Pipeline Cleaning

The complexity of gas and oil pipelines has not substantially changed, but the demands for pipeline cleaning and de-scaling have. Millions of dollars are at stake in lost production time and equipment costs if pipelines have to be dismantled to be cleaned.

The key for pipeline cleaning and specialist companies such as Tube Tech International, is the ability to bring innovative thought to problems that have always bedeviled the petrochemical industry. Indeed, the company's reputation is growing rapidly on the back of the proposal that won it a three-year contract with Nigeria LNG Ltd (NLNG).1

Problems at the gas processing plant in the West African state, which opened in 1999, were classified as 'uncleanable'. Condenser, heat exchanger tubes, and pipelines had become seriously contaminated by deposit, and millions of dollars in new equipment and downtime were at stake if the complex system had to be dismantled.

Tube Tech won the initial pipeline cleaning and de-scaling contract on three grounds:
* A pledge that production loss would be minimal because none of the pipelines would need to be cut
* Work in Nigeria could start within two weeks
* Regardless of dimension ( 2 - 36 in) deposit could be cleaned

Work began immediately at the company's headquarters in Essex , England , focusing on the logistics on getting 32 multi-disciplined operatives and 46 t of cleaning and de-scaling equipment on site at Bonny Island as soon as possible.

Project planning was also started, involving 12km of pipeline and 60,000 heat exchanger tubes. With a convolution of bends and 'T-offs in a maze of differing diameters of pipe work, there was no 'one size fits all' cure. In the event, the project team came up with a combination of 12 techniques to clear highly stubborn scale and blockages.

An airborne assault was organized, and 3 cargo aircraft of equipment were off- loaded in Nigeria just 2 weeks after the initial site visit. Working continuous day and night shifts in frequently extreme weather conditions the teams completed the cleaning and integrity inspection three times faster than the nearest competing estimate.

The plant was quickly restored to full production using 12 techniques. The first cleaning system was a novel 'mini pig', only 150mm in length and conforming to the tube internal diameter. Propelled by water, the rotating blades only extended as far as the tube diameter and not beyond, thereby avoiding any damage.
The middle third of the dart houses a rotating bladed turbine, and with a water pressure of 500 psi, these blades (emulating the turbine blades on an aircraft engine) are forced to rotate at a speed of approximately 4000rpm.
In this instance, the scale causing the blockage consisted of calcium and iron oxide product. The rotating blades remove impeding scale in their path at a travel rate averaging out at approximately 2 m/s. using this method, pipe work can be cleaned in a matter of hours rather than days.
This particular turbine blade is entirely bespoke and manufactured by hand in materials that can be ferrous or non-ferrous. Tube Tech has a wide range of Dartts(TM) to suit diameters ranging from 10mm to one metre.

A second system used at Bonny Island was a traditional, automated high-pressure water-jetting lance, but this was modified by Tube Tech to create a new, more effective, method for the smaller pipes. Its engineers adapted this system by modifying the traditional high pressure jetting hose system, which normally reaches a maximum pipe length of 400m, so that it can extend as far as 2km.

A further 10 systems were also mobilised, thereby avoiding the worst case scenario of substantial downtime at Bonny Island and the vast financial impact that would be implicit.

There was also a considerable amount of pipe work that was deemed 'un-pigable' by the client, but it too required cleaning and de-scaling as part of the contract.

Cutting is costly
The only solution option proffered by many experts at that time was either to fill the entire arterial network of pipe with acid or to cut into the pipeline and pressure jet.

However, along with this option came environmental implications and costs. There were also considerable safety issues, as well as the cost of cutting the pipe open at various points.

Tube Tech went ahead with an environmentally sound solution using non-standard pigging. The volume of scale built up in the pipeline was such that it needed to be cleaned over the whole surface area, or the flow rate would have been compromised. The result was that more than 40 t of iron oxide and calcium water scale was removed using a variety of innovative pigging processes and types, including:

o Pigs that could be inserted into a 25mm aperture and inflated to match the given pipe diameter.
o Bi-directional pigs adapted with pressure bypass valves so that, in the event of sticking due to the volume of deposits ahead, the increased water back pressure would engage a solenoid in the nose of the pig, turning it into a pressure-jetting nozzle.

o Pigs fired with a guide wire attached so they could be retracted
o A biodegradable pig was developed to break down at the end of a potential dead-end run. This would have negated the need to cut into the pipe, as well as alleviating any risk of losing it. This particular pigging solution had been developed prior to the project.

Once the pipeline cleaning and de-scaling work had been completed. Tube Tech also put both closed circuit TV and wall thickness integrity assessment inspection equipment into action. This enabled technicians to inspect the wall thickness of the pipes electronically rather than by using expensive intelligent pigging.

The competition
While there are many pipeline cleaning systems available from global sources, with every successful contract Tube Tech has frequently found the basic equipment to be inadequate for dealing with the problems specific to each contract.

It is client's increased dislike of the environmentally unsound chemical route and the costly cutting method that has led to the development of bespoke solutions by the research team. With this 'applied innovation' in conjunction with an in-depth study of the system, the company has changed the rules of pigging and exchanger cleaning by inventing new pigs and tube cleaning processes.

