A catalytic cracking product separation device and separation method

Abstract

The invention discloses a catalytic cracking product separation device, which belongs to the field of petroleum refining. In the device, the top outlet of the fractionation tower, the top outlet of the water washing tower, the first gas compressor, the top outlet of the front depropanizer, the second gas compressor, the top outlet of the front deethanizer, and the first inlet of the absorption tower are connected in sequence through pipelines; the bottom outlet of the front depropanizer is connected to the inlet of the rear depropanizer, and the bottom outlet of the water washing tower and the bottom outlet of the rear depropanizer are both connected to the inlet of the desorption tower through pipelines; the bottom outlet of the desorption tower, the bottom outlet of the debutanizer, and the depentanizer are connected in sequence through pipelines; the bottom outlet of the front deethanizer, the top outlet of the rear deethanizer, and the inlet of the ethylene distillation tower are connected in sequence through pipelines; the bottom outlet of the front deethanizer, the bottom outlet of the rear deethanizer, and the propylene distillation tower are connected in sequence through pipelines. The device can effectively separate the various components in the catalytic cracking product.

Description

Technical Field

[0001] The invention relates to the field of petroleum refining, and in particular to a catalytic cracking product separation device and a separation method. Background Art

[0002] Catalytic cracking is the process of producing low-carbon olefins such as ethylene, propylene, and butene by high-temperature cracking of petroleum hydrocarbons in the presence of a catalyst, and simultaneously producing light aromatics. Catalytic cracking products include: ethylene, propylene, C4, C5, light aromatics, light cracking oil, heavy cracking oil, etc. Therefore, it is necessary to separate these different types of products.

[0003] The related technology provides a method for recovering carbon two components in catalytic cracking dry gas using shallow cooling oil and medium cooling oil, which is mainly used to separate carbon two components in catalytic cracking products.

[0004] In the process of implementing the present invention, the inventors found that there are at least the following problems in the prior art:

[0005] The related technology only separates the carbon two components from the catalytic cracking products, but does not provide effective separation measures for other components in the catalytic cracking products. Summary of the invention

[0006] In view of this, the present invention provides a catalytic cracking product separation device and separation method, which can solve the above technical problems.

[0007] Specifically, the following technical solutions are included:

[0008] On the one hand, a catalytic cracking product separation device is provided, the separation device comprising: a fractionation tower, a water washing tower, a first gas compressor, a front depropanizer, a rear depropanizer, a desorption tower, a debutanizer, a depentanizer, a second gas compressor, a front deethanizer, a rear deethanizer, a propylene distillation tower, an ethylene distillation tower, and an absorption tower;

[0009] The top outlet of the fractionation tower, the top outlet of the water scrubber, the first gas compressor, the top outlet of the front depropanizer, the second gas compressor, the top outlet of the front deethanizer, and the first inlet of the absorption tower are connected in sequence through pipelines;

[0010] The bottom outlet of the front depropanizer is connected to the inlet of the rear depropanizer, and the bottom outlet of the water scrubber and the bottom outlet of the rear depropanizer are both connected to the inlet of the desorption tower through a pipeline;

[0011] The bottom outlet of the desorption tower, the bottom outlet of the debutanizer, and the depentanizer are connected in sequence through pipelines;

[0012] The bottom outlet of the front deethanizer, the top outlet of the rear deethanizer, and the inlet of the ethylene distillation tower are connected in sequence through pipelines;

[0013] The bottom outlet of the front deethanizer, the bottom outlet of the rear deethanizer, and the propylene distillation tower are connected in sequence through pipelines.

[0014] In a possible implementation, the bottom outlet of the absorption tower is connected to the inlet of the desorption tower through a pipeline;

[0015] The depentanizer has a lean absorption oil outlet, and the lean absorption oil outlet is communicated with the second inlet of the absorption tower.

[0016] In a possible implementation, the condensate outlet of the first gas compressor is connected to the inlet of the desorption tower through a pipeline.

[0017] In a possible implementation, the catalytic cracking product separation device further includes: a pre-processor, which is located between the first gas compressor and the front depropanizer and is used to remove oxides, acid gases and moisture from the compressed oil and gas.

[0018] On the other hand, an embodiment of the present invention further provides a method for separating catalytic cracking products, wherein the method for separating catalytic cracking products adopts any one of the above-mentioned catalytic cracking product separation devices.

