What is the role of a crystallizer?

 A crystallizer is heating equipment that transforms amorphous PET into a semi-crystalline state from virgin, post-process, or scrap PET.

Processors who produce or use considerable amounts of scrap or recycled PET material need crystallizers. Because processing converts virgin PET to amorphous PET, which cannot be reprocessed in high concentrations, those who must re-use this material has only two choices:

• Process a small percentage of amorphous PET regrind (10% or less) with virgin PET, or blend a small percentage of amorphous PET regrind (10% or less) with virgin PET before processing.
• Using a crystallizer, “re-crystallize” the amorphous PET regrind to a semi-crystalline form (similar to virgin PET).

What is the function of a crystallizer?

A crystallizer raises the temperature of granulated amorphous PET to slightly below its melting point, but above its glass transition temperature. When heated PET reaches its "crystallization" temperature, the amorphous PET molecules rapidly change state: Crystalline structures develop and align inside the molecules, and the material transitions from an amorphous to a semi-crystalline state.

When the transformation is complete, the “crystallized” PET is ready for drying (if necessary) and processing in the same way that virgin PET is. When amorphous materials are heated during drying, they tend to clump together since they haven't crystallized. Several issues arise from agglomerated materials: 1) They cause insufficient residence time for some materials by disrupting smooth mass flow through a drying hopper. 2) Agglomerated clumps are difficult to dry because of their huge size, and they are more prone to retain moisture than is desirable. 3) Agglomerated clumps can become caught or bridged in downstream processes, resulting in a slew of other material handling problems.

Depending on the capabilities of your crystallizer equipment, crystallization can be done in a continuous or batch process. Crystallizers are typically sized according to the amount of material that can be crystallized in an hour.

What are the types of crystallizers?

Majorly the crystallizers are of two types mentioned below:

1. Hot-air hopper Crystallizers
2. Infrared Drum (IRD) Crystallizers

1.      Hot-air hopper Crystallizers

The crystallizers are similar to dryers in many ways: Material is fed into a hopper, heated to a precise temperature with warmed air, and then discharged into a downstream process. A hopper-type crystallizer and a dryer, on the other hand, have numerous key functional differences:

·         Crystallizers use ambient air: In an open-loop crystallizer, heated ambient air is used, rather than dry/desiccated air in a closed-loop system (however, closed-loop systems are available). While some drying may occur as a result of the heating and crystallization process, crystallization does not provide the same level of moisture control as drying. If the recrystallized PET is still damp, it must be thoroughly dried before use.

·         Crystallizer hoppers use an agitator: Mechanical agitation is required within the hopper to keep amorphous PET material moving, break up clumps, and ensure that it flows easily before and after the crystallization process because it can become sticky as it is heated to its crystallization temperature.

2.      Infrared Drum (IRD) Crystallizers

Infrared Drum (IRD) crystallizers are distinguished from hopper-type crystallizers in a number of ways:

·         Infrared Heat Source: An infrared emitter, located in the drum's middle heats material directly as it rotates in the drum, eliminating the need to inject heated air.

·         Rotating Horizontal Drum: Instead of a vertical hopper, the IRD employs a horizontal rotating drum. Slow, continuous rotation reduces clumping, ensures complete material mixing, and removes the need for the agitator found in traditional vertical crystallizer hoppers.

·         Can Simultaneously Crystallize and Dry: The powerful infrared source heats pellets more quickly, causing moisture to rise to the top and be transported away by a steady stream of cool, ambient air. While IRD crystallizers can remove 90% or more of the moisture from a material, which is a far larger percentage than hopper-type crystallizers, they can't give the precision moisture removal that a specialized desiccant dryer can.

 

Alaqua is the best crystallizer supplier in USA along with other processing equipment such as the evaporator, solvent recovery, and other equipment to serve various industrial requirements. Alaqua supplies processing equipment such as crystallizers made in the USA worldwide for various food processing, pharmaceutical, and various chemical industries. To know more contact us today!

Solvent Recovery System and Disposal Recycling System | Alaqua Inc

The solvent recovery systems process takes effluents and extracts valuable solvents and raw materials from the waste stream of a manufacturing process. A variety of procedures or technologies can be used to recover solvents from wastewater. Solvent recycling machines perform distillation to remove dirt, debris, and oils from old cleaning solvents, allowing the cleaning solvent to be reused. Solvent recovery systems for old solvents can cut solvent purchases by more than 95% and chemical waste disposal costs by more than 90%.

Almost any solvent or chemical used in electroplating, metal finishing, paint and powder coating, parts washing, and vapour degreasing can be recycled using solvent recycling equipment.

