PTAC 1302 Introduction to Process Technology Systems

Compressor System Key elements of this system include process piping, valves a compressor, a receiver, hear exchangers, dryers, back pressure regulators, gauges, & moisture removal equipment. Compressor systems are designed to produce clean, dry, compressed air/gas for industrial applications. They also transfer or compress light hydrocarbon gases, nitrogen, hydrogen, CO2, Cl, specialty gases. These gases are sent to headers from which they are distributed to a variety of applications.

Cooling-Tower System Includes a cooling tower & pipe system to transfer cooled water to the unit & back to the cooling-tower water distribution system. The cooling tower has a series of complex instrument systems to control ppm, pH, level, temperature, fan speed, and flow rate. Water from the cooling tower picks up heat and suspended solids as it flows to the operational processes. These suspended solid tend to accumulate in the basin in the internal components of the tower. These solids can change the pH and conductivity of the water system.

Electrical System It is designed to provide electricity to operate motors, lights, electric plugs, fans, computer equipment, control instrumentation, cameras, and many other areas. System composed of a boiler, a stream turbine, a main substation with transformers, a motor control center, & electrically powered equipment. Boilers provide steam that turn a steam turbine, which in turn rotates the electric generator, producing electricity. What to look out for: worn belts on motor systems, exposed wiring, smoking motors, fires, arcing, or strange electrical smells; must be reported immediately

Furnace System Typically used to heat up large quantities of hydrocarbons or chemicals. The basic equipment in a furnace system includes a furnace, advanced process control systems & instruments, pump systems, compressor systems, & fuel systems. Furnace systems support a number of other major processes such as raw material transportation and storage, utilities, distillation and reaction systems. A furnace system includes storage tanks, pumps, pipes and valve. Raw materials are brought in by pipes, trucks, ship and are prepared for introduction to the furnace through processes like desalting, heating, blending or adding special chemicals/additives. Furnaces support steam generation, distillation & mixture separation, reactors and chemical reactions, electric power generation etc.

Furnace problems Flame impingement on tubes Coke build up inside the tubes Hot spots inside the furnace Fuel composition changes Burner flameout Control valve failure Feed pump failure Incorrect temperature indicator reading, failure of oxygen analyzers, oxygen leaks, unexpected shutdown of downstream equipment

Heat Exchanger System Consist of shell in/out piping; tube in/out piping; valves; instruments; flow; temperature, analytical, & pressure control loops; & two separate pump systems. A heat exchange system includes 2/3/4 or more heat exchangers working together in series or parallel operation. Each heat exchanger has a separate tube inlet and outlet system and shell inlet and outlet system. The heating medium is usually steam, heat oil or previously heated process steam

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Pump-Around System Consists of a series of piping, storage tanks, valves, gauges, and a pump. Its important for technicians to to determine which pieces of equipment go together when developing a simple flow diagram. Using a simple pump around system, technicians can learn how to perform equipment line-ups, start-ups, operational checks and shut downs.

Steam-Generation System A complex arrangement of boiler systems designed to convert water to steam. These include pump-around systems, advanced process control systems & instruments, fuel systems, & compressor systems. Steam in useful for heating and temperature control, steam turbines, steam tracing, heat exchange, reboilers, stripping and distillation.

Steam trap-a device used to collect and transfer cooled condensate

Key tERMS Absorber: Device used to remove selected components from a gas stream by contacting the stream with a gas or liquid. Adsorber: Device (Such as a reactor or a dryer) filled with porous solid designed to remove gases & liquids from a mixture. Demineralizer: A filtering-type device that removes dissolved substances from a liquid. Extract: Composed of the solute & the heavier solvent; will layer out or naturally separate from the lighter raffinate. The heavier extract doesn’t flow over the weir; rather, it goes out the extract discharge port.

Key tERMS Extruder: A complex piece of equipment composed of a heated jacket, a set of screws or a screw, a heated die, a large motor, a gearbox, and a pelletizer. An extruder converts raw plastic material into pelletized plastics ready for further processing into finished products. Most extruders use a single- or twin- screw design surrounded by a heated barrel. The molten polymer is forced or pumped through a die. Flare system: Safely burns excess hydrocarbons a flare system is composed of a flare, knockout drum flare header, fan optional, steam line & steam ring, fuel line, & burner. Layer Out: A process in which 2 liquids that are not soluble separate naturally from each other (EX: Oil & water).

