Chemical washing of boilers: description of available means and rules of execution. Washing boilers and heat exchangers: technology, chemicals

RUSSIAN JOINT STOCK COMPANY
ENERGY AND ELECTRIFICATION
"UES OF RUSSIA"

DEPARTMENT OF SCIENCE AND TECHNOLOGY

STANDARD INSTRUCTIONS
ON PERFORMANCE CHEMICALS
CLEANING WATER BOILERS

RD 34.37.402-96

ORGRES

Moscow 1997

DevelopedJSC Firm ORGRES

PerformersV.P. SEREBRYAKOV, A.YU. BULAVKO (JSC Firm ORGRES), S.F. SOLOVIEV(JSC Rostenergo), HELL. EFREMOV, N.I. SHADRINA(OJSC "Kotloochistka")

ApprovedDepartment of Science and Technology of RAO "UES of Russia" 01/04/96

Boss A.P. BERSENEV

STANDARD INSTRUCTIONS PERFORMANCE CHEMICAL CLEANING WATER BOILERS

RD 34.37.402-96

Expiration date set

from 01.10.97

INTRODUCTION

1. Standard instructions(hereinafter referred to as the Instructions) is intended for personnel of design, installation, commissioning and operating organizations and is the basis for designing schemes and selecting technology for cleaning hot water boilers at specific sites and drawing up local work instructions (programs).

2. The instructions are based on the experience of conducting operational chemical cleaning of hot water boilers, accumulated in last years their operation, and determines general order and conditions for the preparation and conduct of operational chemical cleaning of hot water boilers.

The Instructions take into account the requirements of the following regulatory and technical documents:

Rules for the technical operation of electrical stations and networks of the Russian Federation (M.: SPO ORGRES, 1996);

Standard instructions for operational chemical cleaning of hot water boilers (M.: SPO Soyuztekhenergo, 1980);

Instructions for analytical control during chemical cleaning of thermal power equipment (M.: SPO Soyuztekhenergo, 1982);

Guidelines for water treatment and water chemistry regime of water heating equipment and heating networks: RD 34.37.506-88 (M.: Rotaprint VTI, 1988);

Consumption standards for reagents for pre-start and operational chemical cleaning of thermal power equipment of power plants:HP 34-70-068-83(M.: SPO Soyuztekhenergo, 1985);

Guidelines for the use of calcium hydroxide for the conservation of thermal power and other industrial equipment at the facilities of the USSR Ministry of Energy (M.: SPO Soyuztekhenergo, 1989).

3. During preparation and conduct chemical cleaning Boilers should also comply with the documentation requirements of the equipment manufacturers involved in the cleaning scheme.

4. With release of this Instruction The “Standard Instructions for Operational Chemical Cleaning of Hot Water Boilers” (Moscow: SPO Soyuztekhenergo, 1980) is no longer valid.

1. GENERAL PROVISIONS

1.1. During the operation of hot water boilers at internal surfaces deposits form in the water path. If the regulated water regime is observed, the deposits consist mainly of iron oxides. In case of violations of the water regime and use for recharging networks poor quality water or blowdown water from power boilers, deposits may also contain (in amounts from 5% to 20%) hardness salts (carbonates), compounds of silicon, copper, and phosphates.

If the water and combustion regimes are observed, deposits are evenly distributed along the perimeter and height of the screen pipes. A slight increase in them can be observed in the burner area, and a decrease in the hearth area. With a uniform distribution of heat flows, the amount of deposits per separate pipes The screens are basically about the same. On pipes of convective surfaces, deposits are also generally evenly distributed around the perimeter of the pipes, and their quantity is, as a rule, less than on pipes of screens. However, unlike convective surfaces on individual pipes, the difference in the amount of deposits can be significant.

1.2. Determination of the amount of deposits formed on heating surfaces during boiler operation is carried out after each heating season. To do this, pipe samples with a length of at least 0.5 m are cut from various sections of the heating surfaces. The number of these samples should be sufficient (but not less than 5 - 6 pieces) to assess the actual contamination of the heating surfaces. It is mandatory to cut samples from the screen pipes in the area of ​​the burners, from the top row of the upper convective package and the bottom row of the lower convective package. The need to cut an additional number of samples is specified in each individual case, depending on the operating conditions of the boiler. Determination of the specific amount of deposits (g/m2) can be carried out in three ways: by the weight loss of the sample after etching it in an inhibited acid solution, by the weight loss after cathodic etching and by weighing the deposits removed mechanically. The most accurate method listed is cathodic etching.

The chemical composition is determined from an average sample of deposits removed from the sample surface mechanically, or from a solution after etching the samples.

1.3. Operational chemical cleaning is designed to remove deposits formed from the inner surface of pipes. It should be carried out when the contamination of the heating surfaces of the boiler is 800 - 1000 g/m2 or more or when the hydraulic resistance of the boiler increases by 1.5 times compared to the hydraulic resistance of a clean boiler.

The decision on the need for chemical cleaning is made by a commission chaired by the chief engineer of the power plant (head of the heating boiler room) based on the results of analyzes of the specific contamination of heating surfaces, determining the condition of the pipe metal, taking into account boiler operation data.

Chemical cleaning is usually carried out in summer period when the heating season is over. In exceptional cases, it can be performed with winter if it is violated safe work boiler

1.4. Chemical cleaning must be carried out using a special installation, including equipment and pipelines ensuring the preparation of flushing and passivating solutions, their pumping through the boiler path, as well as the collection and neutralization of waste solutions. Such an installation must be carried out according to the design and linked with general plant equipment and schemes for neutralization and neutralization of power plant waste solutions.

2. REQUIREMENTS TECHNOLOGY AND CLEANING SCHEME

2.1. Cleaning solutions must provide high-quality cleaning surfaces, taking into account the composition and amount of deposits present in the boiler screen pipes and to be removed.

2.2. It is necessary to evaluate the corrosion damage to the pipe metal of the heating surfaces and select cleaning conditions with a washing solution with the addition of effective inhibitors to reduce pipe metal corrosion during cleaning to acceptable values ​​and limit the occurrence of leaks during chemical cleaning of the boiler.

2.3. The cleaning scheme must ensure the efficiency of cleaning heating surfaces and the complete removal of solutions, sludge and suspended matter from the boiler. Cleaning of boilers using a circulation scheme should be carried out at speeds of movement of the washing solution and water that ensure the specified conditions. In this case, the design features of the boiler, the location of convective packets in the boiler water path and the presence of large quantity horizontal pipes small diameter with multiple bends of 90 and 180°.

2.4. It is necessary to neutralize the remaining acid solutions and post-wash passivation of the heating surfaces of the boiler to protect against corrosion during boiler downtime from 15 to 30 days or subsequent conservation of the boiler.

2.5. At When choosing a technology and treatment scheme, environmental requirements must be taken into account and installations and equipment for neutralization and decontamination of waste solutions must be provided.

2.6. All technological operations should be carried out, as a rule, by pumping cleaning solutions through the boiler water path along closed loop. The speed of movement of washing solutions when cleaning hot water boilers must be at least 0.1 m/s, which is acceptable, as it ensures uniform distribution of the washing reagent in the pipes of the heating surfaces and a constant supply of fresh solution to the surface of the pipes. Water washes must be carried out at discharge speeds of at least 1.0 - 1.5 m/s.

2.7. Spent washing solutions and the first portions of water during water washing should be sent to the plant-wide neutralization and decontamination unit. Water is drained into these installations until a pH value of 6.5 - 8.5 is reached at the boiler outlet.

2.8. When performing all technological operations (with the exception of final water washing with network water according to the standard scheme), process water is used. Acceptable use network water for all operations, if possible.

3. SELECTION OF CLEANING TECHNOLOGY

3.1. For all types of deposits found in hot water boilers, you can use hydrochloric or sulfuric acid, sulfuric acid with ammonium hydrofluoride, sulfamic acid, low molecular weight acid concentrate (LMAC) as a washing reagent.

