A system for taking heat from a cracking oil and gas of a catalytic cracking of crude oil to produce olefins

Abstract

The utility model discloses a kind of cracking oil gas heat extraction systems of crude oil catalytic cracking for olefin reaction, comprising: reactor, catalytic cracking crude oil generates cracking oil gas;Quenching device, the feed inlet of quenching device is communicated with the discharge port of reactor;Quenching oil tower, the discharge port of quenching device is connected;The quenching oil tower is divided into quenching oil section, middle heat exchange section and gasoline section from bottom to top;Quenching oil section is connected with heat exchange device by pipeline, and heavy component of quenching oil section is heat exchanged with heat exchange device;Middle heat exchange section is provided with coil heat exchanger, and the component of quenching tower middle section is heat exchanged with coil heat exchanger;The top of gasoline section is equipped with gasoline component outlet.The utility model is through the combination mode of multistage multistage heat exchange, improves the cooling and heat recovery efficiency of cracking oil gas produced in the top of crude oil catalytic cracking reactor, reduces the waste of heat, improves energy utilization efficiency, also reduces coking problem simultaneously.

Description

Technical Field

[0001] This utility model belongs to the field of petrochemical technology, specifically, it relates to a crude oil catalytic cracking to olefins reaction cracking oil and gas heat extraction system. Background Technology

[0002] In the field of petrochemical technology, crude oil catalytic cracking to olefins is an important emerging crude oil processing technology. This process primarily utilizes a catalyst to break down heavy molecules in crude oil into lighter molecules, thereby producing high-value-added olefin products. However, the viscosity of the quench oil system in the cracked gas process is a significant challenge hindering the safe and stable operation of the unit. The root cause lies in the fact that the quench oil itself contains a large amount of unsaturated heterocyclic compounds such as olefins, dienes, and cycloolefins. At higher temperatures, these compounds undergo free radical condensation, generating larger molecules, leading to increased byproducts, decreased target product yield, and increased viscosity of the cracked gas. Failure to promptly reduce the temperature can also impact and damage the process pipelines and equipment of the production unit. Therefore, efficient heat extraction and cooling of the cracked gas, as well as the effective utilization and recovery of heat, are crucial research directions for crude oil catalytic cracking to olefins units.

[0003] In existing technologies, the catalytic cracking oil and gas produced in crude oil catalytic cracking processes are not cooled and directly enter the fractionation tower, where the heat is removed through internal circulation. Alternatively, a boiler-generated gas scheme is used to cool and remove heat from the top of the crude oil catalytic cracking reactor for olefin production via simple heat exchange. In the fractionation tower (quench tower), an external heat exchanger is used to exchange heat between the components, but its efficiency is also low. Therefore, the heat exchange methods in existing technologies lead to some heat waste, affecting the efficiency of the entire process, and failing to achieve effective heat utilization and recovery, resulting in energy waste and increased production costs.

[0004] Therefore, how to improve existing heat exchange methods, enhance the cooling and heat extraction efficiency of the entire process, and reduce production costs is an urgent problem to be solved in this field.

[0005] In view of this, this utility model is hereby proposed. Utility Model Content

[0006] The technical problem this invention aims to solve is to overcome the low cooling and heat recovery efficiency of cracked oil and gas in existing technologies, and to provide a heat recovery system for cracked oil and gas from crude oil catalytic cracking to olefins production. By combining a quench cooler heat exchanger with a multi-stage heat exchange system in a segmented quench tower, the system improves the cooling and heat recovery efficiency of the cracked oil and gas produced at the top of the crude oil catalytic cracking reactor, reduces heat waste, improves energy utilization efficiency, and also reduces coking.

[0007] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by this utility model is as follows:

[0008] This utility model provides a crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system, comprising:

[0009] The reactor catalytically cracks crude oil to produce cracked oil and gas.

[0010] A quench cooler, the inlet of which is connected to the outlet of the reactor;

[0011] The quench oil tower is connected to the outlet of the quench cooler.

[0012] The quench oil tower is divided into a quench oil section, a middle heat exchange section, and a gasoline section from bottom to top. The quench oil section is connected to the heat exchange device through pipelines, and the heavy components in the quench oil section exchange heat with the heat exchange device. The middle heat exchange section is equipped with a coil heat exchanger, and the components in the middle section of the quench tower exchange heat with the coil heat exchanger. The top of the gasoline section is provided with a gasoline component outlet.

[0013] In a further embodiment, the heat exchange device includes a first steam generator and a second steam generator connected in series. The cold side of the first steam generator is supplied with boiler water and outputs high-pressure steam, while the cold side of the second steam generator is supplied with boiler water and outputs medium-pressure steam.

