CN115999486A - Photochemical reactor and photochlorination method using the same - Google Patents
Photochemical reactor and photochlorination method using the same Download PDFInfo
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- CN115999486A CN115999486A CN202211690803.5A CN202211690803A CN115999486A CN 115999486 A CN115999486 A CN 115999486A CN 202211690803 A CN202211690803 A CN 202211690803A CN 115999486 A CN115999486 A CN 115999486A
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Abstract
The present application provides a photochemical reactor comprising a feed column section, two or more light string column sections, and at least one spray column section; the feeding tower sections comprise feeding devices, each lamp group tower section is provided with at least one irradiation device, and each spray tower section is internally provided with a spray device; the irradiation device is arranged outside the tower section of the lamp group and is not inserted into the tower section of the lamp group. The present application also provides a method of performing a photochlorination reaction in the photochemical reactor. By adopting the reactor and the method, excellent catalytic efficiency is realized, overall temperature control of the whole reactor is remarkably improved, the service life of the reactor and various parts thereof is prolonged, and simultaneously, the introduction of pollution and impurities in the reactor can be effectively avoided.
Description
Technical Field
The present application relates to the field of photochemical synthesis, and more particularly to a photochemical reactor suitable for carrying out photochemical reactions and a photochlorination process using the same.
Background
Difluorochloroethane (HCFC-142 b for short) is a very important industrial raw material and is commonly used as a refrigerant, a foaming agent or a raw material for synthesizing PVDF, and the synthesis method mainly comprises a preparation process taking methyl chloroform as a raw material, a preparation process taking vinylidene chloride as a raw material, a preparation process taking vinyl chloride as a raw material, a preparation process taking acetylene as a raw material and the like. The acetylene synthesis process includes adding acetylene as initial material to HF to produce difluoroethane (1, 1-difluoroethane, F152 a), and final photochlorination of difluoroethane with chlorine to produce difluorochloroethane (HCFC-142 b).
The photochlorination of difluoroethane produces target difluorochloroethane (HCFC-142 b) and also produces polychlorinated byproducts, such as difluorodichloroethane, difluorotrichloroethane, difluorotetrachloroethane and the like, which need to be separated from the target products after the photocatalytic reaction, and the production of these target products also wastes raw materials.
Conventional photochlorination reactors of the prior art generally employ a manner of inserting a light source into the interior of the reactor to increase the light area, which can lead to further temperature rise in the interior of the reactor, affect the life of various components of the reactor, and the tube protection tube inserted into the interior of the reactor is easily broken.
In addition, in the prior art, the cooling of the reactor is generally performed by adopting a top spray water mode, but the mode can introduce water into the reaction materials, a dehydration and drying system is additionally required to be additionally added when the final product is treated, so that the capital cost and the operation cost of the production process are further improved, the effective control of the reaction temperature of the whole reaction system cannot be realized by adopting the top spray water mode, and the problems of the temperature flying in the reaction system, the reduction of the catalytic efficiency and the shortened service life of the reactor caused by the temperature flying in the reaction system can not be really solved.
Numerous studies have been made to solve these drawbacks, in an attempt to design various kinds, shapes and arrangement of the respective components in the reactor, but none of these prior art attempts has been truly successful in solving the problems. Therefore, it is still desired in the art to develop a photochlorination reaction system, which simultaneously achieves excellent catalytic performance and overall temperature control in the reaction system, improves the service life of the reactor and its various components, avoids breakage of the lamp tube sleeve due to uneven heating, and simultaneously effectively avoids introduction of pollution and impurities in the reactor.
Disclosure of Invention
The inventors of the present application have conducted intensive studies with respect to the above problems, and have succeeded in developing a photochemical reactor and a method for performing a photochlorination reaction using the same, thereby effectively solving the problems of the prior art which have been rapidly solved for a long time.
A first aspect of the present application provides a photochemical reactor comprising a feed column section at a bottom, two or more light string column sections above the feed column section, and at least one spray column section, each of the at least one spray column section being disposed above at least one light string column section, respectively; the feeding tower sections comprise feeding devices, each lamp group tower section is provided with at least one irradiation device, and each spray tower section is internally provided with a spray device; the bottom of the photochemical reactor is provided with a cooling liquid outlet; the irradiation device is arranged outside the tower section of the lamp group and is not inserted into the tower section of the lamp group.
In a second aspect the present application provides a method of performing a photochlorination reaction, the method being performed in a photochemical reactor of the present application, the method comprising the steps of: inputting gaseous substances containing chlorine and raw materials to be chlorinated into a reactor from a feeding tower section at the bottom of the reactor, and enabling the raw materials to be chlorinated to undergo a photochlorination reaction under the irradiation of an irradiation device in a lamp group tower section; spraying cooling liquid from the spraying device in the at least one spraying tower section in a batch or continuous mode, wherein the sprayed cooling liquid contacts and transfers heat with materials in the reactor.
Drawings
Various embodiments of the present application are discussed in the following paragraphs with reference to the drawings. It is noted here that the embodiments shown in the drawings and described in detail below are only some of the preferred embodiments of the present application, the scope of which is defined by the claims and is not limited to these preferred embodiments only. In addition, for the purposes of clarity, the reactors and various components shown in the figures of the specification are not drawn to true scale.
