Hazards And Control Measures Of Oil Evaporation Loss

For example, the explosion limit of gasoline is 1.0%~6.0% (volume fraction), the density of gasoline vapor is about 3.0~3.1kg·m-3 (STP), and the density of air is 1.1kg·m-3 (STP). Therefore, during the storage, delivery, and sales of oil products, a large amount of high-concentration oil and gas with a density greater than air that seriously exceeds the fire explosion limit evaporates and is discharged and diffuses, and mainly floats and accumulates in the ground space, which brings many serious hazards to enterprises and society.

1. Endangering the safety of various links in oil storage and transportation

Since most light oil products are volatile, flammable and explosive substances, they are easy to accumulate. After forming an explosive mixture with air, they are deposited and accumulated in depressions or trenches. When they encounter fire, they are very likely to explode or fire accidents, causing significant losses of life and property. If the hydrocarbon concentration is between 1% and 7%, it is in the explosion range. For this kind of hazard, people are currently more likely to prevent accidents by strengthening management and increasing investment in safety facilities. Nevertheless, due to the wide range of oil and gas explosion limits, the wide range of oil and gas diffusion, and the many factors affecting production safety, fire and explosion accidents caused by them occur from time to time. Statistical results show that among the 222 fire and explosion accidents, 101 were caused by oil and gas, accounting for 45.5%. The statistical results of the fire incidence rate in each area of ​​the finished oil depot are: tank area: 6.94%, loading and unloading area: 27.78%, oil delivery area: 36.11%, and these three areas account for 71%.

2. Pollute the environment and cause different degrees of damage

Oil and gas are gaseous hydrocarbon toxic substances, with a density greater than air and floating on the ground, which aggravates the impact on people and the surrounding environment. Generally, cracked gasoline is more toxic than straight-run gasoline. If gasoline contains unsaturated hydrocarbons and aromatic hydrocarbons, the pollution to the atmosphere will be more serious. When people inhale oil and gas of different concentrations, they will cause chronic (mild) poisoning or acute (severe) poisoning, and their respiratory system and central nervous system will be severely damaged. The high content of aromatic hydrocarbons will also affect the hematopoietic system. When oil and gas directly enter the respiratory tract, it will cause severe respiratory irritation symptoms. Severe patients may experience dyspnea, chills and fever, bronchitis, pneumonia, and even edema, accompanied by exudative pleurisy, etc. Oil and gas damage the central nervous system. Mild poisoning symptoms include dizziness, fatigue, nausea, vomiting, and mild anesthesia symptoms such as drunkenness, and mucosal irritation symptoms such as tearing, coughing, and conjunctival congestion. Its chronic poisoning effects are mainly manifested as neurasthenia syndrome and multiple peripheral neuritis. Some patients have "gasoline addiction" and toxic encephalopathy (similar to schizophrenia). Severe (acute) poisoning may cause amnesia, coma, limb rigidity, and paroxysmal spasms. A small number of patients develop cerebral edema, mental symptoms or central high fever, and may also be accompanied by multiple peripheral neuropathy, and severe cases may even die. Gasoline also has a degreasing effect, which causes lipid balance in cells such as skin to be disturbed, resulting in dryness, cracking, keratinization, and acute dermatitis in some cases. Animal test results show that propane, butane and isobutane have an inhibitory effect on heart function. According to the survey, environmental pollution from petrochemical enterprises has already affected the health of children around them, such as the non-specific immune function showing a downward trend.

Oil and gas will also have a corrosive effect on organic chemical materials such as coatings, thereby accelerating the corrosion rate of equipment. Oil and gas not only directly harm the environment as a primary pollutant, but are also the main reactant for producing photochemical smog. Photochemical smog is one of the main pollutants in modern industrialized society. For example, Los Angeles and Tokyo have experienced famous serious photochemical smog incidents, so it has long been taken seriously by many countries. In the 1970s, my country also observed and measured the photochemical smog formed by hydrocarbons such as oil and gas and the varying degrees of harm caused in Xigu District, Lanzhou.

3. Waste of energy, causing serious economic losses

Before the 1970s, my country basically did not take any control measures on oil and gas losses. The proportion of oil and gas losses to crude oil volume was as high as about 0.6%. With the continuous advancement of technology, especially the promotion and application of floating roof tanks, oil and gas losses have been greatly reduced. Data shows that gasoline generally has to go through four loading and unloading operations from the refinery to the end user. Each loading and unloading operation has a 1.8% volatilization loss, and the loss rate for four loading and unloading operations is 7.2%. Taking Beijing as an example, the annual gasoline consumption has reached 200x104t. It is estimated that the gasoline content above Beijing will increase by more than 1.4x104t every year, which is a very serious problem. Table 1.2 gives the estimated situation of domestic oil and gas evaporation loss in 2000. It can be seen from Table 1.2 that oil and gas loss accounts for 0.19% of crude oil, with a total amount of up to 400,000 tons; if the gasoline ex-factory price is 3,000 yuan/ton, the annual loss is 1.2 billion yuan:

4. Reduce the quality of oil products and affect the normal use of oil products

Since the loss of substances is mainly the lighter components in the oil products, the evaporation loss of oil products will not only cause a loss in quantity, but also a decrease in quality. For example, as the light fraction evaporates and loses gasoline, the initial distillation point and 10% point of gasoline increase, and the vaporization performance deteriorates, that is, the starting performance of gasoline deteriorates. In addition, evaporation loss will also accelerate gasoline oxidation, increase colloid, and reduce octane number.

Petrochemical sales companies have serious oil evaporation losses in different links. This loss has attracted great attention from relevant departments and will further promote the research and development of relevant governance technical measures. At present, from the perspective of administrative law enforcement management departments (such as environmental protection departments), various strict control methods have been adopted at home and abroad to control oil vapor emissions, such as laws and regulations, management regulations, environmental quality standards (indicators), and emission control decrees (indicators), generally including indicators such as maximum allowable emission concentration and maximum allowable emission. There are both qualitative and quantitative controls; there are both standards formulated based on local and national technical levels, and standards formulated from a health perspective.

The United States controls oil and gas volatile pollution in stages, stipulating that emissions in densely populated urban areas are <10mg/L, that is, the total hydrocarbon leakage allowed for each 1 gasoline is no more than 10mg; for other general areas, emissions are required to be <35mg/1. European II Standard 94/63/EC stipulates that the hydrocarbon concentration in industrial waste gas should not exceed 35g/m'; German TI air quality standard stipulates that the hydrocarbon concentration in industrial waste gas should not exceed 150mg/m. Oil refineries and oil depots in the European Community countries generally adopt oil and gas recovery measures, and oil and gas recovery at gas stations has also begun to be implemented. It was fully completed before 2005. The oil and gas generated from the entire process of oil production to consumption have been recovered, and all oil and gas have been discharged after meeting the standards. The United States, which leads in this field, has basically formed a complete oil and gas recovery system that connects the entire process of storage, loading and unloading, transportation, and refueling.