Fiber materials feeding

Membranes have been used for affinity chromatography in various formats, such as stacked sheets, in rolled geometries, or as hollow fibers. Materials that are commonly used for these membranes are cellulose, polysulfone, and polyamide. Because of their lack of diffusion pores, the surface area in these materials is as low as it is in nonporous beads. However, the flat geometry and shallow bed depth of membranes keep the pressure drop across them to a minimum degree. This means that high flow rates can be used, which makes these membranes especially well-suited for capturing proteins from dilute feed streams. 

Biotechnology research is seeking to develop new foods, feeds, fiber, and biomass energy production processes that are environmentally safe. Researchers are developing new uses for agricultural products to replace non-renewable sources of raw materials. Their work promises to have broad commercial applications and has already led to the creation of new industries. These discoveries have led to environmentally compatible commercial products such as biodegradable plastics (60), soybean oil printing inks, and super absorbent polymers (67). 

In all plant materials, the major component will be the cellular lignocellulosic material. Several possible uses for this material exist. Some of the more attractive are cattle feed fiber for pulp, paper, and board chemical feedstock or energy (8,1 1,22). Detailed evaluation of the cellular portion should provide bases for suggesting their most appropriate uses. 

Agronomic crops can be broken down into categories in a number of different ways, such as plant type or climate in which the crop is most likely to be found. One of the most common ways in which field crops are grouped is by the end use of the raw material. Nearly all crops in the world can be considered a form of food, animal feed, fiber, energy, or tools for environmental preservation. Some major crops such as com can be classified in multiple ways, as corn is used for feeding both people and animals and is also refined into ethanol. 

The first applications employed symmetric microporous hollow fibers in which the fiber materials were hydrophobic or hydrophilic. The membrane liquid may or may not wet the pores spontaneously. To separate a gas mixture in a permeator employing symmetric hydrophobic microporous fibers with gas-filled pores and nonwetting aqueous liquid membranes (Figure 2a), the liquid membrane pressure (PjJ is maintained higher than those of the feed gas (Ppo) and the sweep gas (Psg) to prevent their dispersion in the membrane liquid (4), However, the excess pressure of the liquid membrane over that of either gas stream must be less than the breakthrough pressure for the membrane liquid (which is a function of the membrane material, pore size, and the interfacial tension between the pore fluid (here, gas) and the membrane liquid). For other fibers and configurations. Figures 2b and 2c provide appropriate details. 

Essentially all the ammonium sulfate fertilizer used in the United States is by-product material. By-product from the acid scmbbing of coke oven gas is one source. A larger source is as by-product ammonium sulfate solution from the production of caprolactam (qv) and acrylonitrile, (qv) which are synthetic fiber intermediates. A third but lesser source is from the ammoniation of spent sulfuric acid from other processes. In the recovery of by-product crystals from each of these sources, the crystallization usually is carried out in steam-heated sa turator—crystallizers. Characteristically, crystallizer product is of a particle size about 90% finer than 16 mesh (ca 1 mm dia), which is too small for satisfactory dry blending with granular fertilizer materials. Crystals of this size are suitable, however, as a feed material to mixed fertilizer granulation plants, and this is the main fertilizer outlet for by-product ammonium sulfate. 

It is possible to add modifiers or delustrants at the dissolving stage. However, modem viscose dope plants feed several spinning machines which are often expected to make different grades of fiber. It is therefore now more common to add the materials needed to make special fibers by injection close to the spinning machines. 

The main by-products from the malting industry are malt sprouts, cleanout material, and small-kernel barley. Malt sprouts are primarily dried malt rootiets, containing 24—26% protein, 2—3% fat, and 12—14% fiber. Since the protein is readily available, malt sprouts are used in various animal feed blends. Occasionally, malt hulls and barley chaff are blended with malt sprouts. The remainder of the cleanout material and small kernel barley is sold as feed. 

A third factor is the ease with which various membrane materials can be fabricated into a particular module design. Almost ah membranes can be formed into plate-and-frame, spiral, and tubular modules, but many membrane materials caimot be fabricated into hollow-fine fibers or capihary fibers. Finahy, the suitabiHty of the module design for high pressure operation and the relative magnitude of pressure drops on the feed and permeate sides of the membrane can sometimes be important considerations. 

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