[0014] In a further embodiment, the heat exchanger's hot-side outlet is divided into a first branch and a second branch. The first branch connects to the feed inlet of the quencher or the inlet of the quench tower, while the second branch returns to the quench oil section.

[0015] In a further embodiment, the heat exchanger's hot-side outlet is divided into a first branch and a second branch via a tee fitting, and a flow regulation mechanism is provided at the branch interface of the tee fitting.

[0016] In a further embodiment, the flow regulating mechanism is an electric proportional valve or a manual butterfly valve, which dynamically controls the flow ratio of the heavy component entering the first branch and the second branch.

[0017] In a further embodiment, the coil heat exchanger includes a spiral coil, through which boiler water is circulated as a refrigerant, and the outer wall of the coil is provided with enhanced heat transfer fins.

[0018] In a further embodiment, the spiral coil has a multi-layer coaxial winding structure, with the coil axis arranged parallel to or inclined to the tower body axis of the quench tower.

[0019] In a further embodiment, the flow direction of the boiler water in the spiral coil is arranged in countercurrent with the flow direction of the oil and gas in the tower.

[0020] In a further embodiment, the middle heat exchange section is also connected to a third steam generator via a circulation pipeline, and the components of the middle heat exchange section are returned to the quench tower after heat exchange in the third steam generator.

[0021] In a further embodiment, boiler water is introduced into the cold side of the third steam generator, and medium-pressure steam is output.

[0022] By adopting the above technical solution, this utility model has the following beneficial effects compared with the prior art:

[0023] 1. Improved Energy Utilization Efficiency: This invention proposes a heat recovery system for crude oil catalytic cracking to olefins feedstock reaction. Through a combination of quench cooler heat exchange and multi-stage heat exchange in a quench tower, it can more effectively cool the reaction-generated oil and gas and recover heat, thereby improving energy utilization efficiency and reducing coking. Compared to existing technologies, this invention can recover more heat under the same operating conditions, reducing heat waste.

[0024] 2. High adaptability: The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system of this utility model can flexibly adjust operating parameters according to different raw materials and operating conditions, making it more adaptable. Compared with the prior art, this utility model can maintain efficient and stable operation in different production environments, improving production flexibility and adaptability.

[0025] 3. Environmental Benefits: The oil and gas heat recovery system for crude oil catalytic cracking to olefins production of this invention reduces energy consumption by optimizing heat recovery and utilization, thus exhibiting significant environmental benefits. Compared to existing technologies, this invention can reduce negative environmental impacts while ensuring production, thereby improving production sustainability.

[0026] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings, as part of this utility model, are used to provide a further understanding of the present utility model. The illustrative embodiments and descriptions of the present utility model are used to explain the present utility model, but do not constitute an undue limitation of the present utility model. Obviously, the drawings described below are merely some embodiments; those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0028] Figure 1 This is a schematic diagram of the crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system of this utility model;

[0029] Among them, 1-reactor, 2-quencher, 3-quench tower, 4-first steam generator, 5-second steam generator, 6-first branch, 7-second branch, 8-third steam generator, 9-tee fitting, 10-gasoline component outlet.

[0030] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0032] In the description of this utility model, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0033] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0034] refer to Figure 1 As shown, this utility model provides a crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system, comprising:

[0035] Reactor 1 catalytically cracks crude oil to produce cracked oil and gas;

[0036] The quench cooler 2 has its inlet connected to the outlet of reactor 1.

[0037] The quench oil tower is connected to the outlet of the quench cooler 2;

[0038] The quench oil tower is divided into a quench oil section, a middle heat exchange section, and a gasoline section from bottom to top. The quench oil section is connected to the heat exchange device through pipelines, and the heavy components in the quench oil section exchange heat with the heat exchange device. The middle heat exchange section is equipped with a coil heat exchanger, and the components in the middle section of the quench tower 3 exchange heat with the coil heat exchanger. The top of the gasoline section is provided with a gasoline component outlet 10, which is connected to the water washing tower through a pipeline.

[0039] In this invention, reactor 1 is used to generate cracked oil and gas, which is a conventional device for catalytic cracking of crude oil to produce olefins in the prior art, and will not be described in detail here. The feed entering reactor 1 includes, but is not limited to, one or more of the following: C4 alkanes, LPG, raffinate, reformate topping oil, naphtha, jet fuel, diesel, and hydrocracking tail oil.

[0040] The quench cooler 2 also adopts a conventional device in the prior art, and its structure itself will not be described in detail. For example, this utility model uses a pipeline quench cooler 2. The quench cooler 2 itself or its outlet pipe is equipped with a detection structure for detecting the temperature of the product in the quench cooler 2. The pyrolysis oil and gas first undergo appropriate cooling and heat exchange in the quench cooler 2, and the temperature of the pyrolysis oil and gas leaving the quench cooler 2 is between 350 and 600°C, before entering the quench tower 3. In this way, some of the heat from the high-temperature oil and gas can be recovered, improving the energy recovery rate.

