Catalytic cracking method for producing CO and reducing emission

Abstract

The invention relates to a catalytic cracking method for producing CO and reducing emission, which comprises the following steps of: (1) performing steam stripping on a carbon-deposited spent catalyst subjected to a catalytic cracking reaction, feeding the spent catalyst into a regenerator, contacting the spent catalyst with regeneration gas in the regenerator for regeneration, and performing gas-solid separation to obtain a regenerated catalyst and first flue gas; returning part of the first flue gas to the regenerator at a recycle ratio of 50-99%; recycling at least part of the regenerated catalyst for the catalytic cracking reaction; (2) carrying out cyclone separation on the residual first flue gas which is not returned to the regenerator to obtain regenerated catalyst fine powder and second flue gas; (3) the second flue gas is subjected to heat exchange, and third flue gas is obtained; (4) cooling the third flue gas to obtain fourth flue gas; and (5) separating the fourth flue gas in a CO separation unit to obtain a CO product. According to the catalytic cracking method for producing CO and reducing emission, carbon deposit on the spent catalyst is converted into flue gas with higher CO selectivity, and meanwhile, the CO separation energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic cracking of petroleum hydrocarbons, and in particular to a catalytic cracking method for producing CO and reducing emissions. Background Art

[0002] The catalytic cracking of petroleum raw materials is an important petroleum refining process. The catalytic cracking unit mainly includes a catalytic cracking reactor and a catalyst regenerator. In the catalyst regenerator, the regeneration gas is used to regenerate the carbonized catalyst, and regeneration flue gas is generated at the same time. During the regeneration process of the catalyst, the combustion of coke produces a large amount of CO2 gas, making the catalytic cracking unit the largest source of CO2 emissions in the refinery. CO2 in the catalytic cracking flue gas accounts for 15% to 50% of the total emissions of the refinery. The catalytic cracking unit emits 211.7kgCO2 for processing each ton of raw materials. There are about 190 catalytic cracking units in China, with a total processing capacity of about 210 million tons / year, and at least 40 million tons of CO2 emissions.

[0003] The incomplete regeneration process can produce CO. Due to the low concentration of CO in the flue gas, it is often burned and converted into CO2. The heat generated is used to generate steam. There are also some methods to further utilize the CO in the flue gas.

[0004] CN1400159A discloses a method for producing hydrogen using catalytic cracking regeneration flue gas, which can make reasonable use of CO in the regeneration flue gas and alleviate the problem of excess heat in the FCC unit. However, the CO content obtained by this method is low, at about 14% by volume, while the nitrogen content is about 70% by volume.

[0005] CN102698817A discloses a fluidized catalytic cracking catalyst pure oxygen regeneration process and hydrogen production method, which can significantly improve the quality and efficiency of energy utilization, reduce the energy consumption and pollutant emissions of the FCC regeneration system, and at the same time enable the generated CO to produce hydrogen through a water-gas shift reaction.

[0006] CN101457152A discloses a hydrocarbon oil conversion method, in which, during the regeneration process, the catalyst to be regenerated contacts water vapor and oxygen-containing gas in a gasifier to obtain synthesis gas and semi-regenerated catalyst. The method can increase the production of carbon monoxide and hydrogen, and carbon monoxide can also be converted into hydrogen in the subsequent processing process, thereby obtaining a higher hydrogen yield.

[0007] However, the existing technology produces hydrogen by incompletely regenerating flue gas. Although coke is used, carbon is still mainly emitted in the form of carbon dioxide; and the method of directly contacting the regenerated catalyst with a large amount of water vapor to produce synthesis gas will accelerate the deactivation of the catalyst.

[0008] At present, the flue gas of industrial equipment is generally drawn out from the regenerator, and then passes through the cyclone separator to remove the fine catalyst powder carried by the flue gas. The high-temperature flue gas goes to the flue gas turbine for energy recovery. The flue gas turbine drives the main fan to increase the pressure of the main wind. The flue gas with recovered energy enters the waste heat boiler to further recover energy and denitrify, and then enters the desulfurization tower for desulfurization. After desulfurization, the flue gas can be discharged directly. This process can reduce the temperature of the high-temperature flue gas to below 200°C and the pressure to about 20kPa. However, the pure oxygen regeneration process aimed at producing CO requires the absorption of CO2 in the flue gas to separate CO. This process often requires a higher pressure. The flue gas that has been recovered by the flue gas turbine needs to be pressurized, resulting in energy waste. Therefore, the existing process is not suitable for the new regeneration process.

[0009] During the regeneration process of spent catalyst with carbon deposits produced by catalytic cracking reaction, how to convert more carbon deposits into CO to improve CO selectivity while reducing the energy consumption of CO separation is a technical problem that needs to be solved urgently. Summary of the invention

[0010] The present invention provides a catalytic cracking method for producing CO and reducing emissions, the purpose of which is to convert the carbon deposits on the spent catalyst into flue gas with higher CO selectivity and reduce the energy consumption of CO separation.

