Composite resistance reducing agent as well as preparation method and application thereof

Abstract

The invention relates to a composite resistance reducing agent and a preparation method and application thereof, and belongs to the technical field of grounding materials of electric power protection systems. The composite resistance reducing agent provided by the invention is prepared from the following components in parts by weight: 20 to 40 parts of bentonite, 20 to 30 parts of conductive cement, 20 to 30 parts of graphite and 5 to 15 parts of conductive mica powder. The bentonite, the conductive cement, the graphite and the conductive mica powder are reasonably compounded, so that the composite resistance reducing agent has good water absorption and water retention, the lower resistivity of the resistance reducing agent is kept for a long time, meanwhile, the composite resistance reducing agent can well permeate and diffuse into surrounding soil, and long-term stable work of the composite resistance reducing agent can also be guaranteed in different climatic environments. The composite resistance reducing agent does not contain inorganic salt, does not corrode various electrode materials, is non-toxic and does not have negative influence on the surrounding environment.

Description

Technical Field

[0001] The invention belongs to the technical field of grounding materials for electric power protection systems, and in particular relates to a composite resistance reducing agent and a preparation method and application thereof. Background Art

[0002] The grounding device is an important part of the lightning protection design of the power grid. When lightning strikes power equipment such as substations or internal faults occur in the power system, the grounding system can provide efficient discharge capacity for high currents to avoid equipment damage and accidents. The grounding device is mainly composed of grounding electrode materials, connectors and resistance reducing agents. The effect of the resistance reducing agent has a great influence on the size of the entire grounding resistance. The resistance reducing agent should be used in conjunction with the electrode material for a long time. Its lower resistivity will increase the cross-section of the grounding body and achieve the effect of resistance reduction.

[0003] At present, most common resistance reducing materials diffuse current by adding inorganic salts and using ion conduction. However, in dry soil environments, there is a high resistivity and ion conduction is difficult. In particular, after long-term service, inorganic salts are easily lost with soil and water, resulting in increasingly poor resistance reducing effects. At the same time, some resistance reducing agents contain corrosive agents, which are easy to corrode materials such as steel electrodes; in addition, resistance reducing materials are required to be safe, non-toxic and pollution-free. At present, the soil resistivity of mountainous areas is usually above 2000Ω﹒m. It is often difficult to make the grounding resistance meet the requirements. High-efficiency resistance reducing agents are needed to reduce the grounding resistance. At present, there are few high-efficiency resistance reducing materials.

[0004] Therefore, developing an efficient, environmentally friendly, and long-term stable resistance reducing agent is critical to improving the resistance reducing effect of grounding devices in harsh mountainous environments. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems in the above-mentioned prior art, such as poor resistance reducing ability of resistance reducing agents in high resistivity soil or mountainous areas, short life of some resistance reducing agents, unstable resistance reducing effect, corrosion, etc., and to provide a composite resistance reducing agent and its preparation method and application.

[0006] The present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a composite drag reducing agent, which comprises the following components in parts by weight: 20-40 parts of bentonite, 20-30 parts of conductive cement, 20-30 parts of graphite, and 5-15 parts of conductive mica powder.

[0008] The present invention uses a composite drag reducer made by mixing bentonite, conductive cement, graphite and conductive mica powder in a specific proportion. When mixed with water and applied between a grounding electrode and soil, a composite material with low resistivity is formed. In the present invention, bentonite has good water absorption and can retain moisture in the drag reducer material to maintain conductivity, but the drag reduction effect and anti-corrosion performance vary greatly, especially under the condition of water loss, the drag reduction effect will be greatly weakened. For this reason, the present invention adds conductive cement with stable conductivity, which has strong durability, excellent conductivity, is not affected by the environment and chemistry, and has better conductivity than the cement used in general drag reducers. Graphite is a good conductive material with stable chemical properties and corrosion resistance. It does not react with acids, alkalis, etc. and has long-term stable conductivity. Conductive mica powder is a good conductive filler that can increase the crack resistance and chemical resistance of the drag reducer, thereby improving the service life and safety performance of the drag reducer. The present invention reasonably compounds bentonite, conductive cement, graphite and conductive mica powder, so that the composite resistance reducing agent has good water absorption and water retention, and maintains a low resistivity of the resistance reducing agent for a long time, and can penetrate and diffuse into the surrounding soil well, and can also ensure its long-term stable operation in different climate environments. The composite resistance reducing agent does not contain inorganic salts, has no corrosion to various electrode materials, is non-toxic and has no negative impact on the surrounding environment.

