Electric cracking furnace heat recovery system and recovery method

Abstract

The application discloses an electric cracking furnace heat recovery system and a recovery method. The electric cracking furnace heat recovery system comprises, which are sequentially connected, an electric preheater, a mixer, an electric superheater, an electric cracking furnace and a quenching device. The electric preheater is used for preheating hydrocarbon raw materials distributed into the electric preheater by a raw material distribution device to obtain a preheated stream. The mixer is used for mixing the preheated stream with a steam stream conveyed into the mixer to obtain a raw material and steam mixed stream. The electric superheater is used for heating the raw material and steam mixed stream to obtain a superheated stream. The electric cracking furnace is used for cracking the superheated stream to obtain a first cracking stream. The quenching device is used for quenching and cooling the first cracking stream to obtain a second cracking stream. The application solves the technical problem that partial cooling of the electric cracking furnace and waste heat of a heat pump system cannot be fully recovered and utilized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat recovery of electrolytic furnaces, in particular to a heat recovery system and method for an electric cracking furnace. BACKGROUND

[0002] With the aggravation of global climate problems, the world attaches more and more importance to slowing down climate change and reducing carbon dioxide emissions. In order to more effectively promote carbon emission reduction and accelerate the construction of a larger carbon trading market system, more industries with high energy consumption, high emissions and relatively concentrated emission sources will be included in the carbon trading market. Low-carbon development requires changes in petrochemical technology and process design, and many fossil fuel-powered industrial processes will be replaced by electricity.

[0003] The chemical industry is a high-energy and high-carbon emission industry, and is one of the main sources of greenhouse gases in the industrial field. The global chemical industry accounts for 5.8% of global total emissions (including 3.6% of industrial energy emissions and 2.2% of direct industrial emissions). With the approaching of the double carbon target, the implementation of relevant carbon emission standards is imperative, and the carbon emission value specified will tend to be more stringent, which will restrict the development of the chemical industry due to carbon emissions. In order to better meet the carbon reduction needs of the petrochemical industry, the development of the core technology of the electric cracking furnace can effectively promote technological innovation and further open up and expand the economic benefits of the refining and ethylene industry chain.

[0004] In the existing conventional cracking furnace preheated air treatment scheme, the Chinese patent with the application number CN116981880A and the name "Method and system for steam cracking" specifically discloses the following operation process: 1. The system uses an electric cracking furnace without a convection zone. Traditional cracking furnaces usually include a convection zone to recover heat, but this system cancels the convection section by using electricity; 2. The gas from 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℃, forming a superheated hydrocarbon feed and steam mixture; 4. The method of ensuring minimum heat loss and optimal use of energy is emphasized, and the system achieves high thermal efficiency through integrated technology without the need for traditional heat recovery systems such as convection zones. Therefore, the existing technology only considers using a suitable quenching system to cool the cracking products and optimize energy recovery, without considering the waste heat recovery of the electric cracking furnace part cooling and heat pump system.

[0005] Currently, there is no corresponding solution to the problem that the waste heat of the electric cracking furnace part cooling and heat pump system cannot be fully recovered and utilized in the related technology.

[0006] Therefore, based on years of experience and practice in related industries, the inventor proposes an electrocracking furnace heat recovery system and method to overcome the shortcomings of existing technologies. Summary of the Invention

[0007] The purpose of this invention is to provide a heat recovery system and method for an electrocracking furnace, which uses electric heating to provide a heat source for the pyrolysis reaction, enabling zero carbon dioxide emissions. Furthermore, by optimizing the system and process flow, it achieves heat recovery from the cooling and heat pump systems of the electrocracking furnace, thereby reducing energy consumption and operating costs.

[0008] The objective of this invention can be achieved through the following methods:

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

[0010] The preheater is used to preheat the hydrocarbon raw materials distributed to it by the raw material distribution device to obtain a preheated material stream;

[0011] The mixer is used to mix the preheated stream with the steam stream fed into the mixer to obtain a raw material and steam mixture stream;

[0012] The electric superheater is used to heat the mixture of raw materials and steam to obtain a superheated material.

[0013] The electro-pyrolysis furnace is used to pyrolyze the superheated stream to obtain a first pyrolyzed stream;

[0014] The quenching device is used to rapidly cool the first pyrolysis stream to obtain a second pyrolysis stream.

