lắp đặt hệ thống gas

Khí dầu mỏ hóa lỏng hay Khí hóa lỏng (tiếng Anh: Liquefied Petroleum Gas; viết tắt: LPG) là chữ viết tắt của, hoặc LP Gas là "khí dầu mỏ hóa lỏng". Đây là cách diá»…n tả chung của propan có công thức hóa học là C₃H₈ và butan có công thức hóa học là C₄H₁₀, cả hai được tồn trữ riêng biệt hoặc chung vá»›i nhau nhÆ° má»™t há»—n hợp. LPG được gọi là khí dầu mỏ hóa lỏng vì các chất khí này có thể được hóa lỏng ở nhiệt Ä‘á»™ bình thường bằng cách gia tăng áp suất vừa phải, hoặc ở áp suất bình thường bằng cách sá»­ dụng kỹ thuật làm lạnh để làm giảm nhiệt Ä‘á»™. Trong thành phần của LPG, thông thường pha trá»™n Propan:Butan: 30:70, 40:60, 50:50

Nó ngày càng được sá»­ dụng nhÆ° má»™t thuốc phóng aerosol^[1] và má»™t chất làm lạnh,^[2] thay thế chlorofluorocarbon trong ná»— lá»±c giảm thiệt hại cho tầng ozone. Khi được sá»­ dụng cụ thể làm nhiên liệu cho xe, nó thường được gọi là khí tá»± Ä‘á»™ng.

Các loại LPG được mua và bán bao gồm các há»—n hợp chủ yếu là propane (C

3H

8), phần lá»›n là butane (C

4H

10), và, thông thường nhất, các há»—n hợp bao gồm cả propan và butane. Vào mùa đông ở bán cầu bắc, há»—n hợp chứa nhiều propan hÆ¡n, trong khi vào mùa hè, chúng chứa nhiều hÆ¡n butane.^[3][4] Tại Hoa Kỳ, chủ yếu hai loại LPG được bán: propan thÆ°Æ¡ng mại và HD-5. Các thông số kỹ thuật được công bố bởi Hiệp há»™i chế biến khí (GPA)^[5] và Hiệp há»™i Thá»­ nghiệm và Vật liệu Hoa Kỳ (ASTM).^[6] Há»—n hợp propane/butane cÅ©ng được liệt kê trong các thông số này.

Các propylen, butylen và các hydrocacbon khác nhau thường cÅ©ng có mặt ở nồng Ä‘á»™ nhỏ. HD-5 giá»›i hạn lượng propylene có thể được đặt trong LPG đến 5% và được sá»­ dụng nhÆ° má»™t thông số kỹ thuật tá»± Ä‘á»™ng. Má»™t chất tạo mùi mạnh mẽ, ethanethiol, được thêm vào để có thể dá»… dàng phát hiện rò rỉ. Tiêu chuẩn Châu Âu được quốc tế công nhận là EN 589. Tại Hoa Kỳ, tetrahydrothiophene (thiophane) hoặc amyl mercaptan cÅ©ng là chất tạo mùi được phê duyệt,^[7] mặc dù hiện tại không được sá»­ dụng.

LPG được Ä‘iều chế bởi tinh chế dầu mỏ hoặc khí tá»± nhiên "Æ°á»›t", và gần nhÆ° hoàn toàn có nguồn gốc từ các nguồn nhiên liệu hóa thạch, được sản xuất trong quá trình lọc dầu (dầu thô), hoặc được khai thác từ các dòng dầu khí hoặc khí tá»± nhiên khi chúng nổi lên từ mặt đất. Nó được sản xuất lần đầu tiên vào năm 1910 bởi Dr. Walter Snelling, và các sản phẩm thÆ°Æ¡ng mại đầu tiên xuất hiện vào năm 1912. Hiện tại nó cung cấp khoảng 3% tổng năng lượng tiêu thụ và đốt cháy tÆ°Æ¡ng đối sạch không có bồ hóng và rất ít khí thải lÆ°u huỳnh. Vì nó là má»™t loại khí, nó không gây nguy hiểm cho mặt đất hoặc Ã´ nhiá»…m nÆ°á»›c, nhÆ°ng nó có thể gây ra Ã´ nhiá»…m không khí. LPG có giá trị năng lượng cụ thể Ä‘iển hình là 46,1 & nbsp; MJ / kg so vá»›i 42,5 & nbsp; MJ / kg đối vá»›i dầu nhiên liệu và 43,5 & nbsp; MJ / kg đối vá»›i loại cao cấp xăng (xăng).^[8] Tuy nhiên, mật Ä‘á»™ năng lượng trên má»—i Ä‘Æ¡n vị thể tích 26 MJ/L thấp hÆ¡n so vá»›i xăng hoặc dầu nhiên liệu, vì mật Ä‘á»™ tÆ°Æ¡ng đối của nó thấp hÆ¡n (khoảng 0,5–0,58 kg/L, so vá»›i 0,71–0,77 kg/L cho gasoline).

