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HEAD LOSS OF BEEF MANURE SLURRY FLOW IN POLYVINYLCHLORIDE PIPE.
Abstract
The objectives of the investigation were to determine beef manure slurry flow rates and pressure gradients in the pipe flow through 51, 76, and 102 mm polyvinyl chloride (PVC 160) pipe and to determine its head losses as a function of flow velocity and total solids content.
... B1. Modstandstallet, λ, ved rørtransport af gylle med forskelligt tørstofindhold(Rolfes et al., 1977). ...
... Early experimental work in the pumping of manure slurries focused on feasibility and a gross measurement of pressure drop, without developing a detailed analysis of the rheological properties of the manure slurry. Rolfes et al. (1977) assessed the friction head loss in beef manure PVC pipelines as a function of flow velocity, total solids (TS) concentration, and pipe size and found that head loss increases with increasing TS. They concluded that water head loss criteria were definitely inadequate for use in designing manure pumping systems. ...
Anaerobic digestion (AD) of manure can extract useful energy in the form of a medium heating value gas. AD has been implemented on a variety of scales, from small farm-based units to centralized digesters processing manure from multiple sources. AD has significant economies of scale, i.e., per unit processing costs decrease with increasing size. Some regions have a very high concentration of beef cattle infeedlots. For example, near Lethbridge, Alberta, more than a million beef cattle are in feedlots at any point in time; the comparable figure for Dodge City, Kansas, is more than two million. As part of a larger study of the economics of centralized manure processing, we have developed an economic model for the pipelining of beef cattle manure to a centralized AD plant and digestate from the plant back to the manure source for spreading. The model combines rheological and fluid mechanical properties for manure slurry with design and economic data for a pipeline and pumping stations. The model calculates an overall transportation cost for slurried manure that includes capital recovery. Unlike trucking, pipeline transportation of manure has a strong scale dependency; the unit transport cost decreases with increasing capacity. Manure pipelining costs are minimized when transporting manure at 12% to 14% slurry solids concentration in the pipeline. Two-way pipelines carrying manure to and digestate from the plant require less capital investment and operating costs relative to two separate manure and digestate pipelines. © 2006 American Society of Agricultural and Biological Engineers.
... While the loss of OM from stored slurry may lead to a loss in the potential for CH 4 production and for improvement in soil physical properties, the accompanying loss in slurry TS could be an advantage in terms of the ease of slurry handling. In general, the higher the TS concentration in slurry, the more difficult it is to keep slurry pumps operating (Hart et al., 1966), and the greater is the frictional pressure drop in slurry pipelines (Rolfes et al., 1977; Patni, 1981). Information is required on the transformations and losses of TS, VS and carbon (C) in stored slurries in order to develop guidelines for improved management and utilization of manure slurries. ...
Changes in Total Solidsby weight and volume (TSw and TSv), Fixed and Volatile Solids (FS and VS) and Total Carbon (TC) in dairy-cattle liquid manure slurry during undisturbed storage in covered concrete tanks, 12·3 × 7·2 × 3·0m deep were studied. Slurry with nearly 10% TSw was stored from January to October (285 days) in two tanks and , similarly, from June to Novemmber (146 days). Slurry samples were periodically collected from each of the tanks at two locations at depths of 0·3, 1·0, 1·8 and 2·5 m below surface. Slurry TSv were determined by high-speed centrifuging.Substantial spatial and temporal concentration variations occurred in slurry TSw, TSv,FS and VS. Most of the concentration change and loss of TSw, TSv and VS was limited to the top 1 m of the slurry. Settling of solids did not appear to be an important process in the stores slurry. Large concentration changes were limited to the top 0·3 m only for about 6 months after winter and 3 months after summer-filling of the tanks. Thus, most of the initial organic matter and biogas generation potential was probably retained in the slurry at depths of 1 m or more. The rate and location of TSw concentration decreases suggested that VS biodegradation occurred mainly due to aerobic processes, starting near the surface and progressing downwards with time. Mass balances indicated that about one quarter of the initial TSw, VS and TC were lost by the end of the storage period in all tanks. Correlations between TSw and TSv and between wet-basis TC and TSw or TSv were highly significant.
This work presents the findings of a review of research literature on the handling characteristics of agricultural slurries. The features which affect these characteristics and the ways in which they change the handling behaviour of the slurries are included, and the results from different researchers are critically compared. A definitive method of characterizing slurry with respect to its handling properties is needed if a more scientific approach to the design of slurry treatment and handling systems is to be developed.
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