Alkali glue process for improving reaction efficiency of cracking kettle

Abstract

The invention discloses an alkali gel process for improving the reaction efficiency of a cracking kettle. The alkali gel process comprises the following steps: adding hydrolysate and a potassium hydroxide solution into the cracking kettle at normal temperature and normal pressure, and stirring; under a stirring state, adding the hydrolysate and the potassium hydroxide solution for the second time; after stirring, vacuumizing operation is performed, and the vacuum degree is kept to be-84 KPa to-87 KPa; dehydrating to obtain alkali glue; and heating the cracking kettle to 130-140 DEG C, and adding the hydrolysate and a catalyst into the cracking kettle to carry out cracking reaction. Compared with the prior art, part of the hydrolysate reacts with potassium hydroxide to prepare the alkali gel, and then the hydrolysate and the catalyst are added for the cracking reaction of the hydrolysate. The alkali glue can increase the reaction contact area of hydrolysate and improve the heat transfer effect, so that the cracking reaction in the cracking kettle is softer and more sufficient. The cracking reaction adopting the alkali gel process is long in operation period, large in treatment capacity and small in slag discharge amount, the use amount of steam is reduced, and the obtained product is high in index.

Description

Technical Field

[0001] This invention relates to the field of oligomeric siloxane pyrolysis technology, and more particularly to an alkaline gel process for improving the reaction efficiency of the pyrolysis reactor. Background Technology

[0002] Organosilicon products are generally produced from the intermediate DMC (dimethylsiloxane mixed cyclic molecule), and the quality requirements for DMC are becoming increasingly stringent. With the development of the organosilicon industry, the cracking processes for oligomeric siloxanes (hereinafter referred to as hydrolysates) are also becoming more diverse. At the same time, long production cycles, low energy consumption, and high quality are the common goals pursued by everyone.

[0003] The hydrolysate is mainly a linear Si-O-Si mixture with high viscosity, making it difficult to control the reaction rate with the catalyst. The catalyst consumed varies depending on the size of the reactor, and the reaction cycle is short with high energy consumption and frequent start-up and shutdown.

[0004] Domestically and internationally, the main methods for hydrolysate cracking are dry cracking and solvent oil cracking. Most domestic manufacturers use solvent oil cracking, which involves feeding hydrolysate and octadecyl alcohol into a cracking reactor in a specific ratio, adding a certain amount of potassium hydroxide catalyst, and then carrying out a vacuum high-temperature reaction in the reactor. This method involves the addition of an organic catalyst, which affects the quality of the subsequent products. At the same time, this reactor requires a large volume, resulting in the waste of steam and equipment, and the discharged waste residue cannot be reused, resulting in material waste. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an alkaline gel process for improving the reaction efficiency of a pyrolysis reactor. First, a portion of the hydrolysate is reacted with potassium hydroxide to form an alkaline gel. Then, the hydrolysate and a catalyst are added to carry out the pyrolysis reaction of the hydrolysate. The alkaline gel can make the pyrolysis reaction in the pyrolysis reactor more stable and complete, while reducing material loss and the amount of potassium hydroxide used.

[0006] To achieve this technical objective, the present invention adopts the following solution: An alkaline gel process for improving the reaction efficiency of a pyrolysis reactor includes the following steps: S1. At room temperature and pressure, add hydrolysate to the pyrolysis vessel; S2. Add potassium hydroxide solution and stir; S3. Under stirring, add the hydrolysate and potassium hydroxide solution a second time; S4. After stirring, perform a vacuum operation, maintaining a vacuum level of -84~-87KPa; S5. Dehydration yields alkaline gum; S6. The pyrolysis reactor is heated to 130~140℃, and hydrolysate and catalyst are added to the pyrolysis reactor to carry out the pyrolysis reaction.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides an alkaline gel process to improve the reaction efficiency of a pyrolysis reactor. First, a portion of the hydrolysate is reacted with potassium hydroxide to form an alkaline gel. Then, the hydrolysate and a catalyst are added to carry out the pyrolysis reaction of the hydrolysate. The alkaline gel increases the reaction contact area of ​​the hydrolysate, improving heat transfer and making the pyrolysis reaction in the reactor more gentle and complete, thus improving the reaction efficiency within the reactor. The alkaline gel is made using potassium hydroxide, which is the same catalyst used in the subsequent pyrolysis reaction, eliminating the introduction of other impurities. The pyrolysis reaction using the alkaline gel process has a long operating cycle, large throughput, small slag discharge, reduced steam consumption, and high product quality.

