Method for on-line soot cleaning of catalytic cracking smokers

Abstract

This invention relates to the field of cleaning flue gas systems and discloses a method for online cleaning of catalytic cracking flue gas systems. The method includes: during the operation of the flue gas system, flue gas and turbine steam enter the flue gas system for cleaning treatment; the cleaning treatment conditions include: (1) first-stage cooling: reducing the inlet temperature of the flue gas system to 500-570℃; (2) second-stage cooling: continuing to reduce the inlet temperature of the flue gas system by 275-350℃; (3) third-stage heating: finally raising the inlet temperature of the flue gas system to 580-620℃; (4) repeating steps (1)-(3) until the maximum vibration value of the flue gas system decreases by more than 50%, and the cooling rates of the first-stage cooling and the second-stage cooling are different. The method of this invention has broad application prospects in catalytic cracking units in the petrochemical industry. Applying the method of this invention for online cleaning can reduce the number of times the flue gas system needs to be shut down for cleaning by at least half, improve the continuous operation cycle of the flue gas system, save more than RMB 1 million in repair costs per cycle, and save more than 1000MW of electricity.

Description

Technical Field

[0001] This invention relates to the technical field of cleaning scale from flue gas machines, specifically to a method for online cleaning of scale from a catalytic cracking flue gas machine. Background Technology

[0002] Catalytic cracking is a major secondary petroleum processing technology in China's petroleum refining industry. It involves the cracking reaction of heavy oil under high temperature and with the aid of a catalyst, converting it into cracked gas, gasoline, and diesel. The catalytic converter is the main energy-saving equipment in the unit, utilizing the high-temperature flue gas generated by the regenerator's coke combustion to drive the main fan or generator. Depending on the size of the unit, the power of the catalytic converter ranges from 8000 to 20000 kW. The catalytic regeneration flue gas contains a large amount of catalyst powder; after three stages of cyclone separation, approximately 100 mg / m³ of catalyst powder remains in the flue gas. 3 The dust contains particles, of which 93% are micro-dust particles smaller than 10μm. These fine dust particles adhere to the blades of the flue gas machine and gradually accumulate, causing the vibration of the machine to gradually increase and the efficiency to gradually decrease.

[0003] To ensure the efficiency and safety of the flue gas turbine operation, catalytic cracking units typically employ a periodic shutdown and maintenance plan to address the issue of scale buildup threatening the safe operation of the equipment. The maintenance period for the flue gas turbine is approximately one week. During this time, the catalytic unit operates at reduced capacity, the standby main blower is started, the unit's processing capacity decreases, and energy consumption increases significantly. For example, a certain company's 1.2 million tons / year catalytic cracking unit experienced severe scale buildup in its flue gas turbine, requiring descaling approximately every three months. After shutdown, it was found that the scale thickness reached 9mm, with some scale detachment preventing the turbine from turning, and significant wear marks on the blade tips were observed.

[0004] CN110871199A provides an online descaling method for the flue gas turbine of a catalytic cracking unit. This method switches the main blower-flue gas turbine unit to standby after the flue gas turbine rotor has been scaled up, shuts down the main blower-flue gas turbine system, and then cleans the scale online, improving the descaling efficiency and reducing the losses caused by the shutdown of the flue gas turbine. It has achieved good technical results, but the method has the following defects: (1) The speed of the flue gas turbine is controlled below 1000 rpm during descaling. The speed is controlled by manually controlling the warm-up valve, which is not accurate. At low speeds, the vibration of the unit may not be apparent. (2) When the flue gas turbine is shut down, the unit starts up the standby unit, which requires a reduction in processing volume and high power consumption of the standby unit. (3) After online descaling of the flue gas turbine of the catalytic cracking unit, it needs to be reheated and the speed of the flue gas turbine needs to be readjusted, which takes a long time to resume production. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of long maintenance time and high cost when cleaning scale on catalytic cracking flue gas machines in the prior art.

[0006] To achieve the above objectives, the present invention provides a method for online descaling of a catalytic cracking flue gas machine, the method comprising:

[0007] During the operation of the range hood, flue gas and steam from the rotary disc enter the range hood for descaling.

