Reaction product separation device of o-cresol device

Abstract

The utility model discloses a reaction product separation device of an o-cresol device. The reaction product separation device consists of a flash tower, a methanol removal tower, an azeotropic dehydration tower, a phenol recovery tower and an o-cresol rectifying tower which are connected in series in a material flow direction, a condenser is arranged at the upper part of each tower and is connected with a reflux tank, and a reboiler is arranged at the lower part of each tower except the flash tower; the side line of the methanol removal tower is sequentially connected with an anisole extraction mixer and an anisole extraction separation tank; and the bottom of the azeotropic dehydration tower top reflux tank water bag is connected with an anisole extraction mixer. According to reaction products from a reaction unit, separation of phenol-methanol alkyl reaction products can be efficiently realized by using a separation device and adopting a method of combining rectification, azeotropic distillation and liquid-liquid extraction, a byproduct anisole is effectively separated, the influence of the byproduct on reaction selectivity is reduced, the mass fraction of an o-cresol product is greater than or equal to 99.5%, and the yield of the o-cresol product is greater than or equal to 99%. Through azeotropic distillation, phenol-containing wastewater discharge is avoided, the phenol recovery rate is improved, and energy consumption and cost are reduced.

Description

Technical Field

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

[0002] o-Cresol is a colorless, crystalline, aromatic, flammable substance. It is slightly soluble in water, but soluble in ethanol, ether, chloroform, and other solvents. It is primarily used in synthetic resins and can also be used to make the pesticide dimethyltetrachloride, pharmaceutical disinfectants, fragrances, chemical reagents, and antioxidants. For use in synthetic resins, the purity of o-Cresol in chemical industries, such as pesticides and pharmaceuticals, must be above 99.5%. o-Cresol reacts with formaldehyde to produce cresol novolac resin, which is further reacted with epichlorohydrin to produce epoxy cresol novolac resin (ECN). Cresol novolac resin is primarily used as a curing agent for epoxy model compounds in electronic components, particularly computer components. ECN is used in the electronics industry as a transfer model compound for integrated circuit chip packaging and plastic sheets. ECN resins are also used in functional powder coatings for pipe fittings and in oil and gas production. With the growing demand for o-Cresol's downstream chemical products, the demand for o-Cresol is increasing annually, presenting a promising market prospect.

[0003] The production of o-cresol primarily utilizes phenol alkylation technology. Existing plants primarily produce o-cresol as a co-product or by-product alongside 2,6-xylenol. While o-cresol can also be isolated from coal tar, its purity typically only reaches around 96%, insufficient for fine chemical production. The phenol-methanol alkylation process, characterized by its continuity and low catalyst toxicity and corrosion, is a typical green production process and has become the primary process for producing o-cresol and 2,6-xylenol.

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

[0005] CN202410431094.1 discloses an iron-based catalyst for phenol alkylation reaction and its preparation method. 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 the preparation of o-cresol in the phenol-methanol alkylation reaction, the single-pass conversion rate of phenol is not high, and the existing production equipment is basically below 50%. A small amount of by-product anisole is present in the reaction product. Since phenol, anisole and water all form azeotropes with a boiling point difference of 6.2°C, the anisole component exists in the recycled phenol and recycled methanol, accumulating over a long period of time. The anisole concentration in the reaction feed is high, which reduces the selectivity of the reaction o-cresol, the product yield and the equipment load.

[0007] The paper "Process Technology for Synthesis of o-Cresol by Gas-Phase Alkylation of Phenol and 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, based on the current characteristics of the 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 the phenol and methanol alkylation reaction was proposed. Summary of the Invention

[0009] The present invention addresses the shortcomings of existing technologies for separating reaction products from o-cresol plants and proposes an apparatus and method for separating reaction products from o-cresol plants. The present invention provides a method for separating reaction products from o-cresol plants, particularly a separation method that combines conventional distillation, azeotropic distillation, and liquid-liquid extraction. This method addresses the inability of existing conventional separation methods to remove anisole and discharge phenol-containing wastewater, thereby increasing 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 mixed and extracted with water to separate the 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 solutions of the present invention are as follows:

[0012] A device for separating reaction products of 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 provided at the top of each tower, which is connected to a reflux tank; and a reboiler is provided at the bottom of each tower except the flash tower; a side line of the methanol removal tower is sequentially connected 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 structured packing 352Y, and the packing height is 4 meters.

