Flue gas system

Abstract

The invention discloses a flue gas system. The technical problem that carbon dioxide in existing cracking furnace flue gas and power station flue gas is directly exhausted into the atmosphere without being collected is solved. Comprising cracking furnace bodies, flue assemblies, a flue gas header pipe, a gathering chimney and a flue for leading flue gas of a power station to a carbon dioxide collecting mechanism, and each flue assembly is communicated with a flue gas outlet of the corresponding cracking furnace body; the flue gas main pipe is communicated with the flue gas outlets of the more than one flue component; the gathering chimney comprises an outer cylinder, and a cracking furnace chimney and a power station chimney which are arranged in the outer cylinder; an outlet of the flue gas header pipe is communicated with the cracking furnace chimney; the carbon dioxide collecting mechanism comprises a main flue communicated with the cracking furnace chimney and the power station chimney and a carbon dioxide collecting fan arranged on the main flue; and a flue gas outlet of the power station is selectively communicated with the carbon dioxide collecting fan and / or the power station chimney. By collecting the flue gas, carbon dioxide in the flue gas of the cracking furnace body or the power station is conveniently recycled, and the carbon emission of the device is reduced.

Description

Technical Field

[0001] This application belongs to the field of ethylene chemical raw material technology, specifically relating to a flue gas system. Background Technology

[0002] Carbon dioxide, as an important chemical raw material, is widely used in food, beverage, pharmaceutical, and chemical industries. Ethylene cracking furnaces, as key equipment in the petrochemical industry, generate significant carbon dioxide emissions during operation, causing substantial environmental impact. With increasing global concern about greenhouse gas emissions, reducing carbon dioxide emissions has become a crucial task for governments and businesses worldwide. Recovering and utilizing carbon dioxide from ethylene cracking furnace flue gas not only reduces the plant's carbon emissions, helping to lower corporate carbon emissions and meet environmental protection requirements, but also allows companies to profit from carbon trading markets by reducing emissions or increasing carbon sinks. Therefore, the recovery and utilization of carbon dioxide from ethylene cracking furnace flue gas has broad prospects.

[0003] In traditional ethylene plants, the flue gas produced by ethylene cracking furnaces is typically emitted directly into the atmosphere, with each furnace's emissions operating independently and without interference. The power station, also known as a steam power station, is an auxiliary system in large petrochemical, refining, or chemical plants such as ethylene plants. As an auxiliary unit, it is usually located alongside the ethylene plant. However, the high concentrations of carbon dioxide generated between these two units are generally emitted directly into the atmosphere through their respective independent chimneys without any collection or treatment. There is a lack of a unified recovery and coordination mechanism between the units. This direct emission of uncollected carbon dioxide into the atmosphere, without any recovery or coordination, leads to the dilution and diffusion of high-concentration carbon dioxide into the atmosphere, resulting in resource waste and diminishing the incentive for proactive emission reduction, thus failing to meet environmental protection requirements. Summary of the Invention

[0004] To address the technical problem of carbon dioxide being directly emitted into the atmosphere from the flue gas of the cracking furnace and the power station in current ethylene plants without being collected, this application provides a flue gas system.

[0005] In a first aspect of this application, a flue gas system is provided, comprising: One or more pyrolysis furnace bodies; The number of flue assemblies is the same as that of the pyrolysis furnace body, and each flue assembly is connected to the flue gas outlet of the corresponding pyrolysis furnace body; The main flue gas pipe is connected to the flue gas outlet of one or more of the aforementioned flue gas assemblies; The collection chimney includes an outer cylinder and a pyrolysis furnace chimney and a power station chimney located inside the outer cylinder, wherein the pyrolysis furnace chimney is connected to the outlet of the flue gas main; The carbon dioxide collection mechanism includes a main flue that is connected to both the cracking furnace chimney and the power station chimney, and a carbon dioxide collection fan installed in the main flue. The power station, wherein the flue gas outlet of the power station may be selectively connected to the carbon dioxide collection fan and / or the power station chimney.

[0006] In some embodiments, the flue assembly includes: The first smoke pipe has an inlet that is connected to the flue gas outlet of the pyrolysis furnace. An induced draft fan is installed inside the first smoke duct; The front baffle of the induced draft fan is located inside the first flue and upstream of the induced draft fan; The second flue pipe has its inlet connected to the outlet of the first flue pipe, and its outlet connected to the main flue gas pipe.

[0007] In some embodiments, the flue assembly further includes a flue baffle disposed within the second flue and downstream of the induced draft fan.

[0008] In some embodiments, the flue assembly further includes a vent pipe and a vent baffle disposed on the vent pipe, the vent pipe being connected in communication with the first flue pipe and in parallel with the second flue pipe.

