生物质混烧方案的减排和燃煤发电厂的发电成本

1、Biomass co-firing options on the emission reduction and electricity generation costs in coal-fired power plants生物质混烧方案的减排和燃煤发电厂的发电成本AbstractCo-firing offers a near-term solution for reducing CO2 emissions from conventional fossil fuel power plants. 混烧提供了减少传统化石燃料发电厂二氧化碳排放量的短期解决方案。Viable alternatives

2、to long-term CO2 reduction technologies such as CO2 sequestration, oxy-firing and carbon loop combustion are being discussed, but all of them remain in the early to mid stages of development. Co-firing, 可行的替代了长期的二氧化碳减排技术，如二氧化碳封存，氧燃烧和碳循环燃烧正在讨论之中，但他们都只停留在早期到中期的发展阶段。on the other hand, is a well-proven

3、technology and is in regular use though does not eliminate CO2 emissions entirely.另一方面，混烧是一个久经考验的技术，虽然没有完全消除二氧化碳排放，但是这种技术经常被使用。An incremental gain in CO2 reduction can be achieved by immediate implementation of biomass co-firing in nearly all coal-fired power plants with minimum modifications and mo

4、derate investment, making co-firing a near-term solution for the greenhouse gas emission problem.在几乎所有的最低修改和适度投资的燃煤电厂，二氧化碳减排量的增益可以通过 生物质混烧立即见效，这使得混烧成了温室气体排放问题的短期解决方案。If a majority of coal-fired boilers operating around the world adopt co-firing systems, the total reduction in CO2 emissions would be

5、substantial. 如果世界各地大多数锅炉燃烧运行都采取混烧系统，二氧化碳减排量将是巨大的。It is the most efficient means of power generation from biomass, and it thus offers CO2 avoidance cost lower than that for CO2 sequestration from existing power plants.它是从生物质方面考虑发电的最有效手段，而这也意味着二氧化碳避免成本低于现有的发电厂的二氧化碳封存。The present analysis examines seve

6、ral co-firing options including a novel option external (indirect) firing usingcombustion or gasification in an existing coal or oil fired plant.目前的分析研究检查了几个混烧操作，包括一个新的选择那就是在现有的燃煤或 石油发电厂采用燃烧或气化的方法在外部(问接)燃。Capital and operating costs of such external units are calculated to determine the return on in

7、vestment.这些外部单元的资本及营运费用需要计算出来，以确定它的投资回报。Two of these indirect co-firing options are analyzed along with the option of direct co-firing of biomass in pulverizing mills to compare their operational merits and cost advantages with the gasification option.在粉碎厂，其中两个间接混烧选项和直接混燃生物质共同分析以便于比较与选择 气化选项的业务优点和成本

8、优势。1. IntroductionLiving biomass plants absorb CO2 from the atmosphere.活体生物质植物吸收大气中的二氧化碳。So, its combustion/gasification for energy production is considered carbon neutral.因此，其能源生产过程中的燃烧、气化被认为是碳中立。Thus if a certain amount of biomass is fired in an existing fossil (coal, coke or oil) fuel fired plant

9、 generating some energy, the plant could reduce firing the corresponding amount of fossil fuel in it.因此，如果一定量的生物质在现有的化石(煤，焦炭或石油)燃料燃烧发电厂产 生能量，工厂就可以减少燃烧它的化石燃料的相应数额。Thus, a power plant with integrated biomass co-firing has a lower net CO2 contribution over conventional coal-fired plants.因此，拥有集成的生物质混烧电厂

10、比传统的燃煤发电厂具有较低净CO酌贡献。Biomass co-firing is one technology that can be implemented immediately in nearly all coal-fired power plants in a relatively short period of time and without the need for huge investments.生物质混烧是一种可以实现在几乎所有燃煤电厂中立即在较短的时间内应用，无需进行大量投资的技术。It has thus evolved to be a near-term alterna

11、tive to reducing the environmental impact of electricity generation from coal.它由此演变为一个短期的替代，以减少燃煤发电对环境的影响。Biomass co-firing offers the least cost among the several technologies/ options available for greenhouse gas reduction 生物质混烧技术为温室气体减排提供多种技术方案之间的最低成本。7. Principally, co-firing operations are not

12、implemented to save energy but to reduce cost, and greenhouse gas emissions (in some cases).原则上，混烧操作没有实现节约能源，而是降低成本以及温室气体排放量 (在某 些情况下)。In a typical co-firing plant, the boiler energy usage will be the same as it is operated at the same steam load conditions (for heating or power generation), with th

