Electric Boilers and Operation

Flashcards covering the introduction to electric boilers, their operation, efficiency, safety features, and maintenance, based on the provided lecture notes.

When are electric boilers typically used in conjunction with a large power plant?

As standby or emergency backup for times of low output, low demand, upset, or to keep things warm during a plant upset.

What is the claimed efficiency of electric boilers?

99% efficient.

What is the upper operating pressure limit for electric boilers and why?

Limited to about 2,100 kPa due to concerns about overheating electrodes and heating elements.

What is necessary in the water for an electric boiler to transfer current?

A little bit of dissolved minerals to transfer water currents through the water and electricity.

How do electrodes heat water in an electric boiler?

By submerging electrodes into the water, creating a circuit or pathway for electricity to travel, which heats the water as the current passes through it.

How does the float system in an electric boiler respond to an increasing steam load?

As the steam load increases, the water level lowers, causing the float to lower and send a signal to start the boiler feed water pump or open a control valve to replenish water.

What happens when the float arm in an electric boiler gets too high?

It should send a signal to stop the feed water pump or other water input, ceasing water replenishment.

What system is in place to prevent overcurrent in electrodes?

A load monitoring system that will limit current to electrodes to prevent them from overheating.

What company was mentioned as a manufacturer of high voltage electrode boilers?

ACME Engineering.

How is the hot water generated in a high voltage electrode boiler design?

In a closed loop system.

What are the typical voltage ranges for electrodes in a high voltage electrode boiler?

From 4 kV up to 25 kV.

How is the output capacity of an electrode boiler changed?

By raising and lowering a shield, which either exposes more or less of the electrodes to the water, not by changing the input voltage from the grid.

What is continuously monitored in an electrode boiler to ensure proper operation?

The conductivity of the water, via a conductivity sensor.

What is the purpose of the chemical treatment tank in an electrode boiler system?

To balance water chemistry through periodic injection of new chemicals, helping to maintain water conductivity and prevent fouling.

What practices are important for maintaining an electric boiler once it gets fouled?

Having a system or plan to pull out and clean the heating bundle, often using an acid or CLR to boil off scale.