Cracking furnace and cracking method thereof

Abstract

The present invention relates to the technical field of cracking furnaces, and in particular, to a cracking furnace and a cracking method thereof. The cracking furnace comprises: a convection section with a lower opening and a radiation section with an upper opening, and the convection section and the radiation section are connected through the lower opening and the upper opening; the radiation section comprises: a cracking furnace tube, a cracking furnace and at least one burner; each of the burners is provided with a material feed port; the convection section is provided with a cracking raw material feed port and a gas outlet; wherein the cracking furnace is used to carry out a non-catalytic partial oxidation reaction and a reforming reaction on the material to obtain a high-temperature synthesis gas, wherein the material is a mixed gas containing an oxidant and natural gas; the cracking furnace tube is used to carry out a cracking reaction on the cracking raw material; the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction. The cracking furnace can not only avoid the excessively high temperature of the cracking furnace, but also greatly reduce the CO2 concentration in the flue gas at the outlet of the cracking furnace, and is green and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of cracking furnaces, in particular to a cracking furnace and a cracking method thereof, and in particular to a cracking furnace combined with non-catalytic partial oxidation-reforming and a cracking method thereof. Background Art

[0002] The ethylene industry is the leader of the petrochemical industry, and the ethylene cracking furnace is the main production unit for organic chemical raw materials. The cracking reaction in the cracking furnace tube is a strong endothermic process. The required heat is mainly provided by the combustion of fossil fuels. A large amount of carbon dioxide will be produced during the combustion process, thereby exacerbating the greenhouse effect. Therefore, the greening of cracking furnaces has always been a research focus in the cracking field.

[0003] The non-catalytic partial oxidation reaction is to convert natural gas into synthesis gas mainly composed of hydrogen and carbon monoxide through partial oxidation reaction under the condition of no catalyst. Synthesis gas is the main raw material for most chemical synthesis, such as synthetic ammonia, synthetic methanol, olefins and ethylene glycol. Compared with other technologies, the hydrogen / carbon monoxide ratio of the synthesis gas produced by non-catalytic partial oxidation is lower, which can be used for Fischer-Tropsch synthesis and the production of chemicals such as methanol, dimethyl ether and ethylene glycol. In addition, the reaction is a strong exothermic process with a high average reaction temperature of up to 1200-1700℃, which requires the recovery of the heat of the synthesis gas, thereby increasing the system investment.

[0004] According to the strong exothermic characteristics of the non-catalytic partial oxidation reaction and the strong endothermic reaction characteristics of the ethylene cracking furnace tube, if the above two processes can be combined, it will not only solve the problem of heat recovery in the synthesis gas generation process, but also avoid the problem of excessive carbon dioxide content in the flue gas discharged by the traditional ethylene cracking furnace. However, due to the high temperature of the non-catalytic partial oxidation reaction, considering the temperature resistance limitations of the cracking furnace tube material itself, it is also necessary to solve the problem of heat matching between the two.