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

[0016] The raw material preheater works in conjunction with the electric preheater to preheat the hydrocarbon raw material to obtain a preheated feedstock.

[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 from the steam cascade utilization system, so as to mix the dilution steam and / or the medium-pressure steam with the preheated stream and obtain the raw material and steam mixture stream.

[0018] In a preferred embodiment of the present invention, the electropyrolysis furnace heat recovery system 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.

[0019] In a preferred embodiment of the present invention, the electropyrolysis furnace heat recovery system further includes a coke removal air conveying device, which connects the steam cascade utilization system to the furnace tube of the electropyrolysis furnace. The coke removal air conveying device is used to mix the coke removal 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 electropyrolysis furnace heat recovery system further includes an energy storage system, which is connected between the steam cascade utilization system and the electropyrolysis furnace. The energy storage system stores the energy in the steam cascade utilization system and transmits it to the electropyrolysis furnace.

[0021] In a preferred embodiment of the present invention, the heat recovery system of the electropyrolysis furnace further includes a cooling and heat pump system connected to the electropyrolysis furnace, and the cooling and heat pump system is used to cool the gas inside the electropyrolysis 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 exchanges heat with the power supply and electric heating elements in the electrocracking furnace through heat exchange pipes. 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 heat exchange pipes to provide at least a portion of the heat required for preheating the raw material preheater.

[0023] In a preferred embodiment of the present invention, 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 throttling valve is provided 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 further 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 further includes a fourth buffer tank, the inlet of which is connected to the outlet of the first steam generator and the outlet of the second steam generator, the outlet of which is connected to the inlet of the third heat exchanger, and a second throttling valve is provided 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] This invention provides a method for heat recovery from an electropyrolysis furnace, the method comprising the following steps:

[0028] The hydrocarbon feedstock is preheated to obtain a preheated stream.

[0029] The preheated stream is mixed with the steam stream to obtain a raw material and steam mixture stream;

[0030] The raw material and steam mixture stream is heated to obtain a superheated stream.

[0031] The superheated stream is pyrolyzed in an electro-pyrolysis furnace to obtain a first pyrolyzed stream;

[0032] The first pyrolysis stream is rapidly cooled to obtain the second pyrolysis stream.

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

[0034] In a preferred embodiment of the present invention, the mixing of the preheated stream and the steam stream to obtain a raw material and steam mixture stream includes:

[0035] The mixer receives dilute steam and / or medium-pressure steam output from the steam cascade utilization system;

[0036] The dilution steam and / or the medium-pressure steam are mixed with the preheated stream in the mixer to obtain the raw material and steam mixture stream.

[0037] In a preferred embodiment of the present invention, a quenching device is used to quench and cool the first pyrolysis 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 coke removal air conveying device is used to mix coke removal air with steam and then convey it to the furnace tube of the electrocracking 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 transport it to the electrocracking furnace.

[0040] In a preferred embodiment of the present invention

[0041] The power supply and heat from the electric heating element of the electrocracking furnace are provided to the first compressor to obtain the first heat pump material;

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

[0043] In a preferred embodiment of the present invention

[0044] The heat from the quenching device is supplied to the second compressor to obtain a second heat pump flow.

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

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

[0047] Based on the above, the features and advantages of the electropyrolysis furnace heat recovery system and method of the present invention are as follows:

[0048] In the electrocracking process, the hydrocarbon feedstock is first preheated to obtain a preheated stream; this preheated stream is then mixed with a steam stream to obtain a feedstock-steam mixture stream; this mixture stream is then heated to obtain a superheated stream; the superheated stream is then cracked in an electrocracking furnace to obtain a first cracked stream; finally, the first cracked stream is rapidly cooled to obtain a second cracked stream. Throughout the heating and cracking process, electric heating is used to provide the heat source for the cracking reaction, achieving zero carbon dioxide emissions and enabling heat recovery from the electrocracking furnace cooling and heat pump system, thus reducing energy consumption and operating costs. Attached Figure Description

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

[0050] in:

[0051] Figure 1 This is one of the structural schematic diagrams of the electropyrolysis furnace heat recovery system of the present invention.

[0052] Figure 2 This is the second schematic diagram of the heat recovery system of the electropyrolysis furnace of the present invention.

