Cost-effective operation of steam boilers
PolyComp Energo s.r.o. Podebrady, is an authorised distributor of products manufactured by the GESTRA Company. Professionals, working in power engineering, know GESTRABremen as a renowned supplier of power engineering products, namely steam traps, control valves etc.
Individual units of GESTRA production comply with a German standard for operating boilers without constant supervision in accordance with TRD 604 for 24- or 72-hour intervals. The unit consists of an electrode and a level switch. The design of the electrode is based on the electrical conductivity of the boiler water for level signalling. Emergence of the electrode, i.e. low level, produces a slight negative imbalance of the bridge circuit provided in the level switch. This produces a low level alarm signal and consequent cut-out of the burner circuit. A strong negative imbalance of the bridge circuit, which causes an alarm signal and consequent cut-out of the burner circuit, is provided if the insulating seals placed between the electrodes and the body are no longer tight due to deterioration or chemical breakdown, allowing penetration of liquid into the cavities between the body, tube and stud. They are called " self-testing devices of specific design". The conductivity electrode is a system of elements under periodic electronic testing the level switch. The electronic system controlling the burner's technical conditions evaluates fault states and, in the case of any failure of the electrode, cable wiring or its own electronics, stops the burner's operation as mentioned above.
The GESTRA Company equipment is not supplied as a complete system, but in the form of individual elements combined with the existing boilers' protection devices. Its basic components are the NRG type low-level self-monitoring electrode with periodic self-checking and the NRS type two-channel level switch. Newly installed or repaired boilers may be supplemented with modulated or ON-OFF feed water control of GESTRA production. Individual alternatives of the basic, minimum installation of GESTRA equipment are shown in the pictures below. In order to achieve still higher energy savings, the boilers may be fitted with automatic continuous blowdown (depending on the boiler water conductivity the continuous blowdown is controlled by an electrical control valve) and automatic intermittent blow-down involving a membrane valve which keeps opening and closing for about 2 sec. at a pre-set time interval of 0.5 - 32 hours. Unlike classical continuous blowdown and intermittent blow-down, there are energy savings in the reduced amount of wastewater, and control of blowdown increases the durability of the boiler unit.
The equipment for steam boiler plants operating without constant supervision of steam boilers is provided preferably by the installation of the protection tube in boiler units. Devices for external application, however, may also be used. The installation of GESTRA equipment in hot water systems provides not only hot-water boiler protection, but also protection of the whole hot water system. In addition to a NRG level electrode, the hot-water boiler itself also has to be protected by the installation of temperature and pressure sensors. The hot water system should also be protected by water level electrodes (feedwater and expansion vessels), including pressure sensors. Here the "self-testing device of specific design" has to be applied as well. The above mentioned devices may also be combined with remote transfer of fault states.
Examples:
- Gestra Company products for operating steam-boiler plants without constant supervision in accordance with TRD 604 for 24 hours intervals.
- Gestra Company products for operating hot-water boiler plants without constant supervision in accordance with TRD 604 for 24 hours intervals.