(156b) Flareless Start-Ups -- a Possibility

Flaring is an inherent part of a start-up activity for an ethylene unit. A start-up of a typical ethylene plant requires a significant flaring of hydrocarbon. This is not just a loss of product but also causes heavy carbon emission, sooty flames & community nuisance.

An in-depth analysis of various ethylene production technologies & operating procedures of more than 10 facilities indicated beyond a doubt that modifications to the operating strategy of most of the plants results in saving of ~60% of feed material during each start-up. With the saving realized in feed utilization, other benefits like ~20% reduction in start-up time & ~70% reduction in stack emissions have been observed in actuals.

Case Study: For an ethylene producing plant (450 KTA) with 5 crackers following activities allowed reduction in the flaring quantity & start-up time: a. Analysis of the start-up & shutdown activities of the unit & equipments (compressors) b. Survey of the various flaring points c. Study of the process & technology specifics d. Detailed tech-economic feasibility of various start-up & shutdown schemes to reduce flaring e. Recommendation of cost effective modifications required for reducing the flaring during start-up of plant The implementation assistance for the recommendations that was provided to the manufacturer included: ? Calculation of the required inventories and line sizes ? HAZOP ? Preparation of SOPs ? Training of operators ? Basic/Detailed Engineering of the suggested modifications ? Part wise implementation of the procedure especially during planned/unplanned shutdowns/startups for operators to gain valuable experience

Benefits ? With some simple modifications to operations & procedures, following benefits were realized by the Ethylene producing facility: 1. 80% reduction in flare load 2. 25% reduction in start-up time 3. Reduced flaring for reduced time