MTO-grade methanol rectification device without using steam

Abstract

The utility model provides a steam-free MTO-grade methanol rectification device which comprises a synthesis reactor, a reaction gas feeding pipeline is connected to the synthesis reactor, the synthesis reactor is sequentially connected with a first heat exchanger, a second heat exchanger, a cooler, a separator and an expansion tank, the output end of the first heat exchanger is connected with an expansion flash tank, and the output end of the second heat exchanger is connected with the expansion flash tank. The expansion flash tank is connected with an input end of the multi-stage evaporator, an output end of the multi-stage evaporator is connected with the reboiler, the reboiler is arranged at the bottom of the methanol stabilization tower, a tower kettle of the methanol stabilization tower is connected with an input end of the heat exchanger I, a feeding pipeline is arranged on one side of the methanol stabilization tower, and the multi-stage evaporator is connected with a methanol product extraction pipeline; the heat exchanger I is used for providing a heat source for methanol in the multi-stage evaporator, and preferably, the heat exchanger II is used for preheating fed materials of the methanol stabilizing tower; the steam consumption of the stabilizing tower is saved, the cooling medium of the cold area device is also reduced, and the energy is further saved.

Description

Technical Field

[0001] This application relates to the field of chemical equipment technology, specifically to an MTO-grade methanol distillation unit that does not use steam. Background Technology

[0002] MTO-grade methanol distillation units are an important component of the methanol-to-olefins (MTO) process, which converts methanol into low-carbon olefins (such as ethylene and propylene). They are primarily used to purify crude methanol to meet the purity requirements of the MTO process. They utilize the difference in boiling points between methanol and other impurities (such as water, ethanol, ethers, and esters) through multiple partial vaporization and condensation processes to separate and purify the mixture. In the distillation column, rising vapor and descending liquid undergo mass and heat transfer on the trays or packing. Volatile components (such as methanol) are enriched in the vapor phase, while less volatile components (such as water and other high-boiling-point impurities) are enriched in the liquid phase, thus achieving methanol purification.

[0003] In existing MTO-grade methanol distillation units, the evaporators are heated by steam. For example, in patent application number 201420664698.2, a flexible methanol distillation unit that can produce both MTO-grade and AA-grade methanol is provided. In this application, the first-effect evaporator 510 and the fourth-effect evaporator 540 are heated by steam. Steam heating increases the energy consumption of the entire system, thereby increasing the distillation cost. Therefore, a new technical solution is needed to solve the above-mentioned technical problems.

[0004] This application proposes to design an MTO-level methanol distillation unit that does not use steam. However, after a detailed search, no relevant technical solutions were found. Utility Model Content

[0005] This application provides a steam-free MTO-grade methanol distillation unit, including a synthesis reactor connected to a reaction gas feed line. The synthesis reactor is sequentially connected to a heat exchanger, a heat exchanger, a cooler, a separator, and an expansion tank. The output end of the heat exchanger is connected to an expansion flash tank, which is connected to the input end of a multi-stage evaporator. The output end of the multi-stage evaporator is connected to a reboiler, which is located at the bottom of a methanol stabilizer. The bottom of the methanol stabilizer is connected to the input end of the heat exchanger. A feed line is provided on one side of the methanol stabilizer, and a methanol product collection line is connected to the multi-stage evaporator.

[0006] As a preferred embodiment, the bottom of the expansion tank is connected to the input end of heat exchanger two, and the output end of heat exchanger two is connected to the feed pipeline.

[0007] As a preferred embodiment, the cooler comprises an air cooler and a water cooler connected in sequence.

[0008] As a preferred embodiment, a reaction gas heat exchanger is installed on the reaction gas feed pipeline, the bottom pipeline of the synthesis reactor is connected to another feed port of the reaction gas heat exchanger, and the other discharge port of the reaction gas heat exchanger is connected to the heat exchanger through the bottom pipeline of the reactor.

[0009] As a preferred embodiment, the multi-stage evaporator includes a primary evaporator and a secondary evaporator connected in sequence. The secondary evaporator is connected to a reboiler, and the output ends of both the primary and secondary evaporators are connected to methanol product collection pipelines.

[0010] As a preferred embodiment, the bottom of the methanol stabilizer is connected to the input end of heat exchanger one via a methanol stabilizer bottom pipeline, and bottom heat exchanger one and bottom heat exchanger two are installed on the methanol stabilizer bottom pipeline.

