Feasibility Study for Self-Sustained Wastewater Treatment Plants—Using Biogas CHP Fuel Cell, Micro-Turbine, PV and Wind Turbine Systems

This paper studies the application of renewable energy sources in wastewater treatment plants to achieve self-sustain- ability of power. The data of wastewater treatment plant in the rural city of Toukh-EGYPT are presented as a case-study. The primary objective is to provide an entirely renewable standalone power system, which satisfies lowest possible emissions with the minimum lifecycle cost. Mass balance principle is applied on the biodegradable components in the wastewater to evaluate the volume of digester gas that is produced from sludge through anaerobic digestion process. Using digester gas as a fuel lead to study combined-heat-and-power technologies, where fuel cell is selected in order to abide by the low emissions constraint. The study assessed the electrical power obtained from fuel cell and the utilization of the exhausted heat energy for additional electrical power production using a micro-turbine. After covering the major part of load demand, the use of other renewable energy sources was studied. The strength of both solar and wind energy was determined by the case-study location. Hybrid optimization model for electric renewable (HOMER) software was used to simulate the hybrid system composed of combined-heat-and-power units, wind turbines and photovoltaic systems. Simulation results gave the best system configuration and optimum size of each component beside the detailed electrical and cost analysis of the model.

Low-carbon Operation of Combined Heat and Power Integrated Plants Based on Solar-assisted Carbon Capture

Accelerating the development of renewable energy and reducing CO_(2)emissions have become a general consensus and concerted action of all countries in the world. The electric power industry, especially thermal power industry, is the main source for fossil energy consumption and CO_(2)emissions. Since solvent-based post-combustion carbon capture technology would bring massive extra energy consumption, the application of solar-assisted carbon capture technology has attracted extensive attention. Due to the important role of coal-fired combined heat and power plants for serving residential and industrial heating districts, in this paper, the low-carbon operation benefits of combined heat and power integrated plants based on solar-assisted carbon capture(CHPIP-SACC) are fully evaluated in heat and power integrated energy system with a high proportion of wind power. Based on the selected integration scheme, a linear operation model of CHPIP-SACC is developed considering energy flow characteristics and thermal coupling interaction of its internal modules. From the perspective of system-level operation optimization, the day-ahead economic dispatch problem based on a mix-integer linear programming model is presented to evaluate the low-carbon benefits of CHPIP-SACC during annual operation simulation. The numerical simulations on a modified IEEE 39-bus system demonstrate the effectiveness of CHPIP-SACC for reducing CO_(2)emissions as well as increasing the downward flexibility. The impact of different solar field areas and unit prices of coal on the low-carbon operation benefits of CHPIP-SACC is studied in the section of sensitivity analysis.

计及阶梯式碳-绿证联合交易和需求响应的生物质能综合能源系统优化

在“30·60”“双碳”目标背景下,生物质能因其储量大、污染小、可再生等优势愈发受到重视。为促进生物质能的有效应用、减少综合能源系统的碳排放量,提出一种考虑阶梯式碳-绿证联合交易机制和综合需求响应下的生物质能综合能源系统优化模型。首先,基于有机朗肯循环技术,对生物质热电联产的关键机理进行研究,构建生物质热电联产模块,同时对系统中其他设备建立数学模型;其次,将多种负荷的综合需求响应机制引入系统,实现电-热-气灵活响应;然后,在阶梯式碳交易机制与绿色证书交易机制的基础上,根据国家可再生能源政策,构建阶梯式碳-绿证联合交易机制;最后,针对6个不同场景的实际算例,从多个角度对比研究生物质成本、阶梯式碳-绿证联合交易机制和综合需求响应分别对系统规划产生的影响。算例结果表明,以生物质热电联产为核心,并考虑阶梯式碳-绿证联合交易机制和综合需求响应的综合能源系统具有良好的经济性和碳减排效果。

CCPP机组余热锅炉高压蒸发器泄漏分析与处理

燃气-蒸汽联合循环机组(CCPP)作为高效能源转换系统,在钢铁等工业领域得到广泛应用。余热锅炉作为CCPP机组的核心部件,其稳定运行直接关系到整个机组的效率和安全性。文章针对某钢厂燃气轮机组配套余热锅炉高压蒸发器上部迎烟气面频繁泄漏问题进行了深入研究,分析泄漏原因为其下联箱内沉积物导致蒸发器管内水流量减小,进而产生汽水混合物的冲击腐蚀,同时炉膛局部区域的“烟气走廊”现象加剧了这一腐蚀过程。针对这一问题,采取更换泄漏管段、改造下联箱定排管系统以提高排污效率、修复和完善烟气挡板以减少“烟气走廊”形成、优化定期排污操作以及制定定期的检查和维护计划等措施,有效地解决了高压蒸发器的泄漏问题,提高了设备的稳定性和安全性。

