Installation method of ccpp waste heat boiler

Abstract

The application discloses a construction method for a CCPP waste heat boiler, and is characterized in that the method comprises the following steps: foundation acceptance, steel frame guard plate installation, entrance and exit flue and chimney installation, heating surface module installation, platform stair installation, boiler drum installation, expansion joint installation, main body pipeline installation, water pressure test, flue gas side sealing test, boiler working medium side cleaning and safety valve adjustment. The application has the advantages of high safety and efficiency, reasonable installation step design, strong operability, ensured installation quality and precision, greatly shortened construction period, saved engineering cost, created conditions for early start of the whole unit, and good social benefits.

Description

Technical Field

[0001] This invention relates to the field of waste heat boiler installation technology, and in particular to a method for installing and constructing a CCPP waste heat boiler. Background Technology

[0002] The CCPP waste heat boiler is one of the main components of a gas-steam combined cycle green power plant. It is used to recover the high-temperature flue gas generated by the gas turbine. Its modular structure adapts to the frequent start-up and shutdown of the gas turbine and the requirements for rapid start-up. It is convenient and reliable to operate and has broad development prospects.

[0003] CCPP waste heat boilers are large in size and weight, making installation and construction safety difficult to ensure. They also require highly specialized operation, making it difficult to guarantee the quality and precision of boiler installation. Furthermore, they involve long construction times, a large workload for installation and adjustment, and high construction costs. Summary of the Invention

[0004] This invention provides a construction method for installing a CCPP waste heat boiler. In order to solve a series of technical problems encountered in the installation process of waste heat boiler, the construction method of this invention is safe and efficient, the installation steps are reasonably designed, it has strong operability, ensures installation quality and accuracy, greatly shortens the construction period, saves project costs, and also creates conditions for the early start-up of the entire unit, thus having good social benefits.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] The installation and construction method for a CCPP waste heat boiler includes foundation acceptance, steel frame plate installation, inlet and outlet flue and chimney installation, heating surface module installation, platform and ladder installation, boiler drum installation, expansion joint installation, main body piping installation, water pressure test, flue gas side sealing test, boiler working fluid side cleaning, and safety valve adjustment. The specific method for installing the CCPP waste heat boiler is as follows:

[0007] I. Basic Acceptance

[0008] a. The foundation shall not bear any load if its strength has not reached 70% of the design strength level.

[0009] b. Verify the data of boiler positioning axis and foundation dimensions, embedded anchor bolt dimensions, and foundation component positions.

[0010] c. Secondary grouting of the foundation shall be carried out before the heating surface module is hoisted.

[0011] II. Steel Frame Guard Plate Installation

[0012] The boiler body steel frame and protective plate are welded from H-beams and steel plates. There are 12 columns on both sides, which are connected by crossbeams to form an integral frame. The bottom of the 12 columns is equipped with specially designed foundation components. Except for one fixed column that serves as the expansion center, the other 11 columns are column base structures that can be directionally slidable.

[0013] Ground assembly

[0014] Components such as steel frames, protective plates, inlet flues, outlet flues, and chimneys are all processed in sections and pieces and shipped to the site. The steel frames and protective plates are then assembled on the ground at the site.

[0015] Steel frame guardrail installation

[0016] Before the steel frame and protective plates are hoisted into place, the actual elevation of each foundation plane is measured. At the same time, the actual elevation below the 1m elevation line on each column is measured. The thickness of the shims between the column base plate and the foundation surface is calculated. The shims are leveled. After the columns are positioned and aligned, the shims are welded to the base plate in a continuous welding manner. Temporary fixing measures are taken after the steel frame components are hoisted into place. The connections between the steel frame components are corrected using turnbuckles.

[0017] III. Installation of Entrance and Exit Flues and Chimneys

[0018] The chimney structure is divided into three arc-shaped sections along the circumference, which are welded together on the ground to form a cylindrical shape. The sections are then hoisted and erected. The inlet and outlet flues are installed on a steel frame via expansion joints and supported by protective plates. The chimney stands on one side of the boiler.

[0019] IV. Installation of Heated Surface Modules

[0020] Five sets of heating surface modules are installed along the length of the boiler, and two heating surface modules are installed along the width of each set, for a total of 10 modules. Before hoisting, the quality of each part of the heating surface module is checked and defects are corrected. After the waste heat boiler steel frame and protective plate are installed to form a stable and reliable whole, the heating surface modules are hoisted.

[0021] V. Installation of Platform Escalators

[0022] The platform escalator was installed in real time during the steel frame installation process, which facilitated subsequent construction.

[0023] VI. Boiler Installation

[0024] This boiler has three drums: a high-pressure drum, a low-pressure drum, and a deaerator drum. Arc striking and arbitrary welding on the drums are strictly prohibited. Installation guidelines are as follows:

[0025] Inspection and calibration

[0026] Check the inner and outer surfaces of the boiler drum for defects such as cracks and dents. The welding quality and dimensions should meet the requirements.

[0027] Inspection and assembly of internal devices and components.

[0028] Inspect the internal components of the boiler drum and all connecting welds. Thoroughly remove any debris from inside the boiler drum. After passing the inspection, seal the manhole tightly.

[0029] hoisting and alignment

[0030] The boiler drum is placed in a plane perpendicular to the lifting direction beforehand. When the boiler drum leaves the ground, pause for a while to check its stability, and then slowly lift it to the installation position. After the boiler drum is lifted and installed in place, it is strictly aligned.

[0031] VII. Expansion Joint Installation

[0032] An inlet expansion joint is arranged between the outlet and inlet transition flue of the gas turbine diffuser section, and an outlet expansion joint is arranged between the heating surface module and the outlet flue.

