Paper process flow sheet

Sulphuric acid is the largest volume chemical in the world with an annual production of about 180 mill, t/year which is used primarily for phosphate fertilizers, petroleum alkylation, copper ore leaching and in smaller quantities for a number of other purposes (pulp and paper, other acids, aluminium, titanium dioxide, plastics, synthetic fibres, dyestuffs, sulphonation etc.). The major sulphur sources for sulphuric acid production are sulphur recovered from hydrocarbon processing in the refineries and from desulphurisation of natural gas, SO2 from metallurgical smelter operations, spent alkylation acid, and to a minor extent mined elemental sulphur and pyrites. A simplified flow sheet of a modem double-absorption plant for sulphuric acid production from sulphur is shown in Fig. 1. 

General Atomics (GA) and the Commissariat a Ytnergie Atomique (CEA) have been working on sulphur-iodine cycle flow-sheeting for several years, leading to sometimes differing efficiency estimates. They have undertaken to understand and reconcile these differences, and have come to consider in more detail the effect of the VHTR characteristics on the optimisation of the sulphur-iodine flow sheet. This paper will present the outcome of these studies, and stress the interplay between nuclear reactor and chemical process. 

In 2006, GA participated in a study conducted by the Savannah River National Laboratory (Summers, 2006). The S-I process was coupled to a VHTR with a required helium return temperature near 600°C. To efficiently match temperature requirements with available heat, a design was developed to supply HI decomposition section energy with recovered heat from the sulphuric acid decomposition section. For the purposes of comparison and analysis in this paper, the GA flow sheets will refer to this design, and CEA flow sheets will refer to a design in which helium supplies heat to both acid decomposition sections. CEA uses ProSimPlus for flow sheet analysis, and GA uses Aspen Plus . A previous study (Buckingham, 2008) showed that the two process simulators give similar calculated results when the same unit operations and stream compositions are modelled, although different thermodynamic models are used for the calculations. 

To understand the design and function of a chemical plant it is a useful preliminary to study the flow diagram (sometimes called a flow sheet). Its purpose is to illustrate diagrammatically, on one sheet of paper, all the items of equipment required for a chemical process or series of processes to be operated. Items are represented by simple symbols which are usually those recommended by the British Standard 974 1953 and subsequent editions (your supervisor may have a copy). The route of materials through the equipment is indicated by arrows and interconnecting lines and, in some instances, the materials of construction, size or capacity, flow rates, power requirements, and pipe dimensions are also shown. 

The paper by Tonkovich et al. cited above deals with methanol production, tailored to an FPSO vessel, and employing plants similar to those designed by Heatric Ltd. One of the principal differences between the plant described earlier and the methanol unit is the need to carry out distillation and compression processes, the flow sheet being shown in Figure 9.11. 

The greatest quantity of CA was used in the lamination of paper, starting around 1934 (Kimberly and Scribner, 1934). The heat-lamination process involves heating and pressing the paper between two sheets of CA so that the polymer flows into the paper. The degree of substitution, the molecular weight, the purity of the CA, the type and amount of plasticizer, the stabilizers used and the temperatures and pressures employed have been specified (Wilson and Forshee, 1959). Thin tissue was incorporated into the lamination by some... 

The natural gas processing scheme proposed by Sciamanna and Lynn (1988) was developed with the aid of the UCBSRP flow-sheet simulator (Neumann, 1986). The process flow diagram presented in this paper is rather complex for a process of this type, reflecting greater emphasis on technical optimization than on commercial feasibility. An illustration of a simplified, updated generic flow diagram for the UCBSRP selective H2S process is shown in Figure 9-50 (Lynn et al. 1991). 

Figure 7.3. In continuous deflection electrophoresis, flow down a paper sheet or between closely spaced plates carries different solutes, which are gradually separated by electrophoresis along axis x, to different collection ports. However, the flow is classified as passive because it does not enhance the separation occurring along the electrical-field axis. The role of flow is to aid continuous sample collection, not to fundamentally alter the separation process.

This brief overview describes some experiences using tangential-flow and dead-end ultrafiltration techniques for concentration of eukaryotic cells, proteins and virus. The data and conclusions presented here have been drawn from process development work employing available apparatus and should be considered preliminary, rather than definitive or exhaustive. Previous ultrafiltration systems have been described (1-14) for both bench and pilot scale separations of proteins and virus. This paper primarily summarizes work on cartridge and sheet filter systems and their application to processes requiring sterilizable and contained systems. 

In GC the gaseous mobile phase must be confined in a column, so that a pressure gradient can cause it to flow past the stationary phase and eventually elute the separated bands out the effluent end of the column. This is inherently a ID separation, along the column, from one end to the other. This dimensionality applies even should the column be coiled to fit in a GC oven rather than vertically straight, like Tswett s gravity flow liquid mobile phase column. However, unlike gases, liquids as mobile phases do not always require confinement to move in a desired direction or retain their volume. If they are in contact with porous beds of small particles or fiber mats, surface forces (capillary attraction) can often induce them to flow. Thus it is possible to carry out the LC process on a stationary phase arrayed as a thin surface layer, usually a planar, 2D surface. Examples include the matted cellulose fibers of a sheet of paper, or a thin layer of silica gel or alumina particles on a planar support (e.g., a pane of glass). 

Documentation in the hidden factory has its own production process. The raw material of paper is prepared into documents and data entry forms as production plans, master production and control records, batch records, raw material sheets. Standard Operating Procedures (SOPs) and so on, which in turn are enhanced with more and more manual data entry and signing at each step of activity with approvals. The paper flows from desk to desk as collections of related documents. There is a huge "add ingredient" or "assembly" process of data to the physical medium, which at each step of activities has to be at the right place at the right time—just as the physical products. 

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