Research on stamp charging car coal box pressure through field test

Abstract

Coal box pressure has great significance in stamp charging car design. Because of the complexity of the dynamic constitutive relation of the coal powder, the pressure is usually considered in the design as a linear load, which presents neither the instantaneous maximum impact nor the variation during the stamping process, and therefore lacks accuracy. In this research, to obtain a more accurate box pressure, a series of field tests have been conducted, which included side wall tests, bottom plate tests and proof tests. The side wall and bottom plate pressures have been investigated through separating the pressure as 'impulse pressure' and 'coal pressure', which decouples the pressure curves from the side wall and bottom plate tests. As a consequence, a method to calculate box pressure at any time during the stamping has been derived through the analysis of statistic test results. To verify the method, a finite element method (FEM) model has been built and applied with pressures from the method. The FEM results fit well with the proof test result, which indicates that the method is capable of being used for stamp charging car design. In addition, the paper presents some statistic conclusions, such as stamping effect depth, which is useful for further researches. IntroductionThe stamp charging process is highly valued in coke making, for it not only increases the flexibility of the coal quality, but also improves the throughput of the oven. 1 The stamping charging operation is accomplished in a coal box on a stamp charging car.Recent research and experiments concerning stamp charging mainly focused on three aspects:(i) optimising the blending of material coal to improve coke quality 2-4 (ii) elastic-plastic behaviour of a certain coal cake during stamping and effects such as stamping energy, to coal cake quality 5-10 (iii) improvements on stamp charging manufacturing technique and car structure. 11,12 These researches concerned little about pressure on the coal box, which is the basis of a stamp charging car design. In current stamp coal box design, the pressure is usually considered as a linear load, which is not a true reflection of the process and lacks precision, e.g. the instantaneous stress of the structure cannot be identified and neither can the variation during the whole stamping process. As a result, the car design quality could be considered as flawed.In civil engineering and soil mechanics, similar research has been carried out, especially on retaining walls 13 and dynamic compaction; 14 however, these achievements cannot easily be utilised directly because of the differences in either the boundary condition or the impact load. It should be noted that the coal cake stamping itself is a problem because of repeated impacting unsaturated material, which is difficult to solve by regular means. Therefore, to determine the load on a stamp charging coal box, a test is necessary. In this research, the coal box pressure during stamping process was investigated through a field test. A methodology to analyse the c...

Stamping coal cake simulation with Duncan–Kelvin–Maxwell constitutive relations

“…Also presented are the numerical solutions of stress increment to the partial differential equations of the DKM model. Comparing to the earlier test results, 8 the simulating result has indicated that the DKM model can provide accurately the stamping pressure curves as well as other information for the charging car designers and reveal some inherent behaviours of the coal cake.…”

“…Gravity was involved in the process. According to the earlier field test, 8 the lifting height of stamper is set to 0·5 m, which means that the stamper’s initial velocity is v Y = −3·13 m s −1 . The process was divided into a sequence of three stages: initial set-up, gravity equilibrium and stamping impact.…”

“…[5][6][7] The stamping process itself is rarely studied so the lack of information on the stamping operation makes it difficult to analyse and optimise the design of the charging car and operational factors such as coal box pressure. Through a field test reported in an earlier work, 8 the stamp charging process was investigated, and a method to calculate coal box pressure for a certain car was presented. However, the method is not convenient because it is not possible to run the field test on every stamp charging car.…”