Diamond coating system and method by coupling organic waste oil steam reforming with chemical vapor deposition

Abstract

The invention discloses an organic waste oil steam reforming coupled chemical vapor deposition diamond coating system and method. The system comprises an impurity pretreatment module, a steam reforming module, a supplementary gas source module, a gas premixing module, an online gas chromatographic analysis module and a chemical vapor deposition diamond coating module. The impurity pretreatment module is used for removing solid particles, moisture, sulfide and colloid in the organic waste oil; the water vapor reforming module is used for reacting the pretreated organic waste oil with water vapor under the action of a catalyst to generate a mixed gas mainly containing methane and hydrogen, hydrogen is supplemented into the mixed gas, and the component content of the mixed gas is monitored and adjusted in real time through the online gas chromatographic analysis module; and the chemical vapor deposition diamond film coating module is used for converting the adjusted mixed gas into a diamond film to be deposited on the surface of a base material. According to the method, the organic waste oil reformate is used for replacing a traditional artificially synthesized gas source, the production cost of the diamond coating is remarkably reduced, and high-value utilization of the organic waste oil is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of diamond coating, and particularly relates to a system and method for diamond coating by coupling water vapor reforming of organic waste oil and chemical vapor deposition. BACKGROUND

[0002] If not properly disposed, organic waste oil (including industrial lubricating oil, hydraulic oil, catering waste oil, etc.) generated in industrial production and daily life is easy to cause environmental pollution. At present, the conventional treatment methods have significant defects: incineration treatment not only has the risk of combustion and explosion due to the flammable nature of organic waste oil, but also releases toxic and harmful gases such as sulfur, nitrogen oxides and dioxins, and the cost of tail gas purification is high; pyrolysis treatment is easy to generate heavy by-products such as tar due to complex process control, resulting in equipment corrosion and low utilization rate of products.

[0003] As a cleaner conversion method, water vapor reforming technology can convert long-chain hydrocarbons, esters and other high molecular substances contained in organic waste oil into small molecule combustible gases mainly composed of methane and hydrogen through the reaction of high-temperature water vapor and organic waste oil, and has potential in harmless disposal. However, the existing water vapor reforming technology for organic waste oil treatment is mostly limited to "pollution reduction" or "low-value energy recovery" (such as direct combustion for energy supply), and fails to achieve high-value utilization of reforming products, and lacks integration with high-value material preparation processes, limiting the maximization of environmental and economic benefits.

[0004] Chemical vapor deposition diamond coating technology has a wide range of applications and has shown significant advantages in the production of cutting tools and abrasives: the diamond thin film prepared by this technology has high hardness, low friction coefficient, excellent thermal conductivity and electrical conductivity, which can effectively improve the failure problems of cutting tools caused by oxidation and thermal fatigue, and significantly prolong the service life. In addition, boron-doped diamond thin film electrodes prepared by gas deposition method can efficiently dispose high-concentration organic pollutants in water, and the treatment process does not require the addition of reagents, and has the advantages of cleanliness and high efficiency, which can solve the technical difficulties in water treatment field, and is a key technical breakthrough with great application prospect in water treatment field. However, the chemical vapor deposition diamond coating technology currently relies on pure methane, acetone and other synthetic carbon sources, which has high raw material cost and high carbon emission in the preparation process, limiting its large-scale application, and there is an urgent need for low-cost and green carbon source alternatives.

[0005] There are related explorations in the field of waste oil resource utilization, for example, Chinese patent CN 110779038B discloses a waste gas recycling system of a radioactive organic waste steam reforming device, which realizes radioactive waste gas reduction through heat exchange air caching and recycling, providing a train of thought for waste resource utilization, but the technology is aimed at special radioactive waste, and only stays at the low-value level of "reduction and recycling", without involving the conversion of ordinary organic waste oil into high-value functional materials. In the literature SAE International Journal of Fuels and Lubricant, 2010, 3(2):810-818, nickel-based catalyst is used to convert organic lubricating oil waste and edible vegetable oil waste into 65% H2, 15% CO, 15% CO2 and 5% CH4 through steam reforming, and the yield of H2 and CH4 is continuously improved through chemical cycling. Through optimization, the waste oil reforming product can be well applied to the field of chemical vapor deposition diamond coating.

