Pilot studies based on modified uaod process - Education Essay Example

5 - Pilot studies based on modified uaod process introduction.1 Introduction

The objective of developing modified UAOD process is to produce ultra low sulfur or “0” sulfur diesel fuel with high desulfurization efficiency under ambient temperature and pressure. From chapter 3 and 4, with modified UAOD process, it provides high selective removal of organic sulfur compounds either model sulfur compounds or various kinds of diesel fuels by combination process of oxidation, solvent extraction, and/or solid adsorption.

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From chapter 3 and 4, the process is carry under batch process, all the reaction component were combined and performed under controlled conditions until the desired process endpoint has been reached. Reactions are typically slow, taking hours, and the treatment quantity are low. In contrast, the continuous flow system can be operated at steady state with reactants continuously coming into the reaction vessel and product continuously leaving. The nature of continuous flow system can permit itself to large productivities and great economic of scale than the cyclic operation of batch reaction (Nauman, 2001). Please rewrite the red part that shows above.

Until the needed end result was reached in the process, all the reactive ingredients were put together into the process in a controlled manner. It is to be noted for reactions tend to be sluggish (usually spanning over hours). Moreover, the conduct volume is low. On the other hand, it is possible to process the continually running scheme at a constant rate in the manner that the reactive components constantly enter the reaction pot so that the end produce leaves on a constant pace. The point worth-mentioning, with regard to the continually flowing system, is that it can be highly contributing to large procuction resulting a higher profit turn outs or financial gains as compared to the cyclic system of operation.

As we know, the development of a new chemical process that involves major technical and economical effort should meet a definite and practical need of an industry. The nature of petroleum refining prefers the use of continuous flow system for long production runs of high volume fuel streams. Furthermore, as compared with batch reactors, continuous flow reactors tend to be easier to scale up and control, the product is more uniform, materials handling problems are lessened, and the capital cost for the same annual capacity is lower (Missen, et al. 1999). Therefore, pilot study is necessary. Please rewrite the red part that shows above.

For the success of an industry, it is generally known that it is necessary for a new chemical process to take into account chief key components both technology and finance-related. These must be clearly realized and feasible for use. As such there is the petroleum refining system which prioritizes the constantly flowing method so that high scale production with great fuel outlets can be met. Moreover, it is easier to manage and measure the constantly flowing reactive components than those of group. It is because in the continuously flowing system the hitches are not so many; the produce becomes organized; and, the yearly cost for capital in also less. (Missen et al. 1999). Henceforth, it is necessary to execute a pilot stuty.

The term pilot study is used in two different ways in social science research. It can refer to so-called feasibility studies which are “small scale version[s], or trial run[s], done in preparation for the major study” (Polit et al., 2001: 467). However, a pilot study can also be the pre-testing or ‘trying out’ of a particular research instrument (Baker 1994: 182-3). One of the advantages of conducting a pilot study is that it might give advance warning about where the main research project could fail, where research protocols may not be followed, or whether proposed methods or instruments are inappropriate or too complicated. Pilot studies can be based on quantitative and/or qualitative methods and large-scale studies might employ a number of pilot studies before the main survey is conducted. Thus researchers may start with “qualitative data collection and analysis on a relatively unexplored topic, using the results to design a subsequent quantitative phase of the study” (Tashakkori & Teddlie 1998: 47). Please rewrite the red part above, can you summarize into 9-10 sentences.

In the social sciences research, the term PILOT STUDY is defined and executed in two different paradigms. One is the small-scale check-up study which is done to execute a large study of the same nature. (Polit et al. 2001: 467). However, according to Baker (1994: 182-3), a pilot study may also be the one which tries out a specific research tool. One very salient feature of performing a pilot study is that it can in time tell the researcher about the possible failure that a study may meet, or the hurdles that might rise, or that where the suggested tools and methods may not be appropriate or may be out-of-the-fit. Before executing a major study, numerous pilot studies may be performed. They can be conducted either from naturalistic or qualitative paradigm. Thus, a pilot study can help the research to gather qualitative data and its analysis for a major study and its design and so forth (Tashakkori & Teddlie 1998: 47)

In this chapter, a complete new desulfurization system with continuous-flow modified UAOD process and fluidized bed adsorption units was developed. The effectiveness of system on two different diesel fuels was evaluated. Finally, a preliminary economic study for new desulfurization system and UAOD process was conducted. Please rewrite the red part above.

