Online scale removing method for catalytic cracking range hood

Abstract

The invention relates to the field of scale removal of a range hood, and discloses an online scale removal method for a catalytic cracking range hood, which comprises the following steps: in the running process of the range hood, flue gas and wheel disc steam enter the range hood for scale removal treatment; the scale removal treatment conditions comprise: (1) first programmed cooling: reducing the inlet temperature of the range hood to 500-570 DEG C; (2) second program cooling: continuously reducing the temperature of the inlet of the range hood by 275-350 DEG C; (3) third temperature programming: finally raising the temperature of the inlet of the range hood to 580-620 DEG C; and (4) repeating the steps (1)-(3) until the highest vibration value of the range hood is reduced by more than 50%, wherein the cooling speed of the first program cooling is different from that of the second program cooling. The method disclosed by the invention has a wide application prospect in a catalytic cracking device in the petrochemical industry, and when the method disclosed by the invention is applied to online scale removal, the shutdown scale removal frequency of the range hood is at least reduced by half, the continuous operation cycle of the range hood can be prolonged, the repair expense per cycle is saved by more than 1 million yuan, and the electric quantity is saved by more than 1000 MW.

Description

Technical Field

[0001] The invention relates to the technical field of chimney fan descaling, and in particular to an online descaling method for a catalytic cracking chimney fan. Background Art

[0002] Catalytic cracking is the main secondary processing technology of petroleum in the domestic petroleum refining industry. It is to crack heavy oil under the action of high temperature and catalyst to convert it into cracked gas, gasoline and diesel. The catalytic smoke machine is the main energy-saving equipment of the device. It uses the high-temperature smoke machine generated by the burning of the regenerator to drive the main fan or generator to operate. Depending on the size of the device, the power of the catalytic smoke machine is between 8000-20000KW. The catalytic regeneration flue gas contains a large amount of catalyst powder. After the three-stage cyclone separation, there is still about 100mg / m 3 The dust in the air vents is 93% of which is micro dust below 10um. The tiny dust adheres to the blades of the range hood and gradually accumulates and thickens, causing the vibration of the range hood to gradually increase and the efficiency to gradually decrease.

[0003] In order to ensure the efficiency and safety of the operation of the chimney fan, the catalytic cracking unit usually adopts a regular shutdown and maintenance plan to solve the problem of chimney fan scaling threatening the safe operation of the equipment. The time required for the chimney fan to be shut down for maintenance is about one week. During this period, the catalytic unit is operated at a reduced capacity, and the spare main fan is started. The processing capacity of the unit decreases, and the energy consumption increases significantly. For example, the chimney fan of a 1.2 million tons / year catalytic cracking unit of a certain enterprise is severely scaled and needs to be cleaned about once every three months. After the shutdown, it was found that the thickness of the scale blocks reached 9mm, and the scale blocks partially fell off, making it impossible to turn the machine, and the blade tops showed obvious signs of wear.

[0004] CN110871199A provides an online descaling method for a chimney fan of a catalytic cracking unit. According to the method, after the chimney fan rotor has been scaled, the main fan-chimney fan unit is switched to a standby unit, the main fan-chimney fan system is shut down, and then the scale is cleaned online, thereby improving the cleaning efficiency and reducing the loss caused by the chimney fan shutdown. The method has achieved good technical effects, but the method has the following defects: (1) During descaling, the chimney fan speed is controlled below 1000 rpm, and the speed is controlled by manually controlling the warm-up valve. The speed control is not accurate, and at low speeds, the vibration of the unit may not be manifested; (2) When the chimney fan is shut down, the device starts the standby unit for operation, which requires reducing the processing volume and the power consumption of the standby unit is high; (3) After online descaling of the chimney fan of the catalytic cracking unit, it is necessary to reheat it and readjust the chimney fan speed, resulting in a long investment in resuming production. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of long maintenance time and high cost during online cleaning of catalytic cracking flue gas turbines in the prior art.