[0006] The present patent directly connects the gaseous hydrocarbons generated by steam reforming of organic waste oil into a chemical vapor deposition diamond coating system, realizing harmless disposal and resource utilization of organic waste oil, providing a low-cost carbon source for diamond coating, forming a closed loop of "waste oil pollution reduction-carbon source substitution-high value material preparation", and being an innovative solution for the integration of environmental governance and green economy. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings in the prior art, and to provide an organic waste oil steam reforming coupled chemical vapor deposition diamond coating system and method. The core is to remove solid impurities, gum, sulfides, etc. in the raw organic waste oil through an impurity pretreatment module, convert it into a mixture of methane and hydrogen gas through an organic waste oil steam reforming module, monitor the product composition through an online gas chromatography analysis module, adjust the gas ratio through a hydrogen supplement module or a hydrogen supplement module and a boron source gas supplement module, and then connect to a chemical vapor deposition coating module to prepare diamond cutters or boron-doped diamond thin film electrodes, realizing high-value utilization of organic waste oil and reducing coating production cost.

[0008] To achieve the above purpose, the present application adopts the following technical solutions:

[0009] An organic waste oil steam reforming coupled chemical vapor deposition diamond coating system, comprising a hydrogen supplement module, a boron source supplement module, and an impurity pretreatment module, a steam reforming module, a gas premixing module, an online gas chromatography analysis module and a chemical vapor deposition diamond coating module connected in sequence.

[0010] The impurity pretreatment module comprises a precision filter, an oil-water separator and a fixed bed adsorption column connected in sequence, and is used for pretreating the organic waste oil and sequentially removing solid particles, free water, emulsified water, heavy gum, sulfides and gum in the organic waste oil.

[0011] The water vapor reforming module comprises a fixed bed water vapor reforming reactor, and the reactor is filled with an oil-water vapor reforming catalyst.

[0012] The outlet ends of the water vapor reforming module, the hydrogen supplement module and the boron source supplement module are respectively connected with the inlet end of the gas premixing module through pipelines.

[0013] The online gas chromatography analysis module is used for monitoring the component content of the mixed gas at the outlet end of the gas premixing module in real time, so as to ensure that the mixed gas required for coating meets the standards.

[0014] The chemical vapor deposition diamond coating module is used for converting the adjusted mixed gas into a diamond film and depositing the diamond film on the surface of a substrate, and can produce diamond cutters or boron-doped diamond film electrodes according to requirements.

[0015] Further, the filtering precision of the precision filter is 1-10 μm, and preferably 5 μm; the oil-water separator is a heating demulsification and sedimentation unit of the impurity pretreatment module of the application, and is used for removing emulsified water and part of heavy gum in the organic waste oil.

[0016] The oil-water separator comprises a stirring type sedimentation kettle with a heating function, and a demulsifier is added in the stirring type sedimentation kettle.

[0017] The fixed bed adsorption column is filled with a solid adsorbent, the carrier of the solid adsorbent is a composite filler of γ-alumina and 13X molecular sieve with a mass ratio of 1.5-2.5:1, and the active component is ZnO.

[0018] Further, the water vapor reforming module further comprises a water vapor generator and a cold adsorption tower, and the water vapor generator is used for delivering water vapor into the fixed bed water vapor reforming reactor.

[0019] The adsorbent filled in the cold adsorption tower is a composite filler of 4A molecular sieve and activated carbon with a mass ratio of 2-4:1, and is used for adsorbing and removing residual water and heavy hydrocarbons in the gas product after reforming of the fixed bed water vapor reforming reactor.

[0020] Further, the waste oil steam reforming catalyst is a Ni-based catalyst, which takes γ-Al2O3 as the carrier, the active component is Ni element, the loading amount of the active component is 10-15wt%, and 1-3wt% of CeO2 additives are also loaded on the catalyst. The catalyst is activated at 500°C in H2 atmosphere for 2h before first use to activate the catalytic activity.

