Condensate stripper

After acid gas removal the pyrolysis gas from the last stage of compression is cooled by propylene refrigerant and sent to a condensate stripper. This tower separates the C and heavier products, which exit the bottom, from the and lighter components. 

Tower Internals and Equipment Modification. Tower capacity expansion can be achieved through the use of random or stmctured packing, or through the use of higher capacity trays such as the UOP multiple downcomer tray. Packing has been used in the gasoline fractionator, water quench tower, caustic and amine towers, demethanizer, the upper zone of the deethanizer, debutanizer, and condensate strippers. Packing reduces the pressure drop and increases the capacity. 

Evaporator, condensate stripper, and black liquor oxidation systems. 

Description The gas feedstock is compressed (if required), desulfurized (1) and process steam is added. Process steam used is a combination of steam from the process condensate stripper and superheated medium pressure steam from the header. The mixture of natural gas and steam is preheated, prereformed (2) and sent to the tubular reformer (3). The prereformer uses waste heat from the flue-gas section of the tubular reformer for the reforming reaction, thus reducing the total load on the tubular reformer. Due to high outlet temperature, exit gas from the tubular reformer has a low concentration of methane, which is an inert in the synthesis. The synthesis gas obtainable with this technology typically contains surplus hydrogen, which will be used as fuel in the reformer furnace. If C02 is available, the synthesis gas composition can be adjusted, hereby minimizing the hydrogen surplus. Carbon dioxide can preferably be added downstream of the prereformer. 

In new plants the high-pressure condensate stripper recycles condensate pollutants. 

The deethanizer bottoms and condensate stripper bottoms from the charge compression system are depropanized (12). Methylacetylene and propadiene are hydrogenated in the depropanizer using CDHydro catalytic distillation hydrogenation technology. The depropanizer bottoms... 

The uncondensed gas from the surface condenser is vented to the atmosphere throi Qh the final absorber where CO2 and NH3 accompanied by the inerts are absorbed into process condensate from the first stage of the surface condenser under atmospheric pressure. The emission of NH3 from the scrubber is less than 0.15 kg NHa/tonne of urea. The process condensate formed in the second stage of the surface condenser is treated in the process condensate stripper at 3 MPa to remove NH3 and CO2. Gas is fed into the urea hydrolyzer at 16 MPa. The overhead gaseous mixture from the process condensate stripper is sent to the low-pressure decomposer for recovery of NH3, CO2, and heat of water vapors. 

Recontact drum over condensation Stripper inefficiency Stripper turndown problems Cyanides cause hydrogen blistering... 

Pig. 9.12 Flow-sheet for KBR advanced ammonia process 1-Air compressor 2,12,28,33,34-Cooling 3-Feed gas compressor 4-Waste heat boiler 5-Primary reformer 6-Secondary reformer 7,9,11,15,20,22,26,27,30-Heat recovery 8-HTS 10-LTS 16-Condensate stripper 17-C02 absorber 18-C02 stripper 21-Methanator 24-Dryer 25-Synthesis gas compressor 29-KAAP ammonia converter 32-Refrigeration compressor. 

As methanol emissions continue to be monitored more closely, there are some methods of reducing the methanol in the deaerator vent. The vent stream could be condensed and sent to the reformer or the steam system. Catalytic combustion could be used to reduce the methanol. A scrubber system could be added to remove the methanol. In some instances a condensate stripper is added instead of the deaerator to remove the ammonia, methanol, and other contaminants from the condensate. This system recycles the vent stream to the reformer as process steam and the bottoms are mixed with the incoming boiler feedwater makeup. However, this system adds considerable capital cost to a project. 

The bottoms liquid from the deethanizer serves as the principal feed to the depropanizer. A second feed stream to this column consists of the bottoms liquid from the condensate stripper for the fourth and fifth compression stages. The primary function of this column is propylene and propane recovery from these two feeds. The column operating pressure typically will be 240 to 340 psia, which is sufficient to condense the over-... 

The feed gas saturator is used to transfer the low-level energy in the fuel gas into process steam. Hot boiler feed water or process condensate is contacted with cold natural gas in the saturator, whereby the natural gas is preheated, and, at the same time, saturated with water. The water leaves the saturator, make-up water or condensate is added and the water is then reheated in a coil in the reformer waste heat section. About 20% of the required process steam may be taken up by the natural gas in the saturator. The energy saving is typically around 0.10 Gcal/MT ammonia. The saturator also serves as a process condensate stripper whereby overall water consumption may be reduced, and a pollution problem may be solved. The choice between combustion air preheat and saturator depends on local conditions. Combustion air preheat saves fuel directly whereas the saturator saves steam. 

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