Driven by the global goal of carbon neutrality, hydrogen, as a zero-carbon energy carrier, is moving from the laboratory to large-scale industrial application. Due to their high efficiency, cleanliness, and safety, medium-temperature, medium-pressure hydrogen boilers have become core equipment for resource utilization of by-product hydrogen in industries such as chemical, chlor-alkali, and steel. This article will systematically analyze the core knowledge of medium-temperature, medium-pressure hydrogen boilers from four perspectives: technical principles, application scenarios, safety specifications, and industry case studies.

I. Technical Principles: Core Design for Efficient Hydrogen Energy Conversion

1. Boiler Structure
Medium-temperature, medium-pressure hydrogen boilers typically utilize a vertically mounted double-drum D-type layout. The convection heat transfer section is a single-pass structure, resulting in low flue gas emission resistance and heat transfer efficiencies exceeding 90%. For example, the 20 t/h hydrogen boiler at Qingdao Bay Chemical has a design pressure of 1.6-2.5 MPa and a steam temperature of 250-350°C. The combination of membrane water-cooled walls and convection tube bundles optimizes both radiative and convective heat transfer.

2. Combustion System Innovation
Diffusion External Mix Burner: Hydrogen and air enter the furnace in two separate paths, creating a gas-rich center zone and an air-rich edge zone at the burner nozzle, preventing flashback and improving combustion efficiency to over 99.5%.
Secondary Ignition Safety Mechanism: Natural gas is first used to ignite the auxiliary ignition nozzle. Once combustion stabilizes, the hydrogen main burner is switched. Combined with a flame monitor and automatic leak detection system, this ensures a risk-free ignition process.
Intelligent Air Volume Control: A PLC+touchscreen control system adjusts the forced air/induced air ratio in real time based on hydrogen flow, achieving stable combustion within a load range of 30%-100%.
3. Energy-Saving and Environmentally Friendly Design
Spiral Fin Tube Economizer: Utilizes flue gas waste heat to heat boiler feed water, reducing exhaust gas temperature to below 150°C and improving thermal efficiency by 5%-8%.
Ultra-Low NOx Emission Technology: Through staged combustion and flue gas recirculation, NOx emissions are below 30mg/m³, meeting EU BEST standards. Explosion-proof doors and walls: A gravity-type explosion-proof door is installed on the top of the boiler, and refractory concrete explosion-proof walls are built around the furnace to ensure the safety of personnel and equipment under extreme operating conditions.

2. Application Scenario: A Revolution in the Resource Utilization of By-Product Hydrogen

1. Chlor-alkali Industry: From "Wasteful Venting" to "Steam Self-Sufficiency"
Take Shandong Xinlong Group as an example. Its chlor-alkali plant produces over 100 million Nm³ of by-product hydrogen annually. Traditionally, this was handled by burning it or compressing it for export. The introduction of a hydrogen boiler converts the hydrogen into steam and feeds it into the pipeline network, achieving:

Direct Steam Cost Reduction: The steam cost per ton of caustic soda has dropped from 280 yuan to 199.5 yuan, saving over 8 million yuan annually.

Significant Carbon Emission Reduction: Based on a carbon trading price of 80 yuan per ton, this reduces carbon emissions by 200,000 tons annually, generating carbon revenue of 16 million yuan.

Improved Process Stability: The steam supply has shifted from external reliance to self-sufficiency, avoiding production interruptions caused by external steam fluctuations. 2. Steel Industry: Synergistic Utilization of Blast Furnace Gas and Hydrogen
A steel plant mixes blast furnace gas and hydrogen in a 3:1 ratio and burns them. The mixture is then used in a hydrogen boiler to generate medium-pressure steam for power generation. This achieves:

Increased calorific value: The calorific value of the mixed gas increased from 3.5 MJ/m³ to 8.2 MJ/m³, improving power generation efficiency by 40%.

Reduced pollutant emissions: Sulfur dioxide emissions decreased by 60%, and dust emissions by 75%.

Optimized economics: The proportion of hydrogen costs to steam costs decreased from 35% to 18%, shortening the payback period to 2.3 years.

