CARB Training, and Random Flashcards
1
Q
What is the effect of temperature on CO and NOx formation in a combustion reaction?
A
Higher temperature leads to less CO formation, but more NOx formation.
2
Q
What is NFPA 704?
A
NFPA = National Fire Protection Association.
NFPA 704 is the “Standard System for the Identification of the Hazards of Materials for Emergency Response”.
This standard defines the “fire diamond”.
3
Q
Describe the source category approach that CARB uses to regulate air toxics.
A
The Toxic Air Contaminant Identification and Control Act provides a source category approach to controlling TACs. The Act requires CARB to first assess the risk from a TAC, during the TAC identification process. Then CARB must determine if regulatory action is needed to reduce the risk. If so, CARB must develop regulations (ATCMs).
4
Q
What are regulations generally based on?
A
Regulations are generally based on STATUTES.
5
Q
Describe ATCMs.
A
Airborne Toxic Control Measures.
These are regulations put forth by CARB.
Like most regulations, they are specific.
Here is an example:
“ATCM for Emissions of Perchloroethylene from Dry Cleaning Operations”
6
Q
Name the 5 “formal” categories of PM control devices (in addition to the basic simple approaches such as knock-out chambers and wet suppression).
A
- Cyclones/mechanical separators
- Fabric filter dust collectors (aka baghouses)
- Electrostatic precipitators
- Scrubbers
- Ceramic or metal filters
7
Q
Describe pulse jet baghouses.
A
These baghouses are cleaned by a high pressure jet of air, which cracks or shatters the dust cake from the bag.
Only works on the exterior filtration type of baghouse.
8
Q
In terms of exposure to TACs, what is the equation for Risk?
A
Risk = (Adverse Health Effect) x (Exposure)
9
Q
Why is ammonia slip a bad thing? Name 2 reasons. How is it controlled?
A
- Ammonia is toxic in sufficient concentrations.
- Under the right conditions, it can result in the formation of a detached plume (this is bad because detached plumes are made of fine PM that form when exhaust gases cool)
It is controlled by altering the ammonia injection rate into the boiler.
10
Q
Define NMOG.
A
Non-methane organic gases (aka ROG).
11
Q
Provide a general overview of scrubbers.
A
There are 2 kinds: wet and dry.
Wet = used for PM (generally).
Dry = used for gaseous pollutants (generally).
Scrubbers that use a liquid (usually water with additives, called scrubber liquor) to control PM are called wet scrubbers. In a wet scrubber, the dirty gas stream is brought into contact with the liquid by spraying it with the liquid, by forcing the gas though a basin of liquid, or by some other contact process.
12
Q
What is the more appropriate name for baghouses?
A
They are more accurately called “fabric filter dust collectors”.
13
Q
Name 5 applications / industrial processes where baghouses are used.
A
- Woodworking operations
- Food processing (such as coffee roasters, condiment packaging)
- Spray dryers
- Filter manufacturing
- Hot mix asphalt facilities
14
Q
Describe LFR.
A
Lateral flow reactor. This is found in SCR systems. The catalyst is found inside an LFR. In an LFR, the flue gas (pre-mixed with ammonia) is directed into gas inlets, and must pass through catalyst slabs in order to get to the outlets.
15
Q
Describe RFG.
A
Reformulated gasoline.
This is designed to burn cleaner than regular gasoline.
This is required by the CAA in cities with the worst smog pollution.
16
Q
Describe how baghouse types are named, and give the 3 main names.
A
Baghouse types are named after the method used to collect the PM / clean the baghouse.
- Shaker
- Pulse jet
- Reverse air
17
Q
Describe NSPS.
A
New Source Performance Standards.
This was included in the federal Clean Air Act of 1970.
18
Q
Describe Venturi scrubbers.
A
Venturis are the most commonly used scrubber for PM collection.
When the liquid inlet stream exits the “throat”, its pressure and speed drop significantly, which causes the liquid droplets to atomize and turbulently mix with the effluent. This provides a huge number of droplets (lots of surface area) for the PM to contact.
19
Q
Define ROG.
A
Reactive organic gases.
20
Q
Name the 2 major things that came out of the Clean Air Act of 1970.
A
NAAQS and NSPS
21
Q
How is catalytic efficiency calculated?
A
K / K0
K = the current activity level
K0 = the original activity level
22
Q
Explain the steps in acid rain formation, and the effects.
A
- Factories that burn coal with high sulfur content. This causes the release of SO2 and NO2.
- Sulfuric acid and nitric acid are formed in the atmosphere.
- These acids mix with water vapor, then fall to the ground as rain or snow (also, dry acid can fall out of the sky on its own).
- Acid rain can deteriorate stonework, enter bodies of water, damage plants and soil, and harm aquatic life.
23
Q
Describe ISD.
A
In-station diagnostics.
By the end of 2011, gas stations were required to have an ISD system that monitors both phases of the vapor recovery system, and reports break-downs.
24
Q
How is global warming potential quantified for non-CO2 substances?
A
Since carbon dioxide is the most abundant – and one of the most long-lived – greenhouse gases, it is used as the reference gas. It is given a value of 1. The global warming potential of all other greenhouse gases is expressed in terms of carbon dioxide equivalents. You will hear this term a lot and see it abbreviated as CO2Eq or CO2e.
25
In the present day, which is a more significant contributor to acid rain - NOx or SOx?
NOx
26
Define **absorption** and **adsorption**, as they relate to air pollution.
Absorption = intimate contact betwen a mixture of gases and a liquid, so that a high fraction of the gases will **dissolve** in the liquid via a chemical reaction (the pollutants must be soluble in the scrubbing liquid).
Adsorption = when one material accumulates on the **surface** of another material (it physically sticks to the surface).
27
Name 3 applications / industrial processes where ESPs are used.
* Paper mills
* Glass manufacturing
* Municipal solid-waste and hazardous waste incinerators
28
Name the 3 main factors that determine the influence of a particular GHG on atmospheric temperature.
There are three major factors that determine the influence of a greenhouse gas on atmospheric temperature:
•Its ability to absorb heat
•Its concentration in the atmosphere
•The length of time it persists in the atmosphere
29
Describe staged combustion burners for natural gas.
Staged combustion burners have multiple smaller burners, rather than one large burner. This allows for better control of air-to-fuel mixtures, and lowers flame temperatures. These factors results in **lower NOx emissions.**
30
Describe BACT.
