Учебное пособие 1908

adsorbed from the cooling gas will be at the top of the bed and will not be desorbed into the gas during the dehydration step. The still hot regeneration gas and the cooling gas flow through the regeneration gas cooler to condense the desorbed water. Power-operated valves activated by a timing device switch the adsorbers between the dehydration, regeneration, and cooling steps.

Under normal operating conditions, the usable life of a desiccant ranges from one to four years. Solid desiccants become less effective in normal use due to loss of effective surface area as they age. Abnormally fast degradation occurs through blockage of the small pores and capillary openings from lubricating oils, amines, glycols, corrosion inhibitors, and other contaminants, which cannot be removed during the regeneration cycle. Hydrogen sulfide can also damage the desiccant and reduce its capacity.

Упражнение 4. Найдите в тексте данные ниже слова и словосочетания и напишите их русские эквиваленты.

Adsorption dehydration, water vapour, the solid desiccant, very large surface areas per unit weight, solid adsorbents, molecular sieves, dehydration plants, drying ability, a filter separator, to remove solid and liquid contaminants, the filtered gas, a desiccant bed, disturbance, velocity, a hot stream of inlet gas, the regeneration gas heater, a directfired heater, an indirect heater, the regeneration heat, the bottom of the bed, the regenerated bed, the cooling gas, the dehydration step, the regeneration gas cooler, the desorbed water, power-operated valves, a timing device, under normal operating conditions, the usable life of a desiccant, effective surface area, lubricating oils, corrosion inhibitors, capacity.

Упражнение 5. Найдите в тексте ответы на следующие вопросы.

1.What is adsorption due to its definition?

2.What features adsorption dehydration?

3.What are the most common solid adsorbents?

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4.Where are solid desiccants employed?

5.What is a filter separator used for?

6.What is the advantage of the down-flow arrangement?

7.What happens during the dehydration by adsorption?

8.What can supply the necessary regeneration heat?

9.What way does the regeneration heat usually flow?

10.How is the hot regenerated bed cooled?

11.Why does the cooling gas flow downward through the

bed?

12. What switches the adsorbers between the dehydration, regeneration and cooling steps?

13.Why do solid desiccants become less effective?

14.When does abnormally fast degradation occur?

Упражнение 6. Подберите из правой колонки соответствующие окончания предложений из левой колонки.

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Упражнение 7. Переведите предложения на английский язык.

1.Адсорбция – это способность вещества удерживать газы или жидкости на своей поверхности.

2.В процессе адсорбционной сушки водяные пары, находящиеся в газе, концентрируются и удерживаются на поверхности твердого влагоотделителя.

3.Для удаления твердых и жидких примесей из газа поступающий влажный газ должен быть очищен при помощи фильтра-влагоотделителя.

4.Пока один поглотитель осушает, другой поглотитель восстанавливается горячим потоком газа, поступающим из нагревателя с регенерационным газом.

5.Горячий восстановленный слой катализатора охлаждается при выключении нагревателя.

6.Горячий регенерационный газ и охлаждающий газ

проходят через охладитель регенерационного газа, чтобы конденсировать десорбированную воду.

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7.Приводная трубопроводная арматура, активированная таймером, переключает поглотители на режим сушки, регенерации и охлаждения.

8.Слишком быстрая деградация происходит из-за закупорки небольших пор и капиллярных отверстий смазочными маслами, аминами, гликолями, антикоррозионными добавками и другими примесями, которые нельзя удалить в ходе цикла регенерации.

9.Твердые влагопоглотители имеют очень большую площадь поверхности на единицу массы, чтобы успешно преодолеть поверхностное усилие.

10.Самыми распространенными твердыми поглотителями являются диоксид кремния, окись алюминия и некоторые другие силикаты, известные как ультрафильтр.

Упражнение 8. Переведите текст, не пользуясь словарем, и озаглавьте его.

The advantages of solid desiccant dehydration include:

lower dew point, essentially dry gas (water content less 1.0 lb/MMcf) can be produced

higher contact temperatures can be tolerated with some adsorbents

higher tolerance to sudden load changes, especially on

startup

quick startup after shutdown

high adaptability for recovery of certain liquid hydrocarbons in addition to dehydration functions.

Operating problems with the solid-desiccant dehydration include:

space adsorbents degenerate with use and require replacement

dehydrating tower must be regenerated and cooled for operation before another tower approaches exhaustion. The maximum allowable time on dehydration gradually shortens

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because desiccant loses capacity with use.

Although this type of dehydrator has high adaptability to sudden load changes, sudden pressure surges should be avoided because they may upset the desiccant bed and channel the gas stream resulting in poor dehydration. If a plant is operated above its rated capacity, high-pressure loss may cause some attrition to occur. Attrition causes fines, which may in turn cause excessive pressure loss and result in loss of capacity.

Replacing the desiccant should be scheduled and completed ahead of the operating season. To maintain continuous operation, this may require discarding the desiccant before its normal operating life is reached. To cut operating costs, the inlet part of the tower can be recharged and the remainder of the desiccant retained because it may still possess some useful life. Additional service life of the desiccant may be obtained if the direction of gas flow is reversed at a time when the tower would normally be recharged.

Упражнение 9. Составьте аннотацию текста (упр. 8).

UNIT 10

Упражнение 1. Прочтите слова и словосочетания и постарайтесь запомнить их русские эквиваленты.

