Anti-corrosion sewage pipeline inspection well and anti-corrosion method

Abstract

The invention discloses an anti-corrosion sewage pipeline inspection well and an anti-corrosion method, the inspection well comprises a well lid wrapped with copper, a ladder stand, anode material iron immersed in water and a copper wire connecting the well lid, the ladder stand and the anode material iron, and the anode material iron with low electrode potential is coupled with the ladder stand with high electrode potential and a copper coating of the sewer well lid through the copper wire; h2S gas in inspection well water reacts to generate FeS precipitate, H2S is inhibited from escaping into a gas phase, and corrosion of the H2S gas to sewer well lids and crawling ladders is reduced. Copper covering the surfaces of the well lid and the crawling ladder can effectively prevent H2S from making contact with the interior, and the metal well lid and the crawling ladder are prevented from being corroded. According to different concentrations of H2S gas in the sewage pipeline, different anticorrosion effects can be achieved by coupling and covering copper on the surface of a sewer well lid and / or a crawling ladder with anode iron of different volumes.

Description

Technical Field

[0001] The present invention relates to a manhole for a sewage pipeline in an urban drainage network, in particular to an anti-corrosion manhole for a sewage pipeline and an anti-corrosion method. Background Art

[0002] As one of the important infrastructure facilities, the urban drainage network is crucial for waterlogging control, wastewater collection, and water environment protection. During the operation of the drainage network, an anaerobic environment is created, which promotes a series of biochemical reactions and generates toxic and harmful gases. Among them, problems such as pipeline corrosion and odor emission caused by hydrogen sulfide produced by sulfate-reducing bacteria have always been one of the main reasons endangering the healthy operation of the network. The biological sulfuric acid generated by the oxidation of gaseous hydrogen sulfide will cause corrosion of concrete drainage pipelines, resulting in sewage leakage, polluting groundwater and soil, and increasing the maintenance and reconstruction costs. Hydrogen sulfide is the main cause of sewer odor. The emission of hydrogen sulfide not only pollutes the environment but also poses certain hazards to the human body. Therefore, the control of hydrogen sulfide gas in the drainage network is particularly important for the development of the city. As an important part of the drainage network, manholes play an important role in the operation and maintenance of the drainage network. The existing manhole covers and ladders in manholes are generally made of cast iron or steel structures and have good load-bearing capacity. However, the lower surface of the manhole cover and the ladders are easily eroded by sewage, resulting in corrosion, which affects the normal use of the manhole cover and the safety of the personnel entering the well. Therefore, it is imperative to take protective measures for the manhole cover and the ladders to extend their service life and reduce the replacement cost.

[0003] Currently, the addition of chemical agents is a common method for controlling hydrogen sulfide in drainage pipelines. The added chemical agents mainly include oxygen, caustic soda, magnesium hydroxide, sodium nitrate, and iron salts. Among them, iron salts in the form of ferrous chloride (FeCl 2 ) or ferric chloride (FeCl 3 ) are one of the most commonly used chemical agents. It removes sulfides in the form of iron sulfide precipitation. Although directly adding iron salts is effective in controlling hydrogen sulfide, there are also certain defects. First, iron salts need to be continuously added to achieve the control purpose, which increases the energy consumption of the addition and accelerates the aging of the addition equipment. Second, due to the high corrosiveness and strong acidity of iron salts, there are not only occupational health and safety problems for people, but also the transportation and storage of iron salts require containers made of special materials. The control scheme of adding iron salts also has the defect of high investment.

[0004] At present, sewer manhole covers are mainly anti-corrosive by physically isolating sewage and air. For example, the patent with the patent document number CN208363137U discloses a method of anti-corrosion by setting a waterproof net under the manhole cover to prevent the lower surface of the manhole cover from contacting sewage. The patent with the patent document number CN215483133U discloses a method of protecting the manhole cover from corrosion by setting a polyurea coating on the surface of the manhole cover. At present, the anti-corrosion method for ladders mainly involves making ladders from materials with corrosion-resistant properties. Although the above anti-corrosion methods are effective, they lack the full utilization of anti-corrosion materials. Existing plastic inspection wells have good surface hardness and tensile strength, but are not corrosion-resistant, have a short service life, and are not suitable for use in harsh environments. Summary of the Invention

[0005] To solve the above-mentioned defects in the prior art, the purpose of the present invention is to provide an anti-corrosive sewage pipeline inspection well and an anti-corrosion method. By setting an anode iron in the sewage pipeline and connecting it to the ladder and sewer manhole cover with a copper coating, controlling hydrogen sulfide in the sewer to prevent the corrosion of the inspection well, while solving the problem that the current direct addition of iron salts to control hydrogen sulfide in the sewer requires continuous addition and has high requirements for transportation and storage, and protecting the facilities in the sewer.

