In addition to periodic automation settings and optimal technical condition, boiler equipment also needs regular maintenance. Preventive maintenance consists in cleaning the surfaces of pipelines and internal cavities of the structure from harmful salts, alkalis and scale. The purge technology of the boiler allows you to effectively cope with such tasks.
Method Overview
The operation of hot water and steam boilers is associated with the accumulation of salt-containing products that adversely affect the condition of the surfaces of the unit, not to mention the quality of the liquid coolant served by it. Equipment with natural circulation of water and steam must be purged to remove harmful deposits in special separator tanks. There are different ways to implement cleaning, but a complete rejection of this preventive measure can lead to wear of the unit to a state of unsuitability. So, in relation to boilers and steam boilers, purging is the removal of a certain volume of water that contains salts, sedimentary elements and sludge from its design and associated piping circuits. Technically, the procedure is performed using plug-in equipment in the form of a pipe located in the drum of the boiler. To regulate the intensity of the process, valves and shutoff valves are additionally connected.
Purge Purge Boilers
Each boiler model has its own schedule for the purge operation, taking into account the operating mode of the equipment and the quality of the water served. Usually, a special line is provided for this operation, connected to the purge line. The procedure is performed sequentially at each contour point of the removal of foreign particles. Due to the small volumes of accumulated water, you should carefully approach the purge of the salt chambers of cyclones.
What effect should the boiler purge provide? Again, a lot depends on the current state of the equipment. With complex blowing, elements such as sludge, ash, salt, soot and scale are removed from the circuits and functional tanks. If they are not removed on time, then over time the risk of burns will increase, which will lead to a decrease in boiler productivity, an increase in fuel consumption, and even pipe rupture.
Purge Types
There are two purge options - continuous and intermittent. In the first case, respectively, the cleaning process is performed non-stop, and in the second, in the short-term mode after certain periods of operation. The technique of continuous removal of unwanted substances is oriented more likely to leaching salts in the boiler water. In turn, periodic blowdown is activated in cases of elimination of more solid settled substances like scale and sludge.
More often, continuous blowing of the steam boiler is used, since it guarantees a higher quality of service for the surfaces of the equipment. Another thing is that with a thorough thorough cleaning, this method cannot be applied. Purging with large gaps is rather regarded as an additional maintenance operation, the purpose of which is to remove local dry sediment accumulations.
Continuous Purge Technique
The procedure can be performed from any part or circuit of the boiler equipment with piping. In particular, you can start with the lower or upper drum capacity, as well as with remote cyclones. The setting point of the connected communications for purging does not matter, since the operation is performed with small resources with a minimum pressure load. The process is organized using a perforated pipe installed in the boiler drum. Next to the control loops are connected valves that adjust the intensity of the water supply. Sometimes a continuous purge of the boiler is organized through the lower exits of the salt chambers with two active small-format valves. The additional installation of restriction washers with valves with a diameter of 3-8 mm on the lower purge line is also recommended.
Permanent purge shutdown
Salt-containing water is already cleaned outside the boiler using a separator. If the planned alkali indicator is normal at a certain operating period, then the purge of the boiler can be set to a minimum degree of operation or completely disabled. After the contaminated liquid is discharged, the valve of the connected pipeline closes, cutting off the line of separated water. Filtered salts and sludge are sent to the drainage circuit.
Periodic purge procedure
This method involves connecting the output circuits only through the lower points of the collectors or drums in order to output the sludge to the separators. Technically, the process of periodic purging of boilers is carried out in the following sequence:
- The sufficiency of fluid in the nutrient deaerator is checked.
- Water-indicating measuring equipment is blown.
- Checks the tightness of the purge valves, the reliability of the shutdown mechanisms of the boiler.
- The water level in the boiler rises by 2/3 by the standards of a pointing device.
- During the purge process, the water is held at a level not lower than the normal working one (middle range).
- The procedure is performed in turn on each node of the collector or boiler drum.
- First, the second valve on the purge line opens completely, and then the first one. Then purge lasts no more than 30 seconds.
- Valves close in reverse order.
- Simultaneous cleaning from the two lower points is not allowed.
- When a water hammer occurs, purge stops. Eliminate the risk of such phenomena using buffer tanks.
Conclusion
Regulation of salt-containing water in the boiler is an important operation, but energy-intensive and demanding for the technical and structural design of the piping. That is, not in every unit it is even theoretically possible. In modern boilers, for example, biochemical decomposition of alkalis is used with the removal of processed products through regular waste discharge channels. The purge of the boiler itself is not only costly in terms of resources, but it can also be harmful to pipeline circuits. This is especially true for continuous cleaning, which constantly creates conditions for contact between the equipment strapping loops and alkaline products. The best solution to the problem of greasing boiler units is the prevention of the dissolution of sediments and sludge elements. This is done in different ways - in particular, by washing the circuits with softened water during stepwise evaporation.