Optimal Economic Benefits Research Articles

Timing Decision for Active Remanufacturing Based on 3E Analysis of Product Life Cycle

Active remanufacturing is an important technique that is used to reduce the uncertainty of the quality of remanufactured cores. However, the implementation of active remanufacturing too early or late will lead to a reduction in economic benefits and an increase in environmental impact during the whole life cycle of the product. To this end, an active-remanufacturing-timing decision method is proposed based on an economic, energy and environmental (3E) analysis of product life cycle. In this method, the quantitative function of the cost, energy consumption and environmental emissions of used products in the manufacturing stage, service stage, and remanufacturing stage are firstly constructed based on life-cycle assessment (LCA) and life-cycle cost (LCC). Then, a multi-objective optimization method and the particle swarm algorithm are utilized to obtain active-remanufacturing timing with the optimal economic and environmental benefits of remanufacturing. Finally, a case study on remanufacturing on used engines is demonstrated to validate the proposed method.

The Role of the Public-Private Partnership (PPP) in Achieving the Optimal Economic and Social Benefits Through the Port Sector

PPP model is very essential for the success of any partnership between the public and private sector. In this review the types of the PPP models will be analysed, evaluated and proper models will be highlighted. The literature will provide sufficient information about the PPP in one of the developing countries and will also highlight on the work that has been done previously and make proper evaluation of the current situation. This paper presents a theoretical and critical review of the past studies in the PPP program, along with a revision of the outcome and conclusion. The findings of the study suggest that implementation and use of PPP has a significant economic impact on the port sector as it leads to the creation of jobs, can mobilize more financing techniques for infrastructure and multi payment options. The PPP focus more into the efficiency gains, rather than focusing on the expansion of the infrastructure which achieve the best value for money for the government and prevent overspending.

An ecological interval two-stage fuzzy shadow price model for environmental flow allocation in the Shaying River Basin

Abstract In recent years, social water is pressurizing ecological water, causing the environmental flow to not be guaranteed and destroying the ecological environment. This research aims to coordinate social and natural water use to bring about optimal economic benefits, while ensuring environmental flow requirements. In this study, an interval two-stage fuzzy shadow price model (ITS-SPM) has been developed, which combines two-stage programming (TSP) and system of water value to optimize environmental flow. The ITS-SPM is mainly characterized as system benefits constituted by expected water resource benefits and water shortage penalty. This model has removed the uncertainties of economic data and environmental water demand (expressed fuzzy and interval). It has been found that adjusting the social water structure can effectively solve the problem of insufficient ecological flow. The ITS-SPM can make the adjustment of social water use more reasonable, which will produce benefits, unlike the current agricultural water reduction policy. Under the premise of guaranteeing optimal economic benefits, the added value of environmental water use in different scenarios is (social water structure adjustment) as follows: in 2020, it was expected that Shaying River water would increase by at least 13.49%; in 2025, it is expected to increase by at least 33.35%; in 2030, the increase will be by at least 57.54%; and in 2035, it will be by at least 77.50%.

Major Chemical Compounds and Mineral Elements of Astragalus membranaceus Cultivated on the Qinghai-Tibet Plateau with Different Planting Densities.

Astragalus membranaceus is a well-known herb that is widely used in the food and pharmaceutical industries. However, its commercial development has been limited due to wild resource shortages. This study was conducted in 2018 and 2019 to assess the effect of planting density on the major chemical compounds and mineral elements and biomass yield of A. membranaceus. The biomass yield (7,700.956 kg) reached the maximum at M2 planting density in 2018. In 2019, astragaloside IV reached its maximum concentration (0.117 %) at M2 group, which was significantly different from the concentrations obtained at the other groups. Calycosin-7-O-β-D-glucoside (0.062 %) reach its maximum concentration in 2019 at M5, but not significant with M2. The concentration of major chemical compounds among the five groups in 2018 and 2019 all conformed to the Chinese Pharmacopoeia standards. In 2018, the mineral elements (Al, Ba, Fe, Li and Mn) content was higher at M2 than other groups. However, a general decrease in the mineral elements content was observed at M2 group in 2019. Enrichment analysis demonstrated that the enrichment capacity was highest for phosphorus. In conclusion, according to the TOPSIS results, M2 planting density was recommended as the optimal application. For optimal economic benefits, A. membranaceus should be harvested when it is 2 years old.

