1、STP-PT-054CONCENTRATED SOLAR POWER (CSP) CODES AND STANDARDS GAP ANALYSISSTP-PT-054 CONCENTRATED SOLAR POWER (CSP) CODES AND STANDARDS GAP ANALYSIS Prepared by: Steve Torkildson, P.E. Consultant Date of Issuance: December 21, 2012 This report was prepared as an account of work sponsored by ASME Pres
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9、-0-7918-6866-9 Copyright 2012 by ASME Standards Technology, LLC All Rights Reserved Concentrated Solar Power Codes and Standards Gap Analysis STP-PT-054 iii TABLE OF CONTENTS Foreword v Abstract . vi 1 Introduction 1 2 System Descriptions. 3 2.1 Dish Systems . 3 2.2 Linear Systems 3 2.2.1 Linear Par
10、abolic Trough Systems 3 2.2.2 Linear Fresnel Systems 4 2.2.3 Linear System Heat Transfer 4 2.3 Power Towers 5 2.3.1 Power Tower Rankine Cycle Receiver. 5 2.3.2 Molten Salt Receiver 5 2.3.3 Power Tower Brayton Cycle Receiver . 6 3 Boiler and Pressure Vessel Code Issues and Gaps 8 3.1 Boiler Definitio
11、ns 8 3.1.1 Is a CSP heated device fired? . 8 3.1.2 Closed or Open Systems. 9 3.1.3 Review of State Boiler Definitions 9 3.2 Stirling Engine Receivers Gap Analysis . 13 3.3 Rankine Cycle Receiver Gap Analysis 14 3.4 Molten Salt CSP System Gap Analysis . 16 3.4.1 Molten Salt Gaseous Phase 18 3.5 Brayt
12、on Cycle Receiver Gap Analysis 18 4 Recommendations 21 4.1 Boiler Definition 21 4.2 Stirling Engine Systems 21 4.3 Rankine Cycle Tower Mounted 21 4.4 Rankine Cycle - Linear Receiver Systems (Troughs and Linear Fresnel Collectors) . 21 4.5 Molten Salt Receivers . 21 4.6 Brayton Cycle Receivers . 22 5
13、 The Future 23 5.1 ASME CSP Performance Test Code . 23 5.2 Other CSP Technologies . 23 References 24 Appendix A 25 Acknowledgements 28 Abbreviations and Acronyms . 29 STP-PT-054 Concentrated Solar Power Codes and Standards Gap Analysis iv LIST OF TABLES Table 1- State Boiler Definitions 10 Table 2 -
14、 Elements of State Boiler Definition . 11 Table 3 - Comparison of Arizona Definition to Solar Technologies 11 Table 4 - Comparison of California Definition to Solar Technologies . 11 Table 5 - Comparison of Colorado Definition to Solar Technologies 12 Table 6 - Comparison of Nevada Definition to Sol
15、ar Technologies . 12 Table 7 - Comparison of New Mexico Definition to Solar Technologies 12 Table 8 - Comparison of Utah Definition to Solar Technologies . 12 Table 9 - Solar Stirling Engine Risks and Mitigation . 14 Table 10 - CSP Rankine Cycle Boiler Risks and Mitigation 14 Table 11 - CSP Molten S
16、alt System Risks and Mitigation . 17 Table 12 - CSP Brayton Cycle Risks and Mitigation . 19 LIST OF FIGURES Figure 1 - Parabolic Dish With Stirling Engine 3 Figure 2 - Parabolic Trough Collector 4 Concentrated Solar Power Codes and Standards Gap Analysis STP-PT-054 v FOREWORD The report provides an
17、analysis of the ASME codes and standards that apply to Concentrated Solar Power (CSP) technologies to determine the gaps in the codes and standards and where there may be additional codes and standards work required to implement and commercialize CSP. Established in 1880, the American Society of Mec
18、hanical Engineers (ASME) is a professional not-for-profit organization with more than 127,000 members promoting the art, science and practice of mechanical and multidisciplinary engineering and allied sciences. ASME develops codes and standards that enhance public safety, and provides lifelong learn
19、ing and technical exchange opportunities benefiting the engineering and technology community. Visit www.asme.org for more information. The ASME Standards Technology, LLC (ASME ST-LLC) is a not-for-profit Limited Liability Company, with ASME as the sole member, formed in 2004 to carry out work relate
