Project Name: 200,000-ton Continuous Pickling Production Line
Client Name: Zhejiang Xinhong Steel Products Co., Ltd.
Project Nature: New Construction Project
Undertaking Method: General Contracting by Jingjie Ruisi
Signing Date: October 16, 2012
Commissioning Status: Under Construction
Operation Status: Good
I. Description of the Pickling Production Line
This pickling line is a hydrochloric acid pickling line. The provided process equipment and technology are proven, reliable, and mature through production practice, capable of meeting the buyer’s needs for stable production and long-term operation as a complete set of equipment and technology. The technology features reasonable equipment structure, high operational efficiency, low production consumption, convenient operation, and few equipment operation failures.
The designed pickling line completes the entire process of steel strip pickling treatment from uncoiling to coiling online. The line is equipped with double uncoilers; the uncoilers are of hydraulic expansion type with belt braking.
A feeding trolley is installed at the entry of the line. Steel coils are first placed on the receiving rack (saddle) by a crane, and then the feeding trolley transports the steel coils to the center position of the uncoiler mandrel. To ensure pickling effect, a scale breaker is installed after the 2# uncoiler.
After the steel strip enters the pickling tank, chemical reactions occur directly between the strip surface and the hydrochloric acid solution in the tank as follows:
Fe₂O₃ + 6HCl ==== 2FeCl₃ + 3H₂O
Fe₃O₄ + 8HCl ==== 2FeCl₃ + FeCl₂ + 4H₂O
FeO + 2HCl ==== FeCl₂ + H₂O
Fe + 2HCl ==== FeCl₂ + H₂↑
Hot air dryers are used for steel strip drying, and hot air is heated by a steam heat exchanger. The coiler adopts an cantilever-type tension coiler; coiling tension is established through a tension machine, and the coiling is equipped with EPC control to ensure neat edge coiling. A hydraulically driven uncoiling trolley is installed at the exit for uncoiling to transport the steel coil to the discharge rack.
The electrical control system of the line consists of a power distribution system, AC variable frequency motor drive device, AC motor control unit, PLC operation control system, main operation console, sub-operation consoles, and other systems. The operation control of the system is completed by a PLC programmable controller, and the operating system also includes the interlock control function of the auxiliary process system of the pickling line.
II. Design Concepts Followed by the Production Line
1. **Need Satisfaction Principle**: The designed products and performance meet users’ requirements to the greatest extent, based on market research, analysis, and prediction.
2. **Economic Rationality Principle**: The designed products feature advanced structure, good functionality, low cost, and convenient use and maintenance. The specified functions of the product are realized at the lowest cost within the product’s life cycle.
3. **Reliability Principle**: The product has a high degree of reliability in completing specified functions under specified operating conditions and within specified time.
4. **Optimization Principle**: Under given design objectives, optimal design methods are used to recommend the most reasonable方案 to users.
5. **Standardization Principle**: The designed product specifications and parameters comply with national standards; components are generalized with those of similar products to the greatest extent, and components in the same product are interchangeable as much as possible.
6. **Safety Principle**: The designed product ensures the safety of operators, managers, and mechanical equipment, and ensures that the equipment is harmless to the surrounding environment; it minimizes the physical and mental consumption of workers during operation.
7. **Ergonomics Principle**: The product is coordinated with the human body during use, enabling convenient operation, comfortable environment, sensitive response, and high efficiency for people during machine operation.
III. Design Basis
1. Incoming Material: Carbon steel, high-carbon steel
2. Thickness Specification: 1.5—3.0mm
3. Width Specification: 183—420mm
4. Incoming Coil Weight: 5t (max)
5. Finished Coil Weight: 5t (max)
6. Steel Coil Inner Diameter: Incoming Φ508mm; Finished Φ508mm
7. Steel Coil Outer Diameter: Φ1000mm～Φ1600mm
Annual Operation Plan: 300 days * 24 hours
Energy Sources: Water, electricity, steam
Product Form: Coil-to-coil
Production Program: 200,000 tons/year
Maximum Process Speed of the Line: 90m/min
IV. Main Technical Indicators of the Production Line
Process Method: Hydrochloric acid pickling
Production Line Layout: Viewed from the operation side (to be determined: from right to left)
Maximum Process Speed of the Line: 90m/min
Inching Speed: 10-30m/min
Line Drive Mode: AC drive, variable frequency speed regulation
Pickling Medium: HCL (hydrochloric acid)
Concentration of Pickling Medium: 18-25%
Temperature of Pickling Medium: 60-75℃ (user’s steam temperature is approximately 130℃)
Total Length of Acid Tanks: Approximately 120 m
Total Length of the Line: Approximately 215 m
Maximum Uncoiling Tension: 8 kN
Maximum Coiling Tension: 20 kN
V. Process Flow
Crane Feeding to Receiving Rack → 1#, 2# Feeding Trolley → 1#, 2# Uncoiler → Shearing → Welding → Three-roll Scale Breaker → Guide Device → Looper Feeding Device → Disc-type Looper →翻转托架→ 1# Vertical Guide Roll Centering → 1# Two-roll Pinch Machine → Support Roll → 1# Pickling Tank → 1# Acid Squeegee Roll → 2# Vertical Guide Roll Centering → 2# Two-roll Pinch Machine → 2# Acid Tank → 2# Acid Squeegee Roll → 3# Vertical Guide Roll Centering → 3# Two-roll Pinch Machine → Neutralization Tank → 4# Vertical Guide Roll Centering → Cleaning Machine → Rinsing Tank → Water Squeegee Roll → Dryer → 4# Two-roll Pinch Machine → Guide Device → Looper Feeding Device → Disc-type Looper →翻转托架→ Deflector Roll → Tension Machine → Shearing → 5# Two-roll Pinch Machine → Coiler → Discharging Trolley → Manual Operation Crane to Unload Raw Materials
