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GB/T 16508.6-2013 English PDF (GBT16508.6-2013)

GB/T 16508.6-2013 English PDF (GBT16508.6-2013)

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GB/T 16508.6-2013: Shell boilers -- Part 6: Combustion systems

This Part of GB/T 16508 specifies the technical requirements for combustion systems of shell boiler. This Part is applicable to combustion systems of shell boiler defined in the scope of GB/T 16508.1.
GB/T 16508.6-2013
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 27.060.30
J 98
Shell Boilers -- Part 6: Combustion Systems
ISSUED ON: DECEMBER 31, 2013
IMPLEMENTED ON: JULY 1, 2014
Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the PRC;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 5
4 Combustion Systems of Liquid and Gaseous Fuels ... 6
5 Layer Combustion System of Solid Fuel ... 16
Shell Boilers -- Part 6: Combustion Systems
1 Scope
This Part of GB/T 16508 specifies the technical requirements for combustion systems of shell boiler.
This Part is applicable to combustion systems of shell boiler defined in the range of GB/T 16508.1, including:
a) The fuel inlet pipeline, air supply system, smoke discharge system and combustion equipment of liquid- and gas-fuel fired boilers as well as all the relevant control and monitoring equipment;
b) The air supply system, smoke discharge system, combustion equipment and dust (slag) removal device of solid fuel fired grate firing boiler as well as all the relevant control and monitoring equipment.
2 Normative References
The following documents for the application of this document are essential. Any dated reference, just dated edition applies to this document. For undated references, the latest edition (including any amendments) applies to this document.
GB 13271 Emission Standard of Air Pollutants for Boiler
GB/T 16508.5 Shell Boilers - Part 5: Safety Appurtenances and Instruments GB 17820 Natural Gas
GB/T 18342 Specifications of Coal for Chain and Travelling Grate Stoker Boiler
GB/T 21923 General Testing Rules for Solid Biofuels
JB/T 3271 Specification for Travelling Grate Stokers
JB/T 3726 General Specification for Boiler Slag Removed Equipment
CUT off fuel supply. Restoration requires manual intervention.
3.6
Relative density
The ratio of gas density to dry air density under the same pressure and temperature condition.
3.7
Auxiliary combustion system
The combustion-supporting system arranged to ensure safe ignition and stable combustion.
3.8
Ignition device
The auxiliary equipment used to ensure safe ignition of the fuels.
3.9
Rate of riddlings
The mass ratio of the average grate coal leakage (including ash leakage) per hour to the coal consumption during test duration, expressed as a percentage.
3.10
Uneven air distribution coefficient along grate horizontal
The index for measuring the air distribution evenness performance of air chamber along grate horizontal, expressed as a percentage.
4 Combustion Systems of Liquid and Gaseous Fuels
4.1 Fuel
4.1.1 Basic requirements
4.1.1.1 Without impacting the safe operation of the combustor, the liquid fuel shall permissible pressure (but not less than 4kPa) by adopting the air or inert gas; c) The gas pipeline shall be implemented with necessary overpressure protection through a safety shut-off valve and a pressure release valve;
d) The inlet of gas control valve shall be installed with filter device, which may be integrated with the downstream gas control valve. The pore size of the filter shall not be larger than 1.5mm; and the inlet and outlet of the filter shall be installed with permanent pressure measuring point;
e) As for boilers fuel for fuels with high carbon monoxide content such as blast furnace gas, coke oven gas and the like, the gas system shall be equipped with online monitoring device for carbon monoxide;
f) Manual rapid cut-off valve shall be arranged at the upstream of every automatic control valve in the main gas control valve system so as to cut off the air source of the combustor quickly. Manual rapid cut-off valve shall be installed in the site which is safe and convenient for operation.
4.1.3 Measurement of fuel
Each boiler shall be installed with instruments for indicating, integrating and recording the fuel quantity.
4.2 Air supply system
4.2.1 The pressure measuring device of air supply shall be arranged before every combustor on the air supply pipeline in case a fan is shared by several combustors. 4.2.2 As for the combustion system with multiple combustors, in case the air required for combustion is provided by shared air supply equipment, a cut off device shall be arranged at the air pipe of every combustor. The requirements for cut off device are as follows:
a) The switching position of cut off device shall be clearly indicated; b) In case the fuel supply of combustor is cut off, the air supply shall be cut off (if necessary, only the minimum opening is allowed) automatically at the same time.
4.3 Smoke discharge system
4.3.1 The smoke discharge system of boiler shall possess favorable sealing performance.
a) The combustors shall be equipped with flame detector and able to verify whether the flame is established;
b) The installation site of flame detector shall prevent it from the interference of external signal;
c) On such occasion where the ignition flame and main flame are respectively arranged with independent flame detectors, the ignition flame shall not impact the detection of main flame.
