Reaction product separation device and separation method of o-cresol device

Abstract

The invention discloses a device and a method for separating reaction products from an o-cresol device, which are characterized in that non-condensable gas, light components and heavy components of reaction products from a reaction unit are separated in a flash evaporation unit, methanol, anisole and part of water are separated from the light components through a methanol removal unit, anisole is separated from high-concentration anisole, methanol and water through an extraction unit, and the high-concentration anisole is separated from the methanol and the water through a flash evaporation unit. Carrying out phenol and water separation on a phenol and water mixture discharged from the bottom of the methanol removal tower in an azeotropic dehydration unit; and heavy components discharged from the flash evaporation unit are subjected to phenol recovery through a phenol recovery unit, and phenol-free mixed phenol is further separated into an o-cresol product and a 2, 6-xylenol product in an o-cresol separation unit. By adopting a method of combining rectification, azeotropic distillation and liquid-liquid extraction, the phenol-methanol alkyl reaction product can be efficiently separated, the byproduct anisole is effectively separated, the influence of the byproduct on the reaction selectivity is reduced, the mass fraction of the o-cresol product is greater than or equal to 99.5%, the discharge of phenol-containing wastewater is avoided through azeotropic distillation, and the production cost is reduced. The energy consumption and the cost are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of organic chemical industry, and in particular relates to a device and a method for separating reaction products of an o-cresol device. Background Art

[0002] Ortho-cresol is a colorless crystalline, aromatic combustible substance, slightly soluble in water, soluble in ethanol, ether, chloroform, etc. It is mainly used as a synthetic resin, and can also be used to make pesticide dimethyl tetrachloride herbicide, disinfectants in medicine, fragrances, chemical reagents and antioxidants. Ortho-cresol is used in synthetic resins, and the purity of ortho-cresol in chemical fields such as pesticides and medicines is required to be above 99.5%. Ortho-cresol reacts with formaldehyde to obtain cresol phenolic resin, which is further reacted with epichlorohydrin to obtain epoxy cresol phenolic resin (ECN). Cresol phenolic resin is mainly used as a curing agent for epoxy model compounds in electronic components, especially computer components. ECN is used as a transfer model compound in the electronics industry for integrated circuit chip packaging and plastic thin plates. ECN resin can also be used for functional powder coatings for pipe fittings and oil and gas extraction in oil fields. With the growth of demand for downstream chemical products of ortho-cresol, the demand for ortho-cresol is increasing year by year, and the market prospects are broad.

[0003] The production of o-cresol mainly adopts phenol alkylation technology. The existing equipment mainly produces o-cresol as a co-product or by-product while producing 2,6-dimethylphenol. o-cresol can also be separated from coal tar, but the purity can usually only reach about 96%, which cannot meet the needs of fine chemical production. The phenol-methanol alkylation method has the characteristics of continuity, low catalyst toxicity and corrosion, and is a typical green production process. It has become the main process for producing o-cresol and 2,6-dimethylphenol.

[0004] CN200910043076.1 discloses a catalyst for ortho-methylation of phenol and a preparation method thereof. O-methylphenol is prepared by gas-phase alkylation reaction of phenol and methanol using alkaline metal oxide as catalyst. The single-pass conversion rate of phenol can reach up to 48.8%, the selectivity of o-methylphenol can reach over 90%, and the selectivity of o-methylphenol+xylenol can reach over 99%.

[0005] CN202410431094.1 discloses an iron-based catalyst for phenol alkylation reaction and a preparation method thereof. By using the iron-based catalyst, the average phenol conversion rate is above 50%, the o-cresol selectivity is above 90%, the total product selectivity is above 98%, and there are few by-products.

[0006] Due to the existing catalyst system for preparing o-cresol in the phenol-methanol alkylation reaction, the phenol single-pass conversion rate is not high, and the existing production device is basically below 50%. A small amount of by-product anisole exists in the reaction product. Since phenol, anisole and water all form azeotropes, and the boiling points of the azeotropes differ by 6.2° C., the anisole component exists in the recycled phenol and the recycled methanol, and accumulates over a long period of time. The anisole concentration in the reaction feed is high, which reduces the selectivity of the reaction o-cresol, and reduces the product yield and the device load.