Best available control technology.
The federal Clean Air Act Amendments of 1990 mandated the installment of BACT.
BACT is typically enforced in non-attainment areas.
31
When I am doing an inspection, should I give compliance advice? How specific should I be?
**Don't** give specific compliance advice! Only give **GENERAL** advice, and point them in the right direction.
32
Describe adsorption systems. What are they used for? How do they work? What is the most common adsorbent material used?
Adsorption systems are used to control VOC emissions. They work by passing VOC-laden gas through a bed of adsorbent (usually activated carbon). The adsorbent must have a high surface area. When the adsorbent is saturated with VOCs, the bed is isolated from the gas stream and desorbed (usually with low-pressure steam or hot nitrogen).
33
Name one interesting thing about the efficiency of baghouse filters.
Not only does the filter media capture PM, but the dust layer or "filter cake" also aids capture and increases efficiency. The bag provides the surface for capture of larger particles. Particles are collected by impaction or interception and the open areas in the weave become closed. This process is referred to as "sieving.” In other words, optimum control efficiency is not achieved until the bag filters are a little bit “dirty.”
Some particles escape through the filter until the cake is formed. Once the cake builds up, effective filtering will occur until the bag becomes excessively loaded and cleaning is required. At this point the pressure drop will be exceedingly high and filtering will no longer be effective.
34
Describe the 2 different filtration designs used in baghouses.
There are two filtration designs used in baghouses: **interior** filtration and **exterior** filtration.
Interior: PM is collected on the **inside** of the bag.
Exterior: PM is collected on the **outside** of the bag.
35
Name some performance indicators / things to check when inspecting a **SCR system.**
1. Inlet and outlet [NOx].
2. NH3 utilization and NH3 slip.
3. Catalyst bed reaction temperature.
4. Catalyst performance.
5. Schedules for periodic catalyst testing and NH3 injection system testing, catalyst cleaning, and catalyst replacement strategy.
36
Name 6 products of real-world combustion (for example, in a car engine).
1. VOCs (unburned hydrocarbons)
2. CO2
3. CO
4. NOx (NO and NO2)
5. PM
6. Toxics
37
Describe how a facility can deal with the PM that it collects from a cyclone.
* For facilities like hot mix asphalt (or HMA) operations, the collected dust can be re-introduced into the process of manufacturing HMA and used as filler material.
* For facilities that cannot reuse the collected PM, the PM is treated as either a waste product and landfilled (depending on whether toxic compounds are present), or it can be sold to other industries.
38
Describe SNCR. Name 3 things that make it different from SCR.
Selective non-catalytic reduction is similar to selective catalytic reduction, but there is **no catalyst** involved.
1. SNCR is typically used with boilers that are fired on either solid fuel, or on fuel that contains compounds that would **poison or blind a catalyst bed.**
2. **Urea, as well as ammonia,** may be used as the reducing agent (although the urea actually breaks down into ammonia and isocyanic acid at high temp).
3. Because the non-catalyzed reaction is not nearly as efficient, **SNCR requires a superheater in order to function.**
39
Describe Section 25218 of the CA Health & Safety Code.
This section deals with Household Hazardous Waste and Small Quantity Generator Waste.
40
What is the typical catalyst material in SCR?
A metal or metal compound. Examples:
Vanadium pentoxide (V2O5)
Titanium dioxide (TiO2)
Molybdenum
Tungsten
41
Name one source of hexavalent chromium.
Manufacturing processes.
Examples = cement plants, and chrome/metal plating facilities.
42
Name and briefly describe the 3 main types of thermal oxidizers.
1. **Direct-fired** thermal oxidizers (AKA afterburners, incinerators) - These do **not** have a heat recovery system. They require supplemental fuel (low up-front cost, but higher operating cost).
2. **Recuperative** thermal oxidizers - The incoming VOC-laden gas is passed through the hot exhaust (downstream of the incinerator portion), thus heating it up and saving on supplemental fuel costs.
3. **Regenerative** thermal oxidizers (RTOs) - Incoming VOC-laden gas is passed through a packed bed, filled with ceramic. Then, it is burned, then flows through a different packed bed. The beds periodically alternate, via valves.
43
Name a few examples of applications / industrial processes where thermal oxidizers are used.
There are too many to list, but here are a few interesting ones:
Hazardous waste TSDFs (Treatment, storage, and disposal facilities)
Graphic arts industry
Commercial cooking and roasting operations
Paint manufacturing
Storing and loading/unloading of petroleum
44
Describe RTOs in detail.
Regenerative thermal oxidizers have a heat exchanger composed of 2 or more ceramic beds. The VOC-laden gas passes through one bed, is burned, then passes through the other bed (thus heating it). Periodically, valves switch the flow, so that the incoming VOC-laden gas flows through the (now hot) ceramic bed. This saves energy (less supplemental fuel is needed).
Another variation = rotary oxidizers (there is a rotating manifold, to periodically change the flow of gases. These are used when facility space is limited).
45
What is the main way that an inspector can inspect a cyclone?
Perform a Visible Emissions Evaluation (VEE). If visible emissions are being emitted from a cyclone or downstream stack, the device is not working properly. Most Districts limit opacity from cyclones to 40% or less.
In some cases, the inspector may be able to check the pressure differential between the inlet air and outlet of the cyclone. There should be a pressure drop that indicates proper operation.
46
What does CUPA stand for?
Describe the program.
CUPA = Certified Unified Program Agency.
A CUPA is a local agency that has been certified by different departments of CalEPA to manage hazardous waste in its local area.
47
Describe condensers. What is their purpose? Name the most common type of condenser. Describe how they work. What is their control efficiency?
Condensers are used to remove VOCs from a waste stream. They use chilled water to cool and condense a vapor stream. They are typically used as pretreatment devices, upstream of other control devices. Sometimes, organic vapors can be recovered.
The most common type is the "shell & tube", AKA "surface condenser" type. The VOCs and the cooling liquid do **not** contact each other directly. Control efficiency = 50-95%.
48
What is HAZCAT?
It is a commercial kit that can be used to identify / classify hazardous materials.
49
Describe packed column scrubbers. What are they used to control? Describe their basic design. What is their control efficiency?