The choice of cleaning solution is made depending on the degree of contamination of the boiler heating surfaces to be cleaned, the nature and composition of deposits. To develop a technological cleaning regime, samples of pipes cut from the boiler with deposits are treated in laboratory conditions with the selected solution while maintaining optimal performance of the cleaning solution.

3.2. Hydrochloric acid is mainly used as a cleaning agent. This is explained by its high cleaning properties, which make it possible to clean heating surfaces from any type of deposits, even with high specific contamination, as well as the non-scarcity of the reagent.

Depending on the amount of deposits, cleaning is carried out in one (for contamination up to 1500 g/m2) or in two stages (for greater contamination) with a solution with a concentration of 4 to 7%.

3.3. Sulfuric acid used to clean heating surfaces from iron oxide deposits with a calcium content of no more than 10%. In this case, the concentration of sulfuric acid, in order to ensure its reliable inhibition during solution circulation in the cleaning circuit, should be no more than 5%. When the amount of deposits is less than 1000 g/m2, one stage of acid treatment is sufficient; for contamination up to 1500 g/m2, two stages are required.

When cleaning is only carried out vertical pipes(heating screen surfaces), it is permissible to use the etching method (without circulation) with a sulfuric acid solution with a concentration of up to 10%. When the amount of deposits is up to 1000 g/m2, one acid stage is required, with greater contamination - two stages.

As a washing solution for removing iron oxide (in which calcium is less than 10%) deposits in an amount of no more than 800 - 1000 g/m2, we can also recommend a mixture of a dilute solution of sulfuric acid (concentration less than 2%) with ammonium hydrofluoride (of the same concentration). the mixture is characterized by an increased rate of deposit dissolution compared to sulfuric acid. A feature of this cleaning method is the need to periodically add sulfuric acid to maintain the pH of the solution at an optimal level of 3.0 - 3.5 and to prevent the formation of Fe hydroxide compounds ( III).

The disadvantages of methods using sulfuric acid include the formation of a large amount of suspension in the cleaning solution during the cleaning process and a lower rate of dissolution of deposits compared to hydrochloric acid.

3.4. If heating surfaces are contaminated with carbonate-iron oxide deposits in amounts up to 1000 g/m2, sulfamic acid or NMC concentrate can be used in two stages.

3.5. When using all acids, it is necessary to introduce corrosion inhibitors into the solution, protecting the metal of the boiler from corrosion under the conditions of use of this acid (acid concentration, solution temperature, presence of movement of the washing solution).

For chemical cleaning, as a rule, inhibited hydrochloric acid is used, into which one of the corrosion inhibitors PB-5, KI-1, B -1 (B-2). When preparing a washing solution of this acid, the inhibitor urotropine or KI-1 must be additionally introduced.

For solutions of sulfuric and sulfamic acids, ammonium hydrofluoride, and MNC concentrate, mixtures of catapine or catamine AB with thiourea or thiuram or captax are used.

3.6. If the contamination is above 1500 g/m2 or if there is more than 10% silicic acid or sulfates in the deposits, it is recommended to carry out alkalization before acid treatment or between acid stages. Alkalinization is usually carried out between acid stages with a solution of sodium hydroxide or a mixture of it with soda ash. Adding 1 - 2% soda ash to caustic soda increases the effect of loosening and removing sulfate deposits.

If there are deposits in the amount of 3000 - 4000 g/m2, cleaning heating surfaces may require sequential alternation of several acid and alkaline treatments.

To intensify the removal of solid iron oxide deposits, which are located in the lower layer, and if there are more than 8 - 10% silicon compounds in the deposits, it is advisable to add fluorine-containing reagents (fluoride, ammonium or sodium hydrofluoride) to the acid solution, added to the acid solution after 3 - 4 hours after the start of processing.

In all these cases, preference should be given to hydrochloric acid.

3.7. For post-flush passivation of the boiler, in cases where it is necessary, one of the following treatments is used:

a) treatment of cleaned heating surfaces with 0.3 - 0.5% sodium silicate solution at a solution temperature of 50 - 60 ° C for 3 - 4 hours with solution circulation, which will provide protection against corrosion of boiler surfaces after draining the solution in humid conditions in for 20 - 25 days and in a dry atmosphere for 30 - 40 days;

b) treatment with a solution of calcium hydroxide in accordance with the guidelines for its use for the preservation of boilers.

4. CLEANING SCHEME

4.1. The chemical cleaning scheme for a hot water boiler includes the following elements:

boiler to be cleaned;

a tank intended for the preparation of cleaning solutions and simultaneously serving as an intermediate container when organizing the circulation of cleaning solutions in a closed circuit;

a flushing pump for mixing solutions in the tank along the recirculation line, supplying the solution to the boiler and maintaining the required flow rate when pumping the solution through a closed circuit, as well as for pumping the spent solution from the tank to the neutralization and neutralization unit;

pipelines connecting the tank, pump, boiler into a single cleaning circuit and ensuring pumping of solution (water) through closed and open circuits;

neutralization and neutralization unit, where used cleaning solutions and contaminated water are collected for neutralization and subsequent neutralization;

hydraulic ash removal channels (GZU) or industrial storm drainage channels (PLC), where they are allocated conditionally clear waters(with pH 6.5 - 8.5) when cleaning the boiler from suspended substances;

tanks for storing liquid reagents (primarily hydrochloric or sulfuric acid) with pumps for supplying these reagents to the cleaning circuit.

4.2. The flushing tank is intended for preparing and heating cleaning solutions; it is a averaging tank and a place for removing gas from the solution in the circulation circuit during cleaning. The tank must have an anti-corrosion coating and must be equipped with a loading hatch with a mesh with a mesh size of 10´ 10 ÷ 15 ´ 15 mm or with a perforated bottom with holes of the same size, level glass, thermometer sleeve, overflow and drainage pipelines. The tank must have a fence, a ladder, a device for lifting bulk reagents, and lighting. Pipelines for supplying liquid reagents, steam, and water must be connected to the tank. Heating of solutions with steam is carried out through a bubbling device located in the lower part of the tank. It is advisable to put it in the tank hot water from the heating network (from the return line). Process water can be supplied both to the tank and to the suction manifold of the pumps.

The capacity of the tank must be at least 1/3 of the volume of the flushing circuit. When determining this value, it is necessary to take into account the capacity of the network water pipelines included in the cleaning circuit, or those that will be filled during this operation. As practice shows, for boilers with a thermal productivity of 100 - 180 Gcal/h, the tank volume must be at least 40 - 60 m 3.

To ensure uniform distribution and facilitate the dissolution of bulk reagents, it is advisable to run a 50 mm diameter pipeline with a rubber hose from the recirculation pipeline inserted into the tank for mixing solutions into the loading hatch.

4.3. A pump designed to pump the cleaning solution through the cleaning circuit must provide a movement speed of at least 0.1 m/s in the pipes of the heating surfaces. The selection of this pump is made according to the formula

Q= (0.15 ÷ 0.2) S 3600,

Where Q- pump flow, m 3 / h;

0.15 ÷ 0.2 - minimum solution speed, m/s;

S- area of ​​maximum cross section boiler water path, m2;

3600 - conversion factor.

For chemical cleaning of water heating boilers with a thermal output of up to 100 Gcal/h, pumps with a flow rate of 350 - 400 m 3 /h can be used, and for cleaning boilers with a thermal output of 180 Gcal/h - 600 - 700 m 3 /h. The pressure of the flushing pumps must be no less than the hydraulic resistance of the flushing circuit at a speed of 0.15 - 0.2 m/s. For most boilers, this speed corresponds to a pressure of no higher than 60 m of water. Art. To pump washing solutions, two pumps are installed, designed for pumping acids and alkalis.

