Fig. 1.1 Natural water circulation

ФЕДЕРАЛЬНОЕ ГОСУДАРСТВЕННОЕ БЮДЖЕТНОЕ ОБРАЗОВАТЕЛЬНОЕ УЧРЕЖДЕНИЕ ВЫСШЕГО ОБРАЗОВАНИЯ

«КЕРЧЕНСКИЙ ГОСУДАРСТВЕННЫЙ МОРСКОЙ ТЕХНОЛОГИЧЕСКИЙ УНИВЕРСИТЕТ»

Кафедра иностранных языков

Маркевич Т.А.

ИНОСТРАННЫЙ ЯЗЫК

(АНГЛИЙСКИЙ)

Практикум “Marine Steam Boilers”

по проведению и подготовке

к практическим занятиям

и самостоятельной работе

для курсантов 3 курса специальности

26.05.06 «Эксплуатация судовых энергетических установок»

очной и заочной формы обучения

Керчь, 2017 г.

УДК 811.111’276.6:621.3

Составитель: Маркевич Т.А., ст. преподаватель кафедры иностранных языков

ФГБОУ ВО «КГМТУ» __________________

Рецензент: __________________

Практикум рассмотрен и одобрен на заседании кафедры иностранных языков ФГБОУ ВО «КГМТУ»,

протокол № от 20 г.

Зав. кафедрой ________________ О.Н. Кручина

Практикум утвержден и рекомендован к публикации

на заседании методической комиссии МФ ФГБОУ ВО «КГМТУ»,

протокол № ___от_________20___ г.

ФГБОУ ВО «КГМТУ», 2017 г.

СОДЕРЖАНИЕ

ВВЕДЕНИЕ …………………………………………………………………........ UNIT 1. BOILER WATER CIRCULATION UNIT 2. BOILER CLASSIFICATION UNIT 3. BOILER DESIGN AND CONSTRUCTION UNIT 4. THE FURNACE UNIT 5. BOILERS ACCESSORIES UNIT 6. BOILER MOUNTINGS UNIT 7. BOILER WATER TREATMENT AND CLEANING Cписок использованной (рекомендуемой) литературы………………………..

ВВЕДЕНИЕ

Данный «Практикум» представляет сборник текстов и упражнений, предназначенных для аудиторной и самостоятельной работы курсантов и студентов 3 курса специальности 26.05.06 «Эксплуатация судовых энергетических установок» и охватывает круг вопросов, связанных с особенностями конструкций двигателей внутреннего сгорания, их эксплуатации и областями применения.

Цель «Практикума» – развитие навыков технического перевода, накопление и усвоение лексического материала, необходимого как для чтения, так и для развития навыков устной речи. Упражнения направлены на формирование словарного запаса, преодоление трудностей перевода и приобретение разговорных навыков.

Сборник рассчитан на курсантов (студентов), имеющих запас знаний и продолжающих изучение английского языка в ВУЗе.

Тематика текстов подобрана в соответствии с требованиями к обязательному минимуму содержания дисциплины «Иностранный язык (Английский язык)», входящей в основную образовательную программу подготовки специалистов по специальности 26.05.06 «Эксплуатация судовых энергетических установок» Федерального государственного образовательного стандарта высшего образования.

UNIT 1

BOILER WATER CIRCULATION

A boiler is a closed vessel in which water is heated, steam is generated, superheated or any combination thereof under pressure or vacuum by the direct application of heat from combustible fuels or electricity.

A boiler should fulfill the following requirements:

(i) Safety. The boiler should be safe under operating conditions.

(ii) Accessibility. The various parts of the boiler should be accessible for repair and maintenance.

(iii) Capacity. The boiler should be capable of supplying steam according to the requirements.

(iv) Efficiency. To permit efficient operation, the boiler should be able to absorb a maximum amount of heat produced due to burning of fuel in the furnace.

(v) It should be simple in construction and its maintenance cost should be low.

(vi) Its initial cost should be low.

(vii) The boiler should have no joints exposed to flames.

(viii) The boiler should be capable of quick starting and loading.

The performance of a boiler may be measured in terms of its evaporative capacity also called power of a boiler. It is defined as the amount of water evaporated or steam produced in kg per hour. It may also be expressed in kg per kg of fuel burnt or kg/hr/m² of heating surface.