[0033] VIII. Installation of the main piping

[0034] Before pipeline installation, verify the isometric drawing and steam-water system diagram to ensure the correct installation of pipelines, including valves and instrument sockets. Pipeline installation should be planned in a coordinated manner, with drainage slope, and should be aesthetically pleasing without affecting access. Large-diameter pipelines are manufactured in modules at the factory and assembled on-site. Sufficient margin should be left in the assembled large-diameter pipelines. Adjustments should be made for deviations caused during manufacturing, transportation, and installation. Small-diameter pipelines should be installed and supported on-site. The slope of boiler blowdown and drainage pipelines should not be less than 0.2% under operating conditions. The on-site installation and arrangement of small-diameter pipes should ensure free thermal expansion and not hinder the thermal expansion of boiler drum, headers, and pipes. When installing valves, pay attention to the medium flow direction, and valve electric actuators should have reliable rain protection measures.

[0035] All pressure-bearing components of the boiler's piping are welded on-site using argon arc welding. The supports and hangers are arranged reasonably and have a solid structure, ensuring that they do not obstruct the expansion of the pipes. Non-destructive testing is performed after the piping welding is completed.

[0036] IX. Water Pressure Test

[0037] After the weld joints within the hydrostatic test range have passed visual inspection, heat treatment, and non-destructive testing, and the relevant documents have been reviewed and approved by the special equipment supervision and inspection agency, the hydrostatic test can be conducted. The following preparatory work should be carried out before the hydrostatic test:

[0038] a) Inspect the surfaces of all pressure-bearing components. All components and elements within the scope of metal supervision have been inspected.

[0039] b) All hangers and supports within the boiler area have been adjusted, the spring hangers have been removed after a water pressure test, the boiler's internal and external environment is in good condition with no debris, passageways are unobstructed, and temporary scaffolding, communication, and lighting for inspection have been installed.

[0040] c) The expansion indicators at the boiler drum, header, main steam pipe, and reheater have been installed.

[0041] d) The temporary system for the hydrostatic test has been installed and passed the trial operation, and the drainage system has been installed and is able to drain water in a timely and reliable manner.

[0042] e) Check all instrument isolation; local water level gauges must be reliably isolated during overpressure testing.

[0043] f) Review the safety valve hydrostatic test process and take protective measures for the safety valve during boiler hydrostatic testing.

[0044] The boiler test pressure levels are divided into three pressure levels. The heating surface modules, boiler drum and interconnected pipes are subjected to overall hydrostatic tests. The test limit is the primary valve of the boiler steam and water pipeline. The three pressure levels are conducted in the order of low pressure first, then deaeration, and finally high pressure.

[0045] During the hydrostatic test, the ambient temperature should be maintained above +5℃. If the ambient temperature is low, take appropriate antifreeze and anti-cold measures. The test water temperature should not be lower than the ambient temperature and should not be lower than 21℃ under any circumstances.

[0046] The pressure point should be at the boiler drum, with at least two pressure gauges. The accuracy of the pressure gauges should be no less than 1.5 grade, and the water pressure test pressure value should be within the range of 1.5 to 3 times the range.

[0047] After the boiler is filled with water, any condensation on the metal surface should be thoroughly cleaned. The pressure rise and fall rate during the water pressure test should not exceed 0.3 MPa per minute. When the pressure rises to about 10% of the test pressure, a preliminary inspection should be conducted to eliminate any abnormalities. When the water pressure test reaches the working pressure, the pressure increase should be paused for a comprehensive inspection to check for any leaks or abnormalities and to confirm that the working pressure value has not dropped. Then, the pressure should be increased slowly and evenly to the test pressure. The boiler should be maintained at the test pressure for 20 minutes, and then reduced to the working pressure for a comprehensive inspection. During the inspection, the pressure should remain constant, and there should be no cracks or fissures in the welds, no leaks in the welds, and no deformation in the pipes. After the water pressure test, the water should be drained. If there is a long interval between the water pressure test and the start-up, anti-corrosion measures should be taken inside the steam and water system.

[0048] 10. Flue Gas Side Sealing Test

[0049] The purpose of the flue gas side sealing test is to check the flue gas sealing condition. The sealing test range is the entire flue gas path from the boiler inlet flue to the outlet flue and chimney. The test method is to release a smoke curtain in the inlet flue and pressurize it to 5 kPa with a small fan to conduct a comprehensive inspection of the flue and the outside of the furnace shell. If all steel frame plates and flue are butt welded on site and pass the magnetic particle inspection after welding, the flue gas side sealing test is not required.

[0050] XI. Boiler working fluid side cleaning

[0051] The main purpose of working fluid side cleaning is to make the inner surface of the pipe clean and uniform, passivate and generate a protective layer to protect the inside of the pipe from corrosion during operation. It mainly includes the following steps:

[0052] Manual cleaning

[0053] Clean the accessible areas by hand, open all manhole covers on the steam drums, and remove as much grease, welding slag, and other impurities as possible by hand.

[0054] Organic material removal

[0055] After manual cleaning, all residual organic matter (oil, grease, or pipe protective coating) inside must be removed, and all loose impurities attached to the inner surface of the pipe must be rinsed off. Initially, rinse with hot water, then rinse with a cleaning solution in a circulating manner. The cleaning solution should be drained periodically to remove impurities, and the chemical reagents should be adjusted as required. Before the cleaning is finished, rinse with high-quality condensate water and drain until the phosphate content is less than 2 ppm. If residual grease is still obvious, repeat the cleaning steps.

[0056] Oxidation layer removal

[0057] Oxide scale is usually removed with acid or chelating agents. This solvent is heated and remains or circulates in the boiler for a predetermined time until tests show that the reaction rate has decreased. After pickling, the pH of the solution must be increased to promote passivation, or the acid solution can be drained and replaced with an alkaline solution for circulation. Finally, it should be rinsed with clean water circulation. After completion, drain the clean water, open the boiler drum manhole door, rinse the manhole door gasket sealing surface, and replace the gasket with a new one. All acid solutions on the inner surfaces must be completely removed to prevent damage. If oil and grease are present, they will hinder the removal of oxide scale. Alkaline washing must be performed before pickling.