[0019] In a possible implementation, the separation method includes:

[0020] The catalytic cracking product is fractionated in a fractionation tower to obtain heavy cracking oil, light cracking oil, and the first oil and gas component;

[0021] The first oil and gas component enters the water washing tower from the top outlet of the fractionation tower for oil and gas separation, and the second oil and gas component at the top of the water washing tower is pressurized by the first air compressor and then enters the front depropanizer for treatment;

[0022] The top component of the front de-propanizer is pressurized by the second gas compressor and then enters the front de-ethanizer for processing. The top component of the front de-ethanizer enters the absorption tower, and the carbon three components are recovered from the lean absorption oil. The top dry gas of the absorption tower is sent to the downstream processing device; the bottom component of the front de-ethanizer enters the rear de-ethanizer for separation, and the top carbon two components of the rear de-ethanizer enter the ethylene distillation tower to complete the separation of ethylene and ethane; the bottom carbon three components of the rear de-ethanizer enter the propylene distillation tower to complete the separation of propylene and propane;

[0023] The bottom components of the front depropanizer enter the rear depropanizer for separation of C3 components and C4 components. The bottom components of the rear depropanizer and the bottom components of the water washing tower are successively passed through the desorption tower, debutanizer and depentanizer to complete the separation of mixed C4 components, C5 components and lean absorption oil.

[0024] In a possible implementation, the separation method includes:

[0025] The rich absorption oil at the bottom of the absorption tower is sequentially passed through a desorption tower, a debutanizer, and a depentanizer to regenerate lean absorption oil;

[0026] The lean absorption oil enters the absorption tower for recycling.

[0027] In a possible implementation, the lean absorption oil is aromatic gasoline.

[0028] In a possible implementation, the interstage condensate of the first gas compressor is passed through a desorption tower, a debutanizer tower, and a depentanizer tower together with the bottom components of the post-depropanizer tower and the bottom components of the water washing tower to complete the separation of the mixed C4 component, C5 component, and lean absorption oil.

[0029] In a possible implementation, the second oil and gas component at the top of the water washing tower is pressurized by the first gas compressor, and then removed from the oxides, acid gas and water by a pre-treatment device, and then enters the pre-depropanizer for treatment;

[0030] The pre-processor is located between the first gas compressor and the front depropanizer, and is used to remove oxides, acid gases and moisture from the compressed oil and gas.

[0031] The beneficial effects of the technical solution provided by the embodiment of the present invention include at least:

[0032] The catalytic cracking product separation device provided in the embodiment of the present invention can realize the non-clear separation of carbon 2 and carbon 3 by connecting the top outlet of the fractionation tower, the top outlet of the water washing tower, the first gas compressor, the top outlet of the front de-propanizer, the second gas compressor, the top outlet of the front de-ethanizer, and the first inlet of the absorption tower in sequence through pipelines; by connecting the bottom outlet of the front de-propanizer with the inlet of the rear de-propanizer, the clear separation of carbon 3 and carbon 4 components is completed; by connecting the bottom outlet of the front de-ethanizer and the top outlet of the rear de-ethanizer, the The inlet of the desorber is connected to the inlet of the ethylene distillation tower through a pipeline in sequence to complete the separation of ethylene and ethane; the bottom outlet of the front deethanizer, the bottom outlet of the rear deethanizer, and the propylene distillation tower are connected in sequence through a pipeline to complete the separation of propylene and propane; the bottom outlet of the water scrubber and the bottom outlet of the rear depropanizer are connected to the inlet of the desorber through a pipeline, and the bottom outlet of the desorber, the bottom outlet of the debutanizer, and the depentanizer are connected in sequence through a pipeline to complete the separation of the mixed carbon four component, the carbon five component, and the lean absorption oil. In this way, the device provided by the embodiment of the present invention can effectively separate the various components in the catalytic cracking product. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 A schematic structural diagram of a catalytic cracking product separation device provided in an embodiment of the present invention.

[0035] The reference numerals represent:

[0036] 1- fractionation tower, 2- water washing tower, 3- first gas compressor, 4- front depropanizer,

[0037] 5-post-depropanizer, 6-desorption tower, 7-debutanizer, 8-depentanizer,

[0038] 9- the second gas compressor, 10- the front deethanizer, 11- the rear deethanizer,

[0039] 12-propylene distillation tower, 13-ethylene distillation tower, 14-absorption tower, 15-pretreatment tower. DETAILED DESCRIPTION

[0040] To make the technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0041] On the one hand, an embodiment of the present invention provides a catalytic cracking product separation device, as shown in the attached Figure 1 As shown, the catalytic cracking product separation device includes: a distillation tower 1, a water washing tower 2, a first gas compressor 3, a front depropanizer 4, a rear depropanizer 5, a desorption tower 6, a debutanizer 7, a depentanizer 8, a second gas compressor 9, a front deethanizer 10, a rear deethanizer 11, a propylene distillation tower 12, an ethylene distillation tower 13, and an absorption tower 14.

[0042] Among them, the top outlet of the distillation tower 1, the top outlet of the water washing tower 2, the first gas compressor 3, the top outlet of the front depropanizer 4, the second gas compressor 9, the top outlet of the front deethanizer 10, and the first inlet (i.e., the raw material inlet) of the absorption tower 14 are connected in sequence through pipelines.

[0043] The bottom outlet of the front depropanizer 4 is connected to the inlet of the rear depropanizer 5, and the bottom outlet of the water scrubber 2 and the bottom outlet of the rear depropanizer 5 are both connected to the inlet of the desorption tower 6 through pipelines.

