Modernization of the TVG-8M boiler - graduation project

Introduction

The boiler plant is a complex of devices located in special rooms and serving to convert the chemical energy of fuel into thermal energy of steam or hot water.

Boiler plants, depending on the type of consumer, are divided into energy, production-heating and heating. According to the type of heat carrier produced, they are divided into steam (for steam generation) and water heating (for hot water generation).

Heating boiler plants (mainly hot water, but they can also be steam) are designed for servicing heating systems, hot water supply and ventilation of industrial and residential premises.

Depending on the scale of heat supply, heating boiler houses are divided into local (individual), group and district.

Local heating boilers are usually equipped with hot water boilers with water heating to a temperature of no more than or steam boilers with a working pressure of up to. Such boiler houses are designed to provide heat to one or more buildings.

Group heating boilers provide heat to a group of buildings, residential quarters or small microdistricts. Such boilers are equipped with both steam and hot water boilers, as a rule, with greater heat capacity than boilers for local boilers. These boiler houses are usually placed in special buildings.

District heating boiler houses are designed for heating large residential areas; they are equipped with relatively powerful hot water and steam boilers.

The technical condition of heat supply sources, heating networks and other facilities of municipal thermal power engineering today does not meet modern requirements. A technical reconstruction of the entire heat supply system and the introduction of new energy-efficient and environmentally friendly heat and power equipment is needed.

Industrial and utility thermal units have the following disadvantages:

most industrial and domestic boilers are mentally and physically obsolete;

many boilers are no longer manufactured by industry;

water-chemical equipment of heating boiler houses is in a neglected state;

most boilers are not equipped with safety and control automation systems;

the number of capital and current repairs exceeds the permissible norms.

Today, the vast majority of energy conservation projects in the housing and communal services of Ukraine are aimed at solving two urgent issues of the functioning of this sphere: firstly, these are constant energy overspending and the inability to indefinitely raise tariffs for consumers; secondly, this is the absence, unsatisfactory quality or extreme lack of reliability of the main types of housing and communal services (especially in centralized networks).

A promising direction in the technical re-equipment of heat supply sources is the modernization and reconstruction of existing hot water boilers with the installation of modern gas-burner devices that provide more efficient and economical combustion of fuel with the least amount of harmful emissions into the atmosphere; installation of waste gas heat recovery devices; replacement of existing safety automation and control systems; increased heating surface of boilers.

Savings in fuel and energy resources - comparative in comparison with the basic, reference value of reducing the consumption of TER for the production of products, performance of works and provision of services of established quality without violating environmental and other restrictions in accordance with the requirements of society.

The main directions of energy efficiency improvement in the heat supply complex are:

- decommissioning of boiler houses that have lost their life;

- application of renewable sources of low-potential heat (heat pumps);

- modernization of existing boiler houses and construction of new ones using modern technologies and equipment with a efficiency of at least 92%;

- construction of new and replacement of existing heating networks with

the use of modern technologies;

- replacement of old heating boilers in residential and public buildings with individual heating systems with energy-efficient boilers with efficiency of at least 95%;

- Introduction and construction of decentralized heat supply sources.

General part

1.1 Boiler house characteristics

The heating boiler house is located in a residential microdistrict of the city of Lugansk. The boiler room is designed to generate thermal energy in the form of hot water for heating, ventilation and hot water supply of residential and public buildings.

The main fuel for the boiler house is natural gas in composition, equated to fuel from the Shchebelin Kharkiv gas pipeline.

Gas supply of the boiler house is carried out from the high-pressure city gas pipeline. To reduce the gas pressure to the working one, a gas control unit is attached to the boiler room.

The heat supply system is a closed double-tube with a mixed connection scheme for hot water heaters and subscribers.

Heat supply of consumers from the boiler house is carried out along two highways DN 250 and DN 80. Only consumers of the heating system are connected to line DN 80 according to an elevator-free scheme with a temperature schedule of 95/70. Reduction of coolant temperature for this group of consumers is carried out in the central heat point, which is located on the territory of the microdistrict.

For a group of consumers connected to line Dn 250, thermal energy is released according to the temperature schedule 115/70. Regulation is high-quality in terms of heating load. Network water consumption for hot water supply is accepted based on heating schedule.

The main equipment of the boiler house is water heating boilers of the TVG4r type in the amount of two units.

Consumers of thermal energy from the boiler house are groups of residential and public buildings of various storeys and areas.

