【Q&A Question 022】May 12, 2016

When heating a furnace for drying, the following steps must be followed strictly: (1) Before starting the drying process, all manholes, viewing ports, explosion-proof doors should be opened, and the chimney baffles should be removed to allow natural ventilation for more than 5 days, after which ignition can take place to start drying the furnace. (2) At the start of furnace drying, open the chimney damper by about 1/3; once the temperature inside the furnace rises and the suction force increases, then open the chimney damper further. (3) Steam is introduced into the furnace tubes to start heating; once the temperature inside the furnace reaches 130°C, the burners can be ignited to continue with the drying process. (4) When heating the furnace, gas fuel burners should be used as much as possible for diagonal ignition. (5) During the furnace drying process, the temperature should rise evenly; the rates of heating and cooling should follow the specified drying curve, and the condition of the furnace walls should be monitored regularly. (6) Records should be kept during the furnace drying process, and the actual drying curve should be drawn after drying. (7) The furnace chamber is cooled at a rate of 20°C per hour. When the furnace temperature drops to 250°C, shut down the furnace and let it cool; once it reaches 100°C, allow natural ventilation. (8) After the furnace is dried, a thorough inspection of the furnace should be carried out; any defects found should be addressed. Liners with crack widths greater than 3 mm and depths exceeding 5 mm should be repaired; those with voids or separation from the steel plate must be thoroughly repaired

The last edit to this post was made by zhaozq2015 on 2016-5-12 at 07:52. 1. After the nitrogen airtightness of the hydrogen-handling system is initially verified as satisfactory, and after the process flow has been checked three times to confirm its accuracy, the pressure is maintained at 1.5 MPa; the compressor is started for full-cycle operation, and the air-cooling fans are activated along with the heat exchangers. 2. In accordance with the furnace operating procedures, the furnace chamber is purged with steam before ignition to ensure it is in good condition. 3. Open the flue dampers to 1/3 or -1/2 of their full opening, slightly open the air valves, light a kindling rod outside the furnace, and insert it through the ignition hole near the pilot light. Slowly open the pilot light hand valve, light the pilot light, adjust the flame using the air damper, and then add more main burners as needed. Adjust the dampers and flue baffles according to the burning conditions. During the ignition process, a dedicated person should be present to monitor the situation and prevent issues such as backflow caused by unstable pressure in the fuel pipeline network. 4. After maintaining the furnace temperature at a constant level for 24 hours via the heating furnace, the temperature is reduced at a rate of 10 degrees per hour until it reaches 150 degrees, after which the furnace is turned off. The blower is stopped, and the air duct baffles as well as the flue duct baffles are adjusted to the closed position; the furnace is then left to stand for one day. When the furnace chamber is cooled to 100 degrees, the manholes, viewing windows, and flue dampers can be opened to allow natural ventilation until the temperature returns to normal. 5. When the furnace temperature reaches 400–500 degrees, in order to prevent dry burning of the furnace and damage to the furnace tubes, a fluid (such as steam or nitrogen) can be passed through these tubes. The flow rate of the fluid is determined by the wall temperature of the pipe. 6. Turning off the furnace allows the nitrogen circulation to be stopped. 7. During the cooling process, test each burner to see if it works properly.

1. All bypass flue dampers are opened, and the damper in the boiler flue is closed. 2. Based on the temperature reading from the thermocouple, gradually open the boiler flue dampers to ensure that the flue temperature rises in accordance with the furnace drying curve. 3. If the flue temperature does not meet the requirements of the furnace drying curve after the boiler flue dampers are fully opened, the dampers of the bypass flue can be closed appropriately. 4. During the furnace heating process, there must be a medium inside the furnace tubes.

This post was last edited by wangld on 2016-5-12 08:29. 1. After the nitrogen airtightness test of the hydrogen system is initially successful, and the process flow has been checked three times to confirm its accuracy, the high-pressure level is controlled at 1.5 MPa; the compressor is started for full-cycle operation, the air-cooling fans are activated, and the heat exchangers come into use. 2. In accordance with the furnace operating procedures, the furnace chamber is purged with steam before ignition to ensure it is ready for use. 3. Open the flue baffle to 1/3–1/2 of its full opening, slightly open the air damper, light a kindling rod outside the furnace, and insert it through the ignition hole near the pilot light. Slowly open the pilot light hand valve, light the pilot light, adjust the flame using the air damper, and then add more main burners as needed. Adjust the dampers and flue baffles according to the burning conditions. During the ignition process, a dedicated person should be present to monitor the situation and prevent issues such as backflow caused by unstable pressure in the fuel pipeline network. 4. After maintaining the furnace temperature at a constant level for 24 hours via the heating furnace, the temperature is reduced at a rate of 10 degrees per hour until it reaches 150 degrees, after which the furnace is turned off. The blower is stopped, and the air duct baffles as well as the flue duct baffles are adjusted to the closed position; the furnace is then left to stand for one day. When the furnace chamber is cooled to 100 degrees, the manholes, viewing windows, and flue dampers can be opened to allow natural ventilation until the temperature returns to normal. 5. When the furnace temperature reaches 400–500 degrees, in order to prevent dry burning of the furnace and damage to the furnace tubes, a fluid (such as steam or nitrogen) can be passed through these tubes. The flow rate of the fluid is determined by the wall temperature of the pipe. 6. Turning off the furnace allows the nitrogen circulation to be stopped. 7. During the cooling process, test each burner to see if it works properly.