[0006] In order to achieve the above object, 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, the flue gas and the steam from the wheel enter the range hood for descaling;

[0008] Among them, the conditions for descaling treatment include:

[0009] (1) First step of cooling: reduce the inlet temperature of the hood to 500-570°C;

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

[0011] (3) Third program heating: Finally, the inlet temperature of the smoke exhaust fan is raised to 580-620°C;

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

[0013] The cooling speeds of the first cooling program and the second cooling program 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 use of a standby range hood, and can be cleaned online while the range hood is in operation, thus achieving true online cleaning of the range hood. After online cleaning, the vibration of the range hood unit is significantly reduced, effectively extending the continuous operation cycle of the catalytic range hood and reducing the frequency of range hood maintenance.

[0016] (2) The present invention performs online descaling during the operation of the catalytic cracking chimney fan. During the operation, the operating speed of the catalytic cracking chimney fan can be kept at a normal speed by only controlling the conditions for descaling in the chimney fan. There is no risk of long-term low speed and bearing wear.

[0017] (3) After the catalytic cracking flue gas turbine is cleaned by the online cleaning method of the present invention, the flue gas turbine can be directly put into operation without the need for re-preheating and speed-up, and the time required to resume production is short;

[0018] (4) The method of the present invention saves costs and maintains long-term operation, reducing the number of times the range hood is shut down for cleaning by at least half, and can increase the continuous operation cycle of the range hood, saving more than 1 million yuan in repair costs per cycle and more than 1,000 MW of electricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a configuration diagram of a range hood unit. DETAILED DESCRIPTION

[0020] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0021] Figure 1 The figure is a schematic diagram of the configuration of a smoke exhaust unit. The smoke exhaust unit includes a smoke exhaust turbine (short for smoke exhaust), a main fan, a speed increaser and a motor. During operation, the smoke exhaust unit converts the heat and pressure energy in the smoke into mechanical energy. The power output by the smoke exhaust unit is used to drive the main fan, thereby achieving the purpose of energy recovery. Figure 1 The chimney unit in the figure is used as an example to illustrate the method for online descaling of a catalytic cracking chimney, but the method of the present invention is not limited to being applicable to the configuration schematic diagram of the chimney unit.

[0022] In the present invention, the speed of the chimney fan is kept unchanged during normal operation of the chimney fan unit during the descaling process, and the chimney fan is directly put into operation after online descaling without the need for re-preheating. Based on this, the present invention provides a method for online descaling of a catalytic cracking chimney fan, which comprises:

[0023] During the operation of the range hood, the flue gas and the steam from the wheel enter the range hood for descaling;

[0024] Among them, the conditions for descaling treatment include:

[0025] (1) First step of cooling: reduce the inlet temperature of the hood to 500-570°C;

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

[0027] (3) Third program heating: Finally, the inlet temperature of the smoke exhaust fan is raised to 580-620°C;

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

[0029] The cooling speeds of the first cooling program and the second cooling program are different.

[0030] In the present invention, during the operation of the range hood, not only can the range hood not be stopped but can be kept in continuous operation without switching the main fan, and the range hood unit does not need to be reduced in volume or other operations that may affect the normal operation of the catalytic range hood, but the range hood blades can be cleaned by adjusting the flue gas and the disc steam. At the same time, controlling the cleaning conditions can better clean the range hood, and ensure that after online cleaning, all loose scale blocks fall off, so that the range hood can run smoothly after cleaning, and the working capacity of the range hood can be further improved.

[0031] The range hood vibration value described in the present invention includes the range hood shaft vibration value and / or the range hood housing vibration value, and the range hood maximum vibration value refers to the maximum vibration value between the range hood shaft vibration value and the range hood housing vibration value.

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

[0033] (1) First step of cooling: reduce the inlet temperature of the range hood to 530-560°C;

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

[0035] (3) Third program heating: Finally, the inlet temperature of the smoke exhaust fan is raised to 590-610°C;

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

[0037] The above implementation method can effectively extend the continuous operation period of the catalytic cracking flue gas turbine and reduce the frequency of maintenance of the flue gas turbine.

[0038] According to the present invention, in some embodiments, in step (1), the inlet temperature of the range hood is reduced to 500-570° C., preferably to 530-560° C., at a cooling rate of 50-75° C. / h. The above embodiment can better increase the efficiency and effect of descaling.