FIG. 1 shows a schematic view of a reactor structure according to one embodiment of the present application;
FIG. 2 shows an embodiment according to the present application wherein the irradiation device is mounted outside the light bank tower section via an interface;
FIG. 3 shows a schematic view of a reactor structure according to one embodiment of the present application.
The meaning of the numbers in the figures is as follows:
1 condensation-defoaming tower section; 2 spray tower sections; 3, a tower section of the lamp set; 4 a coolant cooler; 5 a cooling liquid container; 6 a cooling liquid circulating pump; 7, a cooling liquid high-level container; 8, a light source interface; 9 feeding tower sections; an L irradiation device; 10. 11, 12 temperature control valve.
Detailed Description
"Range" is disclosed herein in the form of lower and upper limits. There may be one or more lower limits and one or more upper limits, respectively. The given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular ranges. All ranges that can be defined in this way are inclusive and combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, ranges of 60-120 and 80-110 are listed for specific parameters, with the understanding that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.
In this application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values.
In this application, all embodiments and preferred embodiments mentioned herein can be combined with each other to form new solutions, unless specifically stated otherwise.
In the present application, all technical features mentioned herein as well as preferred features may be combined with each other to form new solutions, if not specifically stated.
In the present application, the term "comprising" as referred to herein means open or closed, unless otherwise specified. For example, the term "comprising" may mean that other components not listed may also be included, or that only listed components may be included.
The reactor of the present application can be used for performing various photochemical reactions, and in the present application, the reactor structure of the present application is mainly described by taking the reaction of difluoroethane F152a with chlorine gas, and the photo-chlorination reaction is performed to generate difluorochloroethane (HCFC-142 b), but the reactor of the present application can also be used for other various photochemical reactions, particularly exothermic photochemical reactions, and similar technical effects are obtained based on the reactor and the method of the present application as well. Non-limiting examples of such other photochemical reactions may include photo-halogenation (chlorination, bromination, etc.) reactions of various compounds such as linear hydrocarbons, branched hydrocarbons, aromatic hydrocarbons, heteroaromatic hydrocarbons, halogenated hydrocarbons, and the like.
Fig. 1 shows a photochemical reactor according to one embodiment of the present application, comprising, in order from bottom to top, a feed tower section 9, a light bank tower section 3, a spray tower section 2 and a condensation-foam removal tower section 1.
According to one embodiment of the present application, the feed tower section 9 includes a feed device therein, through which a raw material for the photochlorination reaction, for example, a mixed gas of difluoroethane F152a and chlorine is fed into the photochemical reactor. Non-limiting examples of the feeding means may include one or more of the following: distribution plates, distributors, nozzles, showerheads, etc. According to one embodiment of the present application, the feeding means is a distributor connected to the feeding pipe, the distributor being, for example, a disc-shaped structure having a plurality of openings or nozzles, so that the mixed gas of difluoroethane F152a as a reaction raw material and chlorine is distributed as uniformly as possible in the whole reaction system under the action of the distributor to promote improvement of reaction efficiency and smooth temperature control during the reaction. According to another embodiment of the present application, the structure and dimensions of the feed tower section 9 may be designed as desired, for example the feed tower section may have a cylindrical shape, the height (tower section length) of which may be 200-2000mm, for example 300-1500mm, or 400-1200mm, or 500-1000mm, or 600-800mm, or within the numerical range obtained by combining any two of the above-mentioned end values with each other; the inner diameter of the feed tower section can be 500-2000mm, alternatively 600-1800mm, alternatively 800-1600mm, alternatively 1000-1500mm, alternatively 1200-1400mm, or within the numerical range obtained by combining any two end values.
According to another embodiment of the present application, various devices, such as a raw material container, a heater, a condenser, a heat exchanger, a pressure gauge, a flow meter, a pump, etc., may be provided on the feed line of the feed device or upstream of the feed line, as desired. According to one embodiment of the present application, a valve or flow controller is provided on or upstream of the feed conduit of the feed device, which valve or flow controller may be temperature controlled, which is connected to a thermometer, thermocouple or other temperature sensing counter arranged in the reactor, which automatically controls the flow rate of the feed device input reaction raw material based on the temperature reading provided by the thermometer, thermocouple or other temperature sensing meter. For example, in one embodiment shown in fig. 3, a thermo valve 12 is provided in the feed line of the feed device. According to one embodiment of the present application, in case a sudden increase in the temperature inside the reactor is detected exceeding a certain threshold, the flow rate of the reaction raw material fed to the feeding means is automatically reduced using the thermo valve 12, even the feeding of the reaction raw material is temporarily stopped. For example, the threshold may be set at 100 ℃, or 95 ℃, or 90 ℃, or 85 ℃, or 80 ℃, or 75 ℃, or 70 ℃, or 65 ℃, or 60 ℃, or 55 ℃, or 50 ℃.