13、e same heat input as that in the existing coal-fired plant.在典型的混烧电厂，锅炉能源使用量将是相同的，因为它是在同一蒸汽负荷条件 (加热或发电)下操作的，与现有燃煤电厂投入相同的热量。The primary savings from co-firing result from reduced fuel costs when the cost of biomass fuel is lower than that of fossil fuel, and avoiding landfill tipping fees or other cos

14、ts that would otherwise be required to dispose of unwanted biomass. 从降低燃料成本节省效果来看，生物质燃料成本低于矿物燃料，避免了垃圾倾倒 费，不需要处理有害生物的其他费用。Biomass fuel at prices 20% or more below the coal prices would usually provide the cost savings needed.生物质燃料低于煤炭价格20%或以上，这些通常会提供所需的成本节约。Apart from direct savings in fuel cost, oth

15、er financial benefits that can beexpected from co-firing include the following:除了直接节省燃料成本，其它混烧方面可以预期的经济利益包括以下内容：Various pollution-reduction incentives各种污染减排奖励办法：As co-firing, through synergetic effects, reduces the net SOx, NOx and heavy metal emissions, the plant could claim the applicable pollutio

16、nreduction incentives offered by government agencies.由于混烧，通过协同效应降低了净硫氧化物、氮氧化物和重金属的排放，工厂就可以要求政府机构提供污染减排的奖励。Financial incentives for plant greenhouse gas (GHG) emission reduction:植物温室气体(GHG减排的财政奖励：A co-firing plant that uses biomass to replace an amount of coal in an existing boiler will reduce almost

17、 an equal amount of net CO2 emission from the plant.一个在现有锅炉中使用生物质以减少耗煤量的混烧电厂将减少几乎等同于植物 放出的二氧化碳净排放量。 On-demand power production:按需发电：Unlike other renewable energy technologies (e.g.: solar, wind), biomass-based power generation can be made available whenever it is needed. This helps to accelerate the

18、 capital investment payoff rate by utilizing a higher capacity factor.不同于其他可再生能源技术(如：太阳能，风能)，以生物质为基础的发电 可在必要时提供。这有助于通过利用更高的容量因子促进资本投资回报率。An option towards meeting a renewable energy portfolio: 一个寻求可再生能源投资组合的选择：Cofiringoffers a fast track, low-cost opportunity to add renewableenergy capacity economic

19、ally as it can be added to any coalfiredplant immediately, with minimum investment.混烧为增加可再生能源经济经济性的能力提供了一个快速、低成本的机会，因为 它可以立即用最小的投资添加到任何燃煤电厂。Earning of renewable energy tax credits:可再生能源税收抵免的收益：The use of biomass asan energy source to displace fossil fuel can be eligible forspecial tax credits from m

20、any governments.生物质作为能源来取代化石燃料可以有资格申请许多国家政府特殊的税收抵免。Fuel flexibility: 燃料弹性：Biomass as a fuel provides a hedge against priceincreases and supply shortages of coal ore生物质作为燃料提供了对煤炭价格上涨和铁矿石供应短缺的对冲。In co-firing, biomasscan be viewed as an opportunity fuel, used only when the priceis favorable在混烧中，生物质可以被看

21、作是一个机会燃料，仅在价格优惠时使用。biomass fuels are generally sourced from the areas in theimmediate vicinity of the plant (to save on transportationcosts), the local communities benefit economically from theproduction of biomass fuels.当地社区的经济和环境效益：生物质燃料来源的地区，一般从工厂附近(以 节省运输费用)，当地社区受益于生物质燃料的生产。Co-firing options?昆烧的

22、选择Biomass co-firing has been successfully demonstrated in over 150 installations worldwide for a combination of fuels and boiler types 9.生物质混烧已在全球范围内安装的150个燃料和锅炉类型的组合成功证明。The co-firing technologies employed in these units may be broadly classified under three types:混烧技术大致可分为以下三种类型：Direct co-firing,直

23、接混烧indirect co-firing,间接混烧gasification co-firing.气化混烧In all three options, the use of biomass displaces an equivalent amount of coal(on an energy basis), and hence results in the direct reduction of CO2 and NOxemissions to the atmosphere.在所有这三个选项，利用生物质能取代等量的煤(以能源计算)，因此可以减少 二氧化碳和氮氧化物直接排向大气的排放量。The se

24、lection of the appropriate co-firing option dependson a number of fuel and site specific factors.在适当的混烧方案的选择取决于燃料和特定地点因素。The objective of this analysis is to determine and compare the economics of the different co-firing options.本分析的目的是确定和比较不同混烧方案选择的经济 效益。Brief descriptions of the three co-firing op