Operating pressure – the pressure at which the boiler is operated in service

Boiler efficiency -the ratio between the thermal energy actually absorbed by water and the thermal energy available in fuel (80 – 90 %)

Steaming hours -the time during which the boiler generates steam

Heating surface -the total surface of all parts exposed to combustion gases (tubes, superheater, economiser)

Fig. 1.1 Natural water circulation - student2.ru Generating surface - a part of the surface in which water is heated and steam is generated (drum)

Superheated steam= saturated steam + more heat at constant pressure –> dry steam (to avoid damage to turbine blades)

A boiler is designed to convert the chemical energy contained in fuel to heat energy in the steam. This steam is then available to do work in a variety of systems onboard.

The figure illustrates the circulation pattern of a water tube boiler system. (While only one design is shown, all marine oilfired boilers function in a similar pattern).

VOCABULARY

to convert превращать

to contain содержать

heat energy тепловая энергия

to be available иметься, быть в наличии

a variety of systems onboard различные судовые системы

a water tube boiler водотрубный котел

similar сходный, подобный

directly непосредственно

furnace топка

to be surrounded быть окруженным

to fit оснащать, оборудовать

through headers через коллекторы

the upper and lower drums верхний и нижний барабаны

generating tubes генерирующие трубы

recirculating water in the tubes вода, рециркулирующая в трубах

density плотность

to decrease понижать

downcomer tubes нисходящие трубы

natural circulation естественная циркуляция

steam/water mixture пароводяная смесь

superheater пароперегреватель

incoming feed-water поступающая питательная вода

to add добавлять

auxiliary systems вспомогательные системы

condenser конденсатор

to complete завершать

a waste heat economizer экономайзер-утилизатор

exhaust gases выхлопные(уходящие) газы

an auxiliary boiler вспомогательный котел

main engine главный двигатель

due to из-за, по причине, вследствие

EXERCISES

Exercise 1.Read these word combinations and remember their translation.

To convert the chemical energy contained in fuel to heat energy in the steam, to do work, a water tube boiler system, all marine oilfired boilers, in this way, it tends to rise, a natural circulation, the upper half of the drum, through the complete water circuit, through the steam line, more heat is added, increasing the energy in the steam, a high pressure turbine, the feed system, may be bled off from the turbine system for feedwater heating, similar processes, energy can be fully utilized, completing the boiler/feed system circuit, operating at lower pressure levels, the feed equipment, to be in operation, the boilers used for propulsion, to function under the same principles, to be subject to many of the same problems.

UNIT 2

BOILER CLASSIFICATION

The boilers can be classified according to the following criteria.

BASE OF CLASSIFICATION	TYPES
1. Content of the tubes	a. Fire tube b. Water tube
2. Steam pressure	a. High Pressure(up to 145 bar) b. Intermediate boilers (from 30 to 70 bar) c. Low Pressure (up to 30 bar)
3. Type of water circulation	a. Natural circulation b. Forced circulation
4. Application	a. Stationary b. Mobile (Marine, Locomotive)
5. Position of axis	a. Vertical b. Horizontal c. Inclined
6. Position of furnace	a. Internally fired b. Externally fired
7. Type of fuel	a. Coal fired b. Oil fired c. Gas fired

By their application on board ships, boilers are classified as main boilers or donkey boilers.

Main boilers generate steam for the main engine that drives the propeller and for auxiliary duties.

Donkey boilers are mainly used on diesel-driven ships to supply steam for driving steam pumps and turbo-generators, for oil heating, water heating, space heating, galley and laundry.

In water tube boilers, water circulates through the tubes and hot products of combustion flow over these tubes. In fire tube boiler the hot products of combustion pass through the tubes, which are surrounded by water. Fire tube boilers have low initial cost, and are more compacts. But they are more likely to explosion, water volume is large and due to poor circulation they cannot meet quickly the change in steam demand. For the same output the outer shell of fire tube boilers is much larger than the shell of water-tube boiler. Water tube boilers require less weight of metal for a given size, are less liable to explosion, produce higher pressure, are accessible and can response quickly to change in steam demand. Tubes and drums of water-tube boilers are smaller than that of fire-tube boilers and due to smaller size of drum higher pressure can be used easily.

Water-tube boilers require lesser floor space. The efficiency of water-tube boilers is more.

