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1. What is LPG? – Basic knowledge
LPG (Propane) is widely recognized as Environmentally friendly / Eco-friendly fuel
because it emits less carbon dioxide, which causes global warming, compared to other
fossil fuels. Needless to compare with others such as firewood and coal. Also, since it
contains no nitrogen and almost no sulfur, it is effective energy as a measure against
SOx (sulfur oxides) and NOx (nitrogen oxides). Similar profile is seen with city gas
(natural gas). And thus these 2, LPG (Liquified Petroleum Gas) and NG (Natural
Gas), can be considered among the best human friendly fuel of the day. In many
countries, people use natural gas (or piped gas) as fuel for cooking and heating. And in
some areas, LPG (Propane) plays that role.
At standard pressure and temperature, propane exists as a gaseous fuel. But it liquefies
at minus 42°C, and its volume in liquid state is 250 times reduced from its natural
state. Natural gas liquefies at much lower temperature and thus Propane is easier to
liquefy for transport in cylinders and stored in storage tanks. This nature of
propane makes this fuel reachable to the people who don’t have access to the pipeline
network.
Propane is valued in some cases such as natural disaster for its flexibility. For instance,
in case heavy earthquake may destroy public infrastructure. As Natural gas is supplied
to the users by gas piping network, if the piping may get serious damage, it will require
much time to recover the gas supply. While on the other hand, Propane is supplied
individually by cylinders and storage tank. Recovery is much easier because you can do
at individual level. This was seen in Japan at big earthquake time in year 2011. History
talks! The same applies in the cases of NG supply problems. And thus propane is often
stored as back-up energy even at natural gas supply area.
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2. Natural Vaporization
Propane exists as a gaseous fuel at standard pressure and temperature as explained
earlier. By pressuring the gas and lowering the temperature, it is transformed into liquid
state, Liquefied Petroleum Gas (LPG). However, your equipment burns vapor, not the
liquid of course. And thus the propane as fuel must reach your consuming equipment in
gaseous state. At the standard atmospheric pressure, with a boiling point of −42 °C
(−44 °F), propane is naturally vaporized by its own while exchanging heat. This PhaseChange from liquid to vapor is called Natural Vaporization. This is the essential
process when you consume propane with your equipment. When something is
transformed, it requires energy. In the case of propane vaporization, it requires heat.
Thus Vaporization takes place by Heat-Exchange. 2 factors effects rate of natural
vaporization in your tank. Those are ambient temperature and size of the tank (surface
exposed to the ambient heat). And therefore, maximum volume of natural
vaporization has its limits upon these factors.
4. 3. Propane Tank Freezed? VAPORIZER is a
solution
While the natural vaporization rate has its limits, if you continue consuming gas beyond
vaporization capacity, your equipment may be shut down. And thus it interrupts
continuous and steady operation to run your equipment. Take a look at your storage
tank. If you see frost at the bottom of the tank, it is telling you that the consumption is
beyond natural vaporization capacity. There are following 2 solutions to increase natural
vaporization rate.
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a. Increase the tank size or add more tanks.
b. Keep the tank filled all the time to increase the surface of heat exchange.
But unfortunately, these are not always good solutions. If the situation (codes, laws,
space, etc…) doesn’t allow you to add more tanks, tank replacement cannot be your
option. And even if it is possible, that will cost a lot. Frequent refills will also make
operation costly.
In such cases, installation of VAPORIZER would be fundamental solution.
VAPORIZER is a kind of boiler to increase the heat exchange and assist LPG
vaporization. LPG enters the vaporizer as a liquid and exits as a gas, just like we see
with natural vaporization. The big difference is that vaporizers has function to add
artificial heat to realize more stable and larger vaporization capacity. As it is
creating artificial heat by its own, it demonstrate stable vaporization performance
regardless of outside temperature. And as the vaporizer itself is the heat exchanger,
size and numbers of tanks is not a factor to control vaporization rate. Therefore, you
don’t need to replace to bigger tank or add more tanks. As you can increase the gas
supply volume with existing tanks, you can save space for construction.
And there’s one more issue to be considered – LPG composition. LPG is a mixed gas
and its main components are Propane and Butane. Depending on the area and usage,
Propane-Butane composition differs. For instance, LPG in Japan is 100% Propane. But
in other countries, often Propane rate is 60-70%. Butane is richer than Propane in its
calorific value. But its boiling point is −5 °C, which is much higher than Propane. And
therefore, Butane mixed LPG requires higher temperature for vaporization. When in
natural vaporization from tank, as you consume vapor LPG, Butane is likely to remain
more in tank and thus the gas composition may be changed. This nature also changes
natural vaporization rate. But in the case of using vaporizer, as it takes liquid LPG
directly and vaporize it by force with higher heat exchange, it vaporize both Propane
and Butane evenly. And thus the Gas composition remains the same.
Gas
Propane
Butane
Formula
C3H8
C4H10
Boiling point
-42℃
-0.5℃
Finally, vaporizer contribute to minimize the drainage (heavy-ends). In natural
vaporization, the vapor goes upward and liquid remain bottom of the tank. And
therefore, drainage is likely to accumulate at the bottom of the tank. You need to take
measure to remove this sometimes. But if you use vaporizer, this will be lesser because
the vaporizer takes the liquid directly from downward.
< Summary : Advantages of using vaporizers… >
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It can cover a large amount of gas consumption without adding storage
tanks.
As no additional tanks are required, you can save space and cost.
It realizes stable supply regardless of outside temperature and tank size.
LPG composition would not change as it directly vaporize LPG liquid.
Drainage (heavy-ends) does not easily accumulate at the bottom of the tank
as it directly vaporize LPG liquid.