Partial substitution of chemical fertilizer by organic fertilizer benefits grain yield, water use efficiency, and economic return of summer maize

Partial substitution of chemical fertilizer with organic fertilizer (PSCFOF) is being increasingly recognized as a promising approach for achieving sustainable agriculture. However, comprehensive evaluation of the effect of PSCFOF on the grain yield, water use efficiency (WUE), and its economic return of summer maize is lacking. In this study, field experiments examining the following five treatments were conducted over the 2019 and 2020 growing season: T1, application of chemical NPK fertilizer alone; and T2–T5, substitution of 15%, 30%, 45%, and 60%, respectively, of the chemical N rate of T1 with organic fertilizer. Compared with T1, the other treatments reduced the soil bulk density, and improved soil organic carbon content and the percentage of macro-aggregates (≥0.25 mm) in the 0–20 cm soil layer. The grain yield and WUE of T2 and T3 were significantly higher than that of T1, where as T1, T4 and T5 had similar effect. The higher grain yield and WUE under T2 and T3 treatments may related to its strong root system, higher soil water content, and elevated plant N uptake, which further improved the post-silking photosynthetic capacity, biomass production, and harvest index. The results of the economic benefit analysis indicated that, T2 and T3 increased the net benefit by 2257 and 1404 CNY ha-1, respectively, compared to T1. However, the net benefit was reduced under T4 and T5 treatments. In conclusion, by comparison with T1, T2 and T3 improved the grain yield, WUE, and economic benefit of summer maize. Although T2 can achieve the optimal economic benefits in a short-term, T3 may be a better choice from the perspective of long-term ecological and economic benefits, because of its greater potential to reduce chemical N fertilizer application rate.

Policy model of regional fishery management for Indonesia’s exclusive economic zone

The abundant potential of Fishery resources within the Indonesia’s Exclusive Economic Zone (EEZ) would be very beneficial for the entire community if it is properly managed. The correct management model can provide a balanced state between optimal economic benefits and resources preservation. This study aimed at developing a fisheries management policy model in the Indonesian EEZ as an effort to create optimal and sustainable utilization. The analysis was carried out qualitatively using a case study approach within an empirical juridical point of view which resulted in a descriptive report. The management models developed prescribes several policies to be carried out, such as: 1). New vessels development; and 2). Provision of Access Regulation for both Indonesian as well as foreign fishers. The management model also requires several important prerequisites, such as: 1). Periodic reasonable sea monitoring efforts; 2). Facilitation for the national business actors in the operation and marketing of catches; and 3). Simplification of fishing permits for foreign vessels accompanied by clear and firm cooperation agreements.

Investigating a Water Resource Allocation Model by Using Interval Fuzzy Two-Stage Robust Planning for the Yinma River Basin, Jilin Province, China