[0009] In some embodiments, the second flue includes a first connecting section and a second connecting section that are angled and connected, the flue baffle is disposed on the first connecting section, and the second connecting section is connected to the main flue.

[0010] In some embodiments, the second connecting segment has a first end and a second end disposed opposite to each other, and the inner diameter of the second connecting segment gradually increases from the first end to the second end.

[0011] In some embodiments, the first end of the second connecting segment is connected to the first connecting segment; the second end of the second connecting segment is connected to the flue gas main.

[0012] In some embodiments, the second connecting section is angled to the main flue gas pipe, and the angle between the second connecting section and the main flue gas pipe is 30° to 60°.

[0013] In some embodiments, the flue gas main has a first end and a second end disposed opposite to each other, the inner diameter of the flue gas main gradually increases from the first end to the second end, and the second end of the flue gas main is close to the collection chimney.

[0014] In some embodiments, the flue gas main includes a first flue gas pipe and a second flue gas pipe, the first flue gas pipe and the second flue gas pipe are arranged at an angle, the first flue gas pipe is connected to the flue gas outlet of one or more of the flue gas duct components, and the second flue gas pipe is located above the first flue gas pipe and is arranged at an angle to the first flue gas pipe.

[0015] In some embodiments, the angle between the second flue gas pipe and the pyrolysis furnace chimney is 30° to 60°.

[0016] In some embodiments, the flue gas system further includes a third flue pipe connected to the flue gas outlet of the power station and a power station flue gas bridging baffle disposed in the third flue pipe, the third flue pipe being connected to the main flue. In some embodiments, the outlet pressure of the induced draft fan is less than or equal to 300 Pa.

[0017] A flue gas system according to one or more embodiments of this application includes one or more pyrolysis furnace bodies, a number of flue gas assemblies equal to the number of pyrolysis furnace bodies, a main flue gas pipe, a collection chimney, and a carbon dioxide collection mechanism. Each flue gas assembly is connected to the flue gas outlet of the corresponding pyrolysis furnace body. The main flue gas pipe is connected to the flue gas outlet of one or more flue gas assemblies. The collection chimney includes an outer cylinder and a pyrolysis furnace chimney and a power station chimney disposed within the outer cylinder. The outlet of the main flue gas pipe is connected to the pyrolysis furnace chimney. The carbon dioxide collection mechanism includes a main flue connected to both the pyrolysis furnace chimney and the power station chimney, and a carbon dioxide collection fan disposed in the main flue. The flue gas outlet of the power station may be selectively connected to the carbon dioxide collection fan and / or the power station chimney.

[0018] Therefore, the flue gas system of this application can collect the flue gas produced by multiple pyrolysis furnaces and send it to a carbon dioxide collection mechanism to recover carbon dioxide from the flue gas. The power station flue gas can be used as backup feedstock. When the ethylene pyrolysis furnace is shut down or the flue gas supply is insufficient, the power station flue gas can be sent to the carbon dioxide collection mechanism. If the carbon dioxide collection mechanism malfunctions or the collected flue gas volume is insufficient, both the pyrolysis furnace flue gas and the power station flue gas can be discharged into the atmosphere through the pyrolysis furnace chimney and the power station chimney respectively, without affecting the normal operation of the pyrolysis furnace or the power station. This design achieves carbon reduction or zero carbon emissions, thus contributing clean and low-carbon energy, without affecting the normal production of the pyrolysis furnace and the power station. Collecting the flue gas facilitates the recovery and utilization of carbon dioxide from the pyrolysis furnace flue gas or the power station flue gas, reducing the plant's carbon emissions. Attached Figure Description

[0019] Figure 1 A schematic diagram of a flue gas system in one or more embodiments of this application is shown.

[0020] Figure 2 It shows Figure 1 A schematic diagram of the flue assembly.

[0021] Figure 3 It shows Figure 1 A schematic diagram of the connection between the second flue and the main flue.

[0022] Figure 4 It shows Figure 1 A schematic diagram of the connection between the flue gas main and the pyrolysis furnace chimney.

[0023] Figure 5 It shows Figure 1 A schematic diagram showing the connection between the power station and the carbon dioxide collection mechanism.

[0024] Figure 6 It shows Figure 1 A schematic diagram showing the connection between the power station and the power station chimney.