[0011] As a preferred embodiment, the methanol product collection pipeline of the first-stage evaporator passes through a first-stage bottom heat exchanger and / or the methanol product collection pipeline of the second-stage evaporator passes through a second-stage bottom heat exchanger.

[0012] As a preferred embodiment, the top of the methanol stabilization tower is connected to a reflux tank via a top pipeline, and a top condenser is installed on the top pipeline. The top of the reflux tank is connected to a non-condensable gas extraction pipeline, and the bottom of the reflux tank is connected to the methanol stabilization tower via a reflux pipeline, and a reflux pump is installed on the reflux pipeline.

[0013] This application uses heat exchanger one to provide a heat source for methanol in a multi-stage evaporator. Preferably, heat exchanger two is used to preheat the feed to the methanol stabilizer tower. This saves steam usage in the stabilizer tower and reduces the cooling medium in the cooler, further saving energy. Specifically, it reduces the cooling capacity of the air cooler, the number of air cooler cooling fans used, and / or the circulating water usage of the water cooler. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of this application;

[0015] 1. Synthesis reactor; 2. Reactor gas feed line; 3. Heat exchanger one; 4. Heat exchanger two; 5. Separator; 6. Expansion tank; 7. Air cooler; 8. Water cooler; 9. Circulating gas line; 10. Venting gas line; 11. Expansion flash tank; 12. Reboiler; 13. Methanol stabilizer; 14. Feed line; 15. Methanol product collection line; 16. Primary evaporator; 17. Secondary evaporator; 18. 19. Waste liquid pipeline; 20. Reactor gas heat exchanger; 21. Bottom pipeline of reactor; 22. Top pipeline; 23. Reflux tank; 24. Top condenser; 25. Non-condensable gas extraction pipeline; 26. Reflux pipeline; 27. Reflux pump; 28. Bottom pipeline of expansion tank; 29. ​​Output pipeline; 30. Methanol stabilizer tower bottom pipeline; 31. Tower bottom heat exchanger one; 32. Tower bottom heat exchanger two; 33. Methanol stabilizer tower bottom pump. Detailed Implementation

[0016] The following is in conjunction with the appendix Figure 1 The specific embodiments of this utility model will be described in detail below. It should be noted that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0017] Example 1:

[0018] This embodiment provides a steam-free MTO-grade methanol distillation unit, including a synthesis reactor 1 connected to a reaction gas feed line 2. The reaction gas enters the synthesis reactor 1 through the reaction gas feed line 2 for reaction. In the synthesis reactor 1, carbon monoxide, carbon dioxide, and hydrogen react chemically under the action of a catalyst to produce methanol. The synthesis reactor 1 is sequentially connected to heat exchanger 3, heat exchanger 4, cooler, separator 5, and expansion tank 6. More specifically, the cooler includes an air cooler 7 and a water cooler 8 connected in sequence. The methanol obtained in the synthesis reactor 1 is cooled sequentially by heat exchanger 3, heat exchanger 4, and cooler. The cooled methanol enters the separator 5. The gas phase generated in the separator 5 is discharged through the circulating gas line 9, and the liquid methanol enters the expansion tank 6 for further gas-liquid separation. The gas phase is discharged through the venting gas line 10, and the crude liquid methanol is stored in a tank area.

[0019] The output end of heat exchanger 3 is connected to expansion flash tank 11, expansion flash tank 11 is connected to the input end of multi-stage evaporator, the output end of multi-stage evaporator is connected to reboiler 12, reboiler 12 is located at the bottom of methanol stabilizer tower 13, the bottom of methanol stabilizer tower 13 is connected to the input end of heat exchanger 3, a feed line 14 is provided on one side of methanol stabilizer tower 13, the feed line 14 inputs material, and the multi-stage evaporator is connected to methanol product outlet line 15; specifically, the multi-stage evaporator includes a first-stage evaporator 16 and a second-stage evaporator 17 connected in sequence, the second-stage evaporator 17 is connected to reboiler 12, and the output ends of the first-stage evaporator 16 and the second-stage evaporator 17 are both connected to methanol product outlet line 15.