[0006] The present invention is realized through the following technical solutions.

[0007] One aspect of the present invention provides an anti-corrosive sewage pipeline inspection well, including a ladder provided in the inspection well, a sewer manhole cover located on the upper surface of the inspection well. The surface of the ladder and the sewer manhole cover is wrapped with a copper coating. An anode iron is provided in the sewage pipeline below the inspection well, and the anode iron is connected to the ladder and the sewer manhole cover with a copper coating through a wire;

[0008] By coupling the anode iron with a low electrode potential and the copper coating of the ladder and the sewer manhole cover with a high electrode potential through a wire, the H 2 S gas in the inspection well water reacts to form FeS precipitate, reducing the corrosion of the sewer manhole cover and the ladder by H 2 S gas.

[0009] Preferably, the copper coating material wrapped on the surface of the ladder and the sewer manhole cover is one of purple copper or brass.

[0010] Preferably, the wire is a pure copper core wire wrapped with an insulating layer, and the wire is buried in the well wall.

[0011] Preferably, the wire is provided with an interface near the sewer manhole cover, so that the sewer manhole cover is detachable.

[0012] Preferably, the anode iron is one of an iron block, an iron sheet, pure iron wire or iron filings.

[0013] Preferably, the copper plating wrapped on the surface of the ladder and the sewer manhole cover is in three ways: only covering the surface of the sewer manhole cover, only covering the surface of the ladder, and covering the surfaces of both the ladder and the sewer manhole cover simultaneously.

[0014] Another aspect of the present invention provides three different anti-corrosion methods for sewage pipeline inspection wells, including:

[0015] When the concentration of H 2 S gas in the sewage pipeline is less than 50 ppm, a relatively large iron block or iron sheet is used as the anode iron;

[0016] Only the surface of the ladder is wrapped with copper plating, and the iron block or iron sheet used as the anode iron is connected to the ladder through a copper core wire.

[0017] When the concentration of H 2 S gas in the sewage pipeline is greater than 50 ppm, waste iron filings are used as the anode iron;

[0018] The surfaces of both the ladder and the sewer manhole cover are wrapped with copper plating simultaneously, and the waste iron filings used as the anode iron are placed in a metal container and connected to the ladder through a copper core wire.

[0019] When the concentration of H 2 S gas in the sewage pipeline is less than 30 ppm, an iron block is used as the anode iron;

[0020] Only the surface of the sewer manhole cover is wrapped with copper plating, and the iron block used as the anode iron is connected to the sewer manhole cover through a copper core wire.

[0021] Due to the above technical solutions adopted by the present invention, it has the following beneficial effects:

[0022] 1. The device of the present invention can in-situ generate ferrous ions (Fe 2+ ) through the copper-iron coupling iron as the anode, which combines with sulfide in the sewage to form ferrous sulfide (FeS) precipitate, inhibiting the escape of H 2 S into the gas phase. In addition, the copper covering the surfaces of the manhole cover and the ladder can effectively prevent H 2 S from contacting the interior, preventing the corrosion of the metal manhole cover and the ladder, and reducing the emission of hydrogen sulfide.

[0023] 2. The present invention takes into account the different concentrations of H 2 S gas in the sewage pipeline and provides three different anti-corrosion methods for sewage pipeline inspection wells. It can achieve different anti-corrosion effects by using different volumes of anode iron coupled with copper covering the surface of the sewer manhole cover and / or the ladder according to the different concentrations of H 2 S gas in the sewage pipeline. It solves the problems of equipment corrosion and strong acidity of the existing technology for controlling hydrogen sulfide by adding chemical reagent iron salts, which pose occupational health and safety risks to humans. Moreover, this method is simple, effective, convenient and practical. Brief Description of the Drawings

[0024] The drawings described herein are provided to further understand the present invention, form a part of this application, and do not constitute an improper limitation to the present invention. In the drawings:

[0025] Figure 1 It is a schematic layout diagram of the device of the present invention in a pipeline;

[0026] Figure 2 It is a comparison diagram of the continuous change of sulfide in the performance test of Example 1.

[0027] The meanings of the reference numerals in the drawings: 1 - sewer manhole cover, 2 - copper plating, 3 - wire, 4 - ladder, 5 - anode iron, 6 - interface, 7 - inspection well, 8 - sewage pipeline. Detailed Description of the Preferred Embodiments

[0028] The present invention will be described in detail below with reference to the drawings and specific embodiments. Here, the schematic embodiments and descriptions of the present invention are used to explain the present invention, but do not limit the present invention.

