- Unintentional releases, such as those due to leaking equipment, are known as fugitive emissions
- Can originate at any place where equipment leaks may occur
- Can also arise from evaporation of hazardous compounds from open topped tanks
- Volatile organic compounds (VOCs) can be emitted from leaking valves, flanges, sampling connections, pumps, pipes and compressors.
SOURCES OF FUGITIVE EMISSIONS
Agitator seals Loading arms
Compressor seals Meters
Connectors Open-ended lines
Diaphrams Polished rods
Drains Pressure relief devices
Dump lever arms Pump seals
Flanges Stuffing boxes
MEASURING FUGITIVE EMISSIONS
- Portable gas detector
- Catalytic bead
- Non-dispersive infrared
- Photo-ionization detectors
- Combustion analyzers
- Standard GC with flame ionization detector is most commonly used
- Average emission factor approach
- Screening ranges approach
- EPA correlation approach
- Unit-specific correlation approach
CONTROLLING FUGITIVE EMISSIONS
- Modifying or replacing existing equipment
- Implementing a leak detection and repair (LDAR) program
Table 1 .9.1. Equipment Modification
2. LDAR Programs
- Designed to identify pieces of equipment that are emitting sufficient amounts of material to warrant reduction of emissions through repair
- Best applied to equipment types that can be repaired on-line or to equipment for which equipment modification is not suitable
WATER USE MINIMIZATION
- Water is a critical resource for many economic activities. Even some of the activities can proceed without water.
- It is necessary that use of water should be minimized not only in bigger economic activity but also in daily life so that these activities may be prolonged and water remains available for future generations also.
- Effective water management requires a coupling of production objectives, environmental impacts, and economic influences.
- Water Use Minimization involves a thorough evaluation of existing process operations, water utilization improvements, operational changes, plant-level design improvements, etc.
IN-PLANT CONTROL TO MINIMIZE WATER POLLUTION
The following in plant control measures are suggested to minimize the wastewater generation:
- Modification in the process
- Optimum use of raw materials
- By-product recovery
- Maximum reuse of water
- Attitude of the management in reducing the pollution
- Proper operation and maintenance
- Local regulation regarding the water use and effluent quality
- Good house keeping
PROCESS AND PRODUCT CHANGE
Process and product change is in fact a continuous process which is going on for last so many decades. The process of improvement in the product is basically user oriented. Cost effectiveness is also another factor that governs production criteria.
Sustainable development of industry can be achieved by:
(a) Product changes: a. By designing so as to have less environmental impact b. Increased product life
(b) Process Changes: It is of following three types:
a. Material changes: Material purification and substitution for lesser cost, toxicity and environmental effects
b. Technology changes:
i. Layout changes
ii. Increased automation
iii. Improved operating conditions
iv. Improved equipment
v. New and cleaner technologies
c. Operational changes
i. Operating and maintenance procedures
ii. Management practices
iii. Stream segregation
iv. Material handling improvements
v. Production scheduling
vi. Inventory control
vii. Waste segregation
WATER SUPPLY SYSTEMS
- Water System Audits and Universal Metering: A water system audit quantifies how much water a system produces and purchases and where that water is going. The first step should include metering of all water-service connections.
- Leak Detection and Repair: Leak detection is a process to identify and repair water system leaks that are causing water loss. Leak detection methods range from visual inspection to using specialized leak detection equipment to find hidden leaks .
- Water Reuse: Highly treated wastewater can be used for many purposes, such as irrigation, dust control, and some industrial processes.
BUSINESS AND INDUSTRIAL WATER USE
- Motivation of less water usage: Businesses and industries are motivated to use less water to reduce operating costs by lowering water bills. Cost savings comes from reduced water purchases, pumping expenses and wastewater treatment costs.
- Cooling Water: Cooling towers can consume 20% to 30% of the water used by commercial and industrial facilities.
- Fixture Replacement: Replacing faucets, toilets, showerheads, hose nozzles, and other water delivery devices with more efficient systems reduces the water use.
BOILER WATER MINIMIZATION
Boilers supply steam for process heating, space heating, power generation, etc. Boilers require makeup water to function; and generate wastewater as blow down. Boiler water minimization can be done by:
- High Purity Water Makeup: Pretreatment equipment such as reverse osmosis and demineralization allow the boiler to run at higher cycles of concentration. This results in lower makeup water and lower blow down rates and less energy consumption .
- Increase Condensate Return: The more condensate that can be returned to the boiler, the higher will be the number of cycles and less blow down, makeup, and heat energy will be required.
- Eliminate Condensate Contamination: Perhaps the reason condensate isn’t being returned is condensate contamination. Condensate contamination is avoided, the conductivity would be higher. Higher the conductivity of water in a boiler, the lower the makeup and blow down rates and energy consumption.
- Water Chemistry: It is always a good practice to re-examine the boiler water chemistry. If the feed water quality has changed, this may directly impact the number of cycles the boiler can run. The impact may be positive or negative, but must be checked.
- Blow down Controller: Many boilers are manually blown down to control conductivity. With manual blow down, there are times when the conductivity is below the control range and times when it is above the control range. Automatically controlling the blow down on a boiler ensures the boiler runs within the set conductivity limits. This results in either water savings if the boiler was typically under cycled or improved steam quality if it was typically over cycled.