[0020] After heat exchange in heat exchanger 3, the crude methanol enters expansion flash tank 11, where some of the water is rapidly flashed into steam, achieving preliminary gas-liquid separation. The flashed steam contains a certain amount of heat and can be used as a heat source for the first-stage evaporator 16. The low-temperature liquid after flashing is discharged from the bottom of expansion flash tank 11 and enters the first-stage evaporator 16. The liquid entering the first-stage evaporator 16 is heated in the heating chamber. After the liquid is heated to its boiling point, secondary steam is generated. The secondary steam carries a large amount of heat and enters the separation chamber to separate from the remaining liquid. The methanol concentration in the steam is relatively high, while the methanol concentration in the remaining liquid is relatively low. Part of the steam enters the second-stage evaporator 17 as a heating element. The concentrated liquid also enters the secondary evaporator 17 for further evaporation and concentration. Part of it is collected as methanol product and can be stored in a storage tank. In the secondary evaporator 17, the steam from the first-effect evaporator continues to heat the liquid, causing it to evaporate further. Similarly, the generated steam and the remaining liquid are separated in the separation chamber. Part of the steam is used as a heat source for the reboiler 12 to provide the heat required for the distillation of the methanol stabilizer 13. Part of the steam is collected as product to obtain methanol product, which can be stored in a storage tank. The remaining liquid has a very low methanol content and becomes residual liquid, which is discharged from the waste liquid line 18 of the secondary evaporator 17.

[0021] Preferably, in order to utilize the heat at the bottom of the synthesis reactor 1 and further reduce energy consumption, a reaction gas heat exchanger 19 is installed on the reaction gas feed line 2. The bottom pipeline 20 of the synthesis reactor 1 is connected to another inlet of the reaction gas heat exchanger 19, and the other outlet of the reaction gas heat exchanger 19 is connected to heat exchanger 3 through the bottom pipeline 20. After the liquid phase collected from the bottom of the synthesis reactor 1 exchanges heat with the reaction gas heat exchanger 19, the temperature drops to 110℃-130℃, and the heat from the bottom of the synthesis reactor 1 is used to preheat the reaction gas.

[0022] Preferably, in order to improve the distillation accuracy of methanol, the top of the methanol stabilization tower 13 is refluxed. The top of the methanol stabilization tower 13 is connected to the reflux tank 22 through a top pipeline 21. A top condenser 23 is installed on the top pipeline 21. A non-condensable gas collection pipeline 24 is connected to the top of the reflux tank 22. The bottom of the reflux tank 22 is connected to the methanol stabilization tower 13 through a reflux pipeline 25. A reflux pump 26 is installed on the reflux pipeline 25.

[0023] Example 2:

[0024] In this embodiment, the crude methanol collected from expansion tank 6 directly enters methanol stabilization tower 13, and the crude methanol is heated using the heat from heat exchanger 4. Specifically:

[0025] The bottom of the expansion tank 6 is connected to the input end of the heat exchanger 4 via the bottom pipeline 27 of the expansion tank. The output end of the heat exchanger 4 is connected to the feed pipeline 14 via the output pipeline 28. That is, after the crude methanol in liquid phase exchanges heat with the heat exchanger 4, the temperature of the crude methanol is raised from 40 degrees Celsius to 60 degrees Celsius and then enters the methanol stabilization tower 13 through the feed pipeline 14.

[0026] Example 3:

[0027] This embodiment utilizes the heat from the methanol product, specifically:

[0028] The bottom of the methanol stabilizer 13 is connected to the input end of heat exchanger 3-1 via methanol stabilizer bottom pipeline 29. The methanol stabilizer bottom pipeline 29 is equipped with bottom heat exchanger 30-1, bottom heat exchanger 31-2, and methanol stabilizer bottom pump 32. The methanol product outlet pipeline 15 of the first-stage evaporator 16 passes through bottom heat exchanger 30-1, and / or the methanol product outlet pipeline 15 of the second-stage evaporator 17 passes through bottom heat exchanger 31-2. That is, the methanol product outlet pipeline 15 of the first-stage evaporator 16 is connected to one input end of bottom heat exchanger 30-1, and one output end of bottom heat exchanger 30-1 is connected to methanol product outlet pipeline 15. The second-stage evaporator 17 is similarly connected, and will not be described in detail here.