[0014] The demethanol tower adopts a packed tower, and the packing is 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 structured packing 352Y, the height of the distillation 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 0.45 MPaG steam, which serves as a heat source for the reboilers of the methanol removal tower and the azeotropic dehydration tower; the heat sources of the reboilers of the phenol recovery tower and the o-cresol distillation tower are thermal oils, 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 comprises 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 provided at the top of each tower, and the condenser is connected to a reflux tank; and a reboiler is provided at the bottom of each tower except the flash tower; a side line of the methanol removal tower is sequentially connected to an anisole extraction mixer and an anisole extraction separation tank; a reflux tank is provided at the top of the azeotropic dehydration tower; and a condenser is provided at the bottom of each tower except the flash tower. The bottom of the water bag in the tank is connected to an 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 de-methanol 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 de-methanol tower is separated into phenol and water in the azeotropic dehydration unit; the heavy component coming out of the flash unit is recovered into phenol in the phenol recovery unit, and the mixed phenol without phenol is further separated into o-cresol product and 2,6-dimethylphenol 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 methanol-rich, water-rich light component stream 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 booster 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. 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 of the azeotropic dehydration tower top reflux tank and then sent to the anisole extraction separation tank. The anisole extraction separation tank is subjected to liquid-liquid separation after sufficient residence time. The bottom liquid bag stream 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 produced from the kettle is sent to the azeotropic dehydration tower for separation; a mixed stream of cyclohexane and water is produced 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, and the oil phase is circulated back to the azeotropic dehydration tower, and 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 produced from the azeotropic dehydration tower kettle is sent together with the recombined split stream from the flash tower kettle to the phenol recovery tower for separation, and the phenol stream produced from the top of the phenol recovery tower is sent to the phenol recovery tank as recycled phenol; the phenol recovery tower kettle obtains a mixed stream of o-cresol and 2,6-xylenol, which is sent to the o-cresol distillation tower for separation, and the o-cresol stream is produced in the o-cresol distillation tower and sent to the o-cresol storage tank as the o-cresol product; the o-cresol distillation tower kettle obtains 2,6-xylenol stream and sends it to the 2,6-xylenol storage tank as the 2,6-xylenol 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 top condensers of the phenol recovery tower and the o-cresol distillation tower 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 demethanol tower reaches more than 3%.

[0022] The azeotropic dehydration tower uses cyclohexane as an azeotropic agent; the cyclohexane is circulated and 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] Described anisole extraction unit, when device is newly started, byproduct anisole output is low, and in reuse methanol content, it is lower, and is difficult to extract and separate, and according to the impact of reaction feed anisole on reaction in actual production, when anisole mass fraction in feed is less than 3.5%, reaction selectivity is affected relatively small. According to methanol-anisole-water triangular phase diagram, when anisole concentration is low, more water is needed to extract, causing reuse methanol water content to increase, exceeding reaction feed water distribution requirement, need to carry out methanol and water separation, causing device energy consumption to increase. In conjunction with actual production phenol-methanol reaction feed ratio, after device operation for a period of time, when decarbinolating tower feed anisole mass fraction reaches 3%, according to anisole liquid phase distribution situation in decarbinolating tower, high concentration anisole-methanol-water mixture is extracted from the side of tower, mixture carries out liquid-liquid separation after cooling and mixing with water, reaches anisole separation requirement, maintains anisole concentration stability in reuse methanol, no longer grows, avoids anisole accumulation too much, discharges a large amount of methanol and causes economic loss.

[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 unit. This method rationally sets the separation sequence based on the composition distribution of the reaction products. The o-cresol product mass fraction is ≥99.5%, meeting the o-cresol raw material requirements of downstream products. The method has a short process flow, rationally utilizes heat sources, and has low designed energy consumption.

