Method and system for comprehensive utilization of liquefied gas

Abstract

The application discloses a liquefied gas comprehensive utilization method and system. The method comprises the following steps: separating a liquefied gas raw material to obtain a first stream and a second stream; separating the obtained second stream to obtain a third stream and a fourth stream; subjecting the third stream to a hydrogenation reaction to obtain a fifth stream which is subjected to a reaction in a normalization unit; separating reaction effluent to obtain a sixth stream and a seventh stream; recycling the seventh stream to a first separation unit and / or a second separation unit; subjecting the fourth stream to a hydrogenation reaction to obtain a reaction product; separating the reaction product to obtain an eighth stream and a ninth stream; separating the ninth stream to obtain a tenth stream and an eleventh stream; subjecting the tenth stream to separation to obtain a twelfth stream and a n-butane product. The application further provides a liquefied gas comprehensive utilization system comprising a first separation unit, a second separation unit, a third separation unit, a first hydrogenation unit, a second hydrogenation unit, a normalization unit, a normalization separation unit, a hydrogenation separation unit and a heavy component removal tower. The method can realize efficient utilization of each component in the liquefied gas, and provides strong technical support for resource utilization of the liquefied gas.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of light hydrocarbon utilization, and particularly relates to a liquefied gas utilization method and system. BACKGROUND

[0002] At present, degradable materials have ushered in new development opportunities, and BDO as the main raw material has attracted close attention. In the n-butane-maleic anhydride-BDO industrial chain, the stable supply of n-butane raw material is the key problem to be solved first.

[0003] At present, n-butane is mainly derived from liquefied gas. For the liquefied gas treatment process, the traditional gas fractionation process is only a physical process, and due to the limitation of separation principle, if the n-butane yield is to be increased, the treatment capacity of liquefied gas must be increased, which will be limited by many factors such as source, transportation, cost, etc.

[0004] CN104892339 discloses a method for preparing n-butane from isobutane, comprising the following steps: A. providing a feed gas stream a containing at least 80% of isobutane by mass percentage; B. feeding the feed gas stream a into at least one normalization region, and allowing the isobutane to undergo normalization reaction under the action of a catalyst, thereby obtaining a product gas stream b; C. feeding the product gas stream b into at least one hydrogenation saturation region to perform hydrogenation catalytic reaction, thereby obtaining a gas stream c; D. condensing and separating the gas stream c at 0-40℃ to obtain a gas phase stream d1 and a liquid phase stream d2; E. feeding the liquid phase stream d2 into a first distillation region to further separate the low-boiling secondary components in the liquid phase stream d2 to form a product stream e2 containing isobutane and n-butane; F. feeding the stream e2 into a second distillation region to separate the isobutane and n-butane to form an n-butane stream.

[0005] CN108530254 discloses a method for preparing n-butane from mixed carbon four, which comprises the following steps: putting the by-products carbon four generated in the production processes of petroleum refining, steam cracking for ethylene, methanol for olefin, etc. into a fixed bed reactor, adding a hydrogenation catalyst into the reactor, circulating hydrogen gas for hydrogenation reaction, mixing with a desulfurizing agent uniformly, and feeding into a distillation column, feeding the desulfurized product into a rectifying column, collecting propane at the top of the rectifying column, collecting n-butane at the bottom, and collecting isobutane in the middle, and allowing the collected isobutane to undergo normalization reaction under the action of a catalyst to generate n-butane.

[0006] Moreover, it is found through analysis that CN104892339 and CN108530254 both use halogen-containing catalysts, and the halogen in such catalysts is easy to be lost during the reaction process. In order to maintain the activity of the catalyst, halides need to be constantly added, which not only causes corrosion to the equipment, but also pollutes the environment. SUMMARY

[0007] In view of the deficiencies in the prior art, the main purpose of the present application is to provide a liquefied gas comprehensive utilization method and system, the present application method can realize efficient utilization of each component in liquefied gas, and provides strong technical support for resource utilization of liquefied gas.

[0008] The first aspect of the present application provides a liquefied gas comprehensive utilization method, comprising the following steps:

[0009] (1) The liquefied gas raw material enters the first separation unit, and after separation, the first stream at the top and the second stream at the bottom are obtained;

[0010] (2) The second stream at the bottom obtained in step (1) enters the second separation unit, and after separation, the third stream at the top and the fourth stream at the bottom are obtained;

[0011] (3) The third stream at the top obtained in step (2) enters the first hydrogenation unit, and under the action of hydrogen and the first hydrogenation catalyst, hydrogenation reaction is carried out to obtain the fifth stream of hydrogenation reaction product;

