The control system shown in Figure 5.10A is a simple technique for minimizing energy consumption. The two valves on the makeup and purge lines from and to the feed tank are split ranged so that both valves cannot be open at the same time. This guarantees that a minimum amount of material is going to or coming from the tank.
During regeneration, maximum use is made of equipment used in the normal operation. The recycle compressor is used to recirculate the inert gas. Compressed diluted makeup air is mixed with recycled inert gas flowing to the reactor inlet to provide oxygen to sustain a burn wave in the top catalyst beds. The reactor inert gas is preheated in the feed effluent exchanger then combined with diluted makeup air and heated in the feed furnace before flowing to the reactor inlet. The regeneration is carried out at the pressure that allows the maximum flow rate as limited by the maximum power of the recycle compressor or the discharge temperature of the makeup compressor (1150psig). The makeup air is diluted with the recycling inert gas to avoid forming a combustible mixture in the lubricated makeup compressor. With hydrogen present the maximum 02 concentration is 4mol maximum at a compressor outlet temperature of 265 F. After the regeneration burn has started and the recycling gas stream is...
Light naphtha feed is charged by charge pump P-101 to one of the two drier vessels, D-101 and 102, filled with molecular sieves, and designed to remove water to protect the catalyst (see Figure 4-7). The makeup hydrogen is compressed by makeup gas compressor C-101 to 500psig. The gas then flows to gas driers D103 and D104, similar to those for liquid feedstock before it is combined with fresh feed. The feed is mixed with makeup hydrogen, heated through heat exchange with reactor effluent in E-101 and E-102 and a steam heater E-103, heated with medium pressure steam, and sent to the reactors. In normal operation, two reactors in series are employed. MAKEUP HYDROGEN Ofl IE HS D-101 D-1 2 MAKEUP HYDROGEN COMPRESSOR C-1C1 MAKEUP CAUSTIC SOLUTION
Activated carbon is available in hundreds of different forms that are characterized by their absorption structure and special porous makeup. The carbon gets its characteristics from the method of manufacture and the basic raw material. The carbon absorbs impurities by virtue of many different effects. The carbon is very porous with a large surface area, usually 500-1200 square metres per gramme. The pores can be described as an enormous number of naturally occurring cracks or pores that have randomly fused together into a coherent structure. Carbon can be compared to small sponges where impurities fasten in the holes.
Municipal water feed to the refinery must be upgraded to boiler feed-water quality by further treatment (see Figure 9-3). Boiler feedwater is used as makeup to fired and nonfired steam generators located in the utility plants and process units. Boiler feedwater is also used for process purposes. Fresh water, as received from an outside supply, may not have enough pressure to fill tank TK-101. Booster pump P-101 is used to elevate the water supply pressure. Feedwater is stored in tank TK-101, holding approximately 72-hr supply. Water is pumped by P-102 to water filter V-101, which removes most entrained solids. Filter aids are added at the discharge of P-102, using a dozing pump to facilitate removal of suspended solids. Filtered water next passes through a bed of cation and anion resins in V-102 and V-103, which remove all anions and cations in the water by an ion exchange process. A high-purity water, which is essentially free of salts, is produced and stored in tank TK-102....
CATALYST SOLUTION MAKEUP TANK V102 CATALYST SOLUTION MAKEUP TANK V102 Solvent let-down tank T-101 is provided for PEG storage during filling and emptying and as a reserve for makeup solvent. Washing recovery tank T-102 is provided to recover the PEG water mixture during the unit washing. The mixture is stored in the tank by solvent pump P-101 and reinjected intermittently in the system by metering pump P-103 to compensate for solvent losses and deposits on the packing.
Steam is supplied to the 900psig header from the boiler plant. Some process units, such as hydrogen and sulfur plants, have waste heat boilers that also generate steam at 900 psig. The 900 psig steam is consumed by steam turbines to drive recycle compressors, charge pumps, and the like for many hydroprocessing units of the refinery and as makeup to 475-psig header through a reducing or desuperheating station. 2. 475psig. Sources of 475 psig steam are the exhaust steam of turbines and makeup from the 900 psig steam header. The 475 psig steam is consumed in steam turbines, reboilers, and certain process plants, such as hydrogen. All excess 475 psig steam is reduced and desuperheated to a 150 psig header. 3. 150psig. Sources of 150 psig steam are steam turbine exhaust, waste heat boilers in the process units, and makeup from 475 psig steam. The consumers are process stripping, reboilers, and steam tracing. All excess 150 psig steam is reduced and desuperheated to 50 psig steam...