[0044] The bottom outlet of the desorption tower 6, the bottom outlet of the debutanizer 7, and the depentanizer 8 are connected in sequence through pipelines.

[0045] The bottom outlet of the front deethanizer 10, the top outlet of the rear deethanizer 11, and the inlet of the ethylene distillation tower 13 are connected in sequence through pipelines.

[0046] The bottom outlet of the front deethanizer 10, the bottom outlet of the rear deethanizer 11, and the propylene distillation tower 12 are connected in sequence through pipelines.

[0047] The working principle of the catalytic cracking product separation device provided in the embodiment of the present invention is described below:

[0048] The catalytic cracking product is fractionated in the fractionation tower 1, and the heavy cracking oil is separated at the bottom of the fractionation tower 1, the light cracking oil is separated in the middle of the fractionation tower 1, and the first oil and gas component is separated at the top of the fractionation tower 1. The first oil and gas component enters the water washing tower 2 from the top outlet of the fractionation tower 1 for oil and gas separation. The second oil and gas component in the first oil and gas component, mainly gasoline and water vapor condensed water, is separated and extracted at the bottom of the water washing tower 2. The second oil and gas component at the top of the water washing tower 2 is pressurized by the first gas compressor 3 and enters the front depropanizer 4 for treatment. The top component of the front depropanizer 4 is pressurized by the second gas compressor 9 and enters the front deethanizer 10 for treatment. The top component of the front deethanizer 10 enters the absorption tower 14, and the carbon three component is recovered from the lean absorption oil in the absorption tower 14. The top dry gas of the absorption tower 14 is sent to the downstream processing device. The bottom components of the front deethanizer 10 enter the rear deethanizer 11 for separation, and the top carbon two components of the rear deethanizer 11 enter the ethylene distillation tower 13 to complete the separation of ethylene and ethane; the bottom carbon three components of the rear deethanizer 11 enter the propylene distillation tower 12 to complete the separation of propylene and propane.

[0049] The bottom components of the front depropanizer 4 enter the rear depropanizer 5 to separate the C3 component and the C4 component. After the top oil and gas of the rear depropanizer 5 are all condensed and cooled, part of them return to the top of the rear depropanizer 5 as cold reflux, and part of them return to the top of the front depropanizer 4. The bottom components of the rear depropanizer 5 and the bottom components of the water washing tower 2 are sequentially passed through the desorption tower 6, the debutanizer 7, and the depentanizer 8 to complete the separation of the mixed C4 component, the C5 component, and the lean absorption oil. Among them, the mixed C4 component is extracted from the debutanizer 7, and the C5 component and the lean absorption oil are extracted from different positions of the depentanizer 8.

[0050] It can be seen that the catalytic cracking product separation device provided in the embodiment of the present invention can realize the non-clear separation of carbon 2 and carbon 3 by connecting the top outlet of the distillation tower 1, the top outlet of the water washing tower 2, the first gas compressor 3, the top outlet of the front de-propanizer 4, the second gas compressor 9, the top outlet of the front de-ethanizer 10, and the first inlet of the absorption tower 14 in sequence through pipelines; by connecting the bottom outlet of the front de-propanizer 4 with the inlet of the rear de-propanizer 5, the clear separation of carbon 3 and carbon 4 components is completed; by connecting the bottom outlet of the front de-ethanizer 10 and the inlet of the rear de-ethanizer 11, the bottom outlet of the front de-ethanizer 10 and the inlet of the rear de-ethanizer 11 are connected. The top outlet and the inlet of the ethylene distillation tower 13 are connected in sequence through pipelines to complete the separation of ethylene and ethane; the bottom outlet of the front deethanizer 10, the bottom outlet of the rear deethanizer 11, and the propylene distillation tower 12 are connected in sequence through pipelines to complete the separation of propylene and propane; the bottom outlet of the water scrubber 2 and the bottom outlet of the rear depropanizer 5 are connected to the inlet of the desorber 6 through pipelines, and the bottom outlet of the desorber 6, the bottom outlet of the debutanizer 7, and the depentanizer 8 are connected in sequence through pipelines to complete the separation of the mixed carbon four components, carbon five components, and lean absorption oil. In this way, the device provided by the embodiment of the present invention can effectively separate the various components in the catalytic cracking product.

[0051] Furthermore, as attached Figure 1 As shown, in the catalytic cracking product separation device provided in an embodiment of the present invention, the bottom outlet of the absorption tower 14 is connected to the inlet of the desorption tower 6 through a pipeline; the depentanizer 8 has a lean absorption oil outlet, which is connected to the second inlet of the absorption tower 14.

