Podcast
Questions and Answers
Which two categories are reactors broadly classified in? What are the main differences between the two types (pros/cons)?
Which two categories are reactors broadly classified in? What are the main differences between the two types (pros/cons)?
Reactors can be broadly classified as chemical or biochemical. Chemical reactors involve traditional chemical processes driven by temperature, pressure, and often catalysis. Biochemical reactors exploit biological processes such as fermentation or enzymatic reactions, often involving microorganisms or enzymes.
Which factors are most important to consider when choosing the reaction path to produce a product?
Which factors are most important to consider when choosing the reaction path to produce a product?
The reaction paths that use the cheapest raw materials and produce the smallest quantities of byproducts are to be preferred. Reaction paths that produce significant quantities of unwanted byproducts should especially be avoided, since they can create significant environmental problems. However, there are many other factors to be considered in the choice of reaction path. Some are commercial, such as uncertainties regarding future prices of raw materials and byproducts. Others are technical, such as safety and energy consumption.
Which are the six different types of reaction systems? Describe these systems briefly.
Which are the six different types of reaction systems? Describe these systems briefly.
- Single reactions: just one reaction of the type FEED → PRODUCT 2. Multiple reactions in parallel producing byproducts: a system may involve secondary reactions producing (additional) byproducts in parallel with the primary reaction. 3. Multiple reactions in series producing byproducts. Rather than the primary and secondary reactions being in parallel, they can be in series. 4. Mixed parallel and series reactions producing byproducts: In more complex reaction systems, both parallel and series reactions can occur together 5. Polymerization reactions: monomer molecules are reacted together to produce a high molar mass polymer 6. Biochemical reactions: often referred to as fermentations, can be divided into two broad types. In the first type, the reaction exploits the metabolic pathways in selected microorganisms (especially bacteria, yeasts, molds and algae) to convert feed material (often called substrate in biochemical reactor design) to the required product. In the second group, the reaction is promoted by enzymes.
Which three parameters are used to describe reactor performance? How are they defined?
Which three parameters are used to describe reactor performance? How are they defined?
If there is more than one reactant feed to a reaction, how do you determine which reactant feed the reaction performance should be determined for?
If there is more than one reactant feed to a reaction, how do you determine which reactant feed the reaction performance should be determined for?
Which parameter is considered most important in describing reactor performance?
Which parameter is considered most important in describing reactor performance?
Which are the three idealized models used for reactor design? How do they differ?
Which are the three idealized models used for reactor design? How do they differ?
Why can you describe a PFR with a series of CSTRS?
Why can you describe a PFR with a series of CSTRS?
Under what conditions is a kinetic model, derived from experimental data, valid?
Under what conditions is a kinetic model, derived from experimental data, valid?
Which reactor model is best for which reactor system? Explain why.
Which reactor model is best for which reactor system? Explain why.
How does the reaction order to product vs byproduct, when you have parallel reactions, affect the choice of reactor model if these orders are not equal?
How does the reaction order to product vs byproduct, when you have parallel reactions, affect the choice of reactor model if these orders are not equal?
Which reactor model is the best choice for a reaction system with multiple reactions in series producing byproducts? Explain why.
Which reactor model is the best choice for a reaction system with multiple reactions in series producing byproducts? Explain why.
How does the choice of reactor model affect the product for polymerization reactions?
How does the choice of reactor model affect the product for polymerization reactions?
What determines which reactor model to use for each specific polymerization system?
What determines which reactor model to use for each specific polymerization system?
For a reversible reaction, how is the conversion affected by changes in reaction conditions, such as temperature, pressure and concentration?
For a reversible reaction, how is the conversion affected by changes in reaction conditions, such as temperature, pressure and concentration?
Describe the equilibrium constant and what it defines?
Describe the equilibrium constant and what it defines?
When can the assumption of ideal gas behaviour be made for reactions in a gas phase?
When can the assumption of ideal gas behaviour be made for reactions in a gas phase?
