Low-energy-consumption separation device and low-energy-consumption separation method for post-reaction material for preparing phenol by oxidizing benzene with laughing gas

Abstract

The invention provides a low-energy-consumption separation device and a low-energy-consumption separation method for a post-reaction material for preparing phenol by oxidizing benzene with laughing gas, a benzene rectification tower in the low-energy-consumption separation device comprises a benzene rectification tower body, and a benzene rectification feed port and a benzene rectification medium boiler which are arranged in the middle of the benzene rectification tower body, a top gas phase outlet of the phenol rectifying tower is provided with a first gas phase pipeline, a second gas phase pipeline and a third gas phase pipeline, and the first gas phase pipeline is connected with a heat exchange medium channel inlet of a benzene rectifying medium boiler; the second gas phase pipeline is connected with a heat exchange medium channel inlet of the preheating device; and the third gas-phase pipeline is connected with a heat exchange medium channel inlet of the phenol rectifying tower top heat exchanger. The heat in the tower top high-temperature gas phase of the phenol rectifying tower can be fully utilized, the separation energy consumption is remarkably reduced, and the economical efficiency of the device and the process is improved.

Description

Technical Field

[0001] The invention relates to the technical field of preparing phenol by oxidizing benzene with laughing gas, and in particular to a low-energy-consumption separation device and a low-energy-consumption separation method for materials after the reaction of preparing phenol by oxidizing benzene with laughing gas. Background Art

[0002] Phenol is an important chemical raw material, mainly used in the production of chemical products such as phenolic resin, epoxy resin, alkylphenol, bisphenol A and adipic acid.

[0003] The cumene process is currently the mainstream phenol production process. It involves the reaction of propylene and benzene to produce cumene, which is further oxidized to produce cumene hydroperoxide. Finally, it decomposes under the action of a sulfuric acid catalyst to produce phenol and acetone. This process is lengthy, involves multiple reaction stages, is complex to operate, and produces large amounts of low-value acetone. Given the challenges of the current cumene-based phenol production process, the one-step nitrous oxide (NO) oxidation of benzene to phenol has become a hot topic of research. Compared to the cumene process, this one-step nitrous oxide oxidation of benzene to phenol offers advantages such as environmental friendliness, high atom utilization, a shorter process, and fewer byproducts. This is particularly true for existing nitric acid oxidation plants for adipic acid production, as the large amount of nitrous oxide produced as a byproduct can be utilized for high-value-added purposes, resulting in higher economic value. However, this technology also has drawbacks, such as short catalyst life, low feedstock conversion, and high energy consumption, which significantly impact overall economic benefits and the pace of industrial development.

[0004] Existing research on the oxidation of benzene to phenol by laughing gas has mainly focused on the field of catalyst reactions. For example, SA115360683B1 developed a supported zeolite catalyst. In the reaction temperature range of 320-440°C, laughing gas was used to oxidize benzene to produce phenol, and the conversion rate of benzene reached up to 26%. CN102125868A reported a micro-mesoporous composite Fe-ZSM-5 molecular sieve and applied it to the reaction of benzene to phenol. After 3 hours of reaction, the conversion rate of benzene can be maintained at 20%. It can be found from the above patents that no matter what form of catalyst is used, the conversion rate of benzene is relatively low, which is bound to cause a large amount of benzene circulation and a substantial increase in energy consumption in the separation stage, seriously affecting the profitability of the entire device. If conventional separation methods are used to separate laughing gas oxidation benzene to phenol, such as Figure 1As shown, the reaction product condensate containing benzene, phenol, and heavy components directly enters the benzene column. The overhead gas phase is condensed with circulating water and enters the reflux tank. A portion of the overhead condensate is refluxed to the benzene column, and a portion is withdrawn and recycled back to the oxidation reaction system. The crude phenol at the bottom of the column enters the phenol distillation column. The overhead gas phase is condensed with circulating water, and a portion is refluxed to the phenol distillation column, while the remainder is withdrawn as the product. The heavy components at the bottom of the column are withdrawn and processed. Because the conversion rate of benzene to phenol is generally 20-30% when oxidizing benzene with nitrous oxide to produce phenol, a large amount of benzene needs to be recovered. Therefore, the above process is adopted. The benzene column is used to distill and recover a large amount of benzene from heavy components such as phenol. Therefore, the reboiler in the bottom of the column is heavily loaded and is the main energy consumer in the separation process. Reducing the energy consumption of the benzene column and reducing the steam consumption of the reboiler are key to the industrialization of the nitrous oxide oxidation process of benzene to phenol. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a low-energy consumption separation device and a low-energy consumption separation method for the reaction product of phenol produced by oxidation of benzene with nitrous oxide. By providing a benzene distillation intermediate boiler in a benzene distillation tower and dividing the heat of the gas phase at the top of the phenol distillation tower into three streams for batch utilization, the steam consumption of the benzene distillation tower and the amount of circulating cooling water at the top of the phenol distillation tower are significantly reduced, the separation energy consumption is greatly reduced, and the benzene purity can reach 99.9%, thereby improving the economic efficiency of the entire device and process.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a low-energy consumption separation device for the reaction of phenol produced by oxidation of benzene by laughing gas, wherein the low-energy consumption separation device comprises a preheating device, a benzene distillation tower and a phenol distillation tower; the material inlet of the preheating device is connected to the outlet of the reaction device for phenol produced by oxidation of benzene by laughing gas; the benzene distillation tower comprises a benzene distillation tower body, a benzene distillation feed port and a benzene distillation intermediate boiler arranged in the middle of the benzene distillation tower body, and a benzene distillation tower bottom discharge port arranged at the bottom of the benzene distillation tower body; the phenol distillation tower comprises a phenol distillation tower body, a phenol distillation feed port and a benzene distillation intermediate boiler arranged in the middle of the benzene distillation tower body, and a benzene distillation tower bottom discharge port arranged at the bottom of the benzene distillation tower body; The top of the phenol distillation tower body is provided with a phenol distillation tower top gas phase outlet and a phenol distillation tower top heat exchanger; the benzene distillation feed port is connected to the material outlet of the preheating device; the benzene distillation tower bottom discharge port is connected to the phenol distillation feed port; the phenol distillation tower top gas phase outlet is provided with a first gas phase pipeline, a second gas phase pipeline and a third gas phase pipeline, the first gas phase pipeline is connected to the heat exchange medium channel inlet of the benzene distillation boiler; the second gas phase pipeline is connected to the heat exchange medium channel inlet of the preheating device; the third gas phase pipeline is connected to the heat exchange medium channel inlet of the phenol distillation tower top heat exchanger.

[0008] First, it's worth noting that the nitrous oxide (NO) oxidation of benzene to phenol differs from other reactions in that the conversion of benzene is low, requiring large amounts of benzene to be recovered. This high benzene recovery consumes significant energy, making it crucial to reduce the energy consumption required to separate benzene from phenol. Furthermore, the catalyst in the nitrous oxide oxidation reaction is sensitive to impurities, necessitating that the benzene recovered from the benzene distillation column have a purity greater than 98% by weight and a phenol content less than 2% by weight, preferably less than 1.5% by weight.

