Semi-mechanistic Model Applied to the Search for Economically Optimal Conditions and Blending of Gasoline Feedstock for Steam-cracking Process

Abstract

Abstract. Steam-cracking is energetically intensive large-scaled process which transforms a wide range of hydrocarbons feedstock to petrochemical products. The dependence of products yields on feedstock composition and reaction conditions has been successfully described by mathematical models which are very useful tools for the optimization of cracker operation. Remaining problem is to formulate objective function for such an optimization. Quantitative criterion based on the process economy is proposed in this paper. Previously developed and verified industrial steam-cracking semi-mechanistic model is utilized as supporting tool for economic evaluation of selected gasoline feedstock. Economic criterion is established as the difference between value of products obtained by cracking of studied feedstock under given conditions and the value of products obtained by cracking of reference feedstock under reference conditions. As an example of method utilization, optimal reaction conditions were searched for each of selected feedstock. Potential benefit of individual cracking and cracking of grouped feedstocks in the contrast to cracking under the middle of optimums is evaluated and also compared to cracking under usual conditions.

Experimental Evaluation of Hydrotreated Vegetable Oils as Novel Feedstocks for Steam-Cracking Process

“…A precise economic analysis should be performed to evaluate the most profitable scenario for the current situation in the merchant products market. There are already established methods available [25] for this kind of evaluation, demonstrated in the example of light/heavy naphtha cracking [18]. It uses total economic value of products produced per one ton of investigated feedstock in relation to the products value obtained from a ton of referential (well known) feedstock, which forms referential economic value.…”

“…However, such an analysis must consider current or predicted prices of products. We used the same method for the evaluation as in the previous paper [25], and products prices valid for 06/2017 in the central Europe to demonstrate the impact of HVOs to the process economy. Based on experimental results from lab-pyrolysis in the Table 4, and considering the HCVD as referential feedstock, pure HRSO1 provided strongly positive value 98 EUR/t.…”

Fischer‐Tropsch Wax from Renewable Resources as an Excellent Feedstock for the Steam‐Cracking Process

“…An approximate comparison of the economic potential for the considered materials can be performed using the cracking value (CV) indicator introduced by Karaba et al [32]. The CV represents the sum of market prices of all products obtained per one ton of examined feedstock relative to that sum calculated for the standard primary naphtha as the reference feedstock.…”

“…The CV represents the sum of market prices of all products obtained per one ton of examined feedstock relative to that sum calculated for the standard primary naphtha as the reference feedstock. Using the same method and prices (valid for May 2012) as in the study [32], the cracking values were evaluated as follows: naphtha 0 EUR/t (referential point), HCVD 33.0 EUR/t, FT crude 144.6 EUR/t, FT lights 131.2 EUR/t, FT middle distillate 174.6 EUR/t, and FT vacuum residue 166.4 EUR/t. This allows quantitative comparison of these materials considered as a feedstock for the steam-cracking process.…”

“…Also, several landmarks for the comparison to other feedstocks are presented in this paragraph. For example, this feedstock under standard pyrolysis conditions displays a severity (computed as propylene/ethylene yield ratio) of 0.5, which is somewhere between n-heptane (provides conversion 87.5 %, severity 0.35) [32] and light and heavy naphtha fractions (severity in the range of 0.7-0.8) [29] under the same reaction conditions using the same experimental equipment.…”