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|Title:||Feasibility of an integrated biogas scrubber for a swine manure digester|
|Author(s):||North, John Robert|
|Doctoral Committee Chair(s):||Day, Donald L.|
|Department / Program:||Agricultural and Biological Engineering|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
Engineering, Sanitary and Municipal
|Abstract:||Laboratory experiments were conducted to study a scrubbing system for the removal of carbon dioxide (CO$\sb2$) from the biogas produced by a swine manure anaerobic digester. This innovative scrubbing system was included in the original design of an existing full-scale digester, but had never been tested. The principle of operation was that ammonia (NH$\sb3$) gas would be desorbed from the influent manure in an enclosed preheating vessel, the mix tank, and subsequently reabsorbed in a separate scrub tank full of water (charging cycle). The biogas was passed through this charged scrubbing solution (scrubbing cycle). The CO$\sb2$ would then be absorbed from the biogas stream, producing a higher quality gas in terms of methane content.
Scale models of the full-scale system were constructed and operated in the lab. The critical parameters studied were the pH of the manure slurry in the mix tank, the frequency of operation of the charging cycle, and the rate of turnover of the scrubbing solution. The objectives of this study were to determine the effect of the variation of these parameters on the efficiency of the scrubbing process, and to assess the physical and economic feasibility of incorporating any beneficial modifications into the full-scale system.
The experimental results showed that the scrubbing mechanism described above did not work. Minimal amounts of NH$\sb3$ were transferred from the manure to the scrubbing solution. However, significant CO$\sb2$ removals were achieved via a different mechanism. The charging cycle transferred the biogas (and CO$\sb2$) from the scrub tank to the mix tank, where it was absorbed into the manure. The scrubbing efficiency was directly proportional to the manure pH and the charging cycle frequency. The maximum CO$\sb2$ removal was about 77% corresponding to an average mix tank pH of about 9 and a charging cycle frequency of 4 cycles per hour.
It was determined that this scrubbing process would not be feasible for this application, due to the large quantities, and costs, of alkali required to maintain the manure pH at a beneficial level.
|Rights Information:||Copyright 1990 North, John Robert|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9026283|
This item appears in the following Collection(s)
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Agricultural and Biological Engineering