Method for heating start-up reactor of methanol-to-olefin device

Abstract

The invention discloses a method for heating a start-up reactor of a methanol-to-olefin device. The temperature rising method comprises the steps that the regenerator and the auxiliary combustion chamber are started, air is introduced into the regenerator, the temperature of the regenerator is raised to 150 + / -10 DEG C, and the temperature is kept constant; 2 hours before the constant temperature of the regenerator is finished, starting a start-up heating furnace, introducing pure nitrogen, meanwhile, adjusting the fuel quantity to enable the temperature of nitrogen at an outlet to be 250 + / -10 DEG C, and after the constant temperature is finished, conveying hot nitrogen in the heating furnace to a reactor and raising the temperature to 50 + / -5 DEG C; after the temperature of the reactor is raised, a regeneration slide valve between the regenerator and the reactor is opened, hot air in the regenerator is introduced into the reactor, meanwhile, the temperature of the regenerator is raised to 345 + / -15 DEG C and kept constant, and the temperature of the regenerator is controlled to be 150 + / -30 DEG C higher than that of the reactor; the regenerator is continuously heated to 550 + / -25 DEG C; the heating method for the start-up reactor of the methanol-to-olefin device saves energy, reduces consumption, and is safe, efficient and high in compatibility.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of methanol to olefins, and particularly relates to a heating method for a start-up reactor of a methanol to olefins device. BACKGROUND

[0002] In a start-up process of a methanol to olefins (DMTO) device, the heating operation of a conventional reactor directly affects the start-up time length and energy consumption cost (nitrogen production and heating cost), and the consumption of natural gas and nitrogen is large. The existing process usually uses a gas start-up heating furnace to heat air separation nitrogen, and the hot nitrogen is gradually heated and replaced to raise the temperature of the reactor, so that the size of the equipment and the nitrogen input pipe diameter limit the total amount of the gas source; the nitrogen replacement carries a small amount of dust or other substances, which causes environmental protection problems; the specific heat capacity of the nitrogen is low, the heating efficiency is low, the furnace heating time is long, and the load is high. SUMMARY

[0003] The main purpose of the present application is to provide a heating method for a start-up reactor of a methanol to olefins device to overcome the shortcomings of the prior art.

[0004] In order to achieve the above-mentioned purpose of the application, the technical scheme adopted by the present application comprises:

[0005] The present application provides a heating method for a start-up reactor of a methanol to olefins device, which comprises: the methanol to olefins device comprises a regenerator, a start-up heating furnace, a reactor, an auxiliary combustion chamber, a regeneration slide valve and a pipeline system;

[0006] (1) Start the regenerator and the auxiliary combustion chamber, introduce air into the regenerator, and heat the regenerator to 150±10℃, and then keep the temperature constant for 20h;

[0007] (2) 2h before the end of the constant temperature of the regenerator at 150±10℃, start the start-up heating furnace and introduce pure nitrogen, at the same time, adjust the fuel quantity to make the outlet nitrogen temperature be 250±10℃, and after the constant temperature in step (1) is ended, the hot nitrogen in the heating furnace is transported to the reactor and heated to 50±5℃;

[0008] (3) After the reactor is heated, the regeneration slide valve between the regenerator and the reactor is opened, the hot air in the regenerator is introduced into the reactor to increase the amount of heat source, at the same time, the regenerator is heated to 345±15℃ and kept constant for 28h, and the temperature of the regenerator is controlled to be higher than the temperature of the reactor by 150±30℃;

[0009] (4) After the constant temperature of the regenerator at 345±15℃ is ended, the temperature is continuously raised to 550±25℃ and kept constant for 4h.

[0010] Compared with the prior art, the present application has the following advantages:

[0011] (1) Energy saving and consumption reducing: the present application utilizes the existing equipment and monitoring and analyzing system, reduces the nitrogen consumption by about 6%~12% through the heat air and hot nitrogen gas of regenerator cooperating temperature rising, shortens the start-up temperature rising time by about 5~9%, reduces the natural gas and nitrogen consumption, and improves the reactor temperature rising efficiency;

[0012] (2) Safety and high efficiency: the present application avoids the backflow and oxygen-containing carbon explosion (flying temperature) safety hazard caused by temperature inversion through the control of temperature gradient and the time sequence arrangement of hot nitrogen gas and hot air entering;

[0013] (3) Strong compatibility: the present application does not need to add equipment, and can be realized only by optimizing the operation process, and is suitable for all DMTO devices with regenerator and start-up heating furnace. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and all other drawings obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0015] Figure 1 is the structural schematic diagram of the methanol to olefin device. DETAILED DESCRIPTION

[0016] In view of the defects of the prior art, the present inventors have long-term research and a large number of practices, and have obtained the technical solutions of the present application. The technical solutions of the present application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0017] The present application aims at: (1) saving cost, utilizing the existing facilities of DMTO device regenerator, auxiliary combustion chamber, regeneration slide valve and pipeline system as bypass to increase gas amount; (2) increasing hot air as auxiliary gas source; (3) improving temperature rising speed, reducing displacement temperature rising times and improving environmental pollution. Under the premise of ensuring the safety of the device, the problems of large nitrogen consumption, low reactor temperature rising efficiency and many times of cyclic displacement are solved.

