A method for regenerating a silicon-based core-drawing liquid

Abstract

The application relates to a regeneration method of a silicon-based core stripping liquid, which needs to predict the service life of the core stripping liquid; after the solution used after core stripping in a core stripping reaction kettle is branched, part of the solution used after core stripping is subjected to solid-liquid separation, the pure solution after separation is fully stirred after a solution stabilizer is added at a constant temperature, and then the solution density is measured; the core stripping liquid is regenerated; under the condition of stirring, lime milk is added into the invalid core stripping liquid, solid-liquid separation is carried out, and the solution obtained after the solid-liquid separation is the regenerated core stripping liquid. The service life prediction method of the core stripping liquid is simple, the regeneration process of the invalid core stripping liquid is simple and strong in controllability, green production can be realized in the core stripping process, and no waste liquid and solid waste are discharged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of precision casting, and relates to a silicon-based ceramic core stripping liquid for casting gas turbine blades, in particular to a regeneration method of a silicon-based core stripping liquid. BACKGROUND

[0002] The complexity of the internal structure of the air-cooled turbine blade for the gas turbine is inevitable for the development of the high-efficiency gas turbine, and the ceramic core adopted for casting the air-cooled turbine blade mainly includes the silicon oxide series ceramic core and the aluminum oxide series ceramic core. The removal of the aluminum oxide-based ceramic core is extremely difficult, and the relevant core technology has not been mastered in China due to the technical blockade. The silicon oxide-based ceramic core plays a crucial role in the forming of the complex air-cooled internal cavity of the advanced gas turbine turbine blade for a long time, but with the increasing complexity of the internal cavity of the gas turbine turbine blade, how to effectively and quickly remove the core has become a bottleneck problem for the high-quality preparation of the gas turbine. At present, the silicon oxide-based ceramic core is generally used for casting the gas turbine turbine blade in China, and the turbine blade after casting is removed in a reaction kettle by using a potassium hydroxide solution with a mass fraction of 30-40%. The removal principle is that the potassium hydroxide reacts with the ceramic core to make the silicon dioxide in the ceramic core react with the potassium hydroxide to form a potassium silicate solution, thereby realizing the removal of the core. At present, the intermittent method is adopted for removing the core of the gas turbine turbine blade, that is, a batch of turbine blades after casting are put into a reaction kettle containing the potassium hydroxide solution for heating and cooking for 7-10 hours, and then the turbine blades are taken out after the core in the turbine blades is completely dissolved, and then the turbine blades are cleaned with clean water and then enter the next process. After the core-removed solution is precipitated to remove the insoluble solids, the solution is transferred into the core-removing reaction kettle to remove a batch of turbine blades. When the concentration of the hydroxide in the solution is reduced to a certain value, the core-removing time is increased to 3 times of the initial core-removing time, which is more than 24 hours, and the core-removing efficiency becomes very low. At this time, the core-removing solution is not used for continuously removing new turbine blades, and needs to be treated for external discharge. In the specific production process, since there is no effective life prediction or judgment basis, whether the core-removing solution is used needs to rely on the core-removing time, which seriously affects the core-removing quality and efficiency. In addition, a large amount of invalid core-removing solution needs to be treated specially for external discharge because it contains a large amount of potassium hydroxide which is strongly alkaline. The main way of external discharge is to neutralize the alkaline solution, which is a waste of resources. Therefore, the existing process not only seriously affects the core-removing efficiency and the use efficiency of the potassium hydroxide solution, but also causes certain pressure on the environment. SUMMARY

[0003] OBJECTIVE

[0004] The present application provides a regeneration method of a silicon-based core stripping liquid for solving the problems that the service life of the potassium hydroxide solution (hereinafter referred to as the core stripping liquid) cannot be determined and the core stripping liquid method needs to be recycled during the removal of the silicon-based core after casting the turbine blade for the gas turbine.

[0005] Technical solutions

[0006] A regeneration method of a silicon-based core stripping liquid:

[0007] Predicting the service life of the stripping liquid: the stripping liquid is the solution after the ceramic core is stripped in the stripping reactor, the solution after the stripping in the stripping reactor is divided into two parts, one part of the solution after the stripping is used to enter the solid-liquid separator for solid-liquid separation, and the pure solution separated by the solid-liquid separator is transferred into a holding tank with a temperature of 60-80℃, under the condition of constant temperature of 60-80℃, a solution stabilizer with a volume of 1-10% of the pure solution after the separation is added to the pure solution after the separation, and then the solution is fully stirred, and then the density of the solution is measured, when the density of the solution is greater than 1.5, it is determined that the stripping liquid has failed and is not suitable for continuous use for stripping;

[0008] Regenerating the stripping liquid: the failed stripping liquid is transferred into a reactor with stirring and heat preservation function, under the condition of stirring, lime milk is added to the failed stripping liquid, so that potassium silicate in the solution reacts with calcium hydroxide to form calcium silicate precipitate and potassium hydroxide, after the addition of lime milk is completed, the stirring is continued for a certain time to make the calcium silicate fully precipitate, and then solid-liquid separation is performed, and the solution obtained after the solid-liquid separation is the regenerated stripping liquid, which can be continuously used for blade stripping, so as to realize the regeneration of the failed stripping liquid.

[0009] Further, the solution stabilizer is 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] Further, the lime milk is added to the failed stripping liquid through an annular hollow pipe, the annular hollow pipe comprises a vertical feed pipe and a horizontal perforated annular pipe, one end of the feed pipe is provided with a feed port, the other end of the feed pipe is communicated with the perforated annular pipe, the entire annular hollow pipe is L-shaped when viewed from the side, and a plurality of discharge holes are uniformly arranged on the outer periphery of the perforated annular pipe.