[0008] Furthermore, the mass concentration of the potassium hydroxide solution in step S2 is 46%~49%.

[0009] Furthermore, the mass ratio of the hydrolysate in step S1 to the potassium hydroxide solution in step S2 is 1000:70~80.

[0010] Furthermore, the mass concentration of the potassium hydroxide solution in step S3 is 40%~44%.

[0011] Furthermore, the mass ratio of the hydrolysate to the potassium hydroxide solution in step S3 is 1000:35~40.

[0012] Furthermore, the mass ratio of the hydrolysate in step S1 to that in step S3 is 1:1.

[0013] Furthermore, the hydrolysate and potassium hydroxide solution in step S3 are added in three separate batches, with the amount added increasing each time and the stirring rate increasing each time.

[0014] Further, the hydrolysate and potassium hydroxide solution in step S3 are added in three separate steps: First, the hydrolysate and a 40-44% potassium hydroxide solution are added, with a mass ratio of 800-1200:25-35, over a time of 18-22 minutes, with a stirring speed of 22-27 Hz; second, the hydrolysate and a 40-44% potassium hydroxide solution are added, with a mass ratio of 800-1200:45-55, over a time of 35-45 minutes, with a stirring speed of 32-37 Hz; third, the hydrolysate and a 40-44% potassium hydroxide solution are added, with a mass ratio of 1800-2200:65-75, over a time of 45-55 minutes, with a stirring speed of 38-42 Hz.

[0015] Furthermore, in step S6, after the pyrolysis reactor is heated to 130~140℃, the flow rate of the hydrolysate is controlled at 2~3.5 tons / hour, and a catalyst is added at a mass ratio of 1000:0.3.

[0016] Furthermore, the catalyst in step S6 is potassium hydroxide. Detailed Implementation

[0017] To fully understand the purpose, features and effects of the present invention, the present invention will be described in detail through the following specific embodiments, but the present invention is not limited thereto.

[0018] This invention provides an alkaline gel process for improving the reaction efficiency of a pyrolysis reactor, comprising the following steps: S1. At room temperature and pressure, add hydrolysate to the pyrolysis vessel.

[0019] S2. Add a potassium hydroxide solution with a mass concentration of 46%~49% and stir.

[0020] The mass ratio of the hydrolysate in step S1 to the potassium hydroxide solution in step S2 is 1000:70~80.

[0021] S3. Under stirring, add the hydrolysate and a potassium hydroxide solution with a mass concentration of 40%~44% for the second time; the mass ratio of the hydrolysate added in the second time to the hydrolysate added in step S1 is 1:1.

[0022] The mass ratio of the hydrolysate to the potassium hydroxide solution added in the second addition is 1000:35~40.

[0023] The hydrolysate and potassium hydroxide solution are added in three stages, with the amount added increasing each time and the stirring rate increasing with each stage. Specifically: First, the hydrolysate and a 40-44% potassium hydroxide solution are added, with a mass ratio of 800-1200:25-35, over a time of 18-22 minutes, at a stirring rate of 22-27 Hz. Second, the hydrolysate and potassium hydroxide solution are added again, with a mass ratio of 800-1200:45-55, over a time of 35-45 minutes, at a stirring rate of 32-37 Hz. Third, the hydrolysate and potassium hydroxide solution are added again, with a mass ratio of 1800-2200:65-75, over a time of 45-55 minutes, at a stirring rate of 38-42 Hz.

