I. Papermaking Stage: Thermal Energy Support from Pulp to Finished Paper

1. Pulping and Cooking: Laying the Foundation for Pulp Quality
    
   Pulping is the core process of converting fiber raw materials (such as wood, straw, and waste paper) into usable pulp. Steam plays a dual role in "heating and softening" and "impurity removal" during this process. For wood pulp or straw pulp production, high-temperature and high-pressure steam is introduced into the digester, heating the raw materials to 180-220°C (corresponding to a steam pressure of 0.8-1.6MPa) to soften and decompose the lignin between fibers, enabling fiber separation. Meanwhile, steam heating activates the activity of cooking chemicals (such as alkaline solutions), improving fiber purity. For waste paper pulping, steam heats the deinking agent solution to help ink peel off from waste paper fibers, reducing impurity residues and providing clean raw materials for subsequent paper production.

2. Paper Drying: Controlling Moisture Content and Physical Properties
    
   Freshly formed wet paper sheets from the paper machine have a moisture content as high as 60%-70% and need to be dehydrated to 6%-8% through a multi-cylinder drying system. The uniformity and temperature stability of steam during this process are crucial. Steam is passed into the cylinder interlayer, heating the cylinder surface to 80-120°C (corresponding to a steam pressure of 0.3-0.6MPa). As the wet paper sheet adheres to the cylinder surface, moisture is gradually evaporated. Excessive fluctuations in steam temperature can cause uneven local dehydration—too fast dehydration may lead to wrinkles and cracks, while too slow dehydration reduces production efficiency and even affects paper strength and whiteness.

3. Calendering and Shaping: Enhancing Paper Surface Quality and Printing Adaptability
    
   After drying, paper undergoes calendering and coating shaping processes to optimize surface smoothness and functional properties. Steam is mainly used to heat calendering rolls and coating drying devices in this stage. During calendering, steam heats the calendering rolls to 150-200°C (corresponding to a steam pressure of 0.5-1.0MPa). The paper passes through the roll gap under high temperature and pressure, resulting in a smooth surface that improves ink adhesion during subsequent printing. For functional papers (such as waterproof or wear-resistant paper), steam also heats the coating drying device to quickly cure surface coatings (e.g., waterproofing agents, wear-resistant agents), ensuring stable functionality.

II. Packaging Stage: Processing Support from Paperboard to Finished Packaging

1. Paperboard Forming: Ensuring Firm Bonding and Dimensional Stability
    
   Corrugated and honeycomb paperboards are core substrates in the packaging industry. Steam is mainly used for "adhesive curing" and "stress relief" during their forming. In corrugated board production, steam heats the bonding machine to 140-180°C (corresponding to a steam pressure of 0.4-0.8MPa) to quickly cure eco-friendly adhesives such as corn starch glue, achieving tight bonding between corrugated core paper and face paper. Insufficient or fluctuating bonding temperatures can lead to delamination and weak adhesion, affecting the load-bearing capacity of the packaging. For honeycomb paperboard, steam heats the shaping device to eliminate internal stress after forming through medium-temperature heating, preventing warping or deformation during subsequent storage or use.

2. Printing and Laminating: Ensuring Clear Patterns and Packaging Functionality
    
   Packaging printing (e.g., flexographic printing) and laminating processes have strict requirements for "low-temperature stable steam supply" and "cleanliness." In printing, water-based inks need rapid drying to avoid smudging. Steam heats the drying oven to 120-160°C (corresponding to a steam pressure of 0.3-0.5MPa), evaporating moisture in the ink through hot air circulation. Oil or impurities in steam can adhere to the printing surface with hot air, forming "stains" that affect packaging appearance. Therefore, steam systems must be equipped with oil-removing filters to ensure clean, contaminant-free steam.

