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Editorial - Winning Homogenization Strategies

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Download Winning Homogenization Strategies Editorial by SPX FLOW, Inc.

January 2017


Winning Homogenization Strategies


Homogenizers are widely used across many industries including food & beverage, pharmaceutical, biotechnology and chemical. The processes they operate in have a huge variety of conditions and may require consideration for sterile conditions, abrasive fluids, a wide range of fluid viscosities, high pressures or high flow rates. So what can you do to make sure you get the best from your homogenization process for your specific application – and how can you maintain that performance through the lifetime of the machine?


The homogenization process is designed to give an even distribution of components within a fluid. This may be to improve texture; stability; properties of the fluid (e.g. to obtain better fuel combustion); clinical effectiveness (better active ingredient dispersion in pharmaceuticals), or to disrupt cells in biotech processes without the need for chemicals or solvents. Although the principles of operation of a homogenizer are pretty much the same across different models; selecting the correct materials, geometry and configuration are vital to the machine’s performance. Once operational, understanding how to maintain optimum performance of the homogenizer is also key to ensuring smooth operation and high quality process results throughout its lifetime.


Homogenizing valves

At the heart of a homogenizer is the homogenizing valve. The homogenization process works by forcing the basic product within the process through a small area between the valve and seat at high pressure. This creates a rapid increase in the velocity of the product and decrease in the pressure. The subsequent turbulence and pressure differences this generates tears particles within the fluid apart. While multiple passes through a homogenizer can produce narrower particle size distribution within the fluid, a number of different valve and material configurations are available to best suit the characteristics of the process fluid. Understanding the products involved, their compositions, structures and abrasiveness ensures correct selection of the type of homogenization valve required.


how_homogenization_works_graphic


Why materials and geometries are so vital

Valves, including valve seats, are designed for specific applications by configuring a number of factors such as geometry and material of construction. In terms of geometry the radial distance through which the fluid travels in the homogenizing valve /seat gap (land) is extremely critical.

By putting a large inner chamfer on the flat valve, a short-land valve seat is produced. The “land” is the surface on the seat that the fluid passes over as it travels through the gap between the valve and the seat. The short-land valve is beneficial when processing emulsions with the lowest homogenizing pressure possible to achieve normal shelf stability. This valve usually requires a second-stage valve or a backpressure device.

The overall goal in valve design is to provide the best homogenizing effect for the least energy consumption while providing longest service life. Through experimental tests and experience, it has been found that certain valve geometries are more efficient at homogenization than others, depending on the product or process involved.

Certain applications are specified with a two stage homogenizing arrangement. In such cases the type of valve and material for the second stage are also carefully matched to the requirements.


Low Pressure Applications

Operating under 250 bar (3,600psi), low pressure homogenization tends to use valves in stellite alloy or tungsten carbide material. The fluids typically do not contain abrasive particles, for example wax and grease emulsions.


Medium Pressure Applications

Many fluids are homogenized in the 250 to 600 bar (3,600-8,700psi) pressure range and will often contain abrasive particles; examples include silicone suspensions,carbon black and various emulsions. The valves for such applications are generally available in materials such as stellite alloy, tungsten carbide or ceramic. Tungsten carbide is selected for the more abrasive fluids due to its hardwearing characteristics.


High Pressure Homogenizing

These applications operate at pressures above 600 (8,700psi) bar and include, for example, cellulose fiber suspension, Titanium Dioxide suspension, bacteria cell disruption and algae cell disruption. The standard material is ceramic though stellite alloy and tungsten carbide are available ashomogenzing_valve_seat_wear_patterns optional selections. Tungsten carbide is more hard wearing than ceramic in many applications, however ceramic is preferred at higher operating pressure drops.


Maintain to optimize

For a given pressure and flow of a single emulsion the user should expect continually consistent results from their homogenizer. By its very nature, however, the homogenizing valve is a wear part and requires good, predictive maintenance strategies to ensure maximum runtimes without unscheduled downtimes. The environment within which the valve sits is also important to its operation, so correct maintenance of the complete homogenizer is needed to optimize its reliability and maintain its performance.


