13L×1.6W×3H Zinc Kettle | 410-Ton Zinc Capacity Natural Gas Straight-Line Hot-Dip Galvanizing Production Line | Large-Scale Steel Component Batch Galvanizing & Surface Treatment System

1. Product Overview

This natural gas straight-line environment-friendly hot-dip galvanizing production line features a zinc kettle with internal dimensions of 13m×1.6m×3m, 410-ton zinc capacity, and maximum hourly capacity of 16 tons/hour. The line covers the full process of pre-treatment (degreasing, rinsing, pickling, cleaning, fluxing), galvanizing, cooling, passivation, and exhaust gas treatment. It uses natural gas micro-positive pressure heating and incorporates a cascade flue gas waste heat utilization system (including patented technologies: combustion air heating, fluxing liquid heating, degreasing tank heating, workpiece drying, sludge drying, kettle edge waste heat recovery, and online weighing). It is suitable for high-volume, environmentally compliant hot-dip galvanizing of large steel structural parts.

2. Industry Challenges & Root Cause Analysis

High natural gas consumption and operating costs:Large-scale galvanizing lines consume enormous natural gas – significant operating cost pressure. Root cause: flue gas waste heat directly discharged without cascade recovery.

Acid mist and zinc fume pollution:Large pickling tanks and zinc kettles generate substantial acid mist and zinc-containing dust – severe environmental compliance pressure. Root cause: lack of enclosed negative-pressure pickling rooms and efficient bag filter + water curtain deodorization systems.

Difficult fluxing liquid iron content control:Iron ion accumulation in fluxing liquid affects coating quality and increases zinc consumption. Root cause: lack of online iron removal and automatic pH balance systems.

Galvanizing process relies on manual operation:Large-part immersion time and temperature controlled manually – inconsistent coating thickness and higher costs. Root cause: lack of PLC automatic program control for galvanizing timing management.

Lack of zinc consumption and iron loss measurement:Pickling iron loss and galvanizing zinc consumption cannot be monitored online – coarse cost accounting. Root cause: lack of online weighing system.

3. Solution

3.1 High-Efficiency Natural Gas Heating System:High-speed pulse burners (TJ300×6 sets) – instantaneous gas consumption 420m³/h – dual main intake control (one active, one standby). Three-stage PLC temperature control – zinc bath temperature 438-450℃ automatically controlled – gas consumption approximately 12.5m³ per ton of parts at full load.

3.2 Cascade Flue Gas Waste Heat Utilization System (Multiple Patents):500℃ flue gas → stainless steel heat exchanger heats water to 90℃ → fluxing/degreasing tank titanium heat exchanger heats to 30-70℃. 300℃ flue gas → drying tank heats workpieces (100-180℃). 200℃ flue gas → combustion air heat exchanger heats air to 50-150℃ – saves approximately 3m³ gas per ton of parts. Kettle edge waste heat (~200℃) → stainless steel double-layer coil heats water for acid heating/space heating. Final flue gas → workshop heating. Comprehensive energy savings significant.

3.3 Enclosed Negative-Pressure Acid Mist Treatment System:Pickling tanks with enclosed acid mist treatment room (25500×15450×6500mm) – ground rail carts + pit sliding cover for material loading/unloading – negative pressure maintained at 5-10Pa – no acid mist escape. Acid mist passes through dilution tower + absorption neutralization tower (automatic dosing, 45kW variable frequency fan, inlet/outlet pH probes) for compliant discharge. Rinse water reused for new acid preparation – reduces alkali usage. VFD fan automatically reduces frequency based on negative pressure setting – saves ~50% electricity.

3.4 Zinc Fume Collection & Purification System:Double-sided suction capture of zinc fume at kettle edges – smoke suction + bag filter (filtration area 1920m²) + induced draft fan + water curtain deodorization (chimney, ducts, etc.) – 160kW variable frequency – starts 2-3 minutes before kettle immersion – saves 200-300% power. High/low speed switching ensures bags are blown clean.

3.5 Automatic Iron Removal & pH Balance System:Fluxing liquid equipped with 60t automatic iron removal equipment – ensures iron content ≤1mg/L, pH controlled around 5 – effectively reduces zinc consumption and improves coating quality. Filter press sludge sent to sludge drying oven.