This study introduces a fuzzy method to construct the interval fuzzy two-stage robust (ITSFR) water resource optimal allocation model based on the interval two-stage robust (ITSR) water resource optimal allocation model. Optimal economic benefit was considered the objective function, and the number of available water resources, sewage treatment capacity, reuse water treatment capacity, and total pollutant control were considered as the constraints. Under three five-year planning periods (2015–2020, 2020–2025, and 2025–2030) and according to the allocation levels of dry, flat, and abundant water periods (low, medium, and high discharge), the pollution absorption, upgrading projects, and water resource allocation schemes of various water sectors (industry, municipal life, ecological environment, and agricultural sector) in the Yinma River Basin were optimized. Water consumption quota is an interval value; high and low water consumption lead to a waste of water resources in the water consumption sector and restrict the development of the water consumption sector, respectively, which indicates that the water consumption quota has the characteristics of fuzzy uncertainty. Therefore, the optimization model was set as a fuzzy parameter in the solution process. The simulation results indicated that water quota can directly influence the income of water resource use, and thus, indirectly influence the economic benefit of the Yinma River Basin during the planning period. In the planning period of the Yinma River Basin, the economic benefit interval of dry, flat, and abundant water periods was reduced by 57%, 55%, and 48%, respectively, which provides a robust method with the advantages of a balanced economy, a stable system, reduced decision-making space, and significantly improved decision-making efficiency. Moreover, the emission ranges of typical pollution indicators (chemical oxygen demand (COD) and ammonia nitrogen) in the eight counties and urban areas of the Yinma River Basin were significantly reduced during the three planning periods (Dehui area had the highest overall reduction of ammonia nitrogen in the industrial sector during the second five-year planning period, up to 65%), which indicated a significant improvement in the decision-making efficiency. In addition to the Changchun City planning areas dominated by the agriculture production water sector, water resource allocation accounts for >80% of the regional water resource allocation; using the fuzzy optimization method after the Yinma River Basin water resource allocation model, the overall water deficit was significantly reduced; moreover, it was almost the same as in the first five-year period of Changchun City industry water deficit, which declined by up to 33%. The problem of resource waste caused by excessive water limiting in the water sector could be avoided because of the fuzzy water limit. To solve the prominent problem of water deficit in large- and medium-sized cities in the basin, industrial and ecological water sectors can implement measures such as water resource reuse. The total amount of water reuse in a medium year increases by up to 46% compared with that in the ITSR optimization model, which can be attributed to the reduced water consumption limit range of water consumption sectors after the fuzzy water consumption limit. This shows that more water can be allocated to meet the requirements of the water sector during decision-making. In conclusion, this study offers an effective scheme for decision makers to plan water resource allocation in the Yinma River Basin.

Hierarchical energy optimization management of active distribution network with multi-microgrid system

ABSTRACT A hierarchical energy optimization management model is established and a multi-microgrid operation strategy that mixes the battery and the power interaction designed to strengthen the system output capability. This study carries out dynamic optimization to achieve optimal economic benefits of active distribution network with multi-microgrid system. An improved sparrow search algorithm is developed to achieve an optimal energy configuration by integrating Bernoulli chaotic mapping, Lévy flight, mutation, crossover and competition. The superiority of the improved sparrow search algorithm is demonstrated by the results of different test functions and evaluation indicators. The effectiveness of the proposed method is verified by solving and analyzing the optimal configuration of energy management model. Case study results reveal that the active distribution network with multi-microgrid system has good economic and environmental benefits under various scenarios. The methods proposed are of great significance for the economic operation and environmental protection of multi-microgrid active distribution network.

Economic Assessment and Control Strategy of Combined Heat and Power Employed in Centralized Domestic Hot Water Systems

With the increasing application of CHP and an industry transition to distributed energy, it is necessary to make a comprehensive economic analysis and comparison of the entire lifetime of CHP from the net present value (NPV), payback period, and cost-saving ratio (CSR). Five systems, including micro-CHP, gas boiler (GB), air-source heat pump (ASHP), domestic gas-fired heater and domestic electric hot water-heater, are simulated. First, this paper takes annual heat use efficiency (AHUE) into account to compare the economy of each domestic hot water (DHW) system. The results show that a domestic gas-fired heater system is the most economical option in the AHUE of 31.28%. The economic influence of CHP and gas-fired heater under different AHUE are then analyzed. The results show that the DHW system based on CHP is the best when the AHUE is more than 55.35%. Finally, three different operation strategies of CHP are considered in this paper. From the perspective of annual energy cost and payback, the internal combustion-based CHP with thermal energy system (TES) is superior to the other two strategies being studied. Considering the optimal economic benefits, the CSR of the three different operation strategies is 41.3%, 69.69% and 69.77%, respectively.

