loda prive denis    

Main Advantages of the Microwave Heating

  • Speeding up: minutes instead of hours!!
  • Volume Energy transmission - cold vessel
  • ENERGY Savings, Room Savings
  • Efficiency 70%
  • Automatization
  • Safety *
  • Environment *

Comparing to the processes using the combustion


REFERENCES

ECONOMY 
  • production speed – hours instead of shifts
  • continuity of production
  • minimum space
  • elimination of scrap
  • minimal heat loss  

DOZENS OF MICROWAVE ROmiLL DRYERS
have been successfully used in ceramic ware plants long term

Drying of sinks and simple-shaped sanitary ceramics


For sinks, urinals, toilet bowls, etc.
From moulding to firing
 

 
THREE DIFFERENT OPTIONS AND METHODS OF USE:
 
1. MICROWAVE PREHEATING SPEEDS UP HOT-AIR DRYING, WHICH SHORTENS THE ENTIRE DAY TO A SINGLE SHIFT
Unlike ceramic material, water absorbs microwave energy and is heated up simultaneously at each depth of the product. Heating up the entire thickness of the wall opens up pores through which fluids move by capillary forces. With increasing temperature, pressure increases at the same time, forcing water molecules out into areas of low pressure, which can be found on the surface. Opening up pores accelerates the diffusion of water from within the wall for subsequent main hot-air, generally tunnel-style, drying. The microwave power can be very precisely controlled, so that the rapid pre-heating of material, which is sensitive to the formation of microcracks in this initial phase of drying, is safe, because it is sufficiently gentle.
 
Dozens of microwave pre-dryers for 4 to 8 sinks, toilet bowls, etc. in one batch have been set up in various plants for manufacturing sanitary ware. An example is the reduction of the original 24 hours in a hot-air tunnel to just 8 hours.


 
2. SHAPE STABILIZATION OF MICROWAVE PRE-DRYING
The product that comes out of a fresh ceramic cast is prone to shape deterioration. Due to the need of immediate processing, it is desirable, after taking it out of the mould, to reduce its excessive plasticity by removing part of the moisture. The time of pre-drying using microwaves, lasting approximately 15 minutes, matches the cycle for casting the sinks. In various operations, the time varies depending on the raw material of the product, the shape, size, method of casting, handling, and the initial and target moisture. Microwave pre-drying shortens the commonly used idle period of a fresh casting after it is removed from the mould. Drying it in an available space, moreover, occupies extra space that can be used more effectively for production. Putting it into sealed, temperature-controlled, ventilated rooms with controlled air circulation, temperature and humidity creates an interim storage. Because this requires filling and releasing the stock in batches, it interrupts the smooth flow of castings from the casting press to the dryer tunnel. Idle production time is extended and reduces productivity. Intermediate storage space could be used more efficiently or does not have to be built at all. Losses occur from heating it because only part of the energy used for heating the air is used to reduce the moisture in the casting.
 
Through immediate pre-drying, microwaves stabilize sinks for handling, for retouching, etc., in just minutes.


3. DRYING TO HUMIDITY APPROPRIATE FOR FIRING
The advantages of microwave drying are related to the physical differences of the dielectric heating principle. The energy delivered is absorbed directly by water at each point in the body. It does not heat up through air, solid phase and the surface. Shrinkage in the thickness of the wall is uniform, so no deformation occurs because of stress between the hot surface and the cold interior. The warming of the wall allows the faster diffusion of liquid through pores. No overpressure or steam causing destruction occurs inside. No impervious surface crust preventing evaporation is formed. The equipment does not consume standby power – it simply turns off when idle. It is then immediately ready for use, because it does not require preheating.
For each type of product, there is an optimal combination of temperature, humidity, flow and the speed of passage. The optimal tuning of these parameters for the various stages (pre-drying, critical point, firing humidity) is impossible in continuous hot-air tunnels. In microwaves, only the radiated power is controlled – its values, delays and selection of sources in different positions. This sensitively sets the limits that can withstand the various stages of drying. The modes vary depending on whether the pores are opened by preheating or the intermolecular water is evaporated or if even the capillary water needs to be removed.
 
In addition to shortening the usual drying period by several times, just 1 kWh of microwave power is needed to evaporate 1 liter of water.

PRACTICE 
When preheating either to stabilize after casting or to speed up the subsequent hot-air drying, the retention of sinks and similar products in microwave chamber lasts about 15 minutes. Typical capacities correspond to processing a batch of 4 – 8 units according to their size. The largest previously required equipment pre-dried 12 sinks. For drying fresh castings to firing-enabling values, equipment allowing 36 or 146 sinks, is the current concept. In the shorter version, a batch of 9 fresh units is loaded every 40 minutes while 9 dried units simultaneously leave, ready for firing. It is similar for the longer alternative, but the batch contains 36 units. The total drying time to firing for both capacities is 4 × 40 minutes, which corresponds to up to 3 hours with drying and handling. The semi-continuous concept on the one hand corresponds to batch processing and on the other ensures that the placement and removal along conveyor lines is connected to the continuous flow of products in the plant.

INVESTMENT
Compared to the inefficient hot-air technologies, which are lengthy and consume 1/3 of the total energy needed to manufacture the product, the cost of microwaves is unbeatable. The design and components used allow for a long life in continuous, trouble-free operation. 

OPERATION
The control system allows programming modes according to the technologist’s requirements, it monitors flawless operation, reports deviations and stores records. Even staff without qualifications can operate it.

SERVICE
The equipment requires no special intervention. Consumables are easily replaced by a technician. The manufacturer also offers post-warranty service that guarantees preventive maintenance, repairs, their deadlines and prices.