25、tions are presented here.三混烧选项的简要说明也列在了这里。Direct co-firing 直接混烧Direct co-firing involves feeding biomass into coal going into the mills, that pulverize the biomass along with coal in the same mill.直接混烧生物质被送到轧机里去，和煤一块儿被研磨。Sometime separatemills may be used or biomass is injected directly into the boi

26、ler furnace through the coal burners, or in a separate system.有时单独的轧机可用于生物质直接注入锅炉炉内通过燃烧器，或在一个单独的系统。The level of integration into the existing plant depends principally on the biomass fuel characteristics被现有的电厂所融入的水平主要取决于生物质燃料的 特性。Four different options are available to incorporate biomass cofiring i

27、n pulverized coal power plants10.四个不同的方案可纳入生物质混烧的煤粉发电厂。In the first option, the pre-processed biomass is mixed with coal upstream of the existing coal feeders在第一个方案，预加工的生物质与现有的给煤机上游的煤混 合。The fuel mixture is fed into the existing coal mills that pulverize coal and biomass together, and distribute it

28、across the existing coal burners, based on therequired co-firing rate.该燃料混合物被送入现有磨煤机煤和生物质一起被粉碎，以它所需的混烧率来分散到现有的煤炭燃烧器。This is the simplest option, involving the lowest least capital costs, but has a highest risk of interference with the coal firing capability of the boiler unit.这是最简单的选择，至少涉及的资金成本最低，但单

29、位燃煤锅炉被干扰的风险最 离 问0Alkali or other agglomeration/corrosion-causing agents in the biomass can build-up on heating surfaces of the boiler reducing output and operational tim11. 生物质的碱或其他腐蚀物造成的生物制剂可能积聚在锅炉受热面，使输出和作业时间减少。Furthermore, different combustion characteristics of coal and biomass may affect the st

30、ability and heat transfer characteristics of the flame12. 此外，煤和生物质燃烧特性的不同会影响火焰的稳定性和热传递特性。Thus, this direct co-firing option is applicable to a limited range of biomass types and at very low biomass-to-coal co-firing ratios。 因止匕， 这种直接混烧方案适 用于范围有限的生物质类型和比率非常低的生物质到煤混烧。The second option involves separat

31、ehandling, metering, and pulverization of the biomass, but injection of the pulverized biomass into the existing pulverized fuel pipe-work upstream of the burners or at the burner第二个方案涉及不同的处理，测量和粉碎的生物量，但煤粉生物质的注射是在现有煤粉燃料燃烧器管道的上游或 在燃烧器。This option requires only modifications external to the boiler.这个方

32、案只需要改善 锅炉外部。One disadvantage would be the requirement of additional equipment around the boiler, which may already be congested.一个缺点是要求围绕已经出现挤塞情况的 锅炉增加设备。It may also be difficult to control and to maintain the burner operating characteristics over the normal boiler load curve另一个难点是难以在正常锅炉负荷曲线下控制和 维燃

33、烧器的工作的特点。The third option involves the separate handling and pulverization of the biomass fuel with combustion through a number of burners located in the lower furnace, dedicated to the burning of the biomass alone 第三个方案涉及单独处理和 生物质燃料在炉膛下部的燃烧器的燃烧，致力于生物质单独燃烧。This demands a highest capital cost, but in

34、volves the least risk to normal boiler operation as the burners are specifically designed for biomass burning and would not interfere with the coal burners.这要求最高的资本成本，但涉及锅炉正常运作的风险最小，因为燃烧器是专门为生物质燃烧设计的，也不会干预煤炭燃烧器。The final option involves the use of biomass as a reburn fuel for NOx emission control.最终

35、的方案涉及生物质作为控制氮氧化物的排放的再燃燃料的使用。This option involves separate biomass handling and pulverization, with installation of separate biomass fired burners at the exit of the furnace. 这个方案涉 及在炉膛出口安装生物质燃烧器时的生物质单独处理和粉碎。As with the previous option, the capital cost is high, but risk to boiler operation is minima

36、l. 0与前面的方案相比，资金成本高，但锅炉运行的风险是最小的。Indirect or external co-firing混烧（外部混烧）Indirect co-firing involves the installation of a completely separate biomass boiler to produce low-grade steam for utilization in the coal-fired power plant prior to being upgraded, resulting in higher conversion efficiencies.间接混

