Guidelines for the conservation of thermal power equipment. Equipment conservation act Instructions for conservation of boilers dkvr doc

Hot water boilers KVR.

1. INTRODUCTION

The technical description is a guide for the installation, operation and transportation of the ASK Group of Companies hot water boiler. Contains information about the design of the boiler.

2 . PURPOSE

The water-heating boiler with a heat output of 0.688 Gcal/h is designed to heat water up to 95 0 C, designed for heating systems of residential, industrial and warehouse premises with a total area of ​​up to 8000 m 2 . Simultaneously with the boiler, a heater designed to produce hot water used for domestic and industrial purposes for emissions can be used.

Water tube boiler, creates a natural circulation of water in the heating system, in which you need to have at the top expansion tank, open type. When using a circulation pump that creates pressure up to 6.0 kg/cm 2 , the heating system is closed using a safety valve at the outlet of the boiler.

The boiler is designed for layer combustion of any type of solid fuel (wood, coal, peat). AtIf the boiler is installed in a specially equipped room, with the use of additional devices, it is allowed to burn liquid and gaseous fuels (clarified kerosene, diesel fuel, diesel oil, natural or liquefied gas).

The high degree of softness of the water used creates conditions for long-term operation of the boiler and heating system. FROM outer side the pipe system of the boiler is thermally insulated with mineral wool and sheathed with a casing of steel sheet 2 mm thick.

Installation of a hot water boiler and heating system be carried out in accordance with the heating scheme of the building. To ensure normal circulation in horizontal sections, it is necessary to create a slope of at least 0.01 0 hot water pipelines from highest point, decreasing to heating elements, and the slope of the pipeline return water down to the boiler.

3. TECHNICAL DATA

Basic technical data and parameters of the boiler.

Options	Boiler brand
	KVR-0.2	KVR-0.5	KVR-0.8	KVR-1
Heat output, MW (Gcal/h)	(0,172)	(0,430)	(0,688)	(0,860)
Estimated efficiency, %
water temperature chart, about C	60-95	60-95	60-95	60-95
Working pressure, MPa (kgf/cm 2 )	0,6 (6)	0,6 (6)	0,6 (6)	0,6 (6)
Fuel (coal) consumption, kg/h	39,2
Boiler volume, m 3		10,4	12,4	17,7
Boiler heating surface, m 2

4. COMPOSITION OF THE PRODUCT

The composition of the product includes an all-welded design of the block of the boiler pipe system. The boiler is thermally insulated with mineral wool, lined with a casing, equipped with three doors: a furnace, a blower and an ash pan. Manometers and thermometers, five grates, safety valves.

Installation, brickwork and adjustment works can be carried out at the request of the customer, by the company's mobile team, at the boiler installation site.

By agreement with the customer, the boiler can be equipped with furnace tools and auxiliary equipment

5. DEVICE AND OPERATION OF THE BOILER

5.1 Boiler design

The boiler is a transportable, non-separable block in the form of a furnace and a convective part, installed on an ash pan block (Fig. 1). In the lower part of the boiler there is a collector belt (longitudinal Ø159x5, transverse Ø133x5 mm), to which water cooled in the heating system is supplied through the inlet pipe DN 100. inside lower belt collectors, 5 grate bars with a size of 900x220 mm are laid.

The boiler furnace is a closed volume, shielded by walls made of pipes Ø51x2.5mm.

A door measuring 400x400 mm is installed in the front of the furnace. Under the furnace, in the ash pan, there is a blower with a door measuring 400x400mm and a blowing air inlet window measuring 250x250mm.

The convective part of the boiler is made in the form of descending and ascending gas ducts, each of which has 12 sections. Risers from pipes Ø83x4 mm, convection from pipes Ø51x2.5mm.

Gas ducts of the convective part are separated from the furnace and betweena two-light gas-tight walls (strip 4x30mm). Under the convective block, in the block, there is an ash pan, which has on the left or right side door dimensions 400x400 mm. In the upper part of the boiler there is an upper belt of collectors made of pipes (longitudinal Ø159x5, transverse Ø133x5) with 4 slinging ears. The ceiling of the boiler is shielded with pipes Ø83x4mm, cut into a prefabricated collector Ø133x5mm from which hot water is discharged through a pipe DN100, and then into the heating system of the building.

From the outside, a strip of 4x30 mm is welded between the pipes. The entire pipe system of the boiler is lined with heat-insulating mats made of basalt wool and sheathed with a casing of 2 mm sheet.

