29 results about "Triethylaluminium" patented technology

The invention provides a high-pressure wear-resistant valve rubber. The valve rubber is prepared from the following raw materials in parts by weight: 100 parts of a polyurethane prepolymer, 20 to 30 parts of a chain extender, 12 to 18 parts of a polycaprolactone coated boron nitride / molybdenum disulfide composite material and 0.5 to 2 parts of an antioxidant. Wherein the polycaprolactone coated boron nitride / molybdenum disulfide composite material is obtained by polymerizing an amino silane coupling agent modified boron nitride / molybdenum disulfide composite material, triethyl aluminum and epsilon-caprolactone in an organic solvent at 35-45 DEG C in an inert atmosphere. A polycaprolactone-coated boron nitride / molybdenum disulfide composite material is used as a filler, and boron nitride / molybdenum disulfide as an inner core forms a synergistic structure of a reinforced substrate and a lubricating surface layer, so that high-pressure load bearing and friction coefficient reduction are facilitated; and the polycaprolactone flexible shell layer is compatible with the matrix, so that the filler is uniformly dispersed in the matrix.

The utility model belongs to the technical field of white oil recovery, and particularly relates to a triethyl aluminum-containing waste white oil recovery device, which comprises a triethyl aluminum-containing waste white oil storage tank, a delivery pump, a reaction tower, a liquid nitrogen storage tank, a deethanization adsorption tower, a filter and a rectifying tower, the delivery pump is connected with the reaction tower through a pipeline, the liquid nitrogen storage tank is connected with the top end of the reaction tower through a pipeline, the bottom end of the reaction tower is connected with the filter through a pipeline, the filter is connected with the rectifying tower through a pipeline, and the deethanization adsorption tower is connected with the upper part of the reaction tower through a pipeline; an ethane recovery pipeline and a nitrogen recovery pipeline are arranged on the side wall of the deethanization adsorption tower, and a white oil recovery pipeline is arranged on the side wall of the rectifying tower. The recovery device can safely and efficiently recover white oil.

The utility model provides an inflammable liquid combustion test system and a triethyl aluminum combustion test system. The inflammable liquid combustion test system comprises a first inert gas storage tank, a three-way pipeline and a second inert gas storage tank, the first inert gas storage tank is communicated with the inflammable liquid storage tank through a pressurizing pipeline, and a control valve is arranged on the pressurizing pipeline; a first branch of the three-way pipeline is communicated with the flammable liquid storage tank, a second branch of the three-way pipeline is communicated with the combustion disc, and flammable liquid in the flammable liquid storage tank is guided into the combustion disc through the first branch and the second branch; the second inert gas storage tank is connected with a third branch of the three-way pipeline; each branch of the three-way pipeline is provided with a valve assembly. According to the utility model, residual flammable liquid in the pipeline can be guided into the combustion disc by using inert gas pressure, so that test equipment is prevented from being damaged by combustion of the residual liquid in the pipeline, and the safety risk of a combustion test is greatly reduced.

The invention relates to the field of chemical synthesis, and discloses a method for constructing a full-alkyl quaternary carbon stereocenter through stereospecific conversion of chiral tertiary alcohol. The method successfully solves the industrial problem that the peralkyl quaternary carbon center is difficult to construct with high stereoselectivity due to huge steric hindrance and lack of electron difference, the process shows excellent stereospecificity and chemical selectivity, the ee value of the product is as high as 98%, the dr value is superior to 20: 1, and meanwhile, the excellent yield of 90% or above is kept; besides, according to the scheme, the substrate is wide in universality and can be compatible with various chemical small molecule substrates of different structures, the used reagents such as triethyl aluminum and KHMDS are cheap and easy to obtain, operation is easy and convenient, and a simple and efficient stereospecific conversion strategy with industrial application potential is provided for synthesis of complex drug intermediates.

The application discloses a preparation method of high-purity triethyl indium and relates to the technical field of metal organic source synthesis. Nowadays, high-purity indium source is a key raw material for MOCVD technology. Currently, the commonly used indium source is trimethyl indium. However, trimethyl indium is solid at room temperature, which easily causes problems such as excessive solid indium source residue, low solid molecule overflow rate, and hardening and channeling. Therefore, the solid indium source is worse than liquid source in vapor saturation and source content stability. In the application, the halide of indium and triethyl aluminum are reacted to generate triethyl indium under the protection of inert gas. The crude triethyl indium is purified by reduced pressure distillation. The finished triethyl indium is obtained by further purification. The whole process is simple in operation. In addition, the purity of the product is improved under the protection of inert gas, so that the preparation of triethyl indium is not affected by other solvents.

