Electric cracking furnace heat recovery system and recovery method

Abstract

The invention relates to an electric cracking furnace heat recovery system and recovery method.The electric cracking furnace heat recovery system comprises an electric preheater, a mixer, an electric superheater, an electric cracking furnace and a quenching device which are connected in sequence, and the electric preheater is used for preheating hydrocarbon raw materials distributed into the electric preheater through a raw material distribution device to obtain preheated material flow; the mixer is used for mixing the preheated material flow with the steam material flow conveyed into the mixer so as to obtain a raw material and steam mixed material flow; the electric superheater is used for heating the mixed material flow of the raw materials and the steam to obtain superheated material flow; the electric cracking furnace is used for cracking the superheated material flow to obtain a first cracked material flow; the quenching device is used for quenching and cooling the first pyrolysis material flow to obtain a second pyrolysis material flow. The technical problem that waste heat of a partial cooling and heat pump system of the electric cracking furnace cannot be fully recycled is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat recovery of electrolytic furnaces, and in particular to a heat recovery system and method for an electrolytic furnace. Background Art

[0002] As global climate issues intensify, the world is paying more and more attention to mitigating climate change and reducing carbon dioxide emissions. In order to more effectively promote carbon emission reduction, accelerate the construction of a larger carbon trading market system, and include more industries with high energy consumption, large emissions, and relatively concentrated emission sources into the carbon trading market. Low-carbon development requires changes in petrochemical technology and process design, and many industrial processes that use fossil fuels for energy supply will be replaced by electricity.

[0003] The chemical industry is a high-energy consumption and high-carbon emission industry, and is one of the main sources of greenhouse gases in the industrial field. Carbon emissions from the global chemical industry account for 5.8% of the world's total emissions (including 3.6% of industrial energy emissions and 2.2% of direct industrial emissions). As the dual carbon goals approach, the implementation of relevant carbon emission standards is imperative, and the prescribed carbon emission values ​​will also tend to be stricter, which will make the chemical industry face development constraints from carbon emissions. In order to better meet the carbon reduction needs of the petrochemical industry, the development of the core technology of electric cracking furnaces can effectively promote scientific and technological innovation and further open up and expand the economic benefits of the refining and ethylene industry chain.

[0004] Among the existing conventional cracking furnace preheating air treatment schemes, the Chinese patent with application number CN116981880A and name "Method and System for Steam Cracking" specifically discloses the operation process as follows: 1. The system uses an electric cracking furnace without a convection zone. Conventional cracking furnaces usually include a convection zone to recover heat, but this system eliminates the convection section by using electrical energy; 2. The gas coming out of the electric cracking furnace is cooled in a quenching cooling unit, which includes multiple cooling steps arranged in any order to effectively control the gas temperature; 3. A two-step cooling process is adopted: in the first step, the gas is cooled using boiler feed water at a pressure of 30-175 bar; in the second step, it is further cooled and heated to 350-750°C to form a superheated hydrocarbon feed and steam mixture; 4. The method of ensuring minimum heat loss and optimal use of energy is emphasized. The system achieves high thermal efficiency through integrated technology without the need for traditional heat recovery systems such as convection zones. Therefore, the prior art only considers using a suitable quenching system to cool the cracking products and optimize energy recovery, but does not consider partial cooling of the electric cracking furnace and waste heat recovery of the heat pump system.

[0005] There is currently no corresponding solution to the problem that the waste heat of the partial cooling of the electric cracking furnace and the heat pump system in the relevant technology cannot be fully recovered and utilized.

[0006] Therefore, the inventor, relying on his many years of experience and practice in related industries, proposes a heat recovery system and method for an electric cracking furnace to overcome the defects of the prior art. Summary of the invention

[0007] The purpose of the present invention is to provide a heat recovery system and method for an electric cracking furnace, which adopts electric heating to provide a heat source for the cracking reaction, can achieve zero carbon dioxide emissions, and through optimizing the system and process flow, realize heat recovery of the electric cracking furnace cooling and heat pump system, thereby reducing energy consumption and operating costs.

[0008] The purpose of the present invention can be achieved by adopting the following scheme:

[0009] The present invention provides a heat recovery system for an electric cracking furnace, the heat recovery system for the electric cracking furnace comprising a preheater, a mixer, an electric superheater, an electric cracking furnace and a quenching device connected in sequence.

[0010] The preheater is used to preheat the hydrocarbon feedstock distributed therein by the feedstock distribution device to obtain a preheated stream;

[0011] The mixer is used to mix the preheated stream with the steam stream transported to the mixer to obtain a mixed stream of raw material and steam;

[0012] The electric superheater is used to heat the mixed flow of the raw material and steam to obtain a superheated flow;

[0013] The electric cracking furnace is used to crack the superheated stream to obtain a first cracked stream;

[0014] The quenching device is used to quench the first cracking stream to obtain a second cracking stream.

[0015] In a preferred embodiment of the present invention, the preheater comprises a raw material preheater and an electric preheater, and the raw material preheater and the electric preheater are sequentially connected between the raw material distribution device and the electric preheater;

[0016] The feedstock preheater cooperates with the electric preheater to preheat the hydrocarbon feedstock to obtain a preheated stream.

[0017] In a preferred embodiment of the present invention, the mixer is connected to a steam cascade utilization system, and the mixer is used to receive dilution steam and / or medium-pressure steam output by the steam cascade utilization system to mix the dilution steam and / or the medium-pressure steam with the preheating logistics and obtain the raw material and steam mixture flow.

[0018] In a preferred embodiment of the present invention, the heat recovery system of the electric cracking furnace includes a waste boiler system, the quenching device, the waste boiler system and the steam cascade utilization system are connected in sequence, and the waste boiler system is used to recover the heat of the quenching device and transport the generated steam to the steam cascade utilization system.

[0019] In a preferred embodiment of the present invention, the heat recovery system of the electric cracking furnace also includes a decoking air conveying device, which connects the steam cascade utilization system and the furnace tube of the electric cracking furnace. The decoking air conveying device is used to mix the decoking air with steam and then convey it into the furnace tube to remove the coke layer on the inner wall of the furnace tube.

