WO2020191789A1

WO2020191789A1 - Plug flow distillation tray and method for preparing isophoron by liquid-phase condensation of acetone

Info

Publication number: WO2020191789A1
Application number: PCT/CN2019/080512
Authority: WO
Inventors: 何岩; 黎源; 田博; 边路路; 周锐; 员玫; 李金明; 孙媛媛
Original assignee: 万华化学集团股份有限公司; 万华化学（宁波）有限公司
Priority date: 2019-03-27
Filing date: 2019-03-29
Publication date: 2020-10-01
Also published as: CN110038317B; CN110038317A

Abstract

The present invention provides a plug flow distillation tray and a method for preparing isophorone by liquid-phase condensation of acetone. The plug flow distillation tray provided by the present invention comprises a tray and a plug flow assembly provided on the tray, the plug flow assembly comprising a downcomer, a leveled overflow weir, a light-heavy phase flow dividing element, a liquid receiving tray I and a flow guide element; the downcomer is connected to the tray, and the leveled overflow weir is provided on an inlet of the downcomer; the light-heavy phase flow dividing element is provided in the downcomer and is located below the leveled overflow weir; the liquid receiving tray I is connected to the tray, and is located on a side opposite to the side where the downcomer is connected to the tray; the flow guide element is provided above the junction of the liquid receiving tray I and the tray, and the flow guide element is provided with a plurality of flow guide passages. A pressurized reactive distillation column comprising the plug flow distillation tray of the present invention can be used for performing post-treatment of an IP (isophorone)/alkali liquid system which is easy to foam, so that the liquid phase can be distributed and flow relatively evenly, thereby facilitating the improvement of the reaction effect.

Description

Method for preparing isophorone by horizontal plug flow distillation tray and liquid phase condensation of acetone

Technical field

The invention relates to a reactive distillation tray and a process for preparing isophorone by using the reactive distillation tray.

Background technique

Isophorone is one of the important products of acetone deep processing, chemical name: 3,5,5-trimethyl-2-cyclohexen-1-one, English name: Isophorone (abbreviated as IP), molecular formula is C ₉ H ₁₄ O. Isophorone has a wide range of uses, with strong dissolving ability, good dispersibility, and good leveling. It is an excellent high boiling point green solvent. Because of its conjugated unsaturated ketone structure, it can be further reacted to obtain important products such as alcohols, acids, amines, esters and isocyanates, especially its downstream derivatives isophorone nitrile (IPN), isophorone diamine (IPDA), isophorone diisocyanate (IPDI) and oxoisophorone (KIP) are of great significance in the fields of specialty amines, polyurethanes and nutritional chemicals.

Industrially, isophorone is mainly prepared by acetone condensation. According to the contact state of the reactants, there are two methods for preparing isophorone by condensation of acetone: one is the pressurized liquid phase condensation in an alkaline solution; the other is the gas phase of gaseous acetone on the surface of the solid catalyst. Catalytic condensation method. At present, the liquid phase process is the mainstream industrial production method in the world.

The difficulty of the liquid-phase process is that the reaction is a typical series and parallel complex reaction network, which produces more by-products, resulting in lower selectivity of the target product isophorone, and greatly restricts the single-pass conversion of acetone in industry. rate. At the same time, under the reaction conditions, there are two liquid phases in the system, which puts forward high requirements for the mixing of the reaction liquid, the control of the flow field and the control of the product yield.

Historically, researchers have developed many methods to try to solve these problems. The early process used a tank reactor, such as the method disclosed in the US Published Patent US344226, adding 5 parts by mass of acetone and 4 parts by mass of a 20% NaOH aqueous solution into a stirred tank, and reacting at 150°C and 160PSI for 3 hours The conversion rate of acetone is 17%, and the selectivity of isophorone is 39%. In the method disclosed in the British publication GB583863, 25% NaOH solution is used as a catalyst, and a 90% acetone aqueous solution is reacted at 170° C. for 37 minutes, the acetone conversion rate is 13.6%, and the isophorone selectivity is 51%. The kettle type process has many side reactions, low single-pass yield, long process flow and high energy consumption.

BP company discloses a method for preparing isophorone by reactive distillation in DE2520681, US2399976 and US3981918. The reaction and rectification are integrated into a pressurized reaction rectification tower, and the disturbance of the gas phase is used to play a strong stirring effect. The acetone and the catalyst are fully contacted to react in the reaction section, and the resulting product immediately enters the separation section to recover unreacted acetone. At the same time, some high boilers produced by the condensation of acetone will decompose into acetone and isophorone, which improves the product yield. The technology disclosed in US2399976 uses NaOH as a catalyst, and the yield of isophorone is 78%; when KOH is used as a catalyst, the yield of isophorone is 74%-83%. When the acetone conversion rate in US3981918 is 10.4%, the selectivity of isophorone is 82%. Evonik in Germany has also continuously improved the process of acetone condensation to IP based on the reactive distillation process, such as CN201010625116, 201110140108 and other disclosed technologies.

However, in the above-mentioned existing technologies, the condensation of acetone and the hydrolysis reaction of reaction by-products are all limited to one reactive distillation column, and the reaction conditions are greatly restricted. But in fact, the reaction system for the preparation of IP from acetone is a complex reaction network in which numerous serial and parallel reactions exist simultaneously, and the optimal process conditions for each reaction are different. Traditionally, the process of restricting the reaction to one area simplifies the process to a certain extent, but it actually deviates the reaction control from the optimal conditions and pays the price of product yield loss. CN201110325830 and CN201110325843 disclose a reactive distillation process based on a basic catalyst and staged condensation, which further improves the yield of IP by optimizing the process.

Although the current reactive distillation process overcomes the shortcomings of some traditional processes, the traditional reactive distillation reactor used still has many problems: such as large liquid holding capacity, uneven liquid phase flow, many side reactions, and low distillation efficiency , The tray pressure drop is large (the pressure drop of the conventional technology single plate can exceed 2kPa), and the energy consumption is high. There is a complicated liquid-liquid-gas equilibrium system in the traditional liquid-phase condensation reaction process of acetone. In the conventional reactive distillation tray, the downcomer "pulsation" (the liquid-liquid flow is not flowing) will be caused by the liquid-liquid phase separation. Uniform and discontinuous, it is a stream of semi-intermittent pulsation), which reduces the effect of mixing and mass transfer and affects the efficiency of the rectification tower. Due to the liquid-liquid phase separation on the tray, the liquid-liquid two-phase flow will not be uniform, which will affect the reaction, especially in the process of hydrolysis shrinkage and valuable products in the by-products. At the same time, because the reaction requires a longer residence time, generally a high liquid phase holding capacity is required. Traditional tray technology has poor distillation efficiency and actual recovery effect for high holding liquid and liquid-liquid phase separation systems, and the operating pressure The reduction is very high, the energy consumption and production cost are very high, which is not satisfactory.

For the reactive distillation process with a slow reaction rate and a larger liquid holding capacity, the traditional tray is limited by technology and needs to be met by increasing the number of plates, which increases the difficulty of equipment manufacturing and the amount of investment. At the same time, because the gas phase has to pass through the liquid phase, for a reactive distillation tray with a large liquid holdup, the energy consumption caused by the total pressure drop of the tower and the increase in the temperature of the bottom of the tower are generally unacceptable. The reaction system of acetone has a particularly important value: the reaction network for the preparation of IP by condensation of acetone contains a large number of series of reactions. Excessive temperature will significantly reduce the selectivity of IP products, and significantly increase the difficulty of post-processing and IP refining and purification procedures. It is almost unacceptable for industrial devices pursuing economic efficiency. However, the hydrolysis reaction speed of some high-color substances in the IP system is slow and requires a longer residence time, which means that a larger tray holding capacity is required. For the process using traditional rectification trays, This means that the pressure drop increases sharply, the foaming is serious, and the liquid-liquid phase separation causes problems such as uneven liquid phase mixing and uneven flow. These problems significantly restrict the removal of high-color substances in the process using traditional tray technology.

In addition, the IP and lye system is a strong and easy foaming system, and a very serious foaming phenomenon will occur under the traditional rectification tower, which greatly reduces the rectification efficiency and even brings safety hazards. For the existing technology of acetone pressurized reactive distillation to prepare IP, traditional distillation trays such as sieve trays, bubble caps and valve tray technology are used; the above-mentioned trays are essentially bubble distillation towers. In terms of scope, the operation form of bubbling determines that the film pulling and bubbling effect on the liquid is inevitable during the process of bubbles passing through the liquid layer and gradually merging and growing. It is inevitable for the fine foaming system similar to IP/lye. In terms of distillation, serious foaming often causes serious dry board, back-mixing, flooding, etc., and even serious "liquid shock", causing damage to the equipment. In CN201110140108, technicians use traditional rectification trays. In order to avoid problems caused by severe foaming, an additional defoamer is added to the rectification column to inhibit system foaming. Although it can suppress the problems caused by foaming to a certain extent, it also brings a series of problems such as the introduction of other components to pollute the reaction system, the difficulty of wastewater treatment, the waste of catalysts, and the decomposition and loss of defoamers under severe conditions. .

Summary of the invention

The invention provides a flat-plug flow rectification tray. In the process of preparing isophorone by liquid-phase condensation of acetone, a pressurized reaction rectification tower containing the flat-plug flow rectification tray of the present invention is used for easy foaming The post-treatment of IP (isophorone)/lye system can make the liquid phase more evenly distributed and flow, which is beneficial to improve the reaction effect.

The present invention provides the following technical solutions:

One aspect of the present invention provides a flat-plug flow rectification tray, which is particularly suitable for the process of preparing isophorone by liquid-phase condensation of acetone.

The flat-plug flow rectification tray provided by the present invention includes a tray and one or more sets of flat-plug flow components arranged on the tray. The flat-plug flow components include a downcomer, a grading overflow weir, and light and heavy phases. Diversion element, receiving plate I and flow guiding element;

The downcomer is connected to the tray, the upper part of the downcomer is provided with an inlet, the grading overflow weir is provided on the inlet of the downcomer, and the downcomer is provided with a vertical flow channel The light and heavy phase splitting element is arranged in the downcomer and located below the grading overflow weir, and is used to receive the material liquid overflowing from the tray through the overflow weir to the vertical flow channel of the downcomer, and Separate the light phase material liquid and the heavy phase material liquid from the material liquid and drain the two through different channels to the bottom of the downcomer;

The liquid receiving tray I is connected to the tray, and is located on the opposite side of the side where the downcomer is connected to the tray;

The flow guide element is arranged above the connection between the liquid receiving tray I and the tray, and the flow guide element is provided to enable the material liquid on the liquid receiving tray I to be divided into multiple streams to guide the tower Multiple diversion channels of the disc.

Preferably, an outlet weir is formed at the junction of the receiving tray I and the tray, and the flow guiding element is located above the outlet weir.

Preferably, the outlets at the bottom of the light phase channel and the heavy phase channel respectively include a plurality of discontinuous channel outlets, that is, a plurality of independent channel outlets, so as to play a role similar to a liquid distributor, with liquid (or liquid) Distribution function.

Preferably, the downcomer includes a downcomer plate and a back plate, the downcomer plate is connected to the tray, the back plate and the downcomer plate are enclosed to form the vertical flow channel, and the back plate Higher than the grading overflow weir.