[0021] Further, the online gas chromatography analysis module adopts a PLOT Q capillary chromatographic column, and the detector is a combination of FID and TCD, with a detection accuracy of ≤0.1%. Real-time analysis of gas components is used to guide the proportional adjustment of the supplementary gas source and the recycling of the tail gas.

[0022] Further, the hydrogen supplement module and the boron source gas supplement module are both equipped with mass flow controllers. The H2 purity supplemented by the hydrogen supplement module is ≥99.99%, and the boron source gas supplement module is used to supplement diborane (only used when preparing boron-doped diamond thin film electrodes).

[0023] Further, a tail gas recycling module is also included, which is connected to the tail gas outlet of the chemical vapor deposition coating module at the gas inlet end and connected to the inlet end of the gas premixing module at the gas outlet end, so as to realize tail gas recycling.

[0024] The tail gas recycling module includes a water washing tower, which is used to wash the tail gas with water to remove trace amounts of unreacted heavy hydrocarbons and impurities in the tail gas. The treated tail gas is connected to the inlet end of the gas premixing module to realize the recycling of unused hydrogen and methane and reduce the amount of tail gas emissions.

[0025] A method of an organic waste oil steam reforming coupled chemical vapor deposition diamond coating system, comprising the following steps:

[0026] S1 organic waste oil pretreatment: the organic waste oil (initial sulfur content of 480-550ppm, initial water content of 1.0-1.4wt%) is filtered through a precision filter to remove mechanical impurities, and then separated by an oil-water separator to a water content of less than 0.4wt%. Then, the treated waste oil is passed through a fixed bed adsorption column to obtain clean waste oil with a total sulfur content of <5ppm and a water content of ≤0.1wt%.

[0027] S2 steam reforming: a Ni-based catalyst is arranged in the steam reforming module. The organic waste oil pretreated in step S1 is reformed with steam in the presence of the Ni-based catalyst to generate a mixed gas mainly composed of methane and hydrogen. Specifically, the clean waste oil is mixed with 240-260°C, 0.18-0.22MPa saturated water vapor generated by a steam generator and then passed into a fixed bed steam reforming reactor for reforming. The gas product after reforming is passed into a cold adsorption tower to remove residual water to ≤100ppm and C 10The above heavy hydrocarbon is used to obtain a methane and hydrogen basic mixed gas; online gas chromatography analysis is used to ensure that the minor components of the gas do not affect the subsequent process;

[0028] S3 gas mixing and online detection: hydrogen supplemented by the hydrogen supplementing module and the boron source (added on demand) are mixed with the mixed gas obtained in step S2 through the gas premixing module, and the component content is monitored in real time through the online gas chromatography analysis module. According to the chemical vapor deposition requirement, the flow rate of the supplemented H2 is adjusted, and then the ratio of hydrogen to methane in the mixed gas used for chemical vapor deposition is adjusted in the set range, and then the mixed gas enters the chemical vapor deposition diamond coating module. Specifically, when preparing a diamond tool, only the basic mixed gas and high-purity hydrogen are mixed into the gas premixing module, and the methane is adjusted to 7-9%, the hydrogen is adjusted to 90-92%, and the rest is a small amount of CO, CO2 and light hydrocarbon; when preparing a boron-doped diamond thin film electrode, the basic mixed gas, high-purity hydrogen and a small amount of diborane are mixed into the gas premixing module, and the methane is adjusted to 2-9%, the hydrogen is adjusted to 90-97%, the diborane is adjusted to 0.1-0.5%, and the rest is a small amount of CO, CO2 and light hydrocarbon; after the online gas chromatography monitoring component meets the standard, the mixed gas is introduced into the chemical vapor deposition diamond coating module;

[0029] S4 chemical vapor deposition coating: the chemical vapor deposition diamond coating module converts the adjusted mixed gas into a diamond thin film and deposits it on the surface of the substrate. The specific process adopts the hot wire method, and the coating chamber pressure is controlled to be 3800-4200 Pa, the hot wire temperature is controlled to be 2000-2500 ℃, the substrate temperature is controlled to be 700-900 ℃, and the hot wire distance from the sample is controlled to be 80-100 mm. According to the requirement, a diamond coated tool or a boron-doped diamond thin film electrode is produced.

