A sulfuric acid absorption tower outlet flue gas acid mist testing device

Abstract

This utility model discloses an acid mist testing device for the outlet flue gas of a sulfuric acid absorption tower, comprising an outlet flue of the sulfuric acid absorption tower, a flue gas sampling valve, an acid mist detection chamber, a B sampling port closure device, an A sampling port closure device, a fan, an acid mist collection chamber, and an acid mist collection buffer chamber. A sampling pipe and a flue gas sampling valve are pre-installed on the outlet flue of the sulfuric acid absorption tower. The flue gas sampling valve is connected to the acid mist detection chamber via a flange. A sampling port is located at the top of the acid mist detection chamber. The sampling port is opened and closed by the B sampling port closure device and the A sampling port closure device. It is closed during non-detection periods to isolate the external environment. During detection, it is opened to allow the insertion of the test material. The fan is turned on before exhaust for testing to maintain negative pressure in the entire device and prevent flue gas escape. After exhausting for several minutes, the B sampling port closure device and the A sampling port closure device are opened to observe the negative pressure and flue gas dispersion, and the fan frequency is adjusted accordingly.

Description

Technical Field

[0001] This utility model relates to the technical field of copper smelting flue gas sampling, and specifically to an acid mist testing device for flue gas outlet of a sulfuric acid absorption tower. Background Technology

[0002] An acid absorption tower is a tower-type device used in the process of producing sulfuric acid to absorb sulfur trioxide gas generated in the conversion process. Inside the absorption tower, the process gas contains sulfur trioxide and water vapor, and concentrated sulfuric acid with a concentration of approximately 98% or 99% is sprayed down from the top of the tower.

[0003] Ideally, sulfur trioxide should be directly absorbed by the circulating acid solution. However, before sulfur trioxide gas molecules encounter acid droplets, they react with water vapor molecules in the process gas, directly synthesizing gaseous sulfuric acid molecules in the gas phase. In the low-temperature environment of the absorption tower, the partial pressure of this newly generated gaseous sulfuric acid far exceeds its saturated vapor pressure. This creates a highly supersaturated sulfuric acid vapor environment. This supersaturated state is extremely unstable. Gaseous sulfuric acid molecules spontaneously and rapidly collide and aggregate, forming tiny droplet nuclei. This process is called "homogeneous nucleation." Once the nuclei are formed, more gaseous sulfuric acid molecules condense on them, growing into suspended droplets typically between 0.1 and 10 micrometers in diameter, commonly known as acid mist. Furthermore, as the temperature decreases, gaseous sulfur trioxide reaches a supersaturated state, directly condensing into droplets composed of free sulfur trioxide dissolved in sulfuric acid, called fuming sulfuric acid droplets, which are also essentially a form of acid mist. Once stable submicron-sized acid mist droplets are formed, they become extremely difficult to capture by traditional absorption towers. Modern sulfuric acid absorption towers are equipped with demisters, installed before the gas outlet, to capture the generated acid mist and prevent acid droplet loss and corrosion of downstream equipment.

[0004] In the sulfuric acid industry, a visual inspection method for acid mist is commonly used. This is a very traditional, intuitive, but qualitative rather than quantitative, rapid on-site assessment method. Its purpose is to quickly and visually determine whether the flue gas at the absorber tower outlet contains acid mist and to roughly estimate the operating status of the demister. The principle mainly utilizes the extremely strong dehydrating and hygroscopic properties of concentrated sulfuric acid. When dry wooden boards or cotton strips are exposed to flue gas containing sulfuric acid mist, the sulfuric acid trioxide droplets or sulfuric acid vapor in the flue gas will rapidly absorb the moisture from the organic matter and carbonize it. An observation port with a flange and valve is usually provided on the flue wall at the absorber tower outlet.

[0005] The flue gas, towers, and pipelines of sulfuric acid production systems contain large amounts of water vapor and acid mist, resulting in extreme humidity and complex temperature variations. In rough areas of the pipe walls, weld depressions, and especially in airflow dead zones or low-speed areas such as the sampling port short pipe, acid mist condenses and accumulates very easily. These areas accumulate pools of concentrated liquid sulfuric acid, known as "acid buildup." Without pre-venting, placing a wooden board directly at the sampling port will cause the airflow to "blow" or "splash" these accumulated liquid acid droplets onto the board, instantly carbonizing them into large black spots. This severely distorts the test results, leading to a misjudgment of "serious acid mist leakage" and resulting in incorrect process adjustments. Opening the valve and allowing a high-speed main airflow to continuously flush the sampling short pipe for several minutes aims to thoroughly purge, evaporate, and remove the accumulated liquid acid in this dead zone using continuous, stable, and representative flue gas. After a period of purging, the temperature, humidity, and acid concentration inside the sampling short pipe will reach a dynamic equilibrium with the main flue gas flow. Only then can the gas coming out of the sampling port truly represent the real-time flue gas conditions within the main flue.

