Environment Management in Oil Refineries - EHS guide

Petroleum refineries are generally regarded as foremost source of pollution in the areas where they are located and are governed by certain Environmental laws identified with air, land and water.

Environment Management in Oil Refineries

Environment Management in Oil Refineries

This article provides a general diagram of the forms of treatment facilities, possible associated environmental risks, permitted toxin containment points, environmental parameters for observation, constant online testing equipment and accepted pollution control procedures in oil refineries.

Petroleum refining has extended non-refined petroleum ie. Crude oil-making activities to complete refined, vaporous, liquid and solid products and operating results, including fuel gas for process facilities, LPG, motor spirit, Keo / diesel, fuel oil, bitumen, lubricating oils, waxes, sulfur, industrial coke and petrochemical intermediates (eg propane / propylene mixtures, naphtha, aromatic, central distillates and vacuum distillates). Completed commercial items are supplied by mixing different intermediate items. Processing facilities are unpredictable frameworks that are explicitly intended to create the ideal elements that depend on the properties of the raw material of the crude oil. The treatment plant forms different types of unrefined oil reserves (light, medium, overwhelming, paraffinic, aromatic, naphthenic with a variable sulfur content, such as high viscosity and density, etc.)

The most widely recognized differentiation between types of unrefined/crude oil is "sweet" and "sour". Sweet crude oil is generally low in sulfur and slightly paraffinic. Sour crude oil is normally rich in sulfur (more than 0.5% by weight) and intense naphthenic. Unrefined oils are also grouped in light, medium and substantial, depending on their paraffin, their naphthenic and aromatic substances.

Petroleum Refineries pollutants

Ecological issues related with oil refining incorporate the accompanying:

1. Emissions to environment
2. Handling and transfer of operation wastewater
3. Handling of hazardous materials and squanders
4. Noise from working hardware

1. Air pollutants

There are several sources of emissions into the atmosphere from normal emissions, volatile emissions, unintended emissions or factory malfunction, including equipment leaks (valves or other devices); combustion process at elevated temperatures during the actual combustion of fuels for power generation; steam and process liquid heating; and product transfer. The combination of volatile hydrocarbons and nitrogen oxides also contributes to the formation of ozone and these are,

1. BTEX compounds: benzene, toluene, ethylbenzene and xylene.
2. Combustion gases: particles (PM), nitrogen oxides (NOx), carbon monoxide (CO), hydrogen sulfide (H2S), sulfur dioxide (SO2), natural gas (methane) and other fuels and oils. lightweight volatile

(Fugitive emissions: may occur due to leaks in pipes, valves, fittings, flanges, gaskets, steam traps, gaskets, open ends, floating roof storage tanks and pump gaskets, gas transport systems, compressor seals, valves Pressure relief, breathing valves, open tanks or sinks / containers, oil seals, water separators and storage, loading and unloading of hydrocarbons: hydrogen, methane, ethane, ethylene, propane, propylene, butanes, butylenes, pentanes, pentenes, C6-C9 alkylate, benzene, toluene, xylenes, phenol and C9 aromatics, polycyclic aromatic hydrocarbons (PAH)) Inorganic gases, ammonia (NH3), CO, CO2, SO2, SO3, NOx, butyl methyl tertiary ether ( MTBE), butyl ethyl tertiary ether (ETBE), methyl t-amyl ether (TAME), methanol and ethanol, HF, H2S, other VOC).

 

2. Water pollutants:

Refiners are also potentially important contributors to the contamination of groundwater and surface water. Some refineries use deep injection wells to discharge wastewater generated in factories, and some of these wastes end up in aquifers and groundwater. Wastewater in refineries can be highly contaminated, given the amount of sources with which it can come into contact during the refining process (such as leaks and spills of equipment and desalination of crude oil). This contaminated water can be wastewater from the desalination process, cooling tower water, rainwater, distillation or cracking. May contain oil residues and many other hazardous wastes. This water is reused in a few stages during the refining operation and experiences a few filtration forms, including a wastewater treatment plant, before being discharge into surface waters.

Contaminants in water, such as sulfides, ammonia, suspended solids and other compounds that may be present in wastewater.

3. Soil Pollutants:

Soil contamination by refining processes is generally a less significant problem than air and water pollution. Most of the waste is produced during the refining process and recycled. Other residual materials are collected and disposed of in landfills, or they can be recovered by other facilities.

Soil contamination, including certain hazardous wastes, spent catalysts or coke dust, the bottom of the tanks and the sludge of the treatment processes, can occur due to leaks, accidents or spills on or off-site during the process of transport.