[0018] Specifically, as one aspect of the technical solutions of the present application, a kind of methanol to olefin device reactor temperature rising method includes: the methanol to olefin device includes regenerator, start-up heating furnace, reactor, auxiliary combustion chamber, regeneration slide valve and pipeline system;

[0019] (1) Start the regenerator and auxiliary combustion chamber, introduce air into the regenerator and heat the regenerator to 150±10℃, and then keep it at a constant temperature for 20h;

[0020] (2) Two hours before the regenerator is at 150±10℃, start the start-up heating furnace and introduce pure nitrogen. At the same time, adjust the fuel quantity to make the outlet nitrogen temperature 250±10℃. After the constant temperature in step (1) is completed, transport the hot nitrogen in the heating furnace to the reactor and raise the temperature to 50±5℃.

[0021] (3) After the reactor is heated, the regeneration slide valve between the regenerator and the reactor is opened to introduce hot air from the regenerator into the reactor to increase the heat source. At the same time, the regenerator is heated to 345±15℃ and kept at a constant temperature for 28 hours. The temperature of the regenerator is controlled to be 150±30℃ higher than the temperature of the reactor.

[0022] (4) After the regenerator has reached a constant temperature of 345±15℃, continue to raise the temperature to 550±25℃ and maintain the temperature for 4 hours.

[0023] In some preferred embodiments, the heating method specifically includes: starting the regenerator and auxiliary combustion chamber, introducing air into the regenerator and heating the regenerator to 150±10℃ at a heating rate of ≤10℃ / h, and then maintaining the temperature for 20h.

[0024] Furthermore, temperature sensors are used to monitor the bed temperature distribution in the regenerator in real time and to sample and analyze humidity to ensure that the equipment and catalyst are preheated uniformly and that the humidity of the hot air decreases.

[0025] In some preferred embodiments, the heating method specifically includes: 2 hours before the end of the constant temperature of 150±10℃ in the regenerator, starting the start-up heating furnace, introducing pure nitrogen from the air separation unit into the start-up heating furnace through a nitrogen pipeline, and adjusting the fuel quantity to make the outlet nitrogen temperature 250±10℃. After the constant temperature in step (1) ends, hot nitrogen is transported to the reactor through a hot nitrogen transport pipeline for 2 hours to raise the reactor temperature to 50±5℃.

[0026] In some preferred embodiments, the heating method specifically includes: after the reactor is heated for 2 hours, opening the regeneration slide valve between the regenerator and the reactor to introduce hot air from the regenerator into the reactor, while simultaneously heating the regenerator to 345±15℃ at a heating rate of 10±5℃ / h and maintaining the temperature for 28 hours, controlling the temperature of the regenerator to be 150±30℃ higher than the temperature of the reactor.

[0027] Furthermore, a temperature sensor is used for real-time monitoring to ensure that the temperature of the regenerator is 150±30℃ higher than that of the reactor.

[0028] Furthermore, the moisture content of the gas in the regenerator, reactor, and pipeline is controlled to be <100ppm, and the oxygen content is ≤0.5vol.

[0029] In some preferred embodiments, the heating method specifically includes: after the regenerator has reached a constant temperature of 345℃±15℃, the temperature is continued to rise to 550±25℃ at a heating rate of 18~23±5℃ / h and held at that temperature for 4h. In the later stage of heating, the regeneration slide valve between the regenerator and the reactor is closed, and only hot nitrogen gas from the start-up heating furnace is used for heating.

[0030] Furthermore, the regeneration slide valve between the regenerator and the reactor is closed 12 hours before the temperature is raised to 550±25℃.

[0031] Furthermore, in the later stage of heating, the regeneration slide valve between the regenerator and the reactor is closed, and the system is heated and oxygen is replaced by pipelines to ensure that the oxygen content of the reactor and regenerator system is ≤0.5 vol% and the moisture content is <40 ppm.

[0032] The methanol-to-olefins (MTO) apparatus of this invention includes a regenerator, a start-up heater, a reactor, an auxiliary combustion chamber, a regeneration slide valve, and a piping system, as shown in the schematic diagram. Figure 1 As shown.

