Unit 12 Typical Industrial Plant Configurations Flashcards
Steam is the principal energy transfer medium that industry depends on for its process applications. It provides energy for process
Heating, pressure control, mechanical drives, electrical generation and component separation
Advantages of steam
Low toxicity, transportability, high efficiency, high heat capacity and low acquisition and production costs
Most of the heat contained in Steam is in the form of
Latent heat
Heat transfer fluid systems (HTF) - hot oil
Industrial Systems were a special heat transfer fluid, not water, is circulated by a pump through a fired heat exchanger.
HTF systems may be preferred when the temperature is above
175°C
Steam is generated in a boiler by
Transferring thermal energy released in a heat generating process, into liquid water. The additional energy carried by the steam is transferred out of the steam by thermal or mechanical action
Generation
3 heat conversion mediums
HTF, Compressed Gas, Steam
The efficiency of distribution is affected by
Thermal insulation, piping and component separation Technologies
Steam accumulators
Allow the additional energy in excess steam to be discharged into a pressure vessel partially filled with water
During system startup, steam traps allow
Air in equipment and lines to escape
Examples of end use processes
Process heating, mechanical Drive, electrical generation, enabling chemical reactions, fractionation of hydrocarbon components
Two types of processes
Physical and chemical
Absorption process
Absorbing agents called molecular sieves, are used as a filtering medium. The medium separates on the basis of physical size of molecules being different
Crystallization process
A crystalline substance is separated from a non-crystalline one by cooling the solution, and separating the components via a separating process such as filtering or centrifugation.
Dilution
Steam is often used to dilute a process gas which can reduce solid buildup on heat exchangers
Distillation/fractionation
During distillation, usually in a fractionation tower, compounds are separated into fractions by differential boiling points.
Process of drying or evaporation
The vaporization and removal of water or other liquids from a solution
Process quenching
Used to cool and thus stop High temperature reaction processes
Solvent extraction
Separation process which separates substances by using differences in solubility between compound in complex mixtures
Stripping Towers
Steam pulls unwanted contaminants from a process fluid and directs them to waste or back into the process
Thermo-mechanical
Direct conversion of thermal energy into mechanical action, which occurs in the final stages in industrial plants
Thermo-mechanical pulping (TMP)
Direct conversion of mechanical action into thermal energy
Chemical conversion process
Converts one compound into another by chemical reaction. Involves chemical manipulation of molecular size or chemical structure
Molecular size reduction
Involves converting a surplus of unsaleable product with a large molecular size into a smaller one that is in demand
Chemical structure adjustment
Rearranges the chemical structure of a compound or mixture to create a different product, or to improve performance in the product.
A hot oil system is one that uses
Oil as a thermal fluid, in place of steam or water, to transfer heat from a central source to other areas of the plant. Consists of a heat source and piping to distribute the heated oil and return the cooled oil. Heat exchangers transfer the oils heat to other fluids and the pump to create and maintain required circulation
A hot oil system is very much like a hot water heating system, but the difference being that
The fluid chosen has a much higher boiling point than water and the Steam runs at a higher temperature. So, heat transfer fluids exhibit a much lower vapour pressure than Steam.
Heat transfer fluids, especially hot oils are widely used in
High temperature processes, where low pressures are preferred
HTF vapour is generative at higher temperatures but
Exhibits lower pressures
The Vapor phase heat transfer system has even and constant
Heating temperature and the temperature difference between Inlet and Outlet of heat can be controlled within a 1-2°C range.
Vapor systems can be used if higher temperatures and heat transfer rates are required but
They are generally more expensive and complex than liquid systems.
Heat transfer fluids will degrade over time in
Elevated temperatures and oxidized if in contact with atmospheric air.
