Covers water treatment approaches including: separation and purification—end of discharge pipe; zero discharge approach; flow management approach; and preservation and control approach Discusses water treatment process selection, trouble shooting, design, operation, and physico-chemical and treatment Discusses industry-specific water treatment processes.
Hands-on troubleshooting methods on the most recent release of SQL Server The release of SQL Server is the most significant one since and introduces an abundance of new features.
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Process Equipmen t is designed to teach readers about equipment used in the process industries. This book includes a variety of topics including, valves, tanks, pumps, turbines, motors, heat exchangers, cooling towers, furnaces, boilers, separation equipment, reactors, filters, dryers and solids handling equipment. Readers will find this book to be a valuable resource throughout their process technology career.
Pearson Publishing and the Center for the Advancement of Process Technology CAPT have partnered to publish a series of textbooks designed to aid in the education and development of technicians in the field of Process Technology. These texts, which are based on a set of nationally identified objectives, are designed to address the core needs of both industry and education.
Process Technology Instrumentation is a 24 chapter, two-semester textbook, intended for use in community colleges, technical colleges, universities and corporate settings in which process instrumentation is taught. This text includes a variety of topics including control loops, symbology, troubleshooting, and safety systems. Educators in many disciplines will find these materials a complete reference for both theory and practical application.
Students will find this textbook to be a valuable resource throughout their process technology career. Also available from Pearson Publishing and CAPT Introduction to Process Technology -- An overview of various process industries, basic chemistry, basic physics, safety, health, environment, and more.
Safety Health and Environment - Covers a wide range of topics including the environment, cyber security, safety-related equipment and more. What is the purpose of a cooling tower? What are equipment checklists primarily used for? Describe chain and belt drives.
Identify the basic components of a gate valve. Identify the basic components of a globe valve. Explain the operation and design of a ball valve. Identify the basic components of a check valve.
Describe the design and operation of a butterfly valve. Examine the design and operation of a plug valve. Describe the design and operation of a diaphragm valve. Describe the design and operation of a relief valve and a safety valve.
Describe the design and operation of automatic valves. Actuator—a device that controls the position of the flow-control element on a control valve by automatically adjusting the position of the valve stem. Antiseize compound—lubricant used on exposed valve stem threads. Ball valves—named for the ball-shaped, movable element in the center of the valve. Block valve—any valve that is intended to block flow; also called an isolation valve. The term generally refers to gate valves.
Bonnet—a bell-shaped dome mounted on the body of a valve. Bridgewall markings—manufacturer information on the body of a valve. Butterfly valves—characterized by their disc-shaped flow-control element, which pivots from its center.
Check valves—mechanical valves that prevent reverse flow in piping. Control loop—a collection of instruments that work together to automatically control a process; usually consists of a sensing device, a transmitter, a controller, a transducer, and an automatic valve. Control valves—automated valves used to regulate and throttle flow; typically provide the final control element of a control loop.
Diaphragm valve—a device that uses a flexible membrane to regulate flow. Disc—a device made of metal or ceramic that fits snugly in the seat of a valve to control flow. Flange—a device used to connect bolt piping to industrial equipment. Flow-control element—the part of a valve that regulates flow; that is, the gate or the disc. Fluid—of the three forms of matter—solids, liquids, and gases—liquids and gases are considered fluids. Gate—the flow-control element of a gate valve.
Gate valve—a device that places a movable metal gate in the path of a process flow. Globe valve—a device that places a disc in the path of a process flow. Handwheel—attached to the valve stem and used to control the position of the flow-control element of a valve. Packing—a specially designed material used to stop fluids from entering or escaping; packed around the shaft stem of a valve, or shaft of a pump.
Packing gland—a mechanical device that contains and compresses packing. Stem—a metal shaft attached to the handwheel and flow-control element of a valve.
Stuffing box—the section of a valve that contains packing. Three-way valve—a valve with three ports one inlet and two outlets used to divert flow direction. Throttling—reducing or regulating flow below the maximum output of a valve.
Trim—the flow-control element and seats in a valve. Valve capacity—the total amount of fluid a valve will pass with a given pressure difference when it is fully open.
Valve Applications and Theory of Operation Process plants are a network of complex systems and processes. Just as arteries, veins, and the heart are vital to human life, pipes, valves, and pumps are indispensable in a process plant. The primary purpose of a valve is to direct and control the flow of fluids by starting, stopping, and throttling restricting flow to make processing possible. Valves are designed to withstand pressure, temperature, and flow and can be found in homes and industry across the world.
The common valves Figure 2. Valves normally are selected for a specific purpose. As you continue to read through this chapter, you will notice the variety of valve designs that exist. Operators need to be aware of how each valve works and the specific service for which it was designed. Classification of Valves Process operators classify valves by 1 flow-control elements, 2 function, and 3 operating conditions such as pressure, flow, or temperature.
