Special plastic concrete for circulating fluidized bed boiler and its preparation method

Abstract

The application provides a special plastic concrete for circulating fluidized bed boilers and a preparation method thereof. In the binder, vinyl siloxane and octadecyl acrylate functional monomers are used to improve the bonding strength, styrene is used to improve the high-temperature resistance of the binder, and a pre-emulsified semi-continuous emulsion polymerization is used to obtain a polyacrylate thermoplastic resin with a core-shell structure as the binder, thereby improving the pressure resistance, heat insulation, high-temperature resistance and durability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of refractory materials, and particularly relates to a special plastic concrete for circulating fluidized bed boilers and a preparation method thereof. BACKGROUND

[0002] The circulating fluidized bed boiler of a power plant is a medium-large boiler for providing steam in a power plant, and needs to resist high temperature above 150 DEG C. The inner wall and the top of the boiler are paved with refractory bricks, and the surface of the refractory bricks is coated with the special plastic concrete. After drying and curing, the refractory layer is formed. During use, the surface of the refractory layer is easily abraded and eroded due to the air flow pressure and the like. Therefore, how to improve the heat insulation, pressure resistance, and fire resistance of the special plastic concrete determines the safety, stability, and service life of the whole system.

[0003] Generally, the volume shrinkage of the binder during use of the boiler is offset by adding the expanding agent, and the generation of cracks during use is prevented, thereby improving the high-temperature use performance and the normal-temperature pressure resistance of the product. A multidirectional support system is formed by adding the engineering fiber, the directional stress of the mud is dispersed, the generation and development of the original cracks in the mud are prevented, and the number of the original micro cracks is eliminated or reduced. Meanwhile, the strength of the engineering fiber itself is utilized, the fiber is uniformly dispersed in the mud and forms an anchoring effect, and the fiber can absorb a certain amount of damage energy during use of the boiler, thereby reducing the possibility of the generation of cracks in the boiler lining. However, the uneven dispersion of the engineering fiber, the expanding agent, and the like in the special plastic concrete and the insufficient bonding force of the binder easily lead to insufficient pressure resistance, heat insulation, and high-temperature resistance of the special plastic concrete. SUMMARY

[0004] In order to overcome the problems in the prior art, the purpose of the present application is to provide a special plastic concrete for circulating fluidized bed boilers and a preparation method thereof. The vinyl siloxane and the octadecyl acrylate functional monomer are used in the binder, the bonding strength is improved, the styrene is used to improve the high-temperature resistance of the binder, thereby improving the pressure resistance, heat insulation, high-temperature resistance, and durability. In addition, the pre-emulsified semi-continuous emulsion polymerization is used, a part of the monomer solution is used to coat the polyester fiber to form a core layer, and the monomer solution is added dropwise to prepare a shell layer, thereby obtaining the polyacrylate thermoplastic resin with a core-shell structure as the binder, the maximum use temperature, the pressure resistance, the thermal conductivity, and the permanent linear change performance during heating are improved, thereby improving the heat insulation, the pressure resistance, and the high-temperature resistance.

[0005] The purpose of the present application is achieved by the following technical scheme: a special plastic concrete for circulating fluidized bed boilers, the raw materials contain 20-30 parts of perlite, 30-35 parts of fly ash, 5-12 parts of silicon powder, 3-5 parts of expanding agent, 5-12 parts of coupling agent, 24-30 parts of binder, 1-3 parts of engineering fiber, 1.5-2 parts of water reducing agent, and 1-5 parts of curing agent.

[0006] Preferably, the particle size of the perlite is ≤3mm; the particle size of the expanding agent is ≤80μm.

[0007] Preferably, the expanding agent is silica powder; the water reducing agent is industrial grade sodium tripolyphosphate; the curing agent is industrial grade sodium fluorosilicate powder.

[0008] Preferably, the coupling agent is silane coupling agent.

[0009] Preferably, the engineering fiber is polyester fiber, the fiber length is 5mm-20mm, and the fiber diameter is 15μm-40μm.