What information can you get from the equilibrium constant in terms of reactant and product distribution at equilibrium?
What information can you get from the equilibrium constant in terms of reactant and product distribution at equilibrium?
Describe Le Chatelier's principle.
Describe Le Chatelier's principle.
How is the equilibrium constant affected by changes in temperature for an exothermic and an endothermic reaction?
How is the equilibrium constant affected by changes in temperature for an exothermic and an endothermic reaction?
How does this affect the equilibrium composition for an exothermic and an endothermic reaction?
How does this affect the equilibrium composition for an exothermic and an endothermic reaction?
How does the reactor temperature generally affect the rate of reaction?
How does the reactor temperature generally affect the rate of reaction?
Describe how the equilibrium conversion can be increased for an endothermic reaction.
Describe how the equilibrium conversion can be increased for an endothermic reaction.
Which factors affect the highest reactor temperature practically possible?
Which factors affect the highest reactor temperature practically possible?
How should the reactor pressure be chosen for gas phase equilibrium reactions?
How should the reactor pressure be chosen for gas phase equilibrium reactions?
How does changes in reactor pressure generally affect the reaction rate?
How does changes in reactor pressure generally affect the reaction rate?
Which is the preferred reactor phase of operation? Why?
Which is the preferred reactor phase of operation? Why?
For what reasons might you use an excess of one of the reactants?
For what reasons might you use an excess of one of the reactants?
What should be considered when an inert is added to increase the equilibrium conversion for an ideal gas phase reaction?
What should be considered when an inert is added to increase the equilibrium conversion for an ideal gas phase reaction?
Explain how adding an inert to the reaction A ↔ B + C may increase the equilibrium conversion.
Explain how adding an inert to the reaction A ↔ B + C may increase the equilibrium conversion.
For what case does the addition of an inert to an ideal gas phase reaction not affect the equilibrium conversion?
For what case does the addition of an inert to an ideal gas phase reaction not affect the equilibrium conversion?
Describe ways of minimizing byproduct formation for systems with multiple reactions in series, parallel and mixed series and parallel.
Describe ways of minimizing byproduct formation for systems with multiple reactions in series, parallel and mixed series and parallel.
Which factors determine the operating conditions of biochemical reactors?
Which factors determine the operating conditions of biochemical reactors?
What effect does a catalyst have on a reaction system?
What effect does a catalyst have on a reaction system?
Which eight steps are involved in heterogeneous gas-solid reaction on a supported catalyst?
Which eight steps are involved in heterogeneous gas-solid reaction on a supported catalyst?
Describe three methods for immobilizing enzymes.
Describe three methods for immobilizing enzymes.
Describe ways to control the temperature in a reactor for an exothermic and an endothermic reaction.
Describe ways to control the temperature in a reactor for an exothermic and an endothermic reaction.
Describe the mechanisms for catalyst deactivation.
Describe the mechanisms for catalyst deactivation.
How can catalyst degradation be counteracted by control of the reactor?
How can catalyst degradation be counteracted by control of the reactor?
How does mass-transfer affect reactions taking place in a gas-liquid reactor?
How does mass-transfer affect reactions taking place in a gas-liquid reactor?
Which factors are affected by a change in temperature for gas-liquid reactors and in what way?
Which factors are affected by a change in temperature for gas-liquid reactors and in what way?
Describe ways of improving the mass-transfer rate for gas-liquid and liguid-liquid reactors.
Describe ways of improving the mass-transfer rate for gas-liquid and liguid-liquid reactors.
Describe the usual configuration of tubular reactors and when they are most commonly used.
Describe the usual configuration of tubular reactors and when they are most commonly used.
Describe the usual configuration of stirred-tank reactors and when they are most commonly used.
Describe the usual configuration of stirred-tank reactors and when they are most commonly used.
Describe the usual configuration of fixed-bed catalytic reactors and when they are most commonly used.
Describe the usual configuration of fixed-bed catalytic reactors and when they are most commonly used.
Describe the usual configuration of moving-bed catalytic reactors and when they are most commonly used.