Many heat transfer fluids have relatively High
Coefficient of thermal expansion
Heat transfer fluids are non corrosive, and any corrosion problems within the system are usually caused by
Contaminants such as cleaning fluids left in the system at startup or leakage of process fluid in the system
The operating range between efficient operation and the point at which degradation of the oil occurs
20-30°C difference
Although heat transfer fluids have high flash points, the system almost always operates
Above the flash point
Liquid thermal systems generally consists of
A pump, fired heater, and expansion tank to allow for expansion and contraction of hot oil as it heats up and cools down
Three classes of heaters used in HTF systems
Radiant, convection and a combination of the two
Radiant heaters
Combustion gases do not flow across tube surfaces. Heat is transferred from the burning fuel to the tubes by radiation from the furnace space. Low efficiency (40-50%)
Convection heaters
Combustion gases flow across the tubes, heat is then transferred by conduction through the tube to the hot oil flowing in the tubes. Higher efficiency (75-85%)
Combination radiant and convection heaters
Favoured due to their efficiency in larger unit
Updraft fired heater
Radiant and convection tube sections
When operating the expansion tank, the tank level should be between _______
The temperature in the tank should be less than _______ to prevent fluid oxidation
2/3 and 3/4
60°C
Two pumps are usually installed in a hot oil system;
One operating and the other on standby
In order to maintain the standby pump at operating temperature _______
The suction valve of the standby pump should be left open all the time to allow a small amount of oil to flow backwards through the pump.
Hot oil pump should be located
At a level below the expansion tank to provide necessary static head to avoid possible cavitation in the pump suction
Two pumps used for liquid thermal systems
Usually a centrifugal pump, but sometimes gear pumps are used
Petroleum refinery
Complex plant that contains several individual process plants. Each plant has a specific function
The overall goal of a refinery
The separation of hydrocarbon components in the crude oil and modification to maximize production of high demand products.
Gasoline boils within the range of
30 - 300°C
Examples of number 1 oils
Gasoline and kerosene
Distillate fuel oil
Distillable hydrocarbon liquid mixtures of lower volatility than kerosene. Number 2 oil
Residual fuel oil
The material remaining as an evaporated liquid from distillation or cracking processes. Used mainly as boiler fuel and ocean-going ships. Number 6 oil or bunker C
Aviation jet fuel
Blended grades of petroleum distillate suitable for use in jet engines. Have high stability, low freezing point and overall High volatility
Petro chemical feedstock
Refinery products having low molecular mass and high purity.
Examples of petrochemical feedstocks
Ethane, ethylene, propylene, acetylene, butane, butadiene, benzene
Crude petroleum
Mixture of hydrocarbon molecules of many different sizes and shapes.
The boiling point of hydrocarbons increase with
The number of carbon atoms
The first processing stage in a refinery separates fractions by
Boiling point ranges. Separates crude oil into fractions by increasing the boiling point. It is heated to vaporize it, and then the vapour is cooled gradually. As the vapour cools, heavier molecules condense first and are removed. Usually done in fractionating or distillation Towers.
The second stage in the refining process
Convert separated fractions into various product streams. Involves additional separation and processes that alter the molecular structure, like Hydrotreating, cracking, forming and alkylation
Once the products are formed,
They are further processed to remove undesirable contaminants like sulphur and carbon dioxide. Raw products are then Blended and additives are introduced to produce desired products.
Before entering the separation and chemical reaction processes, crude oil must first be
Heated. Initially with a heat exchanger, then a furnace.
After heating, the crude oil enters the
Distillation column. The crude separates into liquid and Vapor. Vapor Rises up the column, up the trays, as it bubbles through the barrier “bubble cap”. The liquid filled up the tray and flows into a secondary distillation column “stripper column”.
Stripper column
Injects the steam into the fraction to extract Vapor which travels with the stripping steam back into the main column.
Lighter hydrocarbons, which are recovered of the lowest temperatures;
Butane and liquid petroleum gases, gasoline blending components, naphtha
Mid temperature range products
Jet fuel, kerosene and distillates
Heaviest products
Residual fuel oil, recovered at temperatures sometimes over 530°C
Additional stages of processing
Hydrotreating, reforming, catalytic cracking and alkylation
Three groups of petrochemical feedstocks
Olefins, aromatics, synthesis gas (syngas)
Olefins
Doubly bonded carbons. Includes; ethylene, propylene and butadiene. Produced in the cracking process assisted by Steam
Aromatics
Includes benzene, Toluene, xylenes. Produced in the reforming process
Synthesis gas (syngas)
Mixture of CO and H2. Produced in lean combustion or steam reforming.