[0006] The specific procedure involves opening the valve and venting for several minutes. Then, place a dry, unpainted wooden board over the valve opening and observe the surface changes after a few seconds of airflow impact. If the board's color remains largely unchanged, or only slightly yellowed due to the high-temperature flue gas, it indicates a high absorption tower efficiency and thorough acid mist capture. If black spots or marks appear, this is due to localized carbonization by sulfuric acid. The more spots and the darker the color, the higher the relative concentration of acid mist. This is like bullet holes left on a target after being hit by acid mist. If the board is quickly burned through, or the entire surface turns black and smokes, it indicates severe acid mist escape and significant problems with the absorption tower's operation.

[0007] This method is simple and effective, but it poses safety and environmental risks. The flue gas temperature is high, posing a risk of burns. If the acid mist concentration is high and the flue gas is emitted under positive pressure, it can easily cause severe chemical burns. Opening the valve to vent for several minutes can lead to the leakage of toxic gases such as sulfur dioxide and sulfur trioxide. It also results in fugitive emissions of flue gas.

[0008] Therefore, how to ensure the normal conduct of acid mist testing while eliminating safety and environmental hazards is a problem worthy of study. Utility Model Content

[0009] In view of this, the purpose of this utility model is to provide a sulfuric acid absorption tower outlet flue gas acid mist testing device.

[0010] To achieve the above objectives, this utility model provides the following technical solution: A sulfuric acid absorption tower outlet flue gas acid mist testing device includes a sulfuric acid absorption tower outlet flue, a flue gas sampling valve, an acid mist detection chamber, a B sampling port closure device, an A sampling port closure device, a fan, an acid mist collection chamber, and an acid mist collection buffer chamber. A sampling pipe is branched off from the sulfuric acid absorption tower outlet flue, and a flue gas sampling valve is installed on the sampling pipe. The flue gas sampling valve is connected to the acid mist detection chamber via a flange. The top of the acid mist detection chamber has a sampling port that allows the test material to enter. The sampling port is equipped with a B sampling port closure device and an A sampling port closure device, thereby achieving opening and closing through the B sampling port closure device and the A sampling port closure device. The outlet of the acid mist detection chamber extends into the bottom of the acid mist collection buffer chamber via a pipe. The upper outlet of the acid mist collection buffer chamber is connected to the acid mist collection chamber via a pipe. The outlet of the acid mist collection chamber is connected to the fan via a pipe.

[0011] Furthermore, the acid mist collection chamber is equipped with an acid mist collection liquid, and the connecting pipe between the acid mist collection buffer chamber and the acid mist collection chamber extends below the surface of the acid mist collection liquid in the acid mist collection chamber.

[0012] Furthermore, the bottom of the acid mist detection chamber is equipped with an acid mist detection chamber condensate drain pipe, and the acid mist detection chamber condensate drain pipe is equipped with an acid mist detection chamber condensate drain valve.

[0013] During non-testing periods, sampling port B and sampling port A closures work together to seal the sampling ports, isolating them from the external environment. During testing, sampling port B and A closures are opened, and the sampling port is inserted into the testing material. Typically, a dry, unpainted wooden board is used, matching the size of the opening at the top of the acid mist detection chamber. Other materials can also be used, with paper applied to the surface. The testing time needs to be shortened. The fan is turned on before exhaust to maintain negative pressure in the entire equipment, preventing flue gas escape. After exhausting for several minutes, sampling port B and A closures are opened to observe the negative pressure and flue gas dissipation, adjusting the fan frequency as needed. The acid mist collection chamber is removable and contains acid mist collection liquid, using alkaline solutions or other solvents, to ensure sufficient absorption of the tested flue gas and guarantee that the gas exiting the fan meets standards. The acid mist collection buffer chamber provides gas buffering conditions, preventing flue gas pressure fluctuations and acid mist collection liquid backflow. The condensate drain valve in the acid mist detection chamber is regularly drained to prevent acid mist accumulation and corrosion of the equipment. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the acid mist testing device for flue gas at the outlet of a sulfuric acid absorption tower. Detailed Implementation

[0015] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings, but the protection scope of this utility model is not limited thereto.

[0016] A device for testing acid mist in flue gas from the outlet of a sulfuric acid absorption tower, such as Figure 1As shown, the system includes a sulfuric acid absorption tower outlet flue 1, a flue gas sampling valve 2, an acid mist detection chamber 3, a B sampling port closure 4, a testing material 5, an A sampling port closure 6, a fan 7, an acid mist collection chamber 8, an acid mist collection liquid 9, an acid mist collection buffer chamber 10, and an acid mist detection chamber condensate drain valve 11. A sampling pipe is branched off from the sulfuric acid absorption tower outlet flue 1, and a flue gas sampling valve 2 is installed on the sampling pipe. The flue gas sampling valve 2 is connected to the acid mist detection chamber 3 via a flange. The top of the acid mist detection chamber 3 has a sampling port that allows the testing material 5 to enter. The sampling port is equipped with a B sampling port closure 4 and an A sampling port closure 6, which together enable opening and closing. The outlet of the acid mist detection chamber 3 extends into the bottom of the acid mist collection buffer chamber 10 via a pipe. The upper outlet of the acid mist collection buffer chamber 10 is connected to the acid mist collection chamber 8 via a pipe. The outlet of the acid mist collection chamber 8 is connected to the fan 7 via a pipe. The bottom of the acid mist detection chamber 3 is equipped with an acid mist detection chamber condensate drain pipe, and the acid mist detection chamber condensate drain pipe is equipped with an acid mist detection chamber condensate drain valve 11.

