What Is Dew Point?

Dew point is the temperature at which a gas is cooled and the water vapor it contains begins to form liquid or solid condensate. The unit is °C. The dew point temperature is a very intuitive reflection of the moisture contained in the gas.

In a sense, controlling dew point is a key condition for industrial production efficiency and product quality. So what is dew point? Why is the industrial field pursuing low dew point?

What is dew point?

It can be simply understood as the air temperature when the water vapor content in the air reaches saturation and condenses into liquid water under a certain atmospheric pressure. At this temperature, condensed water floating in the air is called fog, and when it sticks to a solid surface it is called dew.

For most process industries, moisture is an adverse contaminant that can lead to poor product quality, pipe corrosion, cryogenic freezing, premature wear and equipment failure, as well as reactions with other chemicals and gases.

In industry, dew point temperature is a critical parameter. For example, in specific processes such as drying, refrigeration, and gas treatment, insufficient dew point temperature control can lead to corrosion and damage to components, which can lead to mechanical failure, contamination, and freezing.

Real-time monitoring and control of dew point temperature is the key to controlling air humidity, ensuring product quality and improving production efficiency.

Examples

1. The sulfur content in the fuel is high and the dew point is also high. When fuel is burned, sulfur dioxide is generated, which is further oxidized into sulfur trioxide. Sulfur trioxide and water vapor in the flue gas generate sulfuric acid vapor. If the exhaust gas temperature is too low, dilute sulfuric acid will form and adhere to the pipelines, corroding them. This is called dew point corrosion.

2. Some chemical reactions are sensitive to water, such as the polymerization of propylene. The catalyst will react or even explode when exposed to water, leading to reaction failure or safety accidents. This also requires nitrogen replacement before driving until the dew point analysis is qualified, such as Dew point -20℃.

3. The development of precision industry is inseparable from the cooperation of dew point. Take the welding of engine blades as an example. If the humidity of the argon gas used for argon arc welding is too high, blackening will occur, and the blades will become brittle and the temperature resistance will deteriorate. Use There will be an accident. Some clean rooms and drying rooms in lithium battery production have extremely high requirements for dew point detection. Other common applications include medical gases, dry environments in lithium battery production and high-voltage gas-insulated equipment used in the power industry.

Monitoring the dew point in process gases can bring the following benefits:

1. Process safety and protective equipment: Excess moisture in pipelines may cause corrosion, reduce the integrity of the equipment, and may cause leaks or even explosions. In cold conditions, ice can form and clog pipes. Controlling humidity reduces the need for unscheduled maintenance and protects employees.

2. Quality: Moisture has an adverse effect on many final products. In metallurgy, moisture levels within the furnace need to be carefully controlled to prevent the product from weakening, while in pharmaceutical production, powders must be kept dry to avoid clumping. Refineries require low moisture to avoid unnecessary chemical reactions. In processes that require high gas purity, moisture as a pollutant must be monitored in a timely manner.

3. Energy Saving: The highest cost of many processes is the heat required by the dryer. Monitoring the dryer output ensures that as soon as the drying cycle is complete, the cycle can be stopped.

4. Meet specifications: Many global industry organizations agree on international quality standards, which often include moisture or dew point levels. For example, EASEE natural gas standards for natural gas quality.

Stability and accuracy are the biggest challenges in dew point measurement

The importance of dew point temperature determines that dew point measurement must be accurate to avoid losses.

In many industries, such as petrochemical, electric power, electronics, aerospace, metallurgy, textile, etc., the requirements for dew point measurement are getting higher and higher. In the field of dew point measurement, dew point technology is becoming more and more perfect. There are currently many measurement principles and various dew point measurement instruments at home and abroad.

Dew point meter is an instrument that can directly measure the dew point temperature in air or gas. It is a kind of temperature and humidity sensor and occupies a very important position in modern humidity measurement technology.

It is often used in workshops, factories, warehouses, laboratories and other environments that need to monitor temperature and humidity. It can help production and quality control departments accurately grasp the dew point of compressed gas, continuously and accurately control product quality, and enhance product value.