VOCABULARY

boiler котел

Scotch ~ шотландский котел

water-tube ~ водотрубный котел

smoke-tube ~ котел с дымогарными трубами

auxiliary ~ вспомогательный котел

barrel ~ цилиндрический котел

circulation ~ котел с естественной циркуляцией

cross-drum ~ котел с поперечным расположением барабана

donkey ~ вспомогательный котел

flue ~ дымогарный котел

hot-water ~ водогрейный котел

oil-burning ~ мазутный котел

propulsion ~ главный паровой котел

single-furnace ~ однокорпусный котел

steam ~ паровой котел

two-drum ~ двухбарабанный котел

two-furnace ~ двухкорпусный котел

waste-heat ~ котел-утилизатор

EXERCISES

I. Translate into English.

Главный котел, вспомогательный котел, потребители пара, топливная система котла, система подвода воздуха, теплота продуктов сгорания, сжигание органического топлива в топке, подогрев воды, испарение воды, водотрубные котлы, пароводяная смесь, двигаться внутри труб, омываемые снаружи водой, омываемые снаружи горячими газами, огнетрубные котлы, котлы с естественной циркуляцией (ЕЦ); котлы с принудительной циркуляцией (ПЦ), работающие на твердом топливе (уголь и угольная пыль) котлы, работающие на жидком топливе (мазуты, дизельное топливо) котлы; работающие на газообразном топливе котлы.

II. Complete the diagram below using the information from the text:

Boilers

Tube contain

Method of firing

Circulation of water

Steam pressure

IV. Translate into English.

1. Паровые котлы, установленные на судах, классифицируются по ряду признаков.

2. В зависимости от назначения различают главные и вспомогательные котлы.

3. Главные паровые котлы вырабатывают пар для двигателей (паровых машин, паровых турбин), приводящих в движение судовые движители, а также для вспомогательных механизмов.

4. Вспомогательные паровые котлы вырабатывают пар только для вспомогательных механизмов, для хозяйственно-бытовых и технологических нужд судна.

5. В зависимости от циркуляции воды и пароводяной смеси различают котлы с естественной и принудительной циркуляцией.

6. В котлах с естественной циркуляцией движение воды происходит из-за разности ее удельного веса в нисходящих трубах и пароводяной смеси в подъемных.

7. В котлах с принудительной циркуляцией вода движется по трубам под действием давления, создаваемого специальными насосами.

8. В зависимости от рода сжигаемого топлива различают котлы, работающие на твердом и жидком топливе.

9. В утилизационных котлах используется тепло выхлопных газов двигателей внутреннего сгорания.

10. По величине давления вырабатываемого пара котлы бывают низкого, среднего, и высокого давления.

UNIT 3

Figure 2.1 Boiler design

The combustion chamber, usually made of cast iron or steel, houses the burners and combustion process. Temperatures inside the combustion chamber can reach several hundred degrees very quickly.

Heat exchangers may be made from cast iron, steel tube bundles, or, in the case of some smaller boilers, copper or copper-clad steel.

The exhaust stack or flue is the piping that conveys the hot combustion gasses away from the boiler to the outside. Typically, this piping is made of steel, but in the case of condensing boilers it needs to be constructed of stainless steel to handle the corrosive condensate. Another consideration is whether the exhaust stack will be under a positive or negative pressure. This can determine how the joints of the exhaust stack must be sealed.

Boiler controls help produce hot water or steam in a regulated, efficient, and safe manner. Combustion and operating controls regulate the rate of fuel use to meet the demand. The main operating control monitors hot water temperature or steam pressure and sends a signal to control the firing rate, the rate at which fuel and air enters the burner. Common burner firing sequences include on/off, high/low/off and modulating.

Boiler safety controls include high pressure and temperature, high and low gas/oil pressure, and high and low water level and flame safeguard controls. These controls are considered safeties or limits that break the electrical circuit to prevent firing of the boiler. Flame safeguard controls are programmed to operate the burner and cycle it through the stages of operation.

All boilers have a furnace or combustion chamber where fuel is burnt to release its energy. Air is supplied to the boiler furnace to enable combustion of the fuel to take place. A large surface area between the combustion chamber and the water enables the energy of combustion, in the form of heat, to be transferred to the water.

A drum must be provided where steam and water can separate. The steam drum is also used for the following:

1. To mix the saturated water that remains after steam separation with the incoming feedwater

2. To mix the chemicals that are put into the drum for the purpose of corrosion control and water treatment

3. To purify the steam by removing contaminants and residual moisture

4. To provide the source for a blowdown system where a portion of the water is rejected as a means of controlling the boiler water chemistry and reducing the solids content

5. To provide a storage of water to accommodate any rapid changes in the boiler load.

All of the tubing surrounding the furnace is called heat transfer surface.