According to another embodiment of the present application, the photochemical reactor bottom has a cooling fluid outlet, e.g. the cooling fluid outlet may be arranged in the centre or at the periphery of the photochemical reactor bottom. For example, the bottom plate of the feed column section 9 may be the bottom of the photochemical reactor; or the bottom of the feed tower section 9 may be open and connected to a separate tower section or bottom plate.
According to one embodiment of the present application, two or more light string tower sections 3 and at least one spray tower section 2 are arranged above the feed tower section 9. According to one embodiment of the present application, the number of the lamp group tower sections 3 may be 2-16, for example 2-12, or 3-10, or 4-8, or 4-6, or the number of the lamp group tower sections 3 may be within a numerical range obtained by combining any two end values. According to one embodiment of the present application, the number of the spray tower sections 2 may be 1-6, for example, 2-5, or 2-4, or 2-3. Each of the spray tower sections is arranged above at least one lamp group tower section. According to some embodiments of the present application, the light bank tower sections 3 may be equally divided into groups, for example, equally divided into two, three, four or five groups, with one spray tower section 2 being provided over each group of light bank tower sections 3.
In the exemplary embodiment shown in fig. 1, the photochemical reactor comprises two lamp bank tower sections 3, which two lamp bank tower sections 3 are divided into two groups, each group comprising one lamp bank tower section 3, and one spray tower section 2 is arranged immediately above each group (i.e. each) of lamp bank tower sections 3.
In another exemplary embodiment shown in fig. 3, the photochemical reactor comprises six light bank tower sections 3, which six light bank tower sections 3 are divided into two groups, each group comprising three light bank tower sections 3, and one spray tower section 2 is arranged immediately above each group (i.e. every three) of light bank tower sections 3.
In various embodiments of the present application, any two tower sections may be connected by suitable sealing means and where the interior of the reactor is isolated from the environment outside the reactor, to avoid leakage at the connection between the tower sections. Examples of sealing portions described herein include flanges, sealing washers, bolts/nuts, hinges, dovetail components, and the like, as well as any combinations thereof.
According to one embodiment of the present application, each light string tower section is provided with at least one irradiation device, which is mounted outside the light string tower section and is not inserted inside the light string tower section. According to one embodiment of the application, a plurality of light source interfaces are provided on the side wall of the light bank tower section, and each irradiation device is mounted outside the light bank tower section via the light source interfaces and irradiates light into the photochemical reactor. For example, the light source interface may be of any desired suitable configuration, for example, a viewing port may be used, such as the viewing port of DN150-DN 300. An exemplary construction of the view port may be a construction in which a piece of glass is sandwiched between two steel annular cover plates, which may be secured to the side walls of the lamp bank tower sections by means of flanges, welding, riveting, screwing, hinging, etc. and ensure sealing, avoiding leakage of material inside the reactor. Other structures, such as brackets, bayonets, suction cups, bolts/nuts, bases, etc., may also be provided at each viewing aperture and/or at the outer wall around the viewing aperture as desired for mounting the irradiation device (lamp) to the light source interface. Fig. 2 shows an embodiment in which the view mirror opening is used as the light source interface 8 for the side wall of the tower section of the light bank.
Irradiation devices that may be used in the present application may include any lamps capable of providing radiation of the wavelength required for the photochemical reaction, for example, the emission wavelength of these lamps may be 350-500nm. Examples of such lamps include LED lamps, mercury lamps, halogen lamps, and the like. According to a preferred embodiment of the present application, the lighting devices used in the tower sections of the lamp set are LED lamps, which generate less heat than mercury lamps and halogen lamps during operation, which is more advantageous for overall temperature control and uniformity of the reaction within the reaction system. According to some embodiments of the present application, the irradiation device employs an LED spotlight having a power of 100-600W and a light emission angle of the spotlight between 45-90 deg..
According to one embodiment of the present application, the light emitting surface size of the irradiation device is equal to or slightly larger than the light transmitting opening size of the light source interface to which the irradiation device is mounted, or the former may be slightly smaller than the latter, preferably the former is equal to or slightly larger than the latter. By adopting the combination of the irradiation device and the light source interface, the irradiation device is arranged at the outer wall of the lamp bank tower section, the irradiation device is prevented from being inserted into the reactor, and illumination required by photocatalytic reaction can still be effectively provided for the inside of the reactor.