[0025] Explanation of reference numerals in the attached drawings: 100-Flue gas system, 110-Cracking furnace body, 120-Flue duct assembly, 121-First flue pipe, 122-Induced draft fan front baffle, 123-Induced draft fan, 124-Second flue pipe, 1241-First connecting section, 1242-Second connecting section, 125-Flue duct baffle, 126-Vent pipe, 127-Vent baffle, 130-Flue gas main pipe, 131-First flue gas pipe, 132-Second flue gas pipe, 140-Collection chimney, 141-Outer cylinder, 142-Cracking furnace chimney, 143-Power station chimney, 150-Carbon dioxide collection mechanism, 151-Main flue, 152-Carbon dioxide collection fan, 160-Power station, 161-Power station flue gas bridging baffle. Detailed Implementation

[0026] To enable those skilled in the art to more clearly understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] In traditional ethylene plants, the flue gas from the cracking furnaces is emitted into the atmosphere. Each furnace's flue gas is typically discharged into the atmosphere through its own independent exhaust fan, with each furnace's flue gas operating independently and without affecting the others. Carbon dioxide is emitted directly into the atmosphere without being collected or recovered, resulting in high concentrations of carbon dioxide being diluted and diffused into the atmosphere. This leads to resource waste and diminishes the incentive for proactive emission reduction, failing to meet environmental protection requirements.

[0028] To address the aforementioned issues, this application provides a flue gas system that collects flue gas to facilitate the recovery and utilization of carbon dioxide from the flue gas in the pyrolysis furnace or the power station, thereby reducing the carbon emissions of the equipment.

[0029] Please see Figure 1 According to a first aspect of this application, a flue gas system 100 is provided, including one or more pyrolysis furnace bodies 110, flue gas assemblies 120 in the same number as the pyrolysis furnace bodies 110, a main flue gas pipe 130, a collection chimney 140, and a carbon dioxide collection mechanism 150. Each flue gas assembly 120 is connected to the flue gas outlet of the corresponding pyrolysis furnace body 110. The main flue gas pipe 130 is connected to the flue gas outlet of one or more flue gas assemblies 120. The collection chimney 140 includes an outer cylinder 141 and a pyrolysis furnace chimney 142 and a power station chimney 143 disposed within the outer cylinder 141. The pyrolysis furnace chimney 142 is connected to the outlet of the main flue gas pipe 130. The carbon dioxide collection mechanism 150 includes a main flue 151 connected to both the pyrolysis furnace chimney 142 and the power station chimney 143, and a carbon dioxide collection fan 152 disposed in the main flue 151. The flue gas outlet of the power station 160 can be selectively connected to the carbon dioxide collection fan 152 and / or the power station chimney 143.

[0030] Power Station 160, officially known as "Steam Power Station," is one of the auxiliary systems in large petrochemical, refining, or chemical plants such as ethylene plants. The flue gas of Power Station 160 mainly comes from its boiler system, which generates steam by burning fuel, and the flue gas is the exhaust gas after combustion.

[0031] like Figure 1 As shown, in some embodiments, the number of pyrolysis furnace bodies 110 can be 2 to 10, specifically 3, 5, 7, or 9. The corresponding number of flue gas assemblies 120 is the same as the number of pyrolysis furnace bodies 110. In some embodiments, the number of pyrolysis furnace bodies 110 is 5, namely a first pyrolysis furnace body 110, a second pyrolysis furnace body 110, a third pyrolysis furnace body 110, a fourth pyrolysis furnace body 110, and a fifth pyrolysis furnace body 110.

[0032] like Figure 1 As shown in the diagram, Ax-Bx (x=2~10) represent multiple pyrolysis furnace body sections 110; Bx to Cx represent the flue gas assembly section 120 of the ethylene pyrolysis furnace; Cx to D represent the main flue gas pipe section 130; D to E represent the pyrolysis furnace flue gas exhaust section; and D to F represent the pyrolysis furnace flue gas to carbon dioxide collection mechanism section. Sections F to G, containing flue gas from power station 160, represent mixed flue gas to carbon dioxide collection mechanism section. G is the inlet of the carbon dioxide collection mechanism. M is the flue gas outlet of power station 160; M to P represent the power station 160 flue gas exhaust section; and M to N represent the power station 160 flue gas to carbon dioxide collection mechanism section.

[0033] Furthermore, the flue gas system of this application can collect flue gas produced by multiple cracking furnaces and send it to a carbon dioxide collection mechanism to recover carbon dioxide from the flue gas. The power station flue gas can be used as backup feedstock. When the ethylene cracking furnace is shut down or the flue gas supply is insufficient, the power station flue gas can be sent to the carbon dioxide collection mechanism. If the carbon dioxide collection mechanism malfunctions or the collected flue gas volume is insufficient, both the cracking furnace flue gas and the power station flue gas can be discharged into the atmosphere through the cracking furnace chimney and the power station chimney respectively, without affecting the normal operation of the cracking furnace or the power station. This design achieves carbon reduction or zero carbon emissions, thus contributing to clean and low-carbon energy, without affecting the normal production of the cracking furnace and the power station.

