JP2015189717A - Propylene production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an industrially advantageous propylene production method which allows reduction of energy consumption of a purification system while keeping a propylene yield.SOLUTION: A propylene production method comprises cooling a reaction product obtained by reacting an olefin with methanol and/or dimethyl ether, supplying the reaction product to two or more multi-stage compression units to obtain propylene from ingredients produced by compression in the last-stage compression unit. Liquid ingredients produced by compression in the front-stage compression units are supplied to a distillation unit, and gas ingredients discharged from the distillation unit are supplied to the subsequent-stage compression units.

Description

  The present invention relates to a method for producing propylene from a raw material gas containing olefin and methanol and / or dimethyl ether. More specifically, the raw material gas is subjected to a carbon increase reaction and / or cracking reaction in the presence of a catalyst, with propylene as a main component. The present invention relates to a method for producing propylene, which obtains a product gas containing it.

  Propylene production methods include naphtha and ethane cracking, fluid catalytic cracking of vacuum gas oil, and other effective methods for selective production of propylene by reacting olefin with methanol and / or dimethyl ether. There is a method of manufacturing. In this method, in order to suppress the deterioration of the catalyst and increase the utilization efficiency of the raw material, at least a part of the aromatic compound contained in the gas flowing out from the reactor outlet (reactor outlet gas) is removed, and the fragrance is removed. A process is disclosed in which at least a part of olefins having 4 or more carbon atoms contained in a reactor outlet gas with reduced group compounds is recycled to the reactor (Patent Document 1).

  In one embodiment of the method described in Patent Document 1, after the water at the reactor outlet is condensed and removed by cooling and compression, a distillation column (hereinafter, this distillation column may be referred to as “de-C2 column”). And a stream rich in hydrocarbons having 2 or less carbon atoms and a stream rich in hydrocarbons having 3 or more carbon atoms and separating the stream rich in hydrocarbons having 3 or more carbon atoms into a distillation column (hereinafter referred to as this distillation column). It is sometimes referred to as “de-C3 tower.”) Separated into a stream rich in hydrocarbons having 3 carbon atoms and a stream rich in hydrocarbons having 4 or more carbon atoms, and rich in hydrocarbons having 4 or more carbon atoms Further, the stream is a distillation column (hereinafter, this distillation column may be referred to as “de-C6 column”), a stream rich in hydrocarbons having 4 to 6 carbon atoms and a stream rich in hydrocarbons having 7 or more carbon atoms. And recycle at least part of the hydrocarbon-rich stream with 4 to 6 carbon atoms into the reactor That.

JP 2008-100994 A

  If it is the method of patent document 1, while suppressing the deterioration of a catalyst, the yield of propylene can be raised, but the production cost is reduced by reducing the energy consumption in the separation and purification process of the reaction product. Is desired.

  An object of the present invention is to provide an industrially advantageous method for producing propylene which reduces the energy consumption of the purification system while maintaining the propylene yield.

  As a result of intensive studies to solve the above problems, the present inventors cooled the reactor outlet gas (reaction product) obtained by supplying olefin and methanol and / or dimethyl ether to the reactor filled with the catalyst. After that, it compresses sequentially with the compression device provided in multiple stages, the liquid component generated by the compression with the compression apparatus of the previous stage is separated by distillation with a distillation apparatus (stripper), and the separated gas component is supplied to the compression apparatus of the subsequent stage. As a result, it is possible to reduce the size and load of the de-C2 tower and the de-C3 tower, and to eliminate the need for the de-C6 tower. As a result, while maintaining the propylene yield, the energy consumed for the purification system can be reduced. The present inventors have found that it can be significantly reduced and have reached the present invention.

  That is, the gist of the present invention resides in the following [1] to [4].

[1] After cooling a reaction product obtained by reacting an olefin with methanol and / or dimethyl ether, the gas components generated by the compression in the preceding compression apparatus are transferred to two or more compression apparatuses provided in multiple stages. In the method for producing propylene, the propylene is obtained sequentially from the components produced by the compression in the final stage compression apparatus, as if it is supplied to the stage compression apparatus.
At least a liquid component generated by the compression in the first stage compression apparatus is supplied to the distillation apparatus, and a gas component discharged from the distillation apparatus is supplied to the distillation apparatus as a liquid component generated by the compression. A method for producing propylene, which is supplied to a later-stage compression apparatus.

[2] The method for producing propylene according to [1], wherein the olefin is reacted with methanol and / or dimethyl ether in the presence of an aluminosilicate catalyst.

[3] The method for producing propylene according to [1] or [2], wherein the liquid component fed to the distillation apparatus contains 10 mol% or more of an olefin having 4 or more carbon atoms.

[4] The compression device is provided in three stages, and the liquid component generated by the compression in the first-stage compression device and the second-stage compression device is supplied to the distillation device, and from the distillation device, The method for producing propylene according to any one of [1] to [3], wherein the discharged gas component is fed to a last-stage compression device.

  According to the method for producing propylene of the present invention, in the method for producing propylene by reacting an olefin with methanol and / or dimethyl ether, the energy consumed for the purification system can be reduced while maintaining the propylene yield. .