[0009] In order to better reduce the energy consumption of separation and maintain the purity of the recovered benzene, the low-energy consumption separation device for the reaction material of phenol produced by oxidation of benzene with laughing gas of the present invention has the following special settings:

[0010] A, the oxidizing reaction unit of laughing gas oxidation benzene processed phenol is connected gas-liquid separator after, the purpose of gas-liquid separator is to separate a part of benzene, earlier reclaim return benzene and laughing gas oxidizing reaction unit, remaining benzene and phenol enter the benzene rectifying tower and proceed to separate, in order to avoid phenol, return the oxidizing reaction unit with benzene in gas-liquid separator, need to carry out gas-liquid separation below 80 ℃, therefore the low-temperature liquid phase (this low-temperature liquid phase is reaction after material of the present invention) that obtains directly enters the benzene rectifying tower body and certainly will increase the steam consumption of benzene rectifying tower reboiler, therefore the present invention at first arranges preheating unit before benzene rectifying tower, earlier the raw material that enters benzene rectifying tower is preheated, greatly reduce the energy consumption of benzene rectifying tower bottom reboiler, the heat exchange medium inlet of preheating unit is connected to each other with the second gas phase pipeline simultaneously, namely the heat of phenol rectifying tower top gas phase can be fully utilized,

[0011] B. To ensure that the benzene content in the benzene distillation tower is up to standard, the temperatures of the bottom and the trays near the bottom of the benzene distillation tower are relatively high, making it impossible to utilize the top heat of the phenol distillation tower. The inventors have discovered that as the material to be separated in the benzene distillation tower moves upward, the tray temperature drops significantly. Therefore, it is desirable to extract this portion of the tray material and pass it through a boiler in the benzene distillation to utilize the top gas phase heat energy of the phenol distillation tower, thereby reducing the amount of high-grade steam in the bottom of the benzene distillation tower.

[0012] C. A phenol distillation tower top heat exchanger is also provided. After the preheating device and the benzene distillation intermediate boiler are preferentially matched with the phenol distillation tower top gas phase, the third gas phase pipeline is connected to the phenol distillation tower top heat exchanger to perform residual cooling of the phenol distillation tower top gas phase. This also reduces the energy demand of the phenol distillation tower top heat exchanger and can promote the complete and smooth operation of the entire system.

[0013] Preferably, the benzene distillation tower further comprises a benzene distillation tower top heat exchanger and a benzene distillation tower top liquid separator which are arranged at the top of the benzene distillation tower body and are sequentially connected along the material conveying direction.

[0014] Preferably, a circulation pipeline connected to the benzene distillation tower body and a liquid phase material outlet at the top of the benzene distillation tower are provided at the lower part of the liquid separator at the top of the benzene distillation tower.

[0015] Preferably, a benzene distillation gas phase material outlet is provided at the upper portion of the benzene distillation tower top liquid separator.

[0016] Preferably, the benzene distillation tower further comprises a benzene distillation tower bottom reboiler arranged at the bottom of the benzene distillation tower body.

[0017] Preferably, the number of theoretical plates of the benzene distillation tower body is 10 to 50, for example, it can be 10, 15, 19, 24, 28, 33, 37, 42, 46 or 50, etc., preferably 20 to 35.

[0018] Preferably, the feed position of the benzene distillation tower body is 3 to 25 of the theoretical plates of the benzene distillation tower body, for example, it can be 3, 4, 5, 6, 10, 12, 15, 18, 20, 22 or 25 plates.

[0019] Preferably, the boiler in the benzene distillation is arranged at a position where the theoretical number of plates of the benzene distillation tower body is 4 to 32, for example, it can be 4, 5, 7, 9, 11, 13, 15, 17, 19, 20, 21, 22, 25, 26, 27, 28, 29, 30, 31 or 32, etc.

[0020] The location of the boiler in the benzene distillation is very critical in the present invention. This is because the material needs to exchange heat with the gas phase at the top of the phenol distillation tower. Studies have found that the location of the boiler in the benzene distillation is preferably within the above-mentioned range, which can better reduce the energy consumption of the benzene distillation tower kettle. In addition, the inventors found that the temperature of the material returning from the intermediate reboiler to the original tower plate will affect the purity of the benzene obtained by distillation separation. The inventors avoid adverse effects on the purity of benzene by reasonably setting the side line extraction position.

[0021] Preferably, in order to further utilize the energy of the gas phase at the top of the phenol distillation tower, the number of boilers in the benzene distillation tower is 1 to 3, preferably 1 to 2.

[0022] Preferably, the material withdrawal port of the benzene distillation boiler is located 1 to 2 theoretical plates above the material return port.

[0023] Preferably, when at least two benzene distillation intermediate boilers are provided, to fully utilize energy consumption in a graded manner and ensure that the purity of benzene recovered from the benzene distillation column is greater than 98wt%, the number of theoretical plates between two adjacent benzene distillation intermediate boilers is at least 2, thereby maintaining the temperature gradient within the benzene distillation column and ensuring good mass and heat transfer between the two phases. Preferably, the phenol distillation column further includes a phenol distillation column bottom reboiler and a phenol distillation column bottom outlet disposed below the phenol distillation column body.

[0024] Preferably, the phenol distillation tower further includes a phenol distillation tower top liquid separator, which is connected to the heat exchange medium channel outlet of the benzene distillation boiler, the heat exchange medium channel outlet of the preheating device and the heat exchange medium channel outlet of the phenol distillation tower top heat exchanger.

[0025] The invention returns the liquid phase after heat exchange with the benzene distillation boiler, the preheating device and the phenol distillation tower top liquid separator to the phenol distillation tower top liquid separator, and performs liquid separation and recovery.

[0026] Preferably, a circulation pipeline connected to the phenol distillation tower body and a liquid phase material outlet at the top of the phenol distillation tower are provided at the lower part of the liquid separator at the top of the phenol distillation tower.

[0027] In a second aspect, the present invention provides a low-energy separation method for the reaction material after nitrous oxide oxidation of benzene to produce phenol, wherein the low-energy separation method is carried out using the low-energy separation device for the reaction material after nitrous oxide oxidation of benzene to produce phenol described in the first aspect.

[0028] The low-energy separation method provided in the second aspect of the present invention is carried out using the low-energy separation device for the reaction material after the oxidation of benzene to phenol by nitrous oxide according to the first aspect. It can fully utilize the heat of the gas phase at the top of the phenol distillation tower, thereby significantly reducing the energy consumption of the separation and ensuring the purity of the benzene recovered by the benzene distillation tower.

[0029] Preferably, the low-energy separation method comprises:

[0030] The post-reaction material produced by the oxidation of benzene with nitrous oxide to produce phenol is preheated in a preheating device before being fed into a benzene distillation column for benzene distillation. The bottom material is withdrawn from the middle of the benzene distillation column, heated in a benzene distillation boiler, and then returned to the benzene distillation column.

[0031] The bottom material of the benzene distillation tower is fed into the phenol distillation tower body for phenol distillation, and the gas phase at the top of the phenol distillation tower is extracted from the gas phase outlet at the top of the phenol distillation tower.

