Regeneration method of silicon-based mold core stripping liquid

Abstract

The method comprises the following steps: predicting the service life of the depoling liquid: shunting a depoled solution in a depoling reaction kettle, carrying out solid-liquid separation on part of the depoled solution, adding a solution stabilizer into the separated pure solution at a constant temperature, fully stirring, and measuring the density of the solution; lime milk is added into the invalid depoling liquid under the stirring condition, solid-liquid separation is carried out, and a solution obtained after solid-liquid separation is the regenerated depoling liquid. The method for predicting the service life of the depoling liquid is simple, the regeneration process of the depoling liquid after failure is simple, the controllability is high, green production in the depoling process can be achieved, and waste liquid and solid waste are not discharged.

Description

Technical Field

[0001] The invention belongs to the technical field of precision casting, and relates to a silicon-based ceramic core stripping liquid technology for gas turbine blade casting, and in particular to a method for regenerating a silicon-based core stripping liquid. Background Art

[0002] The complexity of the internal structure of gas turbine air-cooled turbine blades is inevitable for the development of high-efficiency gas turbines. The ceramic cores used for casting air-cooled turbine blades mainly include silicon oxide series ceramic cores and aluminum oxide series ceramic cores. Among them, the removal of aluminum oxide-based ceramic cores is extremely difficult. Due to the technical blockade, my country has not yet mastered the relevant core technology. Silicon oxide-based ceramic cores have long played a vital role in the complex air-cooled inner cavity forming of advanced gas turbine turbine blades. However, with the increasing complexity of the inner cavity of gas turbine turbine blades, how to effectively and quickly remove the core has also become a bottleneck problem for the high-quality preparation of gas turbines. At present, silicon oxide-based ceramic cores are widely used in China to cast gas turbine turbine blades. The cast turbine blades are removed in a reactor using a potassium hydroxide solution with a mass fraction of 30-40%. The removal principle is to use potassium hydroxide to react with the ceramic core to make the silicon dioxide in the ceramic core react with potassium hydroxide to convert into potassium silicate solution, thereby realizing the removal of the core. At present, the core removal of gas turbine turbine blades is intermittent, that is, a batch of cast turbine blades are placed in a reactor filled with potassium hydroxide solution for heating and boiling for 7 to 10 hours. When the core in the blade is completely dissolved, it is taken out and cleaned with clean water before entering the next process. After precipitation, the solution after core removal removes the insoluble solids and is transferred back to the core removal reactor to remove a batch of blades. When the concentration of hydroxide in the solution is reduced to a certain value, the core removal time increases to 3 times that of the initial core removal, reaching more than 24 hours, and the core removal efficiency becomes very low. At this time, the core removal solution is no longer used to continuously remove new turbine blades and needs to be discharged. In the specific production process, since there is no effective life prediction or judgment basis, whether the core removal liquid is used depends on the core removal time, which seriously affects the quality and efficiency of core removal. In addition, a large number of failed core removal liquids contain a large amount of potassium hydroxide and are strongly alkaline, which requires special treatment before discharge. The main way to discharge is to neutralize the alkali solution, which is a waste of resources. Therefore, the existing process not only seriously affects the core removal efficiency and the use efficiency of potassium hydroxide solution, but also puts certain pressure on the environment. Summary of the invention

[0003] Purpose of the Invention

[0004] Aiming at the problems that the service life of potassium hydroxide solution (hereinafter referred to as core stripping liquid) cannot be determined in the process of removing silicon-based cores after casting turbine blades for gas turbines and the core stripping liquid method is circulated, the present invention provides a method for regenerating silicon-based core stripping liquid.

[0005] Technical Solution

[0006] A method for regenerating silicon-based core stripping liquid:

[0007] Predicting the life of the core-removing liquid: The core-removing liquid is the solution after the ceramic core is removed from the core in the core-removing reactor. The solution after the core-removing reactor is diverted, and the diverted part of the solution after the core-removing enters the solid-liquid separator for solid-liquid separation. The pure solution separated by the solid-liquid separator is transferred to a heat preservation tank with a temperature of 60-80°C. A solution stabilizer of 1-10% of the volume of the separated pure solution is added to the separated pure solution at a constant temperature of 60-80°C, and the solution is fully stirred. Then the density of the solution is measured. When the solution density is greater than 1.5, it can be determined that the core-removing liquid has failed and is not suitable for continuous use in core-removing.

[0008] Regeneration of core-removing liquid: transfer the failed core-removing liquid into a reactor with stirring and heat preservation functions, add lime milk to the failed core-removing liquid under stirring conditions, so that the potassium silicate in the solution reacts with calcium hydroxide to form calcium silicate precipitate and potassium hydroxide. After the addition of lime milk, continue to keep stirring for a certain period of time to allow the calcium silicate to fully precipitate, and then perform solid-liquid separation. The solution obtained after solid-liquid separation is the regeneration core-removing liquid, which is continuously used for blade core-removing. The obtained liquid can be continuously used for blade core-removing, thereby realizing the regeneration of failed core-removing liquid.