According to one embodiment of the present application, the light source interfaces 8 are arranged around the side wall of each light bank tower section 3 in a layered manner. For example, each tower section may be provided with 2-6 layers of light source interfaces, each layer of light source interfaces may be aligned or staggered with respect to adjacent layers, and each layer may be provided with 2-12 light source interfaces. According to some embodiments, two, three, four, five or six layers of light source interfaces may be provided in each tower section, such as in the exemplary embodiments shown in fig. 1 and 3, each tower section includes three layers of light source interfaces, respectively. According to one embodiment of the present application, there is a uniform spacing between the layers. According to another embodiment of the present application, the number of light source interfaces included in each layer may be 2-12, for example, two, three, four, five, six, seven, eight, nine, ten, eleven, or twelve. According to one embodiment of the present application, the light source interfaces are arranged in a layered manner around the side wall of each light bank tower section 3 in a symmetrical fashion, in other words, in each layer the central angle between any two adjacent light source interfaces 8 (the central angle between any two adjacent light source interfaces 8 in the cross section of the reactor in which the layer is located) may be identical, for example if each layer comprises two light source interfaces, the angle between them (central angle) is 180 °; if each layer comprises three light source interfaces, the included angle (central angle) between any two is 120 degrees; if each layer comprises four light source interfaces, the included angle (central angle) between any two is 90 degrees; if each layer comprises five light source interfaces, the included angle (central angle) between any two is 72 degrees; if each layer comprises six light source interfaces, the included angle (central angle) between any two is 60 degrees; if each layer comprises eight light source interfaces, the included angle (central angle) between any two is 45 degrees; if each layer comprises nine light source interfaces, the included angle (central angle) between any two is 40 degrees; and so on. According to one embodiment of the present application, each light string tower section may have a cylindrical shape, and its height (tower section length) may be 400-5000mm, for example 600-4000mm, or 800-3000mm, or 1000-2000mm, or 1200-1500mm, or within the numerical range obtained by combining any two of the above-mentioned end values with each other; the inner diameter of the feed tower section can be 500-2000mm, alternatively 600-1800mm, alternatively 800-1600mm, alternatively 1000-1500mm, alternatively 1200-1400mm, or within the numerical range obtained by combining any two end values.
According to one embodiment of the present application, a spray device, such as a nozzle, shower head, distribution plate, etc., is provided within each spray tower section. The cooling liquid is sprayed into the tower section below the cooling liquid through the spraying device, so that liquid drops of the cooling liquid are contacted with materials in the reactor in the falling process, at least part of reaction heat is absorbed by the cooling liquid, and then the cooling liquid absorbing the reaction heat descends to the bottom of the reactor and flows out from a cooling liquid outlet. According to one embodiment of the present application, each spray tower section may have a cylindrical shape, the height (tower section length) of which may be 100-2000mm, such as 200-1500mm, or 300-1000mm, or 400-800mm, or 500-600mm, or within the numerical range obtained by combining any two of the above endpoints with each other; the inner diameter of the spray tower section can be 500-2000mm, or 600-1800mm, or 800-1600mm, or 1000-1500mm, or 1200-1400mm, or within the numerical range obtained by combining any two end values.
According to one embodiment of the present application, the reactor of the present invention further comprises a coolant cooler 4, a coolant container 5, a coolant circulation pump 6 and a coolant elevation container 7, which are arranged outside the tower section. According to one embodiment of the present application, the coolant elevation container 7 is arranged at a position higher than all spray tower sections, for example, the bottom of the coolant elevation container 7 is higher than all spray tower sections 2. According to one embodiment of the present application, the coolant cooler 4 is arranged at a position of 100-3000mm, for example 500-2000mm, or 800-1200mm, below the reactor feed tower section 9. According to another embodiment of the present application, the cooling liquid container 5 is arranged at a position of 100-3000mm, for example 500-2000mm, or 800-1200mm below the cooler 4. According to another embodiment of the present application, the elevated tank 7 is arranged at a position 100-5000mm above the top of the reactor, for example at 500-4000mm, or at 1000-4000mm, or at 2000-4000 mm. According to another embodiment of the present application shown in fig. 1, the coolant outlet is in fluid communication with the coolant cooler 4, such that the coolant flowing out of the coolant outlet, carrying the heat of reaction, flows through the coolant cooler 4, where it is cooled. For example, in another embodiment shown in fig. 3, the cooler 4 is a water-cooled cooler 4, and heat exchange occurs between cooling water flowing through the cooler and cooling liquid, so as to recover waste heat carried by the cooling liquid.
According to another embodiment of the present application, the cooler 4 is in fluid communication with a coolant reservoir 5. In the embodiment shown in fig. 1 and 3, the cooling liquid flowing out of the cooler 4 is subsequently conveyed to a cooling liquid container 5 and stored there. The coolant container 5 is in direct or indirect fluid communication with the coolant elevation and the spray devices provided in each of the at least one spray tower section via a coolant circulation pump. According to one embodiment of the present application, the cooling liquid stored in the cooling liquid container 5 is transported to one or more spraying devices and/or cooling liquid high-level containers in a continuous or intermittent manner as required. According to one embodiment of the present application, one or more functional devices or means, such as valves, flow meters, thermometers, pressure gauges, etc., may be provided at the connecting piping between the coolant container 5 and the spray device and/or the coolant header. According to one embodiment of the present application, one or more valves or flow controllers are provided upstream of each spray device for controlling whether to begin spraying coolant into the reactor space below the spray device or for controlling the rate of spraying coolant into the reactor space below the spray device. According to one embodiment of the present application, the above-described valve or flow controller is temperature controlled, which is connected to a thermometer, thermocouple or other temperature sensing counter-word provided in the light fixture tower section below it, and is used to automatically control whether to start spraying coolant into the reactor space below the spray device or to automatically control the rate of spraying coolant into the reactor space below the spray device based on the temperature readings provided by the thermometer, thermocouple or other temperature sensing meter. For example, in one embodiment shown in fig. 3, a temperature-controlled valve 10 and 11 are each provided on the line upstream of the two showers.