[0007] The paper "Process Technology for Synthesis of Ortho-Cresol by Gas-Phase Alkylation of Phenol-Methanol" in the 202302 issue of "Biochemical Engineering" points out that the five-tower conventional distillation process is used in actual projects. This process cannot solve the problem of difficult-to-treat phenol-containing wastewater discharge, making it difficult for sewage treatment plants to discharge wastewater in compliance with discharge standards, and at the same time, the energy consumption is relatively high.

[0008] Therefore, in view of the current characteristics of phenol-methanol gas-phase alkylation reaction, the problems existing in product separation, and the problem of solving the problem of the accumulation of a small amount of by-product anisole affecting the reaction selectivity, an effective method for separating the products of phenol and methanol alkylation reaction was proposed. Summary of the invention

[0009] The purpose of the present invention is to solve the defects of the existing ortho-cresol device reaction product separation technology and propose an ortho-cresol device reaction product separation device and separation method. The present invention proposes an ortho-cresol device reaction product separation method, in particular, a separation method combining ordinary distillation, azeotropic distillation and liquid-liquid extraction, which solves the problem that the existing conventional separation method cannot remove anisole and discharge phenol-containing wastewater, and increases the economic benefits of the device.

[0010] According to the separation method of the present invention, the reaction products from the reaction unit are first flashed to remove non-condensable gases, and the light components at the top of the flash tower are separated by distillation to obtain a methanol solution, anisole-methanol mixed solution, and a phenol aqueous solution; the anisole-methanol mixed solution is separated by water mixed extraction to obtain a methanol solution and anisole; the phenol aqueous solution is separated by azeotropic distillation to obtain water; the heavy components at the bottom of the flash tower are separated by a phenol recovery tower to obtain a cresol mixture, and the cresol mixture is further separated into an o-cresol product and a 2,6-xylenol product.

[0011] The technical solution of the present invention is as follows:

[0012] A reaction product separation device for an o-cresol device comprises a flash tower, a methanol removal tower, an azeotropic dehydration tower, a phenol recovery tower and an o-cresol distillation tower connected in series in a material flow direction; a condenser is arranged at the top of each tower, and the condenser is connected to a reflux tank; except for the flash tower, a reboiler is arranged at the bottom of each tower; a side line of the methanol removal tower is connected in sequence to an anisole extraction mixer and an anisole extraction separation tank; and the bottom of the water bag of the reflux tank at the top of the azeotropic dehydration tower is connected to the anisole extraction mixer.

[0013] The flash tower is a packed tower, the packing is a structured packing 352Y, and the packing height is 4 meters.

[0014] The demethanol tower adopts a packed tower, and the packing is a structured packing 352Y. The packing height of the distillation section and the stripping section is 4 meters respectively. The distillation section packing is divided into two sections, the upper section packing height is 1 meter, and the lower section packing height is 3 meters. The side line extraction position is the extraction bucket at the bottom of the upper section packing.

[0015] The phenol recovery tower adopts a packed tower, the packing is a structured packing 352Y, the height of the rectification section is 8 meters, and the height of the stripping section is 16 meters.

[0016] The o-cresol distillation tower adopts a packed tower, the packing is a structured packing 352Y, the height of the distillation section is 12 meters, and the height of the stripping section is 8 meters.

[0017] The condensers at the top of the phenol recovery tower and the o-cresol distillation tower are steam generators for generating 0.45MPaG steam, which are used as heat sources for the demethanol tower and the azeotropic dehydration tower reboilers; the heat sources of the phenol recovery tower reboilers and the o-cresol distillation tower reboilers are heat transfer oil, and the reboilers are all vertical thermosyphon reboilers.

