GA Drawing

GA sounds like GH but here is General Assembly which is very important when designing plot plan. This GA drawing is basically a product from plot plan design. This GA drawing will be used from the beginning of the plant/platform until infinite. This is because of the necessity as guidance for space availability. From this GA drawing most of area related to design need to be considered such as pipe rack coordination, pump location, maintainability, equipment installation, hydraulic calculation, etc.

The pipe racks really important when designing the piping route which really dependent to GA drawing which eventually will dictate overall of the process stream. This is because of the products processed are being transported through piping from one unit to another unit (processing area or storage). Besides, this GA will give some idea on the restriction area to be routed such as road access which will affect to the safety and end up with lost time injury, LTI. As everyone aware, nobody wants LTI to be recorded to show the credibility of the company.

This GA drawing will assist a lot in term of pump installation when taking into consideration of the net suction positive head. An engineer can know some idea on the location to be located when deciding the new pump during any expansion.

In addition, this GA drawing also can be used for the preparation of both owner and contractor when planning for maintenance works. This is really crucial when the works need some cranes or fork-lift which is commonly used during the maintenance work usually during turn-around. Besides this machinery they are also some other considerations need to be taken into account. For example, space availability for cleaning any tube bundle which is really common thing to happen during turn-around.

As highlighted for pump installation it goes similarly for new equipment to be installed when new expansion or initiative implemented. This is again will dictate to identify the area where the equipment to be installed before verifying it at site. This will also tell whether the equipment to be installed to be totally new big equipment or just a baby equipment to cater additional capacity. The space availability sometimes can control the design of the equipment for expansion.GA drawing will give the dimension of the distance and the size of the equipments (length and width) which actually can be used for hydraulic calculation as a rough estimation to make judgment on the routing the piping or installing the new equipment.

Confined Space

Confined space by meaning itself means that very limited or closed area. From the definition, what can be seen that something present in very few quantity which is oxygen in this case. This is the term used in oil, gas, and petrochemical industry. This is actually as requirement for personnel when dealing with entrance of the unit operation. All the personnel that involved must have entrance permit to confined space which will be issued by the doctor examined the personnel to assure that he/she is fit to conduct the job.

This confined space must be blown with air by blower in order to sustain the oxygen content so that personnel inside can breathe as usual. Besides, when entering the confined space, personnel must present their identification card to hole watcher or safety officer. This is mainly because of the safety consideration that needs to be addressed so that can monitor number of the personnel in that particular equipment to avoid crowd.

People might be asking why respective personnel need to enter the equipments and when they have to. This is mainly done during turn-around where the plant (mainly downstream) will be shutdown as planned shutdown to inspect the equipments such as vessels, towers, reactors, etc. It is not only conducted during planned shutdown but also unplanned whereby unwanted scenario happens. This is basically happens during plant upset or any unit operation upset due to any failure, rupture, leakage, etc. Therefore, there must be somebody need to go in the affected equipment(s) to inspect any findings could be observed. From the findings found, there would be some initiatives to be taken to rectify the problem and come out with plan to prevent in future.

People might be asking also why need to go inside the equipment even there are monitoring (corrosion) points as given the diagram below. Unit operation might have all those indicators but most of the time the indicators only can show us the result of from the impact such high pressure drop, off-spec product, corrosion behavior, etc. So, in order to rectify it related personnel from operation, maintenance, and inspection need to go inside to conduct detail study.

Here are sample of the signs that can be seen near to area that classified as confined space and require permit to enter with presence of safety officer.

Corrosion Monitoring

Corrosion is a natural phenomenon which will occur but will vary on the rate depending on the environment and the material. Corrosion not only taking place in industry generally or oil and gas specifically but also everywhere which are not really noticed by human being. For instance, many of car manufactures are having some sort of antirust which giving some coating on the surface of the car body to prevent from corrosion taking place. This antirust scheme is not a whole life guarantee given by them but just for some time only. What can be seen from here is that the coating mechanism only can sustain for limited time only and again need to be coat again with the presence of car polishing companies. So, even coating mechanism itself facing corrosion problem where they lose of the coating film on the car body. Here where the material taking the action but some other scenario where environment will take action. For example, those cars exposed to beach area more prone to corrode since the environment is corrosive.

