Outstanding features of chemical centrifugal pumps
Centrifugal pump is a kind of pump commonly used in our industrial production. Chemical centrifugal pump is one of them. It uses the impeller to make the liquid flowing through the impeller act by centrifugal force, improve the mechanical energy of the liquid, and thus carry out liquid transportation. It is an increase. Machine for liquid energy. Due to the special requirements of the chemical production pump, the chemical centrifugal pump has the following outstanding features compared with other centrifugal pumps:
(1) It can adapt to chemical process needs in the chemical production, not only to transport liquid materials and provide the necessary pressure for process requirements, but also to ensure the amount of material to be transported. In certain chemical unit operations, the pump flow and head are required. Stable, keep the pump running efficiently and reliably.
(2) Corrosion resistance The medium transported by the chemical pump, including raw materials and reaction intermediates, is often a corrosive medium. This requires proper and reasonable material selection of the pump to ensure safe, stable and long-life operation of the pump.
(3) High-temperature medium transported by high-temperature, low-temperature chemical centrifugal pump, which has process liquid materials, and also contains heat-transfer liquids required and generated by the reaction process. For example: condensate pump, boiler feed pump, heat transfer oil pump. There are many types of cryogenic media delivered by chemical pumps , such as liquid oxygen, liquid nitrogen, methane, etc. The low temperature operating temperature of the pump is mostly at 20~10 °C. Regardless of the chemical pump that delivers high or low temperature, the material selection and structure must be appropriate, and there must be sufficient strength. The parts of the designed and manufactured pump can be affected by thermal shock resistance, thermal expansion, cold deformation, cold brittleness and the like.
(4) Wear resistance and scouring resistance. Because the logistics conveyed by the chemical centrifugal pump contains suspended solid particles, and the impeller and cavity of the pump also work at high pressure and high flow rate, the surface protective layer of the pump parts is destroyed. The service life is short, so it is necessary to improve the wear resistance and erosion resistance of the chemical pump. This requires that the material of the pump be made of wear-resistant manganese steel, ceramics, cast iron, etc., and the scouring titanium and manganese steel are selected.
(5) Operational reliability The reliable operation of the chemical pump includes two meanings: one is that the long-cycle operation does not fail; the other is that the various parameters are stable during operation. The reliability of operation is critical to chemical production. If the pump fails frequently, it will not only cause frequent production stoppages, but also affect production and economic benefits, and sometimes it may cause accidents in the chemical system. The fluctuation of the speed of the chemical pump will cause the fluctuation of the flow rate and the pressure of the pump outlet, so that the chemical production can not be carried out normally or the reaction in the system is affected, the material can not be balanced, which not only causes waste, but also causes the product quality to drop or the product to be scrapped.
(6) Non-leakage or less leakage The medium delivered by chemical pump is mostly flammable, explosive, toxic and harmful liquid. Once it leaks, it will seriously pollute the environment, endangering personal safety and physical and mental health of employees, and is even less suitable for leak-free factories and To clean the requirements of civilized factories, it is necessary to ensure that the chemical pump does not leak during operation, adopt new technology and new materials on the seal of the pump, operate according to the regulations, and maintain high quality.
(7) A liquid capable of transporting a critical state liquid in a critical state tends to vaporize when the temperature rises or the pressure decreases. Chemical pumps sometimes transport critical liquids. Once the liquid is vaporized in the pump, it is prone to cavitation damage, which requires the pump to have high cavitation resistance. At the same time, the vaporization of the liquid may cause frictional bonding of the static and dynamic parts of the pump, which requires the gap to be larger. In order to prevent mechanical seals, packing seals, labyrinth seals, and the like from being destroyed by dry friction due to vaporization of the liquid, such chemical pumps must have a structure that sufficiently removes gas generated in the pump.
The pump for conveying critical state liquid can use materials with better self-lubricating properties such as polytetrafluoroethylene and graphite. For the shaft seal structure, in addition to the packing seal, a double-end mechanical seal or a labyrinth seal can be used. When the double-face mechanical seal is used, the cavity between the end faces is filled with the sealed liquid; when the labyrinth seal is used, the seal gas having a certain pressure can be introduced from the outside. When the sealing liquid or the sealing gas leaks into the pump, it should be possible to pump the medium, and it is harmless if it leaks into the atmosphere. For example, when liquid helium is transported in a critical state, methanol can be used as a sealing liquid in the cavity of the double-face mechanical seal; when liquid hydrocarbons that are easily vaporized are transported, nitrogen gas can be introduced into the labyrinth seal.