[0029] As Figure 1 shown, a corrosion-resistant sewage pipeline inspection well provided by an embodiment of the present invention includes a ladder 4 with a copper plating provided in the inspection well 7, a sewer manhole cover 1 with a copper plating 2 on the upper surface of the inspection well 7, an anode iron 5 in the sewage pipeline 8 below the inspection well 7, and the anode iron 5 is connected to the ladder 4 and the sewer manhole cover 1 with copper plating through a wire 3.

[0030] Among them, in this embodiment, the copper plating 2 is one of red copper or brass. The wire 3 is a pure copper core wire wrapped with an insulating layer, and the wire 3 is buried in the well wall. The wire 3 is provided with an interface 6 near the sewer manhole cover 1, so that the sewer manhole cover 1 is detachable. The anode iron can be one of an iron block, an iron sheet, pure iron wire or iron filings.

[0031] The copper covering the surfaces of the sewer manhole cover 1 and the ladder 4 is in three ways: only covering the surface of the sewer manhole cover 1, only covering the surface of the ladder 4, and covering both the ladder 4 and the sewer manhole cover 1 at the same time.

[0032] The working principle of the present invention is:

[0033] After the iron with a lower electrode potential and the copper with a higher electrode potential are coupled with a wire, the iron will become the anode and the copper will become the cathode. The anode undergoes an oxidation reaction to generate Fe 2+ , and Fe 2+ will react with S 2- in the water to form FeS precipitate, reducing the diffusion concentration of H 2 S gas into the air, thereby reducing H 2The corrosion occurs after S comes into contact with the inspection well cover and the ladder, playing a role in protecting the well cover and the ladder.

[0034] The present invention adopts an anti-corrosion method for sewage pipeline inspection wells. Through the copper surface layer attached to the inner wall of the sewage pipeline and the anode iron immersed in water, a perforated pipe with a certain inner diameter is made of rigid plastic net. One end of the copper wire is fixed on the copper plating of the sewer manhole cover and ladder and the copper surface layer on the inner wall of the sewage pipeline by welding, and the other end is connected to the anode iron inside the rigid plastic net to achieve the connection between the anode and the cathode. According to the characteristic that the surface area ratio of the anode and the cathode mainly determines the anode reaction rate, that is, the larger the surface area ratio of the anode and the cathode, the faster the rate of generating Fe 2+ in the pipeline, and the better the control effect on H 2 S in the pipeline. In order to better adapt to different application scenarios, according to the concentration of H 2 S gas in the pipeline, the form of the anode iron is determined, and different anti-corrosion methods can be adopted.

[0035] The anti-corrosion method of the sewage pipeline inspection well of the present invention will be further described below through different embodiments.

[0036] Embodiment 1

[0037] When the concentration of H 2 S gas in the pipeline is less than 50 ppm, the anode adopts a relatively large iron block or iron sheet that is easy to obtain; only the surface of the ladder is wrapped with a copper plating, and the iron block or iron sheet as the anode iron is connected to the ladder through a copper core wire.

[0038] This embodiment can reduce the replacement frequency of the anode iron and the replacement cost on the premise of ensuring that H 2 S is removed.

[0039] Embodiment 2

[0040] When the concentration of H 2 S gas in the pipeline is greater than 50 ppm, the anode can adopt iron filings, and at the same time, the surfaces of the ladder and the sewer manhole cover are wrapped with a copper plating. The iron filings as the anode iron are placed in a metal container and connected to the ladder through a copper core wire.

[0041] In this embodiment, the surface area of a single iron filing is extremely different from the surface area of copper, which can accelerate the reaction rate and achieve the purpose of rapid control.

[0042] Embodiment 3

[0043] When the concentration of H 2When the concentration of H₂S gas is less than 30 ppm, an iron block is used as the anode iron. Only the surface of the sewer manhole cover is wrapped with a copper coating. The iron block serving as the anode iron is connected to the sewer manhole cover through a copper-core wire. This embodiment is generally used for connecting a smaller-diameter horizontal branch pipe between a household drainage outlet and a municipal pipeline. Placing an iron block with a smaller volume in the pipeline can reduce the obstruction to pipeline drainage and the slowly released Fe 2+ can relieve H 2 S generation.

[0044] The following gives the performance test of the device and method of the present invention for treating hydrogen sulfide gas in the pipeline.

