Waste time-based process

Following an initial resolution step with 0.5 mol equivalents (R)-mandelic acid in TBME, the crystalline product was filtered and tlie waste isomers in the mother liquors (39% ee) were washed with base and then subjected to racemization with the SCRAM catalyst. Upon completion, the catalyst precipitated and was screened, fresh racemic amine was added, and the whole was resolved a second time. The process was repeated several times, giving the results summarized in Table 13.2. 

Figure 7.4 Classification and image processing results of a typical situation in polymer waste recycling (a) digital image (b) initial classification result (c) calculation of separation data based on the initial classification result (d) classification result after real-time image processing. A, B Polyethylene terephthalate (PET) bottles with paper labels, C PE bottle with paper label, D PE bottle with PE film label, E PP cup, F PS cup. Classification colour code red high-density PE green PS dark blue PET yellow PP light blue paper.

The effect of particle size on the HCl sorption capacity of Ca-C was studied varying the particle sizes i.e. 0.25, 1.0, and 2.0 mm. The other reaction parameters such as sorbent weight (2 g), total gas flow (535 mL/min), linear gas velocity (0.18 m/s), inlet HCl concentration (1820 ppm), and temperature of adsorption (350°C) were kept constant. Figure 18.12 shows that with increase of sorbent particle size the breakthrough of HCl was found to increase from 11 h (0.25 nun) to 2 h (2 mm). The results calculated from the adsorption isotherms, such as amount of HCl adsorbed before breakthrough, observed HCl adsorption until steady state level and adsorption time until steady state are presented in Table 18.6. The adsorption capacity of Ca-C was 63% with particle size 0.25 mm. The increase of particle size from 0.25 to 2 mm decreased the theoretical consumed capacity from 63 to 11%. These studies clearly indicated that calcium-based sorbents are effective for the dechlorination of PVC mixed waste plastics pyrolysis process. 

While acetone would serve as a source of ketene in a number of locations, the acetic acid dehydration would predominate and the acetic acid based ketene process is still widely practiced at the start of the 2r century. While acetone had some attractive features, particularly the generation of an inert co-product (methane) rather than reactive water which can destroy ketene, there are some sound reasons the acetic acid process predominated. First, let s recall that during the period 1910-1920, representing the time these processes were introduced, acetone was still made from calcium acetate, so acetone was obtained, at the time, in a two step process from acetic acid. The choice of acetic acid skipped two steps and eliminated wastes. 

Mass Transfer Efficiency. The human kidney acts as a filter to remove metabolic waste products from the blood. A person s kidneys process about 200 quarts of blood daily to remove two quarts of waste and extra water, which are converted into urine and excreted. Without filtration, the waste would build to a toxic level and cause death. Patients with kidney failure may undergo dialysis, in which blood is withdrawn, cleaned, and returned to the body in a periodic, continuous, and time-consuming process that requires the patient to remain relatively stationary. Portable artificial kidneys, which the patient wears, filter the blood while the patient enjoys the freedom of mobility. Filtration systems may involve membranes with a strict pore size to separate molecules based on size or columns of particle-based adsorbents to separate molecules by chemical characteristics. Mass transfer efficiency refers to the quality and quantity of molecular transport. 

The second key element of time-based competition is to reduce cost and therefore improve productivity through the elimination of non-value-added time in processes. This means that wasted lead time and unnecessary tasks that are not actually adding any value in the customer s eyes should be identified and eliminated. Stopping unnecessary tasks and removing wasted time from those that remain lowers cost by ... 

Time-based organisations come into their own by changing the way they go about their business. They engineer their processes to eliminate unnecessary steps, and take wasted time out of those that remain. Engineering your key processes means focusing on those things the customer cares about and getting rid... 

Olefins are produced primarily by thermal cracking of a hydrocarbon feedstock which takes place at low residence time in the presence of steam in the tubes of a furnace. In the United States, natural gas Hquids derived from natural gas processing, primarily ethane [74-84-0] and propane [74-98-6] have been the dominant feedstock for olefins plants, accounting for about 50 to 70% of ethylene production. Most of the remainder has been based on cracking naphtha or gas oil hydrocarbon streams which are derived from cmde oil. Naphtha is a hydrocarbon fraction boiling between 40 and 170°C, whereas the gas oil fraction bods between about 310 and 490°C. These feedstocks, which have been used primarily by producers with refinery affiliations, account for most of the remainder of olefins production. In addition a substantial amount of propylene and a small amount of ethylene ate recovered from waste gases produced in petroleum refineries. 

By-Products. The PUREX process is efficient at separating uranium and plutonium from everything else in the spent fuel. Within the high level waste stream are a number of components which have, from time to time, been sufficiendy interesting to warrant their recovery. The decision to recover a particular isotope is usually based on a combination of market incentives and desired waste reduction. 

A typical reactor operates at 600—900°C with no catalyst and a residence time of 10—12 s. It produces a 92—93% yield of carbon tetrachloride and tetrachloroethylene, based on the chlorine input. The principal steps in the process include (/) chlorination of the hydrocarbon (2) quenching of reactor effluents 3) separation of hydrogen chloride and chlorine (4) recycling of chlorine to the reactor and (i) distillation to separate reaction products from the hydrogen chloride by-product. Advantages of this process include the use of cheap raw materials, flexibiUty of the ratios of carbon tetrachloride and tetrachloroethylene produced, and utilization of waste chlorinated residues that are used as a feedstock to the reactor. The hydrogen chloride by-product can be recycled to an oxychlorination unit (30) or sold as anhydrous or aqueous hydrogen chloride. 

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