[0041] Furthermore, in traditional catalytic cracking processes, the high-temperature oil and gas exiting reactor 1 is directly used to generate medium- and high-pressure steam. Because the cracked oil and gas are prone to coking on the tube bundles, periodic decoking is required, affecting the long-term operation of the unit. This invention adds an oil quench cooler 2 to pre-cool the cracked oil and gas generated in reactor 1. This also solves the problem in conventional processes where high-temperature oil and gas easily coke on the tube bundles or directly enter the quench tower, leading to sudden boiling, thus improving the stability of the unit's operation and enhancing the product fractionation effect.

[0042] In this invention, the cracked oil and gas are first cooled by the quench cooler 2. The quench tower 3 is divided into three sections from bottom to top: the quench oil section connects to an external heat exchange device for heat exchange, and the middle heat exchange section uses an internal coil heat exchanger. This combination of heat exchange via the quench cooler 2 and multi-stage heat exchange via the quench tower 3 improves the cooling and heat recovery efficiency of the cracked oil and gas produced at the top of the crude oil catalytic cracking reactor 1, reduces heat waste, improves energy utilization efficiency, and also reduces coking problems.

[0043] Along the flow direction of the heavy components in the quenching oil section, the heat exchange device includes a first steam generator 4 and a second steam generator 5 arranged in series. Boiler water is introduced into the cold side of the first steam generator 4 and high-pressure steam is output. Boiler water is introduced into the cold side of the second steam generator 5 and medium-pressure steam is output.

[0044] It should be noted that in this invention, the pressure of the high-pressure steam is 5-10 MPa, and the pressure of the medium-pressure steam is 3.5 MPa. By using a two-stage series-connected steam generator to link with the quench oil section of the quench oil tower, the heavy components in the quench oil section can undergo heat exchange twice sequentially, resulting in better cooling, greater heat recovery, and improved energy efficiency.

[0045] The heat exchanger's hot-side outlet is divided into a first branch 6 and a second branch 7. The first branch 6 is connected to the feed inlet of the quench cooler 2 or the inlet of the quench tower 3, and the second branch 7 returns to the quench oil section.

[0046] In this invention, the hot side refers to the side of the heat exchange device that is in direct contact with the high-temperature medium (the heavy component at the bottom of the quench tower 3, with a temperature of approximately 300-400℃), and is used to release heat. The cold side refers to the side that is in contact with the low-temperature medium (boiler water), and is used to absorb heat. The hot side outlet of the heat exchange device is divided into two paths: the first branch 6 returns to the feed inlet of the quench cooler 2 or to the inlet of the quench tower 3, mixing with the feed material entering the tower to achieve rapid cooling; the second branch 7 circulates back to the quench oil section of the quench tower 3 to maintain the oil balance and temperature stability within the tower.

[0047] The heat exchanger's hot-side outlet is divided into a first branch 6 and a second branch 7 via a tee fitting 9, and a flow regulating mechanism is provided at the branch interface of the tee fitting. The flow regulating mechanism is an electric proportional valve or a manual butterfly valve, which dynamically controls the flow ratio of the heavy component entering the first branch 6 and the second branch 7.

[0048] In this invention, the heat of high-temperature oil and gas is efficiently converted into medium-pressure steam (3.5 MPa) through oil circulation at the hot side outlet of the heat exchanger, enabling cascaded energy utilization. The temperature distribution within the quench tower 3 is controlled by adjusting the flow ratio of the two branches. Furthermore, a portion of the heavy-duty oil is returned to the inlet of the quench tower 3, reducing the temperature of the newly introduced oil and gas and preventing localized overheating that could lead to coking.

[0049] As an alternative, the first branch 6 is also equipped with a filter for removing catalyst particles from the heavy fraction oil.

[0050] The coil heat exchanger is a structure installed inside the quench tower 3 and is not shown in the figure. The coil heat exchanger includes a spiral coil through which boiler water is circulated as a refrigerant. The outer wall of the coil is equipped with enhanced heat transfer fins. These enhanced heat transfer fins can be spiral fins or serrated fins, which can increase the contact area for heat exchange with oil and gas.

[0051] To increase the heat exchange area per unit volume, the spiral coil has a multi-layer coaxial winding structure, with each layer of coil fixed by a support structure. The coil axis is arranged parallel to or inclined to the tower body axis of the quench tower 3.