It is further preferred that the number of stages of the grading overflow weir is ≥1, wherein the first-stage overflow weir is provided on the downcomer plate, and it is further preferred that the first-stage overflow weir is provided with a plurality of different heights. The overflow hole; preferably the number of stages of the grading overflow weir ≥ 2, when the number of stages of the grading overflow weir ≥ 2, from the downcomer plate to gradually away from the downcomer plate and toward the direction of the downcomer cavity , The overflow weirs at all levels are arranged at intervals and their heights increase sequentially, and the height difference between the adjacent two overflow weirs is 50-150mm.

In a preferred embodiment, the guide element includes a set of guide vanes arranged above the outlet weir; the outlet weir includes a first edge of the outlet weir connected to the liquid receiving tray I and an outlet weir connected to the tray Second edge

The set of guide vanes are arranged at intervals along the first edge of the outlet weir above the outlet weir. The guide channels are formed between adjacent guide vanes, and each guide channel is directed from the liquid receiving plate I to the tower. The direction of the disk goes through;

The angle between each guide vane and the vertical line of the first edge of the outlet weir is ≥0° and <90°, and the vertical line refers to the plane located on the tray connected to the outlet weir. And a vertical line perpendicular to the first edge of the outlet weir; the angle between the adjacent guide vanes and the vertical line of the first edge of the outlet weir is the same or different. Preferably, each guide vane is arranged obliquely from one end of the first edge of the outlet weir close to the middle of the tray toward the end of the first edge of the outlet weir close to the tower wall; preferably the guide vanes closer to the first edge of the outlet weir The greater the angle with the perpendicular.

In a preferred embodiment, the outlet weir is arranged obliquely, and the bottom of the outlet weir is connected to the receiving tray I through the first edge of the outlet weir, and the top of the outlet weir is connected to the tray I through the second edge of the outlet weir. , The angle between the outlet weir and the receiving tray I is an obtuse angle; the outlet weir has the function of making the material liquid flow from the receiving tray I to the tray in an oblique upward direction.

In some preferred embodiments, the light-heavy-phase flow dividing element includes a liquid-receiving pan II, a split weir, a heavy phase channel, and a light-phase channel. The split weir is arranged on the liquid-receiving pan II and the liquid-receiving pan II It is divided into a heavy phase receiving area and a light phase receiving area; the heavy phase receiving area is located on the same side of the grading overflow weir in the downcomer and is located below the grading overflow weir, so that the grading overflow The material flow overflowing from the weir into the downcomer tends to flow into the heavy phase receiving area;

The heavy phase channel is used to divert the heavy phase material liquid deposited at the bottom or bottom of the heavy phase liquid receiving zone to below the downcomer;

The light-phase liquid receiving area is used to receive the light-phase material liquid from the upper part of the heavy-phase liquid-receiving area overflowed by the divided weir, and the light-phase channel is used to divert the light-phase material liquid from the light-phase liquid receiving area to Below the downcomer;

Preferably, the heavy phase channel is provided with a partition plate, the partition plate is provided with drainage ports, the inlet and the outlet of the heavy phase channel are respectively located on both sides of the partition plate, and the drainage port The lower edge of is higher than the upper edge of the entrance of the heavy phase channel, preferably the height difference between the two is 20-100mm;

Preferably, a baffle plate is also provided in the downcomer, and the baffle plate is arranged in the space between the grading overflow weir and the light-heavy phase dividing element, and is located in the downcomer with a grading overflow. The opposite side of one side of the weir, so that the material flow overflowing into the downcomer through the staged overflow weir tends to flow to the heavy phase receiving area.

In a preferred embodiment, the flat-plug flow assembly further includes a riser pipe and a spray hood. The riser pipe is provided on the tray and is located in the area between the staged overflow weir and the liquid receiving tray I. The riser pipe is provided with There are gas-phase channels used to guide the gas-phase upwards under the tray;

The spray hood is arranged on the riser pipe, and a gap used as a lower suction hole is left between the bottom of the spray hood and the tray; the lower part of the spray hood is provided above the lower suction hole The upper liquid suction hole of the spray cover is provided with a spray hole, and the position of the spray hole is higher than the outlet of the gas phase passage of the gas riser;

A gas guide vane is installed on the outside of the jet hood to guide the jet stream ejected from the jet hole to reduce the collision between the jet stream jets ejected from each jet hole; preferably the gas guide The flow sheet is arranged beside the jet hole;

Preferably, a foam breaking plate is further provided outside the spray hood, and the foam breaking plate corresponds to the position of the spray hole; preferably, the distance between the foam breaking plate and the spray hole is 1-200 mm, more preferably 10-200 mm. 100mm; the surface of the foam breaking plate is smooth or rough, preferably a rough surface, more preferably the foam breaking plate has spikes;

Preferably, the part of the spray cover provided with the upper liquid suction hole is formed with a constricted structure that is recessed into the spray cover.

In a preferred embodiment, the height of the highest-level overflow weir of the staged overflow weir is between 30-1000m; the height of the lift pipe is 10-50mm, preferably 20-40mm, lower than the highest-level overflow weir.

In some specific embodiments, the cross-section of the riser pipe is circular or rectangular, and the cross-sectional shape of the jet hood is correspondingly circular or rectangular;

In some specific embodiments, the shape of the upper liquid suction hole is rectangular, trapezoidal, circular or elliptical, or a trapezoidal, rectangular, circular or elliptical shape with teeth gaps;

In some preferred embodiments, the ratio of the open area of the upper liquid suction hole to the lower liquid suction hole is 10-1:1;

In some preferred embodiments, when the cross section of the spray hood is circular, the diameter of the spray hood at the necking structure is 50%-99% of the diameter of other parts of the spray hood; When the cross section is rectangular, the width of the spray hood at the necking structure is 50%-99% of the width of the rest of the spray hood;

In some specific embodiments, the shape of the injection hole is circular, rectangular, triangular or oblong, preferably the injection hole is a rectangular hole or an oblong hole, and the length ratio of the long and short sides of the injection hole is 1-20:1, preferably 1.5-10:1;

In some preferred embodiments, the angle between the gas deflector and the tangential direction of the injection hole surface is 1-90°, preferably 1-45°; the gas deflector is provided next to each injection hole, Preferably, the included angles between the adjacent gas guide vanes and the tangential direction of the corresponding injection hole surface are the same or different, and the same angle is preferably used.

The second aspect of the present invention provides a pressurized reactive rectification tower, which is provided with multiple layers of the above-mentioned flat plug flow rectification trays arranged up and down at intervals.

In a preferred embodiment, in the two adjacent layers of flat-plug flow distillation trays, one of the receiving trays I on the flat-plug flow distillation tray of the next layer corresponds to the flat-plug flow distillation tray of the upper layer. Just below a downcomer on the distillation tray, the receiving tray I is used to receive the light and heavy phase splitting elements in the downcomer (from the upper level of the flat plug flow distillation tray) directly above it Light phase material liquid and heavy phase material liquid separated from

The area between the connection between the receiving tray I and the tray and the bottom of the downcomer of the upper layer of the flat push-flow rectification tray is provided with the material liquid outlet of the receiving tray I, and the material liquid on the receiving tray I passes through The material liquid outlet can flow to the tray;

Preferably, an outlet weir is formed at the junction of the receiving tray I and the tray; the guide element is located on the material and liquid outlet of the receiving tray I, and is located above and above the outlet weir. Below the downcomer of the flat push-flow distillation tray.

In a preferred embodiment, a set of plug flow components are provided on the flat plug flow rectification tray of the upper layer, and a set of plug flow components corresponding to it are provided on the flat plug flow rectification tray of the next layer. Components, and the downcomers of the corresponding plug flow components from the adjacent plug flow rectification trays are arranged in a staggered arrangement;

Preferably, in the flat-plug flow distillation trays of each adjacent upper and lower layer, the length of the flow passages for the liquid-phase material flow from the material liquid outlet of the liquid receiving tray I of the flat-plug flow assembly to the staged overflow weir are all equal.

The present invention also provides a method for preparing isophorone by liquid phase condensation of acetone, which is further improved on the basis of the technology disclosed in CN201110325830 and CN201110325843.

The method for preparing isophorone by liquid phase condensation of acetone provided by the present invention includes the following steps:

1) Acetone and catalyst solution undergo aldol condensation reaction in the condensation reaction section;

2) The liquid-phase stream containing the reaction product obtained in step 1) enters the hydrolysis reaction section, and the by-products (ie, high-molecular-weight by-products in the condensation reaction product) contained in the liquid-phase stream containing carbon atoms ≥ 12 and water Contact and hydrolyze to recover part of the valuable components; the hydrolysis reaction section is carried out in a pressurized reactive distillation tower equipped with a flat plug flow distillation tray; the pressurized reactive distillation tower is the above The pressurized reactive distillation tower;

3) Separating the liquid phase stream obtained after step 2) hydrolysis to obtain isophorone.

By adopting the pressurized reactive distillation tower of the present invention to carry out the above process, the raw material acetone can be condensed to produce isophorone products with higher yield, reducing by-products, and significantly reducing downstream separation energy consumption and production costs.

In the acetone liquid phase condensation process, the high boilers with carbon atoms ≥ 12 obtained by the deep condensation of acetone are hydrolyzed in a pressurized reactive distillation tower, and unreacted light components are obtained at the top of the tower, which are condensed into a liquid state by a condenser and then recycled Continue to participate in the reaction in the upstream process section. The product obtained at the bottom of the tower contains condensation products and catalyst solution. After passing through an oil-water separator, it is divided into two phases of oil and water. The oil phase is mainly isophorone and by-product organics, and the water phase is mainly water and catalyst solution.

The liquid phase stream containing the reaction product obtained in step 1) is mainly composed of water and valuable organic matter. The valuable organic matter includes IP generated by the liquid-phase condensation reaction of acetone and high-boiling matter (such as xylose). Xylitone and Isoxylitone, etc.), and contains a small amount of acetone, diacetone alcohol, mesityl oxide, mesitylene, etc.

In the step 1), the condensation reaction section includes two or more condensation reaction sections connected in series, that is, the acetone aldol condensation reaction is carried out in at least two reaction process sections; preferably, the temperature of the aldol condensation reaction of each condensation reaction section is 190-280°C, preferably the temperature of the aldol condensation reaction in the first condensation reaction stage is 200-280°C.

In a preferred embodiment, the step 1) includes a first condensation reaction section and a second condensation reaction section, and through the first condensation reaction section, an acetone conversion rate of ≤10%, preferably acetone conversion rate of ≤8% is obtained. ; In the second condensation reaction section, acetone continues to react to obtain more IP (isophorone) products.

In some specific embodiments, the first condensation reaction stage can be carried out in the upper tray of the reactive distillation column, or can be carried out in a separate reactor, which is not particularly limited. For example, it can be carried out in a tubular reactor with a static mixer or a micro-channel mixer arranged in series before the reactive distillation column, or directly in a reactive distillation column reactor; more preferably a static mixer or a micro-channel mixer Tubular reactor with channel mixer.

Preferably, the second condensation reaction stage can be carried out in a conventional reactive distillation tower, or in a pressurized reactive distillation tower reactor provided with a flat plug flow distillation tray (referred to as pressurized Reactive distillation tower). Further preferably, the second condensation reaction section and the hydrolysis reaction section in step 2) are carried out in the same pressurized reactive distillation tower. In the pressurized reactive distillation tower, the upper part is the condensation reaction section and the lower part It is the hydrolysis reaction section. The trays provided in the pressurized reactive rectification tower can all be the flat plug flow rectification tray provided by the present invention, or part of the conventional trays available in the art (such as the pressure reactive rectification tower The upper part adopts this conventional tray), while part of it is the flat plug flow distillation tray provided by the present invention (for example, the lower part of the pressurized reactive distillation tower adopts the present invention tray), and the former is preferred.