Water flows through the shielding walls and elements of the boiler in accordance with the circulation scheme.

5.2 Boiler operation

5.2.1. Flue gases, having reached the top of the furnace, turn 180 about and through the convective part are sent to the gas duct, from where they enter chimney boiler room.

5.2.2. Water enters the boiler through the inlet pipeline. It is possible to install a mixing water pump, which is installed between the direct and return water supply. With the help of a mixing pump, the return temperature of the water entering the boiler rises to 60°C.Water from the boiler is discharged through the outlet pipeline.

5.2.3. The device and operation of instrumentation and A according to the documentation attached to the set.

6. CONTROL AND MEASURING DEVICES

An indicating manometer and a thermometer are installed on the return water pipe.

A manometer is installed on the direct water inlet pipe.

7. LOCATION AND INSTALLATION

7.1. The boiler must be installed in separate rooms that meet the requirements of SNiP 2.01.02-85

7.2 The installation of the boiler must be carried out in accordance with the Rules for the Construction and Safe Operation steam boilers with steam pressure not more than 0.7kgf/cm 2 : hot water boilers and water heaters with a water heating temperature not higher than 115 ° C "and according to the design of the boiler house.

7.3 During installation, make sure that the boiler is installed strictly horizontally to the floor level of the boiler room.

8. TRANSPORT AND STORAGE

8.1. Boilers can be transported by any means of transport in compliance with the measures to ensure their safety.

8.2. The boiler may only be lifted using the lifting eyes provided for this purpose. When lifting and mounting, special care must be taken to avoid falling or shaking the boiler so as not to damage the lining or insulation of the boiler.

The conditions for transportation and storage of boilers must comply with the requirements of group 5 of GOST 15150-69.

8.3. Storage of boilers from 1 to 3 months is considered short-term. Over 3 months - long-term.

8.4. Short-term storage is allowed under the enclosing structures that protect the boiler from precipitation.

8.5. Long-term storage should be carried out in special rooms that must meet the following requirements:

the premises must be dry, ventilated, protect the boiler from precipitation;

positive temperature is maintained in the premises winter time;

the dimensions of the room provide free placement of boilers.

8.6. During storage, the outer surfaces of the boilers must be cleaned of dirt, washed and dried.

8.7. Clean the flues of the boilers from contamination. Drain the water completely. After draining the water, dry the interior of the boiler.

9. START AND STOP THE BOILER

At the same time, in order to avoid the formation of condensate in the heat exchange elements, the initial start-up of the boiler, and its transition from a cold state to a hot one, should be slow. The recommended water heating rate in the boiler should not exceed 1+1.5 °C/min.

When starting the boiler after a short downtime, the boiler load and the water heating temperature can be increased somewhat faster, but not more than 2 °C / min.

If these requirements are violated during the initial start-up of the boiler, condensation may form in the heat exchange elements.

9.1. Stopping the boiler in all cases, with the exception of an emergency stop, must be carried out only with a written order from the administration.

When stopping the boiler, you must:

Stop the fuel supply to the furnace;

Disconnect the boiler from the pipeline after the cessation of combustion in the furnace. If, after disconnecting the boiler from the pipeline, the pressure in the boiler rises, feed the boiler and purge;

Cool down the boiler and drain water from it;

Ventilate the furnace and flue for 10-15 minutes, turn off the pump and blower;

De-energize the voltage shield;

It is forbidden to drain water from the boiler without the order of the person responsible for the good condition and safe operation boiler room. The descent of water must be carried out slowly, the pipe part must be connected to the atmosphere with the help of an air collector and three-way valve pressure gauge.

The procedure for the conservation of a stopped boiler must comply with the instructions in this manual.

For short-term shutdown of the boiler, there is no need to interrupt the water circulation.

Despite the fact that the boiler room has the necessary technological equipment, and all the necessary measures for the preparation of boiler water have been taken, however, during long-term operation, due to the reasons for the lack of proper control by the operating organizations over the operation of water treatment equipment, solid deposits in the form of scale form on the inner walls of the heat exchange elements of the boilers. To remove scale, chemical cleaning of boilers is carried out. Chemical cleaning boilers are produced using alkalis or acids (trisodium phosphateNa 3 PO 4. sodium hydroxide NaOH, hydrochloric acidHCL).

