Catalytic ozonation small-scale test device for coal gasification wastewater of Lurgi gasifier

Abstract

The utility model discloses a Lurgi gasifier coal gasification wastewater ozone catalytic oxidation small-scale test device, which is characterized in that an ozone generator is communicated with a gas inlet at the bottom of a catalytic ozonation reactor through an ozone flowmeter, a circulating tank is communicated with a liquid inlet at the lower part of the catalytic ozonation reactor through a peristaltic pump, and the liquid inlet is positioned at the upper part of the gas inlet; the circulating tank is communicated with a liquid outlet in the upper portion of the catalytic ozonation reactor through a liquid conveying pipe, the top of the catalytic ozonation reactor is communicated with the KI absorption device through a gas conveying pipe, and a disc type micropore aerator is installed in an inner cavity of the catalytic ozonation reactor between a liquid inlet and a gas inlet. N screens are transversely mounted at equal intervals in a cavity of the catalytic ozonation reactor between the disc type microporous aerator and the air outlet from top to bottom, the catalytic ozonation reactor is divided into N catalytic reaction chambers by the screens, and a Ce-Mn bimetallic oxide catalyst is placed on the screens. The catalytic efficiency of a traditional ozone catalytic oxidation device is effectively improved, and meanwhile, the device is suitable for treating a larger amount of wastewater.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment devices, in particular to a small-scale test device for ozone catalytic oxidation of coal gasification wastewater from a Lurgi furnace. Background Art

[0002] The Lurgi furnace gasification process involves countercurrent contact between coal and a gasifying agent (steam and oxygen) within a furnace. It is suitable for high-gasification activity, lignite with a granularity of 3-30 mm, and weakly caking coal. Due to its low operating costs and wide applicability, it is widely adopted in my country. Lurgi furnace gasification wastewater is generated during the scrubbing and cooling process of the crude coal gas produced by the Lurgi furnace gasification reaction. Test results indicate that its composition is complex, containing ammonia nitrogen, oils, sulfides, cyanides, and other toxic and difficult-to-degrade compounds, such as phenols, polycyclic aromatic hydrocarbons, and nitrogen-containing heterocyclic compounds. Most of these compounds have been shown to be mutagenic and carcinogenic, posing significant environmental risks and posing a threat to human health. Traditional wastewater treatment methods struggle to meet increasingly stringent environmental standards, leading to the development of efficient and environmentally friendly wastewater treatment technologies becoming a hot topic in industry research.

[0003] At present, there are various methods for treating Lurgi furnace gasification wastewater, including adsorption, coagulation, membrane separation, electrochemistry and deep oxidation. Although the adsorption method is low-cost, the adsorbent is easily saturated and needs to be replaced regularly, which is not suitable for industrial applications. The coagulation method is only suitable for occasions with low equipment requirements, large processing volume and low requirements for effluent quality. Membrane separation technology has problems such as high operating costs and membrane fouling. Although the electrochemical method avoids secondary pollution, its equipment is complex and the cost is relatively high. Although a variety of process technologies are widely used in the treatment of phenolic organic matter in coal gasification wastewater, it is difficult to achieve low-cost, environmentally friendly and efficient removal in actual operation and operation. Ozone catalytic oxidation technology, as an emerging advanced oxidation technology, has attracted widespread attention due to its strong oxidation ability and environmental friendliness. Ozone forms hydroxyl radicals in water, with an oxidation potential of 2.83V. It can degrade phenolic substances in coal gasification wastewater into a variety of small molecular organic compounds such as acetic acid, oxalic acid, hydroquinone, and catechol, and ultimately degrade them into CO2 and H2O. However, this free radical reaction is non-selective and has a fast reaction rate. Utility Model Content

[0004] The utility model aims to provide a Lurgi furnace coal gasification wastewater ozone catalytic oxidation pilot device, which solves the problem of poor ozone degradation efficiency in existing coal gasification wastewater ozone treatment devices.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A Lurgi furnace coal gasification wastewater ozone catalytic oxidation pilot device, comprising an oxygen cylinder, an ozone generator, a circulation tank, an ozone flowmeter, a peristaltic pump, an ozone catalytic oxidation reactor, a KI absorption device, a screen and a disc-type microporous aerator; the oxygen cylinder is connected to the ozone generator, the ozone generator is connected to the air inlet at the bottom of the ozone catalytic oxidation reactor through an air pipe, an ozone flowmeter is provided on the air pipe at the rear end of the ozone generator, the circulation tank is connected to the liquid inlet at the bottom of the ozone catalytic oxidation reactor through a liquid pipe, and a liquid pipe between the circulation tank and the ozone catalytic oxidation reactor is provided. A peristaltic pump is fixed, the liquid inlet is located above the air inlet, the circulation tank is connected to the liquid outlet on the upper part of the ozone catalytic oxidation reactor through a liquid infusion pipe, the top of the ozone catalytic oxidation reactor is connected to the KI absorption device through an air inlet, a disc-type microporous aerator is installed in the inner cavity of the ozone catalytic oxidation reactor between the liquid inlet and the air inlet, N screens are installed at equal intervals horizontally from top to bottom in the cavity of the ozone catalytic oxidation reactor between the disc-type microporous aerator and the air outlet, the screens divide the ozone catalytic oxidation reactor into N catalytic reaction chambers, and the Ce-Mn bimetallic oxide catalyst is placed on the screens.