Biomass-fuelled combined heat and power: integration in district heating and thermal-energy storage

Conventional approaches towards energy-system modelling and operation are based upon the system design and performance optimization.In system-design optimization,the thermal or mechanical characteristics of the systems providing for the heat or electricity demands were derived separately without integration with the energy source and without interaction with demand,which results in low-efficiency energy performance.This paper presents a key review on the integration of biomass-powered combined heat and power(BCHP)systems in district-heating systems as well as coupling with thermal-energy storage.In BCHP design,the appropriate sizing of the associated components as part of the district-heating system is very important to provide the optimal dispatch strategy as well as minimized cost and environmental impact while it co-operates with thermal-energy storage.Future strategies for the feasibility,evaluation and integration of biomass-powered energy systems in the context of district systems are also studied.

火电厂源侧综合能源系统集成及性能评估研究

本文建立了以火电厂为核心,消纳可再生能源并提供冷热电汽综合能源服务的一套能源系统,通过对整体系统及关键子系统热力性能分析,验证了提出模型和方法的有效性。并研究了一些关键运行参数对系统综合性能的影响,验证了提出模型和方法的有效性和优越性。结果表明:通过改变火电厂的源侧参数,可以提高综合能源系统荷侧的输出量;且生物质转化气对汽轮机发电功率的影响最大。热泵系统的负荷随着进入系统中的给水流量的增大而增大,利用汽轮机中的部分抽汽来驱动热泵系统,虽然发电功率下降了10.88%,但是却为用户提供了16.8MW的热负荷和16.2MW的冷负荷以及27.78t/h的蒸汽量。

电力市场环境下生物质气化耦合燃煤机组与风电场联合自调度优化策略

利用生物质气化耦合燃煤发电技术可以提升火电机组的燃料及运行灵活性,从而促进风电的高水平消纳,同时实现生物质能的有效开发利用。该文首先建立反映生物质气化耦合热电联产机组内部能流过程和外部出力特性的运行模型。然后,从能源供应商视角出发,给出耦合机组与风电场联合参与日前、日内和实时平衡市场的多阶段决策框架,提出反映联合体期望收益和条件风险价值的多目标自调度策略。最后,利用基于字典优化框架的增强ε约束法,给出构建帕累托前沿的多目标优化求解流程。以一台350 MW燃煤热电联产机组和一座600 MW风电场构成的联合体为例进行分析。结果可知,增设生物质气化子系统和联合运行能够使其经济效益提升6%左右,同时有利于降低能源供应商的运营风险。

考虑多重不确定性的电-热-气综合能源系统协同优化方法

综合能源系统(IES)中风-光出力和负荷不确定性对系统的运行安全和规划提出了挑战。以包含光伏、生物质气化热电联产等设备的IES调度过程为例,提出一种集成随机规划-信息间隙决策理论(IGDT)的方法应对系统优化运行过程中源-荷侧的多重不确定性。随机规划方法处理光伏出力不确定性,并将优化结果作为IGDT处理负荷不确定性的基准值。其中,IGDT中的风险规避和风险寻求策略反映了系统管理者面对不确定性带来运行风险时的态度。结果表明,风险规避策略下生物质气化热电联产日电能输出总量高于风险寻求策略下生物质气化热电联产日电能输出总量的50%。不同策略下的调度结果差异性为系统管理者提供了灵活的选择。

生物质机组低真空循环水供热系统设计

阐述了低真空循环水供热的基本原理,并结合某生物质发电机组项目设计,对低真空供热的设计进行了分析,指出系统在设计应用和运行管理等方面的注意事项。采用低真空供热能够提高全厂热效率,充分利用能源,同时增加企业经济效益。

涉及长输供热管网的热电联产改造研究

文章以呼和浩特市托克托电厂为例,从电厂的供热潜力、长输供热管网的敷设方案等角度详细分析了涉及长输供热管网的热电联产改造。结果表明:托克托电厂能满足城市的远期供热负荷;传统供热方式与大温差供热方式相结合的综合供热方式更适合该项目;相比于DN1400管道,采用DN1600的输送管道,不仅能节约输送能耗,而且在供热年限内经济性更高;包裹110 mm厚的保温层后,整个管道热损失仅占3%。

Carbon emission impact on the operation of virtual power plant with combined heat and power system