[0018] A method for separating the reaction products of an o-cresol device comprises a flash unit, a methanol removal unit, an anisole extraction unit, an azeotropic dehydration unit, a phenol recovery unit and an o-cresol separation unit; the separation device is composed of a flash tower, a methanol removal tower, an azeotropic dehydration tower, a phenol recovery tower and an o-cresol rectification tower connected in series in a material flow direction, a condenser is arranged at the top of each tower, and a reflux tank is connected to the condenser, and a reboiler is arranged at the bottom of each tower except the flash tower; the side line of the methanol removal tower is connected to an anisole extraction mixer and an anisole extraction separation tank in sequence; the top of the azeotropic dehydration tower is refluxed The bottom of the tank water bag is connected to anisole extraction mixer; the reaction products from the reaction unit are first separated into non-condensable gas, light and heavy components in the flash unit, and the light component is separated into methanol, anisole and part of water in the methanol removal unit. Anisole is separated from high-concentration anisole, methanol and water in the extraction unit, and the phenol and water mixture coming out of the bottom of the methanol removal tower is separated into phenol and water in the azeotropic dehydration unit; the heavy component coming out of the flash unit is recovered by the phenol recovery unit, and the mixed phenol not containing phenol is further separated into o-cresol product and 2,6-xylenol product in the o-cresol separation unit.

[0019] The reaction products from the reaction unit are sent to the flash tower after heat exchange with the reaction feed heat exchanger, and a stream rich in methanol and water light components is produced from the top of the flash tower, and the non-condensable gas and light hydrocarbons at the top of the flash tower reflux tank are sent to the carrier gas compressor for pressurization; phenol, o-cresol, 2,6-xylenol and other recombinant streams are produced from the flash tower bottom; the light component stream is sent to the demethanol tower for separation, and the methanol-water solution stream produced at the top of the demethanol tower is sent to the reuse methanol tank, and the anisole with a high concentration produced by the side line of the demethanol tower is sent to the anisole extraction mixer, and is fully mixed with the water from the bottom of the water bag from the top reflux tank of the azeotropic dehydration tower. The anisole extraction separation tank is subjected to liquid-liquid separation after sufficient residence time, and the liquid bag stream at the bottom of the tank is sent to the storage tank as the anisole product, and the top stream is sent to the reuse methanol tank as the reuse methanol component. The phenol-containing aqueous solution extracted from the bottom of the alcohol tower is sent to the azeotropic dehydration tower for separation; the cyclohexane and water mixed stream is extracted from the top of the azeotropic dehydration tower and enters the reflux tank at the top of the azeotropic dehydration tower for oil-water separation, the oil phase is circulated back to the azeotropic dehydration tower, a part of the separated water is used as an extractant, and a part is sent to the sewage treatment plant; the mixed phenol stream extracted from the bottom of the azeotropic dehydration tower is sent to the phenol recovery tower together with the recombinant split stream from the bottom of the flash tower for separation, the phenol stream extracted from the top of the phenol recovery tower is sent to the phenol recovery tank as recycled phenol; the mixed stream of o-cresol and 2,6-xycresol is obtained in the bottom of the phenol recovery tower and sent to the o-cresol distillation tower for separation, the o-cresol stream is extracted from the o-cresol distillation tower and sent to the o-cresol storage tank as an o-cresol product; the 2,6-xycresol stream is obtained in the bottom of the o-cresol distillation tower and sent to the 2,6-xycresol storage tank as a 2,6-xycresol product.

[0020] The operating pressure of the flash tower, methanol removal tower, azeotropic distillation tower, phenol recovery tower and o-cresol distillation tower is 110-150 kPa absolute pressure; the anisole extraction and separation tank uses water as an extractant to extract and recover methanol; the azeotropic dehydration tower uses cyclohexane as an azeotropic agent; the phenol recovery tower and the o-cresol distillation tower top condenser are steam generators for generating 0.45 MPaG steam.

[0021] When the anisole extraction separator is put into use, the mass fraction of anisole in the feed of the de-methanol tower reaches more than 3%.

[0022] The azeotropic dehydration tower uses cyclohexane as the azeotropic agent; the cyclohexane circulation is added from the top of the tower, and the added amount is 7 to 8 times the mass of the water component feed of the azeotropic dehydration tower.