The invention relates to the technical field of olefin polymerization, discloses a method for improving gas-phase copolymerization activity of propylene and alpha-olefin and a polymer, and aims to solve the problems of low polymerization activity and non-uniform rubber phase distribution caused by residual inhibitory activity center of an external electron donor in a copolymerization stage of a conventional Ziegler-Natta catalyst. The preparation method comprises the following steps: pre-complexing, pre-polymerizing, carrying out two-stage polymerization and post-treating, firstly, pre-complexing and pre-polymerizing a titanium Z-N catalyst, triethyl aluminum and cyclohexylmethyldimethoxysilane, and then carrying out first-stage propylene homopolymerization to obtain a high-isotacticity intermediate; after transition treatment, a mixture of a compound activity accelerant and triethyl aluminum is added into the second-stage gas-phase reactor, gas-phase copolymerization is performed under certain conditions, the compound activity accelerant and alkyl aluminum synergistically peel off an external electron donor and release an inhibited active center, so that the activity in the copolymerization stage is improved by 50% or above, and the method is adaptive to an existing industrial device and has a wide application prospect. The method is suitable for the fields of high-end automobile parts, household appliance shells and the like.

The invention belongs to the technical field of high polymer material preparation, and particularly relates to a high-performance ethylene copolymer and a continuous preparation method and application thereof.The continuous preparation method comprises the following steps that a main catalyst and a co-catalyst are mixed and then subjected to pre-activation treatment, the main catalyst is a titanium-series Ziegler-Natta catalyst, and the co-catalyst is a titanium-series Ziegler-Natta catalyst; the cocatalyst is ethyl sesquialuminum chloride or triethyl aluminum; mixing the pre-activated main catalyst, the pre-activated cocatalyst, the ethylene monomer and the solvent in proportion, and then carrying out two-step polymerization reaction; carrying out flash evaporation on the glue solution after the polymerization reaction to remove volatile components; adsorbing and removing the residual catalyst from the glue solution from which the volatile components are removed by adopting modified aluminum oxide or a molecular sieve adsorbent; and mixing the glue solution without the catalyst with a composite antioxidant, and extruding and granulating to obtain the product. The technical problems that an ethylene copolymer prepared in the prior art is insufficient in mechanical property, poor in optical property, poor in oxidation resistance, wide in molecular weight distribution and the like can be effectively solved.

Provided are a preparation method and system for an alane and a use of the alane. The method comprises: preparation of triethylaluminum: using triethylaluminum as a seed and aluminum and hydrogen as raw materials to synthesize triethylaluminum by means of a direct synthesis method, wherein the newly synthesized triethylaluminum comprises triethylaluminum in an amount equal to the seed and triethylaluminum for alane synthesis; and preparation of alane: thermally decomposing the triethylaluminum for alane synthesis to obtain the alane, wherein the newly synthesized triethylaluminum in an amount equal to the seed is used as a new seed for new preparation of triethylaluminum. The present invention only consumes aluminum and hydrogen required for generating the alane during the preparation of alane, and other raw materials can achieve a balance between consumption and output during the production process, achieving recycling, low production costs, high safety performance, and low emissions.

The invention relates to an ion cluster catalyst, and belongs to the technical field of high polymer materials. The ion cluster catalyst is used for ethylene homopolymerization, and is formed by a connection reaction of a phosphine phenol nickel catalyst Ni 3 and a phenol ligand structure under the condition of a cocatalyst triisobutyl aluminum, trimethylaluminum or triethyl aluminum, the prepared ion cluster catalyst has excellent ethylene polymerization activity.