Climatic data of the design area:

- design ambient temperature for heating design - t p.o = - 25 0C;

- average temperature of external air for the heating period - tcp. about = - 0,4 0C ;

- outside air temperature of the coldest month - tx.m = - 5.0 0C;

- heating period duration - no = 172 0C.

Ventilation of the boiler room is natural, plenum.

For air inflow, plenum louver grilles arranged in the boiler room wall are equipped, and for air removal, exhaust baffles built into the boiler room roof are equipped. Ventilation of the boiler room provides three-fold air exchange.

As the main source of water supply of the boiler house, water from the city drinking water supply is used, having the following quality indicators:

- calcium stiffness - 0 mgeq/l;

- magnesium stiffness - 4.3 mhequv/l;

- alkalinity total - 2.5 mheq/l;

- salt content - 270 mg/l.

Boiler house environmental assessment

2.4.1 Pollution source analysis

The level of atmospheric air pollution in the industrialized cities of the republic exceeds the maximum permissible concentrations. The main source of pollution is fuel-using plants, including heating and production boiler houses. Boiler plants release combustion products containing many harmful impurities into the atmosphere, namely: polycyclic aromatic hydrocarbons, including benzene (a) pyrene C20H12 (1st hazard class); nitrogen oxides NOx (hazard class 3); sulphur dioxide SO2 (hazard class 3); CO carbon monoxide (hazard class 4), as well as suspended substances (ash, soot and coke residues), the toxicity of which depends on the impurities contained in them .

The objectives of the studies were to determine the concentrations of harmful substances released during the operation of the boiler house in maximum capacity modes, to analyze the need for measures to clean boiler house emissions and to assess the environmental safety of the boiler house.

In accordance with the "Environmental Doctrine of the Russian Federation," the laws "On Environmental Protection" and "On Atmospheric Air Protection" for all technological installations that emit harmful substances, environmental measures should be provided that reduce or eliminate harmful effects on the atmospheric air. During the environmental assessment of the boiler plant, calculations are made: the amount of emissions of the boiler plant; the mass of contaminants removed by the chimney; the distribution of pollutants in the atmosphere, and maximum permissible emission (IPA) standards are also being developed.

Automation

3.1 Automation of TVG-4r boiler

Automatic control of the combustion process ensures the supply of fuel to the furnace depending on the boiler load, maintaining the optimal fuel-to-air ratio and stable vacuum in the furnace.

The temperature of the water downstream of the boiler (or up to it) is maintained within the specified limits by the regulator changing the fuel supply to the furnace. As a water temperature sensor, a resistance thermometer installed on the pipeline at the outlet of water from the boiler (at the inlet of water to the boiler) is used.

The control of the air supply ensures the optimal ratio between the fuel supplied to the furnace and the air (the optimal excess of air), thereby achieving maximum fuel combustion efficiency in all boiler operating modes. The "fuel air" regulator receives a gas flow pulse to the boiler, which is directly measured by the flowmeter, and an air pressure drop pulse, which is proportional to the air flow. The regulator acts on the blast fan guide vanes.

Control of water flow through the boiler is carried out by the regulator, which controls the control valve downstream the recirculation pump, installed on the straight-back water line.

The required water temperature at the inlet of the heat network is maintained by a regulator that changes the flow rate of cold water using a bypass control valve installed on the bridge. The input signal of the regulator is the signal from the resistance thermometer installed on the straight water pipeline.

Thrust control provides automatic maintenance of stable vacuum in the boiler furnace within the range from -20 to -30 Pa. The rarefaction regulator receives a rarefaction pulse in the upper part of the furnace chamber from the differential traction meter. Regulator amplifier controls thrust actuator acting on smoke pump guide vane.

The gas pressure upstream of the burner is controlled by the regulator. In front of the main burner control element (rotary shutter) and the igniter there are two fast-acting valve compartments, between which there are electromagnetic blowdown valves on the safety plug. Opening of valve compartments in front of the main burner is performed automatically in 45 s, and closing - almost instantly.

The presence of the igniter flares and the main burner is monitored by the igniter (ionization sensor for the igniter flare and photosensor for the main flare).

