Method for on-line descaling of rotary molecular sieve calciner and use thereof

Abstract

This invention relates to the field of molecular sieve preparation, and discloses an online descaling method for a rotary molecular sieve calcination furnace during the ion exchange process of NaY molecular sieves, and its application. The method includes: calcining NaY molecular sieve dry powder that has undergone one ion exchange together with catalytic cracking catalyst powder in a calcination furnace, wherein the bulk density of the catalytic cracking catalyst powder is greater than the bulk density of the NaY molecular sieve dry powder, and the abrasion index of the catalytic cracking catalyst powder is below 2.5 wt% / h. This method avoids downtime and manual descaling, enabling online descaling during the calcination process, thereby significantly improving production efficiency and reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve preparation, specifically to an online descaling method for a rotary molecular sieve calcining furnace during the ion exchange process of NaY molecular sieves and its application. Background Technology

[0002] The Na₂O content in the NaY molecular sieve is approximately 14% by weight. After one cation exchange and filtration washing, it is reduced to approximately 5% by weight. The cations that entered the supercages of the NaY molecular sieve after ion exchange are then calcined at high temperature in a high-temperature furnace under a steam atmosphere. After gaining energy, the cations migrate towards the β-cages. The Na₂O in the β-cages... + The ions then migrate towards the supercage, further completing ion exchange and reducing the percentage of Na2O, thereby meeting the performance requirements of the product. For example, when the exchange products of NaY molecular sieves are used as the active component of a catalytic cracking catalyst, in order to ensure the catalytic performance of the prepared catalytic cracking catalyst, the Na2O content must be reduced to below 1.5% by weight.

[0003] However, the Na exchanged during the roasting process + It melts easily at high temperatures and rotates with the powder during the roasting furnace, eventually adhering to the furnace wall to form scale. This not only reduces heat transfer efficiency and increases gas consumption, but also affects product quality and output.

[0004] Currently, the high-temperature calcining furnace for NaY molecular sieve ion exchange needs to be shut down and cooled to room temperature approximately every 15 days. The furnace cylinder is then manually flushed with water to remove scale before being heated back to the required calcination temperature. The total downtime is about two days. This not only affects continuous production and increases labor intensity, but also generates a large amount of wastewater and slag, raising production costs.

[0005] Therefore, how to avoid the process of actively stopping, extinguishing, cooling, and descaling during the roasting process is an important issue that urgently needs to be addressed in the NaY molecular sieve ion exchange process. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem in the existing technology that the calcination furnace needs to be frequently shut down for descaling during the ion exchange calcination process of NaY molecular sieves. This invention provides an online descaling method for a rotary molecular sieve calcination furnace. This method can avoid shutdown and manual descaling, and can achieve online descaling during the calcination process, thereby significantly improving production efficiency and reducing production costs.

[0007] To achieve the above objectives, the present invention provides an online descaling method for a rotary molecular sieve calcining furnace, wherein the method comprises: calcining NaY molecular sieve dry powder that has undergone one ion exchange together with catalytic cracking catalyst powder in a calcining furnace, wherein the bulk density of the catalytic cracking catalyst powder is greater than the bulk density of the NaY molecular sieve dry powder, and the wear index of the catalytic cracking catalyst powder is less than 2.5 wt% / h.

[0008] Preferably, the catalytic cracking catalyst powder accounts for more than 0.03% by weight of the total weight of the NaY molecular sieve dry powder that has undergone one ion exchange.

[0009] Preferably, the catalytic cracking catalyst powder accounts for 0.03-0.05% of the total weight of the NaY molecular sieve dry powder that has undergone one ion exchange.

[0010] More preferably, the catalytic cracking catalyst powder accounts for 0.035-0.05% of the total weight of the NaY molecular sieve dry powder that has undergone one ion exchange.

[0011] Preferably, the bulk density of the catalytic cracking catalyst powder is 700 kg / m³. 3 above.

[0012] Preferably, the bulk density of the catalytic cracking catalyst powder is 700-800 kg / m³. 3 .

[0013] More preferably, the bulk density of the catalytic cracking catalyst powder is 750-800 kg / m³. 3 .

[0014] Preferably, the wear index of the catalytic cracking catalyst powder is 0.8-2.5 wt% / h.

[0015] Preferably, the median particle size of the catalytic cracking catalyst powder is less than 100 μm.

[0016] More preferably, the median particle size of the catalytic cracking catalyst powder is 60-80 μm.

[0017] Preferably, the roasting conditions include: the temperature of the roasted material is above 600°C, and the roasting time is above 2 hours.

