Furnace system and method for cracking hydrocarbons

Abstract

The present application relates to furnace systems and methods for cracking hydrocarbons. Provided herein are furnace systems and methods for steam cracking hydrocarbons to produce ethylene and other light olefins. The furnace system for cracking hydrocarbons includes a radiant combustion chamber containing a plurality of burners and injection nozzles, a primary transfer line exchanger fluidly connected to and downstream of the radiant combustion chamber, and a flow restrictor fluidly connected to and downstream of the primary transfer line exchanger. The furnace system also includes a decoking vessel containing a flow out entry, a fluid exit, and a coke exit, wherein the flow out entry is fluidly connected to and downstream of the flow restrictor, and the fluid exit is fluidly connected to and upstream of the injection nozzles of the radiant combustion chamber, and a coke collection tank connected to the coke exit of the decoking vessel.

Description

[0001] This application is a divisional application of Chinese patent application No. 202080053160.6, filed on July 22, 2020, entitled "Furnace System and Method for Cracking Hydrocarbons".

[0002] priority

[0003] This application claims priority and benefit to U.S. Provisional Application No. 62 / 878,038, filed July 24, 2019, and European Patent Application No. 19206404.6, filed October 31, 2019, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0004] This disclosure relates generally to furnace systems and methods for cracking hydrocarbons, and more specifically to steam cracking furnace systems and methods for decoking and simultaneous steam cracking to produce ethylene. Background Technology

[0005] Ethylene remains the foundation of the modern petrochemical industry. The vast majority of commercially produced ethylene is manufactured via steam cracking. In steam cracking, hydrocarbon feedstock is supplied to the convection section of a cracker, preheated, mixed with dilution steam, and further preheated to temperatures at which thermal cracking is about to occur or occurs to a slight degree.

[0006] The mixed feed and dilution steam (also known as the production effluent) are then fed to the radiant section of the furnace, where they crack into ethylene and other byproducts. The short residence time and low pressure drop of the radiant section favor selectivity for ethylene. The feed and dilution steam mixture is rapidly heated to produce an economically attractive product series. The temperature tendency for reheating the mixture increases as the feed becomes lighter. In addition to the desired light olefins (e.g., ethylene, propylene, butene, or butadiene), the product series includes byproducts as light as hydrogen and as heavy as tar.

[0007] The required heat input to the furnace is provided by burners typically mounted on the floor and / or walls of the radiant section. The fuel for these burners may be a hydrogen / methane mixture recovered from the byproducts of the cracking reaction, or it may be an external fuel supply, or a mixture of both.

[0008] Subsequently, the cracked effluent is fed from the furnace's radiative (reaction) section to a quench heat exchanger, which rapidly cools the effluent and prevents further reaction. Modern quench heat exchangers produce very high-pressure steam, typically at around 1,500 psig or greater. This very high-pressure steam is superheated in the furnace's convection section to temperatures typically ranging from around 900°F to around 1,000°F, and then used to drive large steam turbines in the recovery section of ethylene plants.

[0009] The effluent is then sent to the facility's recovery section for separation into various desired products and byproducts. Ethylene production requires a significant energy input, and modern furnaces incorporate many features to improve their energy efficiency. Where possible, convection sections include boiler feedwater (BFW) energy-saving devices or preheating coils to recover additional energy from the hot flue gas and increase the rate of high-pressure steam production from the furnace.

[0010] An undesirable byproduct of the cracking process is the deposition of coke on the inner surface of the radiant tubes. Coke acts as a hydraulic constraint on the flow of feed and dilution steam through the coils. It also introduces thermal resistance to heat transfer through the tube walls to the feed / dilution steam mixture, thereby increasing the tube metal temperature. When the radiant coil pressure decreases or the radiant coil tube metal temperature reaches a critical value (which depends on the design of each furnace), the furnace must be removed from production to remove the coke (“decoking”).

[0011] Decoking is typically achieved as follows: feed is removed from the furnace (and energy input from the burners is reduced), the steam effluent is moved from the ethylene facility recovery system to the decoking system, and air is gradually added to the steam. The air / steam mixture combusts the coke from the inside of the radiant coils, but as the coke structure burns, a significant amount of solid coke is released (stripped) and carried into the decoking system in the air / steam mixture. When decoking is complete, air is withdrawn from the furnace, leaving only steam in the coils, and the effluent is returned to the facility recovery section. Feed is then reintroduced into the furnace, and another cracking (production) cycle begins.

[0012] The effluent stream leaving the furnace during decoking contains air and steam, as well as particles of various sizes (e.g., coke, coke precursors, and other particulate compositions), carbon monoxide, and carbon dioxide. Methods have been proposed for removing particles from the decoking effluent, such as those in U.S. Patent Nos. 8,647,415 and 9,630,188, in which solids are removed under relatively high pressure. These conventional methods utilize a series of valves, pressurized closed hoppers, blind pipe sections, etc., to store the removed solids under relatively high pressure until decoking is complete, and the separated particles can be removed from the process (e.g., from a blind pipe section or closed hopper).

[0013] Despite progress, there remains a need for improved furnace systems and methods for cracking hydrocarbons, as well as methods for decoking furnace systems. In particular, there is a need for improved decoking methods that can remove and separate particles from the decoking effluent at lower pressures than those used in conventional methods, for example, to reduce equipment costs and increase process efficiency. Summary of the Invention

[0014] Embodiments of this disclosure provide furnace systems and methods for steam cracking hydrocarbons to produce light olefins such as ethylene, which offer high thermal efficiency compared to existing systems and methods. Embodiments also include methods for decoking furnace systems. In one or more embodiments, the furnace system for cracking hydrocarbons includes a radiant combustion chamber containing multiple burners and multiple injection nozzles (e.g., decoking effluent injection nozzles), a main transfer line heat exchanger fluidly connected to and downstream of the radiant combustion chamber, and a flow restrictor fluidly connected to and downstream of the main transfer line heat exchanger. The furnace system also includes a decoking vessel containing an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to and downstream of the flow restrictor, the fluid outlet is fluidly connected to and upstream of the injection nozzles of the radiant burners, and a coke collection tank is connected to the coke outlet of the decoking vessel.

[0015] In one or more embodiments, a furnace system for cracking hydrocarbons includes a radiant combustion chamber containing multiple burners and injection nozzles, a primary transfer line heat exchanger fluidly connected to and downstream of the radiant combustion chamber, and a secondary transfer line heat exchanger fluidly connected to and downstream of the primary transfer line heat exchanger. The furnace system also includes a first valve disposed between the primary and secondary transfer line heat exchangers, a decoking effluent line fluidly connected to and downstream of the primary transfer line heat exchanger and fluidly connected to and upstream of the first valve, and a second valve fluidly connected to and downstream of the primary transfer line heat exchanger. The furnace system also includes a flow restrictor fluidly connected to the decoking effluent line downstream of the second valve, and a decoking vessel fluidly connected to the decoking effluent line, the decoking vessel having an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to and downstream of the flow restrictor, the fluid outlet is fluidly connected to and upstream of the injection nozzles of the radiant burners, and a coke collection tank is connected to the coke outlet of the decoking vessel.