There must also be a variety of fittings and controls to ensure that fuel oil, air and feedwater supplies are matched to the demand for steam. Finally there must be a number of fittings or mountings which ensure the safe operation of the boiler.

The steam is produced in a steam drum and may be drawn off for use from here. It is known as 'wet' or saturated steam in this condition because it will contain small quantities of water. Alternatively, the steam may pass to a superheater which is located within the boiler. Here steam is further heated and 'dried', i.e. all traces of water are converted into steam. This superheated steam then leaves the boiler for use in the system. The temperature of superheated steam will be above that of the steam in the drum. The hot gases produced in the furnace are used to heat the feedwater to produce steam and also to superheat the steam from the boiler drum. The gases then pass over an economiser through which the feedwater passes before it enters the boiler. The exhaust gases may also pass over an air heater which warms the combustion air before it enters the furnace. In this way a large proportion of the heat energy from the hot gases is used before they are exhausted from the funnel.

VOCABULARY

feedwater in order to to produce watertube boiler firetube boiler furnace combustion chamber to release drum to provide to separate fittings to ensure to enter to pass through to pass outside to surround large - bore downcomer tubes to join superheater burner water wall tube water wall header alternative wind box generating tube floor tube funnel stage forced draught fan = FD fan incoming feedwater attemperator heating surface tank boiler shell single-ended end plate working pressure uptake tube plate plain tube stay tube

питательная вода для того, чтобы вырабатывать, производить водотрубный паровой котел огнетрубный паровой котел топка камера сгорания выделять барабан обеспечивать разделять, отделять арматура, фитинговые соединения (трубопроводов) обеспечивать входить проходить через проходить снаружи окружать с большим (внутренним) диаметром нисходящие трубки соединять пароперегреватель форсунка водогрейная трубка топочного экрана коллектор топочного экрана альтернативное воздухонаправляющее устройство водогрейная труб(к)а днищевая труба дымовая труба ступень, цикл, стадия котельный вентилятор поступающая питательная вода регулятор температуры пара поверхность нагрева цилиндрический котел корпус односторонний заднее днище (котла) рабочее давление вытяжная труба трубная доска простая дымогарная трубка связная дымогарная трубка

EXERCISES

I. Translate into Russian.

The combustion chamber, cast iron, the burners, heat exchanger, copper, copper-clad steel, stainless steel, to handle the corrosive condensate, the joints of the exhaust stack, to be sealed, in a safe manner, to meet the demand, the main operating control, the firing rate, flame safeguard controls, to break the electrical circuit, to prevent firing of the boiler, in the event, the pressure limit setting, the fuel valve, switch contacts for low water cutoff, high limits, air proving switches, redundant safety and operating controls, and flame detectors.

UNIT 5

BOILERS ACCESSORIES

Boilers Accessories are auxiliary plants or parts required for steam boilers for their operation and to increase efficiency of the boiler. Following accessories are commonly used with boiler:

1. Feed pumps

2. Injector

3. Economizer

4. Air preheater

5. Superheater

6. Steam separator

7. Steam trap.

Superheaters

A superheater is a device found in steam boilers that is used to convert wet, saturated steam into dry steam. Superheaters are a very beneficial part of the steam cycle, because dry steam contains more thermal energy and increases the overall efficiency of the cycle. The function of superheater is to increase the temperature of the steam generated by boiler above its saturation point, using the hot flue or exhaust gases coming from the combustion chamber of the furnace. Super heaters are heat exchangers.

Superheaters are essentially a bank of tubes, in the exhaust gas duct after the boiler, used to heat the steam above the saturation temperature. The saturated steam enters the inlet header from piping connected to the steam drum. In a superheater, the saturated steam flows from the saturated header through the superheater elements into the superheater outlet header.

Superheaters are referred to as convection, radiant, or combination types.

