Process water stripper

Olefins Process water stripper A bottom downcomer installed bade-ward caused a restriction between the downcomer bottom and the seal pan walL Qrdic flooding resulted. Ensure adequate inspection even when internal is hard to get at. 

Wet oxidation systems are used for very dilute acid gas and for total sulfur removal in small plants. However, wet oxidation systems cannot convert COS, nor can they process water stripper gases. 

All the process water streams are collected, the entrained hydrocarbons decanted, and the water is sent to the waste water stripper. 

As an introduction to the technical aspects of the conference, the results of some studies conducted by the writer on two relevant subjects are presented below. The first commentary is concerned with the design of sour-water strippers and the effects of thermodynamic data on these designs the second commentary is concerned with the calculation of enthalpies of steam-containing mixtures, essential to the design of coal processing and related plants. 

Alkylation generates relatively low volumes of wastewater, primarily from water washing of the liquid reactor products. Wastewater is also generated from steam strippers, depropanizers, and debutanizers, and can be contaminated with oil and other impurities. Liquid process waters (hydrocarbons and acid) originate from minor undesirable side reactions and from feed contaminants, and usually exit as a bottoms stream from the acid regeneration column. The bottoms stream is an acid-water mixture that is sent to the neutralizing drum. The acid in this liquid eventually ends up as insoluble calcium fluoride. 

Some refineries neutralize the caustic with spent sulfuric acid from other refining processes, and charge it to the sour water stripper. This removes the H2S. The bottoms from the sour water stripper go to the desalter, where the phenolics can be extracted by the crude oil. 

For convenience, the discussion of materials for these various processes is divided into five chapters. Crude units and utilities are discussed in this chapter. FCCs, fluid cokers, delayed cokers, sour water strippers, and sulfur plants are covered in Chapter Two. Desulfurizers, reformers, hydrocrackers, and flue gas are discussed in Chapter Three. Hydrogen plants, methanol plants, ammonia plants, and gas treating are discussed in Chapter Four. Underground piping, pipelines, production equipment, and tankage associated with the refinery industry are covered in Chapter Five. Discussed throughout these chapters are many common environments and equipment (e.g., sour or foul water, distillation, etc.) that appear in the various types of refinery process plants. 

Redirect sour water stripper vent gas from flare to sulfur plant Use gas from crude vacuum unit as fuel rather than as flare Adjust process conditions to reduce flare gas generation FCU... 

The volatile hydrogen sulfide (b.p. —60.7°C) is then separated as an overhead gas stream. The monoethanolamine (b.p. 170°C) and diethylene glycol (b.p. 245°C) emerge as a regenerated solution, hot, from the bottom of the stripping column. To conserve heat, the hot, H2S-lean monoethanolamine stream from the stripper is heat exchanged with the cooler H2S-rich stream from the base of the absorber, sometimes with additional cooling with process water before it enters the absorber. 

The sour-water stripper removes contaminants from condensed water and wash water used in various process units. The water may then be reused, for example, as desalter wash water or to water-wash light gas streams. In this process, the contaminants such as H2S are removed by stream stripping of the water. Figure 9 is a general diagram of a sour-water stripper. 

Watkins, R.N. Sizing Separators and Accumulators. Hydrocarbon Processing, November 1967, p. 253. Walker, G.J. Design Sour Water Strippers Quickly. Hydrocarbon Processing, June 1969, p. 121. 

Fig. 5.6. PHOSAM-W-process. (a) Sour water stripper, (b) absorber, (c) 1-7 condenser/heat exchanger, (d) stripper, (e) fractionator... 

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. 

In a process simulation, they play a decisive role for the mass balance in a decanter, operating at = 50 °C, and in a waste water stripper, operating at 2 = 2.3 bar, corresponding to a temperature 1 2 = 125 C. The task of the stripper is to take the organic components overhead to simplify the biological waste water treatment. Check whether the parameters can be used in the process simulation. If not, replace them by appropriate ones. 