[0012] (4) The fifth stream obtained in step (3) enters the normalization unit, and under the action of the normalization catalyst, reaction is carried out, and after the gas-liquid separation of the reaction effluent, the sixth stream in the gas phase and the seventh stream in the liquid phase are obtained, and the seventh stream in the liquid phase is recycled back to the first separation unit and / or the second separation unit;

[0013] (5) The fourth stream at the bottom obtained in step (2) enters the second hydrogenation unit, and under the action of hydrogen and the second hydrogenation catalyst, hydrogenation reaction is carried out, and after the gas-liquid separation of the hydrogenation reaction product, the eighth stream in the gas phase and the ninth stream in the liquid phase are obtained;

[0014] (6) The ninth stream in the liquid phase obtained in step (5) enters the heavy removal column and is separated to obtain the tenth stream at the top and the eleventh stream at the bottom;

[0015] (7) The tenth stream at the top obtained in step (6) enters the third separation unit, and after separation, the twelfth stream at the top and the thirteenth stream at the bottom are obtained, and the thirteenth stream at the bottom is a normal butane product.

[0016] Further, in the above liquefied gas comprehensive utilization method, the liquefied gas raw material in step (1) can be one or more of the following: by-product gas from a refinery atmospheric-vacuum unit, by-product gas from a catalytic cracking unit, by-product gas from a reforming unit, by-product gas from a hydrocracking unit, by-product gas from a coking unit, ethylene plant cracking gas, MTO device by-product gas, oilfield associated gas, and natural gas field associated gas, preferably carbon four liquefied gas after separation of olefins (ethylene, propylene).

[0017] Further, in the liquefied gas comprehensive utilization method, the first separation unit in step (1) is used to separate C2, C3 and other light components in advance. The first separation unit can be a rectification tower, and can be a plate tower or a packing tower. The operating conditions of the first separation unit are as follows: the tower top pressure is 0.8-3.5 MPa, preferably 1.1-2.2 MPa; and the tower bottom temperature is 80-160 °C, preferably 90-110 °C.

[0018] Further, in the liquefied gas comprehensive utilization method, the second separation unit in step (2) can be a rectification tower, and can be a plate tower or a packing tower. The operating conditions of the second separation unit are as follows: the tower top pressure is 0.2-2.5 MPa, preferably 0.3-1 MPa; and the tower bottom temperature is 40-150 °C, preferably 50-110 °C.

[0019] Further, in the liquefied gas comprehensive utilization method, the second separation unit in step (2) can be a rectification tower, and can be a plate tower or a packing tower. The operating conditions of the second separation unit are as follows: the tower top pressure is 0.2-2.5 MPa, preferably 0.3-1 MPa; and the tower bottom temperature is 40-150 °C, preferably 50-110 °C.

[0020] Further, in the liquefied gas comprehensive utilization method, the third stream in step (3) enters the first hydrogenation unit to undergo olefin saturation reaction, and the isobutene in the third stream is saturated by hydrogenation to obtain isobutane. The operating conditions of the first hydrogenation unit are as follows: the reaction temperature is 100-350 °C, preferably 200-260 °C; the reaction pressure is 1.0-6.0 MPa, preferably 2.5-4.2 MPa; the volume space velocity is 0.5-10 h -1 , preferably 1.0-5.0 h -1 ; and the hydrogen / oil volume ratio is 100:1-1000:1, preferably 300:1-600:1. The first hydrogenation catalyst can be a commercially available product or prepared according to the methods disclosed in the art, such as LH-10, FH-40C and HDO-18 catalysts developed by Dalian Petrochemical Research Institute of China Petroleum Chemical Co., Ltd.

[0021] Further, in the liquefied gas comprehensive utilization method, the fifth stream obtained after the reaction of the first hydrogenation unit in step (3) is a stream rich in isobutane.

[0022] Further, in the liquefied gas comprehensive utilization method, the operating conditions of the normalization unit in step (4) are as follows: the reaction temperature is 200-500°C, preferably 300-400°C; the reaction pressure is 0.5-5 MPa, preferably 0.8-3.5 MPa; the hydrogen / oil volume ratio is 10:1-1000:1, preferably 30:1-500:1; the volume space velocity is 0.1-5 h -1 , preferably 0.5-3 h -1 .

[0023] Further, in the liquefied gas comprehensive utilization method, the normalizing unit in step (4) is provided with at least one reactor, which can be one or more of a fixed bed reactor, a moving bed reactor, and a fluidized bed reactor, and is preferably a fixed bed reactor.

