Washing operations

The use of ether may be avoided by mixing the ester, after its isolation from the water layer, with about 20 ml. of carbon tetrachloride. The carbon tetrachloride solution then forms the lower layer in all washing operations (compare Methyl Benzoate, Section IV,176). 

Acryflc acid, alcohol, and the catalyst, eg, sulfuric acid, together with the recycle streams are fed to the glass-lined ester reactor fitted with an external reboiler and a distillation column. Acrylate ester, excess alcohol, and water of esterification are taken overhead from the distillation column. The process is operated to give only traces of acryflc acid in the distillate. The bulk of the organic distillate is sent to the wash column for removal of alcohol and acryflc acid a portion is returned to the top of the distillation column. If required, some base may be added during the washing operation to remove traces of acryflc acid. 

The trays may be fitted with rims this is particularly useful for flooding the trays in washing operations. Scavenger leaves are often used. FUtration areas up to 50 m are avaUable. Like aU horizontal leaf filters, horizontal vessel, horizontal leaf filters are particularly suitable when thorough washing is needed. 

Desalting is a water-washing operation performed at the production field and at the refinery site for additional cmde oil cleanup. If the petroleum from the separators contains water and dirt, water washing can remove much of the water-soluble minerals and entrained soflds. If these cmde oil contaminants are not removed, they can cause operating problems duting refinery processiag, such as equipment plugging and corrosion as well as catalyst deactivation. 

Following calcination, the product may require milling to reduce particle size to that necessary for use. This size reduction may be carried out either wet or dry. If there are soluble by-products, a washing operation may also be required. It is almost always necessary to break up agglomerates by a process such as micronizing. 

Cake Washing Wash efficiency data are most conveniently represented by a semilog plot of percent remaining B as a function of wash ratio N as shown in Fig. 18-103. Percent remaining refers to that portion of the solute in the dewatered but unwashed cake which is left in the washed and dewatered cake. Since a cake-washing operation... 

The presence of hydrogen chloride during the hydrogenation of many organic compounds is desirable or without effect, so that the washing operations may be omitted in such cases. Thus, the palladium chloride on carbon may be used in the same manner as the prereduced catalysts, i.e., simply added before reduction to the solvent and the hydrogen acceptor. 

Intensive soluble recovery or removal of contaminants from the cake as accomplished by countercurrent washing operations. This is especially the case with horizontal belt, tilting pan and table filters, which are described later in this subseetion,... 

Orifice Mixing Column An orifice mixing column consists of a series of orifice plates contained in a pipe. The pipe normally is fabricated of two vertical legs connected by a return bend at the bottom with the orifice plates installed between flanges in the vertical legs. Typical use is for cocurrent contacting in caustic and water washing operations. 

Acid used in the formation process is removed from the batteries and reused. The batteries are washed, fresh acid is added, and the batteries are tested, re-washed, and inspected before being shipped to an on-site warehouse. The intermediate and final washes generate process wastewater, as do the battery repair and housekeeping (floor washing) operations. This wastewater Is pretreated on-site and then piped to the local publicly owned treatment works (POTW). 

Textile products are particularly sensitive to iron, which discolors the product. Many washing operations, as in metal finishing, require softened water to avoid staining... 

All manufacturing industries produce peculiar wastes from their production processes. The bulk of the wastes is conveyed to the wash waters that end up as wastewaters. The washing operations include washing of raw materials, the intermediate and final products, the plant (before and after production batch), and unsolicited rain storm that washes the exposed plant parts. 

Introducing a local recycle around a scrubber or washing operation. 

If the occluded hydrochloric acid and aluminum salts are effectively removed during the washing operation, this product can be dried in a steam oven without discoloration. 

To illustrate the application of the proposed algorithm the agrochemicals problem already presented in Chapter 4 of this textbook is revisited. It involves a completely batch operation wherein reusable water is generated from liquid-liquid extraction (product washing) operations with water as the aqueous phase in the production of three agrochemicals A, B and D. The data for the production of these products are shown in Table 5.1. These agrochemicals are produced in batch reactors. All three reactions form sodium chloride (NaCl) as a byproduct which is later removed from... 

In the presence of wastewater minimization, the sequence constraints initially presented in Chapter 2 are modified as follows. The following constraints stipulates that the task corresponding to state s n. can only commence once all the previous tasks and their corresponding washing operations are complete. 

In order to illustrate the capability of the proposed technique, this multipurpose example has been enhanced by including compulsory washing operations after each of the reactions in each of the 2 reactors. The philosophy is that the reactors need to be cleaned after each reaction in order to remove contaminants that are formed as byproducts, so as to ensure product integrity. Data pertaining to cleaning tasks is shown in Table 6.6. The variation in performance in the 2 reactors could be ascribed to differences in design, which is indeed a common encounter in practice. In addition to this data, it is known that freshwater cost is 2 cost units per kg of water whilst the effluent treatment cost is 3 cost units per kg. 

Figure 12.11 represents targeting in interval (0.25-0.51 kg salt/kg water). This interval, as shown in Fig. 12.8, has the B and the C reactions with an overall water demand of 560 kg. Since both these reactions start before the completion of the washing operation of product A, no reusable water is available in the reaction time subintervals. This implies that fresh water will have to be used. The accumulated fresh water demand is, therefore, 1560 kg. As this is the last concentration interval, this quantity presents itself as the target for the optimal design. This is equivalent to a 34% reduction in freshwater demand compared to the base case. 

Many evaluations have led to the commercial utilization of PEN, its copolyesters and blends in some commercial applications. The cost effectiveness is especially apparent in retumable-refillable applications, which take advantage of PEN s chemical resistance in commercial washing operations, so ensuring an increased number of re-fill trips [26], Other applications benefit from PEN s increased gaseous barrier, UV absorption, thinner and lower weight potential. Considerable effort is underway to enable utilization of PEN, its copolyesters and blends for beer, higher hot-fill and heat-pasteurizable containers [27],... 

The processes that have been developed to accomplish gas purification vary from a simple once-through wash operation to complex multistep recycling systems. In many cases, the process complexities arise because of the need for recovery of the materials used to remove the contaminants or even recovery of the contaminants in the original, or altered, form (Kohl and Riesenfeld, 1979 Speight, 1993, and references cited therein). 

Absorption. In theory, the penetration of one substance into another. In refining and petrochemicals processing, separation of gases by a scrubbing or washing operation with a liquid. Preferential solubility is shown for one or more of the components in the gas mixture allowing a separation... 

---