[0008] The conditions for descaling include:

[0009] (1) First cooling process: Reduce the inlet temperature of the range hood to 500-570℃;

[0010] (2) Second cooling process: Continue to reduce the inlet temperature of the range hood by 275-350℃;

[0011] (3) Third stage of heating: Finally, the inlet temperature of the range hood is raised to 580-620℃;

[0012] (4) Repeat steps (1)-(3) until the maximum vibration value of the range hood decreases by more than 50%;

[0013] The cooling rates of the first and second cooling programs are different.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects:

[0015] (1) The method of the present invention does not require the activation of the backup smoke machine. It cleans the smoke machine online during its operation, achieving true online cleaning of the smoke machine. After online cleaning, the vibration of the smoke machine unit is significantly reduced, effectively extending the continuous operation cycle of the catalytic smoke machine and reducing the frequency of smoke machine maintenance.

[0016] (2) The present invention performs online descaling during the operation of the catalytic cracking flue gas machine. By controlling the conditions for descaling treatment in the flue gas machine during operation, the operating speed of the catalytic cracking flue gas machine can be kept at a normal speed, and there is no risk of long-term low speed and bearing wear.

[0017] (3) The catalytic cracking flue gas machine can be put into operation directly after being cleaned by the online descaling method of the present invention, without the need for reheating and speed-up, and the time to resume production is short.

[0018] (4) The method of the present invention saves costs and maintains long-term operation, reduces the number of times the range hood is shut down for cleaning by at least half, increases the continuous operation cycle of the range hood, saves more than RMB1 million in repair costs per cycle, and saves more than 1000MW of electricity. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the configuration of a smoke-making machine unit. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] Figure 1 This is a schematic diagram of a flue gas turbine unit. The unit includes a flue gas turbine (hereinafter referred to as the turbine), a main fan, a speed increaser, and a motor. During operation, the turbine expands the heat and pressure energy in the flue gas to do work, converting it into mechanical energy. The power output of the turbine is used to drive the main fan, thereby achieving the purpose of energy recovery. In this invention, [the following is a separate section, likely related to energy recovery]. Figure 1 The present invention provides an exemplary description of a method for online descaling of a catalytic cracking flue gas unit, but the method is not limited to the configuration diagram of the flue gas unit applicable to this invention.

[0022] This invention provides a method for online descaling of a catalytic cracking flue gas turbine, wherein the turbine speed is maintained at the same level as during normal operation of the turbine unit during descaling, and the turbine can be directly put into operation after online descaling without reheating. The method includes:

[0023] During the operation of the range hood, flue gas and steam from the rotary disc enter the range hood for descaling.

[0024] The conditions for descaling include:

[0025] (1) First cooling process: Reduce the inlet temperature of the range hood to 500-570℃;

[0026] (2) Second cooling process: Continue to reduce the inlet temperature of the range hood by 275-350℃;

[0027] (3) Third stage of heating: Finally, the inlet temperature of the range hood is raised to 580-620℃;

[0028] (4) Repeat steps (1)-(3) until the maximum vibration value of the range hood decreases by more than 50%;

[0029] The cooling rates of the first and second cooling programs are different.

[0030] In this invention, during the operation of the flue gas fan, it is possible to not only keep the fan running continuously without switching the main fan, but also to avoid operations that would affect the normal operation of the catalytic flue gas fan, such as reducing the output of the fan unit. Furthermore, by adjusting the flue gas and the steam of the impeller, the blades of the fan can be cleaned. At the same time, controlling the conditions of the cleaning process can better achieve the cleaning of the fan. After online cleaning, all loose scale pieces are removed, allowing the fan to operate stably after cleaning, and further improving the working capacity of the fan.

[0031] The vibration value of the range hood mentioned in this invention includes the vibration value of the range hood shaft and / or the vibration value of the range hood housing. The highest vibration value of the range hood refers to the highest vibration value among the vibration values ​​of the range hood shaft and the vibration values ​​of the range hood housing.