[0005] CN105293434A discloses a method for producing synthesis gas by combining integrated hydrocarbon heat exchange steam reforming with non-catalytic partial oxidation, using an integrated reformer, which is divided into two parts, the upper part is a free cavity, which is a gaseous hydrocarbon non-catalytic partial oxidation reaction zone, and the lower part is a shell-and-tube steam reforming reactor equipped with a catalyst, and the outside of the tube is a high-temperature synthesis gas generated in the non-catalytic partial oxidation zone; the preheated gaseous hydrocarbons and water vapor are mixed in a certain proportion and then enter the shell-and-tube steam reforming reactor, and the sensible heat of the high-temperature synthesis gas outside the tube is used to supply the heat required for steam reforming; the product of the heat exchange steam reforming and oxygen enter the non-catalytic partial oxidation zone through a nozzle in a certain proportion and then react to generate high-temperature synthesis gas, thereby realizing further conversion of gaseous hydrocarbons; the high-temperature synthesis gas is supplied to the steam reforming reaction and then led to the downstream heat recovery device by a conduit. Although the device utilizes the heat released by the non-catalytic partial oxidation, the quality of the product synthesis gas is not high, the moisture content is too high, and the temperature of the product synthesis gas of the reformer is still as high as 650-800°C, and a heat recovery device is required later. Therefore, a new cracking furnace is urgently needed. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of the existing cracking furnaces such as too high temperature in the cracking furnace and low quality of the product synthesis gas (high temperature, high moisture content, high CO2 content), and to provide a cracking furnace and a cracking method thereof. The cracking furnace can avoid excessively high temperature in the cracking furnace by utilizing the strong exothermic characteristics of the non-catalytic partial oxidation reaction of specific materials and the strong endothermic characteristics of the reforming reaction, and at the same time, effectively improve the quality of the product synthesis gas.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a cracking furnace, which comprises: a convection section with a lower opening and a radiation section with an upper opening, and the convection section and the radiation section are connected through the lower opening and the upper opening; the radiation section comprises: a cracking furnace tube, a cracking furnace and at least one burner; each of the burners is provided with a material feed port; the convection section is provided with a cracking raw material feed port and a gas outlet;

[0008] The cracking furnace is used to carry out non-catalytic partial oxidation reaction and reforming reaction on the material to obtain high-temperature synthesis gas, wherein the material is a mixed gas containing an oxidant and natural gas;

[0009] Wherein, the cracking furnace tube is used to carry out cracking reaction on the cracking raw material;

[0010] Wherein, the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction.

[0011] The second aspect of the present invention provides a cracking method, which is carried out in the cracking furnace provided in the first aspect.

[0012] Preferably, the method comprises the following steps:

[0013] The method comprises the following steps:

[0014] (1) feeding a material into a cracking furnace through a material feed port in the cracking furnace to carry out a non-catalytic partial oxidation reaction and a reforming reaction to obtain a high-temperature synthesis gas; wherein the material is a mixed gas containing an oxidant and natural gas;

[0015] (2) feeding the cracking raw material into the cracking furnace tube through the cracking raw material feed port in the cracking furnace to carry out cracking reaction;

[0016] Wherein, the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The cracking furnace provided by the present invention makes full use of the strong exothermic characteristics of the non-catalytic partial oxidation reaction of the specific material and the strong endothermic characteristics of the reforming reaction, so that the temperature of the high-temperature synthesis gas in the cracking furnace meets the temperature required by the cracking reaction in the cracking furnace tube, avoiding the excessive temperature in the cracking furnace and effectively improving the quality of the product synthesis gas of the cracking furnace, that is, reducing the temperature, moisture content and CO2 content of the product synthesis gas;

[0019] In particular, the volume flow ratio of the oxidant and the natural gas in the material is further limited, thereby regulating the temperature of the high-temperature synthesis gas and further improving the quality of the product synthesis gas;

[0020] (2) Compared with the traditional cracking furnace, the cracking furnace provided by the present invention can significantly reduce the CO2 concentration in the flue gas at the cracking furnace outlet while avoiding excessively high cracking furnace temperature, which is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a schematic structural diagram of a cracking furnace provided by the present invention.

[0022] Description of Reference Numerals

[0023] 1. Convection section 2. Radiant section 3. Cracking furnace

[0024] 4. Cracking furnace tube 5. Bottom burner 6. Side wall burner

[0025] 7. Material feed port 8. Denitrification device 9. Gas outlet

[0026] 10. Cracking raw material feed port 11. Rapid cooling boiler DETAILED DESCRIPTION

[0027] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0028] In the present invention, unless otherwise specified, the top refers to the position of 0-10% from top to bottom of the reactor; the upper part refers to the position of 10-30% from top to bottom of the reactor; the middle part refers to the position of 30-70% from top to bottom of the reactor; the lower part refers to the position of 70-90% from top to bottom of the reactor; and the bottom refers to the position of 90-100% from top to bottom of the reactor.