[0007] Furthermore, a feed port is opened on one side of each catalytic reaction chamber.

[0008] The Ce-Mn bimetallic oxide catalyst is a spherical porous particle with a diameter of 3 to 5 mm.

[0009] Preferably, the Ce-Mn bimetallic oxide catalyst comprises Ce-Mn bimetallic oxide and a coal gasification ash carrier, and the Ce-Mn bimetallic oxide is loaded on the coal gasification ash carrier.

[0010] A small-scale test device for ozone catalytic oxidation of Lurgi furnace coal gasification wastewater also includes a water inlet pump, a digestion tank and a centrifugal device. The water inlet pump is connected to the water inlet of the circulation tank through a pipeline, and the drainage outlet of the circulation tank is connected to the digestion tank and the centrifugal device in sequence through pipelines. A water inlet valve is installed on the pipeline near the water inlet, and a drainage valve is installed on the pipeline near the drainage outlet.

[0011] Ozone molecules themselves have an extremely high oxidation potential, enabling them to directly attack and decompose organic pollutants in coal gasification wastewater. However, this process is significantly accelerated in the presence of Ce-Mn bimetallic oxide pellet catalysts. By providing active sites or altering the reaction pathway, the catalyst promotes the decomposition of ozone into hydroxyl radicals (·OH), which have a stronger oxidizing potential. These radicals react almost non-selectively with organic matter in coal gasification wastewater, effectively removing a variety of difficult-to-degrade pollutants, including phenols, polycyclic aromatic hydrocarbons, and nitrogen-containing heterocyclic compounds.

[0012] The beneficial effects of the utility model are as follows: the Ce-Mn bimetallic oxide catalyst is particularly suitable for the treatment of Lurgi furnace gasification wastewater with high COD content, and has high COD degradation efficiency. Moreover, due to the setting of the KI absorption device, it can prevent ozone and other harmful substances from being discharged into the environment. The ozone catalytic oxidation reactor is provided with a partitioned sampling port, thereby ensuring that the catalyst can be evenly distributed in the reactor, and the microporous aerator at the bottom of the reactor can enable ozone to fully contact and degrade the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the structure of a small-scale pilot plant for ozone catalytic oxidation of Lurgi furnace coal gasification wastewater. DETAILED DESCRIPTION

[0014] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0015] Example 1

[0016] like Figure 1 As shown,

[0017] This embodiment involves a Lurgi furnace coal gasification wastewater ozone catalytic oxidation pilot device, comprising an oxygen cylinder 1, an ozone generator 2, a circulation tank 3, an ozone flowmeter 4, a peristaltic pump 5, an ozone catalytic oxidation reactor 6, a KI absorption device 7, a screen 601, and a disc-type microporous aerator 603;

[0018] The oxygen cylinder 1 is connected to the ozone generator 2, and the ozone generator 2 is connected to the air inlet at the bottom of the ozone catalytic oxidation reactor 6 through an air supply pipe. An ozone flowmeter 4 is set on the air supply pipe at the rear end of the ozone generator 2, and the ozone delivery amount is controlled by the ozone flowmeter 4. The circulation tank 3 is connected to the liquid inlet at the bottom of the ozone catalytic oxidation reactor 6 through a liquid infusion pipe, and a peristaltic pump 5 is fixed on the liquid infusion pipe between the circulation tank 3 and the ozone catalytic oxidation reactor 6. The liquid inlet of the ozone catalytic oxidation reactor 6 is controlled by the peristaltic pump 5. The liquid inlet is located above the air inlet to facilitate uniform gas and liquid Mixing, the circulation tank 3 is connected to the liquid outlet on the upper part of the ozone catalytic oxidation reactor 6 through a liquid infusion pipe, and the top of the ozone catalytic oxidation reactor 6 is connected to the KI absorption device 7 through an air infusion pipe. A disc-type microporous aerator 603 is installed in the inner cavity of the ozone catalytic oxidation reactor 6 between the liquid inlet and the air inlet. N screens are installed at equal intervals horizontally from top to bottom in the cavity of the ozone catalytic oxidation reactor 6 between the disc-type microporous aerator 603 and the air outlet. The screen divides the ozone catalytic oxidation reactor 6 into N catalytic reaction chambers, and the Ce-Mn bimetallic oxide catalyst is placed on the screen.

