Crystallizers: Specification, Design, and Methods

 A crystallizer is processing equipment used to transform wastewater into solid crystals and pure water. Solid crystals are created from a liquid solution through crystallization, also known as a solid-liquid separation process. Liquid waste may be eliminated by crystallizers, resulting in Zero Liquid Discharge (ZLD). Primary nucleation and secondary nucleation are the two steps in the crystallization process. New crystals development is called primary nucleation. Secondary nucleation is the major stage that leads to the bulk formation of crystals and is what keeps growth going.

Specifications of Crystallizers

The selection of crystallizers necessitates an examination of the application requirements. A salt crystallizer, for example, treats wastewater to generate both solid salt crystals and clean water. A resin crystallizer allows flake or amorphous resin pellets to crystallize. To crystallize very viscous and slowly crystallizing fill masses, a vertical continuous cooling crystallizer (VCCC) is utilized. Other crystallizers tailored to specific applications are also available.

 

Crystallizers made in USA can be used alone or in conjunction with other technologies like a brine concentrator or an evaporator. Steam-driven evaporators evaporate water from a solution or slurry, but the output is still liquid rather than a crystal. A product is concentrated during evaporation by boiling the solvent, which is usually water. A brine concentrator is a type of evaporator majorly used to alter waste-saturated industrial effluent into distilled water that may be reused. A typical brine concentrator can reuse 95 to 99 percent of wastewater. When a plant's initial steam host fails, evaporators and crystallizers are frequently used to replace it.

There are four types of crystallizers equipment:

·         Crystallizers for bulk solutions. While nucleation and growth take place, crystals are suspended in solution for an extended period of time.

·         Vessels for accumulating precipitation. When feed streams enter the vessel, they quickly reach high degrees of supersaturation (due to chemical reactions, drowning, or salting-out), generating enormous quantities of tiny crystals.

·         Multiple crystals are formed when crystallizers are melted. The majority of the solution or melt (usually > 90%) crystallizes in suspension or on a cooled surface. The little quantity of uncrystallized mother liquor retains impurities.

·         Melt crystallizers produce massive single crystals of great purity. Large, pure, defect-free crystals develop slowly from high-purity melts. These are commonly utilized in the production of semiconductors.

All of these equipment has the following features in common:

·         Supersaturation is created in this area to drive crystallization.

·         For crystal growth, a zone is when crystals come into contact with the supersaturated solution. In certain conditions, crystals are suspended throughout the vessel by agitation; while in others, crystals occupy only a portion of the vessel, generally as a fluidized bed.

Selection/Design

The feed material available, the system parameters, and the customer's product needs will all influence which crystallizer is best for a given assignment. The following are examples of common design sequences:

·         Data collecting at its most basic level

·         Methods for generating supersaturation should be chosen carefully.

·         Batch or continuous operations are available.

·         Selection of a certain piece of equipment.

·         Tests on a bench and on a small scale.

·         Full-fledged design.

Supersaturation Generation

Supersaturation can be achieved in five ways:

·         Cooling can be accomplished by utilizing the vessel walls, internal coils, or by flowing mother liquid via an external heat exchanger. When the feed stream's solubility varies greatly with temperature and the feed stream is approaching saturation at a high temperature, this method is applied.

·         Evaporation, which is accomplished by heating the mother liquid or lowering the pressure in the vessel to create a boiling zone at the top. This may be utilized for a variety of systems, albeit it consumes more energy than cooling.

·         Reaction in which input streams enter and mix, resulting in a chemical reaction that produces the product, frequently at high supersaturation levels.

·         Drowning out occurs when a miscible solvent is introduced to a combination, resulting in a less soluble product. This is related to reaction crystallization.

·         Salting out is the process of removing a product from the solution by adding salt with a common ion. This has a lot in common with reaction crystallization.

Role of Crystallizers in Industrial Development & Manufacturing

Process robustness regulates process productivity and profitability. Crystallization is one of the most extensively utilized processes in the chemical industry. Crystallization is extensively used in the food and pharmaceutical industries for improved purification, separation, and solid form selection. For the creation of Active Pharmaceutical Ingredients (APIs), crystallization is the most prevalent method of forming pharmaceutical solids. The physical form influences the quality and efficiency of pharmacological products, thus optimizing particulate qualities such as particle size and shape distributions is critical.

Many pharmaceutical medicines have poor physiochemical characteristics, such as low biological fluid solubility. To facilitate the production of Active Pharmaceutical Ingredients (APIs), significant research and development efforts have been undertaken to establish a solid form landscape that encompasses all potential solid structures, including solvates, polymorphs, salts, co-crystals, and the amorphous phase.

Crystallization Methods

In chemical engineering terms, crystallization is the earliest "unit operation." Sodium chloride, for example, has been created in this manner since the dawn of civilization.

There are several conventional crystallization processes, each with its own set of advantages and disadvantages. The procedure used must be based on the qualities of the crystallizing substance.

·         Solvent Evaporation: Solvent evaporation is simple to set up, needs air-tight samples, and only a small amount of solvent to operate efficiently. A particular amount of material is required.

·         Slow cooling: It necessitates solvents with low boiling points and modest solute solubility. A particular amount of material is required.

·         Solvent/Vapour Diffusion: It works well with modest quantities of material, although it can be difficult to locate two acceptable solvents. It is possible to "oil out."

·         Sublimation: It isn't the best way to make diffraction-quality crystals. Usually done at high temperatures, which causes crystals to develop too fast.

Sonocrystallization

Although crystallization processes can be difficult to manage, sonocrystallization is a more recent type of crystallization that has several advantages over previous approaches. The development, growth, and collapse of bubbles are known to cause acoustic cavitation in liquids. The collapse of the bubble gives enough energy to speed up the nucleation process. This produces crystallizations that are very reproducible and predictable, as well as a number of other advantages.

·         Induction times are shorter.

·         Metastable zone width (MSZW) decrease.

·         Nucleation rate has sped up.

·         Crystal growth speed has increased.

·         Agglomeration should be minimized as much as possible.

·         Crystal size distribution that is tailored to the individual

Crystallizers can be used to recover salts from wastewater, which can subsequently be utilized or sold. A crystallizer increases waste stream utilization and assists facilities in meeting zero liquid discharge (ZLD) standards in this way. Crystallizers supplier in USA supply it to be utilized by a variety of industries, including manufacturing, chemical processing, mining, petrochemical refining, and electric component manufacture.

 

Alaqua is processing equipment such as the evaporator, solvent recovery, distillation, spray dryer, heat exchanger, and crystallizer supplier in USA that fulfills various industrial requirements. We also provide troubleshooting, personnel training, installation and commissioning, retrofitting, and other services for processing equipment. Connect with us to know more!