[0052] The boiler water flow direction within the spiral coil is counter-current to the oil and gas flow direction within the tower. The spacing between the spiral coil tubes gradually increases along the oil and gas flow direction, which can match the oil and gas temperature gradient and avoid localized overheating. Thus, the optimized fluid flow channel can further improve heat exchange efficiency.

[0053] In this invention, the middle heat exchange section is also connected to a third steam generator 8 via a circulation pipeline. The components of the middle heat exchange section return to the quench tower 3 after heat exchange in the third steam generator 8. Boiler water is introduced into the cold side of the third steam generator 8, and medium-pressure steam is output.

[0054] In this way, the components in the middle section of the quench tower 3 not only undergo heat exchange through the coil heat exchanger, but also further through the external third steam generator 8. The components in the middle section also undergo two stages of heat exchange, resulting in better cooling effect of oil and gas, more heat recovery, and effectively improved heat recovery efficiency.

[0055] In this invention, the heat extraction process using the crude oil catalytic cracking to olefins reaction cracking oil and gas heat extraction system includes:

[0056] The high-temperature oil and gas produced in reactor 1 is fed into quencher 2 for initial cooling, and then into quench tower 3. In the bottom quench section, the cracked oil and gas undergo heat exchange and cooling sequentially with steam from the first steam generator 4 and the second steam generator connected to the quench section. The heavy components after heat exchange in the quench section are proportionally distributed to the first branch 6 and the second branch 7, re-entering the inlet of quencher 2 or quench tower 3, or returning to the quench section tower for recirculation. In the middle heat exchange section, the middle component (light component) contacts the outer wall of the coil, and heat is transferred to the cooling medium inside the coil. After absorbing heat, the cooling medium (boiler water) partially vaporizes (generating steam) or heats up, flowing out of the coil into the downstream system. After the temperature of the middle component (light component) stabilizes, it is recirculated to the tray spray or transported to the third steam generator 8 for heat exchange, and then returned to quench tower 3. The product gas from the top gasoline section is transported to the water washing tower for fractionation and purification. Throughout the process, multi-stage refrigerant heat extraction is used, which greatly improves the cooling and heat recovery efficiency of pyrolysis oil and gas, reduces heat waste, improves energy utilization efficiency, and also reduces coking problems.

[0057] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system, characterized in that, include: The reactor catalytically cracks crude oil to produce cracked oil and gas. A quench cooler, the inlet of which is connected to the outlet of the reactor; The quench oil tower is connected to the outlet of the quench cooler. The quench oil tower is divided into a quench oil section, a middle heat exchange section, and a gasoline section from bottom to top. The quench oil section is connected to the heat exchange device through pipelines, and the heavy components in the quench oil section exchange heat with the heat exchange device. The middle heat exchange section is equipped with a coil heat exchanger, and the components in the middle section of the quench tower exchange heat with the coil heat exchanger. The top of the gasoline section is provided with a gasoline component outlet.

2. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to claim 1, characterized in that, The heat exchange device includes a first steam generator and a second steam generator connected in series. The cold side of the first steam generator is supplied with boiler water and outputs high-pressure steam, while the cold side of the second steam generator is supplied with boiler water and outputs medium-pressure steam.

3. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to claim 1, characterized in that, The heat exchanger's hot-side outlet is divided into a first branch and a second branch. The first branch connects to the feed inlet of the quench cooler or the inlet of the quench tower, while the second branch returns to the quench oil section.

4. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to claim 3, characterized in that, The heat exchanger's hot-side outlet is divided into a first branch and a second branch via a tee fitting, and a flow regulation mechanism is provided at the branch interface of the tee fitting.

5. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to claim 4, characterized in that, The flow regulation mechanism is an electric proportional valve or a manual butterfly valve, which dynamically controls the flow ratio of the heavy component entering the first branch and the second branch.

6. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to any one of claims 1-5, characterized in that, The coil heat exchanger includes a spiral coil, through which boiler water is circulated as a refrigerant, and the outer wall of the coil is provided with enhanced heat transfer fins.

7. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to claim 6, characterized in that, The spiral coil has a multi-layer coaxial winding structure, and the coil axis is parallel to or inclined to the tower body axis of the quench tower.

8. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to claim 6, characterized in that, The flow direction of boiler water in the spiral coil is countercurrent to the flow direction of oil and gas in the tower.

9. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to any one of claims 1-5, characterized in that, The middle heat exchange section is also connected to a third steam generator through a circulation pipeline. The components of the middle heat exchange section are returned to the quench tower after heat exchange in the third steam generator.

10. The crude oil catalytic cracking to olefins reaction cracking oil and gas heat recovery system according to claim 9, characterized in that, The cold side of the third steam generator is fed with boiler water and outputs medium-pressure steam.

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