Describe the usual configuration of moving-bed catalytic reactors and when they are most commonly used.
Describe the usual configuration of fluidized-bed noncatalytic reactors and when they are most commonly used.
Describe the usual configuration of fluidized-bed noncatalytic reactors and when they are most commonly used.
Flashcards
What are Chemical Reactors?
What are Chemical Reactors?
Reactors that use traditional chemical processes driven by temperature, pressure and catalysis.
What are Biochemical Reactors?
What are Biochemical Reactors?
Reactors that exploit biological processes like fermentation using enzymes and microorganisms.
Factors when choosing reaction path?
Factors when choosing reaction path?
Using materials that are cheap and minimize byproducts to avoid environmental problems
What is a Single Reaction System?
What is a Single Reaction System?
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Multiple Reactions in Parallel?
Multiple Reactions in Parallel?
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Multiple Reactions in Series?
Multiple Reactions in Series?
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Polymerization Reactions
Polymerization Reactions
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What is Conversion?
What is Conversion?
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What is Selectivity?
What is Selectivity?
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What is Reactor Yield?
What is Reactor Yield?
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Multiple Reactant Feeds?
Multiple Reactant Feeds?
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What is Ideal-Batch Reactor?
What is Ideal-Batch Reactor?
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What is Continuous-Stirred-Tank Reactor (CSTR)?
What is Continuous-Stirred-Tank Reactor (CSTR)?
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What is Plug-Flow Reactor?
What is Plug-Flow Reactor?
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When Valid Kinetic Models?
When Valid Kinetic Models?
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Best reactor for single reactions?
Best reactor for single reactions?
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Reactions in series producing byproducts?
Reactions in series producing byproducts?
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Main Concern for Polymerization?
Main Concern for Polymerization?
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Narrow molecular weight distribution?
Narrow molecular weight distribution?
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Termination-sensitive reactions
Termination-sensitive reactions
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Exothermic Reaction?
Exothermic Reaction?
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Endothermic Reaction?
Endothermic Reaction?
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What to consider for reaction type?
What to consider for reaction type?
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Multiple reactions producing byproducts?
Multiple reactions producing byproducts?
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Preferred reactor phase?
Preferred reactor phase?
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Driving Complete Conversion?
Driving Complete Conversion?
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Minimizing Byproduct?
Minimizing Byproduct?
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Adding Inert?
Adding Inert?
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Addition of inert, w/ no effect?
Addition of inert, w/ no effect?
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Ways of minimizing byproducts?
Ways of minimizing byproducts?
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Factors Determining Biochemical Reactors?
Factors Determining Biochemical Reactors?
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What Effect Does a Catalyst Have?
What Effect Does a Catalyst Have?
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Eight Steps in Heterogeneous Reactions?
Eight Steps in Heterogeneous Reactions?
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Exothermic and Endothermic?
Exothermic and Endothermic?
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Mechanisms for Catalyst Deactivation?
Mechanisms for Catalyst Deactivation?
