Plant miniplant

Setting up costs A rough estimate of the costs of setting up a small-scale plant (miniplant, see Section 4.4) is sufficient since this item is normally the smallest in the development costs. Once some notion of the process is available (a rough process flow diagram), these costs can be determined with reasonable accuracy. 

Davister, A. 1991. Technological Options for Construction of Fertilizer Plants - Miniplants, UNIDO-NFC Pakistan Workshop on Appropriate Strategies for Fertilizer Technology and Development, Lahore,... 

Whereas in a micro plant only the most important process steps and some of the recycle loops are tested, in the miniplant the complete process with all recycle loops is executed and processed continuously for several weeks. For environmental and economic reasons, solvents and unconverted reactants are recycled. Here, it is especially important to find out if small impurities below the detection limit will possibly accumulate or form deposits. To minimize the up-scaling risk for the final production plant, often a pilot plant is the next scale-up step. Now the final product is produced and often first samples are sent to customers. Every step in this scale-up procedure is followed by an evaluation step defined in a number of evaluation studies, which assist in the decision as to whether the project has to be terminated, repeated or further processed. 

With the introduction of advanced process simulation tools [25], the so-called integrated process development established. Here the most time-consuming pilot plant phase is bypassed by a combined approach of experimental miniplant testing and numerical process modeling. 

Miniplant Technology - A Model for the Micro Structured Reactor Plant Concept... 

As miniplant technology must be considered as a model for micro structured reactor plant technology, a closer look into its working principles is very illustrative. All characteristics of a miniplant were described by the inventors of this technology, Dow, in 1979 [28] and BASF [29], which also introduced the combined simulation/ experimentation concept (Figure 4.2). 

The above-mentioned integrated process development combines simulation tools with miniplant equipment to bypass the set-up of a pilot-scale plant Similar to this combined approach, a micro structured reactor plant can bridge laboratory-scale and micro-scale development. One could think of a future micro-integrated process... 

It must be pointed out again that even today confusion of terms can be observed when chemical engineers discuss miniplants or microplants . In most of these cases they identify with the terms mentioned above chemical plants made of glassware with volumes in the range of up to a few liters. To summarize, at that early stage no specialized micro structured reactors for production purposes were available. Most of the fabricated micro structured devices were made in terms of micro fabrication capabilities and not adapted to the chosen chemical process. It is no wonder that at first visionary theoretical work either had to be based on conventionally fabricated chemical reactors or did not outline reactor design in detail [30],... 

These disadvantages should be overcome by miniplants, generally defined similar as in [1, 60], strictly based on a modular design. In order to adapt to varying needs, several modules may be operated in parallel. Typical module capacities range from 100,000 to 1,000,000 lb/yr. Operation of the miniplants should be so reliable and simple that the majority of these plants can be operated by personnel not specially skilled in process technology. Start-up and shutdown have to be performed fast to allow just-in-time production. The entire plant should be transportable including footprint and containment volume. 

In a microstructured reactor plant, in contrast, the flow rate will be dominated by the pressure loss. Typical pressure losses in micro devices are of the order of 1 bar at a flow of 11 h 1 (water) [50,93], If sufficient pump capacity is available, the pressure loss in a micro structured device is limited by the mechanical stability of the reactor housing, which is often made of steel and hence a loss of several bar is certainly acceptable. Even the combination of up to 10 different micro devices only amounts to about 10 bar in this example. The main advantage of a micro structured reactor plant is that the flow rate can be adjusted more freely because the flow is pressure driven and not influenced by a single gravity-driven device as in a miniplant. 

In the above-described pChemTec project, a combination of miniplant and micro structured reactor plant equipment is used for the organoborane synthesis as an example for a future production facility for fine chemicals. This approach differs from the usual application of a miniplant as a mediator between laboratory-scale and pilot plant-scale operation. The microstructured reactor plant shown in Figure 4.47, a combination with a typical miniplant set-up, exhibits greater complexity than the miniplant but it nevertheless consumes a much smaller proportion of the volume of the plant set-up. 

Figure 4.47 Combination of a miniplant with a micro structured reactor plant. The micro structured reactor plant is shown with a dashed box) [86].

Before scale-up in micro structured reactor plants is discussed, a short introduction to problems which occur during scale-up from a miniplant to a production plant will be given. Experimental correlations found in a miniplant will have to be transferred to the geometric scale of a production plant. Some scale-up factors which have been tested successfully for a number of devices are given in Table 4.10 [16, 137-139],... 

Table 4.10 Factors for safe scale-up of the mass flow from a miniplant to a production plant [137].

Robbins, L. A., Pilot plant operations -the miniplant concept, Chem. Eng. Progr. 1979, 45-48. 

Dienes can also read with the Cj building block C02. In the 1970s, the catalyzed telomerization of C02 with 1,3-butadiene was reported by Inoue and co-workers, which yields, in the presence of catalytic amounts of palladium and phosphine ligands, a 6-ladone with up to 90% seledivity (Equation 3.5) [75], Behr s group scaled up this reaction from the laboratory to the miniplant scale and it could be carried out in a full-scale plant in the near future [76-80]. 

Supercritical fluid extraction (SFE) is a separation technique that uses sc-fluids as separating solvents. Supercritical fluids can replace other solvents in many purification procedures, even in countercurrent extraction. In synthetic chemistry, SFE can be an alternative to conventional methods for purification/isolation of complex products, for example pharmaceuticals, nutraceuticals and vitamins [12, 18j. Since SFE is still quite a young discipline, physical properties and basic parameters for many interesting compounds and mixtures are not yet known (in contrast to classical methods like distillations). Therefore, it must be pointed out that for all applications of sc-fluids the phase equilibria have to be determined properly. Unfortunately, for many technical or industrial applications of procedures based on supercritical fluids, the basic parameters are often not yet known. For industrial implementation, scale-up, miniplant, or pilot plant activities, it is absolutely necessary to have information about phase behaviour, solubility, energy balances and... 

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