Gas-phase raw material cracking system and raw material distribution method

Abstract

The invention provides a gas-phase raw material cracking system and a raw material distribution method. The system comprises a plurality of feeding pipelines, wherein each feeding pipeline comprises a main pipeline and a plurality of branch pipelines connected with the main pipeline; the cracking device comprises a plurality of cracking furnaces, branch pipelines of the feeding pipelines are connected with the cracking furnaces, main pipelines of the feeding pipelines are arranged side by side, every two adjacent main pipelines are connected through a communicating pipeline, and a switch valve is arranged in each communicating pipeline. The system can improve the problem of unstable load of the cracking furnace, so that the working condition of the cracking furnace is relatively stable, and the operation cycle of the cracking furnace is prolonged. Moreover, the system can realize automatic and stable switching of the raw materials, and does not need to synchronously open and close the feeding valves of the two cracking furnaces, so that the problem of feeding interruption caused by misoperation is effectively improved, the occurrence of secondary accidents is reduced, and the system can stably run for a long period.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical production, in particular, to a gas phase raw material cracking system and a raw material distribution method. BACKGROUND

[0002] Ethylene is a basic raw material of petrochemical industry, and the production of ethylene is an important indicator of the development level of a country's petrochemical industry. The ethylene production system transports and distributes gas phase raw materials to different cracking furnaces through a feed pipe. In the process of cracking the gas phase raw material, the raw material entering the cracking furnace needs to be switched, and the cracking furnace in the end of the operation period needs to be cut out of the system and the cracking furnace in the standby state after the coke burning is completed needs to be cut into the system. In the switching process, the cracking furnace in the cut-in system is fed for production, and the cracking furnace in the cut-out system is withdrawn for offline preparation for coke burning. SUMMARY

[0003] The present application is made based on the discovery and understanding of the inventors on the following facts and problems:

[0004] The inventors found that the current gas phase raw material cracking system has the problems of short operation period and easy interruption of cracking furnace feeding during switching. Specifically, referring to Figure 2 , the current gas phase raw material cracking system supplies different gas phase raw materials to corresponding cracking furnaces through different feed pipes. Each cracking furnace has a predetermined load. Under normal feeding conditions, the feed pipe supplies the cracking furnace according to its load. For example, the normal load of each cracking furnace is 30 t / h. If the first feed pipe 10 supplies two cracking furnaces, the feeding amount of the first feed pipe is 60 t / h. If the second feed pipe 20 supplies five cracking furnaces, the feeding amount of the second feed pipe is 150 t / h. If the third feed pipe 30 supplies one cracking furnace, the feeding amount of the third feed pipe is 30 t / h. The above feeding amount cannot be greatly changed. If the feeding amount of the feed pipe changes, the load of the cracking furnace supplied by the feed pipe will also change synchronously. For example, if the feeding amount of the first feed pipe is greater than 60 t / h, the load of the two cracking furnaces supplied by the first feed pipe will increase, and vice versa. The change of the load of the cracking furnace is not conducive to the long-period stable operation of the cracking furnace. In other words, the operation period of the cracking furnace is relatively short.

[0005] In addition, at the end of the operation of the cracking furnace, when coking needs to be burned, the cracking furnace needs to be unloaded, and the raw material supplied thereto is switched to another cracking furnace. For example, under normal feeding conditions, the first cracking furnace 110 is supplied with the third raw material, and the third cracking furnace 130 is supplied with the first raw material. When the first cracking furnace 110 is unloaded, the third raw material supplied to the first cracking furnace 110 is switched to the third cracking furnace 130. The feeding valve of the third cracking furnace 130 for the first raw material needs to be closed, the feeding valve of the third cracking furnace 130 for the third raw material needs to be opened, and the feeding valve of the first cracking furnace 110 for the third raw material needs to be closed. The opening and closing of the above-mentioned feeding valves need to be synchronized to change the raw material entering the third cracking furnace to realize switching. However, in actual operation, if the operation is not proper, for example, the feeding valve is closed too quickly or opened too slowly, the feeding of the third cracking furnace will be interrupted, the temperature of the furnace tube of the third cracking furnace will rise rapidly, and even the furnace tube will be broken, causing secondary accidents, which is not conducive to the long-period operation of the device.

[0006] It should be noted that the above related technical information is only used to strengthen the understanding of the background of the present application, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art.

[0007] The present application aims to at least partially solve one of the technical problems in the related art.

[0008] To this end, in one aspect of the present application, a gas-phase raw material cracking system is provided, which comprises: a plurality of feeding pipes, each of which comprises a main pipe and a plurality of branch pipes connected to the main pipe; and a cracking device comprising a plurality of cracking furnaces, wherein the branch pipes of the feeding pipes are connected to the cracking furnaces, and wherein the main pipes of the plurality of feeding pipes are arranged side by side, and two adjacent main pipes are connected by a communication pipe, and a switch valve is arranged in the communication pipe.

[0009] Further, the diameter of the communication pipe and the diameter of the main pipe with the smaller diameter among the two main pipes connected thereto are consistent.

[0010] Further, the gas-phase raw material cracking system comprises a first feeding pipe, a second feeding pipe, and a third feeding pipe, the main pipe of the first feeding pipe and the main pipe of the second feeding pipe are connected by a first communication pipe, and the main pipe of the first feeding pipe and the main pipe of the third feeding pipe are connected by a second communication pipe.

[0011] Further, the cracking device comprises a first cracking furnace, a second cracking furnace, a third cracking furnace, a fourth cracking furnace, a fifth cracking furnace, a sixth cracking furnace, a seventh cracking furnace and an eighth cracking furnace, the third supply pipeline has two branch pipelines, the two branch pipelines are connected with the first cracking furnace and the third cracking furnace respectively, the first supply pipeline has eight branch pipelines, the eight branch pipelines are connected with the eight cracking furnaces respectively, and the second supply pipeline has six branch pipelines, the six branch pipelines are connected with the second cracking furnace, the fourth cracking furnace, the fifth cracking furnace, the sixth cracking furnace, the seventh cracking furnace and the eighth cracking furnace respectively.

