Abstract: Provided is a waveform control and adaptive compensation method for pulsed gas shielded welding, which comprises the following steps: step 1: acquiring an actual welding pulse waveform at an initial welding stage; step 2: according to the actual welding pulse waveform, extracting initial parameter values of the pulse waveform and an actually output pulse peak voltage Us at the beginning of welding; step 3: judging whether the actually output pulse peak voltage Us is abnormal; and step 4: when the actually output pulse peak voltage Us is abnormal, forming new parameter values of the pulse waveform for pulse waveform compensation. According to the waveform control and adaptive compensation method for pulsed gas shielded welding, an influence of environment on globular transfer can be effectively reduced through pulse control and pulse waveform compensation, thus improving an anti-interference performance and ensuring a welding effect.

Abstract: Disclosed is a multi-functional digital pulse electric welding machine system, which comprises an LCD interactive platform, an MCU control module, a wire feeder and an inverter main circuit, the LCD interactive platform is connected to the MCU control module, and is a man-machine interactive operation platform, an input end of the inverter main circuit is connected to a commercial power input and an output end of the inverter main circuit outputs a direct current to provide for a welding torch of an electric welding machine, the MCU control module is connected to the inverter main circuit and the wire feeder, and the MCU control module controls the inverter main circuit and the wire feeder to work according to a working mode selected by the LCD interactive platform.

Abstract: A method for preparing a high viscosity index poly-?-olefin subjects ?-olefin to a polymerization reaction in the presence of a metallocene catalyst to obtain a poly-?-olefin. The polymerization reaction is carried out in the absence of a solvent, and the metallocene catalyst is formed of, or is formed by interaction between, a metallocene compound and an activator.

Abstract: A metallocene compound having a structure shown by formula (I). A functional group connected to a bridging atom of the metallocene compound is an amine-substituted group and/or a metallocene-substituted group and/or a substituted metallocene group. A metallocene catalyst containing the metallocene compound has high catalytic activity, and can synthesize metallocene polypropylene having high isotacticity.

Abstract: The present application relates to an olefin polymerization method and system in the field of olefin polymerization. The method combines a supported double catalyst with a series process, introduces a liquid material obtained after heat exchange and gas-liquid separation of a circulation gas flow into a separate first reactor to get into contact with the supported double catalyst for polymerization reaction, and then introduces the reaction material and the first polyolefin generated by reaction into a second reactor to continue polymerization reaction, thereby enabling particles to circulate between first reactor and second reactor, improving mixing effect of two polyolefins with obvious differences in properties, avoiding the occurrence of phase separation, and facilitating the production of polyolefins with excellent performance.

Abstract: A ligand based chromium catalyst and application in catalyzing ethylene oligomerization are disclosed. The chromium catalyst is formed by a chromium compound and an organic ligand containing P and/or N. The substituents on N and P of the ligand can be replaced, whereby selective ethylene trimerization and tetramerization can be realized so as to produce 1-hexene and 1-octene at the same time.

Abstract: The present invention relates to an n-heterocyclic carbene (NHC) type palladium catalyst and its preparation method as well as applications. Its preparation process is as below: select glyoxal as the raw material to synthesize glyoxaldiimine in the presence of Lewis acid or Bronsted acid, and then react with paraformaldehyde to get the NHC type ligand. Use palladium(II) to react with the compound containing carbon-nitrogen double bonds to get palladium(II) cyclic dimer; make the palladium cyclic dimer and the NHC type ligand coordinated to get the NHC type palladium catalyst. The palladium catalyst with a brand new structure according to the present invention, boasts high activity and multi-purpose.

Abstract: A ligand based chromium catalyst and application in catalyzing ethylene oligomerization are disclosed. The chromium catalyst is formed by a chromium compound and an organic ligand containing P and/or N. The substituents on N and P of the ligand can be replaced, whereby selective ethylene trimerization and tetramerization can be realized so as to produce 1-hexene and 1-octene at the same time.

Abstract: The present invention relates to an n-heterocyclic carbene (NHC) type palladium catalyst and its preparation method as well as applications. Its preparation process is as below: select glyoxal as the raw material to synthesize glyoxaldiimine in the presence of Lewis acid or Bronsted acid, and then react with paraformaldehyde to get the NHC type ligand. Use palladium(II) to react with the compound containing carbon-nitrogen double bonds to get palladium(II) cyclic dimer; make the palladium cyclic dimer and the NHC type ligand coordinated to get the NHC type palladium catalyst. The palladium catalyst with a brand new structure according to the present invention, boasts high activity and multi-purpose.

Abstract: The present invention discloses an intercepting device capable of maintaining interception without the need of ensuring the sealing performance and automatically adjusting a height for interception. This intercepting device overcomes the deficiencies that a prior art intercepting device will fail to work if failing to ensure the sealing performance and can block only fluid at a same height as the intercepting device.

Abstract: The present invention provides a main catalyst component for olefin polymerization, which is prepared by a process comprising the steps of: (i) reacting a magnesium compound in nascent state having a rational formula (RMgX)y(MgX2), in which R is an alkyl having from 3 to 12 carbon atoms, X is a halogen, and y is a value of from 0.

Abstract: The present invention relates to a catalyst for polymerization of ethylene, a process for preparing the same, and a method for controlling kinetic behavior of said catalyst in ethylene polymerization. Said catalyst contains a titanium-containing main catalyst component and a co-catalyst. The titanium-containing main catalyst component is prepared by reacting the following components: (1) a hydrocarbon solution of dialkylmagnesium compound of formula RMgR?.yEt3Al; (2) an alcohol compound of formula R1OH; (3) a silica support thermally activated at 200-800° C.; (4) an alkylaluminum compound of formula R2nAlCl3-n; (5) a linear halogenated alkane of formula R3X; and (6) a titanium compound of formula Ti(OR4)mCl4-m. The co-catalyst is an organoaluminum compound. Three different types of ethylene polymerization kinetic curves can be obtained by adjusting the temperature for thermally activating the silica support and the ratio of titanium to magnesium in the titanium-containing main catalyst component.

