Emissions liquid fuels

The code provides for the testing of gas turbines supplied with gaseous or liquid fuels (or solid fuels converted to liquid or gas prior to entrance to the gas turbine). Test of gas turbines with water or steam injection for emission control and/or power augmentation are included. The tests can be applied to gas turbines in combined-cycle power plants or with other heat recovery systems. 

A current vehicle fuel system designed for evaporative emission control should address enhanced SHED, running loss, and ORVR emission level requirements (see Table 1). A typical vehicle fuel system is shown in Fig. 4. The primary functions of the system are to store the liquid and vapor phases of the fuel with acceptable loss levels, and to pump liquid fuel to the engine for vehicle operation. The operation of the various components in the fuel system, and how they work to minimize evaporative losses during both driving and refueling events, is described below. 

The liquid fuel handling components of the fuel system include the fuel filler pipe, fuel tank, fuel pirmp, and the fuel supply and return lines. The fuel tank is a low pressure, low hydrocarbon emission vessel designed to contain both the liquid and vapor phases of the fuel. An electric pump located inside the fuel tank is used to transfer liquid fuel from the tank to the engine. The fuel in the tank is suctioned from a small reservoir in the tank which minimizes liquid level transients caused by vehicle motion. 

In the United States, in particular, recent legislation has mandated sweeping improvements to urban air quality by limiting mobile source emissions and by promoting cleaner fuels. The new laws require commercial and government fleets to purchase a substantial number of vehicles powered by an alternative fuel, such as natural gas, propane, electricity, methanol or ethanol. However, natural gas is usually preferred because of its lower cost and lower emissions compared with the other available alternative gas or liquid fuels. Even when compared with electricity, it has been shown that the full fuel cycle emissions, including those from production, conversion, and transportation of the fuel, are lower for an NGV [2]. Natural gas vehicles offer other advantages as well. Where natural gas is abundantly available as a domestic resource, increased use... 

Solids emissions from solid and liquid fuel fired plant are covered in the HMSO publication Grit and dust-The measurement of emissions from boiler and furnace chimneys. This states levels of emissions which should be achieved in existing plant and specified for new plant. Suitable sampling connections should be incorporated into the flue ducting for the use of test equipment if permanent monitoring is not included. 

Lean burn/dry low-NOx combustors can generate NOx emissions levels as low as 9 ppm (at 15% 02), while those with liquid fuel combustors have NOx emissions limited to approximately 25 ppm (at 15% 02). There is no substantial difference in general performance with either fuel. However, the different heats of combustion result in slightly higher mass flows through the expansion turbine when liquid fuels are used, and thus a very small increase in power and efficiency performance is obtained. Also, the fuel pump work with liquid fuel is less than with the fuel gas booster compressor, thereby further increasing net performance with liquid fuels. 

Among liquid fuels (XTL), only biomass-derived hydrocarbons (BTL) are a relevant option from the perspective of lowering GHG emissions not so other fossil-based liquids (CTL, GTL). Even if CTL fuel supply paths were upgraded by carbon capture and storage, the resulting specific CCF-equivalent emissions would only be reduced to the level of conventional gasoline or diesel energy chains. 

The reduction in the lead content of gasoline and the introduction of reformulated gasoline have been very successful in reducing automobile emissions, due to changes in gasoline composition, with further improvements in fuel quality proposed for the early decades of this new millennium. These projections are accompanied by a noticeable and measurable decrease in crude oil quality, and the reformulated gasoline will help meet environmental regulations for emissions for liquid fuels but will be subject to continuous review because of the potential for environmental impact. 

Methanol s major advantages in vehicular use are that it is a convenient, familiar liquid fuel that can readily be produced using well-proven technology. It is a fuel for which vehicle manufacturers can, with relative ease, design a vehicle that will outperform an equivalent gasoline vehicle and obtain an advantage in some combination of emission reduction and efficiency improvement [1.7]. 

---