 

How Does Solvent Recovery System Work?

Distillation separates volatile and nonvolatile solutions in a solvent, and this is how solvent recovery systems work. Similar to how a vapour degreaser works, the solution is boiled, then the vapours are condensed back into liquid in a separate tank. The temperature at which the various elements of the solvent and impurities boil differs: usually, oils and soils boil at significantly higher temperatures than solvents. Paint thinner, which is used to remove paint from paint guns and parts, is a good example of this; the solvent boils at considerably lower temperatures than paint, therefore boiling the mixture results in a condensed pure solvent in one tank and paint sludge components in another.

Simple vs. Fractional Distillation And Separation Process of Multiple Solvents

Condensing hot boiled vapours directly from the solvent recycler’s boiling tank is referred to as simple distillation. Only one volatile solvent may be recovered since the condensing takes place near to the boil “sump,” and the purity of the solvent may contain trace amounts of non-volatile contaminants conveyed by the boiling, volatile vapours. Vapour degreasers work in the same way. While the recovery of a single volatile solvent can reach 99 per cent or greater in some cases, higher recoveries are sometimes required.

 Fractional distillation is used when better purity recovery or separation of two or more volatile components (for example, water, and isopropyl alcohol) is required. To achieve greater purity solvent recovery and separation of distinct volatile solvents, fractional distillation uses a reflux column between the boiling tank and the condenser coils. This technique can achieve 99.9% solvent recovery and solvent purity above 99.9%, which is frequently required for electronic/PCB manufacturing, medical device production, and aerospace applications.

Vacuum-Assisted Distillation

Higher boiling and heavier-than-air (vapour density greater than 29 AMU – atomic mass units) solvents, such as xylenes, CFCs, and others, may necessitate the use of a vacuum on the distillation column and chamber vs. alcohol, MEK (Methyl ethyl ketone/butanone), lighter-than-air acetones, MPK (Methyl n-Propyl Ketone), etc.

Benefits of a Waste Solvent Recovery System and Recycling

• Reduce your purchasing of new solvents

• Chemical waste from solvents is reduced

• Reduce the impact on the permit status of hazardous waste generators

• Savings on storage

• When employing safer but more expensive designed solvents, you can get a quicker return on your capital equipment

• ALAQUA is a company based in the USA that supplies solutions and equipment worldwide to meet various processing demands and requirements. We supply different types of processing equipment to meet various industrial demands. Along with processing equipment, Alaqua also provides services such as fabrication of equipment, installation and commissioning services, training of personnel, retro-fitting services, field services and troubleshooting services. Contact us to know more about our services and processing equipment. For more info please  visit on Site - https://www.alaquainc.com/ 

Selecting the Evaporators Based On Processing Requirements | Alaqua Inc

Pharmaceuticals, pulp and paper, foods and drinks, polymers and resins, chemicals, inorganic salts, acids and bases, and a variety of other materials are all processed using evaporators. Evaporators technology come in a variety of shapes and sizes, and the optimal one out of them is determined by the product's qualities and intended outcomes.

Evaporation is a technique for concentrating a solution containing a nonvolatile solute and a volatile solvent, which is usually water. To create a concentrated solution, slurry, or thick, viscous liquid, a portion of the solvent is vaporised. The difference between evaporation and drying is that the residue is a liquid rather than a solid. Evaporation differs from distillation in that the vapours are not separated into their constituent parts. It's possible that the desired product is the vapour, concentrate stream, or both. As a result, the evaporator should be constructed to separate the vapours from the condensate and feed in a clean and efficient manner.

A heat exchanger or heated bath, valves, manifolds, controls, pumps, and a condenser are all components of an evaporator. Jacketed tanks, tubular heat exchangers, plate-and-frame heat exchangers and agitated thin-film evaporators are among the most commonly used designs. At least, a well-designed evaporator must:

• Be cost-effective for installation, operations, and maintenance, it must be designed to efficiently transmit heat at a high rate with a small surface area
• Separate the vapour from the liquid concentrate with ease
• Meet the requirements of the product being processed
• Produce a product that satisfies the quality requirements
• Make optimal use of steam via multiple-effect evaporation or vapour recompression where possible to save energy
• Fouling on heat transfer surfaces should be kept to a minimum
• Be made of corrosion-resistant materials

Product Characteristics and Critical Operations

The critical operational and product parameters of the solution to be evaporated play a big role in determining which evaporator type is best for the job.

