阅读说明：本技术 一种湿式催化氧化去除脱硫吸收塔浆液cod的方法 (Method for removing COD (chemical oxygen demand) of desulfurization absorption tower slurry by wet catalytic oxidation ) 是由 康秦豪 袁园 黄鑫 贾西部 郭静娟 邓悦 何新权 孙若晨 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种湿式催化氧化去除脱硫吸收塔浆液COD的方法,包括以下步骤：步骤一：在吸收塔本体中现有的氧化风管网层上布置催化装置；步骤二：在吸收塔本体外部布置加药装置；步骤三：进行湿式过氧化氢催化氧化反应：过氧化氢储罐采用带压注入的方式使得存储的过氧化氢溶液经过导管与吸收塔本体中的浆液中的有机组分一起透过微滤膜进入催化装置,与催化剂接触发生湿式过氧化氢催化氧化反应；步骤四：机械搅拌。本发明结构设计合理,能处理脱硫吸收塔内浆液中有机物,有效降低COD,从而从根本上解决有机物质聚集引起的浆液起泡造成的安全隐患。(The invention discloses a method for removing slurry COD (chemical oxygen demand) of a desulfurization absorption tower by wet catalytic oxidation, which comprises the following steps of: the method comprises the following steps: arranging a catalytic device on an existing oxidation air duct net layer in the absorption tower body; step two: arranging a dosing device outside the absorption tower body; step three: carrying out wet hydrogen peroxide catalytic oxidation reaction: the hydrogen peroxide storage tank adopts a pressurized injection mode to ensure that the stored hydrogen peroxide solution and organic components in the slurry in the absorption tower body penetrate through the microfiltration membrane through the conduit and enter the catalytic device to contact with the catalyst to generate a wet hydrogen peroxide catalytic oxidation reaction; step four: and (4) mechanically stirring. The invention has reasonable structural design, can treat organic matters in the slurry in the desulfurization absorption tower and effectively reduce COD, thereby fundamentally solving the potential safety hazard caused by slurry foaming caused by organic matter aggregation.)

1. A method for removing slurry COD in a desulfurization absorption tower by wet catalytic oxidation is characterized in that: the method comprises the following steps:

the method comprises the following steps: arranging a catalytic device on an existing oxidation air duct net layer in an absorption tower body: a catalyst, a catalyst filter screen, a catalyst frame and a micro-filtration membrane form a catalytic device, and then the catalytic device is arranged above the two sides of the oxidation air branch pipe in an inclined manner, is parallel to the oxidation air branch pipe and is vertical to the support beam;

step two: arranging a dosing device outside the absorption tower body: the hydrogen peroxide is stored in a hydrogen peroxide storage tank outside the absorption tower body, and then the hydrogen peroxide storage tank is communicated with the area of an air oxidation pipe net layer in the inner cavity of the absorption tower body through a guide pipe in a pressurized injection mode;

step three: carrying out wet hydrogen peroxide catalytic oxidation reaction:

a. sending oxidizing air into the oxidizing air branch pipe through an external oxidizing fan, enabling the oxidizing air to leave from small holes in the oxidizing air branch pipe and to be injected into the slurry, dispersing the oxidizing air into small particles through a catalytic device after the oxidizing air is injected into the slurry, enabling the small particles to rise to the surface of the slurry from an oxidizing air pipe net layer and enter an absorption area, and oxidizing sulfite in slurry in an absorption tower and fog drops in the absorption area into sulfate;

b. the hydrogen peroxide storage tank adopts a pressurized injection mode to ensure that the stored hydrogen peroxide solution and organic components in the slurry in the absorption tower body penetrate through the microfiltration membrane through the guide pipe and enter the catalytic device, the hydrogen peroxide solution is in contact with the catalyst to generate a wet hydrogen peroxide catalytic oxidation reaction, the organic matter is mineralized into small molecules and water, then the small molecules and the water pass through the microfiltration membrane and leave the catalytic device, and suspended matters in the slurry are intercepted on the surface of the microfiltration membrane;

step four: mechanical stirring: the agitator inside the absorption tower body is started to work, and under the influence of the agitator inside the absorption tower body, suspended matters intercepted on the surface of the microfiltration membrane are washed back into the slurry by the rising slurry, so that the smooth circulation of liquid inside and outside the catalytic device is kept, organic matters in the slurry inside the absorption tower body are convenient to treat, the COD is effectively reduced, and the potential safety hazard caused by slurry foaming caused by the aggregation of organic matters is fundamentally solved.