In case of emergency deviations of parameters during operation of the boiler, its automatic protection is provided in the following cases:

absence of igniter flare (during start-up period);

main burner flare failure;

pressure drop of primary and secondary air upstream the burner;

increasing the gas pressure upstream of the control member and reducing the gas pressure upstream of the control member and reducing the gas pressure upstream of the main burner shut-off valve;

reducing and increasing the pressure in the boiler furnace;

decrease of water flow through the boiler and its pressure downstream the boiler;

increase of pressure and temperature of water downstream the boiler;

voltage drop in protection and alarm circuits;

opening the nozzle and increasing current of its electric drive (when operating on liquid fuel).

Remaining unchanged from the point of view of the principle of operation of the main regulators, the automatic control system as a whole is a set of the latest achievements and developments in the field of automation.

Boiler ACS is implemented using microprocessor technology, which highlights a number of undeniable advantages compared to traditional control systems. The use of computers allows you to fully monitor the operation mode of the equipment. All necessary information about the state of the object, the values ​ ​ of the operating parameters are displayed on the computer screen. Maintenance personnel can access the computer memory database at any time and see how efficiently the equipment has been used at any time. Based on this data, you can assign activities aimed at improving the efficiency of equipment use. This kind of information can also be useful in the investigation of accidents.

The boiler ACS, being an integral structure, can be considered as one of the modules of the global control system of the subject. Digital communication, by means of which interaction between individual modules of the system is carried out, is able to transmit significant amounts of information in fractions of seconds, which makes the control system inertial, quickly adaptable to changing external parameters.

The functional diagram of the boiler control subsystem is presented in the graphic part.

To ensure the automatic operation of the boiler on the gas line, the following actuators and sensors are adopted:

- solenoid valve VN4H0.5 (Dn = 100) - shut-off valve;

- solenoid valve with electromechanical flow regulator VN4M0.5 (Dn = 100) - control valve;

- valve of safety pipeline BF3/4H4 (Dn = 20) located between valves BH4H0.5 and BH4M0.5;

- valves of blowdown gas pipelines 1, 2, 3, 4 of BF3/4H4 burners (Dn = 20);

- valves on the gas supply line to 1, 2, 3, 4 burners BH1/2H4 (Dn = 15);

- ball cranes (included in the burner) with electric drives before 1, 2, 3, 4 burners;

- gas pressure sensor installed on the main gas pipeline to the boiler in front of the gas unit;

- gas temperature sensor;

- gas flow sensor;

- gas pressure sensor installed between valves BH4H0.5 and BH4M0.5;

- gas pressure sensors on 1, 2, 3, 4 burners.

At all stages of the boiler operation, actuators on/off operations are monitored by position sensors taking into account time characteristics (on/off time). If the failure to execute the command is detected (open/close) at the set time, the boiler is switched off, an emergency message is automatically recorded in the event report indicating an unfair actuator, the alarm is turned on, the units are set to the initial position, the boiler furnace is ventilated.

When the boiler is switched off, the actuators of the gas line are in the initial position:

- inlet gas gate valve (with manual drive) - closed;

- solenoid valve VN4H0.5 (Dn = 100) - closed;

- solenoid valve with electromechanical flow regulator VN4M0.5 (Dn = 100); - closed;

- valves of blowdown gas pipelines and safety gas pipeline VF3/4H4 (Dn = 20) - open;

- valves BH1/2H4 (Dn = 15) installed on gas pipelines of gas supply to ignition burners 1, 2, 3, 4 of the burner - closed;

- ball valves installed on gas pipelines of gas supply to main burners - closed;

When the boiler is switched on, the control system checks the serviceability of all measuring channels (sensors and communication lines with them). Upon positive completion of the check, the control system begins to check the gas line tightness, otherwise the boiler switching on process is stopped and the alarm is turned on, indicating the cause of the accident.

Gas line tightness check is performed in two stages:

check of gas outflow from the line;

check of gas flow into the line.

Check of gas outflow from the line:

- blowdown and safety pipeline valves are closed;

- inlet gas gate valve opens;

- control valve opens;

- shut-off valve is opened for short time to fill the line with gas;

- time monitoring timer is activated;

- if after the specified time interval the gas pressure on the pressure sensor after the control valve is within the permissible limits - the check was successful and the control system begins to perform the next stage of tightness check, otherwise the control process stops with setting of actuators to the initial position.

Check of gas flow into the line:

- opening of valves in blowdown and safety pipelines, pressure in gas line equalizes with atmospheric one;

- valves in blowdown and safety pipelines are closed;

- time monitoring timer is activated;

- if after the specified time interval the gas pressure in the line does not exceed the specified set point - the check was successful and the control system starts the ventilation operation, otherwise the boiler switching on process stops with setting of actuators to the initial position.