[0012] Further, the gas-phase raw material cracking system further comprises a cooling device, a compression device and a separation device connected in sequence, the cooling device is connected with the cracking device, the feed inlet of the third supply pipeline is connected with the separation device, and the first supply pipeline comprises two feed inlets, one of which is connected with the separation device.

[0013] The gas-phase raw material cracking system has the following advantages:

[0014] The gas-phase raw material cracking system can improve the problem of unstable cracking furnace load, make the working condition of the cracking furnace relatively stable, prolong the operation cycle of the cracking furnace, realize automatic and stable switching of raw materials, avoid the need to synchronously open and close the feed valves of two cracking furnaces, effectively improve the problem of feed interruption caused by improper operation, reduce the occurrence of secondary accidents, and make the system run stably for a long period.

[0015] In another aspect of the present application, a method for distributing raw materials by using the above-mentioned gas-phase raw material cracking system is provided, the method comprising: when the feed amount of the supply pipeline changes, at least opening the on-off valve of the communication pipeline connected with the supply pipeline whose feed amount changes, and keeping the total feed amount of the communication supply pipeline unchanged; or when the raw material entering the cracking furnace is switched, at least opening the on-off valve of the communication pipeline between the supply pipeline supplying the raw material to be switched and the supply pipeline supplying the raw material to be switched, and allowing the raw material to be switched to displace the raw material to be switched from the cracking furnace.

[0016] Further, the gas-phase raw material cracking system comprises a first feeding pipe, a second feeding pipe and a third feeding pipe, a total pipe of the first feeding pipe and a total pipe of the second feeding pipe are connected through a first communication pipe, a total pipe of the first feeding pipe and a total pipe of the third feeding pipe are connected through a second communication pipe, a feeding amount of the first feeding pipe is a first preset feeding amount, a feeding amount of the second feeding pipe is a second preset feeding amount, a feeding amount of the third feeding pipe is a third preset feeding amount, when the feeding amount of at least one of the first feeding pipe, the second feeding pipe and the third feeding pipe changes, opening the switch valves of the first communication pipe and the second communication pipe, and keeping the total feeding amount of the first feeding pipe, the second feeding pipe and the third feeding pipe as the sum of the first preset feeding amount, the second preset feeding amount and the third preset feeding amount.

[0017] Further, the gas-phase raw material cracking system comprises a first feeding pipe, a second feeding pipe and a third feeding pipe, a total pipe of the first feeding pipe and a total pipe of the second feeding pipe are connected through a first communication pipe, a total pipe of the first feeding pipe and a total pipe of the third feeding pipe are connected through a second communication pipe, the method further comprises: when the feeding amount of the first feeding pipe meets the first preset feeding amount, the feeding amount of the second feeding pipe meets the second preset feeding amount, and the feeding amount of the third feeding pipe meets the third preset feeding amount, closing the switch valves of the first communication pipe and the second communication pipe.

[0018] Further, the gas-phase raw material cracking system comprises a first feeding pipe, a second feeding pipe and a third feeding pipe, a total pipe of the first feeding pipe and a total pipe of the second feeding pipe are connected through a first communication pipe, a total pipe of the first feeding pipe and a total pipe of the third feeding pipe are connected through a second communication pipe, when the raw material supplied to an initial cracking furnace is switched to other cracking furnaces to switch the raw material entering the other cracking furnaces, opening the switch valves of the first communication pipe and the second communication pipe, opening the feeding valve of the raw material to be switched in the other cracking furnaces, and closing the feeding valve of the raw material to be switched in the initial cracking furnace.

[0019] Further, the raw material supplied by the first feeding pipe comprises propane, the raw material supplied by the second feeding pipe comprises propane and liquefied petroleum gas, and the raw material supplied by the third feeding pipe comprises ethane.

[0020] The raw material distribution method has the following advantages:

[0021] 1. The raw material distribution mode of the present application keeps the total feed amount of the gas-phase raw material constant by opening the communication pipeline to make the feed pipelines communicate, thereby maintaining the load of the cracking furnace unchanged and keeping the working condition of the cracking furnace relatively stable, and prolonging the operation cycle of the cracking furnace.

[0022] 2. The raw material distribution mode of the present application keeps the total feed amount of the gas-phase raw material constant by opening the communication pipeline to make the feed pipelines communicate, and opening the feed valve of the raw material to be switched in the cracking furnace to be switched, and with the closing of the feed valve of the raw material to be switched in the initial cracking furnace, the raw material to be switched will automatically and smoothly enter the cracking furnace to be switched, and the switched raw material will be replaced, thereby improving the problem of feed interruption caused by improper operation, reducing the occurrence of secondary accidents, and enabling the system to operate stably for a long period. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor.

[0024] Figure 1 A structural schematic diagram of a gas-phase raw material cracking system according to an embodiment of the present application is shown;

[0025] Figure 2 A structural schematic diagram of a gas-phase raw material cracking system of the related art is shown.

[0026] Reference signs:

[0027] 10: first feed pipeline; 11: main pipeline of the first feed pipeline; 12A / 12B / 12C / 12D / 12E / 12F / 12G / 12H: branch pipelines of the first feed pipeline; 20: second feed pipeline; 21: main pipeline of the second feed pipeline; 22A / 22B / 22C / 22D / 22E / 22F: branch pipelines of the second feed pipeline; 30: third feed pipeline; 31: main pipeline of the third feed pipeline; 32A / 32B: branch pipelines of the third feed pipeline; 40: first communication pipeline; 41: on-off valve of the first communication pipeline; 50: second communication pipeline; 51: on-off valve of the second communication pipeline; 110: first cracking furnace; 120: second cracking furnace; 130: third cracking furnace; 140: fourth cracking furnace; 150: fifth cracking furnace; 160: sixth cracking furnace; 170: seventh cracking furnace; 180: eighth cracking furnace. DETAILED DESCRIPTION

[0028] Embodiments of the present application are described in detail below. The embodiments described below are exemplary only and are not intended to be limiting of the present application. Unless otherwise indicated, technical or scientific terms used in the embodiments have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Technical or scientific terms used in the embodiments are not intended to be limited to any particular technical or scientific term unless otherwise indicated.

