Load-out Operations Research Articles

Load-Out and Hauling Cost Increase with Increasing Feedstock Production Area

The impact of average delivered feedstock cost on the overall financial viability of biorefineries is the focus of this study, and it is explored by modeling the efficient delivery of round bales of herbaceous biomass to a hypothetical biorefinery in the Piedmont, a physiographic region across five states in the Southeastern USA. The complete database (nominal 150,000 Mg/y biorefinery capacity) had 199 satellite storage locations (SSLs) within a 50-km radius of Gretna, a town in South Central Virginia USA, chosen as the biorefinery location. Two additional databases, nominal 50,000 Mg/y (29.1-km radius, 71 SSLs) and nominal 100,000 Mg/y (40-km radius, 133 SSLs) were created, and delivery was simulated for a 24/7 operation, 48 wk/y. The biorefinery capacities were 15.5, 31.1, and 47.3 bales/h for the 50,000, 100,000, and 150,000 Mg/y databases, respectively. Three load-outs operated simultaneously to supply the 15.5 bale/h biorefinery, six for the 31.1 bale/h biorefinery, and nine for the 47.3 bale/h biorefinery. The required truck fleet was three, six, and nine trucks, respectively. The cost for load-out and delivery was 11.63 USD/Mg for the 50,000 Mg/y biorefinery. It increased to 12.46 and 12.99 USD/Mg as the biorefinery capacity doubled to 100,000 Mg/y and tripled to 150,000 Mg/y. Most of the cost increase was due to an increase in truck cost as haul distance increased with the radius of the feedstock supply area. There was a small increase in load-out cost due to an increased cost for travel to support the load-out operations. The less-than-expected increase in average hauling cost for the increase in feedstock production area highlights the influence of efficient scheduling achieved with central control of the truck fleet.

Central Control for Optimized Herbaceous Feedstock Delivery to a Biorefinery from Satellite Storage Locations

The delivery of herbaceous feedstock from satellite storage locations (SSLs) to a biorefinery or preprocessing depot is a logistics problem that must be optimized before a new bioenergy industry can be realized. Both load-out productivity, defined as the loading of 5 × 4 round bales into a 20-bale rack at the SSL, and truck productivity, defined as the hauling of bales from the SSLs to the biorefinery, must be maximized. Productivity (Mg/d) is maximized and cost (USD/Mg) is minimized when approximately the same number the loads is received each day. To achieve this, a central control model is proposed, where a feedstock manager at the biorefinery can dispatch a truck to any SSL where a load will be available when the truck arrives. Simulations of this central control model for different numbers of simultaneous load-out operations were performed using a database of potential production fields within a 50 km radius of a theoretical biorefinery in Gretna, VA. The minimum delivered cost (i.e., load-out plus truck) was achieved with nine load-outs and a fleet of eight trucks. The estimated cost was 11.24 and 11.62 USD/Mg of annual biorefinery capacity (assuming 24/7 operation over 48 wk/y for a total of approximately 150,000 Mg/y) for the load-out and truck, respectively. The two costs were approximately equal, reinforcing the desirability of a central control to maximize the productivity of these two key operations simultaneously.

Elastic design of skid beams in offshore load-out systems

Skid beams are essential components in skidded load-out systems, widely used in offshore operations, and are usually made in plate or box girder forms. They are continued from the jetty to the barge for a relatively long length and are the foundation of portable superstructures to transfer the distributed vertical load to the jetty/barge. Finite element analysis is usually used to verify the strength and stability of the skid beams' components, including flange, web, and stiffener. As FEM usually includes many analyses with a trial-and-error process, this study presents a general and explicit design procedure for skid beams in load-out operations. The main design criteria are the flange's bending capacity as well as the web and stiffener's buckling capacity. The generalized integral transform technique (GITT) is applied to solve the bending equation of the flange and the buckling equations of the web and stiffener with hinged and rigid connections. An algorithm is suggested by which some design curves (concise formulas) are obtained to find the maximum slenderness ratios of the skid beam's components. Accordingly, a step-by-step design procedure is presented, which can be easily used for practical purposes and can be a better replacement for finite element analysis. Comparing the analytical method with FE modeling, there is acceptable agreement and excellent convergence. A realistic design shows that the reduction of skid beam weight is not more than 10% due to rigid connections. In addition, the weight is reduced by increasing the web and decreasing the stiffener aspect ratios.

Reliability analysis of a load-out support frame in offshore installations

ABSTRACTWhen an offshore platform topside is constructed in a yard, it should be loaded-out onto a transportation vessel. The load-out operations, however, involves many uncertainties, such as changing the load (weight of the topside platform) on the LSF or possible structural failures. The load on the LSF should be evaluated, as even a small failure in a structural member or a welding connection can lead to structural instability, or even catastrophic structural collapse. This study presents a newly developed method for analyzing the structural reliability of the LSF. The probability of failure is calculated by using AFOSM method assessment along with response surface methods. This proposed approach can provide a better understanding of safety requirements, so that the over-design of structures can be avoided. Furthermore, it can provide the coordinators of load-out operations with a better set of guidelines for determining the probability of failure during the load-out process.