Steam generation Powers much of the refinery, so it is generally
The first system to start up and the last to shut down.
Most plants operate at least three distinct steam systems;
High pressure, medium pressure and low pressure. Systems are interconnected through let down, or pressure reducing stations, which exhaust the high pressure system to the medium system and the medium pressure system to the low pressure system.
High pressure steam system range
Low pressure steam system range
4130 - 10 340 Kpa
103 - 415 Kpa
Stripping Steam
Steam is injected into sidestream stripping columns to facilitate the movement of light products up the column. Injected steam carries the lighter hydrocarbons out of the stripper column and back into the main fractionating tower.
The most common method of heat tracing flow lines, valves, metres and Recorders is to use
Steam
Steam stations
Used in Refinery units, so technicians can hook up a steam hose to thaw frozen equipment and lines
Purging equipment with steam
Effective method of preparing a Refinery hydrocarbon unit for turn around. Cleans equipment and Towers in preparation for vessel entry.
Canada’s oil sands produce a heavy oil typically referred to as
Bitumen. The upgrading process for this oil converts bitumen into a high-quality, Light, low sulphur crude oil.
Bitumen diluted with naptha cut as a mixture is called
Dilbit
The first step in the upgrading process of dilbit is to remove
The naturally occurring light gas oil component and to recover the diluent naphtha. This is done in the diluent recovery units
Light gas oil stream is sent to
Hydro treaters, the diluent naphtha is recycled to the extraction plant and the bottoms of the atmospheric topped bitumen is fed to the vacuum distillation unit with a large amount going directly into the conversion units. The unit removes all remaining light and heavy gas oils, directing the streams to the hydrotreaters.
After distillation of naphtha, light gas oil, and heavy gas, oil streams are sent to
Their own hydrotreater to remove sulphur and nitrogen by adding hydrogen. The resulting products from each of the separate Hydrotreaters are then combined to produce synthetic crude oil.
The residue stream from the atmospheric distillation Tower is further separated into two streams
Heavy vacuum gas oil and vacuum residue.
The heavy vacuum gas oil is mixed with
The heavy gas oil from the atmospheric distillation Tower to undergo hydrotreating.
The vacuum residue is
Further upgraded either in a hydro converter by adding hydrogen or in a Coker to produce lighter liquid product and by-product Coke.
The lighter liquid product from the hydro converter or Coker
Further separated into naphtha, light gas oil, and heavy gas oil by distillation. The final products from the upgrading facility are synthetic crude oils and Coke
Fluid cokers.
Thermal conversion units that crack long-chain bitumen molecules into more valuable short-chain molecules - heavy gas oil, light gas oil, and naphtha.
Hydrotreater units
Operate at high pressure to treat the product and remove sulphur, nitrogen, and other impurities.
Bitumen is found in
Geological formations mixed with sand, called oil sands. Bitumen is so heavy and viscous that it will not flow without first being heated.
Two common methods of extracting and descending heavy crude bitumen
Steam assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS)
When the bitumen is found too deep for the economical application of surface mining,
SAGD and CSS are used
SAGD and CSS work by
Reducing the viscosity of the bitumen, so it can flow to the surface.
SAGD
Because once through steam generators (OTSG) generate wet Steam,
Separators are installed in the steam lines to dry the steam to nearly 100% dry and saturated. The saturated steam is piped to a number of wellheads through injection Wells. Vertical section of underground piping maybe around 500m in length
SAGD
Once in the oil sands formation, the injection well piping continues
For another 700 to 1000m. Horizontal piping is slotted along its length, to distribute steam evenly.
SAGD
When the injected steam condenses,
It gives off its latent heat to the surrounding bitumen. The high temperature steam reduces the bitumen viscosity, allowing it to flow. The steam mixes with the bitumen to form an emulsion, which is extracted through Wells drilled adjacent to, and about 5m below, the injection wells. (Producer wells)
Emulsion
Mixture of oil, water, and gas
CSS and SAGD
Similarities and differences
Both use OTSG to supply high temperature, high pressure steam for injection into oil sand formations. Both heat the bitumen to allow it to flow to the surface.
