Standard Test For Ash From Petroleum Products , D482
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The document details an experiment conducted by Yasir Ammar Ahmed to determine the ash content of a residue crude oil sample using standard test D482. The procedure and results indicate that the ash content was calculated to be 1%, highlighting issues related to high ash contents leading to operational challenges in combustion. The document also discusses the relationship between ash and sulfur contents in crude oil, along with methods to mitigate ash formation during fuel combustion.
Standard Test For Ash From Petroleum Products , D482
- 1. Page | 1 University of Zakho Faculty of Engineering Department of Petroleum Engineering 2014-2015 Name of Student: Yasir Ammar Ahmed Class 2 / 2nd stage Experiment NO. 7 Standard Test For Ash From Petroleum Products , D482 Experiment contacted on: 12/1/2015 Report submitted on: 19/1/2014
- 2. Page | 2 Contents 1.1 Objectives -------------------------------------------------------- Page 3 1.2 Introduction ------------------------------------------------------ Page 3 1.3 Apparatus and Materials ---------------------------------------- Page 4 1.4 Procedure --------------------------------------------------------- Page 5 1.5 Result and Calculations -----------------------------------------Page 5 1.6 Discussion --------------------------------------------------------Page 6 1.7 Conclusion --------------------------------------------------------Page 8 Figure(1): Apparatus and Materials used in this experiment --------------- Page 4 Figure(2):Pendant superheater slag with corrosion product underneath. – Page 6 Figure(3): Treatment can make deposits friable for easy removal ----------Page 7 Table (1): Typical residual oil analyses ----------------------------------------Page 8
- 3. Page | 3 Standard Test For Ash From Petroleum Products , D482 1.1 Objectives To determine the ash content of a sample of Residue Crude Oil (RC). 1.2 Introduction Ash contents is defined as the inorganic residue that remains after combustion of the oil in air at specific high temperature. Ash ranges from 0.1% to 0.2%. The ash content of a fuel is a measure of the amount of inorganic noncombustible material it contains. Some of the ash forming constituents occur naturally in crude oil: others are present as a result of refining or contamination during storage or distribution. For instance, it could be due to the presence of compounds of the following elements: vanadium, sodium, calcium, magnesium, zinc, lead, iron, nickel. Or it could be picked up by the crude oil during storage and handling. Metals content above 200 ppm are considered to be significant but the variations are very large. The higher the ash content the higher is the tendency of the crude oil to form sludge or sediment. Oils containing more than 0.05% ash are considered high ash oils; those containing less than 0.02% ash are considered low ash oils. Knowledge of the amount of ash-forming material present in a product can provide information as to whether or not the product is suitable for use in a suitable application. Ash can result from oil or water-soluble metallic compounds or from extraneous soldier such as dirt and rust. Refining crude oil that contain high value of ash content leading to deposition of the metals (in any form) on to the catalyst leads to catalyst deactivation whether it be by physical blockage of the pores or destruction of reactive sites. In the present context, the metals must first be removed if erroneously high carbon residue data are to be avoided. Since most of the ash in heavy fuels occurs naturally, it usually is difficult for the refiner to remove it economically. Purchasing different crude oils with lower ash content can be very expensive. Therefore, methods have been developed for counteracting the effects of ash. These include the use of additives, modifications in equipment design, and the application of fuel processing methods such as water washing.
- 4. Page | 4 1.3 Apparatus and Materials 1. Crucible. 2. Stand. 3. Source of flame (heat). 4. Sample of residue crude (RC). 5. Scientific Balance. 6. . Stand Source of flame (heat) Scientific Balance Crucible Residue Crude (RC) Furnace Figure(1): Apparatus and Materials used in this experiment
- 5. Page | 5 1.4 Procedure 1. First of all we took a dry clean crucible and weight it with the scientific balance. 2. Record the weight of empty crucible which will be W1 . 3. Add 2 g of the sample (RC) to the crucible. 4. Record the weight of sample (RC) which will be W2 . 5. Put the crucible contain the sample on the stand and then poke the fire in the burner under the crucible and heat it carefully at such temperature that the sample continues to burn at a uniform and moderate rate leaving only carbonaceous residue wen the burning ceases. 6. Heat the residue at muffle furnace at 775 + 25 o C until all carbonaceous materials has disappeared ( 20 -30 mins). 7. Cool the crucible at room temperature in a suitable container. 8. Weigh the crucible this will be W3 . 1.5 Result and Calculations Weight of empty crucible, W1 = 17.9 g Weight of the test specimen, W2 = 2 g Weight of ash and crucible, W3 = 17.92 g To calculate the ash content of residue crude, we use this equation below: 𝑨𝒔𝒉 , 𝒎𝒂𝒔𝒔 % = 𝑾𝟑 − 𝑾𝟏 𝑾𝟐 × 𝟏𝟎𝟎 Where: W3 – W1 = mass of ash in grams W2 = mass of sample in grams 𝐴𝑠ℎ , 𝑚𝑎𝑠𝑠 % = 17.92 − 17.9 2 × 100 = 1%
- 6. Page | 6 1.6 Discussion 1. What is the problems of combustion of oils with high ash content? The combustion of high ash oils produced troublesome deposits on boiler convection surfaces such as steam generating, superheat, reheat, and economizer sections. The firing of high ash oils (even in those units which were originally designed to burn coal) produced convection surface deposition that was difficult to remove by soot blowing. The deposition of ashes problems is divided into two main problems: a. Slagging refers to deposits formed on sections of the boiler exposed mainly to radiant heat, such as the furnace walls. Slagging deposits are formed from molten or half molten ash particles that stick to the hot furnace walls. They are not formed immediately upon firing up the boiler but accumulate slowly after an initial layer has been formed over the walls. b. Fouling is used to characterize the deposits formed on the convective pass, such as the heat exchanger tubes. In this case, deposits are formed by inorganic vapours that condense on the relatively cooler surfaces of the heat exchanger tubes. Although the mechanisms of formation for slagging and fouling are not the same, both are closely linked with the tendency of the fuel ash components to melt or vaporize at low temperatures. Figure(2):Pendant superheater slag with corrosion product underneath.
