Offshore Rigs Diesel Engine NOX Emission

The diesel engine combustion process mainly produces NO (approximately 60–90%) and little NO2in the combustion chamber. They are considered a mixture called NOX but only NO2 is relevant for air hygiene as a pollutant input. Diesel engines systematically produce NO2 from NO in catalytic converters. deNOx systems use it to oxidize and efficiently reduce soot particulates.

In air, NO oxidizes to NO2, a gas that irritates mucous membranes and is caustic when combined with moisture (acid rain). It increases asthma sufferers’ physical stress, especially when they exert themselves physically. NO2 has a ‘‘fertilizing’’ effect on plants, i.e. it promotes growth.

According to authority, a limit concentration of NO2 of 40mg/m2 will be in force in the EU in 2010.

Achieving the aforementioned limits will necessitate considerable efforts in all sectors, i.e. not only in the transportation but also the major offshore industry and shipping businesses will be required to reduce NOX emission worldwide.

The IMO (International Maritime Organization) imposed limits on NOX emissions for marine diesel engines

with power outputs >130 kW as of January 1, 2000. It plans to later adapt the limits determined from the test cycles dependent on use (main propulsion or auxiliary engine) and the mode of operation (constant speed or propeller drive) specified.

In 1999, EPA adopted regulations requiring new marine diesel engines to comply with emission standards

beginning in 2004 (tier 1) and 2007 (tier 2). 

In May 2008, EPA published new rules aimed at dramatically reducing air pollution from marine diesel engines.

↓ particulate matter (PM) emissions by 90%

↓ nitrogen oxide (NOx) emissions by 80 %

 

Tier 1 and Tier 2 emission standards currently applicable to new marine diesel engines

Tier 1 limits NOx emissions only, and applies to model years 2004 and later

Tier 2 limits NOx, CO, and PM, and applies to model years 2007 and later

Tier 3 “near term” emission standards for “existing” engines for most towboats, Tier 3 standards become effective in 2016

Tier 4 “long term” emission standards for “newly-built” engines mandates high-catalytic after-treatment application of high efficiency after technology for most of our towboats, Tier 4 standards may become effective in 2016

Growing opportunities for dual-fuel and gas-diesel engines in land and marine power markets have stimulated designs from leading medium speed and low speed enginebuilders. Development is driven by the increasing availability of gaseous fuels, the much lower level of noxious exhaust emissions associated with such fuels, reduced maintenance and longer intervals between overhauls for power plant.

A healthy market is targeted from floating oil production vessels and storage units, rigs, shuttle tankers, offshore support vessels and LNG carriers.

Valuable breakthroughs in mainstream markets have been made since 2000 with the specification of LNG-burning engines for propelling a small Norwegian double-ended ferry (Mitsubishi high speed engines), offshore supply vessels and a 75 000 cu.m. LNG carrier (Wärtsilä medium speed engines).

Natural gas is well established as a major contributor to the world’s energy needs. It is derived from the raw gas from onshore and offshore fields as the dry, light fraction and mainly comprises methane and some ethane. It is available directly at the gas field itself, in pipeline systems, condensed into liquid as LNG or compressed as CNG. Operation on natural gas results in very low emissions thanks to the clean-burning properties of the fuel and its low content of pollutants. Methane, the main constituent, is the most efficient hydrocarbon fuel in terms of energy content per amount of carbon.  Wärtsilä’s dual-fuel (DF) four-stroke engines can be run in either gas mode or liquid-fuelled diesel mode. In gas mode the engines work according to the lean-burn Otto principle, with a lean premixed air-gas mixture in the combustion chamber. (Lean burn means the mixture of air and gas in the cylinder has more air than is needed for complete combustion, reducing peak temperatures). Less NOx is produced and efficiency increases during leaner combustion because of the higher compression ratio and optimized injection timing. A lean mixture is also necessary to avoid knocking (selfignition).

