Automated retrofit targeting of heat exchanger networks

Yang

et al. 2020

Ind. Eng. Chem. Res.

The process of synthesizing syngas with the triple CO2 feeds is proposed to achieve an efficient use of CO2 that mitigates climate warming. Also, the amount of CO2 added in three locations as the variables of the process is optimized based on the CO2 conversion rate and the energy consumption per unit product (ECP) output flow rate by the genetic algorithm. The performances of the triple CO2 feeds in the methanol synthesis process had been evaluated by comparing with the traditional methanol production processes. To further reduce energy consumption, the irreversibility of each component and the locations of the inefficiency in the overall selected production process are studied on the basis of the exergy analysis. Pinch analysis is further used to find the optimal matching scheme. Compared with those of the proposed process, the energy consumption and the total exergy loss of the heat-integrated process are significantly reduced by 33.1 and 6.65%, respectively. Besides, the overall total annual cost is reduced by 10.1% and the cost of utilities is saved by 36.4%, which results in energy-saving.

Section: Energy Utilizationmentioning

confidence: 99%

Optimal Design and Energy-Saving Investigation of the Triple CO₂ Feeds for Methanol Production System by Combining Steam and Dry Methane Reforming

Yang

et al. 2020

Ind. Eng. Chem. Res.

“…It is derived by balancing heat deficit and surplus within the shifted temperature intervals of each HEX in the HEN. Walmsley automated the BA [33] to find the cost-optimal retrofit design under consideration of constraints using the branch-and-bound approach.…”

Section: Retrofit Approachesmentioning

confidence: 99%

“…In the HSDT, positive ∆Ḣ i,i+1 values refer to heat surpluses while negative ∆Ḣ i,i+1 values refer to heat deficits. In contrast to the work of Lal [32] and Walmsley [31,33], in this version the Pinch temperature on the one hand and the possible shifting range of the individual streams on the other hand are highlighted in colour (cf. Figure 6).…”

Section: Construction Of the Heat Surplus And Deficit Tablementioning

confidence: 99%

Heat Pump Bridge Analysis Using the Modified Energy Transfer Diagram

et al. 2020

Self Cite

Heat pumps are the key technology to decarbonise thermal processes by upgrading industrial surplus heat using renewable electricity. Existing insight-based integration methods refer to the idealised Grand Composite Curve requiring the full exploitation of heat recovery potential but leave the question of how to deal with technical or economic limitations unanswered. In this work, a novel Heat Pump Bridge Analysis (HPBA) is introduced for practically targeting technical and economic heat pump potential by applying Coefficient of Performance curves into the Modified Energy Transfer Diagram (METD). Removing cross-Pinch violations and operating heat exchangers at minimum approach temperatures by combined application of Bridge Analysis increases the heat recovery rate and reduce the temperature lift to be pumped at the same time. The insight-based METD allows the individual matching of heat surpluses and deficits of individual streams with the capabilities and performance of different market-available heat pump concepts. For an illustrative example, the presented modifications based on HPBA increase the economically viable share of the technical heat pump potential from 61% to 79%.

“…Goodarzvand-Chegini et al [14] instead investigated retrofitting opportunities in the hydrocracking process, which is of special interest due to high pressure levels, which impose challenging constraints on operation and plant equipment. Walmsley et al [15] recently suggested a promising approach for automated energy targeting in retrofit situations, and applied it to a large-scale refinery case study. However, in all studies cited above, only direct process heat exchange was considered.…”

Section: Introductionmentioning

confidence: 99%

Studying the Role of System Aggregation in Energy Targeting: A Case Study of a Swedish Oil Refinery

et al. 2020

The definition of appropriate energy targets for large industrial processes is a difficult task since operability, safety and plant layout aspects represent important limitations to direct process integration. The role of heat exchange limitations in the definition of appropriate energy targets for large process sites was studied in this work. A computational framework was used which allows to estimate the optimal distribution of process stream heat loads in different subsystems and to select and size a site wide utility system. A complex Swedish refinery site is used as a case study. Various system aggregations, representing different patterns of heat exchange limitations between process units and utility configurations were explored to identify trade-offs and bottlenecks for energy saving opportunities. The results show that in spite of the aforementioned limitations direct heat integration still plays a significant role for the refinery energy efficiency. For example, the targeted hot utility demand is reduced by 50–65% by allowing process-to-process heat exchange within process units even when a steam utility system is available for indirect heat recovery. Furthermore, it was found that direct process heat integration is motivated primarily at process unit level, since the heat savings that can be achieved by allowing direct heat recovery between adjacent process units (25–42%) are in the same range as those that can be obtained by combining unit process-to-process integration with site-wide indirect heat recovery via the steam system (27–42%).