It is preferable to use different process temperatures and raw material ratios in different condensation reaction sections; for example, for a two-stage condensation reaction process, the reaction temperature of the first condensation reaction section is operated at least 10°C higher than the second condensation reaction section. For example, it is 10-50°C higher than the second condensation reaction zone, preferably 10-20°C. The mass ratio (or mass flow ratio) of acetone and water in the first condensation reaction section is preferably 4-10:1; the mass ratio of acetone and water (or mass flow ratio) in the second condensation reaction section is preferably 4:1 -1:4, more preferably 4:1-1:2.

In the two-stage condensation reaction scheme, it is preferred that the second condensation reaction stage adopts a pressurized reactive distillation tower reactor at a temperature of 190-260°C and 20-60 Bar(A); preferably the temperature is 200-240°C, The pressure is 25-40 Bar (A); the second condensation reaction section in the pressurized reaction rectification tower preferably adopts a plate tower with a liquid residence time of 30-180 min, preferably 60-120 min.

In the method of the present invention, the catalyst solution may be an aqueous solution containing KOH or NaOH, and the amount of the catalyst accounts for 0.001 to 1% of the total mass flow of the reactants, preferably 0.01 to 0.1%.

The technical solution provided by the present invention has the following beneficial effects:

Based on the technologies disclosed in CN201110325830 and CN201110325843, the present invention further optimizes the process for preparing isophorone by liquid-phase condensation of acetone. A new type of flat plug flow distillation tray is provided. The use of the tray in a pressurized reaction rectification tower facilitates the uniform distribution and flow of the liquid phase, which is close to the flat plug flow flow; at the same time, it is beneficial to solve the existing reactive distillation In the process, the traditional reactive distillation trays have problems such as low rectification efficiency, serious foaming, liquid-liquid phase separation, uneven liquid flow, and large pressure drop on the trays. Based on the reactive distillation tower of the flat-plug flow distillation tray of the present invention, the process of preparing isophorone by liquid-phase condensation of acetone can realize the defoaming of IP/lye streams without additional chemical additives. , Uniform flow and efficient operation; thereby providing a strong foundation for improving reaction efficiency, reducing product color numbers, reducing tray pressure drop, and simplifying production processes.

Description of the drawings

Figure 1 is a schematic diagram of the cylindrical spray hood and riser in an example;

Figure 2 is a schematic diagram of the structure of the spray hood and the foam breaker when the cylindrical spray hood in an example is viewed from above;

Figure 3 is a schematic diagram of the rectangular jet hood and riser structure in an example;

Figure 4 is a partial schematic top view of the arrangement of the rectangular spray hood and the foam plate on the tray in an example;

Figure 5 is a schematic diagram of the reaction process for preparing IP by liquid phase condensation of acetone.

Figure 6a is a schematic diagram of the positional relationship between the downcomer and the liquid receiving tray of the adjacent-layer flat plug flow distillation tray;

Fig. 6b is a partial schematic diagram illustrating the structure of the flow guiding element in the top view of Fig. 6a;

Figure 7a: Schematic diagram of the downcomer arrangement with multiple downcomers on the flat plug flow distillation tower plate;

Figure 7b: a schematic diagram of the arrangement of multiple downcomers provided on the flat plug flow rectification tower plate adjacent to the lower layer of Figure 7a;

Figure 8: In an example, the structure diagram of the adjacent upper and lower horizontal plug flow rectification trays arranged in the rectification tower.

Description of some reference signs: 1, 2-Push flow distillation tray, 3, 4- tray, 5- downcomer, 6, 7-receiving tray I, 9-stage overflow weir, 13- light and heavy Phase dividing element, 14-baffle, 15-back plate, 16-downcomer plate, 17, 27-spray cover, 19-rise gas pipe, 20-flow guide element, 21-spray hole, 22, gas guide vane , 23- defoaming plate, 24-necking structure, 25- lower suction hole, 26- upper suction hole, 34- outlet weir, 37- light phase receiving area, 38- heavy phase receiving area, 39- Light phase channel, 40-heavy phase channel, 41-division weir, 42-divider, 43-drainage port, 45-heavy phase channel inlet, 46-heavy phase channel outlet, 48-horizontal plug flow assembly, 49-receiving Liquid plate II, 201-guide channel, 202-guide vane.

detailed description

In order to better understand the technical solution of the present invention, the content of the present invention will be further described below with reference to the drawings and embodiments, but the content of the present invention is not limited to the following embodiments.

The present invention provides a flat plug flow distillation tray. Figure 8 shows a partial schematic diagram of a pressurized reactive distillation tower, which shows a schematic diagram of the upper and lower two layers of flat plug flow distillation trays 1 and 2 ; The figure does not fully show the structure of the plug flow distillation trays of other layers. Hereinafter, taking the figure 8 as an example, the flat plug flow distillation tray of the present invention will be described. Taking the flat plug flow distillation tray 1 as an example, the flat plug flow distillation tray includes tray 3 and flat plug flow assembly 48. The flat plug flow assembly 48 includes downcomer 5, graded overflow weir 9, and light and heavy phase splitting elements. 13. The liquid receiving pan I 6 and the guide element 20.

Referring to Fig. 8, the downcomer 5 is connected to the tray 3, and the downcomer 5 is provided with an inlet, which is located on the upper part of the downcomer. The graded overflow weir 9 is arranged on the inlet of the downcomer 5, and a vertical flow channel is formed in the downcomer 5. The material liquid on the tray 3 can overflow into the vertical flow channel of the downcomer 5 by the staged overflow weir 9. The light-heavy phase splitting element 13 is arranged in the downcomer 5 and located below the graded overflow weir 9; the light-heavy phase splitting element 13 is used to receive the vertical overflow from the tray 3 through the overflow weir 9 to the downcomer 5 The material liquid in the flow channel, and separate the light phase material liquid and the heavy phase material liquid from these material liquids, the light and heavy phase splitting element 13 is also used to divert the light phase material liquid and the heavy phase material liquid to the down liquid through different channels Below tube 5. The liquid receiving tray I 6 is connected to the tray 3, and the connection position with the tray 3 is the opposite side of the side where the downcomer 5 and the tray 3 are connected. Above the connection between the liquid receiving tray I 6 and the tray 3 is provided a guide element 20, and the guide element 20 is provided with a plurality of streams for diverting the liquid on the liquid receiving tray I6 to the tray 3 in multiple streams. A diversion channel. An outlet weir 34 is preferably formed at the connection between the liquid receiving tray I and the tray, and the flow guiding element 20 is located above the outlet weir 34.

In a preferred embodiment, referring to Fig. 8, Fig. 6a, and Fig. 6b, the outlet weir 34 is arranged obliquely, and the whole is in a slope shape. Taking Figures 6a-6b as an example, the bottom of the outlet weir 34 is connected to the tray I7 through the first edge of the outlet weir 341, the top of the outlet weir 34 is connected to the tray 4 through the second edge of the outlet weir 342, and the outlet weir 34 is connected to the receiving tray. An obtuse angle is formed between I7, so that the outlet weir 34 forms an inclined upward ramp between the liquid receiving tray I7 and the tray 4. The outlet weir is arranged in a slope shape, so that when the material liquid overflows from the liquid receiving pan I to the tray via the outlet weir, it is guided upward by the outlet weir, which facilitates the uniform distribution of light and heavy liquids.

In a preferred embodiment, as shown in FIG. 8 and FIG. 6a, the light-heavy phase diversion element 13 specifically includes a liquid receiving pan II 49, a dividing weir 41, a heavy phase channel 40, and a light phase channel 39. Among them, the dividing weir 41 is arranged on the liquid receiving pan II49, and the liquid receiving pan II 49 is divided into a heavy phase liquid receiving area 38 and a light phase liquid receiving area 37. The heavy-phase liquid receiving area 38 is located in the downcomer 5 and below the graded overflow weir 9, and is located on the same side as the graded overflow weir 9, so that the material flow in the downcomer 5 overflows from the graded overflow weir 9 Will preferentially flow into the heavy phase receiving area 38, that is, tend to flow into the heavy phase receiving area 38, so that the material can be deposited in the heavy phase receiving area 38, and then the heavy phase material liquid forming the lower layer and the light phase material of the upper layer can be separated Liquid, which plays a role in liquid phase separation. The heavy phase channel 40 is used to divert the heavy phase material liquid deposited at the bottom or bottom of the heavy phase liquid receiving zone 38 to below the downcomer 5. The light-phase liquid receiving area 37 is used to receive the light-phase material liquid from the upper part of the heavy-phase liquid-receiving area 38 overflowed by the dividing weir 41, and the light phase channel 39 is used to divert the light-phase material liquid in the light-phase liquid receiving area 37 To the bottom of the downcomer 5. By providing the heavy phase channel 40 and the light phase channel 39, the light phase material liquid and the heavy phase material liquid can respectively flow to the space below the downcomer 5 through separate channels.

In some preferred embodiments, referring to Figures 8 and 6a, a partition plate 42 is provided in the heavy phase channel 40, and a drainage port 43 is provided on the partition plate 42. The inlet 45 and the outlet 46 of the heavy phase channel 40 are located on both sides of the partition plate 42 rather than on the same side with respect to the partition plate 42. In some specific embodiments, the heavy-phase channel 40 is specifically configured to form a channel by enclosing the heavy-phase drainage plate 44 and the dividing weir 41. The lower edge of the heavy-phase drainage plate 44 and the bottom of the heavy-phase liquid receiving area 38 are left The spacing is used as the entrance 45 of the heavy phase channel; and the partition plate 42 is vertically arranged in the heavy phase channel 40 and connected to the receiving plate II 49; on the receiving plate II in the area between the partition plate 42 and the dividing weir 41 An opening 46 is provided as the outlet of the heavy phase channel. The lower edge of the drainage port 43 is higher than the lower edge of the heavy phase drainage plate 44 (that is, the upper edge of the inlet 45 of the heavy phase channel), and the height difference between the two is preferably 20-100mm, which can also be called the liquid seal height ( See Figure 6a), the height difference can play a role of liquid seal. The vertical distance between the lower edge of the heavy phase guide plate 44 and the bottom 36 of the heavy phase liquid receiving area 38 is preferably 20-200 mm.

In some specific embodiments, referring to Fig. 8, the light phase channel 39 is formed by a member with an internal pipe provided in the light phase receiving area 37. Preferably, the internal pipe inlet of the member is a vertical distance from the bottom of the light phase receiving area. , The internal pipe outlet of the component leads to the area under the downcomer.

The specific shapes of the outlets of the light phase channel 39 and the heavy phase channel 40 are not particularly limited. For example, they can be elongated, round, square, etc., and can also be composed of multiple channel outlets distributed at intervals. The outlets at the bottom of the phase channel 40 are respectively arranged to include a plurality of mutually discontinuous channel outlets, that is, each outlet is independently arranged and discontinuous to each other. Play a role similar to a liquid distributor. As a specific example, referring to Figures 6a and 6b, the light phase channel is provided with a long strip-shaped outlet or the heavy phase channel is provided with a plurality of spaced outlets. This is only an example and is not limited to these forms. .

