Cleaning boilers from scale is the key to their long-term operation. Scale, its influence on the operation of the heating surface of the boiler

Hot water boilers are successfully operated for hot water supply and heating of production shops, administrative buildings, residential buildings, various utility rooms and outbuildings.

During the operation of the boiler, it is regularly necessary to clean it. Its internal surfaces, which are in direct contact with water or steam, must be clean and free from any deposits. Water contains a lot of various impurities and salts. Under the influence of high temperature during the use of the boiler, a concentration of supersaturated solutions arises, which subsequently settle on the walls in the form of various deposits. The cleaning procedure is necessary to ensure efficient heat exchange. The process of scale and various deposits in boilers is inevitable even when the appearance of condensate is strictly controlled by adding chemicals. Scale and deposits also appear in the presence of high-quality water treatment.

Problems that occur without timely cleaning

Due to deposits on the walls of the boiler, various problems arise:

• The temperature of the pipe walls increases due to a sharp decrease in thermal conductivity. This is due to the fact that, compared to metal, the thermal conductivity of scale and deposits is significantly lower.
• Heat transfer is reduced, which can lead to an increase in the design temperature of the pipe walls, as a result of which the pipe may fail due to creep failure. Efficient heat transfer is determined by the ratio of unit performance to fuel consumption. With a decrease in heat transfer, much more large quantity fuel. For example, a mere millimeter scale layer increases fuel consumption by approximately 5%. If the necessary measures are not taken in time, then the scale layer during long-term operation of the boiler increases to 5-6 mm, which in turn causes excessive fuel consumption up to 20% or more. Thus, there is a significant loss of energy.
• The reliability of operation is lost, the operational properties and characteristics of the boiler are reduced, and there is a risk of corrosion.

If you do not carry out preventive cleaning of the boiler for a long time, then due to the formation of scale, the system becomes clogged, while the correct circulation of the liquid is disturbed in the boiler and heat exchanger. Under such circumstances, for the normal functioning of the boiler installation, it becomes necessary to gradually increase the pressure, which in turn can lead to exceeding certain values ​​\u200b\u200band mechanical damage. Due to the formation of scale, the operation of the boiler subsequently becomes impossible. Indeed, as a result, the unit may fail. In this case, flushing is no longer enough, it becomes necessary to overhaul the boiler. And that means a big financial investment.

Boiler cleaning methods

Flushing of the units is carried out using various technologies. The selected method depends on the design of the equipment, and in some cases combinations of methods are used. When carrying out such work, an individual scheme is drawn up.

Electrohydropulse flushing produced by means of electrohydropulse installations. It is carried out for cleaning both hot water and steam boilers, as well as shell-and-tube heat exchangers.

Hydrodynamic washing lies in the fact that under the influence of high-pressure water jets, various deposits and scale are destroyed and simultaneously removed. Water is supplied to the working area using a special hydrodynamic unit. high pressure(GUVD), equipped with cleaning heads and nozzles. The pressure reaches 2000 bar. In situations where the scale layer is too large or with significant deposits, sand of various fractions is also used. This procedure is called hydro-sandblasting. Hydrodynamic flushing is used for all types of heat exchangers, as well as for cleaning hot water and steam boilers.

Chemical (hydrochemical) cleaning it is applied to any type of heat exchangers and coppers. It is carried out by using modern and traditional reagents. Chemical cleaning is indispensable when it is impossible to use a hydrodynamic installation, for example, for cleaning boilers that are not very productive or are non-separable. In such cases, solutions of organic and inorganic acids are used, which are distinguished by high quality properties that allow washing, dissolving and removing scale, corrosion and other formations and deposits from the boiler plant.

After flushing, the internal surfaces of the flushing equipment and the flushing solution itself are neutralized. Based on this, it becomes clear that this solution becomes neutral, safe, and therefore can be removed directly into the sewer. Passivation of washed systems and all equipment is also carried out. The results of the work carried out are determined by comparing the samples that were cut out before washing, as well as after it was carried out. In addition, they measure hydraulic losses. The installation with which hydrochemical cleaning, consists of a container for a working solution, a set of hoses, a chemical pump and fittings.

Hydromechanical cleaning. This method is carried out using both manual and mechanical special devices of increased hardness. Hand tool represents scrapers, scrapers, brushes with a metal bristle. The mechanical tool is represented by cutters, which are mounted on a flexible shaft and driven by an electric motor or an air turbine. Hydromechanical cleaning consists in the qualitative destruction of various deposits in cases where it is impossible to use aqueous solutions. Also, this cleaning method is also indispensable for removing too hard or insoluble formations on the walls of the pipes of a boiler plant.

