Technologies in process technology rely on process intensification and efficient use of the time, energy and raw materials. Mixing and dispersion with new optimised processes generate significant differences with regard to required energy, volume-specific capacity or newly created phase boundaries compared to conventional technologies such as agitators, injectors or high speed dissolvers.
More specifically, a comparison between the energy density of conventional processes and ystral technologies shows significant differences. While energy density with a conventional agitator is in the ballpark of only 0.005 MJ/m3, and with a dissolver at approximately 0.05 MJ/m3, the energy density with an ystral Conti-TDS is up to approx. 5 MJ/m3, and with inline dispersion up to 100 MJ/m3 in a single pass. Modern process technologies have a significantly more intensive effect on the product.
As more intensive processes are faster than traditional processes, new technologies introduce cumulatively less energy and so less heat into a process. For example, the Conti-TDS inline powder wetting and dispersion machine ystral operated in the circuit with an energy density of 5 MJ/m3 introduces only around 0.3-0.6 K of heat per pass.
A ystral Conti-TDS operated in a process vessel usually requires only a third of the cumulative total energy of a high speed dissolver, and less than a twentieth of ball mills. The temperature increase is proportionately low over the entire process, as is the associated effort for cooling.
Process intensification also results in a more efficient utilisation of raw materials. In this way, powders can be processed without loss during introduction by a vacuum, compared to addition to a liquid surface or into a powder conveyor with extraction systems and separators, when part of the solids are lost in the filter.
In addition, due to the improved particle breakdown, the quantity of the raw materials used can be reduced. Cost savings are therefore possible for expensive raw materials such as titanium dioxide. For wall paints, the quantity of titanium dioxide can be reduced by up to 8% with the same colour strength and the same hiding power.
POLLUTION-FREE PROCESS CONTROL
New findings concerning health hazards when handling powders and liquids increasingly require process control that is free from dust, gas and fumes. Technologies from ystral enable powder processing without releasing dust.
For example, a plant installed by ystral for the processing of amylase and protease enzymes used for dishwashing detergents are highly sensitising in powder form. Previously, these powders were added to the liquid surface with mechanical or pneumatic conveyor systems. People at the manufacturer’s office building roughly 50m away showed symptoms of asthma and itching. The plant, now using the ystral Conti-TDS, does not need any filter and conveyor systems and introduces the enzymes into the liquid from the big bag.
At the end of a process, the plant is usually cleaned with water or cleaning agents, but the cleaning process can be dispensed with in the production of foodstuffs if the process conditions can be controlled in a way that there is no risk of pathogen growth in the plant.
However, this is not possible for vessels, which have often been cleaned with cleaning agents at the end of a process. As this is cost-intensive, there is a trend in process technology towards utilising residues of the previously produced product in the subsequent batch. During filling, they are rinsed out under high pressure with recipe components of the coming batch.
During cleaning with recipe components, machines, pipes and vessels are rinsed under high pressure.
BIOCIDES REDUCED OR ELIMINATED
Manufacturers in different industries are aiming to reduce biocides in their products or completely eliminate them. Giving up the use of biocides is possible if the product in the production process is not contaminated with germs – particularly germs from the ambient air.
For example, during the production of shampoo, all liquid recipe components and the process water can be kept sterile while being easy to control. The powder components are also available in controlled quality. However, it gets tricky when adding recipe components to the process vessel, above all when adding powder components. Germs get into the product in an uncontrolled manner when opening the vessel and through contact with the ambient air when introducing the powder or liquids. Therefore, preservatives must be added.
With ystral processes, powder and liquid components are added in a closed circuit. The interior of the process vessel is sealed from the ambient air by sterile filters. In this way shampoos, can be produced without preservatives. Before starting the process, the vessel is filled with sterile air. Then, sterile liquid and powder recipe components are added without opening the vessel.
Many processes, which previously had to be carried out at high temperatures, can be implemented at significantly lower process temperatures by means of intense dispersion under high shearing and intensive mixing. This lowers the energy requirement and enables gentler processing of raw materials.