[0030] Further, in step S1, the oil-water separator adopts a stirring settling tank with heating function, the organic waste oil is heated to 80-120 ℃, and a polyether demulsifier with a final concentration of 50-100 ppm is added. After standing and settling for 1-3 hours, the water and part of the heavy gum are removed by liquid separation;

[0031] The conditions of the reforming reaction in step S2 are that the reaction temperature is 650-750 ℃, the reaction pressure is 0.15-0.3 MPa, and the water / oil mass ratio is 1:8-10. The composition of the basic mixed gas obtained in step S2 is: 50-56% methane, 42-48% hydrogen, 0.5-1.0% CO, and 1.0-1.5% CO2.

[0032] Further, in step S4, when preparing a diamond tool, a cemented carbide substrate is selected, and a diamond thin film with a thickness of 1-20 μm is formed after deposition for 1-6 h; when preparing a boron-doped diamond thin film electrode, a niobium substrate is selected, and a boron-doped diamond thin film with a thickness of 4-8 μm is formed after deposition for 2-5 h.

[0033] Further, the process further comprises a step S5 of tail gas recycling, part of the tail gas of the chemical vapor deposition coating module is recycled to the inlet of the gas premixing module after removing impurities by the water washing tower, and then mixed with fresh gas source to participate in the coating process again.

[0034] Further, the demulsifier is SP169 or T-1001 polyether demulsifier.

[0035] Further, the desulfurization adsorbent is a γ-alumina-13X molecular sieve composite carrier, the mass ratio of γ-alumina to 13X molecular sieve is 1.5-2.5:1, and 0.5-2wt% of ZnO is loaded on the carrier as an active component to enhance the specific adsorption capacity of sulfides, and the adsorption treatment temperature is 100-150℃.

[0036] Further, in step S2, the Ni-based catalyst is supported on Al2O3, the loading amount of Ni is 10-15wt%, and 1-3wt% of CeO2 is loaded as an additive, the reaction temperature of the reforming reaction is 650-750℃, and the reaction pressure is 0.15-0.3MPa.

[0037] Further, after purification by the cold adsorption tower, online gas chromatography analysis shows that the typical product composition is: 50-56% of methane, 42-48% of hydrogen, 0.5-1.0% of CO, 1.0-1.5% of CO2, and the minor components do not affect the subsequent process.

[0038] Further, the H2 supplemented by the hydrogen supplementing module is high-purity hydrogen with a purity of ≥99.99%, which is used to adjust the mixed gas so that the proportion of hydrogen in the composition of methane and hydrogen is 90-95%.

[0039] Further, in step S3, ethylborane is supplemented by a boron source gas supplementing module, and the supplemented H2 and ethylborane are mixed with the mixed gas obtained in step S2 by the gas premixing module, and then enter the chemical vapor deposition diamond coating module, so that the proportion of hydrogen in the composition of methane, hydrogen and ethylborane is 90-97%, and the proportion of ethylborane is 0.1-0.5%, and the chemical vapor deposition diamond coating module converts the adjusted mixed gas into boron-doped diamond film and deposits it on the substrate surface.

[0040] Further, the chemical vapor deposition method of the chemical vapor deposition diamond coating module is selected from hot wire method, and the process parameters are: hot wire temperature 2000-2500℃, substrate temperature 700-900℃, and the tail gas of the chemical vapor deposition diamond coating module is returned to the inlet of the gas premixing module for mixing.

[0041] The core innovation of the present application is that: the preparation of diamond or boron-doped diamond coating by vapor deposition method usually relies on pure hydrogen gas (carrier gas) and pure methane (carbon source), while the present application first integrates organic waste oil reforming gas with chemical vapor deposition technology, uses waste oil reforming products to replace traditional artificial synthesis gas source, forms a synergistic system of "waste oil disposal-gas source supply-high value coating", compared with the existing waste resource technology (such as Chinese patent CN110779038B), the present application is aimed at more extensive ordinary organic waste oil, through the coupling with high value diamond coating process, realizes the leap from "waste harmless" to "functional material high value", the value dimension and the technical synergy are significantly improved; at the same time, through the tail gas recycling module, the gas is recycled efficiently, further reducing the cost and reducing the emission, forming a whole process green closed loop, which has outstanding creativity