A virtual power plant （VPP） can realize the aggregation of distributed generation in a certain region, and represent distributed generation to participate in the power market of the main grid. With the expansion of VPPs and ever-growing heat demand of consumers, managing the effect of fluctuations in the amount of available renewable resources on the operation of VPPs and maintaining an economical supply of electric power and heat energy to users have been important issues. This paper proposes the allocation of an electric boiler to realize wind power directly converted for supplying heat, which can not only overcome the limitation of beat output from a combined heat and power （CHP） unit, but also reduce carbon emissions from a VPP. After the electric boiler is considered in the VPP operation model of the combined heat and power system, a multi-objective model is built, which includes the costs of carbon emissions, total operation of the VPP and the electricity traded between the VPP and the main grid. The model is solved by the CPLEX package using the fuzzy membership function in Matlab, and a case study is presented. The power output of each unit in the case study is analyzed under four scenarios. The results show that after carbon emission is taken into account, the output of low carbon units is significantly increased, and the allocation of an electric boiler can facilitate the maximum absorption of renewable energy, which also reduces carbon emissions from the VPP.

Performance Improvement of Combined Cycle Power Plant Based on the Optimization of the Bottom Cycle and Heat Recuperation

Many F class gas turbine combined cycle （GTCC） power plants are built in China at present because of less emission and high efficiency. It is of great interest to investigate the efficiency improvement of GTCC plant. A combined cycle with three-pressure reheat heat recovery steam generator （HRSG） is selected for study in this paper. In order to maximize the GTCC efficiency, the optimization of the HRSG operating parameters is performed. The operating parameters are determined by means of a thermodynamic analysis, i.e. the minimization of exergy losses. The influence of HRSG inlet gas temperature on the steam bottoming cycle efficiency is discussed. The result shows that increasing the HRSG inlet temperature has less improvement to steam cycle efficiency when it is over 590℃. Partial gas to gas recuperation in the topping cycle is studied. Joining HRSG optimization with the use of gas to gas heat recuperation, the combined plant efficiency can rise up to 59.05% at base load. In addition, the part load performance of the GTCC power plant gets much better. The efficiency is increased by 2.11% at 75% load and by 4.17% at 50% load.

Dispatch Model for Integrated Heat and Power Systems Considering Internal Composition of CHP Plants

An integrated heat and power system(IHPS)is a promising approach for alleviating wind curtailment problems.In an IHPS,the combined heat and power(CHP)plant is the key component,which supplies both heat and electric loads,and couples the thermal system and power system.However,existing research commonly ignores or simplifies the internal composition of CHP plants,which could lead to some unavoidable errors.This paper focuses on the internal composition of CHP plants,and models the physical processes in different components and flexible resources in the CHP plant.Furthermore,a joint dispatch problem of an IHPS with the above CHP plant models is formulated,and an iterative algorithm is developed to handle the nonlinearity in this problem.Case studies are performed based on a real CHP plant in Northern China,and the results indicate that the synergistic effect of different energy resources in the CHP plant is realized by the joint dispatch model,which promotes wind power accommodation and reduces fossil fuel consumption.

The ecosystem of Lake Kenon:past and present(Transbaikal Territory,Russia)

Present-day conditions of the Lake Kenon ecosystem are determined by a combination of natural and anthropogenic factors. We have estimated the effects of a complex of factors on the condition of the abiotic environment and on specific biological components in the lake ecosystem. Change in biogenic load has caused an increase in the role of phytoplankton in the general balance of organic matter during the high-water period. Charophytes are the main dominants of bottom vegetation. Anthropogenic load has caused a decrease in both fish species and fish capacity. The lake application as a water reservoir-cooler has influenced the average annual water mineralization （from 420 mg/L to 530.0 mg/L with a maximum 654 mg/L in 1993） and fluctuations in its hydrochemical composition. The present composition of the lake is sulfate-hydrocarbonate-chloride calcium-sodic-magnesium in character. S（Y44 content is twice as much as the maximum permissible concentration in fishery waters. Water drainage from an ash disposal area to the lake has caused an increase in chemical-element concentrations including the heavy metals. Hg concentration in Perca fluviatilis muscles is 0.5 9g/g dry wt. Thus, understanding directions in the ecosystem of the water reservoir-cooler under changing hydrological conditions will let us forecast the consequences of new combined heat and power plant operation.