[0027] 2) Select the appropriate packing height based on the relative volatility of the light and heavy components separated in each tower, comprehensively consider 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 continuous accumulation of anisole in the reaction system, avoiding the reduction of reaction selectivity, the decrease in production capacity, and the economic losses caused by the large amount of recycled methanol discharged.

[0029] 4) The present invention solves the problem of phenol-containing wastewater discharge in conventional separation processes by azeotropic distillation of cyclohexane and water, avoiding the difficulty in treating phenol-containing wastewater discharge, which makes it difficult for sewage treatment plants to meet 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 with reference to 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-Demethanol tower, 105-Demethanol tower reboiler, 106-Demethanol tower condenser, 107-Demethanol tower reflux tank, 108-Demethanol tower side 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] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive disclosure of the present invention.

[0035] It should be noted that when an element is considered to be "disposed on" another element, it may be directly disposed on or connected to the other element or there may be a central 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 to indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying 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 direction, be constructed and operate in a specific direction.

[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 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] The reaction product separation device of the o-cresol unit 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 in the material flow direction; a condenser is provided at the top of each tower, and the condenser is connected to a reflux tank. Except for the flash tower, a reboiler is provided at the bottom of each tower; the side line of the methanol removal tower is connected in sequence to an anisole extraction mixer and an anisole extraction separation tank; 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.

[0038] The flash tower is a packed tower, the packing is structured packing 352Y, and the packing height is 4 meters.

[0039] The demethanol tower adopts a packed tower, and the packing is 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.

[0040] The phenol recovery tower adopts a packed tower with structured packing 352Y. The height of the distillation section is 8 meters and the height of the stripping section is 16 meters.

[0041] The o-cresol distillation tower adopts a packed tower with structured packing 352Y. The height of the distillation section is 12 meters and the height of the stripping section is 8 meters.

[0042] The top condensers of the phenol recovery tower and the o-cresol distillation tower are steam generators used to generate 0.45MPaG steam, which serves as a heat source for the demethanol tower and the azeotropic dehydration tower reboiler; the heat sources of the phenol recovery tower reboiler and the o-cresol distillation tower reboiler are thermal oil, and the reboilers are all vertical thermosyphon reboilers.

[0043] Example 1

[0044] According to a method for separating reaction products of an o-cresol device of the present invention, light hydrocarbons and non-condensable gases are first removed from the reaction products of the reaction part by flash distillation, and the light components at the top of the flash tower are separated by distillation to obtain a methanol solution, an anisole-methanol mixed solution, and a phenol aqueous solution; the anisole-methanol mixed solution is subjected to mixed extraction with water to separate the 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.

[0045] 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 with reference to the accompanying drawings.

[0046] After heat exchange with the reaction feed heat exchanger, the reaction products from the reaction section are fed into the bottom of flash tower 101. The overhead vapor is condensed in flash tower condenser 102, and the condensate enters flash tower reflux drum 103 for gas-liquid separation. A portion of the liquid phase is used as reflux, while the remaining portion is withdrawn from the reflux drum as light fractions. The tower operates at 140 kPa. This is primarily due to the flash tower feed temperature being 170-180°C. The overhead stream consists of non-condensable gas, methanol, anisole, and light fractions of a mixed phenolic group, primarily phenol. The vapor phase is fed to a reaction carrier gas booster for pressure, and the liquid phase is fed to demethanolation tower 104 for separation. The bottom stream from flash tower 101, primarily phenol, o-cresol, and 2,6-dimethylphenol, is fed to phenol recovery tower 115 for separation.

