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Abstract: Shell 1240E002 is circulating water, and the pipe (medium side) is industrial hydrogen / condensate. The heat exchanger has not been in operation from 2015 to 2021; from March to August 2022, there were three consecutive leaks, which brought great risks and unnecessary economic losses to the stable production of the device. This paper mainly analyzes the reasons for frequent leakage during operation, and studies the corrosion mechanism and formation reasons of circulating water, In view of the problems such as more calcium and magnesium plasma and suspended matter in circulating water, substandard water velocity, and flow dead zone caused by structural defects of tube bundles, feasible countermeasures were proposed, and verified by theoretical analysis and practical application. For example, reducing scaling can increase the backwash process, increase the samarium cobalt fluid processor, increase the water flow rate, optimize the baffle distribution to reduce the flow dead zone, regular sewage, improve the water quality to reduce the amount of suspended solids and mud; For example, to slow down the corrosion of the outer wall coating of the tube bundle (such as the internal anticorrosive process of the tube bundle for circulating water), reduce the content of chloride ions and dissolved oxygen in the circulating water, inhibit the production of microorganisms, strictly control the temperature of the inlet and outlet of circulating water, and adopt sacrificative anode protection technology to protect the tube bundle, etc., and finally reduce the occurrence of scale corrosion, so as to avoid leakage. Ensure the safe and stable operation of the device.Abstract: Shell 1240E002 is circulating water, and the pipe (medium side) is industrial hydrogen / condensate. The heat exchanger has not been in operation from 2015 to 2021; from March to August 2022, there were three consecutive leaks, which brought great risks and unnecessary economic losses to the stable production of the device. This paper mainly analyz...Learn More
Abstract: With the continuous increase of the global population and the continuous development of the social economy, the annual global demand for oil resources has increased significantly. According to the survey results, heavy oil resources are very rich, accounting for about 70% of the world's total oil reserves, much larger than traditional crude oil, so the exploitation of heavy oil is particularly important. Due to the limited supply of conventional oil and soaring oil demand, China's oil security will face unprecedented challenges. Aquathermolysis process is one of the key and economical viscosity reduction technologies for successful recovery of heavy oil in the world. This paper briefly introduces the overview of heavy oil resources in China, the technical means of heavy oil exploitation and the development of heavy oil aquathermolysis technology, and introduces in detail the classification of aquathermolysis catalysts and the research on viscosity reduction mechanism of aquathermolysis. The most suitable catalysts contain strong active sites, which can break the heteroatomic bonds of resin and asphaltene in heavy oil and promote the increase of saturated hydrocarbon and aromatic hydrocarbon content. Finally, the problems and future development trends of heavy oil aquathermolysis technology are analyzed.Abstract: With the continuous increase of the global population and the continuous development of the social economy, the annual global demand for oil resources has increased significantly. According to the survey results, heavy oil resources are very rich, accounting for about 70% of the world's total oil reserves, much larger than traditional crude oil, so...Learn More
Abstract: Objective: In order to solve the problem that there is no conclusive report of the dissociation constant of tofacitinib citrate, the dissociation constant of tofacitinib citrate was determined for the first time by using the model algorithm of different dissociation constants of ultraviolet spectroscopy. It provides an important reference for the analysis and design of the drug form. Methods: The characteristic absorption wavelengths of tofacitinib citrate were obtained by scanning the pH gradient solutions of different tofacitinib citrate by ultraviolet spectroscopy, and the dissociation constant of tofacitinib citrate was calculated according to the logarithmic value of the absorbance ratio of the molecular tofacitinib citrate and the ionized tofacitinib citrate and the data of pH calculation. At the same time, the ionization hop in the acidic environment is derived according to the relationship between the absorbance ratio and pH of the selected different reference wavelengths and the main characteristic absorption wavelength, and the pH value of the ionic and molecular states is the dissociation constant. Results: The dissociation constant of tofacitinib citrate under acidic conditions was 6.0. In addition, the pKa of the substance was calculated according to the structural formula of tofacitinib citrate using commercial dissolution constant estimation software, which was close to the experimental results. The accuracy of the results is corroborated. Buffer test samples corresponding to pH were prepared, and the results were well analyzed. Conclusion: The method of determining the dissociation constant of weak acid and weak base salt - tofacitinib citrate by ultraviolet spectroscopy is simple and fast, and the determination results are reliable.Abstract: Objective: In order to solve the problem that there is no conclusive report of the dissociation constant of tofacitinib citrate, the dissociation constant of tofacitinib citrate was determined for the first time by using the model algorithm of different dissociation constants of ultraviolet spectroscopy. It provides an important reference for the a...Learn More
Abstract: Objective: To establish a method for the determination of Cucurbitin B in drug-loaded PCL-g-PEI polymer micelles. Methods: Cucurbitin B loaded micelles were prepared by solvent volatilization. HPLC method was used to determine the content of Cucurbitin B in PCL-g-PEI micelles. The separation was performed on Agilent C18 column (150 mm×4.6 mm, 5 μm) with mobile phase consisted of acetonitrile/water/glacial acetic acid=45: 55: 0.1 (V/V/V) at the flow rate of 1.0 mL/min. The detection wavelength was set at 228 nm, and the column temperature was 25°C. Sample volume was 20 μL. Result: The good linearity with Cucurbitin B concentration range was achieved in the rang of 1×10-6~0.1 mg/mL (r=0.9999). Blank PCI-g-PEI micelle carrier had no interference. The precision, stability, repeatability and recovery of the method meet the requirements. Solvent volatilization method was employed to prepare Cucurbitin B drug-loaded micelle, which has the highest drug loading capacity among them. Conclusion: The method for the determination of Cucurbitin B established in this paper has strong specificity, good precision and reproducibility, and the recovery rate meets the requirements. The content of Cucurbitin B in drug-loaded polymer micelles can be quantitatively determined, which provides reference for the content determination of Cucurbitin B related preparations of Traditional Chinese medicine.Abstract: Objective: To establish a method for the determination of Cucurbitin B in drug-loaded PCL-g-PEI polymer micelles. Methods: Cucurbitin B loaded micelles were prepared by solvent volatilization. HPLC method was used to determine the content of Cucurbitin B in PCL-g-PEI micelles. The separation was performed on Agilent C18 column (150 mm×4.6 mm, 5 μm)...Learn More