[0039] According to the present invention, as long as the purpose of the present invention can be achieved, there is no special limitation on how to achieve the first program cooling method. For example, in step (1), the opening of the butterfly valve at the inlet of the range hood is reduced from 95-100% at a rate of (8-12)% / 10min, so that the inlet temperature of the range hood is reduced at a cooling rate of 50-75°C / h to 500-570°C (for example, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 570°C or 580°C), preferably to 530-560°C. By adopting the above-mentioned embodiment, the cooling rate and the cooling end point of the first program cooling are achieved by controlling the butterfly valve to reduce the amount of smoke entering the range hood, and at the same time, the scale removal can be better achieved.

[0040] According to the present invention, the opening of the butterfly valve at the range hood inlet is 95-100%, which means that the butterfly valve is in a fully open state, and it can be understood that when the temperature is lowered to the required temperature of 500-570°C, preferably to 530-560°C during the first cooling program, the first cooling program step is stopped and the second cooling program step is started.

[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. By adopting the above-mentioned embodiment, the descaling effect can be better achieved, the number of times the range hood is stopped for descaling can be reduced by at least half, and the continuous operation cycle of the range hood can be increased.

[0042] According to the present invention, as long as the purpose of the present invention can be achieved, there is no special limitation on how to achieve the second program cooling method. For example, in step (2), the opening of the butterfly valve at the inlet of the range hood continues to be reduced at a rate of (8-12)% / 10min, so that the inlet temperature of the range hood is reduced to 275-350°C (for example, 275°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C or 350°C) at a cooling rate of 75-100°C / h, preferably to 280-320°C. By adopting the above-mentioned embodiment, the cooling rate and the cooling end point of the second program cooling are achieved by controlling the butterfly valve to reduce the amount of smoke entering the range hood, and the scale removal treatment of the range hood can be better achieved.

[0043] According to the present invention, in some embodiments, the heating rate during the third program heating is 100-150°C / h. The above-mentioned embodiment can better achieve the effect of online descaling and improve the efficiency of descaling. At the same time, the inlet temperature of the range hood after descaling exceeds 500°C, which is equivalent to the preheating state, and can be directly put into operation without re-preheating.

[0044] According to the present invention, as long as the purpose of the present invention can be achieved, there is no special limitation on how to achieve the third programmed temperature increase. For example, in step (3), the opening of 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 increased to 580-620°C (for example, 580°C, 590°C, 600°C, 610°C or 620°C) at a rate of 100-150°C / h, preferably to 590-610°C. By adopting the above embodiment, by controlling the butterfly valve to increase the amount of smoke entering the range hood, the temperature increase rate and the temperature increase end point during the third programmed temperature increase can be achieved, and at the same time, the scale removal treatment of the range hood can be better achieved.

[0045] According to the present invention, in some embodiments, in step (1), when the first program is cooled, the flow rate of the disc steam entering the range hood is 0.8-2 t / h (for example, 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. The above embodiment can better achieve the descaling treatment of the range hood.

[0046] According to the present invention, in some embodiments, in step (2), when the second program is cooled, the flow rate of the disc steam entering the range hood 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 disc steam entering the range hood is repeatedly adjusted between different flow rates within the range of 0.6-1.8 t / h, which means that in step (2), when the second program is cooled, the disc steam is repeatedly circulated in the range hood at at least two different flow rates and at a certain time interval. In some preferred embodiments, in step (2), when the second program is cooled, the interval between different flow rates is 3-10 minutes, such as 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes. The above-mentioned embodiment can better change the work done by the range hood unit, and with the change of the inlet temperature, can better ensure the effect of online descaling.

[0048] According to the present invention, as long as the purpose of the present invention can be achieved, there is no special restriction on the number of groups of different flow rates during the second program cooling. In some preferred embodiments, in step (2), during the second program cooling, the flow rate of the disc steam entering the range hood is repeatedly adjusted at two steam rates of At / h and Bt / h, where A is 0.6-1 and B = (1.2-3)*A. The above-mentioned embodiment can further ensure the effect of online descaling.

[0049] In the present invention, there is no particular limitation on whether At / h or Bt / h is used first before the second program cooling begins, but At / h is preferably used first.