Marine engine designers in recent years have had to address the challenge of tightening controls on noxious exhaust gas emissions imposed by regional, national and international authorities responding to concern over atmospheric pollution.

Exhaust gas emissions from marine diesel engines largely comprise nitrogen, oxygen, carbon dioxide and water vapour, with smaller quantities of carbon monoxide, oxides of sulphur and nitrogen, partially reacted and non-combusted hydrocarbons and particulate material. Nitrogen oxides (NOx)—generated thermally from nitrogen and oxygen at high combustion temperatures in the cylinder—are of special concern since they are believed to be carcinogenic and contribute to photochemical smog formation over cities and acid rain (and hence excess acidification of the soil). Internal combustion engines primarily generate nitrogen oxide but less than 10 per cent of that oxidizes to nitrogen dioxide the moment it escapes as exhaust gas.

Sulphur oxides (SOx)—produced by oxidation of the sulphur in the fuel—have an unpleasant odour, irritate the mucus membrane and are a major source of acid rain (reacting with water to form sulphurous acid). Acid deposition is a trans-boundary pollution problem: once emitted, SOx can be carried over hundreds of miles in the atmosphere before being deposited in lakes and streams, reducing their alkalinity.

Sulphur deposition can also lead to increased sulphate levels in soils, fostering the formation of insoluble aluminium phosphates which can cause a phosphorous deficiency. Groundwater acidification has been observed in many areas of Europe; this can lead to corrosion of drinking water supply systems and health hazards due to dissolved metals in those systems. Forest soils can also become contaminated with higher than normal levels of toxic metals, and historic buildings and monuments damaged.

Particulate matter (PM) is a complex mixture of inorganic and organic compounds resulting from incomplete combustion, partly unburned lube oil, thermal splitting of HC from the fuel and lube oil, ash in the fuel and lube oil, sulphates and water. More than half of the total particulate mass is soot (inorganic carbonaceous particles), whose visible evidence is smoke. Soot particles (unburned elemental carbon) are not themselves toxic but they can cause the build-up of aqueous hydrocarbons, and some of them are believed to be carcinogens. Particulates constitute no more than around 0.003 per cent of the engine exhaust gases.

Noxious emissions amount to 0.25-0.4 per cent by volume of the exhaust gas, depending on the amount of sulphur in the fuel and its lower heat value, and the engine type, speed and efficiency.

De-NOx technology options are summarized as follows:

The primary NOx reduction measures can be categorised as follows:

-Water addition: either by direct injection into the cylinder or by emulsified fuel.

- Altered fuel injection: retarded injection; rate-modulated injection; and a NOx-optimized fuel spray pattern.

- Combustion air treatment: Miller supercharging; turbocooling; intake air humidification; exhaust gas recirculation; and selective non-catalytic reduction. (Miller supercharging and turbocooling are covered in the Pressure Charging chapter.)

- Change of engine process: compression ratio; and boost pressure.

The basic aim of most of these measures is to lower the maximum temperature in the cylinder since this result is inherently combined with a lower NOx emission.

MARPOLAnnex VI choong

Below courtesy of CATERPILLAR USA


Below courtesy of Watsila
Watsila IMO Tier III



Below courtesy of Watsila
Watsila Emission AAA

Cleaning up the GULF oil and legal mess ...

With the ill-fated Deepwater Horizon rig sunken in the Gulf, there are now two similar rigs, along with the Discoverer Enterprise, a drilling ship; the Viking Poseidon, which knows how to install things on the sea floor; four mother ships for remotely operated underwater vehicles; various barges and supply vessels; and the Q4000 ( built by our KeppelAMFELS yard in 2002, see below for more detail about this rig ), a rig that specialises in repairing and closing wells. If the well that the Deepwater Horizon was in the process of closing off four weeks ago continues to spray oil into the sea for months to come, it won’t be for a lack of expensive, sophisticated and improbable-looking hardware a mile up above it.