Purification with trisodium phosphate is carried out in the following sequence:
The boiler is disconnected from the heating network, the water pressure in the boiler is reduced to 0.5 atm and injected into the boiler from a special chemical tank. reagents trisodium phosphate at the rate of 1.5 kg per 1 m 3 boiler water, turn on the mixing pump. After 2 hours, part of the boiler water is drained into the drainage and additional trisodium phosphate is added at the rate of 0.75 kg per 1 m 3 boiler water. The mixing pump is turned on again to circulate water in the boiler and the boiler is “boiled” for 5-6 hours, while it is necessary to monitor the temperature and pressure of the water in the boiler, after which the boiler is cooled, the water is drained, the boiler is washed and filled with chemically purified water.

Acidic cleaning of boilers is more effective in removing scale than alkaline cleaning. But since acid washing is classified as hazardous work, it can only be entrusted to organizations licensed for this type of activity.

9.2 Emergency shutdown of the boiler

9.2.1. The boiler must be immediately stopped and switched off by the action of protections, or by personnel in the following cases:

Safety valve failure detection;

If cracks, bulges, gaps in welds are found in the main elements of the boiler;

Reduced water flow through the boiler, below the minimum allowable value;

Decrease in water pressure in the hydraulic circuit of the boiler below the permissible level;

The pressure has risen above the permitted by 10% and continues to grow, despite the interruption of the fuel supply and the increased supply of water to the boiler;

Feed pump stopped working;

The power supply is interrupted, as well as the elements of the boiler are damaged, creating a danger to the operating personnel or the threat of destruction of the boiler;

Malfunctions of safety automation or alarms, including power failure in these areas;

The occurrence of a fire in the boiler room that threatens the personnel or the boiler.

9.2.2. The procedure for emergency shutdown of the boiler must be specified in production instructions. The reasons for the emergency shutdown of the boiler must be entered in the shift log.

10. OPERATION AND MAINTENANCE

10.1 How it works

After installing the boiler and connecting it to the space heating system, it is necessary to fill the system and the boiler with water and carry out an inspection. Grates are installed after hydraulic test and inspection.

When firing up the boiler, do the following:

1. open the chimney damper, firebox and blower doors;

2. remove slag and ash from the furnace and from the ashpit blower;

3. lay in the furnace on the grate required amount firewood;

4. lay lumpy coal on the firewood;

5. set fire to firewood in the firebox;

6. close the furnace door and adjust the supply of the blower fan or the opening of the blower door according to combustion;

7. With stable burning of firewood and coal, pour the required amount of coal evenly over the firebox.

10.2 Maintenance

10.2.1 Maintenance consists of periodic inspections, blowing, cleaning of the boiler and its repair.

10.2.2 List of maintenance measures.

In order to ensure reliable operation boiler, it is recommended to carry out the following measures:

Visual control of leaks;

Checking the drain pipe;

Checking flange connections;

blowing;

Complete cleaning, inspection of heating surfaces.

10.3 Blowing and cleaning the boiler

10.3.1. In order to ensure perfect and more economical operation of the boiler, blowing should be carried out quite often. With an increase in flue gas temperature by 30-40 about From above the gas temperature of a clean boiler at the same load, the boiler should be blown. The boiler should also be blown in if the resistance of the boiler gas path increases significantly.

10.3.2. The boiler is cleaned from soot through the doors of the furnace and ash pan. Cleaning can be done either manually or with a mechanized brush (ruff). When cleaning with a power brush, care must be taken to avoid damaging the pipes.

10.3.3. Internal inspection and cleaning of the furnace is carried out during summer downtime boiler. All accumulated soot and dirt is removed from the walls of the furnace and the convective part with a steel brush.

10.3.4. Internal inspection, flushing and cleaning of the water path should be carried out in summer period boiler downtime annually. Inspection of the boiler is carried out through the doors of the furnace and ash pan.

The boiler is cleaned from boiler stone and sludge by chemical means. Chemical cleaning is carried out with a 5% solution of hydrochloric acid inhibited by a mixture of PB-5 - 0.1% with urotropin - 0.5%; or a mixture of PB-5 with urotropine and OP-10 at a temperature of 60-65°C. The solution circulation time is from 6 to 8 hours at a speed of movement along the tract of 1-1.5 m / s.

After cleaning, flush the boiler, removing all deposits of dissolved scale and sludge from it through the lower drain pipe. After that, it is necessary to fill the boiler with treated water as soon as possible. In the absence of such a composition, the boiler should be heated to operating temperature and efficient aeration.