[0020] In a preferred embodiment of the present invention, the heat recovery system of the electric cracking furnace also includes an energy storage system, which is connected between the steam cascade utilization system and the electric cracking furnace. The energy storage system stores energy in the steam cascade utilization system and transmits it to the electric cracking furnace.

[0021] In a preferred embodiment of the present invention, the heat recovery system of the electric cracking furnace also includes a cooling and heat pump system, which is connected to the electric cracking furnace and is used to cool the gas in the electric cracking furnace.

[0022] In a preferred embodiment of the present invention, the cooling and heat pump system includes a first heat exchanger, a first buffer tank, a first compressor and a second heat exchanger, the first heat exchanger performs heat exchange with the heat generated by the power supply and the electric heating element in the electric cracking furnace through a heat exchange pipeline, the first heat exchanger, the first buffer tank, the first compressor and the second heat exchanger are connected in sequence, and the second heat exchanger performs heat exchange with the raw material preheater through a heat exchange pipeline to provide the raw material preheater with at least part of the heat required for preheating.

[0023] In a preferred embodiment of the present invention, the cooling and heat pump system also includes a second buffer tank, which is arranged between the second heat exchanger and the first heat exchanger, and a first throttle valve is arranged on the pipeline connecting the second buffer tank and the first heat exchanger.

[0024] In a preferred embodiment of the present invention, the cooling and heat pump system also includes a third heat exchanger, a third buffer tank, a second compressor, a first steam generator and a second steam generator. The third heat exchanger exchanges heat with the quenching device through a heat exchange pipeline. The third heat exchanger, the third buffer tank, the second compressor, the first steam generator and the second steam generator are connected in sequence, and the first steam generator and the second steam generator are respectively connected to the mixer to provide medium-pressure steam and dilution steam to the mixer, respectively.

[0025] In a preferred embodiment of the present invention, the cooling and heat pump system also includes a fourth buffer tank, the inlet of the fourth buffer tank is connected to the outlet of the first steam generator and the outlet of the second steam generator respectively, the outlet of the fourth buffer tank is connected to the inlet of the third heat exchanger, and a second throttle valve is arranged between the fourth buffer tank and the third heat exchanger.

[0026] In a preferred embodiment of the present invention, the steam cascade utilization system is connected to the first compressor and the second compressor respectively to supply energy to the first compressor and the second compressor respectively.

[0027] The present invention provides a method for recovering heat from an electric cracking furnace, the method comprising the following steps:

[0028] preheating the hydrocarbon feedstock to obtain a preheated stream;

[0029] mixing the preheated stream with a steam stream to obtain a mixed stream of feedstock and steam;

[0030] heating the mixed stream of raw material and steam to obtain a superheated stream;

[0031] The superheated stream is cracked by an electric cracking furnace to obtain a first cracked stream;

[0032] The first cracked stream is rapidly cooled to obtain a second cracked stream.

[0033] In a preferred embodiment of the present invention, after the first cracked stream is rapidly cooled to obtain a second cracked stream, the second cracked stream is sent to a post-separation device.

[0034] In a preferred embodiment of the present invention, the preheated stream is mixed with a steam stream to obtain a mixed stream of raw material and steam, comprising:

[0035] The mixer receives the dilution steam and / or the intermediate pressure steam output by the steam cascade utilization system;

[0036] The dilution steam and / or the intermediate-pressure steam are mixed with the preheated stream in the mixer to obtain the feedstock and steam mixed stream.

[0037] In a preferred embodiment of the present invention, a quenching device is used to quench the first cracking stream, the heat of the quenching device is recovered through a waste boiler system, and the generated steam is transported to the steam cascade utilization system.

[0038] In a preferred embodiment of the present invention, a decoking air conveying device is used to mix decoking air with steam and convey the mixed air to the furnace tube of the electric cracking furnace to remove the coke layer on the inner wall of the furnace tube.

[0039] In a preferred embodiment of the present invention, an energy storage system is used to store the energy in the steam cascade utilization system and transmit it to the electric cracking furnace.

[0040] In a preferred embodiment of the present invention,

[0041] Providing power from the electric cracking furnace and heat from the electric heating element to a first compressor to obtain a first heat pump stream;

[0042] The first heat pump stream supplies heat to the hydrocarbon feedstock through the second heat exchanger for preheating.

[0043] In a preferred embodiment of the present invention,

[0044] providing heat from the quenching device to a second compressor to obtain a second heat pump stream;

[0045] The second heat pump stream provides medium-pressure steam and dilution steam to the mixer through the first steam generator and the second steam generator respectively.

[0046] In a preferred embodiment of the present invention, the energy obtained in the steam stage utilization system is provided to the first compressor and the second compressor to drive the first compressor and the second compressor.

[0047] As described above, the characteristics and advantages of the heat recovery system and method for electric cracking furnace of the present invention are:

[0048] In the process of electric cracking, the hydrocarbon feedstock is first preheated to obtain a preheated stream; the preheated stream is mixed with a steam stream to obtain a feedstock and steam mixed stream; the feedstock and steam mixed stream is then heated to obtain a superheated stream; the superheated stream is cracked by an electric cracking furnace to obtain a first cracked stream; and then the first cracked stream is rapidly cooled to obtain a second cracked stream. In the entire heating and cracking process, electric heating is used to provide a heat source for the cracking reaction, which can achieve zero carbon dioxide emissions, and realize heat recovery for the cooling of the electric cracking furnace and the heat pump system, reducing energy consumption and operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0050] in:

[0051] Figure 1 : is one of the structural schematic diagrams of the heat recovery system of the electric cracking furnace of the present invention.

[0052] Figure 2 : It is the second structural schematic diagram of the heat recovery system of the electric cracking furnace of the present invention.

[0053] Figure 3 :for Figure 2 Schematic diagram of the structure of the cooling and heat pump system.

[0054] Figure 4 : It is the third structural schematic diagram of the heat recovery system of the electric cracking furnace of the present invention.