Purification Benefits

Cleaning boilers from scale and deposits has a number of undeniable advantages. First of all, one should take into account the fact that during high-quality cleaning, all formations leading to malfunctions are removed completely, to the metal surface. Thanks to this procedure, the likelihood of deposits and scale formation on the internal surface of the units is reduced. After cleaning also increases throughput boilers. Eliminates the need for major repairs for a long time, up to 15 years.

In addition to the above, after flushing, hydraulic losses and fuel consumption decrease in boilers, but efficiency increases significantly. In some cases, the efficiency is 98 percent. Various hard-to-reach places of boiler installations are also cleaned: branched pipes or pipes with a small diameter. During the cleaning of such places, there is no need to dismantle the equipment. Flushing the boiler in quality can be compared with the replacement of components with new elements. Also, high-quality flushing does not lead to equipment wear and can be carried out as needed.

A huge advantage is the fact that cleaning is carried out using materials that are environmentally friendly, so that there is no negative impact on people's health and environment. It is also important that the entire cleaning procedure in various ways is much cheaper than the purchase and subsequent replacement of the components of the boiler plant or the cost of the boiler as a whole.

Cleaning methods

Currently, there are two ways to clean boilers: collapsible and in-place method. Each of these methods includes several various methods flushing. CIP cleaning of the boiler is carried out chemical method However, collapsible flushing can be done either chemically or mechanically.

In-place flushing of the unit today is a mandatory measure carried out on a regular basis. Collapsible cleaning of the boiler is carried out only in special cases, with a high degree of contamination of the boiler, and when the circulation of the heat-transfer fluid in the boiler plant becomes impossible due to scale. That is why the collapsible cleaning method does not refer to preventive, but to repair work, the purpose of which is to eliminate the malfunctions that have led to the inoperability of the boiler.

CIP Boiler Flushing

Today, in-place flushing of boilers is carried out to prevent emergencies, as well as for prevention purposes to ensure the operability of all types of boiler plants. The frequency with which flushing is carried out depends on many nuances. However, two decisive factors are:

• design features of the unit;
• the quality of the water used in the operation of the plant.

Basically, 2-4 years pass between preventive cleanings of the boiler. However, sometimes there is a need for unscheduled cleaning or, conversely, it becomes possible to increase the period between flushes.

CIP cleaning of boilers involves the use of various methods of dealing with deposits and scale. Currently, CIP chemical cleaning of heat exchangers and boilers is the most common. However, sometimes there are situations when hydrodynamic cleaning is allowed, as a regular preventive measure in servicing the unit.

Collapsible cleaning of the boiler

As the name implies, the collapsible cleaning method requires the disassembly and removal of contaminated components from the boiler plant. Means intended for collapsible cleaning of boilers need direct contact with contaminated surfaces, which excludes the possibility of safely washing the boiler without disassembling the unit. Collapsible cleaning of the boiler is most often carried out by a mechanical or chemical method, but maximum efficiency can be achieved with the help of complex cleaning, including those and other methods.

Collapsible mechanical cleaning. This is the simplest and most popular technology for flushing the boiler when it is disassembled. Mechanical cleaning of the unit from scale involves the treatment of metal surfaces using various tools, both manual (for example, metal brushes and scrapers) and mechanical. Usually, both tools are used, depending on the surface to be treated, as well as the availability of places that need cleaning. Often, mechanical cleaning of the boiler ends with flushing running water parts that have been cleaned. However, if necessary, these works can be supplemented with chemical washing of the boiler. Such a measure is resorted to in cases where the scale layer is large to such an extent that it prevents the normal circulation of the coolant and thereby reduces the efficiency of the unit.

Collapsible chemical cleaning. This cleaning method differs significantly from CIP cleaning. When disassembling the boiler, it is much easier to clean all the elements by the chemical method. Parts of the system are removed and immersed in a tank filled with a cleaning solution, which ensures the dissolution of scale within a few hours. After chemical cleaning has been carried out, all parts are washed with running water and re-installed in the system.

Collapsible hydrodynamic cleaning. This process is more complicated due to the fact that it implies the mandatory use of a high-pressure hydrodynamic unit. However, the procedure itself is quite simple: under the influence of a jet of running water, launched under high pressure, scale is removed from contaminated surfaces. This method is environmentally friendly due to the fact that no chemical or toxic substances are involved in the cleaning. The main advantage of this method is the extremely high efficiency. When cleaning surfaces, about 98 percent of contaminants are removed, which is why additional work is not necessary.

Each of the technologies is effective in its own way. VekFort specialists will help you determine the most appropriate cleaning method, as well as ensure maximum efficiency during the work.