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Упражнение 2. Переведите слова, обращая внимание на суффиксы и префиксы.

To move – to remove; essential – essentially; to dehydrate – dehydration – dehydrator; to contact – contactor; to boil – boiler; vapor – to vaporize; relative – relatively; to use – to reuse; to condense – condenser.

Упражнение 3. Прочтите и переведите интернациональные слова.

Glycol, an agent, absorption, a contact, diethylene glycol, triethylene glycol, differential, an innovation, methane, a portion, organic, practice, atmosphere.

Прочтите и переведите текст, а затем выполните следующие упражнения.

GLYCOL DEHYDRATION

Absorption occurs when the water vapor is taken out by a dehydrating agent. Glycol Dehydration is an example of absorption dehydration. In this process, a liquid desiccant dehydrator serves to

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absorb water vapor from the gas stream. Glycol, the principal agent in this process, has a chemical affinity for water. This means that, when in contact with a stream of natural gas that contains water, glycol will serve to ‘steal’ the water out of the gas stream. Essentially, glycol dehydration involves using a glycol solution, usually either diethylene glycol (DEG) or triethylene glycol (TEG), which is brought into contact with the wet gas stream in what is called the ‘contactor’. The glycol solution will absorb water from the wet gas. Once absorbed, the glycol particles become heavier and sink to the bottom of the contactor where they are removed. The natural gas, having been stripped of most of its water content, is then transported out of the dehydrator. The glycol solution, bearing all of the water stripped from the natural gas, is put through a specialized boiler designed to vaporize only the water out of the solution. While water has a boiling point of 212 degrees Fahrenheit, glycol does not boil until 400 degrees Fahrenheit. This boiling point differential makes it relatively easy to remove water from the glycol solution, allowing it be reused in the dehydration process.

An innovation in this process has been the addition of flash tank separator-condensers. As well as absorbing water from the wet gas stream, the glycol solution occasionally carries with it small amounts of methane and other compounds found in the wet gas. In the past, this methane was simply vented out of the boiler. In addition to losing a portion of the natural gas that was extracted, this venting contributes to air pollution and the greenhouse effect. In order to decrease the amount of methane and other compounds that are lost, flash tank separator-condensers work to remove these compounds before the glycol solution reaches the boiler. Essentially, a flash tank separator consists of a device that reduces the pressure of the glycol solution stream, allowing the methane and other hydrocarbons to vaporize (‘flash’). The glycol solution then travels to the boiler, which may also be fitted with air or watercooled condensers, which serve to capture any remaining organic compounds that may remain in the glycol solution. In practice these systems have been shown to recover 90 to 99 percent

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of methane that would otherwise be flared into the atmosphere.

Упражнение 4. Найдите в тексте данные ниже слова и словосочетания и напишите их русские эквиваленты.

The water vapor, a dehydrating agent, absorption dehydration, a liquid desiccant dehydrator, a chemical affinity for water, a glycol solution, the wet gas, particles, a flash tank separator-condensers, the greenhouse effect, air or watercooled condensers, to capture, compounds, to recover, to flare.

Упражнение 5. Найдите в тексте ответы на следующие вопросы.

1.When does absorption occur?

2.What is absorption dehydration characterized by?

3.What does glycol dehydration involve?

4.What process does the glycol solution undergo?

5.Why is it possible to remove water from the glycol

solution?

6.What is new in the glycol dehydration process?

7.What is the advantage of a flash tank separatorcondenser?

8.What does a flash tank separator consist of?

9.What is the function of air or water-cooled condensers?

10.What is the efficiency of the system?

Упражнение 6. Подберите из правой колонки соответствующие окончания предложений из левой колонки.

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Упражнение 7. Переведите текст, пользуясь словарем.

DEHYDRATION BY COOLING

The ability of natural gas to contain water vapour decreases

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as the temperature is lowered at constant pressure. During the cooling process, the excess water in the vapour state becomes liquid and is removed from the system. Natural gas containing less water vapour at low temperature is output from the cooling unit. The gas dehydrated by cooling is still at its water dew point unless the temperature is raised again or the pressure is decreased. Cooling for the purpose of gas dehydration is sometimes economical if the gas temperature is unusually high. It is often a good practice that cooling is used in conjunction with other dehydration processes.

Gas compressors can be used partially as dehydrators. Because the saturation water content of gases decreases at high pressure, some water is condensed and removed from gas at compressor stations by the compressor discharge coolers. Modern lean oil absorption gas plants use mechanical refrigeration to chill the inlet gas stream. Ethylene glycol is usually injected into the gas chilling section of the plant, which simultaneously dehydrates the gas and recovers liquid hydrocarbons, in a manner similar to the low-temperature separators.

Упражнение 8. Переведите предложения на английский

язык.

1.Абсорбция происходит при удалении водяного пара обезвоживающим средством.

2.Гликоль является осушителем с жидким поглотителем

ииспользуется для абсорбции водяного пара из газового потока.

3.Раствор гликоля поглощает воду из влажного газа.

4.Поглотив влагу, частицы гликоля становятся тяжелее и опускаются на дно контактного фильтра для последующего удаления.

5.Раствор гликоля, насыщенный водой из природного газа, пропускается через специальный котел для выпаривания воды из раствора.

6.Устройство, находящееся в сепараторе испарительного

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