By Tim Daly
A process plant is a factory or industrial complex that turns raw material into consumable products. This could be anything from turning Foghorn Leghorn into chicken nuggets, to refining crude oil from the Gulf of Mexico to pump premium gasoline into the old Caddy. Some process plants known as power plants, generate electrical energy by using mechanical energy. So we’ll start here at the beginning.
Raw Material is just that. Material that hasn’t had anything done to it. This could be water from a stream; fresh meat, or vegetables from the farm; newly cut logs from the forest; or ore mined from the ground, just to name a few.
Process or Processing consists of the steps taken to turn raw material into something a consumer will want to buy. It could be making soup from poultry, vegetables, water, and spices; or making a ream of printer paper from a tree, for instance.
Product is the end result of the processing or refining. It could be the box of spaghetti on the grocery store shelf, or the box the spaghetti is in on the grocery store shelf. It could also be the end result of just a part of the process. In this case, you might call the deionized water that will be used to make the steam, to spin the turbine, to generate electricity a form of product. For the power plant as a whole, the electricity is the product, but for the reverse osmosis unit removing salt and sediment from the raw water, the deionized water is the product.
Refining is the process used to make a raw material—or even a product more desirable—by adding usable material or removing unwanted material. This could be the act of adding chlorine to water in a treatment plant, or filtering lead and sediment out of the same water in your home. For most people, refining means taking crude oil and making oil based products, and that’s fine.
Energy is most generally lumped into two categories: kinetic energy and potential energy. Kinetic energy is energy in motion like a pendulum swinging, or the sound waves emanating from a speaker. Potential energy is energy that is present, but is not actually doing anything. Like a baseball sitting on the edge of a counter, or water in a still pond, as opposed to water in a river. Some power plants use the mechanical kinetic energy of steam spinning a turbine to generate electrical kinetic energy.
Now that we have discussed what a process plant is, and some of the associated terms, we can now turn our Energy towards pipefitting and defining some of the systems these plants use to churn out Product.
We have gone over Steam and Condensate in various amounts of detail in several of our past articles, so we’ll just touch a little upon it here. Steam, as we know, is the gaseous form of water. At sea level where the atmospheric pressure is 14.7psi, water boils at 212°F, and then turns to steam. When the steam temperature drops back below 212°F, it condenses back to water. We know that steam is often times the blood that brings a process plant to life.
Of course where there is steam and condensate, there are Heat Exchangers. Heat exchangers are exactly what they sound like they are.
Heat is always transferred from hot to cold, so when cold water—known as chilled water—is used to cool hot lubricating oil, the oil side of the coil isn’t absorbing cold from the water side, but the oil is losing heat because the cold water side is absorbing the heat from the warm oil side. This sounds more confusing than it really is. If you hold an ice cube, the ice melts because it is absorbing the heat from your hand. Although your hand may feel like its absorbing coldness from the cube, it is just cooling because of the heat it is losing to the melting ice. Heat exchangers are found in various fashions all over a processing plant. It could be the chilled water being used to cool oil, like in the aforementioned example, or it could be salt water being drawn from a river to cool the fresh water that heated up absorbing the heat from the oil. Or it could be the oil being used to keep machine bearings from overheating and seizing up. Heat exchange takes place when the fire burning in a boiler heats the water to generate steam, or the steam being used in a de-aerating tank pre-heating the feed water.
While discussing heat exchangers we mentioned lubricating oil. Lube oils, like heat exchangers can be found throughout processing plants. Most any machinery including pumps, air compressors, or turbines for example, use one form of lube oil or another. Large machinery, like diesel generators or steam turbines, have large lube oil sump tanks where the oil is stored and pumped from to keep areas subjected to metal to metal contact from generating too much heat due to friction. Other smaller machinery will have small oil bubblers that an operator will have to maintain and keep full, or even a small inlet port where an operator can periodically add a few drops of lube oil. It is important to ensure that if a particular machine calls for a particular oil, that only the specified type of oil is used.
Another prevalent system among most processing plants is instrument air. This system uses air compressors to compress atmospheric air to operate pneumatic valves and components throughout the plant. Compressed air is also used for utility air, which is used for operating pneumatic tools like grinders or impact wrenches.
Co-Generation is a term that has been around for a long time, but with today’s rising fuel costs, more and more companies are investigating co-generation and heat recovery options. For instance, a power plant will use steam to turn steam turbines to generate electricity. After the steam goes through the turbine, much of it hasn’t condensed, and what’s left over can then be used to heat a campus during cold weather, or for steam irons in a dry cleaning business. Using the left over steam is a form of heat recovery, and the plant is then considered a co-generation facility, because it is generating electricity to be used for one application and also steam to be used for another application.
Nearly everything goes through some sort of processing before consumers get a hold of it, and for pipefitters that’s a good thing, because where there’s processing, there’s processing plants, and where there’s processing plants, there’s piping systems, and where there’s piping systems, there’s pipefitters.