Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
  • C21C5/56—Manufacture of steel by other methods
  • C21C5/562—Manufacture of steel by other methods starting from scrap
  • C21C5/565—Preheating of scrap
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D13/00—Apparatus for preheating charges; Arrangements for preheating charges
  • F27D13/002—Preheating scrap
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• This invention relates to a method and a device for pre-heating waste metal for furnaces, flue gases generated in a furnace being supplied simultaneously or sequentially to two pre-heating chambers with waste metal containers.
• waste metal can be utilized as main raw material in electric arc furnaces. Moreover, waste metal can be used as cooling agents in basic oxygene furnaces.
• the invention suggests a combustion chamber provided with a controlled burner of its own, by means of which unburnt gases from the elec trie arc furnace, on one hand, and, on the other hand, from the pre-heating chambers are post-combusted and destructed at a temperature controllable in time. Moreover, a larger amount of energy is added to the flue gases which is then recycled to the process via a hotter waste metal.
• the location of the combustion chamber is independent of the position of the electric arc furnace. In other words, it can thus be placed in a direct connection with the pre-heating chambers.
• the waste metal can also be heated at times with cold flue gases from the furnace by means of the burner.
• a pre-heating device is shown with reference to the figure. Flue gases generated in an electric arc furnace/basic oxygene furnace are evacuated via a dust collector 2 to a combustion chamber 19 provided with a burner 20 and thereafter further to two pre-heating chambers 3 and 4.
• the burner 20 is intended to produce hot flue gases for admixture with flue gases from the furnace 1 and for post-combustion of unburnt gases from the furnace 1 and from the pre-heating chambers 3 and 4.
• the burner 20 can be fired e.g. by means of oil, carbon powder, gas or biofuel (powder).
• oil, carbon powder, gas or biofuel powder
• the burner 20 consist of an electric plasma burner for production of hot air which can be mixed with the flue gases from the furnace 1 and/or the chambers 3 and 4.
• the combustion chamber 19 is provided with connecting ducts for flue gases; an inlet duct 23 for flue gases from the furnace 1, an outlet duct 24 for super heated flue gases to the pre-heating chambers 3 and 4, an inlet duct 25 for unburnt flue gases from the chambers 3 and 4 and an outlet duct 26 for burnt flue gases to the gas cleaning plant 5 for flue gases.
• a by-pass duct 27 for flue gases is arranged between the inlet duct 23 and the outlet 10 and a by-pass duct 30 is arranged between the ducts 25 and 26.
• the pre-heating chambers 3 and 4 are each provided with an inlet duct 6 and 7, respectively, and an outlet duct 8 and 9, respectively.
• the outlet ducts 8 and 9 are connected to a common outlet 10.
• flue gas fans 12 In order to achieve evacuation of the flue gases flue gas fans 12 with a variable speed are arranged in the outlet 10 and immediately upstream the plant 5, respectively.
• the pre-heating chambers 3 and 4 comprise each a liftable roof 13 which is intended to be sealingly adapted on top of a waste metal container 14 in the respective chamber 3 and 4.
• Said containers 14 which can constitute for example a basket or a chute placed on a carriage are preferably provided with a water-cooled jacket and a water-cooled bottom with automatic connection of cooling water and emptying of the water circuits upon charging of the waste metal in the furnace in order to be able to withstand the high gas temperatures (500-1000°C).
• the sealing between the covers 13 and the chambers 3 and 4, respectively, can be achieved for instance by means of an annular waterseal 15.
• the pre-heating chambers 3 and 4 are mutually connected by means of a crosswise connection system, i.e. the chamber 3 is connected to the inlet duct 7 by means of a passage 16 while the chamber 4 is connected to the inlet duct 6 by means of a passage 17.
• the ducts included in the device are provided with adjustable and controllable flue gas dampers 18.
• the flow of the flue gases through the chambers 3 and 4 will be described in the following.
• the flue gases are led via the inlet duct 6 to the chamber 3 containing a waste metal basket 14 next in turn to be charged.
• the flue gases flow through the waste metal container 14 and further through holes in the bottom of the container 14 into the chamber 3.
• the crosswise connection system makes it possible to lead the flue gases via the ducts 16 and 7 to the pre-heating chamber 4 in which the flow is in the same way as in the chamber 3.
• the flue gases are thereafter evacuated through the outlet duct 9 and the outlet 10 either to the flue gas cleaning plant 5 or to the combustion chamber 19.
• the flue gases can also be led directly from the chamber 3 to the outlet 10 without passing the chamber 4.
• the flue gases can first be made to pass the chamber 4 if it is found that the waste metal container 14 therein is next in turn for charging.
• the crosswise connection system is then utilized in the same way as described above.
• the flue gases are first supplied to the chamber containing the hot waste metal basket, so-called cascade heating.
• a high temperature 800-1000°C
• the flue gases are thereafter made to flow via the crosswise connection system through the next chamber with a waste metal basket previously heated in the same way.
• the gases can be evacuated from the furnace 1 directly via the bypass duct 27 to the gas cleaning plant 5.
• the flue gases generated in the furnace 1 stream into the combustion chamber 19 via the duct 23.
• the superheated flue gases leave the chamber 19 via the duct 24 and flow thereafter through the pre-heating chambers 3 and 4 in the way previously described.
• the flue gases can be led directly to the plant 5 via the ducts 10 and 30 or be recycled through the combustion chamber 19 via the ducts 25 and 26.
• a heat exchanger 31 is arranged between the ducts 25 and 26.
• the ratio of gases generated by the burner 20 to flue gases generated in the furnace 1 can be varied thanks to the fact that the capacity of the burner 20 is adjustable steplessly. If the furnace 1 does no generate any flue gases at all the burner 20 can generate alone a sufficient amount of flue gases for pre-heating the waste metal.
• the furnace 1 is an basic oxygene furnace there will be difficulties in leading the hot unburnt gases to the chambers 3 and 4 and the combustion chamber 19, respectively, and therefore the burner 20 in this case accounts alone for the pre-heating of the waste metal.
• the hot flue gases are more suitable for use as fuel.
• the gases can be supplied to the fuel supply system 21 via the duct 29 after treatment.
• Process control of the pre-heating device can be carried out by means of a microprocessor 28 which also controls the part systems included in the device in addition to the control of dampers 18, roof lifting device (not shown) and fans 12.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
• Furnace Details (AREA)
• Incineration Of Waste (AREA)
• Vertical, Hearth, Or Arc Furnaces (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20364184

Family Applications (1)

Country Status (8)

Cited By (4)

Families Citing this family (5)

Citations (4)

Family Cites Families (7)

• 1986
  • 1986-04-15 SE SE8601691A patent/SE452191C/sv not_active IP Right Cessation
• 1987
  • 1987-04-15 WO PCT/SE1987/000195 patent/WO1987006331A1/en not_active Ceased
  • 1987-04-15 DE DE8787902830T patent/DE3776286D1/de not_active Expired - Lifetime
  • 1987-04-15 EP EP87902830A patent/EP0268606B1/en not_active Expired - Lifetime
  • 1987-04-15 US US07/133,065 patent/US4812117A/en not_active Expired - Lifetime
  • 1987-04-15 AU AU72898/87A patent/AU606057B2/en not_active Ceased
  • 1987-04-15 JP JP62502421A patent/JP2621895B2/ja not_active Expired - Lifetime
  • 1987-04-15 AT AT87902830T patent/ATE72036T1/de not_active IP Right Cessation

Patent Citations (4)

Also Published As

Similar Documents

Legal Events