[0009] Preferably, the composite drag reducing agent comprises the following components by weight: 25-40 parts of bentonite, 25-30 parts of conductive cement, 25-30 parts of graphite, and 8-15 parts of conductive mica powder.

[0010] Preferably, the weight ratio of the graphite to the conductive mica powder is (1.0-3.0):1; more preferably, the weight ratio of the graphite to the conductive mica powder is (2.0-3.0):1.

[0011] As a composite resistance reducing agent, the smaller the intrinsic resistivity of the conductive particles, the smaller the resistivity of the composite material; therefore, during use, the weight ratio of graphite and conductive mica powder is preferably (1.0-3.0):1, so that the resistance reducing agent has a better effect, and more preferably (2.0-3.0):1.

[0012] Preferably, the particle size of the bentonite is 100-400 mesh; more preferably, the particle size of the bentonite is 200-400 mesh.

[0013] Preferably, the fineness grade of the conductive cement is 32.5-52.5; more preferably, the fineness grade of the conductive cement is 42.5-52.5.

[0014] Preferably, the particle size of the graphite is 100-800 mesh; further, the particle size of the graphite is 200-800 mesh; further, the particle size of the graphite is 400-800 mesh.

[0015] Preferably, the particle size of the conductive mica powder is 200-800 mesh; further, the particle size of the conductive mica powder is 300-800 mesh; further, the particle size of the conductive mica powder is 400-800 mesh.

[0016] The particle size of each component in the composite drag reducing agent will affect the water absorption and conductivity of the drag reducing agent. When the particle size of each component is within the above range, the drag reducing agent can have a better drag reducing effect.

[0017] In a second aspect, the present invention provides a method for preparing the composite drag reducing agent, comprising the following steps: uniformly mixing the components according to the aforementioned weight proportions to obtain the composite drag reducing agent.

[0018] The composite drag reducing agent of the invention has simple production process, convenient preparation method, extensive raw materials and good construction performance.

[0019] In a third aspect, the present invention provides application of the composite resistance reducing agent in reducing soil resistivity.

[0020] As a preferred embodiment of the application of the composite resistance reducing agent of the present invention in reducing soil resistivity, the composite resistance reducing agent can be used after being mixed with water; preferably, the weight ratio of the composite resistance reducing agent to water is 0.5 to 1.0.

[0021] In view of the characteristics of high resistivity soil in mountainous areas, the drag reducer is required to have a good drag reduction effect, be stable and effective for a long time, and not be corrosive, non-toxic and pollution-free. The present invention selects conductive cement, graphite and conductive mica powder as good conductive filling materials, which have low resistivity and will not react with each other; compared with traditional single copper powder, aluminum powder, etc., the price is low, and it is not easy to oxidize and has a long service life. Bentonite has strong water absorption and water retention. Adding bentonite to the above-mentioned composite drag reducer can be used for a long time and stably during use. When mixed with water and applied between the grounding electrode and the soil, the moisture of the medium around the electrode is maintained, and the cross-section of the grounding body is increased by coupling with the composite drag reducer, which has a drag reduction effect. Compared with traditional drag reducers, the drag reducer does not contain inorganic salts, is not corrosive, and will not corrode the electrode material. It is suitable for various types of grounding electrode materials; at the same time, it will not be washed away by rainwater, resulting in a decrease in its drag reduction effect, and can effectively reduce the grounding resistance for a long time, especially suitable for high soil resistivity areas such as mountains; it will not be affected by the rainy season or dry season environment, resulting in large-scale fluctuations in the drag reduction effect. During use, it only needs to be mixed with water in proportion. It is easy to operate and has good economy and technicality as a whole.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention obtains a high-efficiency, long-life, pollution-free composite drag reducing agent by mixing bentonite, conductive cement, graphite and conductive mica powder in a specific proportion. When the composite drag reducing agent is mixed with water and applied between the grounding electrode and the soil, a composite material with low resistivity is formed. The material itself has a relatively low resistance, and compared with a single drag reducing agent material, it has good water absorption and water retention, and can maintain a low resistivity of the drag reducing agent for a long time. At the same time, it can penetrate well into the surrounding soil to ensure long-term stable operation. The composite drag reducing agent does not contain inorganic salts, is non-corrosive to various electrode materials, is non-toxic, and has no negative impact on the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The composite drag reducing agent of Example 1 and the drag reducing agent material obtained by mixing the composite drag reducing agent with water are shown in FIG. Figure 1 A is a composite drag reducing agent, Figure 1 B is the drag reducing agent material obtained by mixing the composite drag reducing agent with water. DETAILED DESCRIPTION