4.4.2.3 As for pressure atomized fuel oil combustor with rated fuel oil not greater than 100kg/h, safety shut-off valve shall be installed between the fuel oil pump and the nozzle; besides, an integrated structure may be adopted for safety shut-off valve and the fuel oil pump and it shall meet the following requirements:
a) The single-stage combustor shall be arranged with at least one set of safety shut-off valve;
b) As for two-stage or multi-stage control combustor, each nozzle shall be arranged with one set of safety shut-off valve;
c) As for the combustor equipped with return-fuel oil nozzle, both its fuel oil supply pipe and return fuel oil pipe shall respectively be arranged with one set of safety shut-off valves;
d) If the nozzle shut-off valve, through test, may serve as the safety shut-off device, then both the fuel oil supply pipe and the return fuel oil pipe may respectively be arranged with nozzle shut-off valves;
e) If the fuel oil atomizer adopts the return-fuel oil nozzle and the fuel oil quantity is greater than 30kg/h, then the fuel oil pressure monitoring device shall be arranged on the return fuel oil pipe to monitor the pressure within the fuel oil return pipe.
4.4.2.4 As for pressure atomized fuel oil combustor with its rated fuel oil being greater than 100kg/h, safety shut-off valve shall be installed between the fuel oil pump and the nozzle, and an integrated structure may be adopted for safety shut-off valve and the fuel oil pump, which shall meet the following requirements:
a) Two safety shut-off valves in series arrangement shall be arranged on the fuel oil supply pipe, of which one can be shut off quickly and the other can serve as the final control part of the heat input for combustion chamber and must be shut off within 5s;
4.4.2.8 The ignition safety time and extinction safety time of fuel oil and gas combustor shall be in accordance with the relevant requirements of GB/T 16508.5. 4.4.2.9 Before the ignition of combustor, the combustion chamber and flue must be pre-purged.
4.4.2.9.1 The pre-purging time and pre-purging air volume of fuel oil combustor shall meet the following requirements:
a) As for the combustor with the rated fuel oil quantity not greater than 30kg/h, it shall ensure that the fan pre-purges for at least 5s in full open state; b) As for the combustor with the rated fuel oil quantity greater than 30kg/h, its pre- purging air volume may be less than the air flow under rated output thermal power, and the pre-purging time shall be in inverse proportion to the air flow; however, the pre-purging time shall not be less than 15s and the purging air volume shall not be less than 50% of the air volume required for the maximum input heat of the corresponding boiler.
In addition to meeting the requirements of items a) and b) of this article, the pre-purging time and pre-purging air volume shall also meet the design requirements of the matching boiler.
4.4.2.9.2 The pre-purging time and pre-purging air volume of the gas combustor shall meet the following requirements:
a) The pre-purging shall be carried out for not less than 20s with the air flow under rated output thermal power;
b) In case the pre-purging is carried out with the air flow under the thermal power less than the rated output, the pre-purging time shall be in inverse proportion to the air flow and the minimum purging air flow shall not be less than 50% of the rated air flow.
In addition to meeting the requirements of items a) and b) of this article, the pre-purging time and pre-purging air volume shall also meet the design requirements of the matching boiler.
4.4.2.10 The initiating thermal power of fuel oil and gas combustor shall meet the relevant requirements of GB/T 16508.5.
4.4.2.11 Under the following circumstances, the combustor shall automatically cut off the fuel supply within the safety time and the system shall achieve safety interlocking; which the air flow doesn?€?t change along with the gas flow, their air/gas control shall meet one of the following requirements:
a) Adjust the air first when turning up the fire and adjust the gas first when turning down the fire;
b) The gas shall not be surplus during adjusting.
4.4.2.13 For the gas control valve system equipped with bleeding device, the bleeder diameter shall not be less than 25% of the effective pore size of the upstream main gas control valve.
4.4.2.14 During closing of the gas burner system, the air supply system shall not shut down automatically before the gas control valve system closes.
4.4.2.15 Safe interlocking shall be ensured whenever the combustor powers off during initiating and operation, and the combustor may only be re-started when the power supply is reset or cut off and restored manually.
4.4.2.16 Distinct warning signs shall be arranged at the position equipped with high- voltage ignition device.
4.4.2.17 Inspection holes shall be arranged at the combustion chamber or combustor so as to observe the flame of the ignition device and combustor. The measures for protecting the safety of inspection personnel shall be taken where hot fume gas may escape.
4.4.2.18 The combustion load of the combustor shall be automatically controlled. 4.4.2.19 As for steam boiler with rated evaporation greater than 20t/h or hot-water boiler with rated thermal power greater than 14MW, the recording instrument of the temperature and pressure of gas and fuel oil shall be installed.
4.4.3 Energy-saving requirements for the combustor
4.4.3.1 If the combustor operates under rated load, the excess air coefficient shall be less than 1.15, and 1.5 if it operates under minimum load.
4.4.3.2 The combustor shall be installed with air conditioner; if damper regulator is equipped, the place of the air damper shall be clearly indicated.
