阅读说明：本技术 一种氨法烟气脱硫的曝气氧化装置和方法 (Aeration oxidation device and method for ammonia flue gas desulfurization ) 是由 柯昌华 徐承亮 陈文华 胡达清 葛春亮 赵国萍 徐灏 戴尚访 陈春峰 戎淑群 于 2021-08-09 设计创作，主要内容包括：本发明涉及氨法烟气脱硫的曝气氧化装置,包括氧化空气母管、氧化空气支管和冲洗水管；氧化空气母管位于氧化槽外并且高位、水平布置；氧化空气支管为氧化空气母管分支,氧化空气支管包括氧化槽外支管和氧化槽内支管,氧化槽外支管位于氧化槽外,由竖直支管和水平支管组成,氧化槽外支管的水平支管连通氧化槽内支管,氧化槽内支管位于氧化槽内底部；氧化槽内支管上开有若干氧化空气喷孔。本发明的有益效果是：本发明通过将曝气氧化装置母管外置于氧化槽外部而内部仅设置支管,布置时更方便,可以使得氧化空气能更均匀地分布在整个氧化槽的截面上,省掉传统技术中的布风板,节省投资,提高氧化空气的利用率和亚硫酸铵的氧化率。(The invention relates to an aeration oxidation device for ammonia flue gas desulfurization, which comprises an oxidation air main pipe, an oxidation air branch pipe and a flushing water pipe; the oxidation air main pipe is positioned outside the oxidation tank and is arranged horizontally at a high position; the oxidation air branch pipe is branched from the oxidation air main pipe and comprises an oxidation tank outer branch pipe and an oxidation tank inner branch pipe, the oxidation tank outer branch pipe is positioned outside the oxidation tank and consists of a vertical branch pipe and a horizontal branch pipe, the horizontal branch pipe of the oxidation tank outer branch pipe is communicated with the oxidation tank inner branch pipe, and the oxidation tank inner branch pipe is positioned at the bottom in the oxidation tank; the branch pipe in the oxidation tank is provided with a plurality of oxidation air jet holes. The invention has the beneficial effects that: the aeration oxidation device is convenient to arrange by arranging the main pipe of the aeration oxidation device outside the oxidation tank and only arranging the branch pipes inside the oxidation tank, so that the oxidation air can be more uniformly distributed on the section of the whole oxidation tank, an air distribution plate in the traditional technology is omitted, the investment is saved, and the utilization rate of the oxidation air and the oxidation rate of ammonium sulfite are improved.)

1. An aeration oxidation device for ammonia flue gas desulfurization is characterized in that: comprises an oxidation air main pipe (2), an oxidation air branch pipe and a flushing water pipe (9); the oxidation air main pipe (2) is positioned outside the oxidation tank (1) and is arranged horizontally at a high position; the oxidation air branch pipe is a branch of the oxidation air main pipe (2), the oxidation air branch pipe comprises an oxidation tank outer branch pipe (3) and an oxidation tank inner branch pipe (4), the oxidation tank outer branch pipe (3) is positioned outside the oxidation tank (1) and consists of a vertical branch pipe and a horizontal branch pipe, the horizontal branch pipe of the oxidation tank outer branch pipe (3) is communicated with the oxidation tank inner branch pipe (4), and the oxidation tank inner branch pipe (4) is positioned at the inner bottom of the oxidation tank (1); a plurality of oxidation air jet holes (5) are formed on the branch pipe (4) in the oxidation tank; the tail end of the branch pipe (4) in the oxidation tank is provided with a vertical downward open branch pipe tail end bent pipe (6); the horizontal branch pipe of every oxidation groove outer branch pipe (3) sets up tee bend (7) before advancing the oxidation groove, and the interface of tee bend (7) is continuous with the vertical branch pipe of oxidation groove outer branch pipe (3), and interface two links to each other with the horizontal branch pipe of oxidation groove outer branch pipe (3), and interface three links to each other with wash pipe (9), sets up flushometer (8) on wash pipe (9).

2. The ammonia flue gas desulfurization aeration oxidation apparatus according to claim 1, characterized in that: the oxidation air main pipe (2) is 1-1.5m higher than the running liquid level of the oxidation tank.