[0050] According to the present invention, in some embodiments, the descaling treatment conditions also 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 the present invention, in some preferred embodiments, after the maximum vibration value of the range hood drops by more than 50%, the inlet temperature of the range hood remains at 590-610°C for 8-14 hours. The above embodiment can further ensure that all loose scale blocks fall off, and better achieve scale removal.

[0052] According to the present invention, in some embodiments, in step (3), when the third program temperature is raised, the flow rate of the disc steam entering the range hood is 0.8-2 t / h, preferably 0.9-1.6 t / h. The above embodiment can further ensure the effect of online descaling.

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

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

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

[0056] As mentioned above, in the online descaling process of the prior art, the main fan needs to be cut out of the system and the speed of the range hood needs to be reduced. Since the speed reduction of the range hood can only be achieved by closing the butterfly valve of the range hood, it is difficult to control accurately, and there is a risk of insufficient oil film stiffness due to too low speed; and the vibration during low speed operation cannot represent the vibration at normal speed, and the judgment of the descaling effect is not accurate. If the judgment is made after the speed is increased, it will take 4 to 6 hours of heating and speed increase time. According to the present invention, the range hood maintains normal operation during operation, and the speed of the range hood also operates normally. The speed of the range hood is the normal speed during the actual operation of the range hood unit. The present invention has no special restrictions on this. In some embodiments, during the operation of the range hood, the speed of the range hood is 5000-7000rpm. The above embodiment refers to the invention that the speed of the range hood is kept at a normal speed during descaling. This embodiment does not have the risk of long-term low speed and bearing wear, and at its normal operating speed, the real-time changes of the range hood can be monitored in real time. When the online descaling is completed, there is no need to increase the speed to judge the effect, and no need to increase the speed again when recovering.

[0057] The present invention will be described in detail by way of examples. In the following examples, when performing online descaling of a catalytic cracking chimney machine, the SG8000 unit state monitoring system is used to measure the vibration of the front and rear shafts of the chimney machine, and the vibration spot inspection instrument is used to measure the vibration of the unit shell on site.

[0058] Example 1

[0059] At the beginning of 2022, Company A carried out online descaling of the catalytic cracking flue gas turbine. The method included:

[0060] During the operation of the smoke machine, the flue gas (temperature of 680°C and flow rate of 130,000 standard cubic meters per hour) and the disc steam (temperature of 305°C) enter the smoke machine for descaling treatment, and the speed of the smoke machine is 5785rpm;

[0061] Among them, the conditions for descaling treatment include:

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

[0063] During the first program cooling period, the flow rate of the disc steam entering the hood is 0.9t / h;

[0064] (2) Second cooling procedure: The opening of the butterfly valve at the inlet of the range hood continues to be reduced at a rate of 10% / 10min, so that the inlet temperature of the range hood is reduced to 300°C at a cooling rate of about 100°C / h;

[0065] During the second program cooling period, the flow rate of the disc steam entering the smoke exhaust fan is repeatedly adjusted at two flow rates of 0.6t / h and 1.2t / h at an interval of 5 minutes;

[0066] (3) Third program heating: the butterfly valve at the inlet of the range hood is opened at a rate of 20% / 5 min, so that the inlet temperature of the range hood is raised to 600°C at a rate of about 120°C / h;

[0067] During the third program heating period, the flow rate of the disc steam entering the smoke exhaust fan is 0.9t / h;

[0068] (4) Repeat steps (1) to (3) until the maximum vibration value of the range hood drops by more than 50%, and the inlet temperature of the range hood remains at 600°C for 12 hours.

[0069] After the descaling treatment is completed, directly open the butterfly valve at the smoke machine inlet to 95% and resume normal production.

[0070] Finally, steps (1) to (3) were repeated once, and the online cleaning time was about 24 hours.

[0071] The vibration values ​​of the shaft and shell of the range hood unit before and after online descaling are shown in Table 1. The vibration values ​​in Table 1 are the lowest values ​​during the test.

[0072] Through the spectrum analysis of the shaft vibration of the range hood unit, it was found that: before online cleaning, the vibration value of the range hood was 65um and vibration jump occurred. The spectrum analysis showed slight clipping and 1 / 2 frequency component, indicating that the range hood blades were severely scaled and had slight friction with the machine body. After online cleaning, the vibration of the range hood was stable at around 39um, and the spectrum analysis result was the industrial frequency, without 1 / 2 frequency and clipping, indicating that the friction was eliminated and the cleaning effect was obvious.

