Lean and Rich

Lean and rich are commonly jargons used in oil and gas industry which describing most of the oil, gas, and petrochemical processes. If it is looked from normal language, lean means very few and rich means enriched with something. However, in real world of oil, gas, and petrochemical industry those jargons meant vice versa.
There are bunch of processes that always say about these two lean and rich; gas processing, gas dehydration, gas treating, etc. This mainly shows that the products or the agents are almost pure or otherwise.
In gas processing, almost everywhere these terms always being used when describing the processes or the stream. As a nature of gas processing, the ultimate product are natural gas, ethane, and liquefied petroleum gas, (LPG). So, these products are basically having their specifications and require the processing which enhance the specification before it is sold off to customer. Those unprocessed gaseous are named as rich gas because containing all the irrelevant impurities such hydrogen sulfide, (H2S), and mercury, (Hg) for example. The processed gaseous are called lean gas. Same principal even goes to the agent that being used to treat the gaseous, where unused is called lean and used is called rich.
Recently in the last article, there was about gas dehydration which is crucial before exporting it as dry gas. In this article the concern is not on the gas dehydration but more on the tri-ethylene glycol (TEG) that is used for dehydration process. The TEG is being used are fresh and will be regenerated once it is in the loop. Most of the time this TEG is called lean TEG since having very high purity compared to the one in the middle of the process. TEG with a solution of water is called as rich TEG.So, whoever dealing with any designing FEED, detailed, or operation support with any processes and talks about these two jargons, bear in mind that the meaning is actually vice versa of original language.

What is RON?

The moment any of us heard the name of “RON” sounds like somebody’s name, Ron or any Hollywood hero’s name. It’s normal for anyone to classify it as anything since most of the time most of the people not aware of the jargon in this flattened world. In this article, RON is a jargon in oil and gas industry generally and in refinery industry specifically. However, no one has to quit from reading this article as though of that it is not relevant since they are not in oil and gas industry. This article gives some knowledge on the application of RON in petrol station as highlighted recently regard to fuel price. As a non oil and gas personnel, you will have better understanding to choose fuel among RON 92, RON 95, or RON 97.

“RON” itself is defined as Research Octane Number which is done in laboratory for specification of the fuel for motorcar. The RON affects the performance of any car through the combustion which is called ignition knocking, higher the RON lower the ignition knocking. Usually all the cars manufactured so far will collaborate with oil company when designing the engine so that it is compatible with the fuel that being supplied in that nation. So, most of the car has the compatibility or it’s designed it for RON 95. It tells that only fuel that can be used is that RON 95 and above. Sometime, in some countries, there is no fuel with RON 95, only RON 92 and RON 97. So, the only choice that we have is to pump in fuel with RON 97 which is slightly costly but would impact for frequent users. So, for those really aware on this issue and willing to blend it on his/her own will buy 50% of RON 92 and 50% of RON 97 to make it RON 95. However, it can be a mess for those really needs to fast to lift and put the nozzle the nozzle. So, as there will be introduction of fuel with RON 95 and it will be beneficiary for us. However, the compatibility of the engine on the RON can be seen at the cover of the tank for most of the cars. If you couldn’t find it, it must be written in the manual. So, it is not necessary to still pump in with RON 97 if your car is compatible with RON 95. There will be better if your car is designed with RON 92, and then go for it. Always bear in mind that the most expensive is not necessarily the best product but the most compatible will be the best product to be chosen. CHOOSE WISELY AND SAVE YOUR MONEY!

So, what you are waiting for, you not necessarily to wait until implementation of RON 95 in petrol station in your area but you could do it on your own since it is being practiced by most of the frequent drivers. This is because the saving can be up to 20%. People might ask also why is that fuel with higher RON is more expensive than the lesser. There are reasons behind all these since it requires more chemical processes than usual refining of crude oil or condensate. This is very costly because of the catalysts involve are really expensive and require regeneration or change to new after certain life cycle

Oil characterisation

Process simulation is very crucial when designing any equipment in oil facilities or refineries since the physical properties of oils will dictate the size of equipment. Therefore, process simulation software is used when conducting conceptual study of any new field or refinery even for FEED.

In order to characterize the crude from different wells, lab analysis needs to be done by petroleum engineers and/or geologist. The analysis to be done should align with requirement of process engineer when characterizing the crude simulation software. Since physical properties calculated from simulation software and the stream of the oil is defined through lab analysis keyed in manually from data collected by petroleum engineers. So, data must be representative of the oil field to be developed. Those lab analysis really needed for process simulation must be consists of density, viscosity (two different temperatures), and true boiling points (TBP). These data can be used for both oil facility and refinery.

