[0017] A blast furnace five-way ball post-welding heat treatment method, comprising the following steps:
[0018] First, place the test board in the temperate zone and place three test boards at 120° intervals to try to synchronize, set temperature measurement points on the test board, and thicken the insulation layer here to ensure that the temperature of the test board is the same as that of the spherical shell board;
[0019] Secondly, before heat treatment, open two holes with a size of not less than φ500 in the spherical shell, choose the opening position of the rising pipe position and the descending pipe position, one in each place, as the air inlet and exhaust port of the burner nozzle;
[0020] One of the openings must be placed at a lower position from the ground to facilitate the placement of heat treatment equipment during heat treatment, and the other as a smoke exhaust port, placed far away from inflammable and explosive materials;
[0021] Finally, the heat treatment is carried out by internal heating by the fuel oil method: the interior of the spherical tank is used as the furnace chamber, the No. 0 diesel oil is used as the fuel, and the exterior of the spherical tank is insulated with thermal insulation materials. The electronic igniter is ignited, and the high-temperature airflow generated by the continuous combustion of the fuel is convective conduction and flame heat radiation on the inner wall of the spherical tank, so that the spherical tank is heated to the temperature required for heat treatment.
[0022] Heat treatment process specification:
[0023] According to GB50094-2010 "Spherical Storage Tank Construction and Acceptance Specification", select the following heat treatment process parameters (see Table 1) and process curve (see figure 1 ):
[0024] Table 1: Heat treatment process parameter table
[0025] project Heating rate constant temperature constant temperature time Cooling speed Maximum temperature difference when heating and cooling Maximum temperature difference at constant temperature 50-80℃/h 625±25 1.92h 30-50℃/h ≤130℃ ≤50℃
[0026] details as follows:
[0027] 1. Heat treatment process system
[0028] This heat treatment project consists of fuel oil, oil supply, measurement, column leg movement and smoke exhaust system.
[0029] A: Fuel system
[0030] The fuel system adopts the Italian P450T/G light oil burner, the burner is connected to the manhole under the spherical tank, and a set of intelligent inspection system is used to intelligently control the heat treatment project to meet the process requirements. The fuel adopts No. 0 diesel to pass through. The oil is pumped by the oil pump and sprayed into the nozzle through the control of the solenoid valve. The burner blower is supplied with air from the bottom to support combustion, atomize the combustion oil, and the automatic electronic igniter ignites the fuel for combustion.
[0031] B: Oil supply system
[0032] The oil supply system consists of a fuel tank, a primary filter, a primary oil pump, an oil pipeline, a secondary filter, a flow meter, a high-pressure oil pump, and an oil return system.
[0033] C: temperature measurement control system
[0034] The temperature measurement and monitoring system intelligently measures and controls the temperature by thermocouples, compensation wires and a set of DR30 intelligent inspection instruments.
[0035] C-1 Measuring point layout
[0036] According to the requirements of the relevant technical standards of GB50094-2010 "Specification for Construction and Acceptance of Spherical Storage Tanks", a total of 12 temperature measurement points are set for this heat treatment. The temperature measurement points should be evenly arranged on the surface of the spherical shell, and the distance between adjacent temperature measurement points should be ≤4500mm , The temperature measurement point must be set within 200mm from the edge of the manhole and the annular seam of the spherical shell and on the product test plate. Please refer to the temperature measurement point layout diagram ( figure 2 , 3 ); image 3 It is the expansion diagram, unit: mm; A: equatorial belt plate; F: upper pole belt plate; G: lower pole belt plate; □ is the product test plate; ● is the temperature measuring point.
[0037] C-2 Thermocouple Installation
[0038] Press the bolt Figure II The thermocouple is required to be fixed on the outer surface of the spherical shell, and the flue gas and the test plate shall be provided with separate thermocouples. Compensation wires should be properly secured to prevent burnout. The thermocouple models are K-type nickel-chromium-nickel-silicon, and the compensation wire adopts K-type twin-core wire.
[0039] C-3 Temperature Monitoring
[0040] Two sets of temperature monitoring systems are configured, one is EH100-24 long graph automatic balance recorder, which can record 24 temperature measurement points, the other is DR30 intelligent patrol instrument temperature monitoring system, which can detect the temperature of each temperature measurement point on a tour , and print a temperature report for each point every 30 minutes according to the process.
[0041] 2. Insulation method
[0042] The insulation material of the spherical tank is made of aluminum silicate acupuncture blanket with a thickness of 50mm, and is fixed with φ6mm steel bar, M12 nut and 14# thin iron wire. It should be carried out in sequence from bottom to top. The inner and outer joints must be staggered from each other. The upper and lower adjacent insulation layers should overlap at least 200mm, and the left and right insulation layers should overlap at least 50mm. The joints should be tight. In order to prevent the installed thermal insulation cotton from collapsing and falling off, it should be tightened with 12# iron wire and a wire tightening machine on the outside according to the radial and weft directions of the spherical tank. Insulation cotton shall be added to the inlet holes and nozzles on the spherical tank, and the pillars within a length of 1m from the lower end of the welding seam connecting the pillar and the spherical tank shall be insulated. The effect of thermal insulation is specifically monitored by the speed of the intelligent inspection instrument patrolling one point every 3 seconds and once every half a minute or so. It can detect the defects of thermal insulation in time and generate a temperature difference signal alarm, prompting to remedy. ( Figure 4 )
[0043] 3. Simultaneous heat treatment of product test plate and spherical shell plate
[0044] In the heat treatment specification, the test plate and the spherical shell plate of the spherical tank are required to be heat treated by the same process. Therefore, it is stipulated that the test board should be placed in the temperate zone and three test boards should be placed at an interval of 120° to achieve synchronization. Temperature measurement points should be set on the test board, and the thermal insulation layer should be thickened to ensure that the temperature of the test board is the same as that of the spherical shell.
[0045] 4. Preparations before heat treatment
[0046] 4.1. The spheres, manholes, nozzles and pre-welded parts must be fully welded and passed the visual inspection and non-destructive inspection.
[0047] 4.2. After the non-destructive inspection work is completed and qualified, heat treatment shall be carried out. Other work like painting, water pressure needs to be done after heat treatment.
[0048] 4.3. The quality and geometric dimensions of the inner and outer surfaces of the spherical tank shall be inspected and qualified, and the records shall be complete.
[0049] 4.4. The welding inspection of the product test plate is qualified, and confirmed by the supervisory inspector, the test plate should be firmly fixed on the spherical shell.
[0050] 4.5. All original documents are complete, signed and approved by the responsible person for quality assurance, and confirmed by the supervisory inspection unit and Party A.
[0051] 4.6. All heat treatment system devices must be installed, and each system should be debugged.
[0052] 4.7. The power supply system has been fully checked and qualified and meets the requirements, and contact the relevant departments to ensure that the power supply is uninterrupted during the heat treatment.
