Construction of LP and HP Heater

Construction of LP and HP Heater should be performed as procedure and design. The selection of LP heater materials and method of construction remains with the design although the use of shells with a minimum number of joints, welded tube plate to channel joint, and welded feedwater pipe attachments are preferred. The corrosion resistance of the proposed tube material selection should make due allowance for the oxygen content that may prevail in the LP feedwater, particularly at low load and during start up.

The LP and HP heater should be of the conventional U tube and shell type for which the selection of tube and tube plate material, and their method of attachment should be described. The proposed selection of materials for the tubes, tube plate or header should be in accordance with Code and Standards, provided together with full details of the method of tube attachment.

This selection should be based on service experience with waterside velocities not exceeding previous good service experience. All tubes should be produced from single lengths of tubes and be hydraulically tested to the requirements of ASME standard or equivalent standard.

The bled steam inlets of both the LP and HP heaters should incorporate provisions to prevent erosion, impingement and vibration damage of the tubes by either steam or water. All bled steam and drain inlets should incorporate arrangements to prevent direct impingement of fluid against the tube nest.

The method of attaining access into the channel or headers should be described, to permit inspection and plugging of all tube ends. With divided channel designs, details of the construction and attachment of the dividing wall or chamber to the channel should be provided.

For both the LP and HP surface type heaters, only designs with proven service reliability whilst of similar size and rating should be proposed and reference listings should be made available during the contract.

READ MORE - Construction of LP and HP Heater

Design Surface Type LP and HP Heater

Design surface Type LP and HP heater should be described with reference to sectional arrangement drawings. These drawings should be representative in terms of heater disposition, channel division plate details, baffling arrangements, the location of any de-superheating and drain cooling sections arid their shrouding, etc.

The design surface Type LP and HP heater must be performed by manufacturer which has relevant and successful experience with the type of heaters being proposed. Heaters are required to last the life of the station with minimal maintenance. The design surface Type LP and HP heater should therefore describe the design features incorporated into the design of the feed water heaters to minimize or eliminate problems of:

• Tube vibration and corrosion
• Tube fretting at baffles and shroud plates
• Tube erosion and fretting adjacent to bled steam and flash drain inlets
• Distortion and cracking at the tube plate
• Stagnant pockets of non-condensable gases.
• Division plate cracking and damage

READ MORE - Design Surface Type LP and HP Heater

Hot Water Heating Boiler

Hot water heating boiler is one of boiler types which is classified based on use. This boiler is utilized in the heating system to heat water at certain temperature and the hot water is distributed to the expected location. Hot water heating boiler in a house will help convenience especially in the winter season. The heating process is made of piping, pump, and boiler.

Hot water heating boiler based on its capability to heat water at certain temperature can be categorized into three types:

1. Low temperature hot water heating boiler - this boiler can operates and heat water until temperature 95^o C.
2. Medium temperature hot water heating boiler - this type of boiler can perform and increase temperature of water range 95^o - 120^o C
3. High temperature hot water heating boiler - this boiler type is used to heat water until temperature above 120^o C.

For medium temperature type and high temperature type, because of its temperature, water lead to change its phase to be steam. It must be prevented by applying pressure to the boiler system. There are several methods to generate pressurized hot water heating boiler as follow:

1. Nitrogen pressurization method – this method uses nitrogen that is compressed in a vessel tank and distributed together with water as shown in Figure 1 below.

Figure 1: Nitrogen Pressurization Method 

2. Air pressurization method – this method is same with nitrogen pressurization method, the difference is the medium, in this method uses air as the medium.

3. Diaphragm air pressurization method – this method uses compressed air as above method but it uses diaphragm of neoprene as shown in Figure 2 below among water and air.

Figure 2: Diaphragm Air Pressurization Method

4. Pressure pump method – this method uses pump to produce pressure in the hot water heating boiler system as shown in Figure 3 below.

Figure 3: Pressure Pump Method of  Hot Water Heating Boiler
(Source: Book-The Boiler Operator Handbook-NIFES-Graham & Trotman)

READ MORE - Hot Water Heating Boiler

Types of Solar Water Heating Systems

Solar water heating system is useful for people to supply warm water, moreover in cold condition. There are some types of solar water heating systems such as:

1. Type solar water heating thermo siphon

Type water heating thermo siphon is one of types of solar water heating systems in which it is the simplest conversion system of solar energy and most effective. As shown in Figure 1, this system consists only of water storage tank that is placed higher at distance at least 25 cm above the top of row solar collectors. There are differences of density between fluid in column AB and fluid in column A'B '. If the fluid in solar collector (column AB) is heated by sun, then its density will decrease.