A gas boiler is the most popular equipment used by private homeowners who plan to efficiently heat their homes during the cold season. However, the comfort of private housing owners is determined by the serviceability of the functioning heating system, while its flawless operation is possible only if all the working elements of the system are kept in perfect order. Speaking of ideal conditions functioning of the heating gas equipment, it should be noted that all its elements are subject to pollution, which negatively affects the efficiency and duration of its operation. Soot, soot, rust and scale often act as contaminants, which not only reduce the efficiency of heat transfer, but also adversely affect the operation of the device as a whole. How to solve the problem of pollution of gas equipment? Regular inspection, as well as preventive measures, including cleaning of heating boilers, will significantly increase the life of gas equipment, significantly reduce energy consumption and the cost of replacing individual components and elements, reduce the frequency of repair measures and lengthen the time interval between them, and also prevent unwanted emissions into atmosphere of carbon monoxide. Flushing the heat exchangers of gas boilers is the most critical step to ensure the smooth operation of the heating system. How to clean gas equipment, as well as what cleaning method is most appropriate in each case - we will consider in this article.

Functioning of gas boilers: theoretical information

If you study the basic basics of the theory, you can come to the conclusion that the gas heating system operates on the principle of elementary conversion of the energy potential of the burning fuel into the energy of the heat carrier circulating in the heating system, most often this function is performed by water. Despite the fact that the heat exchangers of various heating systems may differ slightly from each other, they are united by a common design and principle of operation: a curved pipe, also called a coil, is a conductor for the coolant (water). During operation, under the action of a flame of burning gas, the coil heats up, and the heat generated on this stage, is transferred to the coolant located in liquid state, which is subsequently fed through pipes and goes to heating radiators. The tube heated by the flame is placed in a system of plates, which contributes to a more uniform heating of the coil to higher temperatures.

Important! Heat exchangers are made of materials with high thermal conductivity, such as copper or its alloys.

In order for the coolant in the heating system to be evenly heated, it is necessary to follow several principles that ensure the efficient functioning of gas boilers:

• It is necessary to carefully monitor the cleanliness of the heat exchanger both inside and outside;
• Keep clean and free of blockages in gas nozzles, which are designed to release gas that heats the heat exchanger and its surrounding plates.

Important! Cleaning double-circuit boiler must be carried out annually before heating season, which will increase the efficiency of its functioning and reduce energy consumption by at least 10-15%. However, practice shows that in the case of using soft tap water, cleaning can be carried out every three years.

Cleaning gas boilers: the relevance of the problem

One of the most common causes failure gas boiler is the fouling of the heat exchanger. Experts believe that constant circulation of distilled water in the system or regular topping up of untreated water can save homeowners the need to clean the boiler without affecting its efficiency. However, some owners of private houses often neglect these rules, filling the system with the usual tap water increased rigidity, which has not undergone additional filtration, which contributes to the contamination of the heat exchanger and the breakdown of gas equipment. However, it should be noted that in the case of a single filling of hard water into the system, the heat exchanger will not be contaminated, but if untreated water, which contains a high salt content, is constantly added to the system, the calcium contained in the water will accumulate on the walls of the heat exchanger. Calcium salts, deposited on the walls of the heat exchanger, contribute to a decrease in the heating capacity of the system, and are also the main cause of heat circulation disturbance with subsequent blockage of pipes. Thus, this process of circulation of hot liquid through pipes with subsequent sedimentation of plaque is similar to the sedimentation of lime on the walls of a kettle, which, with an increase in the thickness of the scale layer, begins to heat up more slowly.

Every homeowner sooner or later asks the question: “What consequences can arise if you neglect or untimely clean gas boilers?”

• Overheating of the heat exchanger. In accordance with the principle of gas boilers, the coolant coming from the return line is designed to cool the internal cavity heating elements. The settling of scale on the walls reduces the cooling efficiency, which contributes to the failure of the heat exchanger;
• Failure of significant parts of the system. Due to the fact that plaque deposited on the walls of pipes reduces their diameter, the maximum load placed on circulation pump, increases, which negatively affects its performance and contributes to its failure;
• Excessive fuel consumption also due to the presence of mineral deposits on the walls of pipes, which are characterized by lower thermal conductivity and therefore more energy is spent on heating water.

How to clean a heat exchanger: basic methods

Due to the fact that do-it-yourself cleaning of a gas boiler can be done in several ways, each of which is characterized by its own advantages and disadvantages, it is necessary to consider the main cleaning methods in order.

Manual cleaning of gas boilers

It is the simplest and, at the same time, effective method cleaning the boiler, feasible at home. Manual cleaning of the boiler can be carried out in two ways and includes:

• Mechanical cleaning of boilers, implying the removal of mechanical particles, including plaque, with a metal brush, scraper or vacuum cleaner;
• flushing, the main stage of which is soaking the elements of the heat exchanger in various active solutions. The use of this method is most appropriate in the case of cleaning a double-circuit boiler, the functional elements and channels of which are most susceptible to contamination.