3. Finished Product Shaping: Ensuring Structural Stability and Usage Safety
    
   Finished packaging shaping includes processes such as carton die-cutting and plastic packaging heat-sealing. Steam plays a role in "auxiliary heating" and "safe temperature control" here. During carton die-cutting, steam preheats die-cutting knives to 100-120°C (corresponding to a steam pressure of 0.2-0.3MPa) to soften hard paperboard fibers, improving cutting precision and avoiding rough edges. For plastic materials like food packaging, steam heats heat-sealing machines to 120-140°C (corresponding to a steam pressure of 0.3-0.4MPa) to melt and seal packaging edges, preventing liquid or gas leakage and ensuring food storage safety.

Key Technical Requirements: Adapting to Papermaking and Packaging Industry Characteristics

1. Continuous Steam Supply and Emergency Support Capability

    

   Most papermaking and packaging production lines operate 24/7 (e.g., large paper machines with daily capacity exceeding 1,000 tons). Steam interruptions can cause significant losses such as wet paper sheet scrapping and paperboard adhesion failure. Therefore, steam generators must adopt a dual-unit or multi-unit parallel design. In case of a single unit failure, the standby unit can switch quickly, with a switching time of no more than 30 seconds. Large-capacity heat accumulators are also equipped to buffer instantaneous steam peaks in processes like pulping and drying (e.g., a 30% sudden increase in steam demand during cooking startup), avoiding system pressure drops and ensuring supply stability.
2. High Efficiency, Energy Saving, and Cost Optimization

    

   Steam costs account for 15%-25% of total production costs in papermaking and packaging, making energy conservation a core enterprise need. Steam generators achieve efficiency improvements through three key technologies:
   • Deep waste heat recovery: Not only recovering heat from condensate in cylinders and drying ovens but also reducing boiler exhaust temperature from 150-200°C to ≤100°C via flue gas waste heat recoverers, improving overall energy efficiency by 20%-30%.
   • Flexible fuel adaptation: Supporting multiple fuels such as gas, biomass (straw, wood chips), and coal, allowing enterprises to choose low-cost options based on local fuel prices (e.g., biomass fuel costs 30%-40% less than gas).
   • Intelligent load adjustment: Monitoring steam consumption via PLC systems and automatically adjusting generator load (e.g., reducing to 50% load during low night-time production) to avoid energy waste.
3. Equipment Durability and Environmental Adaptability

    

   Papermaking workshops have high humidity and dust levels, so steam generators must have strong environmental adaptability:
   • Shells use epoxy resin anti-corrosion coatings to prevent rust in humid environments.
   • Electrical control systems are fitted with dust covers to avoid faults caused by dust ingress.
   • A forced water softening system is installed at the water inlet to remove calcium and magnesium ions, preventing scaling in the boiler liner—scale not only reduces heat exchanger efficiency (1mm of scale decreases thermal efficiency by 5%-8%) but may also detach with steam, contaminating paper or packaging and affecting product quality.

III. Industry Development Trends: Green and Intelligent Upgrades

1. Green and Low-Carbon: Reducing Carbon Emissions and Energy Dependence

    

   On one hand, biomass steam generators are gradually being promoted, using agricultural waste (straw) and forestry waste (wood chips) as fuels to achieve "carbon cycle" utilization. Their carbon emissions are over 50% lower than traditional coal-fired boilers, aligning with environmental policy requirements. On the other hand, some enterprises are exploring the "photovoltaic + electric heating steam generator" model, using solar power for energy supply in sunny areas to further reduce fossil energy consumption and achieve zero-carbon production.
2. Intelligent Management and Control: Improving Efficiency and Quality Stability

    

   Through the Internet of Things (IoT) technology, steam generators are interconnected with production lines and energy management systems:
   • Real-time monitoring of steam consumption, temperature, pressure, and other parameters, with AI algorithms predicting steam demand (e.g., thermal parameters for different paper types and packaging specifications) to adjust generator status in advance and reduce parameter fluctuations.
   • Support for remote fault diagnosis: when equipment malfunctions, alarm information is automatically pushed with maintenance suggestions, reducing downtime for repairs and improving production efficiency.