[0024] Further, in the liquefied gas comprehensive utilization method, the normalizing catalyst used in the normalizing unit in step (4) is a supported noble metal catalyst, which comprises a carrier, an active component, and an additive; the active component is one or more of Pt, Pd, Ru, Rh, and Ir, and is preferably one or more of Pt and Pd; the carrier is one or a combination of alumina, silica, amorphous silica-alumina, and a molecular sieve, wherein the molecular sieve is at least one of ZSM-5, ZSM-11, ZSM-22, Y molecular sieve, and β molecular sieve; and the additive is one or more of a Group VIII transition metal and a rare earth metal. Further specifically, the active component content of the catalyst is 0.1-0.5 wt%, the additive content is 0.01-0.1 wt%, the bulk density is 0.64-0.74 g / cm 3 , the specific surface area is 180-280 m 2 / g, and the pore volume is 0.28-0.38 mL / g, based on the weight of the catalyst. The normalizing catalyst can be prepared according to the existing catalyst preparation method.

[0025] Further, in the liquefied gas comprehensive utilization method, the gaseous sixth stream obtained by gas-liquid separation of the normalizing reaction effluent in step (4) can be used as recycled hydrogen after conventional treatment, and can be recycled to the first hydrogenation unit and / or the second hydrogenation unit.

[0026] Further, in the liquefied gas comprehensive utilization method, the fourth stream at the bottom obtained in step (2) in step (5) enters the second hydrogenation unit, in which mainly an olefin saturation reaction occurs, and 2-butene contained in the fourth stream is saturated by hydrogenation to obtain butane. The operating conditions of the second hydrogenation unit are as follows: the reaction temperature is 100-350°C, preferably 200-260°C; the reaction pressure is 1.0-6.0 MPa, preferably 2.5-4.2 MPa; and the volume space velocity is 0.5-10 h -1, preferably 1.0-5.0 h -1 ; the volume ratio of hydrogen to oil is 100:1-1000:1, preferably 300:1-600:1. The second hydrogenation catalyst can be commercially available or prepared according to the methods disclosed in the art, such as LH-10, FH-40C, and HDO-18 brand catalysts developed by Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation.

[0027] Further, in the liquefied gas comprehensive utilization method, the gaseous eighth stream obtained by gas-liquid separation of the hydrogenation reaction product in step (5) is subjected to optional purification treatment and used as recycle hydrogen, which can be recycled to the first hydrogenation unit and / or the second hydrogenation unit, preferably the first hydrogenation unit.

[0028] Further, in the liquefied gas comprehensive utilization method, the operating conditions of the heavy component removal column in step (6) are generally controlled as follows: the column top pressure is 0.3-2.5 MPa, preferably 0.6-1.5 MPa; and the column bottom temperature is 60-180℃, preferably 80-110℃.

[0029] Further, in the liquefied gas comprehensive utilization method, the eleventh stream at the bottom of the column in step (6) is a C5+ component.

[0030] Further, in the liquefied gas comprehensive utilization method, the twelfth stream at the top of the column obtained by separation in step (7) is subjected to treatment in a normalization unit.

[0031] Further, in the liquefied gas comprehensive utilization method, the third separation unit in step (7) can be a rectification column, specifically any one of a plate column and a packed column. The third separation unit is mainly used to further remove C4 hydrocarbons in the n-butane stream by rectification to ensure the product quality of n-butane. The operating conditions of the third separation unit are generally controlled as follows: the column top pressure is 0.5-1.5 MPa, preferably 0.6-1.0 MPa; and the column bottom temperature is 40-120℃, preferably 50-90℃.

[0032] The second aspect of the present application provides a liquefied gas comprehensive utilization system, comprising:

[0033] a first separation unit for receiving and separating a liquefied gas raw material to obtain a first stream at the top of the column and a second stream at the bottom of the column;

[0034] a second separation unit for receiving and separating the second stream at the bottom of the column from the first separation unit to obtain a third stream at the top of the column and a fourth stream at the bottom of the column;

[0035] a first hydrogenation unit for receiving hydrogen and the third stream from the second separation unit, and performing hydrogenation reaction under the action of a first hydrogenation catalyst to obtain a hydrogenation reaction product fifth stream;

[0036] a normalizing unit for receiving the hydrogenation reaction product fifth stream from the first hydrogenation unit, and performing reaction under the action of a normalizing catalyst;

[0037] a normalizing separation unit for receiving the reaction effluent from the normalizing unit, and obtaining a gas phase sixth stream and a liquid phase seventh stream after gas-liquid separation, and recycling the liquid phase seventh stream back to the first separation unit and / or the second separation unit through a pipeline;

[0038] a second hydrogenation unit for receiving hydrogen and the fourth stream from the second separation unit, and performing hydrogenation reaction under the action of a second hydrogenation catalyst;

[0039] a hydrogenation separation unit for receiving the hydrogenation reaction product from the second hydrogenation unit, and obtaining a gas phase eighth stream and a liquid phase ninth stream after gas-liquid separation;

[0040] a heavy-removal column for receiving the liquid phase ninth stream from the hydrogenation separation unit, and obtaining a top tenth stream and a bottom eleventh stream after separation of the liquid phase ninth stream into the heavy-removal column;

[0041] a third separation unit for receiving the top tenth stream from the heavy-removal column, and obtaining a top twelfth stream and a bottom thirteenth stream after separation, wherein the bottom thirteenth stream is a normal butane product.