37、烧涉及一个完全 独立的生物质锅炉的安装，以在燃煤电厂升级之前生产低品位蒸汽以供利用这导 致更高的转换效率。An example of this option is the Avedore Unit 2 project in Copenhagen, Denmark这个方案的一个例子是Avedore2号机组在丹麦首都哥本哈根的项目。In Canada, Greenfield Research Inc. has developed a similar CFB boiler design that utilizes a number of units of the existing power pla

38、nt systems like ID fan etc. to reduce the capital cost.在加拿大，Greenfield研究公司开发了一种类似的循环流 化床锅炉的设计，它利用了现有的动力，像引风机等设备，来减少成本投资。In this system, a subcompact circulating fluidized bed boiler is designed specifically to have a piggy-back ride on an existing power plant boiler. 在这个系统 中，特别为现有的背驮式运行的电站锅炉设计一个微型循环

39、流化床锅炉。Since it is not a stand-alone boiler it does not need many of the equipment orcomponent of a separate boile的于它不是一个独立的锅炉，所有它并不需要独立 锅炉所需的设备或组件。This unit releases flue gas at relatively high temperature and joins the existing flow stream of the parent coal-fired boiler after air heater.本装置在相对较高的温

40、度 下释放烟气并在空预器之后将燃煤锅炉中的流动蒸汽流汇集。Thus, the flue gas from the co-firing unit does not come in contact with any heating elements of the existing boiler, thus avoiding the biomass related fouling or corrosion problem, which is the largest concern of biomass cofiring因止匕，混烧单元 烟气不会接触任何的现有锅炉加热元件，从而避免了污染或腐蚀的相关问

41、题，这是生物质混烧中最受关注的问题。This boiler is totally independent of the parent unit, and as such, any outage in the co-firing unit does not affect the generation of the parent plant.这种锅炉是完全 独立于母单元的，并因此任何混烧单元故障不会影响上级工厂。Thus this indirect combustion-based option offers high reliability.因止匕， 这种以 间接燃烧为基础的方案可靠性很高。Th

42、e piggy-back boiler produces low pressure steam feeding into the process steam header of the power plant.背 驮式锅炉产生低压蒸汽在进入电 厂前补充过程蒸汽。Fig. 1 shows the photograph of one such unit built by Greenfield Research Inc., for a 220MWe Pulverized coal-fired boiler in India. 图1显示了一个Greenfield研究公 司在印度建立的有这种单元建造 的

43、 220MWei 粉 锅炉。In this specific case, the piggy-back boiler fired waste fuel from the parent boiler as that was the need of theplan。在此特定情况下，背驮式锅炉根据电厂的需要，燃烧从上级锅炉提取的废料。Gasification co-firing 气化混烧Co-firing through gasification involves the gasification of solid biomass and combustion of the product fuel

44、 gas in the furnace of the coal-fired boiler.气化混烧包 括固体生物质和气体燃料燃烧产物中的燃煤锅炉炉膛气化。This approach offers a high degree of fuel flexibility.。这种方法提供了燃料高 度的灵活性。Since the gas can be injected directly into the furnace for burning, the plant can avoid expensive flue gas cleaning as one would need for syngas or f

45、uel gas for diesel engines由于气体可以被注入了直接焚烧炉，该工厂为一体，可避免昂贵的烟气 净化将需要合成气或柴油发动机的燃料气体。As the enthalpy of the product gas is retained, this results in a very high energy conversion efficiency.因为产品气始被保留，这使得能量转化效率很高。If the biomass contains highly corrosive elements like chlorine, alkali etc., a certain amount

46、of gas cleaning may be needed prior to its combustion in the furnace.Another important benefit of injection of gas in the furnace is that it serves as a gas-over firing designed to minimize NOx.如果生物质含有高腐蚀性元素如氯， 碱等，可能其在炉内燃烧之前需要一定量的清洁气体。炉内注气的另一个好处是，它作为一中气体，在设计时减少氮氧化物的排放。Although less popular, indirect

47、 or external and gasification cofiring options have certain advantages,such as the possibility to use a wide range of fuels and easy removal of ash虽然不太受欢迎的，间接的或外部和气化混烧选项有一定的优势， 比如燃料适用范围广，方便除灰。Despite the significantly higher capital investment requirement, these advantages make these two options mor

48、e attractive to utility companies in some cases. 尽管资本投资较高，但在有些公用事业公司中，这些优势使得这两个方案更具吸 引力。Case study methodolo璇例研究方法The present analysis of co-firing options considers only the economic and emissive effects of co-firing biomass within the plant facility and does not include changes in fuel transportat