[0042] Compared with the prior art, the present application has the following advantages:

[0043] (1) The cost is significantly reduced: the organic waste oil is used as raw material, which is directly used as the chemical vapor deposition coating gas source after steam reforming, and the raw material cost is reduced by 40-50% compared with the traditional pure methane / hydrogen gas; the hardness of the produced diamond cutter is ≥90GPa, and the 3-hour degradation efficiency of the boron-doped diamond film electrode to phenol reaches 99.2%, and the product performance reaches the industry high-quality level.

[0044] (2) The system has high flexibility: the gas components can be analyzed in real time by online gas chromatography, and the gas ratio can be adjusted flexibly (such as adjusting the methane proportion to 3-8% to adapt to different coating needs), so that the system can be compatible with the production of diamond cutters, boron-doped diamond film electrodes and other types of products, and has a wide range of applications.

[0045] (3) The environmental and economic benefits are coordinated: the organic waste oil is widely available, which is converted into high-value functional materials by the system, which not only solves the ecological pollution problem of random discharge of waste oil, but also realizes the transformation of "waste-resource-high value products", and provides a new path for the resource utilization of organic waste oil. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a structural schematic diagram of an organic waste oil steam reforming coupled chemical vapor deposition diamond coating system of the present application;

[0047] Figure 2 is a scanning electron microscope photo of the boron-doped diamond film produced by the system. DETAILED DESCRIPTION

[0048] The present application will be further described below in conjunction with specific examples, but the scope of protection of the present application is not limited thereto.

[0049] Example: control Figure 1

[0050] The organic waste oil steam reforming coupled chemical vapor deposition diamond coating system comprises a hydrogen supplement module 3, a boron source supplement module 4, and sequentially connected impurity pretreatment module 1, steam reforming module 2, gas premixing module 5, online gas chromatography analysis module 6 and chemical vapor deposition diamond coating module 7.

[0051] The impurity pretreatment module 1 comprises sequentially connected precision filter, oil-water separator and fixed bed adsorption column, and is used for pretreating the organic waste oil and sequentially removing solid particles, free water, emulsified water, heavy colloid, sulfides and colloid in the organic waste oil.

[0052] The steam reforming module 2 comprises a fixed bed steam reforming reactor, and the reactor is filled with an oil steam reforming catalyst, and is used for reacting the pretreated organic waste oil with water vapor under the action of the catalyst to generate a mixed gas mainly composed of methane and hydrogen.

[0053] The outlet ends of the steam reforming module 2, the hydrogen supplement module 3 and the boron source supplement module 4 are respectively connected with the inlet end of the gas premixing module 5 through pipelines;

[0054] The online gas chromatography analysis module 6 is used for monitoring the component content of the mixed gas at the outlet end of the gas premixing module 5 in real time, so as to ensure that the mixed gas required for coating meets the standard.

[0055] The chemical vapor deposition diamond coating module 7 is used for converting the adjusted mixed gas into a diamond thin film and depositing the diamond thin film on the surface of a substrate.

[0056] In the structure of the impurity pretreatment module 1, the filtering precision of the precision filter is 1-10 μm; the oil-water separator comprises a stirring type settling tank with a heating function, and a demulsifier is added in the settling tank; and the fixed bed adsorption column is filled with a desulfurization solid adsorbent.

[0057] The steam reforming module 2 further comprises a water vapor generator and a cold adsorption tower, the water vapor generator is used for delivering water vapor to the fixed bed steam reforming reactor, and the cold adsorption tower is filled with an adsorbent comprising 4A molecular sieve and activated carbon, and is used for adsorbing and removing residual water and heavy hydrocarbon in the gas product after reforming of the fixed bed steam reforming reactor.

[0058] The online gas chromatography analysis module 6 adopts a PLOT Q capillary chromatographic column, and the detector is a FID+TCD combination.