[0073] After the online descaling treatment, the range hood shaft vibration of the unit was maintained at 38-39um within two months, and no vibration jump occurred.

[0074] Under the same load of the main fan, the average motor power of the range hood before online cleaning was 531KW, and the double valve opening was 6.5%. The average motor power of the range hood one month after online cleaning was 503KW, and the double valve opening was 1.7%. The smaller double valve opening indicates that the cleaning effect is obvious, the gap between the range hood blades is increased, and the amount of flue gas entering the range hood increases. After online cleaning, the workmanship of the range hood is improved.

[0075] After online descaling of the catalytic cracking flue gas turbine, the unit saved 550,000 yuan in equipment maintenance and repair costs; saved 580,800KW≈348,000 yuan in industrial electricity costs; shortened low-load operation time, and the device processed 4,000 tons more raw materials, reducing pressure on production and operation.

[0076] Example 2

[0077] In mid-2022, Company B carried out online descaling of the catalytic cracking flue gas turbine. The method included:

[0078] During the operation of the smoke machine, the flue gas (temperature of 670°C and flow rate of 127,000 standard cubic meters per hour) and the disc steam (temperature of 302°C) enter the smoke machine for descaling treatment, and the speed of the smoke machine is 5787rpm;

[0079] Among them, the conditions for descaling treatment include:

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

[0081] During the first program cooling period, the flow rate of the disc steam entering the hood is 1.6t / h;

[0082] (2) Second cooling procedure: The opening of the butterfly valve at the inlet of the range hood continues to be reduced at a rate of 8% / 10 min, so that the inlet temperature of the range hood is reduced to 280°C at a cooling rate of about 90°C / h;

[0083] During the second program cooling period, the flow rate of the disc steam entering the smoke exhaust fan is repeatedly adjusted at two flow rates of 1t / h and 1.5t / h at an interval of 5 minutes;

[0084] (3) Third program heating: The butterfly valve at the inlet of the range hood is opened at a rate of 15% / 5 min, so that the inlet temperature of the range hood is raised to 610°C at a rate of about 130°C / h;

[0085] During the third program heating period, the flow rate of the disc steam entering the smoke exhaust fan is 1.6t / h;

[0086] (4) Repeat steps (1) to (3) until the maximum vibration value of the range hood drops by more than 50%, and the inlet temperature of the range hood remains at 610°C for 8 hours.

[0087] After the descaling treatment is completed, directly open the butterfly valve at the smoke machine inlet to 95% and resume normal production.

[0088] Finally, steps (1) to (3) were repeated twice, and the online cleaning time was about 26 h.

[0089] The vibration values ​​of the shaft vibration and the housing vibration of the range hood unit before and after online descaling are shown in Table 2. The vibration values ​​in Table 2 are the lowest values ​​during the test.

[0090] After the online descaling treatment, the range hood shaft vibration of the unit was maintained at 34-39um within two months, and no vibration jump occurred.

[0091] Example 3

[0092] In mid-2022, Company C carried out online descaling of the catalytic cracking flue gas turbine. The method included:

[0093] During the operation of the smoke machine, the flue gas (temperature of 675°C and flow rate of 125,000 standard cubic meters per hour) and the disc steam (temperature of 310°C) enter the smoke machine for descaling treatment, and the speed of the smoke machine is 5787rpm;

[0094] Among them, the conditions for descaling treatment include:

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

[0096] During the first program cooling period, the flow rate of the disc steam entering the smoke exhaust fan is 1.0t / h;

[0097] (2) Second cooling procedure: The opening of the butterfly valve at the inlet of the range hood continues to be reduced at a rate of 12% / 10 min, so that the inlet temperature of the range hood is reduced to 320°C at a cooling rate of about 90°C / h;

[0098] During the second program cooling period, the flow rate of the disc steam entering the smoke exhaust fan is repeatedly adjusted at two flow rates of 0.6t / h and 1.8t / h at an interval of 5 minutes;

[0099] (3) Third program heating: The butterfly valve at the inlet of the range hood is opened at a rate of 25% / 5 min, so that the inlet temperature of the range hood is raised to 590°C at a rate of about 130°C / h;

[0100] During the third program heating period, the flow rate of the disc steam entering the smoke exhaust fan is 1.2t / h;

[0101] (4) Repeat steps (1) to (3) until the maximum vibration value of the range hood drops by more than 50%, and the inlet temperature of the range hood remains at 590°C for 14 hours.

