Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by and is under the jurisdiction of the National Technical Committee on Hydrogen Energy of Standardization Administration of China (SAC/TC 309).
Safety requirements for pressurized water electrolysis system for hydrogen production
1 Scope
This standard specifies the hazardous and harmful factors, basic safety requirements and requirements concerning environmental conditions, system components, operation and maintenance, operators and emergency response of pressurized water electrolysis system for hydrogen production (hereinafter referred to as hydrogen production system).
This standard is applicable to alkaline water electrolysis systems and proton exchange membrane water electrolysis systems with working pressures greater than or equal to 0.3 MPa and less than or equal to 5.0 MPa.
Note: Any pressure in this standard is gauge pressure.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 150 (All parts) Pressure vessels
GB/T 151 Heat exchangers
GB 2894 Safety signs and guideline for the use
GB 3836.1 Explosive atmospheres—Part 1: Equipment—General requirements
GB/T 4272 General principles for thermal insulation technique of equipment and pipes
GB 7231 Basic identification colors and code indications and safety sign for industrial pipelines
GB 12014 Static protective clothing
GB 12358 Gas monitors and alarms for workplace —General technical requirements
GB 16808 Combustible gas alarm controller
GB/T 19774 Specification of water electrolyte system for producing hydrogen
GB 21146 Personal protective equipment — Occupational footwear
GB/T 24499 Technology glossary for gaseous hydrogen, hydrogen energy and hydrogen energy system
GB/T 27921-2011 Risk management—Risk assessment techniques
GB/T 29639 Guidelines for enterprises to develop emergency response plan for work place accidents
GB 30871 Safety code of special work in chemical manufactory
GB 50030 Code for design of oxygen station
GB 50057 Code for design protection of structures against lightning
GB 50058 Code for design of electrical installations in explosive atmospheres
GB 50177 Design code for hydrogen station
GB 50217 Standard for design of cables of electric power engineering
HG 20202 Code for construction and acceptance of degreasing project
JB/T 2379 Metallic tube electric heating elements
TSG D0001 Pressure pipe safety technology supervision regulation for industrial pressure pipe
TSG 21 Supervision regulation on safety technology for stationary pressure vessel
3 Terms and definitions
For the purposes of this standard, the terms and definitions specified in GB/T 24499 as well as the followings apply.
3.1
hazardous and harmful factors
factors that may cause casualties, affect people's physical health, and lead to diseases
3.2
hazardous area
area where preventive measures required shall be taken for the structure, installation and application of electrical equipment due to the quantity of explosive mixture that may appear or expect to appear is sufficient
3.3
risk assessment
overall process comprising risk recognition, risk analysis and risk evaluation
3.4
oxygen-enriched atmosphere
environment in which the volume fraction of oxygen in the air is larger than 23.5%
3.5
hot work
unconventional operations that may produce flames, sparks or hot surfaces in the fire forbidden area other than the process equipment that directly or indirectly produces open flames
Note: For example, operations using electric welding, gas welding (cutting), blowtorch, electric drill, grinding wheel, etc.
4 Hazardous and harmful factors of hydrogen production system
4.1 Composition of hydrogen production system and hazardous and harmful factors of unit equipment
The composition of hydrogen production system is determined by the usage and purity of produced hydrogen/oxygen. Refer to Annex A for block diagram of typical hydrogen production system.
Refer to Annex B for major hazardous chemicals and hazardous and harmful factors of unit equipment of the hydrogen production system.
4.2 Leakage
Hydrogen tends to leak through porous materials, mounting surfaces or sealing surfaces. Hydrogen will diffuse rapidly after being leaked, the process of which is invisible to the naked eyes and will enlarge the area contaminated by leakage.
Electrolyte in alkaline water electrolysis system may leak for various reasons.