After the gas line leak check operation, the boiler furnace ventilation operation is performed. After performing the ventilation operation, the operation of setting the required air pressure on the burners and the vacuum in the boiler furnace (at ignition settings) is performed.

After the furnace ventilation, the gas line blowdown operation is performed:

- inlet gas gate valve is open;

- shut-off valve is open;

- control valve is open;

- valves of blowdown gas pipelines 1, 2, 3, 4 of burners and safety gas pipelines are open;

- ball valves on gas burners are closed;

- after the purge time, the valves are closed:

- cutoff;

- regulating;

- blowdown and on the safety gas pipeline.

After the gas line purge operation, the operation of switching on the igniters with closed valves of the purge gas lines and the valve on the safety gas line is started, the valves installed in front of the ignition burners are opened; ignition devices of 1, 2, 3, 4 burners are switched on; if within the specified time interval there are no signals about presence of flame on all igniters - the boiler starting process stops with actuators setting to initial position.

Burner ignition operation is performed after setting of required air pressure on burners and vacuum in boiler furnace (at ignition setpoints):

ball valves on 1, 2, 3, 4 burners are opened;

the shut-off valve opens;

by means of the control valve the gas pressure required for ignition of burners is set;

The timing timer is turned on.

if after the specified time interval there are no signals about the presence of flame on all burners - the boiler switching on process stops with the boiler furnace ventilation operation and actuators setting to the initial position;

when the burners are switched on, the valves on the ignition line are closed;

during the specified time interval the process of small flame stabilization takes place at ignition setpoints (gas, air pressure and vacuum).

After completion of the small flame stabilization process and installation of working air pressure and vacuum in the boiler furnace, the operation of heating the boiler with a slow, step-by-step increase in gas and air pressure on the burners is performed.

After reaching the specified coolant temperature at the boiler outlet (heating temperature), automatic gas and air adjustment is started depending on the boiler load.

When the boiler is switched off, all actuators of the gas line are set to the initial position, and the boiler furnace ventilation operation is started.

From the moment the burner ignition operation is completed, the boiler software safety system is activated.

The program safety system monitors the state of the most critical parameters of the boiler according to the readings of duplicated (vacuum in the furnace, temperature of water downstream the boiler) and trolled Instruments (gas pressure on burners, air pressure on burners). All sensors in the control system use only analog sensors, which allow continuous monitoring of their serviceability. Discrete sensors are not used - their serviceability/malfunction can be installed at the moment of their actuation or failure.

Operation

4.1 Preparation of boiler unit for ignition

Preparation for melting and melting of the boiler is carried out only by order of the head of the boiler room or the person replacing it, recorded in the watch log. The order indicates the duration of filling the boiler with water and its temperature.

Boiler room personnel shall be notified in advance by the person responsible for the change about the start time of boiler melting.

During preparation, the driver (stoker, operator) must:

a) procure wrenches and gas wrenches, hammers, gaskets and stuffing, water-indicating glasses, shovels, scrapers and make sure that fuel and feed water are available in sufficient quantity;

b) inspect the boiler and make sure that there are no dangerous damages, as well as good cleaning and absence of people and foreign objects in the boiler. After inspection close the eyes and hatches;

c) inspect the condition of frosting and lining, make sure that there are no bulges, cracks, non-frosted seams in them, as well as make sure that lining is reliable along the fire line and that the drums are protected from gases with high temperature. Make sure that the boiler headset (furnace doors, grate bars, slush blades, gliders, vanes and dampers, blowing devices, safety blast valves), partitions and arches of the fire line, hatch covers, as well as good cleaning of the heating surface and gas ducts are serviceable. To check correctness of opening and closing of gates and shiber in gas flues, compliance of designations (arrows) and inscriptions for them: openly - "About", it is closed - "Z";

d) make sure that the blinds before and after the safety valves and blinds that disconnected the boiler from the general pipelines (steam pipelines, gas pipelines, fuel oil pipelines, feed, discharge and blowdown lines) are removed;

e) check serviceability of equipment for combustion of liquid and gaseous fuel, shut-off and control devices for boilers operating on these types of fuel;

f) fill the economizer with water of the quality set by the water mode, at that it is necessary to make sure that valves, dampers (vanes) are serviceable and correct, open the air valve installed on it (to remove air) and close it after water appears from the valve;

g) fill (through the economizer) the boiler with feedwater of the quality established by the water mode to the level of the lowest level, at that it is necessary to ensure serviceability and correct position of the valves, open the air valve installed on it (if any) or one of the safety valves for air release;

h) check serviceability of instrumentation and automatic control devices, feed devices, smoke pumps and fans, as well as availability of natural thrust;

and) check packing of glands of valves, gate valves, pumps, water-display columns, etc., presence of lubricant in oil tanks of pumps and traction devices, general supply of lubricant.