- 7. Page | 7 2. How you can decrease the ass formation in fuel combustion? Additives are used to control fouling by elevating the melting point of the deposits, by physically diluting deposits, or by providing a shear plane to assist in removal by soot blowing. Additives used to control fouling contain magnesium, silica, manganese, and/or aluminum. The melting point of untreated ash constituents can be as low as 1000°F. The introduction of appropriate metal oxides elevates the melting point of ash components by several hundred degrees. The additive components most commonly used to raise the deposit melting point are magnesium and/or aluminum. Dosages depend on ash levels in the fuel and the ratio of various ash components. When melting temperatures are raised, the physical characteristics of the deposits are altered. Often, the heaviest deposition occurs in areas where the gas temperature is lower than the melting temperature of a deposit. Therefore, a treatment program designed solely to elevate the melting point of the deposit will not solve the problem, and it is necessary to introduce additive components that change the physical characteristics of the deposit, making it more friable. Additives used for this purpose contain compounds of magnesium or aluminum. Aluminum is usually the most effective material for increasing friability of deposits. Figure(3): Treatment can make deposits friable for easy removal. Also removing salts in crude oil before its exposed to distillation process can paly a role in decreasing the ash contents in crude oil and its products. Since the ash forming materials derived from metallic salts and organometallic compounds, reducing the salt in crude oil will decrease the ash content as well, for this purpose a de-salter unit is placed before the distillation tower wash the crude oil with sweet water to remove the metallic salts in it.
- 8. Page | 8 3. What is the relation between the sulfur content and ash content in reside crude oil? Why ? Table (1.1): Typical residual oil analyses. From the table Sulfur emission regulations have severely restricted the use of high sulfur oils. Generally, high sulfur oils (greater than 1.0% sulfur) have high ash contents. Because sulfur compound will make new compounds with other materials which will solidify at specific temperature in the boilers that result the high ash contents of RC that contain high ratio of sulfur. These oils are usually imported from the Caribbean area. Prior to 1972, most East Coast boilers were burning high sulfur, high ash oils. 4. Why light fractions of petroleum products have negligible ash content? Light fractions don’t contain metallic salt and organometallic compounds as well as the combustion temperature of light fractions is low compare with the temperature that form the ashes. 1.7 Conclusions 1. The principal elements contributing to high ash contents of petroleum residual stocks and the cokes obtained from these stocks are sodium, iron, and magnesium, the contents of which increase with increasing content of chlorides in the crude oil. 2. The contents of silicon, nickel, vanadium, and manganese in the residual stocks and in the cokes are essentially independent of the salt content of the crude oil. 3. Thorough desalting of crude oil is a basic prerequisite in the production of low- ash cokes. 4. In order to produce low-vanadium coke, the coker feedstock must be selected very carefully. Characteristic High Ash Medium Ash Low Ash Specific Gravity, at 60 °F 0.9548 0.9944 0.9285 Viscosity SSF at 122 °F, sec 240 200 100.5 Calorific Value, Btu/gal 147,690 152,220 147,894 Bottom Sediment & Water, % 0.1 0.4 0.1 Sulfur, % 1.93 2.26 0.62 Ash, % 0.06 0.04 0.02 Vanadium, ppm 363 70 6 Sodium, ppm 16 50 9 Nickel, ppm 48 19 14 Aluminum, ppm 9 1 10 Iron, ppm 12 3 1