3. The ammonia flue gas desulfurization aeration oxidation apparatus according to claim 1, characterized in that: the oxidation air injection holes (5) are arranged in groups, the hole group distance is 120-200mm, and each group has 2 or 3 holes.

4. The ammonia flue gas desulfurization aeration oxidation apparatus according to claim 3, characterized in that: when the number of each group of oxidation air jet holes (5) is 2, the two oxidation air jet holes (5) are symmetrically arranged along the vertical central line of the cross section of the branch pipe, and the included angle is 90 degrees; when the number of each group of oxidation air jet holes (5) is 3, two oxidation air jet holes (5) are symmetrically arranged along the vertical central line of the cross section of the branch pipe, the included angle is 90 degrees, and the other oxidation air jet hole (5) is positioned at the bottom of the branch pipe (4) in the oxidation tank.

5. The ammonia flue gas desulfurization aeration oxidation apparatus according to claim 1, characterized in that: the air flow velocity of the oxidation air jet holes (5) is 30-60 m/s.

6. The ammonia flue gas desulfurization aeration oxidation apparatus according to claim 1, characterized in that: the oxygen-sulfur ratio is 2.0-4.0.

7. The ammonia flue gas desulfurization aeration oxidation apparatus according to claim 1, characterized in that: the flow velocity of the oxidation air in the oxidation air main pipe (2) and the oxidation air branch pipe is 10-30 m/s.

8. The ammonia flue gas desulfurization aeration oxidation apparatus according to claim 1, characterized in that: the diameter of the oxidation air branch pipe is 50-150 mm.

9. The ammonia flue gas desulfurization aeration oxidation apparatus according to claim 1, characterized in that: the aperture of the oxidation air jet hole (5) is 8-12 mm.

10. The working method of the aeration oxidation device for ammonia flue gas desulfurization according to claim 1, characterized in that: oxidizing air from an oxidizing fan enters a vertical branch pipe of an oxidizing tank outer branch pipe (3) vertically arranged outside an oxidizing tank after passing through an oxidizing air main pipe (2) horizontally arranged at a high position outside the oxidizing tank (1), then horizontally enters the oxidizing tank (1) through a horizontal branch pipe of the oxidizing tank outer branch pipe (3) horizontally arranged at the bottom of the oxidizing tank (1) and an oxidizing tank inner branch pipe (4), and finally is sprayed into a solution in the oxidizing tank (1) through an oxidizing air spray hole (5) on the oxidizing tank inner branch pipe (4); when the washing is carried out, a washing valve (8) is opened, and the washing water washes the branch pipe (4) in the oxidation tank through a washing water pipe (9).

Technical Field

The invention relates to an aeration oxidation device and method for forced oxidation, in particular to a device and method for forcibly oxidizing ammonium sulfite generated by ammonia flue gas desulfurization into ammonium sulfate, and belongs to the technical field of wet ammonia flue gas desulfurization.

Background

China is a country with coal as a main energy source, and the occupation ratio of the China in primary energy is up to more than 75%. Sulfur dioxide produced by the combustion of coal is the most dominant atmospheric pollutant. The wet ammonia-ammonium sulfate flue gas desulfurization process is used as a resource recovery type environment-friendly process, and is applied and popularized in the flue gas desulfurization field of the industries such as electric power, chemical industry, metallurgy and the like due to the advantages of high gas-liquid reaction speed, high desulfurization efficiency and recyclable desulfurization byproducts. However, the ammonia flue gas desulfurization technology has the problems of ammonia escape, difficult oxidation of aerosol and ammonium sulfite, strong corrosiveness and the like for a long time.

The ammonia flue gas desulfurization technology takes ammonia as an absorbent to absorb sulfur dioxide in flue gas and then generate ammonium sulfite. Since ammonium sulfite is unstable and easily decomposed to release ammonia and sulfur dioxide again, it is necessary to oxidize the generated ammonium sulfite into stable ammonium sulfate. In the ammonia flue gas desulfurization engineering practice, an aeration type forced oxidation mode is adopted, air is pressurized and then is introduced into a solution containing ammonium sulfite, and oxygen in the air is dissolved in the solution and reacts with the ammonium sulfite to generate ammonium sulfate. However, the dissolved oxygen is inhibited due to the high concentration of dissolved salts in the slurry of the ammonia flue gas desulfurization system. Therefore, compared with the oxidation of calcium sulfite in the flue gas desulfurization technology of the limestone-gypsum method, the oxidation rate of ammonium sulfite is lower, and the ammonium sulfite is more difficult to be oxidized.