[0033] In some more specific implementations, the method for heating the start-up reactor of the methanol-to-olefins unit, based on the existing regenerator, start-up heater, reactor, auxiliary combustion chamber, regeneration slide valve, and piping system, includes the following specific steps:

[0034] Regenerator preheating stage: Start the regenerator auxiliary combustion chamber to introduce air into the regenerator, control the heating rate to ≤10℃ / h, and maintain the regenerator temperature at 150±10℃ / h for 20 hours (optimized to 24 hours). Monitor the regenerator bed temperature distribution in real time using existing temperature sensors and sample and analyze humidity to ensure uniform preheating of the equipment and catalyst and reduction of hot air humidity.

[0035] Initial heating stage of the reactor: Two hours before the regenerator reaches its constant temperature of 150℃±10℃, the start-up heater is activated. Pure nitrogen from the air separation unit is introduced into the heater via the existing nitrogen pipeline, and the fuel flow is adjusted to bring the outlet nitrogen temperature to approximately 250±10℃. After the constant temperature is reached, hot nitrogen is supplied to the reactor via the existing hot nitrogen delivery pipeline for two hours, raising the reactor temperature to approximately 50±5℃.

[0036] Coordinated Heating Phase: After the reactor is heated by hot nitrogen for 2 hours, the existing regeneration slide valve between the regenerator and the reactor is opened to introduce hot air from the regenerator into the reactor, increasing the heat source. Safety Control: Simultaneously, the regenerator temperature is raised to 345±15℃ at a rate of 110±5℃ / h and held at that temperature for 28 hours. The control system monitors the temperature in real time using existing temperature sensors to ensure that the regenerator temperature is always approximately 150±30℃ higher than the reactor temperature to prevent heat backflow. Moisture content is simultaneously monitored to be <100ppm and oxygen content to be reduced to 0.5% (vol).

[0037] High-temperature heating and replacement stage: After the regenerator reaches a constant temperature of 345±15℃, the temperature continues to rise to 550±25℃ and is maintained for 4 hours. During the last 12 hours of heating, the slide valve from the regenerator to the reactor is closed, and pure hot nitrogen is supplied only through the start-up furnace. The existing pipelines are used to heat the system and replace oxygen, reducing the system oxygen content to below 0.5% (vol) and moisture content to <40ppm, meeting the safe feeding standards.

[0038] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0039] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0040] Example 1

[0041] Based on the existing regenerator, start-up heater, reactor, auxiliary combustion chamber, regeneration slide valve, and piping system, the specific steps are as follows:

[0042] (1) Regenerator preheating stage: Start the auxiliary combustion chamber of the regenerator, introduce air into the regenerator, control the heating rate to ≤10℃ / h, and keep the regenerator temperature at 150±10℃ for 20 hours (optimize 24-hour constant temperature time). Monitor the temperature distribution of the regenerator bed in real time through existing temperature sensors and sample and analyze the humidity to ensure that the equipment and catalyst are preheated uniformly and the humidity of the hot air decreases.

[0043] (2) Initial heating stage of the reactor: Two hours before the end of the constant temperature period of 150±10℃ in the regenerator, the start-up heating furnace is started, and pure nitrogen from the air separation unit is introduced into the heating furnace through the existing nitrogen pipeline. The fuel quantity is adjusted so that the outlet nitrogen temperature reaches about 250±10℃. After the constant temperature period ends, hot nitrogen is supplied to the reactor through the existing hot nitrogen supply pipeline for 2 hours to raise the reactor temperature to about 50±5℃.

[0044] (3) Coordinated heating stage: After the reactor is heated by hot nitrogen for 2 hours, the existing regeneration slide valve between the regenerator and the reactor is opened to introduce hot air from the regenerator into the reactor, increasing the heat source. Safety control: At the same time, the regenerator temperature is raised to 345±15℃ at a rate of 10℃ / h and held at that temperature for 28 hours. The control system monitors the temperature in real time through existing temperature sensors to ensure that the regenerator temperature is always about 150±30℃ higher than the reactor temperature to prevent heat backflow. Simultaneously, the moisture content is monitored to be <100ppm and the oxygen content is monitored to be reduced to 0.5% (vol).

[0045] (4) High-temperature heating and replacement stage: After the regenerator is kept at a constant temperature of 345±10℃, the temperature is continued to rise to 550±25℃ and kept at a constant temperature for 4 hours. During the last 12 hours of heating, the slide valve from the regenerator to the reactor is closed, and pure hot nitrogen is supplied only by starting the heating furnace. The existing pipeline is used to heat up the system and replace oxygen, so that the oxygen content of the system is reduced to below 0.5% (vol) and the moisture content is <40ppm, which meets the safety feeding standards.

[0046] Comparative Example 1

[0047] Using existing technology, the normal reactor heating process is as follows: natural gas is used as fuel to heat the nitrogen sent from the air separation unit through the start-up heater, and hot nitrogen at different temperatures is sent to the reactor in stages for gradual heating.