[0055] Figure 5 :for Figure 3 Schematic diagram of the structure of the cooling and heat pump system.

[0056] Figure 6 : This is the fourth structural schematic diagram of the heat recovery system of the electric cracking furnace of the present invention.

[0057] Figure 7 :For the present invention Figure 6 Schematic diagram of the structure of the cooling and heat pump system.

[0058] The accompanying drawings in the present invention are:

[0059] 1. Raw material distribution device; 2. Preheater;

[0060] 201. Raw material preheater; 202. Electric preheater;

[0061] 3. Mixer; 4. Electric superheater;

[0062] 5. Electric cracking furnace; 501. Power supply;

[0063] 502. Electric heating element; 6. Rapid cooling device;

[0064] 601. High temperature section; 602. Low temperature section;

[0065] 7. Post-separation device; 8. Sewage treatment system;

[0066] 9. Steam cascade utilization system; 10. Waste boiler system;

[0067] 11. Replacement gas system; 12. Cooling and heat pump system;

[0068] 121. Low-temperature heat pump device; 122. High-temperature heat pump device;

[0069] 1201. a first heat exchanger; 1202. a first buffer tank;

[0070] 1203, a first compressor; 1204, a second heat exchanger;

[0071] 1205. A second buffer tank; 1206. A first throttle valve;

[0072] 1207. a third heat exchanger; 1208. a third buffer tank;

[0073] 1209, a second compressor; 1210, a first steam generator;

[0074] 1211. a second steam generator; 1212. a fourth buffer tank;

[0075] 1213. Second throttle valve; 13. Flare system;

[0076] 14. Energy storage system. DETAILED DESCRIPTION

[0077] The existing cracking furnace uses a mixture of fuel gas and air for combustion, and the high-temperature flue gas generated provides heat for the cracking reaction, but the large amount of carbon dioxide generated will be discharged into the atmosphere with the flue gas. The present invention uses electric heating to provide a heat source for the cracking furnace (i.e., an electric cracking furnace), and no flue gas is generated, thereby achieving near-zero emissions of carbon dioxide.

[0078] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0079] Implementation Method 1

[0080] like Figures 1 to 7As shown, the present invention provides a heat recovery system for an electric cracking furnace, which comprises a preheater 2, a mixer 3, an electric superheater 4, an electric cracking furnace 5 and a quenching device 6 connected in sequence. The preheater 2 is used to preheat the hydrocarbon raw material distributed by the raw material distribution device 1 to obtain a preheated stream; the mixer 3 is used to mix the preheated stream with the steam stream transported to the mixer 3 to obtain a raw material and steam mixed stream; the electric superheater 4 is used to heat the raw material and steam mixed stream to obtain a superheated stream; the electric cracking furnace 5 is used to crack the superheated stream to obtain a first cracked stream; the quenching device 6 is used to rapidly cool the first cracked stream to obtain a second cracked stream, and the obtained second cracked stream can be transported to the post-separation device 7 for separation and discharge.

[0081] The preheater 2 of the present invention preheats the hydrocarbon feedstock introduced therein. If the hydrocarbon feedstock is in liquid phase or partially in liquid phase, the hydrocarbon feedstock is completely vaporized by preheating so that it can be fully mixed with the steam flow in the subsequent mixer 3; if the hydrocarbon feedstock is in gas phase, the temperature drop will not be too large after the hydrocarbon feedstock is mixed with the steam flow by preheating. The preheating of the hydrocarbon feedstock can effectively reduce the load of the subsequent electric superheater 4 and the electric cracking furnace 5, and improve the electric cracking efficiency. After passing through the preheater 2, the temperature of the preheated flow obtained is 150-300°C. In the present invention, the hydrocarbon feedstock can be but not limited to ethane, propane, liquefied petroleum gas, naphtha, diesel, and hydrogenated tail oil.

[0082] In the present invention, after the preheated material flow and the steam material flow are mixed in the mixer 3, the raw material and steam mixed flow are heated to 500-650°C in the electric superheater 4, and after reaching the preset temperature, they are introduced into the electric cracking furnace 5 for cracking treatment.

[0083] Further, such as Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the preheater 2 includes a raw material preheater 201 and an electric preheater 202, which are sequentially connected between the raw material distribution device 1 and the electric preheater 2; the raw material preheater 201 and the electric preheater 202 cooperate to preheat the hydrocarbon raw material to obtain a preheated logistics. Among them, the raw material preheater 201 can be a steam preheater, which is connected to the raw material preheater 201 through the cooling and heat pump system 12 of the electric cracking furnace 5, so as to transport hot steam to the raw material preheater 201, and the hydrocarbon raw material can be preheated by the hot steam first. After the preset temperature (150-300°C) of the preheated logistics is not reached, the hydrocarbon raw material can be preheated by the electric preheater 202. The system waste heat can be fully utilized through the raw material preheater 201 to achieve the purpose of reducing energy consumption.

[0084] In an optional embodiment of the present invention, Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the heat recovery system of the electric cracking furnace includes a waste boiler system 10, a quenching device 6, a waste boiler system 10 and a steam cascade utilization system 9 connected in sequence, the waste boiler system 10 is used to recover the heat of the quenching device 6, and to transport the generated steam to the steam cascade utilization system 9; the mixer 3 is connected to the steam cascade utilization system 9, and the mixer 3 is used to receive the dilution steam and / or medium-pressure steam output by the steam cascade utilization system 9, so as to mix the dilution steam and / or medium-pressure steam with the preheating stream, and obtain a raw material and steam mixed stream. Specifically, the cracking gas (i.e., the first cracking stream) generated in the electric cracking furnace 5 is introduced into the quenching device 6 to quickly reduce the temperature of the cracking gas, maximize the recovery rate of ethylene in the cracking gas and recover the waste heat in the cracking gas; the recovered waste heat is transported to the waste boiler system 10 through the quenching device 6, and the waste boiler system 10 recovers the waste heat and emits high-grade steam (350-450°C), thereby improving the energy utilization rate and reducing energy consumption by recovering the waste heat. Since the waste boiler system 10 is connected to the steam cascade utilization system 9, the high-grade steam in the waste boiler system 10 is transported to the steam cascade utilization system 9, and the steam cascade utilization system 9 reduces the pressure and temperature of the high-grade steam, and generates medium-pressure steam and / or dilution steam, and returns the medium-pressure steam and / or dilution steam to the mixer 3 for mixing with the preheated hydrocarbon feedstock, so that the steam generated by the entire system can be circulated within the system, and the need for external steam or a reduction in the amount of external steam can be achieved, thereby reducing the energy consumption caused by the external steam; at the same time, it can provide a driving source for the first compressor in the cooling and heat pump system 12 described below (this part is explained in the following content).

