How should the chemical filter of the air conditioning box be arranged before and after the humidification section?

When there are both a humidification section and a chemical filtration section in the air-conditioning box, the relationship between the two needs to be confirmed during the design stage.

Different humidification methods have different effects on the chemical filtration section. Steam humidification, high-pressure spray humidification, and wet film humidification have different air conditions and droplet risks. Whether the chemical filtration section is placed before or after the humidification section depends on whether the filter material can adapt to the temperature and humidity conditions at that location, and whether there is a risk of direct contact with droplets.

First identify the impact of humidification methods

The humidification method determines the air condition downstream of the humidification section.

Steam humidification. Steam is sprayed directly into the air. After humidification, the air temperature rises slightly and the relative humidity increases, but there is usually no entrainment of liquid water droplets. If the steam quality is up to standard and the absorption distance is sufficient, the downstream air will be close to a gaseous state.

High pressure spray humidification. Water is atomized into tiny droplets and sprayed into the air, requiring sufficient evaporation distance. If the distance is insufficient or the water volume is too large, some droplets may not completely evaporate and enter the downstream section with the air flow.

Wet film humidification. The air passes through the moist film and the water evaporates into the air. The wet film itself has a trapping effect, but when the wind speed is too high or the wet film is in poor condition, water droplets may be entrained.

Different humidification methods have different risks of droplets downstream. Steam humidification is generally low risk, and spray and wet film humidification require confirmation of evaporation distance and water blocking measures. For specific filter segment configuration, please refer to Discussion on why MAU needs to configure chemical filtration section .

Identify the effects of humidification

After confirming the humidification method, it is also necessary to look at its specific impact on the chemical filtration section.

Humidity level. The relative humidity of the air usually increases after humidification. The adsorption capacity of some chemical media decreases in high-humidity environments, or the properties of impregnated components change after absorbing moisture. For specific impacts, please refer to Discussion on whether to choose activated carbon or other adsorption media for chemical filters .

Droplet entrainment. If there are droplets downstream of the humidification section, the chemical filter section may become damp. Liquid droplets entering the filter material may cause hardening, blocked channels, or reduced capacity. The chemical filtration section cannot replace the water removal structure, and droplet control relies on water baffles or separators.

temperature changes. Steam humidification may cause the air temperature to rise slightly; spray humidification and evaporation may cause the temperature to drop slightly by absorbing heat. Temperature changes have a certain impact on the adsorption or reaction process. When selecting, confirm the suitability of the filter material at the target temperature.

absorption distance. There needs to be enough distance between the humidification section and the next functional section to allow water to evaporate or droplets to settle. If the absorption distance is insufficient, the chemical filter section may be directly facing the incompletely evaporated droplets. For specific layout methods, please refer to Discussion on whether the MAU chemical filter should be installed before or after the surface cooler .

The situation when the chemical filtration section is placed before the humidification section

Placed before the humidification section, the chemical filter section contacts the air before humidification.

advantage. The relative humidity of the air is usually lower than after humidification, which is more friendly to humidity-sensitive media. If the filter material is sensitive to high humidity, it can be placed in front of the humidification section to avoid the high humidity environment. At the same time, the air treated in the filter section then enters the humidification section, and no new gaseous pollution will be introduced due to humidification.

Need to pay attention. If the humidification section itself may produce gaseous pollution (for example, some humidification water sources contain volatile components), this part of the pollution is downstream of the filtration section and cannot be processed by the chemical filtration section. In this case, it is necessary to set up additional treatment measures after the humidification section, or choose a humidification method with controllable water quality.

spatial conditions. Whether the location in front of the humidification section is sufficient to install the chemical filter section and whether the maintenance access is convenient should be confirmed during the design stage. Please refer to the specific structure Discussion of the common product forms of chemical filters .

The chemical filtration section is placed after the humidification section

After being placed in the humidification section, the chemical filter section contacts the humidified air.

advantage. Gaseous contamination that may be introduced in the humidification section can be dealt with. If the humidification water source or steam contains trace amounts of volatile components, the filter section can play a protective role. At the same time, the filter section is located before the end of the air supply, and the treated air is directly sent to the protected area.

Need to pay attention. The air humidity after humidification is high and the risk of droplets is high. The chemical filtration section must confirm the suitability of the filter material under high-humidity conditions, and there must be reliable water-blocking measures in front. If droplets enter the filter material, it may affect the capacity and resistance. For specific inspection methods, please refer to Discussion on how to deal with dust falling on the surface of chemical filters .

Maintenance frequency may increase. In a high-humidity environment, the filter replacement cycle may be shorter than in a dry environment. Projects need to evaluate replacement costs and downtime arrangements.

Review the working conditions throughout the year

The operating status of the humidification section changes with the seasons, and the layout of the chemical filtration section should cover the operating conditions throughout the year.

Humidification in winter. In winter, the outdoor air is dry, the humidification section has a high operating load, and the air humidity may be high after humidification. The chemical filtration section faces the most unfavorable humidity conditions during this season.

Dehumidification in summer. In summer, the outdoor air is humid. After dehumidification by the surface cooler, the air humidity is already high, and rehumidification is rare. However, the impact of the high-humidity environment after the surface cooler on the chemical filtration section still exists.

Season of transition. Humidification and dehumidification may operate alternately, and the temperature and humidity conditions faced by the chemical filtration section vary greatly. When selecting, confirm the stability of the filter material under changing conditions.

Seasonal changes and starts and stops can change humidity and temperature. The layout plan should cover representative conditions and retain front and rear measurement points and replacement space. For specific recording requirements, please refer to Discussion of sampling points for chemical filter performance verification .

Project judgment example

A certain MAU project needs to configure both a humidification section and a chemical filtration section in the air-conditioning box to process the acid gas input from the outside.

The humidification method is high-pressure spray humidification. The preliminary plan places the chemical filtration section after the humidification section, thinking that the humidified air can be processed. However, the inspection found that the evaporation distance after the humidification section was insufficient, and some droplets may be entrained into the downstream.

Adjustment plan: Add a water baffle after the humidification section to ensure droplet separation; place the chemical filter section after the water baffle to confirm that there is no liquid water in the air entering the filter section. At the same time, check the suitability of the filter material under high humidity conditions and select media with suitable moisture resistance. After operation, the outlet concentration and pressure difference changes are detected to confirm that the requirements are met.

This case illustrates: The selection before and after the humidification section should be based on a comprehensive judgment based on the humidification method and the risk of droplets. involving When selecting MAU box-type chemical filters , it is recommended to provide the humidification method, temperature and humidity data and system conditions to the supplier for verification.

Key points for selection and acceptance inspection

About Aili Industrial’s chemical filtration package for air conditioning boxes

The core of the layout of the chemical filtration section and humidification section of the air-conditioning box is to match the humidification method, temperature and humidity conditions, filter material suitability and maintenance conditions.

Aili Industrial has independent manufacturing capabilities in filters, motors, fans, control systems and sheet metal processing, and can provide chemical filter product series and supporting air supply equipment. For air conditioning box projects, the humidification method, temperature and humidity data, filter section location and replacement space can be combined to assist in checking the media type and structural configuration. When the filter is matched with MAU, FFU, EFU and other equipment, the resistance, interface and maintenance methods can be confirmed uniformly.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . Provide humidification method, temperature and humidity conditions and system requirements when enquiring, which will help confirm the appropriate filter section layout plan. The specific selection is subject to the technical documents and test results confirmed by the project.