It is a systematic diagram which shows an example of embodiment of the manufacturing method of the propylene of this invention. 2 is a system diagram showing a method for producing propylene of Reference Example 1. FIG.

  Although the form for implementing this invention is demonstrated in detail as follows, the description described below is an example (representative example) of the embodiment of this invention, and if this invention does not exceed the summary, It is not limited to the following aspects.

  In the method for producing propylene of the present invention, after cooling a reaction product obtained by reacting an olefin with methanol and / or dimethyl ether, two or more compression devices provided in multiple stages are subjected to compression in the compression device in the previous stage. In the method for producing propylene, in which the generated gas components are sequentially supplied so as to be supplied to the next-stage compression device, and propylene is obtained from the components generated by the compression in the last-stage compression device, at least in the first-stage compression device The liquid component generated by the compression is supplied to the distillation apparatus, and the gas component discharged from the distillation apparatus is supplied to the compression apparatus downstream from the compression apparatus in which the liquid component generated by the compression is fed to the distillation apparatus. It is characterized by.

  More specifically, the present invention includes an embodiment including each step described below. However, as long as the purpose of solving the problems of the present invention is followed, the present invention excludes the presence of steps other than the steps described below. It is not a thing, and other processes may exist between each process mentioned below.

  In the present invention, “rich” means that the content of the main component is 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more, and still more preferably 95 mol% or more. Means. For example, “a stream rich in hydrocarbons having 4 or more carbon atoms” means “hydrocarbons having 4 or more carbon atoms” in an amount of 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more. Is a stream containing 95 mol% or more.

[catalyst]
First, the catalyst used in the present invention will be described.
As the catalyst used in the reaction according to the present invention, a catalyst capable of producing propylene from one or both of methanol and dimethyl ether and an olefin, preferably an olefin having 4 to 6 carbon atoms is used. A catalyst may use only 1 type or may use 2 or more types.

  Examples of such a catalyst include a solid catalyst having a Bronsted acid point (solid acid catalyst). For example, clay minerals such as kaolin; impregnation and support of acid such as sulfuric acid and phosphoric acid on a carrier such as clay mineral Examples of the catalyst include: an acidic ion exchange resin; zeolites; aluminum phosphates; and mesoporous silica alumina such as Al-MCM41.

  The solid acid catalyst preferably has a molecular sieving effect, and the acid strength is preferably not so high.

  Examples of the solid acid catalyst having a molecular sieving effect include AEI, AET, AEL, AFI, AFO, AFS, AST, ATN, BEA, CAN, CHA, EMT, ERI, and EUO in the code defined by International Zeolite Association (IZA). , FAU, FER, LEV, LTL, MAZ, MEL, MFI, MOR, MTT, MTW, MWW, OFF, zeolites having structures such as PAU, RHO, STT, TON, and aluminum phosphates.

Among them, a catalyst having a catalyst framework density of 18.0 T / nm ³ or less is preferable, and as such, preferably MFI, MEL, MOR, MWW, FAU, BEA, CHA, more preferably MFI. , MEL, MOR, MWW, CHA, particularly preferably MFI, MEL, MWW, CHA. Here, the framework density (unit: T / nm ³ ) is the number of T atoms (atoms other than oxygen among the atoms constituting the skeleton of the zeolite) present per unit volume (1 nm ³ ) of the zeolite. This means that this value can be determined by the structure of the zeolite.

The catalyst used in the present invention has micropores having a pore diameter of 0.3 to 0.9 nm, a BET specific surface area of 200 to 700 m ² / g, and a pore volume of 0.1 to 0.5 cc / g. Some crystalline aluminosilicates, metallosilicates, or crystalline aluminum phosphates are preferred. The pore diameter referred to here means a crystallographic free diameter of the channels defined by International Zeolite Association (IZA), and when the shape of the pore (channel) is a perfect circle, This means the diameter, and when the pore shape is elliptical, it means the minor axis.

Further, in the _{aluminosilicate,} it is preferable from the viewpoint of durability of the catalyst the molar ratio of SiO 2 / _Al 2 _{O 3} is 10 or more. The upper limit of the molar ratio of SiO ₂ / Al ₂ O ₃ is usually 10,000 from the viewpoint of obtaining sufficient activity in the catalyst. The molar ratio can be determined by a conventional method such as fluorescent X-ray or chemical analysis. The aluminum content in the catalyst can be controlled by the amount of raw material charged during catalyst preparation, and aluminum can be reduced by steaming after the preparation. Further, a part of aluminum may be replaced with other elements such as boron and gallium, and it is particularly preferable to substitute with boron.

  The particle size of the catalyst varies depending on the conditions of the propylene production reaction, but is usually 0.01 to 500 μm as an average particle size from the viewpoint of ensuring a sufficient surface area showing the activity of the catalyst and handling properties of the catalyst. The average particle diameter of the catalyst can be determined by observation with an SEM.

  The catalyst can be prepared by a known method generally called hydrothermal synthesis, and the composition can be changed by modification such as ion exchange, dealumination treatment, impregnation or loading after hydrothermal synthesis.