[0009] Furthermore, the solution stabilizer is a mixture of one or more of sodium gluconate, triethanolamine and ethyl silicate; when the solution stabilizer is a mixture of sodium gluconate, triethanolamine and ethyl silicate, the mass fraction of sodium gluconate is 20-50%, the mass fraction of triethanolamine is 20-50%, and the mass fraction of ethyl silicate is 30-60%.

[0010] Furthermore, the lime milk is added into the de-coring liquid through an annular hollow tube, which includes a vertically arranged feed pipe and a horizontally arranged porous annular tube, one end of the feed pipe is provided with a feed port, and the other end of the feed pipe is connected to the porous annular tube. When viewed from the side, the entire annular hollow tube is L-shaped, and a plurality of discharge holes are evenly arranged on the outer circumference of the porous annular tube.

[0011] Furthermore, the discharge hole of the porous annular tube is not less than 2 cm away from the upper liquid surface of the failed core-deleting liquid.

[0012] Furthermore, the mass fraction of the core-removing solute in the core-removing liquid is 30% to 40% of the core-removing liquid, the ceramic core is a silicon-based core, and the concentration of silicon dioxide is 20% to 30% when the core-removing liquid fails.

[0013] Furthermore, the core removal liquid is a potassium hydroxide solution.

[0014] Furthermore, the effective calcium in the lime milk is 80% to 90%, and the amount of lime milk added and the amount of silicon oxide in the solution are added according to a stoichiometric ratio of 0.9 to 1.2.

[0015] Furthermore, the stirring speed when adding the lime milk is 80 r / min to 120 r / min, and the stirring time is continued to be 40 min to 80 min after the addition of the lime milk is completed.

[0016] Advantages and effects

[0017] 1. The service life prediction method of the core removal liquid is simple. The service life of the core removal liquid can be determined by measuring the density of the solution using a densitometer.

[0018] 2. The regeneration process of the core-removing liquid after failure is simple and easy to control, which can realize green production of the core-removing process without discharging waste liquid and solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. The protection scope of the present invention is not limited to the following description.

[0020] Figure 1 This is a schematic diagram of the technical route;

[0021] Figure 2 This is a picture of calcium silicate powder;

[0022] Figure 3 It is a schematic diagram of the side structure of the annular hollow tube;

[0023] Figure 4 This is a schematic diagram of the structure of the annular hollow tube when viewed from the direction of the feed pipe.

[0024] Explanation of the accompanying drawings: 1. Feed pipe, 2. Multi-hole annular tube, 3. Discharge hole. DETAILED DESCRIPTION

[0025] A method for regenerating silicon-based core stripping liquid:

[0026] Predicting the life of the core-removing liquid: The core-removing liquid is the solution after the ceramic core is removed from the core in the core-removing reactor. The solution after the core-removing reactor is diverted, and the diverted part of the solution after the core-removing enters the solid-liquid separator for solid-liquid separation. The pure solution separated by the solid-liquid separator is transferred to a heat preservation tank with a temperature of 60-80°C. A solution stabilizer of 1-10% of the volume of the separated pure solution is added to the separated pure solution at a constant temperature of 60-80°C, and the solution is fully stirred. The density of the solution is then measured with a glass float. When the solution density is greater than 1.5, it can be determined that the core-removing liquid has failed and is not suitable for continuous use in core-removing.

[0027] Regeneration of core-removing liquid: transfer the failed core-removing liquid into a reactor with stirring and heat preservation functions, add lime milk to the failed core-removing liquid under stirring conditions, so that the potassium silicate in the solution reacts with calcium hydroxide to form calcium silicate precipitate and potassium hydroxide. After the addition of lime milk, continue to stir for a certain period of time to allow the calcium silicate to fully precipitate and then perform solid-liquid separation. The solid obtained after solid-liquid separation can be used for building materials, heat insulation materials and refractory materials after washing with hot water and drying. The obtained solution is the regeneration core-removing liquid, which is continuously used for blade core-removing. The liquid obtained can be continuously used for blade core-removing, thereby achieving regeneration of failed core-removing liquid.

[0028] The solution stabilizer is a mixture of one or more of sodium gluconate, triethanolamine and ethyl silicate; when the solution stabilizer is a mixture of sodium gluconate, triethanolamine and ethyl silicate, the mass fraction of sodium gluconate is 20-50%, the mass fraction of triethanolamine is 20-50%, and the mass fraction of ethyl silicate is 30-60%.

[0029] like Figure 3 and Figure 4 As shown ( Figure 4 The dotted line in the figure represents the position of the discharge hole 3). The lime milk is added to the de-core liquid through the annular hollow tube. The annular hollow tube includes a vertically arranged feed pipe 1 and a horizontally arranged porous annular tube 2. One end of the feed pipe 1 is provided with a feed port, and the other end of the feed pipe 1 is connected to the porous annular tube 2. The entire annular hollow tube is L-shaped when viewed from the side. The outer circumference of the porous annular tube 2 is evenly provided with multiple discharge holes 3, which facilitates the lime milk to evenly enter the solution. The discharge hole 3 of the porous annular tube 2 is not less than 2 cm from the upper liquid surface of the de-core liquid to prevent the lime milk from reacting with the de-core liquid to form scars to block the discharge hole.