Fig. 1.1 Natural water circulation - student2.ru

Words to be Known

superheated steam перегретый nap

heat loss потеря тепла

decreased steam rates уменьшенный расход пара

saturated steam насыщенный пар

superheating surface поверхность перегрева

reheater superheater промежуточный пароперегреватель

to employ использовать

desuperheater пароохладитель

desuperheated steam охлажденный nap

to maintain поддерживать

uniform steam flow равномерный поток пара

radiant superheater радиационный пароперегреватель

convection конвективный

gas passages газоходы

to exceed превышать

tensile strength предел прочности

shell корпус, кожух

safety valve предохранительный клапан

to discharge стравливать

III. Translate into English

1. Пароперегреватель изготавливается из стальных труб, образующих поверхность нагрева для проходящего по ним пара.

2. Хотя пароперегреватель может быть выполнен в виде подключенного к котлу отдельного агрегата с собственной топкой, как правило, пароперегреватели встраивают в систему парогенератора.

3. Встроенные пароперегреватели бывают двух видов: радиационные и конвективные.

4. В зависимости от направления движения газов и пара различают три основные схемы включения пароперегревателя в газовый поток: прямоточную (а) — газы и пар движутся в одном направлении; противоточную (б) — газы и пар движутся в противоположных направлениях; смешанную (в) — в одной части пароперегревателя газы и пар движутся прямоточно, а в другой — в противоположных направлениях.

Economisers

Economisers are heat exchangers which are fitted in a boiler to increase the efficiency of the boiler. This is done by extracting the heat from the exiting gas and using it to heat the feed water entering the boiler.

The flue gases, having passed through the main boiler and the superheater, will still be hot. The energy in these flue gases can be used to improve the thermal efficiency of the boiler. To achieve this the flue gases are passed through an economiser.

Fig. 1.1 Natural water circulation - student2.ru

The economiser is a heat exchanger through which the feedwater is pumped. The feedwater thus arrives in the boiler at a higher temperature than would be the case if no economiser was fitted. Less energy is then required to raise the steam. Alternatively, if the same quantity of energy is supplied, then more steam is raised. This results in a higher efficiency. In broad terms a 10°C increase in feedwater temperature will give an efficiency improvement of 2%.

The economiser is interposed between the boiler and the stack. The water is pumped through the economizer on its way to the boiler. The gases leaving the boiler pass through the economizer before going to the stack. The heat absorbed by the water in passing through the economizer would otherwise be lost. Economizers reduce the losses to a minimum.

An economizer consists of a series of tubes through which feed water flows, surrounded on the outside by the hot gases.

Present practice is to make the economizer an all-steel unit. The tubes are rolled into the headers. When headers are not employed, return bends are used. The ratio of boiler to economizer heating surface is about 2 to 1.

Economizers are parallel or counterflow-parallel when the gases and water flow in the same direction; counterflow when they flow in opposite directions. The counterflow is considered to be the more effective, resulting in a greater heat transfer. In the counterflow, the gases leaving the boiler enter the economizer at the end from which the water makes its exit.

Words to be Known

feed-water heater подогреватель питательной воды

flue gases топочные газы

to interpose размещать

stack дымовая труба

to lose (lost; lost) терять

series of tubes ряд трубок

all-steel unit стальной узел

return bend обратное колено трубы

flange joints фланцевые соединения

to range колебаться в пределах

ratio соотношение

counterflow противоток

opposite противоположный

heat transfer теплопередача

III. Translate into English

1. Экономайзер - это теплообменник, где питательная вода подогревается при помощи уходящих из котла газов.

2. Экономайзер представляет собой устройство, которое обогревается продуктами сгорания топлива.

3. Подобное устройство предназначено для подогрева либо для частичного испарения воды, которая поступает в паровой котёл.

4. Высокотемпературный перегретый пар позволяет повысить экономичность паровых машин и турбин, так как потребление ими пара снижается примерно на 1% с увеличением перегрева на 5° C.

UNIT 6

BOILER MOUNTINGS

Certain fittings are necessary on a boiler to ensure its safe operation. They are usually referred to as boiler mountings. The mountings usually found on a boiler are:

Safety valves. Safety valves are fitted in pairs, usually on a single valve chest. Each valve must be able to release all the steam the boiler can produce without the pressure rising by more than 10% over a set period.

Spring-loaded valves are always fitted on board ship because of their positive action at any inclination. They are positioned on the boiler drum in the steam space. The valve is held closed by the helical spring, whose pressure is set by the compression nut at the top. The spring pressure, once set, is fixed and sealed by a Surveyor. When the steam exceeds this pressure the valve is opened and the spring compressed. The escaping steam is then led through a waste pipe up the funnel and out to atmosphere.