[0011] The present invention relates to a catalytic cracking method for producing CO and reducing emissions, comprising the following steps:

[0012] (1) The spent catalyst with carbon deposits from the catalytic cracking reaction is sent to a regenerator after stripping, the spent catalyst is contacted with a regeneration gas in the regenerator for regeneration, and a regenerated catalyst and a first flue gas are obtained through gas-solid separation; a portion of the first flue gas is returned to the regenerator at a circulation ratio of 50 to 99%; and at least a portion of the regenerated catalyst is circulated for the catalytic cracking reaction;

[0013] Wherein, the oxygen content of the first flue gas is less than or equal to 1%;

[0014] (2) sending the remaining first flue gas that has not returned to the regenerator into a cyclone separator for cyclone separation to obtain regenerated catalyst fine powder and second flue gas;

[0015] (3) allowing the second flue gas to enter a waste heat boiler for heat exchange to obtain a third flue gas;

[0016] (4) allowing the third flue gas to enter a flue gas cooling device for cooling to obtain a fourth flue gas;

[0017] (5) Separating the fourth flue gas in a CO separation unit to obtain a CO product.

[0018] Optionally, the catalytic cracking method further comprises: introducing CO2 and water vapor into the middle of the regenerator;

[0019] The volume proportion of the introduced CO2 in the first flue gas is 5-50%, and the volume proportion of the introduced water vapor in the first flue gas is 0.1-10%;

[0020] Preferably, the volume proportion of the introduced CO2 in the first flue gas is 5-15%, and the volume proportion of the introduced water vapor in the first flue gas is 0.1-2%.

[0021] Optionally, in step (1), the catalytic cracking reaction comprises:

[0022] The hydrocarbon oil feedstock is brought into contact with the catalytic cracking catalyst in a catalytic cracking reactor to carry out a catalytic cracking reaction, and the reaction oil gas and the spent catalyst with carbon deposition are separated.

[0023] Optionally, the catalytic cracking catalyst is loaded with active metals;

[0024] The active metal is selected from one or more combinations of alkali metals, alkaline earth metals and transition metals, preferably one or more combinations of K, Ca, Na, Co, Mo, Ni and Fe;

[0025] The content of the active metal in the catalytic cracking catalyst is 0.1-5%, preferably 0.5-1%.

[0026] Optionally, the hydrocarbon oil feedstock includes petroleum hydrocarbons and / or other mineral oils, the petroleum hydrocarbons are selected from one or more of gasoline, diesel, vacuum wax oil, atmospheric wax oil, coker wax oil, deasphalted oil, vacuum residue oil, atmospheric residue oil, extracted oil and inferior recycled oil, and the other mineral oils are selected from one or more of coal liquefaction oil, oil sand oil and shale oil.

[0027] Optionally, the conditions of the catalytic cracking reaction include:

[0028] The reaction temperature is 450-700° C., the reaction time is 1-10 seconds, and the agent-oil ratio is (1-100):1.

[0029] Optionally, the catalytic cracking reactor is a riser reactor or a fluidized bed reactor, or a combination of the two.

[0030] Optionally, in step (1), the regeneration gas is O2; and / or,

[0031] The conditions for regeneration in the regenerator include:

[0032] The regeneration temperature is 600-800°C, and the residence time of the catalyst to be regenerated in the regenerator is 1-20 minutes; and / or,

[0033] The regenerator is selected from a combination of one or more of a bubbling bed, a turbulent bed, a fast bed and a riser.

[0034] Optionally, in step (1), part of the first flue gas returned to the regenerator is pressurized by a pressurizing device.

[0035] Optionally, the CO separation unit in step (5) includes a CO2 absorption tower and a desorption tower;

[0036] The operating conditions of the CO2 absorption tower include: the absorbent is selected from a combination of one or more of organic amines, ammonia water, carbonates, bicarbonates and carbamates, the CO2 absorption gauge pressure is 0.2-4MPa, and the temperature is 0-80°C.

[0037] Beneficial effects:

[0038] (1) In the present invention, the first flue gas generated by the regenerator is returned to the regenerator for recycling at a certain circulation ratio, and the oxygen content of the first flue gas is controlled within a certain range, thereby controlling the combustion reaction process of the coke on the regenerated catalyst, causing incomplete combustion to generate CO, reducing combustion heat, and storing part of the energy as chemical energy in CO. At the same time, CO2 emissions are greatly reduced without affecting the catalyst regeneration effect or the catalytic cracking reaction activity.

[0039] (2) Part of the CO2-rich first flue gas is directly returned to the regenerator without CO2 separation. On the one hand, CO2 can be used to generate CO with coke, and on the other hand, the separation energy consumption can be greatly reduced. The new flue gas treatment process can reduce energy consumption, and the excess heat of the regeneration system can be used for CO separation.

