With the Conti-TDS powder wetting and dispersing machine, even powders that are difficult to wet, dusty or sticky can be dispersed agglomerate-free

Inspired by the large-scale model, the modular paint factory (MoFa), the "Mini-MoFa" represents a new trend in production systems in the chemical and paint industry. The production of multifunctional semi-finished products, pre-formulations and the actual end product reaches a new dimension in terms of flexibility and quality with the Mini-Mofa. Components such as industrial design, functionality, user-friendliness and cleaning effort, which were previously considered peripheral, have been completely redeveloped and redesigned.

Whether as a development module for new recipe variants, as a "scale-up monitor" for large batch production or as an indicator for determining production costs - the "Mini-MoFa" opens up all decisive parameters.

Status quo: dissolver production

Modern production processes based on dissolver technology, which correspond to the state of the art, are mostly semi-automated processes. The degree of automation is usually a maximum of 75%. For large products, the batch size is between 5,000 kg and 15,000 kg. Solids are dosed from sacks, big bags or silos. It is a time-consuming process in which dust deposits and hard agglomerates form in the headspace of the batch container. These can contaminate the product when the container is emptied.

Dispersion, wetting and homogenization are statistical methods, i.e. they show a large scattering of results and thus of quality characteristics.

An elementary problem with water-based systems is the intake of large quantities of air due to the formation of bubbles during the dispersion process. As a result, the dissolver must be operated at different dispersion speeds, which in turn affects the particle sizes and particle distribution. This is followed by a grinding process with an average throughput of approx. 1,000 kg/h. This process is combined with classic agitator technology. This all leads to a lack of flexibility and a narrow process window.

Certainly not all processes correspond to the scenario described. An average process is shown schematically below.

Perspective: Modular production

Compared to the standard process mentioned above, the degree of automation is higher in modular production. This allows fully automated processes to be achieved. Another advantage is that there is no limit to the batch size. Batches of up to 50,000 kg are currently common. Handling the solids is also easier. Silos are no longer necessary as silo trucks can be unloaded directly. The investment costs are correspondingly lower.

Moreover, in modular production with the MoFa, dispersion is not a statistical model, but a forced dispersion. Mixing and dispersing run with significantly less or even no air intake. The grinding technology used makes volume flows of more than 10,000 kg/h possible.

All these aspects open up a significantly larger process window and potential for considerable cost reductions. Compared to the standard process, the Mofa requires only about half as much space and only about 30 % of the energy costs. The product quality is also significantly better: a sinusoidal distribution becomes "line quality".

Modular production in any batch size

The Mofa is available in various sizes:

- The Mofa series has been around for seven years and can be designed for batch sizes from 5,000 to 50,000 L (Fig. 1).
- The Mini-Mofa series is new for batch sizes from 300 to 5,000 L in five different sizes (Fig. 2).
- The Micro-MoFa series comprises batch sizes from 2 to 300 L in five different sizes and is suitable for test batches on a laboratory scale as well as very small batches. Fig. 3 shows the first Micro-MoFa.

The Mofa is designed as a large-scale solution. It is adapted to the structural infrastructure and integrated in such a way that an optimal production process is guaranteed. A batch size < 5,000 L does not make sense for this type. To cover this range, the Mini-Mofa was designed and developed as the world's most compact paint factory. This type of system has a specially developed integrated cleaning module. This makes it easy to change products from black to white.

Thanks to an innovative recipe organization, the Mini-Mofa works almost waste-free. The system has a modular design and can be fully assembled within a week. All components are installed on the system frame, thus eliminating high investment costs in the building infrastructure. Only the necessary energy is supplied: electricity and compressed air.

Air-free dispersion

The central dispersing unit "Conti-TDS" (transport dissolving system) is a rotor/stator machine that works according to the centrifugal principle (Fig. 4). The special design of the rotor creates a vacuum during the pumping process, through which the solids and liquids are sucked in. Due to the high vacuum, the dispersing unit conveys the powder in a dense flow, so that no additional conveying air is required. The air adhering to the powder (difference between bulk density and specific gravity) is separated during the wetting and deagglomeration process. The result is a practically air-free product. The separation of the air and the complete forced wetting of the particles takes place in the vacuum area of the dispersing zone.