10.4 Boiler repair

Boiler repair during warranty period may only be carried out with the written permission of the manufacturer.

After the warranty period, the repair of the boiler can only be carried out by a company that has the technical means necessary for the high-quality performance of work.

10.5 Safety precautions

10.5.1. During maintenance, strict adherence to safety measures is required. Repair work must be carried out in strict accordance with the rules and regulations for the production of repair work.

10.5.2. Repair, cleaning and inspection of the boiler may only be carried out after appropriate instruction at the workplace.

10.5.3. Work inside the boiler may only be carried out when the boiler is sufficiently cold. Before starting work, the boiler must be ventilated.

10.5.4. It is forbidden to work in the furnace and convective part having a temperature above 60°C.

10.5.6. Repair of the boiler is to be carried out with the following turned off: water, air, with the power removed from the automation system.

10.5.7. Inspection, lubrication and repair of component equipment is carried out in accordance with the operating instructions for the relevant products.

10.5.8. Do not allow burning coal to fall on the floor. The distance from the boiler to combustible structures must be at least 2000 mm.

10.5.9. It is unacceptable to leave firewood, coal, combustible objects near the melted boiler or to dry clothes.

10.5.11. It is forbidden to use flammable fuel or explosive substances (gasoline, kerosene, acetone, etc.) to kindle the boiler.

10.5.12. On a working boiler, it is not allowed to increase the water temperature by more than 100 0 C, when the temperature rises, it is necessary to reduce the combustion of the fuel by covering the blower fan damper or the blower door and reducing the draft or increasing the water flow.

11. PRESERVATION OF THE BOILER

The procedure for preserving the boiler for long-term storage must comply with this manual.

Preservation of the boiler for a period of up to one month should be carried out by the wet method, for this it is necessary:

Stop the boiler according to the instructions;

Disconnect the boiler pipeline from the common lines;

Fill the internal volume of the boiler with a protective solution: sodium hydroxide 1000 mg/l, phosphoric anhydride 100 ml/l and sodium sulfate 200 mg/l;

Before starting up the boiler after wet conservation, open the system, release the alkaline solution and rinse with clean water;

When the boiler is shut down for a long time (more than one month), conservation must be carried out in a dry way, for this it is necessary:

Stop the boiler according to the instructions;

At a pressure in the boiler equal to half the working pressure, purge the boiler according to the instructions;

After lowering the temperature to 50-60ºС, drain the water from the boiler;

Clean the heating surface from scale and sludge;

Dry the inside of the boiler by blowing with compressed air;

Bring into the collector previously prepared baking sheets filled with quicklime (1 kg in each collector, or anhydrous calcium chloride, 0.5 kg each in each collector).

Before starting the boiler, which is in dry conservation, it is necessary to remove the trays with lime (calcium chloride) from the collectors.

Preservation and re-preservation of instruments, protection, control and auxiliary equipment according to the instructions for installation and operation of the manufacturers of these devices and equipment.

The supply of the boiler, which is under conservation, with electricity must be excluded.

12. GENERAL INSTRUCTIONS

12.1. Capital and current repairs of hot water boilers must be carried out in accordance with specially designed schedules. Minor defects found during operation must be eliminated as soon as possible on the operating boiler (if the operating rules allow) or whenhis stop.

12.2. Safety measures during operation, preparation for work, operation procedure, measurement of parameters, adjustment and adjustment, check technical condition during operation, typical malfunctions and methods for their elimination and maintenance should be carried out according to the relevant sections technical description boiler.

The concept of conservation is usually associated with food, which is understandable. The ordinary consumer encounters this form of preservation of the original characteristics much more often. In other areas, such an approach to the maintenance of objects can be considered as one of the inventory tools. This is how the conservation of equipment at enterprises is characterized, which provides not only for the implementation of the technical side of the matter, but also for compliance with the relevant legal standards.

What is the conservation of production equipment?

Situations are quite common when they remain idle for a while. This may be part of the technical equipment at the enterprise, or the entire infrastructure with equipment. In any case, leaving the equipment for a long time is possible only with the appropriate preparation, which is conservation. This is a set of measures aimed at ensuring the safety of equipment characteristics for a certain period. That is, it is assumed that, for example, machines and units at this time will not be operated and will be subject to repair and maintenance measures.

At the same time, it is important to take into account that the conservation of equipment is not a means of passive protection from external influences. Special handling may be required depending on storage conditions. metal surfaces, rubber elements and other parts of the equipment. From this point of view, conservation is also a preventive means of maintaining the good condition of an object.

