Method for reducing the emission of vocs and nox in the flue gas of a two-stage regenerative catalytic cracker

Abstract

The present application relates to the field of catalytic cracking, and discloses a method for reducing VOCs and NOx emissions in the regeneration flue gas of a two-stage regeneration catalytic cracking device, which comprises: introducing the spent catalyst and an oxygen-containing gas into the two-stage regeneration catalytic cracking device, and introducing a CO combustion improver into the dense phase bed of the first regenerator; the conditions in the two-stage regeneration catalytic cracking device satisfy: the temperature of the dense phase bed of the first regenerator is 630-690 DEG C, and the temperature of the dense phase bed of the second regenerator is 5-50 DEG C higher than that of the dense phase bed of the first regenerator. The method provided by the present application can effectively reduce the VOCs and NOx emissions in the regeneration flue gas of the two-stage regeneration catalytic cracking device.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalytic cracking, in particular to a method for reducing the emission of VOCs and NOx in the regeneration flue gas of a two-stage regeneration catalytic cracking device. BACKGROUND

[0002] Volatile organic compounds (VOCs) are important atmospheric pollutants, which have strong photochemical activity, and can cause chemical reactions in the atmosphere, induce the formation of photochemical smog and organic aerosols, and reduce air visibility. Some VOCs also have an unpleasant odor that can adversely affect the environment. Nitrogen oxides (NOx) are also major atmospheric pollutants, which can easily form nitric acid-type acid rain and photochemical smog in the air, damage the ozone layer, and seriously affect the ecological environment and human health.

[0003] Catalytic cracking is an important heavy oil lightening process in petroleum processing, and is a major process for producing transportation fuels and providing part of the low-carbon olefins. It has outstanding advantages and irreplaceable role. In the catalytic cracking production process, the carbon deposited on the catalyst due to the reaction needs to be burned off to restore the activity of the catalyst. If the catalyst is not completely stripped before entering the regeneration or the carbon is not completely burned off during the regeneration process, a small amount of hydrocarbons will be discharged with the regeneration flue gas, resulting in excessive VOCs in the catalytic cracking device. In addition, during the regeneration process of the two-stage regeneration catalytic cracking catalyst, the emission of NOx often exceeds the emission standard due to the high-temperature coking environment. Therefore, the refining and chemical industry is an important source of VOCs and NOx emissions, and the treatment of VOCs and NOx in the flue gas of the catalytic cracking regeneration device has always been a concern.

[0004] CN107456977A discloses a denitration reaction catalyst composition and a preparation method thereof. The denitration reaction catalyst composition is prepared by a simple process, which can catalyze the conversion of NOx in the flue gas to N2 using CO produced by the device itself as a reducing agent, and can quickly and efficiently denitrate the flue gas. However, this method requires the introduction of a new denitration agent, which requires additional investment, and does not contribute to the control of VOCs in the regeneration tail gas.

[0005] CN109939549A discloses a comprehensive treatment method and device for flue gas. The method couples the treatment of oil refining alkali residue with microalgae cultivation, without the need for catalysts and large amounts of absorbents. The flue gas is first introduced into a desulfurization reactor, and oil refining alkali residue is used as an absorbent to obtain desulfurized flue gas and desulfurized waste liquid. The tail gas after absorption of the distillate oil is subjected to catalytic oxidation or ozone catalytic oxidation to oxidize VOCs to CO2 and H2O. The microalgae cultivation can be set up with multiple levels of photobioreactors according to the content of NOx and CO2 in the flue gas to obtain purified gas. However, this method has a complex process setting and is not suitable for treating large amounts of catalytic cracking exhaust flue gas.

[0006] In addition, the existing reduction of VOCs or NOx in the regeneration flue gas of the catalytic cracking device is generally carried out separately, and in most cases, new equipment needs to be added or a de-nitrating agent or the like is added, which is high in cost and complicated in steps, and may cause secondary pollution.

[0007] Therefore, under the trend of increasingly strict environmental protection indicators, how to simply and effectively reduce the emission of VOCs and NOx in the flue gas of the two-stage full-regeneration catalytic cracking device without adding new equipment and causing secondary pollution is a problem to be solved. SUMMARY

[0008] In view of the above problems existing in the prior art, the purpose of the present application is to provide a method for reducing the emission of VOCs and NOx in the regeneration flue gas of a two-stage regeneration catalytic cracking device.

