In today’s world of electrical energy, paper mills and box plants still prefer steam to deliver heat energy to their processes. To understand why steam technology remains the most effective process heat source for paper mills, box plants and many other process industries, it’s useful to understand its intrinsic benefits.
Steam Applies Even Heat
Paper mills and corrugated packaging plants use rolls that are internally heated with steam. Maintaining a uniform temperature across the surface of the roll is essential for making quality product. Since steam is a gas, it fills the entire volume of the roll and evenly distributes heat as it condenses.
Steam Temperature is Exact
At a given pressure, saturated steam always has the same temperature. By controlling the pressure, operators can set the exact temperature of the steam inside the roll. For example, at atmospheric pressure, the temperature is always 212° F (100° C). At 150 psig (10 bar) the temperature is always 366° F (185° C). As run rates increase or as heavier paper grades are produced, higher pressures and temperatures are needed. This predictability allows operators to control their process and change temperature as necessary.
Steam Carries Significant Energy
High-speed industrial processes demand a lot of energy. The latent heat in steam is a very efficient way to carry large amounts of energy to the process. At 150 psig (10 bar) saturated steam carries 3.5 times the heat content, or enthalpy, of condensate. This energy is immediately released as steam contacts the inside surface of the roll and condenses.
Steam is Efficient
Most steam systems are powered by high-efficiency natural gas boilers, and natural gas is a relatively inexpensive form of energy in many parts of the world. The steam that is generated operates in an insulated, closed-loop system, and condensate is returned to the boiler for reuse. The steam generation is safely kept separate from the production process, but it’s onsite proximity limits energy loss in steam delivery.
Steam Systems are Optimized
Energy efficiency, product quality, and operating speed are maximized with an efficient steam system. Optimizing steam systems requires extensive systems knowledge. Kadant Johnson offers 90 years of process expertise designing and updating steam systems, while its Services group installs and maintains steam systems and paper dryer section components. In corrugated packaging plants, Kadant Johnson’s Plant Optimization Services team perform audits, training, and NDT testing.