Tips and tricks that could save you time and money

Following are some top tips and tricks that may help keep your homogenizer performing at its best:

  • Always protect the homogenizer from the possibility that foreign bodies/particles could enter the machine.
  • Introduce preventative maintenance for the homogenizer wear parts, especially the homogenizing valve parts
  • Regular inspection of the condition of valve, seats and impact rings following the manufacturers recommendations.
  • In many cases it is possible to regrind the valve seat to restore optimum performance – see below example of how to distinguish between won seats which show partial radial wear marks
  • Where the valves and seats are worn, they should be replaced immediately., The example below shows continuous radial wear marks – such seats will give a poor homogenizing result.
  • When testing new formulations or recipes, always check that the homogenizer is designed to flow, pressure and level of particles.

worn_homogenizing_valve_top_part

Summary

When it comes to homogenization, SPXFLOW has a long history through its APV Rannie and Gaulin series technology. Our expertise can help ensure the highest quality results for the most complex applications. SPXFLOW has the widest range of homogenizers for applications ranging from pilot plant to large scale production, and solutions are customised to specific processing needs. The art of producing efficient, reliable and consistent homogenization results is based on an in-depth understanding of emulsions and production goals, whatever the application. SPXFLOW’s history with this technology makes its expertise unrivalled in the market place.

Editorial - Ensuring Safety and Quality in the Production of Infant Formula

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February 2016


Ensuring Safety and Quality in the Production of Infant Formula



Across the dairy, food and beverage industries, food safety is of paramount importance, but nowhere more so than in the production of early life nutrition products for babies and young children. SPX FLOW has had a great deal of experience in working with manufacturers of infant formula and this article considers some of the critical factors to ensure quality and safety in this sensitive production process.


From experience, SPX FLOW knows that the best processing results are achieved through co-creation of production lines with its customers. This close partnership encourages the sharing of expertise and specialist knowledge; gives clear understanding of expected key performance indicators (KPIs), drives project efficiency, and offers the potential to exceed system performance expectations. The result is that everyone wins – the food manufacturer, the technology provider and the consumer.


Infant formula or other powder based early life nutrition (including baby milk, follow on milk and growing up milk) require the strictest food safety and quality standards. To meet the demands of this market place, producers want absolute certainty in hygiene and food safety while protecting the nutritional value of the product. Other factors that impact powder quality classification include the level of scorched particles, solubility index, color, structure and other functional parameters. These are important considerations in the design of a processing line and the final value of the infant formula.


Infant Formula Processing


There are many stages in a complete process line for producing infant formula and consideration needs to be taken for the type of ingredients, their quality and their application (liquid, powder in wet or dry compounding). Each stage requires careful design to ensure the highest quality and food safety are maintained and that the plant is efficient, flexible and reliable. SPX FLOW uses advanced technology with the experience it has gained over many years in serving this industry to optimize all aspects of infant formula production.


Mixing


The first main step in producing infant formula is mixing. The quality of mixing has a big impact on end product quality and, where solids and liquids need to be combined, good dispersion is essential. To optimize quality and hygiene, SPX FLOW recommends the use of a vacuum mixer such as its innovative Flex-Mix Instant mixer.


There are many production benefits to a closed vacuum mixer including reduced mixing time, greater energy efficiency, reduced waste and easy maintenance; but for the purposes of this article let’s look at quality and safety issues it addresses:


During vacuum mixing, powder is sucked in from a closed powder hopper or bag system. Using the vacuum level in the tank, the powder is washed out directly into the circulating liquid below the liquid surface; ensuring dust is not released into the surrounding atmosphere. The wet and dry phases of the process are thereby completely separated, reducing the risk of bacteria formation. The use of a vacuum prevents air from entering the mixture, reducing undesirable effects such as oxidation, nutritional degradation and discoloring. The high shear pump is located at the side of the mixer which gives added ergonomic benefits including easy access and a safe environment for maintenance.


The Flex-Mix Instant creates high shear with a forced vortex which ensures fine emulsions that enhance product quality. It further offers a unique, patented valve arrangement that uses three valves at the powder inlet that automatically pulse the powder in using opening and closing sequences with delayed set points between the valves. This prevents any back flush of liquid into the powder supply line and ensures seats and seals are kept clean and dry for long periods; which not only reduces hygiene risks but also secures a stable process with extended lifetime, fewer blockages and less downtime.


Evaporation


The next main stage in the infant formula manufacturing process is an evaporation stage which is an energy efficient method of increasing total solids (TS) of the formula. An evaporator works by adding heat to the solution to a point where liquids turn into vapor and can be separated. The type of evaporator selected will depend upon local energy costs. Mechanical Vapor Recompression (MVR) evaporators use a mechanical compressor or fan to compress the vapor and need ample electricity supply. Thermal Vapor Recompression (TVR) systems use steam jets for compression and require a ready supply of steam to be available. The cost of steam versus the cost of electricity is, therefore, one of the primary considerations in selecting an evaporator for a particular plant.



