Английский язык для обучающихся по направлению «Криогеника и нефтехимическое производство». Учебное пособие

sults in the following changes in the naphtha. The desirable reactions that take place in the cat reforming process are:

1.Paraffins are converted to isoparaffins.

2.Paraffins are converted to naphthenes.

3.Naphthenes are converted to aromatics.

The undesirable competing reactions that take place are:

1.Some of the paraffins and naphthenes crack, forming butanes and lighter

gases.

2.Some of the side chains break away from the naphthenes and aromatics, forming butanes and lighter gases. The main purpose of the cat reformer is to convert paraffins and naphthenes to aromatic compounds and some isomers.

Reformer Equipment

Hydrogen is an important by-product of catalytic reforming. Most of these reactions result in the production of extra hydrogen. This is because aromatics don’t have as many hydrogens as the naphthenes that are introduced as feed. Giving up the extra hydrogen is a endothermic process and thus the need for various stages as shown, with reactors and furnaces in series. The reforming process is also a user of hydrogen in the reactors. Hydrogen must be mixed with the feed to keep a high concentration of hydrogen vapors in the reactors. This prevents carbon atoms from depositing on the catalyst, as in cat cracking. Instead, the carbon reacts with the hydrogen and forms a hydrocarbon gas. As shown in Figure 17, part of the hydrogen stream is recycled to the feed while the other part is sent to the gas plant. The liquid product from the bottom of the separator is sent to a fractionator (called a stabilizer), which is similar to a debutanizer. The fractionator makes a bottom product called reformate, while butanes and lighter product are sent to the sats gas plant.

Regeneration

The three classes of reformers are: 1) semi-regenerative, 2) full regenerative, and 3) continuous regeneration. The semi-regenerative reformers were the original units from the early 1950s. When the catalyst became deactivated due to coke formation, the plant was shut down for regeneration. Thus the catalyst life was required to be at least six months. High pressure (up to 500 psig/34.5 barg) and lower temperatures were required to keep coke formation; thereby, catalyst deactivation was minimized. This produced octanes in the low 90s. Full regeneration reformers have five reactors. At any given time, four are in the process loop and one is being regenerated – with a fresh reactor coming on line every 20 to 30 hours. In the full regeneration scheme, pressures around 100 psig (6.9 barg) are possible and octane

71

numbers of the product were about 100. Continuous regeneration reformers are similar to full regeneration reformers in that about 20 to 30 percent of the catalyst is regenerated each day. However, in a continuous regeneration unit, this is accomplished by a system of stacked reactors and catalyst lock-hoppers to physically move the catalyst around the system.

The regeneration process is a real key in the cat reforming process. Of the steps shown, the most crucial step is the chlorination. Platinum is the active dehydrogenation agent on the catalyst, and it tends to agglomerate over the length of a run. The chlorine causes the platinum to re-disperse over the surface of the catalyst. In addition, a small amount of chloride must be placed on the catalyst to give an acidic function for isomerization activity. To summarize, catalytic reforming is an important process for upgrading low octane naphthas to a high octane-blending component reformate. Unfortunately, the higher the octane number of the reformate, the lower the yield and the more light ends produced.

Exercise 8. Translate into Russian the following words and word combinations:

catalytic reforming, low octane naphthas, high octane-blending component, motor fuels, fractionators, lock-hoppers, regeneration section, re-disperse, hydrocarbon gas.

Exercise 9. Complete the sentences:

1.Catalytic reforming … low octane naphthas to a high octane-blending component reformat.

2.… the process has been applied to the production of … and high purity aro-

matics.

3.Catalytic reforming typically results in …

4.… is an important by-product of catalytic reforming.

5.This is because aromatics don’t have as many … as the … that are introduced as feed.

6.The three classes of reformers are: … .

7.The semi-regenerative reformers were the original units from the early … .

8.Full regeneration reformers … .

9.Continuous regeneration reformers are similar to … .

Exercise 10. What new have you learned about catalytic reforming after reading the text?

72

Part II

Control Valve Guidelines

The process fluid hydrocarbons within a catalytic reformer plant are generally noncorrosive. Carbon steel bodies with 316 stainless trim can normally be used up to temperatures of 450 °F (232 °C). Above 450 °F (232 °C), 316 stainless steel bodies with 316 stainless steel trim with an Alloy 6 overlay should be considered. Globestyle valves with positioners (such as Valtek Mark One globe valves) are generally specified in valve sizes through 4-inch (DN 100). In valve sizes 6-inch (DN 150) and larger, rotary valves with hardened trim (such as the Valtek MaxFlo eccentric plug valve) are specified. Rotary valves are usually less costly that larger globe-style valves. Because NACE-compatible materials have less shaft/packing leakage, they are more attractive to the user when strict environmental standards are in place.