[0016] In some embodiments, the furnace system for cracking hydrocarbons includes a radiant combustion chamber comprising multiple burners, injection nozzles, and one or more coils, wherein the coils are or include radiant coils, convection coils, or any combination thereof; a primary transfer line heat exchanger fluidly connected to and downstream of the radiant combustion chamber; and a secondary transfer line heat exchanger fluidly connected to and downstream of the primary transfer line heat exchanger. The furnace system also includes a first valve disposed between the primary and secondary transfer line heat exchangers; a decoking effluent line fluidly connected to and downstream of the primary transfer line heat exchanger and fluidly connected to and upstream of the first valve; a second valve fluidly connected to and downstream of the primary transfer line heat exchanger; and a flow restrictor fluidly connected to and downstream of the second valve. The furnace system also includes a decoking vessel fluidly connected to the decoking effluent line and comprising an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to and downstream of the flow restrictor, and the fluid outlet is fluidly connected to and upstream of the injection nozzle of the radiant burner. The decoking vessel is or contains a cyclone separator and is configured to receive decoking effluent via an effluent inlet, separate the decoking effluent into coke particles and decoking fluid, transfer the coke particles via a coke outlet to a coke collection tank, and transfer the decoking fluid via a fluid outlet to an injection nozzle. The furnace system also includes a coke collection tank connected to the coke outlet of the decoking vessel, wherein the coke collection tank is configured to store coke particles at ambient pressure.

[0017] In one or more embodiments, the method for cracking hydrocarbons includes flowing decoking effluent from a radiant combustion chamber through a main transfer line heat exchanger, flowing decoking effluent from the main transfer line heat exchanger through a flow restrictor, and flowing decoking effluent from the flow restrictor to a decoking vessel. The method further includes separating the decoking effluent into coke particles and decoking fluid within the decoking vessel, transferring the coke particles from the decoking vessel to a coke collection tank, transferring the decoking fluid from the decoking vessel to the radiant combustion chamber, and burning the decoking fluid within the radiant combustion chamber. Attached Figure Description

[0018] Therefore, a more specific description of the present disclosure, which has been briefly summarized above, can be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings only illustrate typical embodiments of the present disclosure and should not be considered as limiting the scope, as the present disclosure may acknowledge other equally effective embodiments.

[0019] Figure 1 This is a schematic diagram of a furnace system for cracking hydrocarbons, as described and discussed in one or more embodiments herein.

[0020] Figure 2This is a flowchart of a method for cracking hydrocarbons, as described and discussed in one or more embodiments herein.

[0021] To facilitate understanding, the same reference numerals are used where possible to designate the same common elements in the drawings. This covers elements and features of one embodiment that can be beneficially incorporated into other embodiments without further explanation. Detailed Implementation

[0022] Embodiments of this disclosure provide furnace systems and methods for cracking hydrocarbons, including methods for steam cracking hydrocarbons to produce light olefins (e.g., ethylene, propylene, butene, or butadiene). The methods also provide methods for maintaining the furnace system during cracking operations and during periodic decoking of the furnace system.

[0023] In general, scaling in heat exchangers and other process equipment and components is a common problem in the petrochemical industry. Disruption or deliberate alteration of cracking conditions during normal operation can lead to, for example, cooling and shrinkage of the radiant tubing in transfer line heat exchangers and / or other downstream equipment, shedding of coke or spalling, and the flow of coke or spalling downstream.

[0024] The embodiments disclosed herein relate to methods for improving the overall thermal and economic efficiency of a system and reducing fouling in heat exchangers during continuous or semi-continuous processes. Additionally, the embodiments disclosed herein can be used to prevent fouling in other process equipment such as pumps, valves, compressors, and other common equipment where unwanted build-up of fouling or the presence of solid components is undesirable. Furthermore, minimizing the amount of large coke particles entering the combustion chamber during decoking helps promote complete coke combustion and reduces heater chimney emissions (e.g., PM10 (particulate matter smaller than 10 µm) and PM2.5 (particulate matter smaller than 2.5 µm)). In some embodiments, the fouling collection device can be separated and emptied without interrupting one or more sections of the continuous or semi-continuous process. In this way, the fouling portion is not conveyed to a second heat exchanger. In addition, accumulated contaminants can be periodically emptied from the collection unit without shutting down critical process operations (such as decoking processes), thereby providing operational continuity or improved process aspects such as reduced stress, ease of restart, increased production, and other benefits that can be highlighted from the following implementations related to hydrocarbon cracking processes.

[0025] Figure 1 This is a schematic diagram of a furnace system 100 for cracking hydrocarbons into ethylene and other olefins and reducing fouling during the production of such olefins, as described and discussed in one or more embodiments herein. The furnace system 100 includes a radiant combustion chamber 110 containing a plurality of burners 114 (in... Figure 1The image shows four burners 114 and one or more injection nozzles 116 located on the surface 112 (e.g., the bottom surface) of the radiant combustion chamber 110. Figure 1 An injection nozzle 116 is shown. Although not shown, one or more burners 114 and / or one or more injection nozzles 116 may be located on other surfaces of the radiant combustion chamber 110, such as surfaces perpendicular to surface 112 (e.g., sidewalls) or surfaces opposite to surface 112 (e.g., top surface). In one or more embodiments, at least a portion of the plurality of burners 114 are located on surface 112 of the radiant combustion chamber 110 and the injection nozzle 116 is adjacent to at least a portion of the plurality of burners 114.

[0026] Although Figure 1 The description includes a radiant combustion chamber 110 containing four burners 114 and one injection nozzle 116, but the radiant combustion chamber 110 may have a series of burners 114 and injection nozzles 116. In one or more embodiments, the radiant combustion chamber 110 may independently have from 1, 2, 3, 4, 5, 6, 8, 10, about 12, about 15, about 18 or about 20 to about 22, about 24, about 30, about 35, about 40, about 45, about 48, about 50, about 55, about 60, about 64, about 68, about 70, about 80 or about 100 burners 114 and / or injection nozzles 116. For example, the radiant combustion chamber 110 may independently have a range of values ​​from 1 to 100, from 1 to 64, from 1 to 50, from 1 to 48, from 1 to 40, from 1 to 35, from 1 to 30, from 1 to 25, from 1 to 24, from 1 to 20, from 1 to 15, from 1 to 10, from 1 to 5, from 1 to 3, from about 10 to 100, from about 10 to 64, from about 10 to 50, from about 10 to 48, from about 10 to 40, from about 10 to 35, from about 10 to 30, from about 10 to 25, from about 10 to about 24, about 10 to about 20, about 10 to about 15, about 10 to about 12, about 20 to about 100, about 20 to about 64, about 20 to about 50, about 20 to about 48, about 20 to about 40, about 20 to about 35, about 20 to about 30, about 20 to about 25, about 20 to about 24, about 20 to about 22, about 24 to about 100, about 24 to about 64, about 24 to about 48, about 48 to about 100, about 48 to about 64, or about 64 to about 100 burners 114 and / or injection nozzles 116. In one or more embodiments, the radiant combustion chamber 110 may have about 24, about 48, or about 64 burners 114 and about 24 injection nozzles 116.

[0027] In one or more embodiments, each of the burners 114 may independently be any type of burner. In some embodiments, the burner 114 does not recirculate flue gas back to the combustion zone, such as the radiant section 122, within the radiant combustion chamber 110. In one or more instances, the burner 114 may be any burner described in U.S. Patent No. 8,002,951, which is incorporated herein by reference. In some instances, the burner 114 may be the burner shown in Figure 4 of U.S. Patent No. 8,002,951, but configured not to recirculate flue gas from the furnace to the main gas chamber.