4.3 Fire and explosion
Hydrogen fires or explosion may occur when the mixture of hydrogen and air or oxygen reaches the flammable or explosive limit at the presence of an effective ignition source. Hydrogen production system may have hydrogen/air (oxygen) mixture and ignition source,
including but not limited to the following scenarios:
a) Defects in the structure, components or assembly of the water electrolyser, resulting in the mixing or outward leakage of inside hydrogen and oxygen, or even causing the inside liquid being sprayed out with the gas and atomized in serious cases of leakage;
b) Defects in materials, design, manufacture and installation of pressure vessels, pipelines and safety accessories, failure to inspect pressure vessels, pipelines and safety accessories on schedule, and absence or failure of safety accessories, causing system leakage and even physical or chemical explosion;
c) For the gas-liquid processing unit communicated at the bottom of the hydrogen-oxygen separator, abnormality of liquid level control system, making hydrogen and oxygen mixed;
d) Abnormality of gas purity analysis instrument and failure to detect the gas purity out of limits in time; failure of hydrogen leak detection device or mechanical ventilation system, resulting in hydrogen content out of limits in the environment;
e) Insufficient replacement of the hydrogen system prior to use or reverse connection of the positive and negative poles of the power supply for the water electrolyser, causing mixing of hydrogen with air or oxygen;
f) Ammonia gas containing excessive oxygen enters the deoxygenation tower of the ammonia purifier, and is compounded with oxygen to form water under the action of a catalyst to release a large amount of heat, thus generating excessive high temperature in the deoxygenation tower;
g) Hydrogen containing impurities flows too fast, and operators do not wear anti-static workwear, which may generate electrostatic sparks;
h) Oxygen in contact with grease or impurity in high-speed oxygen flow may cause combustion;
i) Explosion-proof tools are not used during operation, friction and impact of which generate sparks;
j) Lightning protection design of the production plant area fails to meet the requirements of specifications, resulting in lightning damage to the equipment and hydrogen leakage and ignition;
k) Electrical equipment generates arc or spark due to leakage, short circuit, overload and excessive contact resistance; the explosion-proof grade of electrical equipment in the hazardous area does not meet the use requirements, and may also become the ignition source;
l) Rain or other electrical conductors fall on the water electrolyser, causing short circuit and damage to the electrolyser body, which may lead to fire or explosion;
m) During maintenance, failure to take effective isolation measures between the maintenance equipment and the production system in use, incomplete replacement before hot work, unrepresentative sampling analysis or inaccurate analysis data may cause fire or explosion.
4.4 Asphyxia
Hydrogen is a simple asphyxiating gas. In the air with a high concentration of chlorine, reduction in the partial pressure of oxygen will result in anoxic asphyxia.
4.5 Electric shock
Equipment or facilities in the hydrogen production system that may cause electric shock include water electrolyser, rectifier transformer, rectifier cabinet, electrical cabinet, motor, power transmission copper bars, etc. During equipment operation and maintenance, operators are in danger of electric shock.
4.6 Burn and scald
The working temperature range of the water electrolyser and some ancillary equipment in the hydrogen production system is 60℃ to 90℃, the working temperature of the deoxygenation catalyst bed of the hydrogen purifier may reach 150℃, and the regeneration temperature of the drying bed (temperature swing adsorption) of the hydrogen purifier may reach 350℃. Human will get scalded if directly contacting the surface of such equipment.
Potassium hydroxide or sodium hydroxide involved in alkaline water electrolysis system is highly corrosive, which may cause chemical burns in direct contact with skin and eyes.
4.7 Mechanical injuries
Mechanical injuries from hydrogen production system mainly refer to injuries caused by direct contact between moving parts of mechanical equipment and human body.
5 Basic requirements
5.1 It is required to avoid the accumulation of hydrogen/air (oxygen) mixture in a confined space and to control the ignition source.
5.2 Where possible, the number of personnel in hazardous environment shall be reduced and such personnel shall stay for a shorter time.
5.3 Risk assessment shall be conducted for hydrogen production system. One or more technologies in Annex B of GB/T 27921-2011 should be adopted for risk assessment. The risk assessment shall show that the countermeasures adopted will control the adverse effects of risks to an acceptable level.
5.4 Relevant operation procedures shall be prepared.
5.5 Operators shall receive post safety education and operation skill trainings.
5.6 Emergency response plans shall be prepared.
6 Environmental conditions
6.1 General requirements
6.1.1 The hydrogen production system shall be designed and installed in consideration of the influence of the environmental conditions at the user site on the safe operation of the equipment, such as environmental temperature, environmental humidity, altitude, seismic fortification intensity, etc.
6.1.2 The layout of hydrogen production system shall meet the provisions of GB 50177.
6.1.3 The use area of hydrogen production system shall be well ventilated to ensure that the hydrogen content in the air does not exceed 1% (volume fraction).
6.2 Hydrogen production system installation site
6.2.1 The fire hazard category of the hydrogen production system shall be "A", and the safety facilities at its installation site shall meet the provisions of GB 50177.
6.2.2 The hydrogen production system and its surrounding areas shall be set up with forbidden zones to prohibit irrelevant personnel from entering.
6.2.3 Hydrogen production sites shall be free of sundries, with the access unblocked.
6.2.4 In areas with alkali liquor, including the vicinity of sampling points for loading/unloading, storage and analysis of alkaline electrolyte, flushing and eye washing facilities shall be provided and equipped with boric acid solution with a concentration of 2% to 3%.
