In an idealised engine with perfect combustion all fuel would burn completely. The exhaust gas would then be composed of carbon dioxide (CO2) and water (H2O) only. The nitrogen in the air would pass through the engine unchanged. In practice, however, when the flame front reaches the relatively cool cylinder walls, or for other reasons, the flame is prematurely quenched, incomplete combustion results. The exhaust gas now contains the additional pollutants of unburnt or partly burnt hydrocarbons (HC) and carbon monoxide (CO). These levels, together with carbon dioxide and excess oxygen, are measured as part of the M.O.T. test. It is for the purpose of understanding the causes of unnecessarily high carbon monoxide (CO) and unburnt hydrocarbons (HC) that this brief note has been produced.
The fundamental differences between causes of high CO and High HC are as follows:- CARBON MONOXIDE : Carbon monoxide (CO) is a result of incomplete combustion. That is, the gas must be subject to combustion in order to form Co. If the mixture is too rich, there is insufficient oxygen (O2). Result instead of the optimum condition of CO2 formation. There will always be at least a small amount of CO in the exhaust because perfect combustion is not to be expected. Abnormally high CO can only be due to an excessively rich air/fuel mixture. CO is very poisonous. Measured as a percentage of the exhaust gas, it is formed when there is not enough oxygen present during combustion. CO combines with a chemical substance, haemoglobin, in the human blood system, which acts as an oxygen transporter. This substance preferentially absorbs CO instead of oxygen in the lungs. If it combines with CO instead of oxygen, respiratory processes are impaired with potentially fatal results. Carbon Monoxide (CO) is bad news.
In the U.K. traffic is said to be responsible for producing 90% of all the carbon monoxide in the atmosphere and 85% of that is from petrol engines.
HYDROCARBON (HC) (Petrol is essentially 100% hydrocarbon) A modest amount of HC will always be present in the exhaust gas. This is the result of both incomplete combustion and fuel at the flame boundaries that have not been fully subjected to combustion.
When CO is normal, and very high HC is present, an abnormal amount of raw fuel is escaping from the combustion chamber without being subjected to the combustion process. This is generally due to ignition misfire or leaking valves. A moderate rise in HC can result from early ignition timing, pre-ignition. HC represents wasted energy.
The third main product of combustion in the engine exhaust has is carbon dioxide (CO2). Carbon dioxide (together with water) is the end product of the complete combustion of a carbon hydrogen based fuel (a hydrocarbon)
One molecule of carbon dioxide contains one atom of carbon and two of oxygen. It is chemically very stable, and does not easily react with other substances. It is not a poisonous gas.
All three of the main constituents of vehicle exhaust emissions, which we have briefly discussed, are regarded as pollutants. Of the three, carbon monoxide (CO)is regarded as the most dangerous. Therefore, the major effort in controlling vehicle pollution is directed towards reducing the carbon monoxide content of exhaust emissions, hence, the pursuit of the lean burn engine design. In some quarters the lean burn engine is considered a more effective solution to the problem that the catalytic converter.
THE ROLE OF FCC
FCC is a green mobile fragrant liquid, which is added to all carbon hydrogen fuels at the very economical ration of 4000:1
FCC is pH neutral and contains no hydrocarbons, sulphur, phosphorus, nitrogen, or metallic ingredients, and is therefore non-polluting. It burns to give only water and carbon dioxide.
It will not attack the platinum or other metal alloy components of catalytic converters. FCC is composed of biodegradable, non –ionic surfactants, dispersants and water miscible solubilises.
FCC is hygroscopic, absorbing the water present, to a greater or lesser degree, in most fuel systems. Since it is absorbed into the fuel, it is burnt off cleanly in the normal combustion process. Water in fuel systems is the underlying cause of many problems. It combines with sulphur in the fuel and forms highly corrosive sulphuric acid, which can find its way into the lubricating oil causing premature bearing surface wear.
Water in diesel fuel also acts as the host to an infamous fungus, or bug, Hormoconis resinae. FCC by absorbing the moisture from the fuel, deprives the fungi of a place to live. Any fungus that is present will be dissolved, pass through the filters, and be burnt off.
Additionally, FCC will dissolve waxes, gums, and varnishes. It also helps to remove carbon deposits. All of these properties will keep the engine system operating in its most efficient mode, within the limits of engine condition and design.