[0009] In order to achieve the above purpose, the present application provides a method for reducing the emission of VOCs and NOx in the regeneration flue gas of a two-stage regeneration catalytic cracking device, wherein the two-stage regeneration catalytic cracking device comprises a first regenerator, an air riser and a second regenerator connected in sequence, and the method comprises:

[0010] introducing spent catalyst and oxygen-containing gas into the two-stage regeneration catalytic cracking device to flow through the first regenerator, the air riser and the second regenerator in sequence for regeneration reaction, and introducing CO combustion-supporting agent into the dense phase bed layer of the first regenerator;

[0011] The conditions in the two-stage regeneration catalytic cracking device satisfy that the temperature of the dense phase bed layer of the first regenerator is 630-690 DEG C, and the temperature of the dense phase bed layer of the second regenerator is 5-50 DEG C higher than that of the dense phase bed layer of the first regenerator.

[0012] The scheme provided by the present application can simultaneously reduce the emission of VOCs and NOx at the outlet of the regeneration flue gas by introducing CO combustion-supporting agent into the dense phase bed layer of the first regenerator of the two-stage regeneration catalytic cracking device of the present application and controlling the process parameters of the catalytic cracking device,

[0013] It also has the advantages of simple steps and high efficiency.

[0014] Compared with the prior art, specifically, the present application has at least the following advantages:

[0015] (1) The method of the present application saves the cost investment caused by adding equipment;

[0016] (2) In the preferred embodiment of the present application, the emission of VOCs and NOx in the two-stage regenerated catalytic cracking regeneration flue gas can be effectively reduced simultaneously, and specifically, the emission of VOCs and NOx in the two-stage regenerated catalytic cracking regeneration flue gas can be reduced to 20 mg / m 3 and 50 mg / m 3 The environmental protection requirements are met.

[0017] (3) In the preferred embodiment of the present application, the steam quantity of the external heat exchanger and the high-temperature heat exchanger can be improved, which has economic and environmental benefits. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The flowchart of the method for reducing the emission of VOCs and NOx in the two-stage regenerated catalytic cracking device is a preferred specific embodiment of the present application.

[0019] REFERENCE SIGNS

[0020] 1: first regenerator; 2: second regenerator; 3: air riser; 4: external flue of the first regenerator; 5: external flue of the second regenerator; 6: mixed flue; 7: catalyst addition line; 8: spent catalyst inclined pipe; 9: regenerated catalyst inclined pipe. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values which are understood to encompass values near the recited approximate value. The endpoints of the ranges of values and the values thereof should be understood to be open-ended ranges which are understood to include values near the recited range and the recited values, respectively. For numeric values, the endpoints of the ranges of values, the endpoints of the ranges of values and individual point values, and individual point values can be combined with each other to form one or more new ranges of values, which should be considered to be specifically disclosed herein.

[0022] The double-acting slide valve on the external flue of the first regenerator, the flue gas turbine inlet valve and the flue gas turbine bypass valve on the mixed flue, the main air distribution ring on the lower part of the first regenerator, the lower part of the second regenerator and the mixed flue, the external heat exchanger connected to the dense phase bed of the first regenerator, and the high-temperature heat exchanger connected to the mixed flue can all be understood in the conventional manner in the art, and the present application does not make special research on them, so they are not shown in the drawings. Figure 1

[0023] Generally, in the two-stage regenerated catalytic cracking device, when the spent catalyst is regenerated, the carbon deposited on the spent catalyst due to the reaction needs to be burned off, i.e., the spent catalyst undergoes a regeneration reaction in the first regenerator and the second regenerator, so that the activity of the catalyst is restored.

[0024] ​The spent catalyst in the present application refers to the catalyst deactivated by coke after contacting with the raw oil in the catalytic cracking reactor. The carbon content of the spent catalyst is generally 0.8-2 wt%, the carbon content of the regenerated catalyst is below 0.15%, and the content of the carbon to be burned is generally 0.65-1.85 wt%. The carbon generally includes the following parts: catalytic carbon (condensed product generated by cracking reaction), additional carbon (carbon converted from inherent residual carbon of the raw material), and strippable carbon (oil gas remaining in the catalyst micropore due to incomplete stripping).