First of all, it is necessary to carefully study the documentation that came with the heating boiler. Flushing a gas boiler can be carried out in two ways, the first of which involves the complete disassembly of the heating equipment, and the second one omits the use of a special reagent and does not involve the complete disconnection of the equipment from the main system. If you prefer the first option, remember that the heat exchanger is an element that occupies a fairly large space inside the gas boiler and is located directly under the combustion chamber, which greatly complicates access to it. To gain access to the heat exchanger, it is necessary to perform the following manipulations:

• Remove the outer case. To do this in accordance with all safety rules, it is necessary to disconnect the gas supply, as well as turn off the power supply, if such is provided for by the design of the device;
• Disconnect the heat exchanger from the pipes of the heating system;
• Remove heat exchanger mountings.

After you have carried out these manipulations, you can pull the heat exchanger out of the boiler and proceed with the cleaning. In most cases, after removing the heat exchanger fasteners, you will find that the internal cavities of the device are clogged with salt deposits (salts of calcium, sodium, and ferric iron). To clean the elements of the system, you will need metal tools - scrapers, pins, as well as a ruff for cleaning the boiler. When using these tools, it is important to be careful not to damage the heat exchanger wall.

Often experienced craftsmen they resort to soaking the device in the bathroom in a weak solution of some acid (most often it is hydrochloric acid). This leads to a softening of salt deposits, which contributes to their easier removal. After completing this procedure, on the advice of specialists, rinse the internal cavities of the device with water supplied under slight pressure. To make it easier for yourself, attach a hose connected to the plumbing system to the nozzle. By carrying out this event, you will make sure how much dirt will come out of the hole. Pressure flushing should be carried out until no water comes out of the holes. pure water. To increase the efficiency of flushing, you can use a rubber or wooden hammer, which you need to tap on the heat exchanger while flushing the internal cavities.

Chemical cleaning of boilers: main aspects

Chemical cleaning of boilers, despite the seeming simplicity of execution, is not the easiest task. To carry it out, you need a specialized device - a booster. Despite the fact that cleaning the boiler with your own hands using a booster is considered a simplified version of the dry cleaning of boilers, you need to familiarize yourself with the main nuances of its implementation.

This process is considered simplified, since during its implementation there is no need to remove the heat exchanger and disassemble the heating boiler. To carry out dry cleaning by this method, it is enough to disconnect two pipes, to one of which a hose is connected that injects a chemical solution into the heating system. It is also necessary to connect a hose to the opposite branch pipe, since the spent chemical solution will exit from it. Thus, a circular movement of the reagent will be carried out inside the heat exchanger and booster.

Consider what a booster is and what elements it consists of?

• Reservoir, for pouring a chemical reagent;
• An electric heating element that is not present in all modifications of boosters, however, experts recommend using just such systems. This is due to the fact that the presence of an electric heating element contributes to the heating of the reagent in the system, which, being in a warm form, contributes to a faster and more efficient destruction of mud and salt deposits;
• Pump.

In the process of dry cleaning of gas boiler heat exchangers, all safety rules must be observed, since equipment is washed using strong acids.

To carry out dry cleaning you will need:

• Booster (powerful sediment designed for flushing boilers);
• Boiler cleaning agent;
• Capacity;
• Gloves and mask.

Cleaning of heat exchangers by chemical means is carried out in two stages. First of all, before cleaning the boiler, use shut-off valves to isolate the water inflow into the system. Only by implementing this event, you can proceed to further cleaning. Remove the top protective cover of the boiler. If you want to increase the cleaning efficiency, remove the unit after draining the water from it. The first stage involves cleaning the boiler with a chemical reagent using a booster. Cleaning is carried out due to the circulation of the reagent in the system under powerful pressure. The reagent functions in such a way that under its influence, salt deposits on the inner surface of the heat exchanger soften and lag behind the walls. Cleaning the boiler using chemicals can take from 2 to 6 hours. The second stage is somewhat easier than the first and presents no technological difficulties. It involves the removal of the reagent and the pouring of a substance that neutralizes its residues. Then wait for the unit to dry and install it in place.

Chemical reagents used for cleaning gas boilers:

• Adipic acid- a reagent that is diluted in water, observing a certain concentration, and then pumped into the boiler after it cools down. Under the pressure of carbon dioxide, carbonates are converted into acid salts, soluble in water. In order for them to precipitate, easily washed off with water, it is necessary to reduce the pressure in time;
• Sulfamic acid- by analogy with adipic acid, it is diluted in water and pumped into a cooled boiler under pressure using a pump. After exposure to the reagent, the boiler is thoroughly washed and dried. The interaction of carbonates and internal elements of the gas boiler contributes to the successful cleaning of the walls of the device;
• Boiler cleaning gel- a substance that is not related to acids, but successfully copes with cleaning the inside of a gas boiler from dirt and salt deposits. It contributes to the removal of scale from the metal elements of the boiler and its dissolution, which corresponds to the principle of functioning of any oil products. The cooled boiler is treated with gel and washed thoroughly clean water. The specified substance acts very gently, easily cleaning the structure without damaging its walls.

