Process system for producing formaldehyde by fluidized bed
By connecting the reactor to the regenerator in the fluidized bed to form a circulating fluidized bed, the discontinuity of the fixed bed reactor and the easy catalyst deactivation problems are solved, and the high yield and selectivity of formaldehyde is achieved, which reduces energy consumption and operation difficulty.
Patent Information
- Application Number
- CN202510500909.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2025-07-04
AI Technical Summary
The existing fixed-bed reactors have problems such as discontinuity, local overheating of the reactor, easy catalyst deactivation, high lamination drop, and high operation difficulty in production, resulting in low formaldehyde selectivity, low yield and short catalyst life.
The fluidized bed process is used to connect the reactor to the regenerator to form a circulating fluidized bed. The catalyst is burned and regenerated in the regenerator and returned to the reactor to maintain the catalyst activity. Continuous production is achieved through the circulating fluidized bed, and formaldehyde yield and selectivity are improved.
The high yield and selectivity of formaldehyde are achieved, the reactor pressure drop is reduced, the stability and operating elasticity of the catalyst are improved, and energy consumption and production costs are reduced.
Smart Images
Figure CN120242898A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of fluidized beds, and more specifically, to a process system for producing formaldehyde in a fluidized bed. Background Art
[0002] Formaldehyde is the simplest aldehyde organic compound and an important chemical raw material. It is widely used in plywood, plastics, and the production of urea-formaldehyde resin (UF), phenolic resin (PF), melamine-formaldehyde resin (MF), etc.; it can improve the wrinkle resistance of fabrics and be used as a wrinkle-proof finishing agent; it is used for medical device disinfection, and a 37% formaldehyde solution is also called formalin; it is used as a pesticide and fumigant, such as for seed disinfection; it is used in the manufacture of artificial boards, such as adhesives in density boards and particle boards.
[0003] Industrially, formaldehyde is mainly produced by two methods. One is the silver catalysis method (also called the methanol oxidative dehydrogenation method), and the other is the iron-molybdenum catalysis method (also called the methanol direct oxidation method). The silver catalysis method accounts for 30% - 40%, and the iron-molybdenum catalysis method accounts for 60% - 70%. Currently, the proportion of the iron-molybdenum catalysis method in China is increasing year by year.
[0004] The iron-molybdenum catalysis method for producing formaldehyde all uses a fixed-bed reactor because the structure of the fixed-bed reactor is simple and the technology is relatively mature. However, the production of the fixed-bed reactor is discontinuous, the heat transfer efficiency is low, which easily leads to local overheating of the reactor, causing catalyst sintering or side reactions to occur, and the temperature distribution in the reactor is uneven, directly affecting the selectivity of formaldehyde and the service life of the catalyst, resulting in a low formaldehyde yield. In the production of formaldehyde by the fixed-bed iron-molybdenum catalysis method, carbon deposition occurs on the catalyst during long-term operation, leading to easy deactivation of the catalyst; catalyst particles cause an increase in the pressure drop of the fixed-bed layer; the fixed-bed reactor is difficult to quickly adjust the load, is prone to getting out of control when the methanol feed fluctuates, has a large operation difficulty, a small operation flexibility, a low heat utilization rate, and high energy consumption. Summary of the Invention
[0005] In view of the above problems, the purpose of the present invention is to provide a process system for producing formaldehyde in a fluidized bed, which connects a reactor to a regenerator. The catalysts in the reactor and the regenerator are fluidized to form a circulating fluidized bed. After the catalyst in the reactor is deactivated, it is sent to the regenerator for coke burning and regeneration. The regenerated catalyst in the regenerator is sent to the reactor to participate in the reaction, always keeping the catalyst in the reactor in the best state, with a high methanol conversion rate, few by-products, good formaldehyde selectivity, high formaldehyde yield, circulating fluidization of the reactor and the regenerator, small pressure drop in the reactor, good heat transfer effect, ensuring the activity and stability of the catalyst, enabling continuous production, small load adjustment, small operation difficulty, and large operation flexibility.
[0006] The technical solution adopted by the present invention is as follows:
[0007] A process system for producing formaldehyde in a fluidized bed, comprising a methanol raw material conveying pipe, the methanol raw material conveying pipe is connected with a methanol vaporizer, the methanol vaporizer is connected with a reactor through a pipeline, an air input pipe is connected to the pipeline connecting the methanol vaporizer and the reactor, the bottom of the reactor is connected with a regenerator through a pipeline, the bottom of the regenerator is communicated with the reactor through a pipeline, the top of the reactor is connected with a quench tower through a pipeline, the top of the quench tower is connected with an absorption tower through a pipeline, and a formaldehyde output pipe is arranged at the bottom of the absorption tower.