[0029] In one aspect of the present application, a gas-phase feedstock cracking system is provided. In some embodiments of the present application, referring to Figure 1 , the gas-phase feedstock cracking system comprises a plurality of feed lines (e.g., a first feed line 10, a second feed line 20, and a third feed line 30 as shown in Figure 1 ) and a cracking device, wherein each feed line comprises a main line and a plurality of branch lines connected to the main line, for example, the first feed line 10 comprises a main line 11 and a plurality of branch lines (e.g., branch lines 12A, 12B, 12C, 12D, 12E, 12F, 12G, 12H of the first feed line as shown in Figure 1 ) connected to the main line 11, the second feed line 20 comprises a main line 21 and a plurality of branch lines (e.g., branch lines 22A, 22B, 22C, 22D, 22E, 22F of the second feed line as shown in Figure 1 ) connected to the main line 21, and the third feed line 30 comprises a main line 31 and a plurality of branch lines (e.g., branch lines 32A, 32B of the third feed line as shown in Figure 1 ) connected to the main line 31, and the cracking device comprises a plurality of cracking furnaces (e.g., a first cracking furnace 110, a second cracking furnace 120, a third cracking furnace 130, a fourth cracking furnace 140, a fifth cracking furnace 150, a sixth cracking furnace 160, a seventh cracking furnace 170, and an eighth cracking furnace 180 as shown in Figure 1 ), the branch lines of the feed lines are connected to the cracking furnaces to supply feedstock to the cracking furnaces, the main lines of the plurality of feed lines are arranged side by side, two adjacent main lines are connected by a communication line (e.g., a first communication line 40, a second communication line 50 as shown in Figure 1 ), and a switch valve (e.g., a switch valve 41 of the first communication line, a switch valve 51 of the second communication line as shown in Figure 1 ) is arranged in the communication line, and by controlling the opening and closing of the switch valve, the communication and disconnection of the two adjacent main lines are achieved. The system can effectively prolong the operation cycle of the cracking furnace, and in the process of switching the feedstock, the feedstock can be actively and smoothly switched, effectively improving the problem of feedstock interruption caused by improper operation, and reducing the occurrence of secondary accidents.

[0030] For ease of understanding, the process of feedstock distribution using the system is first described below:

[0031] The application sets a communication pipeline between the total pipelines of multiple feeding pipelines, opens the switch valve of the communication pipeline, and makes the total pipelines connected with the communication pipeline communicate, so that the raw materials can be flexibly distributed. Specifically, when the feeding amount of the feeding pipeline changes, the switch valve of the communication pipeline connected with the feeding pipeline with the changed feeding amount is opened, or the switch valves of all the communication pipelines are opened, so that the feeding pipelines are communicated, and the total feeding amount of the communicated feeding pipelines is controlled to remain unchanged, so that the amount of raw materials supplied to each cracking furnace remains stable, and the load of each cracking furnace remains stable, which is beneficial to prolong the operation cycle of the cracking furnace.

[0032] When the raw materials entering the cracking furnace are switched, the switch valve of the communication pipeline between the feeding pipeline supplying the raw material to be switched and the feeding pipeline supplying the switched raw material is opened, or the switch valves of all the communication pipelines are opened, so that the feeding pipelines are communicated, and the raw material to be switched replaces the switched raw material from the cracking furnace, so that the automatic and smooth switching of the raw materials can be realized, the problem of raw material interruption caused by improper operation is effectively improved, the occurrence of secondary accidents is reduced, and the long-period stable operation of the system is facilitated.

[0033] The various parts of the system will be described in detail as follows:

[0034] The specific setting position of the communication pipeline is not particularly limited, as long as the total pipelines can be communicated. For example, referring to Figure 1 , along the direction of the flow of the gas-phase raw material, the communication pipeline can be connected with the part of the total pipeline before the first branch pipeline (such as 12A, 22A and 32A shown in the figure). Alternatively, the communication pipeline can also be connected with the part of the total pipeline between two branch pipelines (this case is not shown in the figure). The switch valve in the communication pipeline can make the raw materials in the two total pipelines flow in both directions.

[0035] In some embodiments of the application, referring to Figure 1 , the gas-phase raw material cracking system can include a first feeding pipeline 10, a second feeding pipeline 20 and a third feeding pipeline 30, the total pipeline 11 of the first feeding pipeline and the total pipeline 21 of the second feeding pipeline are connected through a first communication pipeline 40, and the total pipeline 11 of the first feeding pipeline and the total pipeline 31 of the third feeding pipeline are connected through a second communication pipeline 50. Under normal feeding conditions, the feeding amount of the first feeding pipeline is a first preset feeding amount, the feeding amount of the second feeding pipeline is a second preset feeding amount, and the feeding amount of the third feeding pipeline is a third preset feeding amount, and the first preset feeding amount, the second preset feeding amount and the third preset feeding amount are determined according to the normal load of the cracking furnace supplied by the feeding pipeline.

[0036] When the feed amount of at least one of the first feed pipeline, the second feed pipeline and the third feed pipeline changes, for example, the feed amount of the first feed pipeline changes, the switch valve 41 of the first communication pipeline can be opened to make the first feed pipeline and the second feed pipeline communicate, and the total feed amount of the first feed pipeline and the second feed pipeline is controlled to remain the sum of the first preset feed amount and the second preset feed amount, so that the load of each cracking furnace remains unchanged; or the switch valve 51 of the second communication pipeline can be opened to make the first feed pipeline and the third feed pipeline communicate, and the total feed amount of the first feed pipeline and the third feed pipeline is controlled to remain the sum of the first preset feed amount and the third preset feed amount, so that the load of each cracking furnace remains unchanged; or the switch valves of the first communication pipeline and the second communication pipeline can be opened to make the first feed pipeline, the second feed pipeline and the third feed pipeline communicate, and the total feed amount of the first feed pipeline, the second feed pipeline and the third feed pipeline is controlled to remain the sum of the first preset feed amount, the second preset feed amount and the third preset feed amount, so that the load of each cracking furnace remains unchanged, and this mode is more flexible.

