Lesson 5 - Wort Boiling Technology and Process Control SAQ

**Your brewery uses an internal calandria for wort boiling. Your current wort boiling total evaporation is eight percent. What changes to the process and equipment could you make to reduce the energy used in wort boiling without affecting wort quality? 

Response:

The first option is to modify the way you boil using the internal calandria and introduce dynamic low pressure boiling. A significant amount of capital expenditure is required for this approach because the kettle and stack need to be modified and certified to withstand pressures above atmospheric. Also, a valve and a control system need to be installed and modifications carried out to the calandria. Once this is installed, the boiling process can be changed to involve several short phases of pressure build up and pressure release, providing extensive vapour bubble formation. This process can achieve the same results as a standard boil but with evaporation of around 4.5 percent and a shortened boil time.

By installing a vapour condenser into the stack and a condensate cooler, the energy from the vapour can be recovered and used to pre-heat the wort flowing to the kettle. This reduces the amount of energy required to boil successive brews. This reclaimed heat could also be used to heat the mashing vessel, reducing the number of times the steam boiler runs at maximum. A vapour condenser can also be used in conjunction with thermal vapour recompression which uses steam to convert the vapour from the boil into useable steam for wort boiling. Further energy can be recovered from the condensate. 

Alternatively, mechanical vapour recompression can be used to convert the vapour from the boil into useable steam for wort boiling. Again, further energy can be recovered from the condensate. 

Systems incorporating heat recovery from condensate can also use an energy recovery tank, to store the energy recovered from the boil.

Another alternative is to introduce gas sparging into the wort kettle. By doing this, the internal calandria is still used to heat up the wort to just below boiling temperature. Then gas sparging is used to remove volatiles, ensuring sufficient wort mixing. Not needing to provide the thermal energy to boil the wort results in a significant reduction in energy use.

The brewery could also add a vacuum evaporator or gas stripping equipment after the whirlpool. These reduce the amount of evaporation required in the boil and hence the energy used.

Whatever is used, the quality of the wort and beer produced must be closely monitored during the implementation of any changes. Ideally trial brews would be carried out using the equipment at pilot scale before any money was committed. And whatever technology is considered must be small enough to be accommodated in the existing brewhouse. With many of these technologies the most sensible option is often replacing the kettle or even the complete brewhouse!