Mini-plants

A 20ft-high mini plant has been built at BP s refinery at Grangemouth, near Edinburgh, as an experiment by several leading European petrochemical companies to address the difficult issue of plastic recycling. The 7501/ y pilot plant accepts mixed plastics ground into pieces a maximum of 2cm across and passes them over hot sand which converts them into a gas. This is distilled back into plastic feedstock which can be fed back into the petroehemical plant to make fresh plastic. This process eould be replieated at many small plants, located at ehemieal works or even beside municipal waste tips. 

Figure 4. Measured and model predicted residual monomer for mini-plant reactor run with new finishing process.

Rinard dedicated his research to a detailed analysis of methodological aspects of a micro-reactor plant concept which he also termed mini-plant production [85] (see also [4, 9, 10] for a commented, short description). Important criteria in this concept are JIT (Just-in-time) production, zero holdup, inherent safety, modularity and the KISS (keep it simple, stupid) principle. Based on this conceptual definition, Rinard describes different phases in plant development. Essential for his entire work is the pragmatic way of finding process solutions, truly of hybrid character ]149] (miniaturization only where really needed). Recent investigations are concerned with the scalability of hybrid micro-reactor plants and the limits thereof ]149], Expliddy he recommends jointly using micro- and meso-scale components. 

Quite new ideas for the reactor design of aqueous multiphase fluid/fluid reactions have been reported by researchers from Oxeno. In packed tubular reactors and under unconventional reaction conditions they observed very high space-time yields which increased the rate compared with conventional operation by a factor of 10 due to a combination of mass transfer area and kinetics [29]. Thus the old question of aqueous-biphase hydroformylation "Where does the reaction takes place " - i.e., at the interphase or the bulk of the liquid phase [23,56h] - is again questionable, at least under the conditions (packed tubular reactors, other hydrodynamic conditions, in mini plants, and in the unusual,and costly presence of ethylene glycol) and not in harsh industrial operation. The considerable reduction of the laminar boundary layer in highly loaded packed tubular reactors increases the mass transfer coefficients, thus Oxeno claim the successful hydroformylation of 1-octene [25a,26,29c,49a,49e,58d,58f], The search for a new reactor design may also include operation in microreactors [59]. 

Buschulte, T. K., Heimann, F., Verfahrensentwicklung durch Kombina-tion von ProzeiSsimulation und Mini-plant-Technik, Chem. Ing. Tech. 1995, 67, 718-724. 

Model Scale and the State of Flow Problems Concerning Mini Plants... 

The above remarks throw a critical view onto the contemporary efforts to simulate entire chemical processes on the smallest possible scale. Beyond all doubt, this technology can produce the proof about the feasibility of a synthesis. In addition, all process steps carried out in a homogeneous medium and dependent on micro-mixing, will be correctly executed on the micro-scale. Furthermore, the scale-dependent process steps will also be carried out in a satifactory manner on the micro-scale, because their scale-dependence could not express itself. But from these results no statement concerning the scale-up can be made In other words Mini-plants are not suitable to gain any scale-up rules for scale-dependent steps. 

The project started with experimental work in a small lab-scale unit (biomass throughput 2 kg/hr). The operation principle and preliminary results are presented elsewhere [2, 3,5]. The main conclusions which could be drawn was that operation of a reverse-flow slagging gasifier is technical feasible with promising performance. Based on these promising results of the small unit a mini-plant (20 kg/hr) was designed and constmeted. 

Based on promising results obtained in a lab-scale unit the design was made of a mini-plant with a capacity of 20 kg of biomass per hour. The mini-plant included air enrichment by membrane separation technology. 

The pilot plant is shown in Fig. 3. The longest period of continuous operation of the pilot plant was 120 hrs. In the mini plant tests (MP Test) scrap tires shredded into pieces about 10 mm in size were used. In the pilot plant tests (PP Test) scrap tires shredded into pieces about 50 mm in size as well as the fine shredded tires were used. 

