Mid Autumn Festival, also known as Moon Festival, moonlight birthday, moon Eve, autumn festival, Mid Autumn Festival, moon worship Festival, yueniang Festival, Moon Festival and reunion festival, is a traditional festival among Chinese people. The Mid Autumn Festival originated from the worship of celestial phenomena and evolved from the worship of the moon on autumn Eve in ancient times. At first, the festival of “sacrificing the moon” was held on the 24 solar terms “autumnal equinox” of the Ganzhi calendar. Later, it was adjusted to August 15 of the summer calendar (lunar calendar). In some places, the Mid Autumn Festival was set on August 16 of the summer calendar. Since ancient times, the Mid Autumn Festival has folk customs such as sacrificing the moon, appreciating the moon, eating moon cakes, playing lanterns, appreciating osmanthus, drinking osmanthus wine and so on.
The Mid Autumn Festival originated in ancient times, popularized in the Han Dynasty, shaped in the early Tang Dynasty and prevailed after the Song Dynasty. The Mid Autumn Festival is a synthesis of autumn seasonal customs. Most of the festival customs factors contained in it have ancient origins. The Mid Autumn Festival symbolizes people’s reunion with the full moon. In order to place the feeling of missing hometown and relatives, and pray for harvest and happiness, it has become a rich, colorful and precious cultural heritage.
The Mid Autumn Festival, the Spring Festival, the Qingming Festival and the Dragon Boat Festival are known as the four traditional festivals in China. Influenced by Chinese culture, the Mid Autumn Festival is also a traditional festival for some countries in East and Southeast Asia, especially local Chinese and overseas Chinese. On May 20, 2006, the State Council listed it in the first batch of national intangible cultural heritage list. Since 2008, the Mid Autumn Festival has been listed as a national legal holiday.
1. By the wet graphite electrode, before use to dry.
2. Lifting the electrode, cushion the soft thing to the standby electrode to install the end of the connector, to prevent the ground contact damage joints, hanging hook into the sling after lifting the ring, the lifting electrode to be smooth, to prevent the electrode from the B-end loose or collision with other fixtures.
3. The standby electrode is hoisted above the electrodes to be connected, and the electrode hole is lowered slowly; rotate the standby electrode to rotate the screw hook with the electrode to decrease; when the two electrical extremes are separated from each other, the 10-20mm of the electrode two ends and the exposed part of the joint are cleaned again with compressed air. When the electrode is finally completely lowered, it can not be too strong, otherwise, because of a violent collision, the electrode hole and the thread of the joint are damaged.
4. The electrode spreader (the sling with graphite material is recommended) is screwed into the electrode hole at the other end of the standby electrode.
5. Remove the foam protective cap on the hole of the standby graphite electrode and check whether the thread is intact in the electrode hole.
6. With oil-free and water compressed air to clean up the spare graphite electrode surface and hole internal thread;
7. The connector carefully into the spare graphite electrode at one end (it is not recommended that the connector directly into the furnace to remove the electrode) in the electrode hole, no collision thread.
8. Torque wrench to screw the standby electrode until the end of the two electrodes close contact (the correct connection between the electrode and the joint is less than 0.05mm).
Graphite & carbon electrode is a non-metallic product. As a necessary cutting consumable before welding in the carbon arc gouging cutting process, it is made of carbon and graphite plus appropriate adhesive, through extrusion forming, after being baked at 2200 ℃ and then plated with a layer of copper. It has high temperature resistance, good conductivity, and is not easy to break. It is suitable for cutting metal into the required shape.
Graphite & carbon electrode is commonly used in the electric heater of high temperature vacuum furnace. The maximum operating temperature can reach 3000 ℃, and it is easy to oxidize at high temperature. Except for vacuum, it can only be used in neutral atmosphere or reductive atmosphere. Its thermal expansion coefficient is small, its thermal conductivity is large, its resistance coefficient is (8 ~ 13) × 10-6 Ω· m, its processability is better than that of SiC and MoSi2, its high temperature resistance, extreme cold and heat resistance are good, and its price is cheaper.
Improvement of process operation and equipment during burning delay Coke of calcining furnace for graphite rod
In the production, the calcination delay Coke of the graphite rod calcination Furnace is put forward, and many measures are proposed to adapt to the calcination delay Coke from both process operation and equipment. The main measures in process operation are:
(1) Low material surface and improve the first layer of the flue temperature. The aim is to make most of the volatiles added to the delayed Coke can be discharged rapidly in a relatively short period of time.
