Separation system for preparing propylene from methanol

Abstract

The invention provides a separation system for preparing propylene from methanol, belongs to the technical field of preparing propylene from methanol, and solves the problems of large occupied area, high investment cost, unobvious separation effect, low byproduct utilization rate, low product yield, high energy consumption and high production cost of the existing separation system. The device comprises a gas-phase hydrocarbon input pipe and a liquid-phase hydrocarbon input pipe, the gas-phase hydrocarbon input pipe is connected with a depropanizer, the depropanizer is connected with a deethanizer, the deethanizer is connected with a propylene rectifying tower, the propylene rectifying tower is connected with a propylene output pipe, the liquid-phase hydrocarbon input pipe is connected with a debutanizer, and the top of the debutanizer is communicated with the gas-phase hydrocarbon input pipe. Gas-phase hydrocarbons sequentially enter the depropanizer, the deethanizer and the propylene rectifying tower, liquid-phase hydrocarbons sequentially enter the debutanizer, the depropanizer, the deethanizer and the propylene rectifying tower, a demethanizer and an ethylene rectifying tower in the prior art are omitted, operation conditions are relatively simple, the occupied area is small, the investment cost is low, energy consumption is obviously reduced, and the production cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of methanol - to - propylene, and particularly relates to a separation system for methanol - to - propylene. Background Art

[0002] Ethylene and propylene are two of the most produced chemical products in the world. The consumption of propylene is second only to that of ethylene, and it is widely used in the production of polypropylene, acrylonitrile, propylene oxide, cumene, isopropyl alcohol, carbonyl alcohol and other chemicals.

[0003] Currently, the production of propylene by cracking accounts for about 45% of the total global propylene production capacity, propylene from refineries accounts for about 25% of the total propylene production capacity, propane dehydrogenation accounts for about 18% of the total propylene production capacity, methanol - to - olefins accounts for about 10% of the total propylene production capacity, and other processes for propylene production account for about 2% of the total propylene production capacity. In China, the traditional naphtha cracking route for propylene production currently accounts for about 10%, the catalytic cracking route accounts for about 30%, the propane dehydrogenation route accounts for about 35%, and methanol - to - olefins accounts for about 25%.

[0004] Due to the increasingly scarce petroleum resources in China, there is an urgent need to develop a large number of non - petroleum - based propylene preparation process routes. The production of methanol from coal / natural gas has entered large - scale production. Methanol - to - olefins (MTO / MTP) has the advantages of wide raw material sources and low costs, and is suitable for China's national conditions of rich coal and poor oil.

[0005] In the methanol - to - propylene (MTP) process, under the action of a catalyst, methanol undergoes a dehydration reaction to produce dimethyl ether. The mixture of dimethyl ether and unreacted methanol then undergoes another dehydration reaction to produce a mixed product gas containing various hydrocarbons. The separation process of the mixed product gas is to separate out the polymer - grade propylene product and by - products at the same time. The separation of the MTP reaction product gas is necessary, so the separation effect is the most important. A reasonable separation system can improve the efficiency of the MTP process design and is also an important part of the MTP technology.

[0006] The separation systems adopted by currently operating methanol - to - propylene plants have large floor areas, high investment costs, unclear separation effects, low utilization rates of by - products, low product yields, high energy consumption, and high production costs, which are not conducive to improving market competitiveness. Summary of the Invention

[0007] In view of the above problems, the purpose of the present invention is to provide a separation system for methanol - to - propylene. The gaseous hydrocarbons enter the de - propane tower, de - ethane tower, and propylene rectification tower in sequence, and the liquid hydrocarbons enter the de - butane tower, de - propane tower, de - ethane tower, and propylene rectification tower in sequence. The de - methane tower and ethylene rectification tower in the original technology are cancelled. The operating conditions are relatively simple, the floor area is small, the investment cost is low, the energy consumption is significantly reduced, and the production cost is low.

[0008] The technical solution adopted by the present invention is as follows:

[0009] A separation system for methanol to propylene, comprising a gas-phase hydrocarbon input pipe and a liquid-phase hydrocarbon input pipe. The gas-phase hydrocarbon input pipe is connected to a depropanizer. The top of the depropanizer is connected to a deethanizer through a pipeline. The bottom of the deethanizer is connected to a propylene rectification column through a pipeline. The top of the propylene rectification column is connected to a propylene output pipe. The liquid-phase hydrocarbon input pipe is connected to a debutanizer. The top of the debutanizer is communicated with the gas-phase hydrocarbon input pipe through a pipeline.

[0010] Preferably, the bottom of the debutanizer is connected to a dehexanizer through a pipeline. The top of the dehexanizer is provided with a C5 / C6 component output pipe, and the bottom of the dehexanizer is provided with a gasoline output pipe.

[0011] Preferably, the bottom of the depropanizer is connected to a C4 component output pipe.

[0012] Preferably, the top of the deethanizer is connected to a C2 component output pipe.

