Water or other impurities present in the natural gas can increase the risk of damage to the pipeline as the result of corrosion or hydrate formation. Mol sieve dehydration is a process where water vapors are removed from the gas streams using the highly effective desiccant material known as molecular sieves. Different types of molecular sieves are used in industrial natural gas dehydration. This drying process using 3A, 4A and 5A solid desiccant materials are performed depending on the molecules size, pore size, and polarity of the gas stream. They have a slight difference in gas flow rate and water vapor concentration as per their respective pore size.
3A, 4A, and 5A can be used in beads and pellets form as the active adsorbents for the natural gas to very low dew points of up to -100Â°C. They are suitable for natural gas dehydration that contains aromatic compounds too such as methane, ethane, propane, etc. In most of the cases, PTSA (Pressure and Temperature Swing Adsorption) technology is used based on the molecular sieve type. It helps in gaining maximum efficiency. The larger pore size means higher adsorption capacity. In this situation, 5A molecules have maximum adsorption or dehydration capacity as compared to 4A and 3A. Similarly, 3A molecules have maximum water adsorption and minimum adsorption of other compounds present in the natural gas.
The natural gas containing water vapors and contaminants are effectively passed through the molecular sieve columns. With the help of high adsorption ability, the water gets removed from the gas stream to the low concentrations. Such adsorbents can be efficiently regenerated at specific temperatures based on the adsorbent type used for the natural gas drying/dehydration process. The molecular sieves are considered as the most effective desiccant and adsorbent for drying the natural gas with the suitable molecules of critical pore diameters.
In order to have an idea about the gas dehydration process and, we ought to have a better understanding of the component that is being dehydrated. Despite being a very popular source of fuel, not most industries are familiar with the true face of natural gas. So, what exactly is Natural gas?
To give you the exact definition of Natural gas, it is basically a hydrocarbon gas that mainly consists of Methane or CH4 along with some other hydrocarbons in lesser quantities. Formed more than a million years back, this natural gas is the product of the sea and ocean organisms that sunk right into the ocean bottom and were stored beneath structures of sedimentary rocks. After getting subjected to some intense episodes of pressure and heat, the organisms went through a transformation phase and gave is the natural gas which is one of the most popular sorts of fuel for energy that we use.
Nowadays we get natural gas right under the rocks that are underground and are called reservoirs. There are tiny spaces present in between these rocks, these tiny spaces or pores are the places where natural gas gets normally stored along with water, oil and other components.
One of the most common ways of extracting natural gas is through the process of drilling the wells. With pieces of equipment that can penetrate the impermeable rocks, the natural gas is extracted using these artificial methods. When it comes to the different variations of the Natural gas such as the shale gas, sour gas, tight gas, methane hydrates, and coal beds, each of them has got their own standard process of extraction. Most people also find the natural gas trapped in the reservoirs along with oil and other components.
Moving on to the details, we have 2 different types of natural gas. These types are defined and differentiated on the basis of the methane content that they have. It is readily reflected in the formation processes that they both have.
The biogenic gas or more commonly known as the Dry gas has got more or less than 95% of methane in it. The formation of the dry gas is through the decaying process of bacteria in the shallow depths.
The other type of gas that we have is the Thermogenic one which consists of more than 95% of the methane. This type is popularly known as the Wet Gas. A low-quality version of the natural gas, it is generally formed in the places with high temperature. There are some other compounds such as Butane and Ethane in the Wet natural gas apart from the methane content.
These variations of natural gas are extracted and then used for different purposes. To understand how the entire Natural gas sweetening process design and simulation work, we need to have an idea about the uses of Natural gas first.
There are many different sectors that can benefit from the use of natural gas. The Northern Hemisphere is the region that uses natural gas the most. Europe and North America are some major consumers of natural gas.
Natural gas is a very common fuel used for the generation of energy. Particularly in the USA, this source of energy is often used for the generation of electricity. But there are some other sectors that can benefit from natural gas as well.
Natural gas is used in the industrial sector as the process of heating fuel. Most of the combined power and heating systems in America are using it nowadays. Also, it is used as a certain raw material that can be further used in order to create the fertilizers, chemicals, hydrogen and much more. In the year 2017, about 35% of the natural gas in the US was consumed by the industrial sector.
Natural gas is a very useful component that can be used for the generation of electricity. It was in the year 2017 where the power sector consumed about 34% of the natural gas for the generation of electricity. Also, natural gas was found to be the main source for about 26% of the entire power sector in the US. The USA consuming sectors are the major ones that consume power and electricity generated by natural gas.
