Best Practice SABP-S-001 Hydrocarbon Tank Cleaning Methods
1 November 2015
Document Responsibility: Environmental Standards Committee
Saudi Aramco DeskTop Standards Table of Contents
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Introduction.................................................... 2
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Conflict with Mandatory Standards................ 3
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References.................................................... 3
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Definitions...................................................... 4
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Technology Selection Criteria………..…….... 5
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Pre-T&I Requirements………....………...…... 5
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Tank Cleaning Technologies………………… 6
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Current Practices for the Management of Tank Bottoms............. 10
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Safety Precautionary Measures…………… 10
Next Planned Update: TBD Page 1 of 10
Primary contact: Buraikan, Tamim Abdulrazzaq (buraikta) on +966-13-8800433 Copyright©Saudi Aramco 2015. All rights reserved.
Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
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SABP-S-001 Hydrocarbon Tank Cleaning Methods
Introduction 1.1
Overview Oily sludge generated from tank bottoms is one of the major waste management issues in the petroleum industry. Manual cleaning methods for large crude oil tanks are mainly practiced in Saudi Aramco, which are labor intensive, poses health and environmental risks, does not recover hydrocarbons from oily sludge, that is high of BTU value, for beneficial re-use, generates large quantities of hazardous waste that are typically disposed of in landfarms, and requires considerable idle time. Therefore, it is important to address this issue to recover hydrocarbons for beneficial re-use, reduce worker exposure to safety hazards, and minimize the amount of waste generated, and any possible land and groundwater contamination as a result of land-farming practices.
1.2
Purpose This document establishes tank cleaning best practices to be used by Saudi Aramco’s operating facilities during periodic T&I which will enhance the personnel’s health and safety and will lead to financial benefits by recovering the sludge. This document will also aid operating facilities in the selection of the best available technology that is in line with their systems, design conditions, and procedures, and their requirements. Regular maintenance tank cleaning can be conducted in a way that are economical, safe, profitable and with minimum impact on the environment.
1.3
Scope This Best Practice gives general guidance to operating facilities and provides tank bottom waste generators with options available for tank cleaning technologies. It covers the criteria for selecting a tank cleaning technology based on site specific factors, safety, environment, mobility, etc., and presents the available proven technologies which emphasizes on automation and nonman entry practices. This document is addressed to proponent organizations that operate hydrocarbon storage tanks including refineries, central processing facilities, terminals, and oil stabilization facilities.
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Disclaimer This Best Practice is provided for the general guidance and benefit of Saudi Aramco operating facilities. The use of the information or material contained in this document will not relieve operating facilities from the responsibility of safeguarding and controlling their operations as it is established in other guidelines such as GI's and engineering standards. During the process of Page 2 of 10
Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
SABP-S-001 Hydrocarbon Tank Cleaning Methods
developing this best practice, EPD has identified various hydrocarbon tank cleaning technologies. However, there could be other technologies, not illustrated in this document, that can achieve the same objectives. 2
Conflict with Mandatory Standards In the event of a conflict between this Best Practice and other Mandatory Saudi Aramco Engineering Requirements, the Mandatory Saudi Aramco Engineering Requirements shall govern.
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References 3.1
Saudi Aramco Documents Saudi Aramco Engineering Procedures SAEP-1161
Testing and Inspection (T&I) Reporting Procedure
SAEP-1662
Cleaning of Heat Exchangers and Unfired Plant Equipment
Saudi Aramco Engineering Standards SAES-A-104
Wastewater Treatment, Reuse and Disposal
SAES-S-007
Solid Waste Landfill Requirements
General Instruction GI-0430.001
Implementing the Saudi Aramco Hazardous Waste Code
Saudi Aramco Engineering Report ECR-02/01-T
Tank Cleaning Technology Initiative
Saudi Aramco Hazardous Waste Code 3.2
Governmental Standard PME GER Rules for Implementation; Appendix III 2014 PME Environmental Protection Standards - Ambient Air Quality - Control of Emissions to Air for Stationary Source
3.3
International Standards American Petroleum Institute API E5
Crude Oil Tank Bottoms and Oily Debris
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Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
3.4
SABP-S-001 Hydrocarbon Tank Cleaning Methods
Published References https://www.google.com/patents/US5776257 http://www.a-hak-is.com/en/home/what_we_do/services/storage_tank_services/desludging https://www.go-dove.com/auctions/brochures/5334_3464.pdf http://www.rendelin.it/images/BLABO-sistema.gif http://images.pennwellnet.com/ogj/images/ogj2/9648jbo01.gif
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Definitions Centrifugation: It is a physical process that separates oil from water and solids by mechanically-enhanced gravity. This method is a win-win situation for the environment and the waste generators since it minimizes the amount of waste generated for disposal, hence disposal costs and the generator can recover the oil and gain profit out of it. Highly emulsified wastes; waste in which the oil, water, or solids have similar densities; or wastes in which the oil is contaminated so that it cannot be reused, would not be suitable for centrifugation. GER: General Environmental Regulations, the PME regulations related to the Environment. Hazardous Waste: Wastes, which constitute a high degree of hazard to the public health and the environment. This includes material, which is flammable, corrosive, reactive, toxic, radioactive, infectious, carcinogenic, mutagenic or teratogenic. Landfarming: It is a bioremediation treatment process that is performed in the upper soil zone or in biotreatment cells. Contaminated soils, sediments, or sludges are incorporated into the soil surface and periodically turned over (tilled) to aerate the mixture. Landfarming is relatively cheaper in comparison with other recovery technologies. However, landfarming is considered the least effective waste management option as its difficult to control especially in the harsh environment of Saudi Arabia. Oily Sludge: A complex emulsion of various petroleum hydrocarbons water, heavy metals, and solid particles. Oily Waste: Fluids and oils that are either designed to be mixed, or may be mixed with no harmful effects are often referred to as compatible.
