A detailed explanation of the medical negative pressure bottom spraying fluidized bed coating machine

Abstract: starting from the concept of fluidized bed coating technology, this paper makes a comment on the negative pressure bottom spraying fluidized bed coating machine of our company, in order to make the users of pharmaceutical factories have a more systematic understanding of the bottom spraying fluidized bed coating machine Introduction: One of the world's drug development trends is slow controlled release and other drugs Due to the immature technology and equipment in the past few years, slow controlled release and other drugs have developed slowly However, in recent years, through the research and development of micro pill (particle) coating technology and equipment, a variety of micro pill (particle) coating equipment has emerged, which also promotes the continuous development of slow controlled release and other drugs in China, including bottom spray fluidization Bed coating machine is one of the successful equipment Objective: this kind of equipment can make a greater contribution to the development and production of slow and controlled release drugs in China, and at the same time, it can make the users of pharmaceutical factories have a more systematic understanding of the bottom spray fluidized bed coating machine 1 In the fluidized bed coating technology, the "bottom spray" fluidized bed coating is that during the fluidization process, all particles are suspended in the fluidizing airflow, the surface is completely exposed, and various coating liquids can be sprayed, and the heat and moisture exchange can be carried out Among them, the fluidization state is determined by the characteristics of the material being fluidizing and the structure of the equipment Because of the different fluidization states of each technology, the fluidization state is also different, and there are three kinds of spray technology for coating, namely, three forms: Top spray, bottom spray and side spray In order to make the film uniform and continuous, minimize the droplet stroke (i.e the distance from the droplet exit to the particle surface), so as to reduce the spray drying effect of hot air on droplets, so that droplets can keep their original properties on the surface of the coated particles, so as to achieve uniformity, ideal spreading and film continuity A comparison is made between top spray, bottom spray and side spray fluidized beds (1) in the top spouted fluidized bed, the material tank is usually conical, the spray gun is at the high position of Zui, and the fluidizing air flows into the material tank through the bottom screen With the increase of air flow, the original static material is driven by the air flow and fluidizes, and its particles are driven by the air flow to accelerate the movement from the material tank and pass through the nozzle, and the coating liquid from the nozzle is attached to the irregular moving particle surface, its direction and particle movement direction To the contrary 　　 (2) a atomizer is arranged in the center of the distribution plate of the bottom jet fluidized bed, and a circular guide cylinder is arranged in the center of the material bed with the expansion chamber The distribution plate has a large opening rate in the guide cylinder area, so as to meet the passing of most of the air volume, forming a fountain like fluidization The powder particles rise from the guide cylinder accelerated by the air flow, and then leave the guide cylinder to enter the expansion chamber, and then the air speed drops sharply The drop makes the material fall into the annulus area between the bed body and the guide cylinder, so that the material has a high degree of dispersion (3) the side jet fluidized bed material tank is cylindrical, with a variable speed rotary table at the bottom, which can move up and down to adjust the air intake The coating liquid can reach the atomizing nozzle on the wall of the material tank and spray into the material tank The spray direction of the nozzle is the same as that of the particle fluidization, and the coating liquid can be tangential sprayed into the material tank The movement of particles in the trough is spiral, uniform and orderly, and three forces are synthesized For top spray, bottom spray and side spray, these three kinds of spray methods have their own characteristics in fluidized bed coating Compared with table 1, it can be seen that Zui is suitable for pellet (pellet) coating Comparison of characteristics of liquefying bed with top spray, bottom spray and side spray Random high speed large granulating bottom spray medium high regular low medium coating side spray small low regular Low low granulation and coated bottom blown fluidized bed coating was founded in 1959 by Dr DaleWurster of Wisconsin State University Spouting fluidization and spray were combined to form a fountain state to make industrial coating practical The wide application of the technology has not been compared with other forms Its characteristics are: (1) the same direction of spray makes the spray direction consistent with the particle movement direction, showing the characteristics of fast, continuous and uniform; (2) the coating liquid is sprayed on the particle surface which moves orderly near the nozzle, so the distance from the droplet to the coated particle surface is very short, which is easy to form a continuous and tight coating film, and the coating film quality is good (3) it has a wide range of applications and can meet the requirements of medium-sized batch production 3 Basic principle of medical negative pressure bottom spraying fluidized bed coating machine During operation, the materials shall be put into the fluidized bed chamber according to the feeding amount of not less than 80% of the specification, the cylinders shall be pressurized to seal, the induced draft fan and heating system shall be started, the heated air purified by the air filter shall enter the fluidized bed chamber, the coating material liquid shall be delivered to the spray gun through the peristaltic pump, atomized by the compressed air, uniformly contacted with the fluidized materials, and attached to the membrane bag Clothes The special design of the opening rate of the distribution plate of the fluidized bed, most of the air flow passes through the center of the fluidized bed (i.e the guide cylinder), thus forming the material air flow conveying, the materials gather in the guide cylinder area and rise up, forming the fountain like material fluidization Such repeated circulation flow, atomization and material close contact, make full use of the wettability of atomization, improve the coating film-forming rate, through throwing, dropping, extrusion and other materials rotation and circulation circulation circulation regular flow, to achieve the coating adhesion firm, uniform continuous and high sphericity process requirements At the same time, the hot air exchanges with the coating liquid, and the moisture is vaporized and evaporated The induced draft fan draws out the hot and humid air, and the dust material entrained in the hot and humid air is collected by the filter bag In addition, close the induced draft valve and open the hot air valve in an instant through the pressure difference transformation device, carry out the hot air back blowing and soot cleaning, the dust materials accumulated on the filter surface fall into the fluidized bed for re coating, during which the hot and humid air is discharged from the outside of the machine Through simulation observation, when the coating and film forming meet the process requirements, the elevator will discharge the material and enter a new process.