[0042] Further, in the liquefied gas comprehensive utilization system, the normalizing unit is provided with at least one reactor, and the reactor can adopt one or more of a fixed bed reactor, a moving bed reactor and a fluidized bed reactor, and is preferably a fixed bed reactor.

[0043] Further, in the liquefied gas comprehensive utilization system, the first hydrogenation unit is provided with at least one hydrogenation reactor, and when two or more hydrogenation reactors are provided, the hydrogenation reactors can be connected in series and / or in parallel. The specific arrangement of the first hydrogenation unit can be selected by those skilled in the art according to the requirements of the device and the process.

[0044] Further, in the liquefied gas comprehensive utilization system, the second hydrogenation unit is provided with at least one hydrogenation reactor, and when two or more hydrogenation reactors are provided, the hydrogenation reactors can be connected in series and / or in parallel. The specific arrangement of the second hydrogenation unit can be selected by those skilled in the art according to the requirements of the device and the process.

[0045] Further, in the liquefied gas comprehensive utilization system, the first separation unit can adopt a rectifying tower, and specifically can adopt any one of a plate tower and a packed tower.

[0046] Further, in the liquefied gas comprehensive utilization system, the second separation unit can adopt a rectifying tower, and specifically can adopt any one of a plate tower and a packed tower.

[0047] Further, in the liquefied gas comprehensive utilization system, the third separation unit can adopt a rectifying tower, and specifically can adopt any one of a plate tower and a packed tower.

[0048] Further, in the liquefied gas comprehensive utilization system, the gaseous sixth material flow separated by the normalization separation unit can be recycled to the first hydrogenation unit and / or the second hydrogenation unit as circulating hydrogen through a pipeline, and preferably is recycled to the first hydrogenation unit and / or the second hydrogenation unit after being purified.

[0049] Further, in the liquefied gas comprehensive utilization system, the twelfth material flow obtained after separation of the third separation unit is introduced into the normalization unit for treatment through a pipeline.

[0050] Further, in the liquefied gas comprehensive utilization system, the gaseous eighth material flow obtained after gas-liquid separation of the hydrogenation separation unit is used as circulating hydrogen after being optionally purified, and can be recycled to the first hydrogenation unit and / or the second hydrogenation unit through a pipeline, and preferably is recycled to the first hydrogenation unit.

[0051] Compared with the prior art, the liquefied gas comprehensive utilization method and utilization system have the following beneficial effects:

[0052] (1) In the liquefied gas comprehensive utilization method and utilization system, different units such as separation-hydrogenation-normalization are combined, the liquefied gas is first separated into light components (C2, C3), isomerization components including isobutane and isobutene, and n-butane and 2-butene; then according to the properties of each component, the appropriate process unit is used for treatment, from the perspective of molecular management, each component is efficiently utilized, and the purpose of producing the maximum amount of n-butane is achieved.

[0053] (2) In the liquefied gas comprehensive utilization method and utilization system, the normalization unit is the core part of the efficient utilization of liquefied gas, and can convert isobutane into n-butane according to market demand, and timely ensure the large-scale supply of raw materials for the downstream maleic anhydride process.

[0054] (3) In the comprehensive utilization method and system of liquefied gas provided by the present invention, the hydrogenation unit is used to convert isoolefins in liquefied gas into isobutane, and then n-butane is produced through the ortho-alkation unit; at the same time, the hydrogenation unit can also convert n-olefins into n-butane, and produce n-butane in combination with the separation process; it can play a crucial role in increasing the n-butane yield.

[0055] (4) Based on the hydrogen requirements of different units, the present invention returns the recycled hydrogen from the second hydrogenation unit to the first hydrogenation unit as a hydrogen source; the outlet stream of the first hydrogenation unit includes hydrogen and isobutane after reaction, and the hydrogen in this stream can be directly used as a hydrogen source for the ortho-formation unit. The recycled hydrogen utilization scheme proposed in this invention optimizes the utilization of hydrogen resources, reduces the amount of hydrogen used, and helps to improve the overall economic efficiency of the technology of this invention. Attached Figure Description

[0056] Figure 1 This invention provides a schematic diagram of a comprehensive utilization method and system for liquefied petroleum gas. Detailed Implementation