However, some petroleum engineers would do chromatograph method when analyzing newly found oil from fields. There are some circumstances to be considered when choosing one of the methods.

There are two approaches that can be considered when analyzing newly found oil which are boiling points and chromatograph method:-

Boiling points:-
This is boiling point method can used to characterize the crude for both oil facility and refinery. This is because can give various level of gas and oil since the oil is being categorized by different cut-point which refer to the boiling points. Hence, refineries need this test’s result when modeling simulation model for refineries. This is because refinery itself will separate the crude or condensate into different categories of gas and oil such as natural gas, liquefied petroleum gas, naphta, kerosene, diesel, etc and it really needs different cut points to separate it. This only can be done through characterization of crude by boiling points. However, this method more expensive to test in lab compared to chromatograph and this makes newly found oils are being tested by chromatograph method when characterizing crude to design oil facility (onshore or offshore). This is because the main function of oil facility is to separate among oil, gas, and water, whereby, refinery requires more than that.

Chromatograph:-
Chromatograph method can be used for both oil characterization of oil facility and refinery. However, to run chromatography analysis for unknown of carbon number of hydrocarbon might cost really high compared to boiling point lab test. Therefore, chromatograph method usually is being used for only for oil facility purposes which require lesser analysis of carbon chain. Normally, the oil will be tested up to C30+, where the heavies will be lumped as one component. Cost wise, chromatograph method is considered viable if the test will be done up to C30. So, this approach only can be used for oil facility since the function of oil facility just to separate among oil, gas, and water. Whereby, the function of refinery is to process further on heavies who are having group of products and it needs more detail of the cut points. Therefore, it is advisable to characterize crude in different approach for both oil facility and refinery.

So, boiling point approach can be used for both characterization but relatively more expensive for oil facility relative to chromatograph method. Chromatograph method can be used still for both cases but relatively more expensive for refinery. As a conclusion, boiling point lab test result more viable and practical to use for refinery application and chromatography analysis for oil facility application.

Gas Processing Method

Gas must be treated before it can be sent on to the final customer. Three primary methods of treating gas are adsorption, absorption and catalysts. These methods are performed in closed process equipment.

Absorption is the disappearance of one substance into another so that the absorbed substance loses its identifying characteristics, while the absorbing substance retains most of its original physical aspects. Used in refining to selectively remove specific components from process streams. One simple absorption process, which is also very common, is the use of glycol to absorb water from gas.

Adsorption is the adhesion of the molecules of gases or liquids to the surface of solids, as opposed to absorption, in which the molecules actually enter the absorbing medium (see adhesion and cohesion). Certain solids have the power to adsorb great quantities of gases. Charcoal, for example, which has a great surface area because of its porous nature, adsorbs large volumes of gases, including most of the poisonous ones, and is therefore used in gas masks. Certain finely divided solids have great adsorptive properties; for example, minute particles of platinum attract and hold multitudes of hydrogen molecules on their surfaces. Its ability to adsorb other gases makes platinum very useful in the production of sulfuric acid by the contact process and in the preparation of ammonia.

Definitions
Dry Gas: Natural gas with so little natural gas liquids that it is nearly all methane
Sour Gas :Natural gas that contains corrosive, sulfur bearing compounds such as hydrogen sulfide and mercaptans.
Fuel Gas :Refinery gas used for heating
Desulfurization :a process in which the principal purpose is to remove sulfur from gas.
Knockout Drum :A vessel wherein suspended liquid is separated from gas or vapor Hydrogen Sulfide
Dehydration or drying of gas is accomplished by the use of water absorption or adsorption agents to remove water from the gas.

Refer to diagram below for a simple system.

The wet gas is sent to the glycol contactor. The contactor is a drum filled with trays or a mesh to maximize the mixing of its input products. Glycol is a liquid with a great affinity for water. Glycol does not absorb natural gas.

The glycol is pumped into the upper section of the contactor drum where it cascades down the inside of the drum coming into contact with the gas, which is bubbling upward. At this point the glycol absorbs any water that is in the gas. The dry gas goes out the top and the liquid glycol, now combined with water, goes out the bottom. The glycol is regenerated and then sent to the contactor drum again.