Packed Distillation Column System filled with packing to enhance vapor-liquid contact to separate the components in a mixture by boiling point. The most common types of packing include sulzer, rasching ring, flexiring, pall ring, intalox saddle, berl saddle, metal intalox, teller rosette, and mini-ring packing. The basic components of a packed column include a feedline, feed distributors, a shell, hold-down grids, random or structured packing, packing support grids, bed limiters, a bottom outlet, a top vapor outlet, instrumentation, and an energy balance system. Packed columns are designed for pressure drops between 0.20 & 0.60 inches of water per foot of packing material.

Plate Distillation Column System Has trays that are designed to enhance vapor-liquid contact in the distillation process. Plate columns may be bubble-cap, valve tray, or sieve tray. The basic components of a plate distillation column include a feed line, feed tray, rectifying or enriching section, stripping section, down comer, shell, reflux line, energy balance system, overhead cooling system, condenser, preheater, reboiler, accumulator, feed tank, product tanks, bottom line, top line, side stream, & advanced instrument control system.

Key terms (cont..) Pressure Relief System: Safety system that includes relief valves, safety valves, rupture discs, piping, drums, vent stacks, pressure indicators, pressure alarms, pressure control loops, and flare systems. Raffinate: The lighter material in the feedstock that is free of the solute or material being dissolved; flows over the weir in the separator. Refrigeration system: Used to provide cooling to industrial applications. Refrigeration units are composed of a compressor, heat exchanger-cooling tower combination, receiver, expansion valve, and heat exchanger-low-pressure refrigerant gas unit.

Key terms (cont..) Scrubber: Device used to remove chemicals and solids from process gases. Solute: Material that is dissolved in liquid-liquid extraction. Solvent: Chemical that will dissolve another chemical. Separation System: Designed to separate two liquids from each other by density differences; typically, a solvent is introduced that will dissolve one of the components in the mixture, enhancing the separation process. A separator has a shell, weir, vapor cavity, feed inlet, extract, port and pump, and raffinate port & pump. Stirred Reactor: Typically includes a vessel, a mixer, valves. piping, two or more inlet ports, and a single outlet port. Reactors are complex analytical devices that have control features for a wide array of process variables and come in a variety of shapes and designs.

SYSTEMS (CONT..) Reactor system Distillation system Separation system Pressure relief equipment and flare system Plastic system Refrigeration system Water treatment systems Utilities

Distillation system Name the stand alone systems that support the distillation system. Name the applications of a distillation system. Name the products of distillation and what they can be used for. On the distillation unit on page 231, identify and name all the equipment used in the system. What variables are measured in the system?

Plate Distillation Column System Has trays that are designed to enhance vapor-liquid contact in the distillation process. Plate columns may be bubble-cap, valve tray, or sieve tray. The basic components of a plate distillation column include a feed line, feed tray, rectifying or enriching section, stripping section, down comer, shell, reflux line, energy balance system, overhead cooling system, condenser, preheater, reboiler, accumulator, feed tank, product tanks, bottom line, top line, side stream, & advanced instrument control system.

Packed Distillation Column System filled with packing to enhance vapor-liquid contact to separate the components in a mixture by boiling point. The most common types of packing include sulzer, rasching ring, flexiring, pall ring, intalox saddle, berl saddle, metal intalox, teller rosette, and mini-ring packing. The basic components of a packed column include a feedline, feed distributors, a shell, hold-down grids, random or structured packing, packing support grids, bed limiters, a bottom outlet, a top vapor outlet, instrumentation, and an energy balance system. Packed columns are designed for pressure drops between 0.20 & 0.60 inches of water per foot of packing material.

Reactor system Reactors are designed to convert raw materials into useful products through chemical reactions. It combines raw materials, heat, pressure & catalysts in the right proportions to initiate reactions & form products. Various designs: stirred, fluidized, fixed bed and tubular. Fixed-Bed Reactor: Device in which the fixed medium remains in place as raw materials pass over it. Fluidized -Bed Reactor: Suspends solids with the reactor by countercurrent flow. Particle segregation occurs over time as heavier components fall to the bottom & lighter ones move to the top. Stirred reactor: Raw material is mixed with the reactant chemical to form a new chemical