[0034] The flue gas outlet of power station 160 can be selectively connected to carbon dioxide collection fan 152 and / or power station chimney 143. This means that when the overall flue gas volume of the ethylene unit is insufficient, connecting the flue gas outlet of power station 160 to carbon dioxide collection fan 152 can supplement the carbon dioxide collection fan 152 with additional flue gas. This ensures that the normal operation of the carbon dioxide collection mechanism 150 will not be affected in the event of a malfunction or reduced production in the ethylene unit. If the flue gas volume of power station 160 exceeds the requirements of carbon dioxide collection mechanism 150, the excess flue gas can be vented through power station chimney 143, thereby achieving overall dynamic balance through flue gas flow.

[0035] When there is insufficient flue gas in the power station 160 and the ethylene unit, the carbon dioxide collection mechanism 150 can draw in some air at this time. This is an emergency operation of low-concentration make-up air. Although these gases reduce the overall production efficiency of the unit, they can help maintain the normal operation of the unit.

[0036] Therefore, by selectively connecting the flue gas outlet of power station 160 to carbon dioxide collection fan 152 and / or power station chimney 143, carbon dioxide collection mechanism 150 can determine the operating condition through gas composition analysis. In this case, by selectively connecting or disconnecting power station 160 from carbon dioxide collection fan 152, the overall unit load can be smoothly reduced to achieve regulation. That is, even when the entire unit is under complex operating conditions, fault conditions, or accident conditions, it maintains the safe and stable operation of upstream and downstream units, minimizing the impact on other units and ensuring safe and stable operation.

[0037] Therefore, the flue gas outlet of the cracking furnace body 110 is connected to the flue gas assembly 120. The flue gas assembly 120 is used to transport the flue gas from the cracking furnace body 110 to the main flue gas pipe 130, which in turn sends the flue gas to the cracking furnace chimney 142 in the collecting chimney 140. From the main flue gas pipe 130 to the cracking furnace chimney 142 in the collecting chimney 140, from the main flue gas pipe 130 to the main flue 151, and from the main flue 151 to the carbon dioxide collection fan 152, no baffles are installed on these flues. This ensures that the flue gas flows freely under the combined action of the chimney draft and the carbon dioxide collection fan 152, so that when the carbon dioxide collection mechanism 150 reduces its flow or an emergency occurs, excess cracking furnace flue gas can be smoothly discharged into the atmosphere through the cracking furnace chimney, thus not affecting the normal operation of the ethylene plant. By collecting the flue gas, it is convenient to recover and utilize carbon dioxide from the cracking furnace body flue gas or the power station flue gas, reducing the plant's carbon emissions.

[0038] like Figure 1 and Figure 2 As shown, in some embodiments, the flue assembly 120 includes a first flue 121, an induced draft fan front baffle 122, an induced draft fan 123, a second flue 124, and a flue baffle 125. The inlet of the first flue 121 is connected to the flue gas outlet of the pyrolysis furnace; the induced draft fan 123 is disposed inside the first flue 121; the induced draft fan front baffle 122 is disposed inside the first flue 121 and located upstream of the induced draft fan 123; the inlet of the second flue 124 is connected to the outlet of the first flue 121, and the outlet of the second flue 124 is connected to the main flue gas pipe 130; the flue baffle 125 is disposed inside the second flue 124 and located downstream of the induced draft fan 123. In some embodiments, the induced draft fan 123 is a frequency converter fan.

[0039] In some embodiments, the induced draft fan front damper 122 and the flue damper 125 are pneumatic valves. To ensure normal emission of flue gas from the cracking furnace, the induced draft fan front damper 122 and the flue damper 125 are normally open pneumatic valves. Flue gas from section Bx of the cracking furnace passes through section Cx of the induced draft fan front damper 122, the induced draft fan 123, and the flue damper 125 before converging into section 130D of the main flue gas pipe. To ensure the normal operation of the cracking furnace under normal operating conditions, coke removal conditions, hot standby conditions, and emergency accident conditions, the induced draft fan front damper 122, the induced draft fan 123, the flue damper 125, and the vent damper 127 operate in coordination to achieve safe and stable operation of the ethylene cracking furnace and downstream units. To ensure that the pyrolysis furnace can operate safely and stably or be shut down safely under different operating conditions such as normal operation, coke removal, hot standby, and emergency accident, while not causing safety hazards to downstream units, namely the carbon dioxide collection mechanism 150 and the power station 160.