(2) feeding. The amount of each feed not too much (such as the original half an hour to add a material to 15 minutes to add a material), at the same time using continuous discharging mechanism to discharge material, so that the cans often loose material is not easy to form large chunks.
(3) To maintain a high operating negative pressure, and often clean the volatile lead exports and volatile materials, so that volatile can be discharged smoothly.
(4) When the mixture of delayed coke and asphalt coke is used for forging and burning, if the pitch Coke is changed from 50-70 mm to 20 mm, the asphalt Coke and the delayed Coke will be mixed more evenly, and the coking phenomenon can be alleviated.
After adopting the above measures in the process operation, the delayed Coke (such as delayed Coke IV) produced by some refineries has a good effect, but the effect on the delayed Coke V is still unsatisfactory. Delayed Coke v even after the adoption of the above-series measures, in the proportion of mixed coke generally should not be more than 50%, otherwise it is often found in the tank coking and difficult to normal production. In order to further solve the technical problem of the delayed Coke burning in the tank furnace, it is necessary to reconstruct the furnace body structure of the tank furnace properly.
During the operation of the electrolytic cell, the graphite anode is mainly consumed by corrosion in the following forms. Firstly, because the electrolyte contains a large number of hydroxyl ions and a small amount of sulfate and hypochlorite ions as impurities, these ions will discharge on the anode to produce oxygen. The generated primary oxygen oxidizes graphite into carbon dioxide or carbon monoxide, which accounts for more than half of the total erosion of graphite anode.
Secondly, with the deepening of oxidation, the bonding between graphite anode body particles is gradually destroyed, and the loose particles on the surface layer of graphite anode fall off under the scouring of salt water. Oxidation and slag dropping make the anode thinner. To a certain extent, it is necessary to stop the tank for replacement. Such residual loss accounts for more than 1 / 4 of the total consumption of graphite anode. Both oxidation and slag removal consumption are related to the porosity of graphite anode. Large porosity and large consumption. The most common method to reduce the porosity of graphite anode is to impregnate the whole or root with linseed oil, tung oil and other dry oil before use.
1. High temperature resistance: graphite is one of the most high temperature resistant materials known at present. Its melting point is 3850 ℃± 50 ℃ and its boiling point is 4250 ℃. Under 7000 ℃ ultra-high temperature arc for 10s, the graphite loss is the smallest, and the graphite loss is 0.8% by weight. It can be seen that the high temperature resistance of graphite is very prominent.
2. Special thermal shock resistance: graphite has good thermal shock resistance, that is, when the temperature changes suddenly, the thermal expansion coefficient is small, so it has good thermal stability and will not produce cracks when the temperature changes rapidly.
3. Thermal conductivity and conductivity: graphite has good thermal conductivity and conductivity. Compared with ordinary materials, its thermal conductivity is quite high. It is 4 times higher than stainless steel, 2 times higher than carbon steel and 100 times higher than ordinary non-metal.
4. Lubricity: the lubricity of graphite is similar to that of molybdenum disulfide, and the friction coefficient is less than 0.1. Its lubricity varies with the scale size. The larger the scale, the smaller the friction coefficient, and the better the lubricity.
5. Chemical stability: graphite has good chemical stability at room temperature and can resist acid, alkali and organic solvent corrosion.
Graphite electrode is a kind of graphite conductive material with high temperature resistance. Graphite electrode is mainly made of oil-based or coal-based needle coke and coal tar pitch. The technological process of graphite electrode production includes mixing, molding, roasting, asphalt impregnation, re roasting, graphitization and machining. Graphite electrode can conduct current and generate electricity, so as to melt scrap iron or other raw materials in blast furnace to produce steel and other metal products. It is mainly used to make steel. Graphite electrode is the only material with low resistivity and withstanding thermal gradient in electric arc furnace. The main characteristics of graphite electrode production are long production cycle (usually lasting for three to five months), large power consumption and complex production process.
From 2014 to 2019, the global output of graphite electrode excluding China decreased from 800000 tons to 710000 tons, with a CAGR of – 2.4%. In 2019, the output of ultra-high power graphite electrodes outside China accounted for about 90% of the total output of all graphite electrodes in the world except China. In 2019, due to the demolition of low capacity plants, long-term environmental rectification and reconstruction, the production capacity outside China decreased, resulting in the continuous reduction of output outside China. The gap between output and consumption depends on China’s export of graphite electrodes.
