Methanol-to-olefin starting system
The methanol-to-olefins start-up system, which combines medium-pressure superheated steam and an auxiliary combustion chamber, solves the safety hazards and high costs during the start-up process, and achieves safe, reliable and low-cost start-up.
Patent Information
- Application Number
- CN202422778493.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2034-11-14
AI Technical Summary
During the start-up of the methanol to olefins unit, the fuel gas composition and pressure of the start-up heating furnace are unstable and prone to flameout, posing a safety hazard. The nitrogen and fuel consumption are high, resulting in high start-up costs.
Use medium-pressure superheated steam in conjunction with the auxiliary combustion chamber to heat up and start the process, avoiding the use of a start-up heating furnace. Use medium-pressure superheated steam and the auxiliary combustion chamber to jointly heat the reactor and regenerator, and combine with heat exchangers, deliquescence packages and other equipment to optimize the process layout.
It reduces the start-up cost and investment cost, improves safety, reduces the consumption of nitrogen and fuel gas, is easy to operate and has a reasonable structure.
Smart Images
Figure CN223324506U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of methanol to olefins, in particular to a methanol to olefins start-up system. Background Art
[0002] Methanol-to-olefins (MTO) technology was developed based on my country's relatively abundant coal resources. Using methanol synthesized from coal or natural gas as a feedstock, it produces low-carbon olefins through a fluidized-bed reaction in a MTO unit. This technology is a core technology for developing non-petroleum-based production of products such as ethylene and propylene.
[0003] The methanol-to-olefins unit consists of a reaction and regeneration zone, a quenching and stripping zone, and a heat recovery zone. The reaction and regeneration zone primarily comprises a methanol feed system, a reaction and regeneration system, and a main air system. The feed system utilizes a vapor-phase feed method. Liquid methanol from outside the boundary zone is heated, vaporized, and superheated before entering the reactor for reaction. The reaction product is separated by a three-stage cyclone separator to recover a small amount of entrained fines and then sent to a quenching and water scrubber. The reaction and regeneration system utilizes a circulating fluidized bed and incomplete regeneration process. The main air system is equipped with two electric centrifugal main blowers, one in operation and one in standby, to provide sufficient air for regeneration and charring. The quenching and stripping zone primarily comprises a quenching tower, a water scrubber, and a wastewater stripper. The reaction gas from the reaction system is cooled and used to wash the catalyst in the quenching and water scrubber. Most of the heated low-temperature water is sent to the olefin separation unit for separation, refining, and heat exchange for reuse. The water condensed in the quenching and water scrubbing system is recycled to the wastewater stripper to recover a small amount of methanol, dimethyl ether, and other organic matter for refining. The heat recovery area mainly includes the internal and external heat exchangers of the regenerator, the CO incinerator and the waste heat boiler. Its main function is to recover the heat generated during the catalyst regeneration and burning process and produce medium-pressure superheated steam as a by-product.
[0004] The main difficulties and key points in the start-up of a methanol to olefins unit are in the reaction regeneration area. The start-up of a methanol to olefins unit mainly involves increasing the temperature of the reactor and the regenerator. The reactor is heated with nitrogen heated by the start-up heating furnace, and the regenerator is heated with main air heated by the auxiliary combustion chamber. When the temperature of the reactor and regenerator reaches the highest constant temperature point, cold catalyst is added, and the temperature is continued to be increased to maintain the catalyst temperature of the reactor and regenerator, so that the catalyst in the reactor reaches a temperature point where gas phase methanol can be introduced to react. The main focus during the start-up process is to increase the temperature of the reactor and regenerator to ensure that the catalyst temperature is at a favorable condition.