Vì nhiệt Ä‘á»™ sôi của nó thấp hÆ¡n nhiệt Ä‘á»™ phòng, LPG sẽ bay hÆ¡i nhanh ở nhiệt Ä‘á»™ và Ã¡p suất và thường được cung cấp trong bình thép Ã¡p lá»±c. Chúng thường được lấp đầy tá»›i 80-85% công suất để cho phép giãn nở nhiệt của chất lỏng chứa. Tá»· lệ giữa thể tích của khí hóa hÆ¡i và khí hóa lỏng thay đổi tùy thuá»™c vào thành phần, áp suất và nhiệt Ä‘á»™, nhÆ°ng thường là khoảng 250: 1. Áp suất mà LPG trở thành chất lỏng, được gọi là Ã¡p suất hÆ¡i, tÆ°Æ¡ng tá»± thay đổi tùy thuá»™c vào thành phần và nhiệt Ä‘á»™; ví dụ: nó xấp xỉ 220 kilôpascal (32 psi) cho butane tinh khiết tại nhiệt Ä‘á»™ 20 °C (68 °F) và khoảng 2.200 kilôpascal (320 psi) cho propane tinh khiết tại 55 °C (131 °F). LPG nặng hÆ¡n không khí, không giống nhÆ° khí tá»± nhiên, và do đó sẽ tràn dọc theo các tầng và có xu hÆ°á»›ng lắng xuống ở những Ä‘iểm thấp, chẳng hạn nhÆ° các tầng hầm. Có hai mối nguy hiểm chính từ Ä‘iều này. Đầu tiên là khả năng nổ nếu há»—n hợp LPG và không khí nằm trong giá»›i hạn nổ và có nguồn đánh lá»­a. Thứ hai là nghẹt thở do không khí thay thế LPG, làm giảm nồng Ä‘á»™ oxy.

Một bình khí LPG "đầy đủ" chứa 85% chất lỏng, thể tích vỏ sẽ chứa hơi ở áp suất thay đổi theo nhiệt độ..^[9]

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^{lắp đặt hệ thống gas}

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^{lắp đặt lpg}

Liquefied petroleum gas or liquid petroleum gas (LPG or LP gas), is a flammable mixture of hydrocarbon gases used as fuel in heating appliances, cooking equipment, and vehicles.

It is increasingly used as an aerosol propellant^[1] and a refrigerant,^[2] replacing chlorofluorocarbons in an effort to reduce damage to the ozone layer. When specifically used as a vehicle fuel it is often referred to as autogas.

Varieties of LPG bought and sold include mixes that are mostly propane (C

3H

8), mostly butane (C

4H

10), and, most commonly, mixes including both propane and butane. In the northern hemisphere winter, the mixes contain more propane, while in summer, they contain more butane.^[3][4] In the United States, mainly two grades of LPG are sold: commercial propane and HD-5. These specifications are published by the Gas Processors Association (GPA)^[5] and the American Society of Testing and Materials (ASTM).^[6] Propane/butane blends are also listed in these specifications.

Propylene, butylenes and various other hydrocarbons are usually also present in small concentrations. HD-5 limits the amount of propylene that can be placed in LPG to 5%, and is utilized as an autogas specification. A powerful odorant, ethanethiol, is added so that leaks can be detected easily. The internationally recognized European Standard is EN 589. In the United States, tetrahydrothiophene (thiophane) or amyl mercaptan are also approved odorants,^[7] although neither is currently being utilized.

LPG is prepared by refining petroleum or "wet" natural gas, and is almost entirely derived from fossil fuel sources, being manufactured during the refining of petroleum (crude oil), or extracted from petroleum or natural gas streams as they emerge from the ground. It was first produced in 1910 by Dr. Walter Snelling, and the first commercial products appeared in 1912. It currently provides about 3% of all energy consumed, and burns relatively cleanly with no soot and very few sulfur emissions. As it is a gas, it does not pose ground or water pollution hazards, but it can cause air pollution. LPG has a typical specific calorific value of 46.1 MJ/kg compared with 42.5 MJ/kg for fuel oil and 43.5 MJ/kg for premium grade petrol (gasoline).^[8] However, its energy density per volume unit of 26 MJ/L is lower than either that of petrol or fuel oil, as its relative density is lower (about 0.5–0.58 kg/L, compared to 0.71–0.77 kg/L for gasoline).