[0037] When the feed amount of the second feed pipeline changes, or the feed amount of the third feed pipeline changes, or the feed amount of the first feed pipeline and the second feed pipeline changes, or the feed amount of the first feed pipeline and the third feed pipeline changes, or the feed amount of the second feed pipeline and the third feed pipeline changes, or the feed amount of the first feed pipeline, the second feed pipeline and the third feed pipeline all changes, the control mode of the communication pipeline is similar to that when the feed amount of the first feed pipeline changes, which will not be listed one by one here.

[0038] In some embodiments of the present application, the pipe diameter of the communication pipeline can be consistent with the pipe diameter of the total pipeline with smaller pipe diameter connected thereto. For example, according to a specific embodiment of the present application, the total pipeline of the first feed pipeline is a DN400 pipeline, i.e. a pipeline with a nominal diameter of 400 mm, the total pipeline of the second feed pipeline is a DN600 pipeline, i.e. a pipeline with a nominal diameter of 600 mm, and the total pipeline of the third feed pipeline is a DN350 pipeline, i.e. a pipeline with a nominal diameter of 350 mm, then the first communication pipeline is a DN400 pipeline, and the second communication pipeline is a DN350 pipeline.

[0039] In some embodiments of the present application, the total pipeline of the first feed pipeline, the total pipeline of the second feed pipeline and the total pipeline of the third feed pipeline can be pipelines with different nominal diameters, and the nominal diameter of the total pipeline of the first feed pipeline is greater than the nominal diameter of the total pipeline of the second feed pipeline, and the nominal diameter of the total pipeline of the second feed pipeline is greater than the nominal diameter of the total pipeline of the third feed pipeline. Figure 1The cracking device can include a first cracking furnace 110, a second cracking furnace 120, a third cracking furnace 130, a fourth cracking furnace 140, a fifth cracking furnace 150, a sixth cracking furnace 160, a seventh cracking furnace 170, and an eighth cracking furnace 180. The third feed pipe 30 has two sub-pipes 32A and 32B, which are respectively connected to the first cracking furnace 110 and the third cracking furnace 130. For example, the sub-pipe 32A is connected to the third cracking furnace 130, and the sub-pipe 32B is connected to the first cracking furnace 110. The first feed pipe 10 has eight sub-pipes, which are respectively connected to the eight cracking furnaces. For example, the sub-pipe 12A is connected to the eighth cracking furnace 180, the sub-pipe 12B is connected to the seventh cracking furnace 170, the sub-pipe 12C is connected to the sixth cracking furnace 160, the sub-pipe 12D is connected to the fifth cracking furnace 150, the sub-pipe 12E is connected to the fourth cracking furnace 140, the sub-pipe 12F is connected to the third cracking furnace 130, the sub-pipe 12G is connected to the second cracking furnace 120, and the sub-pipe 12H is connected to the first cracking furnace 110. The second feed pipe 20 has six sub-pipes, which are respectively connected to the second cracking furnace 120, the fourth cracking furnace 140, the fifth cracking furnace 150, the sixth cracking furnace 160, the seventh cracking furnace 170, and the eighth cracking furnace 180. For example, the sub-pipe 22A is connected to the eighth cracking furnace 180, the sub-pipe 22B is connected to the seventh cracking furnace 170, the sub-pipe 22C is connected to the sixth cracking furnace 160, the sub-pipe 22D is connected to the fifth cracking furnace 150, the sub-pipe 22E is connected to the fourth cracking furnace 140, and the sub-pipe 22F is connected to the second cracking furnace 120.

[0040] It should be noted that in the present application, the first cracking furnace 110, the second cracking furnace 120, the third cracking furnace 130, the fourth cracking furnace 140, the fifth cracking furnace 150, the sixth cracking furnace 160, the seventh cracking furnace 170, and the eighth cracking furnace 180 can be single-chamber cracking furnaces. Alternatively, the first cracking furnace 110 and the second cracking furnace 120 can constitute a double-chamber gas furnace, the third cracking furnace 130 and the fourth cracking furnace 140 can constitute a double-chamber gas furnace, the fifth cracking furnace 150 and the sixth cracking furnace 160 can constitute a double-chamber gas furnace, and the seventh cracking furnace 170 and the eighth cracking furnace 180 can constitute a double-chamber gas furnace.

[0041] In the present application, during normal feeding process, the operation and standby of each cracking furnace can be selected according to actual conditions, and no special limitation is made. Taking the example of the first cracking furnace 110, the second cracking furnace 120, the third cracking furnace 130, the fourth cracking furnace 140, the fifth cracking furnace 150, and the sixth cracking furnace 160 in operation, and the seventh cracking furnace 170 and the eighth cracking furnace 180 in standby, during the feeding process, the third raw material in the third feeding pipeline can enter the first cracking furnace 110 through the branch pipeline 32B, the first raw material in the first feeding pipeline can enter the third cracking furnace 130 and the second cracking furnace 120 through the branch pipelines 12F and 12G respectively, and the second raw material in the second feeding pipeline can enter the sixth cracking furnace 160, the fifth cracking furnace 150, and the fourth cracking furnace 140 through the branch pipelines 22C, 22D, and 22E respectively.

[0042] When switching the raw material entering the cracking furnace, for example, when the first cracking furnace needs to be decoked at the end of the operation, at this time, the third raw material supplied to the first cracking furnace 110 needs to be switched to the third cracking furnace 130, that is, the first raw material in the third cracking furnace 130 needs to be switched to the third raw material, the switch valve 51 of the second communication pipeline is opened to make the third feeding pipeline and the first feeding pipeline communicate, the feed valve of the third raw material in the third cracking furnace 130 is opened, and the feed valve of the third raw material in the first cracking furnace 110 is closed. Since the first feeding pipeline and the third feeding pipeline communicate, the third raw material entering the third cracking furnace can replace the first raw material in the third cracking furnace, so that the third raw material is automatically and smoothly switched from the first cracking furnace to the third cracking furnace. During the above switching process, there is always raw material in the third cracking furnace, so the problem of raw material interruption caused by improper operation can be effectively improved, which is beneficial to the long-period stable operation of the system. When the first cracking furnace is decoked and the system is cut off, the feeding amount of the first feeding pipeline can be correspondingly reduced at this time to ensure that the feeding amount of the remaining cracking furnaces remains in a normal load state. When the raw material in the third cracking furnace is switched from the first raw material to the third raw material, the feed valve of the first raw material in the third cracking furnace can be closed.