You can select the best vaporization capacity model to much your
consumption volume from various choices.
4. Type of vaporizers
There are several types of vaporizers with different heat source that you can select. In
Japan, where the land is small and the residential and industrial/commercial areas tend
to be adjacent to each other, very strict rules are set regarding gas usage, and safety is
considered to be the most important issue in operation. Due to safety rules, direct-fire
vaporizers that use fire are rarely used in Japan. Instead, electric vaporizers that can
ensure better safety are the mainstream. KAGLA mainly manufactures electric, steam,
and hot water circulation vaporizers that demonstrate safe and reliable operation. Of
course, all products are Explosion-proof structure. Since they can be installed closer
to the tank than Direct Fire, they also contributes to space saving construction.
①Electric Water Bath vaporizer
Electric heater warms the water in the bath. And this hot water indirectly heats the liquid
LPG running through the heat exchanger. As the heat source is hot water with a gradual
temperature change, the vaporization ability is stable and controllable. And even if there
is a problem with the heat source, the vaporization ability can be exerted while the water
is warm.
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Electric Water Bath Vaporizer : AX5 series
Electric Water Bath Vaporizer : CX series
②Dry Electric Type vaporizer
Dry electric type is adopted for the compact vaporizers for space saving. Electric heater
warms the liquid LPG in the heat exchanger. Since it is a single-phase power supply
specification, construction of a three-phase power supply facility is not required and thus
installation is easy. Simple and maintenance easy structure.
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Dry Electric Vaporizer : DX series
Dry Electric Vaporizer : ADX series
③Steam Heating Water Bath Type vaporizer
The steam heater is equipped instead of the electric heater. The existing boiler can be
used to run the vaporizer. The basic structure including the safety mechanism is the
same as the electric water bath type. As the heat source is hot water with a gradual
temperature change, the vaporization ability is stable and controllable. And even if there
is a problem with the heat source, the vaporization ability can be exerted while the water
is warm. No power supply is required as the hot water temperature is controlled by
steam.
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Steam Heating Water Bath Vaporizer : SV-AX5 series
④Hot Water Circulation Type vaporizer
It is a vaporizer with a simple structure that circulates hot water from a water boiler as a
heat source. You can make use of the existing hot water boiler. The basic structure
including the safety mechanism is the same as the electric water bath type. As the heat
source is hot water with a gradual temperature change, the vaporization ability is stable
and controllable. And even if there is a problem with the heat source, the vaporization
ability can be exerted while the water is warm. No power supply is required as the hot
water temperature is controlled by water boiler.
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Hot Water Circuration Type Vaporizer : WV-AX5 series
⑤SNG vaporizer (Natural Gas Back Up Mixer)
Since the calorific value of natural gas is much lower than that of LPG, ordinary
combustion equipment for natural gas cannot be operated with LPG. The SNG
vaporizer solves this problem and makes it possible to operate natural gas equipment
using LPG as an alternative fuel. SNG (Synthetic Natural Gas) substitutes natural gas
in case of supply problem. This product is compactly packaged on a skid that combines
an LPG vaporizer with an air mixing device. By diluting LPG, a mixed gas (SNG) close
to the calorific value of natural gas is generated and used as an alternative fuel for
natural gas equipment. KAGLA’s SNG vaporizer uses a Venturi type structure that takes
in air only when LPG vapor is injected. As this mechanism does not generate mixed gas
in the explosion range, it is excellent in safety. It is often used as a backup facility in
areas where the natural gas supply is unstable. Even if a problem occurs in the supply
of natural gas, the operation is automatically switched to SNG vaporizer by sensing the
pressure drop. And thus you can continue operation without stopping the equipment by
consuming SNG.
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SNG Vaporizer : EVM-AX5 series
⑥NH3 (Ammonia) vaporizer
Ammonia is a compound of Nitrogen and Hydrogen with the formula NH3. NH3 boils
at −33.34 °C (−28.012 °F) at a pressure of one atmosphere. It is normally stored in
cylinder or tank in liquid state and vaporized to gaseous state when in use. Natural
vaporization is generally used, but for some specific usage, ammonia vaporizer
installation is highly recommended. Metal Nitriding (heat treatment) is among such
usage. Nitriding is a heat treating process that diffuses nitrogen into the surface of a
metal to create a case-hardened surface. This is treated against many of mechanical
parts (cars and other machines) such as gears, crankshafts, camshafts, cam followers,
valve parts, extruder screws, die-casting tools, forging dies, extrusion dies, firearm
components, injectors, plastic-mold tools and etc. The purpose of nitriding is to increase
the surface hardness of the steel and improve its wearing properties. And this is one of
the important processing operation for these types of metal parts. For nitriding, unlike
LPG, NH3 (ammonia) gas is not burnt. It is used in gaseous state as nitrogen rich gas,
to prevent oxidation while in heat treatment. When ammonia comes into contact with the
heated work piece it dissociates into nitrogen and hydrogen. The nitrogen then diffuses
onto the surface of the material creating a nitride layer. This is a kind of sensitive work
and thus the ammonia gas should be under good control. Therefore, we recommend
installation of Vaporizer for safe and stable supply of ammonia vapor. Ammonia is a
corrosive gas, and thus corrosion-resistant materials are required to be equipped in
important parts of vaporizers and connected devices. For this reason, KAGLA has a
series of equipment such as valves, regulators, and liquid changeover devices, with a
vaporizer at the top, designed to be used exclusively for Ammonia.
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NH3 (Ammonia) Vaporizer : EVA-AX5 series
KAGLA’s Japan domestic products
Introducing some of Japan domestic products of KAGLA. We also have varieties of
unique products other than LPG vaporizers.
BAiO : LPG storage tank with built-in vaporizer