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Following the successful commissioning of our 10 t/h lime hydration sytem in their Hanoi plant in 2021, our Vietnam client had choosed us again to upgrade their old lime hydration system installed in 2019 in their Hochiminh plant. The previous lime hydrators will be replaced with our hydrators, other parts of the line will remain unchanged for now. The new hydrators will allow more flexibility to their production, improve the current capacity and product quality.   

The non-hydratable substance in the form of grits(usually less than 5-8mm) from the quicklime usually may take up 5% to 10% of the total mass depending the quality of quicklime, which needs to be removed from the hydrated lime via an air classifier in order to improve quality. The output fineness from the classifier can be adjusted to meet different market demands via VFD classifier rotor and blower fan. Increasing the rotating speed of classifier rotor and/or reduce the flowrate of blower fan will increase the output fineness of hydrated lime powder and vise versa. Our lime classifier can achieve output fineness range from D97: 200 mesh to 600 mesh.  

Lime Hydrator is a U-shaped chamber installed with mixing shaft(s) and blades, it is designed for the reaction between quicklime(CaO) and water to produce hydrated lime powder -Ca(OH)2. To achieve maximum hydration reaction and minimum residue moisture in the hydrated lime powder, quicklime and water feeding rate have to be controlled very precisely via high accuracy lime weighing feeder, water flowmeter and flow control valves. furthermore, water injection and the shape &angle of lime mixing paddles have to be optimized for a fully and uniform blending between water and lime.  Depending on the capacity and quality requirement of hydrated lime, a lime hydration system may consist of two, three, four or five hydrators that are connected together to form a multi-hydrator system. To control hydration process, temperatrue sensors are also installed on each of the hydrators to monitor the reaction temperature. if the temperature is lower than the standard, it could mean too much water or too little quicklime input. if temperature runs too high, it would mean too little water or too much quicklime input. the feeding rate of quicklime or water needs to adjusted immediately to keep the temperature at a stable value.

The reactivity of lime refers to how quickly it reacts with water Specifically, it can also be said that within 10 minutes under standard atmospheric pressure, the number of milliliters of 4N HCI solution consumed by 50 grams of lime in water at a constant temperature of 40 degrees Celsius is defined as the reactivity value of lime The reactivity of lime depends on its structure, and the structure of lime is closely related to the burning temperature and burning time. The structures that affect lime reactivity include bulk density, porosity, specific surface area, and crystal grain size of CaO minerals. The smaller the crystal grains, the larger the specific surface area, and the higher the porosity, the higher the lime reactivity and the stronger the chemical reaction ability. At present, the average value of lime reactivity can generally exceed 300 ml/4N-HCI. The reactivity value of quicklime has major effects on the lime hydration process and final quality of hyated lime. The difference between active lime and ordinary lime is that it has a large internal specific surface area and a stable bulk density. The internal specific surface area is large, mainly because the crystal grains of CaO are small,...

There are many variables that could affect the lime hydration process, below are the major factors.  Hydration temperature: The temperature of water and quicklime will affect the hydration reaction speed. Generally, the hydration speed increases with the increase of the reaction temperature. The relationship is as follows: K(T) =K(0)×1.035T K(T): the reaction speed when the temperature is T; K(0): the reaction speed when the temperature is T0; T: T－T0  Chemical composition of quicklime High-purity quicklime accelerates the hydration reaction. The higher the purity of the quicklime, the lower the possibility that the pores of the quicklime will be blocked, and the chance that the surface of the quicklime will be coated with impurities (such as quartz, alumina, iron powder, etc.) that are dissolved during calcination will also reduce the chance that these impurities will hinder the contact between water and the quicklime . In addition, the high magnesium oxide content present in the quicklime powder will also have a negative impact on the reaction, because the higher magnesium content tends to cause over-burning of the lime.  Activity of quicklime The activity of quicklime depends on the size of the quicklime and magnesium oxide crystal particles, the specific...

Lime Hydrator is a mixing reactor where quicklime and water are mixed in a designed rate to fully react and produce hydrated lime powder. When the hydration system is started, the transmission mechanism drives the stirring mechanism to stir, and the calcium oxide enters the first hydrator’s chamber through the belt weighing feeder. The PLC control system controls the water spray device to start spraying water. The material and water are pushed to the chamber of the second hydrator by special-angled blades on the shaft while being fully mixed. The second-stage mixing shaft is also equipped with special-angled blades, which push the materials to the third-stage hydrator chamber while fully stirring. The three-stage mixing shaft is also equipped with special-angled blades, which separates the over-burned lime particles in the material from the outer layer of calcium hydroxide while discharging the hydrated product. The temperature measuring element on the hydrator body transmits the temperature of the material in the hydrator chamber to the PLC control system for monitoring in real time, and adjusts the water supply in time. The steam along with some hydrated lime particles generated by the material reaction is filtered by the pulse bag filter, lime particles are...