Deployment of vessel and WI rig to plug the leak -

Sketch of Well Intervention With Help of a Vessel and a Semi

It is that mile which is the problem. The oil industry has been fixing blowouts for more than a century. The challenge is doing it under 150 atmospheres of pressure ( i.e. 5000ft below sea level ) with the tools and lights of a robot mini-submarine that gets its power and instructions by way of a cable. Under such environmental conditions, even the well orchestrated planned can come hit a snag, as it did when icy methane hydrates that form when natural gas gets mixed up with cold water at high pressure foul the plan to funnel the leaking oil up to Discoverer Enterprise. The hydrates did not just clog the pipes, they also buoyed up the 125-tonne cofferdam that had been lowered over the leak, lifting it right off the sea bed. [ Well, this phenomenon was not even in the eyes or expectation of all the experts BP has supposedly mobilised to study the viability of the cofferdam method it seems ! ]

On May 16th, though, oil did start to be collected by applying a subtler intervention. Oil is currently escaping from two leaks, one at each end of the well’s riser. The riser connected Deepwater Horizon to its blowout preventer, a stack of valves on the sea floor which marked the top of the well proper. When the rig sank, the riser broke near the top while remaining attached to the blowout preventer at the bottom, bending itself like a pretzel in its subsequent collapse. Some oil is now flowing from where the riser and the blowout preventer meet; most is coming from the broken end of the riser, which has ended up about 300 metres away on the sea floor. It is from a tube slipped into that distal end that oil is now being pumped up to Discoverer Enterprise and its attendant barges.

The insertion device, about a fifth of the diameter of the riser itself, is not supposed to block the flow of oil completely. If it did, the pressure of the oil would blow it out of the riser like a cork in a hose. Instead it sucks at the oil flowing around it, but gauging how hard to suck is tricky. Without enough suction more oil than necessary would continue to leak out; too much and it will let in water which will make the formation of those pesky hydrates more likely. Other anti-hydrate measures include a small pipe feeding methanol, an antifreeze, into the maw of the riser, and hot water circulating through a sleeve to warm the pipe bringing the oil to the surface. According to Kent Wells, vice-president of BP, the oil company in overall charge of the project, the amount of oil coming up through the pipe had risen to 2,000 barrels a day by May 17th.

The next step is to try to staunch the flow proper with drilling mud, a mixture of water and clay minerals. The well is gushing because of the pressure the oil is under in its reservoir 4,300 metres below the sea bed. If drilling mud can be forced into the well under even greater pressure—a technique called “top kill”—it will eventually reach a depth where the weight of the column of drilling mud exerts enough pressure to stop any oil flowing upwards.  [ More about well kill when I start to upload from my archives ...]

To do this, BP has been replumbing and rewiring the blowout preventer, paying particular attention to its choke pipe and the kill pipe. These provide access to the central bore of the well underneath most of the heavy valves which should have closed off the flow of oil, but for some reason did not. The two pipes, which originally went up to the Deepwater Horizon, have been reconnected with heavyweight hoses to a metal framework called a manifold that has been installed nearby. Above it the Q4000 rig and three attendant vessels have 50,000 barrels of peculiarly heavy drilling mud and pumps capable of providing 30,000 horsepower ( ie. from the High pressure mud pumps ) with which to muscle that mud into the well.

Q4000 Well Intervention Rig

Q4000

The blowout preventer’s control pod, which was also originally connected to the lost rig, has been taken up to the Q4000, where it has been tested and attached to new cables. The pod should soon be on its way back down for reattachment to the preventer. The Q4000 will then have control over the valves that connect the choke and kill lines to the well proper. One reason why all this is taking time is that there are now up to 14 remotely operated underwater vehicles working around the well. A “simultaneous operations” unit is needed to choreograph the complex dance of vessels, submersibles and rigs.

Once the control pod has been reinstalled on the blowout preventer and the manifold is attached to the Q4000, the top kill could start. The control pod ( refer to my earlier blog article or do a quick search on this word ) will open the valves that allow the drilling mud to be forced into the well. At that point the fluid-dynamics equivalent of a titanic arm-wrestling match will get under way, with the surface vessels’ pumps trying to push the mud down the well while the rising oil tries to push it out.