The present application relates to the field of olefin catalytic polymerization, and aims to provide a catalytic system for preparing ultra-pure isotactic polypropylene and application thereof.The catalytic system comprises three components of a main catalyst, a cocatalyst and an external electron donor; wherein the main catalyst is a TiCl4 / MgCl2.ID supported high-efficiency spherical Ziegler-Natta catalyst, ID refers to diisobutyl phthalate or 2,2-diisobutyl-1,3-dimethoxypropane as an internal electron donor; the cocatalyst is a mixture of triethyl aluminum and triisobutyl aluminum; and the external electron donor is diisopropyl dimethoxysilane; or the cocatalyst is triethyl aluminum; and the external electron donor is a mixture of cyclohexyl methyl dimethoxysilane and dicyclopentyl dimethoxysilane.The catalytic system provided by the present application is simple to operate, does not need to synthesize complex-structure alkyl aluminum or siloxane, has controllable cost, and is easy to industrialize; and the product meets the requirements of low ash content, high polymerization activity and high isotacticity at the same time.

This invention discloses a continuous purification method and system for triethylaluminum based on membrane separation and complexation. The method first uses a sterically hindered amine complexing agent to selectively pre-complex chloride-containing impurities in crude triethylaluminum. Then, it sequentially passes the crude triethylaluminum through an inorganic ceramic nanofiltration membrane to retain large molecular complexes, followed by the removal of small molecular volatile impurities using an organic pervaporation membrane. Finally, it undergoes deep purification via a composite adsorption tower. The entire process is carried out under mild conditions, is safe and efficient, and is easily operable continuously and automatically. It significantly reduces the content of chloride ions and colored impurities in the product, yielding high-purity triethylaluminum, making it particularly suitable for high-end polyolefin catalysis.

The rectification equipment comprises a tower body, the bottom of the tower body is connected with a base, the lower left side of the tower body is connected with a steam inlet pipe, the middle of the left side of the tower body is connected with a feeding port, the top of the tower body is connected with a gas outlet pipe, and filler is arranged in the middle of the interior of the tower body. A lower grid plate is arranged at the bottom of the filler, the middle of the filler is separated by two middle grid plates which are distributed up and down, a gap exists between the two middle grid plates, the top of the gas outlet pipe is connected with a lower connecting flange, and a filtering chamber is mounted at the top of the lower connecting flange. According to the utility model, the two nuts, the fastening bolt, the upper connecting flange, the filter chamber, the filter screen and the lower connecting flange are arranged and are matched with each other, so that gas passing through the gas outlet pipe can be filtered to remove impurities, and the purity of prepared triethyl aluminum is improved.

The utility model provides a kind of effectively improve reaction kettle device of triethylaluminium production efficiency, it solves the problems, such as aluminium powder reaction rate reduction and stirring system abrasion, it includes reaction kettle main part, reaction kettle main part inside rotation is installed with the stirring shaft extending along axial direction, fixed sleeve is installed between the stirring shaft lower end and reaction kettle main part, stirring disc connected with stirring shaft is rotationally installed at the bottom of reaction kettle main part, stirring blade is installed on stirring disc and adjusting assembly is arranged between stirring blade and stirring disc, high-pressure circulating pump is connected to the bottom and top of reaction kettle main part by circulation pipe.The utility model has the advantages of good reaction effect, stable structure and the like.

The present invention is in the field of coated organic particles, in particular comprising small molecules, by using atomic layer deposition. It relates to a process for preparing coated organic particles comprising: (a) bringing organic particles containing a halogen-containing organic compound in motion to each other, wherein the halogen-containing organic compound consists of nonmetals, (b) sequentially contacting the organic particles with triethyl aluminum and a decomposition compound in the gaseous state.

The invention belongs to the technical field of lubricating materials, and discloses ultralow-temperature anti-wear lubricating grease special for a robot. The lubricating grease is composed of 85%-92% of base oil, 6%-10% of a composite thickening agent, 1%-3% of a microencapsulation repairing agent and 0.5%-2% of an auxiliary additive. Wherein the microcapsule has a stress response type fracture characteristic, dicyclopentadiene and triethyl aluminum are released during local damage, and a high-hardness repair film is generated through in-situ polymerization; the composite thickening agent ensures thixotropic stability in a wide temperature range, and a base oil blending system ensures low viscosity and elasticity at-70 DEG C. According to the invention, a basic oil-composite thickening agent-stress response microcapsule three-in-one bionic lubricating system is constructed, so that the problem of irreversible wear caused by film embrittlement of traditional lubricating grease at-70 DEG C is solved; invalid consumption of the repairing agent is avoided; and the structural stability of the repairing film in subsequent operation is ensured. The method is suitable for application scenes such as polar region scientific investigation robots, deep space exploration mechanical arms and ultralow-temperature cold chain transfer robots which have strict requirements on joint reliability.

