With the booming development of the construction industry, commercial concrete mixing plant have been popularized in municipal cities in coastal areas, and small and medium-sized commercial concrete mixing plants have also appeared in county (city) cities one after another.
Based on my experience in product design, on-site installation and construction, commissioning and testing of commercial concrete mixing plant, I would like to analyze the technical points in the preparation and initial operation of the plant, so as to discuss and exchange with the technical personnel of the same industry.
Determination of the overall plan
Determination of the scale and grade of the commercial concrete mixing plant
Determination of the scale of the mixing plant
Before determining the scale of investment, the investor should do a good job of market research as a matter of course. For internal use in the construction sector, the production capacity of the plant should be determined according to the construction capacity and the amount of commercial concrete used. For example, for highway or small-scale (1 year duration) projects, a mixing plant with a capacity of 1 to 1.5 m³ is generally used.
For commercial concrete mixing plant, the size of the plant should be decided according to the economic development of the region, the demand for commercial concrete and the investment capacity of the market in the region, and the capacity of the plant should be 1.5 m³ or more.
Determination of the grade of mixing plant
The investor should fully understand the product quality level, service capability and price of domestic and foreign construction manufacturers in the same industry, conduct market research, and examine the processing and quality assurance capability of the manufacturer on site. The manufacturer of the required set of equipment can be finally selected on the basis of merit by holding a defense meeting, a bidding meeting, etc., and choosing high-quality and inexpensive products. According to the amount of funds, determine the size and grade of the commercial concrete mixing plant. If the investment scale is small, you can choose the mixing plant with all the domestic supporting parts and the main machine with lower cost.
The electrical control system is also an important factor in determining the grade of the mixing plant. Manufacturers have control systems with different levels of automation for customers to choose from.
Site selection of the mixing plant
When choosing the site, it should be close to the stone quarry and sand plant, with sufficient water supply and far from residential areas. If you can make full use of the hillside terrain, set the site on the higher ground level of the hillside, which can reduce the loading height of the batching machine and make the loader climbing angle of the loading small or no climbing, which not only saves energy but also reduces wear and tear. When installing equipment foundation, pay attention to avoid above and below ground fiber optic cable, power supply or communication cable.
Determine the reasonable equipment configuration
The choice of aggregate supply method It is best to use loader to supply materials.
Selection of mixing plant If the mixing plant is used for highway construction (short duration and frequent moving), it should be of quick-loading and modular structure.
Selection of Aggregate Conveyor Belt Machine
If the site is wide, a small inclination angle (18°) flat belt conveyor should be preferred (to reduce equipment procurement cost, a lifting hopper can also be used). If the site area is restricted, a large inclination angle (generally 40°～50°) baffle belt machine (using additional belt structure, can reach 90°) can be considered. However, in the wet environment of sand and gravel, large inclination baffle belt machine has the disadvantage of sticky sand, and the phenomenon of sand falling under the belt is more serious when the belt returns, and the utilization coefficient of sand should be considered for commercial concrete proportioning.
Aggregate batching machine (scale) selection
A complete commercial concrete mixing plant aggregate scale for the cumulative measurement of 1 scale, separate measurement for 2 to 4 scales. In order to ensure that each aggregate has sufficient storage capacity, each aggregate can be designed and made into 2 scales for batching.
If the construction requirements are low, choose 2 kinds of aggregate cumulative metering batching machine; if the project has special requirements, it must choose 3 kinds or 4 kinds of aggregate scale cumulative metering batching machine, or even each kind of aggregate separate metering batching machine.
The choice of other scales can be determined according to the needs of the configuration of cement scales, fly ash scales, powder admixture scales (fed by the child spiral machine), water scales and liquid admixture scales (1 to 2), etc.
Such as the allocation of sand water content detector, through the microcomputer control, according to the different moisture content of sand, can realize the automatic adjustment of online water addition. The application of slump detector can effectively observe the homogeneity of commercial concrete.
The customer can choose a reasonable configuration according to the need and make provisions in the contract.
Inspection of the manufacturer
The customer should examine the general situation (production scale, production capacity, product quality level and service quality, etc.) of several key manufacturers. From the production process, production process, examine the manufacturer’s ability to guarantee the quality system. The prototype has been put into use for on-site inspection, listen to the views of the use of units, to understand the actual quality level of the equipment, the selection of supporting parts, etc.
During the inspection and contract negotiation, pay attention to direct communication with the manufacturer’s designers, especially for large and special requirements of the mixing plant, so that the designers can directly and clearly understand the customer’s requirements and working conditions, so as to develop the most appropriate design plan and avoid causing losses to the customer.