[0085] Furthermore, the waste boiler system 10 is supplied with boiler feed water from the outside, and the boiler feed water in the waste boiler system 10 is transported to the quenching device 6. After the boiler feed water enters the quenching device 6 and undergoes heat exchange, it is mixed with part of the steam in the quenching device 6 and then returned to the waste boiler system 10. The waste boiler system 10 also emits high-grade steam (350-450°C) to supply the steam cascade utilization system 9.

[0086] In the present invention, the steam cascade utilization system 9 may be but is not limited to a plurality of temperature and pressure reducing devices and / or a plurality of superheaters, which cooperate to reduce the pressure and temperature of the high-pressure steam into the pressure range required by the dilution steam, the medium-pressure steam and the energy storage system 14 described below according to actual production needs.

[0087] In the present invention, the quenching device 6 can adopt the quenching facilities in the existing cracking furnace technology (such as a linear quencher). Further, the quenching device 6 has a high temperature section and a low temperature section, wherein the high temperature section can reduce the temperature of the first cracking stream from 800-900°C to 450-550°C, that is, obtain a second cracking stream of 450-550°C; the low temperature section can reduce the temperature of the first cracking stream from 450-550°C to 150-300°C, that is, obtain a second cracking stream of 150-300°C. In the actual working process, different temperature sections can be selected according to actual needs to quench the first cracking stream.

[0088] In an optional embodiment of the present invention, Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the heat recovery system of the electric cracking furnace also includes a decoking air conveying device (not shown), which connects the steam cascade utilization system 9 and the furnace tube of the electric cracking furnace 5. The decoking air conveying device is used to mix the decoking air with steam and then convey it to the furnace tube to remove the coke layer on the inner wall of the furnace tube. In the actual working process, the cracking reaction will inevitably cause a coking reaction in the furnace tube of the electric cracking furnace 5 to produce a coking layer. As the cracking reaction proceeds, the thickness of the coking layer gradually increases, so it is necessary to perform a decoking process on the furnace tube of the electric cracking furnace 5; during the decoking process, it is necessary to stop the introduction of raw materials into the system, and to feed decoking air into the system through the decoking air conveying device. The decoking air and the dilution steam and / or medium-pressure steam conveyed by the steam cascade utilization system 9 are heated and fully mixed in the electric preheater 202, the mixer 3 and the electric superheater 4 in turn, and then enter the electric cracking furnace 5, and a coking reaction occurs in the furnace tube of the electric cracking furnace 5 to achieve the purpose of removing the coke layer on the inner wall of the furnace tube. The decoking air is mixed with steam for decoking, which can make the reaction smooth and avoid excessive reaction, so as to protect the furnace tube. The above-mentioned coking reaction and charring reaction are both in the working process of the electric cracking furnace 5, and the generation of the coke layer and the removal of the coke layer are both conventional decoking solutions, which will not be described in detail here.

[0089] In an optional embodiment of the present invention, Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the heat recovery system of the electric cracking furnace also includes a replacement gas system 11, which is connected to the electric cracking furnace 5 and is used to replace the gas in the electric cracking furnace 5. The gas replaced between the replacement gas system 11 and the electric cracking furnace 5 is an inert gas (such as nitrogen, argon, etc.), ensuring that the inert gas is always in a circulating flow state between the replacement gas system 11 and the electric cracking furnace 5, creating a reaction environment in the electric cracking furnace 5.

[0090] In an optional embodiment of the present invention, Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the heat recovery system of the electric cracking furnace also includes a flare system 13, and the electric cracking furnace 5 is connected to the flare system 13. The flare system 13 is used to receive materials or cracking gases that cannot be processed in the electric cracking furnace 5 in an emergency, and burn them through the flare system 13. Among them, the flare system 13 can adopt an existing flare system (such as an elevated flare, a ground flare, etc.), and the specific flare form adopted needs to be determined according to factors such as the gas processing volume, geographical conditions, and environmental protection requirements. The flare system 13 burns the combustible and toxic gases and steam generated by the electric cracking to ensure safe production and reduce environmental pollution.

[0091] In an optional embodiment of the present invention, Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the heat recovery system of the electric cracking furnace also includes an energy storage system 14, which is connected between the steam cascade utilization system 9 and the electric cracking furnace 5. The energy storage system 14 stores the energy in the steam cascade utilization system 9 and transmits it to the electric cracking furnace 5. The energy storage system 14 can be, but is not limited to, a steam accumulator, which collects the hot steam in the steam cascade utilization system 9 and transmits the collected hot steam to the electric cracking furnace 5. In case of special working conditions such as power failure, the energy storage system 14 supplies energy to the electric cracking furnace 5, thereby ensuring that the furnace tube temperature does not drop too quickly.

[0092] In an optional embodiment of the present invention, Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the heat recovery system of the electric cracking furnace also includes a sewage treatment system 8, which is connected to the electric cracking furnace 5 and is used to discharge pollutants after purging or cooling the electric cracking furnace 5. The specific structure and sewage discharge form of the sewage treatment system 8 are not limited here, and it is sufficient to achieve the purging of the electric cracking furnace 5 and the discharge of pollutants.

[0093] In an optional embodiment of the present invention, Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the heat recovery system of the electric cracking furnace also includes a cooling and heat pump system 12, which is connected to the electric cracking furnace 5 and is used to cool the gas in the electric cracking furnace 5.