[0043] Alternatively, during the switching process, the switch valves of the first communication pipeline and the second communication pipeline are opened to make the first feeding pipeline, the second feeding pipeline, and the third feeding pipeline communicate, the feed valve of the third raw material in the third cracking furnace 130 is opened, and the feed valve of the third raw material in the first cracking furnace 110 is closed, so that the third raw material is automatically and smoothly switched from the first cracking furnace to the third cracking furnace. When the first cracking furnace is decoked and the system is cut off, the feeding amount of the first feeding pipeline or the feeding amount of the second feeding pipeline can be correspondingly reduced at this time to ensure that the feeding amount of the remaining cracking furnaces remains in a normal load state, and this mode is more flexible. When the raw material in the third cracking furnace is switched from the first raw material to the third raw material, the feed valve of the first raw material in the third cracking furnace can be closed.

[0044] The switching process of the other cracking furnaces is similar to the switching process of the third cracking furnace described above, and thus will not be described again.

[0045] In some embodiments of the present application, the first feed pipe, the second feed pipe and the third feed pipe are all fed by the external feeding device. Since the feeding processes of the feed pipes are independent, in other words, the supply of the feedstock in each feed pipe is independent, when the feed amount of a feed pipe changes, only the switch valve of the communication pipe connected to the feed pipe whose feed amount changes is opened, for example, when the feed amount of the first feed pipe changes, the switch valve of the first communication pipe is opened. When the feedstock is switched, only the switch valve of the communication pipe between the feed pipe supplying the feedstock to be switched and the feed pipe supplying the switched feedstock is opened, for example, when the third feedstock supplied to the first cracking furnace is switched to the third cracking furnace, that is, when the first feedstock in the third cracking furnace is switched to the third feedstock, the switch valve of the second communication pipe is opened. Of course, in the case of feeding by the external feeding device, whether the feed amount changes or the feedstock is switched, all the switch valves of the communication pipes can be opened.

[0046] In some embodiments of the present application, the gas-phase feedstock cracking system further comprises a cooling device, a compression device and a separation device connected in sequence, the cooling device is connected to the cracking device, the feed inlet of the third feed pipe is connected to the separation device (the separation device is not shown in the figure), and the first feed pipe comprises two feed inlets, one of which is connected to the separation device. That is, the cracking product of the cracking furnace contains the third feedstock and the first feedstock, the separation device is used to separate the cracking product, the separated third feedstock is supplied to the third feed pipe, and the separated first feedstock is supplied to the first feed pipe through one feed inlet, and the other feed inlet of the first feed pipe can be connected to the external feeding device. That is, the feedstock of the third feed pipe is supplied by the system circulation, and part of the feedstock of the first feed pipe is supplied by the system circulation, thereby realizing the recycling of resources and reducing the production cost.

[0047] In the present embodiment, when the feed amount of a feed pipe changes, all the switch valves of the communication pipes need to be opened, for example, when the feed amount of the second feed pipe changes, the amounts of the first feedstock and the third feedstock will be affected, at this time, the switch valves of the first communication pipe and the second communication pipe are opened to make all the feed pipes communicate and balance the loads of the cracking furnaces. When the feedstock is switched, all the switch valves of the communication pipes also need to be opened, for example, when the third feedstock supplied to the first cracking furnace is switched to the third cracking furnace, that is, when the first feedstock in the third cracking furnace is switched to the third feedstock, the switch valves of the first communication pipe and the second communication pipe are opened to make all the feed pipes communicate and balance the loads of the cracking furnaces while completing the switching.

[0048] The gas phase raw material for generating ethylene is relatively abundant, and due to changes in production plans, the feeding amount of different gas phase raw materials often changes, the feeding amount is frequently adjusted and the adjustment amount is large, and when the feeding amount of the gas phase raw material changes, the load of the cracking furnace in the current gas phase raw material cracking system changes with the change of the feeding amount, which causes the working condition of the cracking furnace to change frequently, easily causing the coking of the furnace tube to accelerate, and is not conducive to the long-period operation of the cracking furnace. The gas phase raw material cracking system is improved, which can improve the problem of unstable load of the cracking furnace, relatively stabilize the working condition of the cracking furnace, and prolong the operation period of the cracking furnace.

[0049] In addition, when the raw material is switched, the current gas phase raw material cracking system needs to synchronously open and close the feeding valves of the two cracking furnaces, and if the operation is improper, the feeding of the cracking furnace will be interrupted, the temperature of the furnace tube will be raised, and even the furnace tube will be broken, which is not conducive to the long-period stable operation of the system. The gas phase raw material cracking system can realize automatic and stable switching of the raw material, does not need to synchronously open and close the feeding valves of the two cracking furnaces, effectively improves the problem of feeding interruption caused by improper operation, reduces the occurrence of secondary accidents, and enables the system to operate stably for a long period.

[0050] In another aspect of the present application, a method for distributing raw materials using the above-described gas phase raw material cracking system is provided. In some embodiments of the present application, the method comprises: when the feeding amount of the feeding pipeline changes, at least opening the switch valve of the communication pipeline connected to the feeding pipeline whose feeding amount changes, and keeping the total feeding amount of the communication feeding pipeline unchanged. In this way, the load of each cracking furnace can be kept stable, which is conducive to the long-period operation of the cracking furnace.