[0059] The system of the present application further comprises a tail gas recycling module 8, the gas inlet end of which is connected to the tail gas outlet of the chemical vapor deposition coating module 7, and the gas outlet end is connected to the inlet end of the gas premixing module 5, so as to realize tail gas recycling; the tail gas recycling module 8 comprises a water washing tower, which washes the tail gas with water, so as to remove trace amounts of unreacted heavy hydrocarbons and other impurities in the tail gas.

[0060] Example 1:

[0061] 1. Pretreatment of organic waste oil

[0062] The catering waste oil is treated by the impurity pretreatment module: first, it is filtered by a 10 μm polypropylene precision filter screen, and then centrifuged at a speed of 4000 r / min for 15 min to remove solid and free water; the oil phase after preliminary impurity removal is sent into a stirred settling kettle, which is heated to 100°C and kept at this temperature, and 80 ppm of SP169 demulsifier is added, and after stirring for 10 min (speed 100 r / min), it is left to stand for 2 h to separate the emulsified water and heavy gum (the water content in the oil phase after settling is ≤0.5 wt.%); the clarified oil phase is introduced into a fixed bed adsorption column filled with desulfurization adsorbent (bed height 30 cm, inner diameter 5 cm, height-diameter ratio 6:1), the carrier of the desulfurization adsorbent is a composite filler of γ-alumina and 13X molecular sieve with a mass ratio of 2:1, and 1 wt.% of ZnO is loaded on the carrier as an active component, and the oil phase space velocity is controlled at 1 h -1 , 120°C constant temperature adsorption, the total sulfur removal rate of waste oil reaches 99.5%, and clean waste oil (water content ≤0.1 wt.%) is obtained.

[0063] 2. Water vapor reforming

[0064] The clean waste oil is transported by an industrial-grade metering pump (feed rate 0.5 mL / min), and after being mixed with saturated water vapor (temperature 250°C, pressure 0.2 MPa) generated by a steam generator, it is introduced into a fixed bed water vapor reforming reactor; the reaction conditions are: temperature 700°C, pressure 0.2 MPa, water / oil mass ratio 1:9.5, and liquid hourly space velocity (based on waste oil) 0.2 h -1 (catalyst loading 50 g, corresponding to waste oil feed volume flow rate 0.01 L / h).

[0065] The reforming catalyst is a Ni-based catalyst, with γ-Al2O3 as the carrier and 12 wt.% Ni + 2 wt.% CeO2 loaded on the carrier, and the catalyst is in the form of spherical particles with a particle size of 20-40 mesh; before first use, the catalyst is activated by reduction in a H2 atmosphere at 500°C for 2 h.

[0066] The gas product after water vapor reforming is purified by cold adsorption to remove residual water and trace amounts of heavy hydrocarbons, and the specific operation is as follows:

[0067] The product is passed into a cold adsorption tower filled with 4A molecular sieve and activated carbon composite filler (mass ratio 3:1) (tower diameter 8 cm, bed height 40 cm), normal temperature, operating pressure 0.2 MPa (consistent with the reforming pressure, reducing energy consumption), gas space velocity 150 h -1 , by 4A molecular sieve adsorption of residual moisture (reduced to ≤100 ppm), activated carbon adsorption of trace amounts of heavy hydrocarbons (C 10 ) not completely cracked; after purification, the composition of the mixed gas is detected by an online gas chromatograph (FID+TCD detector, PLOT Q type capillary column): 53% CH4, 45% H2, 0.8% CO, 1.2% CO2, thereby obtaining a basic gas source.

[0068] 3. Gas source adjustment

[0069] By supplementing the gas source module, high-purity hydrogen (purity ≥ 99.99%) is introduced into the basic mixed gas, so that the proportion of hydrogen in the composition of methane and hydrogen is 92%, and the proportion of methane is 8%, and diborane is introduced at the same time, so that the proportion of diborane in the composition of methane, hydrogen and diborane is 0.3% ± 0.05%, after sufficient mixing by the gas premixing module (operating pressure 4000 Pa, gas residence time 10 s), the components are monitored in real time by an online gas chromatograph, and the components are stable and meet the standards, and then introduced into the chemical vapor deposition coating module.

