invention.

[0059] like Figure 1 As shown, the purification apparatus for 1,2-dichloropropane byproduct of the 3-chloropropene plant according to the present invention includes a light-light removal tower T101, a chlorination reactor R101, a heavy-weight removal tower T102, and adsorption towers T103 and T104.

[0060] The light-weight removal tower T101 is provided with a gas outlet at the top for discharging gaseous substances, a feed inlet in 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-light product 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-light product removal tower T101 via a pipeline for receiving material from the light-light product removal tower T101. The gas inlet is used to introduce chlorine gas into the chlorination reactor R101.

[0062] The heavy component removal tower T102 is located downstream of the chlorination reactor R101. The heavy component removal tower T102 has a feed inlet in the middle, which is connected to the discharge outlet of the chlorination reactor R101 through a pipeline to receive the material from the chlorination reactor R101. The heavy component removal tower T102 has a discharge outlet at the top to discharge the purified 1,2-dichloropropane. The heavy component removal tower T102 has a heavy component residue discharge outlet at the bottom to discharge the heavy component residue.

[0063] Two adsorption towers, T103 and T104, are set up and operate alternately. They are located downstream of the heavy removal tower T102. The top of the adsorption towers T103 and T104 are provided with inlets, which are connected to the outlet of the heavy removal tower T102 through pipelines to receive the material from the heavy removal tower T102. The bottom of the adsorption towers T103 and T104 are provided with outlets to discharge the purified 1,2-dichloropropane final product after adsorption treatment.

[0064] Preferably, the light-weight removal tower T101 is a packed tower, and the tower is equipped with packing support, liquid distributor, redistributor and demister.

[0065] Preferably, the chlorination reactor R101 is a stirred tank reactor.

[0066] Preferably, the deweight removal tower T102 is a packed tower, and the tower is equipped with packing support, liquid distributor, redistributor and demister.

[0067] Preferably, the adsorption towers T103 and T104 are molecular sieve packed towers, and the towers are equipped with packing supports and liquid distributors.

[0068] Preferably, the gas outlet at the top of the light-weight 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 returning a portion of it to the light-weight removal tower T101 to maintain the material balance inside the tower, while the other portion is discharged through the system.

[0069] Preferably, the liquid outlet at the bottom of the light-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 returned to the light-light-removal tower T101 to maintain the material balance in the tower. The remaining part is transported to the chlorination reactor R101 through a pipeline.

[0070] Preferably, the chlorination reactor R101 is equipped with a heat exchange jacket for introducing condensate to control the temperature of the chlorination reactor R101.

[0071] Preferably, the chlorination reactor R101 is equipped with a stirrer to maintain the uniformity of material dispersion within the chlorination reactor R101.

[0072] Preferably, the chlorination reactor R101 is equipped with a chlorine gas distributor to ensure uniform reaction.

[0073] Preferably, the chlorination reactor R101 is equipped with a Venturi jet pump to mix unreacted chlorine gas with the feed chlorine gas, thereby achieving complete utilization of the chlorine gas.

[0074] Preferably, the outlet 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. The remaining portion is transported to the adsorption towers T103 and T104 via pipelines.

[0075] Preferably, the heavy component residue outlet at the bottom of the deweighting tower T102 is connected to a reboiler E112 for vaporizing the discharged liquid material. Part of the material partially vaporized by the reboiler E112 is returned to the deweighting tower T102 to maintain the reaction balance of the material in the tower, and the remainder is discharged from the system through a pipeline.

[0076] The purification method for 1,2-dichloropropane, a byproduct of a 3-chloropropene unit, using the purification apparatus described above according to the present invention, comprises the following steps: The crude 1,2-dichloropropane byproduct of the 3-chloropropene unit is first fed into a light-light product removal tower T101, which has 50-70 theoretical trays, with the feed located at trays 20-40. The operating conditions are atmospheric pressure and an operating reflux ratio of 1-3. The top temperature is 30-37.4°C, the bottom temperature is 100-105°C, and the pressure is 25-35 kPaG. After the vapor phase at the top of the light component removal tower T101 is condensed, a portion is refluxed back into the tower, while the remaining portion is discharged via pump P101. In a typical implementation, the light components removed from the top of the light component removal tower T101 include 1-chloropropane, trans-1-chloropropene, 2-chloropropene, and 1,5-hexadiene. Simultaneously, water is also largely removed in this step, preventing the generation of hydrochloric acid during subsequent chlorination processes from affecting the product and equipment. A portion of the bottom material from the light component removal tower T101 is refluxed via reboiler E111, while the remaining portion is collected via pump P105, cooled in heat exchanger E103, and then sent to the chlorination reactor R101.

