LAT Nitrogen Linz GmbH operates two melamine production plants in the Linz Chemical Park. A new state-of-the-art wastewater treatment plant was built for both plants.
LAT Nitrogen (Borealis Agrolinz Melamine GmbH until July 2023) awarded Pörner Ingenieurgesellschaft mbH in Linz the EPCM execution of this challenging project in March 2020. The contract included authority engineering, extended basic engineering, detail engineering, project management, scheduling, procurement support with expediting, construction supervision and commissioning support. The total investment cost of the modernization was approximately 42 million Euros. After a successful commissioning phase, the new thermal wastewater treatment plant has been in full operation since the end of July 2023.
Dismantling of 1,500 tons
The project consisted of two sub-projects: First, the two decommissioned melamine plants 2&3 had to be completely dismantled. This included the removal and proper disposal of 148 tons of insulation and piping, 1,200 tons of steel and aluminum, and another 160 tons of construction debris. The nine-month process lasted until November 2021, when the site was cleared. Still in the fourth quarter of 2021, the construction of the new treatment plant for the process wastewater of the operating melamine plants 4&5 started. Melamine plant 5 with demanding process parameters (175 bar pressure and over 400 degrees Celsius temperature) was planned by Pörner in 1998 - 1999.
State-of-the-art wastewater treatment
In the melamine plants, urea is used as the feedstock from which the final product, melamine, is purified and isolated by aqueous processing. The mother brine used in this process is largely recirculated. For quality reasons, it is necessary to discharge a minimum amount of mother brine. The treatment of this "process wastewater" was previously carried out by two existing thermal wastewater treatment plants. In the course of the project, these were replaced by a new plant with the best available technology and a 1000 m³ double wall tank was built to buffer the raw process wastewater.
The new wastewater treatment plant consists of two pressure vessels (hydrolyzers) connected in series and run at an operating pressure of 45 bar and an operating temperature of over 230 degrees Celsius. As the wastewater flows through the two hydrolysers, the organic nitrogen compounds are hydrolyzed to ammonia and carbon dioxide by reaction with water. The downstream stripper removes the dissolved ammonia from the wastewater, which is then condensed and recirculated to the process as an ammonium carbonate solution. The purified "process wastewater" is recooled via heat exchangers and, after controlling all legal limits (pH, temperature, turbidity, etc.), is discharged into the cooling water channel.
Two superlatives on their way from Mumbai to Linz
The two hydrolysers weigh 180 tons each and are 37 meters long. They were manufactured in India and shipped from Mumbai to Antwerp. They then continued their journey on inland waterways via the Rhine, Main and Danube rivers to their destination in Linz.
The challenge on site was to place the two hydrolyzers on the five-meter high foundation strips on the plant premises. Due to space limitations, cranes could not be used to lift the hydrolysers, so a special hydraulic lifting/sliding system was used.
The operating temperature of the hydrolyzers is maintained at over 230 °C by heat exchanger bundles heated with 40 bar steam. A corresponding supply pipeline from the two ammonia plants had to be newly constructed and existing pipe bridges had to be upgraded. In April 2023, the 1.2-kilometer 40-bar steam pipeline, including the condensate system, was successfully commissioned.
In total, in the new plant:
- 40 pieces of equipment
- 8,100 m of piping
- 3,600 flanges
- 3,700 bends
- 2,000 fittings
- and 300 EI&C field devices
were prefabricated, installed and tested.
Pörner project manager Harald Grünberger sums up: "It were exciting three and a half years to accompany this plant from dismantling and new construction across all engineering disciplines to commissioning. After very demanding weeks, the hydrolysis plant was handed over to operations, on time, on June 16, 2023 with Mechanical Completion. We are pleased together with LAT Nitrogen that the plant is now running as planned and LAT Nitrogen can produce melamine in compliance with all environmental regulations!"
About LAT Nitrogen
LAT Nitrogen is a leading European provider of nitrogen-based products in the fertilizer and industrial chemical market. The company was created through the acquisition of Borealis Fertilizer, Technical Nitrogen and Melamine business by Agrofert in 2023. LAT Nitrogen employs nearly 2,000 employees across Europe and has production units located in Austria, France and Germany. The company has an extensive warehouse and commercial network in Western, Central and Eastern Europe.
