Hydrodesulfurization unit

Figure 10.9 shows advantages of a hydrodesulfurization unit upstream of an FCC or RCC unit. 

J. Hydrodesulfurization unit effluent exchanger channel head and shell plate. (Hydrocarbon feed to unit and make-up hydrogen Bom ethylene unit)... 

L. Gas-oil hydrodesulfurization unit. Elbow cracked intergranularly and decarburized at fusion line between weld metal and heat-affected zone no postweld heat treatment. 

P. Hydrodesulfurization unit hydrogen preheat exchanger shell blisters, intergranular Assuring, and decarburization in weld metal postweld heat treated at 1150°F. 

U. Hydrodesulfurization unit, C-0.5Mo steel exchanger tubesheet decarburized, fissured, and cracked under intergranularly cracked ASTM Type 304 cladding. 

Natural gas feedstock enters the fuel processing subsystem at about 63 psig (4,5 atm). The fuel is first processed in hydrodesulfurizing unit (HDS) and zinc-oxide (ZnO) beds lo remove any sulfur compounds. The desulfurized fuel is mixed with process steam and preheated to about 850°F (454cC) before entering the reformer, which consists of reactor tubes containing a... 

Feed gas is purified in a hydrodesulfurization unit operating at lower than usual temperatures and passes through a saturator to supply a part of the process steam, while the balance is injected as steam. Heated in an inlet-outlet exchanger to 425 °C... 

Data obtained on trickle-flow processes obtained in microflow tests with diluted catalyst beds are not only reproducible, but are also meaningful for industrial practice. This is demonstrated in Table X by the direct comparison of microflow test results with data from an industrial gasoil hydrodesulfurization unit. 

The Mizushima Oil Refinery of Japan Energy Corporation first implemented a high conversion operation of vacuum residue, versus a constant desulfurization operation, in the commercial residue hydrodesulfurization unit equipped with fixed-bed reactors, to produce more middle distillates as well as fuel oil with lower viscosity. The catalysts will be replaced when the sulfur content in the product oil reaches the allowable limit. Since we have believed that an increase in the residue conversion decreases the catalyst activity by coke deposition, we have been interested in controlling the coke deactivation to maximize the residue conversion during a scheduled operating period. 

Effective solutions to the problems of the vacuum residue hydrodesulfurization unit equipped with the fixed bed reactors, such as a hot spot, pressure-drop buildup, and catalyst deactivation by coke fouling, were discussed. Improving liquid distribution can prevent hot spot occurrence. Dispersing inorganic solids throughout the reactors can control a pressure-drop increase in the first bed. For a high conversion operation, controlling the conversion in each bed can minimize the coke deactivation in the fourth bed. 

The primary nses of trickle bed reactors are for hydrodesulfurization, hydrocracking, and hydrotreating of various high-boiUng petroleum fractions. The direct and capital costs are significantly less for trickle bed operation than for an equivalent hydrodesulfurization unit operating... 

For a fuel cell system incorporating fuel (e.g., CH,) processing the HMM becomes much more complicated. The temperatures of the hydrodesulfurization unit, the reformer, the water-gas shift reactors, the preferential oxidizer, and the stack are all need to be properly controlled and maintained. There will be a heat exchanger between every two adjacent units mentioned above. For steam reforming, heat is needed to generate vapor from liquid water for the steam reforming reaction and the subsequent water-gas shift reactions. The conversion of liquid water to steam is typically carried out in one or more of the heat exchangers mentioned above.". 

Hydrodesulfurization unit—sweetens products by removing sulfur. 

Crude oil is a mixture of hydrocarbons, clay, water, and sulfur. Some crude mixtures have higher concentrations of sulfur than others these mixtures are referred to as sour feed. Hydrodesulfurization (Figure 11-10) is a process used by industrial manufacturers to "sweeten" or remove the sulfur. Hydrodesulfurization units use the following equipment during operation ... 

This is a complex refinery, with a light crude capacity of 8 Mt y and a heavy crude capacity of 1.2 million. It includes an FCC, a catalytic reformer, a visbreaker, a gas oil hydrodesulfurization unit, a naphthenic bitumen unit and a paraffinic oil unit. It is supplied by the water table for boiler make up (3.3-10 m y and by Seine river water for industrial and cooling water. Cooling is partly once-through and partly open recirculating. 

Reinhardt, J Balfanz, U and Dimmig, T. (2002) Sulfur-free diesel fuel. Modifications and operating experience using a middle-distillates hydrodesulfurization unit. Erdod Erdgas Kohle, 118, 456. 

The fact, mentioned earlier, that in multiphase systems one obtains the RTD for the tracer, not the system, is illustrated by Figure 12. In this figure the tracer tests from a hydrodesulfurization unit are represented. Nonvolatile and volatile tracers are used and their response is clearly different. Only the nonvolatile tracer curve can be interpreted in terms of an axial dispersion model to assess the liquid flow pattern. Even then diffusion into the particles and adsorption on the catalyst must be included in the model. These two effects can contribute more... 

Figure 12. Nonvolatile and Volatile Tracer Impulse Responses in a Hydrodesulfurization Unit.

Figure 13. Impulse Response of a Nonvolatile Tracer in Two Hydrodesulfurization Units. 

Figure 15. The Intensity Function for the Volatile Tracer in Hydrodesulfurization Unit A.

In the first occurrence a hydrodesulfurizer unit was being designed. A simple flowsheet is given in Figure 6. The coker gas oil is preheated in a furnace and catalytically reacted with hydrogen to convert the hydrocarbon mercaptans to H2S, which is subsequently stripped off. 

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