[0018] More preferably, the calcination conditions include: the temperature of the calcined material is 600-630℃, and the calcination time is 2-3 hours.

[0019] Preferably, the method further includes: subjecting the roasted material to a second ion exchange, solid-liquid separation, and washing in sequence.

[0020] The second aspect of the present invention provides an application of the online descaling method described in the first aspect of the present invention in the descaling of a rotary molecular sieve calcining furnace.

[0021] The above technical solution involves calcining catalytic cracking catalyst powder together with NaY molecular sieve dry powder after the first ion exchange. Taking advantage of the fact that catalytic cracking catalyst powder has a higher bulk density and stronger wear resistance than NaY molecular sieve dry powder, the catalytic cracking catalyst powder rotates with the calcining furnace cylinder during the calcination process and rubs against the scale on the furnace wall, causing it to fall off.

[0022] The method provided by this invention can remove scale from rotary roasting furnaces online, avoiding downtime for descaling and thus increasing the production efficiency of the roasting process by approximately 15%. Simultaneously, descaling improves the heat transfer efficiency of the roasting furnace, ensuring the quality and stability of the prepared products and reducing production costs.

[0023] In addition, the catalytic cracking catalyst powder calcined together with NaY molecular sieve dry powder does not need to be separated by a separate process. Since the amount of catalytic cracking catalyst added is extremely low (less than 0.05% by weight), and the support of the catalytic cracking catalyst can be ground up by friction in the calcination furnace, only the molecular sieve component is retained. Then, it can be carried out with NaY molecular sieve for a second ion exchange and subsequent preparation process without affecting the quality of the final product. Detailed Implementation

[0024] 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.

[0025] This invention provides an online descaling method for a rotary molecular sieve calcining furnace, wherein the method includes: calcining NaY molecular sieve dry powder that has undergone one ion exchange together with catalytic cracking catalyst powder in a calcining furnace, wherein the bulk density of the catalytic cracking catalyst powder is greater than the bulk density of the NaY molecular sieve dry powder, and the wear index of the catalytic cracking catalyst powder is less than 2.5 wt% / h.

[0026] In this invention, the NaY molecular sieve dry powder that has undergone one ion exchange refers to the NaY molecular sieve that has undergone one cation exchange and filtration washing, then pulped, and the pulped material is dried and pulverized through a flash drying system to form the dry powder.

[0027] In this invention, the catalytic cracking catalyst powder can be any type of catalytic cracking catalyst powder conventional in the art, without any particular limitation. For example, the catalytic cracking catalyst powder can be selected from one or more of DFC-1 catalytic cracking catalyst, CDC catalytic cracking catalyst and CGP-C catalytic cracking catalyst.

[0028] In the prior art, when performing ion exchange on NaY molecular sieves, the NaY molecular sieve dry powder after the above-mentioned first cation exchange is further promoted by calcination to reduce the Na2O content.

[0029] Furthermore, to further meet industrial requirements, a second cation exchange is typically performed after calcination. The product of the second ion exchange is then subjected to solid-liquid separation and washing to obtain the desired product. This is a conventional technique in the field and will not be elaborated upon in this specification.

[0030] In this invention, the NaY molecular sieve dry powder that has undergone one ion exchange is subjected to Na during the calcination process. + It is exchanged out, and because it melts easily in the high-temperature environment of roasting, it will stick to the powder and adhere to the furnace wall together with the powder to form scale, thereby affecting the heat transfer efficiency of the roasting furnace and the product quality.

[0031] The inventors of this invention discovered in extensive production practice that when calcining the NaY molecular sieve dry powder that has undergone one ion exchange in a rotary molecular sieve calcination furnace, by mixing in catalytic cracking catalyst powder, the scale generated in the calcination furnace can be removed during the rotary calcination process without the need for shutdown cleaning, thus completing this invention.

[0032] According to the present invention, the bulk density of the catalytic cracking catalyst powder is greater than that of the NaY molecular sieve dry powder, and the abrasion index of the catalytic cracking catalyst powder is below 2.5 wt% / h. Therefore, when the NaY molecular sieve dry powder, which has undergone one ion exchange, is calcined together with the catalytic cracking catalyst powder in a calcining furnace, the catalytic cracking catalyst powder sinks below the NaY molecular sieve dry powder and comes into contact with the scale on the furnace wall of the rotary molecular sieve calcining furnace, thereby removing the scale from the furnace wall through repeated contact and friction.

[0033] According to the present invention, the smaller the wear index of the catalytic cracking catalyst, the stronger its wear resistance and descaling ability, and the easier it is to remove scale from the furnace wall of the calcining furnace. Preferably, the wear index of the catalytic cracking catalyst powder is 0.8-2.5 wt% / h.

