Purge the boiler: order of execution, purpose

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Boiler equipment, in addition to periodic adjustments of automation and maintenance of optimal technical condition, also needs regular maintenance. Preventive maintenance consists in cleaning the surfaces of pipelines and internal cavities of the structure from harmful s alts, alkalis and scale. Boiler purging technology can effectively deal with such tasks.

General information about the method

The process of operation of hot water and steam boilers is associated with the accumulation of s alt-containing products that adversely affect the condition of the surfaces of the unit, not to mention the quality of the liquid coolant it serves. Equipment with natural circulation of water and steam must be purged in order to remove harmful deposits into special separator tanks. There are different ways to implement cleaning, but the complete failure of this preventive measure can lead to the wear of the unit to the point of unusability. So, with regard toIn hot water and steam boilers, blowdown is the removal of a certain volume of water from its structure and associated pipeline circuits, which contains s alts, sedimentary elements and sludge. Technically, the procedure is performed using a plug-in equipment in the form of a pipe located in the boiler drum. To regulate the intensity of the process, valves and stop valves are additionally connected.

Assignment of boiler blowdown

For each model of the boiler, its own schedule for performing the purge operation is prescribed, taking into account the mode of operation of the equipment and the quality of the serviced water. 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 withdrawal of foreign particles. Due to the small volumes of accumulated water, care must be taken when purging the s alt chambers of the cyclones.

What effect should blowing the boiler provide? Again, a lot depends on the current state of the hardware. With complex purge, elements such as sludge, ash, s alt, soot and scale are removed from the circuits and functional tanks. If they are not removed in time, then over time the risk of burnouts will increase, which will lead to a decrease in boiler performance, an increase in fuel consumption and even pipe rupture.

Types of purge

There are two types of purge - continuous and intermittent. In the first case, respectively, the cleaning process is carried out without stopping, and in the second - inshort-term mode after certain periods of operation. The technique of continuous removal of undesirable substances focuses rather on washing out the s alts in the boiler water. In turn, periodic blowing is activated in cases of removing more solid settled substances such as scale and sludge.

Continuous blowdown of the steam boiler is more commonly used as it guarantees better maintenance of equipment surfaces. Another thing is that such a method cannot be applied during a thorough comprehensive cleaning. Blowing at long intervals is rather considered as an additional maintenance operation, the purpose of which is to remove local dry accumulations of sediment.

Continuous blowdown 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. Further, valves are connected to the regulation circuits, which adjust the intensity of the water supply. Sometimes a continuous blowdown of the boiler is organized through the lower outlets of the s alt chambers with two active small-format valves. It is also recommended to additionally install restrictive washers with valves with a diameter of 3-8 mm on the bottom linepurge.

Permanent purge shutdown

S alty water already outside the boiler is cleaned using a separator. If at a certain operational interval the planned alkali indicator is normal, then the boiler blowdown can be set to a minimum degree of work or completely turned off. After the contaminated liquid is removed, the valve of the connected pipeline closes, cutting off the line of separated water. The filtered s alts and sludge are sent to the drainage circuit.

Periodic blowdown procedure

This method involves connecting the output circuits only through the lower points of the collectors or drums in order to remove the sludge to the separators. Technically, the process of periodic blowdown of boilers is performed in the following sequence:

• Checking the adequacy of the liquid supply in the nutrient deaerator.
• Water-indicating measuring equipment is blown.
• Checking the tightness of the purge fittings, the reliability of the boiler shutdown mechanisms.
• The water level in the boiler rises by 2/3 by the standards of the pointing device.
• Water is kept at or above the normal operating level during the blowdown process (medium 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. Next, blowing starts for no more than 30 seconds.
• Valves close in reverse order.
• Simultaneous cleaning from two low points is not allowed.
• When a water hammer occurs, the purge stops. You can eliminate the risk of such phenomena with the help of buffer hydraulic tanks.

Conclusion

Regulation of saline water in the boiler is an important operation, but energy-intensive and demanding on the technical and structural performance of the piping. That is, not in every unit it is even theoretically possible. In modern boilers, for example, means of biochemical decomposition of alkalis are used with the removal of processed products through standard waste disposal channels. By itself, blowing down the boiler is not only costly in terms of resources, but can also be harmful to pipeline circuits. This is especially true for continuous cleaning, which constantly creates conditions for contact between the equipment piping circuits and alkaline products. The optimal solution to the problem of clogging of boiler units is to prevent the dissolution of sediments and sludge elements. This is done in various ways - in particular, by flushing the circuits with softened water during staged evaporation.