Hydrogen production and high purity nitrogen production

Part A Hydrogen Production

There are four main methods of hydrogen production (excluding hydrogen recovered from industrial waste gas) in China:

1. Natural gas (including naphtha, heavy oil, refinery gas and coke oven gas, etc.) is converted into hydrogen by steam conversion. Natural gas steam conversion is a more traditional technology, and it was often used in large-scale hydrogen supply (above 5000Nm3 / h). According to the characteristics of scattered hydrogen users and small scale in China, a low-investment and low-consumption natural gas steam conversion hydrogen production technology has been developed, which is very suitable for small and medium-scale hydrogen demand occasions. In natural gas-rich regions, natural gas steam conversion is the best option.

2. Coal (including coke and petroleum coke) is converted into hydrogen. The cost of producing hydrogen from coal is low, but due to the long process of producing hydrogen from coal, it is usually suitable for medium and large-scale hydrogen production units (greater than 1000Nm3 / h). For areas without natural gas resources and the scale of the installation is large, it is very suitable to choose coal gasification hydrogen production technology.

3. Methanol or ammonia cracking to produce hydrogen. The process of hydrogen production from methanol or ammonia cracking is relatively simple, easy to operate, and easy to control, but it is not encouraged in China due to enrivornmental protection. In areas where there is sufficient methanol supply and the demand for hydrogen is relatively small (less than 200Nm3 / h), it is suitable.

4. Hydrogen production from water electrolysis. Hydrogen production from water electrolysis is the most traditional hydrogen production method, with high energy consumption and high cost. High-performance and low-cost hydrogen production technology by electrolytic water is the current research focus. 

Part B High purity nitrogen production

For high purity nitrogen such as 99.999%, 99.9995% and 99.9999%. When big flow rate is needed, then the cryogenic air separation unit is more suitable. For some customers only require small flow rate not more than as 1000 Nm3/hr, onsite Nitrogen Generation with purifier is popular.

Option one, hydrogen purifier

To reduce total power consumption, normally 99.5%-99.9% nitrogen is produced using PSA technology, starting from Air Compressor, after air treatment part which normally include dryer, filters and oil remover, then enters one air tank. After the air tank, compressed air enters PSA adsorption towers to get 99.5%-99.9% purity nitrogen. The produced nitrogen enters one nitrogen buffer tank to buffer pressure and flow rate. After this tank, nitrogen enters one hydrogen nitrogen mixer to get rid of residual oxygen with the reacton of hydrogen with oxygen. During this process, water is generated, which is removed by dryers. With this method, high purity nitrogen is achieved.

Option two, carbon purifier

Also the 99.5%-99.9% purity nitrogen is achieved same as above process. Just after the nitrogen buffer tank, nitrogen goes into one oxygen remover which is filled with carbon. With the help of catalyst, the carbon reacts with oxygen to produce carbon dioxide. In this way, high purity nitrogen is achieved. For process does not allow much carbon dioxide, then the CO2 is removed by another CO2 remover. After its treatment, the carbon dioxide content can be less than 10 ppm even lower.