Emissive limit

The European regulations have set SO2 emission limits for industrial combustion systems. They range from 1700 mg/Nm for power generation systems of less than 300 MW and to 400 mg/Nm for those exceeding 500 MW between 300 and 500 MW, the requirements are a linear interpolation (Figure 5.24). To give an idea how difficult it is to meet these requirements, recall that for a fuel having 4% sulfur, the SO2 emissions in a conventional boiler are about 6900 mg/Nm this means that a desulfurization level of 75% will be necessary to attain the SO2 content of 1700 mg/Nm and a level of 94% to reach 400 mg/Nm. ... 

When water is produced along with oil, the separation of water from oil invariably leaves some water in the oil. The current oil-in-water emission limit into the sea is commonly 40 ppm. Oily water disposal occurs on processing platforms, some drilling platforms, and at oil terminals. The quality of water disposed from terminals remains an area of scrutiny, especially since the terminals are often near to local habitation and leisure resorts. If the engineer can find a means of reducing the produced water at source (e.g. water shut-off or reinjection of produced water into reservoirs) then the surface handling problem is much reduced. 

If regulations governing specific emission limit VOC concentrations to the low ppm range then, of course, vapor fractions such as those illustrated by the above tabulation will not be acceptable. It may, however, still be justified to consider VOC condensation as a precursor to a final abatement device such as an adsorption bed. Removing most of the solvent from a vent stream by condensation, can drastically reduce the size and cost of a downstream cleanup system. 

RCRA incinerator regulations include adrninistrative as weU as performance standards. Administrative standards include procedures for waste analysis, inspection of equipment, monitoring, and facihty security. Steps needed to meet adrninistrative standards are outlined ia the permit apphcation performance standards are demonstrated during a trial bum. Trial bum operating conditions are included in the permit to assure ongoing compliance with the performance standards. Performance standards include destmction and removal efficiency (DRE), particulate emissions limits, products of incomplete combustion emission limits, metal emission limits, and HCl and Cl emission limits (see Exhaust CONTROL, INDUSTRIAL). 

Pa.rticula.te Emission Limits. Particulate emissions, including condensables, must be demonstrated during the bum to be on a dry basis less than 0.18 g/m (0.08 grain per dry standard cubic foot (gr/DSCF)) at the iaciaerator s stack, or lower depending on state regulations. 

Products of Incomplete Combustion Emission Limits. Products of iacomplete combustion typically are not directly measured duting the trial bum. Instead, levels of carbon monoxide (qv) emissions are used as an iadication of combustion efficiency. High combustion efficiencies are assumed to result ia acceptable levels of products of incomplete combustion. If carbon monoxide emissions are measured at less than 100 ppmv dry basis, the standard is met. However, if emissions are greater than 100 ppmv, no more than 20 ppmv of total hydrocarbons (qv) are allowed at the iaciaerator stack duting the trial bum. 

HCl and Cl Emission Limits. Hydrochloric acid and chlorine must also meet emission limits for an adjusted stack height. 

Control Systems. Control systems are used to regulate the addition of Hquid waste feed, auxiHary fuel, and combustion air flows to the incinerator furnace. In addition, scmbber operation is automated to help ensure meeting emission limits. Flows are measured using differential pressure... 

Similarly, airborne emission limits have been estabHshed by the NRC for nonrestricted areas. Limits of surface contamination must be estabHshed to provide a safe workplace for users (19). The appHcation of the as-low-as-reasonably-achievable (ALARA) principle to the above draws on the creative talents of the user to regard the limits as nonapproachable barriers and not as tolerable maxima for discharge. 

Emission Standards. In order to have a nationwide basis for air pollution emission controls and to set a minimum emission limit, the EPA developed New Source Performance Standards (NSPS). The NSPS set specific poUutant emission limits or describe the best available control technology (BACT) that should be appUed at that source. The EPA has issued NSPS, which apply to new constmction as weU as to large modifications, for many different sources. Sources in the chemical industry include the foUowing. 

Because of the necessity to comply with national standards for ground-level ozone, some states are planning another phase of more stringent NO emissions limits which may take place in the eady 2000s. These additional post-RACT reductions may affect plants of all sizes and types, but are likely to focus on major sources. The deadline for compliance in the most extreme areas is 2010. For severe nonattainment areas (O levels 0.181—0.280 ppm), including many coastal areas in the Northeast, from northern Virginia to southern Maine, compliance must be achieved by November 2005 to November 2007. Serious ozone nonattainment areas (O levels 0.161—0.180 ppm) are expected to be in compliance by November 1999. Moderate noncompHance areas must comply by November 1996. 

Continuous Emissions Monitoring. A key aspect of the new CAAA is the requirement that plants prove their continued compHance to new emissions limits by installing continuous emissions monitoring systems (CEMs). The CAAA imposes new requirements for monitoring NO, SO2, and CO2 levels in a plant s exhaust gas stream. Affected plants typically must gather data from stack monitoring systems, gas analyzers, and the plant s data acquisition system and provide the data in a format approved by the EPA and state regulators. CEM systems must be in place by November 1993 for boilers affected by Phase I of the CAAA, and byjanuary 1995 for plants impacted by Phase II. 

