Many processes with a heating temperature of around 60 to 90 °C are carried out using instantaneous water heaters, which feed water into hot water tanks. These require both space and constant temperature control in order to compensate for heat radiation. In addition, circulator pumps are often installed. The temperature in a water tank is frequently also controlled by water heaters. When the water tank is empty, another heating period starts; it must finish in order to reach the right temperature. A heating coil only heats up water slowly since this water is not flowing. Hot water mixes with cold water more slowly as if it were actively swirling. The heating process is terminated or cooled either by discarding the tempered water trap or by the heat radiation releasing excess energy into the environment during the waiting period.
Effective use of steam
Steam-powered heat exchanger stations are primarily used for heating temperatures above 100 °C. They utilise the high condensation energy of the steam in order to bring the media to the desired temperature. Since this energy exchange is so high, steam-powered building heating systems which are supposed to reach temperatures of merely 70 to 80 °C rather than 130 °C need to have safety devices. Regulation and control equipment monitors normal operation and its set switching properties guarantee a safe shutdown of the system if limit values are exceeded. Normal operation can then only be resumed subject to an inspection and release.
These safety settings are, of course, taken into account by the Steamaqua heat exchanger station. This compact stainless steel unit (water side 316 L & 316 Ti, steam side 304) has a footprint of just 0.7 m2. The station can be placed anywhere using a forklift or rollers. The system is delivered ready to connect and start up. The nominal temperature is set on the touch panel and hot water is available following a short heating phase after having activated the system.
Safe condensate removal
Steam, introduced via a regulating valve with a cyclone separator, is used for heating. The now dry, perfectly conditioned saturated steam first flows through the safety valve before reaching the spiral heat exchanger. The condensing steam heats up the water on the secondary side and the condensate which builds up is removed quickly and efficiently via a pump steam trap. Effective drainage is especially important for operation at partial loads. This is because, when the target temperature is reached and only a small amount of steam is left in the heat exchanger, the steam condensates and a vacuum is created in the vertical heat exchanger. Even though this condensate reaches the collector thanks to gravity, it still cannot flow freely. This backlog or stall phenomenon causes so-called “flooding” in standard heat exchangers since the heating surface is filled with water. Steamaqua has an integrated PowerTrap, which works either as a steam trap or as a steam operated pump; by removing any condensate which occurs, it guarantees trouble-free operation of the station. The hot condensate is guided via a preheater and cooled. The residual energy is transferred to the inflowing water. This water then flows through the spiral heat exchanger, the corrugated pipes of which ensure turbulent flow and maximise the heat exchange. The steam feed is regulated by the PLC, so that water leaves the heat exchanger at the nominal temperature. It is also possible to start up the station via Modbus TCP and control the nominal temperature in this way.
To avoid unwanted overheating, thermostats and pressure switches are used to monitor both the water temperature and the water pressure. The steam feed is interrupted if limit values are exceeded. The integrated circulation pump cools the heat exchanger by introducing cold water into it from the inlet via a bypass in the counter current, thus protecting the core of the station from thermal stress. This symbiosis of TLV components and expert know-how is why the Steamaqua compact heat exchanger station truly stands out. Not only is the station’s energy balance optimised by the spiral heat exchanger and preheater; in addition, a tailored insulation package helps reduce unwanted heat radiation and simultaneously serves as touch protection against burns.
Short reaction times
The reaction time is short compared to standard hot water systems. Fluctuations in the water circulation intake cause minor differences in the temperature of the hot water. The quick response of the steam-regulated heat exchange station is perfect for controlling the temperature of water circulation systems with or without withdrawal. Even if the hot water is used directly, a constant target temperature is achieved after a short warm-up phase, so that the system is suitable for replacing large water tanks.
An unwanted drop in water temperature during high-load periods – similar to a “cold shower” – is thus prevented.
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