[0008] Preferably, a feed superheater is arranged on the pipeline connecting the methanol vaporizer and the reactor, and the air input pipe is connected to the pipeline between the methanol vaporizer and the feed superheater.
[0009] Preferably, the pipeline at the top of the reactor is communicated with the heat source inlet of the feed superheater, and the heat source outlet of the feed superheater is communicated with the quench tower.
[0010] Preferably, the top of the absorption tower is connected with the pipeline between the methanol vaporizer and the feed superheater through a pipeline.
[0011] Preferably, a mixer is arranged on the pipeline connecting the methanol vaporizer and the reactor, and the mixer is located between the feed superheater and the reactor.
[0012] Preferably, a first coarse cyclone separator is arranged in the reactor, and a first fine cyclone separator located between the feed superheater and the reactor is arranged on the pipeline at the top of the reactor.
[0013] Preferably, a second coarse cyclone separator is arranged in the regenerator, the top of the regenerator is connected with a second fine cyclone separator through a pipeline, and the second fine cyclone separator is connected with a flue gas output pipe.
[0014] Preferably, the reactor is connected with a first heat exchanger.
[0015] Preferably, the regenerator is connected with a second heat exchanger.
[0016] Preferably, the regenerator is communicated with the air input pipe through a pipeline.
[0017] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:
[0018] Connect the reactor to the regenerator. The catalyst in the reactor and the regenerator fluidizes to form a circulating fluidized bed. After the catalyst in the reactor is deactivated, it is sent to the regenerator for coke burning and regeneration. The regenerated catalyst in the regenerator is sent to the reactor to participate in the reaction, always keeping the catalyst in the reactor in the best state, with high methanol conversion rate, few by-products, good formaldehyde selectivity, high formaldehyde yield, circulating fluidization between the reactor and the regenerator, small pressure drop in the reactor, good heat transfer effect, ensuring the activity and stability of the catalyst, enabling continuous production, small load adjustment, low operation difficulty, and large operation flexibility. Brief Description of the Drawings
[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.
[0020] Figure 1 It is a process schematic diagram provided for the embodiments of the present invention;
[0021] Reference Numerals: 1 - Reactor; 2 - Regenerator; 3 - Methanol Vaporizer; 4 - Feed Superheater; 5 - Mixer; 6 - First Fine Cyclone Separator; 7 - Quench Tower; 8 - Absorption Tower; 9 - Compressor; 10 - Second Fine Cyclone Separator; 11 - First Heat Exchanger; 12 - Second Heat Exchanger; 13 - First Coarse Cyclone Separator; 14 - Second Coarse Cyclone Separator; 101 - Methanol Feed Pipe; 102 - Air Input Pipe; 103 - Flue Gas Output Pipe; 104 - Drain Pipe; 105 - Formaldehyde Output Pipe. Detailed Embodiments
[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.
[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.
[0024] In the description of the present invention, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.
[0025] The following will Figure 1 describe the present invention in detail.
[0026] Embodiment
[0027] A process system for producing formaldehyde in a fluidized bed includes a methanol raw material delivery pipe 101. The methanol raw material delivery pipe 101 is connected to a methanol vaporizer 3. The methanol vaporizer 3 is connected to a reactor 1 through a pipeline. An air input pipe 102 is connected to the pipeline connecting the methanol vaporizer 3 and the reactor 1. The bottom of the reactor 1 is connected to a regenerator 2 through a pipeline. The bottom of the regenerator 2 is communicated with the reactor 1 through a pipeline. The top of the reactor 1 is connected to a quench tower 7 through a pipeline. The top of the quench tower 7 is connected to an absorption tower 8 through a pipeline. A formaldehyde output pipe 105 is provided at the bottom of the absorption tower 8.
[0028] A compressor 9 is provided on the air input pipe 102 for compressing and transporting air. Methanol raw material enters the methanol vaporizer 3 from the methanol raw material delivery pipe 101 and is vaporized. The vaporized methanol raw material is mixed with compressed air and enters the reactor 1 for reaction. During the reaction process, the reactor 1 transports the catalyst to be regenerated to the regenerator 2 for coke burning and regeneration to obtain the regenerated catalyst. The regenerated catalyst returns to the reactor 1 through the pipeline, thus forming a circulating fluidized bed. The reaction gas generated by the reactor 1 is washed and cooled by the quench tower 7 to separate the reaction gas at the top of the tower and the water at the bottom of the tower. A drain pipe 104 is provided at the bottom of the quench tower 7, and the water at the bottom of the tower is discharged out of the tower through the drain pipe 104. The reaction gas at the top of the tower enters the absorption tower 8 and is absorbed to obtain the formaldehyde product, and the formaldehyde product is discharged and collected through the formaldehyde output pipe 105.