[0057] The following embodiments further illustrate the comprehensive utilization method and system for liquefied petroleum gas (LPG) according to the present invention. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0058] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0059] like Figure 1As shown, the specific process of the comprehensive utilization method of liquefied gas provided by the present invention is as follows: liquefied gas feedstock 1 enters the first separation unit 2, and after separation, it obtains the first feed stream 3 at the top of the tower and the second feed stream 4 at the bottom of the tower; the second feed stream 4 at the bottom of the tower from the first separation unit enters the second separation unit 5, and after separation, it obtains the third feed stream 6 at the top of the tower and the fourth feed stream 7 at the bottom of the tower; the third feed stream 6 at the top of the tower from the second separation unit and hydrogen 26 enter the first hydrogenation unit 8, where they undergo a hydrogenation reaction under the action of the first hydrogenation catalyst, obtaining the fifth feed stream 9, a hydrogenation reaction product; the fifth feed stream 9, a hydrogenation reaction product from the first hydrogenation unit, enters the ortho-formation unit 10, where it undergoes a reaction under the action of the ortho-formation catalyst; the reaction effluent 11 enters the ortho-formation separation unit 12, and after gas-liquid separation, it obtains the sixth gas phase feed stream 13 and the seventh liquid phase feed stream 14, the sixth gas phase feed stream 13 and the seventh liquid phase feed stream 14, the seventh gas phase feed stream 14 and the seventh liquid phase feed stream 14, the seventh gas phase feed stream 13 ... The seventh feed stream 14 is circulated back to the first separation unit 1 and / or the second separation unit 2 via pipeline; the fourth feed stream 7 from the bottom of the second separation unit 5 and hydrogen 26 enter the second hydrogenation unit 15, where hydrogenation reaction is carried out under the action of the second hydrogenation catalyst; the hydrogenation reaction product 16 from the second hydrogenation unit enters the hydrogenation separation unit 17, and after gas-liquid separation, it yields the eighth gaseous feed stream 18 and the ninth liquid feed stream 19; the ninth liquid feed stream 19 enters the deweighting tower 20, and after further separation, it yields the eleventh bottom feed stream 21 and the tenth top feed stream 22; the tenth top feed stream 22 from the deweighting tower enters the third separation unit 23, and after separation, it yields the twelfth top feed stream 24 and the thirteenth bottom feed stream 25, wherein the thirteenth bottom feed stream 25 is n-butane product, and the twelfth top feed stream 24 enters the n-butane conversion unit via pipeline for processing.

[0060] In this paper, the composition of the liquefied petroleum gas (LPG) feedstock is shown in Table 1.

[0061] Table 1. Composition of LPG feedstock

[0062] Component Ethane Propane Propylene Isobutane n-Butane 2-Butene Isobutene n-Pentane Isopentane [C5 + ]]> Content, wt% 0.01 0.15 0.03 40.79 15.75 20.18 22.71 0.12 0.08 0.19

[0063] In this paper, the first hydrogenation catalyst is the LH-10 catalyst developed by the Dalian Research Institute of Petroleum & Chemical Industry, China Petroleum & Chemical Corporation; the second hydrogenation catalyst is the HDO-18 catalyst developed by the Dalian Research Institute of Petroleum & Chemical Industry, China Petroleum & Chemical Corporation; the properties of the ortho-formation catalysts are as follows: cloverleaf shape, dimensions (1.4–1.8) × (3–8); Pt content 0.35 wt%, La content 0.05 wt%, and bulk density 0.68 g / cm³. 3 Specific surface area is 220m² 2 / g, pore volume is 0.33mL / g.

[0064] Example 1

[0065] use Figure 1The process flow treats a liquefied gas feedstock, wherein the liquid phase seventh stream from the normalization separation unit is entirely recycled back to the first separation unit, and the twelfth overhead stream from the third separation unit is fed to the normalization unit for treatment. The operating conditions of the first separation unit are: a column bottom temperature of 106°C, and a column top pressure of 1.1 MPa; the operating conditions of the second separation unit are: a column bottom temperature of 50°C, and a column top pressure of 0.7 MPa; the operating conditions of the first hydrogenation unit are: a reaction temperature of 200°C, a reaction pressure of 2.5 MPa, a hydrogen / oil volume ratio of 400:1, and a liquid feed volume space velocity of 1.5 h -1 -1; the operating conditions of the second hydrogenation unit are: a reaction temperature of 225°C, a reaction pressure of 3.1 MPa, a hydrogen / oil volume ratio of 580:1, and a liquid feed volume space velocity of 2.0 h -1 -1; the operating conditions of the normalization unit are: a reaction temperature of 360°C, a reaction pressure of 1.8 MPa, a hydrogen / oil volume ratio of 300:1, and a liquid feed volume space velocity of 0.5 h -1 -1. The operating conditions of the heavy removal column are: a column top pressure of 1.15 MPa, and a column bottom temperature of 102°C. The operating conditions of the third separation unit are: a column top pressure of 0.6 MPa, and a column bottom temperature of 78°C. The n-butane yield is 95.47 wt%, which is the amount of n-butane / the amount of liquefied gas feedstock, and the olefin content in the n-butane product is <0.01 wt%.

