Food production is more important than other production, so it is necessary to strictly control the quality of compressed air. If the pollutants come into direct contact with food without separation, various physical and chemical reactions such as adsorption and absorption may occur with the food, which will eventually cause physical harm to consumers and unnecessary losses to the production of enterprises.

Compressed air used in food production can be divided into 3 categories:

Direct Contact: i.e. "compressed air used as part of production and processing, including the packaging and transport of safe food", compressed air that comes into direct contact with food or ingredients.

For example: gas for stirring food ingredients should have the same quality priority as any other ingredients.

Indirect contact: not in direct contact with food, gas used in packaging, transportation, storage and other processes.

For example: blow molding PET bottles with compressed air or preparing and opening bags before pouring into food.

Non-contact: There is also a small amount of compressed air that does not need to come into contact with food, but this type of compressed air also has different quality requirements according to its use scenarios.

For the compressed air in direct contact and indirect contact, ISO 8573 proposes corresponding quality standards, which stipulates that the pollutant content and particle size should be less than 1 micron, 1 mg/m3, the oil mist content should be less than 0.01 mg/m3, the pressure dew point Below -40℃td.

However, the compressed air used by most domestic food factories is dust-free and oil-free, but it is difficult to be water-free.

Excessive moisture content (pressure dew point higher than -26°C) is often accompanied by the growth of rust and bacteria in the pipeline, causing pollution to food raw materials and increasing the defect rate.

Through our more than ten years of visits in Guangdong, we found that the compressed air used by several well-known large-scale candy factories and moon cake factories is still mixed with a lot of water droplets and rust.

After many exchanges, it is concluded that the reason why this phenomenon cannot be improved is that the domestic compressed air drying technology is immature.

Most customers have not heard of the pressure dew point requirement, but only use a refrigerated dryer as a drying device, resulting in a large amount of liquid water at the gas end;

Some customers purchased equipment according to the standard, but the drying effect did not meet expectations, or the effect decreased after running for a long time. This phenomenon is common in traditional double-tower dryers.

The configuration of the correct air compressor station should be:

When choosing an air compressor, in order to ensure product quality, more oil-free air compressors are selected;

Compressed air filters generally need to choose 3-4 levels of filtration to ensure sufficient blocking of solid impurities and remaining oil;

In the selection of compressed air dryers, in order to achieve a pressure dew point below -26°C, a core adsorption dryer must be configured. If the intake air temperature is too high, it is sometimes necessary to use a cold dryer or a cold drying filter. .

Such an air compressor station configuration can meet the quality requirements of compressed air in food production.

Although dust and oil pollution are more harmful to food production, the filtration technology of such pollutants has been very mature, but the drying technology of water has not been a breakthrough.

It was not until the advent of the modular dryer and the core dryer that this dilemma was really broken, and it became a reality to make the compressed air pressure dew point reach the standard continuously and stably.

BY：Karen Chen