[0010] Preferably, the binder is core-shell structure polyacrylate thermoplastic resin, which is formed by in-situ polymerization of methyl methacrylate, styrene, dodecyl acrylate, and vinyl siloxane in the presence of polyester fiber.

[0011] Preferably, the preparation method of the binder comprises:

[0012] Step one, mixing 5-10 parts of KH570 modified polyester fiber, 100 parts of deionized water, and 2-5 parts of initiator azobisisobutyronitrile to prepare solution A;

[0013] Step two, mixing 25-60 parts of methyl methacrylate, 5-18 parts of styrene, 5-10 parts of octadecyl acrylate, 5-10 parts of vinyl siloxane, 5-10 parts of emulsifier, and 100 parts of deionized water to prepare solution B by ultrasonic stirring;

[0014] Step three, adding solution A and 1 / 5 of solution B into a reaction kettle, stirring uniformly, and heating to 50-80℃, reacting for 0.5-1h to form a core emulsion, continuously adding the remaining solution B, the dropping time is 4-6h, after the dropping is completed, adding 0.5-1 parts of redox initiator, and continuing to react for 1-2h, and cooling to room temperature to obtain core-shell structure polyacrylate thermoplastic resin.

[0015] Preferably, the vinyl siloxane, emulsifier, and redox initiator can be common compounds in the field.

[0016] Preferably, the mass ratio of solution A and solution B is 1:10-50.

[0017] Preferably, the polyester fiber used in the KH570 modified polyester fiber has a length of 3mm-5mm and a fiber diameter of 10μm-15μm.

[0018] A preparation method of a special plastic concrete for circulating fluidized bed boilers, comprising the following reaction steps:

[0019] Step one, according to the proportioning, each raw material is weighed;

[0020] Step two, under the condition of 10-35℃, perlite, fly ash, silica powder, expanding agent, coupling agent are mixed and stirred for 3-10min, to obtain mixed material A, standby; the binder, engineering fiber, water reducing agent, curing agent are mixed and stirred for 3-10min, to obtain mixed material B, standby; then mixed material A and mixed material B are mixed, after stirring uniformly, the circulating fluidized bed boiler special plastic concrete is obtained.

[0021] The beneficial effects of the present application are:

[0022] 1, the circulating fluidized bed boiler special plastic concrete of the present application, in the binder, vinyl siloxane, octadecyl acrylate functional monomer can improve the bonding strength, using styrene can improve the high temperature resistance of the binder, and then improve the compressive strength, high temperature resistance and durability of the circulating fluidized bed boiler special plastic concrete.

[0023] 2, the binder of the present application, by adding polyester fiber in situ to prepare polyacrylate thermoplastic resin with core-shell structure as binder, can make polyester fiber better dispersed in plastic concrete composition, make the components in the composition, such as binder, engineering fiber, perlite, fly ash, silica powder, expanding agent, evenly dispersed, fully play the role, so as to improve the maximum use temperature, compressive strength, thermal conductivity, heating permanent linear change performance, and then improve the heat insulation, compressive strength and high temperature resistance of the circulating fluidized bed boiler special plastic concrete.

[0024] 3, the binder of the present application, using pre emulsified semi continuous emulsion method, first use part of the monomer solution to coat the polyester fiber to form the core layer, then drop the monomer solution to prepare the shell layer, which can lock the polyester fiber in the core layer, and in situ polymerization on the surface of the core layer to form a layer of polyacrylate polymer, so that the polyester fiber is fully and uniformly dispersed in the polyacrylate binder, and forms an island structure in the circulating fluidized bed boiler special plastic concrete composition, further improves the compressive strength and high temperature resistance of the circulating fluidized bed boiler special plastic concrete. DETAILED DESCRIPTION

[0025] The technical solutions of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0026] The present application will be further explained and described below in conjunction with specific embodiments.

