LPG

LPG Mix Standard in Nigeria – The abuse of Propane and Butane mix in Nigeria.

Butane Propane Mix

Dangers of abuse of Propane and butane mix to Gas penetration and safety in Nigeria.

 
Background:
 
Liquefied Petroleum Gas (LPG) is a portable, clean, and efficient energy source that is readily available to consumers around the world. Marketed as Propane and Butane, or a combination of the two, LPG is used worldwide in several different applications.
It is produced from Crude oil Refining and Natural gas processing. The constituents of LPG are gaseous at 20°C and 1-atmosphere pressure.
 
LPG – Liquefied Petroleum Gas which exists as propane or butane, are both flammable hydrocarbon gases used as fuel for Heating, Cooling, Cooking, and Vehicular fuel ( Autogas).
 
Origin of LPG
 
About 60% of the world’s LPG is obtained from Natural gas, and the remaining 40% is achieved from refining crude oil. When natural gas is pulled from the ground, the resulting hydrocarbon is a mix of several gases and liquids. About 90% of what is recovered is Methane, or Natural gas. The other 10% is made up of propane, butane ethane, condensates and others. In order to transport the produced Dry gas ( Pure Natural Gas), the LPG must be separated from the methane.
 
LPG is also created when crude oil is refined. One of the first products to be removed from crude oil before refining the hydrocarbon into jet fuel, diesel or gasoline; LPG constitutes about 3% of a barrel of crude oil
 
LPG Properties
 
1. BOILING POINT
Propane has a boiling temperature of -42°C, whilst butane has a higher boiling point at -2°C.This means that propane will continue to vaporize and turn to gas in colder climates up to -42°C, which is perfect for countries that have cold winters. However, in temperate regions like Africa, propane will vaporize quicker leading to extremely higher pressures when stored in tanks and can lead to rupture of tanks, pumps & piping. This makes butane much more suitable and safer for domestic use as cooking gas as it exhibits lower vapor pressures at higher temperatures.
 
2. ENERGY EFFICIENCY
For the same volume, Butane provides about 12% more energy than Propane when the same volumes are burned above freezing temperature. Hence, one liter of Butane gas will cook for a longer time than a similar amount of Propane gas.
 
3. COST
Most of the time, Butane is more affordable than Propane, as a bottle filled with Butane often contains a higher volume than a bottle of Propane. This is due to the extreme vapor pressure of Propane compared to Butane.
Also, tested, and certified Propane cylinders & canisters are relatively more expensive than their butane counterparts – this is due to the volatility of Propane which requires more safety measures in handling.
 
4. SAFETY
When handling both gases, safety is a major concern. However, in tropical regions, Propane handling requires additional safety measures such as thicker shelled storage tanks, piping with higher operating pressures, pressure regulating devices, etc. to avoid accidents. Hence, Butane finds more applications than propane in tropical regions with regards to handling, safety, and consumption.
 
LPG MIXTURE.
 
Liquefied petroleum gas mixture (LPG gas mixture) consists of flammable hydrocarbon gases that include propane, butane, isobutane and LPG gas mixtures of the three gases. The percentage of propane and butane in an LPG gas mixture ranges from 100% propane to 20% propane and 80% butane.
The table below shows the LPG gas mixture percentage of propane and butane in LPG for a few countries. Note that some countries use a more propane rich LPG gas mixture, in the wintertime, to assure proper vaporization.
COUNTRYPROPANE/BUTANE MIX
 UNITED KINGDOM 100:0 Note: Butane is available separately
 USA 100:0 LPG mixture
GERMANY 60:40 to 10:90 depending on season
FRANCE 100:0 to 30:70 LPG mixture
NIGERIA 100:0 to 20:80 LPG mixture or 7 bar Maximum according to NIS 555 2014 – SON standard
 
For Nigeria, the recognized standard for LPG mixture is a Vapour Pressure of 7 bar see chart below ( NIS 555 2014); which is equivalent to 40% Propane to 60% Butane at 37.8-degree centigrade according to the chart from engineeringtoolbox.com
 
Butane Propane Mix
Propane – Butane Mix pressure chart
At LPG in Nigeria, we think that the 7 bar level as the max for LPG mix is very high as equipment in use for cooking gas has a lower rating than 7 bar. The basis of our opinion is based on feedback from customers loading from the Gas plant who despite the sub-7 bar pressure witness significantly higher pressures with valves and equipment during LPG plant operations and from customers during cooking activities.
NIS 555 2014
LPG SPECIFICATION – NIS 555 -2014
 
Common practices in the Nigerian LPG Market.
Information reaching us suggests that due to the availability of propane from recent Natural gas production fields in the Niger Delta area, there has been the uncontrolled introduction of propane in the LPG market by gas plant owners & dealers. This illegal practice of mixing propane with butane in untested quantities by dealers is done in a bid to compete unfairly with legitimate plant owners on basis of cheaper prices. By mixing in small quantities of propane, the price is considerably reduced by over 30%, attracting customers who are oblivious to the dangers of handling such mixture.
 
The effects of these practices are felt in the LPG market in the instability of gas prices and consequently slow sales reported from gas plant owners in affected areas. Furthermore, as a result of the volatile properties of propane earlier stated, of which these dealers are ignorant of, handling propane with equipment designed for butane causes them to fail. These device failures unchecked could result in grave accidents that result in loss of equipment and sadly loss of lives.
 
It’s important to note that Nigeria’s LPG industry at 5kg per capita consumption is still in the infancy stage. The potential new users are huge, this group has little or no awareness about LPG and the handling and would need to be exposed to a less volatile LPG mix. We cannot afford to put profit ahead of Safety.
 
DPR has extensively closed down a number of illegal plants over the years, however, more work has to be done to track down mobile dealers especially around hotspots like Umutu & Umunede.
 
 
 
 

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4 Comments

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  • Aseleke ajayi , January 28, 2021 @ 10:01 am

    You are spot on with your report.
    Handling of propane is a major challenge in Nigeria.
    The issue starts from the un standardised fill quantities of gas cylinders. While most cylinders in use today are propane designed, Distributors will get to the plant hoping to buy 60kg into a 50Kg propane cylinder. Its obvious they are trying to reduce transportation cost but that is at the expense of safety.
    Again, I am not sure how DPR arrived at 7 bar pressure for LPG, but surely the average Nigerian gas user cannot handle this. Most of the gas burners around are designed around butane hence the discharge orifice before the burner head is larger than what is required for propane. This makes the flame velocity at the burner higher than normal hence the gas burns quicker with an LPG mix of a high propane ratio. Most end users are oblivious of this fact hence burner head regulation is not considered that much during cooking to account for a higher propane presence.
    The solution to these dangers are simple. The DPR need to either peg LPG pressure to a manageable 3.5 bars corresponding to around 6% of propane or mandate depots to sell the two major components of LPG separately as done in many countries. This will help reduce the dangers associated with handling throughout the supply chain.

    • lpginnigeria , January 28, 2021 @ 10:23 pm

      Thank you Aseleke, this is a very interesting perspective. We are happy to publish any piece you may have on the design of burners with respect to the LPG mix, and practical suggestions for regulators on the way forward.

  • Jude , January 28, 2021 @ 12:43 pm

    Very timely and insightful analysis

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