Detection, Control And Experimental Study Of Heavy Medium Cyclone Separation Density In The Magnetic Field

Three product heavy medium cyclone has made widely in the world, especially in China, it is by series consist of two two-product-heavy medium cyclone. In terms of Heavy medium separation process control, the separation density of the first paragraph has been achieved by the PID closed-loop regulation, but Sec density control cannot be regulated on line, so the system is necessary to ensure the first paragraph separation density and ash of clean coal also take into account the Sec density and middle ash, it is difficult to achieve the best fit. This thesis studied for sec-separation density of three product heavy medium cyclone online regulation’s difficult technical problems.This paper build and design heavy media separation system, data collection of sorting process and sorting density control system, on this basis, conducted a series of experiments cyclone separation density variation under the permanent magnet solenoid magnetic field and the magnetic field, and simulated the magnetic field inside the cyclone, revealing the variation of the magnetic field for the realization of heavy medium cyclone separation density of online regulation conducted a preliminary exploration.First, the design of the heavy media separation experiment platform, including selection and installation of cyclones, mixing tank, feed pumps and other equipment, and on this basis, the focus on heavy medium cyclone suspension, designed medium cyclone feed, overflow and underflow density detection methods, installation location and installation mode, created conditions for further signal acquisition.Around the heavy media separation process, designed heavy media separation process signal acquisition system, including selection and design of detecting flow, pressure, density and other sensors, selection and design of controllers PLC, choices of human interface and design of communications, and a complete signal acquisition system based on this design.To stabilize heavy media separation processes, real-time acquisition and analysis of variation election process and the separation density under an external magnetic field of heavy medium, based on the design of signal acquisition system, carried design control system of heavy medium cyclone separation density, designed based on preset (coarse) expert system rules and perfect for the follow-up work to fine-tune PID closed-loop control system, thus forming a complete control system solution, provides a stable and reliable platform and environment of next cyclone separation density variation under the magnetic field.Different separation density and the corresponding current density and location parameters to build expert rules table, When you enter the required density sorting, automatic control system automatically matches the desired parameter values from the expert system library, The signal transmission via remote communications DC power supply to the coil. Control system establishes both manual and automatic modes, Auto mode is used to enter the required density sorting, automatic matching corresponding parameters; manual mode does not match the expert system through direct input coil current.When the system is stable, you can start PID control, real-time acquisition calculated density values constantly compared with the values given as feedback to make the difference, the system automatically fine-tune the current value, to ensure the stable of sorting density systems, effectively corrected the outside interference.On the previous sorting platform, we studied the variation of separation density within cyclone under the permanent magnetic field. By placing a permanent magnetic field around the cyclone overflow pipe, cone section and bottom orifice and carrying suspension medium study without coal find:1、Arrange permanent magnetic around the cyclone overflow pipe can reduces separation density, with the increase of the thickness of the magnetic pole, resulting in a greater decrease in the magnitude of separation density;2、Arrange permanent magnetic around the cyclone cone section can also reduce separation density;3、Arrange permanent magnetic around the cyclone bottom orifice can increases separation density;4、In the conditions of the permanent magnetic field, the separation density increased most dramatically is0.4g/cm3, field located at the bottom orifice, magnetic pole thickness of30mm; The separation density reduced most dramatically is0.05g/cm3, field located at the overflow pipe, the magnetic pole thickness of60mm.By simulating the magnetic field can be derived the magnetic field strength distribution and changes, with the increase of magnetic field intensity distribution is more uniform, the magnetic force applied to the magnetic particles inside the cyclone makes the particles adsorbed on the inner wall of the cyclone, to varying diameter, thus realizing the adjustment.On the previous sorting platform, we studied the variation of separation density within cyclone under the electromagnetic field. By placing a coil outside the cyclone impact separation density at different locations and different magnetic field strength; By the test results of solenoid coil, small shield, large shield and fully shielded conditions can be seen: 1、Coil is located near the interface between column and cone,when the current increases, the electromagnetic field generated by the coil can increases separation density, and also gradually improve sorting accuracy;2、In the middle section of the cone, the magnetic weakens the separation density increasing, the size of a current began after separation density decreased;3、Coil is located at the bottom of the cone and the bottom orifice, can reduce the separation density, and the greater shielding effect, smaller separation density can be reduced, but at the same sorting accuracy is not high.4、The coil to enhance the separation density can reach the maximum0.2g/cm3, coil arrangement position is the interface between cone and column at full shielding conditions, the current value needs40A; the coil to reduce the separation density can reach the maximum0.14g/cm3, coil arrangement position is the lower300mm than the interface between cone and column at full shielding conditions, the current value needs40A.