4.4. Pipelines intended for organizing the pumping of cleaning solutions through a closed circuit must have diameters no less than the diameters of the suction and pressure pipes of the flushing pumps, respectively; pipelines for discharging spent washing solutions from the cleaning circuit to the neutralizer tank can have diameters significantly smaller than the diameters of the main pressure-return pipes ( waste) collectors.

The cleaning circuit must be capable of draining all or most of the cleaning solution into the tank.

The diameter of the pipeline intended for drainage of wash water into the industrial storm canal or gas treatment system must take into account the throughput of these pipelines. The boiler cleaning circuit pipelines must be stationary. Their routing must be chosen in such a way that they do not interfere with the maintenance of the main equipment of the boiler during operation. The fittings on these pipelines must be located in accessible places, and the routing of the pipelines must ensure their emptying. If there are several boilers at a power plant (heating boiler house), common pressure-return (discharge) manifolds are installed, to which pipelines are connected, intended for cleaning a separate boiler. Shut-off valves must be installed on these pipelines.

4.5. The collection of cleaning solutions coming from the tank (via the overflow line, drain line), from sampler troughs, from pump leaks through seals, etc., should be carried out in a pit, from where they are sent to the neutralization unit by a special pump.

4.6. When carrying out acid treatments, fistulas often form in the heating surfaces of the boiler and in the pipelines of the flushing circuit. A violation of the density of the cleaning circuit can occur at the beginning of the acid stage, and the amount of loss of the cleaning solution will not allow further execution of the operation. To speed up the emptying of the defective area of ​​the boiler heating surface and subsequent safe repair work to eliminate leaks, it is advisable to top part supply nitrogen to the boiler or compressed air. For most boilers, a convenient connection point is the boiler vents.

4.7. The direction of movement of the acid solution in the boiler circuit must take into account the location of the convective surfaces. It is advisable to organize the direction of movement of the solution in these surfaces from top to bottom, which will facilitate the removal of exfoliated sediment particles from these boiler elements.

4.8. The direction of movement of the washing solution in the screen pipes can be any, since with an upward flow at a speed of 0.1 - 0.3 m/s, tiny suspended particles will pass into the solution, which at these speeds will not settle in the coils of convective surfaces when moving from above down. Large sediment particles, for which the movement speed is less than the soaring speed, will accumulate in the lower collectors of the screen panels, so their removal from there must be done by intensive water washing at a water speed of at least 1 m/s.

For boilers in which convective surfaces are the outlet sections of the water path, it is advisable to organize the flow direction so that they are the first in the direction of movement of the washing solution when pumping along a closed circuit.

The cleaning circuit should have the ability to change the direction of flow to the opposite, for which a jumper must be provided between the pressure and discharge pipelines.

Ensuring the speed of movement of the cleaning water above 1 m/s can be achieved by connecting the boiler to the heating mains, and the circuit should provide for pumping water through a closed circuit with constant removal of cleaning water from the boiler circuit while simultaneously supplying water to it. The amount of water supplied to the purification circuit must correspond bandwidth discharge channel.

In order to constantly remove gases from individual sections of the water path, the boiler air vents are combined and discharged into a flushing tank.

The connection of the pressure-return (discharge) pipelines to the water path should be made as close as possible to the boiler. To clean sections of the network water pipeline between the sectional valve and the boiler, it is advisable to use the bypass line of this valve. In this case, the pressure in the water path should be less than in the network water pipeline. In some cases, this line can serve as an additional source of water entering the cleaning circuit.

4.9. To increase the reliability of the cleaning circuit and greater safety during its maintenance, it should be equipped with steel reinforcement. In order to exclude the flow of solutions (water) from the pressure pipeline to the return pipeline through the jumper between them, to pass them into the discharge channel or neutralizer tank, and to be able to install a plug if necessary, the fittings on these pipelines, as well as on the recirculation line to the tank, must be flanged. The principle (general) diagram of the installation for chemical cleaning of boilers is shown in Fig. .

4.10. When chemically cleaning PTVM-30 and PTVM-50 boilers (Fig. , ), the flow area of ​​the water path when using pumps with a flow rate of 350 - 400 m 3 / h ensures a solution movement speed of about 0.3 m/s. The sequence of passage of the cleaning solution through the heating surfaces may coincide with the movement of network water.

When cleaning the PTVM-30 boiler Special attention it is necessary to pay attention to the organization of gas removal from the upper collectors of the screen panels, since the direction of movement of the solution has multiple changes.

For the PTVM-50 boiler, it is advisable to supply the cleaning solution into the direct network water pipeline, which will allow organizing the direction of its movement in the convective package from top to bottom.

4.11. When chemically cleaning the KVGM-100 boiler (Fig.), the supply and return pipelines for cleaning solutions are connected to the return and direct network water pipelines. The movement of the medium is carried out in the following sequence: front screen - two side screens - intermediate screen - two convective beams - two side screens - rear screen. When passing through the water path, the washing flow repeatedly changes the direction of movement of the medium. Therefore, when cleaning this boiler, special attention should be paid to organizing the constant removal of gases from the upper screen surfaces.

4.12. When chemically cleaning a PTVM-100 boiler (Fig.), the movement of the medium is organized either according to a two- or four-pass scheme. When using a two-pass scheme, the speed of the medium will be about 0.1 - 0.15 m/s when using pumps with a flow rate of about 250 m 3 /h. When organizing a two-way movement pattern, the supply and discharge pipelines for the cleaning solution are connected to the return and direct network water pipelines.

When using a four-pass scheme, the speed of movement of the medium when using pumps of the same flow rate is doubled. The connection of the supply and discharge pipelines of the cleaning solution is organized into bypass pipelines from the front and rear screens. Setting up a four-way circuit requires installing a plug on one of these pipelines.

Rice. 1. Installation diagram for chemical cleaning of the boiler:

1 - flushing tank; 2 - flushing pumps ;

Rice. 2. Scheme for chemical cleaning of the PTVM-30 boiler:

1 - rear additional screens; 2 - convective beam; 3 - side screen of the convective shaft; 4 - side screen; 5 - front screens; 6 - rear screens;

Valve closed

Rice. 3. Scheme of chemical cleaning of the PTVM-50 boiler :

1 - right side screen; 2 - upper convective beam; 3 - lower convective beam; 4 - rear screen; 5 - left side screen; 6 - front screen;

Valve closed

Rice. 4. Scheme for chemical cleaning of the boiler KVGM-100 (main mode):

1 - front screen; 2 - side screens; 3 - intermediate screen; 4 - side screen; 5 - rear screen; 6 - convective beams;

Valve closed

Rice. 5. Scheme for chemical cleaning of the PTVM-100 boiler:

a - two-way; b - four-way;

1 - left side screen; 2 - rear screen; 3 - convective beam; 4 - right side screen; 5 - front screen;

The movement of the medium when using a two-pass scheme corresponds to the direction of movement of water in the water path of the boiler during its operation. When using a four-pass scheme, the washing solution passes through the heating surfaces in the following sequence: front screen - convective packages of the front screen - side (front) screens - side (rear) screens - convective packages of the rear screen - rear screen.

The direction of movement may be reversed when changing the purpose of temporary pipelines connected to the boiler bypass pipelines.

4.13. When chemically cleaning a PTVM-180 boiler (Fig. , ), the movement of the medium is organized either according to a two- or four-pass scheme. When organizing medium pumping according to a two-pass scheme (see Fig.), the pressure and discharge pipelines are connected to the return and direct network water pipelines. With this scheme, the preferred direction of the medium in convective packets is from top to bottom. To create a movement speed of 0.1 - 0.15 m/s, it is necessary to use a pump with a flow rate of 450 m 3 /h.

When pumping the medium using a four-pass scheme, the use of a pump of this type will provide a movement speed of 0.2 - 0.3 m/s.