[0040] (3) The separation of CO and CO2 by CO2 chemical absorption can also remove sulfides from flue gas at the same time. The generated CO can be used as raw materials for subsequent chemical industry, metallurgy, etc., which can save raw materials such as coal and methane for producing CO, save resources and energy consumption, and further reduce emissions. Therefore, under the background of carbon neutrality and carbon peak goals, the production of CO by catalytic cracking regeneration process can achieve waste-to-treasure and energy conservation and emission reduction, which has huge economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 A schematic diagram of a specific embodiment of a process of a catalytic cracking method for producing CO and reducing emissions or a catalytic cracking system for producing CO and reducing emissions according to the present invention;

[0043] Figure 2 This is a schematic diagram of the catalytic cracking flue gas treatment process in Comparative Example 1;

[0044] Description of reference numerals:

[0045] 1 O2 inlet 1 2 Regenerator 3 First flue gas outflow pipeline

[0046] 4 Circulating flue gas pipeline 5 Cyclone separator 6 Second flue gas pipeline

[0047] 7 Waste heat boiler 8 Third flue gas pipeline 9 Steam outlet

[0048] 10 Flue gas cooling equipment 11 Fourth flue gas pipeline 12 CO separation unit

[0049] 13 CO product outlet 14 CO2 outlet 15 Air

[0050] 16 Second regenerator 17 Comparison - first flue gas 18 Second cyclone separator

[0051] 19 Comparison - Second Flue Gas 20 Flue Gas Turbine 21 Comparison - Third Flue Gas

[0052] 22 Second waste heat boiler 23 Steam 24 Comparison - Fourth flue gas

[0053] 25 Second flue gas cooling equipment 26 Comparison - fifth flue gas 27 Second CO2 absorption unit

[0054] 28 Carbon monoxide 29 Carbon dioxide DETAILED DESCRIPTION

[0055] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0056] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0057] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0058] The present invention relates to a catalytic cracking method for producing CO and reducing emissions, comprising the following steps:

[0059] (1) The spent catalyst with carbon deposits from the catalytic cracking reaction is sent to a regenerator after stripping, the spent catalyst is contacted with a regeneration gas in the regenerator for regeneration, and a regenerated catalyst and a first flue gas are obtained through gas-solid separation; a portion of the first flue gas is returned to the regenerator at a circulation ratio of 50 to 99%; and at least a portion of the regenerated catalyst is circulated for the catalytic cracking reaction;

[0060] Wherein, the oxygen content of the first flue gas is less than or equal to 1%;

[0061] (2) sending the remaining first flue gas that has not returned to the regenerator into a cyclone separator for cyclone separation to obtain regenerated catalyst fine powder and second flue gas;

[0062] (3) allowing the second flue gas to enter a waste heat boiler for heat exchange to obtain a third flue gas;

[0063] (4) allowing the third flue gas to enter a flue gas cooling device for cooling to obtain a fourth flue gas;

[0064] (5) Separating the fourth flue gas in a CO separation unit to obtain a CO product.

[0065] It should be noted that the carbon deposited catalyst to be regenerated is roasted at high temperature with the regeneration gas in the regenerator, so that the carbon deposit or coke is converted into flue gas, and the catalyst to be regenerated is converted into a regenerated catalyst. The mixed system of the regenerated catalyst and the flue gas is separated by gas-solid separation to obtain the regenerated catalyst and the first flue gas, and the obtained first flue gas still contains a small amount of fine powdered regenerated catalyst. The first flue gas can be drawn out from the top of the regenerator, a part of which is circulated to the regenerator for recycling, and the other part enters the cyclone separator, the waste heat boiler, the flue gas cooling equipment and the CO separation unit in sequence to obtain the CO product.

[0066] It should be noted that in step (1), the first flue gas is returned to the regenerator at a circulation ratio of 50-99%, and the circulation ratio refers to that, based on the total volume of the first flue gas generated in the regenerator, the volume of the first flue gas circulated back to the regenerator accounts for 50-99% of the total volume of the first flue gas generated in the regenerator. In step (1), the circulation ratio of the first flue gas returned to the regenerator is preferably 60-95%, more preferably 70-90%, and the first flue gas circulation ratio can be preferably 75%, 81%, 85%, 90%, 91% and 95%, etc., which can further improve CO selectivity and reduce separation energy consumption.

[0067] In step (1), the oxygen content of the first flue gas is less than or equal to 1%, and the oxygen content of the first flue gas refers to the ratio of the volume of oxygen contained in the first flue gas to the total volume of the first flue gas.