Taking FIG. 6b as an example, each guide channel 201 in the guide element 20 penetrates from the liquid receiving tray I7 to the direction of the tray 4. In a preferred embodiment, in order to facilitate a more uniform flow of the material and liquid on the tray, as shown in Figure 6b, the guide element 20 includes a set of guide vanes arranged above the outlet weir, and a group of guide vanes specifically includes a plurality of guide vanes. Flow fins 202, a plurality of guide fins 202 are sequentially spaced above the outlet weir 34 along the first edge 341 of the outlet weir. Diversion channels 201 are formed between adjacent guide fins 202, and each guide channel is formed by a liquid receiving plate. I penetrates in the direction of the tray. The angle between each guide vane and the vertical line of the first edge 341 of the outlet weir is ≥0° and <90°, and the vertical line is located on the plane of the tray 4 connected to the outlet weir, And a perpendicular line perpendicular to the first edge 341 of the outlet weir. The angles between adjacent guide vanes and the vertical line of the first edge of the outlet weir are the same or different. Preferably, each guide vane is arranged obliquely from an end of the first edge of the outlet weir close to the middle of the tray (or a position close to the middle of the tray) to the direction of the first edge of the outlet weir close to the end of the tower wall. Preferably, the angle between the guide vanes at both ends of the first edge of the outlet weir and the perpendicular is larger. In a specific embodiment, the gap between the guide vane closest to the tower wall and the tower wall also forms a channel, and its function is the same as that of the guide channel, which can also make the material liquid flow from the liquid receiving tray I to the tray. The baffle can be fixed by welding, for example, fixed on the receiving tray, outlet weir and/or tray.

In a preferred embodiment, referring to Figures 8 and 6a, a baffle 14 is also provided in the downcomer 5, and the baffle 14 is provided in the space between the graded overflow weir 9 and the light-heavy-phase dividing element 13, and Located in the downcomer 5 on the side opposite to the side where the overflow weir 9 is provided, in FIG. 8, the baffle 14 is located directly above the light phase liquid receiving area 37. After the material liquid overflows into the downcomer 5, if the direction deviates from the heavy phase liquid receiving area 38, the material liquid can tend to flow into the heavy phase liquid receiving area 38 through the action of the baffle 14, that is, make most of the material liquid. The liquid can enter the heavy phase receiving zone for liquid phase separation.

Referring to Fig. 8, the downcomer 5 specifically includes a downcomer plate 16 and a backing plate 15. The downcomer plate 16 is connected to the tray 3, for example, the downcomer plate 16 is vertically installed on the tray 3; the backing plate 15 and the downcomer plate 16 is enclosed to form a vertical flow channel. The specific shape of the downcomer 5 is not particularly limited, for example, it is a bow-shaped, rectangular or polygonal box-type downcomer. The back plate 15 is higher than the grading overflow weir 9, so as to prevent the material from overflowing from the back plate. In some specific embodiments, the baffle 14 and the back plate 15 are connected, and the liquid receiving plate II49 is connected between the downcomer plate 16 and the back plate 15.

The number of stages of the graded overflow weir 9 is greater than or equal to 1, for example, there are overflow weirs of 1, 2, or 3 or more. The meaning of the number of stages refers to the number of overflow weirs of different heights. Fig. 8 shows a specific example with a three-stage overflow weir. Among them, the one-stage overflow weir 12 is arranged on the downcomer plate 16, specifically formed by the downcomer plate 16 extending upward, higher than the tray 3 A flat surface forms an overflow weir; a plurality of overflow holes 47 of different heights are preferably opened on the first-level overflow weir 12 to ensure that the upper, middle and lower liquid layers on the tray 3 can overflow. Preferably, the number of stages of the staged overflow weir 9 is ≥2. When the stage number of the staged overflow weir 9 is ≥2, from the downcomer plate 16 to the direction gradually away from the downcomer plate 16 and towards the inner cavity of the downcomer 5, The overflow weirs 9 are arranged at intervals and increase in height. Taking Fig. 8 as an example, the second-stage overflow weir 11 is higher than the first-stage overflow weir 12, and the third-stage overflow weir 10 is higher than the second-stage overflow weir 11. The use of overflow weirs of different heights can ensure the uniformity of the liquid phase flow at different heights on the tray; more than two overflow channels are formed between the overflow weirs to facilitate the horizontal push of the liquid phase in the vertical direction The design of the overflow weir with more than two stages can also effectively suppress the foam in the downcomer for the easy-foaming IP/lye system, and significantly reduce the impact of system foaming on the downcomer. Preferably, the height difference between two adjacent overflow weirs is 50-150mm, which is beneficial to the uniformity of liquid phase flow at different heights.

Referring to Figure 8, the flat push flow assembly 48 also preferably includes a riser tube 19 and a jet hood 17. The riser tube and the jet hood are only schematically shown in Figure 8. The specific structure of the two can be seen in Figures 1-4; 1 is a schematic diagram of the spray hood 17 (or called a cylindrical spray hood) with a circular cross-section; Figure 2 is a schematic diagram of the structure of the cylindrical spray hood and the foam breaking plate when viewed from above; Figure 3 is the spray hood with a rectangular cross-section 27 (or called a strip spray hood or a rectangular spray hood) schematic diagram, FIG. 4 is a schematic diagram of the distribution of the strip spray hood 27 and the froth breaker plate on the tray in an example. The riser pipe 19 is provided on the tray 3 and is located in the area between the staged overflow weir 9 and the liquid receiving tray I 6. The riser pipe 19 is provided with a gas phase channel so that the gas phase below the tray can flow upward through the gas phase channel . The

spray hoods

17, 27 are set on the riser pipe 19, for example, a vertical hood is set on the riser pipe 19; a gap for the lower suction hole 25 is left between the bottom of the

spray hoods

17, 27 and the tray 3; The lower part of the

covers

17 and 27 is provided with an upper liquid suction hole 26 located above the lower liquid suction hole 25, and the upper part of the spray covers 17 and 27 is provided with a spray hole 21, and the position of the spray hole 21 is higher than the gas phase passage outlet of the gas riser 19. The

spray hoods

17, 27 can be specifically fixed on the tray 3, for example, fixed on the tray 3 by screws or brackets. The

jet hoods

17, 27 are equipped with gas guide vanes 22 to guide the jet streams ejected from the jet holes 21 to reduce the collision between the jet streams ejected from the jet holes and reduce the generation of foam ; The gas deflector 22 can be specifically arranged next to the injection hole 21. The angle α between the gas deflector 22 and the tangential direction of the injection hole 21 surface is preferably 1-90°, more preferably 1-45°; each injection hole 21 is provided with a corresponding gas deflector 22, adjacent gas deflectors The angle between the sheet 22 and the tangential direction of the surface of the corresponding injection hole 21 is the same or different, and the same angle is preferably used.

In a preferred embodiment, the

spray hoods

17 and 27 are also provided with a foam breaking plate 23. The position of the foam breaking plate 23 corresponds to the position of the spray hole 21. Referring to FIG. 2, the foam breaking plate 23 can be connected to the gas deflector 22 and opposite to the position of the spray hole 21; or, referring to FIG. 4, a foam breaking plate is provided at least between adjacent spray hoods 27. The distance between the foam breaker 23 and the spray hole 21 is 1-200mm, preferably 10-100mm; the surface of the foam breaker 23 is smooth or rough, preferably a rough surface, and more preferably the foam breaker 23 has spikes, such as sharp Barbed nail board. The

spray hood

17, 27 or the tray 3 is provided with a foam breaker 23, which uses the solid surface to further eliminate foam and mist. The rough surface and the nail plate can strengthen the foam and defoam effect.

In a preferred embodiment, parts of the

spray hoods

27 and 17 provided with the upper liquid suction holes 26 are formed with a necking structure 26 recessed into the spray hood. When the cross section of the spray hood is circular, the diameter of the spray hood at the necking structure is preferably 50%-99% of the diameter of other parts of the spray hood; when the cross section of the spray hood is rectangular, the spray hood is shrinking. The width of the neck structure is preferably 50%-99% of the width of the rest of the spray hood. The design of the necking structure reduces the cross-sectional area of the jet hood from the upper suction hole, increases the gas velocity, and causes the Bernoulli effect, that is, the increase in velocity and the decrease in pressure, which promote the effect of liquid absorption into the recess.

The height of the highest level overflow weir 10 of the graded overflow weir 9 is preferably between 30-1000m; the height of the riser pipe 19 is lower than the highest level overflow weir 10, preferably 10-50mm lower, more preferably 20-40mm lower . The tray in the present invention can ensure extremely high liquid holding capacity: the design of a higher overflow weir, riser pipe and spray hood can ensure the holding time of the tray and the residence time required for the reaction. The reactive distillation process is particularly suitable.

In a preferred embodiment, the cross-section of the riser pipe 19 may be circular or rectangular, the cross-sectional shape of the

spray hoods

17, 27 are correspondingly circular or rectangular, and the corresponding spray hood may be called a cylindrical spray hood or a bar-shaped spray hood. The shape of the upper liquid suction hole 26 may be a rectangle, a trapezoid, a circle, or an ellipse, or a trapezoid, a rectangle, a circle, or an ellipse with slits. The ratio of the open area of the upper liquid suction hole 26 to the lower liquid suction hole 25 is preferably 10-1:1. The design of the upper and lower liquid suction holes and the optimization of the open area can ensure the upper liquid with a higher concentration of organic phase in the liquid phase. The first phase enters the jet hood for mass transfer, which is of great significance for demulsification and improvement of IP recovery. The shape of the spray holes can be round, rectangular, triangular or oblong, preferably rectangular holes or oblong holes, and the length ratio of the long and short sides of the spray holes is 1-20:1, preferably 1.5-10:1;

The present invention also provides a pressurized reactive distillation tower provided with the above-mentioned plug flow rectification trays. Specifically, the pressurized reactive distillation tower is provided with multiple horizontal plug flow arranged at intervals. Distillation tray. Refer to the above description for the specific structure description of the plug flow distillation tray.

The pressurized reaction rectification tower provided by the present invention is mainly based on the existing rectification tower, and its trays are improved. Referring to Figure 8 and Figure 6a, Figure 8 illustrates the relative position of the upper and lower two-layer plug flow distillation trays 1 and 2 in a pressurized reactive distillation tower. Take this as an example to illustrate the pressure reactive distillation The structure of the plug flow rectification trays in the adjacent layers of the tower is not shown in the figure one by one for the plug flow distillation trays of the remaining layers. In the two adjacent layers of flat plug flow distillation trays 1 and 2, a liquid receiving tray I 7 on the flat plug flow distillation tray 2 of the next layer corresponds to the flat plug flow distillation tray I 7 of the upper layer. Directly below a downcomer 5 on the distillation tray 1, the receiving tray I7 is used to receive the light phase material and the heavy phase separated from the light and heavy phase splitting element 13 of the upper level plug flow distillation tray 1. Phase material liquid. The area between the junction of the receiving tray I7 and the tray 4 and the bottom of the downcomer 5 of the upper level plug flow rectification tray 1 is provided with the material liquid outlet 35 of the receiving tray I7, and on the receiving tray I7 The material liquid can flow to the tray 4 through the material liquid outlet 35.