[0032] Among them, the gas phase at the top of the phenol distillation tower is divided into a first gas phase stream, a second gas phase stream and a third gas phase stream. The first gas phase stream is sent to the benzene distillation boiler for heating the intermediate material of the benzene distillation, the second gas phase stream is sent to the preheating device for preheating the reaction material, and the third gas phase stream is sent to the heat exchanger at the top of the phenol distillation tower for condensation treatment.

[0033] Generally, the reaction temperature of the nitrous oxide oxidation of benzene to phenol reaction is 300-500°C, and the temperature of the direct discharge material after the reaction is 350-550°C. The material of the nitrous oxide oxidation of benzene to phenol is first separated by a gas-liquid separation device, and a part of the benzene is first returned to the nitrous oxide oxidation of benzene to phenol reaction system, and the other part of the mixed liquid phase of benzene and phenol is recorded as the post-reaction material.

[0034] Preferably, the temperature of the reaction material is 40-80° C., for example, 40° C., 42° C., 45° C., 48° C., 50° C., 52° C., 53° C., 54° C., 55° C., 58° C., 60° C., 62° C., 65° C., 68° C., 70° C., 72° C., 75° C., 78° C., or 80° C. The reaction material comprises 40-65wt% of benzene and 35-60wt% of phenol. The benzene content can be, for example, 40wt%, 42wt%, 45wt%, 48wt%, 50wt%, 52wt%, 55wt%, 58wt%, 60wt%, 62wt%, or 65wt%. The phenol content can be, for example, 35wt%, 36wt%, 38wt%, 40wt%, 42wt%, 45wt%, 48wt%, 50wt%, 52wt%, 55wt%, 56wt%, 58wt% or 60wt%, etc.

[0035] Preferably, the outlet temperature of the preheating device is 80-150°C, for example, it can be 80°C, 88°C, 96°C, 104°C, 112°C, 119°C, 127°C, 135°C, 143°C or 150°C, etc., preferably 100-135°C.

[0036] Preferably, the top temperature of the benzene distillation tower body is 46-66°C, for example, it can be 46°C, 49°C, 51°C, 53°C, 55°C, 58°C, 60°C, 62°C, 64°C or 66°C.

[0037] Preferably, the bottom temperature of the benzene distillation tower body is 145-165°C, for example, it can be 145°C, 148°C, 150°C, 152°C, 155°C, 158°C, 160°C, 162°C or 165°C.

[0038] Preferably, the top pressure of the benzene distillation tower body is 20-80 kPa, for example, it can be 20 kPa, 27 kPa, 34 kPa, 40 kPa, 47 kPa, 54 kPa, 60 kPa, 67 kPa, 74 kPa or 80 kPa, etc., preferably 30-50 kPa.

[0039] Preferably, the temperature of the benzene distillation intermediate material extracted from the boiler in the benzene distillation is 60-100°C, for example, it can be 60°C, 65°C, 69°C, 74°C, 78°C, 83°C, 87°C, 92°C, 96°C or 100°C.

[0040] The temperature of the benzene distillation intermediate material that the boiler returns in the benzene rectification is 100~130 ℃, for example, can be 100 ℃, 105 ℃, 110 ℃, 112 ℃, 115 ℃, 118 ℃, 120 ℃, 122 ℃, 125 ℃, 128 ℃ or 130 ℃ etc.When the temperature of the benzene intermediate material extracted is on the low side, it will affect the effective and reasonable utilization of heat.And it is necessary to ensure that the intermediate material supplements heat and returns to the tray after the temperature difference with the original tray temperature cannot be greater than 45 ℃, if the temperature difference is too large, it will affect the reduction of benzene purity.When the temperature of the benzene distillation intermediate material extracted is on the high side, there is the problem that the gas phase energy of the phenol tower top cannot be utilized.So it is necessary to maintain a reasonable side-collecting temperature and maintain the temperature of the benzene distillation intermediate material returning to the benzene rectification tower to be within a reasonable range.

[0041] Preferably, when at least two intermediate boilers are provided for benzene distillation, the side-sampling temperature difference between two adjacent intermediate boilers for benzene distillation is 20-40°C, for example, 20°C, 23°C, 25°C, 27°C, 29°C, 32°C, 34°C, 36°C, 38°C or 40°C. When two intermediate boilers are provided, maintaining a certain temperature difference range allows for graded heat utilization.

[0042] In addition, in order to save energy and obtain high-purity recovered benzene, the effects of the inlet flow rate of the benzene distillation tower, the reflux ratio of the benzene distillation tower, and the flow rate of the benzene distillation intermediate material were further studied, as follows:

[0043] Preferably, the reflux ratio of the benzene distillation is 0.5 to 3:1, for example, 0.5:1, 0.8:1, 1.1:1, 1.4:1, 1.7:1, 1.9:1, 2.2:1, 2.5:1, 2.8:1 or 3:1. In the present invention, the reflux ratio of the benzene distillation is preferably controlled at 0.5 to 3:1. A reflux ratio that is too low will result in unqualified purity of the overhead benzene.

[0044] Preferably, the ratio of the flow rate of the benzene distillation intermediate material to the feed inlet flow rate in the benzene distillation is 0.5 to 2:1, for example, it can be 0.5:1, 0.7:1, 0.9:1, 1:1, 1.2:1, 1.4:1, 1.5:1, 1.7:1, 1.9:1 or 2:1, etc.

[0045] The intermediate material of benzene distillation is extracted from the stripping section, heated and partially vaporized in the boiler of benzene distillation, and the obtained vapor-liquid two-phase is returned to the benzene distillation tower body for redistribution. The ratio of the flow rate of the intermediate material extracted from benzene distillation to the flow rate of the feed port in the benzene distillation is controlled within the above range. When the ratio of the flow rate of the intermediate material extracted from benzene distillation to the flow rate of the feed port in the benzene distillation is too high, the purity of the benzene at the top of the tower is affected.

[0046] In the present invention, the phenol distillation tower differs from the prior art in that the gas phase energy at the top of the phenol distillation tower is utilized, thereby reducing the energy demand of the top heat exchanger of the phenol distillation tower. Other parameters of the phenol distillation tower can be set according to requirements. The following preferred embodiments are listed:

[0047] Preferably, the phenol distillation tower has 10 to 50 theoretical plates, for example, 10, 15, 19, 24, 28, 33, 37, 42, 46 or 50 plates, and preferably 20 to 35 plates.

[0048] Preferably, the feed position of the phenol distillation tower is at the 3rd to 25th theoretical tray positions, for example, it can be 3, 4, 5, 6, 8, 10, 12, 13, 14, 15, 18, 20, 22, 24 or 25 theoretical trays.

[0049] Preferably, the top temperature of the phenol distillation tower is 120-200°C, for example, it can be 120°C, 129°C, 138°C, 147°C, 156°C, 165°C, 174°C, 183°C, 192°C or 200°C, and is preferably 130-180°C.

[0050] Preferably, the top pressure of the phenol distillation tower is 20 to 80 kPa, for example, it can be 20 kPa, 22 kPa, 25 kPa, 30 kPa, 32 kPa, 35 kPa, 38 kPa, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa or 80 kPa, etc., preferably 30 to 50 kPa.