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Study Notes
- Study questions on chemical process design and integration are answered
Reactor Classification
- Reactors are broadly classified as chemical or biochemical reactors
- Chemical reactors utilize traditional chemical processes driven by temperature, pressure, and catalysis, for industrial chemicals like ammonia or ethylene
- Biochemical reactors exploit biological processes, like fermentation or enzymatic reactions, often employing microorganisms or enzymes
Chemical Reactors: Pros and Cons
- Pros: Efficiency, well-established technology, operate at extreme conditions for enhanced reaction rates
- Cons: Higher energy consumption, unwanted byproducts, waste and environmental concerns, necessitate safety measures
Biochemical Reactors: Pros and Cons
- Pros: Milder temperature and pressure, fewer hazardous byproducts, environmentally friendly, well-suited for renewable feedstocks
- Cons: Slower reaction rates, sensitive to operational changes, strict control of pH and temperature, scaling up difficulties
Reaction Path Considerations
- Preferred reaction paths use the cheapest raw materials and minimize byproducts to avoid environmental problems
- Commercial factors include raw material and byproduct price fluctuations
- Other factors: Safety and energy consumption
Types of Reaction Systems
- Single reactions: FEED → PRODUCT, FEED → PRODUCT + BYPRODUCT, or FEED1 + FEED2 → PRODUCT
- Multiple reactions in parallel producing byproducts: FEED → PRODUCT and FEED → BYPRODUCT
- Multiple reactions in series producing byproducts: FEED → PRODUCT followed by PRODUCT → BYPRODUCT
- Mixed parallel and series reactions producing byproducts: Involving parallel and series reactions together
- Polymerization reactions: Monomer molecules react to produce a high molar mass polymer
- Biochemical reactions (fermentations): Two types exist. One converts feed via metabolic pathways in microorganisms, the other uses enzymes
Biochemical reactions
- First type: FEED + microorganisms PRODUCT + more microorganisms
- Second Type: FEED + enzymes PRODUCT
Reactor Performance Parameters
- Conversion: (Reactant consumed) / (Reactant fed)
- Selectivity: (Desired product produced) / (Reactant consumed) × Stoichiometric factor
- Reactor Yield: (Desired product produced) / (Reactant fed) × Stoichiometric factor
- Stoichiometric factor: Moles of reactant required per mole of product
Determining Reaction Performance
- When multiple reactant feeds exist, performance is determined by the most critical or expensive feed, considering:
- Cost sensitivity: Measured by the reactant with the highest cost or economic impact
- Stoichiometric importance: Assessed for the limiting reactant for maximum conversion/yield
- Reaction pathway implications: Considers reactant impact on selectivity/yield of the primary product
Key Parameter
- Selectivity is more meaningful than reactor yield, which is based on reactant fed rather than consumed
Idealized Reactor Models
- Ideal-batch model: Reactants are charged, mixed for a period, and discharged, with uniform composition and temperature at any instant
- Continuous-stirred-tank Reactor (CSTR): Continuous feed and product takeoff with perfect mixing, leading to uniform conditions but variable residence time
- Plug-flow model: Steady, uniform movement of reactants without mixing along the flow direction, same residence time for all fluid elements
Approximating PFR
- Continuous Stirred Tank Reactors (CSTRs) in series can approximate a Plug Flow Reactor (PFR)
- The concentration gradient simulates decrease in reactant concentration
- Stepwise concentration changes become smaller with each reactor, approaching PFR characteristics
Kinetic Model Validity
- Kinetic models derived from experimental data are valid only for the conditions over which they are fitted, including:
- Specific molar feed ratios
- Temperatures
Reactor Selection
- Single reactions: Ideal-batch or plug-flow is preferred over mixed-flow due to smaller volume requirements
- Multiple reactions in parallel producing byproducts: Use high FEED concentration with a1 > a2, or low FEED concentration with a1 < a2
- Multiple reactions in series producing byproducts: Batch or plug-flow reactors offer better selectivity/yield than mixed-flow
Mixed Reactions
- a1 > a2, use a batch or plug-flow reactor,
- a1 < a2, plug-flow reactor with a recycle, a series of mixed-flow reactors or combination of reactors.
Polymerization Reactions
- For narrow molecular weight distribution without termination Batch Reactor or PFR because all have same residence time
- With termination: CSTR, maintains monomer concentration and a constant chain-termination rate
- Biochemical reactions: Depending on microorganism concentrations use;mixed-flow, plug-flow, combination or recycle
Enzyme Reactions
- High reaction rates are favored by high concentrations of enzymes and feed
- A plug-flow or ideal-batch reactor is beneficial in these conditions
Parallel Reactions
- Reaction orders with parallel reactions affect reactor model choices
- Plug Flow Reactor (PFR) or Batch Reactor is preferred IF the desired product has a higher reaction order
- A Continuous Stirred Tank Reactor (CSTR) is more appropriate IF the byproduct has a higher reaction order.