[0058] Rinsing and blowing

[0059] Before supplying water and steam, the feedwater pipes, desuperheating water pipes, superheaters and their pipes within the boiler area shall be flushed and purged to remove residual substances accumulated in the piping system. The flushing water volume shall be greater than the maximum water volume during normal operation. The system is considered qualified when the effluent is clear and the outlet water quality is close to the inlet water quality. When purging the superheater and its steam pipes, the purging coefficient k at all points in the system shall be greater than 1.1. A smaller purging coefficient shall be used for the low-pressure system, but the minimum shall not be less than 1.0.

[0060] 12. Safety Valve Adjustment

[0061] The boiler has a total of 8 safety valves, which were adjusted one by one to ensure that each safety valve is safe and effective.

[0062] The heated surface module is installed using a top-mounted method.

[0063] All of the aforementioned inlet expansion joints are non-metallic expansion joints.

[0064] The water used for the hydrostatic test is demineralized water, deoxygenated water, or pure condensate.

[0065] The rinsing water should preferably be demineralized water or softened water.

[0066] Compared with the prior art, the beneficial effects of the present invention are:

[0067] The construction method is safe and efficient, the installation steps are reasonably designed, it is highly operable, it ensures installation quality and accuracy, greatly shortens the construction period, saves project costs, and creates conditions for the early start-up of the entire unit, thus having good social benefits. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of the installation and construction method of the CCPP waste heat boiler described in this invention.

[0069] Figure 2 This is a diagram showing the installation of the protective plate in the CCPP waste heat boiler installation and construction method described in this invention.

[0070] Figure 3 This is a diagram showing the hoisting of the heating surface template for the CCPP waste heat boiler installation and construction method described in this invention.

[0071] Figure 4 This is a diagram showing the rotating installation of the heating surface template in the CCPP waste heat boiler installation and construction method described in this invention.

[0072] In the diagram: 1. Steel frame 2. Flue gas inlet 3. Heating surface module 4. Boiler 5. Platform ladder 6. Pressure boiler drum

[0073] 7. Low-pressure boiler drum 8. Deaerator boiler drum 9. Protective plate 10. Chimney 11. Module centerline Detailed Implementation

[0074] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0075] The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0076]

Example

[0077] The specific implementation of the present invention is illustrated by taking the CCPP waste heat boiler with model number Q1064 / 566-178.2(28)-7.43(0.69) / 533(273) as an example.

[0078] like Figure 1 As shown, the installation and construction method of the CCPP waste heat boiler includes foundation acceptance, installation of steel frame 1 and protective plate 9, installation of inlet and outlet flues and chimney, installation of heating surface module 3, installation of platform ladder 5, boiler drum installation, expansion joint installation, main body piping installation, water pressure test, flue gas side sealing test, boiler 4 working fluid side cleaning, and safety valve adjustment. The method of the CCPP waste heat boiler installation and construction is as follows:

[0079] I. Basic Acceptance

[0080] The foundation acceptance shall be carried out in accordance with the provisions of the "Code for Construction and Acceptance of Concrete Structures". The foundation shall not bear load if its strength has not reached 70% of the design strength grade.

[0081] Verify the dimensions of the boiler's four positioning axes and foundation. Allowable error for foundation marking:

[0082]

[0083] Allowable error values ​​for pre-embedded anchor bolts:

[0084]

[0085] The gap between the foundation surface and the column base plate for secondary grouting shall not be less than 50 mm. The entire foundation surface shall be roughened, and the area where the shims are placed shall be chiseled smooth.

[0086] The foundation components should be installed according to the equipment foundation load diagram and the foundation anchor bolt and fixing device diagram.

[0087] The secondary grouting of the foundation should be carried out before the hoisting of the heated surface module 3. Before the secondary grouting, it should be checked whether the work of the shims, anchor bolts, etc. has been completed, and the oil stains, welding slag and impurities on the bottom surface should be cleaned.

[0088] II. Steel Frame Guard Plate Installation

[0089] The boiler body steel frame 1 and the protective plate 9 are welded from H-beams and steel plates, with a total of 12 columns on both sides, connected by horizontal beams to form an integral frame. The bottom of the 12 columns is equipped with specially designed foundation components. Except for one fixed column that serves as the expansion center, the remaining 11 columns are column base structures that can be directionally slidable.

[0090] Ground assembly

[0091] Due to limitations in manufacturing and transportation conditions, components such as the steel frame 1, protective plate 9, inlet flue, outlet flue, and chimney 10 of the module are processed in sections and pieces before being shipped to the site. The steel frame 1 and protective plate 9 are assembled on the ground on site and then hoisted into place. The heated surface module 3, protective plate 9, and columns in the steel frame 1 are assembled into a piece. A 1m elevation baseline should be marked on each column of the steel frame 1 for leveling during the overall assembly of the steel frame 1.

[0092] Steel frame 1 guard plate 9 installation

[0093] Before hoisting and positioning steel frame 1 and protective plate 9, measure the actual elevation of each foundation plane and the actual elevation below the 1m elevation line on each column. Calculate the thickness of the shims between the column base plate and the foundation surface. The shims should be flat and should not be loose after the column is positioned. After the column is aligned, weld the shims to the base plate continuously around the perimeter. Temporary fixing measures should be taken after the steel frame 1 assembly is hoisted and positioned. The connection between steel frame 1 assemblies can be corrected using turnbuckles. When installing steel frame 1 and protective plate 9, each piece must be installed and aligned one at a time. The foundation of axis 6 is the fixed point. Expand to the right, forward, and backward with axis 6 as the center. First, ensure that the column of axis 6 is correctly positioned. The alignment of steel frame 1 is based on the center line of boiler 4 foundation. Adjust the elevation first, then adjust the position. The elevation of all columns should be consistent; otherwise, adjustments should be made.