[0094] In a specific embodiment of the present invention, Figure 2 ,3 As shown, the cooling and heat pump system 12 includes a first heat exchanger 1201, a first buffer tank 1202, a first compressor 1203, a second heat exchanger 1204 and a second buffer tank 1205. The first heat exchanger 1201 performs heat exchange with the heat generated by the power supply 501 and the electric heating element 502 in the electric cracking furnace 5 through a heat exchange pipeline. The first heat exchanger 1201, the first buffer tank 1202, the first compressor 1203 and the second heat exchanger 1204 are connected in sequence, and the second heat exchanger 1204 performs heat exchange with the raw material preheater 201 through a heat exchange pipeline to provide at least part of the heat required for preheating the raw material preheater 201. The inlet of the second buffer tank 1205 is connected to the outlet of the second heat exchanger 1204 through a pipeline, and the outlet of the second buffer tank 1205 is connected to the inlet of the first heat exchanger 1201 through a pipeline, and a first throttle valve 1206 is provided on the pipeline connecting the second buffer tank 1205 and the first heat exchanger 1201. During operation, the heat obtained by heat exchange between the first heat exchanger 1201 and the power supply 501 and the electric heating element 502 of the electric cracking furnace 5 is recovered through the first buffer tank 1202, and then sent to the first compressor 1203 to obtain a high-grade first heat pump logistics. The high-grade first heat pump logistics can be heat-exchanged with the raw material preheater 201 through the second heat exchanger 1204, thereby providing heat for the raw material preheater 201 for preheating the hydrocarbon raw material; and the low-temperature logistics after heat exchange enters the second buffer tank 1205. Under the control of the first throttle valve 1206, the low-temperature logistics can be sent to the first heat exchanger 1201 and then heat-exchanged with the heat generated by the power supply 501 and the electric heating element 502 in the electric cracking furnace 5 to achieve the purpose of circulation operation.

[0095] In another specific embodiment of the present invention, Figure 4 , 5 As shown, the cooling and heat pump system 12 includes a low-temperature heat pump device 121 and a high-temperature heat pump device 122 .

[0096] Among them, Figure 4 , 5As shown, the low-temperature heat pump device 121 includes a first heat exchanger 1201, a first buffer tank 1202, a first compressor 1203, a second heat exchanger 1204 and a second buffer tank 1205. The first heat exchanger 1201 performs heat exchange with the heat generated by the power supply 501 and the electric heating element 502 in the electric cracking furnace 5 through a heat exchange pipeline. The first heat exchanger 1201, the first buffer tank 1202, the first compressor 1203 and the second heat exchanger 1204 are connected in sequence, and the second heat exchanger 1204 performs heat exchange with the raw material preheater 201 through a heat exchange pipeline to provide at least part of the heat required for preheating the raw material preheater 201. The inlet of the second buffer tank 1205 is connected to the outlet of the second heat exchanger 1204 through a pipeline, and the outlet of the second buffer tank 1205 is connected to the inlet of the first heat exchanger 1201 through a pipeline, and a first throttle valve 1206 is provided on the pipeline connecting the second buffer tank 1205 and the first heat exchanger 1201. During operation, the heat obtained by heat exchange between the first heat exchanger 1201 and the power supply 501 and the electric heating element 502 of the electric cracking furnace 5 is recovered through the first buffer tank 1202, and then sent to the first compressor 1203 to obtain a high-grade first heat pump logistics. The high-grade first heat pump logistics can be heat-exchanged with the raw material preheater 201 through the second heat exchanger 1204, thereby providing heat for the raw material preheater 201 for preheating the hydrocarbon raw material; and the low-temperature logistics after heat exchange enters the second buffer tank 1205. Under the control of the first throttle valve 1206, the low-temperature logistics can be sent to the first heat exchanger 1201 and then heat-exchanged with the heat generated by the power supply 501 and the electric heating element 502 in the electric cracking furnace 5 to achieve the purpose of circulation operation.

[0097] Among them, Figure 4 , 5As shown, along the flow direction of the raw materials, the quenching device 6 includes a high-temperature section 601 and a low-temperature section 602 connected in sequence; the high-temperature heat pump device 122 includes a third heat exchanger 1207, a third buffer tank 1208, a second compressor 1209, a first steam generator 1210, a second steam generator 1211 and a fourth buffer tank 1212, the third heat exchanger 1207 exchanges heat with the low-temperature section 602 of the quenching device 6 through a heat exchange pipeline, the third heat exchanger 1207, the third buffer tank 1208, the second compressor 1209, the first steam generator 1210 and the second steam generator 1211 are connected in sequence, and the first steam generator 1210 and the second steam generator 1211 are respectively connected to the mixer 3 to provide medium-pressure steam and dilution steam to the mixer 3 respectively. The inlet of the fourth buffer tank 1212 is connected to the outlet of the first steam generator 1210 and the outlet of the second steam generator 1211 respectively, and the outlet of the fourth buffer tank 1212 is connected to the inlet of the third heat exchanger 1207. A second throttle valve 1213 is provided between the fourth buffer tank 1212 and the third heat exchanger 1207. During operation, the heat of the low temperature section 602 of the quenching device 6 is recovered through the third buffer tank 1208, and then sent to the second compressor 1209 to obtain a high-quality second heat pump logistics, which can provide medium-pressure steam and dilution steam to the mixer 3 through the first steam generator 1210 and the second steam generator 1211 respectively; and the low-temperature logistics after heat exchange enters the fourth buffer tank 1212, and under the control of the second throttle valve 1213, the low-temperature logistics can be sent to the third heat exchanger 1207 and then heat exchanged with the low temperature section 602 of the quenching device 6 to achieve the purpose of circulation.

[0098] In another specific embodiment of the present invention, Figure 6 , 7 As shown, the cooling and heat pump system 12 includes a low-temperature heat pump device 121 and a high-temperature heat pump device 122 .

