Dryer equipment is a device that uses heat energy to dry materials that contain moisture. The choice of heat source is directly related to the drying effect of the material. The use of heat energy plays a very important role in the drying process.

Reasonable selection of the heat source not only needs to ensure the drying effect of the material, but also needs to consider other factors such as energy conservation, environmental protection, and cost reduction.

The choice of heat source will directly determine the cost, quality, and benefit of drying in the future. So that we need to consider these aspects comprehensively from energy-saving, environmental protection, energy consumption, heat utilization. So how to choose a suitable heat source for the dryer, this article tells you through several following aspects.


The common heat source of dryer
At present, the common types of heat sources on the market are coal, oil, natural gas, electricity, air energy heat pump heating, biomass burning furnace, solar heating, microwave heating, etc. Different heat sources have their own different characteristics and scope of application. Next, I will introduce some commonly used heating methods for dryers.

Coal, oil, natural gas
Natural gas, fuel oil, coal and other heat sources as energy sources are mainly used in large-scale dryer equipment like drum dryer or cereal dryer. Because of their large energy, they play a very important role in industrial production.

As a solid fuel, coal can generate higher heat than fuel and natural gas at the same price. Therefore, using coal as a heat source will be more cost-effective. However, coal will produce smoke and dust during the combustion process, which will cause pollution to the environment.

Fuel oil can not only be burnt directly to produce flue gas, but also can exchange heat indirectly, with good stability. Compared with coal and oil, natural gas has a higher calorific value, but it’s pollution-free. It has the advantages of safe use, high calorific value and environmental protection.

Electric heating, air energy heat pump
Electric heating or air energy heat pump is generally more suitable for small dryer equipment like drying oven or belt dryer, they are generally used in laboratories and dust-free workshops. Because they don’t have any pollution and heat up quickly so that they can be put into use quickly.

Although both methods will produce electricity consumption, they are completely different planning principles. The traditional electric heating method consumes electric energy, while what the air energy heat pump consumes is the heat energy in the surrounding environment.

The traditional electric heating method mainly relies on electric heating. In the internal structure of the heat source, there are special heating elements that consume electric power to increase the temperature.

The heat pump dryer uses only a small amount of electricity to absorb a lot of heat from the surrounding environment and transfer it to the object to be heated. It has small energy consumption and a high energy conversion rate.

Although the cost of air energy heat pumps is higher, the heating efficiency is much higher than traditional electric heating. It can also save energy, reduce the emission of CO2 and other pollutants.

Biomass burner
The biomass burner is a kind of biomass pyrolysis burner that uses biomass particles and other organic biomass as fuel. Biomass fuel is recognized as an environmentally friendly fuel with the advantages of renewability, abundant total, and low pollution. For areas lacking coal, biomass energy can be fully utilized.
According to the conditions of the crops, the grain dryer for drying rice and other grains can use the rice husk stove for mixed combustion of rice husks and coal, which can achieve the purpose of saving energy costs.

Solar heating
As a renewable clean energy, solar energy has always been loved. Using solar energy as a heat source not only saves the cost of raw materials and transportation but also pollution-free. In some areas with sufficient sunshine, it is the best choice for the heat source.

Our solar dryer uses solar panels to convert solar energy into heat to gradually increase the temperature in the drying box. The hot air circulates in the drying box to take away the moisture of the material to achieve the drying effect.

Microwave heating
Microwave drying is a new type of drying method, there is a large number of experiments and data show that microwave drying is the fastest drying method. At the same time, in the drying process, it also has the effect of sterilization, so that the finished product after drying can maintain the original nutritional content and traditional flavor.
The microwave energy directly acts on the medium molecules to convert into heat energy. The penetration of the microwave enables the material to be heated inside and outside at the same time without the process of heat conduction. It has the advantages of fast drying speed, uniform drying, easy accessibility and non-pollution.

Heat Source Selection Tips
Different customers have different requirements for heat sources, such as the output value of drying, material requirements, heating methods, etc. These factors directly affect the selection of heat sources. The characteristics of the drying material also play a vital role in the choice of the heat source. Different drying materials have different choices of heat source and heat exchange equipment. We first determine the material to be dried and then select the heat source that could make the choice of heat source more based.

[s]Select the heat source that matches the material characteristics[/s]
When selecting the heat source of the dryer, you need to pay attention to whether the fuel can meet the requirements of product quality. Different types of dryers have different heating temperatures, so they need different heat sources to match. At the same time, the cleanliness of the heat source also has a certain impact on the finished product. Therefore, when we select the heat source for the dryer, we must make a corresponding analysis of the heating temperature and the cleanliness of the heat source according to the quality requirements of the items to be dried and the products after being dried.

If the processed solid material is not afraid of high temperature and is not the final product, and it can be allowed to be slightly polluted during the process. So the hot blast stove or flue gas can be used as the heating medium to obtain a higher volume evaporation rate and thermal efficiency. For the drum dryer for processing ore, sand, coal and other materials, there is a furnace that can directly generate flue gas, the gas fuel can be coal, oil, natural gas, liquefied gas, etc.

[s]Choose the heat source according to the local conditions[/s]
The local energy resources must be considered when choosing the dryer to achieve reasonable utilization and cost-effectiveness.
In areas with coal mines, we can use coal, anthracite or coke as the heat source, their price is more economical, but the one-time investment in coal-fired hot blast stoves is large. And in areas with oil fields and natural gas, oil or natural gas can be used as the hot blast stove fuel. This type of fuel is expensive to use, but the one-time investment in the hot blast stove is smaller. The special seed dryer should use the oil or natural gas hot air stove, because its air temperature is stable, easy to control, and can ensure the germination rate of dried seeds.

Precautions in the heat source selection
Sometimes we need to dry some flammable, explosive or oxidizable materials which can’t be dried with direct-fire heat sources during production activities.

When processing these materials, indirect heat exchange heat sources should be used, which can effectively dry this kind of materials. Of course, if the direct-fired type is selected, special flame-retardant or explosion-proof measures must be required.

Quite an interesting write up. We may need to work out things together very soon. Thanks @ OP.