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

[0054] Figure 4 This is the third schematic diagram of the structure of the electropyrolysis furnace heat recovery system of the present invention.

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

[0056] Figure 6 This is the fourth schematic diagram of the heat recovery system of the electropyrolysis furnace of the present invention.

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

[0058] The reference numerals in the accompanying drawings of this 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. Electrolytic 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. Displacement gas system; 12. Cooling and heat pump system;

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

[0069] 1201, First heat exchanger; 1202, First buffer tank;

[0070] 1203, First compressor; 1204, Second heat exchanger;

[0071] 1205. Second buffer tank; 1206. First throttle valve;

[0072] 1207. Third heat exchanger; 1208. Third buffer tank;

[0073] 1209. Second compressor; 1210. First steam generator;

[0074] 1211. Second steam generator; 1212. Fourth buffer tank;

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

[0076] 14. Energy storage system. Detailed Implementation

[0077] Existing pyrolysis furnaces use a mixture of fuel gas and air for combustion, and the resulting high-temperature flue gas provides heat for the pyrolysis reaction. However, a large amount of carbon dioxide produced will be released into the atmosphere along with the flue gas. This invention uses electric heating to provide a heat source for the pyrolysis furnace (i.e., an electric pyrolysis furnace), which produces no flue gas and achieves near-zero carbon dioxide emissions.

[0078] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be 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 electrocracking furnace, which includes a preheater 2, a mixer 3, an electric superheater 4, an electrocracking furnace 5, and a quenching device 6 connected in sequence. The preheater 2 is used to preheat the hydrocarbon feedstock distributed by the feedstock distribution device 1 to obtain a preheated feedstock; the mixer 3 is used to mix the preheated feedstock with a steam feedstock supplied to the mixer 3 to obtain a feedstock-steam mixture; the electric superheater 4 is used to heat the feedstock-steam mixture to obtain a superheated feedstock; the electrocracking furnace 5 is used to pyrolyze the superheated feedstock to obtain a first pyrolyzed feedstock; and the quenching device 6 is used to rapidly cool the first pyrolyzed feedstock to obtain a second pyrolyzed feedstock, which can be transported to a post-separation device 7 for separation and discharge.

[0081] The preheater 2 of this invention preheats the hydrocarbon feedstock introduced into it. If the hydrocarbon feedstock is liquid or partially liquid, preheating ensures complete vaporization, allowing for thorough mixing with the steam stream in the subsequent mixer 3. If the hydrocarbon feedstock is gaseous, preheating prevents excessive temperature drop after mixing with the steam stream. Preheating the hydrocarbon feedstock effectively reduces the load on the subsequent electric superheater 4 and electrocracking furnace 5, improving electrocracking efficiency. The temperature of the preheated stream obtained after passing through the preheater 2 is 150-300℃. In this invention, the hydrocarbon feedstock can be, but is not limited to, ethane, propane, liquefied petroleum gas, naphtha, diesel oil, and hydrotreated tail oil.

[0082] In this invention, after the preheated material and the steam material are mixed by the mixer 3, the mixture is heated to 500-650°C by the electric superheater 4. After reaching the preset temperature, it is introduced into the electric pyrolysis furnace 5 for pyrolysis treatment.

[0083] Furthermore, 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 work together to preheat the hydrocarbon raw material to obtain a preheated feedstock. The raw material preheater 201 can be a steam preheater, connected to the electric cracking furnace 5 via a cooling and heat pump system 12. This system supplies hot steam to the raw material preheater 201, allowing for initial preheating of the hydrocarbon raw material. If the preset temperature (150-300℃) of the preheated feedstock is not reached, the electric preheater 202 can then be used for further preheating. The raw material preheater 201 fully utilizes the system's waste heat, thus reducing energy consumption.

