阅读说明：本技术 一种二甲水解系统停车逼干工艺 (Shutdown forced drying process of dimethyl hydrolysis system ) 是由 刘成彬 程渝峰 汪令杰 高帅 张楠 王刚 杜敏 于 2021-09-27 设计创作，主要内容包括：本发明公开了一种二甲水解系统停车逼干工艺,属于水解物裂解技术领域。本发明的停车逼干工艺用于二甲水解系统清理硅醇钾盐,在停车时,持续进行逼干操作,能够最大程度收集硅氧烷环体,减少残留在裂解釜中的硅氧烷环体,减少环体的浪费,逼干操作完成后,通过向裂解釜中加水避免硅醇钾盐的自燃,整个停车逼干过程稳定、安全,同时,逼干时间短,能够有效避免裂解釜内粘度上涨。(The invention discloses a shutdown forced drying process of a dimethyl hydrolysis system, and belongs to the technical field of hydrolysate cracking. The parking forced drying process is used for cleaning the silanol sylvite in the dimethyl hydrolysis system, the forced drying operation is continuously carried out during parking, siloxane ring bodies can be collected to the maximum degree, the siloxane ring bodies remained in the cracking kettle are reduced, the waste of the ring bodies is reduced, after the forced drying operation is finished, the spontaneous combustion of the silanol sylvite is avoided by adding water into the cracking kettle, the whole parking forced drying process is stable and safe, meanwhile, the forced drying time is short, and the viscosity rise in the cracking kettle can be effectively avoided.)

1. The shutdown forced drying process of the dimethyl hydrolysis system is characterized by comprising the following steps of:

s1: closing the KOH feed valve;

s2: stopping introducing steam into the hydrolysate preheater, reducing the temperature of the preheater, stopping cracking feeding, and closing the last manual valve for feeding;

s3: closing the cracking kettle jacket and the coil pipe steam regulating valve, and continuously performing forced drying operation;

s4: after the forced drying is finished, completely closing the cracking kettle jacket, the coil steam regulating valve and the cut-off valve, opening the cracking kettle jacket and the coil pressure relief valve, and relieving the pressure of the cracking kettle jacket and the coil;

s5: circulating water is introduced into the cracking kettle jacket and the coil pipe, so that the temperature of the cracking kettle is accelerated to be reduced;

s6: in the cooling process, starting a nitrogen-filling manual valve of the cracking kettle, removing the last manual valve of the nitrogen filling of the cracking kettle, and starting a soft water tank to add water to all manual valves on the pipeline of the cracking kettle;

s7: after the temperature of the cracking kettle is reduced to a set value, closing a cracking vacuumizing adjusting valve, and simultaneously closing one manual valve of cracking vacuumizing;

s8: opening a nitrogen filling cut-off valve of the cracking kettle, and fully opening the last manual valve for filling nitrogen into the cracking kettle to carry out vacuum breaking operation on the cracking system;

s9: when the pressure in the cracking kettle rises to positive pressure, an emptying manual valve is opened, when the pressure in the cracking kettle reaches a set value, an emptying stop valve is opened to carry out continuous pressure relief and pressurization replacement operation, the pressure relief operation is carried out, meanwhile, a soft water tank is opened to add water to the stop valve on the pipeline of the cracking kettle, and soft water is added into the cracking kettle;

s10: and continuously cooling the cracking kettle, and when the temperature at the top of the cracking kettle is reduced to a set value, opening a manhole to confirm the material condition in the cracking kettle.

2. The di-hydrolysis system shutdown forced drying process of claim 1, wherein in step S1, the KOH feeding valve is closed at least 4 hours apart from the shutdown time.

3. The shutdown forced drying process of the dimethyl hydrolysis system as claimed in claim 1, wherein in step S3, the specific operations of closing the jacket of the pyrolysis kettle and the coil steam regulating valve are as follows: the opening of the kettle-disassembling jacket and the coil steam regulating valve is reduced from full opening to 25-35% within half an hour.

4. The di-hydrolysis system shutdown forced drying process of claim 1, wherein in step S4, the conditions for forced drying end are as follows: the extraction amount of the cracking kettle is less than 1.0m³Or the viscosity of the materials in the kettle is gradually increased.

5. The di-methyl hydrolysis system shutdown forced drying process of claim 1, wherein in step S5, when the circulating water is introduced, the condenser circulating water is opened to remove water hammer.