Examples of the solid acid catalyst suitable for the present invention include a catalyst obtained by calcining a mixture of MFI type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 100 or more and alumina.

  The method for producing propylene of the present invention is preferably carried out by venting the reaction raw material in a gaseous state to a reactor in which a fixed bed filled with such a catalyst is formed. Here, the fixed bed of the catalyst may contain components other than the catalyst. Examples of such components include inert particles. As the inert particle, a granulated product made of a substance inert to the reaction or a binder can be used. Examples of the substance inert to the reaction and the binder include alumina or alumina sol, silica, silica gel, quartz, and a mixture thereof.

  In the fixed bed of the catalyst, the catalyst concentration of the fixed bed of the entire reactor may be the same, or the catalyst concentration may be different for each fixed bed or each fixed bed group. Further, the catalyst concentration in the aeration direction of the fixed bed may be constant, may be different in stages, or may be inclined. The catalyst concentration in the fixed bed can be adjusted by the mixing ratio of the inert particles and the catalyst, and can be determined by experiments using a laboratory machine or calculations by computer simulation.

[Reaction raw materials]
The olefin, methanol, and dimethyl ether used as reaction raw materials in the present invention will be described.

<Olefin raw material>
As the olefin, an olefin having 4 or more carbon atoms is preferable, and an olefin having 4 to 10 carbon atoms is more preferable.

  The origin of production of such olefin raw materials is not particularly limited, for example, those produced from petroleum feedstocks by catalytic cracking or steam cracking (BB fraction, C4 raffinate-1, C4 raffinate-2, etc.), coal Obtained by performing FT (Fischer-Tropsch) synthesis using a hydrogen / CO mixed gas obtained by gasification of the above, obtained by oligomerization reaction including ethylene dimerization reaction, paraffin having 4 or more carbon atoms Various known types such as those obtained by dehydrogenation or oxidative dehydrogenation, obtained by MTO reaction, obtained by dehydration of alcohol, obtained by hydrogenation of a diene compound having 4 or more carbon atoms, etc. Can be obtained by any method, and any mixture of olefins resulting from each process Ku, may be obtained by purification.

  The olefin raw material may contain, for example, paraffins such as normal butane and / or isobutane. As such olefin, for example, BB fraction, C4 raffinate-1 and C4 raffinate-2 are preferable.

<Methanol, dimethyl ether>
The origin of production of methanol and / or dimethyl ether is not particularly limited. For example, coal and natural gas, and those obtained by hydrogenation reaction of a by-product-derived hydrogen / CO mixed gas in the steel industry, plant-derived alcohols Those obtained by a reforming reaction, those obtained by a fermentation method, those obtained from organic substances such as recycled plastics and municipal waste, and the like. Moreover, what is manufactured with the MTD reaction apparatus mentioned later may be used. At this time, a state in which compounds other than methanol and dimethyl ether resulting from each production method are arbitrarily mixed may be used as it is, or a purified one may be used.

[Propylene production process]
One embodiment of the process employed in the method for producing propylene of the present invention will be described with reference to FIG. FIG. 1: shows the systematic diagram which concerns on an example of embodiment of the manufacturing method of the propylene of this invention, and each process in FIG. 1 is as follows.

<Reaction process>
The raw material (1) containing methanol usually forms a stream (3) containing methanol and / or dimethyl ether via an MTD reactor (2) in which 80% or more of methanol is converted to dimethyl ether, and the stream (3) And a stream (5) in which a stream rich in hydrocarbons having 2 or less carbon atoms (35) and a stream rich in hydrocarbons having 4 to 6 carbon atoms (45), which are components recycled in the system, are joined together. , Enters the reactor (6) filled with the catalyst, and contains, as reaction products (reactor effluent, reactor outlet gas), product propylene, unreacted raw materials, by-products and diluent Stream (7) is obtained.

  At this time, the raw material (4) containing olefin is additionally supplied from the outside to the stream (45) rich in hydrocarbon having 4 to 6 carbon atoms, forming a stream (49) and joining the stream ( 5). Examples of the olefin-containing raw material (4) include C4 fraction and C5 fraction produced by a steam cracker, C4 fraction and C5 fraction produced by FCC (fluid catalytic cracking), or a mixture thereof. However, there is no particular limitation as long as it is a hydrocarbon compound containing an olefin.

  The reaction of the present invention is a gas phase reaction, and the form of the reactor (6) is not particularly limited. Usually, a continuous fixed bed reactor or a fluidized bed reactor is used, and preferably a fixed bed reactor. It is.

At this time, the propylene concentration in the mixed stream (7) is usually 5 to 95% by weight.
The unreacted raw material contained in the mixed stream (7) is usually an olefin having 4 or more carbon atoms. Depending on the reaction conditions, the mixed stream (7) contains methanol and / or dimethyl ether, but it is preferable to carry out the reaction under such reaction conditions that methanol and / or dimethyl ether does not remain. Thereby, separation of the reaction product and the unreacted raw material becomes easy.

