MAINTENANCE OF STOP DEVICES

Maintenance system of flowing wells includes equipment of their wellheads with X-mas trees. Key elements of X-mas tree are stop devices.

Plug valve and straight-flow valve sealed with grease do not require much effort to control them. In the process of operation of X-mas tree equipped with straight-flow valves stem bearings must be greased every two-three months. Grease must be also packed in compliance with instructions through the choke in the valve body bottom. Integrity of the straight-flow valve gate is improved due to sealing grease, which is automatically supplied to the gate surface by the medium pressure in the valve body.

When X-mas tree with plug stop valves is installed on a well, sealing grease must be additionally packed into all plug valves the gate functioning must be tested. Grease is added with an oil feeder, which is screwed into the stem threaded hole in the place of the pressure bolt. In the process of grease packing the plug valve must be either fully open or fully closed.

When the plug valve is filled with grease the pressure bolt must be put into initial position. Regular greasing of plug valve sealing surfaces provides for continuous integrity of the gate.

For reliable functioning of the gate grease presence in plug valve system must be regularly checked and grease must be packed as required.

Straight-flow valve or plug valve repairs include: disassembling and washing of details in a kerosene bath, their calibration and rejection, repair of deteriorated details and fabrication of new details, assembling of the valve and hydraulic testing.

Simple in design details, which do not require special thermal treatment are fabricated in a mechanical repair shop.

The words to be memorized:

1. straight-flow valve – прямоточная задвижка;

2. plug stop valves – крановые запорные устройства;

3. sealing grease – уплотнительная смазка;

4. oil feeder – масленка;

5. pressure bolt – нажимной болт;

6. grease packing – набивка смазки;

7. calibration and rejection –промер и отбраковка.

EXERCISE 11 Make up your own sentences using the following words:

Control valves, choke, fittings, gate valves, quick-union connections, stop valves, safety valves, plug valves.

EXERCISE 12 Translate the following text into English.

Трубопроводная арматура

Трубопроводная арматура предназначена для управления потоками нефти, транспортируемой по трубопроводам. Арматура делится на три класса: запорная, регулирующая и предохранительная.

Запорная арматура (задвижки) служит для полного перекрытия сечения трубопровода, регулирующая (регуляторы давления) – для изменения давления или расхода перекачиваемой жидкости, предохранительная (обратные и предохранительные клапаны) – для защиты трубопроводов и оборудования при превышении допустимого давления, а также предотвращения обратных токов жидкости. Задвижками называются запорные устройства, в которых проходное сечение перекрывается поступательным перемещением затвора в направлении, перпендикулярном направлению движения нефти.

Регуляторами давления называются устройства, служащие для автоматического поддержания давления на требуемом уровне.

Предохранительными клапанами называются устройства, предотвращающие повышение давления в трубопроводе сверх установленной величины.

EXERCISE 13 Make up your own topic “Pipeline valves and fittings” and be ready to retell it and discuss with your group mates.

CHAPTER III

OIL REFINING

EXERCISE 1 Read and translate the texts "Heat content" and "Refining methods", using the words after the texts.

HEAT CONTENT

Many economic considerations effecting production of different petroleum products are related to the amount of heat escaping when they burn. To select which flows should be used as refinery fuels we should take into consideration market price of petroleum products and also their heating value.

Two processes take place during hydrocarbon burning – chemical reaction and calorification. Chemical reaction usually means turning of hydrocarbon and oxygen into carbon dioxide and water.

Amount of heat escaping during the process varies for different hydrocarbons. Amount of heat in refining industry is normally measured in British Thermal units (1 BTU=1054,8Joules=252 calories).

One British Thermal unit equals to amount of heat needed for heating of one pound of water to 1°F.

There are two types of heating value. So called the highest heating value demonstrates total amount of heat, which escapes during chemical reaction (heat of combustion), and the lowest heating value shows condition of water generated during the reaction. Part of the chemical reaction heat is spent for water evaporation. Besides, not all the heat can be used, as it comes through the burner and out of the stack. The heavier is the fuel, the lower is ratio between hydrogen and carbon in its composition, and the less water is generated when it is burnt. This situation is reflected in heat efficiency value, which is calculated as ratio of net heat to total heating value.

REFINING METHODS

The most complex are refining methods including production of special valuable products, for example, lube oils or petrochemical products. Corresponding units have high complexity coefficients, which reflect CAPEX level for their construction. For example, complexity coefficient for aromatic hydrocarbons plant equals 33, and for production of olefins it is 10-20 (depending upon type of raw material and method of output product treatment). Pretty often refining method with output of chemical products (ethylene, propylene and aromatics) about 10% with complexity coefficient at least 16 is used. The idea of the analysis was to have a possibility to develop and use the chart reflecting dependability of refining costs upon its complexity accounting production scale effects.

The words to be memorized:

1. Carbondioxide – диоксид углерода (СО₂)

2. fueloil – котельное топливо

3. refinery – нефтеперерабатывающий завод

4. lubeoils – смазочные масла

5. Aromatic hydrocarbons – ароматические углеводороды

6. Olefin – олефин