How to design an oxidation device, the oxidation rate of the ammonium sulfite is improved, and the ammonium sulfite is ensured to be completely oxidized; the utilization rate of the oxidation air is improved, the oxygen-sulfur ratio is reduced, and the energy consumption of the oxidation fan is reduced; meanwhile, the oxidation device is ensured not to be blocked, and the long-term reliable and stable operation can be realized. These become key problems to be solved urgently in the development process of the ammonia flue gas desulfurization technology.

In the prior art, the aeration oxidation device mainly has the problems of low utilization rate of oxidation air, frequent blockage of an aeration pipe and the like. At present, an aeration oxidation device adopts an oxidation air pipe with a 'rich' structure, namely a structure that a main pipe is added with a plurality of branch pipes with the diameter of 20-200mm, a plurality of small holes with the diameter of 3-30mm are arranged on the branch pipes, and the tail ends of the main pipe and the branch pipes are closed. Because the utilization rate of the oxidation air of the aeration device is low, an oxidation fan with a large oxygen-sulfur ratio (such as 2-8 times) and a large air volume needs to be selected. On the one hand, the energy consumption of the oxidation fan is high, on the other hand, the pipe diameter of the oxidation air main pipe is large, the sectional area blocked by the main pipe is large, and the distribution of the oxidation air is uneven. In order to improve the utilization rate of the oxidation air, 2-5 layers of air distribution plates are required to be arranged above the aeration oxidation device to strengthen the redistribution of the air, so that the investment and the pressure head of the oxidation fan are increased. The aeration oxidation device also has the function of stirring to prevent ammonium sulfate crystals in the slurry from depositing, but because the distribution of the oxidation air is not uniform, local ammonium sulfate deposition often occurs in actual operation, the deposited ammonium sulfate is more and more along with the increase of the operation time, the whole aeration oxidation device is buried, small holes on the branch pipes are blocked, and the oxidation fan is over-temperature and over-pressure. Due to the failure of on-line treatment, ammonia desulfurization systems are forced to be shut down to clean deposited ammonium sulfate in severe cases.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide an aeration oxidation device and a method for ammonia flue gas desulfurization, so as to improve the utilization rate of oxidation air and the distribution uniformity of the oxidation air, realize the anti-blocking flushing of the aeration oxidation device, reduce the energy consumption of the aeration oxidation device and improve the operation stability of the aeration oxidation device.

The aeration oxidation device for ammonia flue gas desulfurization comprises an oxidation air main pipe, an oxidation air branch pipe and a flushing water pipe; the oxidation air main pipe is positioned outside the oxidation tank and is arranged horizontally at a high position; the oxidation air branch pipe is branched from the oxidation air main pipe and comprises an oxidation tank outer branch pipe and an oxidation tank inner branch pipe, the oxidation tank outer branch pipe is positioned outside the oxidation tank and consists of a vertical branch pipe and a horizontal branch pipe, the horizontal branch pipe of the oxidation tank outer branch pipe is communicated with the oxidation tank inner branch pipe, and the oxidation tank inner branch pipe is positioned at the bottom in the oxidation tank; a plurality of oxidation air jet holes are formed in the branch pipe in the oxidation tank; the tail end of the branch pipe in the oxidation tank is provided with a vertical downward open branch pipe tail end bent pipe; the horizontal branch pipe of each oxidation tank outer branch pipe is provided with a tee joint in front of the oxidation tank, a first connector of the tee joint is connected with a vertical branch pipe of the oxidation tank outer branch pipe, a second connector of the tee joint is connected with the horizontal branch pipe of the oxidation tank outer branch pipe, a third connector of the tee joint is connected with a flushing water pipe, and the flushing water pipe is provided with a flushing valve.

Preferably, the method comprises the following steps: the operation liquid level of the oxidation air main pipe is 1-1.5m higher than that of the oxidation tank.

