Total demineralization

Removing traces of Ca and S1O2 brought in by recycling seldom entails mixing the condensates with the make up water at the inlet of a series of ion exchangers. In fact the SiOj input by the treatment is very diluted by massive return of unpolluted untreated condensates and by make up water. To check this out, a Si02 balance must be set up. 

Spent caustic is a highly specific effluent. TTte small volumes (0.1 to 8 m -h ) discharged vary according to a refinery s size and layout and to the sulfur content of the crude being processed. However, the harmful effects are considerable due to the concentration in and in phenols. 

In the CONCAWE report of 5 May, 1989, production of spent caustic by 45 European refineries represents about 138,000 t y compared to an overall 252 Mt of crude refined. This should give 550 t of spent caustic for every 1 Mt of crude. 

Depending on a refinery s degree of complexity, average hourly spent caustic discharge can be extremely different  

10 refinery with the above plus SC or lube oil plant. 1.25 t-y  

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For purer water quality, the water may be totally demineralized by mixed beds of polymeric resins which exchange in turn hydrogen ions for all cations and hydroxyl ions for all anions, effectively producing pure HjO from a raw water stream. Such highly purified waters are required for boilers operating from about 6 MPa and for all nuclear boilers (to avoid radioactive half-life of water-borne salts). 

Dissolved Solids None Dissolved solids is measure of total amount of dissolved matter, determined by evaporation high concentrations of dissolved solids are objectionable because of process interference and as a cause of foaming in boilers Various softening processes, such as lime softening and cation exchange by hydrogen zeolite, will reduce dissolved, solids demineralization distillation reverse osmosis electrodialysis... 

Maximumtotal alkalinity consistentwith acceptable steam purity. If necessary, the limitation on total alkalinity should override conductance as the control parameter. If make-up is demineralized waterat 600-1000 Ib/in g, boiler wateralkalinity and conductance should be shown in the table for the 1001 -1500 Ib/in g range. NS (not specified) in these cases refers to free sodium- or potassium-hydroxide alkalinity. Some small variable amount of total alkalinity will be present, and measurable with the assumed congruent control or volatile treatment employed at these high-pressure ranges. 

For higher-pressure boilers demineralization is necessary to minimize total dissolved solids in the boiler. This water is normally carried in steel pipework, but if condensate is returned and the condensate has become contaminated (for example, with carbon dioxide or copper ions) more corrosion-resistant materials such as copper are required. Downstream of the boiler, steam pipework is usually steel with steel or stainless steel expansion bellows. 

The ED process is a reliable, membrane-based, electrically driven demineralization technology that is more than 50 years old. It is suitable for the production of basic pure water from lower TDS supply sources. Commercial ED units consist of hundreds of individual cells in a modular membrane sandwich arrangement, bounded by electrodes and linked to a direct current (DC) rectifier-controller. The total treated water flow is a function of the number of cells in the ED unit. 

ASME recommends that the maximum total alkalinity should be consistent with acceptable steam purity. If necessary, operators should override conductance as a BD control parameter. If MU is demineralized quality water and the boiler operates at less than 1,000... 

Since the scatter of experimental points for total conversion is both above and below the curve for the demineralized sample, it is not possible to assign the behaviour of the untreated coal to either catalyst blinding or enhanced catalytic effects. With regard to the yield of bitumen (Fig. 8), the bias on the high side in yield could be interpreted to suggest that some catalytic... 

The samples and the CSF pool (quality control) are thawed and placed on ice water. Apply a CSF pool at the beginning of a batch as well as at the end of a batch of samples. Add 1 ml of sample for free GABA//3-alanine and, if necessary, add demineralized water to obtain a final volume of 1 ml. Add 50 pi of sample for the determination of total GABA//3-alanine and add demineralized water to obtain a total volume of 400 pi. 

Citrate/phosphate-buffer 1.78 g Na2HP04-2H20 (Merck) is dissolved in 50 ml demineralized water and the pH is adjusted to 5.0 with citrate solution. Subsequently, demineralized water is added until a total volume of 100 ml is obtained. 

Reaction buffer 1.15 ml acetic acid (99.7% Sigma) and 758.68 mg PbAc2-3H20 (Aldrich) are dissolved in 60 ml demineralized water and 250 pi Triton X-100 (Merck) is added. The pH is adjusted to pH 5.6 using a 10 M NaOH solution. Demineralized water is added up to a total volume of 100 ml. The reaction buffer is stored at -20°C. 

For each patient sample, 10 and 20 pi of leukocyte homogenate are transferred to individual wells on the microtiter plate. Subsequently, 100 pi substrate buffer are added and the volume is adjusted to a total of 200 pi by adding demineralized water. The plate is briefly shaken, sealed with tape and covered with aluminum wrapping. Incubation is carried out at 37°C for 45 min. The reaction is stopped with 200 pi stop solution and the fluorescence is read with an excitation wavelength of 365 nm and an emission wavelength of 450 nm. 

A plethora of lactase-treated products are described in the literature (Zadow 1984 Holsinger 1978). The use of hydrolyzed lactose syrups has been proposed as an alternative sweetener to corn syrup solids. Storage of syrups as concentrated liquids can be a problem due to microorganism growth or to extensive precipitation of residual lactose or galactose. Generally, both problems can be controlled by storage at -10 to -20°C if syrup total solids were around 70%. Guy (1979) has reported on the sweetness of hydrolyzed, demineralized syrups. 

In any plant distilling sea water directly to obtain a demineralized water, the ratios of pounds of water distilled per pound of product, and pounds of total material distilled per pound of product, are identical and are equal to unity. Therefore, if a competing process has a distillation ratio greater than unity, it is clearly uneconomical when compared to direct distillation. Table V shows either a three-stage or four-stage plant to fall in this category the ion exchange process, as visualized, involves more distillation than does direct distillation. 

For electrical demineralization, the amount of electric current, the membrane area required, and the costs of the process depend on the amount of salt removed. The electric membrane process is currently most attractive for treatment of so-called brackish waters containing from 1000 to 10,000 p.p.m. of total dissolved solids. 

X 40 inch Nepton 4-ounce membranes for a total of 2750 sq. feet of membrane area. It has a hydraulic capacity of 175 gallons per minute or 250,000 gallons per day and will demineralize a predominantly chloride water at 70° F. by 46%. 

Various bituminous coals were demineralized by an experimental two-step leaching process in which the ball-milled coals were first treated with a hot alkaline solution and then with a dilute mineral acid. Different alkalis and acids were studied to determine their relative effectiveness. In addition, the effects of alkali concentration, treatment temperature, and treatment time were evaluated. Under the best conditions, the process reduced the ash content of the coals by 85-90% and the total sulfur content by 70-90%. As the temperature of the alkaline treatment was raised from 150 to 345 C, the removal of sulfur increased greatly whereas the recovery of organic matter declined. When a 1 M sodium carbonate solution was employed for the treatment, the recovery of organic matter was 91-97% for various coals treated at 250 C and 79-89% for the same coals treated at 300 C. 

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