3.6 Automated Galvanizing Control & Online Weighing:PLC automatic program design – crane automatically enters set zinc immersion time after lifting parts – zinc temperature automatically controlled – prevents manual over-immersion adding unnecessary zinc layers and costs. Online weighing system displays black part weight, pickling iron loss, galvanizing weight gain and zinc consumption in real-time – facilitating timely adjustment of operating plans.

3.7 Workpiece Drying Conversion Pit:Drying conversion pit dimensions 14000×5000×3000mm – heat exchanger inside flue generates hot air to dry workpieces (100-180℃) – reduces zinc splashing – avoids hanging workpieces on zinc kettle for drying – saves hanging time – increases production and reduces gas consumption.

4. Technical Specifications

5. Selection Guide

5.1 Recommended Scenarios

• High-volume galvanizing of large steel structural parts (transmission towers, bridge components, steel gratings, etc.)

• New construction or upgrade of large-scale galvanizing lines requiring environmental compliance

• Energy-saving galvanizing plants seeking natural gas consumption reduction and waste heat utilization

5.2 Key Selection Considerations

1. Kettle size and capacity: Verify 13×1.6×3m kettle and 16 tons/hour capacity meet production needs

2. Fuel conditions: User to supply natural gas with calorific value ≥8400×4.18kJ/m³, pressure 100-200kPa

3. Power supply: User to supply 380V/50Hz 3-phase power, total capacity ~525kW

4. Facility conditions: User responsible for building, concrete tank construction, foundations, water/electricity/gas lines to equipment interface

5. Lifting equipment: User to supply hoists and cranes (5-ton + 5-ton units)

6. Environmental requirements: Acid mist and zinc fume treatment systems meet local emission standards

6. FAQ

Q1: How much natural gas can the waste heat utilization system save?

A: Combustion air heating system heats air to 50-150℃ – saves approximately 3m³ gas per ton of parts. At 60,000-ton annual capacity, annual gas savings ~180,000m³. Combined with fluxing heating, degreasing tank heating, workpiece drying, kettle edge heat recovery, and workshop heating – annual savings of hundreds of thousands RMB.

Q2: How is acid mist emission compliance ensured?

A: Enclosed negative-pressure pickling room (5-10Pa) with ground rail cart + pit sliding cover operation – prevents acid mist escape. Acid mist passes through dilution tower then absorption neutralization tower with automatic dosing – inlet/outlet pH probes – 45kW VFD fan automatically adjusts frequency based on negative pressure – saves ~50% power – ensures compliant discharge.

Q3: How does the zinc fume treatment system work?

A: Double-sided suction captures zinc fume at kettle edges – smoke passes through bag filter (filtration area 1920m²) for dust removal – then water curtain deodorization tower – finally discharged via chimney. 160kW VFD fan starts 2-3 minutes before kettle immersion – saves 200-300% power. High/low speed switching ensures bags are blown clean.

Q4: How is fluxing liquid iron content controlled?

A: Fluxing liquid equipped with 60t automatic iron removal equipment – continuously circulates and removes iron – ensures iron content ≤1mg/L – pH automatically regulated to ~5. Low iron content effectively reduces zinc consumption, minimizes zinc dross generation, and improves coating surface quality. Filter press sludge sent to sludge drying oven.

Q5: What is the function of the online weighing system?

A: Online weighing system displays black part weight, pickling iron loss, galvanizing weight gain and zinc consumption in real-time. Operators can adjust operating plans based on data – controlling zinc consumption and iron loss – achieving refined cost management.

7. Why Choose Wuxi Wondery

• Ultra-large zinc kettle: 13×1.6×3m – 410-ton zinc capacity – 16 tons/hour output – meets large-component batch production

• Cascade flue gas waste heat utilization (multiple patents): Combustion air heating, fluxing heating, degreasing heating, workpiece drying, sludge drying, kettle edge heat recovery – comprehensive energy savings

• Low gas consumption high-efficiency combustion: ~12.5m³ per ton at full load – preheated air saves additional 3m³/ton