[0013] Preferably, the C5 / C6 component output pipe, the C4 component output pipe, and the C2 component output pipe are connected to a feed main pipe.

[0014] Preferably, a feed nozzle connected to the C4 component output pipe is provided on the feed main pipe, and the feed nozzle is connected to a steam input pipe.

[0015] Preferably, the bottom of the propylene rectification column is connected to an LPG output pipe.

[0016] Preferably, a compressor I is provided on the pipeline at the top of the debutanizer, and a compressor II is provided on the pipeline at the top of the depropanizer.

[0017] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0018] The gas-phase hydrocarbons enter the depropanizer, the deethanizer, and the propylene rectification column in sequence, and the liquid-phase hydrocarbons enter the debutanizer, the depropanizer, the deethanizer, and the propylene rectification column in sequence. The demethanizer and the ethylene rectification column in the original technology are cancelled. The operating conditions are relatively simple, the floor area is small, the investment cost is low, the energy consumption is significantly reduced, and the production cost is low. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required 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, other related drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1A schematic flowchart provided by an embodiment of the present invention.

[0021] Reference numerals: 1 - debutanizer; 2 - dehexanizer; 3 - depropanizer; 4 - deethanizer; 5 - propylene rectification column; 101 - gas-phase hydrocarbon input pipe; 102 - liquid-phase hydrocarbon input pipe; 103 - C5 / C6 component output pipe; 104 - gasoline output pipe; 105 - C4 component output pipe; 106 - C2 component output pipe; 107 - propylene output pipe; 108 - LPG output pipe; 201 - compressor 1; 202 - compressor 2; 203 - feed main pipe; 204 - feed nozzle; 205 - steam input pipe. Detailed implementation manners

[0022] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention usually described and illustrated in the accompanying 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 accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within 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. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this application is usually placed during use, it 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, and therefore cannot be construed as a limitation of the present invention.

[0025] The following will be combined with Figure 1 to describe the present invention in detail.

[0026] Embodiment

[0027] A separation system for producing propylene from methanol, comprising a gas-phase hydrocarbon input pipe 101 and a liquid-phase hydrocarbon input pipe 102. The gas-phase hydrocarbon input pipe 101 is connected to a depropanizer 3. The top of the depropanizer 3 is connected to a deethanizer 4 through a pipeline. The bottom of the deethanizer 4 is connected to a propylene rectification column 5 through a pipeline. The top of the propylene rectification column 5 is connected to a propylene output pipe 107. The liquid-phase hydrocarbon input pipe 102 is connected to a debutanizer 1. The top of the debutanizer 1 is communicated with the gas-phase hydrocarbon input pipe 101 through a pipeline.

[0028] The gas-phase hydrocarbons output from the gas-phase hydrocarbon input pipe 101 sequentially enter the depropanizer 3, the deethanizer 4, and the propylene rectification column 5. The liquid-phase hydrocarbons output from the liquid-phase hydrocarbon input pipe 102 sequentially enter the debutanizer 1, the depropanizer 3, the deethanizer 4, and the propylene rectification column 5. Finally, propylene is separated. The propylene output pipe 107 transports the propylene to other processes. In this application, the demethanizer and the ethylene rectification column in the original technology are cancelled. The operating conditions are relatively simple, the floor area is small, the investment cost is low, the energy consumption is significantly reduced, and the production cost is low.

[0029] The bottom of the debutanizer 1 is connected to a dehexanizer 2 through a pipeline. The top of the dehexanizer 2 is provided with a C5 / C6 component output pipe 103. The bottom of the dehexanizer 2 is provided with a gasoline output pipe 104. The C5 / C6 component by-product is separated from the top of the dehexanizer 2, and the gasoline by-product is separated from the bottom of the dehexanizer 2, producing high-value-added gasoline by-products and increasing economic benefits.

[0030] The bottom of the depropanizer 3 is connected to a C4 component output pipe 105. The C4 component output pipe 105 can discharge the C4 components in the depropanizer 3. The top of the deethanizer 4 is connected to a C2 component output pipe 106. The C2 component output pipe 106 can discharge the C2 components in the deethanizer 4.

[0031] The C5 / C6 component output pipe 103, the C4 component output pipe 105, and the C2 component output pipe 106 are connected to a feed main pipe 203. The C5 / C6 components, C4 components, and C2 components can enter the methanol-to-propylene reactor through the feed main pipe 203 for reaction again. Specifically: C5 and C4 undergo a disproportionation reaction in the methanol-to-propylene reactor to generate C2, and C2 and C6 undergo a disproportionation reaction in the methanol-to-propylene reactor to generate propylene. The by-products are used to improve the propylene yield, the utilization rate of the by-products is high, and the product yield is high.