[0066] Example 2

[0067] The operating conditions of the first separation unit are: a column bottom temperature of 90°C, and a column top pressure of 2.2 MPa; the operating conditions of the second separation unit are: a column bottom temperature of 110°C, and a column top pressure of 1.0 MPa; the operating conditions of the first hydrogenation unit are: a reaction temperature of 260°C, a reaction pressure of 3.3 MPa, a hydrogen / oil volume ratio of 300:1, and a liquid feed volume space velocity of 5.0 h -1 -1; the operating conditions of the second hydrogenation unit are: a reaction temperature of 200°C, a reaction pressure of 4.2 MPa, a hydrogen / oil volume ratio of 400:1, and a liquid feed volume space velocity of 4.9 h -1 -1; the operating conditions of the normalization unit are: a reaction temperature of 400°C, a reaction pressure of 3.4 MPa, a hydrogen / oil volume ratio of 80:1, and a liquid feed volume space velocity of 2.5 h -1 -1. The operating conditions of the heavy removal column are: a column top pressure of 1.4 MPa, and a column bottom temperature of 110°C. The operating conditions of the third separation unit are: a column top pressure of 1.0 MPa, and a column bottom temperature of 90°C. The n-butane yield is 92.92 wt%, and the olefin content in the n-butane product is <0.01 wt%.

[0068] Example 3

[0069] The same as example 1, except that the operating conditions of the first separation unit are: column bottom temperature 110℃, column top pressure 1.6MPa; the operating conditions of the second separation unit are: column bottom temperature 80℃, column top pressure 0.3MPa; the operating conditions of the first hydrogenation unit are: reaction temperature 230℃, reaction pressure 4.2MPa, hydrogen / oil volume ratio 600:1, liquid feed volume space velocity 2.9h -1 ; the operating conditions of the second hydrogenation unit are: reaction temperature 255℃, reaction pressure 2.5MPa, hydrogen / oil volume ratio 300:1, liquid feed volume space velocity 1.0h -1 ; the operating conditions of the normalization unit are: reaction temperature 320℃, reaction pressure 0.9MPa, hydrogen / oil volume ratio 500:1, liquid feed volume space velocity 1.5h -1 ; the operating conditions of the heavy removal column are: column top pressure 0.7MPa; column bottom temperature 80℃, the operating conditions of the third separation unit are: column top pressure 0.8MPa, column bottom temperature 55℃. The n-butane yield is 93.26wt%, and the olefin content in the n-butane product is <0.01wt%.

[0070] Comparative example 1

[0071] The same as example 1, except that the liquid phase seventh stream obtained from the normalization separation unit is not recycled back to the first separation unit, and the n-butane yield is 54.64wt%.

[0072] Comparative example 2

[0073] The same as example 2, except that the liquid phase seventh stream obtained from the normalization separation unit is not recycled back to the first separation unit, and the column top twelfth stream obtained from the third separation unit is not fed into the normalization unit for treatment, and the n-butane yield is 47.09wt%.

