Characteristics of electrolyzer hydrogen production equipment
As a kind of electrical conversion equipment, electrolyzer is the key equipment of renewable energy electrolysis water hydrogen production technology. When it is used to stabilize the fluctuation of renewable energy, it needs to have strong adaptability to the unstable power output of renewable energy. Alkaline electrolyzers are currently electrolyzed water hydrogen production equipment for large-scale engineering applications, and have the advantages of mature technology and low cost.
As a special electrical equipment, alkaline electrolyzer has its particularity. The characteristics and working constraints of alkaline electrolyzers can be summarized as follows:
1) Start-stop feature
When the electrolyzer starts up, because the temperature of the electrolyzer is not high enough to meet the temperature conditions for hydrogen production, the power consumed at this time is used to generate heat to increase the temperature of the electrolyzer; Hydrogen is generated, and the power at this time is the thermal insulation power of the electrolyzer. Therefore, it takes a long time to start the alkaline electrolytic cell, and when the electrolytic cell is stopped, the power can be instantly reduced to zero, which can be regarded as an interruptible load.
2) Thermal insulation properties
When the electrolytic cell array is out of operation, the environmental control device works, and the electrolytic cell can keep the temperature unchanged for a certain period of time T. This feature guarantees the ability of the electrolyzer to be put into service immediately after a certain period of downtime.
3) Adjustment characteristics
The electrolytic cell can quickly adjust the power in a wide range of ms-level time from high temperature and high power point to low temperature and low power point, and it takes min level time to adjust from low temperature and low power point to high temperature and high power point.
4) Hydrogen safe operating power
When the electrolyzer is in low-power operation, due to the characteristics of the material inside the electrolyzer, the operating power of the electrolyzer cannot be lower than a certain limit, otherwise there is a risk of hydrogen and oxygen inter-connection exceeding the explosion limit. The limit is generally the electrolyzer. 20%~25% of the rated power of the slot.
At the same time, because the electrolyzer device is an electrical conversion device, its reaction has a certain buffer time, so in practice, the electrolyzer can run below the hydrogen safety power limit for a short time, and the duration varies from several minutes according to the capacity of the electrolyzer.
5) Adjustment range (overload characteristic)
When the electrolyzer is working, its power can exceed the rated power for a short time, reaching 110%~130% of the rated power. Using this feature, the configuration capacity of the electrolyzer can be reduced.
At present, the manufacturing level of alkaline electrolyzers is still in the hundreds of kilowatts to megawatts. In large-scale hydrogen production engineering applications, multiple single electrolyzers are generally required to be connected in parallel to form an electrolyzer array. At present, domestic and foreign scholars have carried out in-depth research on the performance improvement of the alkaline water electrolysis hydrogen production system mainly from the two aspects of device manufacturing and integrated application control strategy.
Improving the manufacturing technology of alkaline electrolyzed water hydrogen production equipment is a long-term research process, and it is difficult to achieve a qualitative breakthrough in the short term, and the control strategy is throughout. Advanced energy management and control strategies have been proved to be feasible to improve the equivalent service life and power regulation characteristics of alkaline electrolysis systems and are worthy of study.