[0077] In a typical implementation, the main feed materials in the chlorination reactor R101 are 1,2-dichloropropane (DCP), 3,3-dichloropropene, 2,3-dichloropropene, and cis-1,3-dichloropropene. The material from the bottom of tower T101 is pumped out by pump P105, heated to 30°C in heat exchanger E103, and then enters the chlorination reactor R101 at the bottom. Simultaneously, another feed stream from the bottom of the reactor is chlorine gas. After sufficient temperature control and reaction in the chlorination reactor R101, the gas is sent to the de-weighting tower T102 through the top outlet of the chlorination reactor R101. During the chlorination reaction, the total feed flow rate is 1175 kg / h, and the chlorine gas flow rate is 126 kg / h. The chlorination reactor R101 is equipped with a chlorine gas distributor and a stirrer, and stirring is maintained throughout the reaction to ensure timely heat dissipation from the solution and prevent uneven reaction caused by excessively high local temperatures, which could lead to a series of side reactions. The chlorination reaction is exothermic, and the chlorination reactor R101 is equipped with a condensate circulation cooling system. Excess chlorine gas is mixed with the feed chlorine gas via a Venturi jet pump to ensure complete utilization of the chlorine. The reaction temperature is 32°C, and the reaction residence time is 2 hours. Excessive reaction time will cause severe dichloropropane substitution side reactions, resulting in material loss. In a typical implementation, 3,3-dichloropropene undergoes chlorination addition with cis-1,3-dichloropropene to produce 1,1,2,3-tetrachloropropane, and 2,3-dichloropropene undergoes addition to produce 1,2,2,3-tetrachloropropane.

[0078] The material from the top outlet of the chlorination reactor R101 enters the deweighting tower T102. The packing material in the deweighting tower T102 is corrugated metal wire mesh packing, with a theoretical number of 50-80 plates. The feed position is located at plate 20-40. The operating conditions are atmospheric pressure operation with a reflux ratio of 0.4-2. The top temperature is 85-96℃, the bottom temperature is 180-190℃, and the pressure is 25-35 kPaG. In a typical implementation, after the top vapor phase is condensed, a portion is refluxed back into the deweighting tower T102, while the other portion is collected by pump P103 to obtain 1,2-dichloropropane with a purity ≥99.5%. A portion of the bottom material is refluxed through reboiler E112, while the other portion consists of heavy impurities, mainly 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 dichloropropene impurities, yielding a dichloropropane product with a purity of ≥99.9%.

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

[0080] The following embodiments are merely examples illustrating implementations of the present invention and do not constitute any limitation on the present invention. Those skilled in the art will understand that modifications made without departing from the spirit and concept of the present invention fall within the protection scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following embodiments are commercially available products.

[0081] Example 1

[0082] The 3-chloropropene unit produces 1255 kg / h of crude 1,2-dichloropropane as a byproduct. The composition is 1,2-dichloropropane (80%, wt%), 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%). The feed is first fed into the light removal tower T101. T101 is packed with corrugated metal wire mesh packing, with 60 theoretical plates. The feed position is located on the 30th theoretical plate. The operating conditions are atmospheric pressure, operating reflux ratio of 2, tower top temperature of 36°C, and tower bottom temperature of 104°C. The gas phase at the top of the light-light removal tower T101 is condensed and first enters the reflux tank S101. Then, part of it is refluxed, and the other part of the material is discharged by pump P101. Trace amounts of water, 1-chloropropane, 1-chloropropene, 2-chloropropene, and 1,5-hexadiene are removed from the top of the tower.

[0083] The bottom feed of the light component removal tower T101 consists of DCP, 3,3-dichloropropene, 2,3-dichloropropene, and cis-1,3-dichloropropene. The bottom feed from T101 is collected by pump P105, cooled to 30°C in heat exchanger E103, and then sent to the bottom feed of chlorination reactor R101. Simultaneously, another feed stream from the bottom of chlorination reactor R101 is chlorine gas. After sufficient temperature control and reaction in chlorination reactor R101, the gas is sent to the heavy component removal tower T102 through the top outlet of chlorination reactor R101. During the chlorination reaction, the total feed flow rate is 1175 kg / h, and the chlorine gas flow rate is 126 kg / h. Chlorination reactor R101 is equipped with a chlorine gas distributor and a stirrer, maintaining constant stirring during the reaction to ensure timely heat dissipation within the solution and prevent uneven reaction caused by localized overheating, which could lead to a series of side reactions. The chlorination reaction is exothermic, and chlorination reactor R101 is equipped with a condensate circulation cooling system. Excess chlorine gas is mixed with the feed chlorine gas via a Venturi jet pump to ensure complete utilization of the chlorine. The reaction temperature is 32°C, and the reaction residence time is 2 hours. Excessive reaction time will cause severe dichloropropane substitution side reactions, resulting in material loss. In a typical implementation, 3,3-dichloropropene undergoes chlorination addition with cis-1,3-dichloropropene to produce 1,1,2,3-tetrachloropropane, and 2,3-dichloropropene undergoes addition to produce 1,2,2,3-tetrachloropropane.