[0019] Furthermore, a feed port 602 is provided on one side of each catalytic reaction chamber, and the feed port facilitates timely replacement of the Ce-Mn bimetallic oxide catalyst.

[0020] The catalyst filling the ozone catalytic oxidation reactor 6 is an existing Ce-Mn bimetallic oxide catalyst. The Ce-Mn bimetallic oxide catalyst is a spherical porous particle with a diameter of approximately 3 to 5 mm. Preferably, the Ce-Mn bimetallic oxide catalyst comprises a Ce-Mn bimetallic oxide and a coal gasification ash carrier, with the Ce-Mn bimetallic oxide supported on the coal gasification ash carrier. The coal gasification ash carrier has a high specific surface area and a porous structure. This structural feature enables the ash to effectively adsorb reactant molecules, increasing the contact area between the Ce-Mn bimetallic oxide catalyst and the reactants, thereby improving the efficiency of the catalytic reaction. Furthermore, the porous structure provides excellent diffusion channels, facilitating the rapid transport of reactants and products, further accelerating the reaction rate. The coal gasification ash carrier also has high mechanical strength. In contrast, using ceramsite or low-purity activated alumina as a carrier has low mechanical strength, is prone to pulverization, and has a short service life. Using coal gasification ash as a carrier not only has economic advantages but also conforms to the concept of sustainable development. At the same time, during the catalyst production process, no harmful components mentioned in the national hazardous waste identification standard (leaching toxicity identification GB5085.3-2007) are added. The catalyst after the reaction can be recovered and reused through simple treatment, reducing catalyst consumption and environmental pollution.

[0021] The present embodiment relates to a pilot test device for the catalytic ozone oxidation of wastewater from a Lurgi furnace gasification process, further comprising a water inlet pump, a digestion tank, and a centrifugal device. The water inlet pump is connected to the water inlet of the circulation tank 3 via a pipeline, and the outlet of the circulation tank 3 is connected to the digestion tank and the centrifugal device in turn via a pipeline. A water inlet valve is installed on the pipeline near the water inlet, and a drain valve is installed on the pipeline near the drain outlet. The pilot test device for the catalytic ozone oxidation of wastewater from a Lurgi furnace gasification process is an intermittent reaction device. During the pilot test, the wastewater in the circulation tank is replaced every 2 hours. Specifically, the peristaltic pump is turned off, the drain valve is opened, and the treated wastewater in the circulation tank is transferred to the digestion tank for digestion under the action of the digestion solution. The wastewater is then centrifuged in the centrifugal device to remove chloride ions and other impurities in the wastewater. After treatment, the drain valve is turned off, the water inlet pump is turned on and the water inlet valve is opened, untreated wastewater is added to the circulation tank to a set water level, the water inlet pump and the water inlet valve are turned off, the peristaltic pump is turned on, and treatment is resumed. During the small-scale test, it was found that the Ce-Mn bimetallic oxide catalyst can be reused more than 20 times, that is, the wastewater in the circulating water tank is replaced 20 times and the catalyst is replaced once. The catalyst's degradation rate of organic matter is still above 80%, the attenuation rate is very low, and the stability is very good.

[0022] The present embodiment relates to a pilot device for ozone catalytic oxidation of wastewater from a Lurgi furnace gasification process, which further includes a controller, a liquid level meter, a counter, a timer, and an alarm. The liquid level meter is installed in the circulation tank 3, and the controller is respectively connected to the water inlet pump, the water inlet valve, the drain valve, the peristaltic pump, the centrifugal device, the liquid level meter, the counter, and the timer to realize automatic control of the pilot device. When the liquid level meter detects that the wastewater has been discharged, the drain valve is closed, the water inlet pump is started and the water inlet valve is opened to add untreated wastewater to the circulation tank; when the liquid level meter detects that the wastewater has been added to the set water level, the water inlet pump and the water inlet valve are closed, and the peristaltic pump is started. When the timer monitors that the peristaltic pump has worked for 2 hours, the peristaltic pump is turned off and the wastewater in the circulation tank is replaced. When the counter detects that the water inlet pump has worked 20 times, a signal is sent to the controller, and the controller controls the alarm to sound an alarm, reminding the staff to replace the catalyst.