If the oil wins, then the team will try a “junk shot”. The manifold has two containers full of various sorts of rubber and plastic that are particularly good at gumming things up. Open and close a few valves on the manifold and the drilling mud from the surface can squirt one of these junk shots down the pipes and into the blowout preventer. The oil pressure will force it up into the heart of the stack of valves. There, by making it harder for anything to get out of the top, the junk will give the drilling mud a better chance in a second bout of arm wrestling. The second container of junk provides another shot.

If both barrels fail there is the possibility of putting a new blowout preventer on top of the old one. That would mean cutting the existing riser, but now that the siphon inserted into it is bringing oil up to the barges it means risking a serious setback. So it may be wiser to wait for the relief wells that are being drilled to get down to the point, 4,000 metres below the sea bed, where they will intersect the existing well. At that depth stopping the flow with a deadweight of drilling fluid could create few problems, once the exceedingly difficult challenge of hitting the well is met. So far, the first relief well is only about 1,000 metres or so below the sea bed, and the second has only just been started.

Underwater spraying by ROV -

Not all the remotely operated vehicles at the site have been involved in replumbing kill lines, hooking up manifolds and supporting the relief wells. Some have been swanning around spraying chemical dispersants into the oily waters. If the top kills do not work this spraying may also help limit the damage done by the oil before the relief wells are finished.

The investigation team’s work thus far shows that this accident was brought about by the failure of a number of processes, systems and equipment. There were multiple control mechanisms— procedures and equipment—in place that should have prevented this accident or reduced the impact of the spill: the investigation is focused on the following seven mechanisms.


1. The cement that seals the reservoir from the well;
2. The casing system, which seals the well bore;
3. The pressure tests to confirm the well is sealed;
4. The execution of procedures to detect and control hydrocarbons in the well, including the use of the BOP;
5. The BOP Emergency Disconnect System, which can be activated by pushing a button at multiple locations on the rig;
6. The automatic closure of the BOP after its connection is lost with the rig; and
7. Features in the BOP to allow Remotely Operated Vehicles (ROV) to close the BOP and thereby seal the well at the seabed after a blow out

The procedure was intended to stem the flow of oil and gas and ultimately kill the well by injecting heavy drilling fluids through the blow-out preventer on the seabed, down into the well.
Despite successfully pumping a total of over 30,000 barrels of heavy mud, in three attempts at rates of up to 80 barrels a minute, and deploying a wide range of different bridging materials, the operation did not overcome the flow from the well.
The Government, together with BP, have therefore decided to move to the next step in the subsea operations, the deployment of the Lower Marine Riser Package (LMRP) Cap Containment System.

The operational plan first involves cutting and then removing the damaged riser from the top of the failed Blow-Out Preventer (BOP) to leave a cleanly-cut pipe at the top of the BOP’s LMRP. The cap is designed to be connected to a riser from the Discoverer Enterprise drillship and placed over the LMRP with the intention of capturing most of the oil and gas flowing from the well. The LMRP cap is already on site and it is currently anticipated that it will be connected in about four days.

The Lower Marine Riser Package (LMRP) Cap :

 •Installing a Lower Marine Riser Package (LMRP) Cap is a containment option for collecting the flow of oil from the MC252 well. The LMRP is the top half of the blow out preventer (BOP) stack.

•The installation procedure first involves removing the damaged riser from the top of the BOP.

•A remote operated hydraulic shear will be used to make two initial cuts and then that section will be removed by crane. A diamond wire saw will then be placed to cut the pipe close to the LMRP and the final damaged piece of riser will be removed.

•The LMRP Cap is designed to seal on top of the riser stub. The seal will decrease the potential of inflow of seawater as well as improve the efficiency of oil recovery. Lines carrying methanol also are connected to the device to help stop hydrate formation.

