First vehicle arrived for our new fleet.
We were having a new refrigerant monitor system installed in the plant and the service tech asked where the breakers were located for the two areas he was was installing the equipment. Locating the one for the main monitor was easy, everything was marked. The remote monitor wasn’t that clear cut. After locating a panel I saw a breaker marked flow meter. We used to have a city water pressure monitor installed where the new remote monitor was being mounted, so I switched it off. Bad idea. it shutdown the boilers! While I was trying to get the boilers back online, the service tech come by and said he didn’t need the breaker off, he installed while the circuit was live. A plant shutdown, switching a 20 amp breaker off, wasn’t required. I hate when these incidents are self induced. Oh, the breaker was for the steam flow indicators.
Make sure your MCC breakers are clearly marked before experimenting to find the right one.
Received this delivery the other day in the plant…..
I don’t think the pallet is big enough.
Cooling Tower Terminology
Approach – difference between cold water temperature and the measured wet-bulb temperature.
Bleed Off – is the circulating water in the tower which is discharged to waste to help keep the dissolved solids concentration of the water below a maximum allowable limit. As a result of evaporation, dissolved solids concentration will continually increase unless reduced by bleed off.
Blowdown – water intentionally discharged from the cooling system to control concentrations of salts and other impurities in the circulating water
British Thermal Unit (BTU) – the heat energy required to raise the temperature of one pound of water one degree Fahrenheit in the range from 32° F to 212° F
Cell – smallest tower subdivision which can function independently
Cold water temperature – temperature of the circulating water leaving the cooling tower
Counterflow tower – design in which air flows upward through the fill section and interfaces counter currently with the down coming hot water.
Crossflow tower – design in which air flows horizontally across the fill section and interfaces perpendicularly with the falling hot water
CTI – Cooling Tower Institute. Organization for testing and certification of cooling towers
Cycles of Concentration – compares dissolved solids in makeup with solids in the circulating water
Drift – water lost from the tower as liquid droplets entrained in the exhaust air stream
Drift eliminators – baffling to control the drift loss in towers
Heat load – heat removed from the circulating water within the tower
Makeup – water added to the circulating water to replace water lost from the system by evaporation, drift, blowdown and leakage
Mechanical draft tower – tower in which a fan moves the air through the fill
Natural draft tower – hyperbolic design in which air moves through the fill because of pressure difference between top and bottom of tower, creating a chimney effect
pH – number between 0 and 14 indicating degree of acidity (below 7) and alkalinity (above 7)
Pumping head – minimum pressure required to lift water from basin level to tower top and force it into the water distribution system
Recirculation air – portion of the exhaust air which reenters the tower measured on the basis of the increase in entering wet-bulb temperature compared to the ambient
TDS – total dissolved solids contained in solution in cooling system water
Ton – an evaporative cooling ton is 15,000 Btu / hr
Water loading – circulating water flow expressed in gal / min per square foot of effective horizontal wetted area of the tower
Wet-bulb temperature – temperature indicated by a psychrometer
This is the formula used to calculate the heating surface of a power plant boiler:
An HRT boiler is 5 ft in diameter and 16 ft long. It contains 60 tubes of 3 inch outside diameter and 2.732 inch inside diameter. Find the boiler-heating surface. Take the inner surface of tubes, half of the shell surface, and two-thirds of the tube plate area, less the area of the tube holes.
Circumference of shell = 5 * 3.14 = 15.700 ft
Half circumference of shell = 15,700 * ½ = 7.850 ft
Area of half of shell = 7.850 * 16 = 125.60 sq. ft
Inner circumference of fire tube = 2.732 * 3.14 = 8.578 in or 8.578 / 12 = 0.7148ft
Surface of one tube = 0.7148 * 16 = 11.437 sq. ft
Surface of 60 tubes = 60 * 11.437 = 686.2 sq. ft
Total area of one tube sheet = 0.785 * 5 * 5 = 19.625
Two-thirds area one tube sheet = 2/3 * 19.625 = 13.083 sq. ft
Area of one tube hole = 0.785 * 3 * 3 = 7.065 sq. in
Area of 60 tube holes = 60 * 7.065 = 423.9 sq. in or 423.9 / 144 = 2.94 sq. ft
Net heating surface of one tube sheet = 13.08 – 2.94 = 10.14 sq. ft
Net surface of two tube sheets = 10.14 * 2 = 20.28 sq. ft
Total net area = 125.60 + 686.2 + 20.28 = 832.08 sq. ft
832 sq. ft