Optimal Digester Sludge Circulation

Bottom-up circulation (clockwise rotation) The mixer moves the sludge upward through the draft tube. The massive, rotating deflector disc above the impeller distributes the sludge across the sludge surface. This prevents a gas-tight foam layer from forming. Heavier sludge ingredients sink to the bottom of the tank by gravity. The digester tank content is thoroughly mixed from the bottom to the top to avoid thermal stratification. The suction at the bottom of the tank moves heavier ingredients through the draft tube to the top. The entire content of the tank is circulated several times per day....

The Draft Tube Mixer Six Tasks – · – · – One Solution 1 Preventing thermal stratification Heavy ingredients sink to the bottom if they are not actively circulated. All areas of the tank are mixed consistently. Anaerobic bacteria are only effective within an optimal temperature range. The mixer prevents the formation of thermal layers between the top and bottom of the digester tank. Homogenising sludge Avoiding scum and foam The smaller the solids and the better they are distributed within the digester tank, the better the digester bacteria can decompose the organic components. This makes homogenising...

Careful Homogenising for Optimal Sludge Stabilisation The Träxler draft tube mixer (TMA) Anaerobic sludge stabilisation turns sludge into a form that makes further handling and disposal easier. The amount of sludge is reduced. Dewatering of the residual sludge is easier, and the digester gas yielded can be used for power and heat generation. For this reason, we rely on the method of carefully homogenising the sludge in the digester tank. Homogeneous sludge mixing causes a rapid anaerobic digestion with the best yield of digester gas and welldigested residual sludge with a low content of solid matter. This high...

TMA Draft Tube Mixer – Homogenisation Made to Measure Only careful homogenisation can create the right conditions for optimal sludge stabilisation: We  follow the concept of homogenising the sludge consistency and temperature levels throughout the entire tank, preventing sedimentation and reducing the concentration of organic matter. When mixed well, organic matter degrades quickly, methane yield is maximised, and the volume of solid matter is reduced, thereby optimising digestion.  Competing systems A comparison of the various technical systems used for this purpose shows significantly  differing results. They must be analysed in each individual case according to economic...

Mixer Components 1. Drive 1 2 The drive features an ATEX-approved three-phase motor designed for clockwise and counter-clockwise rotation. The motor  is mounted on a motor lantern. An elastic coupling connects the motor to the mixer shaft. The direct-drive design eliminates the need for a gearbox. Exception: mixer type TMA8. An electric grease pump supplies lubricant to the mixer  bearings and to the cap sleeves facilitating gas tightness. Using the correct type of lubricant prevents bearing damage. 3. Guide and mixer grease The guide bearing at the top stabilises the shaft. The support bearing at the bottom supports the weight of the impeller and ...

TMA Draft Tube Pipe: Targeted Circulation Throughout the Entire Tank The mixer's key function is to thoroughly mix the sludge in the digester tank: to distribute fresh sludge quickly within the tank, to homogenise the sludge, to ensure uniform temperature distribution, and to avoid sedimentation. For this purpose, Hermann Träxler GmbH uses powerful mixers with an impeller running in a central draft tube pipe, effectively moving the sludge upward or downward. The central draft tube ensures that the contents of the entire tank are mixed. It creates an annular flow inside the tank, circulating the...