[0052] The top component of the front deethanizer 10 enters the absorption tower 14, and the carbon three components are recovered from the lean absorption oil in the absorption tower 14. The top dry gas of the absorption tower 14 is sent to the downstream processing device, and the lean absorption oil that absorbs the carbon three components in the absorption tower 14 becomes rich absorption oil. Since the bottom outlet of the absorption tower 14 is connected to the inlet of the desorber 6 through a pipeline, the rich absorption oil at the bottom of the absorption tower 14 passes through the desorber 6, the debutanizer 7, and the depentanizer 8 in turn to regenerate the lean absorption oil, and the carbon three components therein are further separated. Since the lean absorption oil outlet of the depentanizer 8 is connected to the second inlet of the absorption tower 14, the lean absorption oil enters the absorption tower 14 and is recycled.

[0053] In the embodiment of the present invention, the lean absorption oil used is aromatic gasoline.

[0054] Furthermore, as attached Figure 1 As shown, in the catalytic cracking product separation device provided in the embodiment of the present invention, the condensate outlet of the first gas compressor 3 is connected to the inlet of the desorption tower 6 through a pipeline.

[0055] In this way, the interstage condensate of the first gas compressor 3 is then removed from the bottom components of the propanizer 5 and the bottom components of the water washing tower 2 through the desorption tower 6, the debutanizer 7, and the depentanizer 8, thereby completing the separation of the mixed C4 component, C5 component, and lean absorption oil, which is beneficial to improving the recovery efficiency.

[0056] Furthermore, as attached Figure 1 As shown, the catalytic cracking product separation device provided in the embodiment of the present invention also includes: a pre-processor 15, which is located between the first gas compressor 3 and the front depropanizer 4 and is used to remove oxides, acid gases and moisture from the compressed oil and gas, that is, the second oil and gas component.

[0057] By means of the above arrangement, before the second oil and gas component enters the front depropanizer 4, the pre-processor 15 is used to remove oxides, acid gases and moisture therein, which is beneficial to improving the subsequent separation efficiency.

[0058] Based on any of the catalytic cracking product separation devices mentioned above, an embodiment of the present invention further provides a catalytic cracking product separation method, and the catalytic cracking product separation method adopts any of the catalytic cracking product separation devices mentioned above.

[0059] In a possible implementation, an embodiment of the present invention provides a method for separating catalytic cracking products, the method comprising:

[0060] The catalytic cracking product is fractionated in a fractionation tower 1 to obtain heavy cracking oil, light cracking oil, and a first oil and gas component.

[0061] The top outlet of the distillation tower 1, the top outlet of the water washing tower 2, the first gas compressor 3, the top outlet of the front depropanizer 4, the second gas compressor 9, the top outlet of the front deethanizer 10, and the first inlet (i.e., the raw material inlet) of the absorption tower 14 are connected in sequence through pipelines.

[0062] In this way, the first oil and gas component enters the water washing tower 2 from the top outlet of the distillation tower 1 for oil and gas separation, the second oil and gas component at the top of the water washing tower 2 is pressurized by the first gas compressor 3, and then enters the pre-depropanizer 4 for treatment; the top component of the pre-depropanizer 4 is pressurized by the second gas compressor 9, and then enters the pre-deethanizer 10 for treatment, the top component of the pre-deethanizer 10 enters the absorption tower 14, and the carbon three component is recovered from the lean absorption oil, and the top dry gas of the absorption tower 14 is sent to the downstream processing device.

[0063] The second oil and gas component at the top of the water washing tower 2 is pressurized to 1.0Mpa-2.0Mpa by the first gas compressor 3. The top component of the front depropanizer 4 is pressurized to 2.0Mpa-4.0Mpa by the second gas compressor 9 to obtain high separation efficiency.

[0064] Since the bottom outlet of the front depropanizer 4 is connected with the inlet of the rear depropanizer 5, and the bottom outlet of the water scrubber 2 and the bottom outlet of the rear depropanizer 5 are connected with the inlet of the desorber 6 through pipelines, and the bottom outlet of the desorber 6, the bottom outlet of the debutanizer 7, and the depentanizer 8 are sequentially connected through pipelines. In this way, the bottom components of the front depropanizer 4 enter the rear depropanizer 5 for separation of C3 components and C4 components, and the bottom components of the rear depropanizer 5 and the bottom components of the water scrubber 2 are sequentially passed through the desorber 6, the debutanizer 7, and the depentanizer 8 to complete the separation of the mixed C4 components, the C5 components, and the lean absorption oil.

[0065] Since the bottom outlet of the front deethanizer 10, the top outlet of the rear deethanizer 11, and the inlet of the ethylene distillation tower 13 are connected in sequence through pipelines, the bottom outlet of the front deethanizer 10, the bottom outlet of the rear deethanizer 11, and the propylene distillation tower 12 are connected in sequence through pipelines, in this way, the bottom components of the front deethanizer 10 enter the rear deethanizer 11 for separation, the top carbon two components of the rear deethanizer 11 enter the ethylene distillation tower 13 to complete the separation of ethylene and ethane; the bottom carbon three components of the rear deethanizer 11 enter the propylene distillation tower 12 to complete the separation of propylene and propane.