[0099] Among them, Figure 6 , 7As shown, the low-temperature heat pump device 121 includes a first heat exchanger 1201, a first buffer tank 1202, a first compressor 1203, a second heat exchanger 1204 and a second buffer tank 1205. The first heat exchanger 1201 performs heat exchange with the heat generated by the power supply 501 and the electric heating element 502 in the electric cracking furnace 5 through a heat exchange pipeline. The first heat exchanger 1201, the first buffer tank 1202, the first compressor 1203 and the second heat exchanger 1204 are connected in sequence, and the second heat exchanger 1204 performs heat exchange with the raw material preheater 201 through a heat exchange pipeline to provide at least part of the heat required for preheating the raw material preheater 201. The inlet of the second buffer tank 1205 is connected to the outlet of the second heat exchanger 1204 through a pipeline, and the outlet of the second buffer tank 1205 is connected to the inlet of the first heat exchanger 1201 through a pipeline, and a first throttle valve 1206 is provided on the pipeline connecting the second buffer tank 1205 and the first heat exchanger 1201. During operation, the heat obtained by heat exchange between the first heat exchanger 1201 and the power supply 501 and the electric heating element 502 of the electric cracking furnace 5 is recovered through the first buffer tank 1202, and then sent to the first compressor 1203 to obtain a high-grade first heat pump logistics. The high-grade first heat pump logistics can be heat-exchanged with the raw material preheater 201 through the second heat exchanger 1204, thereby providing heat for the raw material preheater 201 for preheating the hydrocarbon raw material; and the low-temperature logistics after heat exchange enters the second buffer tank 1205. Under the control of the first throttle valve 1206, the low-temperature logistics can be sent to the first heat exchanger 1201 and then heat-exchanged with the heat generated by the power supply 501 and the electric heating element 502 in the electric cracking furnace 5 to achieve the purpose of circulation operation.

[0100] Among them, Figure 6 , 7As shown, along the flow direction of the raw materials, the quenching device 6 includes a high-temperature section 601 and a low-temperature section 602 connected in sequence; the high-temperature heat pump device 122 includes a third heat exchanger 1207, a third buffer tank 1208, a second compressor 1209, a first steam generator 1210, a second steam generator 1211 and a fourth buffer tank 1212, the third heat exchanger 1207 exchanges heat with the low-temperature section 602 of the quenching device 6 through a heat exchange pipeline, the third heat exchanger 1207, the third buffer tank 1208, the second compressor 1209, the first steam generator 1210 and the second steam generator 1211 are connected in sequence, and the first steam generator 1210 and the second steam generator 1211 are respectively connected to the mixer 3 to provide medium-pressure steam and dilution steam to the mixer 3 respectively. The inlet of the fourth buffer tank 1212 is connected to the outlet of the first steam generator 1210 and the outlet of the second steam generator 1211 respectively, and the outlet of the fourth buffer tank 1212 is connected to the inlet of the third heat exchanger 1207. A second throttle valve 1213 is provided between the fourth buffer tank 1212 and the third heat exchanger 1207. During operation, the heat of the low temperature section 602 of the quenching device 6 is recovered through the third buffer tank 1208, and then sent to the second compressor 1209 to obtain a high-quality second heat pump logistics, which can provide medium-pressure steam and dilution steam to the mixer 3 through the first steam generator 1210 and the second steam generator 1211 respectively; and the low-temperature logistics after heat exchange enters the fourth buffer tank 1212, and under the control of the second throttle valve 1213, the low-temperature logistics can be sent to the third heat exchanger 1207 and then heat exchanged with the low temperature section 602 of the quenching device 6 to achieve the purpose of circulation.

[0101] Among them, the steam cascade utilization system 9 is connected to the first compressor 1203 and the second compressor 1209 respectively. The steam cascade utilization system 9 can reduce the pressure of the high-grade steam transported in the waste boiler system 10. The energy obtained by the steam cascade utilization system 9 can be provided to the first compressor 1203 and the second compressor 1209 respectively, so as to drive the first compressor 1203 and the second compressor 1209, thereby reducing the energy consumption required by the first compressor 1203 and the second compressor 1209.

[0102] The characteristics and advantages of the heat recovery system of the electric cracking furnace of the present invention are:

[0103] 1. The heat recovery system and method of the electric cracking furnace can ensure the long-term stable operation of the electric cracking furnace.

[0104] 2. The heat recovery system and method of the electric cracking furnace adopt electric heating to provide the cracking furnace with the heat required for the cracking reaction, reduce carbon dioxide to achieve near-zero emissions, and meet emission standards.

[0105] 3. In the heat recovery system and method of the electric cracking furnace, the cooling and heat pump system 12 includes a low-temperature heat pump device 121 and a high-temperature heat pump device 122, which can be used to recover the waste heat in the electric cracking furnace 5 and the quenching device 6 respectively, and return the waste heat to the raw material preheater 201 for preheating the raw material, thereby effectively reducing energy consumption.

[0106] 4. The heat recovery system and method of the electric cracking furnace are adaptively designed for the electric heating method of the cracking furnace, while taking into account the requirements for recovering waste heat from the cracking furnace to reduce energy consumption, thereby improving the design quality and saving cost investment.

[0107] Implementation Method 2

[0108] The present invention provides a heat recovery method for an electric cracking furnace, which uses the above-mentioned heat recovery system for an electric cracking furnace to perform cracking treatment on hydrocarbon raw materials. The heat recovery method for an electric cracking furnace comprises the following steps:

[0109] Step S1: preheating the hydrocarbon feedstock to obtain a preheated stream;

[0110] Step S2: mixing the preheated stream with the steam stream to obtain a mixed stream of raw material and steam;

[0111] Step S3: heating the mixed flow of raw material and steam to obtain a superheated flow;

[0112] Step S4: cracking the superheated stream by the electric cracking furnace 5 to obtain a first cracked stream;

[0113] Step S5: Rapidly cool the first cracked stream to obtain a second cracked stream.

[0114] In an optional embodiment of the present invention, after step S5, step S6 is further included: sending the second cracking stream to the post-separation device 7 for separation and discharge.

