A composite phase change heat storage ceramsite prepared from waste incineration fly ash and nickel-iron slag and a preparation method thereof

Abstract

The application discloses a kind of composite phase change heat storage ceramsite prepared by waste incineration fly ash and nickel-iron slag and a preparation method thereof.The waste incineration fly ash, nickel-iron slag and phase change material are made into double-layer composite pellets in the application, and the pellets are dried, calcined and cooled to obtain the phase change heat storage ceramsite.By controlling the inner layer of the pellets to be a mixture of waste incineration fly ash, nickel-iron slag and phase change material, and the outer layer to be a mixture of waste incineration fly ash and nickel-iron slag, the internal porosity of the ceramsite can be guaranteed, the surface presents a dense glaze layer, and the phase change material is well encapsulated.The obtained phase change heat storage ceramsite product has the characteristics of lightweight, high strength and good stability, and realizes the collaborative high-value utilization of waste incineration fly ash and nickel-iron slag.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for resource utilization of waste incineration fly ash and nickel-iron slag, in particular to a composite phase change heat storage ceramsite prepared from waste incineration fly ash and nickel-iron slag and a preparation method thereof, belonging to the field of environmental protection technology. BACKGROUND

[0002] Heat storage technology is an effective means to solve the mismatch between energy supply and consumption in time and space. Phase change heat storage material is a commonly used heat storage method, and the principle of phase change heat storage is to complete heat storage and release by using the heat absorption or release effect of material phase change. Due to the flowability of liquid phase in the phase change process, there is a risk of leakage, which seriously limits its industrial application. At present, composite phase change material is a research hotspot to ensure that there is no phase change material leakage. Composite phase change material is composed of phase change material and supporting matrix, wherein the phase change material acts as a working medium to complete energy storage and release by phase change, and the supporting matrix is used to maintain the stable shape of the composite phase change heat storage material in the working state. Composite phase change heat storage material not only can overcome the shortcomings of solid-liquid phase change heat storage material, but also can fully utilize the sensible heat of matrix material to increase the heat storage density of phase change material. When selecting composite phase change heat storage material, the characteristics and applicability of both phase change material and supporting matrix should be considered. On the one hand, phase change material and supporting matrix should not react with each other and have excellent chemical compatibility. On the other hand, the supporting matrix should well confine the phase change material in the skeleton without leakage. However, the current composite phase change heat storage material still has problems such as high preparation difficulty, easy leakage and high cost.

[0003] The inventors found in the previous study that waste incineration fly ash and nickel-iron slag can be used to prepare high-strength ceramsite. The internal structure of the ceramsite is loose and porous, and the surface is dense glaze layer. The main phases are diopside and magnesium olivine, which have excellent stability. Therefore, the ceramsite prepared from fly ash and nickel-iron slag has the potential to be used as a supporting matrix for composite phase change heat storage material. Nickel-iron slag is the fourth largest industrial solid waste in China, and fly ash is a hazardous waste. Both of them are difficult to dispose. If fly ash and nickel-iron slag can be used to prepare composite phase change heat storage ceramsite, not only can it provide low-cost raw materials for the preparation of composite phase change heat storage material, but also can realize the high-value utilization of fly ash and nickel-iron slag, which has significant economic and environmental benefits. SUMMARY

[0004] In view of the problems of composite phase change heat storage material, such as great difficulty in preparation, easy leakage and high cost, the present application aims to provide a method for preparing composite phase change heat storage ceramsite by using waste incineration fly ash and nickel-iron slag. The method uses the ceramsite formed by fly ash and nickel-iron slag in the roasting process as the support matrix of the composite phase change heat storage material, which has loose and porous interior and dense glaze layer on the surface. At the same time, by constructing double-layered pellets, the wrapping effect of the phase change material is strengthened, and space is created for the phase change process, reducing the volume change and enhancing the structural stability. The present application can realize the collaborative high-value utilization of fly ash and nickel-iron slag, turning waste into treasure, and the obtained composite phase change heat storage ceramsite product has excellent performance.

[0005] The technical solutions specifically adopted in the present application are as follows:

[0006] The preparation of the composite phase change heat storage ceramsite includes the following steps:

[0007] (1) Mix fly ash, nickel-iron slag, phase change material and water uniformly to form a mixture A; mix fly ash, nickel-iron slag and water uniformly to form a mixture B; during the pelletizing process, first add the mixture A to form an inner layer pellet, then add the mixture B to form an outer layer, i.e. obtain a double-layered pellet;

[0008] (2) After drying the pellet, roast it at 900°C~1100°C for 30min~90min, and then cool it to obtain the phase change heat storage ceramsite.