[0051] Preferably, the percentage of the first gas phase stream to the top gas phase of the phenol distillation tower is 30 to 70 wt%, for example, it can be 30 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, 45 wt%, 48 wt%, 50 wt%, 55 wt%, 58 wt%, 60 wt%, 62 wt%, 65 wt% or 70 wt%, etc.

[0052] Preferably, the percentage of the second gas phase stream to the phenol distillation tower top gas phase is 20-30wt%, for example, it can be 20wt%, 21wt%, 22wt%, 25wt%, 28wt%, 29wt% or 30wt%.

[0053] Compared with the prior art, the present invention has at least the following beneficial effects:

[0054] (1) The low-energy consumption separation device for the reaction material of phenol produced by oxidation of benzene with laughing gas provided by the present invention is capable of effectively utilizing the heat of the high-temperature gas phase at the top of the phenol rectification tower by arranging a preheating device and a benzene distillation mid-boiler, and arranging the first gas phase pipeline, the second gas phase pipeline and the third gas phase pipeline at the gas phase outlet at the top of the phenol rectification tower, thereby significantly reducing the separation energy consumption of phenol produced by oxidation of benzene with laughing gas. Under preferred conditions, for 30 t / h of reaction material, the circulating water of the present invention can save more than RMB 1.169 million / year, the steam can save more than RMB 12.896 million / year, and the benzene purity can reach 99.9%, thereby improving the economy of the whole set of equipment.

[0055] (2) The low-energy separation method for the reaction of phenol produced by oxidation of benzene with laughing gas provided by the present invention is based on the characteristics of the separation process of phenol produced by oxidation of benzene with laughing gas, and the benzene distillation tower and the phenol distillation tower are effectively thermally coupled, with low equipment investment and obvious energy-saving and consumption-reducing effects;

[0056] (3) In the low-energy separation method for the reaction of phenol produced by oxidation of benzene with nitrous oxide provided by the present invention, the temperature of the top condenser of the phenol distillation tower is high and scaling is easy to form on the circulating water side. The top gas-heat coupling method is adopted to reduce or even avoid the influence of the deterioration of the condensation effect of the top heat exchanger of the phenol distillation tower due to scaling on the normal operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 Schematic diagram of a device for separating materials after the reaction of nitrous oxide oxidation of benzene to phenol provided in Comparative Example 1 of the present invention.

[0058] Figure 2 Schematic diagram of a low-energy separation device for the reaction material after the oxidation of benzene to phenol by laughing gas provided in Examples 1 and 2 of the present invention.

[0059] Figure 3Schematic diagram of a low-energy separation device for the reaction material after the oxidation of benzene to phenol by laughing gas provided in Example 3 of the present invention.

[0060] In the figure: T1, benzene distillation tower body; T2, phenol distillation tower body; E1, benzene distillation tower top heat exchanger; E2, benzene distillation tower bottom reboiler; E3, phenol distillation tower top heat exchanger; E4, phenol distillation tower bottom reboiler; E5, preheating device; E6, benzene distillation intermediate boiler; E7, second benzene distillation intermediate boiler; V1, benzene distillation tower top liquid separator; V2, phenol distillation tower top liquid separator. DETAILED DESCRIPTION

[0061] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0062] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0063] It should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0064] Those skilled in the art will appreciate that the present invention necessarily includes necessary pipelines, conventional valves, and general-purpose pumping equipment to complete the process, but the above content does not constitute the main inventive point of the present invention. Those skilled in the art can further add layouts based on the process flow and equipment structure selection, and the present invention does not impose any special requirements or specific limitations on this. The number of theoretical plates described in the present invention is calculated from the first plate at the top of the tower to the bottom of the tower.

[0065] Example 1

[0066] This embodiment provides a low energy consumption separation device for the reaction of phenol with nitrous oxide oxidation of benzene. Figure 2 The low-energy separation device includes a preheating device, a benzene distillation tower and a phenol distillation tower.

[0067] The benzene distillation tower includes a benzene distillation tower body, a benzene distillation feed inlet and a benzene distillation intermediate boiler arranged in the middle of the benzene distillation tower body, and a benzene distillation tower bottom discharge port arranged at the bottom of the benzene distillation tower body; the benzene distillation tower also includes a benzene distillation tower top heat exchanger and a benzene distillation tower top liquid separator arranged at the top of the benzene distillation tower body and connected in sequence along the material conveying direction; the lower part of the benzene distillation tower top liquid separator is provided with a circulation pipeline connected to the benzene distillation tower body, as well as a benzene distillation tower top liquid phase material outlet; the upper part of the benzene distillation tower top liquid separator is provided with a benzene distillation gas phase material outlet; the benzene distillation tower also includes a benzene distillation tower bottom reboiler arranged at the bottom of the benzene distillation tower body.

[0068] The benzene distillation tower body has 20 theoretical plates; the feed position is set at the 10th theoretical plate, and the benzene distillation boiler is set at the position with the 12th theoretical plate of the benzene distillation tower body; the number of the benzene distillation boilers is 1; the material withdrawal port of the benzene distillation boiler is located on the tower plate above the material return port, that is, the material withdrawal port is located at the position of 1 tower plate above the material return port.

[0069] The phenol distillation tower includes a phenol distillation tower body, a phenol distillation feed inlet arranged in the middle of the phenol distillation tower body, a phenol distillation tower top gas phase outlet arranged at the top of the phenol distillation tower body, and a phenol distillation tower top heat exchanger; the phenol distillation tower also includes a phenol distillation tower bottom reboiler and a phenol distillation tower bottom extraction outlet arranged below the phenol distillation tower body; the phenol distillation tower also includes a phenol distillation tower top liquid separator, which is connected to the heat exchange medium channel outlet of the benzene distillation boiler, the heat exchange medium channel outlet of the preheating device, and the heat exchange medium channel outlet of the phenol distillation tower top heat exchanger; a circulation pipeline is provided at the lower part of the phenol distillation tower top liquid separator, which is connected to the phenol distillation tower body and the phenol distillation tower top liquid phase material outlet.

[0070] The phenol distillation tower body has 20 theoretical plates, and the feed position is the 13th theoretical plate. The top gas phase outlet of the phenol distillation tower is provided with a first gas phase pipeline, a second gas phase pipeline and a third gas phase pipeline. The first gas phase pipeline is connected to the heat exchange medium channel inlet of the boiler in the benzene distillation; the second gas phase pipeline is connected to the heat exchange medium channel inlet of the preheating device; the third gas phase pipeline is connected to the heat exchange medium channel inlet of the heat exchanger at the top of the phenol distillation tower.

[0071] The benzene distillation feed port is connected to the material outlet of the preheating device; the benzene distillation tower bottom discharge port is connected to the phenol distillation feed port; the material inlet of the preheating device is connected to the outlet of the reaction device for oxidizing benzene to produce phenol with laughing gas.