2. The method for removing the COD in the desulfurization absorption tower slurry by wet catalytic oxidation according to claim 1, which is characterized in that: the catalyst is a copper-based composite metal oxide catalyst, the equivalent diameter of the catalyst particles is between 5mm and 50mm, the catalyst adopts a coprecipitation method to successfully prepare a multi-element hydrotalcite-like precursor which takes carbonate as anions and contains divalent copper and zinc ions and trivalent aluminum, iron and lanthanum ions, and the corresponding composite metal oxide catalyst is obtained through pyrolysis.

3. The method for removing the COD in the desulfurization absorption tower slurry by wet catalytic oxidation according to claim 1, which is characterized in that: the gaps of the catalyst screens and the spacing of the catalyst frame are both smaller than the catalyst particle size.

4. The method for removing the COD in the desulfurization absorption tower slurry by wet catalytic oxidation according to claim 1, which is characterized in that: the micro-filtration membrane is a ceramic micro-filtration membrane or CN-CA membrane with the pore diameter ranging from 0.1 mu m to 1 mu m.

5. The method for removing the COD in the desulfurization absorption tower slurry by wet catalytic oxidation according to claim 1, which is characterized in that: the distance between the catalyst and the liquid surface in the absorption column body is usually 3 to 8 m.

Technical Field

The invention relates to the technical field of wet desulphurization and desulphurization absorption towers, in particular to a method for removing COD (chemical oxygen demand) in slurry of a desulphurization absorption tower by wet catalytic oxidation.

Background

Limestone-gypsum wet desulphurization (FGD) process is widely applied to thermal power plants in China, and has more strict requirements on a desulphurization system along with the continuous improvement of the atmospheric emission standard in China. Among them, slurry overflow caused by slurry foaming in the desulfurization and desulfurization absorption tower is one of the common problems in the operation of limestone-gypsum wet desulfurization systems.

Slurry foaming is mainly caused by the organic surface active molecules reducing the surface tension of water, while solid impurities increase the viscosity of the solution, thereby making the foam more stable and durable. Among them, the accumulation of organic substances is the most important cause of slurry foaming. Along with the continuous overflow of the foam of the desulfurization absorption tower outside the system, surfactant micelles in the slurry are continuously enriched on the surface of the aqueous solution, so that the phenomenon of continuous overflow of the foam is aggravated. When a large amount of bubbles appear on the liquid level of the slurry in the desulfurization absorption tower and exist for a long time, the slurry overflows. If the desulfurization control system fails to monitor in time and take effective measures to inhibit the development of the foaming phenomenon, the problems of reduction of desulfurization efficiency, reduction of gypsum quality, difficulty in control of the liquid level of the desulfurization absorption tower, increase of flue resistance, threat of the operation safety of a booster fan and the like can be caused, and the stability and the safe operation of the desulfurization system are influenced.

At present, the research mainly stays in the aspect of reason analysis and control prevention measures, but due to the complexity of a desulfurization system, timeliness and innovativeness are lacked, and the problem generally generated by long-term operation of the desulfurization system cannot be solved in time. At present, the most common method is to add the defoaming agent, although the method is effective in time at the initial stage of slurry foaming, the defects and the limitations are obvious, and continuous addition is needed, so that the content of organic substances in the slurry is continuously increased, the Chemical Oxygen Demand (COD) is continuously increased, the effect of adding the defoaming agent is weaker and weaker, and the more serious foaming problem can occur after the defoaming agent is stopped. Therefore, a method for removing the slurry COD in the desulfurization absorption tower by wet catalytic oxidation is provided.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provides a method for removing the COD in the slurry of the desulfurization absorption tower by wet catalytic oxidation, which can treat organic matters in the slurry in the desulfurization absorption tower and effectively reduce the COD in the slurry, thereby fundamentally solving the potential safety hazard caused by slurry foaming caused by organic matter aggregation.

