GB 51020-2014Code for design of ventilation dedusting and fume scrubbing of aluminum smelter (English PDF)

2.0.1 pollution source of fume (dust)

Location where fume (dust) is generated.

2.0.2 harmful gas

Gas emitted in the production process that pollutes the environment.

2.0.3 fume

Process waste gas generated by reduction cells and baking furnaces in the production process.

2.0.4 ventilation

Technical measure by which air is brought into or exhausted from a room by natural or mechanical means in order to meet air environment requirements such as hygiene and safety; it consists of exhaust hoods, fans, ducts, air inlets and air outlets, etc.

2.0.5 dedusting

Technical measure for the cleaning treatment of dust generated in the production process of an aluminium smelter; it consists of gas collecting and dust suction hoods, ducts, dust collectors, dust discharge devices, fans, exhaust stacks, etc.

2.0.6 fume scrubbing

Technical measure for the purification and treatment of the fume emitted by aluminium reduction cells and baking furnaces in the production process.

2.0.7 fume scrubbing system

System works for the treatment of fume from aluminium reduction cells and baking furnaces, consisting of ducts, dust collectors, fans, stacks and system auxiliary devices.

2.0.8 bag filter

Dust collection and purification device that uses bag-shaped or cylindrical filter elements made of filter media to capture the dust in dust-laden gas and to adsorb harmful gases such as hydrogen fluoride (HF) and sulfur dioxide (SO2).

2.0.9 high-voltage electrostatic precipitator

Dust collector that separates dust and tar from the gas by the adsorption action of a high-voltage electric field on charged dust and charged tar droplets. A high-voltage electrostatic precipitator used mainly for treating liquid pitch tar is also commonly called an electrostatic tar precipitator.

2.0.10 standard condition

State of a gas at a temperature of 273.15 K and a pressure of 101.325 kPa. The fume volumes specified in this code are all based on dry gas under standard condition.

3.1 Ventilation

3.1.1 The ventilation of aluminium smelters shall meet the following requirements:

1 The basis of workshop ventilation design shall comply with the relevant provisions of the current national standards "Hygienic standards for the design of industrial enterprises" GBZ 1, "Occupational exposure limits for hazardous agents in the workplace - Part 1: Chemical hazardous agents" GBZ 2.1 and "Occupational exposure limits for hazardous agents in the workplace - Part 2: Physical agents" GBZ 2.2, and of the current national standard "Design code for heating ventilation and air conditioning of civil buildings" GB 50736.

2 Production workshops generating surplus heat and harmful gases shall be provided with ventilation facilities. Production equipment emitting harmful substances shall be enclosed. Pollution sources shall be provided with local ventilation; where hygienic requirements cannot be met, general ventilation shall be added as a supplement.

3 The arrangement of process equipment in the workshop and the building form shall be coordinated with the ventilation design, and surplus heat and harmful gases shall be subjected to protection and treatment.

4 Where surplus heat and harmful substances generated indoors would pollute adjacent rooms, negative pressure shall be maintained indoors. Where the process production has cleanliness requirements for the indoor air, positive pressure shall be maintained indoors.

5 Supply air outlets of the ventilation system shall be arranged upwind of the pollution source, and exhaust outlets shall be arranged downwind of the pollution source.

6 Where rooms requiring ventilation have dust-proof requirements, filtering measures shall be taken for the intake air.

7 The ventilation volume shall be determined according to the emission quantities of surplus heat and harmful substances and the permissible values of the harmful substances. The surplus heat shall include the building cooling load.

8 The emission of harmful substances shall comply with the relevant provisions of the current national standard "Integrated emission standard of air pollutants" GB 16297.

9 The design of smoke control and smoke exhaust systems shall comply with the relevant provisions of the current national standard "Code of design on building fire protection and prevention" GB 50016.

3.1.2 Natural ventilation shall meet the following requirements:

1 Production workshops and auxiliary buildings should adopt natural ventilation;

2 In summer, measures favourable to removing surplus heat and lowering the indoor temperature shall be taken; in winter, measures favourable to using surplus heat to maintain the indoor heating temperature shall be taken. Air inlets and outlets shall be provided with opening and closing measures.

3.1.3 Mechanical ventilation shall meet the following requirements:

1 Production buildings with mechanical exhaust should adopt natural make-up air; where this does not meet the requirements, mechanical air supply should be adopted;

2 Where there are requirements for the room temperature of production buildings with mechanical exhaust, air volume balance and heat balance calculations shall be carried out;

3 Mechanical ventilation systems shall be divided according to the process production flow, the production working time and the nature of the harmful substances exhausted;

4 In workshops simultaneously emitting surplus heat and harmful gases, or emitting only harmful gases with a density lower than that of air, in addition to local exhaust, natural or mechanical exhaust should be taken from the upper zone, with an exhaust volume of not less than 1 air change per hour; where the room height is greater than 6 m, the exhaust volume may be calculated as 6 m3/(h x m2);

5 In workshops emitting dust or harmful gases with a density greater than that of air, exhaust should be taken from the lower zone and supply air should be delivered to the upper zone; 2/3 of the total exhaust volume should be exhausted from the lower zone and 1/3 of the total air volume from the upper zone, and the air change rate shall not be less than 1 air change per hour.

3.1.4 Emergency ventilation shall meet the following requirements:

1 Rooms that may emit large quantities of harmful gases or gases with explosion hazard shall be provided with an emergency ventilation system.

2 Emergency ventilation should be provided jointly by the ventilation system in regular use and the emergency ventilation system, and when an accident occurs the required emergency ventilation volume shall be ensured.

3 For non-enclosed rooms, the emergency exhaust may be provided without a make-up air system. Enclosed rooms shall be provided with a mechanical make-up air system, the make-up air volume shall be greater than 50% of the exhaust volume, and the emergency exhaust system shall be interlocked with the make-up air system.

4 The suction inlets of emergency ventilation shall be located at the positions where the emission of harmful gases or explosive hazardous substances is greatest or where they accumulate most.

5 The exhaust outlets of emergency ventilation shall not be located at positions where persons stay or pass. The horizontal distance between the exhaust outlet and the air intake of the mechanical air supply system shall not be less than 20 m; where it is less than 20 m, the exhaust outlet shall be more than 6 m higher than the air intake.

6 For rooms emitting explosive hazardous substances, where combustible or harmful gas detection and alarm devices are provided, the emergency ventilation system should be started in interlock with them;

7 The emergency ventilation volume should be determined by calculation according to the process design requirements, but the air change rate shall not be less than 12 air changes per hour;

8 The fans of emergency ventilation shall be provided with electrical switches both indoors and outdoors.