[0045] The performance test experiment was carried out in a glass bottle with a working volume of 1000 mL. The reactor stirring system used a magnetic stirrer to stir the sewage, and the rotation speed was controlled at 250 rpm to simulate the turbulent flow conditions of real sewage. The reactor was kept warm by a water bath, and the reaction temperature was controlled at (25 ± 1 °C) to simulate the temperature of the real sewage environment. The sewage used in the experiment was taken from the sewage inspection well of Huaqing Square, and the initial concentration of sulfide was 0. Before use, the sewage was stored at 4 °C, and when in use, a sodium sulfide solution was added to simulate the sulfide generated in the sewage. A total of three groups of experiments were carried out. In the control group R1, no copper mesh and iron wire were placed in the device. In the first experimental group R2, the copper mesh and iron wire were placed in water and completely immersed in water, and the two were connected by a copper wire. In the second experimental group R3, the copper mesh and iron wire were placed in water and completely immersed in water, and the two were not connected by a copper wire. The experimental results are as Figure 2 shown. It is effective and feasible to use the copper-iron galvanic corrosion system to remove liquid sulfide in water. Compared with the control group, the experimental group can control the liquid sulfide in water. Under two different working conditions of copper-iron coupling and disconnection, the experimental group needs 120 minutes and 140 minutes respectively to remove 90% of the liquid sulfide. Copper-iron coupling can accelerate the removal of sulfide in water.

[0046] There is no obvious change on the copper surface. Under two different working conditions of copper-iron coupling and disconnection, the experimental group needs 120 minutes and 140 minutes respectively to remove 90% of the liquid sulfide, indicating that the present invention can directly reduce the generation of sulfide in water and indirectly protect the inspection well.

[0047] This is much slower than directly adding iron ions. However, compared with the method of directly adding iron ions, this method does not require continuous addition. Only relying on the corrosion of iron in the copper-iron galvanic corrosion system can continuously remove liquid sulfide in water to achieve the purpose of preventing the corrosion of the inspection well.

[0048] The present invention is not limited to the above embodiments. Based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and deformations to some of the technical features without creative labor according to the disclosed technical content, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A corrosion-resistant sewage pipe inspection well, comprising a ladder arranged in the inspection well, and a sewer manhole cover located on the upper surface of the inspection well, characterized in that: The surfaces of the ladder and the manhole cover are coated with a copper coating, an anode iron is arranged in the sewage pipe below the inspection well, and the anode iron is connected to the ladder and the manhole cover with the copper coating through a wire; By coupling the anode iron with low electrode potential with the copper coating of the ladder and manhole cover with high electrode potential through a wire, the H2S gas in the inspection well water reacts to generate FeS precipitation, reducing the corrosion of the sewer manhole cover and ladder by the H2S gas.

2. The corrosion-resistant sewage pipe inspection well according to claim 1 is characterized in that: The copper coating on ladders and manhole covers is made of either copper or brass.

3. The corrosion-resistant sewage pipe inspection well according to claim 1 is characterized in that: The conductor is a pure copper core conductor wrapped with an insulating layer and is buried in the well wall.

4. The corrosion-resistant sewage pipe inspection well according to claim 1 is characterized in that: The wire is provided with an interface near the manhole cover so that the manhole cover can be disassembled.

5. The corrosion-resistant sewage pipe inspection well according to claim 1 is characterized in that: The anode iron is one of iron block, iron sheet, pure iron wire or scrap iron.

6. The corrosion-resistant sewage pipe inspection well according to claim 1 is characterized in that: The copper plating wrapped on the surface of the ladder and the manhole cover is in three ways: only covering the surface of the manhole cover, only covering the surface of the ladder, and covering the surfaces of the ladder and the manhole cover at the same time.

7. A corrosion-resistant sewage pipe inspection well anti-corrosion method as claimed in any one of claims 1 to 6, characterized in that: include: When the H2S gas concentration in the sewage pipe is less than 50ppm, a larger iron block or iron sheet is used as anode iron; Only the copper plating is wrapped on the surface of the ladder, and the iron block or iron sheet serving as the anode iron is connected to the ladder through a copper core wire.

8. A corrosion-resistant sewage pipe inspection well anti-corrosion method as claimed in any one of claims 1 to 6, characterized in that: include: When the H2S gas concentration in the sewage pipe is greater than 50ppm, scrap iron is used as anode iron; At the same time, the surfaces of the ladder and the manhole cover are coated with a copper coating, and scrap iron filings used as anode iron are placed in a metal container and connected to the ladder through a copper core wire.

9. A corrosion-resistant sewage pipe inspection well anti-corrosion method as claimed in any one of claims 1 to 6, characterized in that: include: When the H2S gas concentration in the sewage pipe is less than 30ppm, iron blocks are used as anode iron; Only the copper plating is wrapped on the surface of the manhole cover, and the iron block serving as the anode iron is connected to the manhole cover through a copper core wire.

Images