Legal registration of the procedure

Preparation for the conservation process begins with the implementation of formal procedures. In particular, the preparation of documentation is necessary so that in the future it remains possible to recognize all the costs of the activity. The conservation initiator may be a representative of the service personnel who submits an appropriate application addressed to the head. Next, an order is issued for the allocation Money on the procedure and an indication is given to develop a project in which the conservation requirements of the technical services will be noted. As for legal requirements, representatives of the administration, the management of the department responsible for facilities, economic services etc. Thus, the composition of the commission is formed, which performs the examination of the conserved objects, paperwork, assess the economic feasibility of the project and draw up an estimate for the maintenance of the objects.

Technical execution of conservation

The whole procedure consists of three stages. At the first stage, all kinds of contaminants, as well as traces of corrosion, are removed from the surfaces of the equipment. If necessary and available technical feasibility repairs may also take place. This stage is completed by measures for degreasing surfaces, passivation and drying. Next stage involves processing with protective equipment, which are selected on the basis of individual requirements for the operation of a technical facility. For example, conservation of boilers may include treatment with heat-resistant compounds, which in the future will provide structures with optimal resistance to impact. high temperatures. To universal means treatments include anti-corrosion powders and liquid inhibitor. The final stage provides

Performing a represervation

During storage, responsible services periodically inspect the equipment, assessing its condition. If traces of corrosion or other defects are found on the surfaces of the equipment, re-preservation is carried out. This event also involves the implementation of primary surface treatment in order to remove traces of damage to metal or other materials. In some cases, re-preservation also takes place - this is the same set of preventive measures, but in this case it has a planned nature of execution. For example, if a protective composition is applied with a certain service life, then after this period the technical service must update the product as part of the same re-preservation.

What is reconservation?

When the time allotted for conservation expires, the equipment is subjected to a reverse process, which involves preparation for operation. This means that preserved parts must be freed from temporary protective compounds and, if necessary, treated with other means designed for use on working equipment. It is worth noting the need for precautionary measures. Like technical preservation, depreservation must be carried out under conditions that meet the requirements for the use of degreasing, anticorrosive and other compositions that are sensitive to temperature and humidity. Also, when performing such procedures, special ventilation standards are usually observed, but this depends on the specifics of the particular equipment.

Conclusion

The conservation procedure undoubtedly has many advantages, and its implementation is mandatory in many cases. Nevertheless, it does not always justify itself from a financial point of view, which leads to the involvement of accounting in the preparation of the corresponding project. Nevertheless, conservation is a set of measures aimed at maintaining the operability of equipment in order to obtain benefits for the enterprise. But if we are talking about unused or unprofitable objects, then the meaning of the implementation similar events missing. For this reason, the stage of preparation and development of a project for transferring equipment to a canned state is to some extent even more responsible than the practical implementation of the procedure.

A feature of the state of energy today is that the number of shutdowns and downtime of boilers has increased at thermal power plants, this is due to a change in the mode of energy consumption and heat supply. Equipment is reserved for an indefinite period. During the shutdown of the boiler, the pressure of the environment drops to atmospheric, there is a possibility of moisture and air getting into it, as a result, the boilers corrode, which is considered dangerous, since there is a possibility of damage to all thermal equipment, including pipelines. Therefore, at the moment, the issue of conservation is especially relevant, and the development of technologies for this is progressing.

Scheme of a solid fuel boiler.

Thanks to the protection against corrosion formed during downtime, the working condition equipment, the cost of its repair and restoration is reduced, the technical and economic performance of thermal power plants is maintained, and production costs are also reduced.

There are several ways to preserve boilers:

• gas method of conservation;
• wet preservation method;
• mode of application overpressure;
• dry preservation method.

A daily downtime of an unpreserved boiler will lead to rust of the equipment in the circuit up to 50 kg of iron oxide. When stopping hot water boilers for a period of 15 hours or drum boilers for up to 1 day, it is recommended to carry out preservation by the method of excess pressure, for a short period (5-6 days) - the dry preservation method. The choice of a suitable method to exclude oxygen corrosion is made taking into account the parameters and power of the boilers, their specifics during operation.

To prevent parking corrosion of the metal of heating surfaces of boilers during major and current repairs, only conservation methods are applicable that allow creating a protective film on the metal surface that retains its properties for 1-2 months after draining the preservative solution, since emptying and depressurization of the circuit in this case inevitable.