Preferably, the method comprises the following steps: the oxidation air jet holes are arranged in groups, the distance of the hole groups is 120-200mm, and each group comprises 2 or 3 holes.

Preferably, the method comprises the following steps: when the number of each group of oxidation air jet holes is 2, the two oxidation air jet holes are symmetrically arranged along the vertical central line of the cross section of the branch pipe, and the included angle is 90 degrees; when the number of each group of oxidation air jet holes is 3, two oxidation air jet holes are symmetrically arranged along the vertical central line of the cross section of the branch pipe, the included angle is 90 degrees, and the other oxidation air jet hole is positioned at the bottom of the branch pipe in the oxidation tank.

Preferably, the method comprises the following steps: the air flow rate of the oxidation air jet holes is 30-60 m/s.

Preferably, the method comprises the following steps: the oxygen-sulfur ratio is 2.0-4.0.

Preferably, the method comprises the following steps: the flow velocity of the oxidizing air in the oxidizing air main pipe and the oxidizing air branch pipe is 10-30 m/s.

Preferably, the method comprises the following steps: the diameter of the oxidation air branch pipe is 50-150 mm.

Preferably, the method comprises the following steps: the aperture of the oxidizing air jet hole is 8-12 mm.

The working method of the aeration oxidation device for ammonia flue gas desulfurization comprises the following steps that oxidation air from an oxidation fan enters a vertical branch pipe of an oxidation tank external branch pipe vertically arranged outside an oxidation tank after passing through an oxidation air main pipe which is arranged at a high position and horizontally outside the oxidation tank, then enters the oxidation tank horizontally through a horizontal branch pipe of the oxidation tank external branch pipe horizontally arranged at the bottom of the oxidation tank and an oxidation tank internal branch pipe, and finally is sprayed into a solution in the oxidation tank through oxidation air spray holes in the oxidation tank internal branch pipe; when the washing is carried out, the washing valve is opened, and the washing water washes the branch pipe in the oxidation tank through the washing water pipe.

The invention has the beneficial effects that:

1. the aeration oxidation device is convenient to arrange by arranging the main pipe of the aeration oxidation device outside the oxidation tank and only arranging the branch pipes inside the oxidation tank, so that the oxidation air can be more uniformly distributed on the section of the whole oxidation tank, an air distribution plate in the traditional technology is omitted, the investment is saved, and the utilization rate of the oxidation air and the oxidation rate of ammonium sulfite are improved.

2. According to the invention, through selecting a proper flow velocity of the branch pipe spray orifice of the aeration oxidation device, the dissolution and mass transfer of oxygen are enhanced, the equilibrium concentration of dissolved oxygen is improved, the oxidation rate of ammonium sulfite is improved, and the oxidation effect of the aeration oxidation device is improved.

3. The invention reduces the required oxidation air quantity and reduces the energy consumption of the oxidation fan by selecting the proper oxygen-sulfur ratio.

4. According to the invention, the tee joint and the flushing water pipe are arranged on each branch pipe of the aeration oxidation device, so that the online flushing of the oxidation air pipe can be realized, the aeration oxidation device is prevented from being blocked, and the operation reliability of the aeration oxidation device is improved.

5. The open type bent pipe is arranged at the tail end of the branch pipe of the aeration oxidation device, so that the off-line inspection and maintenance of the aeration oxidation device are facilitated, and the device has high practicability and wide application prospect.

Drawings

FIG. 1 is a schematic structural view of an aeration oxidation apparatus according to the present invention;

FIG. 2 is a schematic diagram of the arrangement of the inner branch pipes of the oxidation tank;

FIG. 3 is a schematic view of two orifice sets;

FIG. 4 is a schematic view of a hole formed by three orifice sets;

FIG. 5 is a graph of oxygen to sulfur ratio versus oxidation unit insertion depth.

Description of reference numerals: 1-an oxidation tank; 2-oxidizing the air main pipe; 3-oxidizing the outer branch pipe of the tank; 4-branch pipe in oxidation tank; 5-oxidizing air jet holes; 6-bending the tail end of the branch pipe; 7-a tee joint; 8-a flush valve; 9-flushing water pipe.

