The Autoclave: The Core of an AAC Aerated Block Production Line

AAC (autoclaved aerated concrete) aerated block production line is a complete set of equipment designed for the efficient production of aerated concrete blocks, AAC blocks, and AAC bricks. This line typically consists of key components such as a slurry tank, a belt conveyor, a pouring mixer, a mesh welder, and the crucial autoclave. As a professional AAC block equipment manufacturer and AAC production line manufacturer, Richi offers turnkey solutions, covering every step from raw material processing to the final production of high-quality AAC aerated concrete products. Among all the equipment in an aerated concrete (AAC) production line, the autoclave is the core equipment, directly impacting the quality, performance, and production efficiency of AAC blocks.

1. Autoclave: AAC Block Production Line Key Equipment

1.1 Introduction to the Autoclave

The autoclave is a key piece of equipment in an aerated concrete block production line. It is a horizontal, cylindrical unit primarily composed of a body, a cover, a sealing device, a pressure control system, and a temperature control system. It is specifically designed to create a high-temperature, high-pressure environment, which is crucial for the curing process of aerated concrete (AAC). The autoclave's structural design is capable of withstanding extreme pressure and temperature conditions, ensuring safe and stable operation during the aerated concrete block production process.

1.2 The Important Role of Autoclaves in Aerated Concrete (AAC) Production

The autoclave plays an irreplaceable role throughout the entire aerated concrete block production process. The AAC slurry is poured into molds via a pouring mixer, cut into specific sizes (consistent with the standard dimensions of AAC blocks) by a cutting machine, and then transported to the autoclave via a conveyor belt for the critical curing phase. In the autoclave, the AAC block body undergoes a series of hydrothermal reactions under high temperature and pressure. These reactions enhance the strength, density, and durability of the AAC blocks, giving them excellent properties such as thermal insulation, sound insulation, and lightweight properties. Without high-quality autoclaves, it would be impossible to produce AAC blocks that meet industry standards (such as the IS specification for AAC blocks) and market demand. Therefore, the autoclave is central to the quality and performance of AAC aerated concrete products.

2. Autoclave Operating Principle and Process

2.1 Operating Principle

The operating principle of the autoclave in an AAC block production line is based on the use of high-temperature, high-pressure saturated steam. After placing the aerated concrete green blocks into the autoclave, the autoclave is sealed. Saturated steam is then introduced into the autoclave, gradually raising the internal temperature and pressure to specified values ​​(typically approximately 180-220°C and 0.8-1.5 MPa). Under these conditions, the silica and calcium oxide in the aerated concrete green blocks (such as sand, fly ash, and cement) react with water to form stable hydrated silicate minerals. These minerals form a tight bond, significantly improving the mechanical properties and stability of the aerated concrete green blocks. This process not only ensures the strength of the aerated concrete green blocks but also reduces their weight, making them an ideal choice for modern green buildings.

2.2 Workflow

2.2.1 Loading the Autoclave

First, the cut aerated concrete green blocks (processed to the desired size) are neatly arranged on a dedicated cart. These carts are then transported into the autoclave via a belt conveyor or other transport equipment. During this process, ensuring that the green pieces are evenly arranged and free of collision is crucial to avoid damage and ensure uniform subsequent curing.

2.2.2 Curing Phase

The autoclave curing phase can be divided into four key stages: heating, constant temperature, and cooling.

Heating: saturated steam is slowly injected into the autoclave, gradually raising the temperature and pressure to the set values. The heating rate must be properly controlled (typically 1-2°C per minute) to prevent cracking of the green pieces due to sudden temperature changes.

Constant temperature: Once the desired temperature and pressure are reached, the autoclave is maintained at this constant temperature for a period of time (typically 6-12 hours, depending on the type and size of the AAC block). During this stage, the hydrothermal reaction in the green blocks is fully developed, ensuring the blocks achieve the desired strength and properties.

Cooling: After the constant temperature phase, the steam supply is stopped and the autoclave is gradually cooled. The cooling rate is also controlled (typically 1-1.5°C per minute) to prevent thermal stress damage to the blocks. The curing process is complete when the temperature and pressure inside the autoclave return to normal levels.

2.2.3 Unloading

After the cooling phase, the autoclave lid is opened, and the carts containing the cured AAC blocks are transported out of the autoclave via a conveyor. The AAC blocks are then inspected for quality (e.g., density, strength, and appearance) before being sent to the next process or stored as finished products. After unloading, the autoclave interior is cleaned to remove any residual material and prepare for the next batch of curing operations.

3. Advantages of Autoclaves

3.1 Product Quality Assurance

The autoclave is key to ensuring the high quality of aerated concrete blocks. By providing a stable high-temperature and high-pressure environment, the hydrothermal reaction of the green blocks is fully carried out, resulting in uniform density (typically 500-800 kg/m³, meeting the standard density for aerated concrete blocks), high compressive strength (meeting the IS specification for aerated concrete blocks), and excellent thermal insulation properties (the thermal conductivity is significantly lower than that of conventional concrete blocks). Furthermore, the curing process within the autoclave ensures consistent product quality and reduces defective product rates. This makes the resulting AAC aerated concrete blocks, AAC bricks, and AAC concrete blocks highly competitive in the market, meeting the demand for high-quality building materials for various construction projects.

3.2 Production Efficiency and Energy Saving

Modern autoclaves are designed with efficiency at their core. Their large capacity allows for simultaneous curing of large numbers of AAC blocks, significantly improving the production efficiency of AAC production lines. For example, a medium-sized autoclave can cure thousands of AAC blocks at a time, which is crucial for meeting the production capacity requirements of AAC block plants. To further enhance energy efficiency, advanced autoclaves are equipped with efficient heat recovery systems. Waste heat generated during the cooling phase can be recovered and used to preheat the next batch of green bodies or for other heating purposes in the factory, thus reducing energy consumption and production costs.

Parameter table of Commonly Used Autoclaves for AAC Aerated Brick Production Line：