Instructions for the conservation of steam and hot water boilers with gas

Scheme of a gas boiler.

This method is intended for the conservation of boilers during downtime with a decrease in pressure to atmospheric pressure. It is used for conservation of steam and hot water boilers. During the proposed conservation, the boiler is emptied of water and filled with gas (for example, nitrogen), after which excess pressure is maintained inside the boiler, at the same time, before gas is supplied, it is filled with deaerated water.

The steam boiler conservation method involves filling the boiler with gas at an overpressure in the heating surface of 2-5 kg/cm² while simultaneously displacing water in the drum. In this case, the ingress of air inside is excluded. According to this scheme, gas (nitrogen) is supplied to the outlet collectors of the superheater and into the drum. The low overpressure in the boiler is due to the consumption of nitrogen.

This method cannot be used for the conservation of boilers in which the pressure has decreased to atmospheric pressure after shutdown and the water has been drained. There are cases of emergency shutdown of the boiler. During repair, it is completely emptied, respectively, air gets inside. The specific gravity of nitrogen and air is not significantly different, therefore, if the boiler is filled with air, it is impossible to replace it with nitrogen. In all areas where the air is located and where the humidity exceeds 40%, the metal of the equipment will be subject to oxygen corrosion.

Little difference in specific gravity is not the only reason. Displacement of air from the boiler and uniform distribution of nitrogen over it is also impossible due to the lack of hydraulic conditions, the cause of which is the nitrogen supply system (through the outlet headers of the superheater and the drum). Also in the boiler there are so-called non-draining areas that are impossible to fill. Therefore, such a method is applicable only after the boiler has been operating under load while maintaining excess pressure in it. This is the disadvantage of such a technical solution.

The task of the boiler conservation method with gas is to increase the reliability and efficiency of boilers that are put into reserve by completely filling the steam-water path with gas, regardless of the shutdown mode. The described preservation method is illustrated by a diagram (image 1).
Boiler conservation scheme with indication of boiler equipment:

Steam boiler diagram.

1. Drum.
2. Airmen.
3. Superheater.
4. Airmen.
5. Capacitor.
6. Airmen.
7. Superheater outlet manifold.
8. Portable cyclone.
9. Airmen.
10. Screens of the boiler circulation panels.
11. Economizer.
12. Drainage of the lower points of the boiler.
13. Air outlet chamber of the superheater.
14. Nitrogen supply line with valve.
15. Air vent line with valve.
16. The line of drainage and supply of water with a valve.

Scroll necessary tools, devices, fixtures:

1. Manometers are U-shaped.
2. Gas analyzer.
3. Set of wrenches.
4. Combined pliers.
5. Screwdrivers.
6. Files.
7. Stairs.
8. Bucket.
9. Solidol.
10. Paronite pads.
11. Plugs, bolts, nuts, washers.
12. Means and medicines of the first pre-medical aid.
13. Fire extinguisher.

The process of conservation of the boiler with gas is carried out as follows (an example of conservation of a steam drum boiler is given):

Schemes of separation devices in the boiler drum.

The boiler is released from water after it stops, opening all its lower points. After emptying, in some places there remains a vapor-air mixture containing oxygen, which causes corrosion of the metal of boiler equipment. In order to displace the steam-air mixture, all elements of the boiler (1, 3, 5, 7, 8, 10, 11) are filled with deaerated water. Filling occurs through the lower points (12). Complete filling is controlled by the valve (15), after which they close and supply nitrogen through the valve (14), then through the air vents (9, 2, 6, 4, 13).

When supplying nitrogen to the boiler, it is necessary to open the drains of the lower points of all its components. Next, the water is forced out and the boiler is filled with nitrogen. The nitrogen pressure in the boiler is adjusted on the supply line 14 and (if necessary) on the discharge line 16. After the water is completely displaced and the boiler is filled with nitrogen, the overpressure necessary for conservation is set (25-100 mm of water column). Despite the presence of a small amount of deaerated water in some parts of the boiler, the metal of the equipment does not corrode, this has been proven by research.

Consequently, the proposed method significantly increases the reliability of conservation due to the absolute disposal of the boiler from air, filling it with deaerated water and nitrogen with parallel displacement of water.

Instructions for the wet method of preservation of hot water and steam boilers

Scheme of the air duct.