[0051] In some embodiments of the present application, with reference to Figure 1 The gas phase raw material cracking system can comprise a first feeding pipeline 10, a second feeding pipeline 20 and a third feeding pipeline 30, the total pipeline 11 of the first feeding pipeline and the total pipeline 21 of the second feeding pipeline are connected through a first communication pipeline 40, and the total pipeline 11 of the first feeding pipeline and the total pipeline 31 of the third feeding pipeline are connected through a second communication pipeline 50. Under normal feeding conditions, the feeding amount of the first feeding pipeline is a first preset feeding amount, the feeding amount of the second feeding pipeline is a second preset feeding amount, and the feeding amount of the third feeding pipeline is a third preset feeding amount, and the first preset feeding amount, the second preset feeding amount and the third preset feeding amount are determined according to the normal load of the cracking furnace supplied by the feeding pipeline.

[0052] When the feed amount of at least one of the first feed pipeline, the second feed pipeline and the third feed pipeline changes, for example, the feed amount of the first feed pipeline changes, the switch valve 41 of the first communication pipeline can be opened to make the first feed pipeline and the second feed pipeline communicate, and the total feed amount of the first feed pipeline and the second feed pipeline is controlled to be the sum of the first preset feed amount and the second preset feed amount, so that the load of each cracking furnace remains unchanged; or the switch valve 51 of the second communication pipeline can be opened to make the first feed pipeline and the third feed pipeline communicate, and the total feed amount of the first feed pipeline and the third feed pipeline is controlled to be the sum of the first preset feed amount and the third preset feed amount, so that the load of each cracking furnace remains unchanged; or the switch valves of the first communication pipeline and the second communication pipeline can be opened to make the first feed pipeline, the second feed pipeline and the third feed pipeline communicate, and the total feed amount of the first feed pipeline, the second feed pipeline and the third feed pipeline is controlled to be the sum of the first preset feed amount, the second preset feed amount and the third preset feed amount, so that the load of each cracking furnace remains unchanged, and this mode is more flexible.

[0053] In some embodiments of the present application, the first feed pipeline, the second feed pipeline and the third feed pipeline can be fed by independent external supply devices. Since the feeding processes of the feed pipelines are independent, when the feed amount of a feed pipeline changes, only the switch valve of the communication pipeline connected to the feed pipeline with the changed feed amount needs to be opened, for example, when the feed amount of the first feed pipeline changes, the switch valve of the first communication pipeline is opened. Alternatively, the raw material of the third feed pipeline is supplied by system circulation, and part of the raw material of the first feed pipeline is supplied by system circulation. When the feed amount of a feed pipeline changes, the switch valves of all communication pipelines need to be opened, for example, when the feed amount of the second feed pipeline changes, the amount of the first raw material and the third raw material will be affected, so the switch valves of the first communication pipeline and the second communication pipeline are opened to make all feed pipelines communicate and balance the load of each cracking furnace. Of course, when the feed pipelines are fed by external supply devices, the switch valves of all communication pipelines can also be opened.

[0054] In some embodiments of the present application, the feed pressure of the third raw material in the third feed pipeline is higher, and when the feed amount of the third raw material is larger, the third raw material is preferentially supplemented into other feed pipelines, so the components of the third raw material in the first cracking furnace or the third cracking furnace for cracking the third raw material are more stable.

[0055] In some embodiments of the present application, the method further comprises: when the feeding amount of the first feeding pipeline meets the first preset feeding amount, the feeding amount of the second feeding pipeline meets the second preset feeding amount, and the feeding amount of the third feeding pipeline meets the third preset feeding amount, closing the switch valve of the first communication pipeline and the second communication pipeline. That is, when the feeding amount of each feeding pipeline meets the feeding condition, the switch valve of the communication pipeline can be closed, so that the components of the raw materials entering each cracking furnace are relatively stable.

[0056] In some embodiments of the present application, the method further comprises: when switching the raw materials entering the cracking furnace, at least opening the switch valve of the communication pipeline between the feeding pipeline supplying the raw material to be switched and the feeding pipeline supplying the raw material to be switched, and allowing the raw material to be switched to displace the raw material to be switched from the cracking furnace. Thus, automatic and smooth switching of the raw materials can be realized, the problem of feeding interruption caused by improper operation can be effectively improved, secondary accidents can be reduced, and the system can be stably operated for a long period.

[0057] Specifically, referring to Figure 1 , the cracking device can include a first cracking furnace 110, a second cracking furnace 120, a third cracking furnace 130, a fourth cracking furnace 140, a fifth cracking furnace 150, a sixth cracking furnace 160, a seventh cracking furnace 170, and an eighth cracking furnace 180. The third feeding pipeline 30 has two sub-pipelines 32A and 32B, and the two sub-pipelines are connected to the first cracking furnace 110 and the third cracking furnace 130, respectively. For example, the sub-pipeline 32A is connected to the third cracking furnace 130, and the sub-pipeline 32B is connected to the first cracking furnace 110. The first feeding pipeline 10 has eight sub-pipelines, and the eight sub-pipelines are connected to the eight cracking furnaces, respectively. For example, the sub-pipeline 12A is connected to the eighth cracking furnace 180, the sub-pipeline 12B is connected to the seventh cracking furnace 170, the sub-pipeline 12C is connected to the sixth cracking furnace 160, the sub-pipeline 12D is connected to the fifth cracking furnace 150, the sub-pipeline 12E is connected to the fourth cracking furnace 140, the sub-pipeline 12F is connected to the third cracking furnace 130, the sub-pipeline 12G is connected to the second cracking furnace 120, and the sub-pipeline 12H is connected to the first cracking furnace 110. The second feeding pipeline 20 has six sub-pipelines, and the six sub-pipelines are connected to the second cracking furnace 120, the fourth cracking furnace 140, the fifth cracking furnace 150, the sixth cracking furnace 160, the seventh cracking furnace 170, and the eighth cracking furnace 180, respectively. For example, the sub-pipeline 22A is connected to the eighth cracking furnace 180, the sub-pipeline 22B is connected to the seventh cracking furnace 170, the sub-pipeline 22C is connected to the sixth cracking furnace 160, the sub-pipeline 22D is connected to the fifth cracking furnace 150, the sub-pipeline 22E is connected to the fourth cracking furnace 140, and the sub-pipeline 22F is connected to the second cracking furnace 120.