According to one embodiment of the present application, the coolant container 5 is in fluid communication with the coolant header container 7 such that the coolant container 5 is capable of supplying coolant to the coolant header container. The cooling liquid is always stored in the cooling liquid high-level container 7, and is used for supplying cooling liquid to the reactor for spraying when the circulating pump fails and the cooling liquid container 5 cannot supply cooling liquid, so that the temperature flying site cannot occur in the reactor, and enough time is provided for staff and an automatic control system to automatically start the standby pump or stop. In addition, when the system detects that the temperature in the reactor is too high, it is optional to increase the output of the circulation pump in a manual or automated manner, to increase the coolant delivered from the coolant reservoir 5 to the spraying device, or alternatively to provide an additional supply of coolant from the coolant elevation reservoir 7 in a manual or automated manner. According to a preferred embodiment of the present application, the coolant liquid elevation vessel 7 stores therein the coolant liquid required for the normal operation of the reactor for 15-30 minutes.
According to one embodiment of the present application, the cooling fluid used in the present invention is free of water and is not hydrochloric acid. In particular, the cooling fluid of the present application is one or more chlorofluorocarbons having a boiling point higher than that of difluoromonochloroethane; more specifically, the cooling liquid used in the present application is a high-boiling substance having a boiling point higher than that of difluoromonochloroethane generated in the process of photochemically reacting difluoroethane with chlorine to synthesize difluoromonochloroethane, and is selected from at least one of the following: difluorodichloroethane, difluorotrichloroethane, difluorotetrachloroethane. By adopting the cooling liquid, water or other substances which can pollute the product are not introduced into the reaction system.
According to another embodiment of the present application, for example in the embodiment shown in fig. 1, a condensation-foam removal column section 1 is further provided at the top of the reactor above the uppermost spray column section 2, which condensation-foam removal column section 1 comprises a condenser, which may be a water cooler, and a foam remover, the product stream rising there being condensed by the condensation water flowing through the condenser, the condensation water and the rising product stream being able to flow in and out of the tubes in the condenser, respectively, heat exchange taking place via the tube walls, without direct contact between the two. The demister may be a conventional demister known in the art for removing entrained liquid droplets or droplets from the gas. The product stream treated in this section 1 may be sent to any operation downstream, for example, the desired difluorochloroethane product may be separated by distillation, the unreacted starting difluoroethane separated may be recycled back to the feed section, and the high-boiling by-products obtained by separation, such as difluorodichloroethane, difluorotrichloroethane, difluorotetrachloroethane, etc., may be supplied to the coolant vessel 5 as the coolant of the present invention or recovered for other uses.
Each tower section of the present application may be manufactured using suitable materials, such as steel, aluminum alloy, quartz glass, glass-ceramic materials, plastics, resins, corrosion resistant metals, steel lined plastics (e.g., steel lined polytetrafluoroethylene, steel lined polyethylene, steel lined enamel glass), etc., respectively, so long as it has sufficient mechanical strength, thermal shock resistance, and chemical corrosion resistance to effectively withstand the temperature change shock, chemical attack, and various conventional or accidental mechanical shocks experienced by the reactor during the photochemical reaction. According to one embodiment of the present application, each tower section may be made of polytetrafluoroethylene material, or may be made of other materials, with a polytetrafluoroethylene inner liner disposed on the inside.
According to another embodiment of the present application, one or more components or structures, such as material inlets, material outlets, valves, temperature sensors, temperature control devices, pressure sensors, pressure control devices, support structures, etc., may also be provided as desired on the interior, exterior surfaces, and interior and exterior of the light sources of the various tower sections of the reactor. According to another embodiment of the present application, the outer wall of each tower section is provided with a temperature measuring port through which a temperature sensor is inserted therein.
According to another embodiment of the present application, an air cooling or water cooling device may be optionally provided around each irradiation device L to further facilitate overall temperature control within the reaction system.
According to another embodiment of the present application, the reaction temperature is maintained throughout the reactor at a value ranging from 20 to 50 ℃, such as from 25 to 45 ℃, or from 30 to 40 ℃, or from 35 to 40 ℃, or a combination of any two of the foregoing endpoints; the reaction pressure is 0.05-0.08MPa, such as 0.06-0.07MPa, or the numerical range obtained by combining any two end values; the residence time of the reaction mass in the reactor is in the range of from 20 to 40 seconds, for example from 25 to 35 seconds, or from 30 to 35 seconds, or a combination of any two of the above endpoints; the temperature of the cooling liquid sprayed from the spraying device is 0-45 ℃, such as 5-40 ℃, or 10-35 ℃, or 15-30 ℃, or 20-25 ℃, or the numerical range obtained by combining any two end values.
