Regeneration unit

The potassium combines with the sulfur to form potassium sulfate, which condenses as a soHd primarily in the electrostatic precipitator (ESP) or baghouse. The recovered potassium sulfate is then deUvered to a seed regeneration unit where the ash and sulfur are removed, and the potassium, in a sulfur-free form such as formate or carbonate, is recycled to the MHD combustor. It is necessary also to remove anions such as Cf and E which reduce the electrical conductivity of the generator gas flow. These are present in the coal ash in very small and therefore relatively harmless concentrations. As the seed is recycled, however, the concentrations, particularly of CF, tend to build up and to become a serious contaminant unless removed. 

FIG. 16-61 Internals of an npflow regenerated unit. (Infilco Degremont Inc.)... 

The Socony Vacuum design consisted of separate vessels for reaction and regeneration. Units constructed in the late 1940s employed a pneumatic lift design which allowed for high catalyst circulation rates. A typical design is shown in Figure 20, which allowed for a primary air stream to convey the catalyst. A... 

Generally, adsorption, absorption, and biofilter units require more space than compact incinerators and condensers. If the plant room is restricted, a local roof-mounted system may be the best alternative. However, roof structural reinforcement may be required even for small and lightweight units. Consideration must be given to the effects of noise and vibration. Small adsorption systems, such as adsorption canisters, require an additional central regeneration unit on site, or they must be regenerated or disposed of off site. A central regeneration unit may require long runs of costly ductwork." ... 

The process consists of a reactor section, continuous catalyst regeneration unit (CCR), and product recovery section. Stacked radial-flow reactors are used to minimize pressure drop and to facilitate catalyst recirculation to and from the CCR. The reactor feed consists solely of LPG plus the recycle of unconverted feed components no hydrogen is recycled. The liquid product contains about 92 wt% benzene, toluene, and xylenes (BTX) (Figure 6-7), with a balance of Cg aromatics and a low nonaromatic content. Therefore, the product could be used directly for the recovery of benzene by fractional distillation (without the extraction step needed in catalytic reforming). 

The Subpart O standards apply to units that treat or destroy hazardous waste and which meet the definition of an incinerator. An incinerator is any enclosed device that uses controlled flame combustion and does not meet the criteria for classification as a boiler, sludge dryer, carbon regeneration unit, or industrial furnace. Typical incinerators1 2 3 include rotary kilns, liquid injectors, fixed hearth units, and fluidized bed incinerators (Table 23.1). The definition of an incinerator also includes units that meet the definition of an infrared incinerator or plasma arc incinerator. An infrared incinerator is any enclosed device that uses electric-powered resistance as a source of heat and which is not listed as an industrial furnace. A plasma arc incinerator is any enclosed device that uses a high-intensity electrical discharge as a source of heat and which is not listed as an industrial furnace. 

The alkylation unit in a petroleum refinery is situated downstream of the fluid catalytic cracking (FCC) units. The C4 cut from the FCC unit contains linear butenes, isobutylene, n-butane, and isobutane. In some refineries, isobutylene is converted with methanol into MTBE. A typical modern refinery flow scheme showing the position of the alkylation together with an acid regeneration unit is displayed in Fig. 1. 

The product alkenes are insoluble in the alcohol and phase separation takes place. After settling, the alcohol layer goes to a regeneration unit. The alkene layer is washed and ethene is recycled to the reactor. The products are distilled and the desired fractions are collected. 

Both of these processes direct the SO2 absorbed from the FCCU flue gas to the refinery SRU, where it is converted to elemental sulfur and added to the marketable sulfur that is generated by the SRU from H2S. Alternately, the SO2 can be converted to sulfuric acid in a dedicated sulfuric acid plant, or in combination with an existing refinery spent acid regeneration unit. When the SO2 is directed to the SRU, 1 ton of SO2 captured in the scrubber is converted to 0.5 tons of marketable elemental sulfur and less than 0.1 ton of sodium sulfate waste is generated per ton of SO2 absorbed. In an acid plant, 1 ton of SO2 generates 1.5 tons of 98% sulfuric acid. Steam is also generated from the conversion of SO2 in both the SRU and the acid plant, which moderates somewhat the steam consumption rate of the solvent regenerator for both the LABSORB and CANSOLV systems. 

Figure 23.6 Scheme of a continuous pilot plant the solvent, 7 - container of the regenerated unit for recovery of MPCA from mother liquor solvent, 9 - container of the stripping solution,... 

Description DCC is a fluidized process to selectively crack a wide variety of feedstocks into light olefins. Propylene yields over 24 wt% are achievable with paraffinic feeds. A traditional reactor/regenerator unit design uses a catalyst with physical properties similar to traditional FCC catalyst. The DCC unit may be operated in two operational modes maximum propylene (Type I) or maximum iso-olefins (Type II). Each operational mode utilizes unique catalyst as well as reaction conditions. DCC maximum propylene uses both riser and bed cracking at severe reactor conditions, while Type II utilizes only riser cracking like a modern FCC unit at milder conditions. 

Description DCC is a fluidized process to selectively crack a wide variety of feedstocks into light olefins. Propylene yields over 24 wt% are achievable with paraffinic feeds. A traditional reactor/regenerator unit design uses a catalyst with physical properties similar to tra-... 

Typical operating data of the four types of commercial FFB regenerator units are presented in Tables IV, V, VI and VII. These tables show the following distinct features. 

Catalyst falling to the bottom of the separator is passed by an airlift to a regenerator unit. Here, the air burns carbon deposited on the catalyst and reheats the catalyst before its return to the riser pipe. In some systems, and to prevent overheating in the regenerator, the oxidation of carbon proceeds only to carbon monoxide and carbon monoxide combustion to carbon dioxide occurs in a second regenerator. 

The catalyst progressively cokes and this is handled by continually moving the catalyst through the system until it is finally passed to regenerator unit (2). Regenerated catalyst is passed to the beginning of the process. 

Use oxygen enrichment in regeneration unit Integrate regeneration energy with air blower Eliminate fluid-bed reactors Fugitives... 

Circulating pump Silicagel regeneration unit Regeneration air fan Silicagel air dehumidifier... 

FWU, FUU, FRU, FRR and FUR are the freshwater to unit, unit to unit, regeneration unit to units, regeneration to regeneration and unit to regeneration flowrates. 

CW c is the pollutant c concentration in freshwater, in turn, ZUU, ZRU, ZUS and ZUR are mass flows of contaminants between units, regeneration to units, units to disposal and units to regeneration units. Finally A/V/ is the mass load of component c. Maximum inlet concentration at the water-using units... 

The consequence of these different performances suggest that for semiregenerative processes a Pt-Re catalyst is better than a Pt-Sn catalyst, but if a continuous regeneration unit is considered then a Pt-Sn catalyst should be preferred. 

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