Hydrogenation reactor for diphthalic acid product
By designing a simplified hydrogenation reactor, combining the dissolution tank and the hydrogenation reactor, and adopting a specific structural design, the problems of high equipment costs and long process flow in the prior art are solved, and the effect of reducing costs and shortening process flow is achieved.
Patent Information
- Application Number
- CN202510152668.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-12
- Publication Date
- 2025-05-27
AI Technical Summary
During the production process of existing bisphthalic acid products, the design of dissolution tanks and hydrogenation reactors leads to high equipment costs, long process flow, and large space.
Design a simplified hydrogenation reactor, combine the dissolution tank and hydrogenation reactor, adopting a reservoir layer, a porous disc distribution disk and a central hollow metal disc filter to reduce equipment and pipeline investment and shorten the process flow.
It has achieved the reduction of equipment and pipeline investment costs, shortened process flow, reduced space layout, and improved production efficiency and product purity.
Smart Images
Figure CN120037834A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of hydrogenation process, and in particular to a hydrogenation reactor for diphthalic acid products. Background Art
[0002] The slurry feed of terephthalic acid, isophthalic acid or phthalic acid containing aldehyde impurities is heated and dissolved. It is firstly required to pass through a dissolving tank with tower plates (10 to 15 plates) to dissolve a small amount of incompletely dissolved powder blocks, and then enter the hydrogenation reactor to react and reduce the aldehyde group to an alkyl group, so as to facilitate subsequent filtration and washing to remove the impurities and obtain high-purity terephthalic acid, isophthalic acid or phthalic acid.
[0003] Due to process requirements, the dissolution tank and the hydrogenation reactor are made of the same material (such as carbon steel + Hastelloy, or carbon steel + stainless steel + titanium), and have the same diameter. The length of the dissolution tank is at least 10-15 plates.
[0004] In the production process of a diphthalic acid product such as purified terephthalic acid, purified isophthalic acid or purified phthalic acid, raw materials such as p-xylene, m-xylene or o-xylene are oxidized to obtain crude terephthalic acid, crude isophthalic acid or crude phthalic acid containing impurities such as p-carboxybenzaldehyde (4CBA), m-carboxybenzaldehyde (3CBA) or o-carboxybenzaldehyde (2CBA), and then the slurry (containing 65-75% water) is heated and dissolved under high temperature and high pressure, and then the impurities 4CBA, 3CBA or 2CBA are reduced to p-toluic acid (pT acid), m-toluic acid (mT acid) or o-toluic acid (oT acid) which are easy to filter, wash and separate in the later stage through a dissolving tank and a hydrogenation reactor, and then the product purified terephthalic acid, purified isophthalic acid or purified phthalic acid is obtained after crystallization, filtration separation and drying. The production process has many units, a long process and high equipment costs.
[0005] In summary, the present invention can reduce the number of dissolving tank units and related pressure pipes and pipe fittings in the process, thereby simplifying the process, saving layout space and reducing costs. Summary of the invention
[0006] In view of the shortcomings of the prior art in that the original cost is relatively high and the distribution pipes in the dissolving tank and the hydrogenation reactor are relatively large, resulting in relatively high costs, the purpose of the present invention is to provide a hydrogenation reactor for diphthalic acid products, which simplifies and shortens the dissolving tank and the hydrogenation reactor into a single hydrogenation reactor, thereby reducing the investment costs of equipment, pipelines, etc., shortening the process flow and reducing the spatial layout.
[0007] In order to achieve the above-mentioned purpose, the present invention is implemented through the following technical scheme: a hydrogenation reactor for diphthalic acid products, comprising a reactor body, a liquid storage layer is arranged on the upper part of the reactor body, an intermediate tube is arranged in the liquid storage layer, a distribution plate is arranged at the bottom of the intermediate tube, a catalyst layer is arranged below the distribution plate, a liquid outlet is arranged at the center of the bottom of the reactor body, a filter is arranged above the liquid outlet, a liquid inlet is arranged on one side of the top of the reactor body, and the liquid inlet is connected to the bottom of the liquid storage layer through a liquid inlet pipe.