The organization of a four-way circuit requires the installation of four plugs on the bypass pipelines from the upper distribution manifold of network water to the two-way and side screens, as shown in Fig. . The connection of the pressure and discharge pipelines in this scheme is carried out to the return network water pipeline and to all four bypass pipes disconnected from the return network water chamber. Considering that the bypass pipes haveD at 250 mm and most of its routing consists of rotary sections; connecting pipelines to organize a four-way circuit requires a lot of labor.

When using a four-pass scheme, the direction of movement of the medium along the heating surfaces is as follows: the right half of the two-light and side screens - the right half of the convective part - the rear screen - the direct network water chamber - the front screen - the left half of the convective part - the left half of the side and two-light screens.

Rice. 6. Scheme for chemical cleaning of the PTVM-180 boiler (two-way scheme):

1 - rear screen; 2 - convective beam; 3 - side screen; 4 - two-light screen; 5 - front screen;

Valve closed

Rice. 7. Scheme for chemical cleaning of the PTVM-180 boiler (four-way scheme):

1 - rear screen; 2- convective beam; 3- side screen; 4 - two-light screen; 5 - front screen ;

4.14. During chemical cleaning of the KVGM-180 boiler (Fig.), the movement of the medium is organized according to a two-pass scheme. The speed of movement of the medium in the heating surfaces at a flow rate of about 500 m 3 /h will be about 0.15 m/s. The pressure and return pipelines are connected to the return and direct network water pipelines (chambers).

The creation of a four-pass flow diagram for the medium in relation to this boiler requires much more modifications than for the PTVM-180 boiler, and therefore its use when performing chemical cleaning is impractical.

Rice. 8. Chemical cleaning scheme for the KVGM-180 boiler:

1 - convective beam; 2 - rear screen; 3 - ceiling screen; 4 - intermediate screen; 5 - front screen;

Valve closed

The direction of movement of the medium in the heating surfaces should be organized taking into account the change in flow direction. During acid and alkaline treatments, it is advisable to direct the movement of the solution in convective packages from bottom to top, since these surfaces will be the first in the circulation circuit along a closed circuit. During water washes, it is advisable to periodically reverse the flow movement in convective packets.

4.15. Cleaning solutions are prepared either in portions in a washing tank and then pumping them into the boiler, or by adding a reagent to the tank while circulating heated water through a closed cleaning circuit. The amount of the prepared solution must correspond to the volume of the cleaning circuit. The amount of solution in the circuit after organizing pumping in a closed circuit should be minimal and determined necessary level For reliable operation pump, which is ensured by maintaining a minimum level in the tank. This allows you to add acid during processing to maintain the required concentration or pH value. Each of the two methods is acceptable for all acid solutions. However, when performing cleaning using a mixture of ammonium hydrofluoride and sulfuric acid, the second method is preferred. It is better to dose sulfuric acid into the cleaning circuit at the top of the tank. Acid injection can be done either plunger pump by supply of 500 - 1000 l/h, or by gravity from a tank installed at a level above the flushing tank. Corrosion inhibitors for cleaning solutions based on hydrochloric or sulfuric acid do not require special conditions for their dissolution. They are loaded into the tank before acid is introduced into it.

The mixture of corrosion inhibitors used for washing solutions of sulfuric and sulfamic acids, a mixture of ammonium hydrofluoride with sulfuric acid and NMC, is prepared in a separate container in small portions and poured into the tank hatch. Installation of a special tank for this purpose is not necessary, since the amount of the prepared inhibitor mixture is small.

5. TECHNOLOGICAL CLEANING MODES

Approximate technological modes used to clean boilers from various deposits, in accordance with Section. are given in table. .

Table 1

	Type and quantity of deposits removed	Technological operation	Composition of the solution	Options technological operation				Note
				Reagent concentration, %	Temperature environment, °C	Duration, h	End Criteria
1. Hydrochloric acid in circulation	No limits	1.1 Water rinsing			20 and above	1 - 2
		1.2. Bucking	NaOH Na 2 CO 3	1,5 - 2 1,5 - 2	80 - 90	8 - 12	By time	The need for an operation is determined when choosing a cleaning technology depending on the amount and composition of deposits
		1.3. Washing process water			20 and above	2 - 3	The pH value of the discharged solution is 7 - 7.5
		1.4. Preparation in the circuit and circulation of the acid solution	Inhibited HCl Urotropine (or KI-1)	4 - 6 (0,1)	60 - 70	6 - 8		When removing carbonate deposits and reducing the acid concentration, periodically add acid to maintain the concentration of 2 - 3%. When removing iron oxide deposits without adding acid
		1.5. Washing with technical water			20 and above	1 - 1,5	Clarification of discharged water	When carrying out two or three acid stages, it is allowed to drain the washing solution by filling the boiler once with water and draining it
		1.6. Re-treatment of the boiler with an acid solution during circulation	Inhibited HCl Urotropine (or KI-1)	3 - 4 (0,1)	60 - 70	4 - 6		Performed when the amount of deposits is more than 1500 g/m2
		1.7. Washing with technical water			20 and above	1 - 1,5	Cleaning water clarification, neutral environment
		1.8. Neutralization during solution circulation	NaOH (or Na 2 CO 3)	2 - 3	50 - 60	2 - 3	By time
		1.9. Drainage of alkaline solution
		1.10. Pre-washing with technical water			20 and above		Clarification of discharged water
		1.11. Final cleaning with network water into the heating network			20-80			Carried out immediately before putting the boiler into operation
2. Sulfuric acid in circulation	<10 % при количестве отложений до 1500 г/м 2	2.1. Water rinsing			20 and above	1 - 2	Clarification of discharged water
		2.2. Filling the boiler with an acid solution and circulating it in the circuit	H2SO4	3 - 5	40 - 50	4 - 6	Stabilization of iron concentration in the circuit, but not more than 6 hours	No additional acid dosage
			KI-1 (or katamin)	0,1 (0,25)
			Thiuram (or thiourea)	0,05 (0,3)
		2.3. Performing the operation according to clause.
		2.4. Re-treatment of the boiler with acid during circulation	H2SO4	2 - 3	40 - 50	3 - 4	Stabilization of iron concentration	Performed when the amount of deposits is more than 1000 g/m 3
			KI-1
			Tiuram	0,05
		2.5. Performing operations according to paragraphs. 1.7 - 1.11
3. Sulfuric acid etching	Same	3.1. Water rinsing			20 and above	1 - 2	Clarification of discharged water
		3.2. Filling boiler screens with solution and etching them	H2SO4	8 - 10	40 - 55	6 - 8	By time	It is possible to use inhibitors: catapina AB 0.25% With thiuram 0.05%. When using less effective inhibitors (1% methenamine or formaldehyde), the temperature should not exceed 45 °C
			KI-1
			Thiuram (or thiourea)	0,05 (0,3)
		3.3. Performing the operation according to clause.
		3.4. Repeated acid treatment	H2SO4	4 - 5	40 - 55	4 - 6	By time	Performed when the amount of deposits is more than 1000 g/m2
			KI-1
			Tiuram	0,05
		3.5. Performing the operation according to clause 1.7
		3.6. Neutralization by filling screens with solution	NaOH (or Na 2 CO 3)	2 - 3	50 - 60	2 - 3	By time
		3.7. Drainage of alkaline solution
		3.8. Performing the operation according to clause 1.10						Filling and draining of the boiler two or three times until a neutral reaction is allowed
		3.9. Performing the operation according to clause 1.11
4. Ammonium hydrofluoride with sulfuric acid in circulation	Iron oxide containing calcium<10 % при количестве отложений не более 1000 г/м 2	4.1. Water rinsing			20 and above	1 - 2	Clarification of discharged water
		4.2. Preparation of the solution in the circuit and its circulation	NH 4 HF 2	1,5 - 2	50 - 60	4 - 6	Stabilization of iron concentration	It is possible to use inhibitors: 0.1% OP-10 (OP-7) with 0.02% captax. When pH increases above 4.3 - 4.4, add sulfuric acid to pH 3 - 3.5
			H 2 SO 4	1,5 - 2
			KI-1
			Thiuram (or captax)	0,05 (0,02)
		4.3. Performing the operation according to clause 1.5
		4.4. Re-treatment with cleaning solution	NH 4 HF 2	1 - 2	50 - 60	4 - 6	Stabilization of iron concentration in the circuit at pH 3.5-4.0
			H2SO4	1 - 2
			KI-1
			Thiuram (or captax)	0,05 (0,02)
		4.5. Performing operations according to paragraphs. 1.7 - 1.11
5. Sulfamic acid in circulation	Carbonate-iron oxide in quantities up to 1000 g/m2	5.1. Water rinsing			20 and above	1 - 2	Clarification of discharged water
		5.2. Filling the circuit with solution and circulating it	Sulfamic acid	3 - 4	70 - 80	4 - 6	Stabilization of hardness or iron concentration in the circuit	No additional dosage of acid. It is advisable to maintain the solution temperature by igniting one burner
			OP-10 (OP-7)
			Captax	0,02
		5.3. Performing the operation according to clause 1.5
		5.4. Repeated acid treatment as in paragraph 5.2
		5.5. Performing operations according to paragraphs. 1.7 - 1.11
6. NMK concentrate during circulation	Carbonate and carbonate-iron oxide deposits in quantities up to 1000 g/m2	6.1. Water flushing			20 and above	1 - 2	Clarification of discharged water
		6.2. Cooking in solution circuit and its circulation	NMC in terms of acetic acid	7 - 10	60 - 80	5 - 7	Stabilization of iron concentration in the circuit	No additional acid dosage
		8.3. Performing the operation according to clause 1.5	OP-10 (OP-7)
		6.4. Repeated acid treatment as in paragraph 6.2 6.5. Performing operations according to paragraphs. 1.7 - 1.11	Captax	0,02