SAGD is a continuous recovery process, whereas CSS takes place in the stages or Cycles
CSS
first stage (injection stage)
High pressure and temperature wet steam, around 320°C, is injected into vertical wellbores
CSS
second stage (soaking stage)
Steam is allowed to soak through the oil sands, melting the bitumen
CSS
Production stage
Steam is shut off and the resulting bitumen and water emulsion is brought to the surface through the same wellbore
CSS
The cycle is repeated
Many times, upwards of 15 Cycles on each well, until the reservoir bitumen is depleted. Each cycle of this process can take from 4 months to two years
CSS is not used for
Shallow reservoirs, because they do not have a thick shale cap which is needed to contain the high injected steam pressure.
CSS is superior to SAGD at extracting bitumen when ________
Oil sand reservoirs are deeper
In both SAGD and CSS, the emulsion returning from the producer Wellhead contains
Water, bitumen, and sand.
Oil dewatering
Emulsion returning from the Wellhead
May be around 160-170°C. Some of the heat is used to preheat boiler feed water, using heat exchangers. Emulsion is now cooled to 115°C and enters a knockout vessel, in the first step to the emulsion separation.
Oil dewatering
Knockout vessel
Separates the free water from the remaining bitumen and emulsion, with a special demulsifier chemical.
Oil dewatering
The bitumen that leaves the knockout vessel
Is diluted and less viscous, by adding diluent. After dilution, the bitumen is called dilbit.
Oil dewatering
Dilbit
Flows to a Treater vessel, where electrostatic grids help remove water. Final sales dilbit has less than 0.5% water and relative density of 0.95. Stored in large tanks, pumps then transport the sales dilbit to an upgrader facility through a pipeline
Water de-oiling
Produced water
Water that leaves the free water knockout vessel and combines with the water from the treater vessel
Water de-oiling
Produced water flows to
Large settling tanks (skim tanks), where Oil floats to the surface and is recaptured. The produced water then flows to a induced gas flotation (IGF) vessel. Natural gas is blown through the produced water, forming an oil froth and further cleaning the water.
Water de-oiling
The last step
Uses oil removal filters (ORF’s), which are filled with Walnut shells and naturally attract oil. Water leaving the ORF’s contains less than 25ppm oil
De-oiled produced water
Contains dissolved scale forming compounds, like bicarbonate and silica. These impurities must be removed.
The de-oiled produced water is softened using
Hot or warm lime precipitation softener. Soda Ash will be added if the permanent hardness is present in the influent
The softener effluent is filtered and then further softened by
Ion exchangers. Typically, weak acid cation exchangers (WAC) are used opposed to Strong acid cation exchangers (SAC).
WAC are more efficient ion exchangers than
SAC. Also cost less to regenerate.
Both WAC and SAC
convert hardness to highly soluble sodium compounds, which will not precipitate as scale in boilers.
Results in 0 ppm hardness and less than 50ppm dissolved silica.
SOR
Steam to oil ratio. Barrels of steam consumed per barrel of oil produced. Ranges from 1.5 to 3. If SOR becomes too high, the plant is uneconomical.
Predominant constituent of natural gas
Methane, with 95% volume.
The production gas from Wells passes through
6
Compression, separation, absorption, dehydration, stabilization, and recompression
Absorption
The process where the hydrogen sulfide and carbon dioxide, acid gases, are absorbed by a solution of amine
Often monoethanolamine (MEA)
Dehydration
Additional absorption process that removes water through contact with a glycol mixture
Stabilization
Involves the flashing off of gases removed in the separation processes at low pressure from the liquid hydrocarbons.
Recompression is needed to
Increase the pressure of the gases from the stabilization process to a pressure suitable for sales gas or for the plant boiler fuel gas.
Cryogenic removal process
Uses an expansion turbine (turboexpander). Gas stream flows through an expansion valve, lowering its pressure. The lowered pressure causes the gas to expand and cool to below the dew point for the gas to be removed.