[0029] In the present invention, unless otherwise specified, "first" and "second" do not indicate a sequence or limit the materials or steps, but are only used to distinguish the materials or steps. For example, "first" and "second" in "first heat exchange" and "second heat exchange" are only used to distinguish that they are not the same heat exchange.

[0030] The first aspect of the present invention provides a cracking furnace, which comprises: a convection section with a lower opening and a radiation section with an upper opening, wherein the convection section and the radiation section are connected through the lower opening and the upper opening; the radiation section comprises: a cracking furnace tube, a cracking furnace and at least one burner; each of the burners is provided with a material feed port; the convection section is provided with a cracking raw material feed port and a gas outlet;

[0031] The cracking furnace is used to carry out non-catalytic partial oxidation reaction and reforming reaction on the material to obtain high-temperature synthesis gas, wherein the material is a mixed gas containing an oxidant and natural gas;

[0032] Wherein, the cracking furnace tube is used to carry out cracking reaction on the cracking raw material;

[0033] Wherein, the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction.

[0034] The inventors of the present invention have found that the non-catalytic partial oxidation reaction is a highly exothermic reaction. It does not need to burn additional fuel to provide the heat required for the reaction like the steam reforming method, so the unit energy consumption is significantly reduced. At the same time, the reaction does not require a catalyst and has no special requirements for the reactor type, so it can be combined with an ethylene cracking furnace. However, at the same time, the reaction temperature of the non-catalytic partial oxidation reaction is relatively high, usually up to 1200-1700°C, which far exceeds the temperature resistance limit of the cracking furnace tube material itself, so the reaction heat needs to be adjusted. The reforming reaction is a highly endothermic reaction, which is mainly a reforming reaction between natural gas and the water vapor generated by the non-catalytic partial oxidation reaction. On the one hand, it reduces the cracking furnace temperature, and on the other hand, it reduces the water vapor content in the synthesis gas and improves the quality of the synthesis gas.

[0035] Therefore, the non-catalytic partial oxidation reaction, reforming reaction and cracking reaction are combined, which fully utilizes the strong exothermic characteristics of the non-catalytic partial oxidation reaction and the strong endothermic characteristics of the reforming reaction and the ethylene cracking furnace tube, and fully utilizes the heat of the non-catalytic partial oxidation reaction, avoiding the high investment of heat recovery equipment in traditional synthesis gas reactors. At the same time, the CO2 emission in the flue gas at the cracking furnace outlet is reduced, and the by-product synthesis gas can be used for reactions such as Fischer-Tropsch synthesis and methanol synthesis, with high resource utilization.

[0036] In the cracking furnace provided by the present invention, the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction, that is, the temperature of the high-temperature synthesis gas meets the temperature required by the cracking reaction.

[0037] According to the present invention, preferably, the cracking furnace tube is arranged in the cracking furnace, the high-temperature synthesis gas and the cracking furnace tube perform a first heat exchange, and the heat-exchanged synthesis gas obtained enters the convection section. That is, the high-temperature synthesis gas in the cracking furnace transfers heat to the cracking furnace tube to obtain the heat-exchanged synthesis gas.

[0038] According to the present invention, preferably, the convection section is used to perform a second heat exchange on the heat-exchanged synthesis gas and the cracking feedstock to obtain a product synthesis gas converted from the heat-exchanged synthesis gas and a heated cracking feedstock converted from the cracking feedstock.

[0039] According to the present invention, preferably, the cracking raw material feed inlet is arranged at the top of the convection section for introducing the cracking raw material into the convection section; the gas outlet is arranged at the upper part of the convection section for leading out the product synthesis gas.

[0040] According to the present invention, preferably, the burner comprises a bottom burner and an optional side wall burner, and the bottom burner and the side wall burner are respectively arranged at the bottom and the side wall of the radiation section.