Detailed Description

The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Example one

The embodiment of the application provides an aeration oxidation device for ammonia flue gas desulfurization, which comprises an oxidation air main pipe 2, an oxidation air branch pipe and a flushing water pipe 9. The oxidation tank 1 is not provided with a main pipe and is only provided with a branch pipe, and the oxidation tank is also not required to be provided with an air distribution plate. The oxidation air main pipe 2 and the oxidation air branch pipes form a hand-shaped structure, the oxidation air main pipe and the oxidation air branch pipes are different from a ' feng ' shaped structure oxidation device in the prior art that the main pipe and the branch pipes are both positioned in an oxidation tank, a ' vertical ' in the feng ' is the main pipe, a ' horizontal ' is the branch pipes, and the branch pipes are distributed on two sides of the main pipe. Hand shape structure oxidation unit in this patent, perpendicular downwards behind the branch pipe that becomes required radical at the outer female pipe horizontal segment branch of oxidation groove, then follow the horizontal direction and get into the oxidation groove from oxidation tank bottom, only the branch pipe is located the oxidation groove, and female pipe is located outside the oxidation groove, and female pipe is just like the arm, and the branch pipe is just like the finger, easily arranges for the oxidation air can distribute more evenly.

The adding amount of the oxidation air is 2.0-4.0 times of the theoretical air amount required by the oxidation of the ammonium sulfite (hydrogen sulfite), namely the oxygen-sulfur ratio is 2.0-4.0, and the oxidation air volume is reduced so as to reduce the energy consumption of the oxidation fan.

The oxidation air main pipe 2 is positioned outside the oxidation tank 1, is horizontally arranged at a high position, and is 1-1.5m higher than the operating liquid level of the oxidation tank. The flow rate of the oxidizing air in the oxidizing air main pipe 2 is 20-25 m/s.

The oxidation air branch pipe is branched from a high-position and horizontally-arranged oxidation air main pipe 2 and comprises an oxidation tank outer branch pipe 3 and an oxidation tank inner branch pipe 4. The oxidation tank outer branch pipe 3 is positioned outside the oxidation tank 1 and consists of a vertical branch pipe and a horizontal branch pipe. The flow rate of the oxidation air in the branch pipe is 20-25m/s, the diameter of the branch pipe is DN100, so that the oxidation air is uniformly distributed on the cross section of the oxidation tank, and the utilization rate of the oxidation air is improved.

The horizontal branch pipe of the oxidation tank outer branch pipe 3 is communicated with the oxidation tank inner branch pipe 4, the oxidation tank inner branch pipe 4 is positioned at the bottom in the oxidation tank 1, the oxidation tank inner branch pipe 4 is provided with a plurality of oxidation air jet holes 5, the oxidation air jet holes 5 are arranged in groups, each group is 2 or 3, and the distance between the hole groups is 120-200 mm. When the number of each group of oxidation air jet holes 5 is 2, the two oxidation air jet holes 5 are symmetrically arranged along the vertical central line of the cross section of the branch pipe, and the included angle is 90 degrees. When the number of each group of oxidation air jet holes 5 is 3, two oxidation air jet holes 5 are symmetrically arranged along the vertical central line of the cross section of the branch pipe, and the included angle is 90 degrees; the other oxidation air jet hole 5 is positioned at the bottom of the branch pipe 4 in the oxidation tank and vertically jets downwards. The air flow velocity of the spray holes is 30-60m/s, so that the dissolution mass transfer of oxygen is enhanced, the dissolution of the oxygen is promoted, and the dissolution equilibrium concentration is improved. The aperture of the spray hole is 10mm, and the spray hole can be self-cleaned at high speed, so that the spray hole is not easy to block.

The tail end of the branch pipe 4 in the oxidation tank is provided with a vertically downward 90-degree bent pipe, the outlet of the bent pipe is not closed, a blind flange is not arranged, and when the oxidation device is stopped (off-line), whether the oxidation air pipe is blocked or not can be checked through the bent pipe, high-pressure water washing is carried out, and the like.