[0028] The radiant combustion chamber 110 includes a radiant section 122 and a convection section 126. The radiant section 122 includes one, two, or more radiant coils 124 extending upward from surface 112, and the convection section 126 includes one, two, or more convection coils 128, or any combination thereof. The radiant combustion chamber 110 may include any combination and any number of radiant coils 124 and / or convection coils 128. The furnace system 100 includes one, two, or more feed lines (not shown) fluidly connected to the radiant coils 124. The feed lines may be or include one or more hydrocarbon feed lines, one or more steam feed lines, one or more additive feed lines, or any combination thereof. For example, a hydrocarbon feed line is used to transfer production effluent containing hydrocarbons (also referred to as mixed feed and dilution steam) to the radiant coils 124. The production effluent contains butane, propane, ethane, asphaltenes, residual oil, bitumen, gas oil, naphtha, one or more other hydrocarbons, or any combination thereof. Upon application of heat, the hydrocarbons crack to produce product gases such as ethylene, propylene, and / or other olefins. Other hydrocarbons, such as C5 and C6 hydrocarbons, gas oil, naphtha, and heavier / longer hydrocarbons, can also be used to produce olefins according to any embodiment.

[0029] Furnace system 100 includes a primary transfer line heat exchanger (PTLE) 130 or other quench heat exchanger fluidly connected to and downstream of radiant combustion chamber 110, and a secondary transfer line heat exchanger (STLE) 140 or other quench heat exchanger fluidly connected to PTLE 130 via transfer line 135 and downstream. More specifically, PTLE 130 has an inlet 132 and an outlet 134, and STLE 140 has an inlet 142 and an outlet 144. Furnace system 100 also includes a first valve 136 (e.g., a transfer line valve) disposed between PTLE 130 and STLE 140, for example, on transfer line 135 between outlet 134 of PTLE 130 and inlet 142 of STLE 140. Thus, inlet 142 of STLE 140 is fluidly connected to outlet 134 of PTLE 130, and outlet 144 of STLE 140 is fluidly connected to one or more recovery systems 146.

[0030] In one or more instances, each of PTLE 130 and STLE 140 may independently be a quench heat exchanger that rapidly cools the effluent and prevents further reaction of the effluent. The first valve 136 may be or include an electrically operated valve (MOV), an electronic valve, a mechanical valve, a pneumatic valve, a hydraulic valve, or a manual valve. The first valve 136 may also be a multi-way valve, such as a three-way valve.

[0031] In the operation of furnace system 100, the production effluent containing hydrocarbon feed is first preheated, and in the case of liquid feed, it is often at least partially evaporated and mixed with dilution steam in the convection section 126 of furnace system 100. The temperature of the production effluent leaving the convection section 126 is typically designed to be at or near the point where significant thermal cracking begins. Typically, for example, the temperature of the convection section 126 is about 1,050°F (565°C) to about 1,150°F (620°C) for gas oil feed, about 1,150°F (620°C) to about 1,250°F (675°C) for naphtha feed, and / or about 1,250°F (675°C) to about 1,350°F (730°C) for ethane feed. After preheating in the convection section 126, the steam feed / dilution steam mixture is typically rapidly heated in the radiant section 122 to achieve the desired level of thermal cracking. The coil outlet temperature (COT) of the radiant section 122 is typically from about 1,450°F (790°C) to about 1,500°F (815°C) for gas oil feed, from about 1,500°F (815°C) to about 1,600°F (870°C) for naphtha feed, and / or from about 1,550°F (845°C) to about 1,650°F (900°C) for ethane feed. After the desired degree of thermal cracking has been achieved in the radiant section 122, the furnace effluent is rapidly quenched in the PTLE 130.

[0032] During production processes involving cracking reactions, carbonaceous fouling materials such as coke, carbon, and / or tar may be generated as byproducts. Steam may be introduced as a diluent, for example, via a flow line fluidly connected to the radiant coil 124. Heat is provided by heating the medium outside the radiant coil 124 in the radiant section 122 of the radiant combustion chamber 110, which is introduced through a heating medium inlet or burner 114 (e.g., a furnace burner, bottom plate burner, or wall burner). The heat then passes through the convection section 126 containing the convection coil 128 and then exits via exhaust 129.

[0033] After the production effluent containing hydrocarbon feedstock is processed through the radiation section 122 and the convection section 126, the product (e.g., gas) flows through PTLE 130 and STLE 140. The production effluent containing the product exits from outlet 144 of STLE 140 and is directed to one or more recovery systems 146. The recovery system 146 may be or include a recovery section of a facility, storage containers or vessels, one or more types of downstream processing equipment (e.g., quench towers and / or separation units), or any combination thereof.

[0034] Furnace system 100 includes decoking system 150, which is a bypass system activated by being brought online or otherwise for the decoking process. Decoking system 150 includes decoking effluent line 154 and a second valve 138 (e.g., decoking effluent line valve) that works in conjunction with first valve 136 to switch between production and decoking modes. Decoking effluent line 154 is fluidly connected downstream of PTLE 130 and fluidly connected upstream of first valve 136. Second valve 138 is fluidly connected downstream of PTLE 130 to decoking effluent line 154. Second valve 138 may be or include a motor-operated valve (MOV), an electronic valve, a mechanical valve, a pneumatic valve, or a manual valve. Second valve 138 may also be a multi-way valve, such as a three-way valve that functions as both valves 136 and 138. In other words, the first valve 136 and the second valve 138 can be replaced by a single three-way valve (not shown) fluidly connected to the transfer line 135 and the flow restrictor 152 and located between the transfer line 135 and the flow restrictor 152. In other respects, valves 136 and 138 are connected and operate under common control, for example, under common mechanical, electrical, or electromechanical control. In these respects, a control system for controlling valves 136 and 138 can be configured to prevent valve 136 from opening when valve 138 is open, and vice versa. The control system can be an automatic control system, but this is not necessary. For example, manual control is within the scope of the invention.

[0035] The decoking system 150 of the furnace system 100 also includes a flow restrictor 152 with one or more flow-limiting orifices, fluidly connected to the decoking effluent line 154 downstream of the second valve 138; a decoking container 160 fluidly connected to the decoking effluent line 154; and a coke collection tank 170 connected to the decoking container 160. The second valve 138 is disposed between the PTLE 130 and the flow restrictor 152. The STLE 140 is fluidly connected to the PTLE 130 downstream and to the second valve 138 and the flow restrictor 152 upstream.

[0036] Some implementations include at least one PTLE and at least one STLE. For example, the PTLE can be used to generate steam, and the STLE can be used to preheat the hydrocarbon feed to the convection section of the steam cracker. Surprisingly, the authors found that extracting the decoking effluent from outlet 144 resulted in increased fuel consumption (i.e., lower energy efficiency) during decoking mode compared to removing the decoking effluent via line 154. Increased fuel consumption is required during decoking mode to maintain the radiant combustor at the desired decoking temperature. This effect is surprising because existing technologies typically indicate that energy recovery (e.g., in the STLE used for feed preheating) leads to improved energy efficiency, which would reduce the amount of fuel required.

[0037] As an illustrative example of a typical cracker operating in decoking mode, removing the decoking effluent via line 154 results in a decoking effluent with a higher temperature (361°C) than when removed via outlet 144 (266°C). The lower temperature of the decoking effluent, if removed via outlet 144, results in a combustion chamber temperature lower than the desired range of 980°C to 1040°C (flue gas temperature), and therefore requires additional burner fuel to achieve the desired combustion chamber temperature. Those skilled in the art will also appreciate that STLE decoking is generally unnecessary because it typically does not scale during operation. As a result, there is no significant loss of furnace performance when the decoking effluent does not pass through the STLE.