[0094] The allowable deviations for the installation of steel frame 1 are as follows:

[0095]

[0096] like Figure 2 As shown, after the steel frame 1 component is aligned and in place, the unassembled side guard plates 9 are installed. First, the guard plate 9 is lifted to a position close to one side column, then rotated through the other side column, and then adjusted to a suitable position and welded. At the same time, the corresponding bottom beam and bottom guard plate 9 are installed, the corresponding top beam is installed, and then the insulation layer and inner lining plate of the construction joint are installed. After the heated surface module 3 is hoisted into place, the top seal is installed.

[0097] The joints and corners of the steel frame 1 guard plate 9 should be filled with thermal insulation material. The thermal insulation material should be pressed tightly with staggered joints. The inner lining plate should be installed in accordance with the direction of flue gas flow and can be allowed to expand freely. All sealed welds should be inspected for oil seepage or other non-destructive tests to ensure weld quality.

[0098] III. Installation of Entrance and Exit Flues and Chimneys

[0099] The installation of the flue gas inlet 2 and flue gas duct steel frame 1 and protective plate 9 shall be carried out in accordance with the requirements, and the degree of ground assembly shall be maximized. The structure of the chimney 10 is divided into 3 arc-shaped segments along the circumference, which are welded into a cylindrical shape on the construction site. The segments are hoisted and erected. The inlet and outlet flue gas ducts are installed on the steel frame 1 through expansion joints and supported by protective plate 9. The chimney 10 is erected on the side of the boiler and assembled on the ground as much as possible. The center line of the flue gas inlet 2 of the chimney 10 is consistent with the center line of the main body steel frame 1 and protective plate 9. The verticality deviation of the chimney 10 shall not exceed 1‰ of the length of the chimney 10 and shall not exceed 20mm.

[0100] IV. Installation of Heated Surface Module 3

[0101] Five sets of heating surface modules 3 are installed along the length of boiler 4, and each set has two heating surface modules 3 along the width, for a total of 10 modules. Each heating surface module 3 consists of a tube panel, a furnace top liner, a hanging device, a hanging beam, connecting pipes, and a smoke baffle.

[0102]

[0103] Before hoisting, inspect the quality of each part of the module. Any defects found should be corrected if possible; otherwise, they should be recorded and hoisted only after the manufacturer confirms that they will not affect performance.

[0104] like Figure 3 , 4 As shown, the heating surface module 3 can only be hoisted after the steel frame 1 and protective plate 9 of the waste heat boiler 4 are installed to form a stable and reliable whole. The heating surface module 3 adopts the top hoisting method and uses a hoisting stretcher to hoist the heating surface module 3. One end of the stretcher is fixed to a specially designed foundation, and the stretcher can rotate freely on the foundation through the rotating shaft fixed to the foundation. The heating surface module 3 is placed flat on the stretcher. The head of the heating surface module 3 is connected to the head of the stretcher through the lifting lug and the pin. One main crane lifts the head of the heating surface module 3, one auxiliary crane lifts the head of the stretcher, and two crawler cranes work together to smoothly turn the heating surface module 3 from a horizontal state to a vertical state. In the vertical state, the pin is removed to separate the heating surface module 3 from the stretcher. The main crane hoists the heating surface module 3 to the designed position on the crossbeam of each column of the furnace body steel frame 1. The auxiliary crane lowers the stretcher back to the horizontal position and starts hoisting the next heating surface module 3. The hoisting sequence of the heating surface module 3 can be arbitrary.

[0105] Lifting Parameter Table for Heated Surface Module 3:

[0106]

[0107] The installation deviation of the heated surface module 3 should meet the following requirements:

[0108]

[0109] VI. Installation of Platform Escalator 5

[0110] The installation of platform ladder 5 shall be carried out in accordance with the requirements of JB / T1620 and steel frame 1 guard plate 9. Platform ladder 5 should be installed as early as possible to facilitate construction. First, install the support frame and beam onto the boiler body 4, then hoist the platform frame to the fixed position and connect it with bolts or welding. Finally, install the grid and pay attention to the cutting and reinforcement of holes such as pipes passing through the grid.

[0111] VII. Boiler Drum Installation

[0112] Boiler 4 has three drums: a high-pressure drum 6, a low-pressure drum 7, and a deaerator drum 8. Arc striking and arbitrary welding on the drums are strictly prohibited. High-pressure drum 6 has an outer diameter of φ2060mm, a total length of approximately 10000mm, and a weight of approximately 53 tons. Low-pressure drum 7 has an outer diameter of φ1540mm, a total length of approximately 8080mm, and a weight of approximately 79 tons. Deaerator drum 8 has an outer diameter of φ2436mm, a total length of approximately 9228mm, and a weight of approximately 15 tons. Installation points are as follows:

[0113] Inspection and calibration

[0114] Check the inner and outer surfaces of the boiler drum for cracks, dents, or other defects. Verify that the welding quality and dimensions meet the requirements. Locate the horizontal and vertical centerline marks at both ends and check that their positions are correct. Inspect pipe joints, pipe seats, etc. for damage. Repair any damage before installation.

[0115] Inspection and assembly of internal devices and components

[0116] Check the internal components of the boiler drum and all connecting welds to ensure they meet the requirements of the drawings. Check for any loose parts. Ensure that the internal fasteners are securely connected. For welds made on-site, remove any debris from the inside of the boiler drum before welding. If there is any debris inside the boiler drum, remove it completely. After acceptance, seal the manhole tightly.

[0117] hoisting and alignment

[0118] The boiler drum should be pre-positioned in a plane perpendicular to the lifting direction to prevent it from swaying and impacting during lifting. Lifting slings or other measures to prevent marks on the boiler drum surface should be used during lifting. Pipe joints must not be squeezed during lifting. When the boiler drum leaves the ground, pause briefly to check its stability, then slowly raise it to the installation position. After the boiler drum is lifted and installed in place, strict alignment is required. The allowable installation deviation is as follows:

[0119]

[0120] 8. Expansion Joint Installation

[0121] An inlet expansion joint is installed between the outlet and inlet transition flue of the gas turbine diffuser section, and an outlet expansion joint is installed between the heating surface module 3 and the outlet flue. All of these are non-metallic expansion joints, and their installation should comply with the requirements of the manufacturer's drawings and documents.