Subsidy strategy of sharing logistics platform

Sharing logistics platform can effectively realize the sharing of idle logistics resources and maximize the utility of logistics resources utilization by publishing and matching the supply and demand information of logistics resource. For sharing logistics platform, subsidy strategy plays a significant role in winning market competition. Therefore, how to establish an effective subsidy scheme is a burning issue. By analyzing the problems in the transaction orders of drivers and consignor on the sharing logistics platform, this paper estimates the subsidy strategy on the following three aspects: (1) establish a dynamic model of freight supply and demand matching according to the freight cost and determine the impact of different subsidy policies on the platform usage; (2) evaluate the solution of different subsidy policies to the matching problem of vehicles and goods, and determine the optimal subsidy scheme based on the evaluation results; (3) establish the subsidy model based on platform maximum benefit and social welfare optimization and analyze a practical case of "Huochebang" (a Sharing logistics platform). The analysis results show that the model constructed in this paper can be well applied to the subsidy problem of sharing logistics platform and assist the platform to establish the most suitable subsidy policy to achieve the optimal economic benefits.

Buildings Optimal Insulation Thickness Effects on Air Conditioning Capacity and PV Self-Consumption Share Level

Energy conservation projects and renewable energy power generation are the future of sustainable energy supply. Combining both is very effective and maximizes benefits. PTs building sector is the highest consumer, constitute 48.6% of the total Palestinian energy balance. Until now, there is no specific Palestinian engineering building code. As a result, building insulation is still mandatory. There are few performed studies about optimal building insulation thickness economic and environmental benefits. Regarding renewable energy national share increase, the PA developed many ambitious plans, most of which concentrated on increasing PV systems installed capacity due to its high potential. PTs enjoy 3000 sunshine hours per year, 5.4 kWh/m2/day average solar radiation. Few studies are targeting Palestinian building's renewable energy share increase through the principle of self-consumption. This research presents a novel approach in investigating the economic feasibility of installing optimal insulation thickness in buildings. Practically, insulation layers are assumed to be installed during the building phase, before mechanical building systems. However, the insulation effect will reduce AC required capacity as a result of reducing summer CL, thus, reduce initial investment. For that reason, the P1-P2 method has been used to generalize the optimal insulation thickness approach for the West Bank area considering different Tb values. It has been found that at Tb=18 °C, optimal thickness values, total cost, energy saved, and Np values are 10-11 cm, 18 $/m2, 175-375 $/m2, and 5-14 years, respectively. Then, a commercial building in Ramallah city was taken as a case study; it has a 1,700m2 roof area for PV installation. PVsyst software is used to design a 173 kWp system. It is estimated to generate 320MWh per year for building self-consumption. The insulation effect raised renewable energy share from 62.6% to 64.1%, and reduced AC rated capacity by 20 refrigeration ton (saved $20,000 as an initial investment).

Energy‐effective carbon dioxide capture and storage design in hydrogen production from liquefied natural gas

To solve the problems of excessive CO2 emission and low resource utilization, which exist in the original hydrogen production process that occurs in an oil refinery, the original natural gas steam reforming process is improved by proposing a new coupled energy-effective hydrogen production process from liquefied natural gas (LNG) with a CO2 capture and storage (CCS) unit; this is based on the background that the oil refinery takes the LNG of the adjacent receiving station as feedstock to produce hydrogen products. The newly designed process recovers the high-grade cold energy released by the raw LNG during gasification to liquefy the CO2 generated in the process, which achieves energy integration to the greatest extent and improves the energy utilization efficiency. Meanwhile, the unreacted raw gas is recycled to improve the resource utilization. Moreover, to obtain the optimal operating parameters of the new process for further evaluation of its advantages, the global optimization model with the optimal overall economic benefit as the objective function is established and the best-operating conditions for the new process with optimal economic benefit are obtained. The result of the energy analysis of the thermodynamic process indicates the exergy efficiency of the new process reaches 60.14%. Compared with the original process, even though the total energy consumption of the new process is increased, the economic benefit still grows by 123.6 million CNY/year owing to the increasing of CO2 product benefit with a high recovery rate of 99.5% in the hydrogen production process and an overall CO2 recovery rate of 69.72%. This study can provide theoretical references for the design and actual production of the hydrogen production process from natural gas.