Packed column absorbers, AKA scrubbers, are used to control VOC emissions. In this device, the liquid (liquor) flows downward, and the pollutant-laden gas flows upward (counter-flow device). The scrubbing liquid usually contains a chemical that will react with the target VOC. The scrubbing liquid is atomized by nozzles, in order to increase its surface area. Just upstream of the exhaust port, there is a mist eliminator, which recovers moisture from the exhaust gas. Control efficiency = 90% or more.
50
Describe activated carbon. What is it derived from? What makes it "activated"?
Activated carbon is a form of carbon that has been processed to make it extremely porous, and thus it has a very large surface area available for adsorption. It is usually derived from charcoal.
51
Describe ultrafine PM.
What is the definition?
What are the sources?
What are the health effects?
Ultrafine PM refers to particles **\< 0.1 microns** in diameter.
Ultrafine PM is emitted from combustion. As they move through the air, they merge together into larger particles. If someone is near the source (eg a freeway), they will inhale the ultrafine particles before they merge.
Ultrafine particles have a **large surface area to mass ratio,** so they are more harmful than an equivalent mass of coarse PM.
52
Name 2 properties (**not** related to toxicity) that may make a TAC more problematic?
1. A high amount of **persistence** in the atmosphere.
2. The ability to travel a long distance **(transport).**
Together, these are called **persistence & transport.**
53
Name the 4 main mechanisms that can be used to reduce GHG emissions.
1. Direct emission reduction measures via regulations and enforcement.
2. Market-based systems, such as Cap and Trade.
3. Alternative compliance, such as urban planning.
4. Incentive Programs.
54
Name one source of perchlorethylene.
Dry cleaning.
55
Explain the difference between NESHAPs and MACT.
NESHAPs are the old set of federal standards, that **individually identified** 7 air toxics.
As part of the CAA Amendments of 1990, **MACT replaced NESHAPs.** The resultant regulations from this are sometimes called NESHAPs, but more commonly called MACT Standards. MACT Standards focus on regulating **sources of HAPs,** instead of regulating HAPs one at a time.
56
Describe stationary bed adsorbers.
They are the most common type of regenerative adsorber. They usually have 2 beds. One is used to adsorb, while the other is regenerated. Valves are used to periodically alternate between which one is being used for adsorption and which one is being regenerated. This allows the unit to be operated constantly, with greater efficiency.
57
How are MACT standards enforced in California?
In California, **air districts** must implement and enforce federal MACT standards, as well as some of the state toxics regulations.
58
What should I do if the company representative is in a hurry, is busy, or doesn't have a lot of time to meet with me?
I control the speed / pace of the inspection. Don't allow anyone to rush me.
59
Describe the Ringelmann scale.
It is a way to measure smoke density / **opacity**. You use a series of grids to estimate the amount of smoke emitted from a stack.
The scale is has a 5 levels of density inferred from a grid of black lines on a white surface which, if viewed from a distance, merge into known shades of grey. Shade 1 is slightly grey and is usually categorized by air pollution boards as acceptable. It corresponds to an opacity of 20%. Shades 2, 3, 4 and 5 correspond to opacities of 40%, 60%, 80% and 100% (completely black) and are usually considered to be "black smoke" by air pollution boards of most countries.
60
Describe DPF.
Diesel particulate filter. These are used on both stationary and mobile sources which have diesel engines.
61
Explain the distinction between PM10 and PM2.5 (NOT how big they are, but how they tend to be formed).
PM10 tends to form when big things are broken down into smaller pieces (examples = tires on the road, dirt being ground up by a farmer, vehicle brake pads).
PM2.5 tends to form when aerosols start to stick together and form larger particles (examples = gas phase nucleation and sedimentation).
62
Explain the atmospheric nitrogen cycle, and the reactions that happen, in the ABSENCE of human activities.
1. UV rays cause NO2 to split into NO and O.
2. The O atom reacts with O2, forming O3.
3. The NO (from reaction 1) reacts with O3, forming NO2 and O2.
63
Name one source of benzene.
Vapor emissions from gas stations.
64
Describe albedo.
Depending on the albedo, or reflectivity of the surface, radiation may be reflected back into space or absorbed by the earth and re-radiated as heat.
Examples:
Clean snow has a high albedo, and reflects lots of radiation back into the atmosphere.
Dark soil and dark vegetation have a low albedo, and absorb lots of solar radiation and re-radiate heat.
65
Describe reverse air baghouses.
In this type of baghouse, cleaning is accomplished by temporarily stopping the flow of dirty air and "backwashing" the filters with low-pressure air.
66
Name the 3 sub-types of packed-bed scrubbers.
1. Counter-current AKA Counter-flow (most common design).
2. Co-current flow.
3. Cross-flow.
67
How does the US EPA define "major stationary sources", and "area sources", of air toxics?
Major sources are sources that emit **over 10 tons per year of any one HAP** or **25 tons per year of any combination of HAPs.** Area sources are sources that emit lesser amounts of HAPs, like gas stations.
68
Name the 2 main types of oxidizers. What are they used for? What are the subtypes of each? Name any synonyms that they have.
Oxidizers are used to **control VOC emissions:**
1. **Thermal** oxidizers (AKA high-temp oxidizers). The 3 subtypes are **direct-fired,** **recuperative** and **regenerative.**
2. **Catalytic** oxidizers (AKA low-temp oxidizers). The 2 subtypes are **recuperative** and **regenerative.**
69
Describe the different source categories that California uses to regulate TACs.
For purposes of toxics regulatory authority, California only uses 2 categories, **stationary and mobile.** Unlike the U.S. EPA, California does **not** separate major stationary sources from area sources. All size facilities are considered stationary sources. For example, a gas station and a power plant are both considered stationary sources.
70
What is the control efficiency of packed-bed and Venturi scrubbers for PM and VOCs?
Packed-bed scrubbers:
PM: 30-80%
VOCs: 30-80%
Venturi scrubbers:
PM: 50-90%
VOCs: N/A
71
Explain the difference between MACT Standards and ATCMs.
MACT = Federal
ATCMs = State
ATCMs are similar to MACT standards except that they may be developed for mobile sources as well as stationary sources.
72
Describe how California added many TACs to its list.
In 1993, CA legislation was passed, which made it so that all federal HAPs are now state-listed as TACs.
73
Name 2 problems that can occur with catalysts.
1. Blinding (when the catalyst carrier becomes plugged, for example by PM).
2. Poisoning (when the catalyst becomes chemically changed).
74
Define nuisance.