[0024] S4. After stirring, perform a vacuum operation, maintaining a vacuum level of -84~-87KPa.

[0025] S5. Dehydrate to obtain alkaline gum.

[0026] S6. The pyrolysis reactor is heated to 130~140℃, and hydrolysate and catalyst are added to the pyrolysis reactor to carry out the pyrolysis reaction.

[0027] After the pyrolysis reactor is heated to 130~140℃, the flow rate of the hydrolysate is controlled at 2~3.5 tons / hour, and a catalyst, potassium hydroxide, is added at a mass ratio of 1000:0.3. Example 1

[0028] S1. At room temperature and pressure, add 4 tons of hydrolysate to the pyrolysis reactor; S2. Add 300 kg of potassium hydroxide solution with a mass concentration of 48% and stir. S3. Under stirring, add the hydrolysate and potassium hydroxide solution a second time. The specific operation is as follows: The hydrolysate and potassium hydroxide solution were added in three stages. The first stage involved adding 1 ton of hydrolysate along with 30 kg of a 42% potassium hydroxide solution over 20 minutes, with a stirring speed of 25 Hz. The second stage involved adding 1 ton of hydrolysate along with 50 kg of a 42% potassium hydroxide solution over 40 minutes, with a stirring speed of 35 Hz. The third stage involved adding 2 tons of hydrolysate along with 70 kg of a 42% potassium hydroxide solution over 50 minutes, with a stirring speed of 40 Hz. S4. After stirring, perform a vacuum operation, maintaining a vacuum level of -85 kPa. S5. After vacuuming, dehydrate for 30 minutes to obtain alkaline gel; S6. After the pyrolysis reactor is heated to 130~140℃, normal feeding and discharging begins. Open the hydrolysate feed regulating valve to control the flow rate. The hydrolysate flow rate is 3.5 tons / hour. At the same time, open the three-way valve for potassium hydroxide feed and add 48% potassium hydroxide solution at a mass ratio of 1000:0.3. The hydrolysate then undergoes a pyrolysis reaction. Example 2

[0029] S1. At room temperature and pressure, add 4 tons of hydrolysate to the pyrolysis reactor; S2. Add 280 kg of potassium hydroxide solution with a mass concentration of 46% and stir. S3. Under stirring, add the hydrolysate and potassium hydroxide solution a second time. The specific operation is as follows: The hydrolysate and potassium hydroxide solution were added in three stages. The first stage involved adding 0.8 tons of hydrolysate along with 25 kg of a 40% potassium hydroxide solution over 20 minutes, with a stirring speed of 22 Hz. The second stage involved adding 1 ton of hydrolysate along with 45 kg of a 42% potassium hydroxide solution over 35 minutes, with a stirring speed of 35 Hz. The third stage involved adding 2.2 tons of hydrolysate along with 70 kg of a 42% potassium hydroxide solution over 50 minutes, with a stirring speed of 40 Hz. S4. After stirring, perform a vacuum operation, maintaining a vacuum level of -84KPa; S5. After vacuuming, dehydrate for 30 minutes to obtain alkaline gel; S6. After the pyrolysis reactor is heated to 130~140℃, normal feeding and discharging begins. Open the hydrolysate feed regulating valve to control the flow rate. The hydrolysate flow rate is 3.0 tons / hour. At the same time, open the three-way valve for potassium hydroxide feed and add 48% potassium hydroxide solution at a mass ratio of 1000:0.3. The hydrolysate then undergoes a pyrolysis reaction. Example 3