Radiation surface of screens, m 2

Surface of convective packets, m 2

Boiler water volume, m 3

ptvm -30

128,6

PTVM-50

1110

PTVM-100

2960

PTVM-180

5500

kvgm -30

KVGM-50

1223

KVGM-100

2385

KVGM-180

5520

80 - 100

Data on the surface area of ​​pipes to be cleaned and their water volume for the most common boilers are given in table. . The actual volume of the cleaning circuit may differ slightly from that indicated in the table. and depends on the length of the return and direct network water pipelines filled with the cleaning solution.

7.5. Consumption of sulfuric acid to obtain a pH value of 2.8 - 3.0 in mixtures with ammonium hydrofluoride are calculated based on the total concentration of the components at their mass ratio of 1: 1.

From stoichiometric ratios and based on the practice of purification, it has been established that per 1 kg of iron oxides (in terms of F e 2 O 3) about 2 kg of ammonium hydrofluoride and 2 kg of sulfuric acid are consumed. When cleaning with a solution of 1% ammonium hydrofluoride with 1% sulfuric acid, the concentration of dissolved iron (in terms of F e 2 O 3) can reach 8 - 10 g/l.

8. MEASURES IN COMPLIANCE WITH SAFETY RULES

8.1. When preparing and carrying out work on chemical cleaning of hot water boilers, it is necessary to comply with the requirements of the “Safety Rules for the Operation of Thermal Mechanical Equipment of Power Plants and Heating Networks” (M.: SPO ORGRES, 1991).

8.2. Technological operations for chemical cleaning of the boiler begin only after all preparatory work has been completed and repair and installation personnel have been removed from the boiler.

8.3. Before carrying out chemical cleaning, all personnel of the power plant (boiler house) and contracting organizations involved in chemical cleaning undergo safety training when working with chemical reagents with an entry in the training log and signature of those instructed.

8.4. An area is organized around the boiler to be cleaned, the wash tank, pumps, pipelines, and appropriate warning posters are posted.

8.5. Protective handrails are manufactured on the tanks for preparing reagent solutions.

8.6. Good lighting is provided for the boiler being cleaned, pumps, fittings, pipelines, stairs, platforms, sampling points and the duty shift workplace.

8.7. A water supply is organized through hoses to the reagent preparation unit and to the personnel’s place of work to wash off spilled solutions or solutions that spill through leaks.

8.8. Means are provided for neutralizing cleaning solutions in case of a violation of the density of the flushing circuit (soda, bleach, etc.).

8.9. The workplace of the duty shift is provided with a first aid kit with medications necessary for first aid (individual bags, cotton wool, bandages, tourniquet, boric acid solution, acetic acid solution, soda solution, weak solution of potassium permanganate, petroleum jelly, towel).

8.10. Persons not directly involved in chemical cleaning are not allowed to be present in hazardous areas near the equipment being cleaned and the area where washing solutions are discharged.

8.11. Hot work is prohibited near the chemical cleaning site.

8.12. All work on receiving, transferring, draining acids, alkalis, and preparing solutions is carried out in the presence and under the direct supervision of technical managers.

8.13. Personnel directly involved in chemical cleaning work are provided with woolen or canvas suits, rubber boots, rubberized aprons, rubber gloves, goggles, and a respirator.

8.14. Repair work on the boiler and reagent tank is permitted only after thorough ventilation.

Application

CHARACTERISTICS OF REAGENTS USED IN CHEMICAL CLEANING OF WATER BOILERS

1. Hydrochloric acid

Technical hydrochloric acid contains 27 - 32% hydrogen chloride, has a yellowish color and a suffocating odor. Inhibited hydrochloric acid contains 20 - 22% hydrogen chloride and is a yellow to dark brown liquid (depending on the inhibitor introduced). PB-5, V-1, V-2, catapin, KI-1, etc. are used as inhibitors. The inhibitor content in hydrochloric acid is in the range of 0.5 ÷ 1.2%. The dissolution rate of St 3 steel in inhibited hydrochloric acid does not exceed 0.2 g/(m 2 h).

The freezing point of a 7.7% hydrochloric acid solution is minus 10 °C, and a 21.3% solution is minus 60 °C.

Concentrated hydrochloric acid smokes in the air and forms a fog that irritates the upper respiratory tract and the mucous membrane of the eyes. Dilute 3 - 7% hydrochloric acid does not smoke. The maximum permissible concentration (MPC) of acid vapor in the working area is 5 mg/m 3 .

Exposure of the skin to hydrochloric acid can cause severe chemical burns. If hydrochloric acid gets on the skin or in the eyes, it must be immediately washed off with plenty of water, then the affected area of ​​the skin should be treated with a 10% solution of sodium bicarbonate, and the eyes with a 2% solution of sodium bicarbonate and go to a medical center.

Personal protective equipment: coarse wool suit or cotton suit with acid-resistant impregnation, rubber boots, acid-resistant rubber gloves, safety glasses.

Inhibited hydrochloric acid is transported in non-gummed steel railway tanks, tank trucks, and containers. Tanks for long-term storage of inhibited hydrochloric acid must be lined with diabase tiles on acid-resistant silicate putty. The shelf life of inhibited hydrochloric acid in iron containers is no more than one month, after which additional administration of the inhibitor is required.

2. Sulfuric acid

Technical concentrated sulfuric acid has a density of 1.84 g/cm3 and contains about 98% H 2 SO 4 ; It mixes with water in any proportions, releasing a large amount of heat.

When sulfuric acid is heated, sulfuric anhydride vapor is formed, which, when combined with water vapor in the air, forms acid fog.

Sulfuric acid upon contact with the skin causes severe burns, which are very painful and difficult to treat. When inhaling sulfuric acid vapors, the mucous membranes of the upper respiratory tract are irritated and cauterized. Contact of sulfuric acid in the eyes can result in loss of vision.

Personal protective equipment and first aid measures are the same as when working with hydrochloric acid.

Sulfuric acid is transported in steel rail tanks or road tankers and stored in steel containers.