  The reaction temperature is the temperature of the raw material gas at the inlet of the reactor (6), usually from 300 to 700 ° C., from the viewpoint of preventing the generation of unreacted raw materials and suppressing the decrease in the yield of propylene. Is preferable, and it is more preferable that it is 400-600 degreeC.

  The reaction pressure is usually 2 MPa (absolute pressure) or less, and is 1 kPa to 1 MPa (absolute pressure) from the viewpoint of suppressing the production of by-products and suppressing the decrease in the reaction rate of the propylene production reaction. The pressure is preferably 50 kPa to 0.7 MPa (absolute pressure).

The space velocity is 0.1 to 500 hr from the viewpoint of suppressing reduction in the conversion rate of the raw material, from the viewpoint of obtaining a sufficient propylene selectivity, from the viewpoint of suppressing the amount of catalyst used, and from the viewpoint of suppressing the formation of by-products. ⁻¹ is preferable, and 1.0 to 100 hr ⁻¹ is more preferable. The space velocity is a flow rate (weight / hour) obtained by adding the flow rates of olefins having 4 to 6 carbon atoms in the raw material gas per weight of the catalyst and the flow rates of methanol and dimethyl ether.

In the reactor (6), in addition to olefin having 4 or more carbon atoms and methanol and / or dimethyl ether, paraffins, aromatics, water (steam), carbon dioxide, carbon monoxide, nitrogen, argon, helium, And a gas inert to the reaction, such as a mixture thereof, can be present as a diluent. Of these, paraffins and aromatics may react slightly depending on the reaction conditions, but are defined as diluents because the reaction amount is small.
As such a diluent, impurities contained in the reaction raw material may be used as they are, or a separately prepared diluent gas may be used by mixing with the reaction raw material.
The diluent may be mixed with the reaction raw material before entering the reactor, or may be supplied to the reactor separately from the reaction raw material.
Preferred diluents for the present invention are paraffins having 4 or more carbon atoms, more preferably normal butane and / or isobutane. These paraffins are advantageous in that control of the reaction temperature is facilitated because they can be used in olefin raw materials and are relatively large heat capacities.

<Purification process>
The reaction product is subjected to a general separation and purification process such as cooling, compression and distillation, a stream rich in hydrocarbons having 2 or less carbon atoms, a stream rich in hydrocarbons having 3 or more carbon atoms, and a carbonization having 3 carbon atoms. A stream rich in hydrogen, a stream rich in propylene, a stream rich in propane, a stream rich in hydrocarbons having 3 or less carbon atoms, a stream rich in hydrocarbons having 4 or more carbon atoms, and a carbonization having 4 to 6 carbon atoms It is separated into a stream rich in hydrogen, a stream rich in hydrocarbons having 7 or more carbon atoms, a stream rich in water, and the like. These flows are selected according to the process aspect. Further, quenching, alkali cleaning, dehydration and the like can be performed as necessary.

  A stream rich in hydrocarbons having 2 or less carbon atoms is a stream in which the content of hydrocarbons having 2 or less carbon atoms is increased in the stream discharged from the separator compared to the stream supplied to the separator. Preferably, the stream contains the most hydrocarbons having 2 or less carbon atoms, and more preferably, the stream contains 60% by weight or more hydrocarbons having 2 or less carbon atoms. . Similarly, other flows can be defined.

An example of the purification process will be described with reference to FIG.
In FIG. 1, three compressors, ie, a first compressor (13), a second compressor (17), and a third compressor (22) are connected in series as tanks (15), (20 ), The compression device is not limited to the one provided in three stages, and may be provided in two or more stages, and may be provided in two stages or four or more stages.
Examples of the compressor include a centrifugal compressor, an axial flow compressor, and a reciprocating compressor, but the type of the compressor is not particularly defined.
The compressors (compressors) provided in multiple stages are designed to increase the pressure and increase the degree of compression toward the rear stage.

  In the case where an oxygen-containing compound such as methanol or dimethyl ether is contained in the reaction product, at least a part of the oxygen-containing compound is removed by, for example, the quenching step (8) in FIG. When the mixed stream (7) exiting the reactor (6) contains an acidic gas such as carbon dioxide, at least a part of the acidic gas is removed by alkali cleaning. The quench step (8) may also separate at least a portion of the water contained in the mixed stream (7) exiting the reactor (6), the separated water being a water-rich stream (10). May be discharged out of the system. Further, the reactor outlet gas may be cooled simultaneously with the separation of at least a part of the water contained in the outlet gas of the reactor (6) by the quenching step (8). For example, the temperature of the quenching step (8) is preferably 30 ° C. to 130 ° C., and the pressure is preferably 0.01 to 0.20 MPa (absolute pressure).

The gas cooled by the quench step (8) is sent to the tank (11) as a flow (9) and supplied to the first compressor (13) as a flow (12).
The stream (12) is compressed by the first compressor (13), becomes a stream (14) whose pressure is increased by the compression, and is temporarily stored in the tank (15). At this time, the pressure of the flow (12) is preferably 0 to 0.25 MPa (absolute pressure), and is preferably increased to 0.25 to 0.50 MPa (absolute pressure) by the first compressor (13). The temperature of the pressurized stream (14) is preferably 20-60 ° C. The gas component in the tank (15) is supplied as a flow (16) to the second compressor (17) in the next stage, and the liquid component in the tank (15) is supplied as a flow (19) to a stripper (distillation device) (37). Supplied. At this time, the flow rate ratio of the flow (16) and the flow (19) is preferably 80 to 99% by weight: 1 to 20% by weight (however, the total of the flow (16) and the flow (19) is 100% by weight. %).