Reaction Systems
- For certain conversion system FEED must have corresponding time residence
- The mixed-flow model gives poorer selectivity because some of FEED and PRODUCT leave
- With the mixed-flow reactor Batch and Plug flow is better
Polymerization Reactions Reactor Choice
- Batch/Plug-Flow Reactors: Uniform residence time yields narrow molar mass distribution (if no termination) or broader distribution (with free radical termination)
- Mixed-Flow Reactors: Varying residence times broaden molar mass distribution; uniform monomer ensures constant chain-termination rate, resulting in a narrow distribution
Polymerization Reactor Choice
- For Polymerization reactors key concern for is product properties
- Molecular weight distribution, group orientation, chain cross-linking and consideration of monomers
- Desired narrow distribution: batch reactors or PFR
- wide distribution: CSTR
Termination sensitivity
- Using CSTR may control termination through equal monomer concentration
- Step-growth Polymerization use batch or PFR for high weights
Reactor preferences
- Large scale CSTRs for continuing operation
- Bach reactors or PFR for smaller more accurate applications
Reversible reaction conditions
- Exothermic reactions: Decreasing temperature increases efficiency
- Endothermic reactions: Increasing temperature increasesefficiency
Le Chatelier's Principle
- Reactions with decreased number of moles are efficient in increased pressure
- Reactions with increased number of moles are efficient in decreased pressure
- High shift of one of the reactants increase conversion
Equilibrium Constant
- Ka. represents balances in a system
- Fixed temperature
Ideal gas behavior
- The ideal gas law can be determined with medium temperature low pressure and non-polar molecules present minimizing interactions
Equilibrium reactions
- This determines relative connections between reactants and products
- Large K favors products. If near 1 concentrations become even.
Le Chatelier's Principle
- Changing reactor conditions causes imbalance and displacement
- Follow this principle to change equilibrium conversions
endothermic reactions
- high temps for higher conversions
exothermic reactions
- lower temps for higher efficiency
Factors determining max reactor temperature
- Safety consideration
- Material Construction
- Catalyst Life
- Reaction Type (Exothermic vs. Endothermic):
reactions with lower moles
- High pressure causes conversion rates while reducing reactor voume
- can make cost and safe concerns in relation
reactions with high moles
- lower rates toward product formulaition
- Reduces reaction rates and increases volume
- Low pressure enhance reaction with steady decline as approach
Multipule product creation
- Preassure helps maximaze conversion
Pressure in reactions
- vapor reactions increase speed and help decrease reaztor volume
- Effect on solids and liquids
Phased operation
- The phased of liquid prefferes
Excess reactant use
- Driving reaction in a single irreversible direction
Reactions shifts
- Conversion in reverse is determined by equilibrium
- Extra reactant converts equilibrium
Biproduct formation
- Excess reactant supresses side effects
Saafety considerations
- Less harsh chemical is more prefferable
Series reaction
- Limits transform of product
Increasing equilibrium
- Volume, rate, effiiciency
Explain inert aditions
- increasing number ratio
Inert materials
- the reaction must have a change in number otherwise inert materal has no affect
limiting byproduct
- less conversions needed
- remove product sooner
parallel reactions with limitations
- Increase inert with decrease product
Mixed reactions limitations
- more conversation is required
Factors in biochemical process
- careful attention to temperature acidity oxygen and product
Catalyst efect
- increase rate and unchanged in quantity
Gas and solid reactions
- gas transfer
- diffusion
- activation
- etc
Enzyme reactions
- enzymes can improve adsorption, covalent binds can be created
How to control Exothermic and Endothermic reactions
- Adiabatic Operation
- Catalyst Profile Adjustments
- Heat Carriers
Deactivation can occure from
- Physical loss
- Surface deposits
- Poisoning
- Chemical change
Control catalyst
- By gradually increasing temperature
Mass transport
- If the reaction has multiple phases the phase must effective