[0025] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0026] Unless otherwise specified, the experimental methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0027] Example 1

[0028] A composite drag reducing agent comprises the following components by weight: 30 parts of bentonite with a particle size of 300 meshes; 28 parts of conductive cement with a fineness of 42.5; 28 parts of graphite with a particle size of 400 meshes; and 13 parts of conductive mica powder with a particle size of 600 meshes.

[0029] The preparation method of the composite drag reducing agent comprises the following steps: mixing the components uniformly according to the weight parts to obtain the composite drag reducing agent, the physical diagram of which is as follows: Figure 1 As shown in A.

[0030] The composite drag reducing agent and water are mixed at a weight ratio of 0.7 to obtain a drag reducing agent material, as shown in the figure. Figure 1 As shown in B.

[0031] Example 2

[0032] A composite drag reducing agent comprises the following components by weight: 25 parts of bentonite with a particle size of 300 meshes; 30 parts of conductive cement with a fineness of 42.5; 30 parts of graphite with a particle size of 400 meshes; and 15 parts of conductive mica powder with a particle size of 600 meshes.

[0033] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0034] The composite drag reducing agent and water are mixed in a weight ratio of 0.8 to obtain a drag reducing agent material.

[0035] Example 3

[0036] A composite drag reducing agent comprises the following components by weight: 40 parts of bentonite with a particle size of 300 meshes; 25 parts of conductive cement with a fineness of 42.5; 25 parts of graphite with a particle size of 400 meshes; and 10 parts of conductive mica powder with a particle size of 600 meshes.

[0037] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0038] The composite drag reducing agent and water are mixed in a weight ratio of 0.6 to obtain a drag reducing agent material.

[0039] Example 4

[0040] A composite drag reducing agent comprises the following components by weight: 30 parts of bentonite with a particle size of 200 meshes; 28 parts of conductive cement with a fineness of 52.5; 28 parts of graphite with a particle size of 400 meshes; and 13 parts of conductive mica powder with a particle size of 600 meshes.

[0041] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0042] The composite drag reducing agent and water are mixed in a weight ratio of 0.7 to obtain a drag reducing agent material.

[0043] Example 5

[0044] A composite drag reducing agent comprises the following components by weight: 30 parts of bentonite with a particle size of 400 meshes; 28 parts of conductive cement with a fineness of 52.5; 28 parts of graphite with a particle size of 800 meshes; and 13 parts of conductive mica powder with a particle size of 800 meshes.

[0045] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0046] The composite drag reducing agent and water are mixed in a weight ratio of 0.7 to obtain a drag reducing agent material.

[0047] Example 6

[0048] A composite drag reducing agent comprises the following components by weight: 30 parts of bentonite with a particle size of 100 meshes; 28 parts of conductive cement with a fineness of 32.5; 28 parts of graphite with a particle size of 100 meshes; and 13 parts of conductive mica powder with a particle size of 200 meshes.

[0049] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0050] The composite drag reducing agent and water are mixed in a weight ratio of 0.7 to obtain a drag reducing agent material.

[0051] Comparative Example 1

[0052] A composite drag reducing agent comprises the following components by weight: 60 parts of bentonite with a particle size of 300 meshes; 15 parts of conductive cement with a fineness of 42.5; 15 parts of graphite with a particle size of 400 meshes; and 10 parts of conductive mica powder with a particle size of 600 meshes.

[0053] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0054] The composite drag reducing agent and water are mixed in a weight ratio of 0.7 to obtain a drag reducing agent material.

[0055] Comparative Example 2

[0056] A composite resistance reducing agent comprises the following components by weight: 50 parts of conductive cement with a fineness of 42.5; 30 parts of graphite with a particle size of 400 meshes; and 20 parts of conductive mica powder with a particle size of 600 meshes.

[0057] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0058] The composite drag reducing agent and water are mixed in a weight ratio of 0.7 to obtain a drag reducing agent material.