[0072] Example 2

[0073] This embodiment provides a low energy consumption separation device for the reaction of phenol with nitrous oxide oxidation of benzene. Figure 2 , which is different from Example 1 in that:

[0074] The benzene distillation tower has 30 theoretical plates; the feed position is set at the 15th theoretical plate, and the benzene distillation intermediate boiler is located at the 20th theoretical plate of the benzene distillation tower. There is one intermediate boiler in the benzene distillation tower, and the material withdrawal port of the intermediate boiler is located on the tray above the material return port, that is, the material withdrawal port is located one tray above the material return port. The phenol distillation tower has 35 theoretical plates, and the feed position is at the 20th theoretical plate.

[0075] The rest are the same as in Example 1 and will not be described again.

[0076] Example 3

[0077] This embodiment provides a low-energy separation device for the reaction material after the oxidation of benzene to phenol by laughing gas, which is different from Example 1 in that:

[0078] The material extraction port of the benzene distillation boiler is located on a tower plate below the material return port, that is, the material extraction port is located at a position of one tower plate below the material return port.

[0079] Example 4

[0080] This embodiment provides a low energy consumption separation device for the reaction of phenol with nitrous oxide oxidation of benzene. Figure 3 , which is different from Example 1 in that:

[0081] The benzene distillation column body has 20 theoretical plates; the feed position is set at the 10th theoretical plate; the benzene distillation intermediate boilers are set at positions where the theoretical plates of the benzene distillation column body are 16 and 13; the number of the benzene distillation intermediate boilers is 2. All other steps are the same as those in Example 1 and will not be repeated here.

[0082] Example 5

[0083] The difference from Example 4 is that the boilers in the benzene distillation are arranged at the positions where the theoretical plates of the benzene distillation tower body are 11 and 13. The rest are the same as Example 4 and will not be repeated here.

[0084] Comparative Example 1

[0085] This comparative example provides a device for separating the materials after the reaction of nitrous oxide oxidation of benzene to phenol. Figure 1 The separation device is the same as that in Example 1 except that the preheating device, the benzene distillation boiler, the first gas phase pipeline, the second gas phase pipeline and their related connections are not provided, and will not be described in detail here.

[0086] Comparative Example 2

[0087] This comparative example provides a separation device for the reaction material after the oxidation of benzene to phenol by nitrous oxide. Except that the benzene distillation middle boiler, the first gas phase pipeline and their connection relationship are not provided, the rest of the separation device is the same as Example 1, and no further details are given here.

[0088] Application Example 1

[0089] This application example provides a low-energy separation method for the reaction product after the oxidation of benzene to phenol by nitrous oxide. The low-energy separation method is performed using the apparatus of Example 1 and specifically includes:

[0090] The material of the laughing gas oxidation benzene to phenol is first separated by condensation and gas-liquid separation device, and a part of benzene is first returned to the reaction system of the laughing gas oxidation benzene to phenol, and the mixed liquid phase of the other part benzene and phenol is recorded as the reaction material. 30t / h, 40 ℃ of the described reaction material (benzene 54wt%, phenol 44wt%) enters the preheating device E5 and is first preheated to 130 ℃, and then sent to the benzene rectification tower body from the 10th theoretical plate to carry out benzene rectification. The top pressure of the benzene rectification tower body is 40kPa, and the temperature of the benzene rectification tower top gas phase is 53 ℃. The benzene rectification tower top gas phase enters the shell side of the benzene rectification tower top heat exchanger E1, and the tube side adopts circulating cooling water to condense. The condensate in the benzene rectification tower top heat exchanger E1 The benzene distillation tower enters the top liquid separator V1. A portion of the condensate is returned to the benzene distillation tower as reflux, while a portion is extracted as benzene and recycled to the nitrous oxide oxidation of benzene to phenol. Non-condensable gases are discharged to a flare for incineration. The reflux ratio of the benzene distillation is set at 2.5. A stream of 50 t / h of benzene distillation intermediate material (temperature 65°C) is extracted from the side line of the stripping section at the 12th theoretical plate and enters the tube side of the benzene distillation intermediate boiler E6. Through the first gas phase pipeline, it is passed to the shell side for heating the first gas phase stream (temperature 159°C) for the benzene distillation intermediate material. After heating (the heated temperature is 109°C), the benzene distillation intermediate material is returned to the lower tray of the extract to continue benzene distillation separation. Low-pressure steam is used to provide heat in the benzene distillation tower reboiler (E2), and the benzene distillation bottom material is extracted at the bottom discharge port of the benzene distillation tower.

[0091] The bottom material of the benzene distillation tower is fed into the phenol distillation tower body for phenol distillation. The top pressure of the phenol distillation tower benzene body is 50kPa and the temperature is 159°C. The gas phase at the top of the phenol distillation tower is divided into a first gas phase stream, a second gas phase stream and a third gas phase stream. 70wt% of the first gas phase stream is fed into the benzene distillation boiler for heating the benzene distillation intermediate material, 28wt% of the second gas phase stream is fed into the preheating device for preheating the reaction material, and 2w t% of the third gas phase stream is sent to the shell side of the heat exchanger at the top of the phenol distillation tower for condensation treatment. The tube side of the heat exchanger at the top of the phenol distillation tower is cooled by circulating cooling water. The condensate enters the liquid separator at the top of the phenol distillation tower. A portion of the condensate is returned to the phenol distillation tower body as reflux liquid, and the remaining condensate is extracted as the phenol product. The reflux ratio in the phenol distillation is set to 1.5. The reboiler at the bottom of the phenol distillation tower is heated by low-pressure steam, and the heavy components at the bottom of the tower are sent out of the boundary area for treatment.

[0092] Application Example 2

[0093] This application example provides a low-energy separation method for the reaction product after the oxidation of benzene to phenol by nitrous oxide. The low-energy separation method is performed using the apparatus of Example 2 and specifically includes:

[0094] The material of nitrous oxide oxidation benzene to produce phenol is first condensed and separated in a gas-liquid separation device. A portion of the benzene is first returned to the reaction system of nitrous oxide oxidation benzene to produce phenol, and the mixed liquid phase of the other portion of benzene and phenol is recorded as the reaction material. The reaction material at 30t / h and 40°C enters the preheating device and is first preheated to 100°C. It is then sent from the 15th theoretical plate to the benzene distillation tower body for benzene distillation. The top pressure of the benzene distillation tower body is 50kPa, and the temperature of the gas phase at the top of the benzene distillation tower is 59°C. The gas phase at the top of the benzene distillation tower enters the shell side of the benzene distillation tower top heat exchanger, and the tube side is condensed using circulating cooling water. The condensate in the benzene distillation tower top heat exchanger enters the benzene distillation tower top liquid separator. In the device, a portion of the condensate is returned to the benzene distillation tower body as reflux, and a portion of the condensate is extracted as benzene to be circulated to the nitrous oxide oxidation of benzene to phenol. The non-condensable gas is discharged to the torch for incineration. The reflux ratio of the benzene distillation is set to 2.5. The stripping section side line extracts a benzene distillation intermediate material (temperature is 68 ° C) with a flow rate of 40t / h at the 20th theoretical plate position and enters the tube side of the benzene distillation boiler. The first gas phase stream (temperature is 144 ° C) for heating the benzene distillation intermediate material on the shell side is passed through the first gas phase pipeline. After the benzene distillation intermediate material is heated (the temperature after heating is 104 ° C), it returns to the lower tower tray of the extract to continue benzene distillation separation. Low-pressure steam is used for heat supply in the benzene distillation tower kettle reboiler, and the benzene distillation bottom material is extracted at the benzene distillation tower bottom discharge port.