Cryogenic removal is most often used when
CO2 concentrations are high (50%). Mechanical energy from the gas expansion is converted to electrical energy in an attached generator
Sulfur removal using the Claus process
Requires a rich H2S gas stream. Burns 1/3 of the H2S in a furnace to produce SO2. SO2 reacts with remaining H2S in a catalytic process to produce water and Elemental sulphur. Recovers 95 to 97% of the sulfur
Gas treating
Dehydration
Uses glycol based absorption units
Gas treating
Hydrocarbon recovery
Uses a cryogenic turbo expander followed by a fractionating process. Leads the cooled liquids through separate distillation columns
Gas treating
Nitrogen
Removed by cryogenic distillation
Gas treating
Helium
Removed similar to nitrogen removal
Liquefaction of natural gas produces
A liquefied natural gas (LNG). typically 90% methane.
Sawn Timber that is not sold when newly cut, is required to be
Air or kiln-dried to prevent deformation of the wood through uneven natural drying
Drying and lowering the moisture of wood
Increases the woods value due to its Dimensions becoming stabilized, it’s increased strength, and mass lowered. Reducing Transportation costs
Air drying
Stacking the sawn Timber in piles in the open or under open sheds, exposed to a good flow of air
Kiln drying
Accelerates the drying process and permits greater temperature and humidity control. Can be completed within one week to one month
2 most common kilns
Batch and Progressive type
Kiln drying of sawn Timber accounts ___ of the total energy consumed in the sawmilling process
70-90%
2 types of kiln configurations to deliver Heat
Indirect heated Kilns and direct heated Kilns
Indirect heated Kilns
The most common.
Pelletizing
Compresses biomass (sawdust), into a pellet which can then be used as a solid fuel.
Plywood
Flat panel built of sheets of veneer, fused together by a bonding agent under heat and pressure to create a panel
Medium density fiberboard (MDF) has replaced particle board for a number of reasons;
3
Improved Machining and mechanical characteristics, smoother appearance, smaller particles
A pulp Mill is normally used to
Reduce wood to pulp fibre for the production of paper or other products
Pulp
The cellulosic material used for commercial purposes
Wood is composed of
50% cellulose and 30% lignin, as well as sugars and organic compounds
Pulp may be prepared from wood by _______ or ________
A Mechanical or chemical process
Pulp mechanical process
Wood is shredded with a grinder made from sandstone, or stone made of blocks of silicon carbide. Cheapest method, less equipment is needed compared to chemical processing.
Pulp chemical process
Freeze the cellulose material in the wood by treating it with reagents which dissolve the lignin. Lignin interferes with bonding in the cellulose fibres needed for increased strength in paper
Pulp chemical process advantages
Resulting product is more refined and has greater strength than ground would.
Pulp Chemical processes use
Sulfite and sulfate
Sulfate process can
Pulp any kind of wood
Digester
Filled with chips and cooking liquor (white liquor). Mixture of sodium sulfide and sodium hydroxide. Heated with steam to 175°C for 6 hours
Black liquor
The liquid leaving the digester and blow tank after the cooking operation is finished. Must be put through a recovery process to restore its properties before reuse in the digester
Green liquor colour is a result of
Iron impurities
High pressure steam is mainly used to
Power turbines
Medium pressure steam is used in
The process to heat, cook, and mix Liquors and stock
Low pressure steam used for
Heating and process applications
Thermal water/Steam cycle in a pulp mill
Generation - steam turbogenerators, wood waste boilers, recovery boilers
Distribution - condensing turbines, pressure reducing stations
End-use process - Dryers, digesters, evaporators
Recovery-reuse - condensers
Common combustion method with firing black liquor
Black liquor is fired on a vertically inclined trajectory, so the black liquor dries and starts to combust in suspension, prior to falling and accumulating in the furnace. The burning pile of fuel is called char bed
2 preventable causes of black liquor recovery furnace explosions
Fuel explosions and smelt water explosions
___________ increases the efficiency of the overall operation of a sawmill
Adding cogeneration facilities to convert extra waste into electricity for sale to utilities
The largest volume of non-coal solid-fuel is
Wood or wood waste and bark from the paper or Lumber industry
Hog fuel contains ____ moisture
45-55%
Four ways wood waste is burned in a furnace
Dutch ovens, Cyclone furnaces, boilers with underfeed Stoker’s, fluidized bed combustors
Gasification