6. The di-hydrolysis system shutdown forced drying process of claim 1, wherein in step S6, the soft water tank level is ensured to reach more than 80%.

7. The di-hydrolysis system shutdown forced drying process of claim 1, wherein the set point for the gas phase temperature reduction in step S10 is 100 ℃.

8. The di-methyl hydrolysis system shutdown forced drying process of claim 7, wherein in step S10, when the cracking kettle material condition is confirmed:

if no large amount of sylvite exists on the kettle wall, stopping to force dry the technological process;

if a large amount of sylvite is remained on the wall of the kettle, continuing to add soft water into the cracking kettle until the position of the cracking kettle is close to the position of a manhole cover, then closing the manhole cover, closing a pipeline for introducing circulating water into a jacket and a coil pipe of the cracking kettle, draining the water in the jacket and the coil pipe of the cracking kettle, introducing steam into the jacket and the coil pipe of the cracking kettle, raising the temperature of a liquid phase to 90 ℃, maintaining the temperature, continuously stirring and preserving the temperature for 4 hours, then opening the manhole and simultaneously discharging slag, and ending the shutdown forced drying process flow.

9. The shutdown forced drying process of the dimethyl hydrolysis system according to any one of claims 1 to 8, wherein in step S2, when the temperature of the preheater is reduced to 65-75 ℃, the cracking feed is stopped;

in step S7, the temperature of the cracking kettle is reduced by a set value of 100 ℃;

in step S8, the pressure of nitrogen is 0.7 MPa;

in step S9, the pressure in the cracking kettle reaches a set value of 10 Kpa;

in step S10, the set value of the decrease in the gas phase temperature is 100 ℃.

Technical Field

The invention relates to the technical field of hydrolysate cracking, in particular to a shutdown forced drying process of a dimethyl hydrolysis system.

Background

When the hydrolysate cracking process is a dimethyl hydrolysis system, the produced hydrolysate is mixed siloxane with linear content of about 70% and cyclic content of about 30%, and the mixed siloxane in the hydrolysate is cracked in a cracking kettle under high temperature and low pressure conditions by stirring, wherein the mixed siloxane in the linear content of the hydrolysate is converted into cyclic siloxane by using 45% potassium hydroxide as a catalyst and octadecanol as a solvent. The principle of the cracking is as follows:

when the length of the chain link is less than 3, the potassium silanol salt cannot form a ring body, and can only stay in the kettle in the form of the potassium silanol salt, so that the materials in the cracking kettle are increased due to long-time accumulation, and a sufficient cracking place cannot be provided, therefore, after the cracking kettle runs for a certain period, the cracking kettle needs to be stopped to discharge the residual potassium silanol salt out of the system, and the feeding and the starting are carried out again after the operation is finished. Because the potassium silanol salt forms spontaneous combustion when meeting air, in the prior art, water can be directly added into the cracking kettle when the cracking kettle is stopped, although the natural problem of the potassium silanol salt is solved, a large amount of rings are discharged along with the water, and a large amount of rings are wasted.

Disclosure of Invention

The invention aims to provide a parking drying-forcing process of a dimethyl hydrolysis system, which aims to solve the problem that a large amount of cyclic bodies are wasted when the existing dimethyl hydrolysis system is parked to clean potassium silanol salt.

The technical scheme for solving the technical problems is as follows:

a shutdown forced drying process of a dimethyl hydrolysis system comprises the following steps:

s1: closing the KOH feed valve;

s2: stopping introducing steam into the hydrolysate preheater, reducing the temperature of the preheater, stopping cracking feeding, and closing the last manual valve for feeding;

s3: closing the cracking kettle jacket and the coil pipe steam regulating valve, and continuously performing forced drying operation;

s4: after the forced drying is finished, completely closing the cracking kettle jacket, the coil steam regulating valve and the cut-off valve, opening the cracking kettle jacket and the coil pressure relief valve, and relieving the pressure of the cracking kettle jacket and the coil;

s5: circulating water is introduced into the cracking kettle jacket and the coil pipe, so that the temperature of the cracking kettle is accelerated to be reduced;

s6: in the cooling process, starting a nitrogen-filling manual valve of the cracking kettle, removing the last manual valve of the nitrogen filling of the cracking kettle, and starting a soft water tank to add water to all manual valves on the pipeline of the cracking kettle;

s7: after the temperature of the cracking kettle is reduced to a set value, closing a cracking vacuumizing adjusting valve, and simultaneously closing one manual valve of cracking vacuumizing;