[0095] The bottom material of the benzene distillation tower is fed into the phenol distillation tower body for phenol distillation. The phenol distillation tower body is provided with 35 theoretical plates, and the feed position is the 20th theoretical plate. The top pressure of the phenol distillation tower benzene body is 30kPa, and the temperature is 144°C. The top gas phase of the phenol distillation tower is divided into a first gas phase stream, a second gas phase stream, and a third gas phase stream. 61wt% of the first gas phase stream is fed into the benzene distillation boiler for heating the benzene distillation intermediate material, and 18wt% of the second gas phase stream is fed into the preheater. The heat device is used to preheat the reaction material, 21wt% of the third gas phase stream is sent to the shell side of the heat exchanger at the top of the phenol distillation tower for condensation treatment, the tube side of the heat exchanger at the top of the phenol distillation tower is cooled by circulating cooling water, the condensate enters the top liquid separator of the phenol distillation tower, a part of the condensate is returned to the phenol distillation tower body as reflux liquid, and the remaining condensate is extracted as phenol product. The reflux ratio in the phenol distillation is set to 1.5, the reboiler at the bottom of the phenol distillation tower is heated by low-pressure steam, and the heavy components at the bottom of the tower are sent out of the boundary area for treatment.

[0096] Application Example 3

[0097] This application example provides a low-energy separation method for the reaction product after nitrous oxide oxidation of benzene to phenol. The low-energy separation method is carried out using the device of Example 3. During operation, routine adjustments are made to ensure stable operation of the device system. Other aspects are the same as those of Application Example 1.

[0098] Application Example 4

[0099] The difference from Application Example 1 is that external heat is used to ensure that the intermediate material of benzene distillation is heated to 115°C after completion, and is returned to the lower tower plate of the extract to continue benzene distillation separation. During operation, routine adjustments are made to ensure stable operation of the device system. Other aspects are basically the same as Application Example 1.

[0100] Application Example 5

[0101] This application example provides a low-energy separation method for the reaction product after the oxidation of benzene to phenol by nitrous oxide. The low-energy separation method is performed using the apparatus of Example 4 and specifically includes:

[0102] The material of phenol produced by oxidation of benzene by laughing gas is first condensed and separated by a gas-liquid separator, and a part of benzene is first returned to the reaction system of phenol produced by oxidation of benzene by laughing gas, and the mixed liquid phase of the other part of benzene and phenol is recorded as the reaction material. The reaction material at 30t / h and 40°C enters a preheating device and is first preheated to 130°C, and then is sent to a benzene distillation tower body from the 10th theoretical plate for benzene rectification. The top pressure of the benzene distillation tower body is 40kPa, and the temperature of the gas phase at the top of the benzene distillation tower is 53°C. The gas phase at the top of the benzene distillation tower enters the shell side of the benzene distillation tower top heat exchanger, and the tube side adopts circulating cooling water for condensation. The condensate in the benzene distillation tower top heat exchanger enters the benzene distillation tower top liquid separator, and a part of the condensate returns to the benzene distillation tower body as reflux. Part of the condensate is extracted as benzene and circulated to the phenol production process using benzene oxidized by laughing gas. The non-condensable gas is discharged to a flare for incineration. The reflux ratio of the benzene distillation is set to 2.5. The stripping section side line extracts a 25t / h benzene distillation intermediate material (temperatures of 99°C and 61°C, respectively) at the 16th and 13th theoretical plate positions, which enters the tube side of the benzene distillation boiler. The first gas phase stream (temperature of 159°C) is first passed into the benzene distillation boiler of the 16th theoretical plate and then into the shell side of the benzene distillation boiler of the 13th theoretical plate for heating the benzene distillation intermediate material. After heating, the benzene distillation intermediate material is returned to the lower tray of the extract to continue benzene distillation separation. Low-pressure steam is used to supply heat in the benzene distillation tower kettle reboiler, and the benzene distillation bottom material is extracted at the benzene distillation tower bottom discharge port.

[0103] The bottom material of the benzene distillation tower is fed into the phenol distillation tower body for phenol distillation. The phenol distillation tower body is provided with 20 theoretical plates, and the feed position is the 13th theoretical plate. The top pressure of the phenol distillation tower benzene body is 50kPa, and the temperature is 159°C. The top gas phase of the phenol distillation tower is divided into a first gas phase stream, a second gas phase stream and a third gas phase stream. 63wt% of the first gas phase stream is fed into the benzene distillation boiler for heating the benzene distillation intermediate material, and 30wt% of the second gas phase stream is fed into the benzene distillation boiler for heating the benzene distillation intermediate material. The preheating device is used to preheat the reaction material, and 7wt% of the third gas phase stream is sent to the shell side of the heat exchanger at the top of the phenol distillation tower for condensation treatment. The tube side of the heat exchanger at the top of the phenol distillation tower is cooled by circulating cooling water. The condensate enters the liquid separator at the top of the phenol distillation tower, and a part of the condensate is returned to the phenol distillation tower body as reflux liquid. The remaining condensate is extracted as a phenol product. The reflux ratio in the phenol distillation is set to 1.5. The reboiler at the bottom of the phenol distillation tower is heated by low-pressure steam, and the heavy components at the bottom of the tower are sent out of the boundary area for treatment.

[0104] Application Example 6

[0105] The difference from Application Example 5 lies in that the apparatus of Example 5 is used. A stream of 25 t / h of benzene distillation intermediate material (temperatures of 80°C and 67°C, respectively) is drawn from the stripping section sideline at both the 13th and 11th theoretical plate positions and fed into the tube side of the benzene distillation intermediate boiler. The first vapor phase stream (temperature of 159°C) is first passed into the benzene distillation intermediate boiler at the 13th theoretical plate and then into the shell side of the benzene distillation intermediate boiler at the 11th theoretical plate to heat the benzene distillation intermediate material. After heating (temperatures of 114°C and 99°C, respectively), the benzene distillation intermediate material is returned to the lower tray of the extract to continue benzene distillation separation. Conventional adjustments are made during operation to ensure stable operation of the apparatus system. All other aspects are essentially the same as those of Application Example 5.