Abstract: The invention discloses a process for preparing a titanium-containing main catalyst component, comprising the steps of: (i) reacting a magnesium compound having a formula (MgRX)p(MgX2)q, where R is an alkyl having 3 to 12 carbon atoms, X is halogen, and q:p=0:1 to 1.

Abstract: The present invention provides a high-activity solid main catalyst component for ethylene polymerization, a process for preparing the same and a catalyst containing the same. The main catalyst component consists essentially of a magnesium compound, a titanium compound, an electron donor, an alkyl aluminum compound and fumed silica, and is prepared by a process comprising the step of: reacting powdered magnesium with an alkyl halide to form a magnesium compound in the nascent state; adding the magnesium compound in the nascent state together with a titanium compound and an alkyl aluminum compound into an electron donor to form a complex; adding and well dispersing a fumed silica thereto to form a homogeneous thick mixture; molding and drying the mixture to form main catalyst component particles with good particle morphology; and optionally, dispersing the main catalyst component particles into a hydrocarbon solvent or a mineral oil to form a slurry.

Abstract: The present invention discloses a polyethylene catalyst and a process for preparing the same, said catalyst being composed of a main component of catalyst and a cocatalyst, wherein the main component of catalyst is prepared by reacting: (1) a magnesium-alcohol complex, (2) an alkyl aluminum compound having a formula R3nAlCl3-n supported on silica, and (3) a titanium compound having a formula Ti(OR2)mCl4-m, and the cocatalyst is an organic aluminum compound. The catalyst of the present invention has advantages including high polymerization activity, less difference between the polymerization activities at low hydrogen level condition and at high hydrogen level condition, stable polymerization reaction, good particle morphology of catalyst, and less fine powder of polymer product.

Abstract: The present invention relates to a catalyst for polymerization of ethylene, a process for preparing the same, and a method for controlling kinetic behavior of said catalyst in ethylene polymerization. Said catalyst contains a titanium-containing main catalyst component and a co-catalyst. The titanium-containing main catalyst component is prepared by reacting the following components: (1) a hydrocarbon solution of dialkylmagnesium compound of formula RMgR?.yEt3Al; (2) an alcohol compound of formula R1OH; (3) a silica support thermally activated at 200-800° C.; (4) an alkylaluminum compound of formula R2nAlCl3-n; (5) a linear halogenated alkane of formula R3X; and (6) a titanium compound of formula Ti(OR4)mCl4-m. The co-catalyst is an organoaluminum compound. Three different types of ethylene polymerization kinetic curves can be obtained by adjusting the temperature for thermally activating the silica support and the ratio of titanium to magnesium in the titanium-containing main catalyst component.

Abstract: The present invention provides an ethylene polymerization catalyst. The present invention also provides a process for preparing the ethylene polymerization catalyst, comprising reacting powdered magnesium with an alkyl halide of formula RX in the presence of an ether solvent to form a magnesium compound having a structure represented by the formula (RMgX)p(MgX2)q, in which R is an alkyl group having from 3 to 12 carbon atoms, X is halogen, and molar ratio of q to p is in the range of from larger than 0 to 1, impregnating the magnesium compound onto silica carrier, reacting the silica loading the magnesium compound with an alkyl halide of formula R1X, a titatium compound and an alkyl aluminum compound to form a main catalyst component, contacting the main catalyst component with a cocatalyst component to form catalyst for ethylene polymerization. The present invention also relates to the use of the catalyst in the polymerization of ethylene.

Abstract: The present invention provides a main catalyst component for olefin polymerization which is prepared by a process comprising the steps of: (i) reacting a magnesium compound in nascent state having a rational formula (RMgX)y(MgX2), in which R is an alkyl having from 3 to 12 carbon atoms, X is a halogen, and y is a value of from 0.

Abstract: The present invention provides an ethylene polymerization catalyst. The present invention also provides a process for preparing the ethylene polymerization catalyst, comprising reacting powdered magnesium with an alkyl halide of formula RX in the presence of an ether solvent to form a magnesium compound having a structure represented by the formula (RMgX)p(MgX2)q, in which R is an alkyl group having from 3 to 12 carbon atoms, X is halogen, and molar ratio of q to p is in the range of from larger than 0 to 1, impregnating the magnesium compound onto silica carrier, reacting the silica loading the magnesium compound with an alkyl halide of formula R1X, a titatium compound and an alkyl aluminum compound to form a main catalyst component, contacting the main catalyst component with a cocatalyst component to form catalyst for ethylene polymerization. The present invention also relates to the use of the catalyst in the polymerization of ethylene.

Abstract: The present invention discloses a polyethylene catalyst and a process for preparing the same, said catalyst being composed of a main component of catalyst and a cocatalyst, wherein the main component of catalyst is prepared by reacting: (1) a magnesium-alcohol complex, (2) an alkyl aluminum compound having a formula R3nAlCl3-n supported on silica, and (3) a titanium compound having a formula Ti(OR2)mCl4-m, and the cocatalyst is an organic aluminum compound. The catalyst of the present invention has advantages including high polymerization activity, less difference between the polymerization activities at low hydrogen level condition and at high hydrogen level condition, stable polymerization reaction, good particle morphology of catalyst, and less fine powder of polymer product.