[0023] The anisole extraction unit, when the device is newly started, the reaction byproduct anisole output is low, and the content of reused methanol is low, and it is difficult to extract and separate it. According to the impact of the reaction feed anisole on the reaction in actual production, when the anisole mass fraction in the feed is less than 3.5%, the reaction selectivity is relatively small. According to the methanol-anisole-water triangular phase diagram, when the anisole concentration is low, more water is needed to extract, resulting in an increase in the water content of the reused methanol, exceeding the reaction feed water distribution requirement, and methanol and water need to be separated, resulting in an increase in device energy consumption. Combined with the actual production of phenol-methanol reaction feed ratio, after the device runs for a period of time, when the de-methanol tower feed anisole mass fraction reaches 3%, according to the anisole liquid phase distribution in the de-methanol tower, a high-concentration anisole-methanol-water mixture is extracted from the side of the tower, and the mixture is cooled and mixed with water and then liquid-liquid separation is performed to reach the anisole separation requirement, and the anisole concentration in the reused methanol is maintained to be stable, and no longer grows, so as to avoid excessive accumulation of anisole and discharge a large amount of methanol to cause economic losses.

[0024] The anisole extraction and separation tank uses water as the extractant, the extraction liquid mixer is a pipeline mixer SV type, and the extraction water flow rate is 1 to 1.5 times the side line extraction flow rate.

[0025] The technical solution of the present invention has the following beneficial effects:

[0026] 1) The present invention proposes a method for separating the reaction products of an o-cresol device. According to the composition distribution of the reaction products, the separation order is reasonably set. The mass fraction of the o-cresol product is ≥99.5%, which meets the requirements of downstream products for the o-cresol raw material. The process flow is short, the heat source is reasonably used, and the designed energy consumption is low.

[0027] 2) According to the relative volatility of light and heavy components separated in each tower, select the appropriate packing height, comprehensively consider the equipment investment and operating costs, and use process simulation software to design the optimal parameters.

[0028] 3) The present invention uses an anisole extraction process to extract an appropriate amount of anisole from an anisole-methanol mixture of a certain concentration, thereby solving the problem of anisole continuously accumulating in the reaction system, avoiding the reduction of reaction selectivity, the decrease in production capacity, and the economic losses caused by the large-scale reuse of methanol.

[0029] 4) The present invention solves the problem of phenol-containing wastewater discharge in conventional separation processes by azeotropic distillation of cyclohexane and water, and avoids the difficulty in treating phenol-containing wastewater discharge, which causes the sewage treatment plant to have difficulty in meeting discharge standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0031] Figure 1 A schematic diagram of a reaction product separation device for an o-cresol device provided by the present invention is shown.

[0032] Description of reference numerals:

[0033] 101-flash tower, 102-flash tower condenser, 103-flash tower reflux tank, 104-de-methanol tower, 105-de-methanol tower reboiler, 106-de-methanol tower condenser, 107-de-methanol tower reflux tank, 108-de-methanol tower side line cooler, 109-anisole extraction mixer, 110-anisole extraction separation tank, 111-azeotropic dehydration tower, 112-azeotropic dehydration tower reboiler, 113-azeotropic dehydration tower condenser, 114-azeotropic dehydration tower Reflux tank, 115-phenol recovery tower, 116-phenol recovery tower reboiler, 117-phenol recovery tower steam generator, 118-phenol recovery tower reflux tank, 119-o-cresol distillation tower, 120-o-cresol distillation tower reboiler, 121-o-cresol distillation tower steam generator, 122-o-cresol distillation tower reflux tank, 123-reaction feed preheater, 124-o-cresol hot water heat exchanger, 125-o-cresol cooler, 126-2,6-xylenol cooler. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0035] It should be noted that when an element is considered to be "set on" another element, it may be directly set or connected to another element or there may be a centered element at the same time. The terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification are only for describing specific implementation purposes and are not intended to limit the present invention.