[0009] As a preferred embodiment, in the mixture A, the mass ratio of fly ash, nickel-iron slag and phase change material is (0.2~0.3):1:(0.4~0.5); in the mixture B, the mass ratio of fly ash and nickel-iron slag is (0.1~0.2):1.

[0010] As a preferred embodiment, the roasting temperature is 950°C~1050°C.

[0011] As a preferred embodiment, the roasting time is 60min~90min.

[0012] Compared with the prior art, the present application has the following beneficial effects:

[0013] The composite phase change heat storage ceramsite prepared by using waste incineration fly ash and nickel-iron slag is based on a large number of experimental conclusions, and the inventors have found that the ball structure, fly ash, nickel-iron slag and phase change material ratio, roasting temperature, heating rate and roasting time are key factors through a large number of researches on the influencing factors of the preparation process of the composite phase change heat storage ceramsite. Therefore, the inventors carried out systematic experimental researches, and summarized that the mass ratio of fly ash, nickel-iron slag and phase change material in the internal mixture of the double-layer ball is (0.1-0.4):1:(0.2-0.5), the mass ratio of fly ash and nickel-iron slag in the external mixture is (0.1-0.4):1, the roasting temperature is 950°C-1050°C, and the roasting time is 60 min-90 min. By adjusting the ball structure, raw material ratio and roasting parameters, the nickel-iron slag and fly ash can react to generate diopside and magnesium olivine to form a support matrix, and the liquid phase formed by the phase change material can strengthen the mass transfer process and improve the sintering effect. At the same time, the gas generated by the volatilization and decomposition of dioxin and heavy metal chlorides in fly ash serves as a gas-forming component, forming an internal loose porous structure. By further synergistically adjusting the heating rate and roasting time, the bubble generation rate in the process is indirectly adjusted, thereby forming closed pores with uniform pore size and uniform distribution, further ensuring the strength of the obtained ceramsite. At the same time, by synergistically adjusting the ball structure, fly ash, nickel-iron slag and phase change material ratio, roasting temperature, heating rate and roasting time, the fly ash and nickel-iron slag can be completely detoxified while ensuring excellent encapsulation of the phase change material and excellent performance of the composite phase change heat storage ceramsite. In addition, the high content of sodium chloride and potassium chloride in fly ash can be used as a phase change material to improve the latent heat of fusion and heat storage density of the phase change heat storage ceramsite. Overall, by precisely adjusting the preparation process, not only can the composite phase change heat storage ceramsite product with excellent performance be obtained, but also the synergistic high-value utilization of fly ash and nickel-iron slag can be realized, which has a broad application prospect. DETAILED DESCRIPTION

[0014] The content of the present application will be further described in detail below in combination with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application. Embodiment 1

[0015] In this embodiment, fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A; fly ash, nickel-iron slag and water are mixed uniformly to form a mixture B; during the balling process, the mixture A is first added to form an inner layer ball, and then the mixture B is added to form an outer layer, i.e. a double-layer ball is obtained; after drying and roasting, the composite phase change heat storage ceramsite is obtained.

[0016] In the embodiment, the mass ratio of fly ash, nickel-iron slag and phase change material in the mixture A is 0.2:1:0.5; the mass ratio of fly ash and nickel-iron slag in the mixture B is 0.2:1.

[0017] In the embodiment, the phase change material is sodium fluoride.

[0018] In the embodiment, the diameter of the inner layer sphere is 10 mm, and the thickness of the outer layer is 2 mm.

[0019] In the embodiment, the roasting temperature is 1050°C, and the roasting time is 60 min.

[0020] In the embodiment, the temperature rising rate is 10°C / min from room temperature to 800°C, and the temperature rising rate is 2°C / min above 800°C.

[0021] The composite phase change heat storage ceramsite obtained in the embodiment 1 has a latent heat of fusion of 110 J / g, a heat storage density of 520 J / g, and a cylinder compressive strength of 48 MPa. Embodiment 2

[0022] In the embodiment, fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A; fly ash, nickel-iron slag and water are mixed uniformly to form a mixture B; during the process of balling, the mixture A is first added to form an inner layer sphere, and then the mixture B is added to form an outer layer, so that a double-layered ball is obtained; the ball is dried, roasted and cooled to obtain a composite phase change heat storage ceramsite.