  The stream (16) is compressed by the second compressor (17), becomes a stream (18) whose pressure is increased by the compression, and is temporarily stored in the tank (20). At this time, the pressure of the flow (16) is preferably 0.25 to 0.50 MPa (absolute pressure), and is preferably increased to 0.50 to 0.90 MPa (absolute pressure) by the second compressor (17). Flow (18). The temperature of the pressurized stream (18) is preferably 20-60 ° C. The gas component in the tank (20) is supplied as a flow (21) to the third compressor (22) at the last stage, and the liquid component in the tank (20) is supplied as a flow (24) to the stripper (37). At this time, the flow rate ratio between the flow (21) and the flow (24) is preferably 50 to 90% by weight: 10 to 50% by weight (however, the total of the flow (21) and the flow (24) is 100% by weight. %).

  The flow (21) is compressed by the third compressor (22), becomes a flow (23) whose pressure is increased by the compression, and is temporarily stored in the tank (25). At this time, the pressure of the flow (21) is preferably 0.50 to 0.90 MPa (absolute pressure), and is preferably increased to 0.90 to 4.00 MPa (absolute pressure) by the third compressor (22). Flow (23). The temperature of the pressurized stream (23) is preferably 20-60 ° C.

  The gas component in the tank (25) is supplied as a flow (26) to the moisture removal equipment (27), and the moisture in the gas component (mainly composed of methane, ethylene and propylene) is removed. In addition, the liquid component in the tank (25) is supplied as a flow (29) to the water removal facility (30), and the water in the liquid component (mainly hydrocarbons having 3 or more carbon atoms) is removed. At this time, the temperature and pressure are almost the same, but the liquid component is more than the gas component, usually about 10 times, and the flow ratio of the flow (26) to the flow (29) is 1 to 20% by weight: It is preferably 99 to 80% by weight (however, the total of stream (26) and stream (29) is 100% by weight).

  Separation of water can be performed by condensing water vapor mainly by cooling and / or compression. For example, the water may be separated by the compressor (13) or the compressor (17) shown in FIG. Moisture remaining in the compressed stream (14) or (18) may be removed with a moisture removal facility filled with an adsorbent such as molecular sieve, and is recirculated to the quench step (8) by recirculating to the quench step ( In step 8), moisture may be removed. The water removed by condensation and / or adsorption may be used for a wastewater treatment process such as activated sludge, but can also be used for process water or the like.

  A stripper (37) separates a stream (38) having a suitable propylene content, which will be described later, as a gas component, and a stream (39) rich in hydrocarbon having 4 to 6 carbon atoms and a hydrocarbon having 7 or more carbon atoms. In order to separate the rich stream (49), it is preferable to operate at a temperature of 30 to 200 ° C., particularly 50 to 150 ° C. The pressure is preferably operated at 0.25 to 2.00 MPa (absolute pressure), particularly preferably 0.50 to 1.50 MPa (absolute pressure). More specifically, the top pressure of the stripper (37) is 0.50 to 1.00 MPa (absolute pressure), the top temperature is 30 to 100 ° C., the inlet pressure is 0.60 to 1.20 MPa (absolute pressure), It is preferable to operate at an inlet temperature of 30 to 100 ° C., a tower bottom pressure of 0.50 to 1.20 MPa (absolute pressure), and a tower bottom temperature of 80 to 200 ° C.

In the present invention, the gaseous component stream (38) separated by the stripper (37) usually contains 1 to 50% by weight, preferably 1 to 40% by weight, of the product propylene. Is returned to the tank (20) and fed to the third compressor (22) via the tank (20).
If only the stream (39) is separated without performing the operation of fractionating the stream (38) and returning it to the last stage compressor (22), the streamer (37) is included in the streams (19) and (24). Part of the propylene supplied to the reactor is recycled to the reactor (6) in the streams (39) and (43) without being sent to the propylene purification column (46) for separating propylene. However, since a part is contained in the flow (44) and discharged out of the system, the yield of propylene decreases.

  Since the stream (39) contains hydrocarbons having 4 or more and 6 or less carbon atoms, it becomes a reaction raw material and may be recycled to the reactor (6). The stream (49) may be discharged out of the system because it contains aromatics such as toluene and xylene, which are components that reduce the catalyst life. Stream (49) may also be recycled to reactor (6), may be utilized as fuel for this process and / or other processes, and may be used as gasoline with or without purification. The raw material of this process and / or other processes may be used.

  The stream (28) and the stream (31) are separated into a hydrocarbon-rich stream (33) having 2 or less carbon atoms and a stream (36) rich in hydrocarbons having 3 or more carbon atoms in the de-C2 column (32). Is done. The hydrocarbon-rich stream (33) having 2 or less carbon atoms is preferably recycled to the reactor (6). At this time, at least a part of the stream (33) is paraffins such as methane and ethane in the system. May be purged out of the system as purge stream (34), and stream (35) may be recycled to reactor (6).