- high temps increase transport
resistance from gass and liquid
- reactants can defuse liquid of gass
Solubility controll
- low solid gas limit high rates
increase reaction in a reaxtor
- use bed pack
Changes affecting reactors
- higher reation decrease gas in liquid
- gas is more mass than liquid
Improving reactors
Increase Interface. reduce agitation reduce resistance or pressure use counter current
multiphase reactors
- increase agitation and or decrease drop
Tubiular reators
- Steady in only 1 direction
Reactions for Tubulars
- Series reactions need time to pass
- Good transfer rates needed
Stirred tanks
- They consinst of agitatin tanks
fixed bed reactors
- Use packed solid catalyists
- Follow plug, flow behaivor
non catalytic fixed bed
- gas absorbent tools
mobile catalyticreactors
catalyist move to feeder
fluid reactors
- solid held in supension
Non Catalyst fluid
- Increase hreat and efficiency
Gas product
- Free gas with solid
Configuration choice affected by
- catalyst
temp rannge
- changes accure when streams start or finish
Curves combined
- temp
- Hot steams combined
curve calculatilns
- Enthalpy
utilitys needed
- Determine min need
heat recovery
- The amount and how is it is affected by the curves relationship as a whole
Avoid heat transfers
- increasing levels
Threshold
- the heat utility and cold needs are the same
temparature shifting
- shifting gives best outcome
surppluss heat
- it may not be enough yo make other end usefull
Heat flows why do need
- heat must be 0
how to determine min heating
- shifts all infor to followinf steps
nont temp changes
- fluids
Process constraint
- Independence across 1 step
Compositive curve vs
The grand
how to show utility
- Show through flows and across temperature ranges
how to determine min use
- identify zones
integration process
- integrate abiove hot point for max reject
heat pump
- this arngement helps genuinley
Determine heat unit
- units are limited by stream
five stepps
- five steps using heat pump
you should what start
- start where problems exhist
what rule for cp
- increases in temperature
cp and table
- identify matches
the tick off
- minium heat unit
what to splirt strem
- if balanaces off
How to split 4
- split to maintain temps
Pinches,
isolate curve
integration methods
- adibatic opertion
- haet carriers
- how shot injection
- indirect
- quench
Placement
- placement detemerds how each point operates
How to determine
- distilation colums
What to intigrate to
Pressure and distillation relation
- changes how it will operate
what help
- adjust the pressurre to lower or higher temps
utility demand and heat duty
- can be traded off
intermediate devices
- extra points at temps
Heat pumps
- reluse overhead
integration of olums
- forward or backwards
reboilers
- add more
heater
- re using vapor to add
distillation sequenss
reorder to to improve
couple ddevicess
- elimate units
doubledifustion
- more heat help
dryer vs distilation
- changes vary by a lot
steam boilers
- feedwater treated
- suspended solids
- gas
water perfroms
- scale, corosion , foul
Blowdown does what
- reduces contaminats
Boiler
- steam and coal with clean air
What do gaz turbins
- compressing air
Steam Trapps
- stop condensat
coling
- once, air, recrcu
make up coling
- compensate loses
heat pumps
- efficiency, temp
refrigerant
Heat source
- gas
Condensor
- refridgrin
what occure in process
- heat will transfer depending on temp
atmospheric
- solid particals
Emissons
hardemissions
some leake
What can help with particlas
- filter
Precipitios
- larg eflows
Hierarchy can help reduce contaminates
- reduce sourecs
what problems are there
- there are too many saource
example is tank
- the gass is redirect
reducing quiality
- samples may not be perfect
what removes voc
- cool, adsorb, membranes
simple remve
- adsorption cool
How to destroys Voc
- use thermal for example
therm oxidation can make treatment easier
what can help with S
increase yield energy effincity
Best route
- gass
Why does gass help
- convert suilfer making it simpler
What does gass us
- absorbsion so it can efficiently sappeerate
What is made from steam
- all of the above
H2s can be
- removed
- Chemical adsorption helps in this process
- carbon, potasium
what form is removed from gas
SO2
scrubber
- the gas flows helping remove sulfur
What are component
- nox
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