Dual-radiation-chamber coordinated overall energy efficiency scheduling solution for ethylene cracking process regarding multi-parameter setting and multi-flow allocation

This work proposes a novel energy efficiency scheduling solution for cracking process, which achieves energy efficiency improvement comprehensively and scientifically. The proposed solution reflects several significant features of process operation, for example, the impact of COT, COP, and dilution ratio on product output and energy utilization, the influence of SHS recycle energy and exhaust gas energy loss on fuel and DS consumption. Also, DRC independent parameter setting and asynchronous batch processing have also been taken into account with scheduling of cracking furnace groups. Ethylene cracking process is the core production process in ethylene industry, and is paid more attention to reduce high energy consumption. Because of the interdependent relationships between multi-flow allocation and multi-parameter setting in cracking process, it is difficult to find the overall energy efficiency scheduling for the purpose of saving energy. The traditional scheduling solutions with optimal economic benefit are not applicable for energy efficiency scheduling issue due to the neglecting of recycle and lost energy, as well as critical operation parameters as coil outlet pressure (COP) and dilution ratio. In addition, the scheduling solutions mostly regard each cracking furnace as an elementary unit, regardless of the coordinated operation of internal dual radiation chambers (DRC). Therefore, to improve energy utilization and production operation, a novel energy efficiency scheduling solution for ethylene cracking process is proposed in this paper. Specifically, steam heat recycle and exhaust heat loss are considered in cracking process based on 6 types of extreme learning machine (ELM) based cracking models incorporating DRC operation and three operation parameters as coil outlet temperature (COT), COP, and dilution ratio according to semi-mechanism analysis. Then to provide long-term decision-making basis for energy efficiency scheduling, overall energy efficiency indexes, including overall output per unit net energy input (OONE), output-input ratio per unit net energy input (ORNE), exhaust gas heat loss ratio (EGHL), are designed based on input–output analysis in terms of material and energy flows. Finally, a multi-objective evolutionary algorithm based on decomposition (MOEA/D) is employed to solve the formulated multi-objective mixed-integer nonlinear programming (MOMINLP) model. The validities of the proposed scheduling solution are illustrated through a case study. The scheduling results demonstrate that an optimal balance between multi-flow allocation, multi-parameter setting, and DRC coordinated operation is reached, which achieves 3.37% and 2.63% decreases in net energy input for same product output and conversion ratio, as well as the 1.56% decrease in energy loss ratio.

A multi-objective stochastic optimization model for electricity retailers with energy storage system considering uncertainty and demand response

The development of electricity retailers with energy storage systems expands the energy use ways of users, promotes the consumption of clean energy power generation, and facilitates the development of electricity market. However, due to the imperfect trading mechanism and uncertainties of power supply and demand, the business risk continues to be large, which leads to limited sustainable development of electricity retailers. Therefore, based on the design of a trading mechanism of electricity retailers with energy storage systems in the electricity market, this paper constructs a multi-objective stochastic optimization model of the retailers’ flexible purchase of electricity, aiming at minimizing the cost of electricity retailers and maximizing the consumption of clean energy power generation. In the model, the uncertainty of supply and demand and the demand response are taken into consideration. The results show that: (1) Compared with the conventional optimization model, considering the uncertainty in the medium-and-long-term electricity trading, although the demand for clean energy is reduced, the retail cost of temporary electricity in the day-ahead trading is also reduced. (2) The retailers make full use of flexible power charging and discharging, so the extra cost of purchasing electricity in the day-ahead trading caused by the uncertainty of clean energy is reduced via the energy storage demand response. (3) A price-based demand response can change the electricity purchase demand of retailers, improve the transaction volume between retailers and clean power enterprises in the medium-and-long-term electricity trading, and reduce the energy purchase cost while improving the consumption of clean energy power generation. (4) Due to the impact of initial investment cost and other factors, there is no obvious linear relationship between the capacity of energy storage systems and the reduction of retail energy purchase cost; therefore, it is necessary to apply energy storage systems reasonably to achieve the optimal economic benefits.