[0038] In one or more embodiments, the first valve 136 and the second valve 138 may be simultaneously open and / or closed relative to each other. For example, the first valve 136 may be open while the second valve 138 is closed. Alternatively, the first valve 136 may be closed while the second valve 138 is open. In some embodiments, the first valve 136 and the second valve 138 may be two valves connected in series. In other embodiments, a single valve, such as a three-way valve (not shown), may be used instead of the first valve 136 and the second valve 138. If used, the three-way valve is fluidly connected to and positioned between PTLE 130, STLE 140, and flow restrictor 152. For example, the three-way valve is fluidly connected to outlet 134 downstream via transfer line 135, fluidly connected to inlet 142 of STLE 140 upstream, and fluidly connected to flow restrictor 152 upstream.

[0039] The flow restrictor 152 increases the pressure upstream of the decoking vessel 160 and the flow restrictor 152, allowing the decoking vessel 160 to operate at lower pressures, such as ambient pressure or approximately ambient pressure. As used herein, ambient pressure is approximately 740 Torr to approximately 780 Torr, approximately 750 Torr to approximately 770 Torr, approximately 755 Torr to approximately 765 Torr, or approximately 760 Torr. Operating the decoking vessel 160 at ambient pressure or approximately ambient pressure reduces costs and improves process efficiency. For example, the decoking vessel 160 and the coke collection tank 170 can be constructed with a thinner structure than conventional decoking vessels and coke collection tanks required for operation at higher pressures.

[0040] The flow restrictor 152 may be or include one or more restricting orifice plates, baffles, pipes or conduits with narrowing diameters, or any combination thereof. In one or more instances, the flow restrictor 152 includes one, two, three, four, or more restricting orifice plates. If two or more restricting orifice plates are used together, they may be placed in series. The restricting orifice plates may have one or more holes or orifices through them, which provide fluid communication between the transfer line 135 and the decoking effluent line 154. Positioning the flow restrictor 152 upstream of the decoking-to-combustion chamber line 172 and the decoking vessel 160 provides surprising process benefits relative to conventional processes. Positioning the flow restrictor immediately upstream of the injection nozzle 116, for example in line 172, can result in a non-uniform flow distribution when more than one injection nozzle is used. Furthermore, it has been observed that configuring the decoking-to-combustion chamber line 172 to provide a desired pressure drop to each nozzle can result in non-uniform flow to each injection nozzle 116. Irregular flow distribution in the combustion chamber can lead to unstable burner flames, potentially causing operational safety issues. These difficulties are largely avoided or mitigated by positioning the flow restrictor 152 upstream of the decoking vessel 160.

[0041] In some embodiments, the orifice plate is limited to having 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 holes to 13, 14, 15, about 18, about 20, about 24, about 28, about 30, about 32, about 35, about 40 holes, or about 50 holes. For example, the orifice plate is limited to having from 2 to about 50 holes, 2 to about 40 holes, 2 to about 30 holes, 2 to about 25 holes, 2 to about 20 holes, 2 to about 18 holes, 2 to about 15 holes, 2 to about 13 holes, 2 to about 10 holes, 2 to about 8 holes, 2 to about 5 holes, about 5 to about 50 holes, about 5 to about 40 holes, about 5 to about 30 holes, about 5 to about 25 holes, about 5 to about 20 holes, about 5 to about 5 The number of holes may be approximately 18, 5 to 15, 5 to 13, 5 to 10, 5 to 8, 10 to 100, 10 to 40, 10 to 30, 10 to 25, 10 to 20, 10 to 18, 10 to 15, 10 to 14, 10 to 13, or 10 to 12. In some instances, the current limiter 152 includes two or more tandemly positioned limiting orifice plates, and each orifice plate has a plurality of holes, such as approximately 4, 8, 10, or 12 holes to approximately 14, 16, 20, or 24 holes.

[0042] The decoking container 160 includes an effluent inlet 162, a fluid outlet 164, and a coke outlet 166. The effluent inlet 162 is fluidly connected to and downstream of the flow restrictor 152, and the fluid outlet 164 is fluidly connected to and upstream of the injection nozzle 116 of the radiant combustion chamber 110. The coke collection tank 170 is connected to the coke outlet 166 of the decoking container 160.

[0043] In one or more embodiments, the decoking container 160 is or includes a decoking drum or a cyclone separator. The cyclone separator or other decoking container 160 receives decoking effluent from the decoking effluent line 154 via a fluid inlet 162, separates the decoking effluent into coke particles and decoking fluid, and transfers the coke particles via a coke outlet 166 to a coke collection tank 170. The decoking fluid in the decoking container 160 is transferred from the fluid outlet 164 through the decoking to combustion chamber line 172 or conveyed to the injection nozzle 116.

[0044] In one or more embodiments, the coke collection tank 170 is located within the facility, allowing accumulated coke / sludge to be periodically emptied and removed for disposal. The coke collection tank 170 may be or include one or more tanks, containers, hoppers, coke traps, or other structures for emptying accumulated sludge. It may be movable, for example via wheels or forklifts, and may be continuously positioned near the decoking container 160, or may be temporarily placed for emptying as desired or required. In some instances, the coke collection tank 170 is a dust or coke collection tank that may be sealed to retain all collected particles while maintaining ambient pressure. At ambient pressure, the coke collection tank 170 stores or otherwise contains coke particles. The coke collection tank 170 may include a shut-off system to prevent pressurization exceeding ambient pressure or any other predetermined pressure. This may be achieved, for example, by using a furnace shut-off system, such as a system that automatically reduces the burner load in response to overpressure in the radiant section 122. In one or more instances, as used herein, the ambient pressure is approximately 740 Torr to approximately 780 Torr, approximately 750 Torr to approximately 770 Torr, approximately 755 Torr to approximately 765 Torr, or approximately 760 Torr.

[0045] A flow restrictor 152 is positioned upstream of the decoking vessel 160, allowing the decoking vessel 160 and the coke collection tank 170 to operate at relatively low pressures, such as at or near ambient pressure. Therefore, the coke collection tank 170 does not need to be a pressurized "locked-in hopper"—which would be the case if the flow restrictor were located elsewhere in the riser or system. A second valve 138 and a stole 140 positioned upstream of the decoking vessel 160 provide the furnace system 100 with high thermal efficiency compared to existing systems.

[0046] The decoking vessel 160 and / or coke collection tank 170 according to one or more embodiments disclosed herein may also include one or more valves, baffles, manholes, or other functional connections. For example, a valve may serve as a steam supply inlet for purging any lighter hydrocarbons from accumulated coke / sludge before venting. In other instances, a valve may serve as a cooling water inlet to quench accumulated sludge and provide a liquid environment to prevent potentially spontaneously combustible materials from being exposed to air. Other inlets and outlets may also be provided for nitrogen purging or sweeping, cleaning, or other purposes. If desired or advantageous, one or more connections may be attached to the decoking vessel 160 and / or coke collection tank 170 using angled connections to prevent the accumulation of sludge.

[0047] During the cracking operation in the production process, coke and carbon can form on radiant coil 124, PTLE 130, transfer line 135, and other equipment or portions of furnace system 100. During the production process, valve 136 is in the open position and valve 138 is in the closed position. To interrupt the production process and initiate the decoking process, valve 136 is adjusted to the closed position and valve 138 is adjusted to the open position. After interrupting the hydrocarbon feed flow, a decoking fluid, including steam and / or air, is injected to remove coke buildup from at least radiant coil 124, PTLE 130, and transfer line 135. Once the decoking process is complete, valve 138 is adjusted to the closed position and valve 136 is adjusted to the open position, and the production process continues thereafter. The production and decoking processes can be sequentially repeated to improve the overall efficiency of each process while cracking hydrocarbons to produce ethylene and / or other light olefins (e.g., propylene, butene, or butadiene).