[0011] Further, the distance from the discharge hole of the perforated annular pipe to the liquid surface of the failed stripping liquid is not less than 2cm.

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

[0013] Further, the stripping liquid is a potassium hydroxide solution.

[0014] Further, the effective calcium in the milk of lime is 80% to 90%, and the milk of lime is added in a proportion of 0.9-1.2 of the stoichiometric ratio of the amount of silica in the solution.

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

[0016] Advantages and effects

[0017] 1. The service life prediction method of the core removal liquid is simple, and the service life of the core removal liquid can be determined by measuring the solution density through the densimeter.

[0018] 2. The regeneration process of the failed core removal liquid is simple and easy to operate, and green production can be realized in the core removal process, without waste liquid and solid waste. BRIEF DESCRIPTION OF DRAWINGS

[0019] The application will be further described below in combination with the drawings and specific embodiments. The protection scope of the application is not limited to the following content.

[0020] Figure 1 It is a technical route schematic diagram;

[0021] Figure 2 It is a calcium silicate powder diagram;

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

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

[0024] Explanation of reference signs: 1. feed pipe, 2. porous annular pipe, 3. discharge hole. DETAILED DESCRIPTION

[0025] A regeneration method of a silicon-based core removal liquid:

[0026] Prediction of the service life of the core removal liquid: the core removal liquid is the solution after the ceramic core is removed in the core removal reactor, and the solution after the core removal in the core removal reactor is divided into two parts, one part of the solution after the core removal is used to enter the solid-liquid separator for solid-liquid separation, and the pure solution separated by the solid-liquid separator is transferred to a heat preservation tank with a temperature of 60-80℃, and then the solution is fully stirred after adding a solution stabilizer with a volume of 1-10% of the separated pure solution under the condition of constant temperature of 60-80℃, and then the solution density is measured by using a glass float meter, when the solution density is greater than 1.5, it is determined that the core removal liquid has failed and is not suitable for continuous use in core removal.

[0027] Regeneration of de-coring liquid: The failed de-coring liquid is transferred into a reactor with stirring and heat preservation functions. Lime milk is added to the failed de-coring liquid under stirring conditions to allow the potassium silicate in the solution to react with calcium hydroxide to form calcium silicate precipitate and potassium hydroxide. After the addition of lime milk, stirring is continued 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 is washed with hot water and dried, and can be used for building materials, heat insulation materials and refractory materials. The obtained solution is the regeneration de-coring liquid, which is continuously used for blade de-coring. The obtained liquid can be continuously used for blade de-coring, thereby realizing the regeneration of the failed de-coring 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 location of the discharge hole 3. The lime milk is added to the de-core solution through an 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. When viewed from the side, the entire annular hollow tube is L-shaped. Multiple discharge holes 3 are evenly arranged on the outer circumference of the porous annular tube 2 to facilitate the uniform entry of the lime milk into the solution. The discharge holes 3 of the porous annular tube 2 are at least 2 cm from the upper liquid surface of the de-core solution to prevent the lime milk from reacting with the de-core solution to form scars that block the discharge holes.

[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 after adding lime milk is continued to be 40min~80min.

[0033] The de-coring time of the de-coring liquid after the failure is more than 24 hours, and the de-coring efficiency is significantly reduced. The de-coring time of the de-coring liquid after the failure is 8 to 10 hours.

[0034] Figure 1 Schematic diagram of the technical route.Figure 2 The particle size of the calcium silicate powder obtained by the reaction is about 28 μm, and the surface is a flower-shaped structure composed of flaky thin layers.

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

[0036] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made, and here it is impossible to enumerate all the embodiments, and any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. A method for regenerating a silicon-based core stripping fluid, characterized in that: Predicting the life of the core-removing liquid: The core-removing liquid is the solution left after the ceramic core is removed from the core-removing reactor. The core-removing liquid in the core-removing reactor is diverted, and the diverted portion of the core-removing liquid 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 at a temperature of 60-80°C. A solution stabilizer is added to the pure solution at a constant temperature of 60-80°C, which accounts for 1-10% of the volume of the pure solution. The solution is then stirred thoroughly, and the density of the solution is measured. When the solution density is greater than 1.5, the core-removing liquid is deemed to have expired and is not suitable for continued core removal. Regeneration of core-removing liquid: The failed core-removing liquid is transferred into a reactor with stirring and heat preservation functions. Lime milk is added to the failed core-removing liquid under stirring conditions to allow the potassium silicate in the solution to react with calcium hydroxide to form calcium silicate precipitate and potassium hydroxide. After the addition of lime milk, stirring is continued for a certain period of time to allow the calcium silicate to fully precipitate, and then solid-liquid separation is performed. The solution obtained after solid-liquid separation 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 realizing the regeneration of the failed core-removing liquid.

2. The method for regenerating silicon-based core stripping fluid according to claim 1, wherein: 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 fluid according to claim 1, wherein: 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, and the other end of the feed pipe (1) is connected to the porous annular tube (2). When viewed from the side, the entire annular hollow tube is L-shaped. A plurality of discharge holes (3) are evenly arranged on the outer circumference of the porous annular tube (2).

4. The method for regenerating silicon-based core stripping fluid according to claim 3, wherein: 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 fluid according to claim 1, wherein: 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. When the core-removing liquid fails, the concentration of silicon dioxide is 20% to 30%.

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

7. The method for regenerating silicon-based core stripping fluid according to claim 1, wherein: The effective calcium in the lime milk is 80% to 90%, and the amount of lime milk added is in a 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, wherein: The stirring speed when adding lime milk is 80r / min~120r / min, and the stirring time after adding lime milk is continued to be 40min~80min.

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