PTQ Q4 2022 Issue

10.1080/00986445.2017.1379400]. CSIR-Indian Institute of Petroleum, Dehradun, has also developed a new crude oil processing method to reduce operating costs and GHG emissions. The similar topology of the developed method of an existing CDU ensures the implementation for revamping the existing and designing the grass-root. The techno-economic study using the commercial CDU configuration showed a potential to reduce the ADC bot - tom stripping steam by 80-100% and energy cost by 11-16%. The lower vapour flow rate in the section above the flash zone and higher flow rate in the stripping sec - tion provide the opportunity to increase throughput and address the poor vapour-liquid contact problem in the strip - ping section of the ADC [Kumar, Sunil, Avinash S. Mhetre, Comparative techno-economic evaluation of potential pro- cessing schemes for petroleum crude oil distillation, Results in Engineering (2022): 100480]. A Kevin Clarke, Chief Strategy Officer, Imubit, kevin. clarke@imubit.com: It has always been the case that the simplest way to cut your energy cost is to shut down the unit – obviously not a realistic approach, so the industry has focused on cut- ting energy costs by improving the efficiency of use for many decades. Many energy management and optimisa - tion systems evolved to support this process, but one area remained very hard to define: how do you know whether that last MMSCFD of fuel gas or last lb/hr of steam you con - served cost you more in unit yield recovery? Or, if you were to spend more energy, could you gain more economic value in throughput or yield recovery? And how does that change as the cost of carbon emissions increases? Offline simulation models have been built for many years, with engineers working tirelessly to try to understand this relationship, but the optimum is continuously changing with economics, feed rates, feed quality, and ambient conditions. Today, for the first time, enabled by advances in computer capabilities and artificial intelligence, the most forward- thinking refinery operators are using leading edge, deep reinforcement machine learning models to close this yield/ energy/emissions cost trade-off in real-time, in closed-loop. A Marcello Ferrara, Chairman, ITW Technologies, mferrara@itwtechnologies.com: The CDU is the most energy-intensive process in a refin - ery (also one of the largest in the whole process industry), with its performance affecting refinery-wide efficiency. Average CDU energy consumption is estimated to be over 192 TWh/y for US refineries (DOE, 2006). Among the CDU asset, the preheat train (PHT) is the most sensitive. If work - ing improperly, it will predicate a series of chain effects: extra CO₂ emissions, reduced flow, extra furnace fuel consump - tion, drop in furnace inlet temperature (FIT), production loss, and reduced throughput to the point that the refiner will shut down the fouled unit for equipment cleaning due to unsustainable fouling conditions. Formerly, Van Nostrand et al. (1981) estimated that pro- cess side fouling cost US refineries around $1.36 billion per year and $861 million due solely to PHT fouling. Currently,

these numbers, corrected for inflation and current energy costs, are superior by at least one order of magnitude. The fouling problem is so important that its mitigation in CDU operations could lead to over 15% fuel savings. As fuel con - sumption for the atmospheric column’s furnace represents around 4% of total refinery throughput, 15% fuel savings in a 500,000 bpd facility equates to more than $347 million in savings per year. Savings are even higher when considering that the car- bon tax can reach $80 per ton or more (depending on refin - ery location). ITW has developed and patented its Online Cleaning technology, which can clean an entire production unit on a 24-hour feed-out/feed-in basis. The technol - ogy will allow refineries to recover losses in one day while reducing emissions and eliminating waste. Online Cleaning technology helps target sustainability development goals (SDGs) while also serving as a tool to improve Operational Excellence, rather than an alternative to mechanical cleaning. A Jagannadh Sripada, Consultant, KBC (A Yokogawa Company), Jagannadh.Sripada@kbc.global: Due to the high-energy consumption of crude distillation units (CDU) and vacuum distillation units (VDU), energy reduction is essential to meet emission targets and reduce energy costs in the refining industry. Three key aspects of a new design or future revamp scenario(s) are as follows: Configuration Recent developments in progressive crude distillation methodology make it a viable process to be con - sidered during the design stage to potentially save utility and perhaps better yields. However, the initial Capex could be higher for such configurations, and the sensitivity of ben - efits on the type of crude should also be kept in mind. Depending on location and pricing, refineries should eval - uate their overhead vacuum configuration. Replacing the last stage of ejectors with liquid ring vacuum pump (LRVP) has been beneficial for refineries in the past, and the con - figuration is to be carefully evaluated and selected based on steam, cooling water and, electricity prices. Heat integration Optimising heat recovery from the preheat train via a revamp could include utilising spiral and plate and frame heat exchangers at select locations, adding extra heat transfer surface area to existing heat exchangers, installing new exchangers, and more. Process integration between CDU and VDU to save fuel, periodic re-evaluation of minimum approach temperature based on energy costs, and utilisation of pinch technology to identify opportunities should be beneficial to refineries. Monitoring heat exchanger fouling, online cleaning, and an optimised cleaning schedule will minimise fuel costs and emissions. Evaluating opportunities to utilise the product heat can include providing hot feed to downstream units or using that heat to preheat the crude at CDU. Distillation column optimisation Reduce the operating pressure of the atmospheric column during winters to ben - efit from lower temperature cooling water. APC can be used to automate the minimisation of pressure to great effect.

PTQ Q4 2022