[0068] It should be noted that in the catalytic cracking method for producing CO and reducing emissions of the present invention, the carbon-deposited catalyst to be regenerated is contacted with the regeneration gas in the regenerator for regeneration, and the first flue gas generated in the regenerator is returned to the regenerator for recycling at a circulation ratio of 50 to 99%; at the same time, by controlling the oxygen content of the regeneration gas passed into the regenerator, or controlling the amount of pure oxygen passed into the regenerator as the regeneration gas, the oxygen content of the first flue gas is less than or equal to (not exceeding) 1%, and the composition of the first flue gas may include CO, CO2 and optional O2; then, the first flue gas that is not circulated back to the regenerator enters the cyclone separator, the waste heat boiler, the flue gas cooling equipment and the CO separation unit in sequence to obtain a CO product and CO2 at the same time, thereby achieving a significant reduction in CO2 emissions and producing CO at a relatively low energy consumption. Therefore, the catalytic cracking method for producing CO and reducing emissions of the present invention has high CO selectivity and low separation energy consumption.

[0069] According to a specific embodiment of the catalytic cracking method of the present invention, the catalytic cracking method further comprises: introducing CO2 and water vapor into the middle of the regenerator;

[0070] The volume proportion of the introduced CO2 in the first flue gas is 5-50%, and the volume proportion of the introduced water vapor in the first flue gas is 0.1-10%;

[0071] Preferably, the volume proportion of the introduced CO2 in the first flue gas is 5-15%, and the volume proportion of the introduced water vapor in the first flue gas is 0.1-2%.

[0072] It should be noted that the inventors of the present application have found through years of research and development experiments that, in the catalytic cracking method of the present application, the introduction of CO2 and water vapor into the regenerator is conducive to the improvement of CO selectivity and the reduction of energy consumption. In particular, when CO2 and water vapor are introduced into the middle of the regenerator, and the introduction amount of CO2 and water vapor (i.e., the volume proportion in the first flue gas) is controlled within the above-mentioned preferred range, the CO selectivity of the catalytic cracking method for producing CO and reducing emissions of the present application is further greatly improved, and the energy consumption is reduced.

[0073] According to a specific embodiment of the catalytic cracking method of the present invention, in step (1), the catalytic cracking reaction comprises:

[0074] The hydrocarbon oil feedstock is brought into contact with the catalytic cracking catalyst in a catalytic cracking reactor to carry out a catalytic cracking reaction, and the reaction oil gas and the spent catalyst with carbon deposition are separated.

[0075] It should be noted that the reaction oil and gas can be separated by a subsequent separation system to obtain dry gas, liquefied gas, stabilized gasoline and catalytic diesel fractions. The specific separation method is a conventional technical method in the art, and the present invention is not limited to this and is not described in detail herein. At least a portion of the catalytic cracking catalyst used for the catalytic cracking reaction is a regenerated catalyst, preferably all of which are regenerated catalysts. Preferably, the present invention also includes degassing the regenerated catalyst and then returning it to the catalytic cracking reactor for recycling.

[0076] According to a specific embodiment of the catalytic cracking method of the present invention, the catalytic cracking catalyst is loaded with active metals;

[0077] The active metal is selected from one or more combinations of alkali metals, alkaline earth metals and transition metals, preferably one or more combinations of K, Ca, Na, Co, Mo, Ni and Fe;

[0078] The content of the active metal in the catalytic cracking catalyst is 0.1-5%, preferably 0.5-1%.

[0079] It should be noted that the content of active metal in the catalytic cracking catalyst represents the mass content. After a long period of research and development, the inventors of the present application have found that in the catalytic cracking method for producing CO and reducing emissions of the present invention, when the catalytic cracking catalyst loaded with active metals as above undergoes a catalytic cracking reaction and the resulting carbon-deposited catalyst is regenerated in a regenerator, the carbon deposits are in contact with oxygen for an oxidation reaction to regenerate the catalyst. In this process, the presence of the above-mentioned active metal is beneficial to converting more carbon deposits into CO, thereby increasing the CO content in the first flue gas and further improving the CO selectivity.

[0080] According to another specific embodiment of the catalytic cracking method of the present invention, the hydrocarbon oil feedstock includes petroleum hydrocarbons and / or other mineral oils, the petroleum hydrocarbons are selected from one or more of gasoline, diesel, vacuum wax oil, atmospheric wax oil, coker wax oil, deasphalted oil, vacuum residue oil, atmospheric residue oil, extracted oil and inferior recycled oil, and the other mineral oils are selected from one or more of coal liquefaction oil, oil sand oil and shale oil.

[0081] It should be noted that the catalytic cracking method for producing CO and reducing emissions of the present invention has a wide range of applicability, and the spent catalyst with carbon deposits produced by catalytic cracking of the above hydrocarbon oil feedstock can be well regenerated and separated to obtain CO products.

[0082] According to a specific embodiment of the catalytic cracking method of the present invention, the conditions of the catalytic cracking reaction include:

[0083] The reaction temperature is 450-700° C., the reaction time is 1-10 seconds, and the agent-oil ratio is (1-100):1.