 

4. Noise (Pollutants):

The primary wellsprings of noise in oil refining operation incorporate enormous rotating machines, for example, compressors and turbines, siphons, electric motors, air coolers, blowers, fans and heaters. In addition, steam leaks/venting, if significant, can be noisy. During emergency pressure relief, high noise levels can be generated due to the high-pressure gases that are released and / or the steaming into the atmosphere.

 

Environment management in oil refineries

Monitoring of Environmental pollutants

Environmental monitoring uses different equipment and techniques, depending on the monitoring approach. Monitoring the quality of the surface water can be measured, for example, by means of remotely deployed instruments, manual instruments or by applying biomonitoring when assessing the benthic invertebrate macro-community. In addition to the techniques and instruments used in field work, remote sensing and satellite images can also be used to monitor parameters on a larger scale, such as air pollution columns or sea surface temperatures.

From a general perspective, environmental checking can be characterized as the methodical examining of air, water, soil and biota to watch and concentrate nature, and to pick up information on this procedure. Observing can be done for different purposes, including the foundation of "baselines, patterns and combined impacts" on ecology.

Inspecting of air, water and soil through natural observing can give information that can be utilized to comprehend the condition and creation of the environment and its process. Natural observing must be considered under ordinary, anomalous and crisis circumstances:

The environmental aspects of an organization under all circumstances are determined by the procedures of its environmental management system and may include:

1. Air emissions.
2. Water pollution,
3. Soil pollution,
4. Use of raw materials and natural resources.
5. Use of energy, released energy, including heat, radiation, vibrations, noise and light.
6. Production of waste and / or by-products.
7. Environmental aspects with beneficial effect.

AIR EMISSION LEVEL			EMISSION AND WASTE GENERATION
Pollutant	Units Guideline Value	Guideline Value	Parameter	Unit	Industry bench marking
NOxb	mg/Nm3	300 100 for FCCU	Wastewater	m3 /metric ton crude oil	0.1–1.51
Soxc	mg/Nm3	150 for SRU; 300 for FCCU 500	Emissions CO22 NOx3 Particulate matter SOx 4 VOC	Metric ton /million metric tons of processed crude oil	105,000–276,000 70–450 60–150 60–300 65–300
Particulate Matter (PM10) d	mg/Nm3	25
Vanadium e	mg/Nm3	5
Nickel	mg/Nm3	1
H2S	mg/Nm3	5

Liquid Effluents Levels
Pollutant	Units	Guideline Value
Lead	mg/L	0.1
Nickel	mg/L	0.5
Mercury	mg/L	0.003d
Arsenic	mg/L	0.1
Vanadium	mg/L	1
Phenol	mg/L	0.2
Benzene	mg/L	0.05e
Benzo (a) pyrene	mg/L	0.05
Sulfides	mg/L	0.2
Total Nitrogen	mg/L	10f
Total Phosphorus	mg/L	2
Temperature increase	mg/L	<3g
Cyanide Total Free	mg/L	1 0.1
Iron	mg/L	3
Copper	mg/L	0.5
Chromium (hexavalent)	mg/L	0.005
Chromium (total)	mg/L	0.5
Oil and Grease	mg/L	10
Total Suspended Solids (TSS)	mg/L	30
COD	mg/L	125 c
BOD5	mg/L	30 b
pH	S.U.	6 – 9

Fence Line Monitoring Action Level
Pollutant	Unit	Guideline value
Benzene	µg/m3 a	9

Resource and Energy Consumption
Parameter	Definition of Parameter	Unit	Industry Benchmark
Total Energy Consumption	Total energy consumed by the process, including direct combustion, steam, electricity, etc.	MJ per metric ton of processed crude oil	2,300–3,300
Electric Power Consumption	Total electricity consumed by the process	kWh per metric ton of processed crude oil	22–31
Fresh Make-up Water	The supply of raw filtered water that integrates drift and evaporation losses as well as blow-down	m3 per metric ton of processed crude oil	0.07–0.66

Petroleum Refineries pollution prevention and control measures

Adoption of different process technologies and environment monitoring with industrial, national, and international bench marking helps to prevent and control the pollution.