[0017] The acid mist collection chamber 8 is equipped with acid mist collection liquid 9, and the connecting pipe between the acid mist collection buffer chamber 10 and the acid mist collection chamber 8 extends below the surface of the acid mist collection liquid 9 in the acid mist collection chamber 8. The acid mist detection chamber 3 has a sampling port at the top, which is opened and closed by sampling port closure device B 4 and sampling port closure device A 6. It is closed during non-detection periods to isolate the external environment.

[0018] The detection material 5 is typically a dry, unpainted wooden board, with the same opening size as the upper part of the acid mist detection chamber 3. Other materials can also be used, with paper sheets applied to the surface; however, the detection time needs to be shortened. Those skilled in the art observe the changes on the surface of the wooden board or paper. If the color of the wooden board or paper remains basically unchanged, or only slightly yellowed due to the high-temperature flue gas, it indicates that the absorption tower is highly efficient and the acid mist is captured very cleanly. If black spots or marks appear, this is because the sulfuric acid has locally carbonized them. The more spots and the darker the color, the higher the relative concentration of acid mist. This is like "bullet holes" left on a "target" after being "hit" by acid mist. If the wooden board or paper is quickly burned through, or the entire surface turns black and smokes, it indicates that the acid mist escape is very serious, and there are significant problems with the operation of the absorption tower.

[0019] The fan 7 is turned on before exhaust testing to maintain negative pressure in the entire equipment and prevent flue gas from escaping. After exhausting for several minutes, the B sampling port closure 4 and the A sampling port closure 6 are opened to observe the negative pressure and flue gas dispersion, and the frequency of the fan 7 is adjusted accordingly.

[0020] The acid mist collection chamber 8 is detachable and contains acid mist collection liquid 9. Alkali or other solvents are used to fully absorb the detected flue gas, ensuring that the gas at the fan outlet meets the standards.

[0021] The acid mist collection buffer chamber 10 provides conditions for gas buffering, avoiding flue gas pressure fluctuations and backflow of acid mist collection liquid 9.

[0022] The condensate drain valve 11 in the acid mist detection chamber is used to drain the condensate regularly to prevent acid mist from accumulating in the acid mist detection chamber 3 and corroding the device.

[0023] Sampling port closure device 4 (B) and sampling port closure device 6 (A) are existing technologies. Specifically, sampling port closure device 6 (A) is a sealing plate hinged to the sampling port. The sealing plate has a pin hole and a sealing strip around its perimeter. Sampling port closure device 4 (B) is a pin seat with a pin shaft. During non-testing periods, sampling port closure device 6 (A) seals the sampling port and is connected to sampling port closure device 4 (B) through the pin shaft and pin hole.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the specific implementation of this utility model and not to limit it. Those skilled in the art should understand that any equivalent substitutions or obvious modifications made to the implementation of this utility model without changing its performance or use, without violating the spirit of this utility model, should be covered within the scope of protection claimed by this utility model.

Claims

1. A device for testing acid mist in flue gas at the outlet of a sulfuric acid absorption tower, characterized in that, The system includes a sulfuric acid absorption tower outlet flue, a flue gas sampling valve, an acid mist detection chamber, a B sampling port closure device, an A sampling port closure device, a fan, an acid mist collection chamber, and an acid mist collection buffer chamber. A sampling pipe is branched off from the sulfuric acid absorption tower outlet flue, and a flue gas sampling valve is installed on the sampling pipe. The flue gas sampling valve is connected to the acid mist detection chamber via a flange. The top of the acid mist detection chamber has a sampling port that allows the sampled material to enter. The sampling port is equipped with a B sampling port closure device and an A sampling port closure device, which together enable opening and closing. The outlet of the acid mist detection chamber extends into the bottom of the acid mist collection buffer chamber via a pipe. The upper outlet of the acid mist collection buffer chamber is connected to the acid mist collection chamber via a pipe. The outlet of the acid mist collection chamber is connected to the fan via a pipe.

2. The acid mist testing device for flue gas at the outlet of the sulfuric acid absorption tower according to claim 1, characterized in that, The acid mist collection chamber is equipped with acid mist collection liquid, and the connecting pipe between the acid mist collection buffer chamber and the acid mist collection chamber extends below the surface of the acid mist collection liquid in the acid mist collection chamber.

3. The acid mist testing device for flue gas at the outlet of the sulfuric acid absorption tower according to claim 1, characterized in that, The bottom of the acid mist detection chamber is equipped with a condensate drain pipe, and the condensate drain pipe is equipped with a condensate drain valve.

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