Mechanical Cleaning
Build up of petroleum coke on the inner tube surface; coke is formed as a thermally cracked fraction of the hot oil product.
The challenge
Fouling within process tubes and piping systems compromises flow assurance, production rates and can lead to accelerated corrosion.
Within heat exchange tube systems such fouling can cause overheating which compromises integrity and may lead to catastrophic failure.
The nature and morphology of fouling depends on the product, process conditions and system design. Within crude oil systems it can manifest as petroleum coke (potentially including inorganic material) and as scale within steam generation systems. Historically, a variety of techniques have existed to remove such contamination. Mechanical cleaning, also known widely as pig decoking or pigging, has become the preferred method throughout the industry.
Older techniques such as steam air decoking and hydroblasting have varying degrees of success, depending on the competence of the tooling and personnel skills. There can be adverse side effects such as increased environmental load and potential asset damage.
The solution
With some 20 years of world wide experience, Cokebusters have developed, deployed and refined an integrated solution to comprehensively clean such systems.
Our service-led solution involves connecting our Double Pumping Unit machine to the tube/pipeline asset and progressively scraping away layers of coke/scale with incrementally sized mechanical pigs.
Scraper pigs are propelled by pressurised water flow supplied by our Pumping Unit. This operation is managed from the machine’s on-board control room by our personnel. Use of water carries all the debris allowing back to the machine for subsequent filtration and disposal.
Mechanical Pigs
The mechanical scraper pigs are built in house to a patented design. There are some 50 different incremental pig sizes, ranging from 1”-12” diameter. We can manufacturer ‘off spec’ to suit particular requirements.
The ability to design and build in house allows Cokebusters to be in control of its own supply chain. It also means we can respond quickly to customisation requests.
Key Features:
- All our pigs have stud pattern options which are designed subject to task
- Material hardness ratings (Shore A) can be adjusted to suit not only the task but also to aid process tube navigation
- Designed to ensure 360° circumferential coverage of bends and pipework
- Able to manoeuvre short radius return bends, plug headers, mule ears & flat-back bends
- Bi-directional operation and control
- Low pressure operation (typical operational pressure of 250psi)
- Continuous monitoring of pressure, flow and pig positioning
- Residual water can be removed from process pipework following operations if required
- Full passivation procedure for stainless steel tubing as per NACE standard RP0170 requirements can be additionally provided
Series 21 Double Pumping Unit
Commonly referred to as a DPU – a purpose built trailer, or containerised unit, which contains all the equipment and functionality to connect and deploy mechanical ‘scraper’ pigs. The unit has four basic elements:
- manned control room
- water handling tanks
- double pumping engines
- all connection equipment and tooling
All our pumping units are designed, built and maintained in house.
On board two stage filtration can separate particles down to 750µm.
Our on board InnerVision™ system is used to monitor the cleaning performance using various process signatures.
Cokebusters’ DPU are strategically located in the regions we serve.
Application
- Removal of coke contamination from fired heater process tube assets includes: Delayed Coker, Crude Distillation, Visbreaker, Vacuum Distillation along with a wide variety of charge heaters and process boilers
- Removal of coke contamination from transfer lines
- Removal of internal scale from HRSG / OTSG boilers and solar steam generation systems
- Descaling, dewatering, slug removal and purging of pipework and pipelines
- Pre-cleaning prior to intelligent pig inspection
Advantages
- Incremental mechanical cleaning, using scraper pigs, is considered to be the most thorough process and least likely to create tube wall damage
- The debris is suspended in solution for recovery through 2 stage filtration. This minimises atmospheric losses
- All equipment is designed and built in house, meaning that any machinery interventions can be facilitated by Cokebusters personnel on site
- All our personnel are graded by examination and experience
- Alternative pig designs can be accommodated to suite unique applications
- Test loops at our premises enable operators to be process trained and new technologies to be evaluated before attending site
Environmental Policy