[0025] In the present application, the first regenerator and the second regenerator of the two-stage regeneration catalytic cracking device are respectively provided with an upper and lower communicating dilute phase bed (dilute phase section) and a dense phase bed (dense phase section), and the dilute phase bed of the first regenerator and the second regenerator is respectively arranged at the upper part of the dense phase bed of the first regenerator and the second regenerator; the upper part of the first regenerator is provided with a catalyst feeding line and an external flue of the first regenerator, which respectively communicate with the dilute phase bed of the first regenerator, and the upper part of the second regenerator is provided with an external flue of the second regenerator, wherein the external flue of the first regenerator and the external flue of the second regenerator converge and communicate with a mixed flue of the two-stage regeneration catalytic cracking device.

[0026] In the present application, preferably, the two-stage regeneration catalytic cracking device further comprises a double-acting slide valve arranged on the external flue of the first regenerator, and a flue gas turbine inlet valve and a flue gas turbine bypass valve arranged on the mixed flue, wherein the double-acting slide valve is used to control the pressure of the dense phase bed of the first regenerator, and the flue gas turbine inlet valve and the flue gas turbine bypass valve are used to control the pressure of the dense phase bed of the second regenerator.

[0027] As described above, the present application provides a method for reducing the emission of VOCs and NOx in the regeneration flue gas of a two-stage regeneration catalytic cracking device, wherein the two-stage regeneration catalytic cracking device comprises a first regenerator, an air lift pipe and a second regenerator which are sequentially communicated, and the method comprises:

[0028] introducing the spent catalyst and the oxygen-containing gas into the two-stage regeneration catalytic cracking device to sequentially flow through the first regenerator, the air lift pipe and the second regenerator for regeneration reaction, and introducing the CO combustion-supporting agent into the dense phase bed of the first regenerator;

[0029] The conditions in the two-stage regeneration catalytic cracking device satisfy that the temperature of the dense phase bed of the first regenerator is 630-690℃, and the temperature of the dense phase bed of the second regenerator is 5-50℃ higher than that of the dense phase bed of the first regenerator.

[0030] In the present application, the conditions in the two-stage regenerated catalytic cracking device are such that the oxygen content in the regenerated flue gas drawn from the outlet of the two-stage regenerated catalytic cracking device is not higher than 5% by volume.

[0031] In the present application, according to a preferred embodiment, the spent catalyst is subjected to a first regeneration reaction in the dense phase bed of the first regenerator in the presence of oxygen-containing gas and CO combustion improver to form semi-spent catalyst, and the semi-spent catalyst is flowed into the second regenerator under a suitable temperature, pressure and suitable air lift to undergo a second regeneration reaction to obtain regenerated catalyst.

[0032] Preferably, the conditions in the air lift pipe include that the air lift speed in the air lift pipe is 1-100 m / s, the pressure in the air lift pipe is 0.08-0.6 MPa, and the temperature in the air lift pipe is 500-600 ℃; further preferably, the air lift speed in the air lift pipe is 1-40 m / s, the pressure in the air lift pipe is 0.2-0.5 MPa, and the temperature in the air lift pipe is 530-560 ℃.

[0033] In the present application, preferably, the CO combustion improver can be introduced into the dense phase bed of the first regenerator through the catalyst addition line, and more preferably, the amount of the CO combustion improver added is 10-1000 kg, and further preferably 300-500 kg, based on 100 t of the spent catalyst introduced into the two-stage regenerated catalytic cracking device.

[0034] In the present application, in particular the scheme of limiting the amount of CO combustion improver to 300-500 kg based on 100 t of the spent catalyst introduced into the two-stage regenerated catalytic cracking device, can effectively reduce the VOCs and NOx emissions in the regenerated flue gas of the two-stage regenerated catalytic cracking device.

