Industrial Carbon and Graphite Materials. Группа авторов

Чтение книги онлайн.

СКАЧАТЬ water to cool. After, the top and bottom heads of the full coke drum cooled are removed, and then the solid raw coke is cut from the coke drum with a jet stream of high‐pressure water and transferred into a tank for dewatering.

A typical example of the material balance in coking and the physical properties of coke, oil, and gas is shown in Table 6.1.3.3 [1, 7, p. 79]. PC generally differs from petroleum coke as follows:

       A yield of the coke relative to the raw material supplied is larger [1, 7, p. 76].

       The content of ash and sulfur in raw coke is less and the content of nitrogen is higher [1, 7, p. 76].

       Since the aromaticity of the raw material supplied is higher but its reactivity is lower [8, 9, p. 159], coking is performed at higher temperature [1, 7, p. 76].

       The aromaticity of oil as a by‐product is high and the content of hydrogen and methane in the gas formed is high [1, 7, p. 76].

The variation of the carbon and hydrogen ratio in different production processes is given in Table 6.1.3.4 and Figure 6.1.3.3, respectively. In the case of PC, the C/H ratio indicates that the raw material comprises on average four aromatic rings as in chrysene, but coking of the raw coke increases the number of aromatic rings to exceed 10 as in ovalene, and after calcination the carbon content is almost 99%. The carbon content in the raw material is higher in the case of PC, but the carbon content of raw coke after coking and that in a product after calcination are similar.

      As compared with the chamber coking process, the delayed coking process is substantially improved as follows:

       Environmental pollution

Table 6.1.3.3 Production of PC by the delayed coking process.

Material balance and properties of products.
Typical delayed coking yield	wt% of charge
Product gas	3.0
Light oil	10.7
Heavy oil	25.4
Coke	60.9
Total	100.0

Average properties of products
Product gas
	vol%
H2	48.2
N2	Trace
CO	1.0
CO2	Trace
CH4	44.9
C2H4	Trace
C2H6	5.9

Light oil
Specific gravity	1.018
Naphthalene content (wt%)		32.5
Distillation (°C)	IBP	180
	10	205
	50	235
	70	247
	90	275
	EP	310

Heavy oil
Specific gravity	1.085
Conradson carbon (wt%)		0.30
Distillation (°C)	IBP	256
	10	293
	50	324
	70	338
	90	367
	EP	400

Coke
Apparent density (lb./cu.ft.)	61–69
Volatile combustible matter (wt%)	7.5–9.5

Table 6.1.3.4 Variation of the carbon and hydrogen ratio in production steps of pitch coke.

	C (wt%)	H (wt%)	C/H (atomic ratio)	References
Feed	91.6	5.1	1.50	[6]
Raw coke	94.6	2.8	2.82	[5]
Pitch coke	98.68	0.34	24.19	[4]

СКАЧАТЬ