Natural air pressure situation?

Question

a list would be great. person with most things will get the best answer. thx

Answer 1

If the underground pressure in the oil reservoir is sufficient, then this pressure will force the oil to the surface. Gaseous fuels, natural gas or water are usually present, which also supply needed underground pressure. In this situation, it is sufficient to place a complex arrangement of valves (the Christmas tree) on the well head to connect the well to a pipeline network for storage and processing.

Usually, about 20% of the oil in a reservoir can be extracted using primary recovery methods.

[edit] Secondary recovery

Over the lifetime of the well the pressure will fall, and at some point there will be insufficient underground pressure to force the oil to the surface. If economical, as often is, the remaining oil in the well is extracted using secondary oil recovery methods (see: energy balance and net energy gain).

Secondary oil recovery uses various techniques to aid in recovering oil from depleted or low-pressure reservoirs. Sometimes pumps, such as beam pumps and electrical submersible pumps (ESPs), are used to bring the oil to the surface. Other secondary recovery techniques increase the reservoir's pressure by water injection, natural gas reinjection and gas lift, which injects air, carbon dioxide or some other gas into the reservoir.

Together, primary and secondary recovery generally allow 25% to 35% of the reservoir's oil to be recovered.

[edit] Tertiary recovery

Tertiary oil recovery reduces the oil's viscosity to increase oil production. Thermally enhanced oil recovery methods (TEOR) are tertiary recovery techniques that heat the oil and make it easier to extract. Steam injection is the most common form of TEOR, and is often done with a cogeneration plant. In this type of cogeneration plant, a gas turbine is used to generate electricity and the waste heat is used to produce steam, which is then injected into the reservoir. This form of recovery is used extensively to increase oil production in the San Joaquin Valley, which has very heavy oil, yet accounts for 10% of the United States' oil production.[citation needed] In-situ burning is another form of TEOR, but instead of steam, some of the oil is burned to heat the surrounding oil. Occasionally, detergents are also used to decrease oil viscosity as a tertiary oil recovery method.

Tertiary recovery allows another 5% to 15% of the reservoir's oil to be recovered.

Tertiary recovery begins when secondary oil recovery techniques are no longer enough to sustain production, but only when the oil can still be extracted profitably. This depends on the cost of the extraction method and the current price of crude oil. When prices are high, previously unprofitable wells are brought back into production and when they are low, production is curtailed.

Yes! Natural-air corn drying has been used successfully for many years by researchers at a number of agricultural experiment stations and by thousands of corn producers. The process works best under cool (40 to 60 degrees F), dry (55 to 75% relative humidity) conditions. Since average fall temperature and humidity are in these ranges in the Upper Midwest, natural-air drying usually works quite well.

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Natural-air drying, also called ambient-air drying, near-ambient drying, unheated-air drying, or just air drying, is an in-storage drying method that uses unheated, outdoor air to dry corn to a safe storage moisture (13 to 15%). Instead of using heat energy from fossil fuels to remove moisture, natural-air drying uses electricity to operate fans, with energy for removing moisture coming primarily from the drying potential of outdoor air. Natural-air drying of shelled corn is similar in principle to the drying that takes place in cribs of ear corn, except that, because the airflow resistance for shelled corn is greater than for ear corn, fans rather than wind pressure move air through the bin.

Natural-air drying is basically a race between drying progress and growth of the fungi (commonly called molds) that cause grain spoilage. The bin is usually filled in a few days and the fan is started as soon as bin filling begins. Drying takes place in a one- to two-foot thick drying zone (also called a drying front) that moves slowly up through the bin (Figure 1) . Grain below the zone is generally dry enough to be safe from spoilage, while grain above the zone remains at its initial moisture until the zone passes. (Note that positive pressure, or upward airflow, is recommended for natural-air drying so that wet grain is at the top of the bin. There it is easier to watch for signs of mold and to move moldy corn out of the bin if necessary.)

Combustion Gas Spillage can occur when a residential fuel burning appliance, such as a water heater, furnace, or fireplace, is improperly ventilated. Each of these appliances has a chimney or vent to exhaust its combustion by-products, which may range from water and carbon dioxide to nitrogen dioxide and carbon monoxide. When these by-products are exhausted properly, they escape outdoors and cause no in-home problems. However, if a negative pressure situation occurs, the gases may be drawn into the home, where they can cause numerous indoor air quality and health concerns.  

  

  

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  Common Causes

An influx of combustion gases occurs whenever the exhaust system comes under a negative pressure, and thus negative pressure situations are the cause of combustion gas spillage. Negative pressure occurs when indoor air pressure is less than that of outdoor air pressure, drawing outside air into the home. Two different types of forces work on a home and affect air pressure: external forces and internal forces.

External Forces: those that occur naturally and usually are determined by weather conditions. The two major external forces at work on a home are:

[1] Wind, which can cause a positive pressure on the windward side of a house and negative pressure on the leeward side and sides parallel to the flow, affecting a home's pressure balance.

[2] Temperature, which changes pressure because of its effect on air density. If temperatures vary greatly between indoor and outdoor, this can create what is known as the "stack effect" in which cold air enters easily through lower level openings and, once heated, rises and exits through openings in the upper levels of the home. This creates a negative pressure at the lower levels and a positive pressure in the upper ones.

Internal Forces: those which occur within the home to create pressure differences. Any device which has an air exhaust can cause depressurization of a home, including bathroom fans, downdraft cooktop fans, clothes dryers, fireplaces and woodstoves, and fuel fired furnaces or water heaters.

Other than negative pressure, another problems which may arise are "backdrafting" and "spillage."  Fuel fired appliances rely on the natural tendency of their exhaust gases to be warmer than surrounding air, thereby creating a natural updraft in the chimney for the gases to escape. Whenever house depressurization occurs, the chimney must work against the suction created by other exhaust devices. If this suction is great enough, the flow of combustion gases may be reversed, which causes combustion gas spillage (aka backdrafting).

Usually the chimney will warm up after a short time, creating a stronger updraft to pull the gases out, but if the negative pressure inside the home is strong enough it will continue to spill into the home for as long as the appliance remains running. However, not all combustion appliances are susceptible to this combustion gas spillage. Those which are vulnerable to spillage problems include: naturally aspirated fuel-fired appliances, induced draft combustion appliances, and all fireplaces or wood burning stoves, even those classified as ‘airtight.’ Those not susceptible are: direct vent combustion appliances, sealed combustion appliances, and non fuel-fired appliances





Two front fired power boilers, a 250 MW CE boiler with sixteen burners and a 75 MW Foster Wheeler boiler with six burners were retrofitted with new COEN burners developed for utility applications. The burners were engineered to meet low air pressure drop, low excess air and low NOx requirements. At the design stage a computational fluid dynamic models representing a portion of ductwork, the wind boxes and burners were set up to in order to evaluate the uniformity of air distribution between the burners. When firing natural gas the flame in both boilers was quite different compared with the original burners. Low flame emissivity - high transparency caused initial difficulties with high temperature in the super heater. In the 250 MW boiler with the burners arranged in a four by four array the problem was overcome with fuel biasing between the levels. At the same time low excess air operation, down to 0.3% O2 in the flue gas, with practically no carbon monoxide emissions and NOx emissions of 330 ppm, corr. to 3% O2 dry, at high fire