Research On The Feeding Stability Of Positive Pressure Pneumatic Conveying Cement

Pneumatic conveying is the use of having a dynamic pressure of the gas can convey powder particles in a sealed pipe technology. Because the technology with simple equipment, stable operation, convenient easy to automate control operation, flexible piping, etc. It is widely used in building materials, electricity, chemicals, food, metallurgy and other industries. Pneumatic conveying system according to the working pressure during the case can be divided into positive pressure Pressure feed, suction feed type and the hybrid combination of both. Wherein the positive pressure pneumatic conveying wider application due to the excellent stability, good controllability, long distance transport, etc, more suitable for conveying powder particulate material.Positive open pneumatic conveying is an important part of a positive pressure pneumatic conveying, because of their ease its pipe network layout, and low power consumption are widely used in cement powder pneumatic conveying. But in actual operation there is material when the material level falls below a certain level, the gas pressure tube was significantly higher than the static pressure in the silo solid powder produced, it will occur within the silo solid particle layer formed by the breakdown slugging, greatly reducing the solids concentration and transport capacity in the pipeline, the energy consumption was also increased significantly.This paper by Rizhao Haihui Group diameter 20m, height of 22m silo cement powder pneumatic conveying for the study, to solve these problems run its open pneumatic conveying equipment exist, respectively under the hair of silo design, research and development of new cutting equipment, the feeding process automatic control and so on three aspects to carry out the research, to be oriented type pneumatic conveying system solids feed stability guidance.Firstly, according to the similarity theory and the gas-solid flow mechanism designed sump pumps, in the design process to study the influence of particle size of the material properties, shape, friction angle and density, moisture content of pneumatic conveying. Detailed study of the physical properties of the parameters of pneumatic conveying of cement powder.According to the theory of two-phase flow, based on the research of pneumatic conveying of some common parameters on, Such as transmission capacity, solid-gas ratio, pressure loss, etc. According to the actual working conditions similar to theory and steel Rizhao Haihui Group cement silo design a new type of airtight silo,the sump pumps are designed to achieve the stability of the cement powder feeding.Secondly, features currently insufficient for suction Haihui Group under the sea means the existence of material, design and development of the venturi feeder. According to the venturi feeder working principle, structure and device characteristics, in theory, the use of the principle of conservation of mass and energy conservation equations for the structure of the nozzle, the gas velocity and gas mass flow rate derivation and research; On the basis of structural parameters of the venturi feeder were studied and analyzed, on the cross sectional dimensions as well as the various components of the venturi size and other structural parameters were analyzed and optimized design calculation, then get the best structure of venturi feeder.Finally, papers based on PLC and configuration software design a suitable for this type of pneumatic conveying automatic control system. The automatic control system uses PLC and PC configuration software approach to design control systems. PLC works using sequential scan, continuous cycle of work. According to the pneumatic conveying process and the design of the overall program use STEP 7-Micro/WIN V4.0 programming software to write PLC ladder program and simulation run, and use based on MCGS configuration control system was designed, edit script in the operation strategy, complete the operation of the system debugging in MCGS operation environment, simulation discovery, the control system can meet the design requirements of the open pneumatic conveying system and the actual project needs.