[0066] It can be seen that the device provided by the embodiment of the present invention can effectively separate the various components in the catalytic cracking product.

[0067] Furthermore, in the catalytic cracking product separation device provided in the embodiment of the present invention, the bottom outlet of the absorption tower 14 is connected to the inlet of the desorption tower 6 through a pipeline; the depentanizer 8 has a lean absorption oil outlet, which is connected to the second inlet of the absorption tower 14.

[0068] Thus, the catalytic cracking product separation method provided by the embodiment of the present invention further includes: the rich absorption oil at the bottom of the absorption tower 14 is successively passed through the desorption tower 6, the debutanizer 7, and the depentanizer 8 to regenerate the lean absorption oil; the lean absorption oil enters the absorption tower 14 for recycling.

[0069] As an example, the lean absorption oil is aromatic gasoline.

[0070] In the embodiment of the present invention, the amount of aromatic gasoline is adjusted according to the requirements of the downstream processing device for the content of carbon three components in the top dry gas of the absorption tower 14, and the rich absorption oil at the bottom of the absorption tower 14 is returned to the desorption tower 6, the debutanizer 7, and the depentanizer 8 for regeneration.

[0071] The temperature of the lean absorption oil when entering the absorption tower 14 is higher than -40°C, and two, three or more intercoolers may be arranged inside the absorption tower 14, and the cooling temperature of the intercooler is higher than -40°C to ensure a good absorption effect.

[0072] Since the condensate outlet of the first gas compressor 3 is connected to the inlet of the desorption tower 6 through a pipeline, the interstage condensate of the first gas compressor 3 is then removed from the bottom components of the propanizer 5 and the bottom components of the water washing tower 2 through the desorption tower 6, the debutanizer 7, and the depentanizer 8 to complete the separation of the mixed C4 component, C5 component, and lean absorption oil.

[0073] In a possible implementation, the second oil and gas component at the top of the water washing tower 2 is pressurized by the first gas compressor 3, and then removed from the oxides, acid gases and moisture by the pre-treatment unit 15, and then enters the front depropanizer 4 for treatment, wherein the pre-treatment unit 15 is located between the first gas compressor 3 and the front depropanizer 4, and is used to remove oxides, acid gases and moisture from the compressed oil and gas.

[0074] In the embodiment of the present invention, the operating pressure range of the front depropanizer 4 is 1.0Mpa-2.0Mpa, and the volume content of C4 and above components in the top oil and gas components of the front depropanizer 4 is 0%-5%.

[0075] In the embodiment of the present invention, the operating pressure range of the post-depropanizer 5 is 0.4Mpa to 0.8Mpa.

[0076] The mixed C4 components are separated by the debutanizer 7, wherein the mixed C4 components can be directly returned to the catalytic cracking reactor for recycling, or the mixed C4 components can be returned to the catalytic cracking reactor for recycling after butadiene is removed.

[0077] The C5 components are separated by the depentanizer 8, wherein all of the C5 components can be returned to the catalytic cracking reactor for recycling, or part of the C5 components can be returned to the catalytic cracking reactor for recycling.

[0078] In the embodiment of the present invention, the top stream of the post-deethanization tower is the top carbon two component, wherein the top carbon two component is divided into three parts, one part enters the top of the post-deethanization tower 11 as cold reflux, one part returns to the top of the pre-deethanization tower 10 as cold reflux, and the other part enters the ethylene distillation tower 13. Among them, the amount of the top carbon two component entering the ethylene distillation tower 13 is determined by the processing load of the downstream device. The amount of high-purity ethylene obtained by the ethylene distillation tower 13 is 90%-98% of the total amount of ethylene obtained by the catalytic cracking reaction.

[0079] If the top carbon two components of the post-deethanizer 11 contain acetylene, the acetylene needs to be removed before entering the ethylene distillation tower 13;

[0080] If the three carbon components at the bottom of the post-deethanizer 11 contain impurities such as methylacetylene or propadiene, the impurities such as methylacetylene or propadiene in the three carbon components at the bottom of the tower need to be removed before entering the propylene distillation tower 12.

[0081] In a possible implementation, the ethane separated from the bottom of the ethylene distillation tower 13 can be returned to the top of the previous deethanization tower as a cold reflux.

[0082] In a possible implementation, the ethane separated from the bottom of the ethylene distillation tower 13 can be discharged from the device as a product, or can be fully or partially returned to the catalytic cracking reactor for recycling.

[0083] In a possible implementation, the propane separated from the bottom of the propylene distillation tower 12 can be returned to the top of the pre-deethanizer tower 10 as a cold reflux.

[0084] In a possible implementation, the propane separated from the bottom of the propylene distillation tower 12 can be discharged from the device as a product, or can be fully or partially returned to the catalytic cracking reactor for recycling.