[0037] Example 1

[0038] According to a method for separating reaction products of an o-cresol device of the present invention, the reaction products from the reaction part are first flashed to remove light hydrocarbons and non-condensable gases, and the light components at the top of the flash tower are separated by distillation to obtain a methanol solution, anisole-methanol mixed solution, and a phenol aqueous solution; the anisole-methanol mixed solution is separated by water mixed extraction to obtain a methanol solution and anisole; the phenol aqueous solution is separated by azeotropic distillation to obtain water; the heavy components at the bottom of the flash tower are separated by a phenol recovery tower to obtain a cresol mixture, and the cresol mixture is further separated into an o-cresol product and a 2,6-xylenol product.

[0039] The process mainly includes the following units: flash evaporation unit, methanol removal unit, anisole extraction unit, azeotropic dehydration unit, phenol recovery unit, and o-cresol separation unit. The above units will be described below in conjunction with the accompanying drawings.

[0040] The reaction product from the reaction part is fed from the bottom of the flash tower 101 after heat exchange with the reaction feed heat exchanger. After the top steam is condensed by the flash tower condenser 102, the condensate enters the flash tower reflux tank 103 for gas-liquid separation. Part of the liquid phase is used as reflux, and the other part is extracted from the reflux tank as a light component. The operating pressure of the tower is 140KPa. The main reason is that the feed temperature of the flash tower is 170-180°C. The components of the stream extracted from the top of the tower are non-condensable gas, methanol, water anisole and light components of mixed phenols mainly composed of phenol. The gas phase is sent to the reaction carrier gas booster for pressure, and the liquid phase is sent to the demethanol tower 104 for separation. The main components of the stream from the bottom of the flash tower 101 are phenol, o-cresol, and 2,6-dimethylphenol, which are sent to the phenol recovery tower 115 for separation.

[0041] The liquid phase stream from the top of the flash tower is fed from the middle of the de-methanol tower 104, and after sufficient vapor-liquid heat and mass transfer, light and heavy separation is achieved. After the top steam is condensed by the de-methanol tower condenser 106, it enters the de-methanol tower reflux tank 107, a part of it is refluxed, and the rest is extracted as recycled methanol, wherein the methanol content is about 78.8%, and the anisole content is less than 3%. The distillation section packing is 2 sections, the upper section packing height is 1 meter, the lower section packing height is 3 meters, and the side line extraction position is the upper section packing bottom extraction bucket extraction. When the mass fraction of anisole in the de-methanol tower feed reaches 3%, the high-concentration mixed solution of anisole is extracted and sent to the anisole extraction mixer 109 after being cooled by the de-methanol tower side line cooler 108. The tower bottom temperature is 112-115°C, and the tower operating pressure is 120KPa. A demethanol tower reboiler 105 is provided in the tower bottom, and the heat source of the reboiler is 0.45MPaG steam. The mixed phenol-water mixture produced from the tower bottom is sent to the azeotropic dehydration tower 111 for dehydration.

[0042] The mixed liquid from the sideline cooler 108 of the methanol removal tower is mixed with the water from the water bag of the azeotropic dehydration tower reflux tank 114 in the anisole extraction mixer 109. After mixing, the stream enters the anisole extraction separation tank 110 for static separation. The methanol solution at the top of the tank is sent to the reuse methanol tank, and the anisole stream extracted from the liquid bag at the bottom of the tank is sent to the anisole storage tank as an anisole product. The anisole extraction separation tank is operated at normal pressure, the operating temperature is 40°C, and the extraction water flow rate is 1 to 1.5 times the sideline extraction flow rate.

[0043] After the mixed phenol-water mixture enters the azeotropic dehydration tower 111, water and cyclohexane are azeotropic in the tower. After sufficient gas-liquid heat and mass transfer, water and phenol are separated. The top steam is condensed by the azeotropic dehydration tower condenser 112 and enters the azeotropic dehydration tower reflux tank 114 for oil-water separation. The oil phase is circulated back to the azeotropic dehydration tower 111. A part of the separated water is used as an extractant, and a part is sent to the sewage treatment plant. The azeotropic agent cyclohexane enters the tower from the top of the tower, and the amount added is 7 to 8 times the mass of the water component feed of the azeotropic dehydration tower 111. The tower bottom temperature is 95°C, and the tower operating pressure is 120KPa. The tower bottom is equipped with an azeotropic dehydration tower reboiler 112, and the heat source of the reboiler is 0.45MPaG steam. The mixed phenol stream produced from the tower bottom is sent to the phenol recovery tower 115 together with the recombined split stream of the flash tower 101 kettle.