[0027] Preparation example 1

[0028] A polyacrylate thermoplastic resin binder is formed by in-situ polymerization in the presence of polyester fibers using methyl methacrylate, styrene, dodecyl acrylate, and vinyl siloxane as raw materials. Specifically, the following reaction steps are included:

[0029] Step one, KH570 modified polyester fibers 45 parts, deionized water 100 parts, initiator azobisisobutyronitrile 2 parts are mixed to prepare solution A;

[0030] Step two, methyl methacrylate 30 parts, styrene 8 parts, octadecyl acrylate 5 parts, KH570 5 parts, emulsifier SDS 8 parts, deionized water 100 parts are mixed to prepare solution B by ultrasonic stirring;

[0031] Step three, solution A and 1 / 5 of solution B are added to the reaction kettle, ultrasonic stirring is performed, stirring and heating to 65℃, reaction for 0.5h, forming a core emulsion, continue to add the remaining solution B, the dropwise adding time is 5h, after the dropwise adding is completed, supplement 0.8 parts of redox initiator potassium sulfate / sodium sulfite, continue to react for 1.5h, cool to room temperature, to obtain a polyacrylate thermoplastic resin with core-shell structure. The mass ratio of solution A and solution B is 1:10. The polyester fiber length of the KH570 modified polyester fiber used is 3mm, and the fiber diameter is 10μm.

[0032] Preparation Example 2

[0033] A polyacrylate thermoplastic resin binder is formed by in-situ polymerization in the presence of polyester fibers using methyl methacrylate as a raw material. Specifically, the following reaction steps are included:

[0034] Step one, KH570 modified polyester fibers 45 parts, deionized water 100 parts, initiator azobisisobutyronitrile 2 parts are mixed to prepare solution A;

[0035] Step two, methyl methacrylate 48 parts, emulsifier SDS 8 parts, deionized water 100 parts are mixed to prepare solution B by ultrasonic stirring;

[0036] Step three, solution A and 1 / 5 of solution B are added to the reaction kettle, ultrasonic stirring is performed, stirring and heating to 65℃, reaction for 0.5h, forming a core emulsion, continue to add the remaining solution B, the dropwise adding time is 5h, after the dropwise adding is completed, supplement 0.8 parts of redox initiator potassium sulfate / sodium sulfite, continue to react for 1.5h, cool to room temperature, to obtain a polyacrylate thermoplastic resin with core-shell structure. The mass ratio of solution A and solution B is 1:10. The polyester fiber length of the KH570 modified polyester fiber used is 3mm, and the fiber diameter is 10μm.

[0037] Preparation Example 3

[0038] A polyacrylate thermoplastic resin binder is formed by in-situ polymerization using methyl methacrylate, styrene, dodecyl acrylate, and vinyl siloxane as raw materials in the presence of polyester fiber. Specifically, the following reaction steps are included:

[0039] Step one, 45 parts of KH570 modified polyester fiber, 100 parts of deionized water, 2 parts of initiator azobisisobutyronitrile are mixed to prepare solution A;

[0040] Step two, 30 parts of methyl methacrylate, 8 parts of styrene, 5 parts of stearyl acrylate, 5 parts of KH570, 8 parts of emulsifier SDS, 100 parts of deionized water are mixed to prepare solution B by ultrasonic stirring;

[0041] Step three, solution A and solution B are added to the reaction kettle, ultrasonic stirring is uniform, the temperature is raised to 65℃ by stirring, and the reaction is carried out for 5h, then 0.8 parts of redox initiator potassium sulfate / sodium sulfite is added, and the reaction is continued for 1.5h, and then the temperature is lowered to room temperature to obtain the polyacrylate thermoplastic resin. The mass ratio of solution A and solution B is 1:10. The polyester fiber used in the KH570 modified polyester fiber has a length of 3mm and a fiber diameter of 10μm.