The design capacity of fuel oil heating and pumping equipment usually equals 125 of the design requirement of the plant, assuming simultaneous firing at the design rate of all fuel oil burning furnaces and boilers. This allows for 25 recirculation of oil. Rotary pumps are used, one driven by electric motor and the other by steam turbine. Heaters used are steam heaters. Relief valves are located on the discharge side of the pumps and on oil heaters. Relief valve discharge is piped back to storage tank. Strainers are provided at the pump inlet and outlet to strain out any precipitated carbon particles. Piping from the suction line to the fuel oil pumping equipment is sized for a pressure drop not exceeding 3 psi 1000 ft. The discharge piping supplying burners and recirculation piping returning to storage have protective heating. Separate nozzles are provided on storage tanks for makeup fuel and for recirculation and withdrawal of oil.
The bottoms water stream is combined with a water makeup stream (46.2 kmol h) and cooled before being fed as the extraction water feed to C2. The distillate methanol stream is combined with the fresh feed of methanol (232 kmol h), and the total is split between the prereactor and the reactive distillation column. Figure 14.6 displays the temperature profile. There are two areas where the temperature changes from tray to tray are fairly large, which suggests either one-end temperature control or two-temperature control may be possible.
Around between the extractive column and the recovery column. However, there is a small amount of water lost in the overhead from column C2. A water makeup stream is used to control the liquid level in the base of column C3. This makeup flow is very small compared to the water circulation, so the base of column C3 must be sized to provide enough surge capacity to ride through disturbances.
As an alternative to Item 5, one may use a recirculating coolant system ( tempered coolant) with condensate temperature control of makeup coolant. This keeps the condenser dynamics constant and eliminates the problem of retuning the controller as the load changes (see Figure 3.9).
A purge ratio is the ratio of the volume of hydrogen in the purged gas to the volume of hydrogen in the makeup gas. Purging is required to prevent the buildup of inert gases and light hydrocarbons in the recycle gas. The quantity of purge directly influences the purity of the hydrogen in the recycle gas. For low-sulfur feeds such as naphtha, the purge ratio required is small. For heavy, high-sulfur feeds the purge ratio required to maintain the purity of recycled hydrogen is quite high. Typical purge values used are shown in Table 2-1.
Hydrogen-rich gas recovered in a hydrogen recovery unit (HRU) is gathered into a hydrogen header together with hydrogen gas manufactured by the hydrogen production unit to supply makeup hydrogen to several hydrogen-consuming units. See Tables 5-12 to 5-15 for the unit's operating parameters and yields.
Citric acid is the most important acid produced by fungi and the only organic acid produced almost exclusively through fermentation. Widely used in the food and beverage industry, its pleasant acid taste enhances products such as soft drinks, fruit juices, jams, jellies, candies, prepared desserts, and frozen fruits. Citrates are also efficient buffering and chelating agents and are used by the cosmetics industry and in blood transfusion products, effervescent tablets, detergent manufacturing, electroplating, printing, inks, leather tanning, and a host of other applications. With increasing emphasis on nonpolluting chemical products, the market for nature's acidulant is increasing.
The minimum acid strength required to operate the system is 85-87wt , although this varies somewhat depending on the olefin type and spent acid composition. At acid strengths lower than this, polymerization becomes so predominant that the acid strength cannot be maintained and the plant is said to be in an acid runaway condition. To provide a sufficient safety margin, an acid strength of 89-90 H2S04 is used. However, the composition of acid diluents, as well as acid strength, is important. Water lowers the acid catalytic activity three to five times faster than hydrocarbon diluents. Some water is necessary to ionize the acid. The optimum water content is approximately 0.5-1 by weight. Impurities present in the olefin feed stream either react with or are absorbed in the acid catalyst, causing a decrease in strength and a need for increased acid makeup.
The fresh C5 stream containing the reactive isoamylenes and the chemically inert other C5 components is fed into the reactor on flow control. The methanol fed to the prereactor is ratioed to the fresh feed flowrate. The exit temperature of the reactor is controlled using a temperature temperature cascade structure. The reactor effluent temperature controller changes the setpoint of the circulating cooling water temperature controller, which manipulates the cooling water makeup valve (see Fig. 14.7).
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