Addressing production bottlenecks and brownstock washer optimization via a membrane concentration system

Advancements in membrane systems indicate that they will soon be robust enough to concentrate weak black liquor. To date, the economic impact of membrane systems on brownstock washing in kraft mills has not been studied and is necessary to understand the viability of these emerging systems and their best utilization. This study investigated the savings that a membrane system can generate related to brownstock washing. We found that evaporation costs are the primary barrier for mills seeking to increase wash water usage. Without these additional evaporation costs, we showed that our hypothetical 1000 tons/day bleached and brown pulp mills can achieve annual savings of over $1.0 MM when operating at higher dilution factors and fixed pulp production rate. We then investigated the impact of increasing pulp production on mills limited by their equipment. In washer-limited mill examples, we calculated that membrane systems can reduce the annual operating cost for a 7% production increase by 91%. Similarly, in evaporator-limited mill examples, membrane systems can reduce the annual operating cost for a 7% production increase by 86%. These results indicated that membrane systems make a production increase significantly more feasible for these equipment-limited mills.

Reduction of Annual Operational Costs in Power Systems through the Optimal Siting and Sizing of STATCOMs

The problem of the optimal siting and placement of static compensates (STATCOMs) in power systems is addressed in this paper from an exact mathematical optimization point of view. A mixed-integer nonlinear programming model to present the problem was developed with the aim of minimizing the annual operating costs of the power system, which is the sum of the costs of the energy losses and of the installation of the STATCOMs. The optimization model has constraints regarding the active and reactive power balance equations and those associated with the devices’ capabilities, among others. To characterize the electrical behavior of the power system, different load profiles such as residential, industrial, and commercial are considered for a period of 24 h of operation. The solution of the proposed model is reached with the general algebraic modeling system optimization package. The numerical results indicate the positive effect of the dynamic reactive power injections in the power systems on annual operating cost reduction. A Pareto front was built to present the multi-objective behavior of the studied problem when compared to investment and operative costs. The complete numerical validations are made in the IEEE 24-, IEEE 33-, and IEEE 69-bus systems, respectively.

A study on evaluation systems for optimized design GSHP and ES technologies used in HVAC systems

Due to the lack of suitable evaluation systems for heating, ventilation, air-conditioning (HVAC) systems with ground source heat pump (GSHP) and energy storage (ES) technologies, it is difficult to design a building HVAC system to achieve optimized design with regard to investment cost, energy saving and environmental protection. This is a study on developing a fuzzy evaluation system by including GSHP and ES with comprehensively determined weights into an HVAC system. A questionnaire method was used and the answers from 21 HVAC experts were analyzed to facilitate the modeling. Taking a commercial integrated project in Nanjing as an engineering case, the evaluation system was tested. If the system with a comprehensive merit value of 0.303 is adopted, the annual operating cost is reduced by 32.5%, the annual total life cycle cost is reduced by 26.5% and the primary energy consumption and carbon emissions are reduced by 10.5%, with the initial investment increased by 6.5%. This study revealed that the newly developed evaluation system is very useful for realizing the optimal design of HVAC systems.

A Two-Stage Configuration Method of Integrated Community Energy System Considering Demand Response

The integrated community energy system (ICES) has aroused considerable attention for its low emission and high operating efficiency. The existing configuration methods for ICES with multi-energy sectors ignored the controllable load. In this paper, a two-stage configuration method of ICES is developed to achieve the minimum annual investing and operating cost. At the first stage, the capacities of components in ICES are optimized to minimize the annual investment cost of ICES. At the second stage, the annual operating cost including the electricity and gas purchase costs and the component maintenance cost is minimized to satisfy the energy load. The controllable load under the time-of-use energy price in seasonal typical days is considered in the second stage. Relevant simulations are conducted to validate the effectiveness of the proposed configuration method for ICES. Considering the controllable load, comparative simulations illustrate that the proposed configuration method can significantly reduce the battery investment cost.

Investment Payback Period Calculating Model for Airport Bridge Facility

Due to the uncertainty and difficulty of estimating the investment payback period of the airport bridge facility, a model for calculating the investment payback period of bridge facility is proposed in this paper from the perspective of airport routine operation. Based on the actual operational data of Kunming Changshui Airport, Wuhan Tianhe Airport, and Lijiang Sanyi Airport in 2018, the factors influencing the payback period of bridge facility are the number of bridge facilities and service time, which have been discussed in this paper. According to the simulation, it is concluded that the number of bridge facilities and service time are the key points to the length of the investment payback period, and the annual operating cost of the airline can be saved quite a lot. The research results can be used to assist the leaders’ decision-making of airports and airlines for the promotion of the service of bridge facilities.

Research of cooling load & chiller selection in metro station

Air conditioning is of the most energy saving potential system in the metro station. This study analyzes the composition and characteristics of air conditioning cooling load in a metro station. The hourly distribution and the proportion of each cooling load are calculated. The results show that cooling load fluctuation of metro air conditioning is large, and the operating time of different load varies greatly. According to the air conditioning cooling load, the coefficient of performance of the fixed frequency screw, variable frequency screw, series countercurrent screw and magnetic bearing centrifugal chiller under the load of 20–100% are tested. The annual operating cost of four chillers is compared. Test results show that the magnetic bearing centrifugal chiller has a much higher coefficient of performance at part load and lower annual operating cost. Increased initial investment can be recovered in less than 2 years. The magnetic bearing centrifugal chiller is suitable as a cold source of air conditioning system in the metro station.

Planning of the Multi-Energy Circular System Coupled with Waste Processing Base: A Case from China

With the accelerated development of urbanization, waste disposal has become a tough problem. If waste cannot be disposed properly, it will lead to environment pollution and waste of resources. Since the energy utilization of the Waste Processing Base (WPB) has not been considered thoroughly, optimal planning of the Multi-Energy Circular System (MECS) coupled with the WPB is studied in this paper. Based on a typical WPB, this paper adds Power to Gas (P2G) and energy storage equipment, and applies a bi-level optimization model to optimize energy utilization. The minimum of total annual cost is the objective of the upper model, whose decision variables are the capacity of each equipment. The minimum annual operating cost is the lower model’s objective whose decision variables are the control parameters of certain energy equipment. Finally, a practical WPB is used for the demonstration and simulation of the proposed planning scheme. The analysis of the simulation results indicates that the collaborative optimization of the MECS coupled with WPB is effective, and improves the benefits of energy, economy, and environment enormously.

Analysis of an energy storage sizing for grid-connected photovoltaic system

This paper present on the analysis of an energy storage sizing for a small grid-connected PV system. This project is to study the proper sizing of energy storage (battery) in a grid-connected PV system for consumers whom purchase and sell electricity from and to the utility grid. The goal is to minimize the total cost of the operation for a consumer with a PV system with a battery storage system. This is to make sure that minimizing the total annual operating cost while maintaining an efficient system. This study uses typical consumer load consumption, and solar irradiance data throughout a year, while varying the type of battery storage (study lead acid and Lithium ion battery) as an energy storage for a similar system. Since lithium ion is not the main options to be integrated with PV system, this study will then reveal the data in terms of cost on why it is not a popular choice.

Investment Costs of Heating in Poland and Spain—A Case Study

Heating a room or a building is a basic annual operating cost. This paper presents typical heating systems in Poland and Spain. Based on the calculations made for lecture rooms located in different climate zones in Poland and Spain, the design heat loss and energy demand for heating are compared and analyzed. Additionally, the paper includes a statement about selected radiators and a comparison of their purchase costs for individual locations.