[0032] According to some preferred embodiments of the present invention, the conditions for the descaling treatment include:

[0033] (1) First cooling process: Reduce the inlet temperature of the range hood to 530-560℃;

[0034] (2) Second cooling process: Continue to reduce the inlet temperature of the range hood by 280-320℃;

[0035] (3) Third stage of heating: Finally, the inlet temperature of the range hood is raised to 590-610℃;

[0036] (4) Repeat steps (1)-(3) until the maximum vibration value of the range hood decreases by more than 50%.

[0037] By adopting the above implementation method, the continuous operation cycle of the catalytic cracking flue gas machine can be effectively extended and the frequency of flue gas machine maintenance can be reduced.

[0038] According to the present invention, in some embodiments, in step (1), the inlet temperature of the flue gas fan is reduced to 500-570°C, preferably to 530-560°C, at a cooling rate of 50-75°C / h. Using the aforementioned embodiments can better increase the efficiency and effectiveness of descaling.

[0039] According to the present invention, there is no particular limitation on how to achieve the first-stage cooling method as long as the purpose of the present invention can be achieved. For example, in step (1), the opening of the butterfly valve at the inlet of the flue is reduced from 95-100% at a rate of (8-12)% / 10min, so that the inlet temperature of the flue is reduced at a cooling rate of 50-75℃ / h to 500-570℃ (e.g., 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 570℃ or 580℃), preferably to 530-560℃. By adopting the aforementioned embodiment, the cooling rate and the cooling endpoint during the first-stage cooling are achieved by controlling the butterfly valve to reduce the amount of flue gas entering the flue, while also achieving better descaling.

[0040] According to the present invention, the opening degree of the butterfly valve at the inlet of the smoke hood is 95-100%, which means that the butterfly valve is fully open. It is understood that when the temperature is cooled to the required temperature of 500-570°C, preferably 530-560°C, during the first cooling program, the first cooling program is stopped and the second cooling program begins.

[0041] According to the present invention, in some embodiments, in step (2), the inlet temperature of the range hood is reduced to 275-350°C, preferably to 280-320°C, at a cooling rate of 75-100°C / h. Using the aforementioned embodiments, a better cleaning effect can be achieved, reducing the number of times the range hood needs to be shut down for cleaning by at least half, and increasing the continuous operation cycle of the range hood.

[0042] According to the present invention, there is no particular limitation on how to achieve the second-stage cooling method as long as the purpose of the present invention can be achieved. For example, in step (2), the opening of the butterfly valve at the inlet of the flue gas hood continues to be reduced at a rate of (8-12)% / 10min, so that the inlet temperature of the flue gas hood is reduced to 275-350℃ (e.g., 275℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃ or 350℃) at a cooling rate of 75-100℃ / h, preferably to 280-320℃. By adopting the aforementioned embodiment, the cooling rate and cooling endpoint during the second-stage cooling are achieved by controlling the butterfly valve to reduce the amount of flue gas entering the flue gas hood, while also achieving better cleaning of the flue gas hood.

[0043] According to the present invention, in some embodiments, the heating rate during the third heating process is 100-150℃ / h. By employing the aforementioned embodiments, the online descaling effect can be better achieved, and the descaling efficiency can be improved. Furthermore, the inlet temperature of the descaled range hood exceeds 500℃, equivalent to a preheated state, allowing for direct operation without the need for reheating.

[0044] According to the present invention, there is no particular limitation on how to achieve the third-stage heating method as long as the purpose of the present invention can be achieved. For example, in step (3), the butterfly valve at the inlet of the range hood is opened at a rate of (15-25)% / 5min, so that the inlet temperature of the range hood is raised to 580-620℃ (e.g., 580℃, 590℃, 600℃, 610℃ or 620℃) at a heating rate of 100-150℃ / h, preferably to 590-610℃. By adopting the aforementioned embodiment, the heating rate and heating endpoint during the third-stage heating are achieved by controlling the butterfly valve to increase the amount of flue gas entering the range hood, while also achieving better cleaning of the range hood.

[0045] According to the present invention, in some embodiments, during the first cooling process in step (1), the flow rate of steam from the turbine entering the flue gas fan is 0.8-2 t / h (e.g., 0.8 t / h, 1 t / h, 1.2 t / h, 1.4 t / h, 1.6 t / h, or 2 t / h), preferably 1.2-1.6 t / h. By employing the aforementioned embodiments, the cleaning of the flue gas fan can be better achieved.