49、ion requirements.前混烧方案的分析只考虑了生物质混 烧在电厂的经济效益和效率，并不包括燃料的运输。In North America, many local sources of biomass are available, and the use of a locally available source of biomass could have benefits beyond those discussed in this paper, in terms of reduced costs and emission generated from transportation

50、of fuel. 在北美，当地有许多的生物质资源，这些当地生物质资源的利用使得在资本投资 和运输过程的污染物减排等很多方面受益而不仅仅是以上在纸面上讨论的这些。In areas where the supply of high quality biomass is limited transportation of biomass to the plant would likely be an important part of the economic and environmental costs.在高品质生物质有限的地区，生物质的运输很可能会在是经 济和环境投资方面着重考虑的。The a

51、mount of fuel replacement with biomass is generally very low in co-firing because especially in direct firing, the boiler furnace designed for a specific fossil fuel may not respond favorably as there is a major departure in combustion and flame radiation characteristics when some other fuels in use

52、dM 烧时被生物质所代替的燃 料数量通常非常少，尤其是在直接混烧时，因为锅炉是为化石然料特别设计的， 可能不适应其他燃料的燃烧特点。If co-firing is applied to a fluidized bed boiler, this limit may not be that stringent.如果混烧被应用于流化床锅炉，那么这些限制并不是那么明显。The present economic analysis is based on a 150 MW pulverized coal plant located in Eastern Canada.目前的经济性分析是基于对位于加拿大东部

53、的 150兆瓦 煤粉电厂的研究。As such, only 10% biomass co-firing rate is considered in all the three different co-firing options examined here像这样，在以上三种混烧方案中只考虑 10%勺生物 质混烧比率。Engineering design of the indirect co-firing system, its capital cost estimation, including fuel requirements for all three options, was car

54、ried out through a computer-based analysis11接混烧系统的工程设计的资本投资评估，包括所有三种 方案的燃料需求，都是通过计算机分析的。Table 1 lists the inputs of the thermodynamic design.表歹U 出了 热力设计的投 入。T her mod yn mic| de sig n inputs.Input 陋r TOC o 1-5 h z Plant genrauon (MWJ150Biomass energy fractionIDPlant heat rate (kJfkWTi)10326Qpia-dtV

55、factor (%)soTurbine 囱Tiden中(XJThe properties of the biomass fuel used in the analysis were taken as that of the hardwood maple在特性分析中，生物质燃料被当做硬枫木。Hardwood species are widely available in Eastern Canada and are often discarded when harvesting of softwood trees for the pulp and paper industry takes pla

56、ce, making hardwood very cost effective力口拿大的东部有许多的硬木物种，而 且通常因为不盛产软木而被纸浆业和造纸业所忽视，使得使用硬木的经济效益很 好。.For coal, a low ash bituminous type coal was considered, typical of the fuel type used in the specific pulverized coal boilers对于煤炭，低灰分沥青型煤是煤粉锅炉 使用的燃料类型的典型。presents the results of the ultimate analysis of

57、coal and biomass.表二列出了煤和生物质的最终分析结果。For all three co-firing options, theenergy input remains the same, and was determined using the overall plant generation and heat rate:对所有这三个方案，输入的能量保持不变，取决于全厂的发电和热 效率Qplint =where, Qplant is the plant heat input (MJ), Pplant is plant electrical generation (MWh) an

58、d HRplant is the plant heat rate (MJ/MWh).这里 Qplant 指的是电厂输入热量， Pplant指的是发电量，Hrplant指的是电厂热耗率。The heat input required from the biomass was calculated at 10% of the overall heat required by the plant由生物质提供的热量输入占总热量输入的10%The amount of coal that would be offset through the co-firing of biomass, in a year

59、, was found through the following equation:煤的数量通过生物质混烧会发生变 化，一年之内的偏移量可以用下面的公式：苗 x 3600 x 24x 365 x CF(2)HHVcojiwhere, mco is the mass of coal offset by co-firing (tons/year), fbf is the biomass co-firing fraction, HHVcoal is the higher heating value of coal (MJ/ton), and CF is the plant capacity fac

60、tor.这里，Mco旨的是混烧造成的煤量偏移，Fbf指的是生物质混 烧比例，HHVcoaF旨的是煤的高品位发热量，CF旨的是电厂容量因素。The capacity factor specifies as to what extent the installed capacity of the plant is utilized, either for technical reasons, or for operational reason矫量因子指定为任何 程度上的被利用装机容量，无论是技术原因还是操作原因。Technical reasons, leading to technical ava