Bothersome activities or conduct that unreasonably interferes with the rights of others.
75
Why do inversions occur?
After the sun goes down, the earth radiates heat into outer space, cooling rapidly. The air layer in contact with the ground is cooled, while air above remains at about the same temperature as it was before.
76
What are the 3 major air pollutants of concern in California?
What is their main source?
Ozone, PM, and toxic compounds.
Their main source is from combustion of fuels (directly or indirectly).
77
What are the 2 main types of "laws" that are relevant to air quality? Describe them briefly.
1. Case law = the reported decisions of appeals courts and other courts, which make new interpretations of the law.
2. Statutory law = written laws that are enacted by a legislative body.
78
Define mixing height.
The mixing height is the maximum height of vertical motion of a rising plume.
79
Name the different methods of controlling PM pollution, from simple to complex.
1. Containment
2. Gravity and Centrifugal Force
3. Filtration
4. Electrostatic Precipitation
80
Describe the 4 parts of the fire diamond.
Top = Red (flammability).
Left = Blue (health hazard).
Right = Yellow (instability / reactivity).
Bottom = White (special notice). May contain OX (oxidizer), W (reacts with water), or SA (simple asphyxiant).
81
What effect does a **high** pressure system have on air quality? Explain the reasons for this.
**High** pressure systems are generally **bad** for air quality.
When the air is under high pressure, it is pushed down towards the ground. There is less mixing, which means the air is more stable. More stable = less air movement (wind), and therefore **longer exposure times.**
82
How many Air Districts are there in California?
35
83
When I am noting a violation, what specifically should I cite? (legislation, law, code, regulation, rule, etc)
Cite the current law section, NOT the legislation.
84
What are the 2 main types of wet scrubbers?
Packed-bed type (cylindrical), and Venturi type (conical).
85
Describe how solids are removed from baghouses.
With the exception of the cartridge filter type, most PM control devices have a hopper at the base to collect the particulate matter.
Automatic continuous discharge devices are installed on baghouses that are used constantly.
86
Describe how the "Hot Spots" program is implemented and enforced.
The program is implemented and enforced by **local air districts.** First, districts require facilities to **report their emissions of toxics.** Based on this information, the district determines if a risk assessment is warranted. Selected facilities must perform **risk assessments** (usually via computer modeling). If the district determines that there is significant health risk, **the facility must notify the public** of the risk and prepare a **risk reduction plan.** The district assures that the facility implements the plan and that the risk is reduced until it is no longer significant.
87
Define soot, as it relates to diesel.
Soot = the collection of harmful compounds which are carried on the fine PM found in diesel exhaust. Diesel PM is a carcinogen.
88
Describe the simplest type of carbon adsorption system.
It consists of two or more small drums filled with activated carbon. They are arranged in series, so that when the first one becomes saturated, the second one will start working.
89
Explain "regeneration" in terms of diesel engines, and explain the 2 types.
Regeneration = Removing the PM that is stuck in a DPF, and burning it, in order to regenerate the filter so it will continue to work.
Passive regeneration = the soot ignites spontaneously.
Active regeneration = the temperature must be raised, because it would not get hot enough on its own. 2 types (electrical and fuel-dosing).
90
Name one source of para-dichlorobenzene
Found in many consumer products, such as insecticides, insect repellant, and air fresheners.
91
Name one source of methylene chloride.
Cleaning products, such as paint remover and degreasers.
92
Name and describe the more complex type of carbon adsorption system. When is it used? What is the main thing that sets it apart from the simple type? Name the 3 subtypes of this type of system.
Regenerative adsorption systems are used at facilities where the VOC stream is a direct result of the source's operation (permanent, not temporary or intermittent).
They are designed to be regenerated in place, rather than off-site as with the simpler system.
The 3 subtypes: Fixed (AKA stationary?), moving beds, and fluidized beds.
93
Describe ammonia skid.
This refers to the pieces of equipment that are used to prepare the ammonia to be injected into the boiler or turbine duct in an SCR system.
For aqueous ammonia, there is an evaporator which heats the liquid mixture to vaporize it. The vapors are then blended with air and sent to the injection grid.
For anhydrous ammonia, there is no evaporator needed, because pure ammonia is a gas at standard conditions. The system draws vaporized ammonia from the tank and mixes it with air, then sends it to the injection grid.
94
Name 2 **containment** strategies for reducing VOC emissions.
1. Keep the VOC-containing material in a vapor tight container (many local district rules require this).
2. Cleaning equipment, such as spray gun cleaners and parts cleaners, should be fitted with lids that prevent vapor escape.
95
Describe the Toxic Substances Control Act.
Passed in 1976. Authorized the EPA to secure information on all new and existing chemical substances, as well as to control any of them that were determined to cause unreasonable risk to public health or the environment.
96
What is the approximate PM control efficiency of ESPs?
ESPs are most effective with PM10:
Older existing ESPs: 90-95%
New ESPs: 95-99%
97
Explain the basics of how cyclones work.
A cyclone is used to remove PM from dirty air **without a filter.**
PM-laden air enters near the top of the device, and then flows in a spiraling path inside the cyclone. Then, the air makes a sudden change in direction, and flows to the cyclone outlet. The PM will experience centrifugal and inertial forces as it travels through the cyclone. The greater the particulate’s mass, the easier it will be to separate from the air stream. Generally, the higher the velocity of the gas stream through a cyclone, generating greater forces and faster change in flow direction, the higher the collection efficiency. However, the velocity of the gas stream has an upper limit, and beyond that, the efficiency starts to decline due to turbulence.
98
Generally speaking, why is ozone harmful? In other words, how does it react?
It "scavenges" water. Specifically, it reacts with the partially-positive hydrogens on the water molecules.
99
Name the 3 "types" of exposure to TACs.
1. Community-wide exposure (outdoor ambient air)
2. Near-source exposure (when people live or work near a source)
3. Indoor exposure
100
Describe the difference between positive pressue and negative pressure baghouses.
Fan upstream = Forced draft = Positive pressure baghouse.
Fan downstream = Induced draft = Negative pressure baghouse.
101
Name the 2 ways to promote condensation in a system.
1. Decrease the temperature
2. Increase the pressure
(these can also be done simultaneously)
102
Describe **lean burn.** Is the combustion complete or incomplete? What effect does it have on CO formation and NOx formation?
