Methane leaks

Another type of leak Methane release could It happens in depleted oil and gas Characterisation... 

Landfill G as Recovery. This process has emerged from the need to better manage landfill operations. Landfill gas is produced naturally anaerobic bacteria convert the disposed organic matter into methane, carbon monoxide, and other gases. The quantity of methane gas is substantial and could be utilized as fuel, but generally is not. Most of the methane simply leaks into the surrounding atmosphere. 

Other energy sector concerns are methane emissions from unburned fuel, and from natural gas leaks at various stages of natural gas production, transmission and distribution. The curtailment of venting and flaring stranded gas (remotely located natural gas sources that are not economical to produce liquefied natural gas or methanol), and more efficient use of natural gas have significantly reduced atmospheric release. But growth in natural gas production and consumption may reverse this trend. Methane has... 

At present there is still excess electrical capacity in the U.S.. In addition, the low price of gas permits the economic construction of new gas turbine electrical plants. But new gas plants, and methane leaking from underground gas production facilities and... 

Size of molecules. Since the hydrogen molecule is smallest of all it will leak through permeable materials where methane and gasoline will not. 

A natural gas wellhead is located 400 m from an instrument control room. The control room is a potential ignition hazard in the event of a leak of natural gas (essentially pure methane). Studies have shown that a suitable safety margin is imposed if the downwind gas concentration is determined using one-half the LFL. For methane this represents a concentration of 2.5 vol. %. 

A methane leak fills a 200 m3 room until the methane concentration is 30 % by volume. Calculate how much nitrogen must be added to the room before air can be allowed in the space. 

Solution Assume the process takes place at constant temperature and pressure and Figure 4.16 applies. The constant pressure assumption requires that as the methane leaks into the room, the pressure is not increased, as would occur in a constant volume process,... 

It is interesting to realize that as the N2 or air is being added, CH4 is always part of the gas mixture leaking from the room. This exhausted methane can have a flammable concentration as it now mixes with the external air. The flammable states for the exhaust stream in exterior air can be described by a succession of lines from the B-C locus to A. 

A methane leak in a closed room is assumed to mix uniformly with air in the room. The room is (4 x 4 x 2.5)m high. Take the air density as 1.1 kg/m3 with an average molecular weight of 29 g/g mole. How many grams of methane must be added to make the room gases flammable The lower and upper flammability limits of methane are 5 and 15 % by volume respectively. 

Methane leaks from a tank in a 50 m3 sealed room. Its concentration is found to be 30 % by volume, as recorded by a combustible gas detector. The watchman runs to open the door of the room. The lighter mixture of the room gases flows out to the door at a steady rate of 50 g/s. The flammable limits are 5 and 15 % by volume for the methane in air. Assume a constant temperature at 25 °C and well-mixed conditions in the room. The mixture of the room gases can be approximated at a constant molecular weight and density of 25 g/mol and 1.05 kg/m3 respectively. After the door is opened, when will the mixture in the room become flammable ... 

The oxygen consumption in the partial combustion process is a function of the preheat temperatures of the gas and oxygen, the heat leak from the combustion zone, and the efficiency of the burner which is measured by the terminal temperature required for a given conversion of methane. Pressure and space velocity are also important variables but their effect can easily be obscured by small changes in burner performance or terminal temperature. 

---