Needle coke, production

Table II shows estimated yields and product qualities for three typical needle coker feedstocks. The feedstocks are considered desirable needle coker feedstocks because of their high density, low sulfur content and highly aromatic nature. Note the high production of coke, the result of high pressure and high recycle ratis, which is typical in needle coke production.

Table II. Estimated Yields and Product Properties For Needle Coke Production...

In contrast, needle coke formation is an endothermic reaction. This is shown by the 50 F-80 F drop in temperature between the coke drum inlet and outlet during needle coke production. 

A schematic diagram of the liquid solvent extraction process is illustrated in Figure 1. Where the production of liquid hydrocarbons is the main objective an hydrogenated donor process solvent is used, whereas in the production of needle coke this is not necessary and a coal derived high boiling aromatic solvent may be used (e.g. anthracene oil). An essential economic requirement of the process is that a high extraction yield of the coal is obtained and this will depend upon the coal used and the digestion conditions. 

Needle Coke. Usually produced from highly aromatic thermal tar, pyrolysis tar or decanted oil stocks. This coke is typically characterized by a fibrous texture with long, unidirectional "needles" of coke. This form of coke is a premium product, which is sold to the carbon industry for use in the manufacture of large graphite electrodes. 

Needle Coke Operation - Typical Yields and Product Qualities... 

A specialized application of petroleum coke is the production of electrodes for the steel industry. For this application, it is necessary to use needle coke because its low coefficient of thermal expansion and low resistivity. The needle coke must have low sulfur and low metals content. After production in a delayed coker, needle coke is crushed and calcined in preparation for electrode production. 

A general description of the carbonization processes using the characterization methods for widely used coke products like binder coke, regular coke, and needle coke is given in this review. The... 

Chemistry in the Production and Utilization of Needle Coke, Isao Mochida. Ken-ichi Fujimoto, and Takashi Oyama... 

The ultimate pitch product is a black tar best characterized by its softening point. This can vary from below room temperature to above 200°F by control of front-end distillation. Its specific gravity is normally 1.15-1.20, and it is incompatible with asphalt or residual fuel oil. It finds markets as a raw material for petroleum coke or carbon black and for various specialty end uses. It is a preferred feed for needle coke manufacture. It can also be used as a low sulfur fuel oil. 

Mochida I, Fujimoto K, Oyama T. Chemistry in the production and utilization of needle coke. 

Petroleum coke is a carbonization product of high-boiling hydrocarbon fractions obtained in petroleum processing (heavy residues). It is the general term for all special petroleum coke products such as green, calcined and needle petroleum coke. 

Needle Coke. Needle coke, named for its needle-like structure, is made from feeds that contain nil asphaltenes, such as hydrotreated FCC decant oils. Needle coke is a high-value product used to make graphite electrodes for electric-arc furnaces in the steel industry. At present (April 2004), needle coke fetches more than US 500 per ton, which is significantly greater than the US 40 to US 45 per ton price for metallurgical coke exported from the United States. 

The physical and chemical properties of fuel coke, anode coke, and needle coke vary substantially, and determine the end use of the material that can be burned as fuel, calcined for use in the aluminum, chemical, or steel industries, or gasified to produce steam, electricity, or gas feedstocks for the petrochemicals industry. Petroleum coke can be successfully employed for the production of synthesis gas via gasification route. Since the main objective in a coking-based refinery is to maximize liquid product yield, any value added by selling the fuel grade coke is a bonus for the refiners (Jacob, 1971 Dymond, 1991). 

Low sulfur and ash levels are required for high GTE, isotropic cokes used for carbon and graphite specialty products. Highly isotropic cokes are also the filler materials for producing graphite for nuclear reactors. The purity, particularly the boron content, is critical in this appHcation. Properties of typical needle and isotropic (regular) cokes are summarized in Table 1. 

Cokes are also the product of liquid-phase carbonization of pitches, as mentioned above. The nanotexture of the resultant cokes can be changed by applying a shear stress during liquid-phase carbonization, giving the so-called needle-like cokes, which are now important raw materials in the production of large-sized graphite electrodes for metal refining [93],... 

Needle-like coke has been widely used for the industrial production of graphite electrodes for steel refining. The changes in transverse magnetoresistance (Ap/p0) with the rotation angles 9 and 9 of the magnetic held along and perpendicular to the axis of a needle-like particle (TL and T... 

Needle Grade Coke, which is produced from highly aromatic with low asphaltenes, sulfur, and ash content feedstocks. This coke, with high strength and low coefficient of thermal expansion, is used to manufacture large electrodes for the steel industry and the production of synthetic graphite. 

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