•The device will be connected to a riser extending from the Discoverer Enterprise drillship.

•The LMRP Cap is on site, and it is anticipated that this option would be available for deployment by the end of May.

Clearing the oil slick :
Dispersants consist of surfactants (which are like detergents) in a solvent. When applied to a slick of oil they are meant to break it up into tiny droplets which disperse widely and are broken down by bacteria. The use of dispersants reduces the chances of direct exposure to oil by birds, fish, sea animals and everything ashore, but it may increase the risks for things on the sea floor in some circumstances. This is why they cannot be used everywhere. They are also toxic, though a lot less so than oil itself.

Spraying dispersants in new ways, rather than using new formulations, may make more of a difference. BP thinks spraying dispersants into the oil plume where it leaves the riser may be 20 times more effective than waiting until it reaches the surface. If so, the 45,000 gallons so far sprayed at depth may have done more good than all the spraying at the surface. Three trials of this technique have been made by the EPA ( Environment Protection Agency ), the first two being inconclusive due to logistical difficulties.

There will be plenty of lessons to learn from the Deepwater Horizon disaster. Once the leaks have been stopped, the operation may try to get the failed blowout preventer to the surface so that it is at last possible to see what really went wrong. It is not just the engineering response to future oil spills that will be affected, but also working practices, safety systems and regulation. The future safety of offshore drilling for both the roughnecks and the environment will be shaped by what happens a mile below. 

[ And also the subsequent legal proceedings, if every of those involved wishes to wash their hands and pointing to the culprit of the cause....... ]

EVERY oil spill has a silver lining—if you are a lawyer, that is. More than 70 related lawsuits were filed in the two weeks after oil started leaking into the Gulf of Mexico on April 20th, most of them class actions that claim damages on behalf of many similar victims. Trial lawyers are dreaming of one of the biggest paydays since they feasted on tobacco litigation. Even more certain are the bumper fees for law firms defending BP, Halliburton and other firms involved. The most notable winner is Kirkland & Ellis, which will represent the British oil giant.

No one doubts that the BP lawsuits will dwarf those that followed the Exxon Valdez spill in Alaska in 1989.

However, actual damages could run into billions, even before fees. Less comforting is the $75m cap on liability for economic damages under the Oil Pollution Act (OPA) of 1990. Regardless of what happens to efforts in Congress to raise this cap to $10 billion, this legislation may not constrain tort lawsuits under state or common law. The point of the OPA was not to limit tort law but to supplement it. Legal damages could thus be in addition to other compensation that is paid voluntarily to victims by BP and others, an amount that has been estimated at anything from $3 billion to $8 billion.

A crucial contest is looming between BP and the trial lawyers over the extent to which various lawsuits will be consolidated, and where the trial will happen. The trial lawyers fancy Louisiana, with its long history of generosity to class-action litigants; BP would prefer oil-friendly Texas.

Litigation over the oil spill is helping to reverse a downward trend in class-action suits against business. The BP case may be just the sort of disaster that tort law exists to address. But the justification is less clear for some other high-profile litigation.

Cleaning the oil spill and impact to the Gulf environment and wildlife :
030610 Oil Spill Impact

Copenhagen Summit 2009 outcome

Seems there was no agreement to reduce emissions, but just "meet and talk". Developed countries proposed targets that could limit climate change to an average of two degrees Celsius. Some developed countries made this commitment conditional on major developing countries, notably China, India and Brazil, agreeing to accept binding targets. This wasn’t forthcoming, though China did, for the first time, suggest it would be prepared to accept binding intensity targets.


