Cooling System

1. Equipment Positioning

The cooling system is a core auxiliary unit of heat treatment production lines. It precisely controls the cooling rate and cooling uniformity of workpieces, which directly determines the metallographic structure, hardness, toughness and deformation degree of workpieces. It is divided into three major types: in-furnace cooling, quenching cooling and finished product slow cooling. It is equipped with integrated devices for circulation, filtration, temperature control and medium recovery, matching full processes including quenching & tempering, annealing, normalizing, solution treatment and tempering.

2. Main Classification of Cooling Systems

(1) Classified by cooling medium

1. Water cooling system

It adopts clean water, salt water and PAG water-soluble polymer quenchant as cooling media with fast cooling speed, including three structures: spray cooling, integral immersion cooling and laminar flow cooling. It is equipped with closed cooling towers, circulating water pumps, impurity filter tanks and automatic temperature adjustment modules, mostly used for quenching and tempering of carbon steel, oil well pipes and steel plates.

2. Oil cooling system

Special quenching mineral oil serves as the medium with gentle cooling rate, greatly reducing the risk of workpiece cracking and deformation. It is configured with tank stirring devices, plate heat exchangers, oil-water separators and oil fume collection devices, suitable for quenching of alloy steel, die steel and precision parts.

3. Gas / Air cooling system

It uses air, nitrogen or nitrogen-hydrogen mixed gas as the cooling medium without oxidation and surface contamination, including forced convection circulating air cooling, jet gas cooling and vacuum high-pressure gas cooling. It is applied to bright annealing and solution slow cooling of stainless steel, aluminum alloys and precision components.

4. Composite cooling system

It adopts combined gas-liquid sectional cooling: pre-cooling by gas first followed by liquid cooling to realize precise sectional cooling rate control. It fits long pipes, wide and thick plates and variable cross-section forgings to balance hardenability and deformation.

(2) Classified by technological structure

1. Built-in in-furnace cooling system

Integrated inside the furnace body, including furnace wall water cooling jackets, furnace door water cooling and circulating fan air cooling. It is used for furnace body self-cooling and pre-cooling before workpieces are discharged from furnaces, standard configuration for bell-type furnaces, roller hearth furnaces and Bogie Hearth Furnaces.

2. Off-line quenching cooling system

Independent quenching tanks, spray quenching machines and roller press quenching machines. Workpieces are quickly transferred to cooling units after furnace discharge to complete quenching, which is the core equipment of quenching & tempering production lines.

3. Finished product slow cooling system

Air cooling slow cooling beds and sealed atmosphere cooling hoods conduct low-speed and uniform temperature drop after tempering or solution treatment to eliminate residual stress and prevent workpiece cracking and dimensional distortion.

(3) Classified by conveying and cooling mode

1. Spray cooling system

Outer annular spray and synchronous internal & external spray for pipes with adjustable pressure and uniform cooling, specially designed for pipes and shaft parts.

2. Immersion cooling system

Workpieces are fully immersed into the medium tank, and stirring mechanisms inside the tank ensure consistent temperature in the whole area, commonly used for plates and forgings.

3. Laminar flow cooling system

Low-pressure stable laminar water curtain without splashing, specially adopted for steel plate heat treatment with extremely small temperature difference on plate surface.

4. Vacuum high-pressure gas cooling system

High-pressure inert gas is filled into the sealed vacuum chamber for circulating cooling, applied to high-end precision alloys and aerospace parts.

3. Standard Composition Units of Cooling System

1. Cooling medium storage tank (water tank / oil tank / gas storage tank)

2. Circulating power unit: variable frequency water pumps, high-pressure fans, stirring circulating pumps

3. Heat exchange and cooling unit: closed cooling towers, plate heat exchangers

4. Filtration and purification unit: sedimentation tanks, magnetic slag removers, precision filters, oil-water separators

5. Cooling execution unit: spray rings, immersion tanks, laminar flow headers, air cooling ducts

6. Monitoring and regulating unit: temperature sensors, liquid level gauges, medium concentration detectors, pressure regulating valves

7. Safety auxiliary unit: medium replenishing devices, overflow vent pipelines, oil fume & waste gas collection devices

4. Core Technical Characteristics

1. Controllable cooling rate: Wide-range cooling speed adjustment by regulating medium pressure, flow rate, temperature and stirring intensity.

2. Recyclable medium: Closed-loop filtration circulation reduces consumption of water resources and quenching oil with eco-friendly performance.

3. Closed-loop stable temperature: Real-time collection of medium temperature linked with cooling towers for automatic heat exchange, with temperature fluctuation ≤ ±3℃.

4. Low deformation design: Multi-point uniform spraying and full-area medium stirring minimize temperature difference along the full length and cross-section of workpieces.

5. Automatic linkage: Signal interlock with heating furnaces and conveying mechanisms to automatically start and stop cooling and adjust flow rate.

5. Applicable Process Scenarios

Quenching for quenching & tempering, rapid cooling after solution treatment, air cooling for normalizing, slow cooling for annealing, temperature drop after tempering, self water cooling of furnace equipment, high-pressure gas quenching for vacuum furnaces.