Thermal Cracking of Ethane and Ethane-Propane Mixtures

Abstract

The first part of this paper concerns the thermal cracking of ethane in a pilot plant, under conditions representative for industrial operation, and the second part deals with the cracking of mixtures of ethane and propane. The rate of cracking of ethane is found to be decreased by the addition of propane, while the rate of propane cracking is slightly increased by the presence of ethane. Correlations are given for the rate coefficients of ethane and propane cracking in the mixtures. Global rate coefficients are also given. The product distribution was determined as a function of the reaction conditions and the mixture composition. The deviations from the pure additivity behavior are explained and correlated. A molecular reaction model was derived from the experiments. It permits a successful simulation of the cracking of ethane and mixtures of ethane-propane in industrial reactors.

Multivariable optimization of thermal cracking severity

“…Then, a tradeoff exists between the plant throughput and the frequency of the down times and, thus, an optimum figure should exist for ω. To this complexity, one can add the nonlinear behavior of the yields of propylene, butene, butadiene and gasoline along the reactor coil as demonstrated in Lichtenstein (1964), Chambers and Potter (1974a), Froment et al (1976), Szepesy (1980), Van Damme et al (1981), Van Camp et al (1984), Van Camp et al (1985), and Van Geem et al (2005) as a consequence of the temperature profile and the coil geometry. Then, oversimplification must be avoided in order to assure an optimal set-point collection of the three process variables employed in this research.…”

Construction of an ab initio kinetic model for industrial ethane pyrolysis

“…The process conditions and experimental yields were taken from Froment et al 2,3 and from Wauters. 39 The first set of data corresponds to an industrial ethane cracker with an ethane conversion of 59.9% and a residence time of 0.93 s. 3 The feed consists of 98.2 mol % C 2 H 6 , 1.0 mol % C 2 H 4 , and 0.8 mol % C 3 H 6 . The average heat flux was not reported by Froment et al, 3 but can be estimated from an overall energy balance.…”

“…1 Accurate kinetic models are required for the design and optimization of the steam cracking process, and models for feedstock ranging from light hydrocarbons, such as ethane and propane, [2][3][4][5][6][7][8][9] to heavier mixtures, such as naphtha 5,10,11 can be found in the literature. The accuracy of a kinetic model depends on the completeness of the reaction network and on the accuracy of its kinetic and thermodynamic parameters.…”

“…12,13 Steam cracking proceeds via a high temperature radical mechanism and in particular for heavier feedstock the reaction network can involve several hundreds of reactions. [13][14][15][16] Three types of kinetic models are commonly used to describe steam cracking: empirical models, 10 molecular reaction models, 3,5,17 and kinetic models based on elementary reactions. 4,6,7,12,14,15,18 In principle, kinetic models based on elementary reactions should be preferred since they can be used outside the domain where their parameters have been fitted.…”

“…Ethane steam cracking was selected because it is an example of a complex gas phase radical reaction for which pilot scale and industrial experimental data have been published (Table 1). 2,3,39 Moreover, compared to naphtha and vacuum gasoil cracking, the feed composition is well defined, and the size of the reaction network remains manageable. This then allows calculating all the individual kinetic and thermodynamic parameters in the model directly from first principles.…”