[0044] After the stream from the flash tower 101 and the stream from the azeotropic dehydration tower 111 are mixed, they are separated in the phenol recovery tower 115. The top steam is condensed by the phenol recovery tower steam generator 117 and enters the phenol recovery tower reflux tank 118. Part of it is refluxed and the rest is extracted. The extracted phenol material is sent to the reaction feed preheater 123 to preheat the raw materials and then sent to the phenol recycling tank. The cooling medium of the recovery tower steam generator 117 is deoxygenated water, which is used to generate 0.45MPaG steam. The tower bottom temperature is 200-210℃, and the tower operating pressure is 120KPa. The tower bottom is equipped with a phenol recovery tower reboiler 116, and the heat source of the reboiler is from the system heat transfer oil. The o-cresol and 2,6-xylenol streams extracted from the tower bottom are sent to the o-cresol distillation tower 119.

[0045] After the o-cresol and 2,6-xylenol streams enter the o-cresol distillation tower 119, after sufficient gas-liquid heat and mass transfer in the tower, o-cresol and 2,6-xylenol are separated. The top steam is condensed by the o-cresol distillation tower steam generator 121, and then enters the o-cresol distillation tower reflux tank 122, where part of it is refluxed and the rest is extracted. The extracted o-cresol material is sent to the o-cresol hot water heat exchanger 124 to heat hot water, and then cooled by the o-cresol cooler 125 and sent to the o-cresol product storage tank. The cooling medium of the o-cresol distillation tower steam generator 121 is deoxygenated water, which is used to generate 0.45MPaG steam. The tower bottom temperature is 220-230℃, and the operating pressure of the tower is 120KPa. The tower bottom is provided with an o-cresol distillation tower reboiler 120, the heat source of the reboiler is the heat transfer oil from the system, and the 2,6-xymethylphenol produced from the tower bottom is cooled by a 2,6-xymethylphenol cooler 126 and then sent to a 2,6-xymethylphenol product storage tank.

[0046] In order to better illustrate the technical superiority of the present invention, a comparison is made with the actual project pointed out in the paper "Process Technology for Synthesis of Ortho-Cresol by Gas Phase Alkylation of Phenol-Methanol" in "Biochemical Engineering" Issue 202302, Example 1.

[0047] The process shown in Comparative Example 1 is a 16,000 tons / year o-cresol device, and its process distillation part adopts a five-tower process, namely a flash tower, a dehydration tower, a methanol removal tower, a phenol removal tower and an o-cresol tower. The reaction product first enters the flash tower for gas-liquid separation, and the liquid phase at the bottom of the flash tower is pressurized by the flash tower discharge pump and sent to the dehydration tower for distillation. The liquid phase at the bottom of the dehydration tower is pressurized by the dehydration tower discharge pump and sent to the phenol removal tower feed tank. The phenol removal tower feed pump sends the material in the phenol removal tower feed tank to the phenol removal tower for distillation. The product at the bottom of the phenol removal tower is pressurized by the dephenol removal tower discharge pump and sent to the o-cresol tower feed tank. The o-cresol tower feed pump sends the material in the o-cresol tower feed tank to the o-cresol tower for distillation. The o-cresol vapor produced from the top of the o-cresol tower is condensed by the o-cresol tower top separation tank, the feed-o-cresol heat exchanger, and the o-cresol cooler, and then enters the o-cresol tank as a finished product, which is pumped to the tank area with the o-cresol finished product. The o-cresol tower reboiler in the o-cresol tower kettle uses heat transfer oil as a heat source, and a side line is opened at the top of the tower bottom to produce a mixed 2,6-xylenol product, which is boosted by the o-cresol tower discharge pump and cooled to 80°C by the 2,6-xylenol cooler, and then sent to the 2,6-xylenol tank, and then pumped to the tank area with the 2,6-xylenol finished product.