[0046] According to the present invention, in some embodiments, during the second cooling process in step (2), the flow rate of steam entering the flue gas fan is repeatedly adjusted between different flow rates within the range of 0.6-1.8 t / h.

[0047] According to the present invention, the flow rate of the steam from the rotary disc entering the flue gas fan is repeatedly adjusted between different flow rates within the range of 0.6-1.8 t / h in step (2). During the second cooling process, the steam from the rotary disc circulates repeatedly in the flue gas fan at at least two different flow rates at certain time intervals. In some preferred embodiments, during the second cooling process in step (2), the interval between different flow rates is 3-10 min, for example, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, or 10 min. By adopting the aforementioned embodiments, the work done by the flue gas fan unit can be better modified, and in conjunction with the change in inlet temperature, the online descaling effect can be better guaranteed.

[0048] According to the present invention, as long as the purpose of the present invention can be achieved, there is no special limitation on the number of groups with different flow rates during the second cooling program. In some preferred embodiments, during step (2), the flow rate of steam entering the flue gas fan during the second cooling program is repeatedly adjusted between two steam quantities: At / h and Bt / h, where A is 0.6-1 and B = (1.2-3)*A. By adopting the aforementioned embodiments, the online descaling effect can be further guaranteed.

[0049] In this invention, there is no special restriction on whether At / h or Bt / h is used before the second cooling process begins, but it is preferred to perform At / h first.

[0050] According to the present invention, in some embodiments, the conditions for the cleaning treatment further include: after the maximum vibration value of the range hood decreases by more than 50%, the inlet temperature of the range hood remains at 580-620°C for more than 5 hours.

[0051] According to some preferred embodiments of the present invention, after the maximum vibration value of the range hood decreases by more than 50%, the inlet temperature of the range hood remains at 590-610°C for 8-14 hours. By employing the aforementioned embodiments, it is possible to further ensure that all loosened scale is removed, thus achieving better scale removal.

[0052] According to the present invention, in some embodiments, during the third temperature rise in step (3), the flow rate of steam from the turbine entering the flue gas fan is 0.8-2 t / h, preferably 0.9-1.6 t / h. Using the aforementioned embodiments further ensures the effectiveness of online descaling.

[0053] According to the present invention, during the operation of the flue gas machine, the temperature of the flue gas and the temperature of the steam from the turbine are the actual temperatures during the actual operation of the flue gas machine unit. There are no special limitations in the present invention. For example, in some embodiments, the temperature of the flue gas during the operation of the catalytic cracking flue gas machine is 650-700°C.

[0054] In this invention, the flow rate of the flue gas is not specifically limited and can be selected according to the actual process during the actual operation of the flue gas generator unit, for example, 12-15 standard cubic meters per hour.

[0055] According to some embodiments of the present invention, the temperature of the steam from the disc is 280-340°C during the operation of the smoke machine.

[0056] As mentioned above, in existing online descaling techniques, the main fan needs to be disconnected from the system and the fan speed reduced. Since reducing the fan speed can only be achieved by closing the butterfly valve, it is difficult to control precisely and carries the risk of insufficient oil film stiffness due to excessively low speed. Furthermore, vibration during low-speed operation does not represent vibration at normal speed, leading to inaccurate assessment of the descaling effect. If the speed is increased before assessment, a 4-6 hour heating and speed-up period is required. According to this invention, the fan maintains normal operation during operation, and its speed is also normal. The fan speed is the normal speed during actual operation of the fan unit, and this invention does not impose any special limitations. In some embodiments, the fan speed is 5000-7000 rpm during operation. The aforementioned embodiments refer to the present invention where the fan speed is maintained at normal speed during descaling. This embodiment eliminates the risk of prolonged low speed and bearing wear, and at its normal operating speed, the real-time changes of the fan can be monitored. After online descaling is completed, there is no need to increase the speed to assess the effect, and no further speed increase is required during recovery.