[0005] At present, during the start-up process of the methanol to olefins unit, a start-up heating furnace is needed to heat nitrogen to heat the reactor. The start-up heating furnace is prone to flameout when the fuel gas composition and pressure are unstable, which poses a safety hazard and has a high risk factor. In addition, the nitrogen consumption is large and the fuel consumption is high, resulting in high start-up costs. Utility Model Content
[0006] In response to the above problems, the purpose of the present utility model is to provide a methanol to olefins start-up system, which uses medium-pressure superheated steam in conjunction with an auxiliary combustion chamber to heat up the system for start-up. The system is easy to operate, has a simple structure, a reasonable layout, saves nitrogen and fuel gas, and reduces start-up costs and investment costs. It avoids the use of a start-up heating furnace to start the system, thereby reducing risks and being safer and more reliable.
[0007] The technical solutions adopted in this utility model are as follows:
[0008] A methanol-to-olefins start-up system comprises a methanol tank, a reactor, and a regenerator connected to the reactor. The reactor is provided with a feed pipe connected to a medium-pressure steam inlet pipe. The regenerator is connected to an auxiliary combustion chamber. The bottom of the methanol tank is connected to a heat exchanger A via a pipeline. The heat exchanger A is connected to the feed pipe via a pipeline. The top of the reactor is connected to a heat source inlet of the heat exchanger A via a pipeline.
[0009] Preferably, the heat exchanger a is connected in parallel with a bypass pipeline, and the cold source inlet and the bypass pipeline of the heat exchanger a are both provided with valves.
[0010] Preferably, heat exchanger b and heat exchanger c are sequentially arranged in the pipeline at the bottom of the methanol tank.
[0011] Preferably, a methanol deliquoring bag is provided in the pipeline at the bottom of the methanol tank and is located between the heat exchanger c and the bypass line.
[0012] Preferably, the bottom of the methanol deliquoring bag is connected to a methanol collecting tank via a pipeline, the top of the methanol collecting tank is connected to a nitrogen inlet pipe, and the bottom of the methanol collecting tank is connected to the methanol tank via a pipeline.
[0013] Preferably, the bottom of the reactor is connected to a regenerator with a catalyst delivery pipe to be regenerated, and a regeneration valve is provided in the catalyst delivery pipe to be regenerated; the bottom of the regenerator is connected to a regenerated catalyst delivery pipe to be connected to the reactor, and a regeneration valve is provided in the regenerated catalyst delivery pipe.
[0014] Preferably, the catalyst delivery pipe to be generated is connected to a stripping hot nitrogen inlet pipe.
[0015] Preferably, a reaction triplex is provided on the pipeline between the reactor and the heat exchanger a.
[0016] Preferably, a methanol pump is provided in the bottom pipe of the methanol tank.
[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0018] The use of medium-pressure superheated steam in conjunction with the auxiliary combustion chamber to heat up and start the operation is easy to operate, with a simple structure and reasonable layout. It saves nitrogen and fuel gas, reduces the start-up cost and investment cost; it avoids the use of a start-up heating furnace to start the operation, thereby reducing danger and being safer and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.
[0020] Figure 1 A schematic diagram of a process flow provided for an embodiment of the present utility model.
[0021] Figure markings: 1-reactor; 2-regenerator; 3-reaction three-cyclone; 4-heat exchanger a; 5-methanol tank; 6-methanol pump; 7-heat exchanger b; 8-heat exchanger c; 9-methanol collecting tank; 10-methanol deliquescence bag; 11-auxiliary combustion chamber; 12-waiting valve; 13-regeneration valve; 14-medium-pressure steam inlet pipe; 15-stripping hot nitrogen inlet pipe; 16-nitrogen inlet pipe; 17-bypass pipeline; 18-waiting catalyst delivery pipe; 19-regenerated catalyst delivery pipe; 20-feed pipe. DETAILED DESCRIPTION
[0022] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein 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 accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.
[0024] In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.
[0025] The following combination Figure 1 The utility model is described in detail.
