The GRL series hot-air furnace is a high-efficiency, energy-saving, new-type heat-exchange device independently developed by our factory. It uses coal, biomass, gas, or oil as fuel and delivers clean, pollution-free hot air through radiation heat transfer, conduction heat transfer, and convection heat transfer.

Product Introduction

The GRL series hot-air furnace is a high-efficiency, energy-saving, new-type heat-exchange device independently developed by our factory. It uses coal, biomass, gas, or oil as fuel and delivers clean, pollution-free hot air through radiation heat transfer, conduction heat transfer, and convection heat transfer. The clean hot-air furnaces designed and manufactured by our company have been granted national patents.

Thanks to the optimization measures and innovative design adopted in this series of hot-air furnaces, heat transfer and heat exchange performance have been significantly enhanced, resulting in a high overall heat-transfer coefficient, rapid temperature rise, and substantial thermal storage capacity for the entire unit.

The GRL series hot-air furnace, as a new type of heat-source equipment, can replace steam heat exchangers, thermal-oil heat exchangers, and electric air heaters, offering advantages such as compact size, easy installation and transportation, and low energy consumption. It is widely applicable in various operations including drying, heating, heat preservation, and dehumidification, and when paired with drying equipment such as cyclone flash dryers, pressure spray dryers, and vibratory fluidized-bed dryers, it can maximize the performance of the entire system.

Working Principle

The GRL series hot-air furnaces are available in two configurations: vertical and horizontal. The vertical coal-fired (or biomass-pellet-fired) hot-air furnace can be further customized according to customer requirements as either a manual-firing unit or an mechanically-fired unit. It consists of two main components: the combustion chamber and the heat-exchanger assembly. High-temperature flue gases generated in the combustion chamber enter the heat-exchanger assembly, where they undergo multi-pass counterflow heat exchange with cold air supplied by a blower through both radiation and convection. After the cold air is heated to the desired temperature, it is discharged through the hot-air outlet of the furnace and delivered to the heat-using equipment. The flue gases are drawn out by an induced-draft fan and then passed through a flue-gas separator and a dust collector before being vented to the atmosphere.

The hot air does not come into direct contact with the material, thereby preventing flue-gas contamination; this makes it suitable for materials with stringent requirements regarding whiteness and freedom from impurities.

Product Features

• Pure and contamination-free: Hot air is separated from combustion products, ensuring that the material remains uncontaminated.
• High efficiency and energy savings: large heat-exchange area and high heat-transfer efficiency, with some models achieving thermal efficiencies of 85% or higher.
• Temperature control: The hot-air temperature is precisely regulated via an intelligent PLC control system, with an output range of 100–450°C.
• Special Note: Our equipment features a multi-layer, sleeve-type all-metal construction (without refractory materials), thereby eliminating common issues associated with traditional equipment—such as cracking and spalling caused by differential thermal expansion and contraction due to varying material coefficients of thermal expansion). Each air-gap sleeve is densely fitted with metal fins, maximizing heat-exchange efficiency. The high-temperature zone is constructed from high-temperature-resistant stainless steel (310S), ensuring a long service life.

Application Fields

• Food industry: drying of milk powder, bread, biscuits, and other products.
• Pharmaceuticals and chemicals: drying of pharmaceuticals, synthetic resins, and other materials.
• Other fields: grain drying, wood processing, industrial heating, and more.

Strengths and Weaknesses

• Advantages: high-quality manufactured materials, wide applicability, and excellent environmental performance.
• Disadvantage: High equipment costs.

Selection Recommendations

• Select the appropriate type based on material characteristics, such as requirements for whiteness, impurities, and contamination.
• Considering fuel type (coal, natural gas, etc.) and thermal efficiency, natural-gas-fired systems are cleaner but more expensive.
• Pay close attention to the material and design of the heat exchanger to ensure long-term stable operation.