[0057] The present invention will be described in detail below through embodiments. In the following embodiments, during online descaling of the catalytic cracking flue gas turbine, the vibration of the front and rear shafts of the flue gas turbine unit is measured using the SG8000 unit condition monitoring system, and the vibration of the unit casing is measured on-site using a vibration detector.

[0058] Example 1

[0059] In early 2022, Company A conducted online descaling of its catalytic cracking flue gas system. The method included:

[0060] During the operation of the range hood, flue gas (temperature 680℃, flow rate 130,000 standard cubic meters / hour) and steam from the rotary disc (temperature 305℃) enter the range hood for cleaning. The range hood rotates at 5785 rpm.

[0061] The conditions for descaling include:

[0062] (1) First cooling process: The opening of the butterfly valve at the inlet of the smoke hood is reduced from 95% at a rate of 10% / 10min, so that the inlet temperature of the smoke hood is reduced to 550℃ at a rate of about 70℃ / h.

[0063] During the first cooling process, the flow rate of steam entering the flue gas fan from the rotary disc is 0.9 t / h;

[0064] (2) Second cooling process: The opening of the butterfly valve at the inlet of the smoke hood continues to decrease at a rate of 10% / 10min, so that the inlet temperature of the smoke hood is reduced to 300℃ at a cooling rate of about 100℃ / h.

[0065] During the second cooling process, the flow rate of steam entering the flue gas fan is repeatedly adjusted at 5-minute intervals between two flow rates of 0.6t / h and 1.2t / h.

[0066] (3) Third program heating: The butterfly valve at the inlet of the smoke hood opens at a rate of 20% / 5min, so that the inlet temperature of the smoke hood rises to 600℃ at a rate of about 120℃ / h.

[0067] During the third heating process, the flow rate of steam entering the flue gas fan from the rotary disc is 0.9 t / h;

[0068] (4) Repeat steps (1)-(3) until the maximum vibration value of the smoke machine drops by more than 50%, and then keep the inlet temperature of the smoke machine at 600℃ for 12 hours.

[0069] After the cleaning process is completed, open the butterfly valve at the inlet of the flue gas hood to 95% to resume normal production.

[0070] Finally, repeat steps (1)-(3) once, and the online cleaning time is approximately 24 hours.

[0071] Table 1 shows the vibration values ​​of the smoke hood shaft and the smoke hood casing before and after online cleaning. The vibration values ​​in Table 1 are the lowest values ​​during the test.

[0072] Vibration spectrum analysis of the smoke machine unit revealed the following: Before online cleaning, the vibration value of the smoke machine was 65µm with vibration jumps. The spectrum analysis showed slight clipping and a 1 / 2 harmonic component, indicating severe scaling on the moving blades and slight friction with the machine body. After online cleaning, the vibration of the smoke machine stabilized at around 39µm, and the spectrum analysis showed the power frequency with no 1 / 2 harmonic or clipping phenomenon, indicating that the friction was eliminated and the cleaning effect was significant.

[0073] After online descaling, the vibration of the range hood shaft remained at 38-39µm for two months, without any vibration jumps.

[0074] Under the same load on the main fan, the average motor power of the range hood was 531KW and the dual valve opening was 6.5% one month before online cleaning. One month after online cleaning, the average main motor power was 503KW and the dual valve opening was 1.7%. The smaller dual valve opening indicates that the cleaning effect of the machine is obvious, the blade gap of the range hood increases, the amount of flue gas entering the range hood increases, and the working capacity of the range hood is improved after online cleaning.

[0075] After online descaling of the catalytic cracking flue gas unit, the unit saved 550,000 yuan in equipment maintenance and repair costs; saved 580,800 KW (approximately 348,000 yuan) in industrial electricity costs; shortened the low-load operation time; and allowed the unit to process an additional 4,000 tons of raw materials, thus reducing the pressure on production and operation.

[0076] Example 2

[0077] In mid-2022, Company B conducted online descaling of its catalytic cracking flue gas system. The method included:

[0078] During the operation of the range hood, flue gas (temperature 670℃, flow rate 127,000 standard cubic meters / hour) and steam from the rotary disc (temperature 302℃) enter the range hood for cleaning. The range hood rotates at 5787 rpm.