s8: opening a nitrogen filling cut-off valve of the cracking kettle, and fully opening the last manual valve for filling nitrogen into the cracking kettle to carry out vacuum breaking operation on the cracking system;

s9: when the pressure in the cracking kettle rises to positive pressure, an emptying manual valve is opened, when the pressure in the cracking kettle reaches a set value, an emptying stop valve is opened to carry out continuous pressure relief and pressurization replacement operation, the pressure relief operation is carried out, meanwhile, a soft water tank is opened to add water to the stop valve on the pipeline of the cracking kettle, and soft water is added into the cracking kettle;

s10: and continuously cooling the cracking kettle, and when the temperature at the top of the cracking kettle is reduced to a set value, opening a manhole to confirm the material condition in the cracking kettle.

Further, in step S1, the KOH feeding valve is closed at least 4 hours apart from the shutdown time.

Further, in step S3, the specific operation of closing the jacket of the pyrolysis kettle and the coil steam regulating valve is as follows: and the opening of the regulating valve is reduced from 25 to 35 percent from the full switch within half an hour.

Further, in step S4, the conditions for approaching end are: the extraction amount of the cracking kettle is less than 1.0m³Or the viscosity of the materials in the kettle is gradually increased.

Further, in step S5, when the circulating water is introduced, the condenser circulating water is opened to drain water to eliminate the water hammer phenomenon.

Further, in step S6, the soft water tank is ensured to have a liquid level of 80% or more.

Further, in the above step S10, the set value of the decrease in the gas phase temperature is 100 ℃.

Further, in step S10, when the cracking kettle is confirmed to contain the material:

if no large amount of sylvite exists on the kettle wall, stopping to force dry the technological process;

if a large amount of sylvite is remained on the wall of the kettle, continuing to add soft water into the cracking kettle until the position of the cracking kettle is close to the position of a manhole cover, then closing the manhole cover, closing a pipeline for introducing circulating water into a jacket and a coil pipe of the cracking kettle, draining the water in the jacket and the coil pipe of the cracking kettle, introducing steam into the jacket and the coil pipe of the cracking kettle, raising the temperature of a liquid phase to 90 ℃, maintaining the temperature, continuously stirring and preserving the temperature for 4 hours, then opening the manhole and simultaneously discharging slag, and ending the shutdown forced drying process flow.

Further, in the step S2, when the temperature of the preheater is reduced to 65-75 ℃, the cracking feed is stopped;

in step S7, the temperature of the cracking kettle is reduced by a set value of 100 ℃;

in step S8, the pressure of nitrogen is 0.7 MPa;

in step S9, the pressure in the cracking kettle reaches a set value of 10 KPa;

in step S10, the set value of the decrease in the gas phase temperature is 100 ℃.

The invention has the following beneficial effects:

(1) the parking dry forcing process is used for cleaning the silanol sylvite in the dimethyl hydrolysis system, when parking is carried out, dry forcing operation is continuously carried out, siloxane ring bodies can be collected to the maximum degree, the siloxane ring bodies remained in the cracking kettle are reduced, waste of the ring bodies is reduced, after the dry forcing operation is finished, spontaneous combustion of the silanol sylvite is avoided by adding water into the cracking kettle, and the whole parking dry forcing process is stable and safe.

(2) In the whole process of parking forced drying, the forced drying time is short, and stirring regulation caused by viscosity rising in the cracking kettle can be effectively avoided, so that the problem that a product finally formed in parking cannot be discharged from the cracking kettle is solved.

(3) The method can effectively clean the potassium silanol salt remained on the wall of the cracking kettle in the forced drying process, and shorten the time consumed for cleaning the kettle wall.

Detailed Description

The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.

Examples

A shutdown forced drying process of a dimethyl hydrolysis system comprises the following steps:

s1: closing the KOH feeding valve more than 4 hours before stopping, namely, at least separating the time for closing the KOH feeding valve from the stopping time by 4 hours, stopping feeding of KOH, fully reacting in the cracking kettle, and avoiding the waste of raw materials;

s2: stopping introducing steam into the hydrolysate preheater, reducing the temperature of the preheater to 65-75 ℃, stopping cracking feeding, and closing the last manual valve on the feeding pipeline;

s3: slowly closing the cracking kettle jacket and the coil steam regulating valve, reducing the opening of the cracking kettle jacket and the coil steam regulating valve from full opening to 25-35% within half an hour, and continuously performing forced drying operation;