In addition to cost advantages due to the reduced energy requirement, cold process engineering also has a positive effect on product quality. This is the case for the production of aromatic substances, since they are volatile. The higher the temperature is during processing, the greater quantity of aromatic substances are lost. If the temperature can be reduced to 60°C in such a process that previously had to be carried out at 80°C, more aroma can be extracted.
In traditional process technology, many processes take place in a vessel. This makes production processes inefficient, energy-intensive and slow.
High speed dissolvers can be used in production, but it is more efficient to carry out powder wetting and dispersion outside the vessel. In the vessel, only a homogeneous mixture is needed, which can be realised by using a jet-stream mixer.
The intensity can be measured through the capacity introduced per unit volume. With the high speed dissolver, this is approx. 10 kW/m³. With the Conti-TDS, however, this is approximately 200,000 kW/m³, as the volume in which the entire capacity is produced is only a fraction of a litre.
In light of variable requirements and variable batch sizes, a flexible machine and plant design is becoming increasingly important. Concepts for building plants from modules are well-documented in the process industry. ystral plants are also based on the principle of modularity, as physical modules can be combined with control modules and adapted to requirements, or extended. With Conti-TDS, ystral uses conversion sets, for example, to tailor a universal basic machine to changed requirements; the machinery can be adapted to new requirements by replacing the tool head.
Many process steps can be combined into a single system, meaning that individual processes can be realised in parallel.
Dispersers and mixers from ystral are useful in process technology. For example, the ystral Conti-TDS inline disperser combines several processes for the processing of powders in liquids: transport, dosing, addition and mixing, as well as dispersion and dissolution.
When using combination machinery, such as a ystral Dispermix, a combination of mixer and disperser, multiple processes can also be carried out in parallel in one system. This machine is used for products for which the mixing of powder or liquid with liquid is not sufficient, and rotor/stator dispersion is too intensive.
REDUCING BATCH SIZES
There is a trend in many processes towards a decrease in batch sizes. Small batches mean greater flexibility,
reduced space requirements, easier cleaning and accelerated processes. For example, producers of varnishes and paints benefit from switching to smaller batches.
This trend also applies to the pharmaceutical industry. Batches tended to get bigger in the coating and inks industry due to unavoidable fluctuations in quality due to dispersion with the high-speed dissolver. The lack of consistency has meant that every batch needed to be checked.
Conti-TDS technology can resolve a fluctuating dispersion quality. Readjustment of viscosity, colour strength or hiding power is not necessary. This enables flexible production in small batches.
At a twin tank plant, production takes place in one vessel and the finished product is pumped out in a second vessel. The twin-tank principle is also used at ystral for increasing plant capacity, as a Conti-TDS is only used for powder introduction and dispersion. By alternating the use of the Conti-TDS in two identical process vessels, downtime can be minimised.
A trend in process technology sees a move from production of scratch (co-grind) to slurry. As the powders are introduced individually for slurries, the raw material can be dispersed optimally. In addition, compared to powders, slurries are easier to store and pump across long distances, and are dosed more precisely. Cleaning processes are easier because only liquids are processed. Powder handling is only necessary when producing slurry, but not when producing the end product. This enables faster product changes.
INLINE INSTEAD OF BATCH
More users are switching from batch production in the process vessel to continuous production without the process vessel for large production quantities. In addition, powders can be processed in a continuous process, but introduced in liquid form as slurry because they contain a large volume of air.
Progress in sensor technology enables users to make predictions of how long machine components will still work properly. It is possible for predictive maintenance to replace machine components before they become faulty.
The changes in process technology are varied and do not always point in the same direction. However, the solutions which will be successful will be those which decrease production costs, shorten production times, improve plant efficiency, lower energy consumption and use raw materials more efficiently.
BOX: ABOUT THE SUPPLIER
ystral designs and manufactures highly efficient mixing, dispersion and powder wetting machines as well as process systems. The technologies of the owner-managed family business are used worldwide in chemical, pharmaceutical, coatings & inks, foodstuffs, home and personal care and battery production industries.