[0040] like Figure 2As shown, in some embodiments, the flue assembly 120 further includes a vent pipe 126 and a vent baffle 127 disposed on the vent pipe 126. The vent pipe 126 is connected to the first flue pipe 121 and is connected in parallel with the second flue pipe 124. The vent baffle 127 is a normally closed pneumatic valve. Under normal circumstances, the vent baffle 127 is closed, and the flue gas from the pyrolysis furnace body 110 will not pass through the vent pipe 126. However, when an emergency occurs in the pyrolysis furnace body 110, such as a furnace tube rupture, causing the flue gas to contain excessive combustible hydrocarbons or CO, the flue gas cannot be sent to the carbon dioxide collection mechanism 150. At this time, the vent baffle 127 can be opened, and the flue baffle 125 disposed on the second flue pipe 124 can be closed to prevent the flue gas from entering the carbon dioxide collection mechanism 150. The flue gas is then directly discharged into the atmosphere through the vent pipe 126, i.e., the small chimney, on the top of the pyrolysis furnace body 110.

[0041] like Figure 2 As shown, in some embodiments, the second flue duct 124 includes a first connecting section 1241 and a second connecting section 1242 that are angled and connected to each other. A flue baffle 125 is disposed on the first connecting section 1241, and the second connecting section 1242 is connected to the main flue gas duct 130. The second flue duct 124 is arranged in segments, consisting of the first connecting section 1241 and the second connecting section 1242. The first connecting section 1241 and the second connecting section 1242 are angled, and the connection between the first connecting section 1241 and the second connecting section 1242 can be achieved by welding an elbow or a flange connection, forming a flue gas transmission channel with a directional turning function to ensure the space arrangement requirements.

[0042] like Figure 2 and Figure 3 As shown, in some embodiments, the second connecting section 1242 has a first end and a second end that are disposed opposite to each other, and the inner diameter of the second connecting section 1242 gradually increases from the first end to the second end; the flue gas flows from the first end to the second end of the second connecting section 1242, which can reduce frictional resistance, avoid eddies and excessive turbulence, and ensure the smooth flow of flue gas.

[0043] In some embodiments, the first end of the second connecting section 1242 is connected to the first connecting section 1241; the second end of the second connecting section 1242 is connected to the flue gas main duct 130. This ensures that flue gas can flow from the first connecting section 1241 to the second connecting section 1242, and from the second connecting section 1242 to the flue gas main duct 130, where it flows.

[0044] like Figure 3As shown, in some embodiments, the second connecting section 1242 is angled to the flue gas main duct 130, with the angle between the second connecting section 1242 and the flue gas main duct 130 being 30° to 60°. The angled arrangement of the second connecting section 1242 with the flue gas main duct 130, i.e., the second connecting section 1242 being inserted obliquely into the flue gas main duct 130, can reduce resistance and avoid turbulence. The angle between the second connecting section and the flue gas main duct 130 can be 30°, 40°, 45°, 50°, 55°, or 60°.

[0045] like Figure 3 As shown, in some embodiments, the flue gas main duct 130 has a first end and a second end arranged opposite to each other. The inner diameter of the flue gas main duct 130 gradually increases from the first end to the second end, and the second end of the flue gas main duct 130 is close to the collection chimney 140. Several pyrolysis furnaces are arranged side by side in sequence, namely a first pyrolysis furnace body 110, a second pyrolysis furnace body 110, a third pyrolysis furnace body 110, a fourth pyrolysis furnace body 110, and a fifth pyrolysis furnace body 110. Correspondingly, the flue gas outlet of the first pyrolysis furnace body 110 is connected to the first flue gas duct assembly 120, the flue gas outlet of the second pyrolysis furnace body 110 is connected to the second flue gas duct assembly 120, the flue gas outlet of the third pyrolysis furnace body 110 is connected to the third flue gas duct assembly 120, the flue gas outlet of the fourth pyrolysis furnace body 110 is connected to the fourth flue gas duct assembly 120, and the flue gas outlet of the fifth pyrolysis furnace body 110 is connected to the fifth flue gas duct assembly 120. The fifth pyrolysis furnace body 110 is located near the collecting chimney 140, while the first pyrolysis furnace body 110 is located away from the collecting chimney 140. The flue gas main duct 130 connects to the flue gas outlets of the first, second, third, fourth, and fifth flue gas duct assemblies in sequence. The second end of the flue gas main duct 130 is near the collecting chimney 140, and the first end is near the first pyrolysis furnace body 110. The flue gas main duct 130 adopts a gradually expanding diameter structure from its first end to its second end to ensure a stable flue gas velocity.