[0041] According to the present invention, preferably, the ratio of the number of bottom burners to side wall burners is 1:1.5-3, for example, 1:1.5, 1:2, 1:2.25, 1:2.5, 1:3, and any value in the score range composed of any two numerical values, preferably 1:2-2.5.

[0042] According to the present invention, preferably, the number of the bottom burners is ≥2, preferably 2-8.

[0043] According to the present invention, preferably, the material feed port is used to introduce the material into the cracking furnace. In the present invention, the material feed port serves as the inlet of the material, so that the material enters the cracking furnace for non-catalytic partial oxidation reaction and reforming reaction, and produces high-temperature synthesis gas that meets the heat required by the cracking reaction.

[0044] According to the present invention, preferably, in each of the burners, the volume flow ratio of the oxidant and the natural gas in the material is 0.5-0.8:1, for example, 0.5:1, 0.65:1, 0.7:1, 0.8:1, and any value in the range of any two values, preferably 0.65-0.7:1. By adjusting the volume ratio of the oxidant and the natural gas in the material, the present invention can, on the one hand, regulate the temperature of the cracking furnace (1150-1250°C) to meet the temperature resistance requirements of the cracking reaction and the furnace tube material; on the other hand, improve the quality of the product synthesis gas.

[0045] According to the present invention, preferably, the oxidant is an oxygen-containing gas, and the oxygen content in the oxygen-containing gas is 20-100 volume%, preferably 21-35 volume%. In the present invention, the oxidant includes but is not limited to air, pure oxygen, etc., as long as the oxygen content in the oxygen-containing gas meets the above definition.

[0046] According to the present invention, preferably, the cracking feedstock is selected from at least one of ethane, naphtha, hydrogenated tail oil and diesel.

[0047] According to the present invention, preferably, the temperature of the high temperature synthesis gas is 1150-1250° C., for example, 1150° C., 1180° C., 1200° C., 1250° C., and any value in a range consisting of any two values, preferably 1150-1200° C. The preferred conditions are adopted to meet the temperature resistance requirements of the cracking reaction and the cracking furnace tube material.

[0048] According to the present invention, preferably, the process of the non-catalytic partial oxidation reaction comprises: subjecting the oxidant in the material and the natural gas to a non-catalytic partial oxidation reaction to obtain a product containing water vapor.

[0049] According to the present invention, preferably, the process of the reforming reaction comprises: reforming the natural gas in the material and the water vapor in the product to obtain the high-temperature synthesis gas.

[0050] According to the present invention, preferably, the cracking reaction temperature is 650-900°C, for example, 650°C, 750°C, 800°C, 850°C, 880°C, 900°C, and any value in the range of any two values, preferably 750-880°C.

[0051] According to the present invention, preferably, the temperature of the product synthesis gas is 100-130°C, preferably 110-120°C; further preferably, the molar ratio of H2 to CO in the product synthesis gas is 1-3:1, preferably 2-2.5:1.

[0052] In some embodiments of the present invention, preferably, the water vapor content in the product synthesis gas is ≤ 15 volume %, preferably 10-15 volume %; the CO2 content is ≤ 2.5 volume %, preferably 1.5-2 volume %.

[0053] According to the present invention, preferably, the cracking furnace further comprises a denitration device; further preferably, the denitration device is arranged above the interior of the convection section to remove NO generated by the non-catalytic partial oxidation reaction. x , thereby ensuring low NO in the cracking furnace x emission.

[0054] According to the present invention, preferably, the cracking furnace also includes a quenching boiler connected to the cracking furnace tube; further preferably, the quenching boiler is connected to the top of the cracking furnace tube to reduce the temperature of the cracking gas product at the cracking furnace tube outlet, thereby ensuring the cracking reaction.