The boiler is filled with preservative solutions that create a layer on the metal that retains its properties throughout the entire time the steam generator is idle. An alkali solution is added to the water with which the steam generator is filled, observing the proportions: 2-3 kg of sodium hydroxide and 5-10 kg of sodium phosphate per 1 l³ of water with the addition of 1 kg of ammonia hydrate or a 10% solution of hydrazine hydrate. This solution provides a concentration in water of 200 mg/kg NzH and is added using a plunger pump. Re-preservation of the boiler and its kindling after this method of conservation takes place quite quickly. To prevent corrosion, use a special protective solution that contains caustic soda. The use of soda ash is also practiced, but this is undesirable, since there is a danger of local corrosion.

Using the wet preservation method, the boiler is filled with a protective solution, which ensures absolute resistance to rust, even if the liquid is saturated with oxygen. During the use of the proposed conservation method, it is possible to determine the period of permissible duration without loss of mining; determine the timing of drainage, repair of lining, ventilation, lifting complex and other equipment with other reparative measures.

wet preservation technology

When carrying out wet conservation of the boiler, it is necessary to ensure the dryness of its surface and masonry, close all hatches tightly. Monitor the concentration of the solution (the content of sodium sulfate should be at least 50 mg / l). The use of the wet preservation method during repair work or in the presence of leaks in the boiler is unacceptable, since compliance with tightness is the main condition. If with dry and gas method conservation, steam seepage is unacceptable, then when wet it is not so dangerous.

Scheme of a double-turn steam superheater.

If it is necessary to stop the boiler for a short period, a simple wet preservation method is used, filling the boiler and the steam heater with deaerated water while maintaining excess pressure. If the pressure in the boiler drops to 0 after it has been shut down, filling it with deaerated water is no longer effective. Then you need to boil the boiler water with open air vents, this is done in order to remove oxygen. After boiling, if the residual boiler pressure is not lower than 0.5 MPa, conservation can be carried out. This method is used only when the oxygen content in deaerated water is low. If the oxygen content exceeds the allowable value, corrosion of the metal of the superheater is possible.

Boilers with shutdown immediately after operation can be subjected to wet preservation without opening the drums and headers.

AT feed water you can add ammonia in gaseous form. A protective film is formed on the surface of the metal, protecting it from corrosion.

In order to exclude the occurrence of corrosion in boilers that are in reserve for a long time, the wet preservation method is used, maintaining an excess pressure of a nitrogen cushion over the liquid in the boiler, eliminating the possibility of air entering the boiler. In contrast to dry conservation, in which dewatering agents operate, dewatering is provided from the mine working, boiler equipment maintained in a condition suitable for use when necessary. At the time of conservation, the write-off of mineral reserves is not allowed.

Preservation method by creating excess pressure

Boiler valve connection diagram.

Instructions for the technology of preservation of the boiler by creating excess pressure is applicable regardless of the heating surface of the boiler. Other methods using water and special solutions are not able to protect the intermediate superheaters of boilers from corrosion, since certain difficulties arise during filling and cleaning. To protect superheaters, conservation is applied by vacuum drying using ammonia gas or filling with nitrogen regardless of downtime. As for the metal screen pipes and other parts of the steam-water path of drum boilers, they are not 100% protected to the same extent.

The proposed conservation technology is suitable for both steam and hot water boilers. Principle this method It consists in maintaining the pressure in the boiler above atmospheric, which will prevent the ingress of oxygen into it, and is used for boilers of any type of pressure. To maintain excess pressure in the boiler, it is filled with deaerated water. This method is used when there is a need to put the boiler on standby or carry out repair work not related to measures on the heating surface, for a total period of up to 10 days.

The implementation of the method of maintaining excess pressure in stopped hot water or steam boilers is possible in several ways:

1. During the downtime of the boilers for more than 10 days, conservation by dry or wet methods is applicable (determined by the presence of certain reagents, gasket materials, etc.).
2. During a long downtime in winter and in the absence of room heating, the boilers are preserved using the dry method; application wet process conservation under these conditions is unacceptable.

The choice of one or another method depends on the mode of operation of the boiler room, total number reserve and operating boilers, etc.

Dry method of preservation of boilers

Boiler outlet diagram.

The release of the boiler from water at a pressure above atmospheric pressure occurs after emptying due to the heat accumulated by the metal, lining and isolation while maintaining the temperature of the boiler above the temperature of atmospheric pressure. At the same time, the inner surfaces of the drum, collectors and pipes are dried.