[0084] It should be noted that the reaction temperature is preferably 500-650°C, more preferably 550-630°C; the reaction time is preferably 2-5 seconds, and the catalyst-oil ratio (the weight ratio of the catalyst to the hydrocarbon oil feedstock) is preferably 5-30. In the present invention, water vapor can also be injected into the catalytic cracking reactor, and the water vapor is preferably injected in the form of atomized steam, and the weight ratio of the injected water vapor to the hydrocarbon oil feedstock can be 0.01-1:1, preferably 0.05-0.5:1. By controlling the conditions of the catalytic cracking reaction as above, the carbonized catalyst to be produced can obtain a CO product with higher CO selectivity through the above-mentioned regeneration and separation processes.

[0085] According to a specific embodiment of the catalytic cracking method of the present invention, the catalytic cracking reactor is a riser reactor or a fluidized bed reactor, or a combination of the two.

[0086] It should be noted that the catalytic cracking reactor can be a conventional catalytic cracking riser reactor, a fluidized bed reactor or a combination thereof known to those skilled in the art, for example, a catalytic cracking riser reactor connected in series with a fluidized bed reactor. The riser reactor can be selected from an equal diameter riser reactor and / or an equal linear velocity riser reactor, preferably an equal diameter riser. The fluidized bed reactor can be located downstream of the riser reactor and connected to the outlet of the riser reactor. The riser reactor includes a pre-lifting section and at least one reaction zone from bottom to top. In order to allow the crude oil to react fully and according to different quality requirements of the target product, the reaction zones can be 2 to 8, preferably 1 to 3.

[0087] According to a specific embodiment of the catalytic cracking method of the present invention, in step (1), the regeneration gas is O2; and / or,

[0088] The conditions for regeneration in the regenerator include:

[0089] The regeneration temperature is 600-800°C, and the residence time of the catalyst to be regenerated in the regenerator is 1-20 minutes; and / or,

[0090] The regenerator is selected from a combination of one or more of a bubbling bed, a turbulent bed, a fast bed and a riser.

[0091] It should be noted that the regeneration temperature can be preferably 700°C, 740°C, 750°C, etc., to further improve the CO selectivity. The regeneration gas is O2, and O2 can come from an air separation unit. The O2 from the air separation unit generally has a pressure of more than 0.3MPa and can directly enter the regenerator without the need for a main fan or other booster for pressurization. By using oxygen as the regeneration gas and not introducing nitrogen, a simpler method can be used to separate a higher purity CO product, reducing separation energy consumption. Part of the flue gas is recycled back to the regenerator to control the incomplete regeneration reaction process, while converting part of the CO2 into CO, further increasing the CO yield.

[0092] In the catalytic cracking method for producing CO and reducing emissions of the present invention, the first flue gas is returned to the regenerator for recycling at a certain circulation ratio, and the oxygen content of the first flue gas is controlled within a certain range, and pure oxygen regeneration is adopted. By controlling the regeneration reaction process, incomplete regeneration is achieved to produce CO, which can avoid the problem of difficulty in separating CO and nitrogen, further improve CO selectivity, and reduce separation energy consumption.

[0093] Internal components, such as orifice plates, may be provided in the regenerator. An internal heat exchanger or an external heat exchanger may be provided in the regenerator, and the type, connection and operation of the heat exchanger are well known to those skilled in the art.

[0094] According to a specific embodiment of the catalytic cracking method of the present invention, in step (1), part of the first flue gas returned to the regenerator is pressurized by a pressurizing device.

[0095] It should be noted that the inventors of the present application discovered during the long-term research and development experiments that the first flue gas circulating back to the regenerator enters the regenerator after being pressurized, and at the same time the circulation ratio is controlled as above, and the amount of oxygen introduced into the regenerator as the regeneration gas is controlled to control the oxygen content of the first flue gas, so that the carbon deposits on the catalyst to be regenerated are converted into more CO by reacting with oxygen in the regenerator, the CO content in the first flue gas is higher, and finally a CO product is obtained with a higher CO selectivity, and the separation energy consumption is low.

[0096] According to a specific embodiment of the catalytic cracking method of the present invention, the CO separation unit in step (5) includes a CO2 absorption tower and a desorption tower;

[0097] The operating conditions of the CO2 absorption tower include: the absorbent is selected from a combination of one or more of organic amines, ammonia water, carbonates, bicarbonates and carbamates, the CO2 absorption gauge pressure is 0.2-4MPa, and the temperature is 0-80°C.

[0098] It should be noted that in step (3), the second flue gas contacts water in the waste heat boiler for heat exchange, and the heat in the second flue gas is absorbed by water to obtain water vapor and the third flue gas after a certain degree of cooling. In step (5), the fourth flue gas containing CO and CO2 enters the CO2 absorption tower, CO2 is absorbed by the absorbent to obtain CO, and the rich absorption liquid enters the desorption tower, and CO2 is released through desorption, and the absorbent is regenerated at the same time. The CO2 absorption tower and the desorption tower are conventional technologies in the field, and the present invention is not limited. The sulfur-containing compounds in the flue gas are removed simultaneously during the CO2 absorption process. The cyclone separator, the waste heat boiler, the denitrification section in the waste heat boiler, and the flue gas cooling equipment are all conventional technologies in the field, and the present invention is not limited. Using the method of the present invention, the flue gas mainly contains CO2 and CO. After chemical absorption, CO and CO2 with higher purity can be obtained, which is beneficial to the subsequent utilization of CO2 and CO.