[0102] Finally, steps (1) to (3) were repeated once, and the online cleaning time was about 18 h.

[0103] After the descaling treatment is completed, directly open the butterfly valve at the smoke machine inlet to 95% and resume normal production.

[0104] The vibration values ​​of the shaft and shell of the range hood unit before and after online descaling are shown in Table 3. The vibration values ​​in Table 3 are the lowest values ​​during the test.

[0105] After the online descaling treatment, the range hood shaft vibration of the unit was maintained at 36-41um within two months, and no vibration jump occurred.

[0106] Example 4

[0107] At the beginning of 2022, Company A carried out online descaling of the catalytic cracking chimney in another chimney unit with the same operating process as that of Example 1 according to the method of Example 1;

[0108] The difference is: in the first cooling program: the opening of the butterfly valve at the inlet of the range hood is closed from 95% at a speed of 30% / 10min, so that the inlet temperature of the range hood is cooled to 550℃ at a cooling rate of about 80℃ / h; during the first cooling program, the flow rate of the disc steam entering the range hood is 0.9t / h.

[0109] After the descaling treatment is completed, directly open the butterfly valve at the smoke machine inlet to 95% and resume normal production.

[0110] Finally, steps (1)-(3) were repeated three times, and the online cleaning time was about 30 h.

[0111] The vibration values ​​of the shaft and shell of the range hood unit before and after online descaling are shown in Table 4. The vibration values ​​in Table 4 are the lowest values ​​during the test.

[0112] After the online descaling treatment, the range hood shaft vibration of the unit was maintained at 30-36um within one month, and no vibration jump occurred.

[0113] Example 5

[0114] At the beginning of 2022, Company A carried out online descaling of the catalytic cracking chimney in another chimney unit with the same operating process as that of Example 1 according to the method of Example 1;

[0115] The difference is that during the second cooling program, the flow rate of the disc steam entering the range hood is 1.6t / h.

[0116] After the descaling treatment is completed, directly open the butterfly valve at the smoke machine inlet to 95% and resume normal production.

[0117] Finally, steps (1)-(3) were repeated 4 times, and the online cleaning time was about 34 hours.

[0118] The vibration values ​​of the shaft and shell of the range hood unit before and after online descaling are shown in Table 5. The vibration values ​​in Table 5 are the lowest values ​​during the test.

[0119] After the online descaling treatment, the range hood shaft vibration of the unit was maintained at 28-34um within one month, and no vibration jump occurred.

[0120] Example 1 Before online descaling After online descaling Fan shaft vibration (um) 65 32 Range hood housing vibration (mm / s) 4.1 2.6 Main fan shaft vibration (um) 55 36 Main fan housing vibration (mm / s) 3.8 2.9 Motor housing vibration (mm / s) 2.6 1.5 Speed ​​increaser shaft vibration (um) 45 23 Speed ​​increaser housing vibration (mm / s) 2.3 1.1

[0121] Table 2

[0122] Example 2 Before online descaling After online descaling Fan shaft vibration (um) 64 30 Vibration of hood housing (mm / s) 3.9 2.7 Main fan shaft vibration (um) 54 35 Main fan housing vibration (mm / s) 3.7 2.7 Motor housing vibration (mm / s) 2.7 1.6 Speed ​​increaser shaft vibration (um) 43 22 Speed ​​increaser housing vibration (mm / s) 2.3 1.3

[0123] Table 3

[0124] Example 3 Before online descaling After online descaling Fan shaft vibration (um) 61 28 Range hood housing vibration (mm / s) 3.7 2.5 Main fan shaft vibration (um) 51 33 Main fan housing vibration (mm / s) 3.4 2.4 Motor housing vibration (mm / s) 2.7 1.5 Speed ​​increaser shaft vibration (um) 41 22 Speed ​​increaser housing vibration (mm / s) 2.5 1.5

