The working principle of spray dryer is based on the rapid evaporation of droplets

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Changzhou Luyang Pharmaceutical Drying Equipment Co., Ltd

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Date: 2025-05-21Read: 10

1、 Working principle of spray dryer

The working principle of spray dryer is based on the rapid evaporation of droplets. Firstly, the liquid material that needs to be dried is sent to the atomizer through the conveying system. The atomizer disperses the liquid into countless tiny droplets, greatly increasing the surface area of the liquid. Generally, the droplet diameter is between 10-60 microns, which creates favorable conditions for subsequent rapid drying. After entering the drying tower, these droplets come into full contact with the hot air, which transfers heat to the droplets. Due to the large surface area of fog droplets, water evaporates and vaporizes rapidly. In a very short period of time (usually only 5-30 seconds), the water in the fog droplets evaporates completely, eventually forming dry solid particles that are collected by a collection device.

2、 Structure and composition of spray dryer

The spray dryer is mainly composed of five parts: feeding system, atomization system, drying system, gas-solid separation system and control system.

feeding systemResponsible for stably delivering liquid materials to atomizers, common feeding equipment includes centrifugal pumps, screw pumps, metering pumps, etc. Different material characteristics require the selection of appropriate feeding equipment to ensure the uniformity and stability of material transportation.

Atomization system: is the core component of spray dryer, and its performance directly affects the drying effect. Common atomization methods include pressure atomization, centrifugal atomization, and airflow atomization. Pressure atomization uses a high-pressure pump to pressurize the material and spray it out of the nozzle to form droplets; Centrifugal atomization utilizes a high-speed rotating centrifugal disk to eject and atomize materials; Airflow atomization is the process of mixing compressed air and material at the nozzle, and atomizing the material through high-speed airflow.

drying systemMainly composed of a drying tower and a hot air distributor. The drying tower provides space for heat exchange between droplets and hot air, and its shape and size are designed according to production requirements. The function of the hot air distributor is to evenly distribute the hot air inside the drying tower, ensuring that the droplets are in full contact with the hot air and improving the drying efficiency.

Gas-solid separation systemUsed to separate dried solid particles from hot air, common gas-solid separation equipment includes cyclone separators, bag filters, and wet dust collectors. According to product requirements and environmental standards, different gas-solid separation methods or a combination of multiple methods can be selected for use.

control system: Monitor and adjust the whole spray drying process, including the control of temperature, pressure, flow, speed and other parameters, to ensure the stable operation of the drying process and the consistency of product quality.

3、 Technical advantages of spray dryer

Fast drying speedDue to the large surface area of fog droplets and their sufficient contact with hot air, water evaporates rapidly and the drying process can be completed in a short period of time, greatly improving production efficiency.

The product quality is good.The drying process is carried out at a lower temperature, which can effectively retain the thermosensitive components in the material, such as nutrients in food and active substances in pharmaceutical products. At the same time, the dried product has uniform particle size and good flowability, making it easy for subsequent processing and use.

Continuous production: The spray dryer can realize continuous feeding, continuous drying and continuous discharging, which is suitable for large-scale industrial production, reduces manual operation, reduces labor intensity, and improves the stability and reliability of production.

Flexible operationBy adjusting the parameters of the atomizer, the temperature and flow rate of the hot air, etc., the particle size, moisture content, and bulk density of the product can be easily controlled to meet the production needs of different products.

Wide adaptability rangeIt can handle various forms of materials such as solutions, emulsions, suspensions, etc. Whether they are low viscosity or high viscosity materials, they can be dried through appropriate processing methods.

4、 Application scenario of spray dryer

food industryIn the food industry, spray dryers are widely used in the production of milk powder, coffee powder, juice powder, instant tea powder and other products. For example, during the production of milk powder, the spray drying technology can quickly dry the milk into milk powder to maximize the retention of nutrients and flavor substances in the milk. Meanwhile, the dried milk powder has good solubility and flowability, making it easy to store and transport.

pharmaceutical industryUsed for drying antibiotics, vitamins, enzyme preparations, and other drugs. The quality requirements of pharmaceutical products are jigao. The spray dryer can quickly dry at low temperature, effectively protect the active ingredients of drugs, and ensure that the product quality meets the pharmacopoeia standards. In addition, by controlling the drying conditions, drug particles with different particle sizes and shapes can be prepared to meet the production needs of different dosage forms.

chemical industryIn the chemical industry, spray dryers are often used in the production of dyes, pigments, detergents, catalysts and other products. For example, in the production of dyes, the spray drying technology can dry the dye solution into powder products for easy packaging and use. Meanwhile, by adjusting the drying parameters, the particle size and color of the dye particles can be controlled, improving the quality and performance of the product.

environmental protection industryCan be used to treat industrial wastewater and sludge. Drying wastewater or sludge after atomization can not only reduce its volume for subsequent treatment and disposal, but also recover useful substances and achieve resource reuse. For example, when treating electroplating wastewater, heavy metal ions in the wastewater can be concentrated in the dried solid particles through the spray drying technology for further recovery and treatment.

5、 Future development trend of spray dryer

Intelligence and automationWith the continuous development of industrial automation and intelligent technology, the future spray dryer will be equipped with more advanced control systems and sensors to achieve real-time monitoring and intelligent adjustment of the drying process. Through artificial intelligence algorithms and big data analysis, it is possible to automatically optimize drying parameters, improve production efficiency and product quality, and reduce energy consumption and production costs.

Energy-saving and environmental protectionIn the context of the global energy crisis and increasingly stringent environmental requirements, energy conservation and environmental protection will become an important direction of the development of spray dryer. The future spray dryer will adopt more efficient heat exchange technology, waste heat recovery technology and energy-saving equipment to reduce energy consumption. At the same time, developing more environmentally friendly drying processes and equipment, reducing the discharge of waste gas, wastewater, and waste residue, and achieving clean production.

Refinement and multifunctionalityIn order to meet the higher requirements of different industries and customers for product quality and performance, spray dryers will develop towards refinement and multi-function. By improving atomization technology and drying process, products with finer particle size, narrower distribution, and more regular morphology can be prepared. At the same time, develop spray drying equipment with multiple functions, such as drying granulation integration, drying reaction integration, and expand the application field of spray drying technology.

Nano scale drying technologyWith the widespread application of nanomaterials in various fields, higher requirements have been put forward for the drying technology of nanoscale particles. In the future, spray dryers will make greater breakthroughs in the field of drying nanomaterials, develop special equipment and processes suitable for drying nanomaterials, and provide technical support for the preparation and application of nanomaterials.

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