Statistics tell us that every German citizen eats around 9.5kg of chocolate a year, in the form of bars, hollow figures, pralines and such like, with a particularly steep rise in consumption at Easter and Christmas.
The sweet may be very popular, but it is extremely complicated to make. In particular, the temperature has to be precisely controlled at all times to achieve the later melt-in-your-mouth effect. To avoid there being any gap in the processing chain here, NETZSCH Pumpen & Systeme GmbH has now developed a special tempering pump known as the chocolate pump.
It is designed to meet the strictest hygiene requirements and is also easy-to-clean. This means one type of pump can cover a really wide range of tasks in chocolate production.
The secret of high-quality chocolate is ensuring that the fat crystals contained in its fats are configured in the best possible way. This is directly dependent on tempering. If the temperature is too high or too low, chocolate will no longer melt in your mouth or will not have an attractive, shiny finish, but a milky, lackluster look instead. The viscosity also changes along with the crystal content, and this may lead to problems further on in processing or when filling. Tempering is therefore crucial in terms of quality. This means tempered chocolate needs smooth conveyance at a constant temperature.
Controlling the temperature of each pump part independently
That is why the NEMO progressing cavity pump, which is characterized by its particularly smooth performance in conveyance, is used as the chocolate pump. It is based on the geometries of a helix rotor and the reverse-helix stator surrounding it, with these being precisely attuned to one another.
The sealing line between the two means that sealed conveying chambers are formed with the continuous rotation of the rotor. These allow the medium to move from the inlet to the discharge side at a stable pressure and pulsation-free. The size of the chambers and the low surface speed of the rotor even allow coarser solids, such as nuts or brittle, to be conveyed without any damage being caused.
An adjustable heating jacket has been added to this proven form of pump for tempering. This encloses the whole length of the pump, from the mechanical seals to the pressure ports. It allows the required heat to be kept constant through the various stages of the process. As an option, the complete heating module can also be split into several sections which are controlled separately and can generate different temperatures. This means it is possible for instance to ensure a permanent supply of heat to the mechanical seals, where the fats otherwise often cool down and crystallize.