According to one embodiment of the present application, a mixture of gaseous substances comprising chlorine and the raw material to be chlorinated (for example difluoromonochloroethane) is fed into the reactor from a feed column section at the bottom of the reactor, the reaction raw material mixture being gradually moved upwards in the reactor, the raw material to be chlorinated (for example difluoromonochloroethane) being subjected to a photochlorination reaction during the movement under irradiation by irradiation means in a lamp bank column section. Spraying cooling liquid from a spraying device in the at least one spraying tower section in an intermittent or continuous mode according to the temperature change condition in the reactor, wherein the sprayed cooling liquid is contacted with materials in the reactor and mutually transfers heat. And after the sprayed cooling liquid contacts with the materials in the reactor and obtains heat generated by the reaction, discharging the cooling liquid from a cooling liquid outlet at the bottom of the photochemical reactor, cooling the cooling liquid in a cooling liquid cooler, and then conveying the cooling liquid to a cooling liquid container, wherein the cooling liquid is conveyed from the cooling liquid container to a cooling liquid high-level container and/or a spraying device arranged in the at least one spraying tower section in a continuous or discontinuous mode by utilizing the cooling liquid circulating pump. The coolant cooler may be any conventional cooler, such as a water cooler using cooling water, in which the coolant and the cooling water are in heat exchange relationship through the pipe wall without direct contact. The reacted reaction mixture rises to the top of the reactor, where the product stream rising to this point is condensed at a condensate-demister column section and liquid droplets or droplets entrained in the gas are removed. The product stream is withdrawn from the top of the reactor and can be sent to any downstream operation, for example, the desired difluorochloroethane product can be separated by distillation, the separated unreacted starting difluoroethane is recycled back to the feed section, and the separated high-boiling by-products, such as difluorodichloroethane, difluorotrichloroethane, difluorotetrachloroethane, etc., are supplied as the cooling liquid of the present invention to the cooling liquid vessel 5 or recovered for other uses.
The reactor and method of the present invention may achieve one or more of the following advantages: 1) The conversion rate of raw materials is high, the selectivity of difluoro chloroethane is high, and the high-boiling product yield is small; 2) The consumption of liquid alkali is small; 3) By adopting the LED light source, excellent life is realized while maintaining high power, specifically, the light source power can be maintained above 200w, and the life is maintained above 3 years; 4) The whole system has high self-control rate, strong emergency and high safety, when the temperature of the reaction system exceeds 65-75 ℃ when overtemperature occurs, the spray cooling liquid can be gasified in a large amount, so that a large amount of reaction heat is absorbed, the temperature cannot be overtemperature, and the gasified gas can reduce the proportion of chlorine, so that the intensity of the reaction is reduced.
The present application is described below in terms of specific embodiments for the purpose of better understanding the contents of the present application. It should be understood that these embodiments are merely illustrative and not limiting. The reagents used in the examples were commercially available as usual unless otherwise indicated. The methods and conditions used in the examples are conventional methods and conditions unless otherwise specified.
Examples
In the following examples, the reaction performance of the photochlorination reactor for the synthesis of difluoromonochloroethane was examined in the reactor of the present application. The following embodiment is merely one specific example enumerated in the present application, but the technical features of the present application are not limited thereto. Any simple changes, equivalent substitutions or other modifications made on the basis of the present application to solve the substantially same technical problems, substantially the same technical effects, etc. are all covered by the protection scope of the present application.
Example 1
In this example 1, a photochemical reactor was constructed as shown in fig. 3, the reactor body comprising, in order from bottom to top, a feed tower section 9 lined with steel PTFE, three lower lamp bank tower sections 3, one lower spray tower section 2, three upper lamp bank tower sections 3, one upper spray tower section 2, and a condensation-foam removal tower section 1, the tower sections being sealed with flange and bolt connections. All tower sections are circular in cross section and 1000mm in inner diameter. The feed tower section 9 has a height of 500mm and is provided with a circular perforated distribution plate with a diameter of 1000mm. The height of each lamp bank tower section 3 is 1500mm, the side wall of each lamp bank tower section is provided with a sealed plug-in temperature measuring port and three layers of light source interfaces, the distance between the three layers is 400mm, each layer comprises four light source interfaces, and the light source interfaces in each layer are uniformly distributed on the side wall of the lamp bank tower section, as shown in fig. 2. The light source interface is DN300 sight glass mouth, the lamp L that uses is the LED shot-light of nominal power 100W, and its emission wavelength is 350-500nm, and the light emission angle is 90, and the shot-light is installed against the sight glass mouth, and the light irradiation is to tower section inside through the sight glass mouth from tower section outside. In the running process, the temperature sensors inserted into the three lower lamp bank tower sections 3 are in digital communication with the temperature control valve 11 at the upstream of the lower spray tower section 2, the temperature sensors inserted into the three upper lamp bank tower sections 3 are in digital communication with the temperature control valve 10 at the upstream of the upper spray tower section 2, and the flow rate of the cooling liquid materials flowing through the temperature control valves 10 and 11 is controlled according to the temperature in each lamp bank tower section 3 measured by the temperature sensors. The height of each spray tower section 2 is 500mm.
