Absorber tank

Calculate the total mass of chlorine (kg) in the chlorine absorber tank, assuming ideal gas behavior in the head space. Suggestion Take as a basis of calculation a specified mass of slurry, calculate the volume your basis amount would occupy and the mass of chlorine it would contain, and scale the results to the actual volume of the slurry in the tank calculated in Problem 12.11. Then calculate the mass of chlorine in the head space.)... 

A complete circuit for an advanced scrubber is shown in Fig. 4, which includes oxidation of the sludge to form gypsum. In this circuit, limestone is first reduced to a fine particle size by a grinding mill, producing a slurry. The slurry is then added to the absorber tank, and pumped into the scrubber tower. A portion of the descending absorbent is diverted back to the absorber tank, which provides more time for the sulfur dioxide and limestone to react. The remaining absorbent collects in the base of the tower, where it is oxidized by injected air while being recirculated in the lower portion of the scrubber. A portion of the absorbent is continuously drawn off to a hydrocyclone. 

Fig. 4 Circuit for a wet limestone scrubber, with oxidation of the solids to gypsum. The absorbent tank simplifies control of the process, while the hydrocyclone and filter remove coarse gypsum particles.

Calcium reagent is added to the absorber tank and pumped to the sulfur dioxide absorber. Most of the spent reagent is returned to the absorber tank, and part is provided as reagent make-up to the quencher system. The spent quencher reagent, containing particulate and reaction salts, is removed from the process as a sludge blow down. Make-up water, to compensate for evaporation losses and sludge blow down, is added primarily as mist eliminator wash. 

In the absorber tank, time for external desupersaturation is provided and fresh reagent is added to raise the pH and thereby promote desupersaturation of the spent reagent stream. The delay tank provides contact time for crystal growth and sulfite and sulfate salt precipitation. 

Axially located inside absorber tank 5 and clearing paddles 10 is an elongated cylindrical reaction tank 15 attached at its upper end to a tube type heat exchanger 16 having vertical tubes and supplied with coolant through inlet 17 and outlet 18. 

The reaction tank 15, when filled with solution, defines a reaction zone. The space between the reaction tank 15 and the absorber tank 5 defines an absorption zone. In this latter space is placed a quantity of thorium oxide pellets 60 introduced through absorber supply pipe 61. Pellets 60 can be removed from the absorption zone through axial outlet 11 connected with an absorber outlet pipe 62 through bearing block 6. The pellets 60 arc held in the absorbing zone by absorber valve 64 operated by lever 65 outside of walls 1. 

The thorium in the absorbing zone also needs to be cf oled, and the entire device needs to be shielded at the top of the pit. Consequently, the pit is filled with water (HaO) to provide a shield layer 50 to 75 ft. high over the surge chambers 32 and 33. This water shield is circulated both to cool the thorium pellets, and to rotate the absorber tank 5 to stir up the pellets 60. This water circulation will next be described. 

The head of water in the pit is applied to the top of the absorber tank 5 which is open. The water passes through the voids between the pellets 60 and enters lower pit portion 2 through apertures 12, and also through bores 66 in bearing block 6 so that the pellets 60 immediately above the valve 64 can be cooled. The water then passes upwardly between the absorber tank 5 and the pit walls, exerting pressure on spiral fins 9 to rotate the absorber tank 5. The water then passes into a circumferential collector 70 through a plurality of passages 71 near the top of the absorber tank 5. Water from the collector 70 is then pumped up to the top of the pit by a plurality of pumps 72 and risers 73. Thus, as the water circulates the absorber tank 5 is rotated so that paddles 10 will stir up pellets 60. 

When the solvent around the spot has evaporated, the plate is placed ertically in a glass developing tank (a cylinder for small slides) which contains a small quantity of the solvent and is lined with filter-paper dipping into the solvent the level of the latter is adjusted, preferably with a pipette, so that the lower edge of the absorbent layer is under the soh ent but the spot is above this level, and the top of the cylinder is then firmly closed. The solvent rises through the adsorbent layer, and the components of the mixture ascend at different rates depending on their affinities for the adsorbent. 