This part of the valve controls or regulates the flow of fluid through the device. Some valves have movable metal gates, balls, plugs, diaphragms, discs, needles, or even butterfly-shaped elements.
Most valves are named for the type or design of the flow-control element. Valves that are used for isolation are classified as block valves. While gate valves are the most common valve used for isolation, any valve can be used for this type of service.
Another term associated with valve operation is valve capacity. Valve capacity is a term used to describe the total amount of fluid a valve will pass with a given pressure difference when it is fully open. Bridgewall Markings The body of the valve contains bridgewall markings, which provide manufacturer information specific to the valve.
Gate Valves One of the more common valves found in industry is a gate valve. A gate valve places a movable metal gate in the path of a process flow in a pipeline. The gates are sized to fit the inside diameter of a pipe, so very little restriction occurs when it is in the open position. Valves vary in size from 0. This type of valve is used where flow 26 Gate Valves Figure 2. Gate valves should not be used to throttle flow for extended periods.
Turbulent flow rates across the valve body will cause metal erosion, seat damage, and damage to the flow-control element, which can prevent the valve from blocking the flow completely. The seats in a gate valve fall into two categories: replaceable and fixed. Smaller valves typically have fixed or cast seats because it is easier and more cost efficient to replace the valve than to replace the seats.
In most cases, a gate valve has two vertical seating surfaces. The edges of the seats match up with the parallel discs or wedge.
The typical gate valve consists of a gate, body, seating area, stem, bonnet, packing, stuffing box, packing gland, and handwheel Figure 2. The gate can be wedge shaped or may consist of parallel discs.
It can be composed of a variety of materials. The gate is placed directly in the path of a process flow when it is shut and is lifted completely out of the way when open. The body is the largest part of the valve. The body can be connected to the process piping in three ways: flanges, threaded connections, or welding. The rest of the valve is attached to the body.
The seating area consists of two fixed surfaces or rings inside the body of the valve that the gate closes against to stop flow. The seating area falls into two categories: replaceable or fixed. Seats must provide a clean mating surface for the gate to seal properly. The seat can be fabricated or cast as part of the valve, press-fit, threaded, or welded into place. Note that high-temperature and high-pressure situations may require a combination of threading and welding.
The stem is a long, slender shaft attached to the gate, bushing, or wheel. When the handwheel is turned, it transmits rotational energy to the stem, causing it to rise to open or lower to close.
It is attached to the body permanently by welding or temporarily by threading or bolts. The packing is a specially designed material that prevents leakage from the bonnet, yet allows the stem to move up and down smoothly. The stuffing box is typically located where the stem goes through the bonnet. The stuffing box is a recessed area specially designed to allow packing to be mounted around the stem.
The packing gland is a device used to compress and secure the packing material into the stuffing box. The packing gland nuts are designed to be evenly tightened by a technician to stop leaks. The handwheel is attached to the valve stem. The handwheel transfers rotational energy to the stem. This rotational energy controls the movement of the flow-control element. Turning the handwheel clockwise closes the valve.
When the handwheel is turned counterclockwise, it is opened. Common Gates The gate on a gate valve comes in a variety of shapes and sizes. The most common designs include the solid wedge, solid split gate, and parallel discs Figure 2. The solid wedge gate forms a positive seal when the solid metal gate slips into the seat.
A set of guides keeps the disc aligned. Because the solid wedge gate is designed to fit snugly into the seat, it should never be overtightened. Excessive force will damage the seats, so the technician should shut the valve until it seats and then back off slightly.
The solid split gate forms a positive seal when the split metal gate slips into the seat. The solid split gate is designed like the solid wedge but has Figure 2. The split, nonjamming feature lets this type of gate handle higher temperatures than the solid wedge.
Fluid pressure is used to seat this type of gate. The parallel, or double, discs gate is composed of two separate discs mounted to a shaft.
Some parallel discs have a spring located between the two discs, whereas others are attached to a solid metal core. The double discs gate valve is designed for high-temperature service because of its nonjamming design. As fluid enters this type of valve, it pushes against one of the discs, compressing the spring or flow-control element and forcing the opposite disc snugly into its seat. System pressure helps position the gate in its seat. The higher the pressure, the more tightly the disc fits into the seat.
Gate Valve Materials Gate valves Figure 2. The specific condition dictates what type of material the valve will be made of. For example, stainless steel gate valves are used in corrosive, high- and low-temperature services.
Specialty alloy gate valves are used in high-temperature, high-pressure service. Bronze gate valves are used in low-temperature, low-pressure service. Brass gate valves are used in low-temperature, low-pressure service.
Cast iron gate valves are used in water, lubrication, and some low-pressure steam services. Figure 2. It is not uncommon to find gate valves that have not been operated for many years. Rising Stem and Nonrising Stem The stem on a gate valve comes in two designs: rising stem and nonrising stem. Located at the top of the gate valve is the handwheel.