Claims

1. A method for comprehensive utilization of liquefied gas, comprising the following steps: (1) a liquefied gas raw material enters a first separation unit, and after separation, a first overhead stream and a second bottom stream are obtained; (2) the second bottom stream obtained in step (1) enters a second separation unit, and after separation, a third overhead stream and a fourth bottom stream are obtained; (3) the third overhead stream obtained in step (2) enters a first hydrogenation unit, and under the action of hydrogen and a first hydrogenation catalyst, a hydrogenation reaction is carried out to obtain a fifth stream of hydrogenation reaction product; (4) the fifth stream obtained in step (3) enters a normalization unit, and under the action of a normalization catalyst, a reaction is carried out, and after gas-liquid separation of the reaction effluent, a sixth stream of gas phase and a seventh stream of liquid phase are obtained, and the seventh stream of liquid phase is recycled back to the first separation unit and / or the second separation unit; (5) the fourth bottom stream obtained in step (2) enters a second hydrogenation unit, and under the action of hydrogen and a second hydrogenation catalyst, a hydrogenation reaction is carried out, and after gas-liquid separation of the hydrogenation reaction product, an eighth stream of gas phase and a ninth stream of liquid phase are obtained; (6) the ninth stream of liquid phase obtained in step (5) enters a heavy-removal column for separation to obtain a tenth overhead stream and an eleventh bottom stream; (7) the tenth overhead stream obtained in step (6) enters a third separation unit, and after separation, a twelfth overhead stream and a thirteenth bottom stream are obtained, and the thirteenth bottom stream is a n-butane product; the liquefied gas raw material is derived from one or more of refinery atmospheric-vacuum unit by-product gas, catalytic cracking unit by-product gas, reforming unit by-product gas, hydrocracking unit by-product gas, coking unit by-product gas, ethylene plant cracking gas, MTO device by-product gas, oilfield associated gas, and natural gas field associated gas; the operating conditions of the first separation unit are controlled as follows: the overhead pressure is 0.8-3.5 MPa, and the column bottom temperature is 80-160 ℃; the operating conditions of the second separation unit are controlled as follows: the overhead pressure is 0.2-2.5 MPa, and the column bottom temperature is 40-150 ℃; the normalization catalyst is a supported noble metal catalyst, comprising a carrier, an active component, and an additive; the active component is one or more of Pt, Pd, Ru, Rh, and Ir; the carrier is one or a combination of several of alumina, silica, amorphous silica-alumina, and molecular sieve; and the additive is one or more of Group VIII transition metal and rare earth metal; the operating conditions of the first separation unit in step (1) are controlled as follows: the overhead pressure is 1.1-2.2 MPa, and the column bottom temperature is 90-110 ℃; the operating conditions of the second separation unit in step (2) are controlled as follows: the overhead pressure is 0.3-1 MPa, and the column bottom temperature is 50-110 ℃; the normalization catalyst is a supported noble metal catalyst, comprising a carrier, an active component, and an additive; the active component is one or more of Pt and Pd; and the molecular sieve is at least one of ZSM-5, ZSM-11, ZSM-22, Y molecular sieve, and β molecular sieve; the sixth stream of gas phase obtained after gas-liquid separation of the normalization reaction effluent in step (4) is recycled back to the first hydrogenation unit and / or the second hydrogenation unit. ​ ​ ​ ​ ​ ​ ​ wherein, ​ ​ ​ 2. The comprehensive utilization method of liquefied gas according to claim 1, characterized by: ​ 3. The comprehensive utilization method of liquefied gas according to claim 1, characterized by: ​ 4. The comprehensive utilization method of liquefied gas according to claim 1, characterized by: The operating conditions of the first hydrogenation unit in step (3) are as follows: the reaction temperature is 100-350°C, the reaction pressure is 1.0-6.0 MPa, the volume space velocity is 0.5-10 h -1 -1, and the hydrogen / oil volume ratio is 100:1-1000:

1.

5. The comprehensive utilization method of liquefied gas according to claim 1 or 4, characterized by: The operating conditions of the first hydrogenation unit in step (3) are as follows: the reaction temperature is 200-260°C, the reaction pressure is 2.5-4.2 MPa, the volume space velocity is 1.0-5.0 h -1 , and the hydrogen / oil volume ratio is 300:1-600:

1.

6. The comprehensive utilization method of liquefied gas according to claim 1, characterized by: The operating conditions of the normal-forming unit in step (4) are as follows: reaction temperature 200-500°C, reaction pressure 0.5-5 MPa, hydrogen / oil volume ratio 10:1-1000:1, and volume space velocity 0.1-5 h -1 .

7. The comprehensive utilization method of liquefied gas according to claim 1 or 6, characterized by: The operating conditions of the normal-forming unit in step (4) are as follows: reaction temperature 300-400°C, reaction pressure 0.8-3.5 MPa, hydrogen / oil volume ratio 30:1-500:1, and volume space velocity 0.5-3 h -1 .

8. The comprehensive utilization method of liquefied gas according to claim 1, characterized by: ​ 9. The comprehensive utilization method of liquefied gas according to claim 1, characterized by: ​ 10. The comprehensive utilization method of liquefied gas according to claim 1, characterized by: The operating conditions of the second hydrogenation unit in step (5) are as follows: reaction temperature 100-350°C, reaction pressure 1.0-6.0 MPa, volume space velocity 0.5-10 h -1 -1, and hydrogen to oil volume ratio 100:1-1000:

1.

11. The comprehensive utilization method of liquefied gas according to claim 1 or 10, characterized by: The operating conditions of the second hydrogenation unit in step (5) are as follows: the reaction temperature is 200-260°C, the reaction pressure is 2.5-4.2 MPa, the volume space velocity is 1.0-5.0 h -1 , and the hydrogen / oil volume ratio is 300:1-600:

1.

12. The comprehensive utilization method of liquefied gas according to claim 1, characterized in that: The gaseous eighth stream obtained after gas-liquid separation of the hydrogenation reaction product in step (5) is subjected to optional purification treatment and used as recycle hydrogen.