In order to achieve the technical purpose and achieve the technical effect, the invention is realized by the following technical scheme:

a method for removing COD in slurry of a desulfurization absorption tower by wet catalytic oxidation comprises the following steps:

the method comprises the following steps: arranging a catalytic device on an existing oxidation air duct net layer in an absorption tower body: a catalyst, a catalyst filter screen, a catalyst frame and a micro-filtration membrane form a catalytic device, and then the catalytic device is arranged above the two sides of the oxidation air branch pipe in an inclined manner, is parallel to the oxidation air branch pipe and is vertical to the support beam;

step two: arranging a dosing device outside the absorption tower body: the hydrogen peroxide is stored in a hydrogen peroxide storage tank outside the absorption tower body, and then the hydrogen peroxide storage tank is communicated with the area of an air oxidation pipe net layer in the inner cavity of the absorption tower body through a guide pipe in a pressurized injection mode;

step three: carrying out wet hydrogen peroxide catalytic oxidation reaction:

a. sending oxidizing air into the oxidizing air branch pipe through an external oxidizing fan, enabling the oxidizing air to leave from small holes in the oxidizing air branch pipe and to be injected into the slurry, dispersing the oxidizing air into small particles through a catalytic device after the oxidizing air is injected into the slurry, enabling the small particles to rise to the surface of the slurry from an oxidizing air pipe net layer and enter an absorption area, and oxidizing sulfite in slurry in an absorption tower and fog drops in the absorption area into sulfate;

b. the hydrogen peroxide storage tank adopts a pressurized injection mode to ensure that the stored hydrogen peroxide solution and organic components in the slurry in the absorption tower body penetrate through the microfiltration membrane through the guide pipe and enter the catalytic device, the hydrogen peroxide solution is in contact with the catalyst to generate a wet hydrogen peroxide catalytic oxidation reaction, the organic matter is mineralized into small molecules and water, then the small molecules and the water pass through the microfiltration membrane and leave the catalytic device, and suspended matters in the slurry are intercepted on the surface of the microfiltration membrane;

step four: mechanical stirring: the agitator inside the absorption tower body is started to work, and under the influence of the agitator inside the absorption tower body, suspended matters intercepted on the surface of the microfiltration membrane are washed back into the slurry by the rising slurry, so that the smooth circulation of liquid inside and outside the catalytic device is kept, organic matters in the slurry inside the absorption tower body are convenient to treat, the COD is effectively reduced, and the potential safety hazard caused by slurry foaming caused by the aggregation of organic matters is fundamentally solved.

Preferably, the catalyst is a copper-based composite metal oxide catalyst, the equivalent diameter of the catalyst particles is between 5mm and 50mm, the catalyst adopts a coprecipitation method to successfully prepare a multi-element hydrotalcite-like precursor which takes carbonate as an anion and contains divalent copper and zinc ions and trivalent aluminum, iron and lanthanum ions, and the corresponding composite metal oxide catalyst is obtained through pyrolysis.

Based on the technical characteristics, the copper-based composite metal oxide catalyst is taken as a heterogeneous catalyst with high flexibility, low price and high catalytic efficiency, takes a composite oxide carrier, porous activated carbon, diatomite, a molecular sieve and the like as carriers, and is widely applied to industrial wastewater treatment, wherein more copper-based oxides are researched and used for carrying out catalytic oxidation reaction, and the catalyst prepared by being loaded in a porous carrier material has the characteristics of high stability and wear resistance, and particularly can enhance the mineralization of organic matters in wastewater, shorten the reaction time and reduce the reaction temperature and pressure.

Preferably, the gaps of the catalyst screens and the spacing of the catalyst frame are both smaller than the catalyst particle size.

Based on the technical characteristics, the catalyst is convenient to store in the catalytic device.

Preferably, the microfiltration membrane is a ceramic microfiltration membrane or a CN-CA membrane having a pore size in the range of 0.1 μm to 1 μm.

Based on the technical characteristics, the suspended matters can be effectively filtered, and the water solution and the soluble components can be permeated.

