Heliostats 101

1、eSolar公司此前在solarpaces2013大會(huì)上發(fā)布了其新型模塊化熔鹽型塔式光熱發(fā)電站的設(shè)計(jì)，CSPPLAZA記者日前獲得了關(guān)于該設(shè)計(jì)更詳細(xì)的相關(guān)信息。單個(gè)模塊熱功率變?yōu)?0MWteSolar此前的電站設(shè)計(jì)單個(gè)模塊為2.5MW發(fā)電功率，其在加州Lancaster建設(shè)的5MW示范電站即由兩個(gè)獨(dú)立的2.5MW塔式熱發(fā)電模塊組成。新的設(shè)計(jì)改變了其集熱功率，升至50MWt。集熱場(chǎng)設(shè)計(jì)重新調(diào)整eSolar此前的鏡場(chǎng)設(shè)計(jì)為長(zhǎng)方形設(shè)計(jì)，兩個(gè)長(zhǎng)方形布置的鏡場(chǎng)中間放置集熱塔，單個(gè)發(fā)電模塊的鏡場(chǎng)面積約28000平方米。新的鏡場(chǎng)設(shè)計(jì)采用了一種六邊形的結(jié)構(gòu)，四個(gè)子鏡場(chǎng)圍繞一個(gè)集熱塔布置。反射鏡尺寸也隨之增加，

2、此前的反射鏡尺寸為1.136平方米，新的設(shè)計(jì)采用了2.2平方米的反射鏡，單個(gè)集熱模塊共配裝47000面定日鏡，使得單個(gè)六邊形鏡場(chǎng)的集熱面積大幅增加至103000平方米，集熱塔高100米，比此前的55米的集熱塔高度也有大幅增加。增加儲(chǔ)熱系統(tǒng)此前eSolar采用水工質(zhì)方案，新的設(shè)計(jì)采用了熔鹽傳熱儲(chǔ)熱的技術(shù)方案。使電站的容量因子由之前的25%獲得大幅提升。以組建一個(gè)凈發(fā)電功率100MW，配置13個(gè)小時(shí)儲(chǔ)熱的塔式電站計(jì)算，需要大約14個(gè)集熱模塊，容量因子可達(dá)75%（空冷）或78%（水冷）。如果配置6小時(shí)儲(chǔ)熱，則僅需要10個(gè)集熱模塊，容量因子約為50%。通過(guò)管道聯(lián)接將各個(gè)集熱場(chǎng)的熱量匯集至儲(chǔ)熱換熱單元，

3、以100MW配13小時(shí)儲(chǔ)熱的電站裝機(jī)計(jì)算，預(yù)計(jì)冷熔鹽的流通管道的長(zhǎng)度在10500米，熱熔鹽的流通管道的長(zhǎng)度在17400米，為最大程度地降低熔鹽對(duì)管道的腐蝕但不過(guò)多地增加成本，冷熔鹽管道采用碳鋼材質(zhì)，熱熔鹽管道則采用不銹鋼。所有管道均安裝熱追蹤設(shè)備，采取多種保溫措施，實(shí)現(xiàn)完全疏水。以100MW裝機(jī)的配置13小時(shí)儲(chǔ)熱的電站計(jì)算，需求的總儲(chǔ)熱能力在3500MWht左右，需要36500噸熔鹽。據(jù)此設(shè)計(jì)的熔鹽罐的尺寸為直徑39米，高17.5米。吸熱器的變化加州Lancaster的5MW示范電站采用了兩家公司生產(chǎn)的不同的吸熱器，分別為Babcock&Wilcoxgs公司生產(chǎn)的外置式吸熱器和VictoryE

4、nergy公司生產(chǎn)的雙向腔式吸熱器。此次新的電站設(shè)計(jì)則由eSolar和B&W公司合作，將采用B&W為其新設(shè)計(jì)的熔鹽吸熱器，依然為外置式，外形結(jié)構(gòu)與此前的設(shè)計(jì)基本相似。eSolar宣稱(chēng)，此款吸熱器在工廠實(shí)現(xiàn)完全整裝，減少了在項(xiàng)目現(xiàn)場(chǎng)的組裝程序，更易實(shí)現(xiàn)快速安裝。吸熱器采用垂直管板和蛇型管線設(shè)計(jì)，具備30秒內(nèi)的完全疏水能力，可實(shí)現(xiàn)快速啟動(dòng)。Heliostats 101The heliostat is the basic building block of the Solar Collector System (SCS). In our system, a heliostat consists of