[0055] A schematic diagram of a cracking furnace structure provided by the present invention is as follows Figure 1 As shown by Figure 1 It can be seen that the cracking furnace includes: a convection section 1 with a lower opening and a radiation section 2 with an upper opening, and the convection section 1 and the radiation section 2 are connected through the lower opening and the upper opening; the radiation section 2 includes: a cracking furnace tube 4, a cracking furnace 3, at least one bottom burner 5 and a side wall burner 6, and the bottom burner 5 and the side wall burner 6 are respectively arranged at the bottom and the side wall of the radiation section 2, and a quenching boiler 11 connected to the top of the cracking furnace tube 4; each of the burners 5 is provided with a material feed port 7; the convection section 1 is provided with a cracking raw material feed port 10 and a gas outlet 9; a denitrification device 8 is provided above the interior of the convection section 1;

[0056] The cracking furnace 3 is used to carry out non-catalytic partial oxidation reaction and reforming reaction on the material to obtain high-temperature synthesis gas, wherein the material is a mixed gas containing an oxidant and natural gas;

[0057] Wherein, the cracking furnace tube 4 is used to carry out cracking reaction on the cracking raw material;

[0058] Wherein, the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction.

[0059] According to a particularly preferred embodiment of the present invention, the cracking furnace comprises: a convection section with a lower opening and a radiation section with an upper opening, and the convection section and the radiation section are connected through the lower opening and the upper opening; the radiation section comprises: a cracking furnace tube, a cracking furnace and at least one burner; each of the burners is provided with a material feed port; the convection section is provided with a cracking raw material feed port and a gas outlet;

[0060] The cracking furnace is used to carry out non-catalytic partial oxidation reaction and reforming reaction on the material to obtain high-temperature synthesis gas, wherein the material is a mixed gas containing an oxidant and natural gas;

[0061] Wherein, the cracking furnace tube is used to carry out cracking reaction on the cracking raw material;

[0062] Wherein, the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction;

[0063] Wherein, in each of the burners, the volume flow ratio of the oxidant and the natural gas in the material is 0.5-0.8:1.

[0064] The second aspect of the present invention provides a cracking method, characterized in that the method is carried out in the cracking furnace provided in the first aspect.

[0065] According to the present invention, preferably, the method comprises the following steps:

[0066] (1) feeding a material into a cracking furnace through a material feed port in the cracking furnace to carry out a non-catalytic partial oxidation reaction and a reforming reaction to obtain a high-temperature synthesis gas; wherein the material is a mixed gas containing an oxidant and natural gas;

[0067] (2) feeding the cracking raw material into the cracking furnace tube through the cracking raw material feed port in the cracking furnace to carry out cracking reaction;

[0068] Wherein, the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction.

[0069] In some embodiments of the present invention, preferably, the high temperature synthesis gas and the cracking furnace tube are subjected to a first heat exchange to obtain the heat exchanged synthesis gas. In the present invention, the first heat exchange fully utilizes the heat of the high temperature synthesis gas to heat the cracking furnace tube, thereby initiating a cracking reaction in the cracking furnace tube.

[0070] In some embodiments of the present invention, preferably, the heat-exchanged syngas and the cracking feedstock are subjected to a second heat exchange to obtain a product syngas converted from the heat-exchanged syngas and a heated cracking feedstock converted from the cracking feedstock. In the present invention, the second heat exchange further reduces the temperature of the heat-exchanged syngas while heating the cracking feedstock, thereby reducing the temperature of the product syngas.

[0071] In some embodiments of the present invention, preferably, in each of the burners, the volume flow ratio of the oxidant to the natural gas in the material is 0.5-0.8: 1, preferably 0.65-0.7: 1. By adopting the preferred conditions, the temperature of the cracking furnace is regulated to meet the temperature resistance requirements of the cracking reaction and the cracking furnace tube material, which is more conducive to improving the quality of the product synthesis gas.

[0072] In some embodiments of the present invention, preferably, the oxidant is an oxygen-containing gas, and the oxygen content in the oxygen-containing gas is 20-100 volume%, preferably 21-35 volume%. In the present invention, the oxidant includes but is not limited to air, pure oxygen, etc., as long as the oxygen content in the oxygen-containing gas meets the above definition.