A tee joint 7 with the same diameter is arranged in front of each oxidation tank outer branch pipe 3 entering the oxidation tank, a first connector of the tee joint 7 is connected with a vertical branch pipe of the oxidation tank outer branch pipe 3, a second connector is connected with a horizontal branch pipe of the oxidation tank outer branch pipe 3, a third connector is connected with a flushing water pipe 9 of DN32-DN50, and the flushing water pipe 9 is provided with a flushing valve 8.

Example two

The second embodiment of the application provides a working method of an aeration oxidation device for ammonia flue gas desulfurization, which comprises the following steps:

1. the process comprises the following steps:

the process of the invention can be divided into two system steps:

1) aeration oxidation system

The system comprises an oxidation tank 1, an oxidation air main pipe 2, an oxidation tank outer branch pipe 3, an oxidation tank inner branch pipe 4 and the like. The method aims to uniformly distribute air required by completely oxidizing the ammonium sulfite in the oxidation tank into the ammonium sulfate in the solution in the oxidation tank, and the air is sprayed into the solution from the spray holes on the branch pipe in the oxidation tank at a high speed to strengthen the dissolution and mass transfer of oxygen, so that the utilization rate of the oxidation air and the oxidation rate of ammonium sulfite can be improved, the oxygen-sulfur ratio is reduced, the energy consumption of an oxidation fan is reduced, and the investment is saved.

2) On-line flushing system

The system comprises a tee joint 7, a flushing water valve 8, a flushing water pipe 9 and the like. The purpose is to periodically open the washing water to wash the branch pipe 4 in the oxidation tank so as to prevent ammonium sulfate crystallization, ammonia scale and the like from blocking the branch pipe and the spray hole, thereby greatly improving the long-term stable and reliable operation of the aeration oxidation device.

2. The main technological parameters are as follows:

1) the oxygen-sulfur ratio is 2.5-3.0. According to the reaction principle of ammonia desulfurization, the theoretical oxygen-sulfur ratio is 2.0. In practical engineering design, the actual oxygen-sulfur ratio will be higher than the theoretical oxygen-sulfur ratio, taking into account the mass transfer efficiency of oxygen. The mass transfer efficiency of the oxidizer oxygen is primarily determined by the depth of insertion of the oxidizer below the liquid level. The mass transfer effect of this patent oxidation unit oxygen is good, and actual oxygen sulfur ratio is low, and required oxidation amount of wind is few, and oxidation fan power consumption is low. The relationship between oxygen to sulfur ratio and the depth of insertion of the oxidizer is shown in FIG. 5.

2) The air flow velocity of the spray holes of the branch pipe in the oxidation tank is 40-50m/s, the diameter and the number of the spray holes are firstly determined, and then the diameter and the number of the spray holes are finely adjusted to ensure that the flow velocity is in the range.

3) The oxidation rate of the ammonium sulfite is not less than 99%.

3. The process flow comprises the following steps:

oxidizing air from an oxidizing fan enters a vertical branch pipe of an oxidizing tank outer branch pipe 3 vertically arranged outside an oxidizing tank after passing through an oxidizing air main pipe 2 horizontally arranged at a high position outside the oxidizing tank 1, then horizontally enters the oxidizing tank through a horizontal branch pipe of the oxidizing tank outer branch pipe 3 horizontally arranged at the bottom of the oxidizing tank 1 and an oxidizing tank inner branch pipe 4, and finally is sprayed into a solution in the oxidizing tank 1 through an oxidizing air spray hole 5 on the oxidizing tank inner branch pipe.

When the washing is needed, the washing valve 8 is opened, and the washing water washes the branch pipe 4 in the oxidation tank through the washing water pipe 9.

4. Application example:

the ammonia desulphurization engineering for the 480t/h boiler flue gas has the flue gas treatment amount of 650000Nm³H, inlet SO₂The concentration is 6000mg/Nm³Ammonia water with concentration of 15% is used as a desulfurizing agent, and all ammonium sulfite generated by desulfurization reaction is oxidized into stable ammonium sulfate by adopting the aeration oxidation device shown in figure 1.

The device is mainly characterized in that:

1) oxygen-sulfur ratio 2.5, oxidizing air quantity 7200Nm³/h。

2) The diameter of the oxidation air jet hole is 10mm, and the jet flow speed is 45 m/s. Operating parameters and results:

the oxidation rate of ammonium sulfite was 99.5%.