Yuanhui Zhang
University of Illinois at Urbana-Champaign
The thermal chemical conversion (TCC) process is “a chemical reforming process in a heated and pressurized enclosure, in the absence of free oxygen, where long-chain organic compounds (solid waste) break into short-chain molecules (liquid oil).” Initial research using the TCC process to convert fresh swine manure to oil was conducted on 230 different batches. Optimum operating conditions were identified as 275-305 oC, 900-1500 psi, 20% solid content, 30-120 minute retention time, 1:7.5 ration (by weight) of carbon monoxide to volatile solids and 6.5 pH. The products formed from the conversion of the volatile solids averaged 70% oil, 15% gasses, 6% inerts and 8% water. Development of a continuous bench scale TCC reactor (CTCC) required the addition of a pre-processing shear mixer to reduce particle size and increase homogeneity, a oscillating/rotating feeder to permit additions of manure to the high pressure tank, a continuously stirred tank reactor and a separation vessel. Analysis of the oil produced indicated a low sulfur, heavy oil (low boiling point) that could be burned for heat or electricity or used as an alternative for crude oil products such as plastics. Collaboration with industry is underway to develop a pilot plant but additional research is needed to assess the effect of aging of the manure as well as to optimize the system for other materials such as dairy manure or biosolids. The TCC has the potential to provide up to 50 million barrels of oil per year from the hog manure produced in the US while improving the profitability of livestock producers and reducing the potential of negative environmental impacts from manure handling
To view the slides from Dr. Zhang’s presentation, click on the link under seminars at http://www.oardc.ohio-state.edu/ocamm/
To read about Dr. Zhang’s work in more detail, see http://www.age.uiuc.edu/bee/RESEARCH/tcc/tccpaper3.htm
Discussion:
Betty Ayslworth (OSU) asked if the University of Illinois had any patent protections on the process or if companies have funded the research. Zhang responded that the only patents at this time are on some of the engineering processes for the continuous system. The TCC process itself has not been patented and the primary funding for the research has been from public sources. There is a licensing agreement between UIUC and an Bioenergy industry based on ‘know-how’.
David Munn (OSU) asked how much energy must be input, both theoretically and based on the batch tests, to create a kilogram of oil. Zhang noted that for every unit of energy put into the systems, three units of energy based on the optimum conversion rate. The energy yield also assumes that no energy required to produce the manure as it is a by-product. Additional work is needed to add a heat exchanger to the system to recapture the heat.
Participant in Lima requested a comparison of the “fingerprint” of the TCC oil to standard heavy petroleum crude oils produced in North America. Dr. Ocefemia, a post-doc working on the TCC project, responded that the oil is very heavy but lighter than oil from tar sands. While it has not been fingerprinted, analyses indicate approximately 40% asphaltenes.
Mark Smith (NRCS) asked about the potential for having a CTCC reactor on site at a swine operation. Zhang replied that two options have been discussed: 1) an on-farm reactor and 2) a central reactor site requiring transport of manure. The preference is on-farm, especially if a furnace-size unit that could fractionate the oil on-site was developed, allowing on-site use of the products. Another alternative would be to transport the oil off-site for processing. If constructed as modules, the size of the reactor could be increased as needed by adding additional units.
Harold Keener (OSU) asked if the by-products from the TCC process contain nitrogen, phosphorus and/or potash. Zhang responded that the oil is low in sulfur but has is approximately 4% in nitrogen than petroleum sources of oil. The phosphorus and potassium are primarily in the solids that remain which could be used as a soil conditioner. The gas produced by the system is approximately 98% carbon dioxide.
Notes by Mary Wicks
The OCAMM (Ohio Composting and Manure Management) Program is funded by OARDC/OSU.