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Absorption, stripping & scrubbing columns An absorber column is used to remove selected components from a gas stream by contracting the stream with a gas or liquid. Typically a plate/packed distillation columns. Product exchange takes place typically in one direction, vapor phase to liquid phase

The fundamental physical principles underlying the process of gas absorption are the solubility of the absorbed gas and the rate of mass transfer. One or more of the constituents of the gas mixture dissolves or is absorbed in the liquid and can thus be removed from the mixture. In some systems, this gaseous constituent forms a physical solution with the liquid or the solvent, and in other cases , it reacts with the liquid chemically. Stripping columns are used with absorption columns to remove liquid hydrocarbons from the absorption oil. Page 232

adsorption In adsorption, a device (reactor, drier) is filled with a porous solid designed to remove gases or liquids from a mixture. The adsorber can be activated alumina or charcoal or a porous substance. During adsorption, the mixture to be separated is passed over the adsorbent in the primary device. After the reaction takes place, the process flow is transferred to a secondary device, then a stripping gas is administered into the primary device. The stripping gas removes or separates the selected chemical from the adsorption material. The process switches back and repeats.

scrubber A device used to remove chemicals and solids from process gases to protect and enhance environmental quality.

As dirty gases enter the lower section of a scrubber they begin to rise. As these dirty vapors rise, they encounter a liquid- chemical wash that is being sprayed downward. As the vapors and liquids come into contact, the undesirable products entrained in the stream and removed. The dirty materials are absorbed into the liquid medium and fall to the bottom of the scrubber where they are mechanically removed. Clean gases flow out the top of the scrubber and move on for further processing.

Pressure relief equipment & flare system The system includes relief valves, safety valves, rapture discs, piping, drums, vent stacks, pressure indicators, pressure alarms, pressure control loops and flare systems. As equipment are rated for specific P and T ranges, P and T control devices ensure that these conditions are not exceeded. Pressure relief devices can be placed on pumps, compressors, tanks piping reactors etc. Because many of the materials cannot be released into the atmosphere , they are recycled back into the system or sent to a scrubber or flare system. This discharge is collected in a closed piping system and sent to a flare stack and are discharged to the atmosphere at a safe distance

Flare systems Removes excess hydrocarbons from processes. They are connected to a complex network of pipes to a knockout drum and flare. Flare systems are part of a plant safety systems. When unexpected process upsets and excess P releases occur the flare system provides safety to the system.

Water treatment system Some decades back, the CPI pumped water from underground boreholes to industrial processes. The water table dropped and land subsidence occurred. This practice was dropped. Today the CPI uses surface water (lakes, rivers, oceans) for its operations. As water enters the CPI, it is stored in large holding basins. Pumps take suction off the basins and send the water to filters for additional purification. Chemical are added to control pH and remove suspended/dissolved solids. Some filtered water is sent to demineralizers for additional treatment to remove dissolved impurities.

Process troubleshooting Data collection  organization  analysis  Check sheets  large amount of data  plotted on a graph  trend  Process variations identified.

terminology Equipment failure: Occurrence when equipment has broken, ruptured or is no longer responding to its design specification. Fail Open/fail closed: Term used in describing how a control valve ceases to work (fails) in the open or closed position Troubleshooting methods: means of diagnosing process problems. Include educational, instrumental, experiential, and scientific. Tools used to teach troubleshooting techniques. Basic models include distillation, reaction, and absorption and stripping, or combinations of these three.

The first stage is identifying the issue The first stage is identifying the issue. The second stage is performing the actual repair (or taking other steps that identifying the issue has made clear). To identify the issue, you must: Gather information. Verify the issue. Try quick fixes. Use appropriate diagnostics. Perform a split-half search (apply system knowledge to isolate the fault). Use additional resources to research the issue. Escalate the issue (if necessary). After you have identified the issue, you must: Repair or replace the faulty item. Verify the repair by testing the product thoroughly. Inform the user of what you have done. Complete administrative tasks (yes, really).

PV- Process variable, a quantity measured by an instrument (Measured Value) SP-set point: Desired value for the PV OP-Output; A signal to a device that can change the PV Overshot: When the PV moves way past the SP

DISCUSS What will happen if the reflux control valve fails to close? Column pressure? Reflux flow rate? Column top temperature? Level in D-100

What will happen if the reflux control valve fails to close? Column pressure?- stay the same Reflux flow rate? - increase Column top temperature? - go down Level in D-100 - decrease