The production of ceramic wall and floor tiles is a relatively complex process. Its main production processes include material ball milling, powder preparation, pressing and forming, kiln drying, glazing and printing, firing and polishing, etc.
Among them, the spray drying powder-making process is an important link in ceramic production, and the spray drying tower is an indispensable production equipment for powder preparation.
Working Principle
Its working principle is that the hot air furnace provides high-temperature hot air to the tower body through the hot air pipe. The mud with a moisture content of 33%-40% processed by the ball milling process is pumped to the atomizer by the mud pump, and sprayed from bottom to top through the atomizer nozzle to form atomized mud droplets with a small diameter, so that the mud droplets are fully contacted with the high-temperature hot air for dehydration and drying. Spherical powder particles suitable for subsequent pressing and forming are obtained, and gathered at the bottom of the tower under gravity for unloading and storage.
Powder Agglomerate Problem
However, during the production process, the powder obtained after high-temperature drying is often at a high temperature. As the heat of the powder dissipates, it will condense into water mist on the powder conveyor belt when it encounters water molecules in the air. When the powder is unloaded on the powder conveyor belt, it easily gets stained with water mist, which causes the powder to regain moisture and agglomerate during transportation, which is not conducive to the subsequent screening and storage of the powder.
Traditional Method: Adding Cooling Equipment
In order to reduce the powder outlet temperature of the spray drying tower, the powder can be cooled by adding cooling equipment, but this method not only increases equipment investment and production links, but also increases energy consumption, which is not conducive to the control of production costs.
At present, the traditional spray drying tower is to set a fixed size of air distribution port on the discharger. Since the air pressure in the tower is negative pressure, the circular air distribution holes and rectangular air distribution holes arranged circumferentially on the discharger are opened, and the external gas enters the tower body from the hole, flows downward along the inner wall of the cone at the bottom of the tower body, and passes through the discharger to the powder in the lower hopper below for heat exchange, achieving the effect of cooling.
However, the air holes of the traditional spray drying tower discharger are generally of fixed size. When the temperature is high, the temperature of the powder out of the tower is high. Because the powder temperature is too high, it is easy to generate a large amount of water vapor during the slow cooling process after it is sent to the silo by the conveyor belt. The water vapor condenses on the silo wall and flows back, causing a large amount of powder to clump, resulting in the unsmooth discharge of the silo and blocking the discharge channel of the electronic scale; at the same time, the agglomerated powder has too high water content, which is not conducive to the subsequent screening and storage of the powder, resulting in reduced batching accuracy and affecting the quality of powder pressing.
Improvement Plan
In order to solve the problem of rehumidification and agglomeration of powder during transportation and storage due to temperature changes, the discharge device of the traditional spray drying tower is designed and optimized, and a ceramic spray drying tower discharge device with high powder cooling efficiency and the controllable cooling effect is designed, which is easy to operate and saves preparation costs.
The designed discharging device of the ceramic spray drying tower comprises a cylinder assembly of the lower cone of the spray drying tower, an air distribution adjustment plate, an air distribution assembly at a discharging port and a discharger, wherein the cylinder assembly comprises a connecting ring, a cylinder connected with the connecting ring and a guide plate, an air distribution port for discharging the cold air of the discharging device is arranged on the circumferential wall of the cylinder, a bolt hole for adjusting and fixing the bolts is arranged below the air distribution port, and a guide plate for preventing the powder from sticking to the wall is welded at 45 degrees on the surface of the inner wall of the cylinder.
The air distribution assembly at the discharging port comprises a trumpet-shaped sandwich cone and an air distributor connected through the inner wall of the cone, the air distributor comprises a conical outer plate in the shape of a bamboo hat, a conical inner plate in the shape of a bamboo hat which is mounted on the inner wall of the conical outer plate and forms a partition, a plurality of air ducts which are connected through the conical inner plate in the shape of an umbrella and are distributed, and an air distribution cover plate which is connected to the port of the air duct through a connecting ring and a lifting eye screw.
The amount of cold air inlet is adjusted by adjusting the opening and closing angle of the air distribution cover. At the same time, the external cold air can pass through the inner plate of the bamboo hat-shaped inner plate along the air guide pipe to the inner surface of the inner wall of the bamboo hat-shaped outer plate; in order to extend the service life of the equipment, wear-resistant ceramic tiles are also laid on the inner plate wall of the sandwich cone where the powder flows and falls; the discharger is composed of a connecting plate with a through hole and a discharge hopper welded on the connecting plate. The upper part of the discharge hopper is connected to the air distribution assembly of the discharge port through the connecting plate.
The discharge device is arranged below the spray drying tower. The powder particles formed by physical and chemical drying in the inner cavity of the spray drying tower fall into the discharge device at the bottom of the tower under the action of gravity. The flow is diverted by the bamboo hat-shaped cone outer plate of the air distributor of the discharge device, so that the scattered powder falls on the guide plate in an umbrella shape, falls on the sandwich cone, and then falls into the discharger for discharge.
By controlling the air distributor, loosening the eyebolt, adjusting the opening and closing angle of the air distribution cover, tightening the eyebolt, and then adjusting the air distribution adjustment port of the cylinder assembly, first loosen the bolt, move the air distribution adjustment plate up or down along the adjustment slot to a suitable position, and then tighten the eyebolt to control the air intake. After the cold air enters the discharge device, it continuously takes away the heat along the direction of the centrifugal fan duct, quickly cools the powder, and greatly improves the cooling efficiency of the powder.
Summary
By setting an air distributor inside the discharge device, the powder is divided into an umbrella shape and scattered on the guide plate through the large conical cover on the air distributor, increasing the contact area between the powder and the cold air; at the same time, the opening and closing angle of the air distribution cover is adjusted according to production needs to adjust the cold air intake, with high cooling efficiency and controllable cooling effect, which improves the preparation efficiency of the powder.
The application of the newly designed ceramic spray drying tower discharge device keeps the powder discharge temperature at 29°~39° all year round, improving the large difference in powder discharge temperature in summer and winter, powder sticking to the wall, and agglomeration, and improving production continuity.
By laying a layer of porcelain wear-resistant ceramic tiles on the inner side of the conical bucket where the powder particles flow through and fall, the service life of the equipment is extended and the equipment maintenance cost is saved.