In order to avoid disturbance of rolling joints and the occurrence of thermal deformations due to uneven heating of the boiler, the water temperature used to fill the boiler should not exceed 90 ° C in winter and 50-60 ° C in summer. It is not recommended to fill the boiler with water below 50 ° C, especially if the boiler metal and its coating are not sufficiently cooled. The boiler must not be filled with water at a coating temperature below 0 ° C. Fill the boiler with water gradually.

After filling the boiler with water, it is necessary to close the feed valve and monitor the level of water in the glass: does it fall. If it falls, then find the place of leakage and eliminate.

Before the boiler melt, the boiler furnace and gas ducts shall be ventilated for 1015 minutes (depending on the boiler design) by opening the furnace doors, blowing, vanes for regulating air supply, natural thrust dampers, and, if there are smoke pumps and fans, by switching them on.

It is necessary to pay attention to the careful ventilation of the furnace, gas ducts and air pipelines when working on explosive (oil, gas and dust) fuels.

Prior to decay of the liquid fuel boiler, the fuel temperature shall be brought to the value specified in the manufacturer's instructions for installation and operation of the boiler. The steam line to the nozzles shall be heated (released from condensate).

Just before the boiler is trampled, check the correct opening and closing of valves, gate valves, dampers (vanes).

The following shall be opened: valves and gate valves in front of the feed pump, valves of the bypass feed pipeline of the economizer, the valve between the boiler and the check valve, the valve between the boiler and the superheater (if any), the drain (drain) valve of the superheater. One of the boiler safety valves shall be raised and lined to discharge air from the boiler during filling with water.

The following shall be closed: gate valve at the outlet (pressure) branch pipe of the feed pump, valves at the inlet to the economizer and at the outlet from it, drain and drain valves (valves, valves) of the economizer and boiler, the main steam shutoff element of the boiler.

If all boilers did not operate in a gas-fuelled boiler house, the supply ventilation, which is explosion-proof, must be switched on before entering the boiler house. When entering the boiler room (after 5-10 minutes), check the absence of gas in the room with a gas analyzer or other reliable method.

If signs of gas contamination of the boiler room are detected, the electric lighting and electrical equipment made not in explosion-proof design are switched on and off, the boilers are not allowed to melt, as well as the use of open fire.

In preparation for the decay of the gaseous fuel boiler, it is necessary to:

a) make sure that the vanes on the boiler gas ducts that are not included in the operation are closed;

b) open the gate valves at the gas inlet to the boiler room and all subsequent gate valves (valves) along the gas flow, except for the cranes in front of the burners and the igniter of the melted boiler;

c) check serviceability of the section of the connected gas pipeline. Make sure that there are no gas leaks from gas pipelines, gas equipment and valves by washing them. It is forbidden to use open fire (burning matches, candles, etc.) during this work. Lower the accumulated condensate from the gas pipeline through the drain, then close the drain valve (valve) tightly;

d) check the correspondence of the gas pressure by pressure gauges, and at two-wire burners, in addition, the correspondence of the air pressure before the burner gate valves at the operating blast fan to the established pressures (gas, air);

e) ventilate the furnace, gas ducts and air ducts during 10-15 minutes. Adjust the thrust of the melted boiler by installing a vacuum in the upper part of the furnace 20-30 Pa (2-3 mm of water. Art.), and at the level of gas burners at least 40 - 50 Pa (4 - 5 mm of water. article).

When preparing the newly installed boiler for flushing, it is necessary to flush the feed pipelines with water from contaminants accumulated during manufacture, transportation, storage at the manufacturer's warehouses and installation site, as well as from contaminants caught in the pipelines during installation work (up to the first pre-start tests).

Careful flushing of feed lines is mandatory.