[0032] A feed nozzle 204 connected to the C4 component output pipe 105 is provided on the main feed pipe 203, and the feed nozzle 204 is connected to a steam input pipe 205. The C4 component by-product is in a liquid phase. After the feed nozzle 204 is provided, gas-liquid resonance is prevented from damaging the pipeline. 2 to 8 groups of feed nozzles 204 are symmetrically and evenly arranged to prevent C4 from flowing unevenly or breaking through the pipeline, protect the feed pipeline. The steam output from the steam input pipe 205 connected to the feed nozzle 204 can atomize the C4 liquid-phase feed, making the C4 enter the main feed pipe 203 more evenly and stably, without generating gas-liquid resonance, protecting the equipment and extending the service life of the equipment. The C4 component by-product enters the reactor through the main feed pipe 203 for reaction. C4 and C2 undergo a disproportionation reaction in the methanol-to-propylene reactor to generate propylene, and at the same time, C4 and C5 undergo a disproportionation reaction in the methanol-to-propylene reactor to generate C2, using the by-product to improve the propylene yield, with high by-product utilization and high product yield.

[0033] The bottom of the propylene distillation column 5 is connected to an LPG liquefied gas output pipe 108. While separating propylene at the top, the propylene distillation column 5 separates high-value LPG (liquefied petroleum gas) liquefied gas by-products from the bottom, increasing economic benefits.

[0034] A compressor 201 is provided on the pipeline at the top of the debutanizer 1, and a compressor 202 is provided on the pipeline at the top of the depropanizer 3. The two compressors increase the pressure of the pipeline, and at the same time ensure that the heavy components fed into the depropanizer 3 and the deethanizer 4 enter in a partially liquid phase state, improving the separation effect, and the separation effect is obvious.

[0035] The separation method of the methanol-to-propylene separation system of this application:

[0036] The gaseous hydrocarbons are separated by the depropanizer 3. The C3 and light components separated from the top of the tower enter the deethanizer 4 for separation after being compressed by the compressor 202. The C4 component by-product separated from the bottom of the depropanizer 3 enters the reactor through the feed nozzle 204 to the main feed pipe 203 to participate in the reaction again; the C3 and light components are separated by the deethanizer 4. The C2 component by-product separated from the top of the deethanizer 4 enters the reactor through the main feed pipe 203 to participate in the reaction again. The C3 component separated from the bottom of the deethanizer 4 is separated by the propylene distillation column 5. Propylene products are separated from the top of the propylene distillation column 5, and LPG liquefied gas by-products are separated from the bottom of the propylene distillation column 5;

[0037] The liquid hydrocarbons are separated by the debutanizer 1. The C4 and light components separated from the top of the tower enter the depropanizer 3 for separation after being compressed by the compressor 201. The heavy components separated from the bottom of the debutanizer 1 are separated by the dehexanizer 2. The C5 / C6 component by-product separated from the top of the dehexanizer 2 enters the reactor through the main feed pipe 203 to participate in the reaction again, and gasoline by-products are separated from the bottom of the dehexanizer 2.

[0038] 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 may have various modifications and changes. 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 separation system for methanol to propylene, characterized in that, It includes a gaseous hydrocarbon input pipe (101) and a liquid hydrocarbon input pipe (102). The gaseous hydrocarbon input pipe (101) is connected to a depropanizer tower (3). The top of the depropanizer tower (3) is connected to a deethanizer tower (4) through a pipeline. The bottom of the deethanizer tower (4) is connected to a propylene rectification tower (5) through a pipeline. The top of the propylene rectification tower (5) is connected to a propylene output pipe (107). The liquid hydrocarbon input pipe (102) is connected to a debutanizer tower (1). The top of the debutanizer tower (1) is communicated with the gaseous hydrocarbon input pipe (101) through a pipeline.

2. The separation system for methanol to propylene according to claim 1, wherein, The bottom of the debutanizer tower (1) is connected to a dehexanizer tower (2) through a pipeline. A C5 / C6 component output pipe (103) is arranged at the top of the dehexanizer tower (2). A gasoline output pipe (104) is arranged at the bottom of the dehexanizer tower (2).

3. The separation system for methanol to propylene according to claim 2, wherein The bottom of the depropanizer tower (3) is connected to a C4 component output pipe (105).

4. A separation system for methanol to propylene according to claim 3, characterized in that, The top of the deethanizer tower (4) is connected to a C2 component output pipe (106).

5. The separation system for methanol to propylene according to claim 4, characterized in that, The C5 / C6 component output pipe (103), the C4 component output pipe (105), and the C2 component output pipe (106) are connected to a feed main pipe (203).

6. The separation system for methanol to propylene according to claim 5, characterized in that, A feed nozzle (204) connected to the C4 component output pipe (105) is arranged on the feed main pipe (203). The feed nozzle (204) is connected to a steam input pipe (205).

7. A separation system for methanol to propylene according to claim 1, characterized in that, The bottom of the propylene rectification tower (5) is connected to an LPG output pipe (108).

8. A separation system for methanol to propylene according to claim 1, characterized in that, A compressor one (201) is arranged on the pipeline at the top of the debutanizer tower (1). A compressor two (202) is arranged on the pipeline at the top of the depropanizer tower (3).

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