[0048] In one or more embodiments, the method of cracking hydrocarbons includes flowing decoking effluent from a radiant combustion chamber 110 through a PTLE 130, flowing decoking effluent from the PTLE 130 through a flow restrictor 152, and flowing decoking effluent from the flow restrictor 152 to a decoking container 160. The method further includes separating the decoking effluent into coke particles and decoking fluid within the decoking container 160, transferring the coke particles from the decoking container 160 to a coke collection tank 170, transferring the decoking fluid from the decoking container 160 to the radiant combustion chamber 110, and burning the decoking fluid within the radiant combustion chamber 110. In some instances, the decoking fluid contains a portion of coke particles that were not separated by the decoking container 160. The method includes transferring the coke particles to the coke collection tank 170 under ambient pressure. The method may include storing the coke particles in the coke collection tank 170 under ambient pressure.

[0049] In some embodiments, the method includes closing valve 138 located between PTLE 130 and flow restrictor 152, and allowing production effluent to flow from PTLE 130 to STLE 140. The method also includes allowing production effluent to flow from STLE 140 to recycling system 146. In other embodiments, before allowing coke effluent to flow from PTLE 130 through flow restrictor 152, the method further includes allowing production effluent to flow from PTLE 130 to STLE 140, closing a first valve 136 located between PTLE 130 and STLE 140, opening a second valve 138 located between PTLE 130 and flow restrictor 152, and allowing decoking effluent to flow from PTLE 130 through flow restrictor 152.

[0050] Figure 2This is a flowchart describing a method 200 for cracking hydrocarbons using a furnace system during a production process to produce ethylene and / or other light olefins, and for decoking the furnace system during a decoking process, as described and discussed in one or more embodiments herein. Method 200 may be performed on furnace system 100 and other different furnace systems not described or discussed herein. Method 200 includes:

[0051] At 202, production effluent and steam flow or otherwise pass through the radiant combustion chamber 110, which includes one, two or more radiant coils 124 within the radiant section 122, and then, during the production process, the production effluent flows through PTLE 130 and then through STLE 140.

[0052] At 204, when the decoking process begins, the flow of the production effluent stops or is otherwise terminated, and steam flow is maintained.

[0053] In step 206, method 200 includes closing a first valve 136 disposed between PTLE 130 and STLE 140, and opening a second valve 138 disposed between PTLE 130 and flow restrictor 152. In one or more embodiments, the first valve 136 may be closed while the second valve 138 is open simultaneously. In some embodiments, a single valve may be used instead of the first and second valves 136, 138 to provide simultaneous closing and opening. For example, a three-way valve may be used instead of the first and second valves 136, 138 to stop flow from PTLE 130 to STLE 140 while simultaneously initiating flow from PTLE 130 to flow restrictor 152. Essentially, flow from PTLE 130 is diverted from STLE 140 to flow restrictor 152.

[0054] At 208, airflow originates from or otherwise originates from the radiant combustion chamber 110, which includes one, two or more radiant coils 124 within the radiant section 122, and then flows or otherwise passes through the PTLE 130 during the decoking process.

[0055] At 210, the decoking effluent originates from or otherwise originates from the radiant combustion chamber 110, which includes one, two or more radiant coils 124 within the radiant section 122, and then flows or otherwise passes through PTLE 130 during the decoking process.

[0056] At 212, the decoking effluent flows from PTLE 130 or otherwise passes through flow restrictor 152.

[0057] At 214, the decoking effluent flows from the flow restrictor 152 or is otherwise transferred to the decoking container 160.

[0058] At 216, the decoking effluent is separated into coke particles and decoking fluid within the decoking container 160.

[0059] At 218, coke particles are transferred from the decoking container 160 to the coke collection tank 170.

[0060] At 220, the decoking fluid is transferred from the decoking container 160 to the radiant combustion chamber 110. The decoking fluid can be injected or otherwise introduced into the radiant combustion chamber 110 through one or more injection nozzles 116.

[0061] At 222, the decoking fluid is burned in the radiant combustion chamber 110 by a burner 114 disposed in the radiant combustion chamber 110.

[0062] At 224, the flow of decoking effluent and air is stopped or otherwise terminated, and the remaining air is purged or otherwise removed from the radiant coil 124 and other parts of the system before production is restarted.

[0063] At 226, the second valve 138 is closed and the first valve 136 is open.

[0064] In one or more embodiments at 226, the first valve 136 may open while simultaneously closing the second valve 138. In some embodiments, if a three-way valve is used at 226, the cessation and commencement of flow may occur simultaneously with the use of a single three-way valve instead of the first and second valves 136, 138. For example, using a three-way valve instead of the first and second valves 136, 138 thereby stopping the flow from PTLE 130 to flow restrictor 152, and simultaneously stopping the flow from PTLE 130 to STLE 140. Essentially, the flow from PTLE 130 is diverted from flow restrictor 152 to STLE 140.

[0065] Once the second valve 138 is closed and the first valve 136 is open or the three-way valve is adjusted, the production process begins a new cracked hydrocarbon cycle to produce light hydrocarbons such as ethylene. The production effluent flows or otherwise passes through the radiant combustion chamber 110 and can repeat the processes described from 202 to 204. Throughout method 200, 210 to 226 may occur partially or entirely, and simultaneously or at least partially or completely overlap in time during the production and decoking processes described and discussed herein.

[0066] In one or more embodiments, furnace system 100 includes or is integrated with one or more selective catalytic reduction (SCR) units (not shown). The furnace system 100 and / or methods described and discussed herein, including decoking of furnace system 100, improve the expected lifespan of the SCR system by removing large coke particles from the decoking vessel 160 before or upstream of the radiant combustion chamber 110.

[0067] Implementations of this disclosure also relate to one or more of the following paragraphs:

[0068] 1. A furnace system for cracking hydrocarbons, comprising: a radiant combustion chamber including a plurality of burners and injection nozzles; a main transfer line heat exchanger fluidly connected to and downstream of the radiant combustion chamber; a flow restrictor fluidly connected to and downstream of the main transfer line heat exchanger; a decoking vessel including an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to and downstream of the flow restrictor, and the fluid outlet is fluidly connected to and upstream of the injection nozzles of the radiant burners; and a coke collection tank connected to the coke outlet of the decoking vessel.

[0069] 2. The furnace system according to paragraph 1 also includes a valve disposed between the heat exchanger and the flow restrictor in the main transfer pipeline.

[0070] 3. The furnace system according to paragraph 1 or 2 also includes a secondary transfer line heat exchanger that is fluidly connected to the primary transfer line heat exchanger and is downstream of the primary transfer line heat exchanger and upstream of the flow restrictor.

[0071] 4. According to the furnace system in paragraph 3, it also includes valves disposed between the primary transfer line heat exchanger and the secondary transfer line heat exchanger.

[0072] 5. According to the furnace system in paragraph 3, the secondary transfer line heat exchanger includes an inlet and an outlet, wherein the inlet of the secondary transfer line heat exchanger is fluidly connected to the outlet of the primary transfer line heat exchanger, and the outlet of the secondary transfer line heat exchanger is fluidly connected to the recovery system.

[0073] 6. A furnace system according to any one of paragraphs 1-5, wherein the decoking container includes a cyclone separator.