[0048] After the 16,000 tons / year o-cresol device is implemented by adopting the technical solution of the present invention, the operating parameters are compared with those of comparative example 1 as shown in Table 1, and the energy consumption is compared as shown in Table 2.

[0049] The process shown in Comparative Example 1 results in 60 kg / h of methanol being discharged due to the accumulation of anisole, which needs to be treated by related enterprises. The technology of the present invention discharges 4 kg / h of anisole, which can be sold as a gasoline blending component; the selectivity of the alkylation reaction is reduced to 80% due to the high concentration of anisole in the recycled methanol, the output of o-cresol is reduced by 200 kg / h, and the output of xylenol is increased by 200 kg / h.

[0050] The process shown in Comparative Example 1 discharges 500kg / h of phenol-containing wastewater with a phenol concentration of 5000ppm, which requires electrochemical catalytic oxidation pretreatment before being discharged to the park sewage treatment plant. The technology of the present invention discharges oily wastewater that can be directly discharged to the park sewage treatment plant after passing through a grease trap.

[0051] Table 1 Comparison of operating parameters between the technology of the present invention and comparative example 1

[0052]

[0053]

[0054] Table 2 Comparison of energy consumption per ton of cresol product between the technology of the present invention and comparative example 1

[0055]

[0056] As shown in Tables 1 and 2, after the implementation of the technology of the present invention, the operating parameters of the tower are optimized, and the utility consumption is significantly reduced relative to that of Comparative Example 1. According to the energy consumption calculation of GB / T50441-2016, the energy consumption per unit of cresol product is reduced by 40.09 kg standard oil. The increased production cost of Example 1 compared with the technology of the present invention is shown in Table 3.

[0057] Table 3 Example 1 increases production costs compared with the technology of the present invention

[0058]

[0059] The embodiments described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have all been recorded in the claims.

Claims

1. An o-cresol device reaction product separation device, which is composed of a flash tower, a methanol removal tower, an azeotropic dehydration tower, a phenol recovery tower and an o-cresol distillation tower connected in series with a material flow direction; a condenser is provided at the top of each tower, and the condenser is connected with a reflux tank. Except for the flash tower, a reboiler is provided at the bottom of each tower; a side line of the methanol removal tower is connected in sequence to an anisole extraction mixer and an anisole extraction separation tank; and the bottom of the reflux tank water bag at the top of the azeotropic dehydration tower is connected to the anisole extraction mixer.

2. The o-cresol device reaction product separation device according to claim 1, characterized in that The flash tower is a packed tower, the packing is a structured packing 352Y, and the packing height is 4 meters.

3. The o-cresol device reaction product separation device according to claim 1, characterized in that The demethanol tower adopts a packed tower, and the packing is a structured packing 352Y. The packing height of the distillation section and the stripping section is 4 meters respectively. The distillation section packing is divided into two sections, the upper section packing height is 1 meter, and the lower section packing height is 3 meters. The side line extraction position is the extraction bucket at the bottom of the upper section packing.

4. The o-cresol device reaction product separation device according to claim 1, characterized in that The phenol recovery tower adopts a packed tower, the packing is a structured packing 352Y, the height of the rectification section is 8 meters, and the height of the stripping section is 16 meters.

5. The o-cresol device reaction product separation device according to claim 1, characterized in that The o-cresol distillation tower adopts a packed tower, the packing is a structured packing 352Y, the height of the distillation section is 12 meters, and the height of the stripping section is 8 meters.

6. The o-cresol device reaction product separation device according to claim 1, characterized in that The condensers at the top of the phenol recovery tower and the o-cresol distillation tower are steam generators for generating 0.45 MPaG steam, which are used as heat sources for the reboilers of the methanol removal tower and the azeotropic dehydration tower.

7. The o-cresol device reaction product separation device according to claim 1, characterized in that The heat sources of the phenol recovery tower reboiler and the o-cresol distillation tower reboiler are heat transfer oil, and the reboilers are both vertical thermosyphon reboilers.