[0122] IX. Installation of main body piping

[0123] In addition to complying with the provisions of DL / T5047 "Technical Specifications for Construction and Acceptance of Power Plants" (Boiler Unit Section), pipeline installation should also comply with the provisions of DL5031 "Technical Specifications for Construction and Acceptance of Power Plants" (Pipeline Section) and meet the requirements of the design drawings. Before pipeline installation, in addition to checking the isometric drawing of the pipeline, the steam-water system drawing should also be checked to ensure the correctness of the pipeline installation, including valves and instrument sockets. Pipeline installation should be planned in a coordinated manner, with drainage slope, aesthetically pleasing workmanship, and without affecting the passage. Large-diameter pipelines should be manufactured in modules in the factory and assembled on the ground. Sufficient margin should be left in the assembled large-diameter pipelines to adjust for deviations caused during manufacturing, transportation, and installation. Small-diameter pipelines should be installed and supported on-site. The slope of boiler blowdown and drainage pipelines should not be less than 0.2% under operating conditions. The on-site installation and layout of small-diameter pipes should ensure free thermal expansion and not hinder the thermal expansion of the boiler drum, header, and pipes. When installing valves, attention should be paid to the medium flow direction to facilitate operation and maintenance. Valve electric actuators should have reliable rain protection measures.

[0124] All pressure-bearing components of the boiler's piping are welded on-site using argon arc welding or argon arc welding for the root pass. The supports and hangers are arranged reasonably and have a solid structure, and must not obstruct the expansion of the pipes. After the pipe welding is completed, non-destructive testing must be carried out strictly in accordance with the drawings. The next construction process can only be carried out after the non-destructive testing is qualified.

[0125] 10. Water pressure test

[0126] Within the scope of the hydrostatic test, the weld joints must pass visual inspection, heat treatment, and non-destructive testing, and the relevant documents must be reviewed and approved by the special equipment supervision and inspection agency before the hydrostatic test is conducted.

[0127] The following preparations should be made before the hydrostatic test:

[0128] a) Inspect the surfaces of all pressure-bearing components. All components and elements within the scope of metal supervision have been inspected.

[0129] b) The hangers and supports within the boiler 4 area have been adjusted, the spring hangers have been removed after the water pressure test, the internal and external environment of boiler 4 is good and free of debris, the passage is unobstructed, and temporary scaffolding, communication and lighting for inspection have been installed.

[0130] c) The expansion indicators at the boiler drum, header, main steam pipe, and reheater have been installed.

[0131] d) The temporary system for the hydrostatic test has been installed and passed the trial operation, and the drainage system has been installed and is able to drain water in a timely and reliable manner.

[0132] e) Check all instrument isolation; local water level gauges must be reliably isolated during overpressure testing.

[0133] f) Review the safety valve hydrostatic test process and take protective measures for the safety valve during boiler hydrostatic testing.

[0134] Boiler 4 was subjected to an overall hydrostatic test in three pressure levels, including the module, boiler drum, and interconnecting pipes. The test limit was the primary valve of the steam and water pipeline of Boiler 4. The three pressure levels were tested in the order of low pressure first, then deaeration, and finally high pressure.

[0135]

[0136] During the hydrostatic test, the ambient temperature should be maintained above +5℃. If the ambient temperature is low, take appropriate antifreeze and anti-cold measures. The test water temperature should not be lower than the ambient temperature and should not be lower than 21℃ under any circumstances.

[0137] The pressure point should be at the boiler drum. There should be no fewer than two pressure gauges, and the accuracy of the pressure gauges should be no less than 1.5 grade. The pressure gauges should be calibrated and qualified. The water pressure test pressure value should be within the range of 1.5 to 3 times the range.

[0138] After the boiler is filled with water, any condensation on the metal surface should be removed. The pressure rise and fall rate during the water pressure test should not exceed 0.3 MPa per minute. When the pressure rises to about 10% of the test pressure, a preliminary inspection should be conducted to eliminate any abnormalities. When the water pressure test reaches the working pressure, the pressure rise should be paused for a comprehensive inspection to check for leaks or abnormalities and to confirm that the working pressure value has not dropped. Then, the pressure should be slowly and evenly increased to the test pressure. The boiler should be kept at the test pressure for 20 minutes, and then reduced to the working pressure for a comprehensive inspection. During the inspection, if the pressure remains constant, there are no cracks or fissures in the welds, no leaks in the welds, and no deformation in the pipes, the water pressure test can be considered qualified. After the water pressure test, the water should be drained. If the interval between the water pressure test and the start-up is long, anti-corrosion measures should be taken inside the steam and water system.

[0139] Low-pressure system hydrostatic test operation procedure

[0140] Open all drain and condensate valves of the low-pressure system and deaeration system, as well as all vent valves of the low-pressure system and deaeration system. Close all near-end valves. Open all condensate valves and vent valves of the deaeration feedwater pump system, low-pressure feedwater pump system, and high-pressure feedwater pump system. Close the needle valves of the instrument system. Open the low-pressure end valves. Open all vent valves of the low-pressure system. Inject water into the system through the valves. Except for the top vent valve, close the bottom vent valves step by step according to the water injection situation. After the top vent valve overflows, quickly open the bottom drain and condensate valves to inject water into the system. Perform flushing repeatedly until the water quality is clear. After flushing, close the valves and open all steam vent valves of the low-pressure system. Inject water into the system through the valves and close each steam vent valve step by step according to the water injection situation. After the system is full of water, close the bottom valve and the top steam vent valve. Confirm that all drain and condensate valves and steam vent valves except for the low-pressure system are open. Open the condensate valve and pressurize the system according to the plan requirements. After the water pressure test is qualified, first slowly open the top steam vent valve to release pressure, and then open the bottom valve and each drain and condensate valve at the bottom to release water.