Important! The disadvantage of dry cleaning is the inability to control the chemical processes of acid interaction not only with scale and salt deposits, but also with metal elements of the boiler that are not subject to contamination. However, this detrimental effect can be avoided by adding inhibitors to the acid, which reduce the negative effect of the acid on metals.

Hydrodynamic cleaning of a gas boiler

It is a method of cleaning gas equipment, during which there is no need to disassemble it. This method is based on pumping water into the system (sometimes with an abrasive filler) and then pressurizing it. Due to the fact that in the process of manipulation the liquid moves at an increased speed, this contributes to the destruction of salt deposits and their subsequent removal to the outside.

Important! The disadvantage of this technique is the possibility of exceeding the critical pressure in the system, which can cause pipe rupture. In this regard, experts do not recommend dynamic cleaning of the gas boiler with their own hands, as it can cause adverse effects on the equipment. To carry out hydrodynamic cleaning, contact specialists who are authorized to work with gas equipment. However, knowledge of the technology for performing work will not hurt you, since, having familiarized yourself with the information provided by us, you will be able to control the work of invited specialists.

Cleaning the boiler from soot: a step-by-step guide

Cleaning a gas boiler involves not only cleaning the chimney, but also cleaning the channels of the gas boiler itself. In case of contamination of the chimney and problems with draft, there is automatic shutdown gas equipment. The accumulation of soot inside the gas equipment does not contribute to the operation of the automation and the shutdown of the boiler, which can cause poisoning of the residents of the house by combustion products. In addition, contaminated equipment does not function properly, and therefore, gas equipment must be cleaned annually, and this is especially true for gas boilers operating year-round.

Disassembly and removal of soot

To remove the parts of the boiler and clean them, you will need the following tools:

• Screwdriver;
• Open-end wrenches (No. 8-17);
• Ruff for cleaning the boiler;
• Brushes (soft and metal);
• Rags.

Thus, any materials and tools will come into play, using which you can remove limescale from metal surface, and you will also need wrenches.

If you follow the guide suggested in this article, you can not only effectively clean the internal parts of the gas boiler from soot and soot, but also prevent smoke in the room or an accident.

Walkthrough:

First of all, you need to turn off the gas. Then remove the boiler door and disconnect the wire that leads to the piezoelectric element. Unscrew the elements one by one, observing the specified sequence:

• First unscrew the thermocouple;
• Then - the ignition electrode;
• And finally, the pilot burner tube.

Important! To avoid misconfiguration, note the position of the burner in the nozzle. It is recommended that the gasket under the pilot burner be replaced with a new one. Being careful, they take out the nozzle, copper tube and, finally, the burner, while unscrewing the set of clamps.

Important! Use a #17 wrench to unscrew the copper tube fixing nut, use a #10 wrench to remove the ignition electrode, and prepare a flathead screwdriver to loosen the pilot burner mounting screws.

After you have taken out the thermometer sleeve, remove the boiler cover together with the insulating sheet. Then remove the gas duct, having previously disconnected the terminals from the traction sensor. Clean the swirlers removed from the heat exchanger during disassembly using a brush. Clean the base and outside of the heat exchanger in the same way. Internal channels must be blown out with a vacuum cleaner. To clean the burner, use a brush and brush. As for the flue, it must be wiped from all sides.

Important! Particular attention must be paid to cleaning the nozzle, the outer surface of which is cleaned with a brush, and the hole is cleaned with a thin needle, the diameter of which is somewhat smaller than the diameter of the hole. If you do not clean carefully or choose the wrong needle, you can expand the hole, which will disrupt the combustion mode.

The internal and external elements of the heat exchanger are cleaned with a hard metal brush. Dust and lime residues that have settled on the surface of the boiler are removed with a vacuum cleaner and a damp cloth. To clean any form of internal surfaces from plaque, use a boiler brush.

How to assemble in reverse order?

The main burner, copper tube and nozzle are returned to their place in the specified sequence. A pilot burner is installed on a new gasket after it has been cleaned with a metal brush. To prevent damage to the ceramic base, when connecting the ignition electrode, refrain from using the key and perform manual manipulations. Also fix the main parts in place. To carry out a control check, use the soaping of the connections. Checking the tightness of the fixation of the burners and copper tubes you will be able to carry out only in the process of turning on the equipment.