Design nd Operation. The destruction efficiency of a catalytic oxidation system is determined by the system design. It is impossible to predict a priori the temperature and residence time needed to obtain a given level of conversion of a mixture in a catalytic oxidation system. Control efficiency is determined by process characteristics such as concentration of VOCs emitted, flow rate, process fluctuations that may occur in flow rate, temperature, concentrations of other materials in the process stream, and the governing permit regulation, such as the mass-emission limit. Design and operational characteristics that can affect the destmction efficiency include inlet temperature to the catalyst bed, volume of catalyst, and quantity and type of noble metal or metal oxide used. 

The upper hmit of a gas concentration measurement range is usually 1.5 to 2.5 times the applicable emission limit. If no span value is provided, a span value equivalent to 1.5 to 2.5 times the expected concentration is used. For convenience, the span value should correspond to 100 percent of the recorder scale. 

MWCs Metal Emissions The NSPS includes a PM emission limit of 0.015 grains per dry standard cubic feet (gr/dscf) at 7 percent oxygen dry/volume and an opacity hmit of 10 percent (6 minute aver-... 

MWCs Acid Gas Emissions The NSPS requires a 95 percent reduction of HCl emissions and an 80 percent rediiction of SO9 emissions for new MWCs or an emission limit of 25 ppmv for HCl and 30 ppmv for SO2 (at 7 percent O2 dv). 

Table 27-21 gives typical values or ranges of these criteria for gas, oil, and coal. The furnace release rates are important, for they establish maximum local absorption rates within safe hmits. They also have a bearing on completeness of combustion and therefore on efficiency and particulate emissions. Limiting heat release on grates (in stoker firing) will minimize carbon loss, control smoke, ana avoid excessive fly a. ... 

CAAA90 is a technology-based program rather than the health-based program used in the original Clean Air Act. The standards and emission limits are based on maximum achievable control technology. The final emission lirnits will be set forth in permits issued by the individual states. 

The new law also establishes a clean fuel car pilot program in California, requiring the phase-in of tighter emission limits for 150,000 vehicles in model year 1996 and 300,000 by the model year 1999. These standards can be met with any combination of vehicle technology and cleaner fuels. The standards become even stricter in 2001. Other states can opt in to this program, though only through incentives, not sales or production mandates. 

Nationwide, plants that emit SO2 at a rate below 1.2 Ibs/mm Btu will be able to increase emissions by 20% between a baseline year and 2000. Bonus allowances will be distributed to accommodate growth by units in states with a statewide average below 0.8 Ibs/mm Btu. Plants experiencing increases in their utilization in the last five years also receive bonus allowances, 50,000 bonus allowances per year are allocated to plants in 10 mid western states that make reductions in Phase I. Plants that repower with a qualifying clean coal technology may receive a 4 year extension of the compliance date for Phase II emission limitations. 

Some variants of best practicable means are spelled out in the U.S. Clean Air Act of 1977. One is the requirement that best available control technology (BACT) for a specific pollutant be employed on new "major sources" that are to be located in an area that has attained the National Ambient Air Quality Standard (NAAQS) for that pollutant. BACT is also required for pollutants for which there is no NAAQS [e.g., total reduced sulfur (TRS), for which emission limits are specified by a Federal New Source Performance Standard (NSPS)]. BACT must be at least as stringent as NSPS but is determined on a case-by-case basis. 

An example of a set of emission limits based on the rollback approach is the limits adopted by the United States for carbon monoxide, hydrocarbons, and oxides of nitrogen emissions from new automobiles (Table 25-2). 

Emission Limits Adopted by the United States for New Light-Duty Automobiles... 

In some countries, the enforcement agency is allowed to exercise judgment on how much emission to allow rather than to adhere to a rigid emission limit. Discuss the advantages and disadvantages of this system. 

Regulation of aircraft engine emissions has been made a national responsibility by law in the United States. The Administrator of the Environmental Protection Agency is responsible for establishing emission limits of aircraft engines, and the Secretary of Transportation is required to prescribe regulations to ensure compliance with these limits. 

Are there regulatory limits in the jurisdiction where you reside which are different from your state, provincial, or national air quality or emission limits If so, what are they ... 

A key parameter in the design of the fuel vapor control system is the volume of activated carbon required to meet the emission standards for the various regulatory tests. In the case of the three-day diurnal test sequence, the emission limits are 0.05 grams of HC per mile during the run loss portion of the test (maximum emission -0.85 grams), and a maximum release of 2.0 grams for the sum of the hot soak period and any one of the three 24-hour periods making up the diurnal test sequence. 

Table 10.2 Selected emission limits for municipal waste incineration (units mg/m ) ...

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