Fluidized bed|1 set
Hydrogen press | 2 sets
Pump front buffer tank | 3m3|1 set
Pump after buffer tank | 3m3 | 1 set
O-nitrotoluene intermediate tank |25m3|2 sets
Catalyst loading and unloading tank |20m3|1 set
Crude aniline intermediate tank |25m3|2 sets
Exhaust trap |2000L|Enamel kettle|1 set
O-nitrotoluene large storage tank |500m3|1 set
O-nitrotoluene preheater |Horizontal double pipe|F=23m2|1 set
O-nitrotoluene gasifier |F=110m2|1
Hydrogen heat exchanger F=220m2|1 set
O-toluidine cooler F=220m2|3 sets
Thermal oil furnace (200,000 kcal heat)|1
The project uses 4-nitrotoluene as raw material. The main processes include preheating, vaporization, superheating, reduction, condensation, separation, dehydration and rectification. The specific process flow is as follows:
(1) Preheating 4-nitrotoluene is preheated into a preheater, and the preheating temperature is 140~150 °C; the hydrogen gas is driven into the jacket of the heat exchanger by a hydrogen compressor for preheating, and the preheating temperature is 120 ° C. At the start of the process, the steam generated by heating the soft water by the heat transfer oil furnace is used for preheating, and after the process is started, the steam produced by the fluid bed reaction is used for preheating.
(2) Vaporization The preheated 4-nitrotoluene and hydrogen are driven into a vaporizer to completely vaporize and fully mix the raw materials. In the vaporization process, steam is indirectly heated, and the heating temperature is about 160 to 180 °C.
(3) Overheating Then the raw material is driven into the superheater, heated to 190-220 ° C, and indirectly heated by heat transfer oil. Reduction: the superheated 4-nitrotoluene and hydrogen are added to the fluidized bed reactor to reduce the reaction under the action of the copper catalyst, and the NO2 on the 4-nitrotoluene is reduced to NH2 by H2 to form p-toluidine. The reaction control temperature was 270 ± 5 ° C, and the reaction was an exothermic reaction. The copper catalyst is replaced approximately three years.
(4) Temperature rise activation of the catalyst The newly purchased copper catalyst catalyst is introduced into the fluidized bed from the feed port, and copper is attached to the surface of the silica gel in the form of Cu(OH)2, and the new catalyst needs to be regenerated and activated. The specific process is as follows: after the system is sealed, the system air is replaced with nitrogen, the compressor is turned on to circulate the gas, and then heated by indirect steam. When the temperature is raised to 200 ° C, hydrogen is slowly introduced, and the nitrogen is gradually evacuated. Hydrogen first reduces Cu(OH)2 to CuO, and then reduces to elemental copper, and activated water is formed. Control the amount of hydrogen to increase the temperature of the catalyst evenly. When the temperature of the fluidized bed drops from the highest point and the condensed activated water disappears, and the bed temperature is maintained at 180~200 °C for 4~5 hours, the total hydrogen purity reaches 99.7% or more. The activation is over.
(5) Regeneration of the catalyst After the reaction for a certain period of time, it is generally about one month. Due to the high local temperature and other reasons, a small amount of carbon deposits on the surface of the catalyst, the catalyst gradually loses its activity. When the nitro content of the reduction end point exceeds 0.5% for three consecutive times , the catalyst needs to be regenerated. The specific process: first stop feeding, by overheating The heat of the fluid is maintained at a temperature of about 180 °C. The air is introduced into the buffer tank before the pump, so that the surface area of the catalyst is oxidized to carbon dioxide and water, and the bed temperature is gradually increased. At this time, the superheater is stopped to be heated, and the air volume is adjusted to increase the bed temperature by 15 to 20 ° C / h. The temperature of the chemical bed should be kept at 380~400 °C, and the temperature at the filter tube should not exceed 350 °C. The process is about 40h.
(6) condensing the fluidized bed reactor to give the product enters the heat exchanger and sequentially three tube condenser, the heat exchanger is heated while hydrogen is also the product of the condensation. The three-stage tubular condenser is condensed by circulating cooling water, and the condensation efficiency of the heat exchanger and the three-stage tubular condenser is 99.9%. The condensed non-condensable gas is trapped by the tail gas trap, separated into hydrogen and crude products by filtration through a filter, and the circulating hydrogen gas enters the vaporizer through the hydrogen buffer tank, and the crude product enters the continuous separator.
The final product is obtained through a process of separation, dehydration, rectification, azeotropy, and the like. This product is continuously fed.