  A purge stream (34) rich in hydrocarbons having 2 or less carbon atoms is preferably utilized as fuel for the present process and / or other processes. Further, it may be used as a regeneration gas for removing water adsorbed by an adsorbent such as molecular sieve filled in the water removal step (27) and / or (30) of this process. Further, the purge stream (34) rich in hydrocarbons having 2 or less carbon atoms may be further separated and used as a raw material for products and other processes.

The distillation separation condition of the de-C2 column (32) is ethylene in the stream (36) rich in hydrocarbons having 3 or more carbon atoms extracted from the bottom of the de-C2 column (32), calculated by the following formula 1. In addition, it is preferable to set conditions so that the weight ratio of ethane is 0 to 0.03.
Total weight of ethylene and ethane in stream (36) / total weight of stream (36) (Equation 1)
Further, decalcification of C2 with respect to the total weight of propylene and propane in the gas and liquid (that is, the sum of stream (28) and stream (31)) supplied to the de-C2 tower (32) calculated by the following equation Conditions are set so that the total weight ratio of propylene and propane in the stream (33) rich in hydrocarbons having 2 or less carbon atoms withdrawn from the top of the tower (32) is 0 to 0.01. Is preferred.
Total weight of propylene and propane in stream (33) / total weight of propylene and propane included in sum of stream (28) and stream (31) (Equation 2)

  In addition to the foregoing embodiment, the streams (28) and (31) are separated into a hydrocarbon rich stream having 3 or less carbon atoms and a hydrocarbon rich stream having 4 or more carbon atoms, and then converted to a hydrocarbon having 3 or less carbon atoms. The rich stream may be separated into a hydrocarbon rich stream having 2 or less carbon atoms and a hydrocarbon rich stream having 3 carbon atoms.

  The hydrocarbon-rich stream (36) having 3 or more carbon atoms is divided into a stream (41) rich in hydrocarbons having 3 carbon atoms and a stream rich in hydrocarbons having 4 or more carbon atoms (42) in the de-C3 tower (40). ).

The distillation separation conditions of the de-C3 column (40) are the butenes in the hydrocarbon-rich stream (41) extracted from the top of the de-C3 column (40) calculated by the following formula 3. It is preferable to set conditions such that the molar ratio of hydrocarbons having 4 carbon atoms such as butane and butadiene is 0 to 0.03.
Number of moles of C4 hydrocarbons in stream (41) / total number of moles of stream (41) (Equation 3)
Further, the total molar ratio of propylene and propane in the stream (42) rich in hydrocarbons having 4 or more carbon atoms extracted from the bottom of the de-C3 tower (40) calculated by the following formula 4 is 0. It is preferable to set the conditions so as to be ˜0.03.
Total moles of propylene and propane in stream (42) / total moles of stream (42)
... (Formula 4)

  The hydrocarbon-rich stream (41) having 3 carbon atoms is separated in the propylene purification column (46) into a propylene-rich stream (47) and a propane-rich stream (48).

The distillation separation conditions of the propylene purification column (46) were such that the molar ratio of propylene in the propylene-rich stream (47) withdrawn from the top of the propylene purification column (46) calculated by the following formula 5 was 0.00. It is preferable to set the conditions so as to be 9 to 1.0.
Number of moles of propylene in stream (47) / total number of moles of stream (47) (Formula 5)
Also, it is extracted from the top of the propylene purification column (46) with respect to propylene in the hydrocarbon-rich stream (41) supplied to the propylene purification column (46) calculated by the following formula (6). It is preferable to set the conditions so that the molar proportion of propylene in the propylene-rich stream (47) to be discharged is 0.9 to 1.0.
Number of moles of propylene in stream (47) / number of moles of propylene in stream (41)
... (Formula 6)

  The hydrocarbon-rich stream (42) having 4 or more carbon atoms is preferably combined with the stream (39) and recycled to the reactor (6) as a stream (43), at which time one of the streams (43) In order to prevent paraffins such as butane and pentane from accumulating in the system, the part may be purged out of the system as a purge stream (44) and recycled to the reactor (6) as stream (45). . Further, the purge stream (44) may be used, for example, as a fuel for the present process and / or other processes, and may be steam cracked as a raw material for the steam cracker to produce olefins such as ethylene and propylene.

As described above, in the present invention, the compressor may be provided in two or more stages, and is not limited to the case where it is provided in three stages as shown in FIG. When the compressor is provided in two stages, the liquid component generated by the compression of the former stage compressor is fed to the stripper (37), and the gas component separated by the stripper (37) is fed to the latter stage compressor. do it. In addition, when the compressors are provided in three stages as shown in FIG. 1, only the liquid component generated by the compression of the first stage compressor (13) can be supplied to the stripper (37). The liquid component generated by the compression of the first stage compressor (13) and the second stage compressor (17) is fed to the stripper (37), and the gas component separated by the stripper (37) is supplied to the last stage. It is advantageous in terms of maintaining propylene yield to be fed to the first stage compressor (22).
Furthermore, even when the compressor is provided in multiple stages of four or more stages, the liquid component generated by the compression of the stripper other than the last stage compressor is fed to the stripper, and the gas component separated by the stripper is supplied to the last stage. Preferably it is fed to the compressor.

