process flow
The gas from the benzene washing tower enters the desulfurization tower, and the gas is in countercurrent contact with the lean liquid from bottom to top.
Acid gases such as H2S and HCN in Y gas are absorbed, and the main reactions are as follows:
At the same time, a certain amount of alkali liquor (NaOH) is added to the upper part of the desulfurization tower to further remove H2S from the gas.
Make the H2S content in the gas ≤200mg/m3. Part of the desulfurization gas is sent back to the coke oven and crude benzene pipeline. '
The stove is heated and used, and the rest is distributed to users. Rich liquid with acid gas absorbed comes from the bottom of the regeneration tower.
After heat exchange, the hot lean liquid enters the regeneration tower from the top for regeneration, and the regeneration tower runs at vacuum and low temperature, rich in liquid.
J6 u* p8 ` 1 k% ~: E" d" p) f0 B contacts with the rising steam at the bottom of the regeneration tower to desorb acidic components, and the reaction is as follows:
The acid gas from the top of the regeneration tower enters the condensation cooler, and after water is removed, the acid gas is pumped out by a vacuum pump.
Sent to the acid-making section. The lean liquid at the bottom of the regeneration tower is pumped out by the desulfurization liquid circulating pump and sent to the upper part of the primary cooler.
The waste heat recovery part exchanges heat with gas. After heat exchange, the desulfurization liquid flows into the desulfurization liquid circulation tank, and then
Desulfurization liquid is pumped by feed pump and sent back to the bottom of regeneration tower. It generates steam 8 through a flash device at the bottom of the regeneration tower.
Steam is used as the heat source for rich liquid regeneration in the regeneration tower. In order to ensure the stable operation of the regeneration tower, rich liquid regeneration is needed.
Set 1 steam reboiler with 0.4MPa steam as auxiliary heat source. regenerate
After heat exchange between the lean liquid and the rich liquid and cooling by the cooler, the lean liquid enters the absorption tower from the top of the tower for recycling. In the system
A small amount of KCNS and K4Fe(CN)6 salt solution generated by the side reaction is sent to the cold drum section, and the remaining ammonia $ I* y- i+ B( ~' C).
The sink.
) process characteristics * [) ]3 B) m \% s' N+ \
1) The desulfurizer adopts KOH(2KOH +CO2=K2CO3+H2O), which has low cost and simple operation.
1 E S+P3 S 1 P2) rich liquid regeneration adopts vacuum desorption method, and the operating temperature is low, because the oxygen content in the system is low and the side reaction speed is low.
# k！ f2 w % u & ampi5 y 1 l s； B is slow, resulting in little waste liquid and low alkali consumption.
3) Rich liquid regeneration mainly uses waste heat of raw gas to save steam heat consumption;
Low regeneration temperature and weak corrosiveness. The absorption tower, regeneration tower and most equipment are made of carbon steel, which saves investment.
The alkaline solution (NaOH) needed to fix ammonium salt in the residual ammonia water is added to the upper part of the desulfurization tower for further removal. C.
Besides H2S, gas has two uses, one is raw material.