[0035] In the present application, in a preferred embodiment, the temperature of the dense phase bed of the first regenerator is 665-675 ℃, and the temperature of the dense phase bed of the second regenerator is 10-30 ℃ higher than that of the first regenerator; therefore, preferably, in the present application, in particular the scheme of limiting the temperature of the dense phase bed of the first regenerator to 665-675 ℃ and the temperature of the dense phase bed of the second regenerator to be 10-30 ℃ higher than that of the first regenerator, can effectively reduce the VOCs and NOx emissions in the regenerated flue gas of the two-stage regenerated catalytic cracking device.

[0036] In the present application, the two-stage regenerated catalytic cracking device further comprises a main air distribution ring respectively arranged in the lower part of the first regenerator, the lower part of the second regenerator and the mixed flue, respectively used to control the amount of main air in the first regenerator, the second regenerator and the mixed flue, wherein the main air distribution ring can be one or more, preferably two.

[0037] In the present application, the method comprises the step of controlling the amount of main air in the regeneration reaction process, preferably at least one of the amount of main air in the first regenerator, the amount of main air in the second regenerator and the amount of main air in the mixed flue of the two-stage regenerated catalytic cracking device.

[0038] In the present application, in a preferred embodiment, the content of oxygen in the regenerated flue gas discharged from the outlet of the two-stage regenerated catalytic cracking device is 0.01-5% by volume, more preferably 0.05-2% by volume.

[0039] In the present application, preferably, the conditions in the two-stage regenerated catalytic cracking device further satisfy that the pressure of the dense phase bed layer of the first regenerator is 0.14-0.295 MPa, and the pressure of the dense phase bed layer of the second regenerator is 0.13-0.285 MPa; more preferably, in a preferred embodiment, the pressure of the dense phase bed layer of the first regenerator is 0.255-0.285 MPa, and the pressure of the dense phase bed layer of the second regenerator is 0.245-0.275 MPa.

[0040] In the present application, especially the scheme comprising that the pressure of the dense phase bed layer of the first regenerator is 0.255-0.285 MPa, and the pressure of the dense phase bed layer of the second regenerator is 0.245-0.275 MPa, can effectively reduce the VOCs and NOx emissions in the regenerated flue gas of the two-stage regenerated catalytic cracking device.

[0041] In the present application, preferably, the content of CO and oxygen in the first regenerated flue gas in the exhaust flue of the first regenerator and the content of CO and oxygen in the second regenerated flue gas in the exhaust flue of the second regenerator are within a certain range, which can appropriately control the temperature of the mixed flue.

[0042] Preferably, the content of CO in the first regenerated flue gas in the exhaust flue of the first regenerator is not higher than 3% by volume, and the content of oxygen is not higher than 0.5% by volume; the content of CO in the second regenerated flue gas in the exhaust flue of the second regenerator is not higher than 1% by volume, and the content of oxygen is not higher than 5% by volume.

[0043] More preferably, the content of CO in the first regenerator flue gas is 0.5-2% by volume, and the content of oxygen is 0.01-0.2% by volume; the content of CO in the second regenerator flue gas is 0.1-0.3% by volume, and the content of oxygen is 0.5-3% by volume.

[0044] In the present application, in a preferred embodiment, the method further comprises controlling the temperature of the mixed flue of the two-stage regenerator catalytic cracking device to be 850-1100°C, preferably 950-1100°C.

[0045] In the present application, preferably, especially the scheme comprising controlling the temperature of the mixed flue of the two-stage regenerator catalytic cracking device to be 950-1100°C, can effectively reduce the VOCs and NOx emissions of the two-stage regenerator catalytic cracking device.

[0046] In the present application, preferably, when the temperature of the mixed flue is not within the above range, the temperature of the mixed flue can be controlled by controlling the amount of combustion air in the mixed flue or controlling the amount of main air of the second regenerator. The combustion air process pipeline can timely adjust the amount of combustion air. The combustion air has a separate pipeline and process to inject into the mixed flue, and the amount of air injected into the mixed flue can control the combustion of the flue gas in the mixed flue.

[0047] In the present application, preferably, the conditions in the two-stage regenerator catalytic cracking device make the VOCs emissions in the regenerator flue gas less than 100 mg / m 3 , and make the NOx emissions in the regenerator flue gas less than 300 mg / m 3 .

[0048] More preferably, the conditions in the two-stage regenerator catalytic cracking device make the VOCs emissions in the regenerator flue gas less than 20 mg / m 3 , and make the NOx emissions in the regenerator flue gas less than 50 mg / m 3 .