s4: the extraction amount of the cracking kettle is less than 1.0m³H or when the viscosity of the materials in the kettle is gradually increased, the drying forcing operation is considered to be finished, the drying forcing operation is stopped at the moment, then the cracking kettle jacket, the coil steam regulating valve and the cut-off valve are closed, the cracking kettle jacket and the coil pressure relief valve are opened, and the pressure relief is carried out on the cracking kettle jacket and the coil; when the pressure is relieved, the pressure relief operation is as fast as possible, so that the cracking kettle jacket and the coil pipe pressure relief valve are fully opened as far as possible on the premise of ensuring safety;

s5: after the pressure in the cracking kettle jacket and the coil pipe is exhausted, circulating water is introduced into the cracking kettle jacket and the coil pipe, so that the cooling of the cracking kettle is accelerated; when the circulating water is introduced, the circulating water entering the jacket and the coil pipe is possibly gasified due to overhigh temperature in the jacket and the coil pipe of the cracking kettle, so that a water hammer phenomenon is generated, if the water hammer phenomenon occurs, the circulating water of the condenser can be drained and opened, the water hammer phenomenon is eliminated, and if the water hammer phenomenon does not occur, the circulating water does not need to be opened.

S6: in the cooling process, opening a nitrogen-filled manual valve of the cracking kettle, removing the last manual valve of the nitrogen filling of the cracking kettle, namely keeping the last manual valve of the nitrogen filling of the cracking kettle closed, simultaneously confirming that the pressure of the nitrogen to be used is 0.7MPa, then ensuring that the liquid level of the soft water tank reaches more than 80%, and opening all the manual valves of the soft water tank for adding water to the pipeline of the cracking kettle;

s7: when the temperature of the cracking kettle is reduced to 100 ℃, closing a cracking vacuumizing adjusting valve, and simultaneously closing one manual valve of cracking vacuumizing;

s8: opening a nitrogen filling cut-off valve of the cracking kettle, fully opening the last manual valve for filling nitrogen into the cracking kettle, filling nitrogen with the pressure of 0.7MPa into the cracking kettle, and performing vacuum breaking operation on the cracking system;

s9: when cracking cauldron internal pressure rises to the malleation, preferably rises to the pressure-fired, open the manual valve of unloading, when cracking cauldron internal pressure reaches 10KPa, open the replacement operation that the unloading trip valve carries out continuous pressure release and pressurize (fill pressure and pressure release coexist promptly), through continuous replacement, take away the cracking cauldron with the heat in the cauldron on the one hand, reach the effect of cooling, on the other hand continuous replacement of sweeping can promote the inactivation of silanol potassium salt, create the safety condition for follow-up opening manhole cover. Carrying out pressure relief operation, simultaneously opening a cut-off valve on a pipeline of the cracking kettle for adding water into a soft water tank, and adding soft water into the cracking kettle to avoid spontaneous combustion of the sylvite silanol when a manhole is opened;

s10: continuously cooling the cracking kettle, and opening a manhole when the temperature at the top of the cracking kettle is reduced to 100 ℃ to confirm the material condition in the cracking kettle;

if no large amount of sylvite exists on the kettle wall, stopping to force dry the technological process;

if a large amount of sylvite is remained on the wall of the kettle, continuing to add soft water into the cracking kettle until the position of the cracking kettle is close to the position of a manhole cover, then closing the manhole cover, closing a pipeline for introducing circulating water into a jacket and a coil pipe of the cracking kettle, draining the water in the jacket and the coil pipe of the cracking kettle, introducing steam into the jacket and the coil pipe of the cracking kettle, raising the temperature of a liquid phase to 90 ℃, maintaining the temperature, continuously stirring and preserving the temperature for 4 hours, then opening the manhole and simultaneously discharging slag, and ending the shutdown forced drying process flow.

Through the parking dry forcing process flow, siloxane ring bodies can be collected to the maximum degree, the siloxane ring bodies remaining in the cracking kettle are reduced, the waste of the ring bodies is reduced, after the dry forcing operation is finished, the spontaneous combustion of sylvite is avoided by adding water into the cracking kettle, and the whole parking dry forcing process is stable and safe; and the forced drying time is short, so that stirring regulation caused by viscosity rising in the cracking kettle can be effectively avoided, and the problem that the finally formed product cannot be discharged from the cracking kettle during stopping is avoided.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.