An outlet weir 34 is formed at the junction of the liquid receiving tray I7 and the tray 4. As mentioned above, referring to Fig. 8, Fig. 6a, and Fig. 6b, the outlet weir 34 is preferably arranged in an inclined manner, and the whole is inclined. For example, taking Fig. 6a as an example, the bottom of the outlet weir 34 is connected to the tray I7 through the first edge of the outlet weir 341, the top of the outlet weir 34 is connected to the tray 4 through the second edge of the outlet weir 342, and the outlet weir 34 is connected to the receiver. An obtuse angle is formed between the trays I7, so that the outlet weir 34 forms an inclined upward ramp between the liquid receiving tray I7 and the tray 4. The outlet weir is arranged in a slope shape, so that when the material liquid overflows from the liquid receiving pan I to the tray via the outlet weir, it is guided upward by the outlet weir, which facilitates the uniform distribution of light and heavy liquids.

The guide element 20 is located on the material liquid outlet 35 of the liquid receiving tray I and above the outlet weir, that is, the transition area between the receiving tray I and the tray. The guiding element 20 is formed with a plurality of guiding channels 201 spaced apart on the material and liquid outlet of the liquid receiving tray I, and each guiding channel penetrates from the receiving tray I7 to the direction of the tray 4, thereby making the receiving The material liquid on the tray I7 can be divided into a plurality of streams to flow toward the tray 4 more evenly; specifically, a plurality of guide vanes 202 can be distributed at intervals to form the guide element 20, and a self-receiving element 20 is formed between adjacent guide vanes. The diversion channel 201 through which the liquid tray penetrates the direction of the tray, for details, please refer to FIG. 6b. Fig. 6b is a schematic view of the flow guiding element in Fig. 6a when viewed from above. Fig. 6b is mainly to reflect the distribution of the flow guiding channels of the flow guiding element, and other components are not shown one by one. In order to facilitate the more uniform flow of the material and liquid on the tray, referring to Figure 6b, the guide element 20 includes a set of guide vanes arranged above the outlet weir, and a group of guide vanes specifically includes a plurality of guide vanes 202, The guide vanes 202 are arranged at intervals along the first edge 341 of the outlet weir 34 above the outlet weir 34. Diversion channels 201 are formed between the adjacent guide vanes 202, and each guide channel extends from the liquid receiving tray I to the direction of the tray. Run through. The angle between each guide vane and the vertical line of the first edge 341 of the outlet weir is ≥0° and <90°, and the vertical line is located on the plane of the tray 4 connected to the outlet weir, And a perpendicular line perpendicular to the first edge 341 of the outlet weir. The angles between adjacent guide vanes and the vertical line of the first edge of the outlet weir are the same or different.

The present invention designs light and heavy phase splitting elements on the tray, which can play the role of light and heavy phase splitting and distribution, can effectively avoid the pulsation when the light and heavy two phases are mixed, and at the same time facilitate the even "distribution" of the light and heavy phases at the downcomer outlet In addition, in conjunction with the ramp design of the outlet weir and the design of the diversion element, the light and heavy liquid can be more evenly distributed in the horizontal direction to achieve a flow close to the horizontal plug flow.

As mentioned above, the specific shapes of the outlets of the light phase channel 39 and the heavy phase channel 40 are not particularly limited. For example, they can be elongated, circular, square, etc., and they can also be composed of multiple channel outlets distributed at intervals; preferably the light phase The outlets at the bottom of the channel 39 and the heavy phase channel 40 are respectively arranged to include a plurality of mutually discontinuous channel outlets. The outlets of the light phase channel 39 and the heavy phase channel 40 are preferably arranged as liquid distribution ports with a liquid distribution function, which play a similar liquid distribution function. The function of the filter is to make the light phase material liquid and the heavy phase material liquid evenly distributed to the liquid receiving plate I7 directly below the light phase channel 39 and the heavy phase channel 40. As a specific example, referring to Figures 6a and 6b, the light phase channel is provided with a long strip-shaped outlet or the heavy phase channel is provided with a plurality of spaced outlets. This is only an example and is not limited to these forms. .

On the flat plug flow distillation tray, one or more sets of flat plug flow assemblies 48 may be provided, for example, two or more sets of flat plug flow assemblies 48 are provided. A set of plug flow components 48 is provided on the flat plug flow rectification tray 1 of the upper layer, and a set of plug flow components 48 are provided on the flat plug flow rectification tray 2 of the next layer. , And the downcomers 5 of the corresponding plug-flow components from the adjacent-layer plug-flow rectification trays are arranged in a staggered arrangement; see Figure 8 for details. Fig. 8 is a schematic diagram when only one set of flat plug flow components 48 is provided on each flat plug flow rectification tower plate. At this time, the back plate 15 is the tower wall of the pressure reaction rectification tower. Each layer of plug flow rectification trays can also be provided with more than two sets of plug flow components 48. Figures 7a and 7b show an example of the upper layer of plug flow distillation trays and the next layer. The top view schematic diagram of the staggered arrangement of the downcomers 5 of the plug flow rectification trays, which only shows the arrangement of the downcomers in the upper and lower plug flow rectification trays, and does not show other parts; Figure 7a An example arrangement of the guide vanes of the guide element located under the downcomer is also shown.

In a preferred embodiment, taking FIG. 8 as an example, in each adjacent upper and lower horizontal plug flow rectification trays, the liquid phase flows from the material liquid outlet (or outlet weir) of the liquid receiving tray I6 of the plug flow assembly 48 ) The lengths of the channels flowing to the staged overflow weir 9 are all equal.

The pressure reaction rectification tower with the flat plug flow rectification tray of the present invention, in which the design of the light and heavy phase splitting element 13 can ensure that the light and heavy phases in the downcomer 5 can pass through their respective channels ( For example, the light phase channel and the heavy phase channel) flow to the next stage of the tray, combined with the design of the outlet weir 34 and the multi-stage overflow weir, to ensure that the fluid leaves the downcomer 5 and enters the next level of flat push-flow distillation tray The flow on the tray 4 in the vertical direction can be close to the flow of the flat push flow; combined with the design of the guide element 20 above the outlet weir 34, it is ensured that the fluid leaves the downcomer 5 and enters the tray of the next layer of trays. The horizontal flow on 4 is relatively uniform, which is close to the flow of flat push flow. The use of the pressurized reactive distillation tower of the present invention can effectively overcome the pulsation phenomenon in the prior art without dividing the channel design, and effectively reduce the possible intermittent flow-no-flow-flow problems of the light and heavy phases, thereby improving the liquid phase Flow uniformity and reaction effect. The downcomers of the upper and lower trays are arranged staggered so that the liquid phase flows out from the downcomer, and the flow channels from the material liquid outlet of the liquid tray I6 to the overflow weir 9 are equal, which can ensure that the liquid phase on the trays of the same stage flows close to each other. Flat push. The overflow weir is a graded overflow weir, and the number of stages is ≥1, preferably ≥2, each stage of overflow weir is higher than the previous one, and the height difference is 50-150mm, so as to ensure the liquid phase flow at different heights on the tray The uniformity. In addition, the first-level overflow weir of the staged overflow weir is equipped with overflow holes of different heights to ensure that the upper, middle and lower liquid layers can overflow, and the design of two or more overflow channels formed by the staged overflow weir, Ensure the horizontal plug flow of the liquid phase in the vertical direction; at the same time, the setting of the multi-stage overflow weir, for the easy-foaming IP/lye system, can also effectively inhibit the foam in the downcomer and significantly reduce the system The effect of foaming on the downcomer. In summary, the liquid phase can flow close to the horizontal and vertical direction on the tray, and the light and heavy phases in the downcomer can also flow more uniformly, which can obtain a higher reaction yield for the series of reaction intermediate products. Provides a strong foundation.

The present invention also provides a method for preparing isophorone by liquid-phase condensation of acetone, which mainly includes the following steps:

2) The liquid phase stream containing the reaction product obtained in step 1) enters the hydrolysis reaction section, and the by-products with carbon atoms ≥ 12 contained in the liquid phase stream are in contact with water and hydrolyzed; the hydrolysis reaction section is equipped with a horizontal push The pressure reaction rectification tower used in the hydrolysis reaction section is the pressure reaction rectification tower provided by the present invention as described above; some valuable components are recovered by hydrolysis. Minute;

In step 1), the condensation reaction section preferably includes two or more condensation reaction sections in series; preferably, the aldol condensation reaction temperature of each condensation reaction section is 190-280°C, preferably the aldol condensation reaction temperature of the first condensation reaction section It is 200-280°C. Each condensation reaction stage can be carried out in a reactor well known in the art.

In a preferred embodiment, step 1) includes a first condensation reaction section and a second condensation reaction section, and through the first condensation reaction section, an acetone conversion rate ≤10%, preferably acetone conversion rate ≤8% is obtained, for example 5%-10%, 5%-8%, etc., of course, can also be lower; in the second condensation reaction stage, acetone continues to react to obtain more IP (isophorone) products. The reactor used in the first condensation reaction stage can be carried out in the upper tray of the reactive distillation tower, or in other reactors separately installed, such as a static mixer or a static mixer installed in series before the reactive distillation tower A tubular reactor with a microchannel mixer, or a reactive distillation tower reactor; more preferably a static mixer (such as the SMV static mixer of Sulzer, Switzerland) or a microchannel mixer (such as the German Eppen Germany’s Miprowa type microchannel reactor) tubular reactor. The second condensation reaction stage can be carried out in a conventional reactive distillation tower, such as a sieve plate, a float valve, a bubble-cap type plate-type reactive distillation tower; preferably, it is carried out in the pressurized reactive distillation tower provided by the present invention. The second condensation reaction section and the hydrolysis reaction section described in step 2) are preferably carried out in the same pressurized reactive distillation tower provided by the present invention, and the upper tray of the pressurized reactive distillation tower is the second condensation reaction section , The lower tray is the hydrolysis reaction section.

Preferably, different process temperatures and raw material ratios are used in different condensation process sections. For example, the reaction temperature of the first condensation reaction section is operated at least 10°C higher than that of the second condensation reaction section, for example, 10°C higher than that of the second condensation reaction section. -50°C, preferably 10-20°C higher; the acetone-water mass ratio in the first condensation reaction stage is preferably 4-10:1; the acetone-water ratio in the second condensation reaction stage is preferably 4:1-1:4, More preferably 4:1-1:2.

When the two-stage condensation reaction process is adopted, the second condensation reaction stage preferably adopts a pressurized reactive distillation tower reactor at a temperature of 190～260℃ and 20～60Bar(A); the preferred temperature is 200～240℃, pressure 25-40Bar(A); the liquid phase residence time in the pressure reaction rectification tower of the second condensation reaction section is 30-180min, preferably 60-120min.

The catalyst solution may specifically be an aqueous solution containing KOH or NaOH, and the amount of the catalyst accounts for 0.001 to 1% of the total mass flow of the reactants, preferably 0.01 to 0.1%.

In the liquid phase condensation process of acetone, the high boilers (such as Xylitone and Isoxylitone, etc.) with carbon atoms ≥ 12 obtained by the deep condensation of acetone are hydrolyzed in a pressurized reactive distillation tower. The unreacted light components (mainly acetone, but also a small amount of diacetone alcohol DAA, mesityl oxide MO, β-isophorone, trimethylbenzene, etc.) are obtained from the top of the tower, which are condensed into a liquid state by the condenser and then recycled Continue to participate in the reaction in the upstream process section. The product obtained at the bottom of the tower contains condensation products and catalyst solution. After passing through an oil-water separator, it is divided into two phases of oil and water. The oil phase is mainly isophorone and by-product organics, and the water phase is mainly water and catalyst solution.