Preferably, the distance between the catalyst and the liquid surface in the desulfurization absorption tower slurry is generally 3-8 m.

Based on the technical characteristics, the liquid column pressure is between 0.3bar and 0.8bar, so that the working pressure of the microfiltration membrane is met, organic substances smoothly enter and exit the catalytic device to continuously react, and the COD of the slurry of the desulfurization absorption tower is effectively reduced.

Compared with the prior art, the invention has the following beneficial effects:

firstly, the method comprises the following steps: the invention relates to a method for removing COD (chemical oxygen demand) in slurry of a desulfurization absorption tower by wet catalytic oxidation, which adopts a wet catalytic oxidation method and utilizes a high-efficiency copper-based composite metal oxide catalyst with low price, flexibility, adjustability and strong stability to promote oxidation reaction and dispersion of bubbles of oxidizing air while removing organic matters in the slurry of the absorption tower, thereby improving the oxidation efficiency of the desulfurization absorption tower;

secondly, the method comprises the following steps: the invention relates to a method for removing COD (chemical oxygen demand) in slurry of a desulfurization absorption tower by wet catalytic oxidation, which adopts a built-in catalytic device, fully utilizes the reaction in the desulfurization absorption tower, is simple and efficient to transform and has little influence on a desulfurization system;

thirdly, the method comprises the following steps: the invention relates to a method for removing COD (chemical oxygen demand) in slurry of a desulfurization absorption tower by wet catalytic oxidation, wherein a microfiltration membrane is attached to the outer layer of a catalyst, water and soluble substances are infiltrated into the catalyst by utilizing hydraulic pressure to react with the catalyst, so that suspended matters in the slurry of the absorption tower are prevented from directly contacting the catalyst, and the condition that the catalyst is inactivated due to the blockage of a porous structure in the catalyst is further avoided.

Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a system layout diagram of a method for removing COD in a desulfurization absorption tower slurry by wet catalytic oxidation according to the present invention;

FIG. 2 is a schematic view of the structure of the catalytic device of the present invention;

FIG. 3 is a schematic diagram illustrating the position of the catalyst screen and the catalyst frame according to the present invention;

in the drawings, the components represented by the respective reference numerals are listed below:

1-an absorption tower body, 2-an oxidation air duct net layer, 3-a stirrer, 4-a support beam, 5-an oxidation air branch pipe, 6-a catalytic device, 7-a hydrogen peroxide storage tank, 8-a catalyst, 9-a catalyst filter screen, 10-a catalyst frame and 11-a micro-filtration membrane.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, a method for removing COD from a desulfurization absorption tower slurry by wet catalytic oxidation includes the following steps:

the method comprises the following steps: arranging a catalytic device 6 on the existing oxidation air duct net layer 2 in the absorption tower body 1: a catalyst 6 is formed by a catalyst 8, a catalyst filter screen 9, a catalyst frame 10 and a micro-filtration membrane 11, and then the catalyst 6 is arranged above the two sides of the oxidation air branch pipe 5 in an inclined manner, is parallel to the oxidation air branch pipe 5 and is vertical to the support beam 4;

step two: arranging a dosing device outside the absorption tower body 1: hydrogen peroxide is stored outside the absorption tower body 1 by using a hydrogen peroxide storage tank 7, and then the hydrogen peroxide storage tank 7 is communicated with the area of the air oxidation pipe net layer 2 in the inner cavity of the absorption tower body 1 by a guide pipe in a pressurized injection mode;

step three: carrying out wet hydrogen peroxide catalytic oxidation reaction:

a. the oxidizing air is sent into the oxidizing air branch pipe 5 through an external oxidizing fan, then leaves from the small hole on the oxidizing air branch pipe 5 and is injected into the slurry, after being injected into the slurry, the oxidizing air is dispersed into small particles through a catalytic device 6, rises to the surface of the slurry from the oxidizing air pipe net layer 2 and enters an absorption area, and sulfite in the slurry of the absorption tower and fog drops in the absorption area is oxidized into sulfate;