Gas boiler cleaning video

Cleaning boilers from scale during operation is important condition their long and trouble-free operation. Indeed, often heating boilers operate either on completely untreated water or on hard water, and it is not possible to carry out. In addition, as a result, the formation on their walls limescale(scale). And if cleaning is not carried out in time, then the scale formed on the heating surfaces of the boilers will lead to a deterioration in heat transfer, a decrease in the efficiency of the equipment and an increase in fuel consumption. thick layer lime deposits formed will cause too much heating of some areas, the appearance of cracks, blowouts, fistulas, and even rupture of pipes in them. Further operation of such heating boilers can lead to an accident and their premature failure.

In addition, it will not be superfluous to know that only one millimeter of scale on internal surfaces boilers will increase energy consumption by almost two percent, since scale conducts heat several tens of times worse than metal.

From the formed scale can be carried out in two ways - chemical and mechanical. The mechanical method is the simplest - in the process of its implementation, cleaning is carried out using special scrapers, chisels, ruffs, steel brushes, cutters on a flexible shaft. The only drawback is that with this method it is not always possible to efficiently clean scale from hard-to-reach places. Wherein mechanical way cleaning requires care and accuracy, since the heating surfaces of the boiler can be easily damaged during careless work.

The most effective and fastest cleaning of boilers from scale is chemical. The essence of this method lies in the use of inorganic and organic acids or other reagents for washing boilers, taking into account chemical composition deposits and scale. Boilers operated for a long time should be chemically cleaned when 15-20 grams of scale is formed per square meter of the inner surface of boilers and pipes. One of the options for chemical and boilers is the use of hydrochloric acid. But at the same time, it should be remembered that such work requires a careful approach and strict adherence to all technologies, therefore only qualified chemists should carry it out. However, chemical boiler descaling is the cheapest, easiest, and most affordable option.

When heating boilers are cleaned from scale with a solution of hydrochloric acid, no harmful compounds are formed on their inner surface, as is sometimes the case when washing with certain types of organic acids, including sulfamic acid, is carried out. To protect the metal parts of boilers from exposure to hydrochloric acid, special corrosion inhibitors are added to the solution, which slow down the reaction. The use of inhibitors is most appropriate in the case when the scale in the boilers has a different thickness.

The technology of cleaning with hydrochloric acid is that it is supplied from the tank using a special pump through the purge pipe to the boiler. After that, it is drained from the boiler through the selection pipe hot water or steam back to the tank. In the process of chemical cleaning of the boiler from scale, hidden surface defects under the scale layer are often found. Therefore, before starting cleaning, it will not be superfluous to check it technical condition. And if you properly perform chemical cleaning, then it is absolutely safe.

Mechanical cleaning of boilers from scale does not begin with the boiler itself, but with those surfaces of the equipment that are easiest to reach. These are collectors and drums, that is, open and accessible areas. To clean these areas, specialized heads are used, on which the OP marking is applied. This is a tool with cutters located on a flexible shaft. When the electric motor is turned on, the flexible shaft starts to move, the rollers begin to rotate, removing scale from the surface of the heating boiler. To capture the largest possible surface, the cutlets are made in several rows.

It is best not to carry out the work yourself, because there is a high probability that, due to the lack of necessary experience, instead of descaling the boiler, you will have to purchase a new boiler. In the article, we will talk about how important timely cleaning of the boiler is. We will also tell you what is traditionally included in such a procedure.

Cleaning methods

Boiler cleaning involves a standard set of separate methods, which includes both mechanical and chemical cleaning. Another possible way out is to pre-clean the boiler from the dirt that may settle on its walls in the future. Since preliminary operations are very expensive, they are now rarely preferred. Regular cleaning of the boiler from the formed scale is enough to prevent the occurrence of possible emergencies. Much more expensive will be the consequences of the lack of timely descaling, when things can end up not just repair work, but also a complete replacement of heating equipment.

Reagent cleaning of boilers from the formed scale

Such cleaning traditionally includes methods that imply surface treatment with chemical reagents (hence the name). Among such reagents, strong acids are currently especially popular, because they cope with such common types of scale as carbonate and ferruginous with great efficiency. Used for cleaning boilers from scale and other solutions. So, silicate scale can be easily removed if you turn to solutions with high alkalinity for help. In any case, it is very important to choose a washing agent on an individual basis, because the choice is influenced by both the nature of the pollutant and the properties of the pollutant.

Varieties of chemical cleaning

An important step in flushing boilers indiscriminately is the supply of a cleaning solution to the system. The booster pump is responsible for this task. It is very important to be able to regulate the system pressure, because this is associated not only with the supply of cleaning solution, but also with an increase in pressure during the reaction between plaque and acid.

In the case of collapsible cleaning, the system is initially dismantled, and dirty parts are placed in a separate container with a solution for several hours. After that, the elements are washed and reassembled into a single whole. Traditionally, chemical cleaning of the described dismantling type is carried out together with mechanical descaling. It is best to refer to such an operation if the scale has become significant.