含吸收式热泵的高能效热电厂优化运行研究

针对乏汽余热利用方案的差异性对比,文章首先基于吸收式热泵整体建模,建立配置最佳容量吸收式热泵后抽凝机组的可行运行区间模型以及煤耗函数模型。以此为基础,量化分析配置吸收式热泵较低压缸可灵活切除改造、高背压改造二者在运行灵活性、调峰成本和供热能力方面的优劣,提出包含3种余热利用方案的高能效热电厂厂内机组优化调度通用模型。最后根据东北某热电厂的数据,在不同场景下校验了3种余热利用方案的差异,进一步总结不同余热利用方案并存时,厂内不同类型机组之间的协同运行规律。

Schedule for Reducing the Use of Peat and the Possibilities of Replacing It with Forest Chips in Energy Production in Finland

Between 2018 and 2020, an average of 15 TWh of energy peat was consumed in Finland. Energy peat is used in 260 boilers in Finland, which produce district heat and heat and steam for industry, as well as electricity as cogeneration (CHP) in connection with district heating and industrial heat production. Peat accounts for 3% - 5% of the energy sources used in Finland, but its importance has been greater in terms of security of supply. With current use in accordance with the 2018-2020 average, the emissions from peat are almost 6 Mt CO2 per year in Finland, which is 15% of emissions from the energy sector. In this study, the technical limitations related to peat burning, economic limitations related to the availability of biomass, and socio-economic limitations related to the regional economy are reviewed. By 2040, the technical minimum use of peat will fall to 2 TWh. The techno-economical potential may be even lower, but due to socio-economic objectives, peat production will not be completely ceased. The reduction in the minimum share assumes that old peat boilers are replaced with new biomass boilers or are alternatively replaced by other forms of heat production. Based on the biomass reserves, the current use of peat can be completely replaced by forest chips, but regional challenges may occur along the coast and in southern Finland. It is unlikely that the current demand for all peat will be fully replaced by biomass when part of CHP production is replaced by heat production alone and combustion with waste heat sources.

考虑碳捕集及需求响应的虚拟电厂热电联合优化调度

燃煤热电机组独特的以热定电工作方式与风电反调峰特性,导致虚拟电厂存在调峰能力不足的问题,且碳排放量居高不下。目前,通过碳捕集技术辅之合理的需求响应机制是实现虚拟电厂灵活低碳运行的重要手段。研究的虚拟电厂在包含热电厂、风电场、光伏电站的基础上加入碳捕集设备与电锅炉并考虑需求响应机制。基于虚拟电厂的源荷结构与工作原理,建立了考虑碳捕集及需求响应的虚拟电厂优化调度模型,并应用自适应免疫遗传算法对模型进行求解,分析了4种不同策略的调度情况。仿真结果表明,规划的虚拟电厂结构合理,提出的调度策略能通过协调源荷两侧资源,在提高系统新能源消纳能力与总收益的同时达到减少碳排放量的目的。

考虑风电消纳的含P2G-CCS虚拟电厂优化调度

针对热电联供(CHP)运行过程中产生大量CO_(2)以及“以热定电”运行方式导致的弃风问题,提出一种考虑风电消纳的含电转气和碳捕集系统(P2G-CCS)虚拟电厂优化调度方案。首先,在虚拟电厂(VPP)中引入P2GCCS耦合模型,并使其与CHP能源流动形成循环,将CO_(2)作为CHP的燃料来源;其次,在VPP中加入地源热泵(GSHP),与P2G-CCS协同运行,实现CHP的热电解耦,促进风电消纳;最后,将电、气综合需求响应引入负荷侧,进一步促进风电消纳。以华北某地区VPP为例进行算例分析,结果表明所提调度方案可以有效促进风电消纳,同时碳排放和运行成本也更低。

考虑多重不确定性的垃圾焚烧热电联产电厂日前鲁棒申报策略

垃圾焚烧电厂是处理固体废弃物的主要方式之一,并且越来越多的垃圾焚烧电厂具有热电联产模式,既可以在电力市场出售电能,又能为相邻区域供热。基于此,在考虑日前电力市场价格和固体废弃物来量不确定性的前提下,构建了垃圾焚烧热电联产电厂的两阶段鲁棒申报模型。该模型可以在最坏场景下保证垃圾焚烧热电联产电厂的预期收益最大化。为了对模型进行求解,引入Benders分解将该模型分解为易求解的主问题和子问题。最后,算例仿真结果表明,该模型可以帮助运营商制定经济合理的电能申报策略。并通过对比分析和敏感性分析验证了该模型的优越性与适用性。

太阳能光伏-内燃机发电及余热利用系统热力学分析

对利用太阳能和生物质能的联合冷热电系统(CCHP)进行热力学分析。系统由内燃机和太阳能光伏电池供电,由吸收式制冷及热水系统进行余热回收。太阳能光伏电池采用五参数模型,内燃机为零维、单区模型。分析转速和压比对内燃机输出功率、排气排放物和气缸内传热的影响。结果显示:太阳能光伏电池效率为14%,日发电量500 kWh;内燃机热效率可以达到37%。转速提高后,整体CCHP电效率提高2.8%,余热利用效率提高10%。内燃机的压缩比增大后,CCHP电效率增大0.52%,整体冷热电效率几乎不变。整个CCHP系统电效率为20%,冷热电联合效率可以达到40%。