1 Scope
This standard specifies the basic requirements of explosion prevention design for coal conveying, storage and pulverized coal preparation of coal-fired power plant, as well as such design for relevant flue, air duct and dust ignition.
This standard is applicable to coal and pulverized coal preparation system of coal-fired power plant, as well as explosion and ignition of pulverized coal cloud in enclosure (such as raw coal bunker, pulverized coal bin, coarse and fine pulverized coal separator as well as cylindrical silo etc.). For coal-fired power plant using multi-fuel ignition of coal and fuel oil or that of coal and fuel gas, it shall comply with this standard for contents related to coal.
This standard is not applicable to enclosure that produces extremely large internal pressure due to external flame or being exposed to other ignition source. If there are explosion prevention requirements of boiler furnace and boiler ignition system, it is not applicable to detonation and unconditional explosion and ignition.
2 Normative references
The following documents contain provisions which, through reference in this standard, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding corrections), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the documents. For undated references, the latest edition of the normative document referred to applies.
GB/T 16426 Determination for Maximum Explosion Pressure and Maximum Rate of Pressure Rise of Dust Cloud
GB 50058 Electrical installations design code for explosive atmospheres and fire hazard
DL/T 435-2004 Code for the Prevention of Pulverized Coal Firing Furnace Explosions in Power Plant Boilers
DL/T 466-2004 Guide for Type Selection for Pulverizers and Pulverizing Systems of Power Station
DL 5000 Technical Code for Designing Fossil Fuel Power Plants
DL/T 5035-2004 Technical Code for Heating Ventilation and Air Conditioning Design of Fossil Fuel Power Plant
DL/T 5121-2000 Technical Code for Design of Thermal Power Plant Air & Flue Gas Ducts/ Raw Coal & Pulverized Coal Piping
DL/T 5145-2002 Technical Code for Design and Calculation of Pulverized Coal Preparation System of Fossil-fired Power Plant
3 Terms and definitions
3.1 Basic conception
3.1.1 Coal spontaneous ignition tendency
It refers to characteristic of difficult degree of coal spontaneous ignition. Coal spontaneous ignition tendency is related to coal's oxygen uptake capacity, moisture capacity, total sulfur content as well as granularity and other characteristics. According to difference of coal's oxygen uptake capacity and total sulfur content, spontaneous ignition tendency may be divided into three grades as showed in table 3.1.1
Classification chart for coal spontaneous ignition tendency Table 3.1.1
Spontaneous ignition tendency grade Spontaneous ignition tendency Coal's oxygen uptake capacity
cm3/g (Dry coal) Total sulfur content (only applicable to high-sulphur coal and anthracite type) %
Lignite and soft coal type high-sulphur coal and anthracite type Whose volatile constituent of dry ash-free basis is ≤18.0%
Ⅰ Easy spontaneous ignition ≥0.71 >1.00 >2.00
Ⅱ Spontaneous ignition 0.41~0.70 ≤1.00 ≥2.00
Ⅲ Difficult spontaneous ignition ≤0.40 ≥0.80 <2.00
3.1.2 Inert gas
It refers to incombustible gas without reaction, and it makes combustible material in system be unable to maintain burning.
3.1.3 Enclosure
It refers to objects enclose coal or pulverized coal, such as room, building, container, facility or pipeline.
3.1.4 Raw coal bunker
It refers to enclosure used to store raw coal.
3.1.5 Cylindrical silo
It refers to cylindrical enclosure used as coal-blending facility, cushioning facility of coal-transporting system and coal-storing facility.
3.1.6 Pulverized coal bin
It refers to enclosure used to store pulverized coal.
3.2 Pulverized coal cloud explosibility
Foreword
1 Scope
2 Normative references
3 Terms and definitions
3.1 Basic conception
3.2 Pulverized coal cloud explosibility
3.3 Explosion prevention of pulverized coal cloud
3.4 Explosion control of pulverized coal cloud
4 Designs
4.1 General provision
4.2 System configuration
4.3Building and structure
4.4 Cylindrical silo and raw coal bunker
4.5 Equipment, duct and component in pulverized coal preparation system
4.6 Duct and fume, air duct design
4.7 Pulverized coal bin
4.8 Dust control unit
4.9 Instrument and control
4.10 Explosion door
4.11 vent discharge duct for explosion door
5 Operation
5.1 General requirements
5.3 Operation
5.3.1 Except pair in-out coal pulverizer, all inflamers supplied by one coal pulverizer of direct firing pulverizing system should be put into operation.
5.3.2 Coal pulverizer shall operate under lowest permissible load, and shall maintain flow velocity of medium in pulverized coal delivering duct be no less than lowest permissible flow velocity.
5.3.3 During operation of band conveyer, all of dust control units installed in coal transportation system shall operate.
5.4 Abnormal operation
5.5 Shutdown