[0115] In an optional embodiment of the present invention, step S2 includes:

[0116] Step S201: The mixer receives the dilution steam and / or medium-pressure steam output by the steam cascade utilization system 9;

[0117] Step S202: Mix the dilution steam and / or medium-pressure steam with the preheating flow in the mixer 3 to obtain a mixed flow of raw materials and steam.

[0118] In an optional embodiment of the present invention, in step S5, a quenching device 6 is used to quench the first cracking flow, the heat of the quenching device 6 is recovered through a waste boiler system 10, and the generated steam is transported to a steam cascade utilization system 9.

[0119] In an optional embodiment of the present invention, during the working process (i.e., in steps S1 to S6), a decoking air conveying device is used to mix the decoking air with steam and then convey it to the furnace tube of the electric cracking furnace 5 to remove the coke layer on the inner wall of the furnace tube.

[0120] In an optional embodiment of the present invention, during the working process (ie, in step S4 to step S6 ), the energy storage system 14 is used to store the energy in the steam cascade utilization system 9 and transmit it to the electric cracking furnace 5 .

[0121] In an optional embodiment of the present invention, during the operation (i.e., in step S4 to step S6), the heat of the power supply 501 and the electric heating element 502 of the electric cracking furnace 5 is provided to the first compressor 1203 to obtain the first heat pump stream; the first heat pump stream supplies heat to the hydrocarbon feedstock through the second heat exchanger 1204 for preheating. Specifically, Figure 2 , 3 As shown, the heat obtained by the heat exchange between the first heat exchanger 1201 and the power supply 501 and the electric heating element 502 of the electric cracking furnace 5 is recovered through the first buffer tank 1202, and then sent to the first compressor 1203 to obtain a high-grade first heat pump logistics. The high-grade first heat pump logistics can be heat-exchanged with the raw material preheater 201 through the second heat exchanger 1204, thereby providing heat for the raw material preheater 201 for preheating the hydrocarbon raw material; and the low-temperature logistics after the heat exchange enters the second buffer tank 1205. Under the control of the first throttle valve 1206, the low-temperature logistics can be sent to the first heat exchanger 1201 and then heat-exchanged with the heat generated by the power supply 501 and the electric heating element 502 in the electric cracking furnace 5 to achieve the purpose of circulation.

[0122] In an optional embodiment of the present invention, during the working process (i.e., in step S4 to step S6), the heat of the quenching device 6 is provided to the second compressor 1209 to obtain the second heat pump stream; the second heat pump stream provides medium-pressure steam and dilution steam to the mixer 3 through the first steam generator 1210 and the second steam generator 1211 respectively. Specifically, Figure 4 , Figure 5 As shown, the heat of the low-temperature section 602 of the quenching device 6 is recovered through the third buffer tank 1208, and then sent to the second compressor 1209 to obtain a high-quality second heat pump logistics. The high-quality second heat pump logistics can provide medium-pressure steam and dilution steam to the mixer 3 through the first steam generator 1210 and the second steam generator 1211 respectively; and the low-temperature logistics after heat exchange enters the fourth buffer tank 1212. Under the control of the second throttle valve 1213, the low-temperature logistics can be sent to the third heat exchanger 1207 and then exchange heat with the low-temperature section 602 of the quenching device 6 to achieve the purpose of circulation.

[0123] In an optional embodiment of the present invention, during the working process (i.e., in step S4 to step S6), the energy obtained in the steam stage utilization system 9 is provided to the first compressor 1203 and the second compressor 1209 to drive the first compressor 1203 and the second compressor 1209. Specifically, Figure 6 , Figure 7 As shown, the steam cascade utilization system 9 is connected to the first compressor 1203 and the second compressor 1209 respectively. The steam cascade utilization system 9 can reduce the pressure of the high-grade steam transported in the waste boiler system 10. The energy obtained by the steam cascade utilization system 9 can be provided to the first compressor 1203 and the second compressor 1209 respectively to drive the first compressor 1203 and the second compressor 1209, thereby reducing the energy consumption required by the first compressor 1203 and the second compressor 1209.

[0124] The characteristics and advantages of the heat recovery method of the electric cracking furnace of the present invention are:

[0125] 1. The heat recovery method of the electric cracking furnace adopts electric heating to provide a heat source for the cracking reaction during the entire heating and cracking process, which can achieve zero carbon dioxide emissions and realize heat recovery of the electric cracking furnace cooling and heat pump system, thereby achieving the effect of reducing energy consumption and operating costs.

[0126] 2. The heat recovery system and method of the electric cracking furnace can ensure the long-term stable operation of the electric cracking furnace.

[0127] 3. The heat recovery system and method of the electric cracking furnace are adaptively designed for the electric heating method of the cracking furnace, while taking into account the requirements for recovering the waste heat of the cracking furnace to reduce energy consumption, thereby improving the design quality and saving cost investment.

[0128] The heat recovery method for an electric cracking furnace of the present invention has the same characteristics and advantages as the above-mentioned heat recovery system for an electric cracking furnace, which will not be described in detail here.

[0129] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A heat recovery system for an electric cracking furnace, characterized in that: The heat recovery system of the electric cracking furnace comprises a preheater, a mixer, an electric superheater, an electric cracking furnace and a quenching device which are connected in sequence. The preheater is used to preheat the hydrocarbon feedstock distributed therein by the feedstock distribution device to obtain a preheated stream; The mixer is used to mix the preheated stream with the steam stream transported to the mixer to obtain a mixed stream of raw material and steam; The electric superheater is used to heat the mixed flow of the raw material and steam to obtain a superheated flow; The electric cracking furnace is used to crack the superheated stream to obtain a first cracked stream; The quenching device is used to quench the first cracking stream to obtain a second cracking stream.

2. The heat recovery system for an electric cracking furnace according to claim 1, characterized in that: The preheater comprises a raw material preheater and an electric preheater, and the raw material preheater and the electric preheater are sequentially connected between the raw material distribution device and the electric preheater; The feedstock preheater cooperates with the electric preheater to preheat the hydrocarbon feedstock to obtain a preheated stream.