Not all of the glycol goes out the bottom on the contactor. A small mist of glycol will go out the top with the gas. Therefore a glycol knockout drum is used to get the last of the glycol out of the stream.
Desulfurization: Sour gases are dried and sweetened. Sweetening removes sulfur and also reduces concentrations of carbon dioxide.
Note, this section is about recovering sulfur from natural gas, keep in mind that sulfur is also removed from liquids.

Sulfur Recovery from hydrogen sulfide. Sulfur recovery converts hydrogen sulfide in sour gases and hydrocarbon streams to elemental sulfur. The most widely used recovery system is the Claus process, which uses both thermal and catalytic-conversion reactions. Sulfur is separated from natural gas as hydrogen sulfide and then converted to elemental sulfur by the Claus process, which involves the partial burning of hydrogen sulfide to sulfur dioxide

Hydrogen sulfide or h2s is an extremely toxic gas that smells like rotten eggs. It commonly occurs in natural gas and must be removed.

First, the hydrogen sulfide is absorbed from the natural gas at ambient temperature in a scrubber, either in alkanolamine-glycol solution or in aqueous alkaline carbonate solution. This scrubber works much like the glycol concentrator mentioned above/

Second, the hydrogen sulfide is partially oxidized to SO2 with considerable evolution of heat:

Third, this resulting sulfur dioxide is then reacted with hydrogen sulfide in the presence of Fe2O3 as a catalyst to yield the more conveniently handled elemental sulfur:

Removal of free sulfur: Sulfur also occurs in natural gas as a free element. This material is removed in a vessel by running the gas through an aluminum sieve. The free sulfur will adsorb on the aluminum. The aluminum then catalyzes or burns the sulfur to eliminate it. In cases of large amounts the sulfur is recovered and sold as a marketable by product.

Onshore and Offshore

There is ultimate goal of both onshore and offshore operation which is to produce oil, gas, and/or petrochemicals. This is eventually will give or produce dollar and cent which is the main business of all personnel. Besides, all the personnel in both environement are really concern also on the Health, Safety, and Environment as this is one of the companies policy. All the personnel in both operation need to go to all related technical and safety training in order to certify them as capable as a operator, supervisor, superintendent, etc.

However, there are lot more differences that not really realised by us when thinking of designing or conducting any study to both operations. Definitely, there are lot of assumptions or considereations to be taken into account as it is normal practise in engineering practise eventhough those assumptions or considerations are from experiences or best practises that being practised in oil and gas. So, there are some assumptions or considerations may valid or invalid depending on the operation to be developed.

Let us go into the differences that could be observed in this industry that sometime people very rarely realised. This is not highlighted blindly here but from the observations are being done by all the personnel that experienced in either onshore or offshore. This is because sometime because of the pressure was put to the designer of either plant or platform might cause to this to happen. All these issues raised might be very ridiculus but it might happen and already had happend nowadays and anywhere even all the lead engineers having experience more than twenty (20) years but still can make some silly mistake which can cause to additional modification even the platform already fabricated. So, this articles basically will give some ideas on what are the key area usually really need to be taken into account to avoid any unwanted to happen. There are many issues can be highlighted that can be found in oil platform usually since having very limited freedom to modify or "disturb". Some of it are such as plan layout and space availability, spare parts (start-up, normal operation, critical, etc), production profiles (water cut, sand presence, etc), etc.

When discuss about plant or platform layout dealt with all those piping engineers and partially other disciplines will get involve too. This is because all the routing of piping will be done by the piping engineer. Sometimes, there is tendency of blank spot whereby the spotted area is not occupied by the piping, equipments, valves, etc which is really crucial in platform layout design. This is mainly because of the space flexibility is not there compared to plant where still have huge area can be manipulated by rerouting the access road. Besides, when designing the layout of the platform, all the blind spots for the crane operator must be reduced to zero. This is because crane usage is really essential when dealing with maintenance work and need this crane to lift it. As usual this is not an issue for the onshore plant or oil facilities since it can be assessed by anywhere even there is some constraints but relatively much lesser than platform (in the middle of the sea). In addition, there must be couple of safety studies to be done prior to installation of crane for example which dealing with human being to operate it all the time. For instance, if crane is located near to any devices that can contribute to heat, radiation, etc might can cause lost time injury (LTI). However, there is scenario where this might still can happen.

What can be seen is that, crane operator still really is exposed to the exhaust gas from the turbine generator. Sometimes, this type of scenario might happen if the decision been made once the platform almost at the completion stage.

There will be some best practises to be published during coming articles. This is mainly to share the experience in oil, gas, and petchem industry when designing or operating it.