As its boiling point is below room temperature, LPG will evaporate quickly at normal temperatures and pressures and is usually supplied in pressurised steel vessels. They are typically filled to 80–85% of their capacity to allow for thermal expansion of the contained liquid. The ratio between the volumes of the vaporized gas and the liquefied gas varies depending on composition, pressure, and temperature, but is typically around 250:1. The pressure at which LPG becomes liquid, called its vapour pressure, likewise varies depending on composition and temperature; for example, it is approximately 220 kilopascals (32 psi) for pure butane at 20 °C (68 °F), and approximately 2,200 kilopascals (320 psi) for pure propane at 55 °C (131 °F). LPG is heavier than air, unlike natural gas, and thus will flow along floors and tend to settle in low spots, such as basements. There are two main dangers from this. The first is a possible explosion if the mixture of LPG and air is within the explosive limits and there is an ignition source. The second is suffocation due to LPG displacing air, causing a decrease in oxygen concentration.

A full LPG cylinder contains 85% liquid; the ullage volume will contain vapour at a pressure that varies with temperature.^[9]

Uses[edit]

LPG has a very wide variety of uses, mainly used for cylinders across many different markets as an efficient fuel container in the agricultural, recreation, hospitality, industrial, construction, sailing and fishing sectors. It can serve as fuel for cooking, central heating and to water heating and is a particularly cost-effective and efficient way to heat off-grid homes.

Cooking[edit]

LPG is used for cooking in many countries for economic reasons, for convenience or because it is the preferred fuel source.

In India, nearly 8.9 million tons of LPG was consumed in the six months between April and September 2016 in the domestic sector, mainly for cooking. The number of domestic connections are 215 million (i.e., one connection for every six people) with a circulation of more than 350 million LPG cylinders.^[10] Most of the LPG requirement is imported. Piped city gas supply in India is not yet developed on major scale. LPG is subsidised by the Indian government for domestic users. Increase in LPG prices has been a politically sensitive matter in India as it potentially affects the middle class voting pattern.

LPG was once a standard cooking fuel in Hong Kong; however, the continued expansion of town gas to newer buildings has reduced LPG usage to less than 24% of residential units. However, other than electric, induction, or infrared stoves, LPG-fueled stoves are the only type available in most suburban villages and many public housing estates.

LPG is the most common cooking fuel in Brazilian urban areas, being used in virtually all households, with the exception of the cities of Rio de Janeiro and São Paulo, which have a natural gas pipeline infrastructure. Since 2001, poor families receive a government grant ("Vale Gás") used exclusively for the acquisition of LPG. Since 2003, this grant is part of the government main social welfare program ("Bolsa Família"). Also, since 2005 the national oil company Petrobras differentiates between LPG destined for cooking and LPG destined for other uses, practicing a lower price for the former. This is a result of a directive from Brazilian federal government, but its demise is currently being debated.^[11]

LPG is commonly used in North America for domestic cooking and outdoor grilling.

Rural heating[edit]

 

LPG Cylinders in India

Predominantly in Europe and rural parts of many countries, LPG can provide an alternative to electric heating, heating oil, or kerosene. LPG is most often used in areas that do not have direct access to piped natural gas.

LPG can be used as a power source for combined heat and power technologies (CHP). CHP is the process of generating both electrical power and useful heat from a single fuel source. This technology has allowed LPG to be used not just as fuel for heating and cooking, but also for decentralized generation of electricity.

LPG can be stored in a variety of manners. LPG, as with other fossil fuels, can be combined with renewable power sources to provide greater reliability while still achieving some reduction in CO₂ emissions. However, as opposed to wind and solar renewable energy sources, LPG can be used as a standalone energy source without the prohibitive expense of electrical energy storage. In many climates renewable sources such as solar and wind power would still require the construction, installation and maintenance of reliable baseload power sources such as LPG fueled generation to provide electrical power during the entire year. 100% wind/solar is possible, the caveat being that even in 2018 the expense of the additional generation capacity necessary to charge batteries, plus the cost of battery electrical storage, still makes this option economically feasible in only a minority of situations.