Ash increased after calcination. This is because the graphite rods emit a considerable amount of volatile matter during the calcination process, at the same time, there is a small amount of carbon oxidation, and ash in the calcination temperature can not be discharged, so the graphite rods in the forging when the more volatile and oxidation burn loss, the greater the amount of ash increase after the burn. In addition, the raw materials in custody, pre-crushing and burning will also be mixed with some foreign impurities and increased ash.
2. True weighting
The true proportion of all kinds of graphite rods has been improved greatly. In particular, the true gravity of various petroleum cokes, from 1.42-1.61 g/cm 3 before calcination to 2.00-2.12 g/cm 3, increased by about 40%. The increase of the true proportion of graphite rods after calcination is mainly due to the condensation reaction of polymer hydrocarbons at high temperature, and the constant regularity of the basic particle composition of coke. The difficulty degree of graphitization of all kinds of raw materials can be judged by the size of the real proportion after the burn. In general, the higher the true proportion after the same temperature is burned, the more easily graphitization.
All graphite rods shrink in volume after calcination, but the degree of contraction is different. Generally speaking, the volatile material content of raw materials and in the production of more emissions, the greater the degree of contraction _. In the process of forging and burning, the volume variation of Chengjio oil Coke with low temperature is larger. Because the Gio Cheng coke temperature of delayed coking is lower than that of the kettle coking, the content of delayed coke volatile is much larger. For example, the delayed coking of oil Coke V and oil Coke IV, after forging volume contraction reached 25.5% and 28.5%, while the kettle-type coking I and oil Coke II after the volume contraction of only 13% and 14.6%. The Chengjio temperature is close to the calcination temperature of the asphalt coke, and the shrinkage is very small (1.25%) in calcination.
4. Specific resistance
The resistance of anthracite and petroleum Gio before burning is great, and there is a significant change in electric conductivity after forging and burning. After the same temperature has been burned, the petroleum coke has the lowest specific resistance, the tar Coke is slightly higher than the petroleum coke, the metallurgical Coke is slightly more than the Tar Coke, and the anthracite is higher than the resistance. The ash content of anthracite coal fluctuates greatly, so the specific resistance of anthracite is not only related to calcination degree.
Graphene exists in nature, but it is difficult to peel off the single-layer structure. Graphene layer by layer is graphite. Graphite with a thickness of 1mm contains about 3 million layers of graphene. When a pencil scratches gently on the paper, the trace may be several layers or even just one layer of graphene.
In 2004, two scientists, Andre Guy (Andre Geim) and Kostya Novolov (Konstantin Novoselov), from the University of Manchester, UK, separated the graphite sheet from the highly oriented pyrolytic graphite, and then glued the two sides of the sheet to a special tape. They kept doing this, so the sheets became thinner and thinner. Finally, they got a sheet composed of only one layer of carbon atoms, which is graphene. In the following three years, Andre Geim and Konstantin Novoselov found the integer quantum Hall effect and the quantum Hall effect at room temperature in the single-layer and double-layer graphene systems, respectively. Therefore, they won the 2010 Nobel Prize in physics.
The graphite electrodes produced in our country generally use straight-line joints, with less taper joints. The advantage of using cone joint is that it is easy to twist the joint, the joint hole is tapered so the hole wall of the joint hole is thicker, the strength of the hole wall at the impact is larger, the joint hole and the joint are not easy to break (compared with the linear joint), this is the advantage of using tapered However, the processing cone joint ergonomics is low (more than one times lower than the straight-line connector), the material yield is low when processing, and the use of cone joints once shaken loose buckle is easy to drop.
The electrodes for processing the taper joints of graphite electrodes are also made of ordinary lathes. The machining method of the outer circle of the graphite electrode is similar to that of a straight-line joint electrode, in the flat end face and boring, milling thread should be on the lathe on the other side of the mold device, so that the car knife or milling cutter in the direction of the specified diagonal movement, thus processing the cone.
When machining graphite electrode joint, the blank of the outer circle of the car is divided into several sections according to the joint length. The two halves of each section are Cheng Cheng to the cone of the ends (according to the taper specified in the drawing), the same is done by the mould device, and finally, each section is cut, and the thread is milled individually. The end of the joint is fixed on the chuck at the end of the milling thread, and the thread, the flat end face and the end part of the milling ends are milled on the side of the double cone billet.
The semi-finished product of one end thread has been milled on another lathe (removing the chuck instead of the first) and processing the other end in the same way. During processing, the end of the thread is screwed into the tire to protect the thread, and then the same tool is used to mill the other end of the thread and flat end face, milling half buckle, etc.