Тандем - 2, шлакоблочные станки, бетоносмесители


Производство оборудования и технологии
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Carbon Management

In the Texaco process, soot is extracted from the carbon-water mixture with naphtha and recycled with the feedstock to the reactor where it is gasified to extinction. The black water from the quench and the scrubbing section is cooled and contacted with the naphtha in the decanter. In this vessel the naphtha extracts the soot from the water leaving much (but not all) of the ash present in the water phase (gray water). The soot-naphtha mixture is drawn off the top of the decanter and mixed with fresh feed oil. The naphtha is recovered in a distillation tower and recycled to the decanter, leaving the soot-oil mixture as a bottoms product for feeding to the gasi­fier. Traces of naphtha remain in the tower bottoms and are gasified as well. This naphtha slip has to be made up with fresh naphtha to the system.

The gray water is degassed to recover naphtha and recycled for use in the quench and scrubbing sections. When operating in quench mode the overall water balance is negative because of the large amount carried out with the syngas. Nonetheless, a bleed stream of gray water is bled from the circuit to remove ash. This is necessary to limit the buildup of ash in the circuit. This is by no means trivial, and a soot-oil gasifier feed metals content of about ten times that of the fresh feedstock has been reported. A device was developed that reduced this buildup factor to about 2.5 (Czytko, Gaupp, and Muller 1983).

When operating in the syngas cooler mode there is little water in the raw syngas, so that the bleed stream is necessary in any case to maintain the water balance.

Equipment Performance

The equipment for the process has proved reliable in service, and in a study on operation and maintenance aspects of the process, the data in Table 5-10 have been published.

Process Performance

Typical process performance for different feedstocks is shown in Table 5-11.

Table 5-10

Maintenance Intervals for Texaco Oil Gasifier

Component

Frequency

Time required for intervention

Burner

every six months

6-10 hrs

Quench

every two years

156-180 hrs

Refractory

every three years

680-760 hrs

Source: Bresson and Curcio 1997

Table 5-11

Performance Data for the Texaco Oil Gasification Process

Feedstock Type

Natural

Gas

Naphtha

Heavy Fuel Oil

Tar (from Bituminous Coal)

Feedstock composition

C, wt%

73.41

83.8

87.2

88.1

H, wt%

22.8

16.2

9.9

5.7

O, wt%

0.8

0.8

4.4

N, wt%

3.0

0.7

0.9

S, wt%

1.4

0.8

Ash, wt%

0.1

Raw gas composition

Product gas (25 bar, quench)

Carbon Dioxide, mol%

2.6

2.7

5.7

5.7

Carbon Monoxide, mol%

35.0

45.3

47.4

54.3

Hydrogen, mol%

61.1

51.2

45.8

38.9

Methane, mol%

0.3

0.7

0.5

0.1

Nitrogen + Argon, mol%

1.0

0.1

0.3

0.8

Hydrogen Sulfide, mol%

0.3

0.2

Soot, kg /1000 Nm2

1.8

10

6.1

Consumption figures per

1000 Nm3 CO+H2

Feedstock, kg

262

297

323

356

Oxygen, Nm3

248

239

240

243

Steam, kg

74

148

186

With permission: ChevronTexaco

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