An organic compound formed by dehydration of amino acids, containing carboxyl and amino groups, and being amphoteric. Also known as "peptide".
Two, one of the amide. It consists of two or more amino acids joined by the amino group of one amino acid to the carboxyl group of the other. An amino acid cannot be called a peptide, nor can a peptide be synthesized, but must be a compound of two or more amino acids linked by a peptide bond. Compounds where two amino acids are linked by a peptide bond are called dipeptides; A compound with three amino acids linked by peptide bonds is called a tripeptide, and so on, a compound with thirty-four amino acids linked by peptide bonds is called a thirty-four peptide.
A peptide is a chain of polymers of amino acids
A peptide is a chain of polymers of amino acids
Three, is related to the biological body of a variety of cell functions of biological active substances. Hundreds of peptides have been found in living organisms, which are essential participants in the body's complex physiological activities. All cells can synthesize peptides and their functional activities are regulated by peptides. It involves hormones, nerves, cell growth and reproductive fields, and its importance lies in the regulation of various systems, organs and cells in the body. The physiological and pharmacological effects of enzymatic polypeptides are mainly to activate related enzymes in vivo, promote the permeability of intermediate metabolic membrane, or affect specific protein synthesis by controlling DNA transcription or translation, and eventually produce specific physiological effects or play their pharmacological effects. Peptide is better than amino acid, one is faster than amino acid absorption; Second, it is absorbed by the body in a complete form; Third, active absorption (amino acids are passive absorption); Fourth, low consumption, compared with amino acids, peptide absorption has the characteristics of low consumption or no energy consumption, peptide absorption through the duodenum, directly into the blood circulation, their own energy nutrition transported to various parts of the human body; Fifth, peptide absorption is less than amino acid, with the characteristics of unsaturated; Sixth, there are only 20 kinds of amino acids, with countable functions, while peptides take amino acids as substrates, which can be synthesized into hundreds of thousands of kinds.
It is mainly divided into medical polypeptide drugs, peptide antibiotics, vaccines, antimicrobial peptides for agricultural use, small peptides for feed, cosmetics for daily use, soybean polypeptides for food, corn polypeptides, yeast polypeptides and sea cucumber peptides.
From the functional point of view, can be divided into antihypertensive peptide, antioxidant peptide, cholesterol lowering peptide, opioid active peptide, high F value oligopeptide, food strong taste peptide and so on.
Active peptide, and nutrition, hormone, enzyme inhibition, regulation of immunity, antibacterial, antiviral, antioxidant has a very close relationship. Polypeptides are generally divided into: polypeptide drugs and polypeptide health products. Traditional peptide drugs are mainly peptide hormones. The development of peptide drugs has been developed into various fields of disease prevention and treatment, especially in the following fields. [2]
Antitumor polypeptide
Tumorigenesis is the result of many factors, but ultimately all involve the regulation of oncogene expression. In 2013, many tumor-related genes and regulatory factors have been discovered. Screening peptides specifically bound to these genes and regulatory factors has become a new hot spot in the search for anticancer drugs. For example, somatostatin has been used to treat endocrine tumors of the digestive system; American scholars found a hexapeptide can significantly inhibit adenocarcinoma in vivo; Swiss scientists have discovered an octapeptide that induces apoptosis in tumor cells. [2]
Antiviral polypeptide
By binding to specific receptors on host cells, viruses adsorb cells and rely on their own specific proteases for protein processing and nucleic acid replication. Therefore, peptides binding to host cell receptors or active sites such as viral proteases can be selected from the peptide library for antiviral therapy. In 2013, many small peptides with antiviral properties have been screened from peptide banks in Canada, Italy and other countries, and some small peptides have entered the stage of clinical trials. In June 2004, the Chinese Academy of Sciences institute of Microbiology came out of the news, which was undertaken by the Chinese Academy of Sciences known
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