- Cleanup could require hours of effort, shutting down production.
- Risk of product loss during the overboiling
When a large brewery needed a solution to kettle overboil, they needed to address the obvious risks from above, but they also wanted to provide additional benefits to plant operations.
Under the prior operating guidelines, the brewery’s kettles often overboiled. A kettle overboil situation could occur as many as 30 times in a typical life cycle from filling to knockout. When an overboil situation occurs, the steam exhaust valve should shut immediately. This shut-down will avoid a massive product loss, and it protects personnel in the immediate area from this situation.
However, the downstream effect of having the exhaust valve slam shut during an over-boil event is dramatic on demand for steam from the utility department. The steam demand for brewing can swing as much as 40,000 to 80,000 lbs. during this event which can easily pull a boiler off-line.
Utility Department Issues
Aside from preventing an undesired over-boil situation and a dangerous environment to personnel in the immediate area, finding the right solution would provide several benefits to the utility department with issues related to steam demand swings
- The Boiler draft problems occur when rapid load changes occur due to excessive steam demands. Boiler controls react by increasing fuel and air supply to meet this new demand. If equilibrium is not established, the boilers can trip off-line due to positive or negative drafts.
- Boiler trip on low water levels can occur when the steam load suddenly drops. The feed water and the steam valve work together, and as the demand for steam drops, the feed water valve starts to close. This could cause the boiler to trip off-line due to the low water level.
The Solution
The brewery contacted Drexelbrook to provide a suitable solution. After reviewing the requirements, an RF level technology solution was recommended which would allow plant operations to control the kettle boil without damaging quality and manage the swing demands for steam by preventing an over-boil situation.
Drexelbrook’s solution is to provide a continuous level measurement that generates a signal proportional to the amount of foam on the RF sensor that is generated during the boiling process. Past methods used a “presence or absence” measurement by the so-called point level instruments or Level Switches; these detect when the foam reaches the over-boil stage. The continuous proportional signal is used as one input to the logic controller to modulate the amount of steam that is used during the boil. The logic program keeps the temperature while gradually cutting back on the steam, avoiding over-boils and drastic swings of steam demand.
The Drexelbrook continuous RF system is comprised of a standard RF transmitter and an RF foam sensor that is long enough to cover the anticipated range of foam in the kettle during the boil. RF technology was proven to provide the best reliability and repeatability in this measurement.
A Drexelbrook RF Admittance system was the base for this measurement of foam level. The Admittance technology allows accurate, repeatable, and reliable performance in the face of any coatings deposited on the sensor from the foam. Foam sensors are fully Teflon coated and are available with 3A certification and sanitary designs with NPT, Flange, or Triclover fittings for mounting on the kettle. RF Admittance Technology is immune to coating build-up, variations in product density and temperature, or pressure changes while maintaining the sensitivity required for foam measurement.
Learn more about level measurement solutions for food and beverages industries in Drexelbrooks free Learning Zone