[0008] Preferably, the distribution plate is a porous disc.
[0009] Preferably, the height of the intermediate pipe is calculated based on the volume flow rate of the feed material, the inner diameter of the equipment, the outer diameter of the intermediate pipe, and the residence time of the material.
[0010] Preferably, the filter is composed of a plurality of metal discs with nearly 80% of the center hollowed out, with a fixed required gap between the discs, and the discharge flows from the gap to the liquid outlet. The number of discs is calculated based on the discharge volume flow rate, the required flow rate, and the flow area of the gap.
[0011] A method for preparing a diphthalic acid product comprises the following steps:
[0012] 1. Oxidation section: alkylbenzene is reacted in liquid phase with oxygen in compressed air in an oxidation reactor with acetic acid as solvent and cobalt manganese bromine as catalyst. The reaction product is crystallized, separated and dried to obtain crude phthalic acid (CTA) containing p-carboxybenzaldehyde (4CBA) as the main impurity, crude isophthalic acid (CIA) containing m-carboxybenzaldehyde (3CBA) as the main impurity, or crude phthalic acid (COA) containing o-carboxybenzaldehyde (2CBA) as the main impurity.
[0013] 2. Refining section: CTA or CIA or COA powder or filter cake (CAKE) coming out of the oxidation section contains impurities 4CBA or 3CBA or 2CBA, which will seriously affect the color and quality of downstream bottle flakes, polyester fibers, and coating products. At this time, CTA or CIA or COA powder or filter cake is prepared into slurry with desalted water or recycled water in the process, preheated and dissolved through 4-8 series heat exchangers, and hydrogenation refining process is adopted. With fragile pd / c as catalyst, hydrogen is added to the hydrogenation reactor at 3.5-8.8MPa and 235-290℃ to reduce the impurities 4CBA, 3CBA, and 2CBA to p-toluic acid (pT acid), m-toluic acid (mT acid) or o-toluic acid (oT acid) that are easily soluble in water. In order to avoid disturbances in temperature control and ensure that the slurry entering the pd / C catalyst bed is in a completely dissolved state, a dissolution tank or dissolution tank is set in front of the hydrogenation reactor to intercept the insoluble matter;
[0014] The slurry that is still completely dissolved after the reaction is recrystallized by gradually cooling and reducing the pressure in 3-5 series-connected crystallizers, and then the water-soluble impurities pT acid, mT acid or oT acid reduced by the hydrogenation reaction are washed away with deionized water through a rotary filter or a separator + vacuum filter, and the filter cake of PTA, PIA or POA is separated and sent to a dryer for drying to obtain a high-purity diphthalic acid product.
[0015] Beneficial effects of the present invention:
[0016] The present invention simplifies and shortens the dissolving tank + hydrogenation reactor into a single hydrogenation reactor, and the hydrogenation reactor is provided with an inner barrel (liquid storage layer) and a dispersion plate of an overflow pipe (intermediate pipe), replacing the original high-cost and large dissolving tank and distribution plate in the hydrogenation reactor. The material stays in the inner barrel for 5 minutes, preferably within 3 minutes. The hydrogenation reactor is provided with a plurality of metal discs, and filters with fixed gaps between the discs replace the high-cost, poor-strength and easily damaged Jonsonscreen filters. The present invention can reduce the investment costs of equipment, pipelines, etc., shorten the process flow and reduce the space layout. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments;
[0018] Figure 1 It is a schematic diagram of the structure of the present invention. DETAILED DESCRIPTION
[0019] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.
[0020] Reference Figure 1 The present specific embodiment adopts the following technical scheme: a hydrogenation reactor for diphthalic acid products, comprising a reactor body 1, a liquid storage layer 2 is arranged on the upper part of the reactor body 1, an intermediate tube 3 is arranged in the liquid storage layer 2, a distribution plate 4 is arranged at the bottom of the intermediate tube 3, a catalyst layer 6 is arranged below the distribution plate 4, a liquid outlet 7 is arranged at the center of the bottom of the reactor body 1, a filter 5 is arranged above the liquid outlet 7, a liquid inlet 8 is arranged on one side of the top of the reactor body 1, and the liquid inlet 8 is connected to the bottom of the liquid storage layer 2 through a liquid inlet pipe.