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Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
SABP-S-001 Hydrocarbon Tank Cleaning Methods
PME: Presidency of Meteorology and Environment; the Kingdom’s environmental regulator [established under Royal Decree No. 7/M/8903, dated 21/4/1401 H (25 February 1981). T&I: Testing and Inspection. Refer to SAEP-1161. Thermal Desorption: It is a technology that separates volatile compounds from nonvolatile (sand and scale) such that they can be removed (separated) from the solid matrix (typically soil, sludge or filter cake). The volatilized contaminants are then either collected or thermally destroyed. A thermal desorption system therefore has two major components; the desorber itself and the off-gas treatment system. 5
Technology Selection Criteria Proponent organizations are advised to use a tank cleaning method or technology which meets the following conditions:
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1.
Minimum disturbance to operation,
2.
No or minimum exposure of personnel inside the tank (i.e., technology is fully automated),
3.
Maximum oil recovery from oily sludge,
4.
No or minimum waste generation from tank bottoms,
5.
A technology or a method that utilizes the minimum resources needed for cleaning,
6.
A technology or a method that requires no or low design modifications to the crude oil storage tanks intended for cleaning,
7.
A technology used for tank cleaning must be mobile,
8.
A technology used for tank cleaning must comply with minimum hydrocarbon emissions and polluting effluents,
9.
A technology used for tank cleaning must comply with Saudi Aramco applicable standards with regard to health safety requirements.
Pre-T&I Requirements Test and Inspection activities shall comply with SAEP-1161 “Testing and Inspection (T&I) Reporting Procedure.”
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Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
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SABP-S-001 Hydrocarbon Tank Cleaning Methods
Tank Cleaning Technologies Commercially available mechanical tank cleaning technologies, other than manual cleaning, fall under two principle categories: (1) circulation of cleaning fluids through nozzles installed inside the tank, and (2) use of immersible robotic devices to extract tank sludge. 7.1
Circulation of cleaning fluids through nozzles installed inside the tank. -
Crude Oil Washing System (COWS): Tank bottoms are washed with crude oil until the quality of fresh crude oil and recovered oil are the same. Afterwards, the tank is washed with hot water. The floating hydrocarbon is separated and returned to an oil storage tank and the water is discharged to the oily water sump for further processing.
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Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
7.2
SABP-S-001 Hydrocarbon Tank Cleaning Methods
Use of robotic devices to extract tank sludge: a)
MegaMacs: Oily sludge is removed mechanically (i.e., sludge extractors) through hot water nozzles installed inside the tank. The effluent is sent to a three-phase centrifuge where oil, water, and solids are separated. The recovered oil is sent to a nearby tank, the water is sent to a wastewater treatment unit and the solids are sent for disposal at an approved waste management facility.
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Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
b.
SABP-S-001 Hydrocarbon Tank Cleaning Methods
Balbo: Automated non-man entry tank cleaning method in which crude oil is used as the washing media for oily sludge. Nozzles are installed at the roof through existing openings. Crude oil is heated in a circulation module and sent back to tank to mix with oily sludge. After that, the mixed waste is sent to hydro cyclone to separate any heavy solids. The mixed waste is sent to a skimming module to recover oil from water.
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Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
c.
Note:
SABP-S-001 Hydrocarbon Tank Cleaning Methods
Gas tight tank cleaning: A robotic tank cleaning system is introduced through the temporary seal into the tank. The tank interior is sprayed with diluent to remove liquid and solid volatile organic compound (VOC) generating residue. VOC's are removed from the tank by repetitive diesel and water/surfactant fogging until a safe, legal level of VOC's remains in the tank atmosphere. The liquefied effluent exiting the tank is sent to the processing equipment that included screeners and centrifuges. Recovered water from processing was used by the tank entry device to liquefy the sludge in the tank. Solids are moved out of the tank as a result of jetting. Recovered oil from the centrifuge units are sent back for re-processing or storage.
The above figures are provided for clarification purposes only and EPD does not exclude other technologies that can achieve the same objectives.
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Document Responsibility: Environmental Standards Committee Issue Date: 1 November 2015 Next Planned Update: TBD
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SABP-S-001 Hydrocarbon Tank Cleaning Methods
Current Practices for the Management of Tank Bottoms Several current practices have been cited as follows. EPD strongly recommends that a comprehensive evaluation is conducted from health and environmental point of view prior to pursuing them.
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1.
Utilizing mixers installed on the sidewalls to agitate the oily sludge prior to the T&I event. This practice is used by Terminal Operations and Maintenance Departments.
2.
Liquefying tank bottoms by spraying kerosene on the oily sludge and applying mixers to agitate the blend. This practice is used by Yanbu Refinery Department.
3.
Tank bottoms are directed to a lined lagoon and the fed into a centrifugation unit to separate oily sludge into oil, water, and solids. The recovered oil is re-processed and the water is sent to the industrial wastewater treatment plant. The solids are sent to a thermal desorption unit for further treatment prior to final disposal. This practice is used by SASREF Refinery.
Safety Precautionary Measures All safety requirements shall be complied with; for example Job Safety Analysis (JSA) prior to the commencement of cleaning activities.
1 November 2015
Revision Summary New Saudi Aramco Best Practice that establishes tank cleaning best practices to be used by Saudi Aramco’s operating facilities during periodic T&I which will enhance the personnel’s health and safety and will lead to financial benefits by recovering the sludge. This document will also aid operating facilities in the selection of the best available technology that is in line with their systems, design conditions, procedures, and their requirements.
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