The reactor also comprises a coolant cooler 4, a coolant container 5, a coolant circulation pump 6 and a coolant elevation container 7. The coolant cooler 4 is arranged 2000mm below the reactor feed tower section 9, and the coolant container 5 has a volume of 3m 3 Is arranged 1000mm below the cooler 4, while the elevated tank 7 is of 3m volume 3 Is placed 4000mm above the top of the reactor. The cooler 4 is a tubular water cooler, and the cooling liquid flowing out from the bottom of the reactor exchanges heat with condensed water through the pipe wall.
In the reaction process, mixed gas of difluoroethane (F152 a) and chlorine is fed from a feed tower section at the bottom of the reactor, wherein the molar ratio of the difluoroethane to the chlorine in the mixed gas is 1:0.9, and the total flow rate of the mixed gas is 300kg/h. In the whole reaction process, the lamps of all the lamp group tower sections are turned on at intervals, and half of the light sources are turned on, so that the total power of all the light sources L in the experiment process is determined to be 4kW by using an ammeter because the actual power of each lamp is slightly in and out of the nominal power of each lamp.
In the whole reaction process, a mixed solution of difluorodichloroethane, difluorotrichloroethane and difluorotetrachloroethane is used as a cooling liquid, and the cooling liquid is a high-boiling component obtained by previous photochemical reaction separation of F152a and chlorine. Spraying cooling liquid with temperature of 40deg.C from the upper and lower spray tower sections, and controlling flow rate of cooling liquid sprayed from the lower spray tower section based on measured temperature at the lower lamp group tower section (at 15-20m 3 In the range of/h), the flow rate of the cooling liquid sprayed by the upper spray tower section is controlled based on the measured temperature at the upper lamp bank tower section (in the range of 5-10m 3 And/h), the higher the temperature, the faster the coolant spray rate, maintaining the temperature in the reactor at 45-50 ℃ throughout the reaction. After the reaction temperature was stabilized and continued for 1 hour, the composition of the reaction product flowing out from the top of the reactor was checked by gas chromatography, and the result was measuredThe method comprises the following steps: f152a 13%, F142b 85%, high boiling point component 1.5% and other components 0.5%.
Example 2:
this example 2 was conducted in the same reactor as in example 1, except that the total flow rate of the mixed gas of difluoroethane (F152 a) and chlorine gas fed into the reactor was 600kg/h, all the light sources were turned on, and the total power of all the light sources L during the experiment was 7kw using an ammeter. The flow rate of the cooling liquid sprayed by the lower spray tower section is controlled based on the measured temperature at the lower lamp group tower section (at 20-30m 3 In the range of/h), the flow rate of the cooling liquid sprayed by the upper spray tower section is controlled based on the measured temperature at the upper lamp bank tower section (at 10-15m 3 In the range of/h) such that the temperature in the reactor is maintained between 45 and 50 ℃.
After the reaction temperature was stabilized at 45-50℃for 1 hour, the composition of the reaction product flowing out from the top of the reactor was measured by gas chromatography, and the result was: f152a 11.3%, F142b 87.2%, high boiling point component 1.1% and other components 0.4%.
Example 3:
this example 3 was conducted in the same reactor as in example 1 in the same manner as in example 1 except that the total flow rate of the mixed gas of difluoroethane (F152 a) and chlorine gas fed into the reactor was 700kg/h, and the temperature of the spray liquid fed into both spray tower sections was 25 ℃. All light sources were turned on and the total power of all light sources L during the experiment was determined to be 7kw using an ammeter.
After the reaction was stabilized at 45-50 ℃ for 1 hour, the composition of the reaction product flowing out from the top of the reactor was measured by gas chromatography, and the measured result was: f152a 10.9%, F142b 87.9%, high boiling point component 0.8% and other components 0.4%.
Comparative example 1
In the same reactor as in example 1, this comparative example 1 was conducted in the same manner as in example 1, except that in this comparative example 1, all of the light source interfaces were removed, all of the light source structures were replaced with transparent quartz sleeves inserted into the reactor, and the inserted LED spot lamps were inserted into the transparent quartz sleeves inside the reactor. In comparative example 1, an aqueous hydrochloric acid solution having a concentration of 30 wt% was used as a cooling liquid, and an aqueous hydrochloric acid solution having a temperature of 40℃was sprayed into the reactor from the upper and lower spray tower sections, respectively.
After the reaction was stabilized at 45-50 ℃ for 1 hour, the composition of the reaction product flowing out from the top of the reactor was measured by gas chromatography, and the measured result was: f152a 12.9%, F142b 84.9%, high boiling point component 1.6% and other components 0.6%.
Comparative example 2
In comparative example 2, in the same reactor as in comparative example 1, the operation was performed in the same manner as in comparative example 1 except that the total flow rate of the mixed gas of difluoroethane (F152 a) and chlorine gas fed into the reactor was 600kg/h, and the temperature of the aqueous hydrochloric acid spray liquid fed into both spray tower sections was 45 ℃. The temperature in the reactor was maintained at 85-90 ℃ during the duration of the reaction.
After the temperature stabilization reaction was continued for 1 hour, the composition of the reaction product flowing out from the top of the reactor was measured by gas chromatography, and the measured result was: 23.6% of F152a, 72.5% of F142b, 2.8% of high boiling point component and 1.1% of other components.