b. the hydrogen peroxide storage tank 7 adopts a pressurized injection mode to ensure that the stored hydrogen peroxide solution and organic components in the slurry in the absorption tower body 1 penetrate through the microfiltration membrane 11 through the guide pipe and enter the catalytic device 6, and contact with the catalyst 8 to generate a wet hydrogen peroxide catalytic oxidation reaction, the organic substances are mineralized into small molecules and water, and then the small molecules and the water pass through the microfiltration membrane 11 and leave the catalytic device 6, and suspended matters in the slurry are intercepted on the surface of the microfiltration membrane 11, in the process, on one hand, the air bubbles of the oxidizing air are smashed, so that the utilization rate of the oxidizing air is improved, and on the other hand, the catalyst 8 can promote the oxidation of sulfite in the slurry while oxidizing the organic substances;

step four: mechanical stirring: starting the stirrer 3 in the absorption tower body 1 to work, wherein suspended matters intercepted on the surface of the microfiltration membrane 11 are washed back into the slurry by the rising slurry under the influence of the operation of the stirrer 3 in the absorption tower body 1, and the smooth circulation of the liquid inside and outside the catalytic device 6 is kept;

the catalyst 8 in the above steps is a copper-based composite metal oxide catalyst, the equivalent diameter of the particles of the catalyst 8 is between 5mm and 50mm, the catalyst 8 adopts a coprecipitation method to successfully prepare a multi-element hydrotalcite precursor which takes carbonate as anion and contains divalent copper and zinc ions and trivalent aluminum, iron and lanthanum ions, the corresponding composite metal oxide catalyst is obtained through pyrolysis, the copper-based composite metal oxide catalyst is used as a multi-phase catalyst with high flexibility, low price and high catalytic efficiency, and the composite oxide carrier, porous active carbon, diatomite, molecular sieve and the like are used as carriers, so that the catalyst is widely applied in industrial wastewater treatment, wherein the copper-based composite metal oxide is more researched and used for implementing catalytic oxidation reaction, the catalyst loaded in the porous carrier material has the characteristics of high stability and wear resistance, and particularly can enhance the mineralization of organic matters in wastewater, the reaction time is shortened, the reaction temperature and the pressure are reduced, the gap of the catalyst filter screen 9 and the interval of the catalyst frame 10 are both smaller than the particle size of the catalyst 8, the catalyst 8 is convenient to store in the catalytic device 6, the micro-filtration membrane 11 is a ceramic micro-filtration membrane or CN-CA membrane with the aperture ranging from 0.1 mu m to 1 mu m, the suspended matters can be effectively filtered, the aqueous solution and the soluble components can permeate, the distance between the catalyst 8 and the liquid level in the absorption tower body 1 is usually 3 to 8m, the liquid column pressure is between 0.3bar and 0.8bar, thereby meeting the working pressure of the micro-filtration membrane 11, leading the organic substances to smoothly enter and exit the catalytic device 6 for continuous reaction, therefore, organic matters in the slurry in the desulfurization absorption tower can be conveniently treated, the COD of the slurry in the absorption tower body 1 is effectively reduced, and the potential safety hazard caused by slurry foaming caused by organic matter aggregation is fundamentally solved.

One specific application of this embodiment is: the invention has reasonable structural design, and by adopting a wet catalytic oxidation method and utilizing a high-efficiency copper-based composite metal oxide catalyst with low price, flexibility, adjustability and strong stability, the invention can promote the oxidation reaction and the dispersion of air bubbles of oxidizing air while removing organic matters in slurry of the absorption tower, thereby improving the oxidation efficiency of the desulfurization absorption tower; by adopting the built-in catalytic device 6, the reaction in the desulfurization absorption tower is fully utilized, the modification is simple and efficient, and the influence on a desulfurization system is small; meanwhile, the microfiltration membrane 11 is attached to the outer layer of the catalyst 8, and water and soluble substances are infiltrated into the catalyst 8 by utilizing hydraulic pressure to react with the catalyst 8, so that suspended matters in slurry of the absorption tower are prevented from directly contacting the catalyst 8, and the condition that the catalyst 8 is inactivated due to blockage of a porous structure in the catalyst 8 is further avoided.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.