球磨自动加球机及其效益分析

一、前言 在大多数选矿厂,物料磨碎费用占生产成本的60～70％。磨矿作业主要有两项消耗:能耗和钢耗。能耗约占磨矿费用的60％,世界上各种磨矿的电耗占总电耗的3～4％。磨矿钢耗(钢球和衬板消耗)约占磨矿费用40％的绝大部分。据统计,1979年我国各类磨矿钢耗达42.56万吨。因此,提高球磨机的生产能力,降低磨矿钢耗和能耗具有极其重要的现实意义。     

能量因数与节能潜力评估

介绍了能量因数的概念以及应用单位能量因数能耗如何评价一个炼油厂的用能水平和不同炼油厂之间的能耗的对比.     

中国石油广西石化千万吨级炼厂“节能减排”设计

介绍了中国石油在南方布点建设的大型炼油企业——广西石化1000×10^4t／a炼油项目的用能特点。分析比较了该项目的能耗指标,该项目全厂炼油部分综合能耗为74．69kg标油／t原油,单位因数能耗为10．01kg标油/（t原油·能量因数）,达到了国内外先进水平。介绍了该项目主要的节能、节水措施以及“节能减排”预期效果     

基于小波包特征提取及统计分析的磨煤机球径配比诊断

火电厂制粉系统球磨机筒内钢球球径配比会直接影响制粉出力,为了提高制粉系统出力降低球磨机能耗,一种用于诊断球径配比的方法在文中被研究。为了获得不同球径配比,在现场进行了钢球装载试验;通过在球磨机轴承上安装振动传感器记录轴承振动信号,尝试利用小波包频带顺序分解技术对获得的轴承振动信号进行处理,以提取表征不同球径配比的特征量;最后对获得的特征量进行统计分析,通过统计分析对球径配比做出诊断。试验研究及工程实例分析表明,利用轴承振动信号的相关频带能量特征能够诊断球径配比的偏移,该研究具有重要的工程应用价值。     

神经网络球磨机出力软测量模型的建立

为了准确地获得球磨机的制粉出力,提出了用灰熵关联分析法分析球磨机制粉出力的影响因素,选择对球磨机制粉出力影响较大的几个因素作为辅助变量建立模型,以最优拉丁超立方法选取的数据作为训练样本,基于BP神经网络建立球磨机出力软测量模型,并选出几组样本验证所建模型的可靠度.结果表明:所建立的球磨机出力软测量模型预测输出误差较小,有较强的泛化能力,具有很好的测量性能.     

基于运行模式识别的球磨机自适应解耦模糊控制与仿真

针对目前球磨机系统控制存在的不足,提出了一种基于运行模式识别的球磨机系统自适应模糊解耦控制算法.首先,分析了球磨机系统的动态特性,并结合某电厂测试试验,得到了球磨机系统的数学模型;其次,采用LS-SVM算法对球磨机系统的运行状态进行识别和分类;对于正常工况,针对耦合回路,设计了自适应解耦模糊控制器对球磨机进行控制;对于异常工况,给出了相应的控制策略.最后对正常工况下的自适应解耦模糊控制算法进行了仿真研究.仿真结果表明,该算法能够有效地实现球磨机系统运行工况模式识别和耦合回路的解耦控制,控制系统具有良好的动态性和鲁棒性.     

水泥磨机改造与水泥生产节能

根据滚动摩擦阻力小于滑动摩擦阻力的原理，从减少水泥球磨机主轴承的摩擦着手，采用滚动轴承代替滑动轴承，降低球磨机能耗，达到明显节能效果，并在浙江有水泥厂的使用中得到验证。     

基于飞蛾扑火算法的浆液循环泵组合优化

为了解决浆液循环泵能耗过高问题,在满足供浆指标约束条件的基础上,建立浆液循环泵的最小能耗优化模型,采用螺旋式搜索的飞蛾扑火优化算法求解浆液循环泵的最优组合和频率以及该条件下的最低能耗.分析了10个典型工况点下实际运行负荷、浆液pH值和烟气入口二氧化硫浓度对浆液循环泵能耗的影响.结果 表明:负荷与入口二氧化硫浓度越高,能...     

球磨机防磨降耗的措施

本文介绍了几种降低球磨机磨耗和能耗的措施和新型耐磨材质,并取得了显著的效果。可供有同类型磨煤机的电厂或单位参考和借鉴。     

单位GDP能耗的分解模型及其分析

通过研究因素替代法,建立了单位GDP能耗分解模型,然后对中国1994年~2005年单位GDP能耗及其影响因素的历史轨迹和变化特征作了分析。基于以上研究,运用单位GDP能耗分解模型,将1994年~2005年单位GDP能耗分解为三次产业单位增加值能耗影响份额、产业结构影响份额、单位GDP生活能耗影响份额,并对分解结果进行了分析。     