[0023] In the embodiment, the mass ratio of fly ash, nickel-iron slag and phase change material in the mixture A is 0.1:1:0.5; the mass ratio of fly ash and nickel-iron slag in the mixture B is 0.2:1.

[0024] In the embodiment, the phase change material is sodium fluoride.

[0025] In the embodiment, the diameter of the inner layer sphere is 8 mm, and the thickness of the outer layer is 2 mm.

[0026] In the embodiment, the roasting temperature is 1100°C, and the roasting time is 90 min.

[0027] In the embodiment, the temperature rising rate is 10°C / min from room temperature to 800°C, and the temperature rising rate is 2°C / min above 800°C.

[0028] The composite phase change heat storage ceramsite obtained in the embodiment 2 has a latent heat of fusion of 93 J / g, a heat storage density of 490 J / g, and a cylinder compressive strength of 43 MPa. Embodiment 3

[0029] The fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A in the embodiment; the fly ash, nickel-iron slag and water are mixed uniformly to form a mixture B; the mixture A is added first to form an inner layer sphere in the process of balling, and then the mixture B is added to form an outer layer, so that the double-layered pellet is obtained; and the pellet is dried, roasted and cooled to obtain the composite phase change heat storage ceramic particles.

[0030] In the embodiment, the mass ratio of the fly ash, nickel-iron slag and phase change material in the mixture A is 0.4:1:0.2; and the mass ratio of the fly ash and nickel-iron slag in the mixture B is 0.4:1.

[0031] In the embodiment, the phase change material is sodium sulfate and sodium chloride.

[0032] In the embodiment, the diameter of the inner layer sphere is 10 mm, and the thickness of the outer layer is 2 mm.

[0033] In the embodiment, the roasting temperature is 1050°C, and the roasting time is 60 min.

[0034] In the embodiment, the temperature rising rate is 10°C / min at room temperature to 800°C, and the temperature rising rate is 2°C / min above 800°C.

[0035] The composite phase change heat storage ceramic particles obtained in the embodiment 3 have a latent heat of fusion of 80 J / g, a heat storage density of 480 J / g and a cylinder compressive strength of 35 MPa. Embodiment 4

[0036] The fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A in the embodiment; the fly ash, nickel-iron slag and water are mixed uniformly to form a mixture B; the mixture A is added first to form an inner layer sphere in the process of balling, and then the mixture B is added to form an outer layer, so that the double-layered pellet is obtained; and the pellet is dried, roasted and cooled to obtain the composite phase change heat storage ceramic particles.

[0037] In the embodiment, the mass ratio of the fly ash, nickel-iron slag and phase change material in the mixture A is 0.2:1:0.5; and the mass ratio of the fly ash and nickel-iron slag in the mixture B is 0.2:1.

[0038] In the embodiment, the phase change material is sodium fluoride.

[0039] In the embodiment, the diameter of the inner layer sphere is 8 mm, and the thickness of the outer layer is 4 mm.

[0040] In the embodiment, the roasting temperature is 1050°C, and the roasting time is 60 min.

[0041] In the embodiment, the temperature rising rate is 9°C / min from room temperature to 800°C, and the temperature rising rate is 2°C / min above 800°C.

[0042] The composite phase change heat storage ceramic granule obtained in the embodiment 4 has a melting latent heat of 92J / g, a heat storage density of 492J / g, and a cylinder compression strength of 39MPa. Embodiment 5

[0043] In the embodiment, the fly ash, the nickel-iron slag, the phase change material and the water are mixed uniformly to form a mixture A; the fly ash, the nickel-iron slag and the water are mixed uniformly to form a mixture B; the mixture A is added first to form an inner layer of the spheroids, and then the mixture B is added to form an outer layer, so that the double-layered spheroids are obtained; and the spheroids are dried and roasted to obtain the composite phase change heat storage ceramic granule.

[0044] In the embodiment, the mass ratio of the fly ash, the nickel-iron slag and the phase change material in the mixture A is 0.2:1:0.5; and the mass ratio of the fly ash and the nickel-iron slag in the mixture B is 0.2:1.

[0045] In the embodiment, the phase change material is sodium fluoride, sodium chloride and potassium chloride.

[0046] In the embodiment, the diameter of the inner layer of the spheroids is 10mm, and the thickness of the outer layer is 2mm.

[0047] In the embodiment, the roasting temperature is 900°C, and the roasting time is 30min.