13. The comprehensive utilization method of liquefied gas according to claim 1, characterized in that: The operating conditions of the depropanizer in step (6) are as follows: the column top pressure is 0.3-2.5 MPa, and the column bottom temperature is 60-180°C.

14. The comprehensive utilization method of liquefied gas according to claim 1 or 13, characterized by: The operating conditions of the depropanizer in step (6) are as follows: the column top pressure is 0.6-1.5 MPa, and the column bottom temperature is 80-110°C.

15. The comprehensive utilization method of liquefied gas according to claim 1, characterized in that: The twelfth stream obtained after separation in step (7) is fed into the normalization unit for treatment.

16. The comprehensive utilization method of liquefied gas according to claim 1, characterized in that: The operating conditions of the third separation unit in step (7) are as follows: the column top pressure is 0.5-1.5 MPa, and the column bottom temperature is 40-120°C.

17. The comprehensive utilization method of liquefied gas according to claim 1 or 16, characterized by: The operating conditions of the third separation unit in step (7) are as follows: the column top pressure is 0.6-1.0 MPa, and the column bottom temperature is 50-90°C.

18. A liquefied gas comprehensive utilization system, comprising: a first separation unit for receiving and separating a liquefied gas raw material, and obtaining a first stream at the column top and a second stream at the column bottom after separation; a second separation unit for receiving and separating the second stream at the column bottom from the first separation unit, and obtaining a third stream at the column top and a fourth stream at the column bottom after separation; a first hydrogenation unit for receiving hydrogen and the third stream at the column top from the second separation unit, and performing hydrogenation reaction under the action of a first hydrogenation catalyst to obtain a fifth stream of hydrogenation reaction product; a normalization unit for receiving the fifth stream of hydrogenation reaction product from the first hydrogenation unit, and performing reaction under the action of a normalization catalyst; a normalization separation unit for receiving the reaction effluent from the normalization unit, and obtaining a sixth stream in gaseous phase and a seventh stream in liquid phase after gas-liquid separation, and recycling the seventh stream in liquid phase back to the first separation unit and / or the second separation unit through a pipeline; a second hydrogenation unit for receiving hydrogen and the fourth stream at the column bottom from the second separation unit, and performing hydrogenation reaction under the action of a second hydrogenation catalyst; a hydrogenation separation unit for receiving the hydrogenation reaction product from the second hydrogenation unit, and obtaining an eighth stream in gaseous phase and a ninth stream in liquid phase after gas-liquid separation; a depropanizer for receiving the ninth stream in liquid phase from the hydrogenation separation unit, and obtaining a tenth stream at the column top and an eleventh stream at the column bottom after separation of the ninth stream in liquid phase into the depropanizer; a third separation unit for receiving the tenth stream at the column top from the depropanizer, and obtaining a twelfth stream at the column top and a thirteenth stream at the column bottom after separation, wherein the thirteenth stream at the column bottom is a normal butane product.

19. The integrated liquefied gas utilization system according to claim 18, characterized by: The normalization unit is provided with at least one reactor, and the reactor is one or more of a fixed bed reactor, a moving bed reactor and a fluidized bed reactor.

20. The integrated liquefied gas utilization system according to claim 19, characterized by: The reactor is a fixed bed reactor.

21. The integrated liquefied gas utilization system according to claim 18, characterized by: The first separation unit is a rectifying column, and the rectifying column is any one of a plate column and a packed column.

22. The integrated liquefied gas utilization system according to claim 18, characterized by: The second separation unit is a rectifying column, and the rectifying column is any one of a plate column and a packed column.

23. The integrated liquefied gas utilization system according to claim 18, characterized by: The third separation unit is a rectifying column, and the rectifying column is any one of a plate column and a packed column.

24. The integrated liquefied gas utilization system according to claim 18, characterized by: The sixth stream in gaseous phase obtained after separation of the normalization separation unit is recycled back to the first hydrogenation unit and / or the second hydrogenation unit as recycle hydrogen.

25. The comprehensive utilization system of liquefied gas according to claim 18 or 24, characterized by: The gaseous sixth stream separated in the normal paraffinization separation unit is recycled back to the first hydrogenation unit and / or the second hydrogenation unit after being purified.

26. The integrated liquefied gas utilization system according to claim 18, characterized by: The twelfth overhead stream from the third separation unit is passed to the normal paraffinization unit for processing.

27. The integrated liquefied gas utilization system according to claim 18, characterized by: The gaseous eighth stream from the hydrogenation separation unit is used as recycle hydrogen after being optionally purified and recycled back to the first hydrogenation unit and / or the second hydrogenation unit via line.

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