[0074] 7. According to the furnace system in paragraph 6, wherein the cyclone separator is configured to: receive decoking effluent via an effluent inlet, separate the decoking effluent into coke particles and decoking fluid, and transfer the coke particles via a coke outlet to a coke collection tank and the decoking fluid via a fluid outlet to an injection nozzle.

[0075] 8. A furnace system according to any one of paragraphs 1-7, wherein a coke collection tank is configured to store coke particles under ambient pressure.

[0076] 9. A furnace system according to any one of paragraphs 1-8, wherein at least a portion of the plurality of burners is located on the bottom surface of the radiant combustion chamber.

[0077] 10. A furnace system according to any one of paragraphs 1-9, wherein the injection nozzle is adjacent to at least a portion of a plurality of burners.

[0078] 11. A furnace system according to any one of paragraphs 1-10, wherein the radiant combustion chamber further comprises one or more coils disposed therein.

[0079] 12. The furnace system according to paragraph 11, wherein the coils include radiant coils, convection coils, or combinations thereof.

[0080] 13. A furnace system for cracking hydrocarbons, comprising: a radiant combustion chamber including a plurality of burners and injection nozzles; a primary transfer line heat exchanger fluidly connected to and downstream of the radiant combustion chamber; a secondary transfer line heat exchanger fluidly connected to and downstream of the primary transfer line heat exchanger; a first valve disposed between the primary transfer line heat exchanger and the secondary transfer line heat exchanger; a decoking effluent line fluidly connected to and downstream of the primary transfer line heat exchanger and fluidly connected to and upstream of the first valve; a second valve fluidly connected to and downstream of the primary transfer line heat exchanger; a flow restrictor fluidly connected to and downstream of the second valve; a decoking vessel fluidly connected to and including an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to and downstream of the flow restrictor, and the fluid outlet is fluidly connected to and upstream of the injection nozzles of the radiant burners; and a coke collection tank connected to the coke outlet of the decoking vessel.

[0081] 14. The furnace system according to paragraph 13, wherein the decoking container includes a cyclone separator.

[0082] 15. The furnace system according to paragraph 14, wherein the cyclone separator is configured to: receive decoking effluent via an effluent inlet, separate the decoking effluent into coke particles and decoking fluid, and transfer the coke particles via a coke outlet to a coke collection tank and the decoking fluid via a fluid outlet to an injection nozzle.

[0083] 16. A furnace system according to any one of paragraphs 13-15, wherein a coke collection tank is configured to store coke particles under ambient pressure.

[0084] 17. A furnace system according to any one of paragraphs 13-16, wherein at least a portion of the plurality of burners is located on the bottom surface of the radiant combustion chamber.

[0085] 18. A furnace system according to any one of paragraphs 13-17, wherein the injection nozzle is adjacent to at least a portion of a plurality of burners.

[0086] 19. A furnace system according to any one of paragraphs 13-18, wherein the radiant combustion chamber further comprises one or more coils disposed therein.

[0087] 20. The furnace system according to paragraph 19, wherein the coils comprise radiant coils, convection coils, or combinations thereof.

[0088] 21. A furnace system for cracking hydrocarbons, comprising: a radiant combustion chamber including a plurality of burners, injection nozzles, and one or more coils, wherein the coils include radiant coils, convection coils, or any combination thereof; a primary transfer line heat exchanger fluidly connected to and downstream of the radiant combustion chamber; a secondary transfer line heat exchanger fluidly connected to and downstream of the primary transfer line heat exchanger; a first valve disposed between the primary transfer line heat exchanger and the secondary transfer line heat exchanger; a decoking effluent line fluidly connected to and downstream of the primary transfer line heat exchanger and fluidly connected to and upstream of the first valve; a second valve fluidly connected to and downstream of the primary transfer line heat exchanger and the decoking effluent line; and a decoking effluent line fluidly connected to and downstream of the primary transfer line heat exchanger. A flow restrictor is fluidly connected downstream of the second valve; a decoking container is fluidly connected to the decoking effluent line and includes an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to the flow restrictor downstream, and the fluid outlet is fluidly connected to the injection nozzle of the radiant burner upstream, wherein the decoking container includes a cyclone separator configured to: receive the decoking effluent via the effluent inlet, separate the decoking effluent into coke particles and decoking fluid, and transfer the coke particles via the coke outlet to a coke collection tank and the decoking fluid via the fluid outlet to the injection nozzle; and a coke collection tank is connected to the coke outlet of the decoking container, wherein the coke collection tank is configured to store coke particles at ambient pressure.

[0089] 22. A method for cracking hydrocarbons using a furnace system according to any one of paragraphs 1-21.

[0090] 23. A method for cracking hydrocarbons, comprising: flowing decoking effluent from a radiant combustion chamber through a main transfer line heat exchanger; flowing decoking effluent from the main transfer line heat exchanger through a flow restrictor; flowing decoking effluent from the flow restrictor to a decoking vessel; separating the decoking effluent into coke particles and decoking fluid within the decoking vessel; transferring the coke particles from the decoking vessel to a coke collection tank; transferring the decoking fluid from the decoking vessel to a radiant combustion chamber; and burning the decoking fluid within the radiant combustion chamber.

[0091] 24. According to the method in paragraph 23, the decoking container includes a cyclone separator.

[0092] 25. The method according to paragraph 23 or 24 also includes transferring coke particles to a coke collection tank under ambient pressure.

[0093] 26. The method according to any one of paragraphs 23-25 ​​further includes storing coke particles in a coke collection tank under ambient pressure.

[0094] 27. The method according to any one of paragraphs 23-26 further includes: closing the valve located between the primary transfer line heat exchanger and the flow restrictor; and allowing the production effluent to flow from the primary transfer line heat exchanger to the secondary transfer line heat exchanger.

[0095] 28. The method according to paragraph 27 also includes allowing the production effluent to flow from a secondary transfer line heat exchanger to a recovery system.

[0096] 29. The method according to any one of paragraphs 23-28, before allowing the decoking effluent to flow from the main transfer line heat exchanger through the flow restrictor, further includes: allowing the production effluent to flow from the main transfer line heat exchanger to the secondary transfer line heat exchanger; closing a first valve disposed between the main transfer line heat exchanger and the secondary transfer line heat exchanger; opening a second valve disposed between the main transfer line heat exchanger and the flow restrictor; and allowing the decoking effluent to flow from the main transfer line heat exchanger through the flow restrictor.

[0097] 30. A furnace system for cracking hydrocarbons by means of any one of paragraphs 23-29.

[0098] While the forms disclosed herein are described in the context of use in furnaces or industrial furnaces, such as those used for the production of ethylene, it will be apparent to those skilled in the art that the teachings provided herein also apply to other process components and methods, such as pyrolysis or cracking of other feedstocks, refining processes, and boilers. Therefore, the term "furnace" herein should be understood to mean furnace, boiler, and other applicable equipment, process components, and methods.

[0099] In summary, furnace systems and methods for cracking hydrocarbons, especially methods for steam cracking hydrocarbons to produce ethylene, offer enhanced energy efficiency while successfully removing coke from the cracking process.

[0100] This application also relates to the following implementation schemes:

[0101] 1. A furnace system for cracking hydrocarbons, comprising:

[0102] A radiant combustion chamber containing multiple burners and injection nozzles;

[0103] The heat exchanger is in fluid connection with the radiant combustion chamber and is located downstream of the main transfer pipeline.