[0026] Example
[0027] A methanol-to-olefins startup system includes a methanol tank 5, a reactor 1, and a regenerator 2 connected to the reactor 1. The reactor 1 is provided with a feed pipe 20 connected to a medium-pressure steam inlet pipe 14. The regenerator 2 is connected to an auxiliary combustion chamber 11. The bottom of the methanol tank 5 is connected to a heat exchanger A4 via a pipeline, which is connected to the feed pipe 20 via a pipeline. The top of the reactor 1 is connected to the heat source inlet of the heat exchanger A4 via a pipeline. A flue gas exhaust pipe is provided at the top of the regenerator 2; a methanol delivery pipe is connected to the methanol tank 5; and a main air line is connected to the auxiliary combustion chamber 11.
[0028] The bottom of the reactor 1 is connected to a regenerator 2 via a feed pipe 18 for regenerated catalyst. A regeneration valve 12 is provided in the feed pipe 18. The bottom of the regenerator 2 is connected to a feed pipe 19 for regenerated catalyst, which is connected to the reactor 1. A regeneration valve 13 is provided in the feed pipe 19. During the reaction, the regenerated catalyst in the reactor 1 enters the regenerator 2 for regeneration. After regeneration, the regenerated catalyst returns to the reactor 1 to participate in the reaction.
[0029] At the initial start-up, auxiliary combustion chamber 11 is used to heat regenerator 2. When the temperature of regenerator 2 reaches 150-200°C, regeneration valve 12 and regeneration valve 13 are opened, connecting reactor 1 for simultaneous temperature increase. When the temperature of regenerator 2 rises to 450-550°C, the temperature of reactor 1 rises to approximately 250-350°C. At this time, medium-pressure steam inlet pipe 14 is slowly switched to output steam to heat reactor 1. When the temperature of reactor 1 rises steadily, regeneration valve 12 and regeneration valve 13 are closed. When adding catalyst to regenerator 2, balancing agent is added first. The amount of catalyst added is adjusted to a ratio of 4-6 between fresh catalyst and balancing agent. This can save the amount of fresh catalyst and thus reduce start-up costs. Medium-pressure steam is medium-pressure superheated steam, which is used for start-up. The temperature is 380-450℃, 3.8-4.5MPa, preferably 420-450℃, 4.0-4.2MPa. Medium-pressure steam is used to heat the start-up. It is suitable for initial start-up and start-up after maintenance, as well as for start-up after various emergency stops.
[0030] After the start-up is completed, methanol enters the methanol tank 5 and is then heated by heat exchanger a4 so that the methanol remains in a gaseous state and enters the reactor 1. At the same time, heat exchanger a4 uses the waste heat of the reaction gas, which can reduce the energy consumption of methanol heating.
[0031] Heat exchanger a4 is connected in parallel with a bypass line 17. Both the cold source inlet of heat exchanger a4 and bypass line 17 are equipped with valves to control the opening and closing of the line. During the initial stage of methanol vaporization into reactor 1, this bypass line 17 is used to slowly switch between the medium-pressure steam and the medium-pressure steam 14 to feed methanol. This slow switching process facilitates system adjustment. After a certain reaction time, the methanol is heated by heat exchanger a4 to prevent methanol condensation due to the initial lack of heat in heat exchanger a4.
[0032] Heat exchangers b7 and c8 are installed in the pipes at the bottom of methanol tank 5. Heat exchanger b7 exchanges heat between methanol and process water, while heat exchanger c8 exchanges heat between methanol and steam, improving the utilization of process water and steam heat. Both heat exchangers heat methanol, preserving it in a gaseous state before it enters reactor 1 to participate in the reaction.
[0033] A methanol deliquescence bag 10 is provided in the pipeline at the bottom of the methanol tank 5, between the heat exchanger c8 and the bypass line 17. The methanol deliquescence bag 10 can perform preliminary recovery of the condensed methanol to avoid waste of methanol.