Hereinafter, the present invention will be described more specifically with reference to examples.
In the following Example 1 and Reference Example 1, the processes shown in FIGS. 1 and 2 are constructed on a computer according to an actual process using “Aspen Plus” (manufactured by Aspen Technology, Inc.) as a process simulator. This is a simulation. Aspen Plus is process modeling software that includes physical property estimation models for ordinary chemicals, electrolytes, solids and polymers, and a large database of pure substance parameters. Design conditions and operating conditions for distillation and solvent extraction in actual plants Is the software that can reproduce the data equivalent to the actual plant by calculation based on chemical engineering methods.

[Example 1]
The process flow shown in FIG.
The de-C2 tower (32) in FIG. 1 has 40 theoretical plates, and is operated at a tower top pressure of 3.0 MPaA (“MPaA” indicates “absolute pressure”, the same applies hereinafter).
The de-C2 tower is supplied with streams (28) and (31) from the water removal facilities (27) and (30) in the sixth and ninth stages from the top of the tower, respectively, and carbon such as ethylene and ethane. A stream (33) rich in hydrocarbons having a number of 2 or less is withdrawn from the top, and a stream (36) rich in hydrocarbons with 3 or more carbon atoms such as propylene is withdrawn from the bottom. At this time, conditions are set so that the value calculated by the expression 1 is 0.0001 and the value calculated by the expression 2 is 0.0008. Table 1 shows the column diameter of the de-C2 column (32) and the reboiler heat load at this time.

  The de-C3 tower (40) has 39 theoretical plates and is operated at a tower top pressure of 2.0 MPaA. The de-C3 column (40) is fed with a hydrocarbon-rich stream (36) having 3 or more carbon atoms from the de-C2 column (32) having the following composition from the 20th theoretical plate from the top of the column. And a propane-rich C3 hydrocarbon-rich stream (41) is withdrawn from the top, and a hydrocarbon-rich stream (42) with 4 or more carbons such as butene and butane is withdrawn from the bottom. . At this time, conditions are set so that the value calculated by Equation 3 is 0.001 and the value calculated by Equation 4 is 0.001. Table 2 shows the tower diameter of the de-C3 tower (40) and the heat load of the reboiler at this time.

(Composition of stream (36):% by weight)
Propylene: 21.6
Propane: 1.8
Butenes: 11.0
Butanes: 49.1
C5 class: 15.8
C6 or more: 0.7

The stripper (37) has 17 theoretical plates and is operated at a top pressure of 0.75 MPaA.
In the stripper (37), the flow (19), (24) of the liquid components from the first compressor (13) and the second compressor (17) having the following composition is supplied to the tanks (15), (20), respectively. From the top of the tower, a stream (38) rich in hydrocarbons having 3 or less carbon atoms such as propylene and propane is extracted from the top of the tower and passed through the tank (20) to the third tank. It is fed to the compressor (22). Also, a hydrocarbon-rich stream (39) having 4 or more and 6 or less carbon atoms is withdrawn from the theoretical stage of 14 stages from the top of the column, and a stream of high-boiling components such as olefins and paraffins having 7 or more carbon atoms (49 ) Is extracted from the bottom of the tower. Table 4 shows the tower diameter of the stripper (37) and the heat load of the reboiler at this time. The propylene content in stream (38) is 19% by weight.

(Composition of stream (19):% by weight)
C2 or less: 0.2
Propylene: 1.6
Propane: 0.2
Butenes: 4.1
Butanes: 14.3
C5 class: 24.7
C6 or higher: 54.7
Water: 0.2

(Composition of stream (24):% by weight)
C2 or less: 1.4
Propylene: 6.0
Propane: 0.6
Butenes: 9.8
Butanes: 38.7
C5 class: 36.0
C6 or higher: 7.2
Water: 0.3

The compression conditions of the first to third compressors (13), (17), and (22) at this time are as follows.
Flow (12): pressure about 0.1 MPaA, temperature about 50 ° C.
Flow (14): pressure of about 0.3 MPaA, temperature of about 100 ° C.
Flow (16): pressure of about 0.3 MPaA, temperature of about 40 ° C.
Flow (18): pressure about 0.9 MPaA, temperature about 90 ° C
Flow (19): pressure of about 0.3 MPaA, temperature of about 40 ° C.
Flow (21): Pressure of about 0.7 MPaA, temperature of about 40 ° C
Flow (23): pressure about 2.7 MPaA, temperature about 100 ° C
Flow (24): pressure about 0.73 MPaA, temperature about 40 ° C
The flow ratio between the flow (16) and the flow (19) is 97% by weight of the flow (16) and 3% by weight of the flow (19), and the flow ratio of the flow (21) and the flow (24) is the flow ( 21) 66 wt%, stream (24) 34 wt%.