Control Valve Applications:

•Control Valve Applications

•Recycle Gas

•Vent Gas

•Vent Gas to Vent Drums

•Nitrogen Purge

•Flare Vent

•Recycle Gas

•Nitrogen to Regeneration Tower

•Air to Regeneration Tower

Recommended Control Valves

Valtek MaxFlo Eccentric Plug Valve – The MaxFlo control valve is used

in a number of catalytic reformer operations. The valve has a 200:1 turndown and has reduced trim options that are accomplished by simply changing the seat ring. The MaxFlo is offered in various configurations of body and trim materials, which can handle temperatures from cryogenic up to 800 °F (427 °C). Trim options include NACE, soft seat, hard seat, and solid Alloy 6 configurations. Antifugitive emission packing is also available. The Valtek rotary-motion spring cylinder actuator is designed for high performance operation and high torque, and is compact and lightweight.

73

Valtek Mark One Globe-style Valve – The Mark One control valve (Figure XX) is offered in sizes 0.5 - 42-inch/DN 15 - 1000) and in pressures ANSI Class 150 - 2500/PN16 - 400. It is constructed from carbon or 316 stainless steels, Hastelloy C, Alloy 20, or other alloys as required. To meet the requirements of refining industry, the standard Mark One configuration (carbon steel body/ 316 stainless steel trim) is built with NACE-compatible materials. The Mark One allows for interchangeable trim installations, including anti-noise, anti-cavitation, high CV, or low CV trims. Double-top stem guiding is used to keep the guiding surfaces out of the flow stream - this effectively avoids the use of cage-guided trim that stick or gall in dirty services. To ensure a tight packing seal and accurate guiding, the Mark One design includes large plug stem diameters. The Mark One high-performance spring cylinder actuator is field reversible, compact, lightweight, and easy to maintain.

Exercise 11. Translate into Russian the following words and word combinations:

noncorrosive, positioners, NACE-compatible materials, rotary valves, rotarymotion spring cylinder actuator, double-top stem guiding, high-performance spring cylinder actuator, cage-guided trim.

Exercise 12. Say whether the following statements are true or false:

1.The process fluid hydrocarbons within a catalytic reformer plant are generally corrosive.

2.Carbon steel bodies with 216 stainless trim can normally be used up to temperatures of 400 °F (232 °C).

3.Rotary valves are usually less costly that larger globe-style valves.

4.To meet the requirements of refining industry, the standard Mark One configuration is not built with NACE-compatible materials.

5.The Mark One allows for interchangeable trim installations, including antinoise, anti-cavitation, high CV, or low CV trims.

6.The Mark One high-performance spring cylinder actuator is field reversible, compact, lightweight, and easy to maintain.

74

Speaking

Case 1

Find in the text (both parts) the sentences that correspond to the following statements:

1.The role of catalytic reforming in refinery process.

2.Innovation has led to improvement of the process.

3.Description of important by-product of catalytic reforming.

4.Description of full regenerative, semi-regenerative and continuous regenerative classes of reformers.

5.A real key in the cat reforming process is revealed.

6.Control valve applications are given.

Case 2

Speak English on the following information:

1. Каталитический риформинг переформирует низкооктановые нафты

ввысокооктановые компоненты.

2.Первоначально каталитический риформинг был разработан для модернизации низкооктановой прямогонной нафты до высокооктановых моторных топлив, затем этот процесс применили для производства сжиженного нефтяного газа и ароматических веществ высокой чистоты.

3.Водород является важным побочным продуктом каталитического риформинга.

4.Большая часть из этих реакций приводит к в производству экстренного водорода. Это происходит потому, что ароматические вещества не имеют столько водорода, сколько нафтенов, которые вводятся в качестве исходного нефтяного сырья.

5.Жидкие углеводороды при обработке в установке каталитического риформинга, как правило, не вызывают коррозию.

Case 3

Speak on catalytic reformer:

1.What is the role of catalytic reforming in oil refinery? What was it designed for?

2.Is hydrogen an important by-product of catalytic reforming? Why? Is hydrogen mixed with any compounds?

75

3.What temperature and pressure is necessary for this process?

4.What three classes of reformers do you know?

5.What catalyst life is required to be?

6.Can you name the most famous control valves?

SECTION IX

Life Security and Troubleshooting in Cryogenic Engeneering

Grammar: Gerund, Participle I, Verbal Noun (repetition).

Word-formation: Suffix -ity.

Speaking: Providing long servicing life of refrigeration appliances.

Learn the pronunciation and the meaning of the words:

76

Grammar study: Gerund, Participle I, Verbal Noun

Brief characteristics of Gerund and Participle I see in Section I, subsection “Vocabulary development”.

Vocabulary development: word-formation: suffix -ity

Суффикс -ity образует существительные от прилагательных и глаголов со значением свойства, качества, состояния.

Samples: plastic (adj) пластичный – plasticity (n) пластичность; to simplify (v) упрощать – simplicity (n) упрощение.

