Brewery Filter Tank

Craft of brewed beer – Filtration process of filter tank

Johnson screen is widely used in Breweries, wedge wire false bottom screen (lauter tun screen & mash tun screen), spent grains dewatering screen, rotary drum screen and so on.

The filtration tank is not only an old but also a widely used wort filtration equipment, the filtration tank of brewery is a cylindrical container, in which there is a perforated sieve plate, which supports the wheat tank, and the wort is filtered.

We use Johnson screen (wedge wire screen) instead of perforated plate, with larger flow, longer service life, not easy to block, easy to clean.

Filtering steps of filter tank

• hot water pressure in:In order to filter quickly, the sieve plate must be clean and free of dirt and air bubbles. Therefore, hot water should be pressed in from the bottom of the Johnson screen plate, and the sieve plate should be preheated at the same time.

• Mash pump in:The mash should be pumped into the filtration tank as quickly as possible and evenly distributed, otherwise, it will lead to uneven dissolution of the leachables and decrease the leaching rate.
  Static: After the mash is pumped in, a grain layer of 25cm high will be formed when the unit load is 150kg / m, and when the unit load is 200kg / m, the thickness of the waste layer is about 34cm.
  The first wort is gathered on the top of the lees layer, which is necessary because the wort tank is required as the natural filtering medium for wort filtration, which is called filtration standing.
  The higher the temperature of saccharification termination, the looser the wheat trough, and the faster the filtration. For this reason, temperature drop must be avoided during filtration.
  
• Pre spray and turbid wort return:There are some particles passing through the Johnson screen sieve plate between the sieve plate and the bottom of the tank, these particles and the wort just filtered form turbid wort. The turbid wort must be refluxed. It enters the tank from under the wort liquid level of the filter tank and refluxes for 5-10min until the wort is clear.
  The purpose of refluxing wort into the filter tank is to minimize oxygen absorption.
  For the filter tank still using valves for filtration, the two filter valves are always opened at the same time and closed immediately during reflux, in this way, eddy current will be formed in the cross-section area of the filter valve to take away the turbidity at the bottom of the tank.
  This process is called “pre spray”, and the pre spray operation is repeated 2-3 times.
  
• First wort filtration: The first wort should be filtered as quickly as possible to avoid unnecessary time loss. The first wort from each wort tube is the same.
  The first wort is filtered through the trough layer. The trough has resistance to the outflow of wort, which leads to suction.
  When the natural filtration amount is less than this amount, the tank layer is constantly compressed, the resistance increases, and the outflow of wort is also less and less, which in turn will cause the filtration speed to slow down.
  
• Filtration of wort in wash tank and wash tank: When the grains in the tank are just out of the liquid level, the first wort filtration should be stopped and the grains should be washed.
  The washing water will submerge the grains and slowly press out the wort from top to bottom to wash out the extract from the grains.
  The leaching out is not fast, it needs a certain time.
  Before or during the washing, start the plough, the operation of the plough mainly depends on the filterability of the malt. First, plough the surface of the malt, then the plough blade is lowered slowly until it is 5-10cm away from the sieve plate.
  Don’t put the blade too low, or the wort will be turbid again, the time of filtration and the brightness of wort were determined by the operation of ploughing.
  
• Exhaust sludge: After washing residual water, adjust the blade crosswise to row the grains. In the new filter tank, the plate is opened downward, and the grains fall from the mouth.