The dialogue between the developed and developing countries was further complicated by the developing countries most vulnerable to climate change pushing to limit temperature rise to 1.5 degrees. This standoff ended with the developed countries, including the United States, agreeing to submit their firm emissions targets no later than the end of January. The two-degree limit would call for reductions of 25% to 40% relative to 1990 by 2020, a level deeper than any proposed at Copenhagen; the estimate of current non-binding pledges yields about a three-degree increase, so there’s a large gap to be closed. What is going to happen to the major industries reaction to this ? Improve technology to reduce emission is going to cost them in production and manufacturing and will directly pass on to the consumers. Their concerns were mitigated somewhat when the developed countries, again including the United States, agreed to fund as much as $100 billion for technology transfer to accelerate the development of low-carbon economies and adaptation measures in the developing world. The action has to be taken very carefully by these major producers. China and the United States agreed to internally measure and report on the results of their mitigation actions. While agreeing to the overall conference summary, the smaller developing countries remained skeptical that there would be sufficient commitment to even the two-degree target, which they already deemed too high for comfort. Brazil and Norway proposed an international fund to support deforestation reductions in developing countries.

The EU already is committed to 20% below 1990 levels, but has agreed to 30% if other major emitters, notably China, the United States, India and Brazil, make meaningful commitments. This higher level will mean some radical rethinking of everything from building codes to energy supply. However, while challenging domestically, the EU's overall climate policy is acting as a catalyst for some world-class businesses.

Following Copenhagen, China was criticized by many as being a major barrier to a deal. Specifically, it wasn’t ready to commit to intensity reductions or outside verification. In the same month, China established some of the most ambitious renewable energy standards anywhere in the world, backed by strong domestic policy and guidelines. This follows its recent implementation of tough vehicle efficiency standards, systematic development of high-speed rail and radical upgrading of building codes. The need to grow with far less pollution is becoming clearer to the Chinese, and they aren’t overlooking the potential world market for energy-efficient solutions and climate-friendly products.

The next conference will be in Mexico in November this year.  One way or another, U.S. need to be comfortable with monitoring and managing greenhouse gas emissions as a part of their normal job responsibility, just as their bankers now have greater moral responsibility to work harder and pay back their dues, if at all, by way of reduced bonuses, where in the past they have been generously and overly remunerated.

Copenhagen Summit 2009 achieved what ??

Maybe a plenty. By getting  over 190 nations and 130 leaders together for the United Nations climate change summit is already no mean feat. Raising global awareness of climate change to an unprecedented level getting world leaders to confront the issue further.

Outcome of the talks did not satisfy everyone, given the differences in priorities between developed and developing nations. For the latter, bread and butter issues come first. But countries facing immediate danger from the effects of climate change, such as small islands and those with low-lying areas near the coast, would of course make demands quite different from those of nations not at similar risk.

The Copenhagen Accord recognises the need to limit the rise in global temperatures to no more than 2 deg C above pre- industrial levels. Though not a binding target, the accord gave official recognition to the widely held scientific view that the rise in global temperatures should be kept to this level. With this agreement on temperature, it is expected that countries will devise measures to cut carbon emissions accordingly.

In addition, under the accord, countries are asked to review their pledges for curbing carbon emissions by 2020. Although no country would be penalised for failing to keep to its pledge, the accord would encourage government policies to tackle carbon emissions. This would remove the business-as-usual attitude and the world may witness the beginning of a new social norm. If the countries that have made pledges remain committed to them, other countries would come under peer pressure to follow suit.

Another breakthrough was the pledge by rich nations to jointly mobilise US$30 billion (S$42.2 billion) over the next three years, and US$100 billion a year by 2020, to help poor nations adapt to and mitigate the impact of climate change. Good news for developing nations as they have long asked rich nations for such funding.

While how the funds will be disbursed remains a big question mark, another issue is how rich countries will raise the funds with present economic crisis looming and starting to see some slow recovery. Will the funds come from other adjustments by balancing the budget and through means of increased taxes or from cutting foreign aid for education and infrastructure development? Higher domestic taxes will for sure create discord, and dampen the political will of rich countries to contribute funds. But reducing support for foreign aid will not help poor countries either.

Ideally, the Copenhagen Accord should have included a provision that the rich countries pledge not to cut other areas of foreign aid while creating a global fund for climate change.