Air Pollutant prevention and control measures

Continuous online air quality monitor

Pollution prevention measures for process heater

For process heaters, the following main measures to prevent and control pollution should be considered:

1. To increase the efficiency of the furnace, combustion air preheaters and an advanced control of the operating variables (temperature and oxygen concentration of the flue gases to optimize combustion, the air / fuel ratio for the mixture of combustion must be installed, fuel must be continuously monitored; optimization of excess air to minimize heat loss from unburned gases or unburned wastes).
2. High thermal efficiency designs with good control systems (eg oxygen deposition).
3. Energy requirements can be minimized by using pumps, fans and other highly efficient equipment.
4. Prevention of condensation of exhaust gases on surfaces.
5. Proper operation and control, a constant supply of liquid fuel in secondary heating, a good mixture of exhaust gases and a catalytic afterburner can regulate CO emissions.
6. To improve heat transfer by radiation, high emission refractory materials can be provided, for example, by applying ceramic coatings as reflective surfaces.
7. Regular cleaning of the heating surface (soot blowing) for liquid fuels or mixed fires.

Pollution prevention measures for flare and venting

For venting and flaring system, the following pollution prevention and control measures should be considered:

1. The emission of emergency openings in the process and the discharges of the safety valves are collected in the purge network that is exhausted.
2. A flare gas extraction system must be used for the planned start and stop.
3. In non-emergency situations, excess gas from process openings should be recovered or regulated and the volume of gas to be burned should be minimized.
4. Burning changes, the chemical nature of substances emitted by incineration.
5. Before adopting burning, viable alternatives to the use of gas should be evaluated and integrated as much as possible in the production design.
6. Burned gas volumes should be recorded for all burning activities. Torch management plans must be developed and implemented. Burning volumes for new facilities must be estimated during the initial commissioning period so that fixed volume burning targets can be developed.
7. Use of efficient torch tips, that is, an optimal sonic speed released, to prevent torch malfunction due to its flames and to optimize the size and number of burner nozzles.
8. Limit flaring and decontamination pilots, without trading off wellbeing, through measures that incorporate the establishment of purge gas decrease gears, flare gas recuperation units (for the most part for ceaseless or unsurprising conveyance), a deactivation drum upstream (vapor fluid separator used to forestall fluid entrancement to the flare), soft seat valve innovation (if relevant), preservation pilots, utilization of latent cleanse gas and the redirection of streams to the water arrange fuel gas dispersion of the processing plant. Greatest ignition proficiency of the flare by controlling and advancing the fuel/air/steam stream paces of the flare to guarantee the right connection between the assistant stream and the flare stream.
9. Minimize the risk of flying the pilot ensuring sufficient speed from the point of departure and providing windshield.
10. Use of a reliable self-ignition system for pilots.
11. Minimize entrained liquid and entrainment in the gas torch flow with an appropriate liquid separation system
12. Installation of highly reliable instrument pressure protection systems, if necessary, to reduce over pressure events and to prevent or reduce torches.
13. Minimize the flame light (flash off) and lick the flame (flashback).
14. Work with torches to control odours and visible smoke emissions using appropriate optical instruments, such as flame detectors, that react to steam injection in the event of black smoke at the tip.
15. Implement burner maintenance planning and replacement programs to ensure maximum continuous torch efficiency
16. Monthly measurement of flame gases in order to assess pollution, mainly in terms of CO2 and SO2, as well as the heat released (which is an indirect estimate of greenhouse gas emissions).
17. Avoid a flame dominated by the wake. A strong high speed crosswind can have a powerful effect on the size and shape of the torch flame, so that the flame is dominated by the wake (ie the torch leans on the side of the torch in the wind and is embedded in the aftermath of the torch point), thereby reducing torch performance and possibly damaging the torch spot
18. Avoid excessive steam because too much steam in a torch reduces the performance of the torch.
19.  To minimize flaring due to equipment malfunctions and installation problems, the reliability of the installation must be high (> 95%).
20. Avoid turning off the flame, a state where a flame separates from the tip of the torch and there is a space between the tip of the torch and the bottom of the flame due to excessive induction of air due to gas outlet rates of the torch and central vapor. This type of flame can reduce the operation of the torch and can develop into a state in which the flame is completely extinguished.

