(1) Oxygen enters the reformer after being preheated in the convection section of the preheating furnace, and coke oven gas enters the reformer after being preheated in the radiation section of the preheating furnace. The process of preheating coke oven gas and pure oxygen in one preheating furnace at the same time does not have the same design in domestic methanol plants of the same type. However, there is an intrinsic safety problem in this design, that is, once a large amount of leakage occurs in the oxygen coil of the preheating furnace, or a small amount of leakage occurs without timely detection and shutdown measures, high-temperature oxygen will lead to major accidents in the preheating furnace; more seriously, If the oxygen pipeline in the preheating furnace leaks a lot, and the high temperature gas at about 1000 ℃ in the reformer flows back into the oxygen pipeline, it will also cause a secondary accident, and the consequences will be more serious. The two previous oxygen pipeline leaks were found in time, handled correctly and decisively, to avoid the occurrence of vicious accidents. (2) In the original design of the preheating furnace, there is no "permanent light". After the fuel gas leaks in the furnace or the flame is instantaneously extinguished, the fuel gas will inevitably accumulate in the furnace and mix with the air to form an explosive gas. (3) The combustion-supporting air of the preheating furnace is designed to be forcedly supplied by the air blower. Once the combustion-supporting air blower fails, the combustion-supporting air supply of the preheating furnace must be stopped. At this time, the preheating furnace must quickly cut off the fuel gas and extinguish the flame, otherwise it will inevitably cause A large amount of fuel gas accumulates in the hearth of the preheating furnace, which is very likely to explode, and after the preheating furnace is turned off, the coke furnace gas, steam and oxygen cannot be preheated, and the heat required for the conversion reaction in the subsequent process cannot be provided. Parking is required. Therefore, the combustion-supporting air of the preheating furnace is only designed to be forced air by the blower, which has inherent safety hazards. (4) The flame detection protection system is not set in the design of the preheating furnace. After the preheating furnace is extinguished, the fuel gas cannot be automatically interlocked and cut off, which will inevitably lead to a large accumulation of fuel gas in the furnace chamber of the preheating furnace, which is very likely to explode.