[0046] like Figure 3As shown, in some embodiments, the section of the flue gas main duct 130 connected to the first flue assembly 120 is designated as the first section, the section connected to the second flue assembly 120 is designated as the second section, the section connected to the first flue assembly 120 along the flue gas main duct 130 is designated as the third section, the section connected to the first flue assembly 120 along the flue gas main duct 130 is designated as the fourth section, and the section connected to the first flue assembly 120 along the flue gas main duct 130 is designated as the fifth section. The inner diameter of the first section of the flue gas main duct 130 is smaller than the inner diameter of the second section, the inner diameter of the second section is smaller than the inner diameter of the third section, the inner diameter of the third section is smaller than the inner diameter of the fourth section, and the inner diameter of the fourth section is smaller than the inner diameter of the fifth section. That is, the cross-sectional area of ​​the flue gas main duct 130 increases in a stepwise manner with the increase of flue gas volume, ensuring a stable flue gas flow rate and avoiding eddies and sudden drops in static pressure caused by sudden expansion at the end, so as to achieve low resistance and uniform velocity in the entire section when it enters the collection chimney 140.

[0047] like Figure 4 As shown, in some embodiments, the flue gas main duct 130 includes a first flue gas pipe 131 and a second flue gas pipe 132. The first flue gas pipe 131 and the second flue gas pipe 132 are arranged at an angle. The first flue gas pipe 131 is connected to one or more flue gas duct assemblies 120. The second flue gas pipe 132 is located above the first flue gas pipe 131 and forms an angle of 120° to 150° with the first flue gas pipe 131. Flue gas flows into the pyrolysis furnace chimney 142 through the first flue gas pipe 131 and the second flue gas pipe 132. The second flue gas pipe 132 is inserted obliquely into the middle of the pyrolysis furnace chimney 142. A portion of the flue gas rises to the upper atmosphere and is released under the natural draft of the pyrolysis furnace chimney 142, while a portion flows downwards to the F interface (flue gas mixing point) under the draft of the carbon dioxide collection fan 152 in the carbon dioxide collection mechanism 150. The ratio of upward and downward flue gas can be determined according to the balance between the carbon dioxide collection fan 152 and the natural draft of the pyrolysis furnace chimney 142. For example, when the carbon dioxide collection mechanism 150 requires a large volume of flue gas, the fan's suction power can be increased, allowing more flue gas to flow downwards to the carbon dioxide collection mechanism 150. Conversely, when the carbon dioxide collection mechanism 150 requires a small volume of flue gas, the fan's suction power can be reduced, thus reducing the amount of flue gas flowing downwards to the carbon dioxide collection mechanism 150.

[0048] In some embodiments, the first pyrolysis furnace body 110, the second pyrolysis furnace body 110, the third pyrolysis furnace body 110, the fourth pyrolysis furnace body 110 and the fifth pyrolysis furnace body 110 are arranged in parallel, and the first flue gas pipe 131 is connected to one or more flue gas assemblies 120. The first flue gas pipe 131 is arranged horizontally, which can realize the horizontal collection and transportation of flue gas from multiple furnaces that are synchronously drawn in, do not interfere with each other, and have symmetrical flow velocity distribution.

[0049] like Figure 4As shown, in some embodiments, the second flue pipe 132 is located above the first flue pipe 131 and is set at an angle to the first flue pipe, which facilitates the arrangement and installation.

[0050] like Figure 4 As shown, in some embodiments, the angle between the second flue gas pipe and the pyrolysis furnace chimney is 30°~60°, and the angle between the second flue gas pipe 132 and the pyrolysis furnace chimney 142 can be 30°, 40°, 45°, 50°, 55° or 60°. The second flue gas pipe 132 is inserted obliquely upward into the pyrolysis furnace chimney 142, and the upward movement relies solely on the natural draft of the chimney. The oblique upward structure can effectively reduce the resistance of the upward flue gas, which is beneficial to reducing the height of the chimney. Calculations show that this saves about 10Pa of resistance drop in the upward flue gas, and the chimney can be lowered by 3~5 meters. Since the inner diameter of the chimney is relatively large, plus the outer cement cylinder 141, the cost of the chimney is very high, thus improving economic efficiency.

[0051] Furthermore, the upward-sloping structure of the second flue gas pipe 132 increases the difficulty of downward flue gas flow. In the event of a sudden shutdown of the carbon dioxide collection mechanism, a large amount of flue gas can quickly switch to an upward flow mode, significantly reducing pressure fluctuations in the main flue gas pipe 130 and minimizing the impact of downstream unit failures on the normal operation of the ethylene cracking furnace or even the ethylene plant. Although the upward-sloping structure of the second flue gas pipe 132 increases the resistance to downward flue gas, the increased resistance has a relatively small impact on the mechanical fan and will not lead to an increase in fan investment.

