New control and pump for feed water in Hylte

Hylte paper mill wanted the pumping of feed water to work automatically. Operators would thus be free to work on other issues that required more commitment.

Hylte paper mill wanted the pumping of feed water to work automatically. Operators would thus be free to work on other issues that required more commitment.

Optimation created a new control system that together with a new pump gave the mill an efficient and fully automatic control of their feed water facility.

"Hylte wanted a control system that required as little interference as possible," says Björn Söderlund, Optimation. "Ideally, none at all. The operators would be able to rely on the automation and focus on more important things. At the same time, the plant of course wanted a feed water system that consumed an as small amount of energy as possible, by optimizing the pressure level so that it provides a necessary flow, but no more."

As one pump consume less power than two, one of the proposed measures became to replace one of the five pumps with a 50 percent larger one, which also was speed regulated.

"The larger pump was dimensioned to meet the complete need on its own, when that was at a normal level. Previously, the pumps’ size had put the need to between one and two pumps, which caused many starts and stops of the pumps. In combination with the fact that two of the pumps lacked speed-regulation, it all provided an unnecessarily high energy consumption."

Optimation had created the regulation that existed before the latest project as well, and that control system had worked very well. But changes in the production in Hylte also changed the requirements of the plant’s feed water system, and the regulation of the pumps hence became less efficient. Therefore, a new project was conducted where the new larger pump was installed, and Optimation was engaged to adapt the control system for this pump.

"But the project became larger, and we created a completely automatic control system," says Björn Söderlund.

Optimation noted during the project that the regulation would be more effective if, instead of speed control, one regulated the pumps with respect to torque, a quantity that is proportional to both power and flow.

"It is quite unusual that one run different sized pumps in parallel as in Hylte. If we had used speed regulation only, it would probably have led to that the largest pump would often have had to do all the work, instead of having a regulation that is optimized from an energy point of view," says Björn Söderlund.

Joakim Wallbing at Optimation worked a lot on the project and he was the one who developed the simulator for the new automatic control.

"Since we were able to control the torque of each pump separately, it became like opening one valve at a time," says Joakim Wallbing. "The control system is now in normal operation, works automatically and provide an energy efficient pumping of feed water."

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