Corrosion is everyone issue which need to be addressed by everyone, everywhere, and every time. However, the corrosion that taking place in industry is more severe compared to non-industry related. This is mainly because of the function of itself where in industries, corrosion like a culprit to production. If the corrosion persists, the production line has to be shut-down since the safety always become on the top priority even ultimate aim of industries are to make profit. Therefore, there lot initiatives have been taken and being done in all level to monitor the corrosion. This mainly to study the suitable material to be used in related industry and way of minimizing the rate of corrosion. There are lot of proprietary chemicals are being used as a corrosion inhibitor to inhibit the corrosion. Again this corrosion can behave very differently for different application and they need different chemicals as a corrosion inhibitor. There is detail study to be done when procuring any vendor chemicals to avoid any off-spec products which can cause billion dollars losses. Thus, corrosion monitoring is important to identify the behavior of the fluid exposed to the material (piping, vessel, etc.). There are many ways of monitoring and one of it has been discussed on corrosion coupon. In addition to that, electrical resistance (ER) and linear polarization resistance (LPR) also have been successfully applied and are used in an increasing range of applications.

ER probes can be thought of as “electronic” corrosion coupons. Like coupons, ER probes provide a basic measurement of metal loss, but unlike coupons, the value of metal loss can be measured at any time, as frequently as required, while the probe is in-situ and permanently exposed to the process stream.

The LPR technique is based on complex electro-chemical theory. For purposes of industrial measurement applications it is simplified to a very basic concept. In fundamental terms, a small voltage (or polarization potential) is applied to an electrode in solution. The current needed to maintain a specific voltage shift (typically 10 mV) is directly related to the corrosion on the surface of the electrode in the solution. By measuring the current, a corrosion rate can be derived.

Design HX

Simulation tools always need the physical properties to define the stream or to conduct the study on any particular issue. This is crucial because of the Mother Nature to have some identification as human being as well. This principal goes same to anything and everywhere; if you are employee you must have ID number which is your identification in that organization. Generally categorization is needed when dealing with anything and characteristics of the stream needs either specifically.

In previous article on Oil Characterization, there were some key points highlighted when characterizing the crude which later will affect the sizing of whole equipments of the facility.
Similarly happens here on designing a heat exchanger where there couple of physical properties needed if the pure components not available for the streams that being studied to design or rating the heat exchanger. As goes as characterizing the crude, the right properties at right condition need to be taken or be available when keying in the data into the simulation tool (HTRI, HEXTRAN, etc.)

There are about four physical properties necessary when designing the heat exchangers which are specific heat, viscosity, thermal conductivity, and density. All these physical properties need to be taken for two different conditions. In addition, the referred conditions must be giving the range of the temperatures of the initial temperatures and targeted temperatures. This is very crucial because of the extrapolation will be done in between the range provided or else the result can be challenged because of the consistency error.

Wastes

Everyday wastes are being produced by us either by household or industrial. The waste itself has the category and phase. Most of human being might be thinking that industrial waste has the huge impact to the environment rather than household waste. However, this article will show that perception slightly not right to say. This is because of the way of disposing it. In this article, different types of waste such as waste gas (gas effluent), waste water, and solid waste will be covered which is really crucial when managing waste.

Waste gas or more commonly known as gas effluent or the waste produced in gas or vapor form from industry mainly and very little portion from household. There are bunch of gaseous that being monitored before it is discharged to the environment such as carbon oxide (COX), NOX, sulfur oxide (SOX), particulate matter, volatile organic compounds (VOCs), hydrogen sulfide (H2S), etc. Beware also there is also potential of harm our household sewage line that releasing hydrogen sulfide which can cause fatality. This has happened even not in house but in living quarters of ship which shows that there is tendency to occur since there function only deals with sewage system. Besides these direct releases, there are also volatile organic compound is being released from solid waste disposal which releases methane from the anaerobic reaction. There is commercial approach is being practiced to monetize the methane but so far people generally not really interested yet to monetize it since it is not really profitable enough.

Waste water generally covers most of the industry and also household effluent after the treated water has been used. Again in industrial waste there are experts working on it to come out with latest technology to minimize the impact to the environment. Whereby, lack of awareness in household application, the effluent for water is discharged to common drainage system which not really measures the containment of anything that can impact the environment. For example, used cooking oil will drained together with used water in sink which can cause troublesome to the whole line. If noticed, all these happening because of the lack enforcement of the law for the residential area. However, for those thinking that industrial can cause harm the environment are the one actually treating the effluent before it is discharge. In fact, the effluents are treated step by step to achieve all the parameters as regulated by the regulatory bodies. There are couples of elements to be covered when treating the waste water such BOD, COD, suspended solids, temperature, etc. There are guidelines to be followed by the industry but none of guideline is given to household.

Now come to solid waste where this is the ultimate waste that would come if gas and/or water are treated. As for solid waste, the waste can be easily monetized if the good practice can be practiced from the beginning of throwing the waste/rubbish to the dustbins. And again it comes from our awareness to implement it. Nowadays lot of campaigns can be seen everywhere to throw the rubbish into different dustbins so that the garbage already segregated before it is collected. Besides that the categorized can be categorized straight away such as paper, plastic, etc. In addition to direct monetization, there is also direct monetization as highlighted above such methane gas produced from solid waste landfill.