[0084] The material from the top outlet of the chlorination reactor R101 enters the deweighting tower T102, which is packed with corrugated wire mesh packing. The theoretical plate number is 60, and the feed position is the 30th theoretical plate. The operating conditions are atmospheric pressure and an operating reflux ratio of 0.5. The top temperature is 93℃, and the bottom temperature is 185.7℃. The vapor phase at the top of the tower is condensed and enters the reflux tank S102. A portion is then refluxed, while the remaining material is collected by pump P103, yielding 1,2-dichloropropane with a purity ≥99.5%. The bottom product consists of heavy impurities, mainly 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 passed through adsorption towers T103 and T104 to remove dichloropropene impurities, yielding a dichloropropane product with a purity ≥99.9%. The adsorbent is 5A molecular sieve, the tower temperature is 42.5℃, the tower pressure is 21 kPaG, and the residual dichloropropene content after adsorption is <100 ppm.

[0086] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A refining device for 3-chloropropylene device byproduct 1,2-dichloropropane, comprising a light-removing column, a chlorination reactor, a heavy-removing column and an adsorption column; wherein the light-removing column is provided with a gas outlet at the top for discharging gaseous substances, a feed inlet at the middle of the column body for receiving raw materials, and a liquid outlet at the bottom for discharging liquid substances; the chlorination reactor is located downstream of the light-removing column, and is provided with a discharge outlet at the top for discharging chlorinated products, a feed inlet and a gas inlet at the bottom, which are connected with the liquid outlet at the bottom of the light-removing column through pipelines for receiving materials from the light-removing column, and the gas inlet is used for introducing chlorine gas into the chlorination reactor; the heavy-removing column is located downstream of the chlorination reactor, and is provided with a feed inlet at the middle of the column, which is connected with the discharge outlet of the chlorination reactor through a pipeline for receiving materials from the chlorination reactor, a discharge outlet at the top for discharging purified 1,2-dichloropropane, and a heavy component residue discharge outlet at the bottom for discharging heavy component residues; the adsorption column is located downstream of the heavy-removing column, and is provided with a feed inlet at the top, which is connected with the discharge outlet of the heavy-removing column through a pipeline for receiving materials from the heavy-removing column, and a discharge outlet at the bottom for discharging the final product of purified 1,2-dichloropropane after adsorption treatment. The light-removing column is a packed column, which is provided with packing support, liquid distributor, redistributor and demister. The chlorination reactor is a stirred tank reactor. The heavy-removing column is a packed column, which is provided with packing support, liquid distributor, redistributor and demister. The adsorption column is a molecular sieve packed column, which is provided with packing support and liquid distributor.

2. The finishing apparatus according to claim 1, characterized by The gas outlet at the top of the light-removing column is connected with a condenser for condensing the discharged gaseous substances into liquid, and the condenser is connected with a reflux tank, which is used for temporarily storing the condensed liquid substances, and part of the condensed liquid substances is refluxed to the light-removing column to maintain the material balance in the column, and the other part is discharged through a discharge system.

3. The finishing apparatus according to claim 1, characterized by The liquid outlet at the bottom of the light-removing column is connected with a reboiler for vaporizing the discharged liquid substances, and part of the discharged liquid substances is vaporized and refluxed to the light-removing column to maintain the material balance in the column, and the other part is transported to the chlorination reactor through a pipeline.

4. The finishing apparatus according to claim 1, wherein The chlorination reactor is provided with a heat exchange jacket for introducing condensed water to control the temperature of the chlorination reactor.

5. The finishing apparatus according to claim 1, wherein The chlorination reactor is provided with a stirrer for maintaining the uniformity of the dispersion of materials in the chlorination reactor.

6. The finishing apparatus of claim 1, wherein The chlorination reactor is provided with a chlorine gas distributor to ensure uniform reaction.

7. The finishing apparatus of claim 1 wherein, The chlorination reactor is provided with a Venturi jet pump for mixing unreacted chlorine gas with feed chlorine gas to achieve complete utilization of chlorine gas.

8. The finishing apparatus of claim 1, wherein The discharge outlet at the top of the heavy-removing column is connected with a condenser for condensing the purified 1,2-dichloropropane.