The disclosure provides a catalyst composition for the oligomerization of ethylene to produce one or more linear alpha olefins, the catalyst composition including a chromium compound, a heteroatomic multidentate ligand having an NPNPN backbone, wherein each P is an optionally substituted phosphino group and each N is an optionally substituted amino group, a methylaluminoxane, and triethyl-aluminum.

The utility model relates to a catalyst feeding system for a polyolefin device reactor. The catalyst feeding system comprises a reactor; a triethyl aluminum conveying pipeline; the feeding connecting pipe is connected to the catalyst injection port, the ethylene back flushing pipeline is connected with the feeding connecting pipe, and the connecting position of the ethylene back flushing pipeline and the feeding connecting pipe is located on the upstream of the connecting position of the triethyl aluminum conveying pipeline and the feeding connecting pipe. Ethylene gas conveyed by the ethylene back-blowing pipeline brings triethyl aluminum conveyed into the feeding connecting pipe from the triethyl aluminum conveying pipeline into the reactor, the section, used for being connected with the feeding connecting pipe, of the ethylene back-blowing pipeline is marked as a first pipeline section, and the section, used for being connected with the ethylene back-blowing pipeline, of the feeding connecting pipe is marked as a second pipeline section. The included angle between the material conveying direction in the first pipeline section and the material conveying direction in the second pipeline section is an acute angle. The device has the advantages that dead zones in the pipeline can be effectively eliminated, the pressure feed effect of the triethyl aluminum is enhanced, and then the potential safety hazard problem caused by pipeline blockage is solved.

The application discloses a process method for preparing a nano-limited NaAlH4 hydrogen storage material capable of low-pressure circulation with low energy consumption, and comprises the following preparation steps: (1) pretreating selected two-dimensional carrier materials; (2) placing aluminum powder, sodium, triethylaluminum and an organic solvent into a high-pressure reaction kettle in an argon-filled glove box; (3) dispersing the pretreated two-dimensional carrier materials in the organic solvent, and sealing the reaction kettle; (4) placing the reaction kettle in an ultrasonic machine for ultrasonic mixing and dispersion; (5) vacuumizing the reaction kettle, filling hydrogen into the reaction kettle, heating the reaction kettle at a certain heating rate, and keeping for a period of time; (6) after the reaction is completed, cooling the reaction kettle to room temperature, and discharging the remaining hydrogen pressure; (7) placing the mixture under dynamic vacuum for solvent removal and drying, and obtaining the nano-limited NaAlH4. Through the above method, the pressure and temperature of the loading process are effectively reduced, and the synthesis of NaAlH4 and nano-loading are combined.

The utility model discloses a waste triethyl aluminum treatment device which comprises a bottom plate and a Unipol polypropylene tank, the upper surface of the bottom plate is fixedly provided with a plurality of annularly-arranged supporting columns, the upper surface of each supporting column is fixedly installed on the bottom face of the Unipol polypropylene tank, the right side face of the Unipol polypropylene tank is fixedly communicated with a first conveying pipe, and the right side face of the Unipol polypropylene tank is fixedly communicated with a second conveying pipe. A metering valve is fixedly installed on the outer surface of the first conveying pipe, and a first cushion block and a reactor are fixedly installed on the upper surface of the bottom plate. According to the device, through cooperation of the first conveying pipe, the first pump body and the second conveying pipe, triethyl aluminum in the Unipol polypropylene tank can be conveyed into the reactor, so that the triethyl aluminum can be prevented from being transferred, potential safety hazards and waste are avoided, the reactor can treat the triethyl aluminum, and the production efficiency is improved. And through cooperation of a third conveying pipe, a second pump body and a fourth conveying pipe, the treated triethyl aluminum can be conveyed into the Unipol polypropylene tank again.

Alkylaluminoxane compositions are produced by a process comprising the steps of reacting trimethylaluminum, triethyluminum, and water in a hydrocarbon solvent to form alkylaluminoxane, and then removing insoluble aluminum-containing species from the solvent to form an alkylaluminoxane composition containing from 0.1 wt% to 20 wt% aluminum. Typically, the molar ratio of trimethyl aluminum: triethyl aluminum is from 5: 95 to 80: 20, and the molar ratio of water: aluminum is from 0.2: 1 to 1: 1. The alkylaluminoxane compositions are useful as activators in transition metal-based catalyst systems and ethylene oligomerization processes.