[0049] In the present application, the oxygen-containing gas is preferably a gas with an oxygen content of more than 18% by volume, and more preferably air.

[0050] In the present application, the two-stage regenerator catalytic cracking device further comprises a spent catalyst inclined pipe connected with the first regenerator and a regenerated catalyst inclined pipe connected with the second regenerator, wherein the spent catalyst inclined pipe is used to send the spent catalyst into the first regenerator, and the regenerated catalyst inclined pipe is used to lead the regenerated catalyst out of the two-stage regenerator catalytic cracking device.

[0051] The following will be described in combination with Figure 1A preferred embodiment of the method of the present application is provided:

[0052] In the two-stage regenerative catalytic cracking unit, the spent catalyst is fed into the first regenerator 1 through the spent catalyst inclined pipe 8, the main air distribution ring of the first regenerator is adjusted, air is introduced into the first regenerator 1, and the main air flow of the first regenerator is controlled so that the temperature of the dense phase bed layer of the first regenerator is 630-690℃, the double-acting slide valve of the first regenerator is adjusted so that the pressure of the dense phase bed layer of the first regenerator is 0.14-0.295MPa, and CO combustion aid is added to the dense phase bed layer of the first regenerator, and the spent catalyst is regenerated in the first regenerator 1 to generate semi-spent catalyst, which is then flowed into the second regenerator 2 through the air lift pipe 3 under the action of 1-100m / s lift air at 0.08-0.6MPa and 500-600℃; the main air distribution ring of the second regenerator is adjusted, air is introduced, and the main air flow of the second regenerator is controlled so that the temperature of the second dense phase bed layer is 5-50℃ higher than that of the first dense phase bed layer, the flue gas inlet valve and the flue gas bypass valve on the mixing flue 6 are adjusted, and the pressure of the second dense phase bed layer is controlled to be 0.13-0.285MPa, and the semi-spent catalyst is regenerated in the second regenerator to obtain regenerated catalyst which is discharged through the regenerated catalyst inclined pipe 9; the first regeneration flue gas of the first regenerator outer flue 4 and the second regeneration flue gas of the second regenerator outer flue 5 are burned in the mixing flue 6, and the temperature of the mixing flue 6 is controlled to be 850-1100℃, and finally the regenerated flue gas is introduced through the outlet of the mixing flue 6.

[0053] The present application will be described in detail below through examples.

[0054] The CO combustion aid used in the following examples and comparative examples is a commercially available product of CO combustion aid of the Linzi brand purchased from Shandong Junfei Environmental Protection Technology Co., Ltd.

[0055] The content of carbon deposited in the spent catalyst is 1.1wt %.

[0056] Example 1

[0057] In the two-stage regenerative catalytic cracking unit, 100 t of spent catalyst is fed into the first regenerator through the spent catalyst inclined pipe, the main air distribution ring of the first regenerator is adjusted, air is introduced into the first regenerator, and the main air volume of the first regenerator is controlled so that the temperature of the dense phase bed of the first regenerator is 665℃, the double-acting slide valve of the first regenerator is adjusted so that the pressure of the dense phase bed of the first regenerator is 0.26 MPa, and 500 kg of CO combustion aid is added to the dense phase bed of the first regenerator, and the spent catalyst is regenerated in the first regenerator to generate semi-spent catalyst. The semi-spent catalyst is then introduced into the second regenerator through the air lift pipe under the action of the lift air at 0.3 MPa and 530℃ at a speed of 30 m / s; the main air distribution ring of the second regenerator is adjusted, air is introduced, and the main air volume of the second regenerator is controlled so that the temperature of the second dense phase bed is 685℃, the inlet valve and bypass valve of the flue gas turbine on the mixing flue are adjusted, and the pressure of the dense phase bed of the second regenerator is controlled to be 0.25 MPa, and the semi-spent catalyst is regenerated in the second regenerator to obtain regenerated catalyst which is discharged through the regeneration inclined pipe; the first regeneration flue gas of the outer exhaust flue of the first regenerator and the second regeneration flue gas of the outer exhaust flue of the second regenerator are burned in the mixing flue, and the temperature of the mixing flue is controlled to be 1000℃, and finally the regenerated flue gas is introduced through the outlet of the mixing flue.