[0048] Characterization results: In Comparative Example 1, the total heating time of the normal reactor was 85 hours, and the nitrogen consumption was 1.615 million Nm³. 3 14,000 Nm³ of natural gas 3 The total heating time using the method described in Example 1 was 80 hours, with an actual time saving of approximately 5 hours (excluding the 4-hour extension of the refractory brick replacement and constant-temperature time compared to the normal heating time). Energy consumption was reduced by 95,000 Nm³ of nitrogen. 3 830 Nm of natural gas 3 Compared with the normal reactor heating in Example 1, the nitrogen consumption is reduced by about 6%, and the start-up heating time is shortened by about 5%. Theoretically, the remaining improvement space can reduce the nitrogen consumption by about 6%-12% and shorten the start-up heating time by about 5-9%.

[0049] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0050] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A method for heating the reactor during startup of a methanol-to-olefins (MTO) plant, characterized in that, include: The methanol-to-olefins unit includes a regenerator, a start-up heater, a reactor, an auxiliary combustion chamber, a regeneration slide valve, and a piping system. (1) Start the regenerator and auxiliary combustion chamber, introduce air into the regenerator and heat the regenerator to 150±10℃, and then keep it at a constant temperature for 20h; (2) Two hours before the regenerator is at 150±10℃, start the start-up heating furnace and introduce pure nitrogen. At the same time, adjust the fuel quantity to make the outlet nitrogen temperature 250±10℃. After the constant temperature in step (1) is completed, transport the hot nitrogen in the heating furnace to the reactor and raise the temperature to 50±5℃. (3) After the reactor is heated, the regeneration slide valve between the regenerator and the reactor is opened to introduce hot air from the regenerator into the reactor to increase the heat source. At the same time, the regenerator is heated to 345±15℃ and kept at a constant temperature for 28 hours. The temperature of the regenerator is controlled to be 150±30℃ higher than the temperature of the reactor. (4) After the regenerator has reached a constant temperature of 345±15℃, continue to raise the temperature to 550±25℃ and maintain the temperature for 4 hours.

2. The heating method according to claim 1, characterized in that, Specifically, it includes: Start the regenerator and auxiliary combustion chamber, introduce air into the regenerator and heat it to 150±10℃ at a heating rate of ≤10℃ / h, then keep it at a constant temperature for 20h.

3. The heating method according to claim 2, characterized in that: Temperature sensors are used to monitor the bed temperature distribution in the regenerator in real time, and humidity is sampled and analyzed.

4. The heating method according to claim 1, characterized in that, Specifically, it includes: Two hours before the regenerator reaches a constant temperature of 150±10℃, the start-up heating furnace is started. Pure nitrogen from the air separation unit is introduced into the start-up heating furnace through a nitrogen pipeline. At the same time, the fuel quantity is adjusted so that the outlet nitrogen temperature is 250±10℃. After the constant temperature in step (1) ends, hot nitrogen is transported to the reactor through a hot nitrogen pipeline for 2 hours to raise the reactor temperature to 50±5℃.

5. The heating method according to claim 1, characterized in that, Specifically, it includes: After the reactor has been heated for 2 hours, the regeneration slide valve between the regenerator and the reactor is opened to introduce hot air from the regenerator into the reactor. At the same time, the regenerator is heated to 345±15℃ at a heating rate of 10±5℃ / h and kept at a constant temperature for 28 hours, controlling the temperature of the regenerator to be 150±30℃ higher than the temperature of the reactor.

6. The heating method according to claim 5, characterized in that: Temperature sensors are used for real-time monitoring to ensure that the temperature of the regenerator is 150±30℃ higher than that of the reactor.

7. The heating method according to claim 5, characterized in that: The moisture content of the gas in the regenerator, reactor and pipeline is controlled to be <100ppm and the oxygen content is ≤0.5vol.

8. The heating method according to claim 1, characterized in that, Specifically, it includes: After the regenerator reaches a constant temperature of 345℃±15℃, the temperature is increased to 550±25℃ at a rate of 18~23±5℃ / h and held for 4 hours. In the later stage of the heating process, the regeneration slide valve between the regenerator and the reactor is closed, and only hot nitrogen gas from the start-up furnace is used for heating.

9. The heating method according to claim 8, characterized in that, Specifically, it includes: Close the regeneration slide valve between the regenerator and the reactor 12 hours before the temperature reaches 550±25℃.

10. The heating method according to claim 8, characterized in that: In the later stage of heating, the regeneration slide valve between the regenerator and the reactor is closed, and the system is heated and oxygen is replaced by pipeline to ensure that the oxygen content of the reactor and regenerator system is ≤0.5 vol% and the moisture content is <40 ppm.

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