[0106] Comparative Application Example 1

[0107] This comparative example provides a method for separating the reaction material after the oxidation of benzene to phenol by nitrous oxide. The difference between the separation method and Application Example 1 is that the device of Comparative Example 1 is used. The specific process is as follows:

[0108] The material of laughing gas oxidation benzene to phenol is first passed through after the separation of condensation and gas-liquid separator, and a part of benzene returns to the reaction system of laughing gas oxidation benzene to phenol first, and the mixed liquid phase of another part benzene and phenol is recorded as reaction after-material, 30t / h, 40 ℃ described reaction after-material enters and is sent into benzene rectification tower body (totally 20 theoretical plates) from the 10th theoretical plate and carries out benzene rectification, the top pressure of benzene rectification tower body is 40kPa, and the temperature of benzene rectification tower top gas phase is 53 ℃, benzene rectification tower top gas phase enters the shell side of benzene rectification tower top heat exchanger, and tube side adopts circulating cooling water to condense, condensate in the benzene rectification tower top liquid separator, a part of condensate returns benzene rectification tower body as reflux, a part of condensate extraction is circulated to laughing gas oxidation benzene to phenol as benzene, and non-condensable gas is discharged to flare and is incinerated, and the reflux ratio of benzene rectification is set to 2.5. Low-pressure steam is used to supply heat in the reboiler of the benzene distillation tower kettle, and the bottom material of the benzene distillation tower is taken out at the bottom discharge port of the benzene distillation tower.

[0109] The bottom material of the benzene distillation tower is fed into a phenol distillation tower body for phenol distillation. The phenol distillation tower body is provided with 20 theoretical plates, and the feed position is the 13th theoretical plate. The top pressure of the benzene body of the phenol distillation tower is 50 kPa, and the temperature is 159° C., wherein all the gas phase at the top of the phenol distillation tower is fed into the shell side of the heat exchanger at the top of the phenol distillation tower for condensation treatment. The tube side of the heat exchanger at the top of the phenol distillation tower is cooled by circulating cooling water. The condensate enters the top liquid separator of the phenol distillation tower, a part of the condensate is returned to the phenol distillation tower body as reflux liquid, and the remaining condensate is extracted as a phenol product. The reflux ratio in the phenol distillation is set at 1.5, the reboiler at the bottom of the phenol distillation tower is heated by low-pressure steam, and the heavy components at the bottom of the tower are sent out of the boundary area for treatment.

[0110] Application Comparative Example 2

[0111] This comparative example provides a method for separating the reaction material after the oxidation of benzene to phenol by nitrous oxide. The difference between the separation method and Application Example 1 is that the device of Comparative Example 2 is used. The specific process is as follows:

[0112] The material of laughing gas oxidation benzene to phenol is first passed through after the separation of condensation and gas-liquid separator, and a part of benzene returns to the reaction system of laughing gas oxidation benzene to phenol first, and the mixed liquid phase of another part benzene and phenol is recorded as reaction after-material, 30t / h, 40 ℃ described reaction after-material enters and is sent into benzene rectification tower body (totally 20 theoretical plates) from the 10th theoretical plate and carries out benzene rectification, the top pressure of benzene rectification tower body is 40kPa, and the temperature of benzene rectification tower top gas phase is 53 ℃, benzene rectification tower top gas phase enters the shell side of benzene rectification tower top heat exchanger, and tube side adopts circulating cooling water to condense, condensate in the benzene rectification tower top liquid separator, a part of condensate returns benzene rectification tower body as reflux, a part of condensate extraction is circulated to laughing gas oxidation benzene to phenol as benzene, and non-condensable gas is discharged to flare and is incinerated, and the reflux ratio of benzene rectification is set to 2.5. Low-pressure steam is used to supply heat in the reboiler of the benzene distillation tower kettle, and the bottom material of the benzene distillation tower is taken out at the bottom discharge port of the benzene distillation tower.

[0113] The bottom material of the benzene distillation tower is fed into a phenol distillation tower body for phenol distillation. The phenol distillation tower body is provided with 20 theoretical plates, and the feed position is the 13th theoretical plate. The top pressure of the benzene body of the phenol distillation tower is 50 kPa, and the temperature is 159° C. The gas phase at the top of the phenol distillation tower is divided into a second gas phase stream and a third gas phase stream. 30 wt % of the second gas phase stream is fed into a preheating device for preheating the reaction material, and 70 wt % of the third gas phase stream is fed into the shell side of the heat exchanger at the top of the phenol distillation tower for condensation treatment. The tube side of the heat exchanger at the top of the phenol distillation tower is cooled by circulating cooling water. The condensate enters the top liquid separator of the phenol distillation tower, and a portion of the condensate is returned to the phenol distillation tower body as reflux liquid. The remaining condensate is extracted as a phenol product. The reflux ratio in the phenol distillation is set at 1.5. The reboiler at the bottom of the phenol distillation tower is heated by low-pressure steam, and the heavy components at the bottom of the tower are sent out of the boundary area for treatment.

[0114] ASPEN was used to simulate the energy consumption test, where the composition after the reaction was 54 wt % benzene, 44 wt % phenol, and the temperature was 40°C.

[0115] The simulation test results of the above application examples and application comparison examples are shown in Table 1.

[0116] Table 1

[0117]

[0118]

[0119] From Table 1 we can see the following points:

[0120] (1) It can be seen from the comprehensive application examples 1 to 2 that the low-energy consumption separation device for the reaction material of phenol produced by oxidation of benzene with nitrous oxide provided by the present invention can not only increase the purity of recovered benzene to 99.9%, but also the utility energy consumption of the Zhengege separation system is very low, wherein circulating water can be saved by 47.96% and steam can be saved by 43.7%. Compared with the solution of comparative example 1, for 30t / h of reaction material, the circulating water of the present invention can save more than RMB 1.169 million / year and steam can save more than RMB 12.896 million / year, with obvious economic benefits.

[0121] (2) The influence of the boiler setting and its related connections in benzene distillation

[0122] By comparing Application Example 1 and Application Example 3, it can be seen that Application Example 3 adopts the low-energy separation device provided in Example 3, but the material collection port is located one tower plate below the material return port, resulting in the purity of the recovered benzene being only 97.6%, which is difficult to meet the demand for recycled benzene.

[0123] By comparing Application Examples 5 and 6, it can be seen that Application Examples 5 and 6 are carried out using the apparatus of Example 4 and Example 5, respectively. Both are equipped with two benzene distillation intermediate boilers, but the benzene distillation intermediate boilers in Example 4 are arranged at positions where the theoretical plates are 16 and 13, while the benzene distillation intermediate boilers in Example 5 are arranged at positions where the theoretical plates are 11 and 13 of the benzene distillation tower body, with a difference of only one theoretical plate between the two. Finally, the purity of the recovered benzene in Application Example 6 is 99.5%.

[0124] By comparing Application Example 1 with Application Comparative Examples 1 to 2, it can be seen that the present invention can significantly reduce circulating water consumption and steam energy consumption by providing a benzene distillation mid-boiler.

[0125] (3) Influence of return temperature of benzene distillation intermediate material after heating

[0126] By comparing Application Example 1 and Application Example 4, it can be seen that the temperature after heating in Application Example 4 is 115°C, resulting in the purity of the final recovered benzene not meeting the standard. This shows that the present invention controls the temperature difference between the heated benzene distillation intermediate material and the original tower plate temperature to be less than 45°C, which can ensure the purity of the recovered benzene.