Partial combustion of the biomass in a low-oxygen environment, leading to the release of a gaseous product, called producer gas or syngas, which has CO as a major constituent
Pyrolysis
Partial combustion is stopped at a lower temperature (450-600°C), resulting in the creation of a liquid Bio-Oil, as well as a gaseous and solid product
Anaerobic digestion or biomethanization
Process which takes place in most biological material that is decomposing and is favoured by warm, wet and airless conditions. The resulting gas, which is mostly methane and carbon dioxide, is known as biogas
Equipment used with steam in the production of sugar
Boilers, evaporators, clarifiers, crystallizer, and steam turbine/generator
Co-firing
Process of adding a percentage of biomass to the fuel mix in a solid fuel fired power plant
Co-firing process is typically used to reduce
The potential environmental impacts associated with the combustion of fossil fuels. Works best with a large Coal Fueled utilities, that have Material Handling capabilities on site
Three possible setups for co-firing
Direct, indirect and parallel
Direct co-firing
Biomass and coal are fed into a boiler with shared or separate burners
Indirect co-firing
Solid biomass is converted into a fuel gas, burned together with Coal
Parallel co-firing
Biomass burned in a separate boiler and steam is supplied to the coal fired power plant
Advantage of biomass co-firing
electric efficiency is higher than dedicated biomass combustion plants
Ambient temperature food processing
Prepares freshly harvested or slaughtered food for;
Processing, altering size, mixing ingredients, separating components
Elevated temperature food processing
Converts raw materials, plant or animal based, into edible and inedible components using steam or hot water
Reduced temperature food processing (preservation)
Involves methods to prolong the safe storage time frame of food
The initial stage of ambient temperature processing is
Surface treatment. Involves cleaning, sorting, grading and peeling if the surface requires removal
Culinary Steam
Steam used for direct injection into products
Reducing the temperature of food slows the
Biochemical and microbiological changes that would otherwise take place during storage
By bringing the internal temperature to _____ most foods have both an increased shelf life and increased perception of freshness
8°C and -1°C
Freezing
When the product is reduced below its freezing point and a portion of the water undergoes a change in state to form ice crystals
As food is Frozen,
Ice crystals form within its Matrix. At lower temperatures, the unfrozen material becomes more concentrated and forms a glass, which encompasses the ice crystals, preventing growth
Equipment used for chilling and freezing
Mechanical refrigerators, Heat exchangers, cryogenic systems
Cryogenic chillers and freezers
Use solid and liquid carbon dioxide, or liquid nitrogen, as a chilling medium placed in the chilling chamber
Minerals
Metals in their natural state combined with Rock and other nonmetallic components of the Earth
Native ores
Contain Metals in the freeform
Sulfide and arsenide ores
Contain Metals in combination with sulphur or arsenic
Oxide ores
Contain Metals combined with oxygen or oxygen based salts, such as carbonates or nitrates
Carbonate ores
Contain Metals in contact with the carbonate ion
The first step in all metallurgical processing is
The second step is
Mining The Ore
Preparing the raw materials for metal extraction. Focuses on concentrating or enriching the ore to remove non-metallic elements
Crushing
Reduces Rock size to smaller pieces
Hydraulic washing
Form of classifier which separates components of the mineral ore
Froth flotation
Common in the concentration of metallic sulfides. Separates based on differences in surface properties
Magnetic separation
Separate magnetic ores from the non-magnetic ores with an electromagnet
Ore leaching
Chemical reaction which washes the ore with a solvent solution to dissolve the metal
Metal ores are the most abundant in their __________ forms
Oxide, sulfide, and carbonate
Two methods for converting concentrated ores into their oxide forms
Calcination and roasting
Calcination
Heats the concentrated ore in an oxygen depleted atmosphere at a temperature below the melting point of the ore. Used for carbonates and hydrates
Roasting
Heats the concentrated ore in the presence of excess air and other metals. Used for sulfide ores
Smelting
Involves heating The Ore with a reducing agent
Electrolysis
Electric current is passed through the molten oxide or chloride of the metal. Pure metal is deposited at the cathode
The conversion of iron oxide to iron is the most
Significant reaction in metal processing