3. The heat recovery system for an electric cracking furnace according to claim 2, characterized in that: The mixer is connected to the steam cascade utilization system, and is used to receive the dilution steam and / or medium-pressure steam output by the steam cascade utilization system to mix the dilution steam and / or the medium-pressure steam with the preheating flow to obtain the raw material and steam mixture flow.

4. The heat recovery system for an electric cracking furnace according to claim 3, characterized in that: The heat recovery system of the electric cracking furnace includes a waste boiler system. The quenching device, the waste boiler system and the steam cascade utilization system are connected in sequence. The waste boiler system is used to recover the heat of the quenching device and transport the generated steam to the steam cascade utilization system.

5. The heat recovery system for an electric cracking furnace according to claim 3, characterized in that: The heat recovery system of the electric cracking furnace also includes a decoking air conveying device, which connects the steam cascade utilization system and the furnace tube of the electric cracking furnace. The decoking air conveying device is used to mix the decoking air with steam and then convey it into the furnace tube to remove the coke layer on the inner wall of the furnace tube.

6. The heat recovery system for an electric cracking furnace according to claim 3, characterized in that: The heat recovery system of the electric cracking furnace also includes an energy storage system, which is connected between the steam cascade utilization system and the electric cracking furnace. The energy storage system stores energy in the steam cascade utilization system and transmits it to the electric cracking furnace.

7. The heat recovery system for an electric cracking furnace according to claim 3, characterized in that: The heat recovery system of the electric cracking furnace also includes a cooling and heat pump system, which is connected to the electric cracking furnace and is used to cool the gas in the electric cracking furnace.

8. The heat recovery system for an electric cracking furnace according to claim 7, characterized in that: The cooling and heat pump system includes a first heat exchanger, a first buffer tank, a first compressor and a second heat exchanger. The first heat exchanger exchanges heat with the heat generated by the power supply and the electric heating element in the electric cracking furnace through a heat exchange pipeline. The first heat exchanger, the first buffer tank, the first compressor and the second heat exchanger are connected in sequence, and the second heat exchanger exchanges heat with the raw material preheater through a heat exchange pipeline to provide the raw material preheater with at least part of the heat required for preheating.

9. The heat recovery system for an electric cracking furnace according to claim 8, characterized in that: The cooling and heat pump system further includes a second buffer tank, which is disposed between the second heat exchanger and the first heat exchanger, and a first throttle valve is disposed on a pipeline connecting the second buffer tank and the first heat exchanger.

10. The heat recovery system for an electric cracking furnace according to claim 8 or 9, characterized in that: The cooling and heat pump system also includes a third heat exchanger, a third buffer tank, a second compressor, a first steam generator and a second steam generator. The third heat exchanger exchanges heat with the quenching device through a heat exchange pipeline. The third heat exchanger, the third buffer tank, the second compressor, the first steam generator and the second steam generator are connected in sequence, and the first steam generator and the second steam generator are respectively connected to the mixer to provide medium-pressure steam and dilution steam to the mixer respectively.

11. The heat recovery system for an electric cracking furnace according to claim 10, characterized in that: The cooling and heat pump system also includes a fourth buffer tank, the inlet of the fourth buffer tank is connected to the outlet of the first steam generator and the outlet of the second steam generator respectively, the outlet of the fourth buffer tank is connected to the inlet of the third heat exchanger, and a second throttle valve is arranged between the fourth buffer tank and the third heat exchanger.

12. The heat recovery system for an electric cracking furnace according to claim 10, characterized in that: The steam stage utilization system is connected to the first compressor and the second compressor, respectively, to supply energy to the first compressor and the second compressor, respectively.

13. A method for recovering heat from an electric cracking furnace, characterized in that: The heat recovery method of the electric cracking furnace comprises the following steps: preheating the hydrocarbon feedstock to obtain a preheated stream; mixing the preheated stream with a steam stream to obtain a mixed stream of feedstock and steam; heating the mixed stream of raw material and steam to obtain a superheated stream; The superheated stream is cracked by an electric cracking furnace to obtain a first cracked stream; The first cracked stream is rapidly cooled to obtain a second cracked stream.

14. The heat recovery method of an electric cracking furnace according to claim 13, characterized in that: After the first cracked stream is rapidly cooled to obtain a second cracked stream, the second cracked stream is sent to a post-separation device.

15. The method for recovering heat from an electric cracking furnace according to claim 13, characterized in that: The step of mixing the preheated stream with the steam stream to obtain a mixed stream of raw material and steam comprises: The mixer receives the dilution steam and / or the intermediate pressure steam output by the steam cascade utilization system; The dilution steam and / or the intermediate-pressure steam are mixed with the preheated stream in the mixer to obtain the feedstock and steam mixed stream.

16. The method for recovering heat from an electric cracking furnace according to claim 15, characterized in that: A quenching device is used to quench the first cracking stream, the heat of the quenching device is recovered through a waste boiler system, and the generated steam is transported to the steam cascade utilization system.

17. The method for recovering heat from an electric cracking furnace according to claim 15, characterized in that: A decoking air conveying device is used to mix decoking air with steam and convey the decoking air to the furnace tube of the electric cracking furnace to remove the coke layer on the inner wall of the furnace tube.

18. The method for recovering heat from an electric cracking furnace according to claim 15, characterized in that: An energy storage system is used to store the energy in the steam cascade utilization system and transmit the energy to the electric cracking furnace.

19. The method for recovering heat from an electric cracking furnace according to claim 16, characterized in that: Providing power from the electric cracking furnace and heat from the electric heating element to a first compressor to obtain a first heat pump stream; The first heat pump stream supplies heat to the hydrocarbon feedstock through the second heat exchanger for preheating.

20. The method for recovering heat from an electric cracking furnace according to claim 19, characterized in that: providing heat from the quenching device to a second compressor to obtain a second heat pump stream; The second heat pump stream provides medium-pressure steam and dilution steam to the mixer through the first steam generator and the second steam generator respectively.

21. The method for recovering heat from an electric cracking furnace according to claim 20, characterized in that: The steam stage utilizes energy obtained in the system to provide to the first compressor and the second compressor to drive the first compressor and the second compressor.

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