This carbon dioxide-free solution is usually treated in an external, weU-agitated liming tank called a "prelimer." Then the ammonium chloride reacts with milk of lime and the resultant ammonia gas is vented back to the distiller. Hot calcium chloride solution, containing residual ammonia in the form of ammonium hydroxide, flows back to a lower section of the distiller. Low pressure steam sweeps practically all of the ammonia out of the limed solution. The final solution, known as "distiller waste," contains calcium chloride, unreacted sodium chloride, and excess lime. It is diluted by the condensed steam and the water in which the lime was conveyed to the reaction. Distiller waste also contains inert soHds brought in with the lime. In some plants, calcium chloride [10045-52-4], CaCl, is recovered from part of this solution. Close control of the distillation process is requited in order to thoroughly strip carbon dioxide, avoid waste of lime, and achieve nearly complete ammonia recovery. The hot (56°C) mixture of wet ammonia and carbon dioxide leaving the top of the distiller is cooled to remove water vapor before being sent back to the ammonia absorber. 

A filter cake from the wringer is washed to remove absorbed acid, transferred to a slurry tank of water, and quickly submerged, after which the nitrocellulose is pumped to the stabilization operation as a diluted water slurry. Exhaust systems are installed to protect personnel and equipment from acid fumes, and water sprays and cyclone separators are used for acid fume recovery before venting to the air. 

Storage. For receiving glycerol from standard 30.3-m (8000-gal) tank cars (36.3-t), a storage tank of 38—45-m ((10-12) x 10 — gal) capacity should be employed. Preferably it should be of stainless steel (304 or 316), of stainless- or nickel-clad steel, or of aluminum. Certain resin linings such as Lithcote have also been used. Glycerol does not seriously corrode steel tanks at room temperature but gradually absorbed moisture may have an effect. Therefore, tanks should be sealed with an air-breather trap. 

The rich oil from the absorber is expanded through a hydrauHc turbiae for power recovery. The fluid from the turbiae is flashed ia the rich-oil flash tank to 2.1 MPa (300 psi) and —32°C. The flash vapor is compressed until it equals the inlet pressure before it is recycled to the inlet. The oil phase from the flash passes through another heat exchanger and to the rich-oil deethanizer. The ethane-rich overhead gas produced from the deethanizer is compressed and used for produciag petrochemicals or is added to the residue-gas stream. 

Mercury vapor discharge from vents of reactors or storage tanks at normal atmospheric pressure is controlled readily by means of activated carbon. Standard units (208-L (55-gal) dmms) of activated carbon equipped with proper inlet and outlet nozzles can be attached to each vent. To minimize the load on the carbon-absorbing device, a small water-cooled condenser is placed between the vent and the absorber. 

Many redundant safety features were provided at the SRP. These included a moderator dump tank, gadolinium nitrate solution as emergency absorber, continuously mnning diesel generators, and a 95 x 10 -L (25 x 10 -gal) elevated water tank for each reactor, for assurance of cooling. 

Gas leaving the economizer flows to a packed tower where SO is absorbed. Most plants do not produce oleum and need only one tower. Concentrated sulfuric acid circulates in the tower and cools the gas to about the acid inlet temperature. The typical acid inlet temperature for 98.5% sulfuric acid absorption towers is 70—80°C. The 98.5% sulfuric acid exits the absorption tower at 100—125°C, depending on acid circulation rate. Acid temperature rise within the tower comes from the heat of hydration of sulfur trioxide and sensible heat of the process gas. The hot product acid leaving the tower is cooled in heat exchangers before being recirculated or pumped into storage tanks. 

Titanium alloyed with kon is a candidate for soHd-hydride energy storage material for automotive fuel. The hydride, FeTiH2, absorbs and releases hydrogen at low temperatures. This hydride stores 0.9 kWh /kg. To provide the energy equivalent to a tank of gasoline would thus requke about 800-kg... 

The calcium cyanamide feed is weU mixed with the recycled slurry and filtrate ia a feed vessel. The calcium cyanamide is added at a rate to maintain a pH of 6.0—6.5 ia the cooling tank. The carbonation step can be conducted ia a turbiae absorber with a residence time of 1—2 min. After the carbonation step, the slurry is held at 30—40°C to complete the formation of calcium carbonate, after which the slurry is cooled and filtered. AH equipment for the process is preferably of stainless steel. The resulting solution is used directiy for conversion to dicyandiamide. 

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