[0058] It should be noted that in the present application, the first cracking furnace 110, the second cracking furnace 120, the third cracking furnace 130, the fourth cracking furnace 140, the fifth cracking furnace 150, the sixth cracking furnace 160, the seventh cracking furnace 170 and the eighth cracking furnace 180 can be single-chamber cracking furnaces respectively. Alternatively, the first cracking furnace 110 and the second cracking furnace 120 constitute a double-chamber gas furnace, the third cracking furnace 130 and the fourth cracking furnace 140 constitute a double-chamber gas furnace, the fifth cracking furnace 150 and the sixth cracking furnace 160 constitute a double-chamber gas furnace, and the seventh cracking furnace 170 and the eighth cracking furnace 180 constitute a double-chamber gas furnace.

[0059] In the present application, during normal feeding, the operation and standby of each cracking furnace can be selected according to actual conditions, and no special limitation is made. Taking the example that the first cracking furnace 110, the second cracking furnace 120, the third cracking furnace 130, the fourth cracking furnace 140, the fifth cracking furnace 150 and the sixth cracking furnace 160 are operated, and the seventh cracking furnace 170 and the eighth cracking furnace 180 are standby, during feeding, the third raw material in the third feeding pipeline can enter the first cracking furnace 110 through the branch pipeline 32B, the first raw material in the first feeding pipeline can enter the third cracking furnace 130 and the second cracking furnace 120 through the branch pipelines 12F and 12G respectively, and the second raw material in the second feeding pipeline can enter the sixth cracking furnace 160, the fifth cracking furnace 150 and the fourth cracking furnace 140 through the branch pipelines 22C, 22D and 22E respectively.

[0060] When switching the raw material into the cracking furnace, i.e. switching the third raw material supplied to the first cracking furnace 110 (i.e. the initial cracking furnace) into the third cracking furnace 130 (i.e. the other cracking furnace), for example, i.e. switching the first raw material (i.e. the switched raw material) in the third cracking furnace 130 into the third raw material (i.e. the raw material to be switched), opening the switch valve 51 of the second communication pipeline, making the third feeding pipeline and the first feeding pipeline communicate, opening the feeding valve of the third raw material in the third cracking furnace 130, and closing the feeding valve of the third raw material in the first cracking furnace 110, since the first feeding pipeline and the third feeding pipeline communicate, the third raw material into the third cracking furnace can displace the first raw material in the third cracking furnace, so that the third raw material is automatically and smoothly switched from the first cracking furnace to the third cracking furnace, and during the above switching process, the third cracking furnace is always in a state of having raw material, so as to effectively improve the problem of raw material interruption caused by improper operation, and is beneficial to long-period stable operation of the system. The first cracking furnace is discharged for coking and cutting out the system, at this time, the feeding amount of the first feeding pipeline can be correspondingly reduced to ensure that the feeding amount of the remaining cracking furnaces remains in a normal load state, and after the raw material in the third cracking furnace is switched from the first raw material to the third raw material, the feeding valve of the first raw material in the third cracking furnace can be closed.

[0061] Alternatively, during the switching process, the switch valves of the first communication pipeline and the second communication pipeline are opened, the first feeding pipeline, the second feeding pipeline and the third feeding pipeline are made to communicate, the feeding valve of the third raw material in the third cracking furnace 130 is opened, and the feeding valve of the third raw material in the first cracking furnace 110 is closed, so that the third raw material is automatically and smoothly switched from the first cracking furnace to the third cracking furnace. The first cracking furnace is discharged for coking and cutting out the system, at this time, the feeding amount of the first feeding pipeline can be correspondingly reduced or the feeding amount of the second feeding pipeline can be correspondingly reduced to ensure that the feeding amount of the remaining cracking furnaces remains in a normal load state, and this mode is more flexible. When the raw material in the third cracking furnace is switched from the first raw material to the third raw material, the feeding valve of the first raw material in the third cracking furnace can be closed.

[0062] In some embodiments of the present application, the first feed pipe, the second feed pipe and the third feed pipe can be fed by independent external supply devices. When switching the raw materials, only the switch valves between the communication pipes of the feed pipe supplying the raw material to be switched and the feed pipe supplying the switched raw material are opened, for example, when switching the third raw material supplied to the first cracking furnace to the third cracking furnace, i.e. when switching the first raw material in the third cracking furnace to the third raw material, the switch valve of the second communication pipe is opened. Alternatively, the raw material of the third feed pipe is supplied by system circulation, and part of the raw material of the first feed pipe is supplied by system circulation. When switching the raw materials, all the switch valves of the communication pipes need to be opened, for example, when switching the third raw material supplied to the first cracking furnace to the third cracking furnace, i.e. when switching the first raw material in the third cracking furnace to the third raw material, the switch valves of the first communication pipe and the second communication pipe are opened to make all the feed pipes communicate, and at the same time, the loads of the cracking furnaces are balanced. Of course, in the case of feeding by external supply devices, all the switch valves of the communication pipes can also be opened.

[0063] In some embodiments of the present application, the raw material supplied by the first feed pipe can include propane, the raw material supplied by the second feed pipe can include propane and liquefied petroleum gas, and the raw material supplied by the third feed pipe can include ethane.

[0064] In the current raw material distribution mode, the load of the cracking furnace changes with the change of the feed amount. In the raw material distribution mode of the present application, the total feed amount of the gas phase raw material is kept constant by opening the communication pipes to make the feed pipes communicate, so as to maintain the load of the cracking furnace unchanged, make the working condition of the cracking furnace relatively stable, and prolong the operation cycle of the cracking furnace. Through the raw material distribution mode of the present application, the Venturi pressure difference of each group of furnace tubes is balanced and maintained at a high level at the end of the operation of the cracking furnace, the deviation of the surface temperature (TMT) of each group of radiant section furnace tubes is not large, and is maintained below 1050℃, without reaching the coking condition. At present, the operation cycle of each cracking furnace can be longer than the design operation cycle of 90 days, and according to the overall production arrangement, the longest operation cycle reaches 121 days.