The dispersing unit basically works as a "side-line" wetting and dispersing machine. For this reason, important production parameters, such as the dispersion speed and throughput, are constant for all batch sizes.

Integrated jet mixing technology

The jet mixer installed in the process tank (Fig. 5) ensures intensive, air-free and homogeneous mixing of the entire contents of the tank, regardless of the batch size, viscosity and flow properties of the products to be produced. These functional properties enable the production of products with a specific weight > 2.5 kg/dm3 ("high-solid products"). The additives used are distributed directly over the entire contents of the container.

Dust-free solids dosing

Solids are dosed dust-free from specially developed reusable containers. A large volume container has a capacity of 50 to 1,500 liters and a small volume container - from 1 to 70 liters. Both container types are coupled in a self-sealing manner. They are pre-weighed and emptied via the vacuum of the dispersion unit. The containers are handled inside the Mini-Mofa by an integrated crane system.

Liquid dosing

Two different options are available for dosing liquids. Liquid raw material doses from containers with a filling volume of up to 1,000 liters (e.g. IBCs, stainless steel containers) are automatically dosed via the integrated crane system with weighing device. Quantities of up to approx. 20 kg can be added via the small quantity hopper provided for this purpose. Both dosing streams are fed into the volume flow of the dispersion unit via a feed pump. This technology guarantees absolute fine distribution of the raw materials introduced into the liquid feed in the container. The "MiniMoFa" is designed in such a way that the large components can be dosed from the container without dripping (Fig. 6).

Integrated cleaning concept

Based on the requirement for more frequent product and color changes (black and white), a cleaning concept was developed that encompasses the entire system. All system components required for cleaning are part of the Mini-Mofa and do not have to be additionally adapted. The cleaning process includes containers, product-carrying pipes and hoses, powder and additive paths. The central dispersion unit is used to input mechanical cleaning energy. All surfaces and pipe connections are designed to ensure residue-free removal of the products. The cleaning process is based on cascade technology and is individually adapted to the requirements.

Operation and maintenance

The entire system is operated via a programmable logic controller (PLC) using a touch-screen monitor (Fig. 7). The operator can choose between semi-automatic and automatic operation. Maintenance and servicing work is carried out in service mode. The process sequence is carried out via recipes with operator guidance. All possible process variants for production and cleaning are stored in the control system.

At the end of the process, a batch report is created containing all relevant process data. The entire process unit is weighed for additional weight control of the added components. This means that a continuous plausibility check is possible throughout the entire production process. An externally adapted bead mill is also operated and monitored via the control system. The control system monitors all wearing parts of the system by monitoring operating hours and switching cycles. A maintenance schedule is stored in the control system for these components. Before the maintenance interval is reached, the control system reports which system components require maintenance and to what extent. This eliminates the usual effort required to monitor maintenance activities.

MoFa versus dissolver technology

Compared to conventional dissolver production, modular production using MoFa and/or Mini-MoFa offers a number of advantages, such as

- Reduction in production times of up to 80%,
- Reduction in energy costs of up to 70%,
- Reduction in labor costs of up to 80%,
- up to 100 % higher capacity,
- up to 100% more flexible batch sizes,
- constant production parameters (line quality),
- Up to 50% reduction in testing costs due to increased batch capacity,
- any product change, operation of the system by a single employee,
- Reduction of additives in the formulation thanks to increased efficiency of up to 25%,
- better dispersion thanks to the "Conti-TDS",
- Avoidance of air entrainment in the production process,
- Reduction of odor emissions,
- improved work hygiene and cleanliness.

Outlook

The Mini-MoFa offers advantages in terms of economical production, product quality, occupational hygiene, health and safety and design. It can be used as:

- Development module for new recipe variants,
- production system,
- scale-up monitor for large batch production,
- indicator for determining production costs.
The systems in operation confirm all specifications.