3. Chemical Park: A Model of Cascaded Hydrogen Energy Utilization
In a chemical park in Jiangsu, a hydrogen boiler, thermal oil boiler, and steam turbine form a cascaded energy utilization system:

Primary Utilization: The hydrogen boiler generates medium-pressure steam (3.82 MPa, 450°C) to drive a steam turbine for power generation.

Secondary Utilization: The turbine back-pressure steam (1.0 MPa, 180°C) is used by park enterprises. Level 3 Utilization: Low-temperature waste heat is used to heat the process medium via a thermal oil boiler, achieving an overall system energy efficiency exceeding 85%.

3. Safety Standards: Comprehensive control from design to operation and maintenance

1. Safety Redundancy in the Design Phase

Pressure Vessel Standards: The boiler drum and header are designed in accordance with GB/T 150 "Pressure Vessels," with a 20% safety margin reserved for wall thickness.

Material Selection: Components contacting hydrogen are constructed using 316L stainless steel or Monel alloy to mitigate the risk of hydrogen embrittlement.

Explosion-Proof Design: The combustion chamber volume is designed to 1.5 times the explosion limit of hydrogen (4%-75%) to ensure a safe clearance.

2. Standardized Installation and Commissioning Procedures

Pipeline Pressure Testing: Hydrogen pipelines must undergo a hydraulic pressure test at 1.5 times the design pressure, maintaining the pressure for four hours without leaks.

Nitrogen Replacement: Before commissioning, the pipelines must be purged with nitrogen. Hydrogen can only be introduced when the oxygen content is below 0.5%. Pre-ignition Inspection: Confirm that the pneumatic shut-off valve, flame monitor, and pressure interlock are functioning properly, and conduct a simulated ignition test.
3. Key Control Points for Operation and Maintenance
Water Quality Management: Maintain the feed water pH between 8.8 and 9.2, with an iron ion content below 50 μg/L, to prevent boiler drum corrosion.
Load Regulation: The single load change rate should not exceed 10%/min to avoid stress cracking caused by sudden changes in furnace temperature.
Regular Inspection: Conduct internal inspections every two years, focusing on water-wall tube thickness, weld quality, and explosion-proof door sealing.

4. Industry Case Study: Fangkuai Boiler's Zero-Carbon Practice

1. Technological Breakthrough: Domestication of Medium-Temperature, Medium-Pressure Hydrogen Boilers
Fangkuai Boiler's 65 t/h medium-temperature, medium-pressure hydrogen boiler utilizes fully premixed surface combustion technology, achieving:

92% thermal efficiency: Through slightly positive pressure combustion and flue gas recirculation, this achieves an 8 percentage point improvement over traditional boilers. Fast Startup and Shutdown: The time from cold to full load is reduced to 40 minutes, adapting to fluctuating chemical production demands.
Intelligent Diagnosis: The operation and maintenance system, equipped with AI algorithms, can predict boiler failures 72 hours in advance, reducing unplanned downtime by 90%.
2. Application Results: A Win-Win Transformation for a Chlor-Alkali Company
After introducing Fangkuai hydrogen boilers, a chlor-alkali company achieved:

100% steam self-sufficiency: Annual reduction of external steam purchases by 200,000 tons, saving 40 million yuan.
Carbon Quota Surplus: Annual reduction of carbon emissions by 500,000 tons, generating 40 million yuan in profits through carbon trading.
Environmental Compliance: Nitrogen oxide emissions were reduced from 200mg/m³ to 25mg/m³, meeting ultra-low emission requirements.
Conclusion: Hydrogen Boilers – The Key Player in Industrial Green Transformation
Medium-temperature, medium-pressure hydrogen boilers are reshaping the industrial energy landscape through the dual guarantees of technological innovation and safety regulations. From the utilization of byproduct hydrogen in the chlor-alkali industry to its cascaded utilization in steel and chemical parks, its economic and environmental benefits have been fully demonstrated. With the global implementation of carbon tariffs and the tightening of domestic carbon quotas, hydrogen boilers will become core equipment for companies to achieve their "zero-carbon steam" goals, accelerating the evolution of industrial energy towards cleaner and more efficient processes.