Lean burn occurs when there is **excess air available** in the combustion reaction. Therefore, this results in **complete combustion.** This results in **very little CO formation.** However, when there is enough extra air, there is also **not much NOx formation,** because the extra air acts as a heat sink and cools the flame (but too much air will cause the flame temp to drop too low and put out the fire).
## Footnote
**Lean burn is desirable because it minimizes pollutant formation during complete combustion.**
103
Name one source of formaldehyde.
It is used in the adhesive in particle board. It is commonly found in woodworking shops.
104
Describe the 2 main regulatory approaches that California uses to control TAC emissions.
1. Regulations for each source category (similar to federal system). This approach is guided by the Toxic Air Contaminant Identification and Control Act and results in ATCMs.
2. Regulations for individual sources. This approach is guided by the Air Toxics "Hot Spots" Information and Assessment Act.
105
Describe FIT.
Fluid Impingement Technology is a type of high efficiency spray equipment. This design uses 2 different streams of liquid, shooting at each other from opposite sides of the tip of the gun. This gun requires very low air pressure, and can achieve a transfer efficiency of 90% or more.
This type of technology is used in resin coating operations.
106
Name 4 applications / industrial facilities where scrubbers are used.
* Chemical manufacturing facilities
* Fertilizer manufacturing
* Rendering operations
* Gas plants
107
Name one source of butadiene.
Agricultural burning.
108
What does CESQG stand for?
Conditionally exempt small quantity generator.
109
Does a high lapse rate or a low lapse rate lead to cleaner air? Explain why.
A **high lapse rate** leads to cleaner air, because air will move up and down faster (think of something floating in water, bobbing up and down). This increased up and down motion leads to increased mixing of the air, thus lower concentrations of pollutants.
110
Describe smog. What is the definition of smog? Describe the chemicals involved, and the colors/visibility issues that they cause.
Smog is a non-technical term for brown, hazy, unhealthy air.
Smog is generally composed of:
1. Ozone (light blue tint)
2. PM (decreased visibility / haze)
3. NO2 (brown)
111
What is a UN number?
It is a 4-digit number assigned to an individual or a class of hazardous chemicals. This number is used in the Emergency Response Guidebook. Non-hazardous chemicals will NOT receive a number.
112
Name how airborne toxics are identified / referred to at the **federal** level **and** the **state** level.
Federal = Hazardous Air Pollutants.
State = Toxic Air Contaminants.
113
How many Air Basins are there in California?
15
114
Name 3 inspection parameters for HVLP spray guns.
1. Check for an "HVLP Stamp" on the gun.
2. Check the size of the holes on the air cap (HVLP air caps have comparatively large holes).
3. Check for a pressure gauge (HVLP equipment is designed to be used within a particular pressure range).
115
What is the approximate PM control efficiency of baghouses?
Conventional: PM10: 95-99.9%
HEPA: PM0.3: 99.997%
Ultra-low penetration air (ULPA): PM0.12: 99.9995%
116
Name some performance indicators / things to check when inspecting an **adsorber.**
1. Adsorbent particle size (smaller particles = higher control efficiency).
2. Physical bed depth.
3. Gas velocity (too high = not enough residence time).
4. [VOCs] in **inlet gases** (must be below the specified maximum) and **exhaust gases** (must be well below the LEL).
5. Temperature (lower temp = better adsorption).
6. Humidity (high humidity can reduce adsorption).
7. Fouling (pluggage caused by PM will reduce adsorption).
8. Channeling (when some of the waste gas stream finds a path of least resistance, thus skipping part of the adsorbent bed).
9. Modes of regeneration (thermal swing, pressure swing, or vacuum).
10. Housekeeping (leaks/damage).
117
Name 2 benefits and 1 weakness of RTOs.
Benefits:
1. Very tolerant of high temperatures and **resistant to thermal shock/stress,** unlike recuperative systems.
2. Ceramic is **very resistant to chemical attack** by acid gases, and resistant to corrosion.
Weakness:
The weak point is the **valves** that switch the direction of gas flow. If the valve timing is off, or if the valve seals leak, then VOCs may leak into the exhaust stream.
118
Explain how baghouses work.
A baghouse operates on the same principle as a vacuum cleaner. It's a filter media with an air mover (fan) to pull or push the air through the filter, and a collection device to collect the dust.
119
Name the 4 things that should be checked during a baghouse inspection.
1. Outlet opacity (VEE)
2. Pressure differential
3. Outlet PM concentration
4. Maintenance records
120
Name some performance indicators / things to check when inspecting oxidizers.
Both types of oxidizers:
1. Outlet opacity (VEE) - should be minimal.
2. Inlet and outlet [VOCs].
3. Temperature of combustion chamber and/or outlet.
4. Outlet [CO] and [O2] are indicative of the combustion efficiency, and therefore control efficiency.
5. Flow rate of exhaust gas (to determine residence time).
6. Housekeeping (leaks / damage).
Catalytic Oxidizers ONLY:
1. ΔT across catalyst bed (it should rise, to indicate that oxidation is occurring).
2. Catalyst activity level (it will decrease over time, and eventually will need to be replaced).
121
What effect does a **low** pressure system have on air quality? Explain the reasons for this.
**Low** pressure systems are generally **good** for air quality.
With low pressure, there is a lot of vertical mixing of the air, and high winds. This is generally good for air quality.
Exception: In dry places, the high wind can stir up dust.
122
Name 4 examples of area-wide sources.
1. Gas stations
2. Fireplaces
3. Dust from roads
4. Household products
123
Name the 4 factors that affect diffusion and transport.
1. Heat
2. Moisture
3. Wind (caused by pressure differences)
4. Terrain
124
In terms of control efficiency, what is the best design for cyclones?
1D-3D cyclones are considered to be the optimal design for best control efficiency.
125
Describe codes, and name a few examples.
Code = a set of laws/rules that are arranged in a systematic way, and enforced by a local agency.
Examples:
CFR, CCR, and CHSC (CA Health and Safety Code).
126
Name and briefly describe the 3 mechanisms that produce NOx.
1. Thermal NOx - formed when nitrogen and oxygen combine at high temperatures (this type makes up the majority of NOx released during combustion).
2. Fuel-bound NOx - formed when nitrogen present in the fuel is oxidized.
3. Prompt NOx - formed at the very beginning of the combustion process (don't worry too much about it).
127
Define liquor.
"Liquor" is the liquid scrubbing or washing element that is used in wet scrubbers.