[0099] The catalytic cracking method for producing CO and reducing emissions of the present invention can be implemented based on the catalytic cracking system for producing CO and reducing emissions of the present invention. The catalytic cracking system for producing CO and reducing emissions of the present invention includes a catalytic cracking reactor, an oil agent separation device, a stripping device, a regenerator 2, a cyclone separator 5, a waste heat boiler 7, a flue gas cooling device 10 and a CO separation unit 12;

[0100] The catalytic cracking reactor is provided with a hydrocarbon oil feedstock inlet, a catalyst inlet and an oil agent outlet, the oil agent outlet is communicated with the inlet of the oil agent separation device, the oil agent separation device is also provided with an oil gas outlet and a catalyst outlet to be regenerated, the catalyst outlet to be regenerated is communicated with the catalyst inlet of the stripping device, and the catalyst outlet of the stripping device is communicated with the catalyst inlet to be regenerated of the regenerator 2;

[0101] The regenerator 2 is also provided with an O2 inlet 1 and a gas-solid separation device. The catalyst to be regenerated and O2 entering the regenerator 2 are regenerated to obtain a mixed system of flue gas and regenerated catalyst; the mixed system of flue gas and regenerated catalyst is subjected to gas-solid separation by the gas-solid separation device to obtain a first flue gas and a regenerated catalyst; the first flue gas outlet of the gas-solid separation device is connected to a first flue gas outflow pipeline 3, one outlet of the first flue gas outflow pipeline 3 is connected to a first flue gas inlet of the cyclone separator 5, and the other outlet of the first flue gas outflow pipeline 3 is connected to a circulating flue gas inlet of the regenerator 2 via a circulating flue gas pipeline 4; the regenerated catalyst outlet of the regenerator 2 is connected to the catalyst inlet of the catalytic cracking reactor.

[0102] The first flue gas entering the cyclone separator 5 is cyclonically separated into regenerated catalyst fine powder and second flue gas. The cyclone separator 5 is provided with a second flue gas outlet; the second flue gas outlet of the cyclone separator 5 is connected to the second flue gas inlet of the waste heat boiler 7 through a second flue gas pipeline 6.

[0103] The waste heat boiler 7 is also provided with a steam outlet 9 and a third flue gas outlet, and the third flue gas outlet of the waste heat boiler 7 is connected to the third flue gas inlet of the flue gas cooling device 10 through a third flue gas pipeline 8;

[0104] The fourth flue gas outlet of the flue gas cooling device 10 is connected to the fourth flue gas inlet of the CO separation unit 12 through a fourth flue gas pipeline 11;

[0105] The CO separation unit 12 is also provided with a CO product outlet 13 and a CO2 outlet 14 .

[0106] In the catalytic cracking system for producing CO and reducing emissions of the present invention, the regenerator 2 may be provided with internal components; the circulating flue gas pipeline 4 may be connected to a circulating flue gas pressurizing device.

[0107] The catalytic cracking method or system of the present invention eliminates the flue gas turbine, solves the problem of scaling of the flue gas turbine due to the entrainment of catalyst fine powder in the flue gas, and maintains the flue gas pressure, which is beneficial to the subsequent CO2 absorption and reduces energy consumption. Compared with the separation and circulation of CO2 in the flue gas, the direct circulation of the flue gas greatly reduces the energy consumption of separating CO and CO2, and improves the CO selectivity by combining other steps.

[0108] The method or system provided by the present invention not only reduces the carbon dioxide emission of the catalytic device and produces CO, realizes the transformation of waste into treasure and the full utilization of resources, and improves the economic benefit of the catalytic cracking device; at the same time, CO is used as a raw material for subsequent chemical processes, saving fossil resources such as coal, oil and methane used to produce CO, reducing energy consumption and investment, reducing pollution, and improving the economic and social benefits of the petrochemical industry.

[0109] The present invention is further described in detail by way of examples below, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the experimental instruments and raw materials involved are all commercially available products.

[0110] The raw material oil used in the following examples and comparative examples is Anqing wax oil, and its properties are shown in Table 1.

[0111] Table 1

[0112]

[0113] The catalyst used in the examples and comparative examples is a catalytic cracking catalyst, and its trade name is CDOS (Sinopec Catalyst Co., Ltd. Changling Branch).

[0114] The calculation method of CO selectivity in the following examples and comparative examples is as follows:

[0115]

[0116] In the CO selectivity calculation formula, the amount of CO substance generated represents the amount of CO substance in the second flue gas; the amount of carbon substance in the coke represents the amount of coke substance on the deposited catalyst to be regenerated entering the regenerator.

