Petroleum Process Streams

For low electricity costs ( 75% compared with the reference case). Cases IE and IG will be more attractive compared with the other cases. These cases are still attractive even with higher electricity cost (125% compared with the reference case), with a payback period of 0.88 years. As expected, a higher electricity price reduces the attractiveness of all cases. Waste LLP steam can be recovered economically from the steam condensate system. Alternatively, waste heat can be recovered as hot water from process streams. Petroleum refineries often discard a lot of waste heat through furnace stacks, fin-fan coolers and product coolers, which can be used to generate LLP steam (Reddy et al., 2013b). In such situations, where LLP steam is available at zero cost, a single-stage absorption chiller (Cases ID and IF) becomes feasible and attractive with a payback period of 0.93 years (Table 11.2). 

The feedstocks used ia the production of petroleum resias are obtaiaed mainly from the low pressure vapor-phase cracking (steam cracking) and subsequent fractionation of petroleum distillates ranging from light naphthas to gas oil fractions, which typically boil ia the 20—450°C range (16). Obtaiaed from this process are feedstreams composed of atiphatic, aromatic, and cycloatiphatic olefins and diolefins, which are subsequently polymerized to yield resias of various compositioas and physical properties. Typically, feedstocks are divided iato atiphatic, cycloatiphatic, and aromatic streams. Table 2 illustrates the predominant olefinic hydrocarbons obtained from steam cracking processes for petroleum resia synthesis (18). 

Toluenesulfonic Acid. Toluene reacts readily with fuming sulfuric acid to yield toluene—sulfonic acid. By proper control of conditions, /)i7n7-toluenesulfonic acid is obtained. The primary use is for conversion, by fusion with NaOH, to i ra-cresol. The resulting high purity i7n -cresol is then alkylated with isobutylene to produce 2 (i-dii-tert-huty -para-cmso (BHT), which is used as an antioxidant in foods, gasoline, and mbber. Mixed cresols can be obtained by alkylation of phenol and by isolation from certain petroleum and coal-tar process streams. 

Thermal Cracking. Heavy petroleum fractions such as resid are thermally cracked in delayed cokers or flexicokers (44,56,57). The main products from the process are petroleum coke and off-gas which contain light olefins and butylenes. This stream also contains a considerable amount of butane. Process conditions for the flexicoker are more severe than for the delayed coker, about 550°C versus 450°C. Both are operated at low pressures, around 300—600 kPa (43—87 psi). Flexicokers produce much more linear butenes, particularly 2-butene, than delayed cokers and about half the amount of isobutylene (Table 7). This is attributed to high severity of operation for the flexicoker (43). 

Process Stream Separations. Differences in adsorptivity between gases provides a means for separating components in industrial process gas streams. Activated carbon in fixed beds has been used to separate aromatic compounds from lighter vapors in petroleum refining process streams (105) and to recover gasoline components from natural and manufactured gas (106,107). 

Waste-derived fuels from refining processes Fuels produced by refining oil-bearing hazardous wastes with normal process streams at petroleum refining facilities are exempt if such wastes resulted from normal petroleum refining, production, and transportation practices. For these wastes to be considered as refined, they must be inserted into a part of the process designed to remove contaminants. This would typically mean insertion prior to distillation. 

In the processing of petroleum the first step is the removal of salt water. The presence of salt water in any processing steps would mean that expensive corrosion-resistant materials are required for those steps. This would greatly increase the price of the equipment (see Chapter 9). After removing the salt water, the next major separation is the crude still where the feed is split into six or more large-volume streams to reduce the size of future processing equipment. 

The generation of the required reducing gas is very expensive because natural gas or low sulfur oil are used. Both of these fuels are in short supply and do not offer long-term solutions to the problem. However, in certain industrial processes, like petroleum refineries, a reducing gas could be readily available. Also, if a Claus sulfur recovery plant existed on-site, the concentrated SO2 stream could be sent to the Claus plant where it would mix with the H2S containing gas streams. Final adjustment of the H2S S02 ratio would be necessary. If the overall sulfur balance were favorable, the need for a reducing gas could be avoided. Either of these options could make the use of a recovery process economically attractive for industrial applications. 

The use of various substances as additives to process streams to inhibit corrosion has found widespread use and is generally most economically attractive in recirculation systems, however, it has also been found to be attractive in some once-through systems such as those encountered in the petroleum industry. Typical inhibitors used to prevent corrosion of iron or steel in aqueous solutions are chromates, phosphates, and silicates. In acid solutions, organic sulphides and amides are effective. 

EPA) to aid in registering chemicals under the federal Toxic Substances Control Act (TSCA) of 1976. CAS numbers are assigned to generic refinery process streams, such as kerosene and lube base stocks, that contain no additives. Petroleum products containing additives are termed "mixtures" by the TSCA and, as such, do not have CAS numbers. All chemical substances used in such mixtures are assigned CAS numbers and must be listed with the EPA by the refiner or the additive supplier. 

Leopold, G. Breaking Produced-Fluid and Process-Stream Emulsions in Emulsions, Fundamentals and Applications in the Petroleum Industry, Schramm, L.L., Ed., American Chemical Society Washington, DC, 1992, pp. 342-383. 