[0085] Based on the above, an embodiment of the present invention provides a method for separating a catalytic cracking reaction product, which comprises the following steps:

[0086] The reaction oil and gas comes from the catalytic cracking reactor and enters the bottom of the fractionation tower 1, where heavy cracking oil and light cracking oil are separated from bottom to top. The oil and gas at the top of the fractionation tower 1 enter the water washing tower 2, where they are countercurrently contacted with the circulating washing water to cool down. The condensed crude gasoline and water are separated and extracted separately by settling in the tower kettle. The oil and gas at the top of the water washing tower 2 enter the first air compressor 3 to increase the pressure to 1.0Mpa-2.0Mpa, and undergo pretreatment such as removing oxides, acidic gases, and water.

[0087] The pretreated compressed oil and gas are sent to the front depropanizer 4, which is operated at a pressure of 1.0Mpa-2.0Mpa, and the volume content of carbon four and above components in the oil and gas at the top of the tower is controlled to be 0% to 5%, and the bottom logistics is sent to the rear depropanizer 5 for clear separation of carbon three and carbon four components. The operating pressure range of the rear depropanizer 5 is 0.4Mpa-0.8Mpa, and the volume content of carbon three and below components in the bottom logistics of the tower is controlled to be 0% to 3%.

[0088] The bottom stream of the post-depropanizer 5, the bottom crude gasoline of the water washing tower 2 and the condensate between the air compressor stages are sent to the desorption tower 6 to remove the light components of C3 and below, and then enter the debutanizer 7 and the depentanizer 8 to separate the mixed C4, C5 components and aromatic gasoline. Among them, after separating butadiene from the mixed C4, part or all of it can be returned to the catalytic cracking reactor for recycling, and part or all of the C5 components can be returned to the catalytic cracking reactor for recycling.

[0089] The top oil gas of the front depropanizer 4 is further pressurized to 2.0Mpa-4.0Mpa by the second gas compressor 9 and then sent to the front deethanizer 10, and the volume content of light components such as methane in the bottom flow of the tower is controlled to be 0% to 3%. The top gas of the front deethanizer 10 enters the absorption tower 14, and the aromatic gasoline cooled to above -40°C is used as the absorbent, and two or three intercoolers are set, and the temperature after cooling of the intercooler is higher than -40°C, and the volume content of the top carbon three components of the absorption tower 14 is controlled to be 0% to 3%. The top ethylene-containing dry gas of the absorption tower 14 is sent to the subsequent processing device. The rich absorption oil at the bottom of the absorption tower 14 is sent to the desorption tower 6, and after the light components are removed by the debutanizer 7 and the depentanizer 8, it returns to the absorption tower 14 for recycling.

[0090] The bottom stream of the front deethanizer 10 enters the rear deethanizer 11 to complete the separation of carbon two and carbon three. The top stream of the rear deethanizer 11 is divided into three parts, one part enters the top of the rear deethanizer 11 as cold reflux, one part returns to the top of the front deethanizer 10 as cold reflux, and the other part enters the ethylene distillation tower 13 to complete the separation of ethylene and ethane, so as to obtain ethylene and ethane products of required concentrations.

[0091] The bottom stream of the post-deethanizer 11 enters the propylene distillation tower 12 to complete the separation of propylene and propane, and obtain propylene and propane products with the required concentration. The above-mentioned ethylene and propylene are used as product delivery devices, and ethane and propane can be used as product delivery devices, or returned to the catalytic cracking reactor for recycling, or returned to the top of the pre-deethanizer 10 as the top cold reflux of the tower.

[0092] If the top stream of the post-deethanizer 11 contains acetylene, the acetylene needs to be removed before entering the ethylene distillation tower 13; if the bottom stream of the post-deethanizer 11 contains impurities such as methylacetylene or propadiene, they need to be removed before entering the propylene distillation tower 12.

[0093] It can be seen that the above process can achieve efficient separation of catalytic cracking reaction products. Part of the ethylene is sent to downstream devices in the form of ethylene-containing dry gas, such as a dry gas to ethylbenzene device for further processing, and the other part is sent to downstream devices in the form of high-purity ethylene for processing or sold as a product, thereby achieving flexible processing of products of different grades. The ethane, propane, mixed C4 and C5 components separated in this process can be sold as products or returned to the catalytic cracking reactor for refining to increase the yield of the target products ethylene and propylene. The embodiment of the present invention does not use cryogenic separation related equipment, which reduces equipment investment, has low energy consumption, simple operation and maintenance, and is safe and reliable.

[0094] The present invention is further described below by specific examples:

[0095] The oil and gas composition (dry basis) at the outlet of a catalytic cracking unit reactor is shown in Table 1, and the separation process is shown in the attached figure. Figure 1 shown.

