Sulfur flowsheets

Charcoal absorption towers (not included in the flowsheet) were used to keep the sulfur content in the fresh feed gas less than 0.1 ppm in equivalent volume of H2S. 

The second example that is used to illustrate the design methodologies is a modification to the EDTA problem as follows. The structure of the flowsheet is exactly the same as the one presented in Section IV. The only change to the problem is the statement that sulfuric acid and formaldehyde should not be allowed to come into contact with each other. 

The chemical processing techniques considered for synfuels flowsheet for the removal and recovery of sulfur are similar to those employed in other industries - notably natural gas sweetening, petroleum hydrodesulfurization, and coke oven gas treatment -but with certain significant differences attributable to the operating conditions encountered in synfuels processing. 

A plant is to manufacture butadiene sulfone at the rate of 1250 lb/hr from liquid sulfur dioxide and butadiene to be recovered from a crude C4 mixture as starting materials. Construct a flowsheet for the process according to the following description. 

On the modem plants employing the Bufflex flowsheet, uranyl sulfate is stripped from the resins with the bisulfate anion. The eluate contains about 1 M sulfuric acid since this is the optimum concentration for the subsequent solvent-extraction process at lower acid concentrations, the tertiary amine in solvent extraction is only partially ionized, which reduces its capacity for uranyl sulfate, whereas at higher acid concentrations the bisulfate anion begins to compete with the uranyl sulfate anion for tertiary amine functional groups. 

Many processes have been developed for the removal of hydrogen sulfide from gas streams. They can be classified as liquid absorption, liquid oxidation, dry oxidation, and adsorption. One of these processes is usually included in a coal gasification or liquefaction flowsheet since the coal sulfur is converted to H2S and finally elemental sulfur. The Stretford and Townsend direct HpS to S processes and the Recti sol process followed by a Claus plant are frequently included on coal conversion flowsheets (1 ). Kohl and Riesenfeld (2) present pertinent details for many commercial processes. 

The highly exothermic sulfonation of toluene with gaseous sulfur trioxide is one reaction which has been investigated. Figure 4.43 shows the process flowsheet of the microstructured reactor plant used at the ACA. 

A comparison of sulfuric and carbonic acid pretreatment flowsheets shows that some operations associated with processing requirements of... 

Brown, L.C., R.D. Lentsch, G.E. Besenbruch, K.R. Schultz (2003), Alternative Flowsheets for the Sulfur-Iodine Thermochemical Hydrogen Cycle , AIChE Journal, April. 

Kasahara, Seiji, et al. (2007), Flowsheet Study of the Thermochemical Water-splitting Iodine-Sulfur Process for Effective Hydrogen Production , International Journal of Hydrogen Energy, 32, pp. 489-496. 

The process flowsheet inside the battery limits (IBL) is at this stage unknown. However, the recycle of reactant may be examined. The patent reveals that the catalyst ensures very fast reaction rate. Conversion above 98% may be achieved in a fluid-bed reactor for residence time of seconds. Thus, recycling propylene is not economical. The same conclusion results for ammonia. The small ammonia excess used is to be neutralized with sulfuric acid (30% solution) giving ammonium sulfate. Oxygen supplied as air is consumed in the main reaction, as well as in the other undesired combustion reactions. 

Fig. 1.4. Double contact sulfuric acid manufacture flowsheet. The three main S02 sources are at the top. Sulfur burning is by far the biggest source. The acid product leaves from two H2SO4 making towers at the bottom. Barren tail gas leaves the final H2S04 making tower, right arrow.

Fig. 3.1. Sulfur burning flowsheet - molten sulfur to clean dry 700 K S02, 02, N2 gas. The furnace is supplied with excess air to provide the 02 needed for subsequent catalytic oxidation of S02, to SO3. Table 3.1 gives industrial sulfur burning data.

Fig. 5.1. Spent sulfuric acid regeneration flowsheet. H2S04(f) in the contaminated spent acid is decomposed to S02(g), 02(g) and H20(g) in a mildly oxidizing, 1300 K fuel fired furnace. The furnace offgas (6-14 volume% S02, 2 volume% 02, remainder N2, H20, C02) is cooled, cleaned and dried. It is then sent to catalytic S02 + Vi02 —> S03 oxidation and H2S04 making, Eqn. (1.2). Air is added just before dehydration (top right) to provide 02 for catalytic S02 oxidation. Molten sulfur is often burnt as fuel in the decomposition furnace. It provides heat for H2S04 decomposition and S02 for additional H2S04 production. Tables 5.2 and 5.3 give details of industrial operations.

Fig. 9.1. Single contact H2SO4 making flowsheet. SO3 rich gas from catalytic SO2 oxidation is reacted with strong sulfuric acid, Reaction (1.2). The reaction consumes H20(f) and makes H2S04(f), strengthening the acid. Double contact H2SO4 making is described in Fig. 9.6. A few plants lower the SO2 content of their tail gas by scrubbing the gas with basic solution (Hay et al., 2003).

Fig. 21.1. Heat transfer flowsheet for single contact, sulfur burning sulfuric acid plant. It is simpler than industrial plants, which nearly always have 4 catalyst beds rather than 3. The gaseous product is cool, S03 rich gas, ready for H2S04 making. The heat transfer product is superheated steam. All calculations in this chapter are based on this figure s feed gas composition and catalyst bed input gas temperatures. All bed pressures are 1.2 bar. The catalyst bed output gas temperatures are the intercept temperatures calculated in Sections 12.2, 15.2 and 16.3.

Fig. 23.1. Simplified single contact sulfuric acid production flowsheet. Its inputs are moist feed gas and water. Its outputs are 98 mass% H2S04, 2 mass% H20 sulfuric acid and dilute S02, 02, N2 gas. The acid output combines gas dehydration tower acid, H2S04 making tower acid and liquid water. The equivalent sulfur burning acid plant sends moist air (rather than moist feed gas) to dehydration. Appendix V gives an example sulfur burning calculation.

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