[0021] It is worth noting that the distribution plate 4 is a porous disc.
[0022] It is worth noting that the height of the intermediate pipe 3 is calculated based on the volume flow rate of the feed material, the inner diameter of the equipment, the outer diameter of the intermediate pipe, and the residence time of the material.
[0023] In addition, the filter 5 is composed of a plurality of metal discs with nearly 80% of the center hollowed out, and a fixed required gap is left between the discs. The discharge flows from the gap to the liquid outlet 7. The number of discs is calculated based on the discharge volume flow rate, the required flow rate, and the flow area of the gap.
[0024] This specific implementation method connects the two devices of the dissolving tank + hydrogenation reactor in the old device in series and integrates them into a single hydrogenation reactor through optimized design. A liquid storage layer is set on the upper part of the hydrogenation reactor, and the height of the liquid storage layer depends on the intermediate tube, and the intermediate tube is calculated based on the volume flow rate of the feed, the inner diameter of the equipment, the outer diameter of the intermediate tube, and the residence time of the material. The material overflows through the inner wall of the intermediate tube and flows into the distribution plate, and the distribution plate achieves effective distribution of the material through a uniquely designed porous disc. The filter with a special structural design can effectively isolate the catalyst particles while ensuring the smooth flow of the material, and the strength-enhanced design can greatly extend its service life. Compared with the conventional Johnson screen filter, the filter has significantly enhanced strength and greatly improved service life. It can be widely used in equipment such as water supply and drainage, chemical and petrochemical processes, minerals, papermaking and food processing.
[0025] This specific implementation can reduce the number of dissolving tank units and related pressure pipes and pipe fittings in the process, thereby simplifying the process, saving layout space, and reducing costs.
[0026] Example 1: A method for preparing a diphthalic acid product such as purified terephthalic acid (PTA), purified isophthalic acid (PIA) or purified phthalic acid (POA) is divided into two sections, namely an oxidation section and a refining section, and the specific steps are as follows:
[0027] 1. Oxidation section: alkylbenzenes such as p-xylene, m-xylene and o-xylene are reacted in liquid phase with oxygen in compressed air in an oxidation reactor with acetic acid as solvent and cobalt manganese bromine as catalyst. The reaction products are crystallized, separated and dried to obtain crude phthalic acid (CTA) containing p-carboxybenzaldehyde (4CBA) as a main impurity, crude isophthalic acid (CIA) containing m-carboxybenzaldehyde (3CBA) as a main impurity, or crude phthalic acid (COA) containing o-carboxybenzaldehyde (2CBA) as a main impurity.
[0028] 2. Refining section: CTA or CIA or COA powder or filter cake (CAKE) from the oxidation section contains impurities 4CBA or 3CBA or 2CBA, which will seriously affect the color and quality of downstream bottle flakes, polyester fibers, coatings and other products. At this time, CTA or CIA or COA powder or filter cake is prepared into slurry with desalted water or recycled water in the process, preheated and dissolved through multi-stage (4-8) series heat exchangers, and hydrogenation refining process is adopted. With fragile pd / c as catalyst, hydrogen is added to the high temperature and high pressure hydrogenation reactor to reduce the impurities 4CBA, 3CBA, 2CBA to p-toluic acid (pT acid), m-toluic acid (mT acid) or o-toluic acid (oT acid) which are easily soluble in water. In order to avoid the disturbance of temperature control and ensure that the slurry entering the pd / C catalyst bed is in a completely dissolved state, a dissolving tank or dissolving tank is generally set before the hydrogenation reactor to intercept the insoluble matter. If insoluble matter enters the catalyst bed, it may cause the catalyst bed to be crushed and damaged.
