Catalytic combustion treatment process exhaust gas
Process exhaust gas characteristics:
Organic process tail gas emitted from process units of oil refining and petrochemical enterprises (organized emissions) has the following characteristics (take the tail gas of polypropylene plant as an example).
(1) Small fluctuations in concentration and flow rate.
(2) Organic process off-gas does not contain oxygen.
(3) High concentration tail gas with recovery value should first be recovered by the recovery process, and the recovered tail gas should be treated by catalytic combustion process to meet the standards, and the low concentration tail gas should be treated directly by catalytic combustion process.
(4) The exhaust gas may contain chlorides, sulfides and other components that can easily poison the catalytic combustion catalyst.
Main control program
In order to ensure the efficient, safe operation of the catalytic combustion process, the main control and interlocking schemes are as follows.
(1) Catalytic combustion reactor outlet temperature control - The outlet temperature control of the catalytic combustion reactor is achieved by adjusting the amount of circulating purge tail gas. When the outlet temperature of the catalytic combustion reactor is greater than the set value, increase the opening of the inlet regulating valve of the circulating blower, increase the circulating tail gas volume, and return the outlet temperature of the catalytic combustion reactor to the set value; when the outlet temperature of the catalytic combustion reactor is less than the set value, reduce the opening of the inlet regulating valve of the circulating blower, decrease the circulating tail gas volume, and return the outlet temperature of the catalytic combustion reactor to the set value.
(2) Catalytic combustion reactor inlet temperature control - The inlet temperature of the catalytic combustion reactor is achieved by adjusting the bypass regulating valve of the tail gas heat exchanger. When the inlet temperature of the catalytic combustion reactor is greater than the set value, increase the opening of the tail gas heat exchanger bypass adjustment valve, reduce the amount of heat exchange tail gas, so that the inlet temperature of the catalytic combustion reactor returns to the set value; when the inlet temperature of the catalytic combustion reactor is less than the set value, reduce the opening of the tail gas heat exchanger bypass adjustment valve, increase the amount of heat exchange tail gas, so that the inlet temperature of the catalytic combustion reactor returns to the set value.
(3) When the temperature measurement of catalyst bed of catalytic combustion reactor exceeds the set value, the temperature measurement of circulating tail gas cooler outlet exceeds the set value, the flow rate of circulating blower outlet is lower than the set value, the circulating blower stops running or the air blower stops running, the interlock will be triggered as long as one of the above conditions is met, i.e., close the tail gas regulating valve, open the tail gas venting valve, close the air blower and air regulating valve and stop the booster fan. booster fan.
Catalytic combustion treatment of wastewater treatment site waste gas
The waste gas discharged from the sewage treatment plant of oil refining and petrochemical enterprises has the following characteristics:
(1) Large fluctuations in concentration and flow rate.
(2) The exhaust gas from the sewage treatment plant contains sufficient oxygen.
(3) The concentration of non-total methane hydrocarbons from the front-end structures such as grease traps and flotation tanks is high, about 2,000-5,000 mg/m3, and the catalytic combustion process can be considered for direct treatment; the concentration of non-total methane hydrocarbons from the back-end structures such as aeration tanks and biochemical tanks is low, about 100-500 mg/m3, and if the catalytic combustion process is adopted directly, the energy consumption is high. The energy consumption for treatment is high, so the adsorption and concentration process can be considered before the catalytic combustion process.
(4) The exhaust gas from the sewage treatment plant contains hydrogen sulfide, mercaptan, thioether and other components that are likely to poison the catalytic combustion catalyst.
Main control scheme:
To ensure that the catalytic combustion process can operate efficiently, safely and smoothly when treating the waste gas from the wastewater treatment plant, the main control and interlocking schemes are as follows.
(1) Catalytic combustion reactor outlet temperature control - The outlet temperature control of the catalytic combustion reactor is achieved by adjusting the air volume. When the outlet temperature of the catalytic combustion reactor is greater than the set value, the opening of the air inlet regulating valve is increased to increase the air volume, so that the outlet temperature of the catalytic combustion reactor returns to the set value; when the outlet temperature of the catalytic combustion reactor is less than the set value, the opening of the air inlet regulating valve is reduced to lower the air volume, so that the outlet temperature of the catalytic combustion reactor returns to the set value.
(2) Catalytic combustion reactor inlet temperature control - The inlet temperature of the catalytic combustion reactor is achieved by adjusting the output power of the electric heater. When the inlet temperature of the catalytic combustion reactor is greater than the set value, the output power of the electric heater is reduced so that the inlet temperature of the catalytic combustion reactor returns to the set value; when the inlet temperature of the catalytic combustion reactor is less than the set value, the output power of the electric heater is increased so that the inlet temperature of the catalytic combustion reactor returns to the set value.
(3) When the inlet temperature of the catalytic combustion reactor exceeds the set value, the outlet temperature of the catalytic combustion reactor exceeds the set value, the internal temperature of the electric heater exceeds the set value or the electric heater fails, the interlock will be triggered as long as one of the above conditions is met, i.e., the exhaust gas inlet device is cut off, the air valve is fully opened and the electric heater is turned off.