Problems encountered by gasification units during commissioning and operation

There’s a reward! ! ! ! ! ! ! ! ! ! !

There are many different types of gasification units as well. Are you referring to the Texaco gasification unit or the SHELL gasification unit?

The main problems that occur during the commissioning or operation of SHELL are: 1. The coal grinding system has poor airtightness ； 2. The insulation effect of some steam tracing/electrical heating equipment and pipes is poor ； 3. The diesel system is not clean, and the pressure in the oil system is insufficient and unstable ； 4. The reducer followed by the eccentric pipe on the coal powder circulation pipeline is prone to wear and tear ； 5. Fault in the external power, steam, and water supply system ； 6. Inflation cone blockage and rupture ； 7. Damage to the pilot burner tip ； 8. Coal burner cover damaged ； 9. Fault in the quench gas compressor; the quench gas compressor system has weak resistance to external fluctuations ； 10. Deformation and damage of the inlet filter of the boiler feedwater circulation pump ； 11. Factors such as impurities in the coal powder can cause fluctuations in the coal powder flow rate or frequent coal changes, leading to unstable operation of the gasifier ； 12. The slag protective layer inside the gasifier is unstable, and it is difficult to accurately and visually determine the thickness of the protective slag layer on the inner wall of the gasifier ； 13. Fault in the ash water treatment system; blockages in the equipment and pipelines of the slag water system ； 14. Chain break in slag skimmer ； 15. Damage to the internals of the fly ash filter ； 16. Damage to the quenching zone of the gasifier ； 17. The water inlet nozzles of the gasifier’s water wall are blocked by foreign objects ； 18. Dust accumulation in the syngas cooler.

It is necessary to maintain good fluidity of the coal powder and stability in its transportation; otherwise, bridging and blockages in the gasification cone may occur, and it will also make it difficult to control the O/C ratio in the gasifier, leading to a series of consequences. Points to note: ① Keep the moisture content of dry coal powder between 1% and 2% ； ② Ensure that coal powder is not stored in a nitrogen-filled container for too long (less than 10 days) ； ③ Ensure good insulation for the dry coal powder system, so that the coal powder temperature remains above 80 ℃ ； ④ Control the particle size of the coal powder after grinding, ensuring that the proportion of coal powder with a particle size of less than 5 μm is less than 10% ； ⑤ Add fiber screens to prevent foreign materials from entering the coal powder (it also helps prevent clogging of the coal powder control valves) ； ⑥ Control the balanced pressure to prevent poor discharge of V-1204 due to coal powder compaction ； ⑦ Control the slow pressurization of V-1205 to the operating pressure of the gasifier plus 0.8 MPa, to ensure an adequate amount of gas is supplied to the filling cone of V-1205 and to prevent the coal powder in V-1205 from compacting ； ⑧ Pay attention to the installation and initial calibration of the coal powder mass flow meter.

Device management: 1. Control the pressure difference at the cone section to prevent it from becoming too high ； 2. For V-1204, the amount of N2 entering the inflation cone should be controlled, or its structure should be modified by replacing the sintered metal structure with a porous plate structure. 3. Ignition burner, startup burner ① Pay attention to the installation of the ignition burner and the startup burner to prevent mechanical damage to the burners or damage to the water wall of the gasification furnace ； ② Keep the pilot burner and startup burner passages clean to prevent damage to the burner nozzles or blockages in the passages ； ③ A gas buffer tank should be installed on the oxygen main to prevent the shutdown of the burning burner when the first coal burner comes online ； ④ Make sure to check the consistency between the manufacturer’s control system and the device’s control system. 4. Boiler feedwater and circulation system: ① Ensure the effective filtration area of the filter at the inlet of the boiler feedwater circulation pump, as well as the mesh size and pressure difference, in order to avoid damage ； ② Ensure the quality of the boiler feedwater to prevent scaling, which could cause damage to the water wall tubes and the boiler feedwater circulation pump ； ③ It is essential to ensure the reliability of power supply for the boiler feedwater circulation pump; in the event of a sudden power outage, it can prevent heat from the water-cooled walls at the bottom of the gasifier from being removed in time, thereby causing damage to those water-cooled wall tubes. To prevent damage to the cooling jacket and expansion joints of the coal burner, double-sided welding must be carried out on the burner cover during assembly, with the expansion joints filled with refractory material ； ② Temperature measurements have been added at the inlet and outlet of the coal burner cooling water to facilitate real-time monitoring of the coal burner. 6. To prevent damage to the ceramic tubes of the fly ash filter, the connection between the venturi and the tube sheet should be strengthened, and a connector should be installed between the venturi and the backflushing nozzle. 7. Prevent damage to the coal burner cover ① Pay attention to the length of the coal burner extending into the gasifier ； ② Appropriately increase the cooling water flow rate to the burner cover ； ③ Maintain the stability of the coal powder conveying system ； ④ Maintain stable coal quality (if changing the type of coal, it is necessary to adjust all relevant process control parameters promptly) ； ⑤ Pay attention to the addition of vaporized and temperature-regulated steam ； ⑥Appropriately reduce the oxygen-coal ratio ； ⑦ The viscosity of the slag is adjusted by the amount of flux used.

Other issues to consider in project construction: ① The supply and installation of the gasifier are the most critical aspects of the Shell gasification project; properly handling related tasks will help to shorten the project construction timeline； ② Increasing the number of qualified suppliers for key equipment in Shell’s gasification plants, accelerating the localization of such key equipment and instruments, and speeding up the optimization of the plant systems all contribute to reducing the investment required for plant construction ； ③ Tasks such as the clean installation of the vapor system in the gasifier, heating up the refractory lining inside the gasifier, debugging of the constant-force crane, testing the vapor system, individual and combined testing of the instrumentation and control systems, and the mechanical completion inspection of the facility are all very important and require special attention ； ④ The coal grinding and coal drying systems should be built before other processes, so as to produce qualified coal powder first and carry out calibration of the coal powder flow measurement system; this will create the conditions necessary for feeding chemicals into the gasifier.