Application of measuring equipment in new dry process cement production enterprises


The production processes of cement companies are relatively diverse. New dry process cement production technology is currently the most widely used cement production technology and is also the cement production method that best represents the level of scientific and technological development. The new dry process cement production process includes raw fuel entering the factory, crushing, raw meal preparation, clinker calcination, cement production, etc. Modern cement production enterprises require high quality, high output, and low energy consumption. Accurate measurement control of the production process has become an important link. Measurement control is the key to ensuring the output and quality of new dry process cement production products. With the development of computer technology and measurement technology, measurement control technology has also developed rapidly. The new dry process cement production line includes hundreds of equipment, nearly a thousand motors, thousands of switches and valves, dozens of loops and hundreds of detection points. In order to ensure product quality and stable system operation, it must be realized through automatic control. The cement qualification rate is achieved by timely adjusting the feeding ratio of each raw material through the quality control system. It is particularly important to configure a measuring device for powdery materials and block materials with accurate measurement.

Metrological control is the measurement of material quality within unit time. In the cement production process, at least 3 tons of materials (including various raw materials, fuels, clinker, mixtures, and gypsum) must be ground for every ton of Portland cement produced. Selecting accurate measurement and control devices and optimizing process parameters are important means to ensure product quality and reduce energy consumption. How to ensure the stability and accuracy in the measurement control process, selecting equipment is the key. Briefly introduce the application of cement metering equipment from the perspective of new dry process cement production technology.

1. Measuring equipment used for raw and fuel materials entering the factory

Most companies that use cars or trains for transportation use rail scales; rail scales can be managed through real-time networking, installed and used rationally, and their accuracy and effectiveness can meet the requirements.

Most companies use belt weighing feeders in the entire logistics management process of raw and fuel input, storage, crushing, mixing and feeding. When using a belt weighing feeder, you need to consider the vibration of the belt conveyor, belt deviation, belt tightness, material adhesion, external climate and environmental changes, etc. To meet the measurement requirements, there are high requirements for the technology, design and manufacturing of belt scales. The installation must comply with specifications, strengthen daily maintenance, and calibrate on time.

2. Measuring equipment used for raw material ingredients and grinding

Quantitative feeder is mainly used for automatic continuous weighing, quantitative feeding and batching measurement control device of block, granular and powdery materials. As the scale of new dry process cement production lines increases, Double-layer Rotor Weigh Feeder and Granular Material Rotary Feeder are more suitable for large flow materials.

3. Measuring equipment used in clinker calcination process

The accurate and stable feeding of raw meal powder and coal powder is an important factor to ensure the stability of the sintering system, high quality and high output, and reduce energy consumption. In the new dry production process, the raw material feeding system at the end of the kiln is already a mature technology that is widely used. The raw material feeding system at the end of the kiln includes a flow stabilizing system, feeding device and metering equipment. In order to ensure the homogenization effect of the raw meal, the raw meal powder must first be stabilized before being fed quantitatively. Between the unloading of the homogenizing warehouse and the quantitative feeding device, there is a stable flow intermediate warehouse or a feeding device with backflow. The most commonly used one is a weighing intermediate warehouse. By controlling the unloading of the homogenization bin, a certain amount of raw material is maintained in the weighing intermediate bin, which is beneficial to stabilizing the raw material metering and quantitative feeding system, and can also be used to calibrate the raw material quantitative feeding system at the end of the lower kiln. Raw material feeding devices include impeller feeders, screw feeders, horizontal rotary feeders and electric flow control valves. The most commonly used flow control valve in new dry production lines is the flow control valve, which has the characteristics of simple use, low investment, and large control range. The metering equipment is mainly Coriolis Cement Raw Meal Powder Feeder post-compensation with good sealing performance.

The belt quantitative feeder can be adjusted in time, but it takes up a lot of space. Coriolis feeder has good stability and good sealing performance. Because pulverized coal has a light specific gravity, good fluidity, and is easily affected by airflow, the pulverized coal quantitative coal feeding control system includes a steady flow system, a feeding device, a metering device, and a conveying air locking device. The steady flow system is relatively independent, and the remaining three links can be combined according to different functions. Pulverized Coal Quantitative Feeder integrates the three links of coal feeding, metering and air locking into one device to improve control accuracy and reduce system complexity and mutual influence, but it has high technical requirements. The system composed of Coriolis flow meters handles the three links of feeding, metering and conveying air lock separately. The feeding device can use speed-regulated impeller feeder, screw feeder and horizontal rotating feeder; metering The device can use a Coriolis flow meter, etc.; the functions of each part of the system are clear, but each link affects each other.

There is currently no suitable solution for online real-time measurement of clinker output. The temperature of clinker is relatively high during the firing process, the clinker characteristics of the grate cooler are unstable, and high-temperature red material often appears. It is impossible to measure the clinker output in detail online in real time. Measuring, most of them calculate the mature material output through raw material feeding measurement.

The quantitative feeding of raw coal to the coal grinding head mostly uses a belt quantitative feeder, which can control the output of the coal mill, is easy to use, and has high accuracy in metering and quantitative feeding.

4. Measuring equipment used in the cement making process

Cement batching control is the key to metering and dosing in the cement making process. Similar to raw material batching, the cement grinding head batching metering equipment can use a speed-adjusted belt quantitative feeder. The cement production process is mature and high temperature has little impact on the quantitative feeder, which can meet the needs of cement batching and mill load control. In order to improve the utilization rate of cement-making raw materials, most companies adopt a cement-making process in which various materials are ground separately. After the clinker and mixed materials are ground separately, they are then mixed according to appropriate proportions to make cement. Due to the special separate grinding process, ultrafine powder with a higher specific surface area can be obtained, and the reasonable gradation of ultrafine particles can be used to exert its high activity, thereby reducing the usage of cement clinker. In this cement making process, powder quantitative feeding devices with different flow specifications need to be used for proportioning control. The metering and quantitative feeding are similar to the raw material feeding system.

5. Measuring equipment used in factory cement

Cement is shipped from the factory in two ways: bagged and bulk. Bagged cement adopts direct weighing method, computer control can adjust the bagging flow, and the measurement accuracy can be controlled above 0.5%. Generally, cement packaging machines are used for measurement, which are divided into fixed and rotary types. Nowadays, cement production companies mostly choose rotary cement packaging machines. The packaging machine counter is installed on the original computer board of the cement packaging machine, which can measure the packaging quantity of cement. Implement automatic measurement, automatic transmission, and automatic storage to realize the monitoring of cement output. Bulk cement is generally measured using Tank Feeding Bulk Powder. The measurement accuracy is generally about 1%, which can improve management level and loading efficiency.

6. Development direction of new dry process cement production measuring equipment and quantitative feeding

Measuring control and dosing systems not only involve many technologies and disciplines, but also include professional technical issues such as processes and materials. China's new dry process cement production technology has reached the international advanced level. Energy conservation and emission reduction, comprehensive utilization of resources and environmental protection are receiving more and more attention. With the improvement of new dry process cement production technology, how to maximize the utilization of industrial waste and daily garbage is the future development direction. There are many types of industrial waste , the corresponding measurement and quantitative feeding system can only be designed according to the specific situation. When dealing with domestic waste, some special problems will arise, such as pollution, corrosion, etc., which do not exist in the measurement of the original cement production line. Therefore, the measurement and quantitative feeding problems of domestic waste need to be solved when actual needs arise. The current material measurement technology is still based on traditional methods such as weighing or force measurement. The measurement method has many interference factors, especially for pneumatically transported powdery materials, and the system is too complex.

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