"Words are the model, words are the tools, words are the boards, words are the nails." (Richard Rhodes)

 

PTOA Segment 74: Here ... There ... and Everywhere

Aluminum Weatherproofing Wrap: The thin silver wrap that protects pipe insulation from getting wet.

This wrap makes most of the piping in an industrial complex shiny silver and also makes the pipe diameter of the process piping look larger than it is.

Clogged Fin Fan Tubes: Fin fan tubes that are unable to transfer heat optimally due to the collection of airborne debris wedged between the fins on the external side of the tubes.

Fall leaves, blowing sand and dirt, bird poop, pollen, etc. can and do become wedged between the fins of fin fan tubes.

The fin fan must be taken out of service to clean the tubes externally.

Insulating Material: A material that greatly reduces the rate of conduction heat transfer because it increases the thickness of the physical barrier that separates a hot source from a vast, cold heat sink by adding a layer of very low conductivity material.

When wrapped around process piping, insulating material reduces the rate of heat transfer from the hot process fluid flowing through the pipe that is thence conducted through the pipe wall and into the heat sink of the atmosphere.

Insulated Pipe: A pipe that appears to be shiny silver but is really just wrapped in insulation and then covered in aluminum weatherproofing wrap for the purpose of reducing conduction heat transfer.

Other types of insulation exist which are not wrapped in silver. For example, blankets of insulation can be custom made to fit around hardware that needs routine maintenance.

Leaking Fin Fan Tubes: Fin fans tubes will leak at the tubesheet. The cause of leaky fin fan tubes is often corrosive deposits that form when upstream chemical injection rates have not been adjusted downward to match lower process flow rates.

Plugged/Sealed Fin Fan Tubes: Maintenance Department will plug leaking fin fan tubes by sealing off flow which prevents process flow from entering the leaky tube.

Fin fans are designed to cool sufficiently with a minimal number of sealed tubes. At turnaround, the entire tube will be replaced.

 

PTOA Segment 75: Still Sittin' Here Chillin'

Approach (to a Cooling Tower): The Approach provides the driving force for cooling via evaporative heat transfer; ergo, it serves the same purpose as Delta T in conduction and convection heat transfer.

Cooling Tower Approach can be calculated by subtracting the wet bulb air temperature from the temperature of the water in the cooling tower's basin.

Anti-Foulants: Chemicals that are injected into the circulating cooling water to prevent foulants from settling out on the cooling tower hardware and/or change foulants into precipitates that can be removed by filtration.

Biologic Control Chemical: Algaecides, Chlorine/Bromine (which also impact pH).

Corrosion Inhibitors: Chemicals that are injected into the circulating cooling water to reduce the rate of metal corrosion throughout the cooling water system.

Foulants: Solid materials that reduce heat transfer. The common list of circulating heebie jeebies that foul cooling water equipment include phosphates of aluminum and iron, corroded metal, organic stuff like leaves and bird poop, microbes like legionnaires virus, dirt, silt, and sand.

The source of makeup water and its conditioning significantly impacts the type and concentration of foulants.

Scale: Scale is a dense coating of mostly inorganic material like calcium carbonate,calcium phosphate, magnesium silicate, and silica.

Scale Inhibitors: Chemicals that are injected into the circulating cooling water that help control the formation of scale.

 

PTOA Segment 76: Master Plan

Capacity (of a Cooling Tower): The Capacity of the cooling tower is the volume of water the cooling tower can cool.

Natural draft cooling towers can cool a much greater capacity of water than mechanical draft cooling towers.

Chiller: The nickname for a Shell and Tube Heat Exchanger that uses cooling water as the cold side fluid (aka heat sink).

Cooling Range (of a Cooling Tower): The difference in temperature between the hot water returned to the tower and the cold water supplied to the chillers/trim coolers.

 

PTOA Segment 76: It's All Relative

Dew Point: The temperature at which the amount of water in air is at the maximum that the air can hold, ergo it begins to rain.

Otherwise stated, the Relative Humidity is at 100% at the Dew Point.

Dry Bulb Temperature: The temperature of air when measured with a normal thermometer.

Relative Humidity: The amount of water in air expressed as a percentage of the maximum amount of water that the air can hold.

The Relative Humidity depends on the air temperature; Relative Humidity is highest at low temperatures and lowest at high temperatures.

Wet Bulb Temperature: The temperature of air that takes into account relative humidity by indicating a temperature that has been cooled by evaporative cooling.

Wet Bulb Thermometer: A regular type dry bulb thermometer that has its bottom bulb wrapped in muslin that is dipped in water.

Evaporative cooling of the wet muslin by the air surrounding the thermometer causes the temperature of the Wet Bulb Thermometer to be less than the Dry Bulb Thermometer until Relative Humidity = 100%, at which point Wet Bulb Temperature = Dry Bulb Temperature.

 

PTOA Segment 77: A Day in the Life of a Shell and Tube HEx

Counter Flow HEx: A shell and tube heat exchanger which has the hot stream outlet physically located near the cold stream inlet and the cold stream outlet physically located near the hot stream inlet.

This flow arrangement makes it possible to transfer sufficient heat into the cold stream such that the temperature of the exiting cold stream can be greater than the temperature of the exiting hot stream.

Parallel Flow HEx:A shell and tube heat exchanger which has the hot stream inlet physically located near the cold stream inlet the cold stream outlet physically located near the hot stream outlet.

Although this HEx design has the greatest Delta T and therefore the greatest rate of heat transfer taking place in the inlet area, the overall amount of heat transfer is limited by the temperature of the exiting cold water which will always be lower than the temperature of the exiting hot water.

Trim Cooler: Like Chiller, Trim Cooler is another nick name for a shell and tube heat exchanger that uses water for the coolant (aka heat sink).

 

PTOA Segment 79: Goldilocks Ate the Wrong Bowl of Porridge

PTOA Segment 79 challenged PTOA Readers and Students to apply what they had learned about conduction and convection heat transfer so that the outcome of the fairy tale of Goldilocks and the Three Bears would be more thermodynamically accurate.

No additional process technology jargon appeared in PTOA Segment 79.

 

CONGRATULATIONS!

PTOA READERS AND STUDENTS HAVE COMPLETED THE PTOA HEAT TRANSFER FOCUS STUDY JARGON REVIEW!

NEXT UP:

THE LAST PTOA FOCUS STUDY AREA DEDICATED TO THE PROCESS VARIABLE TEMPERATURE RETURNS PTOA READERS AND STUDENTS TO THE BEGINNING OF THEIR PTOA LEARNING JOURNEY:

(PROCESS) TEMPERATURE MEASUREMENT!

 

©2015 PTOA Segment 00093
PTOA Process Industry Jargon Recap 3-5

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