The handwheel is attached to a bushing, which is attached to the threaded stem. As the handwheel is turned counterclockwise, the stem in the center of the handwheel rises. As the stem rises, the gate is lifted out of the valve body, allowing fluid to flow. A process technician can look at this type of valve and tell if it is open or closed by checking the position of the stem. Another type of rising stem valve is threaded at the bottom of the stem.
In this type of valve, the handwheel is firmly attached to the stem and rises with it as the valve is opened. A nonrising stem gate has a collar that keeps the stem from moving up or down. The handwheel is attached firmly to the stem of a nonrising gate. Turning the handwheel screws the stem into or out of the gate. You cannot look at this type of valve and tell if it is open or closed. Valve stem threads exposed to weather need to be lubricated with antiseize compound to keep them operating properly.
The packing should be inspected, and the gland nuts tightened evenly if a leak is found. Valve stems should not be painted, and every effort should be made to keep them free of dirt and dust. When closing a gate valve, the operator should take care not to damage the valve seats. Temperature changes, closing a valve too quickly, and pipe expansion can cause a valve to warp. Because warping can cause a valve to stick, the process technician should close valves slowly.
When the gate is on the bottom, a wrench should never be used to snug it down. Many valves have grease fittings, which admit lubricant to moving parts. Process technicians routinely inspect, clean, and lubricate valves. Globe Valves Globe valves are the second most common valves used in industry. A globe valve places a movable metal disc in the path of a process flow. This type of valve is most commonly used for throttling service.
Globe valves must be installed properly to work efficiently. If the valve is installed backward, it will tend to wear unevenly and push the flow-control element down. The disc is attached to the stem in three ways: slip joint, threading, or onepiece manufacturing. The disc can be classified as plug, ball, composition, or needle shaped. It is composed of a variety of materials. The disc, or flow-control element, rests in the seat, directly in the path of a process flow when it is shut. Unlike the gate valve, the globe valve is designed to be used for throttling.
Flow can be regulated by the percentage of opening of the flow-control element. The body can connect to the process piping in three ways: flanges, threaded connections, or welding. The seating area comes in four designs: cone-shaped, beveled flat surface, O-ring or washer, and tapered or needle-shaped cone. The seating area is where the flow-control element closes against the body of the valve to stop flow.
The seating area can be replaceable or fixed. Seats must provide a clean mating surface to the flow-control element to seat properly. High-temperature and high-pressure situations may require a threading and welding combination. The stem is a long, slender shaft attached to the disc, bushing, or wheel. Turning the handwheel transmits rotational energy to the stem. Packing is a specially designed material that prevents leakage from the bonnet yet allows the stem to rotate evenly.
The packing gland nuts are designed to be evenly tightened by an operator to stop leaks. The back seat is a device used to provide a seal between the stem and the bonnet and to protect the packing from excess pressure inside the valve.
It is used in steam service. The back seat is manufactured as part of the stem. When the stem is in the full-open position, the disc-shaped back seat firmly connects with the mating surface of the bonnet seat. Four Common Disc Designs The disc on a globe valve comes in a variety of shapes and sizes. The four most common designs are plug, ball, composition, and needle Figure 2.
The plug-type disc is used for throttling. It is equipped with renewable seat rings on a cone-shaped mating surface. It is the best device for throttling and in situations with wide temperature and pressure variations. The ball element seats against a beveled, ball-shaped, or flat surface. The composition disc can be adapted for use with a variety of temperatures and flow rates. The composition disc is renewable. Mating surfaces use a rubber O-ring or washer.
The needle disc is used for microthrottling service. Globe Valve Materials Globe valves are designed to be used in a variety of process conditions. The specific condition dictates the type of material the valve will be made of. For example, the stainless steel globe valve is used in corrosive, highand low-temperature services.
The specialty alloy globe valve is used in high-temperature and high-pressure services. Some common alloys used are nickel and iron or steel and titanium. The bronze globe valve is used in low-pressure and low-temperature systems. The brass globe valve is used 32 Globe Valves Figure 2. The cast iron globe valve is used in water lubrication and some low-pressure steam systems.
When compared to gate valves, globe valves Figure 2. Globe valves are designed to be installed in high-use areas. If a globe valve is installed in a low-use area, it tends to plug up even though it has a self-cleaning type design. Unlike the gate and globe valves, a ball valve does not lift the flow-control device out of the process stream.
Instead, the hollow ball rotates into the open or closed position. Ball valves provide very little restriction to flow and can be fully opened with a quarter turn on the valve handle. Ball valves come in a variety of shapes and sizes Figure 2. Larger valves require handwheels and gearboxes to be opened but only require one-quarter turn on a handle.