[0084] In an optional embodiment of the present invention, such as Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the heat recovery system of the electrolytic cracking furnace includes a waste boiler system 10, a quench device 6, and a steam cascade utilization system 9 connected in sequence. The waste boiler system 10 is used to recover the heat from the quench 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 is used to receive the dilution steam and / or medium-pressure steam output from the steam cascade utilization system 9 to mix the dilution steam and / or medium-pressure steam with the preheated stream to obtain a mixture of raw material and steam. Specifically, the cracked gas (i.e., the first cracked stream) generated in the electrolytic cracking furnace 5 is introduced into the quench device 6 to rapidly reduce the temperature of the cracked gas, maximize the recovery rate of ethylene in the cracked gas, and recover the waste heat in the cracked gas. The recovered waste heat is transported to the waste boiler system 10 through the quench device 6. The waste boiler system 10 recovers the waste heat and emits high-grade steam (350-450℃), thereby improving energy utilization and reducing energy consumption through the recovery of 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. The steam cascade utilization system 9 depressurizes and cools the high-grade steam, and generates medium-pressure steam and / or dilution steam. The medium-pressure steam and / or dilution steam are then returned to the mixer 3 for mixing with the preheated hydrocarbon feedstock. This allows the steam generated by the entire system to circulate within the system, eliminating the need for external steam or reducing the amount of external steam, thus reducing the energy consumption caused by external steam. At the same time, it can provide a drive source for the first compressor in the cooling and heat pump system 12 described below (this part will be explained below).

[0085] Furthermore, the waste boiler system 10 supplies boiler feedwater from an external source. The boiler feedwater in the waste boiler system 10 is transported to the quenching device 6. After entering the quenching device 6 and undergoing heat exchange, the boiler feedwater mixes with some of the steam in the quenching device 6 and returns to the waste boiler system 10. The waste boiler system 10 then emits high-grade steam (350-450℃) to supply the steam cascade utilization system 9.

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

[0087] In this invention, the quenching device 6 can employ existing quenching facilities (such as linear quenchers) from pyrolysis furnace technology. Furthermore, the quenching device 6 has a high-temperature section and a low-temperature section. The high-temperature section can reduce the temperature of the first pyrolysis stream from 800-900℃ to 450-550℃, thus obtaining a second pyrolysis stream at 450-550℃. The low-temperature section can reduce the temperature of the first pyrolysis stream from 450-550℃ to 150-300℃, thus obtaining a second pyrolysis stream at 150-300℃. In actual operation, different temperature sections can be selected to quench the first pyrolysis stream according to actual needs.

[0088] In an optional embodiment of the present invention, such as Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the electrocracking furnace heat recovery system also includes a decoking air conveying device (not shown). The decoking air conveying device connects the steam cascade utilization system 9 to the furnace tubes of the electrocracking furnace 5. The decoking air conveying device is used to mix decoking air with steam and then convey it into the furnace tubes to remove the coke layer on the inner wall of the furnace tubes. In actual operation, the pyrolysis reaction inevitably causes a coking reaction in the furnace tubes of the electrocracking furnace 5, producing a coke layer. As the pyrolysis reaction proceeds, the thickness of the coke layer gradually increases, thus requiring decoking treatment of the furnace tubes of the electrocracking furnace 5. During the decoking process, it is necessary to stop the feedstock from entering the system and send decoking air into the system through the decoking air conveying device. The decoking air and the diluted steam and / or medium-pressure steam conveyed by the steam cascade utilization system 9 are heated and fully mixed in sequence through the electric preheater 202, mixer 3 and electric superheater 4 before entering the electrocracking furnace 5. A coking reaction occurs in the furnace tubes of the electrocracking furnace 5 to remove the coke layer on the inner wall of the furnace tubes. Mixing decoking air with steam for decoking treatment can moderate the reaction, preventing it from becoming too violent and thus protecting the furnace tubes. The aforementioned coking and burning reactions are both conventional decoking methods used during the operation of the electropyrolysis furnace 5, and will not be elaborated upon further here.

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

[0090] In an optional embodiment of the present invention, such as Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the electrocracking furnace heat recovery system also includes a flare system 13. The electrocracking furnace 5 is connected to the flare system 13. The flare system 13 is used to receive materials or pyrolysis gases that cannot be processed in the electrocracking furnace 5 in emergency situations and to perform combustion treatment through the flare system 13. The flare system 13 can adopt existing flare systems (such as elevated flares, ground flares, etc.), and the specific flare type adopted needs to be determined based on factors such as gas processing volume, geographical conditions, and environmental protection requirements. The flare system 13 combusts the flammable and toxic gases and vapors generated by electrocracking, ensuring safe production and reducing environmental pollution.