[0042] Preparation example 4

[0043] A polyacrylate thermoplastic resin binder is formed by in-situ polymerization using methyl methacrylate, styrene, dodecyl acrylate, and vinyl siloxane as raw materials. Specifically, the following reaction steps are included:

[0044] Step one, 30 parts of methyl methacrylate, 8 parts of styrene, 5 parts of stearyl acrylate, 5 parts of KH570, 8 parts of emulsifier SDS, 100 parts of deionized water are mixed to prepare solution B by ultrasonic stirring;

[0045] Step three, solution B is added to the reaction kettle, the temperature is raised to 65℃ by stirring, and the reaction is carried out for 5h, then 0.8 parts of redox initiator potassium sulfate / sodium sulfite is added, and the reaction is continued for 1.5h, and then the temperature is lowered to room temperature to obtain the polyacrylate thermoplastic resin.

[0046] Example 1

[0047] A special plastic concrete for circulating fluidized bed boiler includes 20 parts of perlite, 35 parts of fly ash, 5 parts of silica powder, 3 parts of expanding agent, 28 parts of binder, 1 part of engineering fiber, 1.5 parts of water reducing agent, 1 part of curing agent, and 5 parts of coupling agent.

[0048] The particle size of the perlite is 2 mm; the particle size of the expanding agent is 35 μm. The expanding agent is silica powder; the water reducing agent is industrial grade sodium tripolyphosphate; the curing agent is industrial grade sodium fluorosilicate powder. The engineering fiber is polyester fiber, the fiber length is 5 mm, and the fiber diameter is 30 μm. The binder is the polyacrylate thermoplastic resin with core-shell structure prepared in Preparation Example 1.

[0049] The preparation method thereof comprises the following reaction steps:

[0050] Step one, weigh each raw material according to the proportion;

[0051] Step two, mix and stir the perlite, fly ash, silica powder, expanding agent and coupling agent at 25°C for 5 min to obtain a mixture A for standby; mix and stir the binder, engineering fiber, water reducing agent and curing agent for 5 min to obtain a mixture B for standby; then mix the mixture A and the mixture B, and stir uniformly to obtain the special plastic concrete for circulating fluidized bed boiler.

[0052] Comparative Example 1

[0053] A special plastic concrete for circulating fluidized bed boiler, comprising 20 parts of perlite, 35 parts of fly ash, 5 parts of silica powder, 3 parts of expanding agent, 28 parts of binder, 1 part of engineering fiber, 1.5 parts of water reducing agent, 1 part of curing agent and 5 parts of coupling agent.

[0054] The particle size of the perlite is 2 mm; the particle size of the expanding agent is 35 μm. The expanding agent is silica powder; the water reducing agent is industrial grade sodium tripolyphosphate; the curing agent is industrial grade sodium fluorosilicate powder. The engineering fiber is polyester fiber, the fiber length is 5 mm, and the fiber diameter is 30 μm. The binder is the polyacrylate thermoplastic resin with core-shell structure prepared in Preparation Example 2.

[0055] The preparation method thereof comprises the following reaction steps:

[0056] Step one, weigh each raw material according to the proportion;

[0057] Step two, mix and stir the perlite, fly ash, silica powder, expanding agent and coupling agent at 25°C for 5 min to obtain a mixture A for standby; mix and stir the binder, engineering fiber, water reducing agent and curing agent for 5 min to obtain a mixture B for standby; then mix the mixture A and the mixture B, and stir uniformly to obtain the special plastic concrete for circulating fluidized bed boiler.

[0058] Example 2

[0059] A special plastic concrete for circulating fluidized bed boiler comprises 20 parts of perlite, 35 parts of fly ash, 5 parts of silica powder, 3 parts of expanding agent, 28 parts of binder, 1 part of engineering fiber, 1.5 parts of water reducing agent, 1 part of curing agent and 5 parts of coupling agent.

[0060] The particle size of the perlite is 2 mm; the particle size of the expanding agent is 35 μm. The expanding agent is silica powder; the water reducing agent is industrial grade sodium tripolyphosphate; the curing agent is industrial grade sodium fluorosilicate powder. The engineering fiber is polyester fiber, the fiber length is 5 mm and the fiber diameter is 30 μm. The binder is the polyacrylate thermoplastic resin prepared in Preparation Example 3.