The use of linear programming to optimize the flow of process streams through a petroleum refinery began in the mid-1950 s (Symonds, 1955 Manne, 1956). Now, almost twenty-five years later, it is safe to say that one half of U.S. refining capacity is represented by linear programming or LP models which are routinely optimized to schedule operations, evaluate feedstocks, and study new process configurations. 

Generally, past practice has called for evaluating certain portions of the above liquids in existing refinery streams. This led to problems and did not allow for a detailed and comprehensive study of the very nature of the synthetic liquids. A primary purpose of this project was to attempt to define the operable, physical, and chemical nature of the liquids from coal and shale liquefaction, per se, and then contrast and compare with results from processing standard petroleum streams. 

Health effects data also are available for some petroleum fractions or process streams that are less heterogeneous. These materials are more representative of the fractions that may partition in the environment and are more useful for assessing health effects of intermediate and chronic exposure to petroleum hydrocarbons. These products are discussed further in Section 6.2. Additional discussion of these and also the more heterogeneous products is presented in Section 6.3. 

Catalytic cracking is a very flexible process used to reduce the molecular weight of hydrocarbons. Today, fluid catalytic cracking (FCC) remains the dominant conversion process in petroleum refineries. Although FCC is sometimes considered to be a fully matured process, new challenges and opportunities in its application and a continuing stream of innovations in the process and catalyst field ensure that it will remain an important and dynamic process in the future of refining. 

Can have chemical incompatibilities between membrane materials and process streams. This is a difficult problem in the chemical and petroleum industries. 

A modern-day petroleum refinery is a complex chemical operation that involves numerous separations and chemical processing steps. Today virtually all the chemical analysis equipment found in the research laboratory is also used in the refinery or an online basis is often coupled to a control circuit to monitor product quality and make the necessary immediate adjustment in process conditions required to meet product specifications. While the online gas chromatograph is the most widely used instrument, infrared spectrometers, mass spectrometers, pH indicators, new infrared spectrometers with chemometric capability and moisture analysis based in solid-state conductors are not found in every refinery in the country. Until the 1970s, samples of most process streams in the refinery were taken at periodic intervals during the day and adjustments were made after the research was received from the refinery s analytical lab. This process was followed by the installation of online analysis equipment that sounded alarms, and the equipment operators took appropriate action. Today most operations are on computer control and the information received from online analytical equipment is processed almost continuously and controls make the required changes. An alarm may still sound and the equipment operator still responds, but usually the problem has already been corrected. 

Mass spectrometry has been utilized for on-line measurements for many years. The technique has been widely used in the petroleum industry as well as the chemical industry where the process stream contains primarily gases. This type of sample is the most compatible with the mass spectrometer and requires little sample preparation before introduction into the instrument. Early instruments designed for process monitoring did not have full scanning capability, but rather had several detectors at fixed position to monitor specific ions. Most of these instruments had the capability to monitor 5-7 components in the gas stream. These instruments were also widely used as leak detectors since they had the requisite sensitivity for low level detection and the speed to detect leaks very quickly. 

The first of the separation techniques to be used in process measurement was gas chromatography (GC) in 1954. The GC has always been a robust instrument and this aided its transfer to the process environment. The differences between laboratory GC and process GC instruments are important. With process GC, the sample is transferred directly from the process stream to the instrument. Instead of an inlet septum, process GC has a valve, which is critical for repetitively and reproducibly transferring a precise volume of sample into the volatiliser and thence into the carrier gas. This valve is also used to intermittently introduce a reference sample for calibration purposes. Instead of one column and a temperature ramp, the set up involves many columns under isothermal conditions. The more usual column types are open tubular, as these are efficient and analysis is more rapid than with packed columns. A pre-column is often used to trap unwanted contaminants, e.g. water, and it is backflushed while the rest of the sample is sent on to the analysis column. The universal detector - thermal conductivity detector (TCD)-is most often used in process GC but also popular are the FID, PID, ECD, FPD and of course MS. Process GC is used extensively in the petroleum industry, in environmental analysis of air and water samples" and in the chemical industry with the incorporation of sample extraction or preparation on-line. It is also applied for on-line monitoring of volatile products during fermentation processes" ... 

In petroleum refineries, process streams containing hydrogen also frequently contain hydrogen sulfide. This causes sulfidic corrosion. You know from experience that increasing the chromium content of a steel increases its resistance to corrosion by high-sulfur crudes. However, do not jump to the conclusion that chromium alloying always improves resistance to sulfidic corrosion. It does so if the operation is dirty, as it usually is in crude streams, or if the corrodents are elemental sulfur or sulfur compounds that do not decompose to release hydrogen sulfide. This increased resistance to sulfur corrosion depends on formation of a protective scale. With such scales, the corrosion rate is parabolic — it decreases with exposure time. 

Nearly all NMR instiunicnts produced today are of the F r type, and the use ot ( VV instruments is largely limited to special routine applicatiotts, such as the determination of the extent of hydrogenation in petroleum process streams and the determination of water in oils, food products, and agricultural materials, Despite this predominance of pulsed instruments in the tnarketplace, we find it convenient lo base our ini lial devolopmeni of NMR theory on C W experiments and move from there to a discussion of pulsed NMR measurements. 

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