[0029] The first and second heat exchangers 30 and 31 absorb the heat from the methanol product, cooling it down and providing heat for the first heat exchanger 3. The methanol exiting the bottom of the methanol stabilizer 13 is at a temperature of 75°C. After passing through the first and second heat exchangers 30 and 31, the temperature rises to about 80°C and enters the first heat exchanger 3. The first heat exchanger 3 raises the temperature to 120°C and then the methanol enters the expansion flash tank 11 for subsequent reactions.

[0030] The existing MTO-level methanol stabilizer tower requires a steam consumption of 0.25 tons per ton of refined methanol. This application uses heat exchanger 3 to provide a heat source for the methanol in the multi-stage evaporator. Preferably, the feed to the methanol stabilizer tower 13 is preheated through heat exchanger 4. This saves steam usage in the methanol stabilizer tower 13 and reduces the cooling medium in the cooler, further saving energy. Specifically, it reduces the cooling capacity of the air cooler 7, reduces the number of cooling fans used in the air cooler 7, and / or reduces the circulating water usage of the water cooler 8.

[0031] The preferred embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

[0032] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the various possible combinations in this application will not be described separately.

[0033] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, and such combinations should also be regarded as the content disclosed in this application.

Claims

1. A MTO grade methanol rectification device without using steam, comprising a synthesis reactor (1), a reaction gas feeding line (2) is connected to the synthesis reactor (1), characterized in that, The synthesis reactor (1) is connected in sequence to heat exchanger one (3), heat exchanger two (4), cooler, separator (5), and expansion tank (6). The output end of heat exchanger one (3) is connected to expansion flash tank (11), expansion flash tank (11) is connected to the input end of multi-stage evaporator, and the output end of multi-stage evaporator is connected to reboiler (12). Reboiler (12) is located at the bottom of methanol stabilizer tower (13). The bottom of methanol stabilizer tower (13) is connected to the input end of heat exchanger one (3). A feed pipeline (14) is provided on one side of methanol stabilizer tower (13), and methanol product collection pipeline (15) is connected to multi-stage evaporator.

2. A MTO grade methanol rectification device without using steam according to claim 1, characterized in that, The bottom of the expansion tank (6) is connected to the input end of the heat exchanger (4), and the output end of the heat exchanger (4) is connected to the feed line (14).

3. The MTO grade methanol rectification device without using steam according to claim 1, characterized in that, The cooler includes an air cooler (7) and a water cooler (8) connected in sequence.

4. The MTO-stage methanol distillation unit without steam as described in claim 1, characterized in that, A reaction gas heat exchanger (19) is installed on the reaction gas feed line (2). The bottom pipeline (20) of the synthesis reactor (1) is connected to another feed port of the reaction gas heat exchanger (19). The other outlet of the reaction gas heat exchanger (19) is connected to heat exchanger one (3) through the bottom pipeline (20).

5. The MTO grade methanol rectification device without using steam according to claim 1, characterized in that, The multi-stage evaporator includes a primary evaporator (16) and a secondary evaporator (17) connected in sequence. The secondary evaporator (17) is connected to a reboiler (12). The output ends of the primary evaporator (16) and the secondary evaporator (17) are both connected to methanol product collection pipelines (15).

6. A MTO grade methanol rectification device without using steam according to claim 5, characterized in that, The bottom of the methanol stabilizer (13) is connected to the input end of heat exchanger one (3) via the methanol stabilizer bottom pipeline (29). The methanol stabilizer bottom pipeline (29) is equipped with bottom heat exchanger one (30) and bottom heat exchanger two (31).

7. A MTO grade methanol rectification device without using steam according to claim 6, characterized in that, The methanol product outflow line (15) of the first-stage evaporator (16) passes through the first bottom heat exchanger (30) or / and the methanol product outflow line (15) of the second-stage evaporator (17) passes through the second bottom heat exchanger (31).

8. The MTO grade methanol rectification device without using steam according to claim 1, characterized in that, The top of the methanol stabilizer tower (13) is connected to the reflux tank (22) via a top pipeline (21). A top condenser (23) is installed on the top pipeline (21). A non-condensable gas extraction pipeline (24) is connected to the top of the reflux tank (22). The bottom of the reflux tank (22) is connected to the methanol stabilizer tower (13) via a reflux pipeline (25). A reflux pump (26) is installed on the reflux pipeline (25).

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