[0096] Table 1

[0097] Components Mass fraction, % Mass flow, kg / h Dry gas 28.51 54978 Liquefied gas 23.63 45560 Gasoline components 16.73 32266 Light pyrolysis oil 20.26 39074 Heavy pyrolysis oil 10.86 20948 total 100 192826 Ethylene 16.59 31995 Of which propylene 13.16 25382

[0098] The reaction oil and gas of a catalytic cracking unit comes from the catalytic cracking reactor and enters the bottom of the fractionation tower 1, where heavy cracking oil and light cracking oil are separated from bottom to top. The oil and gas at the top of the fractionation tower 1 enter the water washing tower 2, where they are countercurrently contacted with the circulating water washing water for cooling. The condensed crude gasoline and water are separated and extracted separately by settling in the tower kettle. The oil and gas at the top of the water washing tower 2 enter the first gas compressor 3, where they are compressed to 1.6Mpa through three stages, and are pre-treated to remove oxides, acidic gases, water, etc.

[0099] The pretreated compressed oil and gas are sent to the front depropanizer 4, which is operated at a pressure of 1.5Mpa, and the volume content of carbon four and above components in the oil and gas at the top of the tower is controlled to be 0.025%, and the bottom logistics is sent to the rear depropanizer 5 for clear separation of carbon three and carbon four components. The operating pressure of the rear depropanizer 5 is 0.7Mpa, and the volume content of carbon three and below components in the bottom logistics of the tower is controlled to be 0.2%.

[0100] The bottom stream of the post-depropanizer 5, the bottom crude gasoline of the water washing tower 2 and the condensate between the compressor stages are sent to the desorption tower 6 to remove the light components of C3 and below, and then enter the debutanizer 7 and the depentanizer 8 to separate the mixed C4, C5 components and aromatic gasoline. Among them, after separating butadiene from the mixed C4, all of them are returned to the catalytic cracking reactor for recycling, and all of the C5 components are returned to the catalytic cracking reactor for recycling.

[0101] The top oil gas of the front depropanizer 4 is further pressurized to 2.4Mpa by the second gas compressor 9 and then sent to the front deethanizer 10, and the volume content of light components such as methane in the bottom flow of the tower is controlled to be 0.05%. The top gas of the front deethanizer 10 enters the absorption tower 14, and the aromatic gasoline cooled to -25°C is used as the absorbent, and two intercoolers are set, and the temperature after cooling of the intercooler is -25°C, and the volume content of the top carbon three components of the absorption tower 14 is controlled to be 1.0%. The dry gas with a volume fraction of 37.7% of ethylene at the top of the absorption tower 14 is sent to the dry gas ethylbenzene production device. The rich absorption oil at the bottom of the absorption tower 14 is sent to the desorption tower 6, and after the light components are removed by the debutanizer 7 and the depentanizer 8, it returns to the absorption tower 14 for recycling.

[0102] The bottom stream of the front deethanizer 10 enters the rear deethanizer 11 to complete the separation of carbon 2 and carbon 3. The top mixed carbon 2 stream of the rear deethanizer 11 is divided into three parts, one part enters the top of the rear deethanizer 11 as cold reflux, one part returns to the top of the front deethanizer 10 as cold reflux, and the other part enters the hydrogenation reactor and is sent to the ethylene distillation tower 13 after acetylene is removed. 8500kg / h of ethylene products with a volume fraction of 99.99% are extracted from the top of the ethylene distillation tower 13, and ethane with a volume fraction of 98% is obtained at the bottom of the tower and sent to the catalytic cracking reactor for recycling.

[0103] The bottom stream of the post-deethanizer 11 enters the deacetylening reactor, and after removing methylacetylene and propadiene, it is sent to the propylene distillation tower 12 to complete the separation of propylene and propane. A propylene product with a volume fraction of 99.6% is obtained at the top of the tower, and a propane with a volume fraction of 95% is obtained at the bottom of the tower, which is sent to the catalytic cracking reactor for recycling.