(1) Before heating the furnace, all manholes, viewing doors, explosion-proof doors should be opened, and the chimney baffles should be removed to allow natural ventilation for more than 5 days, after which ignition for heating the furnace can begin. (2) At the start of furnace drying, open the chimney damper by about 1/3; once the temperature inside the furnace rises and the suction force increases, then open the chimney damper further. (3) Steam is introduced into the furnace tubes to start heating; once the temperature inside the furnace reaches 130°C, the burners can be ignited to continue with the drying process. (4) When heating the furnace, gas fuel burners should be used as much as possible for diagonal ignition. (5) During the furnace drying process, the temperature should rise evenly; the rates of heating and cooling should follow the specified drying curve, and the condition of the furnace walls should be monitored regularly. (6) Records should be kept during the furnace drying process, and the actual drying curve should be drawn after drying. (7) The furnace chamber is cooled at a rate of 20°C per hour. When the furnace temperature drops to 250°C, shut down the furnace and let it cool; once it reaches 100°C, allow natural ventilation. (8) After the furnace is dried, a thorough inspection of the furnace should be carried out; any defects found should be addressed. Liners with crack widths greater than 3 mm and depths exceeding 5 mm should be repaired, while those with voids or separation from the steel plate must be thoroughly repaired.

1 Reaction section: 1) Initial airtightness testing of the system with nitrogen, followed by steam testing； 2) Unit and pump operation in conjunction, interlock verification ； 3) Instrument calibration: Install and calibrate the instruments in the order of commissioning ； 4) Introduce gas to heat the furnace for drying ； 5) Combined operation of hot nitrogen and oil ； 6) Catalyst loading ； 7) Catalyst drying, nitrogen atmosphere ； 8) System hydrogen airtightness ； Emergency pressure relief test ； 9) Introduction of low-nitrogen oil for vulcanization ； 10) Switch to wax oil to produce qualified products. 2. Fractionation system: 1) System nitrogen airtightness ； 2) Water intermodal transport ； 3) Due to the start of diesel-cool oil combined operation ； 4) Instrument calibration ； 5) Hot oil transportation, furnace heating ； 6) Boiler flushing with waste heat steam generator ； 7) Heat tightening ； 8) The reaction product is obtained as oil.

Develop a plan: first dry the chimney, then the boiler; add chemical reagents to the boiler and clean it. Raise the temperature gradually from low to high, stop increasing the temperature once a certain level is reached, and observe the situation. Only after stability is achieved should the temperature be raised further. The entire process must follow the appropriate heating curve

1. Light the furnace and raise the temperature； 2. Heat to 120°C and maintain at this temperature for 24 hours ； 3. The liquid level in the water separation tank does not rise; the lining dehydration is complete.

(1) Before heating the furnace, all manholes, viewing doors, explosion-proof doors should be opened, and the chimney baffles should be removed to allow natural ventilation for more than 5 days, after which ignition for heating the furnace can begin. (2) At the start of furnace drying, open the chimney damper by about 1/3; once the temperature inside the furnace rises and the suction force increases, then open the chimney damper further. (3) Steam is introduced into the furnace tubes to start heating; once the temperature inside the furnace reaches 130°C, the burners can be ignited to continue with the drying process. (4) When heating the furnace, gas fuel burners should be used as much as possible for diagonal ignition. (5) During the furnace drying process, the temperature should rise evenly; the rates of heating and cooling should follow the specified drying curve, and the condition of the furnace walls should be monitored regularly. (6) Records should be kept during the furnace drying process, and the actual drying curve should be drawn after drying. (7) The furnace chamber is cooled at a rate of 20°C per hour. When the furnace temperature drops to 250°C, shut down the furnace and let it cool; once it reaches 100°C, allow natural ventilation. (8) After the furnace is dried, a thorough inspection of the furnace should be carried out; any defects found should be addressed. Liners with crack widths greater than 3 mm and depths exceeding 5 mm should be repaired, while those with voids or separation from the steel plate must be thoroughly repaired.