[0073] In some embodiments of the present invention, preferably, the cracking feedstock is selected from at least one of ethane, naphtha, hydrogenated tail oil and diesel.

[0074] In some embodiments of the present invention, preferably, the temperature of the high temperature synthesis gas is 1150-1250°C, preferably 1150-1200°C.

[0075] In some embodiments of the present invention, preferably, the temperature of the product synthesis gas is 100-130°C, preferably 110-120°C; further preferably, the molar ratio of H2 to CO in the product synthesis gas is 1-3:1, preferably 2-2.5:1; the water vapor content in the product synthesis gas is ≤15% by volume, preferably 10-15% by volume; the CO2 content is ≤2.5% by volume, preferably 1.5-2% by volume.

[0076] In some embodiments of the present invention, preferably, the method further comprises: before step (1), preheating the material; further preferably, the temperature of the preheated material is 450-500°C, preferably 470-500°C.

[0077] In the present invention, the material is preheated to 450-500°C, and then enters the cracking furnace through the burner mixed gas inlet to undergo non-catalytic partial oxidation-reforming reaction, thereby generating high-temperature synthesis gas whose main components are H2 and CO. Specifically, preheating the material can minimize the amount of complete combustion of natural gas during the reaction process and reduce the amount of H2O generated; then the non-catalytic partial oxidation product and the natural gas in the material undergo reforming reaction, thereby reducing the furnace temperature and further reducing the water vapor content in the product synthesis gas, thereby improving the quality of the synthesis gas at the outlet of the cracking furnace.

[0078] The present invention will be described in detail below through examples.

[0079] In the examples and comparative examples, the air density is 1.29 kg / cm 3 , the density of natural gas is 0.7174 kg / cm 3 .

[0080] Example 1

[0081] Cracking furnace

[0082] The cracking furnace comprises: a convection section 1 with a lower opening and a radiation section 2 with an upper opening, and the convection section 1 and the radiation section 2 are connected through the lower opening and the upper opening; the radiation section 2 comprises: a cracking furnace tube 4, a cracking furnace 3, a bottom burner 5 and a side wall burner 6, and the bottom burner 5 and the side wall burner 6 are respectively arranged at the bottom and the side wall of the radiation section 2, and a quenching boiler 11 connected to the top of the cracking furnace tube 4; each of the burners 5 is provided with a material feed port 7; the convection section 1 is provided with a cracking raw material feed port 10 and a gas outlet 9; a denitration device 8 is arranged above the interior of the convection section 1;

[0083] The cracking furnace 3 is used to carry out non-catalytic partial oxidation reaction and reforming reaction on the material to obtain high-temperature synthesis gas, wherein the material is a mixed gas containing an oxidant and natural gas;

[0084] Wherein, the cracking furnace tube 4 is used to carry out cracking reaction on the cracking raw material;

[0085] The number ratio of the bottom burners 5 to the side wall burners 6 is 1:2.

[0086] Cracking method

[0087] (1) preheating the material (air flow rate is 8000 kg / h, natural gas flow rate is 6844 kg / h, and the volume ratio of air to natural gas is 0.65:1) to 470° C., and then entering the cracking furnace through the material feed port in the above cracking furnace to perform non-catalytic partial oxidation reaction and reforming reaction to obtain high-temperature synthesis gas, wherein the temperature of the high-temperature synthesis gas is 1200° C.;

[0088] The high-temperature synthesis gas is heat exchanged with the cracking furnace tube in the above cracking furnace, and the obtained heat-exchanged synthesis gas is heat exchanged with the cracking raw material (ethylene) to obtain the product synthesis gas S1 converted from the heat-exchanged synthesis gas and the heated cracking raw material converted from the cracking raw material;

[0089] (2) The heated cracking raw material (ethylene) is subjected to cracking reaction in the cracking furnace tubes of the above cracking furnace.