[0030] The mass fraction of the core-removing solute in the core-removing liquid is 30% to 40% of the core-removing liquid, the ceramic core is a silicon-based core, and the concentration of silicon dioxide when the core-removing liquid fails is 20% to 30%. The core-removing liquid is a potassium hydroxide solution.

[0031] The effective calcium in the lime milk is 80% to 90%, and the amount of lime milk added is added according to the stoichiometric ratio of 0.9 to 1.2 to the amount of silicon oxide in the solution.

[0032] The stirring speed when adding lime milk is 80r / min~120r / min, and the stirring time is continued for 40min~80min after the addition of lime milk is completed.

[0033] The de-coring time of the failed de-coring liquid for de-coring the cast turbine blade is more than 24 hours, and the de-coring efficiency is significantly reduced. The de-coring time of the regenerated de-coring liquid for de-coring is 8 to 10 hours.

[0034] Figure 1 This is a schematic diagram of the technical route. Figure 2 As shown, the particle size of the calcium silicate powder particles obtained by the reaction is about 28 μm, and the surface has a flower-like structure composed of scaly thin layers.

[0035] The de-coring reactor, solid-liquid separator, glass float and reactor with stirring and heat preservation functions used in this patent are all existing technical devices commonly sold on the market.

[0036] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the embodiments of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the embodiments here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for regenerating silicon-based core stripping liquid, characterized in that: Predicting the life of the core-removing liquid: The core-removing liquid is the solution after the ceramic core is removed from the core in the core-removing reactor. The solution after the core-removing reactor is diverted, and the diverted part of the solution after the core-removing enters the solid-liquid separator for solid-liquid separation. The pure solution separated by the solid-liquid separator is transferred to a heat preservation tank with a temperature of 60-80°C. A solution stabilizer of 1-10% of the volume of the separated pure solution is added to the separated pure solution at a constant temperature of 60-80°C, and the solution is fully stirred. Then the density of the solution is measured. When the solution density is greater than 1.5, it can be determined that the core-removing liquid has failed and is not suitable for continuous use in core-removing. Regeneration of core-removing liquid: transfer the failed core-removing liquid into a reactor with stirring and heat preservation functions, add lime milk to the failed core-removing liquid under stirring conditions, so that the potassium silicate in the solution reacts with calcium hydroxide to form calcium silicate precipitate and potassium hydroxide. After the addition of lime milk, continue to keep stirring for a certain period of time to allow the calcium silicate to fully precipitate, and then perform solid-liquid separation. The solution obtained after solid-liquid separation is the regeneration core-removing liquid, which is continuously used for blade core-removing. The obtained liquid can be continuously used for blade core-removing, thereby realizing the regeneration of failed core-removing liquid.

2. The method for regenerating silicon-based core stripping liquid according to claim 1, characterized in that: The solution stabilizer is a mixture of one or more of sodium gluconate, triethanolamine and ethyl silicate; when the solution stabilizer is a mixture of sodium gluconate, triethanolamine and ethyl silicate, the mass fraction of sodium gluconate is 20-50%, the mass fraction of triethanolamine is 20-50%, and the mass fraction of ethyl silicate is 30-60%.

3. The method for regenerating silicon-based core stripping liquid according to claim 1, characterized in that: The lime milk is added to the de-coring liquid through an annular hollow tube. The annular hollow tube comprises a vertically arranged feed pipe (1) and a horizontally arranged porous annular tube (2). One end of the feed pipe (1) is provided with a feed port. The other end of the feed pipe (1) is connected to the porous annular tube (2). The entire annular hollow tube is L-shaped when viewed from the side. The outer circumference of the porous annular tube (2) is evenly provided with a plurality of discharge holes (3).

4. The method for regenerating silicon-based core stripping liquid according to claim 3, characterized in that: The discharge hole (3) of the porous annular tube (2) is not less than 2 cm away from the upper liquid surface of the failed core removal liquid.

5. The method for regenerating silicon-based core stripping liquid according to claim 1, characterized in that: The mass fraction of the core-removing solute in the core-removing liquid is 30% to 40% of the core-removing liquid, the ceramic core is a silicon-based core, and the concentration of silicon dioxide when the core-removing liquid fails is 20% to 30%.

6. The method for regenerating silicon-based core stripping liquid according to claim 1 or 5, characterized in that: The core removal liquid is a potassium hydroxide solution.

7. The method for regenerating silicon-based core stripping liquid according to claim 1, characterized in that: The effective calcium in the lime milk is 80% to 90%, and the amount of lime milk added is added according to the stoichiometric ratio of 0.9 to 1.2 to the amount of silicon oxide in the solution.

8. The method for regenerating silicon-based core stripping fluid according to claim 1, characterized in that: The stirring speed when adding lime milk is 80r / min~120r / min, and the stirring time is continued for 40min~80min after the addition of lime milk is completed.

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