Pollution prevention measures for Fugitive emission

Fugitive Emissions (FE), the following primary measures to prevent and control pollution must be considered:

1. The Leak Detection and Repair Program (LDAR) can be implemented based on a systematic P & ID assessment.
2. When selecting suitable valves, seals, flanges, fittings and seals, their effectiveness in reducing gas leaks and diffuse emissions must be taken into account.
3. For petroleum storage tanks, the nitrogen blanket system and the internal floating roof system minimize the release of FE into the atmosphere.
4. The use of vent gas scrubber should be considered to remove oil and other products with a higher vapor oxidation in specific units (eg Bitumen production, loading gantries).
5. Installation of a vapor recovery unit, instead of releasing the vapour into atmosphere or to flare system.
6. Gas combustion must be carried out at a high temperature (around 800 ° C) to ensure complete destruction of minor components (e.g., H2S, aldehydes, organic acids and phenolic components) and to reduce emissions and the influence of odours.
7. Assure the vapor control system (vapor recovery units) during loading and unloading of naphtha, motor spirit, methanol / ethanol and ethers.
8. The ventilation openings of the alkylation plant must be collected and neutralized for HF in a gas washer before introducing in to flare system.

Control measures for nitrogen oxides emission

Nitrogen oxides, the following main measures to prevent and control pollution must be considered:

1. Low NOx burners can be installed in combustion appliances.
2. The ammonia (NH 3) formed during the hydrodesulfurization process of naphtha and diesel is introduced as a component of the acid feed gas into the SRU thermal reactor and converted to NOx fuel.
3. Taking into account technologies for selective catalytic reduction (RCS) or thermal NOx.
4. Includes high temperature air combustion (HiTAC), also known as flameless (or colourless) combustion. With the use of HiTAC, poor gas streams can be burned with uniform thermal fields without the need for fuel enrichment or addition of oxygen.
5. The uniform temperature distribution promotes clean and efficient combustion, with the added benefit of a significant reduction in NOx, CO and hydrocarbon emissions.

  

Control measures for sulphur di-oxides emission

Sulphur oxides, the following main measures to prevent and control pollution:

1. Minimize SOx emissions by desulfurizing fuels, as much as possible, or by targeting the use of high sulfur fuels in units equipped with SOx emission controls.
2. Recover sulfur from exhaust gases using very efficient SRUs, such as Claus units equipped with the specific exhaust gas treatment section.
3. Install scrubbers with sodium hydroxide solution to treat the flue gases from the absorption towers of the alkylation unit.

(Refinery streams containing sulfur are generally directed to hydrotreatment units where hydrogen is combined with sulfur to form H2S, then directed to the Amina unit, from which a single stream is sent, to a high concentration of H2S, towards SRU, generally based on Claus Process.)

 

Environment management in oil refineries

Control measures for particulate matter emission

Particulate matter, the following main measures to prevent and control pollution should be considered:

1. Precipitates, purifiers, third-phase cyclones associated with NOx and SOx emission control technologies (for example, wet gas washers).
2. The combination of these techniques can allow particle reduction of> 99%.
3. Implement techniques to reduce particulate emissions during the treatment of coke, in particular:
4. Keep the coke under closed shelters,
5. Keep the coke constantly moist
6. Cut the coke in a grinder and take it to an intermediate storage silo.
7. Spray the coke with a thin layer of hydrocarbon/GO, to stick the fine dust on the coke,
8. Use conveyor belts covered with extraction systems to maintain negative pressure,
9. Use extraction systems to extract and collect coke dust,
10. Transfer the collected fines from the cyclones pneumatically to a silo with exhaust air filters and recycle the collected fines for storage.
11. Consider, for example, replacing fuel, replacing heavy fuel with light fuel oil, natural gas, or refinery gas.

Control measures for greenhouse gases emission

Greenhouse gases, the following main measures to prevent and control pollution should be considered:

During the design phase or when major renovation improvements are contemplated, improvement of stationary sources of combustion (ie steam boilers, process heaters, combined heat and power), improvement of systems flammable gas and flare should be considered, and the installation of energy recovery / residual heat recovery units. Limiting greenhouse gas emissions (carbon dioxide (CO2) and methane (CH4) are most of the greenhouse gases).

Water Pollutant prevention and control measures

Inhibition and control of accidental release of liquids through periodic inspections and maintenance of storage and transport systems, including pump packaging and valves and other potential leakage points, as well as the implementation of spill control plans.

Providing sufficient capacity to store treatment fluids to allow maximum recovery in the process and, therefore, to avoid large discharges of treatment fluids in the oily wastewater drainage system.

Design and construction of wastewater and hazardous materials storage basins with sufficient waterproof surfaces to prevent infiltration of contaminated water into the soil and groundwater.

Separation of wastewater for storm water treatment and separation of wastewater basins and basins for hazardous substances.

Implementation of good maintenance practices, including the realization of product transfer activities in paved areas and the rapid collection of small amounts of spills.

Install a closed process drainage system to trap and repair leaks and spills of MTBE, ETBE and TAME. These substances do not respond to biological treatment and the ETP must be prevented from entering and damaging.