Commercial plants Currently, more than 30 plants are in operation using NMP solvent for separation of 1,3 butadiene from mixed C s. While no commercial plants are currently operating for the separation of butanes and butenes using NMP as solvent, a mini-plant and a pilot plant have been operating for more than one year demonstrating this separation. 

No single system can be universal in showing uf the herbicidal potential of all compounds. No in vitro system using cells or mini-plants represents all tissues and all species. Herbicides can be tissue specific and species selective and different herbicides act at different rates. This requires that any universal pre-screen has to be multispecific, multi-tissue and multi-time. Many of the factors for consideration in developing such screens may superficially seem mundane or clearly apparent. Based on failures, this is only so in retrospect. 

Dedicated pre-screens for protectants would best be developed with in vitro cultures of the crop to be protected. This can be problematic with herbicides which affect photosynthesis when green photosynthetic cultures are not available. A pre-screen for protectants against diquat was set up using a duckweed mini-plant system (Figure 3). Such a system has the advantage that potential protectants can be seen by their effects on growth and color. They can also be quantifled by measuring 002 fixation or by chlorophyll extraction (2f). 

Okubayashi, S., Suzuma, T., Zhao, C., Miyazaki, K., Hirogaki, K., Tabata, 1., and Hori, T., Supercritical dyeing of polyester fibers in a mini-plant possessing internal circulator. Transactions of Sen-I Gakkaishi, 67, 27-33, 2011. 

A pilot plant demonstration of the process involves construction of a mini plant that typically processes 5%-10% of the actual feed flow. This plant uses membrane modules of the same size as those in the full-scale plant. The plant is usually operated for a minimum of 6 months so that membrane performance, fouling, pretreatment requirements, and design data can be fully established. The testing should be carried out using the actual waste stream that will eventually be treated with a full-scale membrane treatment system. 

G. Demopoulos, R. Molnar and L. Rosato, Bench scale and Mini-Plant Investigations on the Selective Removal of Iron From Zinc Process Solutions by Solvent Extraction , Iron Control and Disposal. J.E.Dutrizac and G.B. Harris, Eds., Canadian Institute of Mining, Metallurgy and Petroleum, Montreal, Canada, 1996,395-416. 

Table 4. Activity of Glycine Ester Analogues on Beef Heart NADH Oxidase and Vine Downy Mildew on Mini Plants...

Based on the R D experience gained on various systems, a lead mini plant with a processing capacity of 1 kg/day for processing the FBTR fuel is in the advanced stage of erection. 

Sometimes, also polynuclear clusters such as Rh4(CO)j2 or Rh6(CO)26 were submitted to the formation of rhodium catalysts [18]. Metallic rhodium embedded in inorganic materials (carbon, AI2O3) was tested for mini-plant manufacturing. In this context, the frequently phosphorus ligands [PPhj, P(OPh)3] were added with the intention to detach rhodium from the heterogeneous layer (activated rhodium catalyst = ARC) [19, 20] More recently, ligand (Xantphos, PPhj, BIPHEPHOS)-modified or unmodified rhodium(O) nanoparticles were used as catalyst precursors for solventless hydroformylation [21]. It is assumed that under the reaction conditions these metal nanoparticles decompose and merge into soluble mononuclear Rh species, which in turn catalyze the hydroformylation. 

An activated rhodium catalyst (ARC) [42], that is, rhodium layered on 5% alumina with PPhj as a modifier, was utilized to propose a hypothetical plant with 1000 mt scale production [43,44]. The hydroformylation was conducted in a mini-plant operating as a batch process (Figure 6.13). The Rh catalyst was recycled in a rotary oven at high temperatures. 

Different ratios of DMF and decane were tolerated. The separation of the product from the catalyst phase could be best realized at a DMF/decane ratio of 50 50. High aldehyde yields and lib ratios were noted even after several recycling experiments. Recently, a mini-plant was constructed based on these findings... 

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