[0141] Deoxygenation system water pressure test operation procedure

[0142] Open all drain and steam vent valves of the low-pressure system and deaeration system, as well as all steam vent valves of the low-pressure system and deaeration system. Close all near-end valves. Open all steam vent valves of the deaeration feedwater pump system, low-pressure feedwater pump system, and high-pressure feedwater pump system. Close all needle valves of the instrument system. Open the valve at the hydrostatic test end. Open all steam vent valves of the deaeration system. Inject water into the system through the water inlet valve. Except for the top steam vent valve, close the bottom steam vent valve step by step according to the water injection situation. After water overflows from the top steam vent valve, quickly open the drain valve to control the system flow. The system is flushed repeatedly until the water quality is clear. After flushing, the bottom valve is closed and the top valve is opened. All steam vent valves of the deaeration system are opened, and water is refilled into the system through the water injection valve. The steam vent valves are closed one by one according to the water injection situation. After the system is full of water, the water injection valve is closed and the top steam vent valve is closed. It is confirmed that all sewage discharge, drainage valves and steam vent valves except those of the deaeration system are open. The pressure pump valve is opened to pressurize the system according to the plan requirements. After the water pressure test is qualified, the top steam vent valve is opened slowly to release pressure first, and then the valve is opened to release water.

[0143] High-pressure system water pressure test operation procedure

[0144] Open all drain and condensate valves and steam vent valves of the low-pressure and high-pressure systems. Close all near-end valves. Open all condensate valves and steam vent valves of the deaerator feedwater pump system, low-pressure feedwater pump system, and high-pressure feedwater pump system. Close the needle valves of the instrument system. Open the high-pressure feedwater valves. Open all steam vent valves of the high-pressure system. Inject water into the system through the water injection valves. Except for the top steam vent valve, close the bottom steam vent valves step by step according to the water injection situation. After water overflows from the top steam vent valve, quickly open the bottom drain and condensate valves to flush the system. Wash repeatedly until the water is clear. After rinsing, close the bottom valve, open the top drain valve, open all the steam vent valves of the high-pressure system, and refill the system with water through the water injection valve. Close each steam vent valve step by step according to the water injection situation. After the system is full of water, close the water injection valve and the top steam vent valve. Confirm that all drain valves, condensate valves and steam vent valves except for the high-pressure system are open. Open the pressure pump valve to pressurize the system according to the plan requirements. After the water pressure test is qualified, first slowly open the top steam vent valve to release pressure, and then open the bottom drain valves to release water.

[0145] XI. Flue Gas Side Sealing Test

[0146] The purpose of the flue gas side sealing test is to check the flue gas sealing condition. The sealing test range is from the boiler inlet flue 4 to the outlet flue and the chimney 10, covering the entire flue gas path. The test method involves placing a smoke screen in the inlet flue and using a small fan to pressurize to 5 kPa to conduct a comprehensive inspection of the flue and the outside of the boiler shell. If all the steel frame plates and the welded joints on the flue that are butted on site pass the magnetic particle inspection after welding, the flue gas side sealing test is not required.

[0147] 12. Boiler working fluid side cleaning

[0148] The main purpose of working fluid side cleaning is to make the inner surface of the pipe clean and uniform, passivate and generate a protective layer to protect the inside of the pipe from corrosion during operation. It mainly includes the following steps:

[0149] Manual cleaning

[0150] Clean the accessible areas by hand, open all manhole covers on the steam drums, and remove as much grease, welding slag, and other impurities as possible by hand.

[0151] Organic material removal

[0152] After manual cleaning, all residual organic matter (oil, grease, or pipe protective coating) inside must be removed, and all loose impurities attached to the inner surface of the pipe must be rinsed off. Initially, rinse with hot water, then rinse with a cleaning solution in a circulating manner. The cleaning solution should be drained periodically to remove impurities, and the chemical reagents should be adjusted as required. Before the cleaning is finished, rinse with high-quality condensate water and drain until the phosphate content is less than 2 ppm. If residual grease is still obvious, repeat the cleaning steps.

[0153] Oxidation layer removal

[0154] To remove oxide scale, iron oxide, or other precipitates, oxide scale is typically removed with acid or a chelating agent. This solvent is usually heated and can remain or circulate in the boiler for a predetermined time until tests show that the reaction rate has decreased. After pickling, the pH of the solution must be increased to promote passivation, or the acid solution can be drained and replaced with an alkaline solution for circulation. Finally, it should be rinsed with clean water. After completion, drain the clean water, open the boiler drum manhole door, rinse the manhole door gasket sealing surface, and replace the gasket with a new one. All acid solutions on the inner surfaces must be completely removed to prevent damage. If oil and grease are present, they will hinder the removal of oxide scale, so alkaline washing must be performed before pickling.

[0155] Rinsing and blowing

[0156] Before putting the boiler into operation, the feedwater pipes, desuperheating water pipes, superheaters and their pipes within the boiler 4 area shall be flushed and purged to remove residual substances accumulated in the pipeline system. The flushing water volume shall be greater than the maximum water volume during normal operation. The system is considered qualified when the effluent is clear and the outlet water quality is close to the inlet water quality. When purging the superheater and its steam pipes, the purging coefficient k at all points in the system shall be greater than 1.1. A smaller purging coefficient shall be used for the low-pressure system, but the minimum shall not be less than 1.0.

[0157] 13. Safety Valve Adjustment

[0158] Boiler 4 has a total of 8 safety valves. The adjustment of the safety valves should comply with the requirements of the "Safety Technical Inspection Regulations for Steam Boilers". Each safety valve should be adjusted one by one to ensure that each safety valve is safe and effective.