4.4.3.3 Regulating device of fuel oil flow shall be adopted where the rated output thermal power of fuel oil combustion equipment is greater than or equal to 4.2MW, and its output power shall be continuously adjustable within specified range. The fuel oil b) Product performance description (including working curve);
c) Installation requirements;
d) Detailed description of operating methods;
e) Maintenance description;
f) Warnings and precautions.
5 Layer Combustion System of Solid Fuel
5.1 Fuel
5.1.1 Fuel requirements
Fuel coal of chain grate boiler shall meet those specified in GB/T 18342 and the design requirements of the boiler; solid biofuel shall meet those specified in GB/T 21923 and the design requirements of the boiler; other fuels shall be adapted to combustion equipment and meet the design requirements of the boiler.
5.1.2 Measurement of fuel
Steam boiler with rated evaporation greater than 4t/h or hot-water boiler with rated thermal power greater than 2.8MW shall be installed with fuel amount indication, integrating and recording instruments.
5.2 Air supply system
5.2.1 Air duct (including bearing air box of grate device) shall be able to bear mechanical load generated during operation period.
5.2.2 The air duct shall be sealed; in case the boiler is equipped with air preheater, effective thermal insulation shall also be carried out for the hot air duct. 5.2.3 As for combustion system equipped with primary and secondary air, air supply mix ratio should be monitored.
5.2.4 Supply duct shall be arranged with air distribution adjustment and shutoff devices.
5.2.5 The following operating parameters of the air supply system shall be monitored to meet the requirements of safe and energy-saving operation.
5.4.1 General requirements
5.4.1.1 Combustion equipment shall be adapted to boiler structure and complete continuous, stable and complete combustion under design operating conditions. Chain grate shall meet the requirements of JB/T 3271; reciprocating grate shall meet the requirements of JB/T 9620; other types of grate equipment shall comply with the relevant contents of JB/T 3271 and meet the design requirements of the boiler. Water- cooled wall of water cooled oscillating grate shall ensure the water circulation reliability and pressure-bearing safety and possess the anti-vibration and anti-fatigue abilities. 5.4.1.2 Chain grate combustion equipment shall be installed with grate speed display instrument.
5.4.1.3 All control and protective devices related to safety shall be subjected to functional test before application.
5.4.1.4 Access door shall be arranged at proper place.
5.4.2 Safety protection
5.4.2.1 General requirements
5.4.2.1.1 Boiler combustion equipment should be arranged with failure outage alarm and protective devices.
5.4.2.1.2 Security functions related to ignition, start, operation and shutdown of combustion equipment shall be described in a detailed way in the operation instructions.
5.4.2.2 Flue purging
5.4.2.2.1 Before boiler ignition, furnace, flue gas duct and flue gas treatment system shall be purged effectively.
5.4.2.2.2 In case electric deduster is adopted for the boiler, during flue purging, electric deduster shall stop operating.
5.4.2.2.3 During purging, fuel shall not be fed into the boiler.
5.4.2.2.4 Under the premise of ensuring the safe ignition of the boiler, flue purging may not be carried out.
5.4.2.3 Safety requirements of ignition process
a) Failure of combustion equipment or slag removal equipment;
b) Failure of safety control equipment;
c) Force draft fan or induced draft fan works abnormally;
d) Control parameters related to the safety of the boiler (such as water level, temperature, pressure, etc.) exceed limit;
e) Other conditions specified in the boiler operating instructions that boiler emergency shutdown is necessary.
5.4.2.5.2 In case the boiler combustion system is shut down, the fuel feed shall be stopped at the same time.
5.4.2.5.3 After shutting the boiler down according to normal boiler shutdown procedure or urgently shutting the boiler down according to the requirements of 5.4.2.5.1, the residual heat shall be dissipated urgently.
5.4.3 Energy-saving requirements
5.4.3.1 Granularity, moisture, ash content, calorific value, coke residue characteristic and ash fusibility of selected fuel shall meet the requirements of corresponding combustion equipment so as to improve the combustion efficiency.
5.4.3.2 Grate plate (or grate bar) of various grates shall enable the grate to maintain venting area with appropriate ratio and shape so as to reduce the rate of riddlings. 5.4.3.3 In case the horizontal width of grate is large, the grate type and air distribution structure with low uneven air distribution coefficient along grate horizontal should be selected so as to improve the combustion efficiency.
5.4.3.4 As for chain grate boiler adopting fuel coal as fuel, in order to improve the combustion efficiency, layer coal feeder should be selected according to boiler and fuel conditions.
5.4.3.5 Coal (material) uniform-distribution device should be adopted so as to reduce the influence of uneven fuel particle size in transverse direction of grate on ventilation and combustion.
5.4.4 Technical document of combustion equipment
5.4.4.1 When leaving the factory, the combustion equipment shall possess at least the following accompanied information:

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