Flow Fraction – Part II

In the previous article on flow fraction, there are issues were discussed on the importance of the consideration while designing the heat exchanger. Although there are about five main streams when analyzing the flow fraction but the mainly emphasized are flow B and flow E. As highlighted in previous article, B must be greater than 40% and E must be less than 20% and the remaining can be mixture of the portion. So, some time or most of the time, heat exchanger will be over designed or over sized to cater the desired temperature but very rare consideration is given on the flow fraction analysis. In this article, flow fraction analysis will be covered on how it can be optimized.

This flow fraction takes place in shell side and directly affected by the shell side configuration and its fluid. So, configuration on the shell side can be modified in order to enhance the flow fraction.

Direct configuration that affecting the flow fraction are both baffle spacing and baffle cut. So, baffle spacing and cut shall be optimized as recommended by TEMA (Tubular Exchanger Manufacturer Association). For example, minimum baffle spacing recommend by TEMA is about 1/5 of shell inner diameter and 20-40% of baffle cut.

Nowadays all these can be done via sophisticated software such HTRI, HTFS, etc. So, as part of heat exchanger analysis, flow fraction analysis can be done since it could be presented by the software. However, as ultimate of heat exchanger warranty again dependent on vendor design and sometime the vendor would declare that they will guarantee the performance even sometime won’t behave as claimed by them. Usually the owner will let the vendor finalize it but as an engineer that designing and reviewing for engineering firm and owner respectively can use this approach to challenge the design done by the vendor. It’s again “Vendor Package” that cannot be argued so much.

Corrosion Coupon

The Weight Loss technique is the best known and simplest of all corrosion monitoring techniques. The method involves exposing a specimen of material (the coupon) to a process environment for a given duration, then removing the specimen for analysis. The basic measurement which is determined from corrosion coupons is weight loss; the weight loss taking place over the period of exposure being expressed as corrosion rate.

The simplicity of the measurement offered by the corrosion coupon is such that the coupon technique forms the baseline method of measurement in many corrosion monitoring programs. The technique is extremely versatile, since weight loss coupons can be fabricated from any commercially available alloy. Also, using appropriate geometric designs, a wide variety of corrosion phenomena may be studied which includes, but is not limited to:

• Stress-assisted corrosion
• Bimetallic (galvanic) attack
• Differential aeration
• Heat-affected zones

Advantages of weight loss coupons are that:

• The technique is applicable to all environments - gases, liquids, solids flow.
• Visual inspection can be undertaken.
• Corrosion deposits can be observed and analyzed.
• Weight loss can be readily determined and corrosion rate easily calculated.
• Localized corrosion can be identified and measured.
• Inhibitor performance can be easily assessed.

In a typical monitoring program, coupons are exposed for 90-day duration before being removed for a laboratory analysis. This gives basic corrosion rate measurements at a frequency of four times per year. The weight loss resulting from any single coupon exposure yields the “average” value of corrosion occurring during that exposure. The disadvantage of the coupon technique is that, if a corrosion upset occurs during the period of exposure, the coupon alone will not be able to identify the time of occurrence of the upset, and depending upon the peak value of the upset and its duration, may not even register a statistically significant increased weight loss.

Therefore, coupon monitoring is most useful in environments where corrosion rates do not significantly change over long time periods. However, they can provide a useful correlation with other techniques such as electrical resistance, (ER) and linear polarization resistance, (LPR) measurements.

Flow Fraction

Flow fraction usually deal with the vapor fraction and liquid fraction. However, here is something different will be discussed which is related to shell and tube heat exchanger. There are bunch of criteria that need to be considered but flow fraction on the shell side flow fraction will be highlighted since this criteria is not really taken into consideration when designing a new shell and tube heat exchanger, (STHX).

As illustrated above, there are about five main flow in the shell side where only one (B) out of five is cross flow and the remaining (A, C, E, and F) are leak-flow or bypass. There are proposed calling for these streams; main cross-flow stream (B), a tube-to-baffle-hole leakage stream (A), a bundle bypass stream, a pass-partition bypass stream (F), and a baffle-to-shell leakage stream (E).

As vapor and liquid fraction, there is a requirement to meet the specification of any particular product before sell it off. So, same goes to the shell side flow fraction of the STHX where the minimum design criteria is that B fraction must be greater than 40% and for E is less than 20%. So, it’s not necessary yet to increase the size of the heat exchanger if this specification not met. There are couple of optimization can be done to get the desired temperature for any particular stream.

The tricky part of the optimization of STHX will be elaborated in detail in next article. Those will explain the areas that can be used to challenge design engineer during design review. In the meantime, design engineer can use that info also to enhance the design