Dry shutdown is applicable to boilers with any pressure, but provided that there are no pipe-to-drum flare joints in them. It is carried out during a planned shutdown in reserve or for the period of equipment repair work for a period of not more than 30 days, as well as during an emergency shutdown. In order to prevent moisture from entering the boiler during downtime, it is necessary to monitor its disconnection from the pressurized water and steam pipelines. Must be tightly closed: plug installations, shut-off valves, inspection valves.

Displacement of water is carried out at a pressure of 0.8-1.0 MPa after the boiler has been stopped and cooled naturally. The intermediate superheater is devaporated onto a heat exchanger. At the end of drainage and drying, the valves and valves of the steam-water circuit of the boiler, the manhole and gate of the furnace and gas duct must be closed, only the revision valve remains open, if necessary, plugs are installed.

During the conservation process, after the boiler has completely cooled down, it is necessary to periodically monitor the ingress of water or steam into the boiler. Such control is carried out by probing the spaces of their probable entry into the area stop valves, opening drains of the lower points of collectors and pipelines, valves of sampling points for a short period.

In case of detection of water ingress into the boiler, the necessary measures must be taken. After that, the boiler is subject to kindling, raising the pressure in it to 1.5-2.0 MPa. The specified pressure is maintained for several hours, and then nitrogen is produced again. If the ingress of moisture cannot be eliminated, a conservation method is resorted to by maintaining excess pressure in the boiler. A similar method is still used if, during the shutdown of the boiler, repair work equipment on heating surfaces and there was a need for pressure testing.

If the boiler is stopped for long time, then it needs to be conserved. When mothballing boilers, it is necessary to follow the instructions of the manufacturer for installation and operation.

To protect boilers from corrosion, dry, wet and gas preservation methods are used, as well as, in some cases, conservation by the overpressure method.

The dry method of conservation is used when the boiler is stopped for a long time and when it is impossible to heat the boiler room in winter. Its essence lies in the fact that after removing water from the boiler, superheater and economizer and cleaning the heating surfaces, the boiler is dried by passing hot air (thorough ventilation) or a small fire is lit in the furnace. Wherein safety valve must be opened to remove water vapor from the drum and pipes. If a superheater is present, the drain valve on the superheated steam chamber must be opened to remove the remaining water in it. After drying is completed, pre-prepared iron pans with quicklime are placed through the open manholes in the drums. lime CaO or silica gel (in the amount of 0.5-1.0 kg of CaCl2, 2-3 kg of CaO or 1.0-1.5 kg of silica gel per 1 m3 of boiler volume). Tightly close the manholes of the drum and cover all the fittings. When stopping the boiler for more than 1 year, it is recommended to remove all fittings and install plugs on the fittings. In the future, at least once a month, the state of the reagents should be checked, and then every 2 months, depending on the results of the check, it must be replaced. It is recommended to periodically monitor the condition of the brickwork and, if necessary, dry it.

Wet way. Wet preservation of boilers is used when there is no danger of water freezing in them. Its essence lies in the fact that the boiler is completely filled with water (condensate) with high alkalinity (caustic soda content 2-10 kg / m of air and dissolved gases and tightly close the boiler.The use of an alkaline solution provides sufficient stability with a uniform concentration protective film on the metal surface.

gas method. At gas method conservation from the cooled boiler drain the water, thoroughly clean the inner surface of the heating from scale. After that, the boiler is filled with gaseous ammonia through the air vent and a pressure of about 0.013 MPa (0.13 kgf/cm2) is created. The action of ammonia is that it dissolves in the film of moisture that is on the surface of the metal in the boiler. This film becomes alkaline and protects the boiler from corrosion. With the gas method, the preservation personnel must be aware of the safety regulations.

The overpressure method consists in the fact that in the boiler, disconnected from the steam pipelines, the steam pressure is maintained slightly above atmospheric and the water temperature is above 100 ° C. This prevents air from entering the boiler and, consequently, oxygen, which is the main corrosive agent. This is achieved periodically by heating the boiler.

When the boiler is placed in a cold reserve for up to 1 month, it is filled with deaerated water and a slight excess hydrostatic pressure is maintained in it by connecting it to a tank with deaerated water located above. However, this method is less reliable than the previous one.

With all methods of conservation of boilers, it is necessary to ensure complete tightness of the fittings; all hatches and manholes must be tightly closed; with dry and gas methods, idle boilers must be separated from working boilers with plugs. Preservation of equipment and its control are carried out according to special instructions and under the guidance of a chemist.