[0159] The safety valve set pressure is as follows:

[0160] One high-pressure superheated steam outlet safety valve, 8.38 MPa (g).

[0161] Pressure cooker drum with 8 safety valves (2 each), rated at 8.65 / 8.91 MPa (g).

[0162] One low-pressure superheated steam outlet safety valve, 1.121 MPa (g).

[0163] Low-pressure boiler drum, 6 safety valves, 1.206 MPa (g)

[0164] One low-pressure water supply safety valve (2.068 MPa (g))

[0165] Two deaerator safety valves, each with a pressure rating of 0.70 / 0.70 MPa (g).

[0166] For the water pressure test, it is recommended to use demineralized water, deoxygenated water, or pure condensate. The condensate needs to be treated with preservatives, such as 10 mg / L ammonia and 200 mg / L hydrazine.

[0167] During the installation process, the construction method of this invention is safe and efficient, the installation steps are reasonably designed, it has strong operability, ensures installation quality and accuracy, greatly shortens the construction period, saves project costs, and creates conditions for the early start-up of the entire unit, thus having good social benefits.

Claims

1. A method for installing and constructing a CCPP waste heat boiler, characterized in that, The installation and construction method for the CCPP waste heat boiler includes the following: foundation acceptance, steel frame guard plate installation, inlet and outlet flue and chimney installation, heating surface module installation, platform ladder installation, boiler drum installation, expansion joint installation, main body piping installation, water pressure test, flue gas side sealing test, boiler working fluid side cleaning, and safety valve adjustment. The method is as follows: I. Basic Acceptance a. The foundation shall not bear any load if its strength has not reached 70% of the design strength grade; b. Verify the data of boiler positioning axis and foundation dimensions, embedded anchor bolt dimensions, and foundation component positions; c. Secondary grouting of the foundation shall be carried out before the heating surface module is hoisted; II. Steel Frame Guard Plate Installation The boiler body steel frame and protective plate are welded from H-beams and steel plates. There are 12 columns on both sides, which are connected by crossbeams to form an integral frame. The bottom of the 12 columns is equipped with specially designed foundation components. Except for one fixed column that serves as the expansion center, the other 11 columns are column base structures that can be directionally slidable. Ground assembly The steel frame, protective plates, inlet flue, outlet flue, and chimney components are all processed in sections and pieces and shipped to the site. The steel frame and protective plates are assembled on the ground at the site. Steel frame guardrail installation Before the steel frame and protective plate are hoisted into place, the actual elevation of each foundation plane is measured. At the same time, the actual elevation below the 1m elevation line on each column is measured. The thickness of the shims between the column base plate and the foundation surface is calculated. The shims are flat. After the column is positioned and aligned, the shims are welded to the base plate in a continuous welding manner. Temporary fixing measures are taken after the steel frame components are hoisted into place. The connection between the steel frame components is corrected using turnbuckles. III. Installation of Entrance and Exit Flues and Chimneys The chimney structure is divided into three arc sections along the circumference, which are welded together on the ground to form a cylindrical shape. The sections are then hoisted and erected. The inlet and outlet flues are installed on a steel frame via expansion joints and supported by protective plates. The chimney stands on one side of the boiler. IV. Installation of Heated Surface Modules Five sets of heating surface modules are installed along the length of the boiler, and two heating surface modules are installed along the width of each set, for a total of 10. Before hoisting, the quality of each part of the heating surface module is checked and defects are corrected. After the waste heat boiler steel frame and protective plate are installed to form a stable and reliable whole, the heating surface modules are hoisted. V. Installation of Platform Escalators The platform escalator was installed in real time during the steel frame installation process, which facilitated subsequent construction. VI. Boiler Installation The boiler has three drums: a high-pressure drum, a low-pressure drum, and a deaerator drum. Arc striking and arbitrary welding on the drums are strictly prohibited. Installation guidelines are as follows: Inspection and calibration Check the inner and outer surfaces of the boiler drum for cracks, dents, or defects. The welding quality and dimensions should meet the requirements. Inspection and assembly of internal devices and components Inspect the internal components of the boiler drum and all connecting welds. Thoroughly remove any debris from inside the boiler drum. After passing the inspection, seal the manhole tightly. hoisting and alignment The boiler drum is placed in a plane perpendicular to the lifting direction beforehand. When the boiler drum leaves the ground, pause for a while to check its stability, and then slowly lift it to the installation position. After the boiler drum is lifted and installed in place, it must be strictly aligned. VII. Expansion Joint Installation An inlet expansion joint is arranged between the outlet and inlet transition flue of the gas turbine diffuser section, and an outlet expansion joint is arranged between the heat transfer surface module and the outlet flue. VIII. Installation of the main piping Before pipeline installation, check the isometric drawing and steam-water system diagram to ensure the correct installation of pipelines, including valves and instrument sockets. Pipeline installation should be planned in a coordinated manner, with drainage slope, and should be aesthetically pleasing without affecting access. Large-diameter pipelines are manufactured in modules in the factory and assembled on-site. Sufficient margin should be left in the assembled large-diameter pipelines to adjust for deviations caused during manufacturing, transportation, and installation. Small-diameter pipelines should be installed and supported on-site. The slope of boiler blowdown and drainage pipelines should not be less than 0.2% under operating conditions. The on-site installation and layout of small-diameter pipes should ensure free thermal expansion and not hinder the thermal expansion of boiler drum, headers, and pipes. When installing valves, pay attention to the medium flow direction, and valve electric actuators should have reliable rain protection measures. All pressure-bearing components of the boiler's piping are welded on-site using argon arc welding. The supports and hangers are arranged reasonably and have a solid structure, and must not obstruct the expansion of the pipes. Non-destructive testing is performed after the pipe welding is completed. IX. Water Pressure Test After the weld joints within the hydrostatic test range have passed visual inspection, heat treatment, and non-destructive testing, and the relevant documents have been reviewed and approved by the special equipment supervision and inspection agency, the hydrostatic test can be conducted. The following preparatory work should be carried out before the hydrostatic test: a) Inspect the surfaces of all pressure-bearing components; all components and elements within the scope of metal supervision have been inspected. b) All hangers and supports within the boiler area have been adjusted, the spring hangers have been removed after a water pressure test, the boiler's internal and external environment is in good condition with no debris, passageways are unobstructed, and temporary scaffolding, communication, and lighting for inspection have been installed. c) The expansion indicators at the boiler drum, headers, main steam pipes, and reheater have been installed. d) The temporary system for the hydrostatic test has been installed and passed the trial operation; the drainage system has been installed and is able to drain water in a timely and reliable manner. e) Check the isolation of all instruments; the local water level gauges must be reliably isolated during the overpressure test. f) Review the safety valve hydrostatic test process and take protective measures for the safety valve during the boiler hydrostatic test; The boiler pressure rating is divided into three pressure levels. The heating surface module, boiler drum and interconnecting pipes are subjected to overall hydrostatic testing. The test limit is the primary valve of the boiler steam and water pipeline. The three pressure levels are tested in the order of low pressure first, then deaeration, and finally high pressure. During the hydrostatic test, the ambient temperature should be maintained above +5℃. If the ambient temperature is low, take appropriate antifreeze and anti-cold measures. The test water temperature should not be lower than the ambient temperature and should not be lower than 21℃ under any circumstances. The pressure point should be at the boiler drum, with no fewer than two pressure gauges. The accuracy of the pressure gauges should be no less than 1.5 grade, and the water pressure test pressure value should be within the range of 1.5 to 3 times the range. After the boiler is filled with water, any condensation on the metal surface should be cleaned. The pressure rise and fall rate of the water pressure test should not exceed 0.3 MPa per minute. When the pressure rises to about 10% of the test pressure, a preliminary inspection should be performed to eliminate any abnormalities. When the water pressure test reaches the working pressure, the pressure rise should be paused for a comprehensive inspection to check for any leaks or abnormalities and to confirm that the working pressure value has not dropped. Then, the pressure should be slowly and evenly increased to the test pressure. The boiler should be kept at the test pressure for 20 minutes, and then reduced to the working pressure for a comprehensive inspection. During the inspection, the pressure should remain constant, and there should be no cracks or fissures in the welds, no leaks in the welds, and no deformation in the pipes. After the water pressure test, the water should be drained. If the interval between the water pressure test and the start-up is long, anti-corrosion measures should be taken inside the steam and water system.

