How to choose concrete batching plant host, powder and aggregate conveying and centralized control system

Concrete mixing plants generally use their production rate as the equipment model, such as HZS60 plant, which represents a production rate of 60m ³/h. Their productivity represents the theoretical productivity of the equipment. Due to the influence of factors such as mixing time and batching time in actual production, the actual productivity is generally around 70% of the theoretical productivity. When determining the model, not only should the engineering task be fully considered to leave room for the production capacity of the equipment, but also the peak amount of concrete and soil used during a certain period of time should be taken into account. If the annual production of 100000 cubic meters of concrete is completed, HZS90 station should be selected.

concrete mixing plant

1、 Selection of mixing host type

Hydropower station construction sites generally use hydraulic main mixers. Mixers with a nominal capacity of less than 3m ³ have been basically localized and the technology is basically mature. Mixers with a nominal capacity greater than 3m ³ (double horizontal shaft forced type and double cone tilting self falling type) are generally imported products with original packaging due to the lack of localization. At present, the most commonly used mixing plant is the double horizontal shaft forced type. Compared with the vertical shaft type, this type of mixer has a lower mixing shaft speed, shorter material movement distance, reduced blade liner wear, and lower energy consumption. Due to the full utilization of the shear and compression effects of the blades on concrete, the mixing quality has been improved, and the mixing time can be completed in 30-45 seconds, which can mix plastic and dry hard concrete. At the same time, the mixer has a high volumetric coefficient, small overall dimensions, and compact structure.

2、 Selection of powder and aggregate conveying systems and control systems

1. Selection requirements for powder and aggregate conveying systems

At present, most domestic mixing plants use screw conveyors to transport powder materials. The weighing device mainly uses weighing buckets and sensors. Generally, the appropriate screw conveyor is selected based on the nominal capacity of the mixing host. If a smaller mixing host chooses a larger screw conveyor, it will affect the accuracy of the ingredients, increase the relative error of the powder ingredients, thereby increasing the consumption of powder and increasing the production of wood; If a larger mixing host uses a screw conveyor that is too small, although the error is small, the feeding time is too long, which will affect the production efficiency of concrete.

The aggregate conveying system mainly consists of a storage hopper, a sand and gravel weighing system, a belt conveyor, and a frame. If the site is wide, a small inclination angle (18 °) flat belt conveyor should be preferred for transportation; If the site area is limited, a large inclination angle (usually 40 ° -50 °) edge guard belt conveyor (using an additional belt structure. It can reach 90 °) can be considered. However, in a humid environment with sand and gravel, the large angle edge blocking belt conveyor has the disadvantage of sticking sand. When the belt returns, the phenomenon of sand falling under the belt is more serious. Therefore, when using the edge blocking belt conveyor, the concrete mix ratio should consider the utilization coefficient of sand. A complete concrete mixing plant requires one aggregate scale for cumulative measurement, and 2-4 scales for individual measurement. To ensure measurement accuracy, a separate scale is generally used for each type of aggregate.

2. Selection requirements for control systems

In recent years, the control technology of concrete mixing plants has also developed rapidly with the development of computer technology. In the selection of control systems, the main focus is on understanding the precision requirements of the control system for concrete material batching. The control precision for raw materials should be controlled within ± 1%, with good stability and minimal accuracy drift. This can not only improve the production quality of concrete, but also save raw materials and improve operational efficiency.