Working in Partnership for a Cleaner and Safer Environment

Steuler and exclusive UK distributors ICE (UK) Ltd have successfully designed, manufactured, installed and commissioned a major fully automated environmental project for AvestaPolarit to reduce emissions from their stainless steel pickling process.

Stainless steel is a fast growing commodity in which growth forecast remains strong. The western world demand has risen on average by 5.5% per annum over the last 20 years, with the world-wide consumption of cold rolled stainless steel rising on average by more than 7.5% per annum since 1994.

Second largest stainless steel manufacturer AvestaPolarit is strategically increasing sales with an upgrade of its current production line, along with actively pursuing production of different grades of stainless steel.

Taking full advantage of the upgrade of the UK operation at Sheffield to cope with increased production, AvestaPolarit a "environmental aware" organisation took the decision to invest in a fully automatic effective and efficient abatement plant for controlling the emissions from the stainless steel pickling process.

The Specialist
Steuler is a name synonymous with quality in the environmental protection field, supply pollution control equipment world-wide. Steuler Anlaganbau GmbH were awarded the contract based upon the quality, price and the ability to work to a specific timescale. The order was placed in April 2000, with the installation and commissioning completed over the Christmas 2000/2001, annual shutdown.

Steuler Anlaganbau GmbH worked in close alliance with ICE (UK) Ltd, Steuler's exclusive UK distributor, along with MBS the fabrication and installation arm of ICE (UK) in order to design, manufacture and install a Selective Catalyst Reduction (SCR) and Hydrofluoric (HF) acid abatement plant.

The Process (CatNox)
Stainless steel is produced through a number of processes, one of which involves passing the steel coil through a bath of mixed acids for descaling. The baths are a mixture of hydrofluoric and nitric acid, and the fumes from this process are captured using a hood systems that sit over the bath; these hoods were designed, manufactured and installed by Steuler plastics division.

The fume is drawn into ducting from the top of the hoods and transported to the abatement plant, via plastic centrifugal fans.

These gasses still at ambient temperature pass through a demister which removes acidic droplets. The hydrofluoric acid and oxides of Nitrogen (N0x) fumes are then raised in temperature above the dew point to eliminate the risk of acidic condensate corroding the downstream units - particularly the heat exchanger. The gasses pass through a heat exchanger, which recovers heat from the process downstream and raises the temperature before being sent into two hydrofluoric acid fume reactors.

The reactors are filled with Calcium Hydroxide blocks that react with the hydrofluoric acid in the fume chemically changing the blocks into Calcium Fluoride. Once totally 'absorbed' the blocks which are replaced, typically at a pre-planned six monthly interval.

The gases are heated with a duct burner to a preset temperature and a controlled measure of aqueous ammonia solution is injected into the gas stream. The fume then enters the selective catalyst reduction (SCR) where the reaction between the N0x and ammonia occurs on the surface of the catalyst, reducing the N0x to nitrogen and water.

Control
A sample of the raw gas is taken and passed through a N0x analyser, which determines the levels of residual N0x in the fume prior to discharging to atmosphere..

The system, which is fully automated, uses the analyse output to adjust the rate of ammonia solution injected into the gas stream to an optimum level so as to control the N0x and to meet the requirements of the regulatory authority.

The Solution
The entire Steuler CatN0x abatement system is PLC controlled, and uses a 'Supervisory Control and Data Acquisition ' (SCADA) system as an easy and user friendly interface for the operating staff.

All of the conditions of the plant are monitored and the data stored on a built in Data Acquisition System (DAS). A modem can be supplied to allow remote access to the system via a telephone line for customer support and system service from anywhere in the world.

Steuler Anlaganbau GmbH and their plastics Division combined to provide the expertise to ensure that the system would operate to the criteria laid out in the initial design.

Steuler are recognised as the worlds leading supplier of the CatNox systems to the stainless steel industry.

Steuler also provide catalyst technology for the removal of other pollutants such as dioxins, furans, CHx, CO and VOC's and particulates as well as acid scrubbing systems for removal of S0x, HF and HCl's.

Research & Development
ICE (UK) Ltd are instrumental in developing new technology for the use of catalyst, ceramic filtration, lime and bicarbonate dosing systems for use in other industries such as:

- Incineration, smelting and foundry industries
- Clay tile manufacturer, ceramic (white-ware) and porcelain
- Crystal and glass manufacturers
- Diesel engines
- Combined Heat & Power

Business for 2000 / 2001
· 3 Hydrogen Fluoride abatement plants in the brick Industry
· 28 SCR catalyst system order for the USA for power generation
· Thermal Oxidation Process abatement plant for municipal waste incineration
· 25 SCR/Oxidation catalyst for the UK in the Greenhouse industry

For more information on the AvestaPolarit project or future enquires please contact John Daley at ICE (UK) Limited on 01543 428730