5、 three main components: The drive The drive houses two motors enabling our heliostat to move in two axes. The control software provides commands to the drive to use the motors to track the sun very accurately as it moves through the sky. The reflector module-The reflector module consists of the mirr

6、ored glass and metal frame that can be easily attached to the drive so it can be accurately controlled. The structure The structure provides a rigid, sturdy anchor for the heliostat to the ground.Small Size, High Volume ApproachAll of the heliostat components are designed to take advantage of high v

7、olume manufacturing techniques proven in industries such as automotive manufacturing. This enables both a cost effective design as well as rapid production and deployment of hardware. The drive is almost completely composed of aluminum die cast, sintered powdered metal, and injection molded plastic

8、components. Final assembly is performed on a streamlined, dedicated line that includes an automated end of line test. The reflector module utilizes roll formed steel components, robotic welding, and a fully automated, robotic final assembly which ensures high quality and repeatability. Automated end

9、 of line tests evaluate the shape of the reflector using proprietary software based image analysis. The structure also takes advantage of roll formed steel components and robotic welding as well as progressive dies stamping. The optimized triangular truss structure offers a greater stiffness with le

10、ss steel consumed.History in the MakingFrom eSolars first heliostat in 2007, the design has come a long way! Quality and performance information from field testing and commercial plant installations has been leveraged to create a high value product. Additionally, advanced system modeling has led to

11、optimization of heliostat size and packing density.A comparison of eSolars last heliostat design to its current one shows improvements in manufacturability and cost, as well as some optimization to its size and shape.Patented CalibrationA figure from one of our many patents in heliostat calibration

12、and controlTo direct sunlight (referred to as flux in the CSP industry)at a target hundreds of meters away, we have to know the position of the sun, the position of the tower and the position of the actuated mirror, or heliostat, to great precision.There can be hundreds of thousands of heliostats at

13、 a single plant and accounting for each one is a significant challenge. Our competitors have avoided this challenge by deploying fewer, larger, and more expensive heliostats which are difficult to install and monitor.Our control software, Spectra, accepts the challenge head-on, massively parallelizi

14、ng the problem, and using novel,patentedalgorithms to identify each heliostat as it is installed, and to prepare each heliostat for tracking by calibrating it to milliradian accuracy.Precise ControlUsing our control system to celebrate the 4th of July at Sierra.Thats right: our control system points

15、 our heliostats with milliradian accuracy. For example, a 2m-wide beam of light is being directed to a point on a thermal receiver absorber panel 300m away. We need less than 1/10th of a degree of accuracy if we dont want to spill our light off of the receiver. And we do it. With such fine individua

16、l heliostat control, we can create intricate flux distributions on our thermal receivers allowing for a wide variety of applications. We can control for superheat, salt temperature, peak flux or delivered power, ourpatentedthrottling algorithm gives us the unprecedented precision we need to respond

17、to the necessary environmental and plant conditions.Large-Scale OptimizationThe techniques for our high performance in the field required many years worth of research, experimentation, and testing vialarge-scale simulation and optimization. We optimize everything: heliostat range of motion, thermal

18、losses, receiver aim-point selection, control group selection, and which heliostats to use at every minute of every day in every plant around the world. Our models of instantaneous and annual performance have been validated time and time again, giving us the confidence (and the tools) to move forwar

19、d with project bidding, winning, and construction.Our SCS5 heliostat performing a pointing test.eSolars Field Layout is FlexibleeSolars solar field includes the heliostats and all of the systems required to use them to deliver flux (heat from the sun) to a receiver. This flux can be used on a pre-qu

20、alified steam or molten salt receiver built by eSolar partner Babcock & Wilcox or a customer selected receiver. eSolars Applications Engineering team can also work with customers to deliver flux to receivers for other applications (such asEORordesalination).Dispatchable Power Reference PlantseSolar won a grant from the United States Department of Energy to develop a reference design for a dispatchable baseload power plant. The result was an optimized molten salt power plant designed for rapid deployment and capable of producing power hours after the sun goes down. Because