The present disclosure provides an alane preparation method, a preparation system and an application thereof that includes: preparing triethylaluminum: taking triethylaluminum as seeds and aluminum and hydrogen as raw materials, synthesizing triethylaluminum via a direct synthesis method; the triethylaluminum that is newly synthesized contains triethylaluminum of an equal amount as the seeds and triethylaluminum configured to perform alane synthesis; preparing alane: performing thermal decomposition on triethylaluminum that is configured to perform alane synthesis, to obtain alane, wherein the newly synthesized triethylaluminum with an amount equivalent to that of the seeds are used as new seeds for the preparation of new triethylaluminum. The present disclosure only consumes aluminum and hydrogen that are necessary for preparing alane during the preparation process, other raw materials can achieve a balance between consumption and production during the production process.

The invention discloses a method for preparing trimethylaluminum through reaction of triethylaluminum and chloromethane, which comprises the following steps of: efficiently catalyzing the reaction of chloromethane and triethylaluminum through high-pressure liquid phase reaction by using cheap and easily available chloromethane as a methylation reagent and triethylaluminum as a raw material and using a composite catalyst consisting of halide of metal bismuth and halide of metal zinc; the reaction temperature is higher than 120 DEG C, and the yield of the trimethylaluminum is higher than 80% and is higher than that of the existing process for preparing the trimethylaluminum by an alkyl exchange method; meanwhile, cheap and easily available chloromethane is used as a methylation reagent instead of expensive bromomethane or iodomethane, and the yield is higher than that of an existing process using bromomethane, so that the process cost is greatly reduced, and the method is green and low-carbon. Meanwhile, the used catalyst can be recycled, and the method for preparing the trimethylaluminum is low in cost, green, rapid and good in industrialization prospect.

The present application belongs to the technical field of catalyst, and particularly relates to a method for hydrogenation reaction in production of triethylaluminum catalyzed by aluminum hydrogen structure activator. The present application provides a method for hydrogenation reaction in production of triethylaluminum catalyzed by aluminum hydrogen structure activator, which comprises adding triethylaluminum mother liquor and aluminum powder mixture mixed with aluminum hydrogen structure activator in advance into a reaction kettle, heating under stirring, passing in hydrogen and pressurizing, continuously keeping hydrogen passing in during the reaction to ensure that the reaction kettle is in a constant pressure state, and obtaining target product diethylaluminum hydride and hydrogenolysis byproduct ethane after the reaction is completed. The present application provides a hydrogenation reaction with introduction of aluminum hydrogen structure activator, effectively improves the hydrogenation reaction speed and production efficiency, simultaneously reduces by-reactions and production cost, the activator is convenient to add, does not additionally increase process burden, related by-products are easy to remove and do not affect the environment and production safety.

This invention relates to a low-energy-consumption, continuous, and intrinsically safe method and system for producing triethylaluminum. The system utilizes aluminum powder, hydrogen, and ethylene to produce triethylaluminum, comprising three parts: an aluminum powder preparation section, a hydrogenation reaction section, and an ethylation reaction section. This reaction system enables continuous hydrogenation of high-aluminum powder, continuous desolidification and separation of diethylaluminum hydride, and continuous ethylation of diethylaluminum hydride, achieving high conversion rates of aluminum powder and high selectivity for triethylaluminum. It is a low-energy-consumption, continuous production method with intrinsic safety characteristics.

The invention discloses a production method of a bio-based polypropylene fiber material. The method comprises the following steps: firstly, pretreating liquid bio-based propylene to remove impurities CO, H2O and COS; feeding the pretreated bio-based propylene, a main catalyst, an external electron donor and triethyl aluminum into a prepolymerization reactor, and carrying out prepolymerization reaction in the presence of hydrogen to obtain a bio-based polypropylene prepolymer; the bio-based polypropylene prepolymer, the pretreated bio-based propylene and hydrogen are introduced into a loop reactor for continuous polymerization reaction, and bio-based polypropylene is obtained; the preparation method comprises the following steps: sequentially carrying out flash evaporation, degassing, steaming and drying on bio-based polypropylene to obtain homopolymerized bio-based polypropylene powder; the preparation method comprises the following steps: mixing the homopolymerized bio-based polypropylene powder and a compound additive, initiating a free radical degradation reaction in an extruder, extruding, and sequentially cooling, drying and pelletizing the obtained material strip to obtain the homopolymerized bio-based polypropylene fiber material. By adopting the method for preparing the bio-based polypropylene fiber material, the C14 content of the bio-based polypropylene fiber material can be remarkably increased, and meanwhile, the mechanical property, the processing property and the production efficiency are improved.