8. A method for separating the reaction products of an o-cresol device, comprising a flash unit, a methanol removal unit, an anisole extraction unit, an azeotropic dehydration unit, a phenol recovery unit, and an o-cresol separation unit; the separation device is composed of a flash tower, a methanol removal tower, an azeotropic dehydration tower, a phenol recovery tower, and an o-cresol rectification tower connected in series in a material flow direction, each tower is provided with a condenser at the top, and the condenser is connected to a reflux tank, and each tower except the flash tower is provided with a reboiler at the bottom; the methanol removal tower side line is connected in sequence to an anisole extraction mixer and an anisole extraction separation tank; the azeotropic dehydration tower top return The bottom of the flow tank water bag is connected to anisole extraction mixer; the reaction products from the reaction unit are first separated into non-condensable gas, light and heavy components in the flash unit, and the light component is separated into methanol, anisole and part of water in the methanol removal unit. The high-concentration anisole, methanol and water are separated into anisole through the extraction unit, and the phenol and water mixture coming out of the bottom of the methanol removal tower is separated into phenol and water in the azeotropic dehydration unit; the heavy component coming out of the flash unit is recovered by the phenol recovery unit, and the mixed phenol without phenol is further separated into o-cresol product and 2,6-xylenol product in the o-cresol separation unit.

9. The method for separating the reaction product of the o-cresol device according to claim 8, characterized in that The reaction products from the reaction unit are sent to the flash tower after heat exchange with the reaction feed heat exchanger, and a stream rich in methanol and water light components is produced from the top of the flash tower, and the non-condensable gas and light hydrocarbons at the top of the flash tower reflux tank are sent to the carrier gas compressor for pressurization; phenol, o-cresol, 2,6-xylenol and other recombinant streams are produced from the flash tower bottom; the light component stream is sent to the demethanol tower for separation, and the methanol-water solution stream produced at the top of the demethanol tower is sent to the reuse methanol tank, and the anisole with a high concentration produced by the side line of the demethanol tower is sent to the anisole extraction mixer, and is fully mixed with the water from the bottom of the water bag from the top reflux tank of the azeotropic dehydration tower. The anisole extraction separation tank is subjected to liquid-liquid separation after sufficient residence time, and the liquid bag stream at the bottom of the tank is sent to the storage tank as the anisole product, and the top stream is sent to the reuse methanol tank as the reuse methanol component. The phenol-containing aqueous solution extracted from the bottom of the alcohol tower is sent to the azeotropic dehydration tower for separation; the cyclohexane and water mixed stream is extracted from the top of the azeotropic dehydration tower and enters the reflux tank at the top of the azeotropic dehydration tower for oil-water separation, the oil phase is circulated back to the azeotropic dehydration tower, a part of the separated water is used as an extractant, and a part is sent to the sewage treatment plant; the mixed phenol stream extracted from the bottom of the azeotropic dehydration tower is sent to the phenol recovery tower together with the recombinant split stream from the bottom of the flash tower for separation, the phenol stream extracted from the top of the phenol recovery tower is sent to the phenol recovery tank as recycled phenol; the mixed stream of o-cresol and 2,6-xycresol is obtained in the bottom of the phenol recovery tower and sent to the o-cresol distillation tower for separation, the o-cresol stream is extracted from the o-cresol distillation tower and sent to the o-cresol storage tank as an o-cresol product; the 2,6-xycresol stream is obtained in the bottom of the o-cresol distillation tower and sent to the 2,6-xycresol storage tank as a 2,6-xycresol product.

10. The method for separating the reaction product of o-cresol device according to claim 8, characterized in that The operating pressure of the flash tower, methanol removal tower, azeotropic distillation tower, phenol recovery tower and o-cresol distillation tower is 110-150 kPa absolute pressure; the anisole extraction and separation tank uses water as an extractant to extract and recover methanol; the azeotropic dehydration tower uses cyclohexane as an azeotropic agent; the top condensers of the phenol recovery tower and the o-cresol distillation tower are steam generators for generating 0.45 MPaG steam; when the anisole extraction and separation device is put into use, the mass fraction of anisole in the feed of the methanol removal tower reaches more than 3%; the cyclohexane circulation is added from the top of the first tower plate, and the added amount is 7-8 times the mass of the water component feed of the azeotropic dehydration tower.

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