3. Caustic soda

Caustic soda is a white, very hygroscopic substance, highly soluble in water (1070 g/l dissolves at a temperature of 20 °C). Freezing point of a 6.0% solution minus 5° C, 41.8% - 0 °C. Both solid caustic soda and its concentrated solutions cause severe burns. Contact of alkali in the eyes can lead to severe eye diseases and even loss of vision.

If alkali gets on the skin, it is necessary to remove it with dry cotton wool or pieces of cloth and wash the affected area with a 3% solution of acetic acid or a 2% solution of boric acid. If alkali gets into your eyes, rinse them thoroughly with a stream of water, followed by treatment with a 2% solution of boric acid and go to a medical center.

Personal protective equipment: cotton suit, safety glasses, rubberized apron, rubber gloves, rubber boots.

Caustic soda in solid crystalline form is transported and stored in steel drums. Liquid alkali (40%) is transported and stored in steel containers.

4. Concentrate and condensate of low molecular weight acids

Purified NMK condensate is a light yellow liquid with the odor of acetic acid and its homologues and contains at least 65% C 1 - C 4 acids (formic, acetic, propionic, butyric). In water condensate these acids are contained in the range of 15 ÷ 30%.

Purified NMK concentrate is a flammable product with a self-ignition temperature of 425 °C. To extinguish a fire, foam and acid fire extinguishers, sand, and felt should be used.

NMK vapors cause irritation to the mucous membrane of the eyes and respiratory tract. The maximum permissible concentration for vapors of purified NMK concentrate in the working area is 5 mg/m 3 (in terms of acetic acid).

If NMK concentrate and its diluted solutions come into contact with the skin, they cause burns. Personal protective equipment and first aid measures are the same as when working with hydrochloric acid; in addition, a gas mask of grade A should be used.

Uninhibited purified NMK concentrate is supplied in railway tanks and steel barrels with a capacity of 200 to 400 liters, made of high-alloy steels 12Х18Н10Т, 12Х21Н5Т, 08Х22Н6Т or bimetals (St3 + 12Х18Н10Т, St3 + Х17Н13М2Т), and is stored in from the same steel or in containers , made of carbon steel and lined with tiles.

5. Urotropin

Hexamine in its pure form is colorless hygroscopic crystals. The technical product is a white powder, highly soluble in water (31% at a temperature of 12° WITH). Highly flammable. In a solution of hydrochloric acid, it gradually decomposes into ammonium chloride and formaldehyde. The dehydrated pure product is sometimes referred to as dry alcohol. When working with methenamine, strict compliance with fire safety regulations is necessary.

If it comes into contact with the skin, methenamine can cause eczema with severe itching, which quickly disappears after stopping work. Personal protective equipment: safety glasses, rubber gloves.

Hexamine is supplied in paper bags. Must be stored in a dry place.

6. Wetting agents OP-7 and OP-10

They are neutral oily liquids of yellow color, highly soluble in water; When shaken with water, they form a stable foam.

If OP-7 or OP-10 gets on the skin, they must be washed off with a stream of water. Personal protective equipment: safety glasses, rubber gloves, rubberized apron.

Supplied in steel barrels and can be stored outdoors.

7. Captax

Captax is a yellow, bitter powder with an unpleasant odor, practically insoluble in water. Dissolves in alcohol, acetone and alkalis. It is most convenient to dissolve captax in OP-7 or OP-10.

Long-term exposure to captax dust causes headaches, poor sleep, and a bitter feeling in the mouth. Contact with skin can cause dermatitis. Personal protective equipment: respirator, safety glasses, rubberized apron, rubber gloves or silicone protective cream. At the end of work, you must thoroughly wash your hands and body, rinse your mouth, and shake out your overalls.

Captax is supplied in rubber bags with paper and polyethylene liners. Stored in a dry, well-ventilated area.

8. Sulfamic acid

Sulfamic acid is a white crystalline powder, highly soluble in water. When sulfamic acid is dissolved at a temperature of 80 °C and above, it hydrolyzes with the formation of sulfuric acid and the release of a large amount of heat.

Personal protective equipment and first aid measures are the same as when working with hydrochloric acid.

9. Sodium silicate

Sodium silicate is a colorless liquid with strong alkaline properties; contains 31 - 32% SiO 2 and 11 - 12% Na 2 O ; density 1.45 g/cm3. Sometimes called liquid glass.

Personal protective equipment and first aid measures are the same as when working with caustic soda.

It is received and stored in steel containers. In an acidic environment it forms a silicic acid gel.



The boiler works properly as long as it is clean. But during operation, contaminants inevitably appear that disrupt operation, and to remove them, chemical flushing of the boiler is necessary. You can't do it without reagents and equipment. Carbon deposits form on top of the heat exchanger, but this is half the trouble; it can be easily removed mechanically during the next maintenance. But scale and deposits form inside the heat exchanger. Only flushing the boiler with chemicals will remove all this.

Typical gas boiler design

What happens when the boiler gets dirty?

For normal operation of the boiler, the rate of heat exchange between the flame and the coolant (usually water) is important. If an obstacle appears in the form of carbon deposits on top of the heat exchanger, and in the form of scale inside it, then, accordingly, more energy will fly into the pipe, rather than indulge in the good cause of heating the home. Also, scale inside thin tubes reduces the clearance and slows down the movement of liquid.

The general diagnosis for the boiler does not look too confident - “it heats worse.” But this does not reduce the losses and the house does not become warmer.

When it's time to chemically flush the heat exchanger

The fact is that there are no exact dates for chemical cleaning of the inside of the boiler; there are only general recommendations:

• For a water system, flush it every 3 years;
• for antifreeze - once every 2 years;

But often, units that are not washed work tolerably well for 5 to 20 years and do not particularly complain about anything. But only when there is water in the system and there was no serious water exchange.

If there were leaks and there was constant refilling, then not only the radiators were damaged by deposits, but also, first of all, the boiler. Therefore, you need to realistically answer for a specific heating system at home: “Isn’t it time to flush the boiler?”

Elements of boiler equipment can become significantly dirty

Everyone knows that Coca-Cola (from the Coca-Cola company) cleans scale and deposits. (if you don’t trust it, you can conduct an experiment and pour the drink somewhere on the sediment, for example, in the toilet). But citric acid in high concentrations is cheaper and more effective against scale. The same one that is sold in bags in the culinary store, and in which everyone soaks heating elements from electric water heaters.

Home craftsmen can do the same with the inside of the heat exchanger. The tank is closed to the boiler on both sides, the pump is turned on manually periodically, and “in theory” citric acid will eat up all the internal scale in the boiler system in all its nooks and crannies within a day.

Flushing with a booster

Specialists have special equipment for washing boilers in private homes using chemical reagents. The device is called a booster and operates similarly to what is described above.

The booster consists of:

• tank with a supply of reagent;
• a pump that drives this liquid through the boiler and through this tank;
• a heating element, which is necessary to speed up the process, because when heated, chemical reactions can accelerate significantly.

All that remains is to invite a specialist with such a device to clean the boiler with chemicals.

How to clean a boiler

• The boiler is disconnected from the system and connected to the booster via two pipes, “input” and “output”.
• The booster and boiler, combined into a small system, are filled with reagent, and air is removed (the booster is above the boiler).
• The device starts working. A few hours are usually sufficient for highly effective reagents.
• The liquid is drained from this system into special containers and must be sent for disposal.
• A flushing reagent is poured into the system to destroy the acid. The system with the booster is washed again with water.
• After turning off the booster, it is recommended to additionally run water through the heat exchanger from a hose to remove all chemical residues, as they can be aggressive to the heating system.

The washed heat exchanger is reconnected to the heating system.

What is usually used to clean the boiler heat exchanger?

At the household level, concentrated citric acid, which is not too dangerous and aggressive, is more often used for chemical flushing of the boiler. But reactions take a long time (days), and no one gives guarantees of complete success.

Specialists with boosters usually use more complex flushing compounds. Some of them can be dangerous; serious safety precautions are required when flushing the boiler with chemical solutions.