[0104] A flow restrictor that is fluidly connected to the heat exchanger of the main transfer pipeline and located downstream;

[0105] A decoking container, comprising an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to a flow restrictor downstream, and the fluid outlet is fluidly connected to the injection nozzle of a radiant burner upstream; and

[0106] At least one (a) movable coke collection tank connected to the coke outlet of the decoking vessel and (b) stationary coke collection tank connected to the coke outlet of the decoking vessel and adapted to convey coke from the furnace system.

[0107] 2. The furnace system according to embodiment 1 further includes a valve disposed between the main transfer pipeline heat exchanger and the flow restrictor.

[0108] 3. The furnace system according to embodiment 1 further includes a secondary transfer line heat exchanger that is fluidly connected to the primary transfer line heat exchanger and downstream of it and fluidly connected to the flow restrictor.

[0109] 4. The furnace system according to embodiment 3 further includes a valve disposed between the primary transfer line heat exchanger and the secondary transfer line heat exchanger.

[0110] 5. The furnace system according to embodiment 3, wherein the secondary transfer line heat exchanger includes an inlet and an outlet, wherein the inlet of the secondary transfer line heat exchanger is fluidly connected to the outlet of the primary transfer line heat exchanger, and the outlet of the secondary transfer line heat exchanger is fluidly connected to the recovery system.

[0111] 6. The furnace system according to embodiment 1, wherein the decoking container includes a cyclone separator.

[0112] 7. The furnace system according to embodiment 6, wherein the cyclone separator is configured as follows:

[0113] The decoking effluent is received through the effluent inlet.

[0114] The decoking effluent is separated into coke particles and decoking fluid, and

[0115] Coke particles are transferred from the coke outlet to the coke collection tank, and decoking fluid is transferred from the fluid outlet to the injection nozzle.

[0116] 8. The furnace system according to embodiment 1, wherein a coke collection tank is configured to store coke particles under ambient pressure.

[0117] 9. The furnace system according to embodiment 1, wherein at least a portion of the plurality of burners is located on the bottom surface of the radiant combustion chamber.

[0118] 10. The furnace system according to embodiment 1, wherein the injection nozzle is adjacent to at least a portion of a plurality of burners.

[0119] 11. The furnace system according to embodiment 1, wherein the radiant combustion chamber further comprises one or more coils disposed therein.

[0120] 12. The furnace system according to embodiment 11, wherein the coil comprises a radiant coil, a convection coil, or any combination thereof.

[0121] 13. A furnace system for cracking hydrocarbons, comprising:

[0122] A radiant combustion chamber containing multiple burners and injection nozzles;

[0123] The heat exchanger is in fluid connection with the radiant combustion chamber and is located downstream of the main transfer pipeline.

[0124] A secondary transfer line heat exchanger that is fluidly connected to the main transfer line heat exchanger and is located downstream;

[0125] A first valve is installed between the main transfer pipeline heat exchanger and the secondary transfer pipeline heat exchanger;

[0126] The decoke effluent line is fluidly connected to the main transfer line heat exchanger downstream and fluidly connected to the first valve upstream;

[0127] A second valve located downstream of the main transfer line heat exchanger, in fluid connection to the decoking effluent pipeline;

[0128] A flow restrictor downstream of the second valve is fluidly connected to the decoking effluent pipeline;

[0129] A decoking vessel fluidly connected to a decoking effluent line and comprising an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to a flow restrictor downstream, and the fluid outlet is fluidly connected to the injection nozzle of a radiant burner upstream; and

[0130] At least one (a) movable coke collection tank connected to the coke outlet of the decoking vessel and (b) stationary coke collection tank connected to the coke outlet of the decoking vessel and adapted to convey coke from the furnace system.

[0131] 14. The furnace system according to embodiment 13, wherein the decoking container includes a cyclone separator.

[0132] 15. The furnace system according to embodiment 14, wherein the cyclone separator is configured as follows:

[0133] The decoking effluent is received through the effluent inlet.

[0134] The decoking effluent is separated into coke particles and decoking fluid, and

[0135] Coke particles are transferred from the coke outlet to the coke collection tank, and decoking fluid is transferred from the fluid outlet to the injection nozzle.

[0136] 16. The furnace system according to embodiment 13, wherein the movable coke collection tank is configured to store coke particles under ambient pressure.

[0137] 17. The furnace system according to embodiment 13, wherein the radiant combustion chamber further comprises one or more coils disposed therein, and wherein the coils comprise radiant coils, convection coils, or any combination thereof.

[0138] 18. A furnace system for cracking hydrocarbons, comprising:

[0139] A radiant combustion chamber comprising a plurality of burners, injection nozzles and one or more coils, wherein the coils comprise radiant coils, convection coils or any combination thereof;

[0140] The heat exchanger is in fluid connection with the radiant combustion chamber and is located downstream of the main transfer pipeline.

[0141] A secondary transfer line heat exchanger that is fluidly connected to the main transfer line heat exchanger and is located downstream;

[0142] A first valve is installed between the main transfer pipeline heat exchanger and the secondary transfer pipeline heat exchanger;

[0143] The decoke effluent line is fluidly connected to the main transfer line heat exchanger downstream and fluidly connected to the first valve upstream;

[0144] A second valve located downstream of the main transfer line heat exchanger, in fluid connection to the decoking effluent pipeline;

[0145] A flow restrictor downstream of the second valve is fluidly connected to the decoking effluent pipeline;

[0146] A decoking vessel fluidly connected to a decoking effluent line and comprising an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to a flow restrictor downstream, and the fluid outlet is fluidly connected to the injection nozzle of a radiant burner upstream, wherein the decoking vessel includes a cyclone separator configured as follows:

[0147] The decoking effluent is received through the effluent inlet.

[0148] The decoking effluent is separated into coke particles and decoking fluid, and

[0149] The decoking fluid is transferred via the fluid outlet to the injection nozzle; and

[0150] At least one (a) movable coke collection tank connected to the coke outlet of the decoking vessel and (b) fixed coke collection tank connected to the coke outlet of the decoking vessel and adapted to convey coke from the furnace system; wherein at least one of the movable and fixed coke collection tanks has an internal volume containing coke particles under ambient pressure.

[0151] 19. A method for cracking hydrocarbons in a cracking furnace, comprising:

[0152] During the decoking mode, the decoking effluent is flowed from the radiant combustion chamber through the main transfer line heat exchanger.

[0153] The decoking effluent flows from the main transfer pipeline heat exchanger through the flow restrictor;

[0154] This allows the decoking effluent to flow from the flow restrictor to the decoking container;

[0155] The decoking effluent is separated into coke particles and decoking fluid within the decoking container;

[0156] The decoking fluid is transferred from the decoking container to the radiant combustion chamber;

[0157] The decoking fluid is burned in the radiant combustion chamber;

[0158] Transferring coke particles from the decoking container to the coke collection tank; and

[0159] At least a portion of the coke particles are transferred from the collection tank from the cracking furnace.

[0160] 20. The method according to embodiment 19, wherein the decoking container includes a cyclone separator.

[0161] 21. The method according to embodiment 19 further includes transferring coke particles to a coke collection tank under environmental pressure.

[0162] 22. The method according to embodiment 19 further includes storing coke particles in a coke collection tank under ambient pressure.

[0163] 23. The method according to implementation scheme 19 further includes:

[0164] Close the valve located between the heat exchanger and the flow restrictor in the main transfer pipeline; and

[0165] This allows the production effluent to flow from the primary transfer line heat exchanger to the secondary transfer line heat exchanger.

[0166] 24. The method according to embodiment 23 further includes causing the production effluent to flow from the secondary transfer line heat exchanger to the recovery system.

