Valves in action
Back pressure regulator UV 5.5
Control of the water pressure in the SNCR plant of a corrugated board manufacturer

In the packaging industry, the trend is increasingly shifting away from plastic materials. Instead, sustainable paper-based packaging solutions are preferred in order to achieve ambitious climate protection targets. As early as 150 years ago, cartons and containers made of corrugated board began their triumphal march around the world. Today, corrugated board production is a complex high-tech process.

UV 5.5

A leading company on the European market produces 500,000 t of corrugated base paper annually in its German paper mill on the basis of 100 % recovered paper. In the paper machines, the pulp suspension is formed into a sheet structure, dewatered, dried and rolled into 5 m wide paper webs. To produce the corrugated board, different paper webs, known as flute and linerboard, are then glued together in several layers. The paper must be heated and moistened before it is formed into flute under high pressure between two rollers.

The corrugated board manufacturer produces in a completely closed cycle. The process wastewater is treated and reused in the company's own wastewater treatment plant. Electricity and steam for the company's own needs are generated in a multi-fuel boiler from lignite and rejects - the residual materials resulting from the production of corrugated board base paper - and biogas from the wastewater treatment plant.

 

TASK // Water pressure control in a SNCR plant

The power plant in the factory uses the SNCR process (selective non-catalytic reduction) for flue gas denitrification (DeNOx). This process retains the nitrogen oxides produced during the combustion processes at high temperatures. For this purpose, reducing agents containing ammonia are injected into the plant. The nitrogen oxides from the flue gas and the ammonia-air mixture react with each other and become water vapor and nitrogen.

A frequency converter-controlled pump delivers water for mixing with the urea, which is used as an ammonia-scavenging reducing agent. The UV 5.5 back pressure regulator is installed as a typical bypass valve on the pump pressure side. It keeps the water pressure in the SNCR system constant to ensure a consistent spray pattern within the system. The self-acting valve simultaneously protects the pump control system by conducting water not required by the SNCR system into the bypass.

 

SOLUTION // Modular back pressure regulator UV 5.5

The UV 5.5 is a spring-operated proportional control valve for universal use with small to medium flow rates and is set to 14 bar response pressure. In this application, it controls city water with a flow rate of max. 3 m³/h at a temperature of 15 °C and ensures a constant pressure in the plant.

The body and medium-wetted internal parts are made of stainless steel (1.4404/316L). The seals are made of EPDM, enabling the UV 5.5 to provide excellent resistance to the corrosive atmosphere of the DeNOx plant of the corrugated board factory.

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