• Substance with adipic acid.
• Reagent based on sulfamic acid. Effective cleaner, but requires rinsing and caution.
• Hydrochloric acid - about labor protection and environmental protection, it is probably unnecessary to remind.

When chemically flushing boilers, special clothing, glasses, and rubber gloves are required.

Where to go for chemical cleaning of boiler equipment

In any area you will find craftsmen with their know-how who will undertake to clean any boiler of anything at a low price. But here it is still recommended to contact a service center that provides warranty (technical) service for this boiler. True, most likely, this procedure will not seem cheap to the owners. But much here is determined by safety and environmental issues, for the solution of which you will have to pay hard-earned money...

Boiler flushing must be done thoroughly and systematically. Using hard water leads to the formation of scale and sediment. If the cleaning procedure is neglected, the boiler may fail ahead of schedule. To understand how pollution occurs, you can imagine an ordinary kettle that heats water several times every day. After some time, scale forms on the walls of the kettle, which leads to slower heating of the water. The same thing happens with the boiler.

Flushing the boiler from scale: consequences of ignoring

Modern mains use ordinary hard water, which quickly leads to the inside of the equipment being covered with scale. Boilers must be cleaned on a regular basis. If cleaning is not done on time. The consequences can be the most unpredictable, but definitely unpleasant.

If the boilers are not flushed from time to time, they will begin to overheat during operation.

The design of the gas boiler is such that the coolant coming from the return line cools the cavities of the heating elements located inside. The coolant cannot effectively cool the elements if they are covered with a thick layer of scale. If the boiler constantly overheats, it will soon stop working altogether.

What will happen if you ignore flushing?

• Scale consists of mineral deposits that do not promote thermal conductivity. Scale causes the water to heat up slowly, which requires significantly more electricity. A thick layer of scale leads to increased gas consumption, which increases the price of using the boiler.
• Scale can lead to boiler failure due to difficult coolant passage. This increases the load on the circulation pump, which leads to its rapid breakdown.

Before flushing the boiler, it is important to pay attention to what kind of liquid flows through the line. The need for frequent flushing will be due to very hard and contaminated water. In order to reduce the frequency of cleaning, it is necessary to use antifreeze - it is important that it is not expired.

Options: how to descale a boiler

If purified water is used in the main line, then flushing the boiler can be done once every four years. Using ordinary running water can lead to damage to the boiler, since such water is too hard. The efficiency of the boiler decreases if cleaning is not carried out for a long time.

The simplest and most effective cleaning method is manual washing - you can do it yourself.

To carry out simple cleaning of the heat exchanger, it is necessary to dismantle the boiler. Cleaning can be done in several ways: mechanical and washing. When dismantling the boiler you need to be careful and careful.

Options for descaling the boiler:

• Mechanical. Allows you to remove plaque and other mechanical particles using a vacuum cleaner, scraper or metal brushes.
• Flushing. The coating of the heat exchanger parts can be soaked in a special solution. This method is good for cleaning boilers with two circuits, as they become dirty very quickly and intensively.

The most effective type of purification is considered to be preliminary water purification. The boiler can be protected from scale formation by installing scale filters. If extraneous sounds are detected in the heating system, it is necessary to check whether mechanical impurities have appeared in the boiler.

How to descale a boiler: washing methods

Impurities clearly negatively affect the operating condition of the boiler. Too hard water always leads to the formation of scale, which can damage the entire system. Typically, users install a mesh filter, which should protect the boiler from scale formation.

The formation of impurities is caused by too much potassium and magnesium in the water, which, during crystallization, settle on the inner walls of the equipment.

Particles formed from water as a result of its heating move through the pipes, causing noise. Usually, equipment that is relatively small in size is installed in houses and apartments. Particles contaminating the system are not drained, which ultimately leads to poor operation of the equipment or its breakdown.

Options for descaling:

• Use of reagent acids. Using strong acids is an effective way to get rid of scale. They easily remove ferrous deposits and carbonate scale.
• To remove silicate scale, it is necessary to use substances that contain a lot of alkali.
• To clean the boiler from scale, you can use a dismountable or non-dismountable cleaning method.

The non-dismountable cleaning method involves the use of reagents, the use of which does not require the process of dismantling the boiler. Most often, the method of this cleaning involves the use of three-component boosters, which perfectly clean boiler equipment. The booster consists of three blocks: a reagent tank, a heating tank and a pump.

Chemical descaling of boilers

The chemical cleaning method, which involves preliminary determination of the composition of the scale and its nature, will help to clean the boiler quickly and effectively. This method is considered the simplest, fastest and most effective. Before cleaning, you need to take a scale sample from different places, and then start determining the average sample.

Chemical cleaning involves cleaning the walls of the boiler by exposing it to acids: hydrochloric, sulfuric or alkalis: soda, sodium, trinatophosphate.

Carbon dioxide promotes the rapid dissolution of carbonate and phosphate deposits. Hydrochloric acid interacts with carbon scale, forming chloride compounds of calcium, magnesium and carbon dioxide, which easily dissolve. Cleaning scale from phosphate and silicate scales is more difficult, but efficiency can be increased by adding fluorine acid to the cleaner.

Types of acids for cleansing:

• Solyanaya;
• Sulfuric;
• Sulfamine;
• Sorrel;
• Lemon.

When choosing acids, it is important to pay attention to their availability, cost, effectiveness and environmental friendliness. You can clean the boiler chemically with your own hands, but you need to be extremely careful. The most popular reagents in the West are those that belong to the class of chemical acids. Chemical cleaning is the most reliable and effective type of descaling if all reagents are selected correctly.

Flushing heating boilers (video)

The presence of a gas boiler means that there are no problems heating water in the house. A problem with a gas boiler and heating can be contamination of the pipes, which has a direct impact on the operation of the boiler. Equipment can be protected from scale only through regular cleaning. The cleaning scheme must be thought out taking into account how contaminated the water in the main is. A chemical anti-scale agent is considered the most effective. Protecting your boiler from contamination means extending its service life for many years to come. You can also make a booster with your own hands for washing boilers.

Timely technical inspection and maintenance of boiler equipment will always contribute to its uninterrupted and stable operation.

One of the important complexes of maintenance work is cleaning and flushing of boilers.

In this article we will describe in detail all the nuances and aspects of performing this type of work.

The essence of the procedure

Internal walls of pipes before and after chemical treatment It is no secret that during the operation of boiler equipment, scale and various types of chemical contaminants settle on the internal surfaces. This in turn complicates the operation of the boiler system.

The scope of work, which includes cleaning and removing unnecessary deposits, is precisely called chemical flushing of the boiler.

It is also worth noting that flushing is a relatively inexpensive cleaning method that results in maximum efficiency. (You can read about cleaning a heating boiler from scale).

Advantages

Chemical flushing of boilers contributes to the following positive aspects:

Such improvements once again confirm that flushing is a truly effective and efficient method of cleaning the boiler system.

Sequence of work

Flushing boiler equipment must occur in a strictly defined order, the main stages of which are the following important points:

In fact, all stages of work do not pose any particular technical difficulties, but for a better understanding it is worth looking in more detail at what devices are used to carry out the entire washing process.

Equipment for cleaning boiler systems

As mentioned above, the entire chemical washing process is carried out using a special device called a booster.

The booster consists of the following elements:

It is worth noting that the booster is a unique device of its kind, which greatly facilitates the flushing of boiler equipment.

Materials used

An important aspect of boiler flushing is the issue of using various acidic substances.