[0058] Among them, the content of oxygen and CO in the first regeneration flue gas in the outer exhaust flue of the first regenerator, the content of oxygen and CO in the second regeneration flue gas in the outer exhaust flue of the second regenerator, the emission amount of VOCs and NOx in the final catalytic cracking unit flue gas and the content of oxygen in the regeneration flue gas at the outlet of the mixing flue are tested, and the results are shown in Table 1.

[0059] Example 2

[0060] In the two-stage regenerative catalytic cracking unit, 100 t of spent catalyst is fed into the first regenerator through the spent catalyst inclined pipe, the main air distribution ring of the first regenerator is adjusted, air is introduced into the first regenerator, and the main air volume of the first regenerator is controlled so that the temperature of the dense phase bed of the first regenerator is 675°C; the double-acting slide valve of the first regenerator is adjusted so that the pressure of the dense phase bed of the first regenerator is 0.265 MPa, and 300 kg of CO combustion aid is added to the dense phase bed of the first regenerator; the spent catalyst is regenerated in the first regenerator to generate semi-spent catalyst; the semi-spent catalyst is then introduced into the second regenerator through the air lift pipe under the action of 40 m / s of lift air at 0.5 MPa and 560°C; the main air distribution ring of the second regenerator is adjusted, air is introduced, and the main air volume of the second regenerator is controlled so that the temperature of the second dense phase bed is 690°C; the flue gas inlet valve and the flue gas bypass valve on the mixing flue are adjusted to control the pressure of the dense phase bed of the second regenerator to 0.255 MPa; the semi-spent catalyst is regenerated in the second regenerator to obtain regenerated catalyst which is discharged through the regeneration inclined pipe; the first regeneration flue gas in the outer flue of the first regenerator and the second regeneration flue gas in the outer flue of the second regenerator are burned in the mixing flue, and the temperature of the mixing flue is controlled to 900°C; finally, the regenerated flue gas is introduced out of the outlet of the mixing flue.

[0061] The content of oxygen and CO in the first regeneration flue gas in the outer flue of the first regenerator, the content of oxygen and CO in the second regeneration flue gas in the outer flue of the second regenerator, the emission amount of VOCs and NOx and the content of oxygen in the regenerated flue gas at the outlet of the mixing flue are tested, and the results are shown in Table 1.

[0062] Example 3

[0063] In the two-stage regenerative catalytic cracking unit, 100 t of spent catalyst is fed into the first regenerator through the spent catalyst inclined pipe, the main air distribution ring of the first regenerator is adjusted, air is introduced into the first regenerator, and the main air volume of the first regenerator is controlled so that the temperature of the dense phase bed layer of the first regenerator is 670°C; the double-acting slide valve of the first regenerator is adjusted so that the pressure of the dense phase bed layer of the first regenerator is 0.263 MPa, and 400 kg of CO combustion aid is added to the dense phase bed layer of the first regenerator; the spent catalyst is regenerated in the first regenerator to generate semi-spent catalyst; the semi-spent catalyst is then introduced into the second regenerator through the air lift pipe under the action of the lift air at 0.4 MPa and 540°C and at a lift air speed of 35 m / s; the main air distribution ring of the second regenerator is adjusted, air is introduced, and the main air volume of the second regenerator is controlled so that the temperature of the second dense phase bed layer is 700°C; the inlet valve and bypass valve of the flue gas turbine on the mixing flue are adjusted to control the pressure of the dense phase bed layer of the second regenerator to be 0.253 MPa; the semi-spent catalyst is regenerated in the second regenerator to obtain regenerated catalyst which is discharged through the regeneration inclined pipe; the first regeneration flue gas in the outer flue of the first regenerator and the second regeneration flue gas in the outer flue of the second regenerator are burned in the mixing flue, and the temperature of the mixing flue is controlled to be 1100°C; finally, the regenerated flue gas is introduced out of the outlet of the mixing flue.

[0064] The content of oxygen and CO in the first regeneration flue gas in the outer flue of the first regenerator, the content of oxygen and CO in the second regeneration flue gas in the outer flue of the second regenerator, the emission amount of VOCs and NOx and the content of oxygen in the regenerated flue gas at the outlet of the mixing flue were tested, and the results are shown in Table 1.