Motor fuel[edit]

 

LPG filling connector on a car

 

White bordered green diamond symbol used on LPG-powered vehicles in China

When LPG is used to fuel internal combustion engines, it is often referred to as autogas or auto propane. In some countries, it has been used since the 1940s as a petrol alternative for spark ignition engines. In some countries, there are additives in the liquid that extend engine life and the ratio of butane to propane is kept quite precise in fuel LPG. Two recent studies have examined LPG-fuel-oil fuel mixes and found that smoke emissions and fuel consumption are reduced but hydrocarbon emissions are increased.^[12][13] The studies were split on CO emissions, with one finding significant increases,^[12] and the other finding slight increases at low engine load but a considerable decrease at high engine load.^[13] Its advantage is that it is non-toxic, non-corrosive and free of tetraethyllead or any additives, and has a high octane rating (102–108 RON depending on local specifications). It burns more cleanly than petrol or fuel-oil and is especially free of the particulates present in the latter.

LPG has a lower energy density per liter than either petrol or fuel-oil, so the equivalent fuel consumption is higher. Many governments impose less tax on LPG than on petrol or fuel-oil, which helps offset the greater consumption of LPG than of petrol or fuel-oil. However, in many European countries, this tax break is often compensated by a much higher annual tax on cars using LPG than on cars using petrol or fuel-oil. Propane is the third most widely used motor fuel in the world. 2013 estimates are that over 24.9 million vehicles are fueled by propane gas worldwide. Over 25 million tonnes (over 9 billion US gallons) are used annually as a vehicle fuel.

Not all automobile engines are suitable for use with LPG as a fuel. LPG provides less upper cylinder lubrication than petrol or diesel, so LPG-fueled engines are more prone to valve wear if they are not suitably modified. Many modern common rail diesel engines respond well to LPG use as a supplementary fuel. This is where LPG is used as fuel as well as diesel. Systems are now available that integrate with OEM engine management systems.

Conversion kits can switch a vehicle dedicated to gasoline to using a dual system, in which both gasoline and LPG are used in the same vehicle.

Conversion to gasoline[edit]

LPG can be converted into alkylate which is a premium gasoline blending stock because it has exceptional anti-knock properties and gives clean burning.

Refrigeration[edit]

LPG is instrumental in providing off-the-grid refrigeration, usually by means of a gas absorption refrigerator.

Blended of pure, dry propane (refrigerant designator R-290) and isobutane (R-600a) the blend "R-290a" has negligible ozone depletion potential and very low global warming potential and can serve as a functional replacement for R-12, R-22, R-134a and other chlorofluorocarbon or hydrofluorocarbon refrigerants in conventional stationary refrigeration and air conditioning systems.^[14]

Such substitution is widely prohibited or discouraged in motor vehicle air conditioning systems, on the grounds that using flammable hydrocarbons in systems originally designed to carry non-flammable refrigerant presents a significant risk of fire or explosion.^[15][16]

Vendors and advocates of hydrocarbon refrigerants argue against such bans on the grounds that there have been very few such incidents relative to the number of vehicle air conditioning systems filled with hydrocarbons.^[17][18] One particular test, conducted by a professor at the University of New South Wales, unintentionally tested the worst-case scenario of a sudden and complete refrigerant expulsion into the passenger compartment followed by subsequent ignition. He and several others in the car sustained minor burns to their face, ears, and hands, and several observers received lacerations from the burst glass of the front passenger window. No one was seriously injured.^[19]

Global production[edit]

Global LPG production reached over 292 million metric tons/yr in 2015, while global LPG consumption to over 284 mn t/yr.^[20] 62% of LPG is extracted from natural gas while the rest is produced by petrochemical refineries from crude oil.^[21] 44% of global consumption is in the domestic sector. The USA is the leading producer and exporter of LPG.^[22]

Security of supply[edit]

Because of the natural gas and the oil-refining industry, Europe is almost self-sufficient in LPG. Europe's security of supply is further safeguarded by:

• a wide range of sources, both inside and outside Europe;


• a flexible supply chain via water, rail and road with numerous routes and entry points into Europe;

According to 2010–12 estimates, proven world reserves of natural gas, from which most LPG is derived, stand at 300 trillion cubic meters (10,600 trillion cubic feet). Added to the LPG derived from cracking crude oil, this amounts to a major energy source that is virtually untapped and has massive potential. Production continues to grow at an average annual rate of 2.2%, virtually assuring that there is no risk of demand outstripping supply in the foreseeable future.^{[ Report this page}