Figure 6.1 – Safety valveThe compression of the spring by the initial valve opening results in more pressure being necessary to compress the spring and open the valve further. To some extent this is countered by a lip arrangement on the valve lid which gives a greater area for the steam to act on once the valve is open. A manually operated easing gear enables the valve to be opened in an emergency. Various refinements to the ordinary spring-loaded safety valve have been designed to give a higher lift to the valve.

Main steam stop valve. This valve is fitted in the main steam supply line and is usually of the non-return type. It regulates the flow of steam supply outside. The steam from the boiler first enters into an anti-priming pipe where most of the water particles associated with steam is removed.

Auxiliary steam stop valve. This is a smaller valve fitted in the auxiliary steam supply line, and is usually of the non-return type.

Feed check or control valve. A pair of valves are fitted: one is the main valve, the other the auxiliary or standby. They are non-return valves and must give an indication of their open and closed position. The high pressure feed water is supplied to the boiler through this valve. This valve opens towards the boiler only and feeds the water to the boiler. If the feed water pressure is less than the boiler steam pressure then this valve remains closed and prevents the back flow of steam through the valve. Feed check or control valve prevent backflow from the boiler through the feedwater line into the condensate/feedwater tank during the off cycle of the pump.

Water level gauge. Water level gauges or 'gauge glasses' are fitted in pairs, at opposite ends of the boiler. The construction of the level gauge depends upon the boiler pressure. This indicates the water level in the boiler, the water level in the boiler should not fall below a particular level otherwise the boiler will be overheated and the tubes may burn out.

Fusible Plug. If the water level in the boiler falls below a predetermined level, the boiler shell and tubes will be overheated. And if it is continued, the tubes may burn, as the water cover will be removed. It can he prevented by stopping the burning of fuel on the grate. When the temperature of the shell increases above a particular level, the fusible plug, which is mounted over the grate, melts and forms an opening. The high-pressure steam pushes the remaining water through this hole on the grate and the fire is extinguished.

Figure 6.2 - Fusible Plug

Pressure gauge connection. Where necessary on the boiler drum, superheater, etc., pressure gauges are fitted to provide pressure readings. Pressure gauge connection indicates the pressure of the steam in the boiler.

Air release cock. These are fitted in the headers, boiler drum, etc., to release air when filling the boiler or initially raising steam. An air cock is located in the uppermost steam space of a boiler. This design allows for air to enter and escape during filling and draining of the boiler. Before firing a cold boiler with no steam pressure, open the air cock to allow air to escape during the heating of the water. When steam begins to come out of the air cock piping, close the valve.

Sampling connection. A water outlet cock and cooling arrangement is provided for the sampling and analysis of feed water. A provision may also be made for injecting water treatment chemicals.

Blow down valve. This valve enables water to be blown down or emptied from the boiler. It may be used when partially or completely emptying the boiler. The blowdown valves on a boiler are used to remove scale and other foreign matter that have settled in the lowest part of the water spaces. Boilers are also blown down to control concentration of dissolved and suspended solids in boiler water. The water column blowdown permits removal of scale and sediments from the water column.

Scum valve. A shallow dish positioned at the normal water level is connected to the scum valve. This enables the blowing down or removal of scum and impurities from the water surface.

Whistle stop valve. This is a small bore non-return valve which supplies the whistle with steam straight from the boiler drum.

VOCABULARY

valve chest клапанная коробка

safety valve предохранительный клапан

helical spring спиральная пружина

compression nut стяжная гайка

main stop valve главный стопорный паровой клапан

auxiliary steam stop valve вспомогательный стопорный клапан.

non - return valve невозвратный клапан

water level indicator датчик уровня воды

drain valve дренажный клапан

salinometer valve солемерный клапан

chemical dosing valve дозировочный клапан

blow down valve клапан продувки котла

discharge tube сливная труба

evaporating tube испарительная (парогенерирующая) труба

scum valve 1) продувочный клапан 2) клапан верхнего продувания

whistle stop valve cтопорный клапан свистка

sampling connection aрматура для взятия проб

steam space паровое пространство

to refer to относиться, ссылаться, зд. называться

mountings гарнитура(котла)

to mount устанавливать

to fit устанавливать

main steam supply line главный паропровод

auxiliary steam supply line вспомогательный паропровод

feed check or control valve регулировочный клапан

water - level gauge водомерное стекло

air release cock воздуховыпускной кран

pressure gauge connections манометровые штуцера

fusible plug плавкий предохранитель

the back flow of steam обратное перетекание котловой воды

the off cycle of the pump отключение насоса по завершению рециркуляции теплоносителя

a predetermined level заданное значение регулируемой величины

the grate колоснико́вая решётка

EXERCISES

Exercise 1.Read these word combinations and remember their translation.