[0034] In this invention, preferably, when the NaY molecular sieve powder that has undergone one ion exchange is calcined together with the catalytic cracking catalyst powder, the catalytic cracking catalyst powder accounts for more than 0.03% by weight of the total weight of the NaY molecular sieve powder that has undergone one ion exchange. More preferably, the catalytic cracking catalyst powder accounts for 0.035-0.05% by weight of the total weight of the NaY molecular sieve powder that has undergone one ion exchange. By limiting the amount of the catalytic cracking catalyst powder within the above range, the descaling effect can be further ensured.

[0035] According to the present invention, the bulk density of the catalytic cracking catalyst powder is greater than that of the NaY molecular sieve dry powder. The bulk density of the catalytic cracking catalyst powder can be 700 kg / m³. 3 The above. Preferably, the bulk density of the catalytic cracking catalyst powder is 700-800 kg / m³. 3 More preferably, the bulk density of the catalytic cracking catalyst powder is 750-800 kg / m³. 3 By limiting the bulk density of the catalytic cracking catalyst powder within the aforementioned range, the efficiency and effectiveness of online descaling can be further improved.

[0036] In this invention, as described above, the catalytic cracking catalyst powder can be a conventional choice in the art. The inventors of this invention have discovered that during the preparation of catalytic cracking catalysts, a large amount of catalytic cracking catalyst powder with particle sizes that do not meet product quality requirements is generated during the molding process. Currently, this type of catalytic cracking catalyst powder with particle sizes that do not meet quality requirements generally requires additional waste treatment. However, in this invention, this type of catalytic cracking catalyst powder with particle sizes that do not meet production requirements can be used, thereby not only eliminating subsequent treatment costs but also allowing it to be recycled into this invention, greatly reducing treatment costs.

[0037] Therefore, in this invention, preferably, the median particle size of the catalytic cracking catalyst powder is less than 100 μm; more preferably, the median particle size of the catalytic cracking catalyst powder is 60-80 μm. This can further improve the descaling effect and significantly reduce the processing cost.

[0038] According to the present invention, the calcination conditions include: a temperature of calcined material above 600°C and a calcination time of 2 hours or more. Preferably, the calcination conditions include: a temperature of calcined material of 600-630°C and a calcination time of 2-3 hours. By calcining under the above conditions, on the one hand, it ensures that the NaY molecular sieve dry powder that has undergone one ion exchange can further complete ion exchange and achieve the calcination effect; on the other hand, under these calcination conditions, the scale deposited in the furnace wall of the calcination furnace can be completely removed. That is to say, online descaling in a rotary calcination furnace can be achieved simultaneously under normal NaY molecular sieve dry powder calcination conditions. This greatly saves on process time, avoids waste of resources, and ensures the quality of the prepared NaY molecular sieve.

[0039] Furthermore, the online descaling method described in this invention eliminates the need for additional separation of the calcined NaY molecular sieve from the fine powder of the catalytic cracking catalyst after calcination. Since the amount of catalytic cracking catalyst added in the method of this invention is extremely low (less than 0.05% by weight), the quality of subsequent products will not be affected even without descaling.

[0040] In addition, NaY molecular sieves, after ion exchange, can be used as the active ingredient in corresponding catalytic cracking catalysts. Since the catalytic cracking catalyst itself contains approximately 70% by weight of support (mainly alumina and silica) and approximately 30% by weight of molecular sieves as the active ingredient, when the catalytic cracking catalyst undergoes a second ion exchange with NaY molecular sieves and the resulting product is used to prepare another catalytic cracking catalyst, the support can be removed during the preparation process via an acid treatment step, while the molecular sieves can be reused as the active ingredient in the next batch of catalytic cracking catalysts. This achieves the recycling of raw materials, reducing production costs and hazardous waste treatment costs.

[0041] The method of the present invention may further include: subjecting the calcined material to a second ion exchange, solid-liquid separation, and washing in sequence. That is, the calcined molecular sieve is subjected to a subsequent conventional molecular sieve ion exchange step together with the catalytic cracking catalyst powder.

[0042] According to the present invention, since the bulk density of the catalytic cracking catalyst powder is greater than that of the NaY molecular sieve, the catalytic cracking catalyst powder can be automatically separated from the NaY molecular sieve in subsequent solid-liquid separation and washing steps.

[0043] The second aspect of the present invention provides the application of the online descaling method described in the first aspect of the present invention in the descaling of a rotary molecular sieve calcining furnace.