Physical cleaning methods

If we are talking about cleaning the boiler from scale in the complex, then mechanical cleaning is initially performed, and only then chemical. Among the main disadvantages of the physical method, one can single out the fact that the inner surface of the boiler is subjected to negative impact, therefore, it quickly deteriorates, especially if, by negligence, too sharp tools are picked up. Once the cleaning of the boiler is completed, it is important to thoroughly rinse all removed parts with water and reassemble them correctly.

Hydrodynamic cleaning of the boiler heat exchanger involves the removal of contaminants by means of a high-pressure water jet. This method differs from the mechanical one in that it excludes any kind of damage to parts. Although hydrodynamics is very efficient, it is not used as often due to its high cost.

There are two ways of physical methods for cleaning boilers from scale. Both options require a mandatory analysis of the system, which means that it is extremely important for anyone who is interested in such work to purchase necessary tools and provide complete equipment. Since scale is formed mainly on the surfaces of the boiler from the inside, it is impossible to interact with contaminated areas directly. Since the disassembly of the system is a time-consuming and complex process, the cost of physically cleaning the devices from scale is also high.

The use of materials is allowed only if there is an indexed link to the page with the material.

A.V. Kolosov, Director, Innovations-Euroservice LLC, Elektrostal

During the operation of steam boilers, scale forms on their internal heating surfaces - tubes, collectors and drums, which significantly reduces heat transfer and prevents water heating (Fig. 1). Excessive fuel consumption, depending on the thickness of the scale, can reach very significant values. If 1 mm of scale causes excessive fuel consumption of 2-3%, then 3 mm of scale is already 6-7%.

Currently, there are several most common cleaning methods: mechanical, hydrodynamic, hydrochemical, electric discharge. Below we describe these technologies in more detail.

mechanical cleaning

This type of cleaning is the traditional, cheapest method of cleaning steam boilers. For these purposes, special cutters, brushes, scrapers, rotating nozzles (in case of connection to a pneumatic drive) are used. Mechanical cleaning is used and effective in the presence of deposits of small thickness and strength. One of the major disadvantages mechanical cleaning boilers lies in the fact that when using nozzles with sharp cutting edges or edges, there is an abnormal impact of the nozzle on the metal of the pipe being cleaned, as a result of which local thinning or damage to the pipe wall may occur.

Hydrodynamic cleaning of boilers

In cases where deposits steam boilers have a small thickness, moderate strength, and for the customer the speed of cleaning the boiler is important, hydrodynamic cleaning of the boilers is used with a high-pressure installation.

The equipment for these purposes is a high pressure pump and a water tank connected by hoses. As a rule, the equipment is installed on the basis of a van (Fig. 2.) and has containers of various volumes from 1 to 5 m 3 (Fig. 3). Through the outlet hose and special nozzles, water is supplied to the pipe to be cleaned under high pressure - up to 300 atm. Due to this, the pipe is cleaned with high speed. In this version, the power supply of the equipment is autonomous, through the vehicle's on-board network. The equipment is designed for cleaning steam boilers of any capacity.

There is also a small size high pressure unit, it is convenient for cleaning small boilers (Fig. 4).

Rice. 4. Installation for washing household boilers.

It should be noted that hydrodynamic cleaning is not used in cases where there is no flow section in the pipe or the pipe is clogged with scale of high strength and considerable thickness.

Chemical cleaning of boilers

A very common cleaning method is the chemical cleaning of steam boilers. Its essence is to pump solutions of acids or alkalis through the boiler to be cleaned. Chemical solutions are selected for specific sediment samples obtained from each facility planned for chemical treatment. For these purposes, products based on hydrochloric, sulfuric, orthophosphoric acid are used. At the same time, the composition of the cleaning solution necessarily includes special corrosion inhibitors that prevent chemical corrosion of the tubes of the boiler being cleaned.

The procedure for chemical cleaning of boilers consists of the following steps: inspection of the boiler, production of a control cut, analysis of the chemical composition of scale, selection of a cleaning agent, cleaning the boiler, flushing and neutralizing the boiler, disposal of the cleaning solution.

The average time for chemical cleaning of boilers is 1-2 days for low power boilers, 2-4 days for medium power boilers, 4-8 days for high power boilers. The method of chemical cleaning of boilers does not allow cleaning completely clogged tubes. The cost of boiler cleaning when using this method is the highest, among other methods, due to the use of expensive chemicals.

Electric discharge cleaning of boilers

Electric discharge cleaning is a relatively new method among the existing ones, since the first working electric discharge technologies appeared no earlier than 20 years ago. Let's take a closer look at this type of cleaning.