77

Read the text, concerning safe technology in cryogenic production:

Text

Life Security and Troubleshooting in Cryogenic Engineering

1.One of the greatest challenges facing the designers of cryocoolers is achieving long life. A key issue is the possibility of internal gaseous contamination from lubricants and wear products associated with bearings or rubbing surfaces. It is admitted that a multi-year-life cryocooler must avoid rubbing surfaces and maintain a tolerance to small particulate contamination as well. The flexure bearings and piston clearance seals incorporated into the Oxford-style Stirling cryocooler are examples of the application of this rule.

2.Another important problem in early cooler applications was the difficulty to structurally attach it to a cryocooler's housing and heat-transfer interface without warping the cooler to violate its tight internal running clearances. Only a very small permanent deflection of the compressor or displacer structure can cause rubbing and accelerated wear of the compressor piston and/or displacer. With such coolers, one needs to be particularly sensitive about these issues and check at the time the system not to be violated by warpage associated with the cooler's structural/thermal attachment or by excessive coldfinger side loads.

3.Managing cryocooler-generated vibration is also the task of primary importance. Cryocoolers that incorporate low frequency compressors, such as Stirling, pulse tube and GM coolers, can generate significant vibratory forces at their drive frequency. The cooler vibration excites mechanical system resonances that degrade application performance with respect to parameters like optical resolution, pointing accuracy or electronic noise. The lowest vibration levels are achieved with cryocoolers, such as turbo-Brayton or sorption JT, which do not incorporate low-frequency compressors.

4.During cooler operation, performance deviates from predictions due to a wide variety of reasons. Measures for troubleshooting also involve providing for active temperature control. Many cryogenic applications require very tight regulation of the cold load temperature, often down to the milliKelvin level. To achieve very tight temperature regulation, one can couple the cold load to the cooler using a passive

78

thermal filter. Another common approach is to provide active temperature control via a small heater on the cold load.

In order to maintain this strict stratification of temperatures, the pulse tube design, for example, must carefully prevent any kind of gas mixing in the pulse tube due to turbulent flow or gravity caused convection.

A third approach is via closed loop control of the cryocoolers drive level. This latter means has been used in military Stirling coolers and later in space pulse tube coolers to provide control for space-instrument focal plane temperatures.

5.The mount of compressors in close proximity to the cold load raises the possibility of negative interactions with the compressor's electromagnetic fields, which are maximum at the cooler's 30-70 Hz drive frequency. Although the cooler magnetic fields have been found to cause no negative interactions with most applications, means have also been developed to greatly suppress the fields using mu-metal shielding attached to the cooler body.

6.Although the cryogenic application invariably requires a vacuum environment to be fully operational, an issue that often arises is the desire to run key portions of the integrated cryocooler and payload outside of its vacuum chamber where access for measurements and troubleshooting is greatly improved. Providing for this external operational capability may involve such things, as the design of temporary vacuum bonnets or purge gas enclosures that allow the cooler to be turned on and run during various short-term tests.

7.Very important thing in refrigeration and cryogenic systems is selecting the right refrigerant. When designing the refrigeration system, there are several refrigerant to choose from, such as chloroflurocarbons (CFCs), ammonia, hydrocarbons (propane, ethane, ethylene, etc.), carbon dioxide, air (in the air conditioning of aircraft) and even water (in applications above the freezing point).

Ethyl ether was the first commercially used, refrigerant in vapor compression systems in 1850, followed by ammonia and other above-mentioned gases. The industrial sectors were satisfied with ammonia and still are, although ammonia is toxic. The advantages of ammonia over other refrigerant are focused in its low cost, higher COPs (coefficient of performance) and thus lower energy costs, higher heat transfer coefficients, greater detectability in the event of a leak and no effect on the ozone

79

layer. The major drawback of ammonia is its toxicity, which makes it unsuitable for domestic use.

Later, in 1928, at the request of the Frigidaire Corporation, the General Motors research laboratory developed the CFC family of refrigerants under the trade name “Freon”. The versatility and low-cost of CFCs made them the refrigerant of choice. They were widely used in aerosols, foam insulation, polystyrol insulating materials and in the electronic industry as solvents to clean computer chips.

Thus, two important parameters needed to be considered in the selection of refrigerant are: the temperatures of the two media, i.e. the refrigerated space and the environment with which the refrigerant is to exchange heat. Other desirable characteristics of a refrigerant include: being non-toxic, non-corrosive, nonflammable and chemically stable, having a high enthalpy of vaporation in order to minimize the needed mass flow rate and, of course, an affordable cost.

Exercise 1. Find in the text the words in the form of Gerund, Participle I or Verbal Noun and define their status:

troubleshooting, facing, achieving, bearing, rubbing, housing, warping, running, managing, pointing, providing, mixing, shielding, selecting, conditioning, freezing, insulating.

Exercise 2. Translate the original and derived words:

Exercise 3. Give the title of each passage of the text, reflecting its contents:

1; 2; 3; 4; 5; 6; 7.

80