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

[0092] In an optional embodiment of the present invention, such as Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, the electropyrolysis furnace heat recovery system also includes a wastewater treatment system 8, which is connected to the electropyrolysis furnace 5. The wastewater treatment system 8 is used to discharge pollutants after the electropyrolysis furnace 5 has been purged or cooled. The specific structure and discharge method of the wastewater treatment system 8 are not limited here, as long as it can achieve the purging of the electropyrolysis furnace 5 and the discharge of pollutants.

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

[0094] In one specific embodiment of the present invention, such as Figure 1 ,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 exchanges heat with the power supply 501 and electric heating element 502 in the electrocracking furnace 5 through heat exchange pipes. The first heat exchanger 1201, the first buffer tank 1202, the first compressor 1203, and the second heat exchanger 1204 are connected sequentially, and the second heat exchanger 1204 exchanges heat with the raw material preheater 201 through heat exchange pipes to provide at least a portion 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 pipe, and the outlet of the second buffer tank 1205 is connected to the inlet of the first heat exchanger 1201 through a pipe. A first throttle valve 1206 is provided on the pipe connecting the second buffer tank 1205 and the first heat exchanger 1201. During operation, the heat obtained by the first heat exchanger 1201 and the power supply 501 and electric heating element 502 of the electrocracking furnace 5 is recovered through the first buffer tank 1202 and then sent into the first compressor 1203 to obtain a high-grade first heat pump stream. This high-grade first heat pump stream can exchange heat with the raw material preheater 201 through the second heat exchanger 1204, thereby providing heat to the raw material preheater 201 for preheating the hydrocarbon raw material. The low-temperature stream after heat exchange enters the second buffer tank 1205. Under the control of the first throttle valve 1206, the low-temperature stream can be sent into the first heat exchanger 1201 to exchange heat with the power supply 501 and electric heating element 502 in the electrocracking furnace 5 to achieve the purpose of cyclic operation.

[0095] In another specific embodiment of the present invention, such as Figure 2 , 5 As shown, the cooling and heat pump system 12 includes a low-temperature heat pump unit 121 and a high-temperature heat pump unit 122.

[0096] Among them, such as 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 exchanges heat with the power supply 501 and electric heating element 502 in the electrocracking furnace 5 through heat exchange pipes. The first heat exchanger 1201, the first buffer tank 1202, the first compressor 1203, and the second heat exchanger 1204 are connected sequentially, and the second heat exchanger 1204 exchanges heat with the raw material preheater 201 through heat exchange pipes to provide at least a portion 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 pipe, and the outlet of the second buffer tank 1205 is connected to the inlet of the first heat exchanger 1201 through a pipe. A first throttling valve 1206 is provided on the pipe connecting the second buffer tank 1205 and the first heat exchanger 1201. During operation, the heat obtained by the first heat exchanger 1201 and the power supply 501 and electric heating element 502 of the electrocracking furnace 5 is recovered through the first buffer tank 1202 and then sent into the first compressor 1203 to obtain a high-grade first heat pump stream. This high-grade first heat pump stream can exchange heat with the raw material preheater 201 through the second heat exchanger 1204, thereby providing heat to the raw material preheater 201 for preheating the hydrocarbon raw material. The low-temperature stream after heat exchange enters the second buffer tank 1205. Under the control of the first throttle valve 1206, the low-temperature stream can be sent into the first heat exchanger 1201 to exchange heat with the power supply 501 and electric heating element 502 in the electrocracking furnace 5 to achieve the purpose of cyclic operation.

[0097] Among them, such as Figure 6 , 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. 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 from 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-grade second heat pump stream. This high-grade second heat pump stream 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. The low-temperature stream after heat exchange enters the fourth buffer tank 1212. Under the control of the second throttle valve 1213, the low-temperature stream can be sent to the third heat exchanger 1207 to exchange heat with the low-temperature section 602 of the quenching device 6 to achieve the purpose of cyclic operation.

[0098] In another specific embodiment of the present invention, such as Figure 2 , 7 As shown, the cooling and heat pump system 12 includes a low-temperature heat pump unit 121 and a high-temperature heat pump unit 122.