Boiler mountings, a single valve chest, spring-loaded valves, the steam space, the helical spring, the compression nut, the escaping steam, the initial valve opening, a lip arrangement, the valve lid, manually operated easing gear, the main steam supply line, an anti-priming pipe, the auxiliary steam supply line, the back flow of steam, the off cycle of the pump, a predetermined level, pressure readings, initially, partially or completely, foreign matter, dissolved and suspended solids, scale and sediments.

Exercise 6. True or False?

T	F	The water level in the boiler should fall below a particular level otherwise the boiler
T	F	The function of the safety valve is to prevent the decrease of steam pressure in the boiler above its design pressure.
T	F	When the pressure increases above design pressure, the valve opens and discharges the steam to the atmosphere.
T	F	When this pressure falls just below design pressure, the valve opens automatically.
T	F	Usually the valve is spring controlled.
T	F	If the water level in the boiler falls below a predetermined level, the boiler shell and tubes will be overheated.
T	F	When the temperature of the shell increases above a particular level, the fusible plug, which is mounted over the grate, melts and forms an opening.
T	F	Due to heating, impurities like mud, sand and, salt are deposited at the bottom of the boiler.
T	F	If the impurities are not removed, they are accumulated at the bottom of the boiler and increase its capacity and heat transfer rates.

UNIT 7

Evaporator Scaling

During the evaporation process, the solubility of most of the dissolved minerals, which remain in the evaporator brine, is exceeded and precipitation occurs, forming scale deposits on heat transfer surfaces. The three most common scales formed in an evaporator are calcium sulfate, calcium carbonate, and magnesium hydroxide. These are efficient heat transfer barriers. Reduced heat transfer results in reduced water production. Eventually, distillers must be shut down and cleaned to remove the insulating scale.

Mechanical Control

Foaming and carryover from evaporators can be minimized by proper management of the water level and salinity (brine) control.

• Improper water level control is often due to the malfunction of the automatic controls and alarms. Automatic equipment and alarms should be maintained in good operating condition.

• Salinity control is an important factor in the prevention of scale deposits as well as carryover. Salinity management refers to the continuous removal of concentrated brine from the evaporator in order to control the amount of dissolved solids buildup. Normally the brine concentration should be maintained at 1.5 (1.5/32nds) concentrations, although some vapor compression units operate at 2.0 (2.0/32nds) concentrations or more.

Chemical Treatment

The problems of scale formation and foaming can be minimized by the addition of chemical treatments containing polymeric scale inhibitors and antifoams. The polymer molecules attach themselves to the scale-forming minerals to disrupt the densely packed crystalline structure. This prevents hard scale from building up on the heat transfer surfaces. Instead, nonadherent, suspended crystals are formed which will easily flow overboard with the brine discharge.

Polymer treatments can remove existing scale from heat transfer surfaces by the same action. If treatment is used, water production can be maintained, and acid cleaning to remove scale can be minimized. Modern formulations include an antifoam ingredient which reduces the surface tension of the water and allows vapor to escape without the formation of foam. This helps to maintain water quality.

EXERCISES

Exercise 1.Read these word combinations and remember their translation.

On the common premise, used onboard for whatever purpose, primarily, to be safely used for steam production, the salts and other contaminants, an evaporator or distiller, purifying the water, to contain only trace levels of minerals, dissolved gases, formed by decaying organic matter, deaeration, the efficient maintenance of all steam generating and cooling system equipment, the desalination of seawater, the most widely used method, routine program, relative simplicity, cost effectiveness, hardness constituents, solutions of different dissolved solids concentration, a semipermeable membrane, the more dilute solution, in the reverse direction, the dilute side, high quality distillate, over a series of coils or tubes, a mist eliminator, the solubility of the dissolved minerals, heat transfer surfaces, the surface tension of the water, the decay of organic materials, the malfunction of the automatic controls and alarms, polymeric scale inhibitors and antifoams, the densely packed crystalline structure, suspended crystals.