6.2.5 Emergency lighting should be provided at the hydrogen production sites.
6.2.6 Safety signs conforming to GB 2894 shall be set up at the hydrogen production sites.
7 Equipment and pipeline
7.1 General requirements
7.1.1 Oxygen recovery equipment, pipelines and accessories of hydrogen production system shall be designed, manufactured, installed and accepted in accordance with GB 50177 and GB/T 19774.
7.1.2 For the hydrogen production system in which oxygen is directly discharged into the equipment housing or room, oxygen shall be effectively diluted by ventilation flow to avoid the formation of an oxygen-enriched atmosphere.
7.1.3 The materials for equipment and pipelines shall be selected in comprehensive consideration of factors such as use conditions (e.g. medium characteristics, working temperature, working pressure, etc.), material properties (mechanical properties, technological properties, physical properties and chemical properties), equipment manufacturing process and economic rationality.
7.1.4 The equipment and pipelines shall be such arranged as to be convenient for operation and maintenance and personnel evacuation in case of emergency.
7.1.5 Condensate water in hydrogen equipment and pipelines shall be discharged outdoor through drainage water seal.
7.1.6 Preventive measures shall be taken for stress and displacement caused by thermal expansion and contraction of equipment and pipelines.
7.1.7 Degreasing of equipment, pipelines, valves and accessories in contact with oxygen shall meet the provisions of GB 50030 and HG 20202.
7.1.8 According to the environmental conditions and process requirements, the thermal insulation measures for equipment and pipelines shall meet the provisions of GB/T 4272.
7.1.9 Where there is danger of personnel falling from high place on equipment and pipelines, ancillary facilities such as escalators, platforms, fences and tie-down devices shall be provided.
7.1.10 All rotating equipment shall be equipped with protective hoods or other protective measures.
7.1.11 Control measures such as sound insulation, noise reduction and shock absorption shall be adopted for equipment with high noise.
7.1.12 Equipment and valves shall be numbered uniformly; safety signs of pipelines shall meet the provisions of GB 7231.
7.2 Single equipment
7.2.1 Water electrolyser
The performance parameters and structure of the water electrolyser shall be based on the basic requirements of reducing electricity consumption per unit hydrogen, decreasing manufacturing cost and prolonging service life. It is required to reasonably select the structural style of the water electrolyser, its electrolytic cells and electrode, diaphragm construction, coating and material, and to control the assembly process of the water electrolyser so as to eliminate the leakage risk.
The water electrolyser shall be mounted by single-end fixing method.
7.2.2 Pressure vessels
The pressure vessels of hydrogen production system are mainly used for gas-liquid separation, cooling, heating and storage. The materials, design, manufacture, inspection and acceptance of pressure vessels shall meet the provisions of TSG 21, GB/T 150 and GB/T 151.
In cold and severe cold areas, corresponding anti-freezing measures shall be taken according to specific conditions at the bottom of outdoor moisture-containing tanks.
7.2.3 Hydrogen purifier
Heat insulation measures shall be taken for hydrogen purifier. The inlet of hydrogen purifier should be equipped with flow meter. The temperature control and valve switching in the hydrogen purification process should be controlled by automatic control devices.
7.2.4 Circulating pump and make-up pump
The flow, lift, working temperature and working pressure of the pump shall meet the process requirements. The material of the pump in contact with the conveying medium shall be suitable for alkali liquor/pure water. Pumps shall meet the provisions of 8.1.2 if they are installed in hazardous areas.
7.2.5 Cut-off/shut-off valve
Cut-off/shut-off valve shall meet the provisions of 50177 and GB/T 19774. If the electric valve is installed in hazardous areas, it shall meet the provisions of 8.1.2.
7.2.6 Pressure relief device
Safety valves shall be fully enclosed and shall not be used until they are calibrated and qualified with lead seals. The safety valves shall be installed vertically close to the protected equipment where it is convenient for inspection and maintenance.
7.2.7 Back-fire relief valve
Back-fire relief valves shall be installed in the hydrogen blow-down pipes. Their arrangement shall conform to the relevant requirements of GB 50177.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Hazardous and harmful factors of hydrogen production system
5 Basic requirements
6 Environmental conditions
7 Equipment and pipeline
8 Electrical and instrument control
9 Operation and maintenance
10 Operators
11 Emergency response
Annex A (Informative) Block diagram of typical hydrogen production system
Annex B (Informative) Major hazardous chemicals and hazardous and harmful factors of unit equipment of the hydrogen production system
Bibliography