[0070] 4. Hot wire chemical vapor deposition coating

[0071] After the niobium substrate (50 mm x 50 mm) is polished and pretreated, it is placed in the chemical vapor deposition coating module: a Φ0.5 mm tantalum wire is used, the hot wire substrate distance is 80 mm, the hot wire temperature is 2200℃; the working vacuum degree is 4000 Pa, the substrate temperature is 800℃, and the deposition is 5 h; after the coating tail gas is removed by the water washing tower, it is recycled to the gas premixing module at 80%.

[0072] 5. Performance verification

[0073] Figure 2 The scanning electron microscope image of the boron-doped diamond thin film electrode prepared by the method described in Example 1 of the present application. Figure 2 It can be seen that the prepared boron-doped diamond thin film has a uniform thickness of 6.87 μm. In the electrochemical test, the prepared boron-doped diamond thin film electrode is used as an anode, and a Ti electrode of the same specification is used as a cathode (the distance between the electrodes is 2 cm), 5 g / L of high-purity sodium chloride is added to adjust the conductivity in 10 L of phenol solution (initial concentration 100 mg / L), under the condition of 20 A constant current, the mechanical stirring speed is 500 r / min, and after 3 h, the phenol degradation rate reaches 99.2%, and the TOC removal rate reaches 95.6%, which is excellent.

[0074] The content described in the specification is merely a list of forms of the inventive concept, and the protection scope of the present application should not be regarded as being limited to the specific forms stated in the embodiments.

Claims

1. An organic waste oil steam reforming coupled chemical vapor deposition diamond coating system, characterized in that, It comprises a hydrogen supplement module (3), a boron source supplement module (4), and sequentially connected impurity pretreatment module (1), water vapor reforming module (2), gas premixing module (5), online gas chromatography analysis module (6) and chemical vapor deposition diamond coating module (7); The impurity pretreatment module (1) comprises a precision filter, an oil-water separator and a fixed bed adsorption column connected in sequence, is used for pretreating the organic waste oil, and sequentially removes solid particles, free water, emulsified water, heavy gum, sulfides and gum in the organic waste oil. The water vapor reforming module (2) comprises a fixed bed water vapor reforming reactor, and the reactor is filled with an oil-water vapor reforming catalyst. The outlet ends of the water vapor reforming module (2), the hydrogen supplement module (3) and the boron source supplement module (4) are connected with the inlet end of the gas premixing module (5) through pipelines respectively. The online gas chromatography analysis module (6) is used for monitoring the component content of the mixed gas at the outlet end of the gas premixing module (5) in real time, so as to ensure that the mixed gas required for coating meets the standards. The chemical vapor deposition diamond coating module (7) is used for converting the adjusted mixed gas into a diamond film and depositing the diamond film on the surface of a substrate.

2. The organic waste oil steam reforming coupled chemical vapor deposition diamond coating system according to claim 1, wherein, The precision filter has a filtering precision of 1-10 μm. The oil-water separator comprises a stirring type settling kettle with a heating function, and a demulsifier is added in the settling kettle. The fixed bed adsorption column is filled with a solid adsorbent, the carrier of the solid adsorbent is a composite filler of γ-alumina and 13X molecular sieve with a mass ratio of 1.5-2.5:1, the active component is ZnO, and the mass loading of the active component is 0.5-2%.

3. The organic waste oil steam reforming coupled chemical vapor deposition diamond coating system of claim 1, wherein, The water vapor reforming module (2) further comprises a water vapor generator and a cold adsorption tower, and the water vapor generator is used for delivering water vapor into the fixed bed water vapor reforming reactor. The adsorbent filled in the cold adsorption tower is a composite filler of 4A molecular sieve and activated carbon with a mass ratio of 2-4:1, and is used for adsorbing and removing residual water and heavy hydrocarbons in the gas product after reforming in the fixed bed water vapor reforming reactor.

4. The organic waste oil steam reforming coupled chemical vapor deposition diamond coating system of claim 1, wherein, The oil-water vapor reforming catalyst is a catalyst with γ-Al2O3 as a carrier and Ni element as an active component, the loading of the active component is 10-15 wt%, and 1-3 wt% of CeO2 additives are further loaded on the catalyst.