[0048] In the embodiment, the temperature rising rate is 8°C / min from room temperature to 800°C, and the temperature rising rate is 3°C / min above 800°C.

[0049] The composite phase change heat storage ceramic granule obtained in the embodiment 5 has a melting latent heat of 83J / g, a heat storage density of 483J / g, and a cylinder compression strength of 37MPa.

[0050] From the results of the above embodiments 1-5, it can be illustrated that the key of the technical scheme of the present application is the spheroid structure and the mixture ratio, in addition to the raw material components, the temperature rising rate, the roasting temperature and the roasting time need to be synergistically controlled.

[0051] In order to further prove the necessity of the spheroid structure, the mixture ratio control and the roasting condition control, the present application further provides several comparative examples. Comparative Example 1

[0052] The fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A in the present comparative example; the fly ash, nickel-iron slag and water are mixed uniformly to form a mixture B; the mixture A is added first to form an inner layer sphere in the process of balling, and then the mixture B is added to form an outer layer, i.e. a double-layered pellet is obtained; the pellet is dried, roasted and cooled to obtain the composite phase change heat storage ceramic granule.

[0053] In the present comparative example, the mass ratio of the fly ash, nickel-iron slag and phase change material in the mixture A is 0.05:1:0.1; the mass ratio of the fly ash and nickel-iron slag in the mixture B is 0.2:1.

[0054] In the present comparative example, the phase change material is sodium fluoride.

[0055] In the present comparative example, the diameter of the inner layer sphere is 10 mm, and the thickness of the outer layer is 2 mm.

[0056] In the present comparative example, the roasting temperature is 1050°C, and the roasting time is 60 min.

[0057] In the present comparative example, the temperature rising rate is 10°C / min from room temperature to 800°C, and the temperature rising rate is 2°C / min above 800°C.

[0058] The composite phase change heat storage ceramic granule obtained in Comparative Example 1 has a latent heat of fusion of 50 J / g, a heat storage density of 310 J / g, and a cylinder compressive strength of 8 MPa. Comparative Example 2

[0059] The fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A in the present comparative example; the fly ash, nickel-iron slag and water are mixed uniformly to form a mixture B; the mixture A is added first to form an inner layer sphere in the process of balling, and then the mixture B is added to form an outer layer, i.e. a double-layered pellet is obtained; the pellet is dried, roasted and cooled to obtain the composite phase change heat storage ceramic granule.

[0060] In the present comparative example, the mass ratio of the fly ash, nickel-iron slag and phase change material in the mixture A is 0.1:1:0.6; the mass ratio of the fly ash and nickel-iron slag in the mixture B is 0.2:1.

[0061] In the present comparative example, the phase change material is sodium sulfate.

[0062] In the present comparative example, the diameter of the inner layer sphere is 8 mm, and the thickness of the outer layer is 2 mm.

[0063] In the present comparative example, the roasting temperature is 1100°C, and the roasting time is 90 min.

[0064] In the present comparative example, the temperature rising rate is 10°C / min from room temperature to 800°C, and the temperature rising rate is 2°C / min above 800°C.

[0065] The composite phase change heat storage ceramic granule obtained in the present comparative example 2 has a melting latent heat of 61J / g, a heat storage density of 261J / g, and a cylinder compression strength of 5MPa. Comparative example 3

[0066] In the present comparative example, fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A, and fly ash and water are mixed uniformly to form a mixture B. The mixture A is added first to form an inner sphere, and then the mixture B is added to form an outer layer, so as to obtain a double-layered ball. After drying and roasting, the composite phase change heat storage ceramic granule is obtained.

[0067] In the present comparative example, the mass ratio of fly ash, nickel-iron slag and phase change material in the mixture A is 0.4:1:0.2.

[0068] In the present comparative example, the phase change material is sodium sulfate and sodium chloride.

[0069] In the present comparative example, the diameter of the inner sphere is 12mm.

[0070] In the present comparative example, the roasting temperature is 1050°C, and the roasting time is 60min.

[0071] In the present comparative example, the temperature rising rate is 10°C / min from room temperature to 800°C, and the temperature rising rate is 2°C / min above 800°C.

[0072] The composite phase change heat storage ceramic granule obtained in the present comparative example 3 has a melting latent heat of 40J / g, a heat storage density of 160J / g, and a cylinder compression strength of 10MPa. Comparative example 4

[0073] In the present comparative example, fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A, and fly ash and water are mixed uniformly to form a mixture B. The mixture A is added first to form an inner sphere, and then the mixture B is added to form an outer layer, so as to obtain a double-layered ball. After drying and roasting, the composite phase change heat storage ceramic granule is obtained.