[0030] S1. At room temperature and pressure, add 4 tons of hydrolysate to the pyrolysis reactor; S2. Add 320 kg of potassium hydroxide solution with a mass concentration of 49% and stir. S3. Under stirring, add the hydrolysate and potassium hydroxide solution a second time. The specific operation is as follows: The hydrolysate and potassium hydroxide solution were added in three stages. The first stage involved adding 1 ton of hydrolysate along with 35 kg of a 42% potassium hydroxide solution over 20 minutes, with a stirring speed of 25 Hz. The second stage involved adding 1.2 tons of hydrolysate along with 50 kg of a 44% potassium hydroxide solution over 45 minutes, with a stirring speed of 37 Hz. The third stage involved adding 1.8 tons of hydrolysate along with 70 kg of a 44% potassium hydroxide solution over 55 minutes, with a stirring speed of 42 Hz. S4. After stirring, perform a vacuum operation, maintaining a vacuum level of -87 kPa. S5. After vacuuming, dehydrate for 30 minutes to obtain alkaline gel; S6. After the pyrolysis reactor is heated to 130~140℃, normal feeding and discharging begins. Open the hydrolysate feed regulating valve to control the flow rate. The hydrolysate flow rate is 3.5 tons / hour. At the same time, open the three-way valve for potassium hydroxide feed and add 48% potassium hydroxide solution at a mass ratio of 1000:0.3. The hydrolysate then undergoes a pyrolysis reaction. Comparative Example 1

[0031] The steps are basically the same as in Example 1, except that the mass concentration of the potassium hydroxide solution added in step S2 is 40%.

[0032] Compared with Example 1, the formation rate of alkaline gel in Comparative Example 1 was slower, indicating that the low concentration of potassium hydroxide solution resulted in poor catalytic effect; the viscosity of alkaline gel was significantly reduced, affecting the continued production of alkaline gel; although the subsequent steps were the same as in Example 1, the final alkaline gel had a lower viscosity, a longer formation time, and a shorter production cycle, as detailed in Table 1. Comparative Example 2

[0033] The steps are basically the same as in Example 1, except that the mass concentration of the potassium hydroxide solution added in step S3 is 48%.

[0034] Compared with Example 1, the alkaline gel formation rate was too fast after adding high-concentration potassium hydroxide solution twice in Comparative Example 2, indicating that the high concentration of potassium hydroxide solution has a strong catalytic effect and a violent reaction; the viscosity of the alkaline gel increased significantly, resulting in severe gelation in the reactor; although the subsequent steps were the same as in Example 1, the final alkaline gel had a higher viscosity and a shorter production cycle, as detailed in Table 1. Comparative Example 3

[0035] The steps are basically the same as in Example 1, except that the hydrolysate and potassium hydroxide solution are added at once in step S3. Specifically, 4 tons of hydrolysate and 150 kg of 42% potassium hydroxide solution are added twice while stirring, and the stirring frequency is fixed at 35 Hz.

[0036] Compared to Example 1, the formation rate of the alkaline gel slowed down after the second addition of hydrolysate and potassium hydroxide solution in Comparative Example 3, indicating that the formation rate of alkaline gel varies depending on the amount of hydrolysate added. The viscosity of the alkaline gel increased significantly, resulting in a higher concentration of alkaline gel. Although the subsequent steps were the same as in Example 1, the final alkaline gel had a higher viscosity and a shorter production cycle. See Table 1 for details. Comparative Example 4

[0037] The existing pyrolysis process is adopted, specifically: Before feeding the pyrolysis reactor, pre-vacuum it to below -95 kPa; preheat the pyrolysis reactor to 100°C, then directly feed 1~1.5 tons / hour of hydrolysate; simultaneously feed a 48% potassium hydroxide solution at a mass ratio of 1000:0.5; start stirring when the liquid level in the pyrolysis reactor reaches about 20%; observe the reaction inside the reactor and control the normal production liquid level at 40%~45%; after 8 hours of normal reaction, start the downward discharge operation; after 4 days of operation, shut down the pyrolysis reactor for discharge treatment. See Table 1 for specific results.

[0038] The pyrolysis products of Example 1 and Comparative Example 1 were tested, and the results are shown in Table 2.