Here, a thoroughly new system for desulphurization was established. UAOD (continuous-flow) and fluidized bed adsorption processes were developed. The efficiency of the system was measured on two non-related diesel fuels. Eventually, a primary financial study for new desulfurization scheme and UAOD was performed.

5.2 Materials

            Two diesel fuels were used as the feedstock in this study. (1) Diesel fuel with sulfur content of 8,100 ppm (Valley Oil) were received from Golden Eagle Oil Refinery, INC. (2) Marine logistic fuel (F-76) with sulfur content of 4,220 ppm were received from U.S Army.

            Tetraoctylammonium fluoride used as phase transfer agent (PTA) was synthesis from (Dermeik, et al. 1989). Acetic acid, tri-fluoro acetic acid (TFA) as catalyst, 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIM][EtSO4]) as ionic liquid and aluminum oxide (activated, acidic, Brokmann I, standard grade, ~150 mesh, 58A) as adsorption media were obtained from Aldrich Chemical. 30% hydrogen peroxide (H2O2) as oxidant and acetonitrile as extraction solvent were obtained from VWR Inc.

5.3       Apparatus and Experimental Procedure

5.3.1 High Shear Mixer

High shear mixer is a single stage rotor/stator generator specially contoured to generate high shear and vigorous flow in a batch mixing environment. It can produce an intense combination of mechanical and cavitational shear, which results perfect mixing condition. Figure AAA shows the flow pattern created by the mixer.

In an group mixing environment of high cut off and huge flow is the high cut off blending generator which has single stage rotor or stator. It can generate a high blend of both automatic and cavitational shear. This is turn produces condition which is perfect for blending. (Figure AAA manifests this.).

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Figure AAA (Charles Ross & Son Inc.)

In this research purpose, high shear mixer has been rent from Charles Ross & Son Company, model HSM-100L has been used for pilot study. Figure WWW shows the photo of model HSM-100L and figure wxy shows the photo of rotating blade.

For the present research for pilot study, a high shear mixer, HSM-100L, was rented from Charles Ross & Son Company. Figure WWW is the photograph of the model; and Figure wxy displays the rotating blade.

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One of the main features of this mixer is that it can provide different rotation speed from 1 to 10,000 rpm. With batch study, with magnetic stir bar, it can only provide up to 1,000 rpm, it may provide enough mixing condition for batch, but may not be enough for pilot study. (please rewrite the information that I discuss above).

One of the salient characteristics of this mixer is its rotation speed from 1 to 10,000 rpm. However it can only provide 1,000 rpm with magnetic stir bar and batch study so falling short of the requirements of the pilot study, although the mixing conditions may be sound enough.

5.3.2 Batch type continuous flow system and its operation

            Figure BBB shows the block diagram of batch type continuous flow system. Generally, two reactant feed streams: (1) aqueous phase with H2O2, IL and catalyst (2) high sulfur content diesel were peristaltically pumped into the reactor through port located on the higher side of the reactor. The exit mixture came out of the reactor by overflow through port located on the lower side of the reactor. The maximum capacity of the reactor is 1.8 Liter with working volume of 1 liter. Since the high shear mixer is “dipped” directly into the reaction mixture where it is capable of generating mixing condition, this system can be viewed as a continuous stirred tank reactor (CSTR) system. The reactor has been custom made by USC glass blower, the reactor size is 15 cm diameter with 30 cm height with 0.3 mm thickness. Figure CCC shows the photo of the reactor.