[0099] Among them, such as Figure 4 , 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 exchanges heat with the power supply 501 and electric heating element 502 in the electrocracking furnace 5 through heat exchange pipes. The first heat exchanger 1201, the first buffer tank 1202, the first compressor 1203, and the second heat exchanger 1204 are connected sequentially, and the second heat exchanger 1204 exchanges heat with the raw material preheater 201 through heat exchange pipes to provide at least a portion 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 pipe, and the outlet of the second buffer tank 1205 is connected to the inlet of the first heat exchanger 1201 through a pipe. A first throttling valve 1206 is provided on the pipe connecting the second buffer tank 1205 and the first heat exchanger 1201. During operation, the heat obtained by the first heat exchanger 1201 and the power supply 501 and electric heating element 502 of the electrocracking furnace 5 is recovered through the first buffer tank 1202 and then sent into the first compressor 1203 to obtain a high-grade first heat pump stream. This high-grade first heat pump stream can exchange heat with the raw material preheater 201 through the second heat exchanger 1204, thereby providing heat to the raw material preheater 201 for preheating the hydrocarbon raw material. The low-temperature stream after heat exchange enters the second buffer tank 1205. Under the control of the first throttle valve 1206, the low-temperature stream can be sent into the first heat exchanger 1201 to exchange heat with the power supply 501 and electric heating element 502 in the electrocracking furnace 5 to achieve the purpose of cyclic operation.

[0100] Among them, such as Figure 4 , 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. 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 from 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-grade second heat pump stream. This high-grade second heat pump stream 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. The low-temperature stream after heat exchange enters the fourth buffer tank 1212. Under the control of the second throttle valve 1213, the low-temperature stream can be sent to the third heat exchanger 1207 to exchange heat with the low-temperature section 602 of the quenching device 6 to achieve the purpose of cyclic operation.

[0101] 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 depressurize 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.

[0102] The features and advantages of the electropyrolysis furnace heat recovery system of the present invention are as follows:

[0103] I. The heat recovery system and method of this electropyrolysis furnace can ensure the long-term stable operation of the electropyrolysis furnace.

[0104] II. The heat recovery system and method of the electric pyrolysis furnace use electric heating to provide the heat required for the pyrolysis reaction, thereby reducing carbon dioxide emissions to near zero and meeting emission standards.

[0105] Third, in the heat recovery system and method of the electric pyrolysis 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 pyrolysis furnace 5 and the quenching device 6, respectively, and return the waste heat to the raw material preheater 201 for preheating the raw materials, effectively reducing energy consumption.

[0106] IV. The heat recovery system and method of the electric pyrolysis furnace are adapted to the electric heating method of the pyrolysis furnace, while taking into account the requirements of waste heat recovery to reduce energy consumption, thus improving the design quality and saving costs.

[0107] Implementation Method 2

[0108] This invention provides a method for heat recovery in an electrocracking furnace, which uses the aforementioned electrocracking furnace heat recovery system to perform pyrolysis treatment of hydrocarbon feedstock. The method includes the following steps:

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

[0110] Step S2: Mix the preheated stream with the steam stream to obtain a raw material and steam mixture stream;

[0111] Step S3: Heating the mixture of raw materials and steam to obtain a superheated stream;

[0112] Step S4: The superheated stream is pyrolyzed using an electric pyrolysis furnace 5 to obtain a first pyrolysis stream;

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

[0114] In an optional embodiment of the present invention, after step S5, step S6 is further included: the second pyrolysis stream is fed into 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 dilute steam and / or medium-pressure steam output from the steam cascade utilization system 9;

[0117] Step S202: Mix dilution steam and / or medium-pressure steam with preheated stream in mixer 3 to obtain a raw material and steam mixture stream.

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

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

[0120] In an optional embodiment of the present invention, during the operation (i.e., in steps S4 to S6), the energy storage system 14 is used to store the energy in the steam cascade utilization system 9 and transport it to the electrocracking furnace 5.