[0090] The temperature of the product synthesis gas S1 is 120° C.; the molar ratio of H2 to CO in the product synthesis gas S1 is 2:1, the water vapor content is 12% by volume, and the CO2 content is 1.8% by volume.

[0091] Example 2

[0092] The cracking furnace shown in Example 1 is different in that the ratio of the number of bottom burners to the number of side wall burners is replaced to 1:0.5.

[0093] Cracking method

[0094] (1) preheating the material (air flow rate is 8000 kg / h, natural gas flow rate is 6844 kg / h, and the volume ratio of air to natural gas is 0.65:1) to 450° C., and then entering the cracking furnace through the material feed port in the above cracking furnace to perform non-catalytic partial oxidation reaction and reforming reaction to obtain high-temperature synthesis gas, wherein the temperature of the high-temperature synthesis gas is 1250° C.;

[0095] The high-temperature synthesis gas is heat exchanged with the cracking furnace tube in the above cracking furnace, and the obtained heat-exchanged synthesis gas is heat exchanged with the cracking raw material (ethylene) to obtain the product synthesis gas S2 converted from the heat-exchanged synthesis gas and the heated cracking raw material converted from the cracking raw material;

[0096] (2) The cracking raw material (ethylene) after heat exchange is subjected to cracking reaction in the cracking furnace tubes in the above cracking furnace.

[0097] The temperature of the product synthesis gas S2 is 125° C.; the molar ratio of H2 to CO in the product synthesis gas S2 is 2.1:1, the water vapor content is 10% by volume, and the CO2 content is 2% by volume.

[0098] Example 3

[0099] According to the cracking furnace shown in Example 1.

[0100] The method shown in Example 1 is followed, except that the volume ratio of air to natural gas in the material is replaced with 0.5:1, and the other conditions remain the same, to obtain the product synthesis gas S3.

[0101] The temperature of the product synthesis gas S3 is 128° C.; the molar ratio of H2 to CO in the product synthesis gas S3 is 0.8:1, the water vapor content is 14% by volume, and the CO2 content is 1.8% by volume.

[0102] Comparative Example 1

[0103] The traditional natural gas and air combustion heating furnace

[0104] A mixture of natural gas and air is introduced into the cracking furnace through a burner at the bottom of the cracking furnace for combustion reaction, wherein the natural gas flow rate is 7161 kg / h and the air flow rate is 8450 kg / h; a methane combustion reaction occurs in the cracking furnace to provide the required heat for the cracking reaction in the cracking furnace, and the average temperature of the flue gas in the cracking furnace is 1100°C. The flue gas after heat exchange is discharged from the cracking furnace after heat exchange with the cracking raw material in the convection section of the cracking furnace, wherein the CO2 content in the flue gas at the outlet of the cracking furnace is 20% by volume.

[0105] Compared with Comparative Example 1, the cracking reaction is carried out by using the cracking furnace provided by the present invention. While reducing the temperature of the cracking furnace, it is possible to significantly reduce the temperature of the product synthesis gas, as well as the CO2 content and water content in the product synthesis gas, thereby improving the quality of the product synthesis gas and making it meet the process requirements of Fischer-Tropsch synthesis, methanol synthesis, etc.; in particular, by adjusting the volume ratio of the oxidant and the natural gas in the material, the quality of the product synthesis gas can be further improved.