In Figure BBB is the diagram of the batch type continuous flow system. Commonly, two feed streams of reactive nature, i.e. aqueous phase with H2O2, IL and catalyst (2) high sulfur content diesel were peristaltically pumped into the reactor through port located on the higher side of the reactor. AS a result, the reactor emitted exit mixture in overflow state out of the port positioned on the lower side of the reactor. With working volume of 1Liter, the maximum capacity of the reactor is 1.8 Liter. The fact that the high shear mixer is “dipped” directly into the reaction mixture (proficient here to generate mixing condition), the system, as such, can be classified as continuous stirred tank reactor (CSTR) system.

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During the mixing inside the reactor, oxidation occurs, at mean time, portion of the oil/aqueous mixture were recycle back to reservoir, this process is continue until 99.9% of organic sulfur compounds OSCs has been oxidized. After completion of oxidation, aqueous phase were passing through de-watering units to remove water that form from reaction, and new portion of catalyst and oxidant were add into reactor. The oxidized diesel were pump thought fluidized bed reactor with alumina, finally, ultra low sulfur will be the effluent. (please rewrite the information that I discuss above).

Oxidation takes place while mixing in the reactor. At mean time, portion of the oil/aqueous mixture were recycled again to tank. Until 99.9% or organic sulfur compounds (OSCs) are oxidized, the very process is constantly taking place. Once oxidization is complete, aqueous phase passed through dewatering units so that water formed from reaction can be wiped off. More quantity of catalyst and oxidant was added to reactor. The oxidized diesel was then pumped through fluidized bed reactor with alumina. Ultimately, the effluent will be the ultra low sulfur.

5.3.3 Fluidized bed reactor and its operation

            Two glass vessels have been purchased from Chem-Glass, with diameter 55 mm and 150 mm in length. For glass vessel were pack with alumina, first, glass fiber wool were place at bottom of vessel to avoid the alumina loss (to avoid leak out: you can see from the photo), then, fresh alumina is add on the top of glass wool, at mean time, toluene were also add to remove the air bubble between the alumina. After both glass vessels were fulfill with alumina, it is connect and seal with clamp, Figure ASF shows the fluidized bed reactor for pilot study. (can you try to make this paragraph more sense according to the following to photos).

Two 55 mm (150 mm length) glass vessels, were purchased from Chem-Glass, and were packed with alumina. To avoid the loss of alumina (or leak out), glass fiber wool was placed at the bottom of the vessels (Photo follows). The on the top of glass wool, at mean time, fresh alumina was added; toluene was added to keep the alumina free from air bubbles. Once both glass vessels were filled with alumina, they were connected and sealed with a clamp (Figure ASF for fluidized bed reactor pilot study).

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Figure ASF

5.3.4 Experimental Methods

            The batch type continuous flow system exclude fluidized bed reactor was set up as described in previous section. Figure NN shows the photo of experimental setup, arrow shows the direction of flow.

As discussed in the previous section, the batch type continuous flow system which excludes fluidized bed reactor was set up. (Figure NN shows the photo of this experiment with arrows pointing to the directions.)

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Reactants was store in two solutions: (1) diesel fuel and (2) hydrogen peroxide (30 vol% solution) containing acid catalyst and RTIL were fed into the reactor by two peristaltic pump (Masterflex, Cole-Parmer, USA). The flow rates of both solutions was measured and adjusted equally according to the chosen residence time and to maintain a constant oil/water ratio of 10:1 in the reactor.

Reactants were stored in two solutions, that is, (i) diesel fuel and (ii) hydrogen peroxide (30 vol% solution). Acid with catalyst and RTIL were inserted into the reactor by two peristaltic pumps: Masterflex, Cole-Parmer, USA. The flow rates of each solution were measured and adjusted in accordance with the chosen residence time and a constant oil/water ration of 10:1 in the reactor was maintained.

The mixture in the reactor was agitated stir by high shear mixer. The sample of the effluent were collected at the time with 10, 20, 30, 40, 60, 80, 140 and 200 minutes. In each time interval, 3 ml of samples for collect. Several experiments has been done, this include: (1) different mixing strategy, (2) different amount of RTIL, (3) different amount usage and concentration of catalyst.