[0047] The liquid stream from the top of the flash tower is fed into the middle of the de-methanolation tower 104. After sufficient vapor-liquid heat and mass transfer, light and heavy separation is achieved. The overhead vapor is condensed in the de-methanolation tower condenser 106 and then enters the de-methanolation tower reflux tank 107. A portion is refluxed, and the remainder is recovered as recycled methanol. The methanol content is approximately 78.8%, and the anisole content is less than 3%. The distillation section is packed in two sections, with the upper section having a height of 1 meter and the lower section having a height of 3 meters. The side draw is taken from the bottom of the upper section. When the anisole mass fraction in the de-methanolation tower feed reaches 3%, the high-concentration anisole mixed solution is withdrawn, cooled in the de-methanolation tower side cooler 108, and then fed into the anisole extraction mixer 109. The bottom temperature is 112-115°C, and the tower is operated at 120 kPa. The tower bottom is provided with a demethanol tower reboiler 105, 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.

[0048] The mixed liquid from the methanol removal tower sideline cooler 108 is combined with water from the azeotropic dehydration tower reflux drum 114 in the anisole extraction mixer 109. The mixed stream enters the anisole extraction separation tank 110 for static separation. The methanol solution at the top of the tank is sent to the methanol recycling tank, while the anisole stream extracted from the bottom of the tank is sent to the anisole storage tank as the anisole product. The anisole extraction separation tank operates at atmospheric pressure and a temperature of 40°C. The extraction water flow rate is 1 to 1.5 times the sideline extraction flow rate.

[0049] The mixed phenol-water mixture enters azeotropic dehydration tower 111, where water and cyclohexane azeotropize. After sufficient gas-liquid heat and mass transfer, the water and phenol are separated. The overhead vapor is condensed in azeotropic dehydration tower condenser 112 and then enters azeotropic dehydration tower reflux drum 114 for oil-water separation. The oil phase is recycled back to azeotropic dehydration tower 111, with some of the separated water used as an extractant and some sent to a sewage treatment plant. Entrainer cyclohexane is introduced from the top of the tower in an amount 7-8 times the mass of the water component fed to azeotropic dehydration tower 111. The tower bottom temperature is 95°C, and the tower operating pressure is 120 kPa. The tower bottom is equipped with an azeotropic dehydration tower reboiler 112, whose heat source is 0.45 MPaG steam. The mixed phenol stream produced from the bottom of the tower is fed to phenol recovery tower 115 along with the recombined split stream from the flash tower 101.

[0050] The stream from the flash tower 101 and the azeotropic dehydration tower 111 are combined and separated in the phenol recovery tower 115. The overhead vapor is condensed in the phenol recovery tower steam generator 117 and then enters the phenol recovery tower reflux drum 118, where it is partially refluxed and the remainder is withdrawn. The withdrawn phenol material is sent to the reaction feed preheater 123 for preheating before being sent to the phenol recovery tank. The recovery tower steam generator 117 uses deoxygenated water as the cooling medium, generating 0.45 MPaG steam. The tower bottom temperature is 200-210°C, and the tower operating pressure is 120 kPa. The phenol recovery tower reboiler 116 is located in the tower bottom, and its heat source is thermal oil from the system. The o-cresol and 2,6-xylenol streams withdrawn from the tower bottom are sent to the o-cresol distillation tower 119.

[0051] After the o-cresol and 2,6-xylenol streams enter the o-cresol distillation tower 119, they undergo extensive gas-liquid heat and mass transfer within the tower, separating the o-cresol and 2,6-xylenol. The overhead vapor is condensed in the o-cresol distillation tower steam generator 121 and then enters the o-cresol distillation tower reflux drum 122, where part of the vapor is refluxed and the remainder is withdrawn. The withdrawn o-cresol material is fed to the o-cresol hot water heat exchanger 124 to be heated, then cooled in the o-cresol cooler 125 before being transferred to the o-cresol product storage tank. The o-cresol product has a mass fraction of ≥99.5%, and a mass fraction of phenol of less than 0.2%. The cooling medium in the o-cresol distillation tower steam generator 121 is deoxygenated water, which generates 0.45 MPaG steam. The tower bottom temperature is 220-230°C, and the tower operating pressure is 120 kPa. The tower bottom is provided with an o-cresol distillation tower reboiler 120, the heat source of the reboiler is the thermal oil from the system, and the 2,6-xylenol produced from the tower bottom is cooled by the 2,6-xylenol cooler 126 and then sent to the 2,6-xylenol product storage tank.