[0106] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A cracking method, characterized in that: The cracking method is carried out in a cracking furnace, which comprises: a convection section with a lower opening and a radiation section with an upper opening, and the convection section and the radiation section are connected through the lower opening and the upper opening; the radiation section comprises: a cracking furnace tube, a cracking furnace and at least one burner; each of the burners is provided with a material feed port; the convection section is provided with a cracking raw material feed port and a gas outlet; The cracking furnace is used to carry out non-catalytic partial oxidation reaction and reforming reaction on the material to obtain high-temperature synthesis gas with a temperature of 1150-1250°C, wherein the material is a mixed gas containing an oxidant and natural gas; in each of the burners, the volume flow ratio of the oxidant to the natural gas in the material is 0.5-0.8:1; wherein the process of the non-catalytic partial oxidation reaction includes: carrying out non-catalytic partial oxidation reaction on the oxidant and natural gas in the material to obtain a product containing water vapor; the process of the reforming reaction includes: carrying out reforming reaction on the natural gas in the material and the water vapor in the product to obtain the high-temperature synthesis gas; The cracking furnace tube is used to carry out cracking reaction on the cracking raw material, and the critical temperature of the cracking reaction is 650-900°C; Wherein, the temperature of the high-temperature synthesis gas is ≥ the critical temperature of the cracking reaction; The cracking furnace tube is arranged in the cracking furnace, the high-temperature synthesis gas and the cracking furnace tube are subjected to a first heat exchange, and the obtained heat-exchanged synthesis gas enters the convection section; the convection section is used to perform a second heat exchange between the heat-exchanged synthesis gas and the cracking raw material, and obtain the product synthesis gas converted from the heat-exchanged synthesis gas and the heated cracking raw material converted from the cracking raw material; The temperature of the product synthesis gas is 100-130°C; the molar ratio of H2 to CO in the product synthesis gas is 1-3:1, the water vapor content is ≤15% by volume; and the CO2 content is ≤2.5% by volume.

2. The lysis method according to claim 1, wherein: The cracking raw material feed inlet is arranged at the top of the convection section; and the gas outlet is arranged at the upper part of the convection section.

3. The lysis method according to claim 1, wherein: The burner comprises a bottom burner and a side wall burner, and the bottom burner and the side wall burner are respectively arranged at the bottom and the side wall of the radiation section.

4. The lysis method according to claim 3, wherein: The quantity ratio of the bottom burners to the side wall burners is 1:1.5-3.

5. The lysis method according to claim 4, wherein: The quantity ratio of the bottom burners to the side wall burners is 1:2-2.

5.

6. The lysis method according to claim 3, wherein: The number of the bottom burners is ≥2.

7. The lysis method according to claim 6, wherein: The number of the bottom burners is 2-8.

8. The lysis method according to claim 1, wherein: In each of the burners, the volume flow ratio of the oxidant and the natural gas in the material is 0.65-0.7:

1.

9. The lysis method according to claim 8, wherein: The oxidant is an oxygen-containing gas, and the oxygen content in the oxygen-containing gas is 20-100 volume %.

10. The lysis method according to claim 9, wherein: The oxidant is an oxygen-containing gas, and the oxygen content in the oxygen-containing gas is 21-35% by volume.

11. The lysis method according to claim 10, wherein: The cracking raw material is selected from at least one of ethane, naphtha, hydrogenated tail oil and diesel.

12. The lysis method according to claim 1, wherein: The temperature of the high temperature synthesis gas is 1150-1200°C; The critical temperature of the cracking reaction is 750-880°C.

13. The lysis method according to any one of claims 1 to 12, wherein: The temperature of the product synthesis gas is 110-120°C; The molar ratio of H2 to CO in the product synthesis gas is 2-2.5:1; The water vapor content in the product synthesis gas is 10-15% by volume; the CO2 content is 1.5-2% by volume.

14. The lysis method according to any one of claims 1 to 12, wherein: The cracking furnace also includes a denitrification device; the denitrification device is arranged above the interior of the convection section and is used to remove NO in the high-temperature synthesis gas. x .

15. The lysis method according to claim 14, wherein: The cracking furnace also includes a quench boiler connected to the cracking furnace tube; The quenching boiler is connected to the top of the cracking furnace tube and is used to reduce the temperature of the cracking gas product at the outlet of the cracking furnace tube.

16. The lysis method according to claim 1, wherein: The cracking method further comprises: preheating the material and then performing the non-catalytic partial oxidation reaction; The temperature of the preheated material is 450-500°C.

17. The lysis method according to claim 16, wherein: The temperature of the preheated material is 470-500°C.

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