[0052] like Figure 4 and Figure 5 In some embodiments, the flue gas system 100 further includes a third flue pipe connected to the flue gas outlet of the power station and a power station flue gas bridging baffle 161 disposed within the third flue pipe. The third flue pipe is connected to the main flue gas duct via the power station flue gas bridging baffle 161. The power station flue gas bridging baffle 161 is a pneumatic valve, which is a normally closed pneumatic control valve. The flue gas from the pyrolysis furnace passes through the mixing point to the G interface, and then enters the carbon dioxide collection fan 152 of the carbon dioxide collection mechanism 150.

[0053] In some embodiments, automatic monitoring instruments such as temperature, pressure, flow rate, and composition analysis can be installed on the flue gas duct. Under normal operating conditions, the flue gas from the ethylene cracking furnace is sufficient for the carbon dioxide collection mechanism 150. However, in special circumstances, when the flue gas from the cracking furnace is insufficient or unavailable, the flue gas bridging baffle 161 of the power station can be opened, allowing the flue gas from the power station 160 to be incorporated into the main flue duct 151, mixed with the flue gas from the cracking furnace, and then enter the carbon dioxide collection mechanism 150. This design increases operational flexibility and prevents sudden shutdowns of the ethylene plant from having an excessive impact on the carbon dioxide collection mechanism 150, thus contributing to the stable operation of the carbon dioxide collection mechanism 150.

[0054] As shown in the figure above, the flue gas pressure of power station 160 is slightly positive. Under normal circumstances, the flue gas bridging baffle 161 of power station is a normally closed pneumatic control valve. The flue gas is mainly vented through the power station chimney 143. Under special working conditions, the flue gas bridging baffle 161 of power station is opened, and part or all of the flue gas of power station 160 and the flue gas of pyrolysis furnace are mixed and enter the carbon dioxide collection mechanism 150.

[0055] In some embodiments, the outlet pressure of the induced draft fan 123 is less than or equal to 300 Pa. The flue gas from each pyrolysis furnace is collected in the pyrolysis furnace flue gas main duct 130. Under normal circumstances, the pressure of the flue gas main duct 130 is maintained at 0 Pa or slightly negative pressure. This ensures that even if individual pyrolysis furnaces are shut down, the flue gas in the flue gas main duct 130 will not backflow into the furnace through the flue damper 125. At this time, the flow of the flue gas is provided by the natural draft of the chimney. However, this inevitably results in an excessively high chimney, which in turn leads to a significant increase in investment. In this application, the outlet pressure of the induced draft fan 123 is less than or equal to 300 Pa, and the corresponding pressure of the pyrolysis furnace flue gas main duct 130 is 0~300 Pa, maintained at atmospheric pressure to slightly positive pressure. This ensures that the flue gas will not backflow into the pyrolysis furnace through the flue damper 125. When the pressure of the flue gas main duct 130 is maintained at a positive pressure below 300 Pa, even if one of the pyrolysis furnaces is shut down, the flue gas will not easily backflow into the pyrolysis furnace through the flue damper 125. At this point, the chimney height can be reduced by about 100 meters, from the original 220 meters to about 120-150 meters, which can reduce the investment in chimneys by more than half.

[0056] Since the pressure in the flue gas main 130 needs to be provided by the induced draft fan 123 of the pyrolysis furnace, increasing the pressure head by 5-8% for the induced draft fan 123 does not significantly increase the cost. When selecting a fan, the margin of this fan is sufficient to provide a pressure head of 300Pa, thus requiring virtually no additional investment. The pressure in the flue gas main 130 of the pyrolysis furnace must also not be too high. As mentioned earlier, if the pressure is too high, there is a risk of backflow of flue gas when a pyrolysis furnace is shut down.

[0057] Through the above embodiments, this application has the following beneficial effects or advantages: (1) In this application, the flue gas outlet of the cracking furnace body 110 is connected to the flue gas assembly 120. The flue gas assembly 120 is used to transport the flue gas of the cracking furnace body 110 to the flue gas main pipe 130. The flue gas main pipe 130 sends the flue gas to the cracking furnace chimney 142 in the collection chimney 140. From the flue gas outlet of the flue gas assembly 120 to the flue gas main pipe 130, the flue gas main pipe 130 to the cracking furnace chimney 142 in the collection chimney 140, the flue gas main pipe 130 to the main flue 151, and the main flue 151 to the carbon dioxide collection fan 152, no baffles are installed on these flues to ensure that the flue gas flows freely under the combined action of the chimney draft and the carbon dioxide collection fan 152. This ensures that the normal operation of the ethylene unit is not affected when the carbon dioxide collection mechanism 150 encounters an emergency. This effectively prevents the carbon dioxide collection mechanism from being evacuated and enables the effective coordinated operation of the ethylene unit, the power station, and the carbon dioxide collection mechanism.