Direct spent caustic soda from chemical and softening treatment units to the wastewater treatment system after corrosive oxidation.

Direct the used liquor from corrosive oxidation (containing thiosulfates, sulphites and soluble sulfates) to the wastewater treatment system.

If present in the installation, the acidic and corrosive wastewater from the demineralized water preparation must be neutralized before being discharged into the wastewater treatment system.

Cold rinse of steam generation systems before discharge. These wastewaters, as well as the rinse of the cooling towers, may contain additives (for example, biocides) that may need to be treated in the ETP before they are discharged.

Water contaminated with oil from planned cleaning activities during the repair of the installation and wastewater containing oil from process leaks must be treated at the ETP.

Contaminated streams should be directed to the industrial ETP.

Hydrostatic test water (equipment and pipes includes a water pressure test) must be used for different tests.

Reduce the need for corrosion inhibitors and other chemicals by minimizing the time the test water stays in equipment or pipes.

If the discharge of hydrotest water into the sea or surface water is the only viable alternative to disposal, a hydrotest water retention plan must be developed taking into account the discharge points, the rejection rate, the use and the distribution of chemicals, environmental risks and the required monitoring. The hydraulic test of water drainage in shallow coastal waters should be avoided.

If chemical products are necessary, select effective chemicals with the least toxicity, bioavailability and bio-accumulative potential and the highest biodegradability.

Soil Pollutant prevention and control measures

Spent catalysts:

Environment management in oil refineries

There are different types of spent catalysts and their physicochemical properties influence their handling. The two most important considerations are whether the specific catalyst is of a "hazardous" or "non-hazardous" nature and if the metal or metals they contain are expensive or recoverable. An analysis of these factors will directly influence the treatment of a used catalyst.

The following primary measures to prevent and control pollution should be considered:

1. Use catalysts with a long service life and regeneration to extend the life of the catalyst.
2. Use proper storage and handling methods on site to avoid uncontrolled exothermic reactions.
3. Return used catalysts to the manufacturer for regeneration or recovery, or transport them to other external management companies for the treatment, recovery / recycling of heavy or precious metals and their disposal in accordance with the recommendations for industrial waste management.

 

 Other Hazardous Wastes:

(Solvents; filters, mineral alcohol, sweetener used, used amines for the removal of CO2, H2S and carbonyl sulfide (COS); activated carbon filters and oily sludges from oil / water separators and desalination plants; emulsions or bottom of tanks; and consumed or used in operation and maintenance fluids (for example oils and test fluids), contaminated sludge, sludge from the purification circuit of the jet water pump, depleted molecular sieves and depleted aluminium oxide by HF alkylation can be generated from crude oil storage tanks, desalination and cover, coke, propane, propylene, butane dryers and isomerization of butanes: ETPs and basins / lagoons generate sludge which can be considered as hazardous waste, depending on the treatment process itself and the incoming wastewater).

The following main measures to prevent and control pollution should be considered:

Process waste must be tested and classified as hazardous or non-hazardous in accordance with local legal requirements or internationally accepted approaches.

Send oily sludge, such as those for crude oil storage tanks (bottom drains) and desalination plants (bottom drains); delayed coke drum, if any, to recover the valuable oil.

Make sure there are no excessive cracking process in vibreaker unit to prevent the production of unstable fuel oil, which would increase sediment and sediment formation during storage.

Maximize oil extraction from wastewater and oily sludge. Minimize oil losses in the wastewater system. Oil can be extracted from the waste using separation techniques (for example, gravity separators and centrifuges).

Sludge treatment can include soil application (bioremediation) or solvent extraction, followed by combustion of the residue and / or use in asphalt or cement kilns, if possible. In some cases, the residue must be stabilized before being removed to reduce the leachability of toxic metals. If left untreated, hazardous sludge from crude oil refineries must be disposed of in a secure landfill, in accordance with the hazardous waste management procedure.

 

 Non-Hazardous Wastes

(HF alkylation produces neutralization sludge, which may contain calcium fluoride, calcium hydroxide, calcium carbonate, magnesium fluoride, magnesium hydroxide and magnesium carbonate)

 After drying and compression, they may be marketed for uses in steel mills, for or land filled.

Summary

Modern technology used in refineries and best engineering practices reduces the emission of environmental pollutants. Continuous online monitoring though fixed analyzer with ultra-high accuracy instruments helps to control the pollution. Although robust Environment Management System with clear commitment toward green environment is need of petroleum refineries for sustainable business. 

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