[0052] In order to better illustrate the technical superiority of the present invention, it is compared with the actual project pointed out in the paper "Process Technology for Synthesis of O-Cresol by Gas Phase Alkylation of Phenol-Methanol" in "Biochemical Engineering" No. 202302, Example 1.

[0053] The process shown in Comparative Example 1 is a 16,000-ton / year o-cresol device. Its process rectification part adopts a five-tower process, namely a flash tower, a dehydration tower, a methanol removal tower, a dephenolization 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 sent to the dehydration tower for rectification after the flash tower discharge pump is boosted. The liquid phase at the bottom of the dehydration tower is sent to the dephenolization tower feed tank after the dehydration tower discharge pump is boosted. The dephenolization tower feed pump sends the material in the dephenolization tower feed tank into the dephenolization tower for rectification. The dephenolization tower bottom product is sent to the o-cresol tower feed tank after the dephenolization tower discharge pump is boosted. The o-cresol tower feed pump sends the material in the o-cresol tower feed tank into the o-cresol tower for rectification. The o-cresol vapor produced from the o-cresol column overhead passes through the o-cresol column overhead separation tank, is condensed in the feed-o-cresol heat exchanger, and cooled in the o-cresol cooler. It then enters the o-cresol tank as the finished product and is pumped to the tank farm with the finished o-cresol product. The o-cresol column reboiler in the o-cresol column kettle uses thermal oil as its heat source. A side stream is opened at the top of the column bottom to produce a mixed 2,6-xylenol product. This product is pressurized by the o-cresol column discharge pump and cooled to 80°C in the 2,6-xylenol cooler before being delivered to the 2,6-xylenol tank. It is then pumped to the tank farm with the finished 2,6-xylenol product.

[0054] After the 16,000 tons / year o-cresol plant was implemented using the technical solution of the present invention, the operating parameters were compared with those of Comparative Example 1, as shown in Table 1, and the energy consumption was compared, as shown in Table 2.

[0055] The process shown in Comparative Example 1 results in anisole accumulation, resulting in an outflow of 60 kg / h of methanol, which needs to be processed by related enterprises. The technology of the present invention uses 4 kg / h of anisole to discharge, which can be sold as a gasoline blending component; the concentration of anisole in the recycled methanol is high, the selectivity of the alkylation reaction is reduced to 80%, the production of o-cresol is reduced by 200 kg / h, and the production of xylenol is increased by 200 kg / h.

[0056] The process shown in Comparative Example 1 discharges 500 kg / h of phenol-containing wastewater with a phenol concentration of 5000 ppm, 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 the grease trap.

[0057] Table 1 Comparison of operating parameters of the present invention and comparative example 1

[0058]

[0059] Table 2 Comparison of energy consumption per ton of cresol product between the present invention and comparative example 1

[0060]

[0061] As shown in Tables 1 and 2, by implementing the present invention's technology and optimizing the tower operating parameters, utility consumption was significantly reduced compared to Comparative Example 1. According to GB / T 50441-2016 energy consumption calculations, energy consumption per unit of cresol production decreased by 40.09 kg of standard oil. The increased production costs of Example 1 compared to the present invention's technology are shown in Table 3.

[0062] Table 3 Example 1 increases production costs compared with the technology of the present invention

[0063]

[0064] The embodiments described in the present invention are merely descriptions of the preferred implementation methods 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 scope of protection 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. A reaction product separation device for an o-cresol unit, comprising 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, the condenser being connected to a reflux tank; and each tower, except the flash tower, is provided with a reboiler at the bottom; characterized in that: The side line of the methanol removal tower is connected in sequence to an anisole extraction mixer and an anisole extraction separation tank; the bottom of the water bag of the azeotropic dehydration tower top reflux tank 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 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 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 structured packing 352Y, the height of the distillation 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 serves as a heat source for the reboiler 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.

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