[0167] 25. The method according to embodiment 19, wherein before allowing the decoking effluent to flow from the main transfer line exchanger through the flow restrictor, the method further includes:

[0168] The production effluent flows from the primary transfer pipeline heat exchanger to the secondary transfer pipeline heat exchanger.

[0169] Close the first valve located between the main transfer pipeline heat exchanger and the secondary transfer pipeline heat exchanger.

[0170] Open the second valve located between the heat exchanger and the flow restrictor in the main transfer pipeline; and

[0171] The decoking effluent flows from the main transfer pipeline heat exchanger through the flow restrictor.

[0172] All documents mentioned herein are incorporated herein by reference, including any priority documents and / or test procedures, provided they do not contradict this document. As will be apparent from the foregoing general description and specific embodiments, various changes may be made to this disclosure without departing from its spirit and scope, although the form of this disclosure has been set forth and described. Therefore, it is not intended to limit the scope of this disclosure.

[0173] Certain embodiments and features have been described using a set of upper limits and a set of lower limits. It should be understood that, unless otherwise stated, the scope encompasses a range including any combination of two values, such as any lower limit value combined with any upper limit value, any combination of two lower limits, and / or any combination of two upper limits. Certain lower limits, upper limits, and ranges appear in one or more of the following claims.

Claims

1. A furnace system for cracking hydrocarbons, comprising: A radiant combustion chamber containing multiple burners and injection nozzles; The heat exchanger is in fluid connection with the radiant combustion chamber and is located downstream of the main transfer pipeline. A secondary transfer line heat exchanger that is fluidly connected to the main transfer line heat exchanger and is located downstream; A first valve is installed between the main transfer pipeline heat exchanger and the secondary transfer pipeline heat exchanger; The decoke effluent line is fluidly connected to the main transfer line heat exchanger downstream and fluidly connected to the first valve upstream; A second valve located downstream of the main transfer line heat exchanger, in fluid connection to the decoking effluent pipeline; A flow restrictor downstream of the second valve is fluidly connected to the decoking effluent pipeline; A decoking container, which is fluidly connected to a decoking effluent pipeline and includes an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to a flow restrictor downstream, and the fluid outlet is fluidly connected to the injection nozzle of a radiant burner upstream; and At least one of the following: (a) a movable coke collection tank connected to the coke outlet of the decoking vessel and (b) a fixed coke collection tank connected to the coke outlet of the decoking vessel and adapted to convey coke from the furnace system. There is no flow restrictor between the fluid outlet and the injection nozzle.

2. The furnace system of claim 1, wherein the secondary transfer line heat exchanger includes an inlet and an outlet, wherein the inlet of the secondary transfer line heat exchanger is fluidly connected to the outlet of the primary transfer line heat exchanger, and the outlet of the secondary transfer line heat exchanger is fluidly connected to the recovery system.

3. The furnace system according to any one of claims 1-2, wherein the decoking container is configured to operate under ambient pressure.

4. The furnace system of claim 1, wherein the decoking container comprises a cyclone separator.

5. The furnace system according to claim 4, wherein the cyclone separator is configured as follows: The decoking effluent is received through the effluent inlet. The decoking effluent is separated into coke particles and decoking fluid, and Coke particles are transferred from the coke outlet to the coke collection tank, and decoking fluid is transferred from the fluid outlet to the injection nozzle.

6. The furnace system of claim 1, wherein a coke collection tank is configured to store coke particles under ambient pressure.

7. The furnace system of claim 1, wherein at least a portion of the plurality of burners is located on the bottom surface of the radiant combustion chamber.

8. The furnace system of claim 1, wherein the injection nozzle is adjacent to at least a portion of the plurality of burners.

9. The furnace system of claim 1, wherein the radiant combustion chamber further comprises one or more coils disposed therein.

10. The furnace system of claim 9, wherein the coil comprises a radiant coil, a convection coil, or any combination thereof.

11. A furnace system for cracking hydrocarbons, comprising: A radiant combustion chamber comprising a plurality of burners, injection nozzles and one or more coils, wherein the coils comprise radiant coils, convection coils or any combination thereof; The heat exchanger is in fluid connection with the radiant combustion chamber and is located downstream of the main transfer pipeline. A secondary transfer line heat exchanger that is fluidly connected to the main transfer line heat exchanger and is located downstream; A first valve is installed between the main transfer pipeline heat exchanger and the secondary transfer pipeline heat exchanger; The decoke effluent line is fluidly connected to the main transfer line heat exchanger downstream and fluidly connected to the first valve upstream; A second valve located downstream of the main transfer line heat exchanger, in fluid connection to the decoking effluent pipeline; A flow restrictor downstream of the second valve is fluidly connected to the decoking effluent pipeline; A decoking vessel fluidly connected to a decoking effluent line and comprising an effluent inlet, a fluid outlet, and a coke outlet, wherein the effluent inlet is fluidly connected to a flow restrictor downstream, and the fluid outlet is fluidly connected to the injection nozzle of a radiant burner upstream, wherein the decoking vessel includes a cyclone separator configured as follows: The decoking effluent is received through the effluent inlet. The decoking effluent is separated into coke particles and decoking fluid, and The decoking fluid is transferred to the injection nozzle via the fluid outlet; and At least one of the following: (a) a movable coke collection tank connected to the coke outlet of the decoking vessel and (b) a stationary coke collection tank connected to the coke outlet of the decoking vessel and adapted to convey coke from the furnace system; wherein at least one of the movable and stationary coke collection tanks has an internal volume containing coke particles under ambient pressure. There is no flow restrictor between the fluid outlet and the injection nozzle.

12. The furnace system of claim 11, wherein the decoking container is configured to operate under ambient pressure.

13. A method for cracking hydrocarbons in a cracking furnace, comprising: During the decoking mode, the decoking effluent is flowed from the radiant combustion chamber through the main transfer line heat exchanger. The decoking effluent flows from the main transfer pipeline heat exchanger through the flow restrictor; This allows the decoking effluent to flow from the flow restrictor to the decoking container; The decoking effluent is separated into coke particles and decoking fluid within the decoking container; The decoking fluid is transferred from the decoking container to the radiant combustion chamber; The decoking fluid is burned in the radiant combustion chamber; Transfer coke particles from the decoking container to the coke collection tank; and At least a portion of the coke particles are transferred from the collection tank from the cracking furnace. There is no flow restrictor between the fluid outlet and the injection nozzle; Also includes: Close the valve located between the heat exchanger and the flow restrictor in the main transfer pipeline; and The production effluent flows from the primary transfer pipeline heat exchanger to the secondary transfer pipeline heat exchanger. The method further includes, before allowing the decoking effluent to flow from the main transfer line exchanger through the flow restrictor: The production effluent flows from the primary transfer pipeline heat exchanger to the secondary transfer pipeline heat exchanger. Close the first valve located between the main transfer pipeline heat exchanger and the secondary transfer pipeline heat exchanger. Open the second valve located between the heat exchanger and the flow restrictor in the main transfer pipeline; and The decoking effluent flows from the main transfer pipeline heat exchanger through the flow restrictor.

14. The method of claim 13, wherein the decoking container is configured to operate under ambient pressure.

15. The method of claim 13, wherein the decoking container comprises a cyclone separator.

16. The method of claim 13, further comprising transferring coke particles to a coke collection tank under ambient pressure.

17. The method of claim 13, further comprising storing coke particles in a coke collection tank under ambient pressure.

18. The method of claim 13, further comprising causing the production effluent to flow from a secondary transfer line heat exchanger to a recovery system.

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