20、d to newly commercialized technology. The ASME ST-LLC mission includes meeting the needs of industry and government by providing new standards-related products and services, which advance the application of emerging and newly commercialized science and technology and providing the research and techn
21、ology development needed to establish and maintain the technical relevance of codes and standards. Visit www.stllc.asme.org for more information. STP-PT-054 Concentrated Solar Power Codes and Standards Gap Analysis vi ABSTRACT Numerous concentrated solar power (CSP) facilities have been in successfu
22、l commercial operation for the past 25 years. Recently, government incentives and advances in cost reduction have brought many new players into the field. An accelerated deployment of CSP is currently being seen worldwide. Many of the developing technologies in CSP have failure modes and effects dif
23、ferent from those treated by existing boiler and pressure vessel codes. This study is a gap analysis to identify differences between the safety regulation needs of emerging CSP technologies and existing ASME Boiler and Pressure Vessel codes (BPV). Six leading CSP technologies are examined. The safet
24、y related failure modes of these systems are identified and compared with existing Code rules to identify gaps in code coverage. Recommendations for actions to close these gaps are proposed. Concentrated Solar Power Codes and Standards Gap Analysis STP-PT-054 1 1 INTRODUCTION Concentrated solar powe
25、r (CSP) systems focus solar radiation collected from a large surface area to a smaller area to heat a medium to an elevated temperature. The collected heat is then used for process purposes or for the generation of electric power. A wide variety of heat transfer media are being explored for use in C
26、SP systems. These media include water, steam, heat transfer oils, air or other gases, and even solid particles. This study examines a select subset of six CSP technologies being developed today with the objective of identifying gaps between the technologies and current ASME Boiler and Pressure Vesse
27、l (BPV) Codes. This study is not a comprehensive review of the entire field of concentrated solar power. Because of the wide scope of active work in the field, only the most visible technologies are reviewed here. Although some of the advantages and disadvantages of the various systems are mentioned
28、 here, it is not the goal of this report to make any judgments about the economic viability of any of the systems. There are commercial plants that have been operating for as long as 25 years; nonetheless, this field is in its relative infancy. There are myriad researchers following a multitude of p
29、aths. The industry does not yet appear to be narrowing its technology choices. It would be premature at this point in time to try to sort the winners from the losers. The common elements in all CSP systems are the collector system and the receiver system. The collector system consists of the mirrors
30、, lenses, or other devices that focus and concentrate the solar radiation on the receiver. The receiver system is a heat exchanger that converts the focused solar radiation to another form of energy that can be used either for process heating or to generate electric power. This paper focuses on CSP
31、power generation. The CSP technologies reviewed for this study are: Dish systems Linear systems o Parabolic trough reflector systems o Linear Fresnel reflector systems Power towers o Direct steam (Rankine cycle) systems o Volumetric expansion (Brayton cycle) systems o Molten salt systems These three
32、 categories are based on the physical architecture of the collector systems. A wide variety of receiver systems are being explored by developers. Receiver systems can be generally be coupled with a variety of different collector systems which results in a large domain of collector/receiver pairings.