[0061] The preparation method comprises the following reaction steps:

[0062] Step one, the raw materials are weighed according to the proportion;

[0063] Step two, the perlite, fly ash, silica powder, expanding agent and coupling agent are mixed and stirred for 5 min at 25℃ to obtain a mixture A for standby; the binder, engineering fiber, water reducing agent and curing agent are mixed and stirred for 5 min to obtain a mixture B for standby; then the mixture A and the mixture B are mixed and stirred uniformly to obtain the special plastic concrete for circulating fluidized bed boiler.

[0064] Comparative Example 2

[0065] A special plastic concrete for circulating fluidized bed boiler comprises 20 parts of perlite, 35 parts of fly ash, 5 parts of silica powder, 3 parts of expanding agent, 28 parts of binder, 4 parts of engineering fiber, 1.5 parts of water reducing agent, 1 part of curing agent and 5 parts of coupling agent.

[0066] The particle size of the perlite is 2 mm; the particle size of the expanding agent is 35 μm. The expanding agent is silica powder; the water reducing agent is industrial grade sodium tripolyphosphate; the curing agent is industrial grade sodium fluorosilicate powder. The engineering fiber is polyester fiber, the fiber length is 5 mm and the fiber diameter is 30 μm. The binder is the polyacrylate thermoplastic resin prepared in Preparation Example 4.

[0067] The preparation method comprises the following reaction steps:

[0068] Step one, the raw materials are weighed according to the proportion;

[0069] Step two, the perlite, fly ash, silica powder, expanding agent and coupling agent are mixed and stirred for 5 min at 25℃ to obtain a mixture A for standby; the binder, engineering fiber, water reducing agent and curing agent are mixed and stirred for 5 min to obtain a mixture B for standby; then the mixture A and the mixture B are mixed and stirred uniformly to obtain the special plastic concrete for circulating fluidized bed boiler.

[0070] Performance test

[0071] The plastic concrete special for circulating fluidized bed boiler obtained from Examples 1-2 and Comparative Examples 1-2 was prepared according to the provisions of DL / T 777-2012, and the maximum use temperature, pressure resistance, thermal conductivity, and heating permanent linear change performance were detected and compared with the technical indexes of the unshaped thermal insulation refractory material Type II as shown in the following table.

[0072] Table 1 Plastic concrete special for circulating fluidized bed boiler

[0073]

[0074] From the comparison of Examples 1 and Comparative Example 1, it can be seen that the maximum use temperature, pressure resistance, thermal conductivity, and heating permanent linear change performance of the plastic concrete special for circulating fluidized bed boiler of Example 1 are significantly improved, which may be due to the use of octadecyl acrylate and vinyl siloxane functional monomer in the preparation of the binder, which can improve the bonding strength, and the use of styrene can increase the high temperature resistance, thereby improving the pressure resistance, high temperature resistance, and durability.

[0075] From the comparison of Examples 1, 2 and Comparative Example 2, it can be seen that the plastic concrete special for circulating fluidized bed boiler of the present application can improve the maximum use temperature, pressure resistance, thermal conductivity, and heating permanent linear change performance by adding polyester fibers in situ in the preparation of the binder, which can improve the thermal insulation, pressure resistance, and high temperature resistance, which may be due to the fact that the polyester fibers added in situ can be better dispersed in the plastic concrete composition, making the binder, engineering fibers, perlite, fly ash, silica powder, and expanding agent in the composition uniformly dispersed and fully play their roles, thereby improving the thermal insulation, pressure resistance, and high temperature resistance.