[0065] In the current raw material distribution mode, when switching the raw materials, the feed valves of two cracking furnaces need to be opened synchronously, and the risk of secondary accidents is high. In the raw material distribution mode of the present application, the feed valves of the cracking furnaces to be switched are opened by opening the communication pipes to make the feed pipes communicate, and the feed valve of the raw material to be switched in the initial cracking furnace is closed. The raw material to be switched will automatically and smoothly enter the cracking furnace to be switched, and the switched raw material will be replaced, which improves the problem of feed interruption caused by improper operation, reduces the occurrence of secondary accidents, and enables the system to operate stably for a long period of time.

[0066] In the description of the application, the terms "first", "second", etc. are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "a plurality" is two or more, unless otherwise explicitly specified.

[0067] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. Furthermore, different embodiments or examples described in the present application and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0068] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and cannot be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A gas phase feedstock cracking system, characterized by, The application relates to a gas-phase raw material cracking system. The gas-phase raw material cracking system comprises a plurality of feeding pipes, each of the feeding pipes comprises a main pipe and a plurality of branch pipes connected with the main pipe; a cracking device comprising a plurality of cracking furnaces, the branch pipes of the feeding pipes are connected with the cracking furnaces, The main pipes of the plurality of feeding pipes are arranged side by side, and two adjacent main pipes are connected through a communication pipe, and a switch valve is arranged in the communication pipe. The diameter of the communication pipe is consistent with the diameter of one of the two main pipes connected with the communication pipe.

2. The gas phase feedstock cracking system of claim 1, wherein The gas-phase raw material cracking system comprises a first feeding pipe, a second feeding pipe and a third feeding pipe, the main pipe of the first feeding pipe and the main pipe of the second feeding pipe are connected through a first communication pipe, and the main pipe of the first feeding pipe and the main pipe of the third feeding pipe are connected through a second communication pipe.

3. The gas phase feedstock cracking system of claim 1, wherein The cracking device comprises a first cracking furnace, a second cracking furnace, a third cracking furnace, a fourth cracking furnace, a fifth cracking furnace, a sixth cracking furnace, a seventh cracking furnace and an eighth cracking furnace, the third feeding pipe has two branch pipes, the two branch pipes are connected with the first cracking furnace and the third cracking furnace respectively, the first feeding pipe has eight branch pipes, the eight branch pipes are connected with eight cracking furnaces respectively, the second feeding pipe has six branch pipes, and the six branch pipes are connected with the second cracking furnace, the fourth cracking furnace, the fifth cracking furnace, the sixth cracking furnace, the seventh cracking furnace and the eighth cracking furnace respectively.

4. The gas phase feedstock cracking system of claim 3, wherein The gas-phase raw material cracking system further comprises a cooling device, a compression device and a separation device connected in sequence, the cooling device is connected with the cracking device, the feeding inlet of the third feeding pipe is connected with the separation device, and the first feeding pipe comprises two feeding inlets, one of which is connected with the separation device.

5. The gas phase feedstock cracking system of claim 3, wherein The application relates to a gas-phase raw material cracking system.

6. A method for distributing feedstock using the gas phase feedstock cracking system according to any one of claims 1 to 5, characterized by, When the feeding amount of the feeding pipe changes, at least the switch valve of the communication pipe connected with the feeding pipe with the changed feeding amount is opened, and the total feeding amount of the connected feeding pipes is kept unchanged. When the raw material entering the cracking furnace is switched, at least the switch valve of the communication pipe between the feeding pipe supplying the to-be-switched raw material and the feeding pipe supplying the switched raw material is opened, and the to-be-switched raw material replaces the switched raw material from the cracking furnace. The gas-phase raw material cracking system comprises a first feeding pipe, a second feeding pipe and a third feeding pipe, the main pipe of the first feeding pipe and the main pipe of the second feeding pipe are connected through a first communication pipe, the main pipe of the first feeding pipe and the main pipe of the third feeding pipe are connected through a second communication pipe, the feeding amount of the first feeding pipe is a first preset feeding amount, the feeding amount of the second feeding pipe is a second preset feeding amount, and the feeding amount of the third feeding pipe is a third preset feeding amount, 7. The method of claim 6, wherein, ​ When the feed amount of at least one of the first feed pipe, the second feed pipe and the third feed pipe changes, the switch valves of the first communication pipe and the second communication pipe are opened, and the total feed amount of the first feed pipe, the second feed pipe and the third feed pipe is kept as the sum of the first preset feed amount, the second preset feed amount and the third preset feed amount.

8. The method of claim 6, wherein, The gas-phase raw material cracking system comprises a first feed pipe, a second feed pipe and a third feed pipe, the total pipe of the first feed pipe and the total pipe of the second feed pipe are connected through a first communication pipe, the total pipe of the first feed pipe and the total pipe of the third feed pipe are connected through a second communication pipe, and the method further comprises: When the feed amount of the first feed pipe meets the first preset feed amount, the feed amount of the second feed pipe meets the second preset feed amount, and the feed amount of the third feed pipe meets the third preset feed amount, the switch valves of the first communication pipe and the second communication pipe are closed.

9. The method of claim 6, wherein, The gas-phase raw material cracking system comprises a first feed pipe, a second feed pipe and a third feed pipe, the total pipe of the first feed pipe and the total pipe of the second feed pipe are connected through a first communication pipe, the total pipe of the first feed pipe and the total pipe of the third feed pipe are connected through a second communication pipe, when the raw material supplied to an initial cracking furnace is switched to other cracking furnaces for switching the raw material into the other cracking furnaces, the switch valves of the first communication pipe and the second communication pipe are opened, the feed valve of the raw material to be switched in the other cracking furnaces is opened, and the feed valve of the raw material to be switched in the initial cracking furnace is closed.

10. The method according to any one of claims 7-9, characterized in that, The raw material supplied by the first feed pipe comprises propane, the raw material supplied by the second feed pipe comprises propane and liquefied petroleum gas, and the raw material supplied by the third feed pipe comprises ethane.

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