  The inlet pressure of the stripper (37) is about 1.00 MPaA, the temperature is about 40 ° C., the pressure at the bottom of the stripper (37) is about 0.76 MPaA, the temperature is 110 to 120 ° C., and the stripper (37) The pressure at the top of the column is about 0.75 MPaA, and the temperature is about 50-60 ° C.

  The propylene purification column (46) has 200 theoretical plates and is operated at a column top pressure of 1.9 MPaA. In the propylene purification column (46), the hydrocarbon-rich stream (41) from the de-C3 tower (40) is fed from the 117th theoretical plate from the top of the tower, and the propylene-rich stream (47 ) From the top and a propane-rich stream (48) from the bottom. At this time, conditions are set so that the value calculated by Equation 5 is 0.96 and the value calculated by Equation 6 is 0.97. Table 5 shows the column diameter of the propylene purification column (46) and the heat load of the reboiler at this time.

[Reference Example 1]
The process flow shown in FIG.
In FIG. 2, members having the same functions as those shown in FIG. In this process flow, the flow (19), (24) from the tanks (15), (20) was fed to the moisture removing device 30, and the carbon from the de-C3 tower (40) instead of the stripper (37). The hydrocarbon-rich stream (42) having 4 or more carbon atoms is further separated into a hydrocarbon-rich stream (39) having 4 to 6 carbon atoms and a hydrocarbon-rich stream (49) having 7 or more carbon atoms. The process flow shown in FIG. 1 is different from the process flow shown in FIG. 1 in that the de-C6 tower (50) is provided.

  The de-C2 tower (32) has 43 theoretical plates, and is operated at a tower top pressure of 3.0 MPaA in the same manner as in Example 1. The value calculated by the equation 1 is 0.0001, and the equation 2 The condition is set so that the value calculated in (1) becomes 0.0008. Table 1 shows the diameter of the de-C2 tower and the heat load of the reboiler at this time.

The de-C3 tower (40) has 68 theoretical plates and is operated at a tower top pressure of 2.0 MPaA in the same manner as in Example 1. The value calculated by Equation 3 is 0.001 and Equation 4 is Conditions are set so that the calculated value is 0.001. Table 2 shows the tower diameter of the de-C3 tower (40) and the heat load of the reboiler at this time.
The de-C6 column (50) has 16 theoretical plates and is operated at a column top pressure of 0.40 MPaA. In the de-C6 column (50), a hydrocarbon-rich stream (39) having 4 to 6 carbon atoms is withdrawn from the top, and a hydrocarbon-rich stream (49) having 7 or more carbon atoms is withdrawn from the bottom. Table 4 shows the tower diameter of the de-C6 tower (50) and the reboiler thermal load at this time.

  The propylene purification column (46) has 98 theoretical plates, and is operated at a column top pressure of 1.9 MPaA as in Example 1. The value calculated by the above equation 5 is 0.96, Conditions are set so that the calculated value is 0.97. Table 5 shows the column diameter of the propylene purification column (46) and the heat load of the reboiler at this time.

As described above, the total reboiler load in Example 1 was 33.0 MW, while the total reboiler load in Reference Example 1 was 82.4 MW.
Therefore, according to the present invention, it is understood that the energy required for the purification system can be reduced while maintaining the yield of propylene.

2 MTD reactor 6 Reactor 8 Quenching process 11, 15, 20, 25 Tank 13, 17, 22 Compressor 27, 30 Water removal equipment 32 De-C2 tower 33 Hydrocarbon rich stream with 2 or less carbon atoms 36 Carbon number A stream rich in 3 or more hydrocarbons 37 Stripper
39 C 4 to 6 hydrocarbon rich stream 40 De-C3 tower 41 C 3 hydrocarbon rich stream 42 C 4 hydrocarbon rich stream 46 Propylene purification tower 47 Propylene rich Stream 48 Propane rich stream 49 Carbon 7 or higher hydrocarbon rich stream 50 De-C6 tower

Claims (4)

After cooling the reaction product obtained by reacting olefin with methanol and / or dimethyl ether, the gas components generated by the compression in the former compression device are compressed into the two or more compression devices provided in multiple stages. In the method for producing propylene, the propylene is obtained sequentially from the components produced by the compression in the last-stage compression device.
At least a liquid component generated by the compression in the first stage compression apparatus is supplied to the distillation apparatus, and a gas component discharged from the distillation apparatus is supplied to the distillation apparatus as a liquid component generated by the compression. A method for producing propylene, which is supplied to a later-stage compression apparatus.   The method for producing propylene according to claim 1, wherein the olefin is reacted with methanol and / or dimethyl ether in the presence of an aluminosilicate catalyst.   The method for producing propylene according to claim 1 or 2, wherein the liquid component fed to the distillation apparatus contains 10 mol% or more of an olefin having 4 or more carbon atoms.   The compression apparatus is provided in three stages, and the liquid component generated by the compression in the first-stage compression apparatus and the second-stage compression apparatus is supplied to the distillation apparatus and is discharged from the distillation apparatus. The method for producing propylene according to any one of claims 1 to 3, wherein the gas component is fed to the last-stage compression device.

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