NOURISHING BY NATURE
The customer’s plant – one of the biggest dairy plants in the world – supplies millions of users with dairy products worldwide every day.
At the customer’s site in the Netherlands the milk is processed to butter products and to high-quality powdered milk. Therefore, the plant has five independent spray towers for drying.
Depending on the process the drying of milk can lead to high temperatures which can cause an explosion or a fire in the plant. Furthermore safety regulations and regulations for explosion protection apply for the equipment of the towers which are tightened constantly. That’s why the existing extinguishing system of the spray towers had to get renewed and adjusted to the latest safety regulations. Also, the concept for the emergency stop and the instrumentation equipped in the explosion-prone area was tested and – if necessary – renewed.
THE SPECIAL FEATURES
Due to the conditions a proper solution was developed for these works. On the one hand, the components could only be placed where spacial conditions allowed it. On the other hand the reconstruction went step by step, meaning that after the installation of the new fire-extinguishing system the towers got connected to it one after another within the frame of planned production downtimes. Simultaneously, the necessary adjustments needed for the respective towers were made.
To meet the high safety requirements, a redundant voltage supply was implemented in the first step. This could only be done with the new fire extinguishing system running via a low-voltage transformer during normal operation and via a stand-by generating set during a voltage breakdown.
The aggregate placed in a container together with a professional F90 version of the incoming line ensures power supply even in case of a fire. The controls are additionally equipped with an uninterruptible power supply (UPS), so that under no circumstances the safety technology can fail.
The fire extinguishing system is fed through three large pumps. These are designed for one spray tower each so even in case of a fire in two of the spray towers there is still one pump in reserve. Additionally, a pressure holding pump keeps the main riser permanently filled with water. This enables an immediate extinguishing of the part of the plant which is on fire.
Another component for increasing the safety was realized by the plant automatically performing a self-test including a trial run of the fire extinguishing pumps during operating hours.
Within the framework of this project other than modernizing the fire extinguishing system the escape routes got equipped with buttons for an emergency stop. In case of dangerous situations these cause an immediate, safe shutdown of the plant.
In the course of the shutdown there may occur high temperatures in the spray tower. This challenge was taken up with the cooling system VERTEX. This system cools down the intake air temperature to approx. 110 °C with altogether five nozzles that are controlled in groups. The system is working even if the external power supply fails.
- 3 fire extinguishing pumps (all 150 m³/h at 6 bar)
- 1 pressure holding pump (3 m³/h at 13 bar)
- VERTEX Cooling System for Every Spray Tower
- 1 diesel stand-by generating set 220 kW according to VDE 0100 part 718
- measuring instruments as ex version: Endress & Hauser
- control system: Siemens Step 7 with WinCC
- data points: approx. 800 I/Os
- coupling to external systems: yes
- stations: 6 units, S7–315-2DP failsafe
Scope of Delivery
- delivery and commissioning of three fire extinguishing pumps and a pressure holding pump
- construction of the new fire extinguishing system incl. the installation of the spray nozzles
- five VERTEX Cooling Systems
- construction of a new concept for the emergency stop incl. adjustments to the wiring of the control cabinet
- failsafe program for controlling the extinguishing process
- reconstruction of control cabinet
- 24-hour production support for 10 days
- 24/7 On-Call Service
- annual maintenance of fire extinguishing system