[0029] The slurry that is still completely dissolved after the reaction is recrystallized by gradually cooling and reducing the pressure in 3-5 series-connected crystallizers, and then the water-soluble impurities pT acid, mT acid or oT acid reduced by the hydrogenation reaction are washed away with deionized water through a rotary filter or a separator + vacuum filter, and the filter cake of PTA, PIA or POA is separated and sent to a dryer for drying to obtain high-purity purified terephthalic acid PTA, purified isophthalic acid PIA or purified phthalic acid POA.
[0030] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.
Claims
1. A hydrogenation reactor for diphthalic acid products, characterized in that: The invention comprises a reactor body (1), wherein a liquid storage layer (2) is arranged on the upper part of the reactor body (1), an intermediate tube (3) is arranged in the liquid storage layer (2), a distribution plate (4) is arranged at the bottom of the intermediate tube (3), a catalyst layer (6) is arranged below the distribution plate (4), a liquid outlet (7) is arranged at the center of the bottom of the reactor body (1), a filter (5) is arranged above the liquid outlet (7), and a liquid inlet (8) is arranged on one side of the top of the reactor body (1), and the liquid inlet (8) is connected to the bottom of the liquid storage layer (2) through a liquid inlet tube.
2. A hydrogenation reactor for diphthalic acid products according to claim 1, characterized in that: The distribution plate (4) is a porous disc.
3. A hydrogenation reactor for diphthalic acid products according to claim 1, characterized in that: The height of the intermediate pipe (3) is calculated based on the volume flow rate of the feed material, the inner diameter of the equipment, the outer diameter of the intermediate pipe, and the residence time of the material.
4. A hydrogenation reactor for diphthalic acid products according to claim 1, characterized in that: The filter (5) is composed of a plurality of metal discs with nearly 80% of the center hollowed out, and a fixed required gap is left between the discs. The discharge flows from the gap to the liquid outlet (7). The number of discs is calculated based on the discharge volume flow rate, the required flow rate, and the flow area of the gap.
5. The method of preparing a diphthalic acid product by using the hydrogenation reactor according to claim 1-4, characterized in that: The following steps are involved: (1) Oxidation stage: alkylbenzene is reacted in liquid phase with oxygen in compressed air in an oxidation reactor with acetic acid as solvent and cobalt manganese bromine as catalyst. The reaction product is crystallized, separated and dried to obtain crude phthalic acid (CTA) containing p-carboxybenzaldehyde (4CBA) as a main impurity, crude isophthalic acid (CIA) containing m-carboxybenzaldehyde (3CBA) as a main impurity, or crude orthophthalic acid (COA) containing o-carboxybenzaldehyde (2CBA) as a main impurity. (2) Refining section: CTA or CIA or COA powder or filter cake (CAKE) from the oxidation section contains impurities 4CBA or 3CBA or 2CBA, which will seriously affect the color and quality of downstream bottle flakes, polyester fibers, and coating products. At this time, CTA or CIA or COA powder or filter cake is prepared into slurry with desalted water or recycled water in the process, preheated and dissolved in 4-8 series heat exchangers, and hydrogenation refining process is adopted. With fragile pd / c as catalyst, hydrogen is added to the hydrogenation reactor at 3.5-8.8MPa and 235-290℃ to reduce the impurities 4CBA, 3CBA, and 2CBA to p-toluic acid (pT acid), m-toluic acid (mT acid) or o-toluic acid (oT acid) which are easily soluble in water; in order to avoid the disturbance of temperature control and ensure that the slurry entering the pd / C catalyst bed is in a completely dissolved state, a dissolving tank or dissolving tank is set before the hydrogenation reactor to intercept the insoluble matter; The slurry that is still completely dissolved after the reaction is recrystallized by gradually cooling and reducing the pressure in 3-5 series-connected crystallizers, and then the water-soluble impurities pT acid, mT acid or oT acid reduced by the hydrogenation reaction are washed away with deionized water through a rotary filter or a separator + vacuum filter, and the filter cake of PTA, PIA or POA is separated and sent to a dryer for drying to obtain a high-purity diphthalic acid product.