[0079] The conditions for descaling include:

[0080] (1) First cooling process: The opening of the butterfly valve at the inlet of the smoke hood is reduced from 95% at a rate of 8% / 10min, so that the inlet temperature of the smoke hood is reduced to 530℃ at a rate of about 60℃ / h.

[0081] During the first cooling process, the flow rate of steam entering the flue gas fan from the rotary disc is 1.6 t / h;

[0082] (2) Second cooling process: The opening of the butterfly valve at the inlet of the smoke hood continues to decrease at a rate of 8% / 10min, so that the inlet temperature of the smoke hood is reduced to 280℃ at a cooling rate of about 90℃ / h.

[0083] During the second cooling process, the flow rate of steam entering the flue gas fan is repeatedly adjusted at two flow rates of 1t / h and 1.5t / h at 5-minute intervals.

[0084] (3) Third program heating: The butterfly valve at the inlet of the smoke hood opens at a rate of 15% / 5min, so that the inlet temperature of the smoke hood rises to 610℃ at a rate of about 130℃ / h.

[0085] During the third heating process, the flow rate of steam entering the flue gas fan from the rotary disc is 1.6 t / h;

[0086] (4) Repeat steps (1)-(3) until the maximum vibration value of the smoke machine drops by more than 50%, and then the inlet temperature of the smoke machine stays at 610℃ for 8 hours.

[0087] After the cleaning process is completed, open the butterfly valve at the inlet of the flue gas hood to 95% to resume normal production.

[0088] Finally, repeat steps (1)-(3) twice, and the online cleaning time is approximately 26 hours.

[0089] Table 2 shows the vibration values ​​of the smoke hood unit shaft and the smoke hood unit casing before and after online cleaning. The vibration values ​​in Table 2 are the lowest values ​​during the test.

[0090] After online descaling, the vibration of the range hood shaft remained at 34-39µm for two months, without any vibration jumps.

[0091] Example 3

[0092] In mid-2022, Company C conducted online descaling of its catalytic cracking flue gas system. The method included:

[0093] During the operation of the range hood, flue gas (temperature 675℃, flow rate 125,000 standard cubic meters / hour) and steam from the rotary disc (temperature 310℃) enter the range hood for cleaning. The range hood rotates at 5787 rpm.

[0094] The conditions for descaling include:

[0095] (1) First cooling process: The opening of the butterfly valve at the inlet of the smoke hood is reduced from 95% at a rate of 12% / 10min, so that the inlet temperature of the smoke hood is reduced to 560℃ at a rate of about 65℃ / h.

[0096] During the first cooling process, the flow rate of steam entering the flue gas fan from the rotary disc is 1.0 t / h;

[0097] (2) Second cooling process: The opening of the butterfly valve at the inlet of the smoke hood continues to decrease at a rate of 12% / 10min, so that the inlet temperature of the smoke hood is reduced to 320℃ at a cooling rate of about 90℃ / h.

[0098] During the second cooling process, the flow rate of steam entering the flue gas fan is repeatedly adjusted at two flow rates of 0.6t / h and 1.8t / h at 5-minute intervals.

[0099] (3) Third program heating: The butterfly valve at the inlet of the smoke hood opens at a rate of 25% / 5min, so that the inlet temperature of the smoke hood rises to 590℃ at a rate of about 130℃ / h.

[0100] During the third heating process, the flow rate of steam entering the flue gas fan is 1.2 t / h.

[0101] (4) Repeat steps (1)-(3) until the maximum vibration value of the smoke machine drops by more than 50%, and then the inlet temperature of the smoke machine stays at 590℃ for 14 hours.

[0102] Finally, repeat steps (1)-(3) once, and the online cleaning time is about 18 hours.

[0103] After the cleaning process is completed, open the butterfly valve at the inlet of the flue gas hood to 95% to resume normal production.

[0104] Table 3 shows the vibration values ​​of the smoke hood unit shaft and the smoke hood unit casing before and after online cleaning. The vibration values ​​in Table 3 are the lowest values ​​during the test.

[0105] After online descaling, the vibration of the range hood shaft remained at 36-41µm for two months, without any vibration jumps.

