Experimental and Techno-economic Studies of Pipeline Hydro-transport of Agricultural Residue Biomass to a Biorefinery

Abstract

Pipeline hydro-transport of agricultural residue biomass to bio-based energy facilities, e.g. a bio-refinery, is considered to be a more economically favorable method than truck delivery. Pipeline hydro-transport not only benefits from economy of scale, but also reduces the environmental and traffic congestion issues compared to truck delivery. In this research, a 25 m closed-circuit lab-scale pipeline facility was designed and fabricated to experimentally investigate pipeline hydro-transport of knife-milled and pre-classified wheat straw and corn stover agricultural residues. Agricultural residue particle-water mixtures (or slurries) were prepared over a wide range of particle size, slurry solid mass content, and slurry bulk velocity, and were pumped into the closed-circuit. Several morphological and mechanical parameters were measured prior to and during pipelining agricultural residue particles through the pipeline. The main objectives of the research were to (1) study the particle size, particle size distribution, and morphological features of agricultural residue biomass; (2) study the technical feasibility of replacing truck with pipeline in agricultural residue biomass delivery; (3) experimentally investigate friction loss and rheological behaviors of agricultural residue biomass slurry through a pipeline at various slurry solid mass content, slurry bulk velocity, and agricultural residue biomass particles types and sizes; (4) develop an empirical correlation to predict the agricultural residue biomass slurry pressure drop across the pipeline; (5) evaluate the performance of centrifugal slurry pumps handling agricultural residue biomass slurry; and finally (6) conduct a series of techno-economic analyses on pipeline hydro-transport of agricultural residue biomass. Based on the results obtained in the study, agricultural residue biomass particles studied here were found to be fibrous in nature, and the slurry of fibrous agricultural residue biomass particles exhibited unique drag-reduction characteristics for more concentrated slurries at elevated velocities. In addition, the proposed empirical correlation was found capable of precisely predicting the longitudinal pressure gradient of the flow of agricultural residue biomass slurry in pipes, and the efficiency of the pump handling small (<3.2 mm) wheat straw particles was found to be more than the efficiency of the same pump handling pure water only. Finally, all the pipelines hydraulically transporting agricultural residue biomass with capacities of 1.0 M dry t/yr and more were found to have lower fixed and incremental costs compared to alternatives of hauling by truck. The results obtained here would help in optimizing the design and operation of commercial agricultural residue biomass pipeline hydro-transport processes and the development of large-scale bio-based energy facilities.