[0029] Among them, the production of formaldehyde from methanol is a by-product water reaction. After the water produced by the quench tower 7 is treated, it can be used as circulating water or industrial washing water, improving the utilization rate of water and being more environmentally friendly.
[0030] On the pipeline connecting the methanol vaporizer 3 and the reactor 1, a feed superheater 4 is provided. The air input pipe 102 is connected to the pipeline between the methanol vaporizer 3 and the feed superheater 4. The vaporized methanol raw material and the compressed air are superheated by the feed superheater 4 to make the feed reach the suitable feed temperature for the reaction, improve the methanol conversion rate, improve the formaldehyde selectivity, and improve the formaldehyde yield. The feed superheater 4 can be provided with 2 to 8 groups of cold methanol nozzles for adjusting the feed temperature, with high operation flexibility and easy control of the reaction feed temperature.
[0031] The pipeline at the top of the reactor 1 is communicated with the heat source inlet of the feed superheater 4, and the heat source outlet of the feed superheater 4 is communicated with the quench tower 7. The high-temperature reaction gas output from the top of the reactor 1 enters the feed superheater 4 as a heat source to heat and process the methanol raw material and the compressed air, improving the heat utilization rate, reducing the energy consumption, and reducing the production cost.
[0032] The top of the absorption tower 8 is connected to the pipeline between the methanol vaporizer 3 and the feed superheater 4 through a pipeline. The gas output from the top of the absorption tower 8 enters the reactor 1 again to participate in the reaction, improving the formaldehyde yield and the utilization rate of by-products.
[0033] A mixer 5 is provided on the pipeline connecting the methanol vaporizer 3 and the reactor 1, and the mixer 5 is located between the feed superheater 4 and the reactor 1. The superheated methanol and the compressed air feed are mixed by the mixer 5 to make the methanol and the air fully and evenly mixed for feeding, improving the conversion rate and the methanol product yield.
[0034] A first coarse cyclone separator 13 is provided in the reactor 1, and a first fine cyclone separator 6 is provided on the pipeline at the top of the reactor 1 and is located between the feed superheater 4 and the reactor 1. Both the first coarse cyclone separator 13 and the first fine cyclone separator 6 are cyclone separators. The first coarse cyclone separator 13 removes the catalysts with larger particle sizes, making the catalysts fall into the dense phase bed of the reactor 1 to continue participating in the reaction. The gas separated by the first coarse cyclone separator 13 then enters the first fine cyclone separator 6, and the catalyst fine powder in the gas is further separated. The catalyst fine powder is collected and processed or reused to avoid clogging the subsequent equipment with the catalyst.
[0035] A second coarse cyclone separator 14 is provided in the regenerator 2. The top of the regenerator 2 is connected by a pipeline to a second fine cyclone separator 10, and the second fine cyclone separator 10 is connected to a flue gas output pipe 103. Both the second coarse cyclone separator 14 and the second fine cyclone separator 10 are cyclone separators. The second coarse cyclone separator 14 removes catalysts with larger particle sizes in the flue gas. The catalysts separated by the second coarse cyclone separator 14 fall into the regenerator 2 for recycling. The separated gas then enters the second fine cyclone separator 10 to separate the fine catalyst powder in the gas, avoiding catalyst blockage of subsequent equipment. The flue gas output pipe 103 is connected to a downstream waste heat system to recover heat, and can produce steam required in the production device, with high heat utilization rate, low energy consumption, and low production cost.
[0036] Gas collection chambers are provided at the tops of both the reactor 1 and the regenerator 2. The gas collection chambers are connected to the coarse cyclone separators. The gas separated by the coarse cyclone separators enters the fine cyclone separators through the gas collection chambers for further separation.
[0037] The reactor 1 is connected to a first heat extractor 11. The production of formaldehyde from methanol is an exothermic reaction. The first heat extractor 11 is used to keep the reaction temperature in equilibrium. The first heat extractor 11 extracts the reaction heat and simultaneously uses the reaction heat to produce steam required in the device, with high heat utilization rate and low energy consumption. The regenerator 2 is connected to a second heat extractor 12. The burning of the catalyst is an exothermic regeneration. The second heat extractor 12 is used to keep the regeneration temperature in equilibrium. The second heat extractor 12 extracts the regeneration heat and simultaneously uses the regeneration heat to produce steam required in the device, with high heat utilization rate and low energy consumption.
[0038] The regenerator 2 is connected to the air input pipe 102 through a pipeline. The air input pipe 102 inputs air into the regenerator 2 to assist in burning and regeneration.