[0034] The bottom of the methanol stripping bag 10 is connected to the methanol collection tank 9 via a pipeline. The top of the methanol collection tank 9 is connected to a nitrogen inlet pipe 16. The bottom of the methanol collection tank 9 is also connected to the methanol tank 5 via a pipeline. Methanol from the stripping bag 10 enters the methanol collection tank 9 through self-pressure. The methanol in the methanol collection tank 9 is pressurized through the nitrogen inlet pipe 16 at the top and sent to the methanol tank 5, where the condensed methanol is recovered and added value.
[0035] The regenerated catalyst delivery pipe 18 is connected to the stripping hot nitrogen inlet pipe 15. The nitrogen output from the stripping hot nitrogen inlet pipe 15 replaces the reaction gas in the regenerated catalyst, preventing the reaction gas from entering the regenerator 2, causing waste of raw materials and increasing the cracking of olefins in the reaction product.
[0036] The pipeline between the reactor 1 and the heat exchanger a4 is provided with a reaction cyclone 3. The reaction cyclone 3 is a gas-solid separation device containing three cyclones. The reaction cyclone 3 separates solid particles in the reaction gas to avoid clogging the pipeline.
[0037] A methanol pump 6 is provided in the bottom pipeline of the methanol tank 5. The methanol pump 6 transports methanol to ensure the rapid flow of gaseous methanol.
[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.
Claims
1. A methanol to olefins start-up system, comprising a methanol tank (5), a reactor (1) and a regenerator (2) connected to the reactor (1), characterized in that: The reactor (1) is provided with a feed pipe (20), the feed pipe (20) is connected to a medium-pressure steam inlet pipe (14), the regenerator (2) is connected to an auxiliary combustion chamber (11), the bottom of the methanol tank (5) is connected to a heat exchanger a (4) through a pipeline, the heat exchanger a (4) is connected to the feed pipe (20) through a pipeline, and the top of the reactor (1) is connected to a heat source inlet of the heat exchanger a (4) through a pipeline.
2. The methanol to olefins start-up system according to claim 1, characterized in that: The heat exchanger a (4) is connected in parallel with a bypass pipeline (17), and valves are provided at the cold source inlet of the heat exchanger a (4) and the bypass pipeline (17).
3. The methanol to olefins start-up system according to claim 2, characterized in that: Heat exchanger b (7) and heat exchanger c (8) are sequentially arranged in the pipeline at the bottom of the methanol tank (5).
4. The methanol to olefins start-up system according to claim 3, characterized in that: A methanol deliquoring bag (10) is provided in the pipeline at the bottom of the methanol tank (5) and is located between the heat exchanger c (8) and the bypass line (17).
5. The methanol to olefins start-up system according to claim 4, characterized in that: The bottom of the methanol deliquoring bag (10) is connected to a methanol collecting tank (9) via a pipeline, the top of the methanol collecting tank (9) is connected to a nitrogen inlet pipe (16), and the bottom of the methanol collecting tank (9) is connected to a methanol tank (5) via a pipeline.
6. The methanol to olefins start-up system according to claim 1, characterized in that: The bottom of the reactor (1) is connected to a catalyst delivery pipe (18) to be regenerated and connected to the regenerator (2), and a regeneration valve (12) is provided in the catalyst delivery pipe (18). The bottom of the regenerator (2) is connected to a regenerated catalyst delivery pipe (19) to be regenerated and connected to the reactor (1), and a regeneration valve (13) is provided in the regenerated catalyst delivery pipe (19).
7. The methanol to olefins start-up system according to claim 6, characterized in that: The catalyst delivery pipe (18) to be generated is connected to a stripping hot nitrogen inlet pipe (15).
8. The methanol to olefins start-up system according to claim 1, characterized in that: A reaction cyclone (3) is provided on the pipeline between the reactor (1) and the heat exchanger a (4).
9. The methanol to olefins start-up system according to claim 1, characterized in that: A methanol pump (6) is provided in the bottom pipeline of the methanol tank (5).