Problems to be noted in the contract signing process
The customer should ask the mixing plant manufacturer to provide a variety of layout options according to the objective conditions such as the geographical location of the mixing plant, and fully justify them so as to choose the best option.
Manufacturer to provide detailed information
The manufacturer should provide the performance profile of the product and the details of the equipment configuration, such as the model, specification and manufacturer of the main supporting parts, information on the host, host drive reducer, motor, electrical control system and main components. Each electronic scale sensor, various pumps, air compressors, admixture pumps, screw machines and vibrators, etc. should be itemized quotation. If as an annex to the contract, the technical documents provided should require the signature of the person in charge of the distribution and the technical person in charge.
In the overall arrangement of the aggregate batching equipment on the material height determination
The reasonable assessment principle for the height of aggregate batching equipment loading is: the base ground on the loading side of the loader is not higher (or not higher than 1m). The way to reach this requirement is to reduce the loading height of the aggregate batching equipment, so that the batching mechanism is installed below the ground level, when using the elevating hopper feeding method, it is required to lengthen the track, when using the belt machine feeding method, it is required to lengthen the belt machine. This issue must be clearly defined in the programmatic drawings of the contract.
Product quality requirements must be marked
The products shall be international standard commercial concrete mixing plant (building) technical conditions. The products must obtain the national license for manufacturing measuring instruments.
Requirements for transportation Each large part and packing box has a unified, clear and formal number to facilitate loading and unloading according to the technical requirements for transportation and inventory according to the list.
Requirements for spare parts Provide a list of wearing parts within 1 year, and purchase at the same time as the main machine.
Requirements for technical documentation in the annex
The technical documents to be provided as the contract proceeds to each stage should be clearly defined. The instruction manual should include sections on mechanical operation, maintenance, installation, commissioning requirements and calibration of the electronic weighing system, and 2 sets of information should be provided for construction and archiving purposes. In addition should also provide a list of wearing parts and atlas, electrical control manuals and other content.
The foundation construction stage of the commercial concrete station should provide foundation drawings that meet the requirements, clear (without delaying the construction, try to provide large format construction drawings by postal express, etc.), accurate and complete installation drawings and foundation plan, section drawings, pre-buried steel plate parts drawings, foot bolt drawings and underground cable trench layout drawings, etc. If there are pile foundation, reinforced commercial concrete building foundation works, etc., they must be designed by the units authorized by the architectural design department.
The contract must specify the manufacturer’s responsibility to guide the installation (or all installation) during the installation process. During the equipment installation stage, the manufacturer shall provide the general diagram of the whole installation, and the component diagrams of major systems. During the commissioning stage, the manufacturer shall provide the outline of installation and commissioning, the timing diagram of the operation of the mixing plant and the rules of acceptance, etc.
Requirements of supervision system
In order to ensure the quality, the customer has the right to request the manufacturer in the contract to send engineers and technicians to supervise the quality of the production process at the site of concrete production, and to participate in the production commissioning, inspection and acceptance of the products.
Content of training
The contract shall stipulate the specific measures of the manufacturer’s training to the customer. The customer should send operation and technical personnel to the manufacturing enterprise for training in advance, and a training certificate should be issued at the end of the training. In addition, let operators, maintenance technicians, electricians to participate in the installation, while learning, while operating is also a good method of on-site training.
Installation and commissioning and production
In order to ensure the normal operation of the equipment at the early stage of production and the quality of commercial concrete, the customer can explicitly request the manufacturer to send technical personnel to complete the technical guidance work for 1 month or a certain project in the contract.
According to the national measurement law, the commercial concrete mixing plant shall be subject to static calibration and material test by the local technical supervision department for cement scale, water scale, aggregate scale and admixture scale, etc., so as to inspect and accept the measurement system. After being put into production, an annual appraisal shall be conducted.
The production of commercial concrete should establish a complete quality assurance system, establish a quality manual and complete procedure documents, strengthen the original records, and put quality management into practice from raw material admission, production, finished product inspection and other aspects to effectively ensure product quality.
Strict and effective equipment management system is the guarantee of normal operation of the mixing plant. After the mixing plant is put into operation, the equipment repair and maintenance plan and spare parts management should be improved so as to improve the production efficiency and ensure the economic benefits.
In a word, the preparation process of commercial concrete mixing plant and the early stage of commissioning are the most critical periods. Only through good negotiation and implementation of contract, selection of economic and reasonable design, purchase of high quality equipment, installation and commissioning, and training of qualified operation and management personnel, can we establish a reliable guarantee for normal operation of the equipment, which will produce good economic and social benefits.