[0065] Example 4

[0066] The method of Example 1 was followed, except that the temperature of the dense phase bed layer of the first regenerator was controlled to be 650°C, and the temperature of the dense phase bed layer of the second regenerator was controlled to be 670°C.

[0067] The content of oxygen and CO in the first regeneration flue gas in the outer flue of the first regenerator, the content of oxygen and CO in the second regeneration flue gas in the outer flue of the second regenerator, the emission amount of VOCs and NOx and the content of oxygen in the regenerated flue gas at the outlet of the mixing flue were tested, and the results are shown in Table 1.

[0068] Example 5

[0069] The method of Example 1 was followed, except that the temperature of the dense phase bed layer of the first regenerator was controlled to be 685°C, and the temperature of the dense phase bed layer of the second regenerator was controlled to be 705°C.

[0070] The oxygen content and the CO content in the first regeneration flue gas in the outer flue of the first regenerator, the oxygen content and the CO content in the second regeneration flue gas in the outer flue of the second regenerator, the VOCs and NOx emission amount and the oxygen content in the regeneration flue gas at the outlet of the mixed flue were tested, and the results are shown in Table 1.

[0071] Example 6

[0072] The method of Example 1 was followed, except that 700 kg of CO combustion-supporting agent was added to the dense phase bed of the first regenerator.

[0073] The oxygen content and the CO content in the first regeneration flue gas in the outer flue of the first regenerator, the oxygen content and the CO content in the second regeneration flue gas in the outer flue of the second regenerator, the VOCs and NOx emission amount and the oxygen content in the regeneration flue gas at the outlet of the mixed flue were tested, and the results are shown in Table 1.

[0074] Example 7

[0075] The method of Example 1 was followed, except that the temperature of the mixed flue was controlled at 850°C.

[0076] The oxygen content and the CO content in the first regeneration flue gas in the outer flue of the first regenerator, the oxygen content and the CO content in the second regeneration flue gas in the outer flue of the second regenerator, the VOCs and NOx emission amount and the oxygen content in the regeneration flue gas at the outlet of the mixed flue were tested, and the results are shown in Table 1.

[0077] Example 8

[0078] The method of Example 1 was followed, except that the pressure of the dense phase bed of the first regenerator was 0.18 MPa, the pressure of the dense phase bed of the first regenerator was 0.17 MPa, and the temperature of the dense phase bed of the second regenerator was 675°C.

[0079] The oxygen content and the CO content in the first regeneration flue gas in the outer flue of the first regenerator, the oxygen content and the CO content in the second regeneration flue gas in the outer flue of the second regenerator, the VOCs and NOx emission amount and the oxygen content in the regeneration flue gas at the outlet of the mixed flue were tested, and the results are shown in Table 1.

[0080] Comparative Example 1

[0081] The method of Example 1 was followed, except that no CO combustion-supporting agent was added during the regeneration reaction.

[0082] The oxygen content and CO content in the first regenerative flue gas in the outer flue of the first regenerator, the oxygen content and CO content in the second regenerative flue gas in the outer flue of the second regenerator, the VOCs and NOx emission amount and the oxygen content in the regenerative flue gas at the outlet of the mixed flue of the final catalytic cracking device are tested, and the results are shown in Table 1.

[0083] Comparative Example 2

[0084] The method of Example 1 is followed, except that the temperature of the dense phase bed of the first regenerator is controlled at 700℃, and the temperature of the dense phase bed of the second regenerator is controlled at 710℃.

[0085] The oxygen content and CO content in the first regenerative flue gas in the outer flue of the first regenerator, the oxygen content and CO content in the second regenerative flue gas in the outer flue of the second regenerator, the VOCs and NOx emission amount and the oxygen content in the regenerative flue gas at the outlet of the mixed flue of the final catalytic cracking device are tested, and the results are shown in Table 1.

[0086] Table 1

[0087]

[0088] Table 1 (continued 1)

[0089]

[0090] As can be seen from the results in Table 1 above, compared with the prior art, the method of the present application can effectively reduce the VOCs and NOx emission amount in the regenerative flue gas of the two-stage regenerative catalytic cracking device, and meet the environmental protection requirements.