[0074] In the present comparative example, the mass ratio of fly ash, nickel-iron slag and phase change material in the mixture A is 0.2:1:0.5, and the mass ratio of fly ash and nickel-iron slag in the mixture B is 0.2:1.

[0075] In the present comparative example, the phase change material is sodium fluoride.

[0076] In the present comparative example, the diameter of the inner sphere is 8mm, and the thickness of the outer layer is 4mm.

[0077] In the present comparative example, the roasting temperature is 800°C, and the roasting time is 60min.

[0078] In the present comparative example, the temperature increasing rate is 10 °C / min.

[0079] The composite phase change heat storage ceramic particles obtained in Comparative Example 4 have a melting latent heat of 62 J / g, a heat storage density of 220 J / g, and a cylinder compressive strength of 2 MPa. Comparative Example 5

[0080] In the present comparative example, fly ash, nickel-iron slag, phase change material and water are mixed uniformly to form a mixture A; fly ash, nickel-iron slag and water are mixed uniformly to form a mixture B; during the balling process, the mixture A is first added to form an inner layer of the pellets, and then the mixture B is added to form an outer layer, thereby obtaining double-layered pellets; the pellets are dried, roasted, and cooled to obtain the composite phase change heat storage ceramic particles.

[0081] In the present comparative example, in the mixture A, the mass ratio of fly ash, nickel-iron slag and phase change material is 0.2:1:0.5; in the mixture B, the mass ratio of fly ash and nickel-iron slag is 0.2:1.

[0082] In the present comparative example, the phase change material is sodium fluoride, sodium chloride and potassium chloride.

[0083] In the present comparative example, the diameter of the inner layer of the pellets is 10 mm, and the thickness of the outer layer is 2 mm.

[0084] In the present comparative example, the roasting temperature is 900 °C, and the roasting time is 20 min.

[0085] In the present comparative example, the temperature increasing rate is 8 °C / min from room temperature to 800 °C, and the temperature increasing rate is 3 °C / min above 800 °C.

[0086] The composite phase change heat storage ceramic particles obtained in Comparative Example 5 have a melting latent heat of 51 J / g, a heat storage density of 183 J / g, and a cylinder compressive strength of 6 MPa.

[0087] It is apparent for those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, but can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The foregoing embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the present application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

[0088] Furthermore, it should be understood that although the description is made according to the embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and the person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be combined appropriately to form other embodiments that can be understood by the person skilled in the art.

Claims

1. A preparation method of composite phase change heat storage ceramsite prepared by using waste incineration fly ash and nickel-iron slag, characterized in that: The method comprises the following steps: ​ (1) mixing fly ash, nickel-iron slag, phase change material and water uniformly to form mixed material A; mixing fly ash, nickel-iron slag and water uniformly to form mixed material B; adding mixed material A to form inner layer spheres in the process of balling, then adding mixed material B to form outer layer, thereby obtaining double-layered pellets; (2) after drying, the double-layered pellets are calcined at 900°C-1100°C for 30min-90min, and then cooled to obtain composite phase change heat storage ceramic pellets; In the mixed material A, the mass ratio of fly ash, nickel-iron slag and phase change material is 0.1-0.4:1:0.2-0.5; in the mixed material B, the mass ratio of fly ash and nickel-iron slag is 0.1-0.4:1; The diameter of the inner layer spheres is 8-10mm, and the thickness of the outer layer is 2-4mm; The heating rate in the calcination process is: 8-10°C / min from room temperature to 800°C, and 2-3°C / min above 800°C.

2. The preparation method of the composite phase change heat storage ceramsite prepared from waste incineration fly ash and nickel-iron slag according to claim 1, characterized in that: The phase change material is one or more of sodium sulfate, sodium fluoride, sodium chloride and potassium chloride.

3. The preparation method of the composite phase change heat storage ceramsite prepared from waste incineration fly ash and nickel-iron slag according to claim 1, characterized in that: The calcination temperature is 950°C-1050°C, and the calcination time is 60min-90min.

4. The preparation method of the composite phase change heat storage ceramsite prepared from waste incineration fly ash and nickel-iron slag according to claim 1, characterized in that: The composite phase change heat storage ceramic pellets have a latent heat of fusion of 80J / g-110J / g, a heat storage density of 480J / g-520J / g, and a cylinder compressive strength of 35MPa-48MPa.