They are usually composed of municipal water, but often contain additives, depending on the type of pollutants found in the exhaust stream.
Examples: NaOH if gas is acidic, Radox™ to control odors and VOCs.
128
How should I behave during a confrontational situation?
Maintain a "neutral demeanor" in a confrontational situation.
129
Name 6 performance indicators for packed bed scrubbers / things to check during an inspection.
1. Liquor chemistry (variable, but may include: pH, suspended solids).
2. Spray nozzle condition.
3. ΔP across the scrubber (too high = packing material may be plugged).
4. **Exhaust gas** flow rate and **liquid** flow rate (the manufacturer will give an acceptable range for each).
5. Housekeeping (signs of leakage or damage).
6. Temperature of gas and fluid flows.
130
Describe shaker baghouses.
These baghouses are cleaned by mechanically shaking the bags, using a motor with a drive shaft that is connected to the bags. The shaking process removes deposited particles.
131
Name 7 ESP performance indicators.
1. Outlet opacity (VEE)
2. ΔP (a moderate amount is good)
3. Outlet PM concentration
4. Primary power (current and voltage)
5. Secondary corona power (current and voltage)
6. Spark rate (should be moderate)
7. Rapper operation (visual inspection, or maintenance records)
132
Name the 3 types of catalytic oxidizers.
1. Basic catalytic oxidizers - very similar to thermal oxidizers, but use a catalyst bed (allows for much lower oxidation temperature, and thus saves fuel).
2. Recuperative catalytic oxidizers - the incoming VOC-laden gas is heated by the exhaust via a cross-flow heat exchanger (similar to recuperative thermal oxidizers). These have burners, but they are normally off (I think they only come on when necessary).
3. Regenerative catalytic oxidizers - they use ceramic packed beds for regenerative heat exchange (similar to regenerative thermal oxidizers). They have a **lower residence time than RTOs,** due to the catalyst speeding things up.
133
Describe radiative forcing. Explain the two types.
Radiative forcing is the difference between insolation (sunlight) absorbed by the Earth and energy radiated back to space.
Positive forcing (incoming energy exceeding outgoing energy) **warms** the system, while negative forcing (outgoing energy exceeding incoming energy) **cools** the system.
Positive forcing can be caused by GHGs.
Negative forcing can be caused by clouds/PM reflecting radiation away from Earth.
134
What effect does rain have on air pollution?
Rain tends to **improve** air quality, by **removing** pollution from the air.
135
Describe SCR. Describe what each word in the name means.
Selective catalytic reduction is a method of removing NOx from the exhaust stream after it has been formed. SCR involves injecting ammonia into the exhaust gases, in the presence of a catalyst.
Selective = the reaction **only** targets NOx.
Catalytic = a catalyst is used to increase the rate of reaction.
Reduction = NO and NO2 are **reduced** to N2 and O2 (which quickly combines with hydrogen to form water).
136
Name 3 natural sources of PM10
1. Forest fires
2. Windblown dust
3. Biogenic emissions from plants/trees
137
Describe the major air pollution event that occurred in 1984.
The disaster in Bhopal, India.
Methyl isocyanate gas was released from a chemical processing plant.
This caused over 7,000 deaths.
This is considered to be the world's worst industrial disaster.
138
What does TES stand for? Describe it.
Triboelectric sensor. This is a device that **directly measures PM concentration** in an effluent gas stream. They work by detecting very small changes in current, caused by PM striking the metal probe.
They are **extremely sensitive**, and work well at **very low PM concentrations.**
139
Name some performance indicators / things to check when inspecting a **boiler.**
1. Stack [NOx], [O2], and [CO]
2. FGR damper valve position monitor
3. Burner temperature
4. Stack exhaust temperature
5. Continuous Emissions Monitoring System (CEMS) data, if the facility is large enough to have one.
140
When (time of day, season) do inversions typically occur?
They can happen in winter, and summer, and probably all seasons.
They usually happen before sunrise.
141
Name some things to check for when inspecting a scrubber system (the list is very long, so just name a few).
* Stack opacity (VEE)
* Liquor pH
* Liquor make-up rate
* Delta p (pressure differential) across the scrubber
* Liquor flow rate
* Physical condition of shell and ductwork
* Means of liquor disposal
* Physical condition of spray nozzles
* Atomization pressure in spray nozzles
* Flow rate within the spray nozzles
142
Describe HVLP.
High Volume Low Pressure spray guns are a type of spray paint nozzle system. At the tip of the gun, a regulator controls the air pressure, so that the paint (or other coating) leaves the nozzle in an atomized form, but with a low velocity. This results in less overspray and higher transfer efficiency (around 80%, vs 25-50% for a regular aerosol spray paint can).
143
Describe DLN.
Dry Low NOx systems are installed on some gas turbines. They reduce NOx emissions by splitting the combustion process into zones and then carefully controlling the air-to-fuel mixture in each zone.
144
Name 5 issues commonly encountered with cyclones.
* Plugging of the inlet and outlet
* Emissions leakage resulting from component erosion
* Corrosion of the entire cyclone, if the effluent gas is too acidic or basic
* Emissions leakage caused by physical damage (eg run into by industrial equipment)
* Re-entrainment of collected material in the conical section/hopper resulting from extended periods between clean out/load out of the device
145
Name some performance indicators / things to check when inspecting a **SNCR system.**
1. Ammonia injection rates (should be fairly constant for a given firing rate).
2. Stack [CO], [O2], and [NOx].
3. Boiler furnace temperature (if too high or too low, the redox reaction won't take place).
4. Detached plume? If so, does the PM source testing account for this?
146
What does ESPs stand for? What are they for? How do they work?
Electrostatic precipitators. They are a type of PM-controlling device. They contain alternating rows of negatively-charged wires (called **discharge electrodes**), and grounded **collector plates.** This causes some air molecules to become negatively-charged. These ions impact PM as it flows through and build up, effectively **giving the PM a negative charge.** These particles are then attracted to, and collected on, the collector plates.
147
Describe how cyclone sizes/dimensions are communicated.
Cyclones are described as "XD-YD"
D = diameter of the body
X = length of body / diameter of body
Y = length of cone / diameter of body
Example: "1D-3D" means that the length of the body is the same as the diameter of the body, but the length of the cone is 3x longer than the diameter of the body.
148
Name 2 weather conditions that affect atmospheric ozone levels, and the reason for the different effects.