System analysis of hydrogen production from gasified black liquor

Hydrogen produced from renewable biofuel is both clean and CO₂ neutral. This paper evaluates energy and net CO₂ emissions consequences of integration of hydrogen production from gasified black liquor in a chemical pulp mill. A model of hydrogen production from gasified black liquor was developed and integration possibilities with the pulp mill's energy system were evaluated in order to maximize energy recovery. The potential hydrogen production is 59 000 tonnes per year if integrated with the KAM reference market pulp mill producing 630 000 Air dried tonnes (ADt) pulp/year. Changes of net CO₂ emissions associated with modified mill electric power balance, biofuel import and end usage of the produced hydrogen are presented and compared with other uses of gasified black liquor such as electricity production and methanol production. Hydrogen production will result in the greatest reduction of net CO₂ emissions and could reduce the Swedish CO₂ emissions by 8% if implemented in all chemical market pulp mills. The associated increases of biofuel and electric power consumption are 5% and 1.7%, respectively.     

Energy efficiency at the paper mill—dilemma of improvement

The paper industry is heavily using energy during all the phases of the manufacturing process. This is especially the case in Nordic mills where pressure ground wood is the source of fiber. The purpose of this case study is to show how energy consumption behaves on a monthly basis in a Finnish paper mill that has several paper machine lines. The research examines different categories of energy usage, as well as the overall costs. The results show that the monthly energy usage varies significantly. The electricity consumption of the case mill is rather steady, but there is significant monthly variation in steam and natural gas consumption. Moreover, steam and electricity unit costs increased significantly when coming to the end of the research period. The longitudinal case data shows that it is difficult to enhance energy consumption per produced unit at the paper mill. One reason for this is the bleak demand outlook for the end products, which often result in downsizing and closing operations inside the integrated unit.     

Chemical process simulation for minimizing energy consumption in pulp mills

Chemical process simulation has proven to be an effective tool for performing a systematic and global analysis of energy systems to identify routes for maximizing the process efficiency concerning to the heat recovery. This paper shows an application of computer simulations in a Brazilian pulp mill, using two strategies for minimizing the mill energy consumption. In the first one, the overall heat transfer coefficient has been predicted for each body of the multiple effect evaporators by using continuous on-line data from the industrial plant in the black liquor recover unit. By monitoring oscillations of this heat transfer coefficient, the suitable time for washing the evaporator heat transfer surfaces can be well determined, reducing the energy loss during black liquor evaporation. In the second strategy, the liquor combustion has been simulated as function of the black liquor solids concentration to analyze its effect on the recovery boiler efficiency improvement.     

Assessing the value of pulp mill biomass savings in a climate change conscious economy

Pulp mills use significant amounts of biofuels, both internal and purchased. Biofuels could contribute to reach greenhouse gas emission targets at competitive costs. Implementing process integration measures at a pulp mill in order to achieve pulp production with less use of energy (biofuels) has not only on-site consequences but also off-site consequences, such as substitution of fossil fuels elsewhere by the saved pulp mill biofuels, and less on-site electric power generation. In this paper a method, a linking model, is suggested to analyse pulp mill biofuel saving measures when carbon dioxide (CO₂) external costs are internalised. The linking model is based on equilibrium economics and links information from CO₂ constrained energy market future scenarios with process integration measures. Pulp mill economics and marginal energy market CO₂ response are identified. In an applied study, four process integration measures at a Swedish pulp mill were analysed using five energy market future scenarios emanating from a Nordic energy model. The investigated investment alternatives for biofuel savings all result in positive net annual savings, irrespectively of the scenario used. However, CO₂ emissions may increase or decrease depending on the future development of the Nordic energy market.     

Energy efficiency investments in Kraft pulp mills given uncertain climate policy

Energy efficiency measures in pulp mills can potentially reduce the consumption of biofuel, which can instead be exported and used elsewhere. In this paper a methodology is proposed for analysing the robustness of energy efficiency investments in Kraft pulp mills or other industrial process plants equipped with biofuelled combined heat and power units, given uncertain future climate policy. The outlook for biofuel and electricity prices is a key factor for deciding if energy efficiency measures are cost competitive. CO ₂ emission charges resulting from climate policy are internalized and thus included in electricity and biofuel prices. The proposed methodology includes a price-setting model for biofuel that assumes a constant price ratio between biofuel and electricity in the Nordic countries. Thirteen energy efficiency retrofit measures are analysed for an existing Swedish Kraft pulp mill. Special attention is paid to heat-integrated evaporation using excess process heat. Four possible energy market development paths are considered that reflect different climate policies. Pulp mill energy efficiency investments considered are shown to be robust with respect to uncertain climate policy. Copyright © 2006 John Wiley & Sons, Ltd.     