[0039] The present invention also provides a method for producing formaldehyde, which includes the following steps:
[0040] Step 1: Feed the methanol raw material into the methanol vaporizer 3. The methanol vaporizer 3 vaporizes methanol using low-low pressure or low-pressure superheated steam. The vaporized gaseous methanol is mixed with compressed air and enters the feed superheater 4. The feed superheater 4 superheats the feed using the heat of the reaction gas. The superheated methanol and air are mixed in the mixer 5 and then enter the reactor 1 for reaction.
[0041] Step 2: The uniformly mixed methanol and air enter the reactor 1 for reaction. The reaction gas is separated by the first coarse cyclone separator 13 and the first fine cyclone separator 6, and then superheats the methanol and air through the feed superheater 4. The superheated reaction gas enters the quench tower 7 for washing and cooling, separating the reaction gas at the top of the tower and the water at the bottom of the tower. The water is sent outside the device. The reaction gas at the top of the tower is absorbed by the absorption tower 8 to obtain the formaldehyde product. The gas phase at the top of the absorption tower 8 enters the reactor 1 for reaction again after passing through the feed superheater 4.
[0042] Step 3: The catalyst fluidization between the reactor 1 and the regenerator 2 forms a circulating fluidized bed. The deactivated catalyst in the reactor 1 is fluidized into the regenerator 2. In the regenerator 2, the catalyst is regenerated by burning coke with the air compressed by the compressor 9, so that the catalyst restores its activity. The regenerated catalyst with restored activity is fluidized into the reactor 1 to participate in the reaction. The flue gas of the regenerator 2 is separated from the catalyst by the second coarse cyclone separator 14 and the second fine cyclone separator 10, and the flue gas enters the downstream waste heat system to recover heat, producing the low low-pressure or low-pressure steam required in the device.
[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A process system for producing formaldehyde in a fluidized bed, characterized in that, It includes a methanol raw material delivery pipe (101). The methanol raw material delivery pipe (101) is connected to a methanol vaporizer (3). The methanol vaporizer (3) is connected to a reactor (1) through a pipeline. An air input pipe (102) is connected to the pipeline connecting the methanol vaporizer (3) and the reactor (1). The bottom of the reactor (1) is connected to a regenerator (2) through a pipeline. The bottom of the regenerator (2) is communicated with the reactor (1) through a pipeline. The top of the reactor (1) is connected to a quench tower (7) through a pipeline. The top of the quench tower (7) is connected to an absorption tower (8) through a pipeline. A formaldehyde output pipe (105) is arranged at the bottom of the absorption tower (8).
2. The process system for producing formaldehyde by fluidized bed according to claim 1, characterized in that, A feed superheater (4) is arranged on the pipeline connecting the methanol vaporizer (3) and the reactor (1). The air input pipe (102) is connected to the pipeline between the methanol vaporizer (3) and the feed superheater (4).
3. A process system for producing formaldehyde in a fluidized bed according to claim 2, characterized in that, The pipeline at the top of the reactor (1) is communicated with the heat source inlet of the feed superheater (4), and the heat source outlet of the feed superheater (4) is communicated with the quench tower (7).
4. The process system for producing formaldehyde by a fluidized bed according to claim 2, wherein, The top of the absorption tower (8) is connected to the pipeline between the methanol vaporizer (3) and the feed superheater (4) through a pipeline.
5. A process system for producing formaldehyde by fluidized bed according to claim 2, characterized in that, A mixer (5) is arranged on the pipeline connecting the methanol vaporizer (3) and the reactor (1), and the mixer (5) is located between the feed superheater (4) and the reactor (1).
6. The process system for producing formaldehyde in a fluidized bed according to claim 2, wherein, A first coarse cyclone separator (13) is arranged in the reactor (1), and a first fine cyclone separator (6) located between the feed superheater (4) and the reactor (1) is arranged on the pipeline at the top of the reactor (1).
7. A process system for producing formaldehyde in a fluidized bed according to claim 1, characterized in that, A second coarse cyclone separator (14) is arranged in the regenerator (2). The top of the regenerator (2) is connected to a second fine cyclone separator (10) through a pipeline. The second fine cyclone separator (10) is connected to a flue gas output pipe (103).
8. A process system for producing formaldehyde in a fluidized bed according to claim 1, characterized in that, The reactor (1) is connected to a first heat exchanger (11).
9. A process system for producing formaldehyde in a fluidized bed according to claim 1, characterized in that, The regenerator (2) is connected to a second heat exchanger (12).
10. A process system for producing formaldehyde in a fluidized bed according to claim 1, characterized in that, The regenerator (2) is communicated with the air input pipe (102) through a pipeline.