In step 2), the liquid phase stream from step 1) is mainly composed of water and valuable organic matter. The valuable organic matter includes IP generated by the liquid-phase condensation reaction of acetone and high boilers (such as xylose). Xylitone and Isoxylitone, etc.), and contains a small amount of acetone, diacetone alcohol, mesityl oxide, mesitylene, etc.

For the existing technology of acetone pressurized reactive distillation to prepare IP, the tray has a large liquid holding capacity. For the process using traditional rectification trays, it means that the pressure drop loss increases sharply, the foaming is serious, and the liquid The liquid phase separation causes uneven mixing and uneven flow of the liquid phase. These problems also significantly restrict the removal of high-color substances in the process using traditional tray technology.

The inventor of the present application has carefully designed a new flat plug flow distillation tray, and step 2) is carried out in a pressurized reactive distillation tower equipped with such trays, so that the liquid phase is close to the flow of the flat plug flow on the tray. The light and heavy phase splitting element makes the light and heavy phases in the downcomer flow evenly in the vertical direction to the receiving tray I of the lower tray according to different channels, avoiding the pulsation when the two phases are mixed, and then through the flow guiding element, so that The light and heavy phases are evenly distributed, combined with the oblique upward diversion function of the outlet weir, the light and heavy phases flow evenly in the horizontal direction to the tray of the next layer of trays. The design of the staged overflow weirs with more than two stages can ensure the uniformity of the liquid phase flow at different heights on the tray. Two or more overflow channels are formed between the overflow weirs, which is conducive to the leveling of the liquid phase in the vertical direction. Push flow. The new flat-plug flow distillation tray of the present application is used to carry out the hydrolysis process for recovering valuable components in the by-products, without the need to add additional chemical additives (in the prior art, for example, CN201110140108, it is necessary to add at least one defoamer Isophorone can be prepared under the conditions of the agent, which can realize the defoaming of the IP/lye stream, uniform flow and efficient operation.

The rectification operation without additional additives can be carried out smoothly and efficiently. The key is the innovative design of the internal components of the tower. Traditional distillation towers such as bubble tower, valve tower, and sieve tray all belong to the category of bubbling distillation towers, and the operation mode fundamentally limits their applicability to easy-foaming systems. The innovative tray internal component form (combined design of spray hood and riser tube) proposed by the present invention makes the gas phase need not be bubbled through the liquid layer, and the problem is solved by changing the mass transfer form. During the use of the flat-plug flow distillation tray of the present invention, the basic operation mode of the combined structure of the spray hood and the riser is:

The gas phase enters the spray hood through the riser. The upper liquid phase and the lower liquid phase in the tray enter the spray hood through the upper suction hole at the necking structure of the spray hood and the lower suction hole near the tray. The rising gas of the riser is torn into smaller droplets. The gas phase is used as the continuous phase and the liquid phase is used as the dispersed phase in the spray hood and sprayed into the space outside the spray hood through the spray hole of the spray hood. Contact and heat transfer, mass transfer; the liquid phase that falls back on the tray after the liquid phase is sprayed can strengthen the disturbance and mixing of the liquid phase on the tray in the vertical direction. Because this operation essentially avoids the problems of large pressure drop caused by bubbles passing through the liquid layer, serious foaming, and significant reduction in mass transfer as the liquid layer increases. At the same time, the high-speed droplets have a certain effect on the bubbles during the ejection process. The rupture effect, the gas deflector set on the jet hood, reduces the disordered collision between jet streams and further reduces foam.

In summary, the adoption of a new-type tray structure can not only ensure the large liquid holding capacity required for the IP synthesis reaction, but also effectively solve the problem of large pressure drop, easy foaming, difficulty in liquid-liquid phase separation, and distillation efficiency in the IP synthesis reaction system. Low-level issues.

Step 2) The treated product is cooled and separated into two phases: oil and water, the oil phase is mainly organic products containing IP, and the water phase is mainly water and homogeneous base catalyst. The treated organic phase is washed, flashed, distilled, rectified and other purification and purification methods, and finally obtained high-yield, low-color, and economically competitive qualified IP products.

In order to facilitate the understanding of the technical solution of the present invention, the following specific embodiments are used for further exemplification, but it should not be understood that the technical solution of the present invention is limited to the content of the following embodiments.

The measurement method of the product color number in the embodiment is implemented in accordance with the regulations of GB/T 3143.

In the examples, the organic phase composition of the IP reaction liquid was analyzed by gas chromatography (GC) analysis method, and the gas chromatography analysis conditions were as follows:

The analytical instrument used is: Shimadzu GC-2010PLUS;

Chromatographic column: DB-5MS (60m*0.25mm*0.25μm);

Vaporization chamber temperature: 180℃;

Program temperature rise conditions: initial temperature 40℃, keep for 3 minutes, 15℃/min to 280℃, keep for 11 minutes;

Detector: FID detector;

Detector temperature: 300℃;

Carrier gas: high-purity nitrogen (purity 99.999%),

Column flow rate: 1-1.5ml/min;

Analysis method: normalization.

Example 1:

In this embodiment, the schematic diagram of the structure of the flat-plug flow distillation tray is shown in Figures 8, 6a, and 6b.

The plug flow distillation tray 1 includes a tray 3 and a plug flow assembly 48 arranged on the tray 3. The plug flow assembly 48 includes a staged overflow weir 9, a downcomer plate 16, a light and heavy phase splitting element 13, and The liquid pan I6 and the guide element 20. The plug flow rectification tray of this embodiment is a single overflow, that is, in the rectification tower, a downcomer 5 and a liquid receiver are installed on the trays of each layer of the flat plug flow rectification tray installed at intervals. Disk I6, that is, a set of flat plug flow components 48 is installed. The downcomers 5 of the plug flow assembly 48 of the upper and lower plug flow rectification trays are arranged in a staggered manner. Therefore, the liquid receiving trays I6 and 7 in the upper and lower layers are also arranged in a staggered manner. Each liquid receiving tray I6 and 7 is correspondingly located on the upper Just below the downcomer 5 of a layer of flat push-flow distillation tray. In this embodiment, the diameter of the plug flow rectification tray is 800 mm. In this example, it is the distance between the downcomer back plates of the upper and lower plug flow distillation trays in FIG. 8. The graded overflow weir 9 in each downcomer has 3 stages, namely, the first-stage overflow weir 12, the second-stage overflow weir 11, and the third-stage overflow weir 10, and the heights are 100, 150, and 100 respectively. 200mm. Among them, the first-level overflow weir 12 has 60 overflow holes 47 with a diameter of 6 mm, and the overflow holes 47 are distributed at different heights. The height of the lowest overflow hole 47 from the tray 3 is 50 mm. The cross-sectional area of the downcomer accounts for 24% of the projected area of the tray in the vertical direction, and the back plate 15 of the downcomer 5 is 290 mm high. Since in this embodiment, a downcomer is installed on the tray of each horizontal plug flow rectification tray, the back plate 15 is the part of the tower wall corresponding to the rectification tower wall. The horizontal distance between the primary overflow weir 12 and the secondary overflow weir 11 is 6 mm, and the horizontal distance between the secondary overflow weir 11 and the tertiary overflow weir 10 is 10 mm. The light-heavy-phase flow dividing element 13 includes a liquid-receiving plate II 49, a dividing weir 41, a light-phase liquid-receiving area 37 and a heavy-phase liquid-receiving area 38, a light-phase channel 39 and a heavy-phase channel 40. The specific structure is shown in Figure 8, Figure 6a-6b and The corresponding description in the previous section will not be repeated here. The lower edge of the drainage hole 43 on the partition plate 42 of the heavy phase channel 40 is 50 mm higher than the lower edge of the gravity phase deflector 44, which corresponds to the "liquid seal height" in FIG. 6a. In the flat-plug flow distillation trays of each layer, the liquid-phase material flow flows from the material liquid outlet 35 (or the position corresponding to the outlet weir) of the liquid-receiving plate I6 of the flat-plug flow assembly to the flow channel of the graded overflow weir 9 Are equal. Referring to Figure 6a, the area between the connection between the receiving tray I6 and the tray 3 and the downcomer of the upper layer of the flat push-flow distillation tray is provided with the material liquid outlet 35 of the receiving tray I, and the receiving tray I An outlet weir 34 is formed at the junction with the tray; the material and liquid outlet of the liquid receiving tray I is provided with a flow guiding element 20 and is located above the outlet weir 34. The guide element 20 is provided with a plurality of guide channels 201 spaced apart on the material and liquid outlet of the liquid receiving tray I, and each guide channel penetrates from the liquid receiving tray to the direction of the tray, so that the The material liquid can be divided into relatively uniform multiple streams to flow toward the tray. The structure of the guide element 20 can be seen in Figures 6a and 6b, and the specific structure description can be referred to the foregoing, and will not be repeated.

The spray hood 17 provided on the flat plug flow rectification tower plate of this embodiment is a cylindrical spray hood with a circular cross section. As shown in Figures 1 and 2, the cylindrical spray hood 17 is provided on the tray 3, and there is a gap between the bottom of the spray hood and the tray, and the gap is used as the lower suction hole 25; the lower part of the spray hood 17 is provided There is an upper liquid suction hole 26, which is located above the lower liquid suction hole 25; the gas lift pipe 19 is installed on the tray 3, and the spray cover 17 is arranged on the gas lift pipe 19. Among them, the riser tube 19 is cylindrical as a whole, with a circular cross section and a diameter of 30 mm. The riser tube 19 is 160 mm higher than the tray 3. The upper liquid suction hole 26 of the spray hood 17 is higher than the top outlet of the riser pipe 19, and the whole spray hood is also cylindrical. The spray hood 17 has a necking structure 24 recessed toward the inside of the spray hood at the upper liquid suction hole 26. The upper part of the spray hood is provided with spray holes 21. The spray holes 21 are specifically rectangular gas spray holes arranged vertically and parallel to each other. The total height of the spray hood is 300mm, and the upper diameter of the spray hood is 60mm. The center of the upper suction hole 26 (that is, the middle part of the upper suction hole) is 100mm from the tray 3, and the diameter of the necking structure 24 is 45mm (this diameter does not include the transition area between the necking structure and the other parts of the spray cover diameter). The upper and lower suction holes 26 and 26 are both rectangular in cross section (the specific structure of the lower suction holes is not shown in Figure 1), the width of the upper and lower suction holes is the same, and the heights of the upper and lower suction holes are 20mm and 10mm, respectively. The opening area ratio is 2:1. In this embodiment, the spray holes 21 on the spray hood 17 are specifically 10 rows of 5*50 mm rectangular holes that are parallel in the vertical direction and arranged uniformly. A guide vane 22 is provided next to the jet hole 21, and the tangential angle to the surface of the jet hole 21 is 45°. A nail plate with sharp protrusions is provided next to the guide vane 22 as the foam breaking plate 23. On the chip, next to the spray hole, opposite to the position of the spray hole, the foam breaker 23 is processed into an arc shape to prevent the gas and liquid between adjacent spray hoods and adjacent spray holes of the same spray hood from colliding with each other, resulting in additional foam. The outer diameter of the foam breaker is 120mm (the outer diameter of the foam breaker is the diameter of the circle formed by each foam breaker).

For the flat-plug flow distillation tray and the pressurized reactive distillation tower involved in the present embodiment that are not described in detail, please refer to the corresponding content in the preceding text.