There are the following types of acids that are used to clean boiler equipment:

1. Adipic acid. This substance is diluted with water in a certain proportion and directly fed into the boiler using a booster. Carbon dioxide, when interacting with dirt and scale, dissolves them and then turns them into sediment, which is subsequently washed out under the pressure of technical water. The most optimal option is to use a solution with adipic acid for chemical flushing of domestic heating boilers.
2. Lemon acid. This type of acidic substance greatly simplifies the cleaning of the boiler unit, since it can be added directly to the reagent that circulates in the process water.
3. Sulfamic acid. After circulating this reagent in the boiler equipment, it is necessary to thoroughly rinse the system and then dry it. This type of acid effectively cleans the internal surfaces of steam boilers.
4. Hydrochloric acid. The concentration of the solution of this aggressive substance directly depends on the thickness of the contaminated scale. If the thickness of the deposits is 1 mm, then, accordingly, there should be a 1% solution. In other cases, the concentration of the solution does not increase, and the boiler unit is washed several times. Hydrochloric acid is optimally suited for cleaning waste heat boilers.
5. Gel. This type of substance does not apply to acidic environments, however, it dissolves contaminated petroleum-based substances quite well. The main condition for using the gel substance is thorough flushing of the boiler equipment with technical liquid.

After reviewing the characteristics of chemical reagents for cleaning the boiler, we can conclude: all types of substances used are aggressive, so it is necessary to take precautions when working with them.

Safety regulations

When working with substances for chemical boiler flushing, the following recommendations must be observed:

In this article, we introduced you in detail to all aspects of chemical flushing of boiler equipment. Taking them into account, you can easily cope with dry cleaning of boilers of any modification.

Watch the video in which experts clearly demonstrate proper chemical flushing of the boiler:

Some salts are released from water during the process of heating and evaporation in the boiler and settle on the inner walls of the heating surfaces in the form of dense, difficult to separate scale, which impairs heat transfer through the wall and can cause destruction of the metal as a result of overheating. Other salts precipitate in the volume of boiler water in the form of fine suspended particles, which leads to the appearance of mobile sediment in the boiler, called sludge, which can also cause a boiler failure.

To prevent the formation of chemical elements and scale, it is necessary to thoroughly clean the boiler equipment every 2-4 years:

Saving your business budget

Mechanical cleaning

Order

(including the cost of reagents)

The most common and most economical method of cleaning a boiler, which does not require large expenditures and fully meets all cleaning standards. This method requires stopping the heat exchanger, cooling it, draining the water and partially disassembling it. Mechanical cleaning of the boiler is carried out using the EKR-2 installation and mechanical tools.

Mechanical descaling of boilers is carried out using two types of tools. Hand tools - scrapers, scrapers, metal brushes. Mechanical tools include fixed and split heads driven through a flexible shaft by a two-speed induction motor or air turbine. During mechanical cleaning, first of all, the walls of the drums and collectors are cleaned. For this purpose, special OP (open surface) heads are used.

The OP heads are equipped with cutters mounted on an axle. When rotated by an electric motor or air turbine, the cutters also rotate together with the head, using their teeth to remove scale from the walls to which the head is pressed. OP heads come in one-, two-, three- and four-row types.

Descaling using hand tools is carried out in places that are inaccessible for cleaning with mechanical tools (in the corners of partition joints, near the protruding ends of pipes, etc.).

Cleaning scale with a hammer with sharp ends, the so-called claw, is strictly prohibited, since this damages the metal surface of the drum to a depth of 0.5...1 mm, which favors increased corrosion.

The surface cleaned with a hand or mechanical tool is washed with a stream of water, and then the quality of cleaning is checked. Screen and boiler pipes are cleaned after drums and collectors. For this purpose, other heads are used, which differ from OP heads in that the axes of the cutters are attached to the head on hinges. When the head rotates, these axes, together with the cutters, diverge to the sides due to the action of centrifugal force, are pressed against the wall of the pipe and clean it of scale. These pipe cleaning heads are called swing heads. In all cases, cleaning pipes with cutters is carried out while simultaneously washing the cleaning areas with water. At the same time, the cones are cooled and scale is washed away, which clogs the space between the teeth of the cones. During cleaning, the flexible shaft should not be passed into the pipe below the secured clamp. This is necessary in order to prevent the head from coming out of the lower end of the pipe and breaking the cutters.

Chemical cleaning

Order

(including the cost of reagents)

This cleaning method allows you to clean heat exchange units (boilers of all types, heat exchangers, boilers, coolers, compressor cooling jackets, etc.) from scale without the need to disassemble the unit. It also allows the cleaning solution to penetrate into all hard-to-reach places of the unit, which allows for more thorough cleaning of the heat exchange surfaces.

Individual selection of reagents, as well as solution concentration, washing methods, depending on the physical and chemical qualities of scale and the material of the heat exchange surfaces, allows washing without damaging the units.
The washing scheme is developed individually for each specific unit, depending on the reagents used, technology and degree of contamination. It includes a compensation tank, a chemical pump, pipelines, a connection to the boiler, and pipelines for removing carbon dioxide released during the chemical reaction. Heating of the solution may also be provided, depending on the washing technology.

The technology for chemical cleaning of boiler units requires compliance with strict safety regulations due to the use of acids, alkalis, and other chemical additives in the process. Chemical cleaning is carried out under the guidance of experienced specialists. The washing process is controlled by regular taking of chemical samples of the solution for the presence of active hydrogen ions, mass content of iron and other metals in the solution from which the heating surfaces of the boiler unit are made. A chemical analysis before cleaning is performed to exclude chemical damage to the heat transfer surface.
After chemical washing of boiler units, active reagent residues are neutralized, washed surfaces are passivated, and they are chemically coated with an anti-corrosion layer (phosphating).

Spent solutions are neutralized, brought to sanitary standards and discharged into the sewer. The boiler cleaning reagents we use do not contain heavy metal salts and are biodegradable.

Hydrodynamic cleaning

Order

(including the cost of reagents)

This method of cleaning boiler equipment consists of destroying deposits and simultaneously removing them from the surface being cleaned with high-pressure water jets supplied to the working area from a high-pressure pump through special nozzles, using a high-pressure hydrodynamic unit.

Depending on the type and condition of the equipment being cleaned, the GUVD operator can change the pressure value from 0 to 630 atm and water flow up to 4.5 cubic meters. m per hour, while cleaning occurs without compromising the integrity of the equipment being cleaned, with the greatest efficiency, productivity and quality.

Highly effective in removing any deposits, regardless of their physical properties, chemical composition and spatial location. A more gentle method that does not damage the surfaces of the equipment being processed. During the cleaning process, there is no excess pressure in the container being washed, which eliminates damage to the sealing elements and components of the equipment being processed.

The use of ultra-high pressure systems makes it possible to increase the productivity of cleaning work tens of times and thereby reduce downtime of process equipment, i.e. direct and indirect economic losses. Environmental cleanliness and safety of the technical process are guaranteed. During cleaning, an environmentally friendly working environment (water) is used, which greatly simplifies the disposal of processing waste.

3.1 Hot water boilers (kW)
	mechanical	chemical	hydrodynamic
Low power (Baxi, Feroli, Viessmann, Boderus, Vaillant, Dakon)
50 - 200 kW
St. 200 - 300 kW
St. 300 - 500 kW
Medium power (De Dietrich, ZioSab, Viessmann, Wolf)
St. 0.5 - 0.9 mW
St. 1 - 2.4 mW
St. 2.5 - 5 mW
St. 5 - 10 mW
Industrial (DKVR, DE, E)
1 - 2.4 mW
St. 2.5 - 9 mW
St. 10 - 15 mW
St. 15 - 20 mW
St. 20 - 25 mW
St. 25 - 50 mW
St. 50 - 100 mW
over 100 - 200 mW
3.2 Auxiliary equipment (boilers, heaters, heat exchangers, water economizers, cleaned surface area sq.m.)
	mechanical	chemical	hydrodynamic
up to 10 sq.m.
St. 10 - 25 sq.m.
St. 25 - 50 sq.m.
St. 50 - 75 sq.m.
St. 75 - 100 sq.m.
St. 100 - 200 sq.m.
St. 200 - 350 sq.m.
St. 350 - 500 sq.m.
St. 500 - 1000 sq.m.
St. 1000 - 2500 sq.m.