[0023] The ozone in this utility model forms tiny bubbles within the micropores of the disc-type microporous aerator 603 and is evenly released into the water. These tiny bubbles have a large specific surface area, enabling rapid contact and mass exchange with water molecules, effectively improving the efficiency of oxygen dissolution and utilization. Furthermore, microporous aeration promotes water disturbance and enhances mixing, facilitating sufficient contact between microorganisms and pollutants, leading to their degradation.

[0024] As the wastewater treatment capacity of the pilot plant increases, the present invention divides the reactor into multiple independent reaction units by placing a screen in the ozone catalytic oxidation reactor 6. The introduction of the screen not only promotes the uniform distribution of catalyst particles, preventing them from piling up due to gravity and forming locally dense or sparse areas; it also effectively prevents the catalyst particles from migrating or wearing out during the operation of the device, thereby extending the service life of the catalyst. In addition, the presence of the screen changes the flow path of the gas in the device, causing it to present more complex flow patterns, such as vortexes and backflows. These flow patterns are conducive to the full mixing and contact of the gas and the catalyst, increasing the collision frequency between ozone molecules and the active sites of the catalyst, thereby promoting the progress of the ozone decomposition reaction. At the same time, the screen can also regulate the residence time of the gas in the device to a certain extent, ensuring that the ozone molecules have enough time to react with the catalyst, achieving a higher removal efficiency, and realizing precise control and optimization of the reaction process. When in use, when water and ozone flow under the screen, they will break up the catalyst so that it is evenly dispersed in each reaction chamber and fully reacts.

[0025] The hydroxyl radicals generated by the present invention are combined with Ce-Mn bimetallic oxide catalyst in the ozone catalytic oxidation reactor 6, and the Mn 2+Catalytically active sites, such as electrons and surface oxygen vacancies, promote ozone decomposition to generate reactive oxygen species (ROS). The addition of Ce increases surface defects in the catalyst, enhancing catalytic activity and the efficiency of ozone conversion to hydroxyl radicals. This increases the concentration of hydroxyl radicals, resulting in more thorough degradation of organic matter. Under the action of the catalyst, ozone molecules are first adsorbed on the catalyst surface, forming reactive intermediates. These reactive intermediates then react with the oxidized substances, oxidizing them into more manageable or harmless substances. This device achieves a COD removal rate of up to 90% for Lurgi furnace gasification wastewater, fully meeting wastewater discharge standards.

Claims

1. A Lurgi furnace coal gasification wastewater ozone catalytic oxidation pilot device, characterized in that: The invention comprises an oxygen cylinder, an ozone generator, a circulation tank, an ozone flowmeter, a peristaltic pump, an ozone catalytic oxidation reactor, a KI absorption device, a screen and a disc-type microporous aerator; the oxygen cylinder is connected to the ozone generator, the ozone generator is connected to the air inlet at the bottom of the ozone catalytic oxidation reactor through an air pipe, an ozone flowmeter is arranged on the air pipe at the rear end of the ozone generator, the circulation tank is connected to the liquid inlet at the bottom of the ozone catalytic oxidation reactor through a liquid pipe, and a peristaltic pump is fixed on the liquid pipe between the circulation tank and the ozone catalytic oxidation reactor. A dynamic pump is provided, the liquid inlet is located above the air inlet, the circulation tank is connected to the liquid outlet on the upper part of the ozone catalytic oxidation reactor through a liquid infusion pipe, the top of the ozone catalytic oxidation reactor is connected to the KI absorption device through an air infusion pipe, a disc-type microporous aerator is installed in the inner cavity of the ozone catalytic oxidation reactor between the liquid inlet and the air inlet, N screens are installed at equal intervals horizontally from top to bottom in the cavity of the ozone catalytic oxidation reactor between the disc-type microporous aerator and the air outlet, the screens divide the ozone catalytic oxidation reactor into N catalytic reaction chambers, and a Ce-Mn bimetallic oxide catalyst is placed on the screens.

2. The Lurgi furnace coal gasification wastewater ozone catalytic oxidation pilot device according to claim 1 is characterized in that: A feed port is provided on one side of each catalytic reaction chamber.

3. The Lurgi furnace coal gasification wastewater ozone catalytic oxidation pilot device according to claim 1 is characterized in that: The Ce-Mn bimetallic oxide catalyst is a spherical porous particle with a diameter of 3 to 5 mm.

4. The Lurgi furnace coal gasification wastewater ozone catalytic oxidation pilot device according to claim 1 is characterized in that: It also includes a water inlet pump, a digestion tank and a centrifugal device. The water inlet pump is connected to the water inlet of the circulation tank through a pipeline. The drain outlet of the circulation tank is connected to the digestion tank and the centrifugal device in turn through a pipeline. An inlet valve is installed on the pipeline near the water inlet, and a drain valve is installed on the pipeline near the drain outlet.

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