FOB Price
Get Latest Price1000 ~ 10000 / Set
|1 Set Minimum Order
Country:
China
Model No:
-
FOB Price:
1000 ~ 10000 / Set Get Latest Price
Place of Origin:
-
Price for Minimum Order:
1000 per Set
Minimum Order Quantity:
1 Set
Packaging Detail:
wooden case
Delivery Time:
60-90 days
Supplying Ability:
10 Set per Year
Payment Type:
T/T
Product Group :
Contact Person anthony
Xianyang, Shaanxi
Top Blown Process
(BOP)
In the top blown process a water
cooled oxygen lance is lowered from the top of the furnace and
blows oxygen at supersonic speed into the melt. The majority
steelmakers utilize top-blown oxygen steelmaking.
Bottom Blown Furnace
(Q-BOP)
In the bottom-blown processes,
oxygen is introduced through a number of tuyeres in the bottom of
the furnace. In the Q-BOP process, the oxygen tuyeres are cooled by
injecting hydrocarbon gas through an outer pipe surrounding the
oxygen pipe. Most bottom-blown processes use methane or propane as
the hydrocarbon coolant, but fuel oil is also used. A principle
advantage of the Q-BOP process is that it reduces the height
requirements of the process allowing a lower profile building to be
constructed.
Combination Processes
One class of combination blown
process uses top-blown oxygen with inert gas (argon and Nitrogen)
injection through the bottom by means of tuyeres or permeable
elements. In the second class of combination furnaces, there are
both top and bottom oxygen lances; the bottom lances can also be
used for inert gas injection during stirring.
The basic oxygen furnace (BOF), whose profile is shown in the figure, is a tiltable vessel lined with refractories such as magnesia carbon brick. Auxiliary equipment includes a chute for scrap charging, hoppers for alloys and fluxes, a lance for injecting pure oxygen gas, a sublance for measuring the temperature and carbon concentration of the molten steel, lifting devices for the lance and sublance, equipment for tilting the vessel, and equipment for recovering and cleaning the exhaust gas. The BOF capacity is expressed as the weight of crude steel that can be decarburized per heat. Most BOFs in China have a capacity of 150-300 tons.
The main function of the BOF is to
decarburize the hot metal using pure oxygen gas. In the top-blown
BOF, pure oxygen is injected as a high-velocity jet against the
surface of the hot metal, allowing penetration of the impinging jet
to some depth into the metal bath. Under these conditions, the
oxygen reacts directly with carbon in the hot metal to produce
carbon monoxide. The pure oxygen top-blown BOF can decarburize 200
tons of hot metal from 4.3% C to 0.04% C during 20 minutes. As a
result of this high productivity, the BOF replaced the open hearth
furnace, which was a much slower process.
The injected pure oxygen gas first
oxidizes silicon and then carbon in hot metal. When the carbon
concentration of the hot metal is decreased to about 1%, the
oxidation of Iron begins in parallel with that of carbon. The
oxidation of Iron becomes marked at carbon concentrations of less
than 0.1%, decreasing both the oxygen efficiency for
decarburization and the decarburization rate, while increasing Iron
loss into the slag. The problem with the top-blown BOF is thus the
oxidation of Iron when a low carbon concentration is reached, and
the resulting decrease in the decarburization rate. When the Iron
oxide content of the slag increases excessively, it can react too
quickly with carbon in the molten Steel and cause sudden gas
evolution, forming a mix of slag and molten Steel that sometimes
erupts from the vessel in a phenomenon called "slopping" or
"spitting".
The use of an oxygen lance with
multiple holes at the tip has proven very effective in delocalizing
the oxygen supply and increasing the decarburization rate while
restraining excessive oxidation of the molten Steel and preventing
slopping and spitting. However, the effectiveness of this lance was
still inadequate, and the bottom-blown oxygen process was
developed, in which pure oxygen gas is injected into the molten
Steel from the bottom of the BOF. The bottom blowing enhances the
stirring of the hot metal and thereby shortens the average mixing
time in the molten Steel bath, and promotes transport of solute
carbon in the bath, preventing the over-oxidation of slag, which is
the cause of slopping and spitting. Consequently, the bottom
blowing enhances decarburization efficiency, especially at low
carbon concentrations. The bottom-blowing is performed with bottom
tuyeres of concentric double-wall pipe. The inner pipe is used to
blow pure oxygen gas along with pulverized limestone as a
slag-forming agent, while propane gas is blown through the outer
pipe as a coolant to prevent tuyere burn back, since propane
undergoes an endothermic reaction during decomposition, which
results in cooling and reduced burning of the tuyeres. These
improvements have made the production of low-carbon steels much
easier.
The top-and-bottom blown BOF, which
combines the advantages of both types of BOF, has recently become
prominent in oxygen steel making. The combined blowing BOF
mostly uses bottom-blown inert gases in place of oxygen gas for
stirring. Various methods of bottom-blowing have been adopted. As
one example, a ceramic plug with embedded multiple small pipes or
multiple slits is used in the bottom tuyeres. Irrespective of the
type of the BOF, the exhaust gas, which is high in CO content, is
either combusted in the throat of the BOF and passes through a
waste-heat boiler installed in the upper part of the throat to
recover the sensible heat and the heat of combustion, or is
recovered through exhaust-gas recovery equipment and stored in a
gas tank for later use as fuel.
Country: | China |
Model No: | - |
FOB Price: | 1000 ~ 10000 / Set Get Latest Price |
Place of Origin: | - |
Price for Minimum Order: | 1000 per Set |
Minimum Order Quantity: | 1 Set |
Packaging Detail: | wooden case |
Delivery Time: | 60-90 days |
Supplying Ability: | 10 Set per Year |
Payment Type: | T/T |
Product Group : | aod |