[0106] Example 4

[0107] In early 2022, Company A carried out online descaling of a catalytic cracking flue gas unit in another flue gas unit with the same operating process as in Example 1, following the method of Example 1.

[0108] The difference is as follows: In the first cooling process, the opening of the butterfly valve at the inlet of the flue gas fan is reduced from 95% at a rate of 30% / 10min, so that the inlet temperature of the flue gas fan is reduced to 550℃ at a rate of about 80℃ / h; During the first cooling process, the flow rate of steam entering the flue gas fan from the rotary disc is 0.9t / h.

[0109] After the cleaning process is completed, open the butterfly valve at the inlet of the flue gas hood to 95% to resume normal production.

[0110] Finally, repeat steps (1)-(3) three times in total, and the online cleaning time is about 30 hours.

[0111] Table 4 shows the vibration values ​​of the smoke hood unit shaft and the smoke hood unit casing before and after online cleaning. The vibration values ​​in Table 4 are the lowest values ​​during the test.

[0112] After online descaling, the vibration of the range hood shaft remained at 30-36µm within one month, without any vibration jumps.

[0113] Example 5

[0114] In early 2022, Company A carried out online descaling of a catalytic cracking flue gas unit in another flue gas unit with the same operating process as in Example 1, following the method of Example 1.

[0115] The difference is that during the second cooling process, the flow rate of steam entering the flue gas fan is 1.6 t / h.

[0116] After the cleaning process is completed, open the butterfly valve at the inlet of the flue gas hood to 95% to resume normal production.

[0117] Finally, repeat steps (1)-(3) a total of 4 times, and the online cleaning time is about 34 hours.

[0118] Table 5 shows the vibration values ​​of the smoke hood unit shaft and the smoke hood unit casing before and after online cleaning. The vibration values ​​in Table 5 are the lowest values ​​during the test.

[0119] After online descaling, the vibration of the range hood shaft remained between 28-34µm within one month, without any vibration jumps.

[0120] Example 1 Before online cleaning After online cleaning Vibration of the smoke machine shaft (µm) 65 32 Vibration of the range hood casing (mm / s) 4.1 2.6 Main fan shaft vibration (µm) 55 36 Vibration of the main fan casing (mm / s) 3.8 2.9 Motor housing vibration (mm / s) 2.6 1.5 Speed ​​increaser shaft vibration (µm) 45 23 Vibration of the gearbox housing (mm / s) 2.3 1.1

[0121] Table 2

[0122] Example 2 Before online cleaning After online cleaning Vibration of the smoke machine shaft (µm) 64 30 Vibration of the range hood casing (mm / s) 3.9 2.7 Main fan shaft vibration (µm) 54 35 Vibration of the main fan casing (mm / s) 3.7 2.7 Motor housing vibration (mm / s) 2.7 1.6 Speed ​​increaser shaft vibration (µm) 43 22 Vibration of the gearbox housing (mm / s) 2.3 1.3

[0123] Table 3

[0124] Example 3 Before online cleaning After online cleaning Vibration of the smoke machine shaft (µm) 61 28 Vibration of the range hood casing (mm / s) 3.7 2.5 Main fan shaft vibration (µm) 51 33 Vibration of the main fan casing (mm / s) 3.4 2.4 Motor housing vibration (mm / s) 2.7 1.5 Speed ​​increaser shaft vibration (µm) 41 22 Vibration of the gearbox housing (mm / s) 2.5 1.5

[0125] Table 4

[0126]

[0127]

[0128] Table 5

[0129] Example 5 Before online cleaning After online cleaning Vibration of the smoke machine shaft (µm) 68 35 Vibration of the range hood casing (mm / s) 3.4 3.1 Main fan shaft vibration (µm) 37 32 Vibration of the main fan casing (mm / s) 2.6 2.3 Motor housing vibration (mm / s) 2.4 2.1 Speed ​​increaser shaft vibration (µm) 34 28 Vibration of the gearbox housing (mm / s) 2.6 1.8

[0130] The test data in Tables 1-5 before and after online descaling show that the online descaling method for catalytic cracking flue gas machines in this invention can significantly reduce the vibration of the flue gas machines, effectively extend the continuous operation cycle of the flue gas machines, and reduce the frequency of flue gas machine maintenance.