[0125] Table 4

[0126]

[0127]

[0128] Table 5

[0129] Example 5 Before online descaling After online descaling Fan shaft vibration (um) 68 35 Range hood housing vibration (mm / s) 3.4 3.1 Main fan shaft vibration (um) 37 32 Main fan housing vibration (mm / s) 2.6 2.3 Motor housing vibration (mm / s) 2.4 2.1 Speed ​​increaser shaft vibration (um) 34 28 Speed ​​increaser housing vibration (mm / s) 2.6 1.8

[0130] It can be obtained from the test data before and after online cleaning in Tables 1-5 that the online cleaning method for catalytic cracking chimney fan in the present invention can significantly reduce the vibration of the chimney fan, effectively extend the continuous operation cycle of the chimney fan, and reduce the frequency of chimney fan maintenance.

[0131] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for online descaling of a catalytic cracking flue gas turbine, characterized in that: The method includes: During the operation of the range hood, the flue gas and the steam from the wheel enter the range hood for descaling; Among them, the conditions for descaling treatment include: (1) First step of cooling: reduce the inlet temperature of the hood to 500-570°C; (2) Second cooling process: Continue to reduce the inlet temperature of the range hood by 275-350°C; (3) Third program heating: Finally, the inlet temperature of the smoke exhaust fan is raised to 580-620°C; (4) Repeat steps (1) to (3) until the maximum vibration value of the range hood decreases by more than 50%; The cooling speeds of the first cooling program and the second cooling program are different.

2. The method according to claim 1, wherein: The conditions for descaling treatment include: (1) First step of cooling: reduce the inlet temperature of the range hood to 530-560°C; (2) Second cooling process: Continue to reduce the inlet temperature of the range hood by 280-320°C; (3) Third program heating: Finally, the inlet temperature of the smoke exhaust fan is raised to 590-610°C; (4) Repeat steps (1) to (3) until the maximum vibration value of the range hood decreases by more than 50%.

3. The method according to claim 1 or 2, wherein: In step (1), the inlet temperature of the smoke exhaust fan is reduced to 500-570°C, preferably to 530-560°C, at a cooling rate of 50-75°C / h.

4. The method according to any one of claims 1 to 3, wherein: In step (2), the inlet temperature of the smoke exhaust fan is reduced to 275-350°C, preferably to 280-320°C, at a cooling rate of 75-100°C / h.

5. The method according to any one of claims 1 to 4, wherein: In step (3), the inlet temperature of the smoke exhaust fan is increased to 580-620°C, preferably to 590-610°C, at a heating rate of 100-150°C / h.

6. The method according to any one of claims 1 to 5, wherein: In step (1), during the first temperature reduction process, the flow rate of the disc steam entering the range hood is 0.8-2 t / h, preferably 1.2-1.6 t / h.

7. The method according to any one of claims 1 to 6, wherein: In step (2), during the second program cooling, the flow rate of the disc steam entering the range hood is repeatedly adjusted between different flow rates within the range of 0.6-1.8 t / h, and preferably the adjustment time between different flow rates is 3-10 min.

8. The method according to claim 7, wherein: In step (2), when the second program is cooled, the flow rate of the disc steam entering the range hood is repeatedly adjusted between two steam volumes of At / h and Bt / h, where A is 0.6-1 and B=(1.2-3)*A.

9. The method according to any one of claims 1 to 8, wherein: The conditions for the descaling treatment also include: after the maximum vibration value of the range hood drops by more than 50%, the inlet temperature of the range hood stays at 580-620°C for more than 5 hours, preferably at 590-610°C for 8-14 hours.

10. The method according to any one of claims 1 to 9, wherein: In step (3), when the temperature is raised in the third program, the flow rate of the disc steam entering the smoke exhaust fan is 0.8-2 t / h, preferably 0.9-1.6 t / h.

11. The method according to any one of claims 1 to 10, wherein: During the operation of the smoke exhaust fan, the temperature of the smoke is 650-700℃; and / or During the operation of the range hood, the temperature of the disc steam is 280-340℃.

12. The method according to any one of claims 1 to 11, wherein: When the range hood is in operation, its speed is 5000-7000rpm.

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