Evaluation of pneumatic inclined deck separator for high-ash Indian coals

Application of pneumatic separators in coal beneficiation is increasing rapidly over the last decade primarily due to their low capital and operating costs, and waste handling problems associated with traditional wet processing methods. Large amount of shale/rock that is extracted in coal production can be removed prior to transportation at the mine face by using this methodology. Due to the limited washing facilities in India, most of the thermal power plants burn raw coal from run-of-mine （ROM） to generate electricity. This practice causes poor utilization efficiency, high operating and maintenance costs, and high emission rates for the power plants. One potential method that can be utilized is the air-fluidized inclined vibrating deck technology. The technology was demonstrated on a pilot-scale at different coal washeries in India at a feed rate of 5-ton per hour. The pilot-scale evaluation showed that 20 %-25 % high-ash incombustible material can be eliminated from ROM feed with only minor losses in energy content （〈10 %） from respective ROM coal. Furthermore, a feasibility analysis showed significant economic gains in terms of transportation cost, improving power-plant efficiency, and reducing emissions rates by using the technology.

Study on Quality Improvement of Flue-cured Tobacco by Threshing and Pneumatic Separation

This study was conducted to further classify threshed strips, so as to broaden the usable range of raw material and facilitate the effective utilization of to- bacco resource. During the threshing and redwing process, various process param- eters including the rotating speeds of threshing drums of threshing machioe, draught fans and fling drums were scientifically and rationally set according to the actual quality of the raw material. According to the characteristic that strips with close in- herent quality have basically the same specific gravity and leaf thickness, the strips from each discharge hole were accurately evaluated, and classified, followed by redrying and packaging. The results showed that the threshing and separating pro- cedure could improve the separating effect and precision according to tobacco qual- ity, so as to satisfy the separation and classification requirements for tobacco.

DOUBLE LOOP ACTIVE VIBRATION CONTROL OF PNEUMATIC ISOLATOR WITH TWO SEPARATE CHAMBERS

A newly designed pneumatic spring with two separate chambers is promoted and double-loop active control is introduced to overcome the following drawbacks of passive pneumatic isolation： ① The low frequency resonances introduced into the system; ② Conflict between lower isolation frequency and stiffness high enough to limit quasi-static stroke;③ Inconsistent isolation level with different force load. The design of two separate chambers is for the purpose of tuning support frequency and force independently and each chamber is controlled by a different valve. The inner one of double-loop structure is pressure control, and in order to obtain good performance, nonlinearities compensation and motion flow rate compensation （MFRC） are added besides the basic cascade compensation, and the influence of tube length is studied. The outer loop has two functions： one is to eliminate the resonance caused by isolation support and to broaden the isolation frequency band by payload velocity feedback and base velocity feed forward, and the other is to tune support force and support stiffness simultaneously and independently, which means the support force will have no effect on support stiffness. Theoretical analysis and experiment results show that the three drawbacks are overcome simultaneously.

Pneumatic separation system for collected seedlings using subdivided air streams

To adhere to the needs of automated supply of collected seedlings for mechanized grafting and cutting machines for enhancing their operational efficiency,herein,a separation system that uses subdivided air streams to separate the collected seedlings is developed.The separation system comprises a feeder for supplying collected seedlings,a seedling separator that uses subdivided air streams,a picking belt for the separated seedlings,a delivery unit for the separated seedlings,a pneumatic unit,and a control unit.To investigate the complete performance of separation,picking,and delivery of the separation system,several separation experiments were conducted to separate the collected Anthurium seedlings.The results show that the consistency of the moving direction of seedlings floated by subdivided air streams in the separation container and the moving direction of the picking belt have a significant effect on the picking of the separated seedlings by the picking belt.Moreover,the seedling supply timing of the feeder has a significant effect on the stability of the collected seedling separation rate during continuous separation.When this timing is such that the percentage of separated seedlings is 70%,the separation rate of continuous separation operation is 2.24 plant/s(the separation productivity is 8060 plants/h)with 0.12 CV.The operating conditions are 0.5 MPa separation pressure,0.5 s nozzle operation time,and 60 mm seedling thickness in the separation container.Moreover,the staying times of the collected seedlings separated in the separation container are less than 2.5 min.

Aerodynamic and solid flow properties for flaxseeds for pneumatic separation by using air stream

This study aimed to develop simple empirical equations to predict flaxseeds properties.The first part of the present study deals with the physical,aerodynamic and solid flow properties of flaxseeds which are evaluated as a function of change in moisture content from 8.60%to 23.90%dry basis(d.b.),the dimensions of the length,width and thickness varied from 4.14 to 4.32 mm,2.03 to 2.13 mm and 0.88 to 0.93 mm,respectively.As the moisture content increased from 8.60%to 23.90%d.b.,the bulk density,true density and porosity were found to decrease from 46.65 to 44.89 kg/m3;1244 to 1176 kg/m3 and 46.65%to 44.89%,whereas angle of repose and terminal velocity were found to increase from 27.60 to 35.80 and 2.46 to 3.56 m/s,respectively.The static coefficient of friction on various surfaces,namely,plywood,stainless steel,galvanized iron,iron and internal also increased linearly with the increase in moisture content.The results of the experimental investigation may help to optimize some engineering parameters of separation equipment.The second part was carried out on a series of experiments to specify the optimum conditions of separating operation which insure the highest grade of separation efficiency with minimum losses.Pneumatic separation equipment was manufactured and tested under different combinations of the following factors:air stream velocity,feed rate and sample moisture content.The performance of the equipment was evaluated by using the indices separation efficiency and percentage of seed losses.The results of the equipment performances showed that the combinations of air stream velocity,feed rate and sample moisture content affected significantly the separation efficiency and grain losses.Air stream velocity of 2-6 m/s combined with 8.5 kg/h.feed rate and 8.6%moisture content can be considered the most favorable combination values of these variables.They gave the highest grades of separation efficiency and the minimum grain losses.