[0059] Comparative Example 3

[0060] A composite drag reducing agent comprises the following components by weight: 60 parts of bentonite with a particle size of 300 meshes; 25 parts of conductive cement with a fineness of 42.5; and 15 parts of conductive mica powder with a particle size of 600 meshes.

[0061] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0062] The composite drag reducing agent and water are mixed in a weight ratio of 0.7 to obtain a drag reducing agent material.

[0063] Comparative Example 4

[0064] A composite drag reducing agent comprises the following components by weight: 30 parts of bentonite with a particle size of 300 meshes; 28 parts of conductive cement with a fineness of 42.5; and 28 parts of graphite with a particle size of 400 meshes.

[0065] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0066] The composite drag reducing agent and water are mixed in a weight ratio of 0.7 to obtain a drag reducing agent material.

[0067] Comparative Example 5

[0068] A composite drag reducing agent comprises the following components by weight: 30 parts of bentonite with a particle size of 300 meshes; 28 parts of conductive cement with a fineness of 42.5; 28 parts of graphite with a particle size of 400 meshes; and 2 parts of ammonium carbonate with a particle size of 50 meshes.

[0069] The preparation method of the composite drag reducing agent comprises the following steps: uniformly mixing the components according to the weight portions to obtain the composite drag reducing agent.

[0070] The composite drag reducing agent and water are mixed in a weight ratio of 0.7 to obtain a drag reducing agent material.

[0071] Performance Testing

[0072] The following performance tests were performed on the drag reducing agent materials of each embodiment and comparative example:

[0073] The grounding device was constructed and accepted in accordance with DL / T 5852-2022 "Construction and Acceptance Specifications for Grounding Devices in Electrical Installation Engineering", and then the three-pole method was used according to DL / T475-2006 "Guidelines for Measurement of Characteristic Parameters of Grounding Devices". CG =4L, L=10m, the ground impedance (i.e. ground resistance) was measured on the first day, sixth month and first year after the completion of the resistance reducing agent material construction; the experimental results are shown in Table 1 below.

[0074] Table 1 Grounding resistance of resistance reducing agent materials in various embodiments and comparative examples

[0075]

[0076] As can be seen from Table 1, the composite drag reducing agent prepared by mixing bentonite, conductive cement, graphite and conductive mica powder in a specific ratio in the present invention can effectively reduce drag for a long time.

[0077] In Comparative Example 1, the component content is not good, resulting in a decrease in the synergistic effect between the components, thereby resulting in a decrease in the resistance reducing effect of the resistance reducing agent. In Comparative Examples 2-4, a certain component is missing, and the resistance reducing effect of the resistance reducing agent cannot be reasonably improved. In Comparative Example 5, a common inorganic salt is used to replace the conductive mica powder, which is not well compounded with the other components, and the effect of the resistance reducing agent is significantly reduced.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A composite drag reducing agent, characterized in that: The invention comprises the following components by weight: 20-40 parts of bentonite, 20-30 parts of conductive cement, 20-30 parts of graphite and 5-15 parts of conductive mica powder.

2. The composite drag reducing agent according to claim 1, characterized in that: The invention comprises the following components by weight: 25-40 parts of bentonite, 25-30 parts of conductive cement, 25-30 parts of graphite and 8-15 parts of conductive mica powder.

3. The composite drag reducing agent according to claim 1, characterized in that: The weight ratio of the graphite to the conductive mica powder is (1.0-3.0):

1.

4. The composite drag reducing agent according to claim 1, characterized in that: The particle size of the bentonite is 100-400 meshes.

5. The composite drag reducing agent according to claim 1, characterized in that: The conductive cement has a fineness grade of 32.5-52.

5.

6. The composite drag reducing agent according to claim 1, characterized in that: The particle size of the graphite is 100-800 meshes.

7. The composite drag reducing agent according to claim 1, characterized in that: The particle size of the conductive mica powder is 200-800 meshes.

8. A method for preparing the composite drag reducing agent according to any one of claims 1 to 7, characterized in that: The following steps are involved: The components are uniformly mixed according to the weight proportions to obtain the composite drag reducing agent.

9. Use of the composite resistance reducing agent according to any one of claims 1 to 7 in reducing soil resistivity.

10. Use of the composite resistance reducing agent according to claim 9 in reducing soil resistivity, characterized in that: The composite drag reducing agent can be used after being mixed with water, and the weight ratio of the composite drag reducing agent to water is 0.5 to 1.0.

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