1. Sunny weather **increases** the rate of ozone **formation**, because UV rays cause NO2 to split into NO and O.
2. Rainy / wet weather **increases** the rate of ozone **destruction**, because the ozone attacks the water in the atmosphere and gets destroyed.
149
Name 5 inspection parameters for facilities that use spray guns.
1. Housekeeping (check for open containers and evidence of repeated spillage).
2. Make sure they are using HVLP or FIT equipment.
3. Make sure the equipment is being operated at the appropriate pressure.
4. Make sure the operators are using the proper techniques.
5. Records (paint usage and solvent recycling).
150
Air Districts have enforcement authority over which source(s) of emissions?
Area sources and stationary sources, but NOT mobile sources, consumer products, or fuels.
151
Why is ozone considered to be "the most democratic of pollutants"?
Ozone shows up about **2 hours downstream** (in terms of wind speed) from where its precursors, the ingredients, are made.
Why democratic? Typically, the highest property value will be in the foothills surrounding the metro area. Because of the 2-hour delay, **ozone tends to show up in wealthy neighborhoods**.
152
Describe ammonia slip.
In SCR, NH3 reacts with NOx in the catalyst bed. The reaction must take place **before** they pass through the catalyst bed. Even with good mixing, some ammonia is going to pass through the bed unreacted. This is called ammonia slip, and is often expressed in ppm.
Today, typical ammonia slip permit limits are \<5 ppm.
153
Explain the difference between soot and ash.
* Soot is a byproduct of incomplete combustion and is what gets combusted in the regeneration process.
* Ash is noncombustible residue, like some constituents of lubricating oil or fuel, that also is captured by the filter and remains in the filter media after regeneration is complete. Ash removal is a regular part of DPF maintenance.
154
Describe rapping systems. What are they for? What are the 2 main types?
Rapping systems are used in ESPs to dislodge dust from the collecting and discharge surfaces.
2 types:
1. Pneumatic or electromagnetic impulse units.
2. Mechanical hammers or anvils.
155
Name one source of carbon tetrachloride.
Was formerly used in Halon and Freon in air conditioners. It has been banned, but it persists in the atmosphere.
156
Name and describe the 2 components of a SIP.
1. Air District Implementation Plans - Each District that was/is in nonattainment for a particular pollutant must develop a local plan that summarizes control measures (for stationary and area sources) that the District will implement.
2. Proposed State Plans - The state must develop a similar plan that summarizes control measures (for fuels, mobile sources, and consumer products) that the state will implement.
157
Describe CAPCOA.
California Air Pollution Control Officer's Association.
Formed in 1976. They are a non-profit. They are NOT a government agency. They are an association of all of the CA Air Districts. They sponsor training for Air District staff, among other things.
158
Define VMT.
Vehicle miles travelled.
159
Name some performance indicators / things to check when inspecting a **NSCR system.**
1. [O2] between the combustion chambers and the catalyst bed. Make sure the oxygen sensor is working!
2. Air-to-fuel ratio going into the chambers.
3. Annual source testing and physical inspection.
4. Maintenance records, including catalyst replacement strategy.
160
How is the atmospheric nitrogen cycle different, in the PRESENCE of human activities?
1. We add huge amounts of NO2, as well as VOCs.
2. The presence of VOCs **slows** the conversion of O3 back into O2.
161
Define TOG.
Total organic gases.
162
Which TAC is responsible for most of the health risks from TACs, state-wide?
Diesel PM.
163
Define STIG. Briefly describe the 2 subtypes.
STIG = Steam injection gas turbine.
2 Subtypes: Full STIG and partial STIG.
Both subtypes result in significant NOx reductions.
164
Define adiabatic lapse.
Adiabatic lapse refers to when the temperature falls with increasing altitude.
165
Describe gravity separators.
AKA Separation chambers or Knock-out Boxes.
A gravity separator is just a box with baffles inside it, which force PM-laden air to change direction. Each directional change causes dust to fall out of suspension and into the collection area.
Gravity separators can remove **larger PM.** They are often used as a **pre-cleaning device** for baghouses or ESPs.
166
Name the 5 main types of technology that are used to control VOC emissions.
1. Material use minimization and containment.
2. Scrubbers.
3. Condensers.
4. Adsorbers.
5. Oxidizers.
167
Describe the California Clean Air Act.
Passed in 1988. This act required the enforcement of CAAQS, which are generally more stringent than NAAQS.
168
Describe **steam injection.** What is its purpose? What are the two variants?
This is a type of **wet NOx control,** where steam is injected into the combustion chamber of a gas turbine. Its purpose is to **reduce thermal NOx formation by lowering peak flame temperature** in the combustion chamber. It is usually more desirable than water injection, because it doesn't cause as much heat loss as water, and it doesn't increase CO emissions as much.
Two variants: Full STIG and partial STIG.
169
Describe **water injection.** What is its purpose? Name some advantages and disadvantages.
This is a type of **wet NOx control,** where water is injected into the combustion chamber of a gas turbine. Its purpose is to **reduce thermal NOx formation by lowering peak flame temperature** in the combustion chamber.
**Advantages:**
Significant reduction in NOx emissions.
**Disadvantages:**
Increase in VOC and CO emissions.
Reduced lifespan of turbine components.
170
Explain the different ways that multiple cyclones can be arranged in a system.
Cyclones can be designed as a single unit, multiple single units grouped in parallel or in series, or as a collection of units called a multi-clone.
171
Describe AB32.
This is a California law, called the "Global Warming Solutions Act of 2006".
This set an emissions target for GHG levels.
Goals:
Reduce GHG emissions to **1990 levels by 2020.**
Reduce GHG emissions to **80% below 1990 levels by 2050.**
172
Name some performance indicators / things to check when inspecting a **surface condenser.**
1. Gas inlet and outlet temperature.
2. Coolant inlet and outlet temperature.
3. Flow rates of the gas and coolant.
4. Condensate flow rate (changes may indicate a potential failure).
5. Housekeeping (signs of disrepair, leaks, damage, etc)
Many of these are meant to be within a specific range, which should be specified in the permit conditions.
173
Name 3 toxic properties that TACs may have.
TACs may be:
1. Carcinogenic
2. Mutagenic
3. Teratogenic (cause birth defects)
174
Describe "unit risk factor".