Feed pipes can be washed only when all measuring washers are removed from them. Intermediate rings are installed instead of washers.

A temporary discharge pipe shall be installed at the end of the washed pipelines for flushing. Dirty water is discharged during flushing to the sewage system.

Usually, at the beginning of the washing, very dirty water flows from the washed pipelines during the first 2-3 minutes, after which the discharge water is noticeably clarified. However, the duration of the feed line flushing shall be at least 20 minutes.

In preparation for flushing, all shut-off elements (valves, gate valves) of the feed pipeline must be fully open, except for the start-up gate valve on the pressure side of the pump.

After completion of pipelines flushing, all time is disassembled, and pipelines are restored according to constant operating diagram. After flushing it is necessary to perform opening and revision of all valves to clean it from contaminants, which can enter the internal cavities of valves during flushing.

Valves having a more complex configuration than valves are especially carefully checked. Temporarily installed intermediate rings are removed, measuring washers are installed instead.

Similar flushing of feed pipelines that have been repaired with replacement of individual pipe sections shall also be performed.

New boilers that arrived from the manufacturer to the installation site, as well as boilers that were in operation and moved from one place to another, after the completion of installation work (before their inclusion in the work) are subject to mandatory alkalization, washing and cleaning from contaminants (oil, rust, sludge, scale, etc.) accumulated during the process of manufacture, installation, operation, storage in warehouses, transportation, etc.

Boilers that have undergone repairs using welding and rolling with partial or complete replacement of heating surface pipes, as well as boilers that have been in preservation for more than two years, are subject to alkalization, washing and cleaning.

Work on alkalization, washing and cleaning of the boiler from contaminants shall be carried out in accordance with a special instruction developed on the basis of the requirements of the manufacturer's instructions for the installation and operation of the boiler, and taking into account the local operating conditions of the installed auxiliary equipment and pipelines. This instruction shall be approved by the chief engineer of the boiler owner.

4.2 Ignition of the boiler running on gaseous fuel

When using gaseous fuel, the order of ignition of burners is chosen depending on their design features.

Starting to receive gas into the gas pipeline, it is checked whether the valves of the gas pipeline to the boiler and the valves (valves, valves) of the gas burners are closed, after which the plug is opened at the end of the gas pipeline. Then gate valve is opened on gas pipeline and gas is started, observing its pressure by pressure gauge. After gas passes from the candle, its valve (crane) is closed, for 10-15 minutes the furnace and gas ducts of the boiler are ventilated, the thrust is adjusted so that the vacuum at the top of the furnace is equal to 20-30 Pa (2-3 mm of water. article).

Ignition of mixing burners (with forced air supply) should be carried out as follows: check closing of cranes in front of burners, close the air damper, open the valve near the portable igniter and light the gas coming out of it. Then the igniter is introduced into the furnace and its flame is brought to the outlet of the burner; gas valve is slowly opened before burner and after ignition of gas leaving burner, igniter is removed from furnace and hung in place.

If the gas does not catch fire or if it is lit, it is necessary to close the valve before the burner, stop the gas supply, ventilate the furnace and gas ducts for 10-15 minutes, opening the air damper. Only then can the burner be ignited again.

If the ignition of the burner is successful, the air damper in the air duct is opened several times and the flame is adjusted so that it is not smoked and that excess air does not tear the flare from the burner. Then, the gas valve in front of the burner is gradually opened and air is gradually added by the air damper, achieving normal gas combustion: the flame should be stable, non-flammable (transparent) and not detaching from the burner.

When separating the flame, the air supply should be reduced, with a long burning flame, the gas supply should be reduced. To prevent the flame from breaking off due to excessive excess air, the load should be increased by first adding gas and then air, and the load should be reduced first by air and then gas.

If the boiler has several burners, they are ignited sequentially, in the same order.

If all burners go off during melting, immediately stop the gas supply to them, remove the igniter from the furnace and ventilate the furnace and gas ducts for 10-15 minutes. Only then can the burners be re-ignited.

The order of ignition of medium-pressure injection burners with a plate combustion stabilizer differs slightly from the order of ignition of mixing burners and consists in the following: after checking the closing of cranes, primary air regulators are opened in front of the burners, gas pressure is checked in front of the burners, the gas valve is opened in front of the portable igniter, which is lit into the furnace, bringing the flame to the outlet of the burner. The valve is then opened in front of the burner (about half) until there is clearly audible noise from the gas flow, which should catch fire.