[0076] The comparison of examples 1 and 2 can see that the maximum use temperature, pressure resistance, thermal conductivity, and heating permanent linear change performance of the special plastic concrete for circulating fluidized bed boiler are improved with the increase of the coating degree of polyacrylate binder on polyester fiber, which may be due to the fact that the pre-emulsified semi-continuous emulsion polymerization is used in example 1, the polyester fiber is coated with 1 / 5 monomer solution to form a core layer, and then the monomer solution is added dropwise to prepare a shell layer, so that the polyester fiber can be well locked in the core layer and polymerized in situ on the surface of the core layer to form a layer of polyacrylate polymer, so that the polyester fiber is fully and uniformly dispersed in the polyacrylate binder, and an island structure is formed in the special plastic concrete for circulating fluidized bed boiler, so as to further improve the pressure resistance, high temperature resistance, heat insulation performance and durability; in example 2, the polyester fiber and the monomer solution are mixed and then polymerized, so that the possibility of forming a shell layer on the surface of the polyester fiber is reduced, and it is more likely to form an interpenetrating network structure with the coupling agent on the surface and the acrylate, so that the dispersion of other components such as perlite, fly ash, silica powder, expanding agent and engineering fiber is poorer than that in example 1, so that the maximum use temperature, pressure resistance, thermal conductivity and heating permanent linear change performance are deteriorated with the decrease of the coating degree of polyacrylate binder on polyester fiber.

[0077] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, which are all included in the protection scope of the present application.

Claims

1. A type of plastic concrete specifically for circulating fluidized bed boilers, characterized in that, Its raw materials include: 20-30 parts perlite, 30-35 parts fly ash, 5-12 parts silica fume, 3-5 parts expansion agent, 5-12 parts coupling agent, 24-30 parts binder, 1-3 parts engineering fiber, 1.5-2 parts water-reducing agent, and 1-5 parts curing agent. The adhesive is a core-shell structured thermoplastic polyacrylate resin, and its preparation method includes: Step 1: Mix 45 parts of KH570 modified polyester fiber, 100 parts of deionized water, and 2-5 parts of initiator azobisisobutyronitrile to prepare solution A; Step 2: Mix 25-60 parts of methyl methacrylate, 5-18 parts of styrene, 5-10 parts of octadecyl acrylate, 5-10 parts of vinylsiloxane, 5-10 parts of emulsifier, and 100 parts of deionized water, and prepare solution B by ultrasonic stirring. Step 3: Add solution A and 1 / 5 of solution B to the reaction vessel, stir evenly, and heat to 50-80℃. React for 0.5-1h to form a core emulsion. Continue to add the remaining solution B dropwise over 4-6h. After the addition is complete, add 0.5-1 part of redox initiator and continue the reaction for 1-2h. Cool to room temperature to obtain a core-shell structured polyacrylate thermoplastic resin.

2. The plastic concrete for circulating fluidized bed boilers according to claim 1, characterized in that, The mass ratio of solution A to solution B is 1:10-50.

3. The plastic concrete for circulating fluidized bed boilers according to claim 1, characterized in that, The KH570 modified polyester fiber uses polyester fibers with a length of 3mm to 5mm and a fiber diameter of 10μm to 15μm.

4. The plastic concrete for circulating fluidized bed boilers according to claim 1, characterized in that, The expanding agent is silica powder.

5. The plastic concrete for circulating fluidized bed boilers according to claim 1, characterized in that, The engineered fiber is a polyester fiber with a length of 5mm to 20mm and a diameter of 15μm to 40μm.

6. The plastic concrete for circulating fluidized bed boilers according to claim 1, characterized in that, The perlite has a particle size of ≤3mm.

7. The plastic concrete for circulating fluidized bed boilers according to claim 1, characterized in that, The particle size of the expanding agent is ≤80μm.

8. The method for preparing plastic concrete for circulating fluidized bed boilers according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Weigh each ingredient according to the proportions; Step 2: Under conditions of 10-35℃, mix perlite, fly ash, silica powder, expanding agent, and coupling agent for 3-10 minutes to obtain mixture A, which is set aside. Mix binder, engineering fiber, water-reducing agent, and curing agent and stir for 3-10 minutes to obtain mixture B, which is set aside. Then mix mixture A and mixture B together and stir evenly to obtain plastic concrete for circulating fluidized bed boilers.

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