Example 2

This embodiment is basically the same as Example 1, except that the spray hood used in the flat plug flow distillation tray is a strip spray hood with a rectangular cross section (or called a rectangular spray hood):

As shown in Figures 3 and 4, the strip-shaped spray hood 27 is provided on the tray 3. The same structural parts of the strip-shaped spray hood 27 and the cylindrical spray hood 17 of the first embodiment will not be repeated here. Embodiment 1, the main differences are described as follows: the cross section of the riser tube 19 is rectangular, the length and width are 240mm and 20mm respectively, the longer side of the rectangle is installed on the tray 3 along the direction of liquid flow, the riser tube 19 160mm higher than tray 3. The total height of the spray hood 27 is 200 mm. The spray hood 27 is arranged on the riser 19, and the overall cross-sectional shape of the spray hood 27 is also rectangular. The spray hood 27 is provided with a necking structure 24 recessed toward the inside of the spray hood at the upper suction hole 26, the upper part of the spray hood 27 has a width of 60mm, and the center of the upper suction hole 26 is 100mm higher than the tray; the upper suction hole has a necking structure. The width is 50mm (this width does not include the width of the transition area between the necking structure and other parts of the spray cover). The upper and lower suction holes 26 and 25 are rectangular in cross section (the specific structure of the lower suction holes is not shown in Fig. 3), the width of the upper and lower suction holes is the same, and the heights of the upper and lower suction holes are 15mm and 15mm, respectively. The opening area is 1:1. In this embodiment, the upper part of the spray hood 27 is specifically provided with 14 rows of 8*100mm rectangular spray holes 21 arranged vertically, parallel to each other, and evenly arranged. Referring to Fig. 4, a gas deflector 22 is provided next to the spray cover. The tangential direction of the gas deflector 22 and the spray hole (in this embodiment can be understood as the angle α° with the surface of the spray hole) is an angle of 30° , To prevent the jet streams from adjacent jet holes of the same jet cover from colliding with each other, resulting in extra foam. The foam breaker 23 is arranged on the tray 3, and is arranged parallel to the longer side of the spray hood 27, and can be positioned opposite to the spray hole 21 provided on the spray hood 27. The foam breaker is 60 mm from the long side of the spray hood. The foam breaker is a nail plate with rough surface or with nail-like protrusions to avoid the collision of gas and liquid between adjacent spray covers to cause extra foam. Referring to Fig. 4, in this embodiment, the strip spray hoods are arranged in parallel on the tray at intervals, and foam breakers are installed between adjacent strip spray hoods.

The following examples illustrate the application of acetone liquid phase condensation to produce isophorone using a rectifying tower provided with a flat-plug flow rectifying tray of the present invention. The measurement method of the product color number in the embodiment is implemented in accordance with the regulations of GB/T 3143.

Example 3

The schematic diagram of the process for preparing isophorone (or IP for short) by liquid-phase condensation of acetone is shown in FIG. 5, the acetone and NaOH aqueous solution are preheated by the preheater 28 and the mixer 29 (this embodiment specifically adopts the Swiss Sulzer Company The SMV static mixer) is fully mixed and then enters the first condensation reactor 30 (the reactor 30 used in this example is a tubular fixed-bed reactor), the reaction temperature is 210°C, the pressure is 3.5 MPa (G), and the acetone processing capacity It is 600kg/h, the mass ratio of acetone and water is 5:1, the catalyst is NaOH, and based on the total flow of the reaction liquid, the mass concentration of NaOH is 0.1%.

The acetone conversion rate corresponding to the outlet of the first condensation reactor 30 is 10%, and the reaction liquid (that is, the liquid phase stream) then enters the pressure reaction rectification tower 31. The pressure reaction rectification tower 31 is at 3.0MPa and the temperature is 200°C. Operation, the mass ratio of acetone to water is 3:1. The pressure reaction rectification tower 31 has a diameter of 800 mm and includes 50 trays of the present invention, of which the residence time of the second condensation reaction section is 30 min. The trays used in this example are specifically the plug flow rectification tower in Example 1. The arrangement of each tray in the rectification tower is also the same as in Example 1. There are 28 cylindrical spray hoods on each tray, and the cylindrical spray hood adopts the design of the cylindrical spray hood of the first embodiment. The distance between the trays of the upper and lower flat push-flow distillation trays is 800mm, and the pressure drop of the single plate is 650Pa; the distance between the bottom of the tower and the bottom tray is 2.0m, and the upper limit of the liquid level of the tower is 1.2m. The reactor liquid in the reaction rectification tower is cooled by the cooler 32, and is divided into two phases of oil and water by the water separator 33. The content of IP (isophorone) in the obtained organic phase is 90%, the others are mainly high boiling point 9.5%, acetone 0.01%, and a small amount of intermediate components.

After adopting the method of acetone liquid phase condensation to synthesize IP using the pressurized reactive distillation tower including the new flat-plug flow distillation tray of the present invention, the color number of the IP product is less than No. 10, and the device and product quality are stable. , The single board pressure drop is small; the device has been running continuously for 1 year, and the product index is stable.

Example 4

The schematic diagram of the process for preparing isophorone by liquid-phase condensation of acetone is shown in FIG. 5. The acetone and KOH aqueous solution are preheated by the preheater 28 and the mixer 29 (this embodiment specifically adopts the SMV static mixer of Sulzer, Switzerland). After fully mixing, enter the first condensation reactor 30 (the reactor used in this example is a tubular fixed-bed reactor), the reaction temperature is 250 °C, the pressure is 6 MPa (G), the acetone processing capacity is 720 kg/h, acetone and The water ratio is 4:1, the catalyst is KOH, and the mass concentration of KOH is 0.04% based on the total flow of the reaction liquid.

The acetone conversion rate corresponding to the outlet of the first condensation reactor 30 is 8%, and the reaction liquid (that is, the liquid phase stream) immediately enters the pressure reaction rectification tower 31, and the pressure reaction rectification tower is at a pressure of 5.0 MPa and a temperature of 240°C. Operation, the ratio of acetone to water is 4:1. The pressure reaction rectification tower has a diameter of 800mm and includes 50 trays of the present invention, of which the residence time of the second condensation reaction section is 30min. The trays used in this embodiment are specifically the plug flow rectification trays in Example 2. , The arrangement of the trays in the rectification tower is also the same as in Example 2. Five strip spray hoods are arranged on each tray, and the strip spray hood adopts the strip spray hood in the foregoing embodiment 2. The distance between the upper and lower flat push-flow distillation trays is 800mm, and the pressure drop of the single plate is 600Pa; the distance between the bottom of the tower and the bottom tray is 2.0m, and the upper limit of the liquid level of the tower is 1.2m. The reactor liquid in the reaction rectification tower is cooled by the cooler 32, and is divided into two phases of oil and water by the water separator 33. The IP content in the obtained organic phase is 92%, the others are mainly high boilers 7.5%, acetone 0.01%, and a small amount of intermediate components.

After adopting the method of acetone liquid phase condensation to synthesize IP by adopting the pressurized reactive distillation tower including the new flat plug flow distillation tray of the present invention, the color number of the IP product can be less than No. 10 and the device and product quality are running Stable, small single board pressure drop; the device has been running continuously for 1 year, and the product index is stable.

Comparison

The schematic diagram of the process for preparing isophorone (or IP for short) by liquid-phase condensation of acetone is shown in FIG. 5, the acetone and NaOH aqueous solution are preheated by the preheater 28 and the mixer 29 (this embodiment specifically adopts the Swiss Sulzer Company The SMV static mixer) is fully mixed and then enters the first condensation reactor 30 (the reactor 30 used in this example is a tubular fixed-bed reactor), the reaction temperature is 210°C, the pressure is 3.5 MPa (G), and the acetone processing capacity It is 450 kg/h, the mass ratio of acetone and water is 5:1, the catalyst is NaOH, and the total flow rate of the reaction liquid is used as a reference, and the mass concentration of NaOH is 0.1%.

The acetone conversion rate corresponding to the outlet of the first condensation reactor 30 is 10%, and the reaction liquid (that is, the liquid phase stream) then enters the pressure reaction rectification tower 31. The pressure reaction rectification tower 31 is at 3.0 MPa and the temperature is 205-235. Operate at ℃. The pressure reaction rectification tower 31 has a diameter of 800mm and includes 50 traditional bubble-cap trays. The residence time of the second condensation reaction section is 45min. It uses a single overflow downcomer. The area of the downcomer is 24 of the cross-sectional area of the tower. %, the height of the overflow weir is 200mm, 28 traditional cylindrical bubble caps are set on each tray, the riser is cylindrical, the inner diameter is 30mm, and the height is 160mm, the same as in Example 1. The distance between the trays of the upper and lower flat push-flow distillation trays is 800mm, and the single-plate pressure drop is 1700Pa; the distance between the bottom of the tower and the bottom tray is 2.0m, and the upper limit of the liquid level of the tower is 1.2m. The reactor liquid in the reaction rectification tower is cooled by the cooler 32, and is divided into two phases of oil and water by the water separator 33. The IP content in the obtained organic phase is 86.3%, and the others are mainly 13.4% of high boilers, 0.05% of acetone, and a small amount of intermediate components.

The color number of the IP product obtained according to the above embodiment is No. 25, with a light yellow color.

The inventor tried to increase the rectification load and then the acetone processing load, but the rectification tower was stopped due to flooding. Limited by the properties of traditional bubble cap trays, under the conditions of this comparative example, the upper limit of acetone processing is about 450 kg/h. The reason is that traditional tray technology (such as the bubble cap tray used in this comparative example) requires mass transfer through the liquid layer by bubbling in the gas phase. For IP synthesis, a system that requires large liquid holding capacity and is easy to foam The upper limit of the gas phase load of the rectification column is significantly reduced, and the rectification efficiency is significantly lower than the corresponding process of the novel tray disclosed in the present invention, resulting in a reduction in the load of the reactive rectification column and poor rectification effect. The hydrolysis effect of high boilers will affect the color number and yield of IP products.

In summary, the pressurized reactive distillation tower based on the new flat plug flow distillation tray designed in the present invention can be used in the process of preparing isophorone by the liquid phase condensation of acetone, which can improve the reaction effect and promote the uniform flow of the liquid phase. And distribution is beneficial to improve production efficiency, improve product color number, and reduce tray pressure drop; and no additional chemical additives are needed to achieve defoaming of IP/lye streams; the device can operate stably and efficiently.

The orientations involved in the text such as "up", "down", "above", "below", "top", "bottom", etc. are all based on the orientation shown in FIG. 8.

Those skilled in the art can understand that under the teaching of this specification, some modifications or adjustments can be made to the present invention. These modifications or adjustments should also fall within the scope defined by the claims of the present invention.