The evaporator temperature is related to the evaporation pressure. System parameters are adjusted to optimize for product concentration and product quality as well as energy efficiency. Some plants select to use two evaporators which enable continuous production as one line is cleaned, the other is in operation; facilitating 24/7 production.


Using an evaporator reduces the energy required for spray drying and also helps extend the shelf life of the final product by removing occluded air from the fluid.


UHT Treatment


SPX FLOW Instant Infusion heat treatment technology is widely used for the production of Infant Formula because of the levels of food safety it offers while protecting nutritional quality. The process is a very gentle form of heat treatment that involves preheating to 75-85°C using plate and tube heat exchangers followed by rapid super-heating to around 140°C using steam infusion. The product is distributed in the form of thin strings into a chamber and is instantly heated by direct steam.


A short, accurate holding time in the range of 0.1-0.5 seconds avoids damage of essential amino acids, proteins and vitamins that can result in nutritional degradation, unacceptable flavor changes and the formation of burnt particles. The high temperature gives exceptional kill rate and eliminates even heat-resistant bacteria spores. This makes the process ideal for Infant Formula by protecting the quality and nutritional value of the product while ensuring the highest standards in food safety.


Optional Cavitation Stage


The SPX FLOW Cavitator™ uses a rotor with precisely machined cavities spinning in a liquid chamber that generates controlled cavitation. The process increases spray drying efficiency by reducing fluid viscosity and enabling an increase in solids level as well as adding microstructural conditioning that optimizes particle structure, size and distribution of solid components.


Combined High Pressure Pumping and Homogenization


Homogenizers are not complicated pieces of equipment but correctly designing and applying them requires skill and understanding. Homogenization helps with controlling final product quality, especially the levels of free fat which effect stability of the infant formula. The Homogenizer acts as a high pressure pump feeding the product to the spray dryer.


Spray Drying


The main part of the latter processing stages for infant formula production involves a spray dryer. This process is vital to final product quality and gives complete control over characteristics such as density, moisture content, powder properties and sensorial aspects. As there is no further heat treatment, it is imperative that product contamination is not allowed. To this end, the air supply to the dryer uses HEPA filters and systems are designed for straight forward cleaning, to minimize the risk of cross-contamination and to maintain food safety.


The Anhydro Triple A spray dryer incorporates an internal fluid bed. This supports e forati of strong powder agglomerates before entering the external fluid bed which further dries and cools the formula ready for packing. This efficient cooling of powder helps maintain quality during storage.


Both internal and external fluid beds in the drying stages of the process are self-emptying. This helps minimize contamination at product changeover, reduces loss of powder in the system, and also ensures powder is out of the system for a more effective clean-in-place (CIP) cycle.


During spray drying the very fine powder and air is transferred to cyclones for separation. The powder fines can be returned to various positions in the process via a flexible fines return system which can further improve agglomeration.


Drying of infant formula powders also presents an explosion risk and comprehensive safety equipment is required to ensure protection of plant and personnel. Rupture chambers, vent ducts, firefighting systems, CO detection systems and suppression systems are all included in the design of a spray dryer. SPX FLOW also offers an early warning camera software system on its Anhydro spray dryers. This detects powder build-up on spray nozzles and gives a potential early warning to operators as there is a risk these may cause fire – enabling action to be taken to avoid emergency shutdown.


Automation Systems


Automation is an important part of an infant formula processing line. Modern systems including the FactoryExpert™ automation solution help ensure reliability and optimized operating costs but they also add flexibility, traceability, assist with the control of quality and enhance overall operational safety of the system. Full integration with enterprise resource planning (ERP) systems accurately measures performance and provides real-time data to monitor product quality and need for proactive maintenance to keep the system running reliably and consistently.


Summary


The production of powder based nutrition involves many process stages, all which require careful integration and design to ensure the desired product quality and maximum food safety is achieved. To ensure all KPIs are met and high consumer confidence in a product brand, a close working relationship between processing companies and technology providers has been shown to yield the best results – offering efficiency, consistent quality and assured food safety at every stage of the processing line.


Each stage of the process requires understanding of the technology and the internal impact it has on the infant formula to maintain and control its desired characteristics. In SPX FLOW’s experience, achieving the highest standards of safety and quality does not mean manufacturers of infant formula need to compromise on production efficiency and flexibility. Systems are designed to meet the needs of today and the future, covering areas such as advanced powder nutrition for all life stages. Features and functions that provide food safety and plant safety are integrated into the plant throughout production stages, brought together with modern automation systems that help protect and control the whole process.