Natural gas is also a very important factor of use for the domestic sector in Europe and America. Natural gas can be used in order to heat water, for cooking purposes and also for the drying of the clothes. Most homes, almost half of them, in the USA are currently using natural gas as a power source for doing exactly that. The residential sector accounted for about 16% of the total consumption of natural gas in the year 2017.
One of the main uses and applications of natural gas is actually in the commercial sector. The commercial section uses natural gas in order to power the heating systems that heat water and buildings. Also, it can be used for drying clothes, cooking. Natural gas is also a major power source for outdoor lighting in such commercial sectors. Most of the consumers that are in this sector use this component in order to power up their heating and cooling systems as well. About 12% of the entire natural gas consumption happened in the USA in the year 2017.
One of the most common uses of natural gas is as a particular fuel that can be very useful for people in transportation businesses. The compressors provided for moving the natural gas are used on the vehicles to fill it with the natural gas which is more popularly known as the CNG. Transportation takes about 3% of the total consumption of natural gas in the US.
The entire concept of processing the natural gas revolves around cleaning the impurities and unnecessary components that are present in the natural gas. The processing of natural gas is done in order to produce what we know as the pipeline quality in natural gas. The processing plant for natural gas a very elaborate process of working and that is what we are going to be discussing right now.
With the help of the pipelines, the natural gas is transferred directly into the processing plants. The plant is actually a system that consists of pipes that are interconnected with each other and also to the different wells in the area.
Some of the most common products that come out from the processing of the natural plants are known as the NGLs or the Natural Gas Liquids. Such by-products include butane, propane, ethane, natural gasoline, and isobutene. These natural gas liquids are then sold separately to the different industries and can be used for certain purposes such as the recovery of oil from the well, providing the raw materials for the petrochemical plants and oil refineries. Some of them are also used as different energy sources as well.
The actual procedure of the natural gas processing to make it pipeline quality is actually a very complicated one. However, to simplify it, the process involves the removal of these impurities that are mentioned below.
Apart from these complex procedures, there are scrubbers and heaters installed in the wellhead in order to remove other impurities such as sand particles and dirt. This is mainly the function of the scrubber. The heaters on the other hand help in maintaining the temperature of the processing plant, ensuring that it doesn’t drop while the processing is going on.
As mentioned in the points below, one of the most common processes in the processing plant is the removal of water from natural gas. It is also known as sweetening or dehydration of natural gas. Here we will be discussing the Natural gas sweetening process design and simulation with the help of molecular sieves. We all know that there is water present in the natural gas when it is extracted with the help of drilling. There are some other impurities as well that need to be removed. These impurities and water that are present in the natural gas can cause damage to the quality of the natural gas. Hydrate formation and corrosion are some of the most common problems.
For that reason, the natural gas dehydration process is essential where the water particle and vapors are removed from the natural gas with the help of a proper molecular sieve dehydration unit. Molecular sieves are desiccant materials that are used for the gas dehydration process.
There are many different types of molecular sieves that are used in order to make sure that the entire dehydration process goes on smoothly. 3A, 4A, 5A molecular sieves are some of the most common types that are used. These sieves are differentiated on the basis of the pore size, molecule size, and the gas stream polarity present in these variations. The molecular sieve manufacturer who is responsible for the creation of these sieves will be the one that will differentiate between the sieves.
The 3A, 4A, and 5A molecular sieves are used in the pellets and the beads form for the molecular sieve dehydration because the active adsorption for the entire process of drying is very low when it comes to the natural gas.
The natural gas that consists of additional components such as ethane, butane, propane, etc. can be readily dehydrated with the help of these molecular sieves. There are many cases where the use of the PTSA or the Pressure and Temperature Swing Adsorption technology is decided on the basis of these sieves. This will help in achieving maximum levels of efficiency for the users.
The Molecular sieve 5A has got maximum adsorption for the dehydration process of natural gas which is higher than the 4A and the 3A molecular sieve. However, the molecular sieve 3A is also used largely because it has a maximum capacity of adsorption of water along with the minimum capacity of adsorption of the other molecules.
The entire sweetening process of natural gas consists of different complex procedures. However, the main gist of the matter is that that natural gas that contains water particles is passed through the columns of the molecular sieves to make sure that the water is successfully removed from the gas.
The Molecular sieve dehydration natural gas technique is considered to be one of the most important ones for the sweetening process of natural gas because these molecular sieves are desiccant and also have adsorption levels which can be used for drying the natural gas in a very efficient manner.