Evaluation methods for crude oil calcium removal agents

The calcium content before and after crude oil descaling is analyzed to calculate the descaling rate; generally, a descaling rate of 60% is considered good. Of course, it is also possible to analyze the removal rates of other metals such as iron.

Thanks for the reply from above! I know that the decalcification rate needs to be measured, but I’m not sure about the specific methods involved. For example, what method is used to determine the calcium content in crude oil? Could you offer some help? Thank you!

Crude oil decalcification technology involves adding appropriate decalcifiers and demulsifiers to the electrodialysis system during the electrodialysis process; the metal ions removed are discharged along with the water produced by electrodialysis in the form of inorganic salts. The evaluation process is similar to that used for evaluating demulsifiers.

　It is sufficient to analyze the calcium content before and after crude oil desulfurization. Metal impurities such as Fe or Ca in crude oil can be detected using ICP emission spectroscopy. ICP emission spectrometry has a wide range of applications and is now commonly used for sample analysis in areas such as water quality, the environment, metallurgy, geology, chemical formulations, petrochemicals, food, and laboratory services. By the early 1980s, as many as 78 elements had been determined using ICP emission spectroscopy. Today, aside from inert gases which cannot be detected, as well as those poorly detectable non-metal elements in the upper right part of the periodic table such as C, N, O, F, Cl, and the alkali metals H, Rb, and Cs for which the detection results are not satisfactory, it is capable of analyzing the vast majority of elements in the periodic table.

4.5 Determination of decalcification rate 4.5.1 Reagents and materials Distilled water； Desulfurized purified water ； Crude oil ； 1% HFY-105 demulsifier. 4.5.2 Instrument: YS-2 Type Electrodesalination Tester ； 20L glass water bath ； Special shaking rack for emulsifier selection ； Atomic absorption spectrometer. 4.5.4 Test Procedures 4.5.4.1 Sampling (1) Pour crude oil and distilled water into beakers respectively, and place them in a water bath at 70°C for 30 minutes to maintain a constant temperature. (2) Using a pipette, 4 mL of distilled water or desulfurized purified water at a constant temperature was added to each of the four evaluation flasks. (3) Pour the crude oil, which has been kept at a temperature of 70°C, into the four evaluation flasks until the 70 mL mark is reached. (4) Using a pipette, transfer solutions of the decalcifier at various concentrations into bottles #2, #3, and #4 for evaluation. (5) Amount of demulsifier added: 0, 25 μg/g. 4.5.4.2 Stirring: Seal the mouths of the four test bottles with silicone stoppers and mount them on a special shaking rack designed for demulsifier testing; shake them up and down forcefully the specified number of times to ensure thorough mixing of the liquid inside the bottles. 4.5.4.3 Demulsification and dehydration: (1) Place the four test flasks in the aluminum bath of the YS-2 type electrodesalination tester, close the lid of the aluminum bath tightly, and connect the power supply. (2) Turn on the device; after waiting for 30 seconds, the tester begins to heat up to the set temperature and maintains that temperature for 10 minutes. (3) The instrument begins demulsification and dehydration. The voltage is controlled at 500V for low voltage and 1300V for high voltage ； The test time is set at 5 minutes at low pressure and 30 minutes at high pressure. (4) After the testing instrument is shut down, use cooling water to cool the aluminum bath to 50°C. (5) Remove the evaluation flasks and let them stand for 5 minutes; meanwhile, take about 10 mL of the crude oil from the upper layer of each of the four evaluation flasks and pour it into four beakers respectively. 4.5.4.4 Detection of calcium content in crude oil: The crude oil in the four beakers was analyzed using an atomic absorption spectrometer to determine its calcium content. 4.5.5 Expression of the evaluation results – Decalcification rate (%) = ————— ×100 ⑵ Where: — is the calcium content in the crude oil from the control test without any decalcifying agent, in μg/g ； 0 — Calcium content in the crude oil from the blank test without descaling agent, μg/g.

An important indicator for the decalcification rate is the calcium-to-agent ratio; if this ratio is 1:1, the decalcification rate can reach 60%, which is a very good result

Generally, desalination is sufficient to remove calcium. . . :lol

Thank you all for your enthusiastic responses; in particular, I’m very grateful to the person on floor 6 for providing specific instructions! :handshake

Comparisons were made regarding the calcium content in crude oil before desalination, after the first desalination step, and after the second desalination step. Similar to desalting agents, the best descaling agents can achieve a descaling rate of up to 80%. Those used by the China Institute of Petroleum Science have shown good results, though they are quite corrosive

Sinopec requires that the corrosion rate not exceed 1 mm/a. I uploaded the technical requirements for decalcifiers from Sinopec in the shared materials upload section. The above explanation is quite detailed. This post was last edited by wujunjin on 2009-2-26 10:12.]