Deodorizing equipment

1Deodorizing equipmentCore principle: Chemical absorption

The essence of deodorization in spray towers is a chemical absorption process, rather than a simple physical water washing. The core principle is to utilize the different solubility of odor components in the absorption liquid or their ability to react chemically with active agents in the absorption liquid, thereby transferring odor from the gas phase (air) to the liquid phase (absorption liquid) for purification purposes.

The entire process can be summarized into the following three steps:

1. Gas liquid contact: Waste gas containing odor is sucked into the tower by a fan and flows from bottom to top. At the same time, the absorbing liquid is high-pressure sprayed out through the nozzle at the top of the tower, forming fine mist like water droplets that settle from top to bottom.

2. Mass transfer and reaction: The packing layer (such as Bauer ring, Raschii ring, etc.) filled in the tower allows for sufficient and efficient reverse contact between the exhaust gas and the absorption liquid. Odor molecules diffuse from the gas phase to the gas-liquid interface, then dissolve in the absorbent and rapidly undergo neutralization or oxidation reactions with the chemical agents present.

3. Separation: The treated clean gas continues to rise, passes through the dehazing layer to remove entrained water droplets, and is discharged from the top of the tower. The liquid that absorbs the odor settles at the bottom of the tower for recycling or discharge.

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2、 Key components

A typical spray tower mainly consists of the following parts:

1. Tower body: usually made of PP (poly), FRP (fiberglass reinforced plastic) or stainless steel, with good corrosion resistance.

2. Packing layer: The core component inside the tower, providing a large specific surface area to enable full contact between gas-liquid phases and improve mass transfer efficiency.

3. Spray system: including water pump, pipeline, nozzle, responsible for evenly spraying the absorbent onto the filling material.

4. Mist remover: located at the top of the tower, it is used to separate the liquid droplets carried in the purified gas and prevent the liquid from being carried out of the tower.

5. Circulating water tank: located at the bottom of the tower, used for storing and circulating absorption liquid.

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3、 The key to deodorization: selection of absorbent solution (agent)

The deodorization effect of the spray tower directly depends on the type of absorbing liquid. Different chemical agents need to be selected for different odor components:

Recommended absorption solution (agent) deodorization principle for typical sources of odor main components

Neutralization reaction of acidic solutions such as alkaline odor (such as NH?) in wastewater treatment, breeding farms, fertilizer plants, dilute (H? SO?), (HCl), etc.: 2NH?+H? SO? → (NH?)? SO? (Generate odorless ammonium, which can be used as fertilizer)

Acidic odor (such as H? S, SO?)? 、 Neutralization reaction of alkaline solutions such as VOCs acids in wastewater treatment, garbage stations, and chemical industry (NaOH): H? S+2NaOH → Na? S+2H? O

Organic sulfides, other complex VOCs (such as thiols) in landfills, food processing, refining (NaClO), (H? O?), ozone (O?) aqueous solutions, and other oxidation reactions: oxidize odorous organic compounds into odorless or low odor substances such as sulfonic acid, carbon dioxide, and water.

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4、 Advantages and disadvantages of spray tower deodorization

Advantages:

1. Mature technology, low cost: simple structure, relatively low initial investment and operation maintenance costs.

2. High processing efficiency: for odors with good water solubility or the ability to undergo rapid chemical reactions (such as NH?, H?)? S）， The removal efficiency can reach over 90%.

3. It has both dust removal and cooling functions: it can effectively remove dust particles from exhaust gas and have a cooling effect on high-temperature exhaust gas.

4. Safe and reliable: easy to operate, stable operation.

Disadvantages:

1. There is a risk of secondary pollution: after the absorption liquid is saturated, it needs to be replaced, which will generate wastewater and must be properly treated, otherwise it will cause secondary pollution.

2. Strong targeting: Limited removal effect on odorous substances with poor water solubility and low chemical reactivity (such as certain non-polar VOCs).

3. Operating costs: It requires continuous consumption of water and chemicals, as well as electricity to drive water pumps and fans.

4. Equipment is prone to blockage/corrosion: If the dust content in the exhaust gas is high or strong corrosive agents are used, it may cause nozzle and packing blockage and corrosion of the equipment.

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5、 Application scenarios

Spray towers are very suitable for handling odors generated in the following situations:

·Wastewater treatment plant: ammonia and odor generated from pre-treatment grilles, sedimentation tanks, sludge treatment workshops, etc.

·Garbage transfer station/compression station: Collected garbage odor.

·Catering fumes: As a pre-treatment, remove some acidic gases and particulate matter from the fumes.

·Chemical, pharmaceutical, and electroplating workshops: deal with specific acidic or alkaline waste gases generated during the production process.

·Livestock and poultry farms: Ventilation and deodorization of enclosed poultry houses.

6、 Comparison between Spray Tower and Plasma Deodorization

Characteristic Spray Tower (Chemical Washing) High Energy Plasma

Principle of chemical absorption (neutralization/oxidation), high-energy electric field cracking, oxidation

Suitable for gases with good water solubility and clear acidity and alkalinity in exhaust gas, especially suitable for low to medium concentrations, high air volume, and complex VOCs

Secondary pollution can generate wastewater that needs to be treated, but may produce trace amounts of ozone

Operating costs include medication fees, water fees, and electricity fees, mainly electricity fees

Regular replacement of chemicals is required for maintenance, and regular cleaning of electrodes is necessary for clearing blockages

summary

Spray tower is an efficient and economical deodorization method, but the key to its successful application lies in "targeted treatment". It is necessary to first analyze the specific components of the odor and then select a suitable chemical absorption solution in order to achieve the desired treatment effect. In practical engineering, spray towers are often combined with activated carbon adsorption towers and plasma adsorption towersDeodorizing equipmentOr a combination of photocatalytic equipment can be used to form a complete purification system capable of treating complex odors.