9. The finishing apparatus of claim 1, wherein ​ 10. The finishing apparatus of claim 1, wherein ​ 11. The finishing apparatus of claim 1 wherein, ​ 12. The finishing apparatus of claim 1 wherein, ​ 13. The finishing apparatus of claim 12, wherein, The condenser is connected with a reflux tank, which is used for temporarily storing the condensed purified 1,2-dichloropropane and refluxing part of the purified 1,2-dichloropropane to the heavy component removal tower to maintain the material balance in the tower, and the rest is transported to the adsorption tower through a pipeline.

14. The finishing apparatus of claim 1 wherein, The heavy component residue outlet at the bottom of the heavy component removal tower is connected with a reboiler, which is used for gasifying the discharged material, and part of the material further gasified through the reboiler is refluxed to the heavy component removal tower to maintain the material balance in the tower, and the rest is discharged through a pipeline discharge system.

15. The finishing apparatus of claim 1 wherein, The adsorption tower is at least one.

16. The finishing apparatus of claim 15, wherein, The adsorption tower is at least two, and when the adsorption tower is provided with two or more, the adsorption towers are alternately operated to ensure the continuous operation of the whole set of devices.

17. The finishing apparatus of claim 1 wherein, Valves and pumps are selectively arranged on each pipeline of the refining device for 1,2-dichloropropane byproduct of the 3-chloropropylene device, which are used for controlling the flow rate and flow of the material.

18. A refining method for 1,2-dichloropropane byproduct of a 3-chloropropylene device, the method comprising: 1) delivering the 1,2-dichloropropane crude byproduct of the 3-chloropropylene device into a light component removal tower, removing the light components in the crude byproduct through reflux treatment at a certain temperature, and discharging the light components through a gas outlet at the top of the light component removal tower; 2) after the treatment of the light component removal tower, the material enters a chlorination reactor, and a dichloropropene compound that is difficult to separate from 1,2-dichloropropane reacts with chlorine at a certain temperature and pressure to form a saturated chloro compound heavy component that is easy to separate from 1,2-dichloropropane; 3) after the reaction of the chlorination reactor, the material containing the saturated chloro compound enters a heavy component removal tower, and the saturated chloro compound heavy component in the material is removed through reflux treatment at a certain temperature, the heavy component is discharged through a heavy component residue outlet at the bottom of the heavy component removal tower, and the purified 1,2-dichloropropane is discharged from a material outlet at the top of the heavy component removal tower and enters an adsorption tower; 4) in the adsorption tower, unreacted dichloropropene compounds are further removed by adsorption of an adsorbent.

19. The method of claim 18, wherein, The 1,2-dichloropropane crude contains 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, and 4-6% of 3,3-dichloropropene by weight percentage.

20. The method of claim 18, wherein the refining is characterized by, The light components include one or more of 1-chloropropane, 1-chloropropene, 2-chloropropene, and 1,5-hexadiene.

21. The method of claim 18, wherein In step 1), the number of theoretical plates of the light component removal tower is 50-70, the feed position is located at the 20th-40th theoretical plate, the operating condition is normal pressure, the operating reflux ratio is 1-3, and the top temperature is 30-37.4 ℃; In step 2), the dichloropropene compound is selected from one or more of cis-1,3-dichloropropene, 2,3-dichloropropene, and 3,3-dichloropropene; In step 2), the saturated chloro compound is selected from one or more of 1,1,2,3-tetrachloropropane and 1,2,2,3-tetrachloropropane, etc. In step 2), the saturated chloro compound is selected from one or more of 1,1,2,3-tetrachloropropane and 1,2,2,3-tetrachloropropane, etc. The number of theoretical plates of the heavy-removing column in step 3) is 50-80, the feeding position is the 20th-40th theoretical plate, the operation condition is normal pressure operation, the reflux ratio is 0.4-2, and the tower top temperature is 85-96 DEG C.

22. The method of claim 18, wherein the refining is characterized by, The light-removing column in step 1) is a packed column, and the packing is small metal Pall ring packing or metal wire mesh packing.

23. The method of claim 22, wherein the refining is characterized by, The packing is metal wire mesh packing.

24. The method of claim 21, wherein the refining is characterized by, The heavy-removing column is a packed column, and the packing is small metal Pall ring packing or metal wire mesh packing.

25. The method of claim 24, wherein the refining is characterized by, The packing is metal wire mesh packing.

26. The method of claim 18, wherein The adsorption tower temperature is 40~50 o C, the tower pressure is 10~30 kPaG, wherein the adsorbent is 3A, 4A, 5A or 13X molecular sieve.

27. The method of claim 18, wherein the refining is characterized by, The purity of the product 1,2-dichloropropane after the adsorption treatment of the adsorption column is greater than or equal to 99.9%, and the residual dichloropropylene is less than 100 ppm.

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