[0044] Generally, based on production practice, it is known that the scale formation cycle in the rotary molecular sieve roasting furnace during the roasting of NaY molecular sieve dry powder that has undergone one ion exchange is approximately 15 days. Once the scale has formed to a certain extent, it will affect the heat transfer efficiency of the roasting furnace, causing the roasting temperature of the NaY molecular sieve to fail to reach above 600℃ during the roasting process. This will affect the roasting effect, resulting in insufficient reduction of Na2O in the roasted NaY molecular sieve, remaining above 1.5% by weight. Consequently, the molecular sieve obtained after the second ion exchange will not meet the standard requirements.

[0045] Therefore, according to the second aspect of the present invention, online descaling of the rotary molecular sieve calcining furnace can be performed approximately every 15 days using the method described in the first aspect of the present invention, based on experience. Alternatively, the calcination temperature of the NaY molecular sieve material during calcination can be measured, and if it fails to reach the target temperature (generally above 600°C), the online descaling method described in the present invention can be used.

[0046] Alternatively, the timing of online descaling can be determined based on the performance test results of the final molecular sieve product. That is, when the Na2O content in the molecular sieve obtained by the second ion exchange is still higher than 1.5% by weight, it proves that the degree of ion exchange during the calcination process is insufficient, and the calcination furnace needs to be descaled.

[0047] During application, you can refer to the above content to make appropriate selections, which will not be repeated here.

[0048] The present invention will be described in detail below through examples.

[0049] In the following examples, the bulk density was determined using the method described in the enterprise standard Q / SH 361 928 of the Research Institute of Petroleum Processing, China Petroleum & Chemical Corporation.

[0050] The wear index was determined according to the determination method of the Petrochemical Research Institute of China Petroleum & Chemical Corporation (Sinopec) Q / SH 3360208-2012.

[0051] In the following examples and comparative examples, the rotary molecular sieve calcining furnace used was purchased from Tianhua Chemical Machinery and Automation Research and Design Institute Co., Ltd., model HZL2100-TJT.

[0052] Preparation Example

[0053] Preparation of NaY molecular sieve powder after one ion exchange

[0054] 1) NaY molecular sieve (sodium content is 13.8% by weight, calculated as sodium oxide), lanthanum chloride aqueous solution with a concentration of 120 g / L and ammonium chloride aqueous solution with a concentration of 180 g / L are mixed to obtain a mixture, wherein the weight ratio of NaY molecular sieve, lanthanum chloride and ammonium chloride in the mixture is 1:0.15:0.3.

[0055] 2) After adjusting the pH of the mixture obtained in step 1) to 4 with a 3% by weight hydrochloric acid aqueous solution, heat the mixture to 70°C and stir the reaction at this temperature for 45 min;

[0056] 3) The reaction product obtained in step 2) was subjected to solid-liquid separation and water washing, and then dried at 160℃ for 2 hours to obtain NaY molecular sieve powder with a bulk density of 0.35 kg / m³ after one ion exchange. 3 ).

[0057] Example 1

[0058] The NaY molecular sieve powder obtained from the preparation example after one ion exchange was calcined in a rotary calcining furnace at a core temperature of 625°C.

[0059] After 15 days of normal production, the operators found that the core temperature of the roasted material had dropped to 580°C, and determined that scaling had occurred on the furnace wall.

[0060] Next, 35 kg of catalytic cracking catalyst powder was added to a calcining furnace and mixed with 1 t of NaY molecular sieve dry powder that had undergone one ion exchange, and then calcined. Calcination continued for 2.5 hours in the furnace to obtain the calcined material. The catalytic cracking catalyst powder was CDC catalytic cracking catalyst powder produced by the Changling Branch of Sinopec Catalyst Co., Ltd., with a bulk density of 750 kg / m³. 3 The wear index was 2.2 wt% / h, and the median particle size was 72 μm.

[0061] The roasted material is subjected to a second ion exchange, solid-liquid separation, and washing in sequence.

[0062] The second ion exchange step is as follows:

[0063] 1) The calcined molecular sieve and an ammonium chloride aqueous solution with a concentration of 180 g / L were mixed to obtain a mixed solution, wherein the weight ratio of NaY molecular sieve to ammonium chloride was 1:0.3;

[0064] 2) After adjusting the pH of the mixture obtained in step 1) to 4 with a 3% by weight hydrochloric acid aqueous solution, heat the mixture to 70°C and stir the reaction at this temperature for 45 min;

[0065] 3) The reaction product obtained in step 2) is subjected to solid-liquid separation and water washing to obtain the molecular sieve after the second ion exchange.