Cilastatin - a bulk active pharmaceutical. Merck Co produce an antibiotic Primaxin (cilastatin (22) + imipenem (6)). To produce cilastatin, a process using methylene chloride was used. Methylene chloride features on the US Toxic Release Inventory (TRI) and elimination of emissions from chemical processes has become a priority. Merck have developed a novel process avoiding the use of methylene chloride altogether [13]. The new process, which cost some US 34 million to implement, required a further expenditure of some US 5 million on a fume stripper and US 500 000 on a waste water stripper. However, they claim to have cut their total TRI air emissions by more than 160 tonnes, of which 150 tonnes would have been methylene chloride. Merck also claim that the economics of the new process saved some US 7.2 million during the second half of 1992 alone. 

The VCM content of PVC suspension after stripping is normally very low. In the case of latex, stripping is more difficult and the residual VCM content depends on a variety of parameters, for instance emulsifier content and type, latex particle size, latex stability, the recipe and the requirements of resin end properties. When steam is used for stripping, the overhead steam containing recovered VCM is condensed. The condensate can be returned to the stripping system, or can be transferred to the water stripper of the effluent treatment or other sections of the process, in order to recover contained VCM and thus to prevent VCM emissions from this effluent. In all cases, the non-condensed overhead gas containing stripped VCM is collected in a recovery unit. 

Any water which may be contaminated with VCM, for example water used for the cleaning of reactors containing VCM, transfer lines and suspension or latex stock tanks, must be passed through a water stripper to remove VCM. This may be either continuous, consisting of a packed column or a column equipped with trays, or be a batch process. The VCM removal is optimised by the correct combination of residence time and temperature. The removed VCM is sent to the recovery plant and the aqueous effluent to a water treatment facility. 

The processing of stripper gas from water stripping, which contains H2S as well as ammonia and hydrogen cyanide... 

An important feature of Claus plants is their ability to decompose COS effectively and incinerate sour water stripper gas in the thermal reactor section. Sour water stripper gas contains NH3, HCN, and H2S produced in the coal gasification process. As previously discussed in the wet scrubber particulate removal portion of this section, these trace compounds are removed from the coal gas in the scrubber water. This "sour water" is then steam stripped to purify the water and to generate the small sour-water stripper gas stream. The Claus process is generally the simplest and most effective way to dispose of this stream. 

In reactive strippers, hydrogen sulfide and/or anunonia are removed from water in a sour water stripper. This is a conunon process for lowering the level of sour gases in effluent water. One question is how much boilup or stripping steam is required to lower the sour gas concentration in the bottoms to acceptable levels. The electrolytic reactions taking place in the column must be considered in order to correctly predict the column performance (Chen et al., 1982). 

Claus Sulfur Recovery Process, At the sulfur plant, H2S is combined with sour-water stripper off-gas and sent to a Claus unit. Invented in 1881 by Carl Freidrich Claus/ almost every refinery in the world uses some version of this process to convert H2S into elemental sulfur. A simplified version of Claus-reaction chemistry is shown in Figure 26. 

As shown, elemental sulfur is produced by the reversible reaction between SO2 and H2S. COS and CS2 appear in small amounts, but even traces of these compounds are hard to remove in tail-gas treating units. Ammonia comes in with the sour-water stripper off-gas. In the Claus process, it is thermally decomposed into nitrogen and water. 

Type 430 stainless is resistant to chloride stress corrosion cracking and elevated sulfide attack. Applications are found in nitric acid services, water and food processing, automobile trim, heat exchangers in petroleum and chemical processing industries, reboilers for desulfurized naphtha, heat exchangers in sour-water strippers and hydrogen plant efluent coolers. The compatibility of type 430 stainless steel with selected corrodents is provided in Table 7.4, which is taken from Reference [1]. 

One of my favorite tricks on hydro-desulfurizer recycle gas HjS absorbers or sour water strippers, or any tower that has far too many trays, is to double the tray spacing. This permits me to increase tower capacity by 40 to 50 percent. Recycle gas H S absorbers, especially, have typically four times the number of trays required (see my book. Process Engineering for a Small Planet, WUey, 2010). 

The two sour water strippers that 1 was troubleshooting in India both conformed to the bad method of process design. 

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