Developing and evaluating predictive conveyor belt wear models

Conveyor belt wear is an important consideration in the bulk materials handling industry. We define four belt wear rate metrics and develop a model to predict wear rates of new conveyor configurations using an industry dataset that includes ultrasonic thickness measurements, conveyor attributes, and conveyor throughput. All variables are expected to contribute in some way to explaining wear rate and are included in modeling. One specific metric, the maximum throughput-based wear rate, is selected as the prediction target, and cross-validation is used to evaluate the out-of-sample performance of random forest and linear regression algorithms. The random forest approach achieves a lower error of 0.152 mm/megatons (standard deviation [SD] = 0.0648). Permutation importance and partial dependence plots are computed to provide insights into the relationship between conveyor parameters and wear rate. This work demonstrates how belt wear rate can be quantified from imprecise thickness testing methods and provides a transparent modeling framework applicable to other supervised learning problems in risk and reliability.

Corn and Rice Starch-Based Bio-Plastics as Alternative Packaging Materials

Due to the negative environmental impacts of synthetic plastics, the development of biodegradable plastics for both industrial and commercial applications is essential today. Researchers have developed various starch-based composites for different applications. The present work investigates the corn and rice starch-based bioplastics for packaging applications. Various samples of bioplastics are produced, with different compositions of corn and rice starch, glycerol, citric acid, and gelatin. The tensile properties were improved after adding rice starch. However, water absorption and water solubility were reduced. On the basis of these results, the best sample was analyzed for thickness testing, biodegradability properties, SEM, hydrophilicity, thermogravimetric analysis, and sealing properties of bioplastic. The results show the suitability of rice and corn-based thermoplastic starch for packaging applications.

Digester thinning: Erosion-corrosion of internal flow channel headers

A softwood continuous digester has experienced severe erosion-corrosion of the shell wall inside the internal flow channel headers of the extraction and modified continuous cooking (MCC) zones. Although erosioncorrosion is a common form, it is not typically looked for inside digester flow channels. The worst damage was located where high velocity liquor exits the screen orifices and enters the collection headers. With erosion-corrosion rates as high as 200 m/year, the damage has effectively reduced the wall thickness almost by half in the worst areas. Also affected were the horizontal backing rings that form the bottom of the flow channels. An API-579/ASME FFS-1 Part 5, Level 2 analysis was performed to allow the mill to continue operating the digester until the next scheduled outage. Owner-users are encouraged to inspect these locations in their digesters to ensure that erosion-corrosion has not caused accelerated and/or unexpected shell thinning. The internal flow channels represent locations that are not readily accessible for internal visual inspection without removal of the flow channel header cover plates and removal of the residual black liquor typically retained in these flow channels. External, on-stream ultrasonic thickness testing (UT) at the proper collection header elevations has been determined to be an effective way to detect the presence of this erosion-corrosion phenomena. Also discussed are considerations to make on-stream UT as accurate as possible. Corrosion rates determined via electrochemical corrosion probe monitoring have correlated very well with the corrosion rates determined by on-stream UT data.