On prediction of torque in flexible pipe reeling operations using a Lagrangian–Eulerian FE framework

In this paper a new framework for FE simulation of reeling operations that utilizes a Lagrangian–Eulerian description of the beam kinematics is proposed. In contrast to the conventional Lagrangian approach, the material is enabled to flow with an axial velocity through a nearly space-fixed beam mesh. This gives far more effective and robust simulations since the length of the beam model reduces significantly and because the contact geometry undergoes less changes. The main ingredients of the Lagrangian–Eulerian framework and a flexible pipe beam model are presented. An idealized spoolbase-vessel load-out operation is considered in order to gain insight into the torsional failures experienced by subsea contractors in recent years. Here, three different mechanisms were found to provoke torsional failure of the pipe. Strategies to avoid the torsional failures and FE modeling remarks are provided.

Optimization of ballast plan in launch jacket load-out

The calculation of ballast plan in load-out operations is generally performed assuming a rigid barge. This assumption may not be reliable since in reality the barge is flexible. Having incorrect ballast plan may lead to overstressing of the loaded-out structure. We present a method of finding a more accurate ballast plan, taking into account the flexibility of the barge. This method makes use of a multi-objective evolutionary algorithm to find the optimum ballast arrangement at every load-out stage. We model the load-out configuration as a beam on elastic foundation, loaded with distributed trapezoidal loading representing the load from the structure. Minimizing deflection and curvature of the beam, as well as maximizing the ballast transfer efficiency between the load-out stages are chosen as the objectives of the algorithm. It is shown that the proposed method is better than the conventional rigid barge method in terms of minimizing the deflection and curvature as well as maximizing the ballast transfer efficiency.

Development of load-out design methodology and numerical strength evaluation for on-ground-build floating storage and offloading system

This paper presents the design methodology and numerical strength evaluation for the Floating Storage and Offloading system (FSO) that was built on the ground without dry dock facilities. This was the first attempt to build FSO entirely on the ground and to launch it using two submersible barges. Successful load-out and float-off of 340,000 DWT Class Very Large Crude Carrier (VLCC) size AMENAM KPONO/FSO were carried out at the end of July 2002. The main feature of this successful operation includes the heavy weight and long length compared to breadth and depth of the load-out structure. It was 298 m long and weighs about 53,000 tons. So, special consideration was required to ensure safe load-out, towing and float-off operations compared with previous load-out of other offshore structures in which case the weight was less than 30,000 Mtons. The strength and longitudinal deflection of FSO were carefully designed/analyzed using Hydraulic Jacking System. Various systems and methodology for load-out including FSO fabrication and erection method on the ground, soil strength and stability quay wall located in offshore yard, operation of two multipurpose semi-submersible barges were all combined to develop a successful ‘Ground build method’. The load-out operation was carried out using two semi-submersible barges connected together by rigid frame structures. The ballasting operation of double barge unit (DBU) can be controlled like a single barge using a load master control software (LMC). Throughout the operation, relative deflection in the form of DBU connection frames was monitored and DBU motion were analyzed and compared to our model test result. After 4 years of dedicated research, we were finally succeeded in confirming the technology of Ground Build design of floating structure, construction, load-out and float-off.

A NEW FRAMEWORK FOR SIMULATION OF MATERIAL FLOWS ON MINE CONVEYOR NETWORKS

Mineral Resources EngineeringVol. 04, No. 03, pp. 265-295 (1995) No AccessA NEW FRAMEWORK FOR SIMULATION OF MATERIAL FLOWS ON MINE CONVEYOR NETWORKSJON C. YINGLING and ANIL KUMARJON C. YINGLINGDepartment of Mining Engineering, University of Kentucky, 234D Mining and Mineral Resources Building Lexington, KY 40506–0107, USA Search for more papers by this author and ANIL KUMARDepartment of Mining Engineering, University of Kentucky, 234D Mining and Mineral Resources Building Lexington, KY 40506–0107, USA Search for more papers by this author https://doi.org/10.1142/S0950609895000266Cited by:3 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractA number of state variables important to bulk material conveyor simulation models vary continuously with time, e.g. the position of material along the beltline or the level of material in a feeder, bunker, or discharging/receiving vehicle. Ostensibly, the generation of time histories of these state variables requires continuous simulation, and most belt simulation packages execute what is essentially a continuous simulation using various discretization approaches. However, since it is reasonable to assume that the derivatives of these continuous variables change at discrete points in time, one alternatively can model the system using a higher-order discrete approach. Such an approach is developed in this paper. Advantages offered by the new framework include (1) improved accuracy, (2) faster execution, (3) the ability to realistically interface with models of production or loadout operations, and (4) the ability to study the performance of a wide array of real-time control systems. The framework has been implemented using the event-scheduling interface to the SIMAN simulation language, but it could readily be employed with other discrete-event simulation languages. The framework is demonstrated in examples involving an integrated track/belt haulage system and a system for reduction of peak loads on gathering belts that involves real-time control of feeder discharge rates. FiguresReferencesRelatedDetailsCited By 3Discrete-Event Simulation of Continuous Mining Systems in Multi-layer Lignite DepositsTheodore N. Michalakopoulos, Christos P. Roumpos, Michael J. Galetakis and George N. Panagiotou1 Jan 2015Applying Queuing Theory and Simulation to a Gold Mine Locomotive Selection Problem in BrazilP. C. B. Magalhães and C. M. Vitorino14 December 2017 | OPSEARCH, Vol. 39, No. 1On-line control strategies to minimize peak loads on mine conveyor networks using surge units with variable discharging capabilityJ.C. Yingling, Z. Luo and J. Sottile1 Jan 1997 | IEEE Transactions on Industry Applications, Vol. 33, No. 1 Recommended Vol. 04, No. 03 Metrics History PDF download