[0117] like Figure 1 As shown, pure oxygen enters the regenerator 2 through the O2 inlet 1, contacts with the coke on the catalyst to react, and the flue gas is drawn out from the regenerator 2, a part of which is returned to the regenerator 2 through the circulating flue gas pipeline 4 as circulating flue gas, and a part of the flue gas enters the cyclone separator 5 through the first flue gas outflow pipeline 3 to remove catalyst fine powder, and the flue gas with fine powder removed enters the waste heat boiler 7 through the second flue gas pipeline 6 for cooling, and steam is generated and flows out from the steam outlet 9, and the flue gas after energy recovery enters the flue gas cooling equipment 10 through the third flue gas pipeline 8, and the flue gas after further cooling enters the CO separation unit 12 through the fourth flue gas pipeline 11, and the carbon monoxide is separated and flows out through the CO product outlet 13 and the carbon dioxide flows out through the CO2 outlet 14.

[0118] Examples 1-4

[0119] The crude oil contacts the catalyst in the riser catalytic cracking reactor for catalytic cracking reaction. The oil-agent mixture is separated by the oil-agent to obtain the reaction oil gas and the spent catalyst with carbon deposition. The spent catalyst enters the regenerator after stripping, and then Figure 1 The process was tested, and the relevant operating conditions and products are listed in Table 2. Among them, the flue gas temperature at the outlet of the waste heat boiler is 120℃, the flue gas temperature at the outlet of the flue gas cooling equipment is 40℃, the absorbent in the CO2 absorption tower is methyldiethanolamine, the absorption gauge pressure is 0.15MPa, the temperature is 40℃, the desorption tower gauge pressure is 30kPa, and the temperature is 140℃. The regenerator is a bubbling bed.

[0120] Example 5

[0121] The method of Example 1 was adopted, except that the catalyst was a CDOS catalyst loaded with 1% Ni.

[0122] Example 6

[0123] The method of Example 1 is adopted, except that CO2 and water vapor are added into the middle of the regenerator, wherein the volume of CO2 accounts for 10% of the total first flue gas, and the volume of water vapor accounts for 1% of the total first flue gas.

[0124] Comparative Example 1

[0125] Similar to Example 1-4, the crude oil is contacted with the catalyst in the riser catalytic cracking reactor for catalytic cracking reaction, and the oil-agent mixture is separated by the oil-agent to obtain reaction oil gas and carbon-deposited spent catalyst, and the spent catalyst is stripped and enters the second regenerator 16. Then, according to Figure 2The process of the experiment was carried out, air 15 entered the second regenerator 16, contacted with the coke on the catalyst to react, the first flue gas 17 was drawn out from the second regenerator 16, entered the second cyclone separator 18 to remove the catalyst fine powder, the second flue gas 19 for removing the fine powder entered the flue gas turbine 20 for energy recovery, the third flue gas 21 for energy recovery entered the second waste heat boiler 22 for cooling, and steam 23 was generated, the fourth flue gas 24 after cooling entered the second flue gas cooling device 25, and the fifth flue gas 26 after further cooling entered the second CO2 absorption unit 27 to separate carbon monoxide 28 and carbon dioxide 29. The relevant operating conditions and products are listed in Table 3. The conditions of the CO2 absorption tower and desorption tower of the second cyclone separator 18, the second waste heat boiler 22, the second flue gas cooling device 25, and the second CO2 absorption unit 27 are the same as those of Examples 1-4.

[0126] Comparative Example 2

[0127] according to Figure 1 The same process was tested, except that the flue gas was not recycled back to the regenerator. The relevant operating conditions and products are listed in Table 3.

[0128] Comparative Example 3

[0129] according to Figure 1 The process of the present invention is tested, except that the flue gas is not directly circulated back to the regenerator, and the separated carbon dioxide is partially returned to the regenerator after flowing out of the carbon dioxide through the CO2 outlet 14. The relevant operating conditions and products are listed in Table 3.

[0130] It should be noted that the regeneration gas in Comparative Example 3 is initially pure oxygen, and part of the carbon dioxide flowing out through the CO2 outlet 14 is returned to the regenerator, so the regeneration gas has the composition shown in Table 3.

[0131] Table 2

[0132]

[0133] Note: In the table, the flue gas circulation ratio refers to the circulation ratio of the first flue gas, and the flue gas in the flue gas composition refers to the second flue gas.

