This document specifies the general technical requirements for materials, design, manufacturing and inspection, safety accessories and instrumentation, and installation and operation of supercritical carbon dioxide boilers (hereinafter referred to as "boilers").
This document applies to boilers that use supercritical carbon dioxide as the working fluid, with a rated outlet working fluid temperature of 500℃ or higher, a rated outlet working pressure of 14MPa or higher, and a single-unit output of 50MW or less.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GBZ 1 Hygienic standards for the design of industrial enterprises
GBZ 2.1 Occupational exposure limits for hazardous agents in the workplace - Part 1: Chemical hazardous agents
GBZ/T 223 Specification of setting monitoring and alarming devices for toxic gas in the workplace
GB/T 2900.48 Electrotechnical terminology of boilers
GB/T 8174 Method of measuring and evaluation thermal insulation effects for equipments and pipes
GB 13223 Emission standard of air pollutants for thermal power plants
GB 13271 Emission standard of air pollutants for boiler
GB/T 16507 (All parts) Water-tube boilers
GB/T 17357 In-situ measurements of heat loss through thermal insulation of equipments and pipes - Heat flow meter apparatus and surface temperature method
GB/T 22395 Specification for design of boiler steel structures
GB/T 23938 High purity carbon dioxide
GB/T 34348 Specification for utility boiler system
DL/T 435 Code for the prevention of furnace explosions/implosions in power plant boilers
NB/T 10939 Rules for receiving acceptance of materials for boiler construction
NB/T 47043 Technical specification for manufacture of boiler steel structures
NB/T 47049 Technical specification for the manufacture of tubular air preheaters
NB/T 47055 Painting and packing specification of boiler
NB/T 47060 The rotary air preheater
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 2900.48 and the following apply.
3.1
supercritical carbon dioxide
carbon dioxide with a pressure greater than 7.38MPa and a temperature greater than 31.1℃
3.2
brayton cycle
a thermodynamic cycle in which a gas serves as the working fluid, undergoing four processes, i.e., adiabatic compression, isobaric heat absorption, adiabatic expansion, and isobaric cooling, in sequence
3.3
supercritical carbon dioxide boiler
boiler that uses supercritical carbon dioxide as the working fluid
3.4
feed gas
carbon dioxide gas that meets certain quality requirements and is input into the boiler
3.5
main gas
carbon dioxide gas that enters the high-pressure turbine to perform work after the feed gas has been heated in the boiler
3.6
reheat gas
carbon dioxide gas that enters the low-pressure turbine to perform work after the exhaust gas from the high-pressure turbine has been reheated in the boiler
3.7
gas-cooled wall
radiant heating surface laid around the boiler furnace, using carbon dioxide gas as the cooling fluid
3.8
shunt economizer
convective heating surface that utilizes a portion of the carbon dioxide gas diverted from the feed gas to absorb heat from the furnace exhaust gas, thereby reducing the exhaust gas temperature
4 Definition of boiler range
4.1 Boiler range
A typical flowchart of a supercritical carbon dioxide brayton-cycle power generation system is shown in Figure 1. The boiler range includes the boiler proper, piping within the boiler range, safety accessories, and instrumentation.
Figure 1 Typical flowchart of a supercritical carbon dioxide brayton-cycle power generation system
4.2 Boiler proper
The boiler proper refers to the integral assembly comprising heating surfaces, headers and their connecting piping, furnace, combustion equipment, air preheater, boiler setting, flue (air) ducts, structure (including platforms and ladders), etc.
4.3 Piping within the boiler range
The piping within the boiler range includes feed gas piping, main gas piping, reheat gas piping, and branch piping within the primary valve (excluding the valve), as shown in Figure 2.
Note: The feed gas piping refers to the piping from the check valve at the outlet of the main compressor to the inlet header of the gas-cooled wall; the main gas piping refers to the piping from the outlet header of the final-stage superheater to the high-pressure main gas valve of the turbine (for boilers operating with a common header system, to the first valve before the header pipe); the cold section of reheat gas piping refers to the piping from the exhaust check valve at the turbine to the inlet header of the reheater; the hot section of reheat gas piping refers to the piping from the outlet header of the reheater to the low-pressure main gas valve of the turbine.
Figure 2 Diagram of piping within the range of a supercritical carbon dioxide boiler
4.4 Safety accessories, and instrumentation
Safety accessories and instrumentation include safety valves, carbon dioxide leak alarms, devices (instrumentation) for pressure measurement, temperature measurement, carbon dioxide concentration measurement, etc., safety protection devices, and blowdown devices.
Contents 1 Scope 2 Normative references 3 Terms and definitions 4 Definition of boiler range 4.1 Boiler range 4.2 Boiler proper 4.3 Piping within the boiler range 4.4 Safety accessories, and instrumentation 5 Models and parameters 5.1 Models 5.2 Parameters 6 General requirements 7 Materials 8 Design 8.1 Header and piping 8.2 Gas-cooled wall 8.3 High-temperature heating surface 8.4 Shunt economizer 9 Manufacturing and inspection 10 Safety accessories and instrumentation 10.1 Safety valve and its discharge line 10.2 Temperature measuring devices 10.3 Pressure measuring devices 10.4 Interlock protection 10.5 Others 11 Product nameplate, painting, packaging, and accompanying documents 11.1 Product nameplate 11.2 Painting and packaging 11.3 Accompanying documents 12 Installation and operation Annex A (Informative) Physical property data of supercritical carbon dioxide Annex B (Informative) Steam-line blowing method for supercritical carbon dioxide brayton-cycle generator set before start-up B.1 Pre-purge B.2 Closed pressure-stabilized steam-line blowing B.3 Quality standards for steam-line blowing Annex C (Informative) Sampling method for working fluid in supercritical carbon dioxide boilers C.1 Method summary C.2 Sampling system C.3 Sampling conditions C.4 Sampling procedure Annex D (Informative) Quality requirements and testing methods for carbon dioxide D.1 Quality requirements for carbon dioxide D.2 Quality testing methods for carbon dioxide Bibliography