[0131] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for on-line fouling removal of a catalytic cracking flue, characterized in that, The method comprises: During the operation of the flue gas turbine, flue gas and turbine steam enter the flue gas turbine for scale removal treatment; The scale removal treatment conditions comprise: (1) first programmed temperature reduction: reducing the inlet temperature of the flue gas turbine to 500-570℃; (2) second programmed temperature reduction: continuously reducing the inlet temperature of the flue gas turbine to 275-350℃; (3) third programmed temperature increase: finally increasing the inlet temperature of the flue gas turbine to 580-620℃; (4) repeating steps (1)-(3) until the amplitude of the maximum vibration value of the flue gas turbine is reduced by more than 50%; In step (1), the inlet temperature of the flue gas turbine is reduced at a temperature reduction rate of 50-75℃ / h; in step (2), the inlet temperature of the flue gas turbine is reduced at a temperature reduction rate of 75-100℃ / h; in the second programmed temperature reduction, the flow rate of the turbine steam entering the flue gas turbine is repeatedly adjusted between two steam amounts of At / h and Bt / h within 0.6-1.8t / h, wherein A is 0.6-1 and B=(1.2-3)*A.

2. The method of claim 1, wherein The scale removal treatment conditions comprise: (1) first programmed temperature reduction: reducing the inlet temperature of the flue gas turbine to 530-560℃; (2) second programmed temperature reduction: continuously reducing the inlet temperature of the flue gas turbine to 280-320℃; (3) third programmed temperature increase: finally increasing the inlet temperature of the flue gas turbine to 590-610℃; (4) repeating steps (1)-(3) until the amplitude of the maximum vibration value of the flue gas turbine is reduced by more than 50%.

3. The method of claim 1, wherein In step (1), the inlet temperature of the flue gas turbine is reduced to 530-560℃ at a temperature reduction rate of 50-75℃ / h.

4. The method of claim 1, wherein In step (2), the inlet temperature of the flue gas turbine is reduced to 280-320℃ at a temperature reduction rate of 75-100℃ / h.

5. The method of claim 1, wherein In step (3), the inlet temperature of the flue gas turbine is increased to 580-620℃ at a temperature increase rate of 100-150℃ / h.

6. The method of claim 5, wherein In step (3), the inlet temperature of the flue gas turbine is increased to 590-610℃ at a temperature increase rate of 100-150℃ / h.

7. The method of claim 1, wherein In step (1), the flow rate of the turbine steam entering the flue gas turbine during the first programmed temperature reduction is 0.8-2t / h.

8. The method of claim 7, wherein In step (1), the flow rate of the turbine steam entering the flue gas turbine during the first programmed temperature reduction is 1.2-1.6t / h.

9. The method of claim 1, wherein In step (2), the adjustment time between the two steam amounts during the second programmed temperature reduction is 3-10min.

10. The method of claim 1, wherein The scale removal treatment conditions further comprise: after the amplitude of the maximum vibration value of the flue gas turbine is reduced by more than 50%, the inlet temperature of the flue gas turbine is kept at 580-620℃ for more than 5h.

11. The method of claim 10, wherein After the maximum vibration value of the flue gas turbine is reduced by more than 50%, the inlet temperature of the flue gas turbine is kept at 590-610 ℃ for 8-14 h.

12. The method of claim 1, wherein, In step (3), when the third program is used for temperature rising, the flow rate of the steam entering the flue gas turbine is 0.8-2 t / h.

13. The method of claim 12, wherein, In step (3), when the third program is used for temperature rising, the flow rate of the steam entering the flue gas turbine is 0.9-1.6 t / h.

14. The method of any one of claims 1-13, wherein, During the operation of the flue gas turbine, the temperature of the flue gas is 650-700 ℃; and / or During the operation of the flue gas turbine, the temperature of the steam is 280-340 ℃.

15. The method of claim 1, wherein, During the operation of the flue gas turbine, the rotating speed of the flue gas turbine is 5000-7000 rpm.

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