[0127] The present invention uses the above-described embodiments to illustrate the detailed features of the present invention. However, the present invention is not limited to the above-described detailed features, which does not mean that the present invention must rely on the above-described detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the selected technical features of the present invention, additions to auxiliary technical features, and selections of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A low energy consumption separation device for the reaction material after the oxidation of benzene to phenol by laughing gas, characterized in that: The low-energy separation device includes a preheating device, a benzene distillation tower and a phenol distillation tower; The material inlet of the preheating device is connected to the outlet of the reaction device for oxidizing benzene to phenol with laughing gas; The benzene distillation tower comprises a benzene distillation tower body, a benzene distillation feed port and a benzene distillation intermediate boiler arranged in the middle of the benzene distillation tower body, and a benzene distillation tower bottom discharge port arranged at the bottom of the benzene distillation tower body; The phenol distillation tower comprises a phenol distillation tower body, a phenol distillation feed inlet arranged in the middle of the phenol distillation tower body, a phenol distillation tower top gas phase outlet arranged at the top of the phenol distillation tower body, and a phenol distillation tower top heat exchanger; The benzene distillation feed port is connected to the material outlet of the preheating device; the benzene distillation tower bottom discharge port is connected to the phenol distillation feed port; The gas phase outlet at the top of the phenol distillation tower is provided with a first gas phase pipeline, a second gas phase pipeline and a third gas phase pipeline. The first gas phase pipeline is connected to the heat exchange medium channel inlet of the benzene distillation boiler; the second gas phase pipeline is connected to the heat exchange medium channel inlet of the preheating device; the third gas phase pipeline is connected to the heat exchange medium channel inlet of the heat exchanger at the top of the phenol distillation tower.

2. The low energy consumption separation device according to claim 1, characterized in that: The benzene distillation tower further comprises a benzene distillation tower top heat exchanger and a benzene distillation tower top liquid separator which are arranged on the top of the benzene distillation tower body and are sequentially connected along the material conveying direction; Preferably, the lower part of the liquid separator at the top of the benzene distillation tower is provided with a circulation pipeline connected to the benzene distillation tower body, and a liquid phase material outlet at the top of the benzene distillation tower; Preferably, a benzene distillation gas phase material outlet is provided at the upper portion of the benzene distillation tower top liquid separator; Preferably, the benzene distillation tower further comprises a benzene distillation tower bottom reboiler arranged at the bottom of the benzene distillation tower body.

3. The low energy consumption separation device according to claim 1 or 2, characterized in that: The number of theoretical plates of the benzene distillation tower body is 10 to 50, preferably 20 to 35; Preferably, the feed position of the benzene distillation tower body is 3 to 25 theoretical plates; the boiler in the benzene distillation is arranged at a position where the theoretical plates are 4 to 32; Preferably, the number of the boilers in the benzene distillation is 1 to 3, preferably 1 to 2; the material extraction port of the boiler in the benzene distillation is located 1 to 2 theoretical plates above the material return port; Preferably, when at least two benzene distillation intermediate boilers are provided, the number of theoretical plates between two adjacent benzene distillation intermediate boilers is at least 2.

4. The low energy consumption separation device according to any one of claims 1 to 3, characterized in that: The phenol distillation tower further comprises a phenol distillation tower bottom reboiler and a phenol distillation tower bottom extraction port arranged below the phenol distillation tower body; Preferably, the phenol distillation tower further comprises a phenol distillation tower top liquid separator, and the phenol distillation tower top liquid separator is connected to the heat exchange medium channel outlet of the benzene distillation boiler, the heat exchange medium channel outlet of the preheating device, and the heat exchange medium channel outlet of the phenol distillation tower top heat exchanger; Preferably, a circulation pipeline connected to the phenol distillation tower body and a liquid phase material outlet at the top of the phenol distillation tower are provided at the lower part of the liquid separator at the top of the phenol distillation tower.

5. A low energy consumption separation method for the reaction material after the oxidation of benzene to phenol by laughing gas, characterized in that: The low-energy separation method is carried out using the low-energy separation device for the reaction material after the nitrous oxide oxidation of benzene to phenol according to any one of claims 1 to 4.

6. The low-energy separation method according to claim 5, characterized in that: The low-energy separation method comprises: The reaction material produced by the oxidation of benzene by laughing gas to produce phenol is first preheated in a preheating device and then sent to a benzene distillation tower body for benzene distillation, and the benzene distillation bottom material is extracted at the bottom discharge port of the benzene distillation tower; wherein, the benzene distillation intermediate material is extracted from the middle of the benzene distillation tower body, heated in a benzene distillation boiler, and then returned to the benzene distillation tower body; The bottom material of the benzene distillation tower is fed into the phenol distillation tower body for phenol distillation, and the phenol distillation tower top gas phase is extracted from the phenol distillation tower top gas phase outlet; Among them, the gas phase at the top of the phenol distillation tower is divided into a first gas phase stream, a second gas phase stream and a third gas phase stream. The first gas phase stream is sent to the benzene distillation boiler for heating the intermediate material of the benzene distillation, the second gas phase stream is sent to the preheating device for preheating the reaction material, and the third gas phase stream is sent to the heat exchanger at the top of the phenol distillation tower for condensation treatment.

7. The low-energy separation method according to claim 6, characterized in that: The temperature of the reaction material is 40-80° C. The composition of the reaction material includes: 40-65 wt% benzene, 35-60 wt% phenol; Preferably, the outlet temperature of the preheating device is 80-150°C, preferably 100-135°C; Preferably, the top temperature of the benzene distillation tower body is 46-66°C; Preferably, the bottom temperature of the benzene distillation tower body is 145-165°C; Preferably, the top pressure of the benzene distillation tower body is 20 to 80 kPa, preferably 30 to 50 kPa; Preferably, the reflux ratio of the benzene distillation tower is 0.5 to 3:

1.

8. The low-energy separation method according to claim 6 or 7, characterized in that: The temperature of the benzene distillation intermediate material extracted from the boiler in the benzene distillation is 60-100°C; Preferably, the temperature of the benzene distillation intermediate material returned from the boiler in the benzene distillation is 100-130°C; Preferably, when at least two benzene distillation intermediate boilers are provided, the difference in side-sampling temperature between two adjacent benzene distillation intermediate boilers is 20-40° C.; Preferably, the benzene distillation intermediate material is extracted from the stripping section, heated and partially vaporized in a benzene distillation boiler, and the obtained vapor-liquid two-phase is returned to the benzene distillation tower body for redistribution; Preferably, the ratio of the flow rate of the benzene distillation intermediate material extracted to the flow rate of the benzene distillation feed port is 0.5 to 2:

1.

9. The low-energy separation method according to any one of claims 6 to 8, characterized in that: The number of theoretical plates of the phenol distillation tower is 10 to 50, preferably 20 to 35; Preferably, the feed position of the phenol distillation tower is at the 3rd to 25th theoretical tray positions; Preferably, the top temperature of the phenol distillation tower is 120-200° C., preferably 130-180° C.; Preferably, the top pressure of the phenol distillation tower is 20 to 80 kPa, preferably 30 to 50 kPa.

10. The low-energy separation method according to any one of claims 6 to 9, characterized in that: The ratio of the first gas phase stream to the gas phase at the top of the phenol distillation tower is 30 to 70 wt %; Preferably, the ratio of the second gas phase stream to the gas phase at the top of the phenol distillation tower is 20 to 30 wt%.

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