Plan for boiler drying and soaking before commissioning I. The following conditions must be met prior to drying the boiler: 1. The boiler and all its auxiliary devices must be fully assembled, and the hydraulic test must have been successful. 2. End of heat retention. 3. The thermal instruments of the boiler must be calibrated properly; the reliability of the boiler’s water supply source should also be checked, and water should be supplied to the boiler until it reaches the normal level. 4. Once the auxiliary equipment required for furnace drying, such as water pumps and fans, have completed their trial runs, and it is confirmed that all components are in conditions to start operating safely, the furnace drying process can begin. II. Oven drying methods and precautions 1. Oven drying should be carried out using methods such as flame or steam, depending on the specific conditions on site; necessary temporary measures must be put in place before drying the oven. 2. When using a flame furnace, the following requirements must be met: 2.1 The flame should be located in the center of the furnace, burning evenly without any interruptions ； 2.2 The furnace drying temperature should be controlled based on the flue gas temperature at the furnace outlet. Drying of the furnace can begin only after the normal curing period has elapsed (approximately 3 days for alumina cement). The furnace should be kept at this high temperature for at least one day; the rate of temperature increase should not exceed 80°C per day, and the flue gas temperature should not exceed 160°C at later stages. III. Boiler Cleaning 1. Purpose of boiler cleaning: NaOH and Na3PO4 are added to the boiler for chemical treatment; alkaline cleaning is used to remove oil, deposits, and rust from within the boiler, thereby ensuring even heat distribution and proper operation of the boiler. 2. Furnace soaking methods and precautions 2.1 Furnace soaking can be carried out as early as toward the end of the drying process. 2.2 The amount of chemicals to be added during furnace heating should comply with the specifications stated in the equipment’s technical documents. Note: 1. The purity of the chemicals is assumed to be 100%. 2. In the absence of trisodium phosphate, sodium carbonate can be used as a substitute, in an amount equal to 1.5 times that of trisodium phosphate. 3. Sodium carbonate can be used alone for boiler cleaning, at a rate of 6 kg/m3 of water. 2.3 The medication should be dissolved into a solution and added to the boiler; care must be taken to ensure safety when preparing and adding the medicinal solution. 2.4 During chemical dosing, the boiler water level should be at a low level. 2.5 To ensure effective boiler cleaning, the operating pressure should be maintained at around 75% of the normal operating pressure toward the end of the cleaning process. The boiler cleaning time should generally be 2 to 3 days; if the cleaning is carried out at a lower steam pressure, the time required should be appropriately extended. 2.6 The boiler heating time requires regular sampling from the drum to analyze the alkalinity of the boiler water. The boiler water alkalinity should not be lower than 45 mg-eg/L; otherwise, chemicals should be added to compensate. 2.7 After the boiler has been boiled, the sediment in the drum should be removed. Flush the inside of the boiler and valves that have been in contact with the chemical solution, and check whether the drain valve is clogged. 2.8 The boiler shall meet the following requirements: A. The inner surface of the boiler drum shall be free from oil deposits. B. After removing the deposits, the metal surface should be free of rust spots. 2.9、Blowing of steam pipes: The superheaters and their pipes must be blown before steam is supplied to them, in order to remove any debris and rust from within the pipes. 2.9.1 The cross-sectional area of all temporary pipes shall be greater than or equal to that of the pipe being cleaned; temporary pipes should be as short as possible to reduce resistance. 2.9.2 During purging, the valve should be fully open; the pressure at the superheater outlet when it is fully open is 1.0 Mpa. 2.9.3 The purging time is generally less than 1 minute, and the decrease in saturation temperature is not more than 42°C (the pressure drop is approximately not more than 0.6 MPa). 2.9.4 During the purging process, there should be at least one shutdown for cooling (for more than 12 hours) to improve the effectiveness of the purging. 2.9.5 The blowdown test is considered successful if the particle size of the impact marks on the target plate (with a width of 8% of the inner diameter of the exhaust pipe) is no greater than 0.8 mm, and there are no more than 8 such marks. 2.9.6 After the purging is completed, records should be organized and approvals obtained. IV. Steam Test 1. After the furnace has been dried and boiled successfully, the steam tightness test should be carried out following these steps: (1) Heat the system and increase the pressure to 0.3–0.4 Mpa, then tighten the bolts of the flanges, manholes, and other connection points within the boiler area while the system is still hot ； (2) Continue to increase the pressure to operating pressure to carry out the following inspections: (2-1) The sealing performance at each manhole, valve, flange, gasket, etc ； (2-2) Expansion of boilers, pipelines, supports, etc ； 2. After the above checks are passed, the safety valves must be adjusted, and such adjustment shall meet the following requirements: a) The safety valves on the boiler drum and superheater shall be adjusted in accordance with the \"Safety Technical Inspection Regulations for Steam Boilers\", with the setting pressure being 1.04 times the operating pressure at the location where they are installed ； b. The safety valve should show no steam leakage or shock phenomena ； 3. After the above tasks are completed successfully, the boiler should be operated continuously under load for 4 to 24 hours. During the trial operation, checks should be carried out to ensure that all components and auxiliary equipment are functioning properly; this is considered satisfactory.