Coking procedure

Pyridine and its homologues are produced in coking procedures and present in the non-condensable gases. Pyridine is also present in coal-tar and as a component in creosote (Agency for Toxic Substances Disease Registry, 1992 Dutch Ministry of Social Affairs and Employment, 1993). 

Ash. The ash was determined by ASTM D3174 using the coke procedure (950°C). 

An other approach to solve the problem of cracks is to repair them after they have formed. This can be done namely by a selective coking procedure [121], However in most cases, the increased membrane selectivity is coupled with a substantial decrease of the membrane flux. 

For experiments involving metal-containing substrates, samples of the Durabead silica-alumina were impregnated with the nitrate salts of copper, iron, or nickel, or with vanadyl sulfate, at a level of 5 wt % metal, and then calcined in air for 10 hrs at 1000°F. The resulting metal oxide-containing materials were then subjected to the coking procedure described below without further treatment. 

In the quenching experiments, the usual coking procedure was initially followed. However, after the required amount of feed was pumped into the drum, the experiment was stopped by quickly removing the drum from the furnace and immersing it in a mixture of ice and water. The quenched contents were carefully removed from the drum, inspected and sectioned. Each section was then extracted in a Soxhlet extractor with toluene, until the toluene extract became colorless. 

Proof of the existence of benzene in the light oil derived from coal tar (8) first estabHshed coal tar and coal as chemical raw materials (see Eeedstocks, COAL chemicals). Soon thereafter the separation of coal-tar light oil into substantially pure fractions produced a number of the aromatic components now known to be present in significant quantities in petroleum-derived Hquid fuels. Indeed, these separation procedures were for the recovery of benzene—toluene—xylene (BTX) and related substances, ie, benzol or motor benzol, from coke-oven operations (8) (see BTX processing). 

Regeneration of noble metal catalysts to remove coke deposits can successfully restore the activity, selectivity, and stabiUty performance of the original fresh catalyst (6—17). The basic steps of regeneration are carbon bum, oxidation, and reduction. Controlling each step of the regeneration procedure is important if permanent catalyst damage is to be avoided. 

Laboratory procedures for proximate and ultimate analyses are given in the Annual Book of ASTM Standards (Sec. 5, American Society for Testing and Materials, Conshohocken, Pa., 1994) and in Methods of Analyzing and Testing Coal and Coke (U.S. Bureau of Mines Bulletin 638, 1967). 

It has been demonstrated that a solvent-extraction procedure with N-methyl pyrrolidone is capable of producing coal-derived extract pitches with low-ash contents. Moreover, the properties of the pitches can be varied by partial hydrogenation of the coal prior to extraction. The yield of the pitches along with the physical and chemical properties of the cokes and graphites vai in an understandable fashion. 

The Conradson test (ASTM D-189) measures carbon residue by evaporative and destructive distillation. The sample is placed in a preweighed sample dish. The sample is heated, using a gas burner, until vapor ceases to burn and no blue smoke is observed. After cooling, the sample dish is reweighed to calculate the percent carbon residue. The test, though popular, is not a good measure of the cokeforming tendency of FCC feed because it indicates thermal, rather than catalytic, coke. In addition, the test is labor intensive and is usually not reproducible, and the procedure tends to be subjective. 

For example, a catalyst with a MAT number of 70 vol% and a 3.0 wt% coke yield will have a dynamic activity of 0.78. However, another catalyst with a MAT conversion of 68 vol% and 2.5 wt% coke yield will have a dynamic activity of 0.85. This could indicate that in a commercial unit the 68 MAT catalyst could outperform the 70 MAT catalyst, due to its higher dynamic activity. Some catalyst vendors ha% c begun reporting dynamic activity data as part of their E-cat inspection reports. The reported dynamic activity data can vary significantly from one test to another, mainly due to the differences in feedstock quality between MAT and actual commercial application. In addition, the coke yield, as calculated by the MAT procedure, is not very accurate and small changes in this calculation can affect the dynamic activity appreciably. 

The heat balance exercise provides a tool for in-depth analysis of the unit operation. Heat balance surveys determine catalyst circulation rate, delta coke, and heat of reaction. The procedures described in this chapter can be easily programmed into a spreadsheet program to calculate the balances on a routine basis. 

Follow proper start-up procedures. Introduce feed to the riser only when the reactor system is adequately heated up. Local cold spots cause coke to build up in the reactor cyclones, the plenum chamber, or the vapor line. 

As an example, Figure 3.1.10 illustrates the use of this procedure for elucidating the location of coke deposits on zeolite catalysts [62]. Samples of zeolites H-ZSM-5... 

Determination of caffeine in soft drinks was undertaken using the aerosol alkali flame ionization detector.24 Soft drinks studied were Coke, Diet Coke, Pepsi, Diet Pepsi, Dr. Pepper, and Mountain Dew. A sample clean-up and concentration procedure is employed followed by GC separation with alkali flame ionization detection. Results showed that Coke, Diet Coke, Pepsi, Diet Pepsi, Dr. Pepper, and Mountain Dew contained 41 2, 52 2, 43 4, 35 9, 46 6, and 60 15 mg caffeine per 355-ml serving. These values compared favorably with levels reported in the literature. 

The products of the reaction are the following /-butyl-phenyl-ether (TBPE), p-/-butyl-phenol (p-TBP), o-/-butyl-phenol (o-TBP) and 2,4-di-/-butyl-phenol (2,4-DTBP). Compounds adsorbed on the external surface were recovered in methylene chloride (CH2C12) by a soxhlet treatment for 24 hours of the deactivated zeolite sample. The content of the compounds inside the zeolite (coke) was determined after dissolution, in 40 % HF at room temperature, of the catalyst recoved after 5 min, 45 min, 5h and 7.5 h extraction by CH2C12 then followed. The composition of soluble coke was investigated by analysis GC-MS. The procedure is reported in detail elsewhere [10]. 

Aromatic amines can be determined by measuring the difference of their UVV absorption spectra, taken at identical concentrations but different pH of the solution. Also, standard mixtures and samples of the amines isolated from coke processing products were tested LOD 0.1-1 ppm. The procedure is potentially useful for waste waters and industrial effluents, where techniques such as GC and nonaqueous titrations may prove difficult to apply333. A determination of certain metabolites symptomatic of pancreatitis... 

In the oldest type of plant, the coke which was used the manufacture of the water gas was in a cylinder, ich was externally heated by a coke or coal fire vever, this procedure was not very efficient, and the ctice is not in use at all at the present time. 

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