Ball valves should not be used for throttling service. During prolonged exposure, the ball seats and ball can be damaged, stopping the valve from sealing properly. Typically, ball valves are not designed for excessive temperatures.
The seats are made of a plasticcoated material that tends to break down under high temperatures. Process technicians should be familiar with the temperature specifications of the valves. Ball valves do not generally seal as well as globe valves in high-pressure service. Some ball valves multiport valves are designed with multiple ports, so an operator can switch fluid sources without stopping flow. The check valve limits backflow but is not considered a tight shutoff.
Check valves come in a variety of designs and applications. Check valves have flow direction stamping on the valve body. A typical check valve design is the swing check, which has a hinged disc that slams shut when flow reverses Figure 2. Flow lifts the disc and keeps it lifted until flow stops or reverses. The body of the check valve has a cap for easy access to the flow-control element. Another design is the lift check, which has a disc that rests on the seat when flow is idle and lifts when flow is active Figure 2.
Special guides keep the disc in place. Like the swing check, it is designed to close when flow reverses. Lift checks are ideal for systems in which flow rates fluctuate.
The lift check is more durable than the swing check. In the horizontal or vertical lift check design, a piston or ball is lifted up and out of the seat by process flow. A third design is the ball check design, which has a ball-shaped disc that rests on a beveled, round seat Figure 2. The ball is down when flow is idle and up when flow is active. Special guides keep the ball disc in place. Ball checks are ideal for systems in which flow rates fluctuate or the fluid contains some solids.
The ball check is as durable as a lift check and more durable than a swing check. A fourth design is the stop check design, which has characteristics of a lift check and a globe valve Figure 2. In the closed position, the stop check disc is firmly seated. In the open position, the stem rises out of the body of the flow-control element and acts as a guide for the disc.
In the open position, the stop check functions like a lift check with one exception. The degree of lift can be controlled. Ball, lift, swing, and stop checks come in horizontal and vertical designs. Check valves are designed to be used in a variety of process conditions. For example, the stainless steel check valve is used on corrosive, highand low-temperature services.
The specialty alloy check valve is used in high-temperature and high-pressure services. The bronze check valve is used in low pressure and low temperature Figure 2. The brass check valve is used in low pressure and low temperature. The cast iron check valve is used in water lubrication and some low-pressure steam services.
The body of this type of valve is relatively small when compared with other valves and, therefore, occupies much less space in a pipeline. The flowcontrol element resembles a disc. A metal shaft extends through the center of the disc and allows it to rotate one-quarter turn Figures 2. A one-quarter turn is all it takes to fully open or close the valve.
During a throttling operation, a butterfly valve handle should be carefully secured. As flow enters the body of the valve, it contacts the disc and will cause it to open if the handle is not latched into position.
Butterfly valves are used for throttling; however, it should be noted that they have nonuniform flow characteristics. Fifty percent open may provide near-maximum flow. Butterfly valves are designed to be operated at low temperature and low pressure. They are commonly found in cooling water and heat exchanger systems throughout the process industry. The seats in a butterfly valve can be made of natural gum rubber or suitable plastics.
Plug Valves Quick-opening, one-quarter turn plug valves are very popular in the process industry. The plug valve takes its name from the plug-shaped flowcontrol element it uses to regulate flow Figures 2.
In the open position, the port lines up with the inner diameter of the pipe. Plug Valve Design Plug valves come in a variety of shapes and sizes. In low-temperature service, the seats are made of a plastic-coated material that tends to break down during higher temperatures. Maintenance With proper care and maintenance, a plug valve can last indefinitely. Lubrication plays a big part in the life of a plug valve.
Plug valves depend on a lubricant inside the body of the valve. This lubricant helps the valve provide a leak-free seal. A plug valve should never be used for throttling.
Diaphragm Valves In a chemical plant, a variety of slurries, corrosive or sticky substances, are transferred from place to place. Standard valves would have a difficult time with this type of product, but diaphragm valves are specifically designed for the job. Diaphragm valves use a flexible membrane and seat to regulate flow. Checking Your Knowledge questions have been updated to better complement chapter objectives.
Practical, on-the-job applications The new edition dives deeper into key applications such as formulas for use with processes, standards, sizing, and testing. New content expands on descriptions of materials such as piping, materials of construction, filters, and dryers, plus federal regulations and tables for quick reference.
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The materials in this text are the foundation topics for operator training. This is the approach taken in the fourth edition of Process Technology: Equipment and Systems. Recently, the industry has noticed a sharp increase in the number of women choosing process technology as an occupation.
This text provides a balanced foundation for the rich diversity of students choosing to prepare for occupations in the chemical processing industry. This includes a much younger group of adult learners who will need to take the place of the baby boomer generation, as people from the latter retire in massive numbers. As with the previous three editions, Process Technology: Equipment and Systems empowers the adult learner to accomplish the learning process.
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