[0066] Tests showed that the Na2O content in the molecular sieve after the second ion exchange was 1.5% by weight, which met the quality requirements.

[0067] This method ensures continuous operation of the rotary roasting furnace, excellent descaling effect, and that the final product obtained after roasting meets quality requirements.

[0068] Example 2

[0069] After scale buildup occurred on the furnace wall of the roasting furnace, descaling was performed according to the method in Example 1, with the difference being...

[0070] The catalytic cracking catalyst powder used is CDOS catalytic cracking catalyst powder produced by Changling Branch of Sinopec Catalyst Co., Ltd., with a bulk density of 790 kg / m³. 3 The wear index was 2 wt% / h, and the median particle size was 73 μm.

[0071] Finally, after testing, the Na2O content in the prepared molecular sieve after the second ion exchange was 1.2% by weight, which met the quality requirements.

[0072] Therefore, this method can ensure the continuous operation of the rotary roasting furnace and achieve excellent descaling effect.

[0073] Example 3

[0074] After scale buildup occurred on the furnace wall of the roasting furnace, descaling was performed according to the method in Example 1, with the difference being...

[0075] The catalytic cracking catalyst powder used is CABC catalytic cracking catalyst powder produced by Changling Branch of Sinopec Catalyst Co., Ltd., with a bulk density of 770 kg / m³. 3 The wear index was 1.8 wt% / h, and the median particle size was 74 μm.

[0076] Finally, after testing, the Na2O content in the prepared molecular sieve after the second ion exchange was 1% by weight, which met the quality requirements.

[0077] Therefore, this method can ensure the continuous operation of the rotary roasting furnace and achieve excellent descaling effect.

[0078] Comparative Example 1

[0079] After scale buildup occurred on the furnace wall of the roasting furnace, descaling was performed according to the method in Example 1, with the difference being...

[0080] The catalytic cracking catalyst powder used is CORH catalytic cracking catalyst powder produced by Changling Branch of Sinopec Catalyst Co., Ltd., with a bulk density of 760 kg / m³. 3 The wear index was 2.9 wt% / h, and the median particle size was 66 μm.

[0081] Ultimately, testing revealed that the Na2O content in the molecular sieve after the second ion exchange was 1.7% by weight, which failed to meet the quality requirements and resulted in poor scale removal.

[0082] 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. An online descaling method for a rotary molecular sieve calcining furnace, characterized in that, The method includes: The NaY molecular sieve dry powder that has undergone one ion exchange is calcined together with catalytic cracking catalyst powder in a calcination furnace. The bulk density of the catalytic cracking catalyst powder is greater than that of the NaY molecular sieve dry powder, and the wear index of the catalytic cracking catalyst powder is below 2.5 wt% / h. The catalytic cracking catalyst powder accounts for more than 0.03% by weight of the total weight of the NaY molecular sieve dry powder that has undergone one ion exchange.

2. The method according to claim 1, wherein, The catalytic cracking catalyst powder accounts for 0.03-0.05% of the total weight of the NaY molecular sieve dry powder that has undergone one ion exchange.

3. The method according to claim 1, wherein, The catalytic cracking catalyst powder accounts for 0.035-0.05% of the total weight of the NaY molecular sieve dry powder that has undergone one ion exchange.

4. The method according to any one of claims 1-3, wherein, The bulk density of the catalytic cracking catalyst powder is 700 kg / m³. 3 above.

5. The method according to claim 4, wherein, The bulk density of the catalytic cracking catalyst powder is 700-800 kg / m³. 3 .

6. The method according to claim 5, wherein, The bulk density of the catalytic cracking catalyst powder is 750-800 kg / m³. 3 .

7. The method according to any one of claims 1-3, wherein, The wear index of the catalytic cracking catalyst powder is 0.8-2.5 wt% / h.

8. The method according to any one of claims 1-3, wherein, The median particle size of the catalytic cracking catalyst powder is less than 100 μm.

9. The method according to claim 8, wherein, The median particle size of the catalytic cracking catalyst powder is 60-80 μm.

10. The method according to any one of claims 1-3, wherein, The roasting conditions include: the temperature of the roasted material is above 600℃, and the roasting time is above 2 hours.

11. The method according to claim 10, wherein, The roasting conditions include: the temperature of the roasted material is 600-630℃, and the roasting time is 2-3 hours.

12. The method according to any one of claims 1-3, wherein, The method further includes: subjecting the roasted material to a second ion exchange, solid-liquid separation, and washing in sequence.

13. The application of the online descaling method according to any one of claims 1-12 in descaling of a rotary molecular sieve calcining furnace.