The specific parameters and experimental results for examples 1-3 and comparative examples 1-2 are summarized in Table 1 below:
table 1: examples 1-3 and comparative examples 1-2 employed process parameters and experimental results
As can be seen from a comparison of the above inventive examples and comparative examples, the inventive examples achieve more excellent raw material conversion and target product selectivity even at higher throughput by employing a non-built-in light source and a specially selected cooling spray, and the temperature control within the reactor is extremely effective. In sharp contrast, in the two comparative examples, the built-in light source and the conventional hydrochloric acid cooling liquid are adopted, so that the raw material conversion rate and the selectivity of the target product are obviously deteriorated, and the dehydration operation is additionally required during the subsequent treatment of the product, thereby further improving the process complexity and the cost.
Comparative example 3
This comparative example 3 was conducted under the same process conditions as in example 1, but the difference was that in this comparative example 3, only one spray tower section 2 above the lamp group tower section 3 was used, and as a result, it was found that after half of the lamps were turned on in the same manner as in example 1, the temperature in the lower part of the reactor was continuously increased very quickly due to the exothermic heat of reaction, the upper spray was increased, the upper temperature was lowered, the lower temperature was excessively high, the upper temperature was excessively low in temperature distribution, the upper-lower temperature difference exceeded 20 ℃, and the lower temperature was still increased, and the stability and distribution of the temperature in the reactor could not be maintained, and the reaction had to be terminated. This comparative example 3 demonstrates that if only one spray tower section 2 design is used, a stable photochlorination reaction system cannot be achieved.
Claims (10)
1. A photochemical reactor comprising a feed tower section at the bottom, two or more light string tower sections above the feed tower section, and at least one spray tower section, each of the at least one spray tower section being disposed above at least one light string tower section, respectively;
the feeding tower sections comprise feeding devices, each lamp group tower section is provided with at least one irradiation device, and each spray tower section is internally provided with a spray device;
the bottom of the photochemical reactor is provided with a cooling liquid outlet;
the irradiation device is arranged outside the tower section of the lamp group and is not inserted into the tower section of the lamp group.
2. The photochemical reactor of claim 1, further comprising a coolant cooler, a coolant reservoir, a coolant circulation pump, and a coolant elevation reservoir, the coolant elevation reservoir being disposed above all of the spray tower sections, the coolant outlet, the coolant cooler, the coolant reservoir, the coolant circulation pump, the coolant elevation reservoir, and the spray device disposed within each of the at least one spray tower sections being in direct or indirect fluid communication.
3. The photochemical reactor of claim 1, wherein said irradiation means is an LED lamp having an emission wavelength of 350-500 nanometers.
4. The photochemical reactor according to claim 1, wherein said irradiation means is installed outside a tower section of the lamp set via a light source interface and irradiates light into the inside of the photochemical reactor,
the light source interfaces in each light source tower section are arranged in 2-6 layers around the periphery of the light source tower section, each layer is provided with 2-12 light source interfaces, and the circumferential angle between each light source interface in the same layer and the adjacent light source interface is 15-180 degrees.
5. The photochemical reactor of claim 1, wherein said photochemical reactor comprises at least two spray tower sections, wherein one spray tower section is disposed above an uppermost light bank tower section and the remaining spray tower sections are each disposed above any one of the light bank tower sections below said uppermost light bank tower section.
6. A method of performing a photochlorination reaction in a photochemical reactor according to any one of claims 1-5, comprising the steps of:
inputting gaseous substances containing chlorine and raw materials to be chlorinated into a reactor from a feeding tower section at the bottom of the reactor, carrying out photochlorination reaction on the raw materials to be chlorinated and the chlorine under the irradiation of an irradiation device in a lamp group tower section,
spraying cooling liquid from a spraying device in the at least one spraying tower section in a batch or continuous mode in the process of carrying out the photochlorination reaction, wherein the sprayed cooling liquid is contacted with materials in the reactor and mutually transfers heat.
7. The method of claim 6, wherein the photochlorination reaction is a photochlorination reaction of an alkane or haloalkane with chlorine, and the coolant is free of water.
8. The method of claim 7, wherein the photochlorination reaction is a reaction of difluoroethane with chlorine to produce difluoromonochloroethane;
the cooling fluid is one or more chlorofluorocarbons having a boiling point higher than that of difluorochloroethane.
9. The method of claim 6, wherein the sprayed coolant is discharged from a coolant outlet at the bottom of the photochemical reactor after contacting the material in the reactor and obtaining heat generated by the reaction, cooled in a coolant cooler, and then transferred to a coolant container,
and conveying the cooling liquid from the cooling liquid container to the cooling liquid high-level container and/or the spraying device arranged in the at least one spraying tower section in a continuous or discontinuous mode by utilizing the cooling liquid circulating pump.
10. The process of claim 6, wherein the reaction temperature in the reactor is 20 to 50 ℃, the reaction pressure is 0.05 to 0.08MPa, the reaction residence time is 20 to 40 seconds, and the temperature of the cooling liquid sprayed from the spraying device is 0 to 45 ℃.
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