[0121] In an optional embodiment of the present invention, during operation (i.e., steps S4 to S6), the heat from the power supply 501 and the electric heating element 502 of the electrocracking furnace 5 is provided to the first compressor 1203 to obtain a first heat pump feedstock; the first heat pump feedstock supplies heat to the hydrocarbon feedstock for preheating through the second heat exchanger 1204. Specifically, as shown... Figure 4 , 3 As shown, the heat obtained by the first heat exchanger 1201 in exchanging heat with the power supply 501 and electric heating element 502 of the electrocracking furnace 5 is recovered through the first buffer tank 1202 and then sent into the first compressor 1203 to obtain a high-grade first heat pump stream. This high-grade first heat pump stream can exchange heat with the raw material preheater 201 through the second heat exchanger 1204, thereby providing heat to the raw material preheater 201 for preheating the hydrocarbon raw material. The low-temperature stream after heat exchange enters the second buffer tank 1205. Under the control of the first throttle valve 1206, the low-temperature stream can be sent into the first heat exchanger 1201 to exchange heat with the power supply 501 and electric heating element 502 in the electrocracking furnace 5 to achieve the purpose of cyclic operation.

[0122] In an optional embodiment of the present invention, during operation (i.e., steps S4 to S6), the heat from the quenching device 6 is provided to the second compressor 1209 to obtain a 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, as shown... Figure 6 , Figure 6 As shown, the heat from 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-grade second heat pump stream. This high-grade second heat pump stream 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. The low-temperature stream after heat exchange enters the fourth buffer tank 1212. Under the control of the second throttle valve 1213, the low-temperature stream can be sent to the third heat exchanger 1207 to exchange heat with the low-temperature section 602 of the quenching device 6 to achieve the purpose of cyclic operation.

[0123] In an optional embodiment of the present invention, during operation (i.e., steps S4 to S6), the steam cascade utilizes the energy obtained from system 9 to supply the first compressor 1203 and the second compressor 1209 to drive the first compressor 1203 and the second compressor 1209. Specifically, as... Figure 6 , Figure 2 Figure 4 Figure 5 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 depressurize 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 features and advantages of the electropyrolysis furnace heat recovery method of the present invention are as follows:

[0125] I. The heat recovery method of the electric pyrolysis furnace uses electric heating to provide a heat source for the pyrolysis reaction throughout the heating and pyrolysis process, which can achieve zero carbon dioxide emissions and recover heat from the cooling and heat pump system of the electric pyrolysis furnace, thereby reducing energy consumption and operating costs.

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

[0127] Third, the heat recovery system and method of the electric pyrolysis furnace are adapted to the electric heating method of the pyrolysis furnace, while taking into account the requirements of waste heat recovery to reduce energy consumption, thus improving the design quality and saving costs.

[0128] The electropyrolysis furnace heat recovery method of the present invention has the same characteristics and advantages as the above-mentioned electropyrolysis furnace heat recovery system, and will not be repeated here.

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

Claims

1. A heat recovery system for an electropyrolysis furnace, characterized in that, The heat recovery system of the electropyrolysis furnace includes a preheater, a mixer, an electric superheater, an electropyrolysis furnace, and a quenching device connected in sequence. The preheater is used to preheat the hydrocarbon raw materials distributed to it by the raw material distribution device to obtain a preheated material stream; The mixer is used to mix the preheated stream with the steam stream fed into the mixer to obtain a raw material and steam mixture stream; The electric superheater is used to heat the mixture of raw materials and steam to obtain a superheated material. The electro-pyrolysis furnace is used to pyrolyze the superheated stream to obtain a first pyrolyzed stream; The rapid cooling device is used to rapidly cool the first pyrolysis stream to obtain the second pyrolysis stream. The preheater includes a raw material preheater and an electric preheater, which are sequentially connected between the raw material distribution device and the mixer. The raw material preheater is a steam preheater, and the electric cracking furnace is connected to the raw material preheater through a cooling and heat pump system to supply hot steam to the raw material preheater for preheating the hydrocarbon raw material. The mixer is connected to the steam cascade utilization system. The electrocracking furnace heat recovery system also 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 from the quenching device and send high-grade steam to the steam cascade utilization system. The mixer is used to receive the dilution steam and / or medium-pressure steam output from the steam cascade utilization system to mix the dilution steam and / or medium-pressure steam with the preheated stream and obtain a raw material and steam mixture stream.

2. The electropyrolysis furnace heat recovery system as described in claim 1, characterized in that, The electrocracking furnace heat recovery system also includes a coke removal air conveying device, which connects the steam cascade utilization system to the furnace tube of the electrocracking furnace. The coke removal air conveying device is used to mix the coke removal air with steam and then convey it into the furnace tube to remove the coke layer on the inner wall of the furnace tube.

