Specific emission control processes

Converter gas recovery (LT process)

State of the art dry gas cleaning and CO-gas recovery technology for steelmaking converter plants.

Converter Gas Cleaning and Recovery using the Lurgi-Thyssen (LT) Steel Gas process

The conversion of hot metal into steel produces CO-laden gases of high caloric value. The recovery of these gases means to save a considerable amount of energy. 

Based on this idea Lurgi together with Thyssen developed in the 1980s the LT-Steel Gas Process.

The LT-Steel Gas Process has become more and more accepted and is in the meantime established worldwide.

Special features:

  • Extremely low clean gas dust contents
  • High steam and gas recovery rate
  • Minimized energy consumption
  • No wastewater or sludge treatment 

Dry electrostatic gas cleaning is the key because it meets the demands of modern environmental protection.

The heart of this process is the cylindrical-type precipitator, specially designed for the dry collection of the fine dust in CO-laden gases.

Working Principle

Working Principle of LT-Process
The waste gas cooling, the cleaning and the steel gas recovery system form the process consisting of:

Movable Skirt

The first precondition for the steel gas recovery is to capture the converter off-gases as concentrated as possible, the task of the movable skirt is to protect the off-gases from entrainment of false air, which would deteriorate the calorific value of the gases.


Waste Gas Cooling Stack

The gases leave the converter at a very high temperature. This heat is used for steam production and represents the first step of energy recovery.


Gas conditioning tower

In the gas conditioning tower, the gases are cooled down to a moderate temperature with especially designed two phase nozzles atomizing water into finest droplets. Off-gas and dust are still dry. Besides cooling, the separation of coarse dust particles and the gas conditioning for the following electrostatic precipitator take place.


Electrostatic Precipitator

The round design warrants a perfect plug flow of the gas which is essential for safe operation. The cylindrically shaped casing requires a special kind of dust removal. A specially designed dust scraper transports the collected fine dust to a trough type chain conveyer installed underneath the casing. Using latest controller systems for the high-voltage transformer rectifier sets improve the dust collection efficiency significantly and save energy costs. Downstream of the electrostatic precipitator an axial flow fan is installed. 


Switchover Station

As soon as the gas contains a sufficient concentration of CO-gas, the switchover station directs the gases to the recovery system and during non-blowing time to the flare stack.


Gas cooler

The gas cooler cools the recovered gas down to the saturation temperature for safe and efficient storage in the gas holder. Downstream of the gas holder the recovered steel gas is led to the consumer grid via booster fans.

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