[Haichuan Illustrated Chemical Equipment] Precision Chemical Drying Equipment – Spray Drying Equipment

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Get to know equipment, understand it, and make good use of it. [Haichuan’s Illustrated Guide to Chemical Equipment] series posts: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=5719196. Everyone is welcome to participate in the discussions. ----------------------------------------------------------- Spray drying equipment: Spray drying technology involves turning liquid raw materials into micron-sized droplets, and enabling rapid heat and mass transfer within hot air; it is an ideal process for producing powdered or granular solid products. Suitable for liquid raw materials such as solutions, emulsions, and suspensions. Core principle: The liquid material is dispersed by an atomizer into tiny droplets of 10–200 μm in size. Upon contact with hot air, the moisture evaporates rapidly within a very short time (several seconds to dozens of seconds), resulting in direct drying into powder. Based on the atomization method, there are three main types: 1. Rotary (centrifugal) atomization spray dryer – Structure and principle: A high-speed rotating centrifugal atomization disk is used to throw the liquid material out, forming fine mist droplets which then come into contact with hot air for drying. Improving atomization precision is the core of the technology, with the deviation in droplet size distribution being able to be kept within ±5%. Applicable scenarios: It features high single-unit production capacity, with a spraying volume of up to 200 tons per hour; the feed rate is easy to control, offering great operational flexibility, and it is widely used. It is particularly suitable for high-volume continuous production in the pharmaceutical and food industries. The cleanliness of the hot air can reach 300,000 grade, making it suitable for processes with high hygiene requirements. Advantages and disadvantages: High production capacity, good product quality. The disadvantages are that the equipment is complex, it requires a large amount of space, the initial investment is high, and its energy consumption is high. 2. Structure and principle of pressure-type atomization spray dryers: The liquid material is forced into the nozzle by a high-pressure pump (with a pressure of 10–30 MPa); atomization is achieved through the friction between the liquid material and the interior of the nozzle, or through special structures such as swirl vanes. The product is in the form of a hollow sphere and has good fluidity. Pros and cons: Can produce coarse particles; easy to maintain ； It has a simple structure, low cost, and low energy consumption. The downside is that the nozzle orifice is very small and prone to clogging; therefore, the liquid material must be strictly filtered ； Nozzle holes are prone to wear and need to be made of wear-resistant materials such as tungsten carbide. Viscosity fluctuations have a significant impact on the atomization effect. 3. Structure and principle of the air-flow type atomizing spray dryer: The interaction between high-speed air flow and the liquid material is utilized to break the liquid into mist droplets. Applicable scenarios: It is mainly used in laboratories and pilot plants to atomize liquid materials that cannot be processed by the first two types of atomizers, such as high-viscosity pastes, creams, and filter cake materials. Advantages and disadvantages: It has strong adaptability and can handle highly viscous materials. The downside is high power consumption and elevated operating costs. Vacuum spray dryer: It combines spray drying with vacuum technology; a vacuum pump creates a vacuum condition in the drying chamber, thereby reducing the boiling point of the material. The material vaporizes and its moisture evaporates at low temperatures, resulting in dried powder – this method is particularly suitable for heat-sensitive materials.