FCC contains no hydrocarbons. This means that it is completely neutral in the combustion sense. It does not alter the burning characteristics of the fuel, and does not boost, or alter in any way, Cetane or Octane. This point is significant because many hydrocarbon-based additives have this effect, which can change the timing of the engine and, over time, cause damage. With FCC, improvements in fuel efficiency and savings in maintenance costs are achieved through cleanliness, and a better burn, as opposed to tampering with the combustion characteristics of the fuel.
The introduction of exhaust emission measurements as part of the M.O.T. test, and the necessary provision of gas analysers to all testing stations provided the first generally available opportunity to identify and quantify the effect of FCC fuel additive lowers emissions and exhaust emission levels. This facility was especially welcome because so many of the previous FCC trial results were, unavoidably, partly subjective. It was very largely the reports from FCC users in the U.K. and abroad of lower emission levels recorded during testing, without any other adjustments that prompted us to arrange our own trails. There are many variables, such as individual engine condition, mixture settings, level of fuel contamination, etc but the results were quite consistent, graphically illustrating the benefits of improved combustion afforded using FCC. FCC fuel additive lowers emissions, reducing money-wasting pollution.
In both concept and formulation FCC is very different from any fuel additive or treatment that you may previously have experienced. It cannot, of course, compensate for a major fault condition, but when mixture and possibly timing adjustments do not bring emissions within acceptable prescribed limits, FCC will usually make the difference.
The reduction in unburnt HC providing a measure of the money-saving prize being gained. However, it should be remembered that up to 40% of particulates emitted from a diesel engine originate from lube oil. The diesel engines critical deposits can form in two basic areas. A build-up of gum or resinous degradation products can occur in the fuel injection system. In severe cases this can result in the sticking of pump plungers and injector pintles or needles. Potential problems typically occur on isolated cylinders, with the resultant misfire causing loss of power and increased exhaust smoke. Carbon deposits build up on the parts exposed to hot combustion gases that can affect both fuel flow and the atomisation characteristics of the injectors. Again, loss of power, increased exhaust smoke and poor starting are the
noticeable engine performance problems. FCC attacks these problems in three major ways.
1. Surface action, due to the polar group promoting the formation of a barrier film on critical surfaces.
2. Dispersant action due to the polymeric ingredients preventing build-up of particulate matter and keeping it dispersed.
3. Solvent action, with FCC ingredients dissolving performed deposits.
Surface action and dispersant action are mainly of importance to the preventative of keep-clean function of FCC. Solvent action is of much more importance in the removal of existing deposits.
FCC conditions fuel by dissolving waxes, gums and carbon deposits that build up in all fuel systems over time.
The solvent action of FCC will dissolve all contaminants that have emanated from the fuel in the first instance.
Fungal contamination is also overcome by the use of FCC.
Ninety percent of the fuel system problems experienced by road transport operators involve filter blockages. There are four main causes of blocked filters. Three of these will be eliminated by the use of FCC, and it will assist in control of the fourth.
1. Water rust and dirt accumulate in the bottom of storage tanks. With FCC present, water and sediment build up will not occur.
2. FCC retards the fuel oxidation process; with the result that the formation of gums and sediments associated with oxidation do not become a problem.
3. Fuel in storage tanks can sometimes develop a dirty slime at the fuel/water interface. This is microbiological contamination. If left untreated it can spoil the fuel, contribute to tank corrosion, as well as blocking tank strainers and vehicle fuel filters.
The key to fungal control is removal of water. The low points of tanks and pipe work must be drained regularly. If all water is removed one of the essential conditions for fungal growth is removed and fungi cannot grow. FCC will remove the remaining water resulting in a better burn, FCC is a fuel additive that lowers emissions.
FCC assists in retarding the crystallizing of wax in fuel, FCC lowers emissions
FCC eliminates contaminants that cause engines to function below manufacturer’s specifications. As a result, a fuel saving of approximately four percent may be expected. Where engines have been neglected or subjected to especially hard usage, savings considerably in excess of that level can be experienced.
A great deal more information on engine condition is contained in the exhaust emission results (CO & HC levels) than is generally made use of, High CO or HC may exist in any mode of engine operation.
Where there are combinations of both excessively high HC and CO measurements They should be considered as separate and unrelated malfunctions. FCC has an important part to play, by improving efficiency and reducing pollution. Polluting less goes hand in hand with saving money!! These benefits, eliminated water, a cleaner fuel system, better burn and less expelled harmful gasses are all benefits of using FCC fuel additive.