In the process of controlling the injection burner, it is necessary to ensure that the flame does not slip into the burner, especially when its load is reduced. In this case, the burner is turned off and after cooling it is again put into operation. When strong pulsations appear in the furnace, the gas supply is reduced.

Similarly, the remaining burners are lit, after which the valve of the portable igniter is closed, taken out of the furnace and hung in place.

When igniting gas burners, you should not stand against the glazing holes (melt hatches), so as not to suffer from a flame accidentally thrown out of the furnace. Maintenance personnel shall be provided with personal protective equipment (safety glasses, etc.).

Do not:

a) ignite the extinguished burners in the furnace without preliminary ventilation of the furnace and gas ducts of the boiler;

b) light the gas torch from the adjacent burner or from the hot masonry of the furnace.

Firing of boiler furnaces equipped with combustion process control automation and safety automation or complex automation shall be carried out in accordance with the requirements of production instructions for their start-up, setup and operation.

4.3 Boiler Unit Maintenance

During the duty, all boiler house personnel shall monitor the serviceability of the boiler units (boilers, superheaters, water economizers, air heaters, furnace devices) served by them, as well as auxiliary equipment of the boiler plant (feed pumps, fans, smoke pumps, air compressors, etc.) and strictly observe the operating mode established by the production instruction.

Failures detected during equipment operation shall be recorded in the replacement (watch) log. Personnel shall take immediate measures to rectify faults that threaten safe and trouble-free operation of the equipment. If it is impossible to repair the faults on your own, then it is necessary to inform the responsible for the good condition and safe operation of the boilers (head of the boiler room), and in emergency cases immediately suspend the operation of the units.

Special attention to compliance with the boiler unit operation mode should be paid to:

a) furnace operation mode;

b) maintenance of normal water level in the boiler and its uniform supply with water;

c) maintaining normal steam and feed water pressure;

d) maintaining the temperature of superheated steam and feedwater after the water economizer. Blowing of heating surfaces;

e) maintenance of steam superheater and main steam shut-off valve (gate valve) of the boiler;

f) safety valves and their maintenance;

g) boiler blowdown;

h) maintenance of water economizer and air heater;

and) traction units (smoke pumps, fans).

Boiler driver (operator) shall:

a) carefully monitor the gas and air pressure in front of the burners so that it does not go beyond the limits set by the production instruction and the control card. If the gas pressure drops below the norm specified in the instruction, reduce the gas consumption up to the complete shutdown of the burners;

b) constantly monitor the flame color of burners, the readings of gas analyzers and traction gauges, achieving complete combustion of gas with the least excess air. The volume fraction of carbon dioxide (CO2) in exhaust flue gases should be 9-10%, which corresponds to the excess air ratio behind the boiler 1.3-1.4. At the same time, the volume fraction of products of chemical insufficiency of CO + H2 combustion should not exceed 0.2%. The volume fraction of CO2 is set by the commissioning organization depending on the type of fuel, type of boiler and furnace device;

c) observe the dilution in the furnace, while not allowing at least minor pressure, as well as knocking out the flame or combustion gases from the furnace or gas ducts of the boiler. The thrust must be adjusted so that the vacuum in the upper part of the furnace is 520 Pa (0.52 mm of water. article). To control the thrust, use the smoke damper behind the boiler unit, air furnace register, rotary blades of the fan guide vanes and the smoke pump, changing their rotation frequency;

d) distribute air to operating gas burners so that to each gas burner it is supplied in proportion to the gas flow rate through the burner;

e) systematically observe the combustion process and ensure that the gas torch evenly fills the entire furnace chamber and does not fly into the tube bundle so that the end of the torch is clean and does not have smoky tongues; the flare must not contain "flies," and its color must be light straw-yellow. Only completely transparent combustion gases shall be discharged from the boiler stack or boiler plant. Even light and short-term dark smoke should not be allowed.

With large excess air, the volume fraction of CO2 in the flue gases decreases, the torch shortens and acquires a dazzling white color. With a lack of air, the CO2 content increases, the torch lengthens, the flame acquires a dark yellow color, and smoky tongues appear at the end of it.

Control gas and air supply by slow and smooth opening of valves, valves and valves. It is necessary to achieve silent stable operation of burners without flame.