10. Flue Gas Side Sealing Test The purpose of the flue gas side sealing test is to check the flue gas sealing condition. The sealing test range is the entire flue gas path from the boiler inlet flue to the outlet flue and chimney. The test method is to place a smoke curtain in the inlet flue and pressurize it to 5 kPa with a small fan to conduct a comprehensive inspection of the flue and the outside of the furnace shell. If all steel frame plates and flue are butt welded on site and pass the magnetic particle inspection after welding, the flue gas side sealing test is not required. XI. Boiler working fluid side cleaning The main purpose of working fluid side cleaning is to make the inner surface of the pipe clean and uniform, passivate and generate a protective layer to protect the inside of the pipe from corrosion during operation. It mainly includes the following steps: Manual cleaning Clean the accessible areas by hand, open all manhole covers on the steam drums, and remove grease, welding slag and impurities by hand. Organic material removal After manual cleaning, all residual organic matter inside must be removed, and all loose impurities attached to the inner surface of the tube must be rinsed off. Initially, rinse with hot water, then rinse with a cleaning solution in a circulating manner. The cleaning solution should be discharged periodically to remove impurities, and the chemical reagents should be adjusted as required. Before the cleaning is finished, rinse with high-quality condensate and drain until the phosphate content is less than 2 ppm. If residual grease is still obvious, repeat the cleaning steps. Oxidation layer removal Oxide scale is usually removed with acid or chelating agents. This solvent is heated and remains or circulates in the boiler for a predetermined time until tests show that the reaction rate has decreased. After pickling, the pH of the solution must be increased to promote passivation, or the acid solution can be drained and replaced with an alkaline solution for circulation. Finally, it should be rinsed with clean water circulation. After completion, drain the clean water, open the boiler drum manhole door, rinse the manhole door gasket sealing surface, and replace the gasket with a new one. All acid solutions on the inner surfaces must be completely removed to prevent damage. If oil and grease are present, they will hinder the removal of oxide scale. Alkaline washing must be performed before pickling. Rinsing and blowing Before supplying water and steam, the feedwater pipes, desuperheating water pipes, superheaters and their pipes within the boiler area shall be flushed and purged to remove residual substances accumulated in the piping system. The flushing water volume shall be greater than the maximum water volume during normal operation. The system is considered qualified when the effluent is clear and the outlet water quality is close to the inlet water quality. When purging the superheater and its steam pipes, the purging coefficient k at all points in the system shall be ensured to be greater than 1.

1. A smaller purging coefficient shall be used for the low-pressure system, but the minimum shall not be less than 1.

0.

12. Safety Valve Adjustment The boiler has a total of 8 safety valves, which were adjusted one by one to ensure that each safety valve is safe and effective.

2. The installation and construction method of the CCPP waste heat boiler according to claim 1, characterized in that, The heated surface module is installed using a top-mounted method.

3. The installation and construction method of the CCPP waste heat boiler according to claim 1, characterized in that, Both the inlet expansion joint and the outlet expansion joint are non-metallic expansion joints.

4. The installation and construction method of the CCPP waste heat boiler according to claim 1, characterized in that, The water used for the hydrostatic test is demineralized water, deoxygenated water, or pure condensate.

5. The installation and construction method of the CCPP waste heat boiler according to claim 1, characterized in that, The rinsing water should preferably be demineralized water or softened water.

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