[0104] The above description is only for the purpose of facilitating those skilled in the art to understand the technical solution of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A catalytic cracking product separation device, characterized in that: The separation device comprises: a fractionation tower, a water washing tower, a first air compressor, a front depropanizer, a rear depropanizer, a desorption tower, a debutanizer, a depentanizer, a second air compressor, a front deethanizer, a rear deethanizer, a propylene distillation tower, an ethylene distillation tower, and an absorption tower; The top outlet of the fractionation tower, the top outlet of the water scrubber, the first gas compressor, the top outlet of the front depropanizer, the second gas compressor, the top outlet of the front deethanizer, and the first inlet of the absorption tower are connected in sequence through pipelines; The bottom outlet of the front depropanizer is connected to the inlet of the rear depropanizer, and the bottom outlet of the water scrubber and the bottom outlet of the rear depropanizer are both connected to the inlet of the desorption tower through a pipeline; The bottom outlet of the desorption tower, the bottom outlet of the debutanizer, and the depentanizer are connected in sequence through pipelines; The bottom outlet of the front deethanizer, the top outlet of the rear deethanizer, and the inlet of the ethylene distillation tower are connected in sequence through pipelines; The bottom outlet of the front deethanizer, the bottom outlet of the rear deethanizer, and the propylene distillation tower are connected in sequence through pipelines; wherein, the top component of the front deethanizer is pressurized by the second gas compressor and then enters the front deethanizer for processing, the top component of the front deethanizer enters the absorption tower, and the carbon three component is recovered by the lean absorption oil, and the top dry gas of the absorption tower is sent to the downstream processing device; the bottom component of the front deethanizer enters the rear deethanizer for separation, the top carbon two component of the rear deethanizer enters the ethylene distillation tower to complete the separation of ethylene and ethane; the bottom carbon three component of the rear deethanizer enters the propylene distillation tower to complete the separation of propylene and propane; The bottom components of the front depropanizer enter the rear depropanizer to separate the C3 component and the C4 component. The front depropanizer is operated at a pressure of 1.0Mpa-2.0Mpa, and the volume content of C4 and above components in the top oil and gas of the tower is controlled to be 0%-5%. After the top oil and gas of the rear depropanizer are all condensed and cooled, a part of them is returned to the top of the rear depropanizer as cold reflux, and a part of them is returned to the top of the front depropanizer. The operating pressure range of the rear depropanizer is 0.4Mpa-0.8Mpa, and the volume content of C3 and below components in the bottom flow of the tower is controlled to be 0%-3%. The bottom components of the rear depropanizer and the bottom components of the water washing tower are sequentially passed through a desorption tower, a debutanizer, and a depentanizer to complete the separation of mixed C4 components, C5 components, and lean absorption oil.

2. The catalytic cracking product separation device according to claim 1, characterized in that: The bottom outlet of the absorption tower is connected to the inlet of the desorption tower through a pipeline; The depentanizer has a lean absorption oil outlet, and the lean absorption oil outlet is communicated with the second inlet of the absorption tower.

3. The catalytic cracking product separation device according to claim 1, characterized in that: The condensate outlet of the first gas compressor is connected to the inlet of the desorption tower through a pipeline.

4. The catalytic cracking product separation device according to claim 1, characterized in that: The catalytic cracking product separation device also includes: a pre-processor, which is located between the first gas compressor and the front depropanizer and is used to remove oxides, acid gases and moisture from the compressed oil and gas.

5. A method for separating catalytic cracking products, characterized in that: The catalytic cracking product separation method adopts the catalytic cracking product separation device according to any one of claims 1-4.

6. The method for separating catalytic cracking products according to claim 5, characterized in that: The separation method comprises: The catalytic cracking product is fractionated in a fractionation tower to obtain heavy cracking oil, light cracking oil, and the first oil and gas component; The first oil and gas component enters the water washing tower from the top outlet of the fractionation tower for oil and gas separation, and the second oil and gas component at the top of the water washing tower is pressurized by the first air compressor and then enters the front depropanizer for treatment; The top component of the front de-propanizer is pressurized by the second gas compressor and then enters the front de-ethanizer for processing. The top component of the front de-ethanizer enters the absorption tower, and the carbon three components are recovered from the lean absorption oil. The top dry gas of the absorption tower is sent to the downstream processing device; the bottom component of the front de-ethanizer enters the rear de-ethanizer for separation, and the top carbon two components of the rear de-ethanizer enter the ethylene distillation tower to complete the separation of ethylene and ethane; the bottom carbon three components of the rear de-ethanizer enter the propylene distillation tower to complete the separation of propylene and propane; The bottom components of the front depropanizer enter the rear depropanizer for separation of C3 components and C4 components. The bottom components of the rear depropanizer and the bottom components of the water washing tower are successively passed through the desorption tower, debutanizer and depentanizer to complete the separation of mixed C4 components, C5 components and lean absorption oil.

7. The method for separating catalytic cracking products according to claim 6, characterized in that: The separation method comprises: The rich absorption oil at the bottom of the absorption tower is sequentially passed through a desorption tower, a debutanizer, and a depentanizer to regenerate lean absorption oil; The lean absorption oil enters the absorption tower for recycling.

8. The method for separating catalytic cracking products according to claim 7, characterized in that: The lean absorption oil is aromatic gasoline.

9. The method for separating catalytic cracking products according to claim 6, characterized in that: The interstage condensate of the first compressor passes through a desorption tower, a debutanizer, and a depentanizer together with the bottom components of the post-depropanizer and the bottom components of the water washing tower to complete the separation of the mixed C4 component, C5 component, and lean absorption oil.

10. The method for separating catalytic cracking products according to claim 6, characterized in that: The second oil and gas component at the top of the water washing tower is pressurized by the first air compressor, and then removed by the pre-treatment device to remove oxides, acid gas and water, and then enters the pre-depropanizer tower for treatment; The pre-processor is located between the first gas compressor and the front depropanizer, and is used to remove oxides, acid gases and moisture from the compressed oil and gas.

Images