Tail gas composition

Tail gas composition, the tail gases will contain from 0.2 to 0.3 per cent NO, say 0.2 per cent, then ... 

The tail-gas composition confirms the design specification for nitrogen oxide emissions of less than 1000 ppm. The emission is approximately 960 ppm. Western Australian emissions standards specify that emission of nitrogen oxides must not exceed 0.2 g per cubic metre of gas (STP). The emission from the absorber of 960 ppm is less than 0.1 g per cubic metre of gas (STP). 

Plate 13 Feed plate for 42% wt. weak acid at 5531 kg/hour. Tail-gas composition leaving the absorber ... 

Oxygen in hydrogen Oxygen in chlorine Moisture in dry chlorine Chlorine tail gas composition... 

PISTON RINGS are of the single-piece, snap-ring type. PISTON-ROD AND TAIL-ROD are one piece of carbon-steel, flame-hardened over packing travel area. The rod is packed with full-floating metallic packing, force-feed lubricated, and vented when the gas composition requires. Vented packing is shown. 

The efficiency of the Claus Process, long the means of conversion of H2S to sulfur, has been increased through improvements in reaction furnace, catalyst bed and computerized feed composition control leading to recovery efficiencies in excess of 98%. Recent development of a Claus Process under pressure may yield further important improvements. Add on tail gas clean-up processes have further reduced plant effluent in response to environmental protection requirements. 

One of the major technical problems that had to be overcome to integrate the POLYBED system with the steam reformer was the variation in tail gas flow and composition. Because of the cyclic nature of the process, tail gas is rejected by the POLYBED unit during blowdown and purge with significant flow and composition variations. The fluctuations would have made it impossible to use the tail gas for fuel and a sophisticated system was developed to balance tail gas heating value. This buffer/mixing tank system has proven to be very reliable in holding heat input variation to 1% (2). ... 

PART OF High NOx Composition I 1. Improved yield from reactor. Higher tail-gas emission levels possible. k) Manually increase make-up water flowrate. 

The composition of the tail-gas stream from the absorber can now be calculated. Calculations are based on an overall mass balance, and also on a mole basis for each element. The assumption made is that the tail gas is saturated with water upon leaving the column. Calculations were performed using an electronic programmable calculator. 

Start-up and shutdown periods will normally increase the NOx content of the tail gas at the stack during the few hours needed for the process to stabilize or for NOx to be cleared from the plant. During the ammonia oxidation some nitrous oxide (NO2) is formed. The amount depends on combustion conditions (pressure, temperature), catalyst composition and age, and design of the oxidation reactor97. 

Reardon E. J. and Poscente P. J. (1984) A study of gas compositions in sawmill waste deposits evaluation of the use of wood waste in close-out of pyritic tailings. Reclam. Reveg. Res. 3, 109-128. 

Sample ports arranged at quarter point locations along the vertical reactor vessel permitted the gas composition to be monitored at different reactor locations, representing different gas residence times. The temperatures at each of these sample ports, as well as at the inlet and the outlet, were continuously monitored. The effluent gas of the reactor vessel passed through the sulfur condenser. The tail gases leaving the sulfur condenser were sampled and analyzed. 

During reforming, over 90 percent of the THC emissions were methane. The composition of the hydrocarbons was analyzed and the presence of toxic contaminants determined. Figure 3 shows the hydrocarbon fractions from fuel processor tests in terms of methane and NMHCs. Samples from these tests were also analyzed to determine the speciated hydrocarbon emissions profile over various operating loads. Figure 4 shows the results of the speciation analysis, in terms of the fraction of olefins and saturated and aromatic hydrocarbons that comprise the NMHCs. Aromatics and saturated hydrocarbons comprise almost all of the NMHC emissions. The fraction of NMHC as aromatics was close to the fraction of aromatics in the test gasoline for several samples taken from the PrOx and the tail gas combustor (TGC). The TGC burned reformer product gas. 

Figure 4. Speciated Hydrocarbon Composition of Air Toxics Samples from the Fuel Processor or Tail Gas Combustor at Various Fuel Processor Loads...

Consider the separation of a ternary gas mixture of species 1, 2 and 3 through a membrane separator with two different types of membranes M and M" such that species 1 appears preferentially in product stream 7=1 from membrane M, product stream 7 = 2 from membrane M" is enriched in species 2, while the tails stream 7 = 3 is enriched in species 3. If the gas composition everywhere inside the separator is indicated by Xg, the mole fraction of species i in tails stream 3, define the following separation factors (Sirkar, 1980) ... 

Proper operation depends primarily on the ratio of hydrogen sulfide to sulfur dioxide and on the total content of hydrogen sulfide and sulfur dioxide in the feed gas. For maximum conversion, it is necessary to maintain the ratio of hydrogen sulfide to sulfur dioxide in the feed gas within 5% of the stoichiometric proportion of two to one. This requires reliable control instruments, such as in-line gas chromatographs or ultraviolet spectrophotometers, to ensure that the composition of the Claus unit tail gas is relatively constant. 

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