In the case of the Nigeria contract, the client approached a number of other companies, but none were able to offer more than three cleaning techniques involving either acid cleaning, cutting into the pipeline or high volume water jetting. Tube Tech's involvement came through the recommendation of Shell Global Solutions International (SGSI). Without using any of these options, Tube Tech was armed with 12 techniques tailored to the varying consistencies and volumes facing them. The loss of efficiency translated quickly into financial loss, which was why the client was looking for a fast, effective cure.

The reward for restoring production to 100% was the three-year contract for further work. This has included advice on fouling mitigation procedures to prevent further scale blockages, particularly with the introduction of vital measures for sound quality water treatment.

While pipeline blockages are eminently treatable with expertise, there is a cause for a rethink on several fronts where prevention is better than cure. Process pipelines are not often manufactured with a view to cleanability. Tube Tech can offer end users and plant fabricators proven advice on how to modify them so that, rather than fighting fires are serious problems arise, a rethink at the manufacturing stage can tackle the root causes of scaling and blockages to out-engineer the problem.

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A Description of Shell and Tube Heat Exchangers

Shell and tube heat exchangers are needed for high-pressure applications; they are durable products, which can withstand the demands of many working environments. Their design plays a large part in ashell and tube exchanger's ability to endure exceedingly-challenging situations.

Shell and tube heat exchangers are made from a series of tubes, which can be made of durable material such as fluoropolymers. Fluoropolymers are highly-durable plastics such as PTFE, FEP, and PFA. Fluoropolymers, like heat exchangers, have a place in a variety of industries such as the automotive, medical, and aeronautical.

In a exchanger's shell, one set of tubes contains fluid, which is either heated or cooled. Another set of tubes also contains liquid, which facilitates the heating or cooling of the primary set of tubes. A tube set is referred to as the tube bundle and can take on a variety of shapes depending on what is most conducive for the intended job.

Engineers of shell and tube heat exchangers need to consider several components of construction:

A smaller tube diameter enables the shell and tube exchanger to be economical and compact, yet a tiny diameter can facilitate malfunction and difficulty of cleaning. Larger tubing can be instituted to eradicate potential flow and cleaning problems. Engineers must factor cost, space, and the propensity of liquids to foul when constructing a heat exchanger.

Tube thickness is important to make sure there is room for corrosion; vibration existing in the product has resistance; and, the shell and tube exchanger can withstand pressure coming from both in and outside of its internal tubes.Folding or wrinkling the inner tubes increases the flow of the liquid, which facilitates the transfer of heat, producing better performance from the exchanger.

Designers also consider the layout of the inner tubes. Tubes can be fashioned in a triangular, square, rotated square, or rotated triangular fashion. Particular, internal designs are conducive to specific jobs and the elimination of potential problems such as fouling of the liquid.

Shell and tube heat exchangers also host baffle components. Baffles serve several purposes such as holding the tube bundles in place; making sure tubes do not sag or vibrate; and, facilitating fluid flow.

Intel Atom - The Reactor That Powers Netbooks & Nettops

Intel Atom's family of processors are unique. They were designed to be general purpose processors. Yet, the most important feature is the extremely low power consumption. Intel positions these processors for the Netbook and nettop devices.

Netbooks are a new category of portable laptop/notebook family. Manufacturers aim these lightweight devices for people on the move. Most important applications on the move should provide the ability to receive and send emails, IMs and surf the net. General purpose productivity applications are not that important, though they would be able to run these applications in a pinch. 

Typically, a 10" display and corresponding smaller size and weight sets these apart. The way Intel defines the Nettops as a category of devices aimed at content consumption rather than content creation such as, browsing web pages, watching online video streaming etc. They see it as the tool the next billion users would use. Besides these are aimed at consumer electronic devices, embedded systems and thin clients.

It is easy to see that this category is going to be very popular. The Netbooks are already almost everywhere. So much so, that for a two year commitment you can get these Netbooks for $99 kind of prices. The commitment is to use the 3G communication services from these mobile services providers. This is the kind of connection that gives you mobility and bandwidth for operation. It is not difficult to see that the power consumption is one of the most important considerations in designs of such mobile devices.

Power consumption, as define as TDP or thermal design power, ranges from 0.65 watts for Z500 to 8w for 330 family, 4 watts in the 200 family and 2.4w or 2 w for the Z530, Z520 and Z510 processors in the Atom processor variants. Compare it with something like 35/40 w in the X86 processors in regular PC products. The processors themselves and the transistors used to implement the processors are of very small geometrical dimensions. Intel uses 45 nm lithography technology. That leads to a very small package size of 13 mmX14 mm in most cases. The processors that have a TDP of 2.5, 4 and 8 watts come in a package size 22mm X 22 mm.

While the extreme small size helps in controlling power dissipation Intel uses other techniques that help reduce power further. One is to use very low core voltage to operate the transistor on the chip. This is in the range of 0.7 to 1.1 volt in case of the processors that dissipates up to 2.4 watts. Processors that have TDP ratings of 2.5 watts to 8 watts use 0.8 to 1.625 v for the 2.5 watt unit; and 0.9 to 0.1625 v for the higher rated processors. 

To top it all, a very sophisticated power control is used to keep the power consumption at a minimum. These techniques include not only external voltage control, Intel has taken it to the extent that parts of the system goes to sleep when even one of the two threads the processors are capable of enters an inactive state. To retain efficiency though the processor is capable of coming out of a sleep state really quickly.

Please click here for Thermal design.