Core Features and Principles of VD/VOD Furnaces
Vacuum Environment: By evacuating the chamber (typically to <1 mbar), the partial pressure of CO is significantly reduced. This enables the carbon-oxygen reaction [C] + [O] → CO↑ to proceed vigorously at lower carbon levels (i.e., "vacuum decarburization").
Oxygen Decarburization (VOD Mode): Oxygen is blown onto the surface of molten steel within the vacuum chamber, prioritizing the oxidation of carbon to form CO, which is then evacuated. The vacuum and precise control enable carbon reduction to extremely low levels (e.g., ≤ 0.03% or even 0.01%) while preserving chromium (Cr is not significantly oxidized).
Inert Gas Stirring: Argon (Ar) is blown through the furnace bottom's permeable bricks, vigorously agitating the molten steel to promote reactions, homogenize composition and temperature, and accelerate the rise of gases and inclusions.
Alloying: High-precision alloys are added under vacuum or atmospheric pressure for fine composition adjustment.
Position in the Metallurgical Process
Typically a critical link in the sequence: EAF/AOD → VOD/VD → Continuous Casting.
For Stainless Steel: Primary furnace (e.g., EAF) supplies initial molten steel → AOD performs primary decarburization and chromium preservation → VOD achieves deep decarburization and final refining to meet ultra-low carbon/nitrogen requirements.
For high-quality alloy steel/structural steel: Primary refining in converter/electric furnace → VD for degassing, deoxidation, and purification.
Primary Structural Components
Vacuum vessel: Movable or fixed sealed container for holding ladles.
Vacuum cover: Features observation ports, charging systems, oxygen lance/spray nozzle, temperature measurement/sampling devices, and seals to the vacuum vessel.
Vacuum System:
Steam jet pump: Traditional mainstream technology utilizing high-pressure steam to generate ultra-high pumping capacity, capable of handling large gas volumes (e.g., substantial CO produced during oxygen blowing).
Mechanical pump (Roots pump + dry pump) combination: More energy-efficient and environmentally friendly (no boiler required), representing the trend for modern new projects.
Oxygen Blowing System (VOD Core): Top lance, adjustable in height, for oxygen injection.
Argon Blowing & Agitation System: Connects to the vent bricks at the ladle bottom.
Charging System: Used to add alloys, deoxidizers, etc., under vacuum conditions.
Control System: Automated control system based on carbon-oxygen balance models and temperature prediction models, enabling real-time regulation of oxygen blowing rate, vacuum level, agitation intensity, etc.
Comparison between VD and VOD Modes and Typical Parameter Table
| VD | VOD | Note | |
| Core purposes | Degassing (H, N), deoxidation, purification | Deep decarbonization and degassing | |
| Main steel varieties | Bearing steel, gear steel, high-end structural steel | Austenitic stainless steel (304L, 316L), ultra-pure ferritic stainless steel (444), silicon steel | |
| Working vacuum degree | 0.5 - 1 mbar (higher degree is required for deep dehydrogenation) | 20 - 100 mbar (oxygen blowing period) → <1 mbar (degassing period) | A certain pressure must be maintained during the oxygen blowing period to control the reactio |
| Oxygen blowing | None | blown in by the top lance | Core characteristics of VOD |
| Initial carbon requirement | Regular | Relatively high (e.g., 0.3% - 0.6%), providing heat and reactants for decarburization | |
| End-point carbon capacity | Depends on initial carbon-oxygen balance | Extremely low (≤0.03%, even 0.01%) | |
| Processing cycle | Relatively short (30-50 min) | Relatively long (50-70 min) | Because it includes an oxygen blowing stage |
Our company has rich experience in the design and manufacturing of different international furnace structures. Over the years, we have provided thousands of sets of equipment to major foreign iron and steel enterprises and heavy machinery enterprises, and our products have been exported to more than a dozen countries and regions. The quality and service of our products enjoy a good reputation among users and are well received by them.
Main parameters of VD/VOD provided by our company
|
Rated Capacity |
Ladle Diameter |
Vacuum Tank Diameter |
Vacuum Tank Height |
Vacuum PumpPumping Capacity |
Working Vacuum Degree |
|
(t) |
(mm) |
(mm) |
(mm) |
(kg/h) |
(Pa) |
|
15 |
2000 |
3800 |
4000 |
100 |
67 |
|
20 |
2200 |
4000 |
4200 |
150 |
67 |
|
30 |
2600 |
4400 |
4600 |
200 |
67 |
|
40 |
2800 |
4800 |
5000 |
200 |
67 |
|
50 |
2900 |
5000 |
5200 |
250 |
67 |
|
60 |
3150 |
5200 |
5400 |
300 |
67 |
|
80 |
3400 |
5600 |
600 |
350 |
67 |
|
100 |
3500 |
5800 |
6200 |
400 |
67 |
|
120 |
3650 |
6100 |
6300 |
400 |
67 |
|
150 |
3900 |
6300 |
6600 |
450 |
67 |
