Carbon residue, Conradson

The Micro-method uses an analytical instrument to measure Conradson carbon in a small automated set. The Micro-method (ASTM D4530) gives test results that are equivalent to the Conradson carbon residue test (D189). The purpose of this test is to provide some indication of relative coke forming tendency of such mat al. 

Figure 2-6. Ramsbottom Carbon Residue versus Conradson Carbon Residue. (Copyright ASTM D-524. Reprinted with permission.)...

Hydroprocessing reduces the Conradson carbon residue of heavy oils. Conradson carbon residue becomes coke in the FCC reactor. This excess coke must be burned in the regenerator, increasing regenerator air requirements. 

Within the field of catalytic cracking, the phrase residue is commonly used for a number of different hydrocarbon fractions. Heavy vacuum gas oils with a high-Conradson carbon residue (CCR) is sometimes called a residue even though... 

The third type is the additional coke related with the feedstock quality. FCC feedstock contains a dissolved carbon, polynuclear aromatic compounds, called Conradson carbon residue (CCR ASTM D-189). It is deposited over the catalyst surface during cracking reactions. In the FCC unit, this material is part of the coke remaining in the catalyst. Some researchers have investigated cracking of heavy feedstock and observed that, in particular cases, the amount of Conradson carbon is linearly related with the carbon-hydrogen ratio of the feedstock [3]. 

ASTM D-189. Standard Test Method for Conradson Carbon Residue of Petroleum Products. 

Although there is no exact correlation between the two methods it is possible to interconnect the data (ASTM, 1995), but caution is advised when using that portion of the curve below 0.1% w/w Conradson carbon residue. 

Coking processes have the virtue of eliminating the residue fraction of the feed, at the cost of forming a solid carbonaceous product. The yield of coke in a given coking process tends to be proportional to the carbon residue content of the feed (measured as the Conradson carbon residue see Chapter 2). The data (Table 7-11) illustrate how the yield of coke from delayed and fluid coking varies with Conradson carbon residue of the feed. 

Thermal coke the carbonaceous residue formed as a result of a noncatalytic thermal process the Conradson carbon residue the Ramsbottom carbon residue. 

These have allowed processing of residues containing up to 9.9% Conradson Carbon Residue (CCR). 

Table IV gives the properties of the SRC-II fuel oil compared to a low-sulfur residual oil utilized in a recent combustion test. The SRC-II fuel oil is a distillate product with a nominal boiling range of 350-900°F, a viscosity of 40 Saybolt seconds at 100°F and a pour point below -20°F. Thus, it is readily pumpable at all temperatures normally encountered in transportation of the fuel oil. The fuel oil has a very low content of ash and sediment as well as a low Conradson carbon residue. These characteristics are favorable from the standpoint of particulate emissions during combustion. Tests of compatibility with typical petroleum fuel oils and on stability of the coal distillates over time have not revealed any unusual characteristics that would preclude utilization of these coal-derived fuels in conventional boiler applications.

Figure 7 summarizes the main relations, which determine the effect of coke on deactivation. Note that a poor coke selectivity (or low cat-to-oil ratio) will aggravate the poisoning effect of the fraction of the Conradson Carbon Residue which is converted to coke. 

While originally designed for cracking the overhead stream from vacuum distillation units, known as vacuum gas oil (4), most FCC units currently operate with some higher boiling vacuum distillation bottoms (Resid) in the feed. Table 5.1 illustrates the difficult challenges faced by refiners, process licensors and FCC catalysts producers the resid feeds are heavier (lower API gravity), contain many more metals like Ni and V as well as more polyaromatic hydrocarbons prone to form coke on the catalysts (Conradson Carbon Residue, or CCR). 

The test conditions for this Microscale Simulation Test (MST) correspond to the low vapor contact times as applied in today s FCC riser technology. An effective feed preheat and feed dispersion is ensured, while the isothermal reactor bed is set to the dominating kinetic temperature in the riser, being approximately the feed catalyst mix temperature. The MST conditions enable the testing of high Conradson Carbon residue feedstocks. 

Elemental Analysis and Physical Properties. Elemental analysis was accomplished by conventional microanalytical techniques in a commercial testing laboratory. Density, refractive index, average molecular weight (VPO), Conradson carbon residue, and ash content were determined by standard methods. Viscosity was determined by a cone-plate viscometer. Simulated distillation was accomplished using a y4" x 18" column of Anachrome Q, 3% Dexil 300, programmed from -30 to... 

In resid cracking the high feed metals and Conradson Carbon Residue (CCR) require careful consideration when assessing both catalyst design and performance evaluation. This paper addresses the issues of the latter with respect to coke, delta coke and catalyst deactivation. 

Since the early 80 s the number of FCCU s processing resids has increased dramatically. New units are being built, designed for processing 100% atmospheric resid with a conradson carbon residue content up to 10%. Many units... 

Abbreviations FAME Fatty Acid Methyi Ester, VOME Vegetabie Oii Methyi Ester, CFPP Coid Fiiter Piugging Point, OCR Conradson Carbon Residue. 

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