Equipment- Water system Flashcards
What is the Kemco Heat Re-use System and its effect on water?
• It is a system of tube and shell heat reclaimer that is used to preheat incoming water with waste water and boiler stack gases.
What is tempered water and why do we use it?
- It is preheated water used to replace cold water.
* Used to avoid shocking poly garments by having cold city water injected.
At what temperature should your hot water tank be set?
- 145-150 Degrees
* If no hot water then will have to inject steam to get the water hot. This in not an effective way to do it.
Why do we have holding tanks for hot and tempered water?
• To reduce fill times- the holding tanks maintain a supply of hot and tempered water that are used to meet the demand of the wash alley.
What is a boiler stack economizer? What temperature increase should you typically realize with this piece of equipment?
- It reclaims the heat from the exhaust from the boiler that is normally wasted out of the boilers’ vent and transfers it to the boilers feed water system.
- 20-25 degrees heat rise
What is a wastewater heat reclaimer and how does it function?
- It uses the ambient heat in the wastewater to preheat the incoming city water.
- Waste water goes in the tubes flowing in one direction and city water surrounds it flowing in the opposite direction. The city water will pick up the heat from the waste water as it passes by.
What is the purpose of the packing or turbulators in a stack economizer?
- Provides direct contact heating of the water as it passes over the tubes.
- Increases surface area
With respect to the flow of city water, what direction does the wastewater flow and why? Is there any reason this direction would ever change?
- Moves opposite the incoming city water.
- The only reason they would move in the same direction is when wastewater is reversed. Done every 15 min
- This is done during back-flushing of the heat re-claimer to help prevent buildup of deposits in the tubing.
- City water always runs the same direction
What does the word “approach” mean, and what should it be on a wastewater heat reclaimer?
- The difference in temperature in incoming wastewater and preheated water from the reclaim system.
- The approach should be 10 degrees
If your wastewater heat reclaimer goes down, what impact would this have on your operation?
- It would not affect our ability to operate as we have the ability to bypass the heat reclaimer.
- It will drastically increase our energy usage and costs.
How else do we heat hot water? Is this an open or closed system?
- Side arm heat exchanger- uses steam from boiler to heat water to desired temp. This is a closed system.
- We can also inject steam directly into the wash wheel. This is considered an open system. It is not ideal as it causes increased cost and causes boiler chemistry to be injected into the wash wheel
What is meant by “emergency fill rate” versus “average fill rate,” and what is its importance?
- Emergency fill rate is when the demand from the wash alley exceeds the ability of the hot water tank. This happens when we do not balance the washalley and run using the same amount of water all day.
- Average fill rate- is our typical demand. Allows water to stay longer in the heat reclaim system and increases its heat.
If a hot water pump goes down, what would you do?
• Our system has backup pumps for both hot and tempered water. We would switch to the backup pump and make the necessary repairs to the main pump.
Why and where do you have a backflow preventer? How often should this be tested?
- They are located after the water meter to prevent contamination of the city water supply.
- We have 3- one for city water main line, one for process water, one for boiler makeup water
- Test yearly by state/city/or Cintas fire
If you had to burn oil in your boilers, could the boiler stack economizer still be used? Why?
• No. Oil does not burn clean thus causing a buildup in the stack economizer. Because the water has direct contact with stack it would affect our water quality and garment quality.