• Heat Sensitivity: Many foods, pharmaceuticals, chemicals and resins are heat or temperature-sensitive, necessitating modest heating temperatures, a short time exposed to the heat, or both. This can be accomplished by reducing the product's bulk boiling temperature by operating the evaporator at lower pressures, as well as minimising the volume of product in the evaporator at any given time. Lowering the internal working pressure while maintaining an appropriate heat-exchanger driving power may also allow lower heating temperatures to be used (difference in temperature between the bulk product's boiling point and the heating medium's temperature).
• Fouling: Solids in the feed, precipitating solids in the concentrate, and product degradation are the most common causes of fouling of heat exchanger surfaces. The overall heat-exchanger coefficient will gradually decrease when a layer forms on the heat transfer surfaces over time. This will eventually necessitate the process being shut down and the heat transfer surfaces being cleaned, resulting in production downtime and more maintenance labour.
• Foaming: During the vaporisation of a product, it is normal for it to foam. It can range from a tiny amount of readily broken unstable foam to a very stable foam that tends to fill the entire void of the evaporator system. Specific designs for the feed inlet (separation of feed from vapour stream) and the vapour/liquid separation area (special disengaging design) can typically reduce foaming. Reduce the boiling intensity of the liquid on the heat transfer surface (by operating at a lower temperature or at higher pressure) and the vapour velocity in the tubes to reduce foaming. Antifoam may solve or considerably decrease the problem if the product purity criteria allow it.
• Solids: To reduce foaming, lower the boiling intensity of the liquid on the heat transfer surface (by operating at a lower temperature or higher pressure) and the vapour velocity in the tubes. If the product purity criteria allow it, antifoam may solve or significantly reduce the problem.
• Viscosity: The overall heat-exchanger coefficient decreases as the viscosity of the concentration increases.
• Distillate-to-concentrate Ratio: In general, enough liquid must move through the evaporator to wet the heated walls. Due to a lack of wall wetting and fluid velocity, particles on heat transfer surfaces may foul and salt, resulting in reduced heat transfer and possibly product quality degradation due to hot spots on the heating surface. Recycling of portion of the concentrate may be necessary for operations that need high distillate-to-concentrate ratios.
• Distillate vapor velocity (pressure drop and entrainment): In the evaporator tubes and heating jackets, the vapour velocity must be considered. To achieve adequate heat-exchanger coefficients without exceeding pressure drop, erosion, or entrainment limits, sufficient velocities are required. The vapor/liquid separator's specifications for separation efficiency and pressure drop must be carefully considered.
• Heat transfer Medium: The type of evaporator chosen could be influenced by the heat transfer medium. Evaporators that are heated by liquid have lower overall heat transfer coefficients and require a larger heat transfer surface. If the product is temperature-stable, hot oil heating can help overcome the reduced heat-exchanger coefficient. This could allow a smaller evaporator to be used in some circumstances.
• Materials required of construction: The required materials of construction may be a crucial factor to consider when choosing an evaporator. The heat-exchanger surface material is critical because it not only influences the overall material cost but also dictates the material's thermal conductivity, which influences the overall heat-exchanger coefficient and necessary surface area.

The needs, standards, and value of a marketable product must all be specified before the process and equipment can be appraised. The general process requirements needed to make a commercial product must next be determined. The method should result in a high-quality product with low waste. 

It can be simple or difficult to select the best evaporator. High viscosities or heavy solids are examples of product qualities that provide some guidance. For many simple applications, however, any or a combination of the different categories will suffice. Capacity, small batch production, previous plant expertise, available space, operator requirements, utility requirements, required maintenance, and/or cost may all play a role in making this decision.

Batch or stirred-batch evaporators are typically the most cost-effective option for low-volume or multi-product batch production. It's easy to use, low-cost, and capable of handling a wide range of products with varying features and operating conditions. Although it may take longer to clean, it is usually a low-maintenance system. Continuous processes are typically employed when a large capacity is required. When tubular evaporators are available, they should be used initially.

The best-suited type will be determined by the throughput, viscosity, solids content, fouling propensity and foaming the tendency, as well as whether the design calls for circulation. Forced-circulation evaporators are generally more expensive than natural-circulation evaporators, although, in some situations, the higher heat-exchanger coefficients allow for a smaller evaporator to be employed, lowering capital expenditures.

Technology such as the plate-and-frame or agitated thin-film evaporator may be required when the product is difficult to handle due to great temperature sensitivity, high viscosity, heavy particles, or a high tendency to foul. Alaqua is the best evaporators supplier in USA along with other processing equipment available. For more information contact us today!!!