The mixture in the reactor was stirred by high shear mixer. The samples of the effluent were at the time intervals of 10, 20, 30, 40, 60, 80, 140, and 200 minutes to collect 3 ml of samples at each interval. Several experiments were done: (1) different mixing strategy; (2) different amount of RTIL, (3) different amount usage and concentration of catalyst.

            After oxidation of diesel, the oxidized diesel was extracted with acetonitrile for three times. Each time the solvent-to-oil (S/O) ratio was kept at 1:1 by weight (i.e., 1 gram diesel per 1 gram acetonitrile) and the mixture was shaken vigorously for 5 min at room temperature and finally separates the phase by centrifuge. Moreover, the total sulfur content was analyzed by a Sulfur-in-Oil Analyzer (SLFA-20).

            After oxidization of diesel, it was extracted with acetonitrile for three times and each time the solvent-to-oil (S/O) ration was maintained at 1:1 by weight (1 gram diesel per 1 gram acetonitrile). The mixture was then stirred vigorously for 5 minutes at the room temperature and which finally separated the phase by centrifuge. Moreover, the total sulfur content was analyzed by a Sulfur-in-Oil Analyzer (SLFA-20).

With adsorption, appropriate amount fresh alumina was packed into glass vessel that has been described at previous section. The oxidized diesel were pass through fluidized bed reactor by centrifugal magnetic pump (polypropylene, Cole-Parmer, USA), the pump has flow rate of 2.9 gallon per minute which provide enough power to pump the oil through bottom of the fluidized bed reactor to the top, and effluent were collect into 30 ml glass vial for total sulfur analysis. Figure CVB shows the experimental set up for fluidized bed reactor with flow direction represent by arrow.

With adsorption, appropriate amount of fresh alumina was poured into the glass vessels described at previous section. The oxidized diesel was passed through fluidized bed reactor by centrifugal magnetic pump (polypropylene, Cole-Parmer, USA). The pump has a flow rate of 2.9 gallon per minute with enough power to pump the oil down from the bottom of the fluidized bed reactor up to the top. Effluent was collect into 30 ml glass vial for total sulfur analysis. (Arrows in Figure CVB show the experimental set up for fluidized bed reactor)

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            For recycle the alumina, the saturated alumina is calcine with furnace, the starting oven temperature were 200oC for 30 minutes to evaporate the aqueous solution, than, increment 25oC for every 10 minute, until temperature reach 500oC. And 500oC were hold for 6 hours.

To recycle the alumina, the saturated alumina was calcine with furnace and the starting oven temperature were 200oC for 30 minutes to evaporate the aqueous solution. Then, it was increased 25oC for every 10 minutes, until the temperature reached 500oC which was held for 6 hours.

In modified UAOD process, the acid catalyst and RTIL played an important role to accelerate the reaction rate and enhance the oxidation efficiency. However, the wasted catalyst may cause to increase the capital cost and issue the environment pollutions. The complete catalyst recovery was essential to enhance the commercial viability of process. This study indicated that the acid catalyst and RTIL could be recovered and shows the same oxidation efficiency as the original catalyst. This information is essential to prevent the consuming cost of RTIL and acid catalyst to perform the optimization of desulfurization process.

The acid catalyst and RTIL were key players in the process of increasing the rate of reaction and the enhancement of the efficiency of oxidation all taking place in the modified UAOD process. None the less, it is possible for the waste catalyst to accelerate the capital cost and cause threats of environment pollution; as such, it was essential to completely recover the catalyst and improve the viability of the process from the viewpoint of commerciality of the process. The study suggests that the acid catalyst and RTIL can be recuperated. It also manifests that the same oxidization efficiency as was originally found in catalyst. The know-how of all this process is essential in order to prevent costs or RTIL from inclining and for acid catalyst to conduct the desulfurization process to the optimal level.

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