Equipment Structure and Components

Equipment Base Frame: Constructed from assembled profiles, divided into four sections: Regeneration System, Purification System, Chiller Unit, and Scrubbing Device.

1. Main Circuit Process (Purification System)

The recovered hydrogen is preliminarily cooled and dedusted by the pre-furnace scrubbing device, then piped to the system inlet. It enters the hydrogen inlet buffer tank, where it mixes with an appropriate amount of make-up hydrogen for buffering. It is then pressurized by two parallel Roots blowers, passes sequentially through the primary and secondary heat exchangers for condensation and dewatering, and then enters the adsorption drying tower (containing desiccant: molecular sieves) for dehumidification. This process achieves a dew point of ≤ -60°C for the recovered and purified hydrogen. Finally, it passes through the hydrogen outlet buffer tank for buffering and filtration before being supplied to the reduction furnace.

To ensure continuous purification and the reuse of the desiccant, the system is equipped with two drying towers. While one tower is operating normally, the other is undergoing desiccant regeneration (dewatering) on standby. The saturated desiccant is regenerated using heating dehydration and cooling methods.

(1) Purification System

The system is equipped with two Roots blowers. During actual production, the blowers can be manually started/stopped as needed. During full-load normal production, a combination of fixed frequency + self-adjusting frequency mode is used: one blower outputs at a set frequency, while the other automatically adjusts its frequency based on the system's set pressure. This method effectively controls the operating cost of the purification system, thereby reducing the unit power consumption during product production. The drive motors are explosion-proof variable frequency motors equipped with inverters (explosion-proof level IICT4) to prevent overload burnout. The blower inlets are equipped with pipeline filters to prevent particulate debris in the pipeline and gas from entering the pump cavity, which could cause rotor seizure and damage. The blowers use imported bearings and helical gear transmission.

Schematic diagram of blower pressurization working principle (omitted in text)

(2) Piping and Main Accessories

All gas pipelines in the equipment are made of 304 stainless steel, equipped with independent adjustable pipe supports for easy on-site assembly, disassembly, and fixation. Rubber expansion joints are installed at the blower inlet and outlet positions to reduce the impact of vibration sources on the equipment piping, lower the risk of weld leakage, and facilitate valve installation. Main accessories in the piping system, such as various control valves, butterfly valves, pressure sensors, flow meters, pressure gauges, and thermometers, are from well-known domestic brands.

The heat exchanger tubes use 304 stainless steel tubes specifically for heat exchangers, and the tube shells are made of seamless alloy steel tubes. The optimized tube layout ensures continuous heat exchange between the medium in the tube side and shell side. The improved end-face sealing flange structure prevents leakage of the tube bundle due to different cold and hot states.

(3) Hydrogen/Nitrogen Make-up Pipeline

The hydrogen/nitrogen make-up pipeline is equipped with an automatic switching valve. In case of sudden power/gas failure, the system will automatically switch from the hydrogen make-up pipeline to the nitrogen make-up pipeline.

(4) Automatic Drainage for Separator

The gas-water separator is equipped with a magnetic flip-plate level gauge. When the liquid level in the drain tank reaches the set drainage value, the drain valve automatically opens to drain the storage tank. When the liquid level reaches the lower limit, the drain valve automatically closes, maintaining the water seal effect at all times.

2. Regeneration Circuit Process (Regeneration System)

The regeneration hydrogen is circulated solely within the regeneration system by a dedicated regeneration blower. Dry hydrogen enters the regeneration system, is pressurized by a Roots blower, and sent to an electric heater for heating. It then enters the drying tower, where the heated regeneration hydrogen removes the moisture absorbed onto the desiccant during the previous cycle. This moisture-laden gas is then cooled via a heat exchanger and dewatered by a condenser before being recirculated in the regeneration system by the regeneration Roots blower.

The circulation capacity of the Roots blower used in the regeneration system in this design is greater than that of the purification system blower, facilitating rapid dehydration of the molecular sieve in the regeneration tower and improving water removal efficiency.

(1) Piping and Main Accessories

All gas pipelines in the equipment are made of 304 stainless steel, equipped with independent adjustable pipe supports for easy on-site assembly, disassembly, and fixation. Rubber expansion joints are installed at the blower inlet and outlet positions to reduce the impact of vibration sources on the equipment piping, lower the risk of weld leakage, and facilitate valve installation. Main accessories in the piping system, such as various control valves, butterfly valves, pressure sensors, flow meters, pressure gauges, and thermometers, are from well-known domestic brands.

The heat exchanger tubes use 304 stainless steel tubes specifically for heat exchangers, and the tube shells are made of seamless alloy steel tubes. The optimized tube layout ensures continuous heat exchange between the medium in the tube side and shell side. The improved end-face sealing flange structure prevents leakage of the tube bundle due to different cold and hot states.

Filtration Buffer Device: Filter devices are installed at the inlet and outlet of the drying tower to prevent broken molecular sieves from escaping the tower and entering other parts of the system during operation.

(2) Hydrogen Outlet Buffer Tank

Located on the regeneration system frame, this is the end of the system process route. After purification and adsorption drying, the gas passes through this device before being supplied to the reduction furnace. This device contains a membrane filter cartridge to filter the hydrogen coming from the regeneration tower, achieving 99.99% filtration efficiency for dust particles above 0.5µm.

(3) Explosion-proof Electric Heater

The electric heater heats the regeneration hydrogen in a manner to the process temperature, thereby removing moisture from the molecular sieve to maintain its activity. The heater temperature is automatically controlled by a temperature control instrument using a thermocouple for temperature measurement.

(4) Automatic Exhaust Device

An exhaust valve is reserved on the regeneration circulation device pipeline. When the system operating pressure becomes too high, the circulating gas in the regeneration system will be automatically exhausted through a water seal via this valve, ensuring the regeneration system gas can be replenished and replaced. When this function is activated, the system's hydrogen consumption will increase slightly. This fluctuation can be adjusted using the manual valve in front of the pneumatic valve.

(5) Gas Detection Device

Located on the pipeline at the outlet of the drying tower, this device samples the adsorbed hydrogen for gas component detection. The main detection parameters are: hydrogen dew point, hydrogen 0-100% VOL, and oxygen 0-100% VOL. Because the sample gas uses a small-diameter output control, the dew point detection value does not have pressure dew point support, resulting in a higher reading compared to direct insertion into the pipeline (under the same conditions, the dew point shown with this installation method might be -60 to -65°C, while direct insertion could reach -75 to -80°C).

During system operation, the nitrogen content is calculated as follows: Nitrogen % = 100% - Hydrogen % - Oxygen %. If the nitrogen content rises to a certain level, the impure hydrogen in the system can be vented using the exhaust device at the hydrogen return port. The exhaust flow rate can be adjusted using a glass rotameter.

3. Chiller Unit (One chiller, two circulating water pumps)

Pure water is stored in the chiller water tank. It is pumped out by the circulating water pumps and supplied to the equipment after being cooled by the chiller. This unit maximizes energy savings, as the chiller automatically starts/stops based on the inlet and return water temperatures.

Chiller unit design diagram (omitted in text)

4. Inlet Hydrogen Return Scrubbing Device

The system inlet is equipped with a scrubbing tower and gas-water separator. This scrubbing device is made of carbon steel and primarily consists of the scrubbing tower, gas-water separator, overflow tank, water seal, spray piping, etc. The spray piping has 3 spray nozzles, and the scrubbing tower is filled with Pall rings. Automatic drainage is achieved using a water seal.