The utility model relates to the technical field of triethyl aluminum, and discloses a triethyl aluminum recycling device which comprises a storage tank, a guide pipe set is fixedly installed on the lower portion of the storage tank, two pressure pumps are fixedly installed on the guide pipe set, a scale discharging pipe is fixedly installed on the guide pipe set, and the scale discharging pipe is fixedly connected with the storage tank. A plurality of first valves are fixedly mounted on the guide pipe group and the scale discharging pipe; a recycling mechanism is arranged on the scale discharging pipe; the scale storage tank is installed between the storage tank and the scale discharge pipe, and the scale storage pipe and the connecting pipe are connected in a through mode, so that when the storage tank and the guide pipe set are cleaned, dirt liquid can be transferred into the scale storage tank to be further processed, and the usable part can flow back into the storage tank through the connecting pipe to be reused; according to the triethyl aluminum cleaning device, cleaning liquid can be evenly sprayed on the inner walls of the storage tank and the scale storage tank, the flow direction of the cleaning liquid is adjusted through the control valve, and therefore the triethyl aluminum can be recycled through the triethyl aluminum cleaning device, and meanwhile the triethyl aluminum cleaning device can be thoroughly cleaned.

The application is suitable for the technical field of metal source organic synthesis, and provides a trimethylaluminum purification device and process, which comprises a reaction device, a reflux device and a vacuum rectification device, the vacuum rectification device is connected with a shunt device through a pipeline connecting piece, the shunt device comprises a rotating cylinder, a rotating assembly is connected to the side wall of the rotating cylinder, a main flow pipe is installed in the rotating cylinder, one end of the main flow pipe is connected with the vacuum rectification device through a diversion pipe, and the other end of the main flow pipe is positioned and butt-jointed with a shunt assembly through a positioning assembly; by adding high-purity triethylaluminum into trimethylaluminum crude product containing dimethylaluminum chloride, pure trimethylaluminum can be obtained through rectification after reaction, and the purification of trimethylaluminum crude product is realized; in the process of rectifying the trimethylaluminum after reaction, the liquid obtained in the process of rising temperature and the liquid under the temperature stable state can be separated through the shunt device, and the purity of the trimethylaluminum can be further ensured.

The invention discloses a triethyl aluminum kettle residue treatment method, which comprises: 1) distilling a triethyl aluminum kettle residue solution to obtain a tri-n-butylaluminium crude product; and 2) oxidizing the tri-n-butylaluminium crude product in an oxygen-containing atmosphere to obtain aluminum oxide. According to the method, the triethylaluminium kettle residue solution is continuously distilled, the tri-n-butylaluminium in the kettle residue solution is extracted, and the tri-n-butylaluminium crude product is oxidized in the atmosphere containing a proper amount of oxygen, so that the high-purity nanoscale aluminum oxide powder is obtained, and part of the kettle residue is converted into a new product with a relatively high additional value. The waste liquid is retreated, the treatment method is simple, and the environmental pollution can be reduced while the production cost is saved.

The present application relates to metering pump cleaning technical field, especially for a kind of nitrogen white oil flush diaphragm device, including flush pipeline, flush pipeline is further subdivided into first pipeline, second pipeline, third pipeline and fourth pipeline, flush system is formed by specific connecting relationship between each pipeline, specifically, one end of second pipeline is connected with gas injection device, the other end is connected with fourth pipeline, fourth pipeline is used to inject flush medium into the inside of metering pump, in the present application, diaphragm in metering pump is flushed by nitrogen and white oil in turn, wherein, nitrogen provides strong driving force, and white oil is used as medium to clean tiny gap, both work together, realize high-efficiency, thorough flushing effect, effectively remove the corrosive substance such as triethylaluminum remaining in pump, ensure the safety of overhaul process, improve the service life of metering pump, ensure the long-term stable operation of pump body.