A Modified Artificial Bee Colony for Probabilistic Peak Shaving Technique in Generators Operation Planning: Optimal Cost–Benefit Analysis

In the generation of operating system planning, saving utility cost (SUC) is customarily implemented to attain the forecasted optimal economic benefits in a generating system associated with renewable energy integration. In this paper, an improved approach for the probabilistic peak-shaving technique (PPS) based on computational intelligence is proposed to increase the SUC value. Contrary to the dispatch processing of the PPS technique, which mainly relies on the dispatching of each limited energy unit in sequential order, a modified artificial bee colony with a new searching mechanism (MABC-NSM) is proposed. The SUC is originated from the summation of the Saving Energy Cost and Saving Expected Cycling Cost of the generating system. In addition, further investigation for obtaining the optimal value of the SUC is performed between the SUC determined directly and indirectly estimated by referring to the energy reduction of thermal units (ERTU). Comparisons were made using MABC-NSM and a standard artificial bee colony and verified on the modified IEEE RTS-79 with different peak load demands. A compendium of the results has shown that the proposed method is constituted with robustness to determine the global optimal values of the SUC either obtained directly or by referring to the ERTU. Furthermore, SUC increments of 7.26% and 5% are achieved for 2850 and 3000 MW, respectively.

Optimization of evaluation method for recoverable reserves of polymer flooding under the condition of optimal economic benefits

At present, there are two main methods to calibrate the recoverable reserves of polymer flooding (polymer consumption method and one-time calculation method), both of which have their advantages and disadvantages. Which evaluation method can better reflect the characteristics of polymer development and better economic evaluation effect is a problem to be studied. In this paper, the difference between the two evaluation methods is reflected by the change of the depletion rate of fixed assets in different evaluation methods of recoverable reserves. Through the comparative analysis of the economic evaluation results of the two different evaluation methods, the economic evaluation methods suitable for polymer flooding are selected. The results show that the evaluation results of polymer consumption method are better than that of one-off calculation method in the economic evaluation of fixed oil price and variable oil price. Under the fixed oil price, the difference of internal rate of return between the former and the latter is more than 2%. Under the condition of variable oil price, the polymer consumption method is obviously better than the one-off calculation method because of the high depreciation of initial production and the small depreciation of later production (large depreciation value in the early stage and less net value of oil and gas assets in the later stage). Through comparison, the evaluation method of polymer consumption is more practical, the evaluation result of block economic benefit is better, and more development potential can be released at the same time, which is more conducive to the promotion of polymer flooding technology.

Evaluation of carrying capacity for shrimp pond culture with integrated bioremediation techniques

The integrated multi-trophic aquaculture (IMTA) is a semi-artificial habitat optimization ecosystem by co-culture species from multiple trophic levels, in which farm waste produced by species of a higher trophic level is a nutrition source for species of a lower trophic level. However, in system construction it is essential to distinguish the roles of aquaculture organisms from different trophic levels and optimize the aquaculture capacity allocation. With this objective, a carrying capacity evaluation model for shrimp culture with integrated bioremediation techniques was developed, and the efficiency to repair the aquaculture pond environment was evaluated. Scenario simulations were conducted to assess the shrimp culture capacity for optimal economic and ecological benefits. The sensitivity analysis of the model indicated that changes in bivalve biomass had no significant impacts on the concentration of total nitrogen (TN) in the system, and macroalgae were more sensitive to the changes in TN than biofilters did. In conclusion, 1,500,000 Litopenaeus vannamei co-cultured with 15,000 kg Crassostrea gigas and 1,125 kg Gracilaria lemaneiformis per hectare would bring maximum integrated benefit, and the use of integrated bioremediation techniques can make shrimp pond culture a virtuous cycle incorporating both production and restoration.