[0039] Table 1. Pyrolysis reaction under different conditions

[0040] Table 2 Detection results of pyrolysis products

[0041] Based on the above embodiments and comparative data, it can be seen that the alkali-gel process of the present invention has low energy consumption, uniform reaction, high product quality, high heat exchange efficiency, large processing capacity, and reduces steam consumption. Changing the process parameters directly affects the operating cycle; a significantly shorter operating cycle results in poor alkali-gel performance, increased slag discharge, excessive material consumption, material waste, and reduced production capacity.

[0042] Finally, it should be noted that the above-listed embodiments are merely preferred embodiments of the present invention. Of course, those skilled in the art can make modifications and variations to the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should be considered as being within the protection scope of the present invention.

Claims

1. An alkaline gel process for improving the reaction efficiency of a pyrolysis reactor, characterized in that, Includes the following steps: S1. At room temperature and pressure, add hydrolysate to the pyrolysis vessel; S2. Add potassium hydroxide solution and stir; S3. Under stirring, add the hydrolysate and potassium hydroxide solution a second time; S4. After stirring, perform a vacuum operation, maintaining a vacuum level of -84~-87KPa; S5. Dehydration yields alkaline gum; S6. The pyrolysis reactor is heated to 130~140℃, and hydrolysate and catalyst are added to the pyrolysis reactor to carry out the pyrolysis reaction.

2. The alkaline gel process for improving the reaction efficiency of the pyrolysis reactor according to claim 1, characterized in that, The mass concentration of the potassium hydroxide solution in step S2 is 46%~49%.

3. The alkaline gel process for improving the reaction efficiency of the pyrolysis reactor according to claim 1, characterized in that, The mass ratio of the hydrolysate in step S1 to the potassium hydroxide solution in step S2 is 1000:70~80.

4. The alkaline gel process for improving the reaction efficiency of the pyrolysis reactor according to claim 1, characterized in that, The mass concentration of the potassium hydroxide solution in step S3 is 40%~44%.

5. The alkaline gel process for improving the reaction efficiency of the pyrolysis reactor according to claim 1, characterized in that, The mass ratio of the hydrolysate to the potassium hydroxide solution in step S3 is 1000:35~40.

6. The alkaline gel process for improving the reaction efficiency of the pyrolysis reactor according to claim 1, characterized in that, The mass ratio of the hydrolysate in step S1 to that in step S3 is 1:

1.

7. The alkaline gel process for improving the reaction efficiency of the pyrolysis reactor according to claim 1, characterized in that, In step S3, the hydrolysate and potassium hydroxide solution are added in three separate portions, with the amount added increasing each time and the stirring rate increasing each time.

8. The alkaline gel process for improving the reaction efficiency of the pyrolysis reactor according to claim 7, characterized in that, In step S3, the hydrolysate and potassium hydroxide solution are added in three separate steps: First, the hydrolysate and a 40-44% potassium hydroxide solution are added, with a mass ratio of 800-1200:25-35, over a time of 18-22 minutes, with a stirring speed of 22-27 Hz. Second, the hydrolysate and a 40-44% potassium hydroxide solution are added, with a mass ratio of 800-1200:45-55, over a time of 35-45 minutes, with a stirring speed of 32-37 Hz. Third, the hydrolysate and a 40-44% potassium hydroxide solution are added, with a mass ratio of 1800-2200:65-75, over a time of 45-55 minutes, with a stirring speed of 38-42 Hz.

9. The alkaline gel process for improving the reaction efficiency of a pyrolysis reactor according to claim 1, characterized in that, In step S6, after the pyrolysis reactor is heated to 130~140℃, the flow rate of the hydrolysate is controlled at 2~3.5 tons / hour, and a catalyst is added at a mass ratio of 1000:0.

3.

10. The alkaline gel process for improving the reaction efficiency of the pyrolysis reactor according to claim 9, characterized in that, The catalyst in step S6 is potassium hydroxide.

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