The load of a boiler with several gas burners should be controlled by changing the gas flow rate of all burners or changing their amount; the latter load control is particularly useful for partial mixing injection burners of low capacity (up to 15-20 m3/g). When the load of the individual burners is increased, the gas supply is first increased and then the air supply is increased; when load is reduced, air supply and then gas supply are reduced first.

It must be remembered that overload burners are not allowed to operate, resulting in flame separation from the burner, and low load burners are not allowed to operate, causing the flame to slip. The full-mix injection burners are particularly unsatisfactory at high and low loads.

To increase the length and luminosity of the flame flare, the primary air supply to the burners is reduced and the secondary air supply is increased while the vacuum in the furnace is increased (to avoid incomplete gas combustion).

In order to avoid flame ejection from the furnace and incomplete gas combustion when the boiler load is increased, first the vacuum in the furnace and then the burner load is increased. When the boiler load is reduced, the burner load is first reduced and then the vacuum is reduced.

The so-called heat distortion of the boiler should not be allowed - heating one part of the boiler is much stronger than the other; operating burners should be evenly distributed across the boiler width. It should be remembered that thermal distortion can lead to a boiler accident as a result of a violation of the density of the pipe rolls and welds, a violation of the correct circulation of water in the boiler and a change in the water level.

If all burners go off during operation (as a result of increasing the gas pressure before the burners or stopping the air supply by the fan to the burners), it is necessary to immediately stop the gas supply to the burners, reduce the blast and thrust, ventilate the furnace, gas ducts and air ducts, find out and eliminate the causes of violation of the normal gas combustion mode.

During the operation of the furnace, it is necessary to monitor the absence of gas leaks from idle (off) burners, as well as the absence of gas combustion at the outlet gas slots, which may threaten the burner parts.

4.4 Start of traction machines

When preparing the smoke pump and fan for start-up, it is necessary to:

a) check quality and quantity (level) of oil in bearings;

b) check the correct position of the lubricating rings on the shaft, their correct assembly and ease of rotation;

c) check by manual turning the absence of jamming (jamming) between the impeller and the casing (especially when the boiler is operating on gas, fuel oil and pulverized fuel);

d) check the water cooling system of bearings (reliability of water supply and discharge);

e) check the electrical part and put the rheostat on start-up contacts;

f) check correct installation of rotary blades and dampers (vanes).

In addition, when preparing the smoke pump, the fan for start-up after a prolonged outage, it should be:

a) check condition of foundation, frame and fixing of foundation bolts;

b) check absence of ash wear and warping of blades, disk, rings and casing (smoke pump);

c) check minimum clearance between impeller and casing (30-50 mm), clearance between impeller rings and sides of casing (not more than 10 mm);

d) check condition, absence of cracks and other damages at shafts, hubs, rods, disk, rings, bearings and at couplings;

e) disassemble the bearings, rinse them with kerosene, collect and re-fill them with oil;

f) check (by couplings) the correct alignment of the smoke pump, fan with the electric motor.

Start-up of smoke pump and fan:

a) check whether the shutters (vanes) of smoke pumps and fans are open and their hatches are closed;

b) turn on the electric motor and, following the readings of the pressure gauge, gradually increase the number of revolutions. Immediately check correctness of rotation direction and rotation of lubricating rings;

c) in case of improper direction of rotation, jamming of lubricating rings, strong vibrations of smoke pumps and fans, strong abnormal noise inside them or excessive heating of bearings, stop and eliminate faults and problems.

Smoke and fan care during operation:

a) monitor the ammeter readings and prevent overload of the electric motor. Monitor the heating of the bearings and the motor housing if their temperature exceeds the permissible norm - stop the motor immediately, find out the cause of overheating and eliminate the malfunctions;

b) monitor the action of the water cooling system, the free rotation of the lubricating rings, the prevention of oil heating in bearings above the permissible norm (75 ° С); periodically lower part of oil from bearings and replace it with fresh oil; at least once every two months (and at first more often) completely replace the oil and open the bearings for inspection, cleaning or repair. Observe the condition of the ball bearings.

Stop of smoke pump, fan:

a) switch off the electric motor;

b) close the valves (vanes) of the smoke pump and fan;

c) stop water supply for bearing cooling (release water from cooling system in winter time);

d) when stopping for a long time, release oil from bearing chambers and lubricate friction parts with solidol to prevent them from rusting.

The stop of the smoke pump, fan should occur gradually and slowly; in case of a quick stop, identify the causes of this and eliminate the malfunctions.