Numerical Investigation of Techno-Economic Multiobjective Optimization of Geothermal Water Reservoir Development: A Case Study of China

Renewable geothermal utilization is a significant approach for residential heating with two principal modes, direct geothermal district heating systems (DGDHSs) and indirect geothermal district heating systems (IGDHSs). The key principle of geothermal development design is to prevent premature thermal breakthrough, which could result in low efficiency of geothermal heating systems. In this paper, a new approach considering building heating demand, geothermal water resource protection, and optimal economic benefits is presented systematically. The results simulated by OGS software show that well spacing, reinjection temperature, and production rate are the most significant parameters affecting thermal breakthrough in geothermal reservoirs. In addition, production rate and reinjection temperature have a huge effect on the payback period of investment. Comparing IGDHS to DGDHS, the investment in construction of geothermal wells and the annual water consumption decrease by up to 10% and 50%, respectively. Additionally, electricity costs increase by 5% to 30%. The indirect geothermal district heating system with a well spacing of 300 m, a production rate of 100 m3/h, and a reinjection temperature of 301.15 K is much better for this case, both technically and economically. The systematic calculation approach can be reasonably applied to other regions with geothermal energy utilization.

A Multi-Objective Model with Probability Constraints of Trans-Provincial Hydropower Consumption Considering Dynamic Stability Limit

With the rapid development of clean energy and serious delay of grid construction, water abandonment is becoming more and more severe. Under this condition, this paper proposed a multi-objective model with probability constraints of trans-provincial hydropower consumption considering dynamic stability limit. Firstly, a mathematical expression about the dynamic stability limit of trans-provincial channel is constructed. Secondly, a risk assessment index of abandoned water is established on the basis of semi-absolute deviation. Then, based on the framework of stochastic programming, a multi-objective model with probability constraints is proposed for hydropower transmission in trans-provincial trade. By means of genetic algorithm with embedded Monte-Carlo simulation technology, the model can be solved efficiently. Finally, data of Tibet power grid is calculated to verify the validity and universality of the research. The results show that the established model can achieve optimal economic benefit between grid companies and generation enterprises, and also effective management of water abandonment risk.

Cost-effective optimization design of light hydrocarbon recovery process based on exergy analysis

To solve the problems of high energy consumption and the difficulty of adapting to the changes in oil gas composition and state, which exist in the original light hydrocarbon recovery process that occurs in an oil gas field, the original “auxiliary cooling & direct heat exchanger” process is improved by taking advantage of the mainstream turbo-expander cryogenic process; this is based on the characteristics of the high pressure of the exploited inlet oil gas. With reduction of the total energy consumption as the goal, the newly designed process recovers the cold energy in the internal system to the greatest extent and efficiently achieves energy integration, which can eliminate the complex and energy-intensive propane refrigeration systems. Moreover, to obtain the optimal operating parameters of the new process for further evaluation of its advantages, an optimization model and solution strategy are established with the optimal economic benefit as the objective and the product quality and recovery as the constraints. To solve the optimization model to optimize the new process, an optimization algorithm based on Sequential Quadratic Programming in combination with the constraint boundary search is proposed, and the optimal operating conditions for the new process with optimal economic benefit are obtained. Compared with the original process, the new process is more reasonable in terms of energy utilization, and the exergy efficiency of the system is increased by 6.7%. The total operating cost is reduced by 18%, and the economic benefit is increased by approximately 12.5 million CNY/year owing to the increase in product recovery. In addition, the new process involves no risk of CO2 freezing; thus, it is safe and feasible. This study can provide theoretical reference for the design and actual production of light hydrocarbon recovery in oil gas fields.