Catalysis 2024 Issue

Observations: It is observed that the test results of both methods correlate quite well. ASTM D4860 is a spectro- scopic method with a wide scale, so it may be more use- ful. Also, ASTM D4860 is instrumental in detection, which avoids human error, resulting in more accurate test results. Moisture removal by alternative techniques Aim: To review the alternative techniques for removing moisture or improving haziness. At laboratory conditions, both a salt dryer and silica gel were tested to remove mois- ture from hydrocarbons, but other techniques such as cal- cium chloride are also available. Exp. condition: For this experimental work, a 500 ml capacity laboratory setup made of glass and a hazy diesel sample with a numerical rating of 6, as per ASTM D4176, P-2, were passed through a bed prepared using rock salt or silica gel. Figure 5 shows a silica gel bed with a glass assembly developed in-lab and used for experimental work. The rock salt (sodium chloride) technique is quite sim- ple, effective, and used to remove moisture from aviation turbine fuel at most refineries. Rock salt is hygroscopic in nature; hence, it adsorbs water molecules. The solubility of sodium chloride in water is around 359 grams per litre, which means that one metric ton of salt can absorb around 2.78 tons of water. The rock salt make-up is from the top, and saturated salty water generated can be easily drained from the bottom, which is much easier than replacing a solid absorbent bed and handling spent absorbent. It will also save the time required to replace the absorbent. The various experiments were conducted using DHDS dryer inlet diesel samples with a hazy appearance at dif- ferent flow rates. The salt dryer outlet samples with a CB appearance and moisture content were found in the range of 70-90 wtppm at respective flow rates of a minimum of 2 ml to a maximum of 50 ml per minute. Silica gel can absorb water up to 40% of its weight. The observed test results are quite encouraging and meet the specification requirements for moisture and appearance. However, more experimental work is needed to calculate exhaust capacity and how to manage spent silica gel. It can be regenerated by thermal treatment. The calcium chloride is also capable of absorbing water up to 300% of its weight. The calcium chloride briquette is also used for removal of moisture. Observations: To avoid bed replacement activity and han- dling of waste generation, the salt dryer technique may be the preferred option among the above moisture removal absorption techniques. Conclusions From the various test results and observations of experi- mental study work, it is concluded that the haziness in the studied diesel samples is not due to any surfactant types of chemicals. The diesel vacuum dryer operation performance can be controlled and improved by increased residence time, temperature, and vacuum level, or a combination of all three variables. The numerical haze rating and haze stability data are extremely useful for taking corrective and preven- tive action to control haziness upstream or downstream.

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Clear & Bright rating by D4860

Figure 4 Correlation of haze rating between two test methods

Exp. conditions: In this experimental work, various diesel samples were evaluated for moisture content and haze rat- ing by ASTM D4176, P-2 and ASTM D4860. Test results: The observed test results are graphically pre- sented in Figure 3 . Figure 3a shows the correlation of mois- ture vs haze rating by ASTM D4176, P2. Figure 3b shows the correlation of moisture vs the CB rating by ASTM D4860. Observations: The following are observations from the cor- relation study:  Moisture in the range of 76-130 ppm correlates with a CB rating of 95-100 and a haze rating of 1.  Moisture in the range of 130-175 ppm correlates with a CB rating of 80-94 and a haze rating of 2.  Moisture in the range of 175-275 ppm correlates with a CB rating of 72-79 and a haze rating of 3.  More data are required to correlate haze ratings above 4 or CB ratings less than 70. Haze rating correlation between ASTM D4176, P-2 and D4860 Aim: To develop the correlation between haze rating test methods ASTM D4860 and ASTM D4176, P-2. Exp. conditions: In this experimental work, various diesel samples were evaluated for haze rating by ASTM D4176, P-2 and ASTM D4860. Test results: The test results of both methods are shown in Figure 4 .

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Figure 5 Glass assembly used for salt dryer and silica gel experiment

Catalysis 2024