[0091] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A method for reducing the emission of VOCs and NOx in the regeneration flue gas of a two-stage regeneration catalytic cracking device, wherein the two-stage regeneration catalytic cracking device comprises a first regenerator, an air riser and a second regenerator connected in sequence, the method comprising: introducing spent catalyst and an oxygen-containing gas into the two-stage regeneration catalytic cracking device to sequentially flow through the first regenerator, the air riser and the second regenerator for regeneration reaction, and introducing a CO combustion improver into the dense phase bed of the first regenerator, wherein the amount of the CO combustion improver introduced into the two-stage regeneration catalytic cracking device is 300-500 kg per 100 t of the spent catalyst; and the conditions in the two-stage regeneration catalytic cracking device satisfy that the temperature of the dense phase bed of the first regenerator is 650-675℃, and the temperature of the dense phase bed of the second regenerator is 5-50℃ higher than that of the dense phase bed of the first regenerator. The conditions in the air riser include that the riser wind speed in the air riser is 1-100 m / s, the pressure in the air riser is 0.08-0.6 MPa, and the temperature in the air riser is 500-600℃. The conditions in the air riser include that the riser wind speed in the air riser is 1-40 m / s, the pressure in the air riser is 0.2-0.5 MPa, and the temperature in the air riser is 530-560℃.

2. The method of claim 1, wherein, The temperature of the dense phase bed of the first regenerator is 665-675℃, and the temperature of the dense phase bed of the second regenerator is 10-30℃ higher than that of the first regenerator.

3. The method of claim 2, wherein, The conditions in the two-stage regeneration catalytic cracking device make the oxygen content in the regeneration flue gas discharged from the outlet of the two-stage regeneration catalytic cracking device not higher than 5% by volume.

4. The method of any of claims 1-3, wherein, The method further comprises the step of controlling the amount of main air in the regeneration reaction process, including controlling at least one of the amount of main air in the first regenerator, the amount of main air in the second regenerator, and the amount of main air in the mixed flue duct of the two-stage regeneration catalytic cracking device.

5. The method of any of claims 1-3, wherein, The oxygen content in the regeneration flue gas discharged from the outlet of the two-stage regeneration catalytic cracking device is 0.01-5% by volume. The conditions in the two-stage regeneration catalytic cracking device further satisfy that the pressure of the dense phase bed of the first regenerator is 0.14-0.295 MPa, and the pressure of the dense phase bed of the second regenerator is 0.13-0.285 MPa.

6. The method of claim 5, wherein, The pressure of the dense phase bed of the first regenerator is 0.255-0.285 MPa, and the pressure of the dense phase bed of the second regenerator is 0.245-0.275 MPa.

7. The method of any of claims 1-3, wherein, The conditions in the first regenerator make the CO content in the first regeneration flue gas in the external flue duct of the first regenerator not higher than 3% by volume, and the oxygen content not higher than 0.5% by volume; and 8. The method of claim 7, wherein, The conditions in the second regenerator make the CO content in the second regeneration flue gas in the external flue duct of the second regenerator not higher than 1% by volume, and the oxygen content not higher than 5% by volume.

9. The method of any of claims 1-3, wherein, The method further comprises controlling the temperature of the mixed flue duct of the two-stage regeneration catalytic cracking device to be 850-1100℃. ​ 10. The method of any of claims 1-3, wherein, ​ 11. The method of claim 10, wherein, The method further comprises controlling the temperature of the mixed flue of the two-stage regeneratively catalytic cracking device to be 950-1100℃.

12. The method of any one of claims 1-3, wherein, The conditions in the two-stage regeneratively catalytic cracking unit are such that the emissions of VOCs in the regeneration flue gas are less than 100 mg / m 3 and such that the emissions of NOx in the regeneration flue gas are less than 300 mg / m 3 .

13. The method of claim 12, wherein, The conditions in the two-stage regeneratively catalytic cracking unit are such that the emissions of VOCs in the regeneration flue gas are less than 20 mg / m 3 and such that the emissions of NOx in the regeneration flue gas are less than 50 mg / m 3 .

Images