3. The electropyrolysis furnace heat recovery system as described in claim 1, characterized in that, The heat recovery system of the electro-pyrolysis furnace also includes an energy storage system, which is connected between the steam cascade utilization system and the electro-pyrolysis furnace. The energy storage system stores the energy in the steam cascade utilization system and transmits it to the electro-pyrolysis furnace.

4. The electropyrolysis furnace heat recovery system as described in claim 1, characterized in that, The heat recovery system of the electropyrolysis furnace also includes a cooling and heat pump system, which is connected to the electropyrolysis furnace and is used to cool the gas inside the electropyrolysis furnace.

5. The electropyrolysis furnace heat recovery system as described in claim 4, 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 power supply and electric heating elements in the electrocracking furnace through heat exchange pipes. 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 heat exchange pipes to provide at least a portion of the heat required for preheating the raw material preheater.

6. The electropyrolysis furnace heat recovery system as described in claim 5, 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 throttling valve is provided on the pipeline connecting the second buffer tank and the first heat exchanger.

7. The electropyrolysis furnace heat recovery system as described in claim 5 or 6, characterized in that, The cooling and heat pump system further 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 heat exchange pipelines. 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.

8. The electropyrolysis furnace heat recovery system as described in claim 7, 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. A second throttling valve is provided between the fourth buffer tank and the third heat exchanger.

9. The electropyrolysis furnace heat recovery system as described in claim 7, characterized in that, 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.

10. A method for heat recovery in an electrolytic cracking furnace, implemented using the electrolytic cracking furnace heat recovery system according to any one of claims 1 to 9, characterized in that, The heat recovery method for the electropyrolysis furnace includes the following steps: The hydrocarbon feedstock is preheated to obtain a preheated stream. The preheated stream is mixed with the steam stream to obtain a raw material and steam mixture stream; The raw material and steam mixture stream is heated to obtain a superheated stream. The superheated stream is pyrolyzed in an electro-pyrolysis furnace to obtain a first pyrolyzed stream; The first pyrolysis stream is rapidly cooled to obtain the second pyrolysis stream.

11. The method for heat recovery from an electropyrolysis furnace as described in claim 10, characterized in that, After rapidly cooling the first pyrolysis stream to obtain the second pyrolysis stream, the second pyrolysis stream is sent to the post-separation device.

12. The method for heat recovery from an electropyrolysis furnace as described in claim 10, characterized in that, The process of mixing the preheated stream with the steam stream to obtain a raw material and steam mixture stream includes: The mixer receives dilute steam and / or medium-pressure steam output from the steam cascade utilization system; The dilution steam and / or the medium-pressure steam are mixed with the preheated stream in the mixer to obtain the raw material and steam mixture stream.

13. The method for heat recovery from an electropyrolysis furnace as described in claim 12, characterized in that, The first pyrolysis stream is rapidly cooled using a quenching device. The heat from the quenching device is recovered through a waste boiler system, and the generated steam is transported to the steam cascade utilization system.

14. The method for heat recovery from an electropyrolysis furnace as described in claim 12, characterized in that, A coke-removing air conveying device is used to mix coke-removing air with steam and then deliver it to the furnace tube of the electrocracking furnace to remove the coke layer on the inner wall of the furnace tube.

15. The method for heat recovery from an electropyrolysis furnace as described in claim 12, characterized in that, An energy storage system is used to store the energy in the steam cascade utilization system and transport it to the electrocracking furnace.

16. The method for heat recovery from an electropyrolysis furnace as described in claim 13, characterized in that, The power supply and heat from the electric heating element of the electrocracking furnace are provided to the first compressor to obtain the first heat pump material; The first heat pump stream supplies heat to the hydrocarbon feedstock for preheating via a second heat exchanger.

17. The method for heat recovery from an electropyrolysis furnace as described in claim 16, characterized in that, The heat from the quenching device is supplied to the second compressor to obtain a second heat pump flow. The second heat pump stream supplies medium-pressure steam and dilution steam to the mixer via the first steam generator and the second steam generator, respectively.

18. The method for heat recovery from an electropyrolysis furnace as described in claim 17, characterized in that, The energy obtained from the steam cascade utilization system is supplied to the first compressor and the second compressor to drive them.

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