[0058] (2) The flue gas system 100 of this application has high operational stability and safety: no large-diameter baffle is installed on the main flue pipe, and the chimney is used as a pressure balancer to realize free flow of flue gas. The vent baffle 127 and the flue baffle 125 participate in the control and interlocking of the pyrolysis furnace to ensure the safe and stable operation of the pyrolysis furnace under various working conditions.

[0059] (3) The flue gas system 100 of this application has good economic efficiency: it can reasonably control the pressure of the main flue pipe, reduce the height of the chimney, and save investment.

[0060] (4) The flue gas system 100 of this application has strong adaptability: the flue gas from the ethylene plant cracking furnace and the power plant flue gas are centrally discharged, and when the flue gas from the cracking furnace is insufficient, the flue gas from the power plant 160 can be supplemented. At the same time, when problems occur in the downstream units, the flue gas from the two units can be discharged independently. By recovering and utilizing carbon dioxide in the ethylene cracking furnace flue gas, not only can the carbon emissions of the unit be reduced, but additional economic benefits can also be created for the enterprise. The recovery and utilization of carbon dioxide in the ethylene cracking furnace flue gas has broad prospects in the future.

[0061] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0062] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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 application.

[0063] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0064] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0065] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A flue gas system, characterized in that, include: One or more pyrolysis furnace bodies; The number of flue assemblies is the same as that of the pyrolysis furnace body, and each flue assembly is connected to the flue gas outlet of the corresponding pyrolysis furnace body; The main flue gas pipe is connected to the flue gas outlet of one or more of the aforementioned flue gas assemblies; The collection chimney includes an outer cylinder and a pyrolysis furnace chimney and a power station chimney located inside the outer cylinder, wherein the pyrolysis furnace chimney is connected to the outlet of the flue gas main; The carbon dioxide collection mechanism includes a main flue that is connected to both the cracking furnace chimney and the power station chimney, and a carbon dioxide collection fan installed in the main flue. The power station, wherein the flue gas outlet of the power station may be selectively connected to the carbon dioxide collection fan and / or the power station chimney.

2. The flue gas system according to claim 1, characterized in that, The flue assembly includes: The first smoke pipe has an inlet that is connected to the flue gas outlet of the pyrolysis furnace. An induced draft fan is installed inside the first smoke duct; The front baffle of the induced draft fan is located inside the first flue and upstream of the induced draft fan; The second flue pipe has its inlet connected to the outlet of the first flue pipe, and its outlet connected to the main flue gas pipe.

3. The flue gas system according to claim 2, characterized in that, The flue assembly also includes a flue baffle, which is disposed inside the second flue and located downstream of the induced draft fan.

4. The flue gas system according to claim 3, characterized in that, The flue assembly includes a vent pipe and a vent baffle disposed on the vent pipe, the vent pipe being connected to the first flue pipe and in parallel with the second flue pipe.

5. The flue gas system according to claim 4, characterized in that, The second flue includes a first connecting section and a second connecting section that are angled and connected to each other. The flue baffle is located on the first connecting section, and the second connecting section is connected to the main flue.

6. The flue gas system according to claim 5, characterized in that, The second connecting segment has a first end and a second end that are arranged opposite to each other, and the inner diameter of the second connecting segment gradually increases from the first end to the second end.

7. The flue gas system according to claim 6, characterized in that, The first end of the second connecting section is connected to the first connecting section; the second end of the second connecting section is connected to the flue gas main pipe.

8. The flue gas system according to claim 7, characterized in that, The second connecting section is set at an angle to the main flue gas pipe, and the included angle between the second connecting section and the main flue gas pipe is 30°~60°.

9. The flue gas system according to any one of claims 1-8, characterized in that, The flue gas main has a first end and a second end that are arranged opposite to each other. The inner diameter of the flue gas main gradually increases from the first end to the second end. The second end of the flue gas main is close to the collection chimney.

10. The flue gas system according to claim 9, characterized in that, The main flue includes a first flue and a second flue. The first flue and the second flue are set at an angle. The first flue is connected to the flue outlet of one or more of the flue components. The second flue is located above the first flue and is set at an angle to the first flue.

11. The flue gas system according to claim 10, characterized in that, The angle between the second flue gas pipe and the pyrolysis furnace chimney is 30°~60°.

12. The flue gas system according to any one of claims 1-8, characterized in that, The flue gas system also includes a third flue pipe connected to the flue gas outlet of the power station and a power station flue gas bridging baffle installed in the third flue pipe, the third flue pipe being connected to the main flue.

13. The flue gas system according to claim 8, characterized in that, The outlet pressure of the induced draft fan is less than or equal to 300 Pa.

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