Cancer risk of a TAC is expressed as a unit risk factor. This factor is the **probability of developing cancer** as a result of **constant exposure** to an ambient air concentration of **1µg/m3** for 70 years.
175
What is a small quantity generator, according to 29 CFR 1910.120?
It is a generator of hazardous wastes who generates under 1000kg of hazardous waste per month.
176
Name 7 applications / industrial processes that use **scrubbers and/or condensers and/or adsorbers** to remove VOCs.
1. Dry cleaning.
2. Degreasing.
3. Pharmaceuticals.
4. Plastics and resin.
5. Paints.
6. Odor reduction (eg H2S).
7. Petroleum refineries / bulk gasoline storage.
177
Name 3 types of facilities where cyclones are typically found.
1. Nut (and other agriculture) processing facilities
2. Woodworking operations
3. Hot mix asphault facilities
178
Describe the difference between wet NOx controls and Dry Low NOx systems.
Wet NOx controls involve liquid water or steam, but Dry Low NOx systems don't.
179
Describe **rich burn.** Is the combustion complete or incomplete? What effect does it have on CO formation and NOx formation?
Rich burn occurs when there is not enough air to complete the combustion reaction. Therefore, this is **incomplete combustion.** This results in **CO formation.** However, there is **not much NOx formation**, for 2 reasons:
1. Lower flame temperature.
2. Available oxygen is consumed by carbon oxidation, so less is available to oxidize the nitrogen.
**Rich burn reduces the NOx problem, but creates a CO problem.**
180
What should I do BEFORE I visit a site for an inspection?
Study the facility (in the office) before I do the inspection. Think about what processes are in place, and what PPE I might need to bring with me.
181
Describe "pressure differential" in a baghouse, and why it is important. What does it look like if it is not good? What does this mean?
One of the primary inspection tasks in many baghouses is the measurement of pressure drop across the filtration system. The drop indicates that there is air flow resistance in the system supplied by the filters. The pressure drop measured on a baghouse is the difference between the clean side and the dirty side.
If ΔP is too low, it means that there is **nothing actually impeding the air flow** coming out of the facility (eg a major hole or bypass has opened, or bag has failed).
If ΔP is too high, there may be **excessive impedance to air flow** and could lead to component failure or be an indication that **cleaning is needed** (eg bags have become very plugged).
182
What is the difference between OSHA and NIOSH?
OSHA creates and enforces regulations. They are part of the Dept of Labor.
NIOSH is a research and educational organization that reports to the CDC.
183
For the NAAQS which use parts per million, what "type" of ppm is it? (by mass, volume, or molarity?)
by volume
184
Define lapse rate. What is the average lapse rate?
It is the rate at which temperature falls with increasing altitude.
The average lapse rate is 5.5°F per 1,000 feet.
185
Describe NSCR.
Non Selective Catalytic Reduction systems (AKA 3-way catalysts) are sometimes installed on large stationary natural gas fired engines. They can simultaneously control the following 3 pollutants:
1. NOx
2. CO
3. Hydrocarbons
One example of NSCR = automobile catalytic converters.
In order to achieve the best control efficiency, the engine is controlled to run **slightly rich.** This provides the excess hydrocarbons necessary to react with all the NOx.
The fuel used should be **low-sulfur fuel,** otherwise the catalyst is susceptible to fouling.
186
Describe TACs. What sets them apart from other air pollutants?
Toxic Air Contaminants. They can produce very serious health effects with **very low exposure levels.** These are things where **any measurable exposure** **is considered hazardous** to human health.
Our bodies can handle a certain amount of ozone, NOx, and PM, but this is **not** the case with TACs.
187
Describe wet suppression.
Often the most effective means of controlling PM is just to keep it wet. Water and/or chemical suppressants will hold PM in place and is adequate control for many types of operations (eg construction or aggregate production).
188
What types of pollutants can scrubbers be used to control?
PM, VOCs, and odors.
189
Name one source of acetaldehyde.
Residential woodburning / fireplace use.
190
Name the first and second most significant causes of atmospheric warming (name the specific substances).
1. Carbon dioxide
2. Black carbon particles / soot
191
What are the 2 main constituents of NOx?
NO and NO2.
192
Describe the Montreal Protocol.
Year = 1987.
Original intent was to ban CFCs by the year 2000, due to ozone layer destruction.
193
Describe the different "levels" of DPF filtration efficiency.
Level 1 - Similar to a catalytic converter. Incinerates ~25% of PM into CO, CO2, and H2O.
Level 2 - Similar to Level 1, except the filter is filled with catalytic packing material (similar to steel wool). Control ~50% of PM.
Level 3 - Requires the exhaust to actually pass through a "wall" with very small pores in it. Control ~85% of PM.
194
What is the approximate PM10 and PM2.5 control efficiency of the different types of cyclones?
PM10:
Conventional: 30-60%
High-efficiency: 60-95%
PM2.5:
Conventional: 0-40%
High-efficiency: 20-70%
Multi-clones: 80-95%
195
Describe the 2 types of ammonia that are used in SCR.
1. Pure ammonia, AKA anhydrous ammonia, is liquefied under pressure.
2. Aqueous ammonia is ammonia in 19-29% water.
196
Name the 3 major anthropogenic sources of methane emissions.
* Leakage from landfills (from organic matter decomposition)
* Natural gas and petroleum systems (leakage during production, processing, storage, transmission, and distribution)
* Enteric fermentation (domesticated ruminant livestock exhale significant quantities of methane as a by-product of digestion)
197
How are the Air Basins defined/divided?
They are defined by geography and meteorology.
198
Define HSC.
(California) Health and Safety Code.
199
Describe FGR.
Flue gas recirculation. This is a form of combustion modification for boilers. In this system, exhaust gases are recirculated back into the combustion chamber. This helps reduce NOx in 2 ways:
1. It lowers peak flame temperatures.
2. It reduces the amount of available oxygen.
The FGR damper can usually be controlled automatically, by computerized logic controls.
200
Describe EVR.
Enhanced vapor recovery.
In 2001, EVR systems were phased in. Gas stations had to install new equipment on pumps and storage tanks.
This helps to reduce fugitive emissions of VOCs from gas stations.
201
Name the 3 common materials used as a catalyst in NSCR.
Palladium, rhodium, and platinum.
202
What does DTSC stand for? Briefly describe it.
(California) Department of Toxic Substances Control.
It is a department of CalEPA.
It administers the CUPA program.