5. The organic waste oil steam reforming coupled chemical vapor deposition diamond coating system of claim 1, wherein, The online gas chromatography analysis module (6) adopts a PLOT Q capillary chromatographic column, and the detector is a FID+TCD combination.

6. An organic waste oil steam reforming coupled chemical vapor deposition diamond coating system as claimed in claim 1, wherein, It further comprises a tail gas recycling module (8), the gas inlet end of the tail gas recycling module (8) is connected with the tail gas outlet of the chemical vapor deposition coating module (7), and the gas outlet end is connected with the inlet end of the gas premixing module (5), so that the tail gas is recycled. The tail gas recycling module (8) comprises a water washing tower, and the tail gas is washed with water, so as to remove trace unreacted heavy hydrocarbons and other impurities in the tail gas.

7. A method based on the system of claim 1, characterized by, The method comprises the following steps: S1 organic waste oil pretreatment: removing mechanical impurities from the organic waste oil through a precision filter, and separating free water through an oil-water separator to obtain the organic waste oil with a water content of less than or equal to 0.4 wt%; Subsequently, the treated waste oil is introduced into a fixed bed adsorption column, so that the total sulfur content of the treated waste oil is less than 5 ppm and the water content is less than or equal to 0.1 wt%, and clean waste oil is obtained. S2 steam reforming: the clean waste oil is mixed with saturated water vapor of 240-260°C, 0.18-0.22 MPa generated by a steam generator, and then introduced into a fixed-bed steam reforming reactor to perform a reforming reaction; the gas product after reforming is introduced into a cold adsorption tower to remove residual water to ≤100 ppm and C 10 The above heavy hydrocarbon is a base mixed gas; S3 gas mixing and online detection: when preparing a diamond tool, only the base mixed gas and high-purity hydrogen are mixed in the gas premixing module, and are adjusted to 2-9% methane, 90-97% hydrogen, and the rest is a small amount of CO, CO2 and light hydrocarbons; when preparing a boron-doped diamond thin film electrode, the base mixed gas, high-purity hydrogen and a small amount of diborane are mixed in the gas premixing module, and are adjusted to 2-9% methane, 90-97% hydrogen, 0.1-0.5% diborane, and the rest is a small amount of CO, CO2 and light hydrocarbons; after the components are monitored by the online gas chromatograph and meet the standards, the chemical vapor deposition diamond coating module is introduced; S4 chemical vapor deposition coating: the chemical vapor deposition diamond coating module converts the adjusted mixed gas into a diamond thin film and deposits it on the surface of the substrate. The specific process adopts a hot wire method, and the coating chamber pressure is controlled to be 3800-4200 Pa, the hot wire temperature is controlled to be 2000-2500 ℃, the substrate temperature is controlled to be 700-900 ℃, and the hot wire distance from the sample is controlled to be 80-100 mm. Diamond-coated tools or boron-doped diamond thin film electrodes are produced according to requirements.

8. The method of claim 7, wherein, In step S1, the oil-water separator is a stirring settling tank with heating function. The organic waste oil is heated to 80-120 ℃, and a polyether demulsifier with a final concentration of 50-100 ppm is added. After standing and settling for 1-3 hours, the water and part of the heavy gum are removed by liquid separation; In step S2, the reforming reaction conditions are as follows: the reaction temperature is 650-750 ℃, the reaction pressure is 0.15-0.3 MPa, and the water / oil mass ratio is 1:8-10. The composition of the base mixed gas obtained in step S2 is as follows: 50-56% methane, 42-48% hydrogen, 0.5-1.0% CO, and 1.0-1.5% CO2.

9. The method of claim 7, wherein, In step S4, when preparing a diamond tool, a cemented carbide substrate is selected, and a 1-6 h deposition forms a 1-20 μm thick diamond thin film; when preparing a boron-doped diamond thin film electrode, a niobium substrate is selected, and a 2-5 h deposition forms a 4-8 μm thick boron-doped diamond thin film.

10. The method of claim 7, wherein, Step S5 also includes the process of recycling the tail gas. After the tail gas of the chemical vapor deposition coating module is removed by the water washing tower, part of the tail gas is recycled to the inlet end of the gas premixing module, mixed with the fresh gas source, and then participates in the coating process again.

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