The essence of the method, in short, is as follows. As a result of electric discharges carried out in the working fluid, high-speed hydroflows, elastic vibrations of high intensity and cavitation formations are formed in it. Electric arc, penetrating into the thickness of the deposits, splits them and crushes them, then high-speed hydroflows carry the deposits out of the cleaned cavity. Due to the combination of these phenomena, cleaning of pipes from scale of almost any strength is achieved.

From the practice of electric discharge cleaning of boilers

Electric discharge equipment consists of a control and protection unit, a capacitor and a step-up transformer (Fig. 5). Since all these elements are electrical equipment, it is necessary to place it on a site isolated from metal structures. If possible, the placement of the equipment should be done in the central part of the upper drum. This is done so that the boiler can be descaled from both sides without moving the equipment.

Rice. 5. Equipment for electric discharge cleaning.

The general principle of boiler cleaning is very simple. The working cable-electrode is fed through the hole for the hatch in the upper drum into each tube. As a rule, convection tubes are placed on one side of the steam boiler in in large numbers. screen pipes are placed on the other side of the boiler. They go in two rows along the central horizontal axis of the upper drum.

To successfully feed the work cable into each tube, plastic plumbing pipes with a diameter of 40 mm are required. Since the length of the boiler drums can be more than 5 meters, pipes of different lengths are used during operation: 0.5, 1, 2 m. There should be two two-meter pipes to ensure the required rigidity when cleaning distant pipes. To plastic tubes lead into the pipes to be cleaned, are used plastic corners of the same diameter, with angles of 30 and 45 degrees (put on each other), or a smooth adapter for 90 O. If possible, two metal plugs can be made in order to fill the boiler with water to the level of the upper screen pipes, as shown in rice. 6.

It is advisable to start cleaning with convection pipes using a 0.5 m long plastic guide pipe. First, two top row from the left and right side drum and one row, which is under water. This cleans several rows into the depth of the drum, as far as the length of the pipe is 0.5 m. After that, a pipe 1 m long is used, then 2 m. After that, a two-meter pipe is built up with smaller pipes. Thus, all convective pipes are cleaned (three rows on the left and right sides of the drum), up to screen pipes (they will be cleaned on the other side) (Fig. 7). Sometimes old boilers of the KRSh-4 type (the predecessors of the DKVR-4) come across, which have only one hatch and pipes, including screen pipes, run along the entire length of the drum. In 2011, our company carried out cleaning of such a boiler. It must be said that descaling this steam boiler required a lot of ingenuity and experimentation, since cleaning a steam boiler with an operator inside the drum is strictly prohibited!

First of all, steam pipelines and separation devices were dismantled from the KRSh-4 steam boiler, since they made it difficult to access the pipes being cleaned. After that, the rows of tubes were marked with chalk, in order not to make a mistake with the choice, since the distant tubes are very difficult to count, they merge if the lighting is insufficient.

Despite the fact that the cleaning of the steam boiler from scale is carried out mainly by one person, he must constantly look for ways to optimize the cleaning process.

The above have been discussed technological aspects cleaning the steam boiler from scale, devices and technology of work. However, the most important aspect is the quality control of the cleaning of the boiler, carried out by means of such human senses as touch and hearing. This is due to the fact that it is not possible to visually control the cleaning process throughout the entire time of work. Of course, the selection of the operating mode of the equipment is carried out visually: three to five lower vertical tubes are cleaned in different modes (frequency and power), water is drained from the boiler to the level of the lower drum and a visual control of the tubes is performed. Thus, it becomes clear which minimal mode work equipment to choose.

It often happens that even a boiler pipe with a diameter of 51 mm is completely clogged with scale, which forms plugs or completely clogged blank areas of different lengths. In these cases, it is necessary to try to break through the cork from above. If this is not possible within, say, 30-60 minutes, then this tube is fixed, its cleaning is carried out later.

After the cleaning of all pipes of the boiler, except for the impassable pipes, is completed, the water is drained, and the sludge is removed from the lower drum.

Completely clogged pipes can be tried to be cleared by supplying a working cable and water from the lower drum as shown in the photo (Fig. 8).

In 2012, the specialists of our company descaled the steam boiler E-1 /0.9. A third of the boiler tubes had no flow area! Part of the completely clogged tubes was cleaned (46 tubes), among them all 25 screen tubes were cleaned through the lower drum. In this case, one specialist manages the working cable, another specialist supplies water to the tubes. The water hose is passed through plastic pipe with two 45° corners.

conclusions

Practice shows that there is no single, optimal technology for cleaning all steam boilers with different scale and deposits! Each cleaning method has its own advantages and disadvantages. Therefore, when choosing a cleaning technology, specialists should take into account many factors: type of boiler, productivity, thickness and strength of deposits, availability and location of resources (water, electricity), climatic conditions on site and others.

Literature

1. V.M. Tarasyuk, Operation of boilers. Practical guide for the boiler room operator, Moscow, ENAS, 2011, p. 118.