Claims

A flat-plug flow distillation tray, which is characterized in that it comprises a tray and one or more sets of flat-plug flow components arranged on the tray, and the flat-plug flow components include a downcomer and a grading overflow weir. , Light and heavy phase splitting element, receiving plate I and flow guiding element;

The downcomer is connected to the tray, the upper part of the downcomer is provided with an inlet, the grading overflow weir is provided on the inlet of the downcomer, and the downcomer is provided with a vertical flow channel The light and heavy phase splitting element is arranged in the downcomer and located below the grading overflow weir, and is used to receive the material liquid overflowing from the tray through the overflow weir to the vertical flow channel of the downcomer, and Separate the light phase material liquid and the heavy phase material liquid from the material liquid and drain the two through different channels to the bottom of the downcomer;

The liquid receiving tray I is connected to the tray, and is located on the opposite side of the side where the downcomer is connected to the tray;

The flow guide element is arranged above the connection between the liquid receiving tray I and the tray, and the flow guide element is provided to enable the material liquid on the liquid receiving tray I to be divided into multiple streams to divert to the tray Multiple diversion channels;

Preferably, an outlet weir is formed at the junction of the receiving tray I and the tray, and the flow guiding element is located above the outlet weir;

Preferably, the downcomer includes a downcomer plate and a back plate, the downcomer plate is connected to the tray, the back plate and the downcomer plate are enclosed to form the vertical flow channel, and the back plate Higher than the grading overflow weir;

It is further preferred that the number of stages of the grading overflow weir is ≥1, wherein the first-stage overflow weir is provided on the downcomer plate, and it is further preferred that the first-stage overflow weir is provided with a plurality of different heights. The overflow hole; preferably the number of stages of the grading overflow weir ≥ 2, when the number of stages of the grading overflow weir ≥ 2, from the downcomer plate to gradually away from the downcomer plate and toward the direction of the downcomer cavity , The overflow weirs at all levels are arranged at intervals and their heights increase sequentially, and the height difference between the adjacent two overflow weirs is 50-150mm.
The flat-plug flow distillation tray according to claim 1, wherein the light-heavy phase splitting element comprises a receiving plate II, a split weir, a heavy phase channel, and a light phase channel, and the split weir is provided on the On the receiving plate II and divide the receiving plate II into a heavy phase receiving area and a light phase receiving area; the heavy phase receiving area is located in the downcomer on the same side as the grading overflow weir. Below the staged overflow weir, so that the material flow overflowing from the staged overflow weir into the downcomer tends to flow into the heavy phase receiving area;

The heavy phase channel is used to divert the heavy phase material liquid deposited at the bottom or bottom of the heavy phase liquid receiving zone to below the downcomer;

The light-phase liquid receiving area is used to receive the light-phase material liquid from the upper part of the heavy-phase liquid-receiving area overflowed by the divided weir, and the light-phase channel is used to divert the light-phase material liquid from the light-phase liquid receiving area to Below the downcomer;

Preferably, the heavy phase channel is provided with a partition plate, the partition plate is provided with drainage ports, the inlet and the outlet of the heavy phase channel are respectively located on both sides of the partition plate, and the drainage port The lower edge of is higher than the upper edge of the entrance of the heavy phase channel, preferably the height difference between the two is 20-100mm;

Preferably, a baffle plate is also provided in the downcomer, and the baffle plate is arranged in the space between the grading overflow weir and the light-heavy phase dividing element, and is located in the downcomer with a grading overflow. The opposite side of one side of the weir, so that the material flow overflowing into the downcomer through the staged overflow weir tends to flow to the heavy phase receiving area.
The flat plug flow distillation tray according to claim 2, characterized in that,

The guide element includes a set of guide vanes arranged above the outlet weir;

The outlet weir includes a first edge of the outlet weir connected to the receiving tray I and a second edge of the outlet weir connected to the tray;

The set of guide vanes are arranged at intervals along the first edge of the outlet weir above the outlet weir. The guide channels are formed between adjacent guide vanes, and each guide channel is directed from the liquid receiving plate I to the tower. The direction of the disk goes through;

The angle between each guide vane and the vertical line of the first edge of the outlet weir is ≥0° and <90°, and the vertical line refers to the plane located on the tray connected to the outlet weir. And the vertical line perpendicular to the first edge of the outlet weir; the angle between the adjacent guide vanes and the vertical line of the first edge of the outlet weir is the same or different; preferably, each guide vane is formed by the outlet weir The first edge is close to the end of the middle of the tray, and is arranged obliquely toward the end of the first edge of the outlet weir close to the end of the tower wall; preferably, the closer to the first edge of the outlet weir, the greater the angle between the guide vanes and the vertical line .
The flat plug flow distillation tray according to claim 3, characterized in that the outlet weir is arranged obliquely, and the bottom of the outlet weir is connected to the liquid receiving tray I through the first edge of the outlet weir , The top of the outlet weir is connected to the tray through the second edge of the outlet weir, and the angle between the outlet weir and the liquid receiving tray I is an obtuse angle;

And/or, the outlets at the bottom of the light phase channel and the heavy phase channel respectively include a plurality of channel outlets that are not continuous with each other.
The flat-plug flow distillation tray according to any one of claims 1 to 4, wherein the flat-plug flow assembly further comprises a gas riser and a spray hood, and the gas riser is provided on the tray, And it is located in the area between the graded overflow weir and the liquid receiving tray I; the gas riser is provided with a gas phase channel for guiding the gas phase below the tray upwards;

The spray hood is arranged on the riser pipe, and a gap used as a lower suction hole is left between the bottom of the spray hood and the tray; the lower part of the spray hood is provided above the lower suction hole The upper liquid suction hole of the spray cover is provided with a spray hole, and the position of the spray hole is higher than the outlet of the gas phase passage of the gas riser;

A gas guide vane is installed on the outside of the jet hood to guide the jet stream ejected from the jet hole to reduce the collision between the jet stream jets ejected from each jet hole; preferably the gas guide The flow sheet is arranged beside the jet hole;

Preferably, a foam breaking plate is further provided outside the spray hood, and the foam breaking plate corresponds to the position of the spray hole; preferably, the distance between the foam breaking plate and the spray hole is 1-200 mm, more preferably 10-200 mm. 100mm; the surface of the foam breaking plate is smooth or rough, preferably a rough surface, more preferably the foam breaking plate has spikes;

Preferably, the part of the spray cover provided with the upper liquid suction hole is formed with a constricted structure that is recessed into the spray cover.
The flat-plug flow distillation tray according to claim 5, wherein the height of the highest level overflow weir of the staged overflow weir is between 30-1000m; the height ratio of the riser pipe is the highest. The stage overflow weir is 10-50mm lower, preferably 20-40mm.
The flat plug flow distillation tray according to claim 5 or 6, wherein the cross-section of the riser pipe is circular or rectangular, and the cross-sectional shape of the jet hood is correspondingly circular or rectangular;

And/or, the shape of the upper liquid suction hole is rectangle, trapezoid, circle or ellipse, or trapezoid, rectangle, circle or ellipse with gaps;

And/or, the ratio of the open area of the upper liquid suction hole to the lower liquid suction hole is 10-1:1;

And/or, when the cross section of the spray hood is circular, the diameter of the spray hood at the necking structure is 50%-99% of the diameter of the other part of the spray hood; when the cross section of the spray hood is When it is rectangular, the width of the spray cover at the necking structure is 50%-99% of the width of the rest of the spray cover;

And/or, the shape of the injection hole is circular, rectangular, triangular or oblong; preferably, the injection hole is a rectangular hole or an oblong hole, and the length ratio of the long and short sides of the injection hole is 1-20:1, preferably 1.5- 10:1;

And/or, the angle between the gas deflector and the tangential direction of the injection hole surface is 1-90°, preferably 1-45°; each injection hole is provided with the gas deflector, preferably relative to each other. The included angle between the adjacent gas deflector and the tangential direction of the corresponding injection hole surface is the same or different, and the same angle is preferably used.
A pressurized reaction rectification tower, characterized in that, the pressurized reaction rectification tower is provided with multiple layers of the flat plug flow rectification trays according to any one of claims 1-7 arranged at intervals.
The pressurized reactive distillation tower according to claim 8, characterized in that, among the two adjacent layers of flat plug flow distillation trays, one of the receiving trays on the next layer of flat plug flow distillation trays I correspond to a downcomer located directly under the flat plug flow distillation tray of the upper layer, and the receiving tray I is used to receive the light and heavy phase splitting elements in the downcomer directly above it. Light phase material liquid and heavy phase material liquid;

The area between the connection between the receiving tray I and the tray and the bottom of the downcomer of the upper layer of the flat push-flow rectification tray is provided with the material liquid outlet of the receiving tray I, and the material liquid on the receiving tray I passes through The material liquid outlet can flow to the tray;

Preferably, an outlet weir is formed at the junction of the receiving tray I and the tray; the guide element is located on the material liquid outlet of the receiving tray I, and is located below the downcomer and above the outlet weir .
The pressurized reactive distillation tower according to claim 9, characterized in that, a set of plug flow components arranged on the flat plug flow rectification tower plate of the upper layer, Each is provided with a set of plug flow components corresponding to it, and the downcomers from the corresponding plug flow components of the adjacent layer plug flow rectification trays are arranged in a staggered manner;

Preferably, in the flat-plug flow distillation trays of each adjacent upper and lower layer, the length of the flow passages for the liquid-phase material flow from the material liquid outlet of the liquid receiving tray I of the flat-plug flow assembly to the staged overflow weir are all equal.
A method for preparing isophorone by liquid-phase condensation of acetone, which is characterized in that the method comprises the following steps:

1) Acetone and catalyst solution undergo aldol condensation reaction in the condensation reaction section;

2) The liquid phase stream containing the reaction product obtained in step 1) enters the hydrolysis reaction zone, and the by-products with carbon atoms ≥ 12 contained in the liquid phase stream are contacted with water and hydrolyzed; the hydrolysis reaction zone is installed It is carried out in a pressurized reactive distillation tower with a flat plug flow distillation tray; the pressurized reactive distillation tower is the pressurized reactive distillation tower according to any one of claims 8-10;

3) Separating the liquid phase stream obtained after step 2) hydrolysis to obtain isophorone.
The method according to claim 11, characterized in that, in the step 1), the condensation reaction section includes two or more condensation reaction sections connected in series; preferably, the temperature of the aldol condensation reaction of each condensation reaction section is 190- 280°C, preferably the temperature of the aldol condensation reaction in the first condensation reaction stage is 200-280°C.
The method according to claim 12, wherein the step 1) comprises a first condensation reaction section and a second condensation reaction section, and through the first condensation reaction section, an acetone conversion rate of ≤10% is obtained, Preferably acetone conversion rate ≤8%;

Preferably, the reactor used in the first condensation reaction stage is a tubular reactor with a static mixer or a microchannel mixer, or a reactive distillation column reactor; more preferably a static mixer or a microchannel mixer Tube reactor;

Preferably, the second condensation reaction section adopts a pressurized reactive distillation tower reactor; further preferably, the second condensation reaction section and the hydrolysis reaction section in step 2) are in the same pressurized reactive distillation section. In the distillation column.
The method according to claim 13, wherein the reaction temperature of the first condensation reaction section is operated at least 10°C higher than that of the second condensation reaction section, and the mass ratio of acetone to water in the first condensation reaction section is preferably 4 10:1; the mass ratio of acetone to water in the second condensation reaction stage is preferably 4:1-1:4, more preferably 4:1-1:2;

Preferably, the second condensation reaction section adopts a pressurized reactive distillation tower reactor at a temperature of 190-260°C and a pressure of 20-60 Bar(A); preferably, the temperature is 200-240°C and a pressure of 25-40 Bar(A). ; The liquid phase residence time of the second condensation reaction section in the pressure reaction rectification tower is 30 to 180 min, preferably 60 to 120 min.
The method according to any one of claims 11-14, wherein the catalyst solution is an aqueous solution containing KOH or NaOH, and the amount of the catalyst accounts for 0.001 to 1% of the total mass flow of the reactants, preferably 0.01 to 0.1% .