[0134] Table 3

[0135] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Reaction conditions Reaction temperature / ℃ 620 620 620 Agent-oil ratio 10 10 10 Reaction time / s 3 3 3 Regeneration conditions Regeneration temperature / ℃ 700 700 700 Catalyst residence time / min 8 8 8 Regeneration gas composition / % <![CDATA[O2]]> 21 100 19.47 <![CDATA[CO2]]> 0 0 80.53 <![CDATA[N2]]> 79 0 0 Flue gas composition / volume % CO 10.00 22.00 18.96 <![CDATA[CO2]]> 12.00 78.00 81.04 CO selectivity / % 45.45 22.00 70.31 Separation energy consumption / MW 7.20 12.71 61.40

[0136] Note: The separation energy consumption is calculated based on the catalytic cracking unit processing capacity of 100t / h, coke yield of 8%, and CO2 separation and absorption energy consumption of 2GJ / t.

[0137] Note: The oxygen content in the flue gas is low and can be ignored.

[0138] It can be seen from the results of the examples that the method of the present invention has the advantages of greatly reducing carbon dioxide emissions and producing carbon monoxide, significantly improving CO selectivity, and low energy consumption.

[0139] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships in the working state of the present application. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present application.

[0140] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0141] The present application has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, various replacements and improvements may be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A catalytic cracking method for producing CO and reducing emissions, characterized in that: The steps include: (1) The spent catalyst with carbon deposits from the catalytic cracking reaction is sent to a regenerator after stripping, the spent catalyst is contacted with a regeneration gas in the regenerator for regeneration, and a regenerated catalyst and a first flue gas are obtained through gas-solid separation; a portion of the first flue gas is returned to the regenerator at a circulation ratio of 50 to 99%; and at least a portion of the regenerated catalyst is circulated for the catalytic cracking reaction; Wherein, the oxygen content of the first flue gas is less than or equal to 1%; (2) sending the remaining first flue gas that has not returned to the regenerator into a cyclone separator for cyclone separation to obtain regenerated catalyst fine powder and second flue gas; (3) allowing the second flue gas to enter a waste heat boiler for heat exchange to obtain a third flue gas; (4) allowing the third flue gas to enter a flue gas cooling device for cooling to obtain a fourth flue gas; (5) Separating the fourth flue gas in a CO separation unit to obtain a CO product.

2. The catalytic cracking method according to claim 1, characterized in that: The catalytic cracking method further comprises: introducing CO2 and water vapor into the middle of the regenerator; The volume proportion of the introduced CO2 in the first flue gas is 5-50%, and the volume proportion of the introduced water vapor in the first flue gas is 0.1-10%; Preferably, the volume proportion of the introduced CO2 in the first flue gas is 5-15%, and the volume proportion of the introduced water vapor in the first flue gas is 0.1-2%.

3. The catalytic cracking method according to claim 1, characterized in that: In step (1), the catalytic cracking reaction comprises: The hydrocarbon oil feedstock is brought into contact with the catalytic cracking catalyst in a catalytic cracking reactor to carry out a catalytic cracking reaction, and the reaction oil gas and the spent catalyst with carbon deposition are separated.

4. The catalytic cracking method according to claim 3, characterized in that: The catalytic cracking catalyst is loaded with active metals; The active metal is selected from one or more combinations of alkali metals, alkaline earth metals and transition metals, preferably one or more combinations of K, Ca, Na, Co, Mo, Ni and Fe; The content of the active metal in the catalytic cracking catalyst is 0.1-5%, preferably 0.5-1%.

5. The catalytic cracking method according to claim 3, characterized in that: The hydrocarbon oil raw material includes petroleum hydrocarbons and / or other mineral oils, the petroleum hydrocarbons are selected from one or more of gasoline, diesel, vacuum wax oil, atmospheric wax oil, coker wax oil, deasphalted oil, vacuum residue oil, atmospheric residue oil, extracted oil and inferior recycled oil, and the other mineral oils are selected from one or more of coal liquefaction oil, oil sand oil and shale oil.

6. The catalytic cracking method according to claim 3, characterized in that: The conditions of the catalytic cracking reaction include: The reaction temperature is 450-700° C., the reaction time is 1-10 seconds, and the agent-oil ratio is (1-100):

1.

7. The catalytic cracking method according to claim 3, characterized in that: The catalytic cracking reactor is a riser reactor or a fluidized bed reactor, or a combination of the two.

8. The catalytic cracking method according to claim 1, characterized in that: In step (1), the regeneration gas is O2; and / or, The conditions for regeneration in the regenerator include: The regeneration temperature is 600-800°C, and the residence time of the catalyst to be regenerated in the regenerator is 1-20 minutes; and / or, The regenerator is selected from a combination of one or more of a bubbling bed, a turbulent bed, a fast bed and a riser.

9. The catalytic cracking method according to claim 1, characterized in that: In step (1), part of the first flue gas returned to the regenerator is pressurized by a pressurizing device.

10. The catalytic cracking method according to claim 1, characterized in that: The CO separation unit in step (5) includes a CO2 absorption tower and a desorption tower; The operating conditions of the CO2 absorption tower include: the absorbent is selected from a combination of one or more of organic amines, ammonia water, carbonates, bicarbonates and carbamates, the CO2 absorption gauge pressure is 0.2-4MPa, and the temperature is 0-80°C.

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