33、 Dish systems have a physical architecture employing a parabolic reflector, generally multi-faceted, as the collector. The receiver, located at the focal point of the reflector, is generally a reciprocating Stirling engine. There has been some research of dish systems employing a gas turbine as the
34、engine. Dish receiver systems that export a heated fluid are also possible. Linear systems consist of linear, fluid-filled receiver tubes running parallel to grade at a relatively low elevation. The collector system employs linear reflectors of parabolic shape or multi-element Fresnel arrangements i
35、n a common plane to focus sunlight on the receiver tubes. Thermal heat transfer fluids, air or molten salt can be heated in these systems. Some systems are generating steam that can directly power a turbine. STP-PT-054 Concentrated Solar Power Codes and Standards Gap Analysis 2 Power towers are poin
36、t focus systems that consist of a collector field of flat or slightly curved mirrors with two axis pointing systems that focus the solar radiation onto a receiver located on a tall central tower. The mirrors and their pointing drives are referred to as heliostats. The receivers in power tower system
37、s can be designed for direct steam generation, for expansion of air or gas, or to heat a mass storage medium such as molten salt. There have even been experimental systems tested that heat a fluidized curtain of falling solid pellets or spheres which could be stored for subsequent extraction of heat
38、 for process or power generation purposes. Each of these systems is described more specifically in Section 2. The major components and their relationships are explained with emphasis placed on identifying system components that contain pressure or provide a heat transfer function. It is these compon
39、ents that may fall under BPV jurisdiction. Section 3 examines the BPV Code issues related to each system. First, the code section having the system within its scope is identified. This exercise is not trivial as the definition of a boiler varies between jurisdictions. Some jurisdictions classify all
40、 of these CSP systems as boilers while others classify none of them as boilers. The confusion in definitions is largely because current regulations were written before the advent of current CSP technologies. Section 3 then examines the safety related failure mechanisms of the systems. For each failu
41、re mechanism, two questions are posed: 1. Are these failure mechanisms adequately covered by present codes? (i.e., what are the code gaps?) 2. Are there BPV Code requirements imposed on the system that serve no safety related purpose? Section 4 provides provisional suggestions of future BPV code dev
42、elopment initiatives. Some judgment will be needed to choose which of the suggestions to pursue. At this time, a wide variety of technologies are being pursued. The industry has not settled on a favored or best technology yet. Some of the technologies may not prove to be economically viable and will
43、 fall out of the marketplace; developing rules to address these systems may waste limited code committee resources. However, the number of gaps between the industrys needs and the BPV codes is small, so the burden of addressing the gaps is not great. Section 5 touches on the future in the developmen
44、t of PTC technologies. The ASME PTC 52 committee is developing a performance test code for concentrated solar thermal power systems. Among the technologies that will be covered by this code are linear Fresnel collectors, parabolic troughs, power towers, and thermal storage. The committee members wer
45、e drawn from various countries and interest areas. Concentrated Solar Power Codes and Standards Gap Analysis STP-PT-054 3 2 SYSTEM DESCRIPTIONS 2.1 Dish Systems Figure 1 illustrates a typical dish system collector. The parabolic shaped dish can consist of a single reflector element of an array of sm
46、aller reflectors lying on a parabolic surface. The dish tracks the sun by means of a two-axis drive. Dish collectors are generally used to power an engine mounted at the reflector focal point. Stirling engines and gas turbines are being explored as receivers for dish collectors. Many dish systems cu
47、rrently being explored have collector diameters of about 10 m (33 ft.). Larger collector areas are possible, but wind loads and drive actuator costs increase with dish size. The modern Stirling engines employed in dish systems operate at pressures as high as 20 MPa (2900 psi) and gas temperatures ov
48、er 700C (1292F). The preferred working fluid is hydrogen gas. A Stirling engine sized for a 10 m dish is about the size of an automotive engine, although it has a lower power density. The Stirling engine may include a regenerator to increase efficiency. It also has a heat exchanger for removing heat
49、 from the cooling chamber. Pressure parts in a Stirling engine include the cylinder(s), connecting passages or piping, and heat exchanges used to either receive or reject heat. Although most dish collector systems being commercialized use Stirling engines, other types of receivers such as gas turbines are possible. There are a number of demonstration Stirling engine dish systems, but no large scale plants have been built yet. 2.2 Linear Systems Linear systems employ ground mounted reflectors that focus radiation on an elevated horizontal tube at the focal point of the reflector.
