[Q&A Question 271] 2017.09.29

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【Q&A Question 271】September 29, 2017: Some tanks used for storing lightly contaminated oil are equipped with a nitrogen pressurization system for filling them; please briefly outline the precautions to be taken. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) The answers to the daily questions change, and today’s answers are shown in subsequent questions. For management purposes, if you need to view content from a few days ago, please access it through the summary post below. 2017 Q&A Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html (Source: Haichuan Chemical Industry Forum) [Q&A Question 261] September 19, 2017: Briefly describe the definition of the downward displacement of the piston rod in a reciprocating compressor. Reciprocating compressors typically have guide rings installed on the piston to reduce wear on the piston rings; when these guide rings wear out, it can cause the piston to sink. By measuring the downward displacement of the piston rod, it is possible to detect early signs of wear on the guide ring, and this helps to prevent direct contact between the piston and the cylinder, which could otherwise cause damage to the cylinder liner. [Q&A Question 262] September 20, 2017: What is the significance of regularly monitoring the acidity levels of water in hydrogenation units for air cooling? In daily operations, it is necessary to check the pH value, iron ions, and chloride ions in such water; adjustments are made to the amount of additives used, and samples are taken regularly to ensure that these parameters remain within acceptable limits, thereby preventing corrosion of the pipelines due to excessive acidity. 【Q&A Question 263】 September 21, 2017: Briefly describe the role of additives in hydrogenation catalysts To improve certain aspects of the catalyst’s performance, such as activity, selectivity, stability, etc. 【Q&A Question 264】 September 22, 2017: Briefly describe the possible reasons for an increase in pressure difference in the reaction system of a hydrogenation unit "Answer: (1) Furnace tube coking ； (2) Poor filtration efficiency; impurities clog the catalyst bed, resulting in an increase in reactor pressure drop ； (3) Ammonium salts clog high-pressure heat exchangers and air coolers ； (4) Changes in the volume and composition of recycled hydrogen ； (5) The feed rate is too high ； (6) The feed oil has poor quality, with high levels of impurities such as Fe, Ca, Ni, V, Cl, and residue. " 【Q&A Question 265】 September 23, 2017: As the hydrogen partial pressure decreases, how does the cetane number change in terms of the impact of hydrogen partial pressure on the quality of diesel fuel? Gradual reduction 【Q&A Question 266】 September 24, 2017. Briefly describe the hazards of bypassing the raw material backwash filter in the hydrogenation unit "The feed oil filter is short-circuited, preventing impurities in the feed from being removed in a timely manner; as a result: 1. When the feed filter is short-circuited, the feed will clog the high-pressure heat exchanger, causing blockages and reducing the heat exchange efficiency ； 2. Once impurities enter the reactor bed, they will deposit within the bed, resulting in an increase in the pressure drop across the reactor bed. " 【Q&A Question 267】 September 25, 2017: Briefly explain what is the concept of \"three no-fires\". "1. Do not carry out any welding or heating work without an approved and valid permit ； 2. Work shall not commence without proper fire safety measures in place ； 3. Do not start any fire work without a fire watcher, or if the fire watcher is not present. " 【Q&A Question 268】 September 26, 2017: What are the possible reasons for a decrease in the water injection flow rate in hydrogenation units? "1. Pressure in the water injection tank decreases ； 2. Clogged pump inlet filter, pump malfunction, etc ； 3. Fault in the flow meter (flow control valve) on the pump outlet main pipe ； 4. System pressure increases ； 5. Air cooling blockage. " 【Q&A Question 269】 September 27, 2017: Briefly explain the significance of controlling the outlet temperature of high-pressure air cooling 1. The lower the air-cooled outlet temperature, the smaller the linear velocity of the gas within the high-pressure section, and thus it is less likely for liquid to be carried along ； The opposite is true for high outlet temperatures. 2. The solubility of hydrogen increases as the temperature rises; excessively high temperatures result in more hydrogen dissolving in the oil, leading to losses. 3. The excessively high temperature at the air-cooled outlet leads to an increase in linear velocity and an increase in the amount of liquid carried, which is not conducive to the safe operation of the recycle hydrogen compressor. The purpose of controlling the outlet temperature of the high-pressure air cooler to ≤50°C is to prevent excessive linear velocity of the high-velocity gas from entraining liquid and disrupting the circulation. In plants designed for cyclic hydrogen desulfurization, the excessively high outlet temperature of the high-pressure air cooler causes hydrocarbons to be present in the cyclic hydrogen, leading to foaming of the amine solution and a reduced desulfurization efficiency. In severe cases, liquid is carried along with the cyclic hydrogen, which affects the safe operation of the cyclic hydrogen compressor. 【Q&A Question 270】 September 28, 2017: What are the hazards of low oil level in the oil filler of the new hydrogen engine? Sealing in the absence of lubrication reduces its service life; it can also lead to abnormal oil supply at various injection points, thereby causing wear. A low oil level may result in poor oil supply to these injection points, leading to wear in the new hydrogen machine