Influence of seasonal variations on energy-saving opportunities in a pulp mill

Significant energy savings can be achieved in the pulp and paper industry through process integration. The aim of this paper was to investigate how much seasonal variations in the process influence the potential for making energy savings. The hot and warm water system in a market pulp mill has been evaluated from an energy point of view, using pinch analysis. Considerable energy-saving potential was found, 40.7 MW, of which 16.5 MW was in the form of steam savings. The steam savings represent 7% of the total steam consumption at the mill. New heat exchanger networks were redesigned using different approaches. The influence of seasonal variations was estimated from the calculated energy savings when monthly averages were used in the new heat exchanger networks. When seasonal variations were taken into account, the energy-saving opportunities fell by 2.5–5.0 MW, depending on heat exchanger network design, compared with a steady-state scenario. Consequently, 88–94% of the theoretical energy savings could be realised. An economic evaluation indicates positive earnings from investment in a new heat exchanger network when seasonal variations were taken into account, even with low prices for the extracted steam and excess heat (5 €/MWh) and with an annuity factor of 0.2.     

The value of flexibility for pulp mills investing in energy efficiency and future biorefinery concepts

Changing conditions in biomass and energy markets require the pulp and paper industry to improve energy efficiency and find new opportunities in biorefinery implementation. Considering the expected changes in the pulp mill environment and the variety of potential technology pathways, flexibility should be a strong advantage for pulp mills. In this context, flexibility is defined as the ability of the pulp mill to respond to changing conditions. The aim of this article is to show the potential value of flexibility in the planning of pulp mill energy and biorefinery projects and to demonstrate how this value can be incorporated into models for optimal strategic planning of such investments. The paper discusses the requirements on the optimization models in order to adequately capture the value of flexibility. It is suggested that key elements of the optimization model are multiple points in time where investment decisions can be made as well as multiple scenarios representing possible energy price changes over time. The use of a systematic optimization methodology that incorporates these model features is illustrated by a case study, which includes opportunities for district heating cooperation as well as for lignin extraction and valorization. A quantitative valuation of flexibility is provided for this case study. The study also demonstrates how optimal investment decisions for a pulp mill today are influenced by expected future changes in the markets for energy and bioproducts. Copyright © 2014 John Wiley & Sons, Ltd.     

Variables affecting energy efficiency and CO2 emissions in the steel industry

Specific energy consumption (SEC) is an energy efficiency indicator widely used in industry for measuring the energy efficiency of different processes. In this paper, the development of energy efficiency and CO₂ emissions of steelmaking is studied by analysing the energy data from a case mill. First, the specific energy consumption figures were calculated using different system boundaries, such as the process level, mill level and mill site level. Then, an energy efficiency index was developed to evaluate the development of the energy efficiency at the mill site. The effects of different production conditions on specific energy consumption and specific CO₂ emissions were studied by PLS analysis. As theory expects, the production rate of crude steel and the utilisation of recycled steel were shown to affect the development of energy efficiency at the mill site. This study shows that clearly defined system boundaries help to clarify the role of on-site energy conversion and make a difference between the final energy consumption and primary energy consumption of an industrial plant with its own energy production.     

Influence of moisture content and hammer mill screen size on the physical quality of barley,oat, canola and wheat straw briquettes

In order to determine the briquetting characteristics of biomass in a commercial setting, a hydraulic briquetter was used to study the compaction behavior of biomass grinds from barley, oat, canola and wheat straw. The selected straw samples were ground with a hammer mill using screen sizes of 19.05, 25.40 and 31.75 mm and conditioned to three moisture content levels of 0.09, 0.12 and 0.15 (w.b.). The residence time was about 6–10 min before being extruded from the briquetter. The specific energy, throughput, as well as the density, and durability of manufactured briquettes were measured during or after briquetting. The applied compression pressure at different parameter combinations ranged from 7 to 14 MPa. Higher pressure resulted at higher biomass moisture content. Hammer mill grinding of biomass with a large screen size (31.75 mm) resulted in high energy consumption and low throughput during briquetting. The increase in moisture content decreased the total energy consumption and increased the throughput of the briquetter. Briquette densities were of consistently higher value when biomass samples were compressed at a lower moisture level. The moisture content and hammer mill screen size indirectly influenced the briquette densities by affecting the pressure and residence time in commercial briquette production. Briquettes were successfully formed without adding a binder.     

Evaluation of energy efficiency in biofuel drying by means of energy and exergy analyses

The calculation of heat consumption is based on the First Law and it gives quantitative information about the energy used in drying. However, it does not pay any attention to the quality of the energy used in drying. To take into account the quality of the energy, attention must be paid to the Second Law, too. Especially in those cases where the energy used in drying may be converted to mechanical work, it is important to consider the Second Law is. In this paper, the energy efficiency of biofuel drying in a pulp and paper mill is evaluated on the basis of energy and exergy analysis. The evaluation is based on the determination of the heat consumption and the irreversibility rate for energy and exergy analysis, respectively. The evaluation methods are applied to two different drying systems, single-stage-drying with partial recycle of spent air, and multi-stage-drying. Both drying systems are also provided with a heat recovery unit in which the inlet air is pre-heated using the outlet air of the dryer. There are two alternative heat sources available for the drying energy, steam at a pressure of 3 bar and water at a temperature of 80 °C. The results show that the heat consumption is only dependent to a small extent on the heat source type or the drying system. On the other hand, the irreversibility rate depends to a considerable on the heat source and the drying system.