If difference of density between AB and A'B 'have been high enough to overcome the friction of system, then clockwise circulation will occurs, warm water from solar collector is distributed to water storage tank and blank space in solar collector will be replaced by cooler water from bottom of tank. The circulation continues until entire system achieves uniform temperature.

Figure 1: Type Solar Water Heating Thermo Siphon

2. Type forced circulation of water glycol systems

If protection against freezing is needed, then solution of antifreeze can be circulated through solar collectors, absorbed heat will be transferred to water in storage tank by using heat exchanger (Figure 2). If the frozen solution is toxic, it would require heat exchanger that is made with double walls.

Figure 2: Type Forced Circulation of Water Glycol Systems

3. Type drain back System

One of types of solar water heating systems is drain back system which uses compressed air to restore water that circulates through solar collector to storage tank when the insulation is not enough. Compressed air can be supplied by a compressor to spray grain water. The circulating water is usual drinking water; in this case heat exchanger is not used. Water is supplied from preheated tank to hot water heater based on requirement. Type drain back system is shown in Figure 3 in which soft water is circulated through solar collector to prevent deposition on the tube and ventilation hole is made on polypropylene tank.

Figure 3: Type Drain Back System

4. Type flat plate water heaters

Type flat plate solar water heater is one of types of solar water heating systems that consist of a sheet of thermal conductive material which is called absorber plates that is connected to pipes to distribute hot water. Solar radiation is transmitted through transparent cover and converted into heat at absorber plate. The bottom and sides are isolated as shown in Figure 4.

Figure 4: Type Flat Plate Water Heater

READ MORE - Types of Solar Water Heating Systems

Solar Collector Components

In general, solar collector serves as an absorber of solar radiation energy which is then converted into thermal energy in the collector pipes. Solar collector consists of some components as follow:

a)      Transparent Cover

-         Transparent cover is one of solar collector components that serves to distribute the sunlight that falls to it, reduce convection and radiation losses to surrounding air and protect solar collector against dust and rain.

-         Transparent cover has properties as follow: translucent, high transmissibility, absorptivity and low reflexivity to short-wave radiation but high in reflect long wave radiation and high temperature resistant.

-         Glass can be selected as the material because it has properties of transmissibility as 0.8.

b)      Fin Collector

-         Fin collector is one of solar collector components that serves to enlarge the area of solar radiation absorber on the solar collector.

-         The properties of fin collector must fulfill following requirements: high conductivity and high absorptivity, and high temperature resistant.

-         Copper plate can be selected as the material because it has value of conductivity as 401 W/mK, and emissivity as 0.03.

c)      Pipe Collector

-          Pipe collector is one of solar collector components that serves as medium channel of heat transfer to water.

-          The properties of pipe collector can be equal with fin collector properties.

d)     House Collector

-          House collector is one of solar collector components that serves as the holder of all the components above as well as prevent the entry of water and dust.

-          The properties must lightweight and corrosion resistant.

-          Aluminum can be selected as the material of house collector because it apply the requirement properties above.

e)      Isolation

-          Pipe collector is one of solar collector components that serves to reduce heat losses to the environment through bottom and sides of solar collector.

-          The properties must have low conductivity.

-          Fiber can be selected  as the material of isolation.

READ MORE - Solar Collector Components

Homemade Solar Water Heater Design

Before the production process is carried out, the design process of homemade solar water heater must be performed first. This design process includes design two main components of homemade solar water heater systems that is storage water tank and solar collector.  The design of both components is limited to the following:

-          Volume of hot water tank is adjusted to the needs of user.

-          The available area at installation location. The size of total area of homemade solar water heater should be adjusted.

-          Hot water temperature to be achieved.

The limitation of volume water tank is determined from user demand, it can be assumed as 300 liters. Review of user's house is required to determine dimensions of homemade solar water heater system. Design location of homemade solar water heater systems must meet some requirements to make system work properly. These requirements as follows:

-          Solar collectors must be directly facing the sun, not hindered by such buildings and high trees.

-          Solar collector must be placed on position which gets more available of solar energy all day than other position.

Figure 1: Exmple Location of Homemade Solar Water Heater

The placement of homemade solar water heater should consider the requirements above to get good location and maximum results. Homemade solar water heater design should consider limitation of hot water temperature that must be available. The specified range of hot water temperature must be designed between 50-60 ° C with reason:

-          No harm

-          Can be stored as  water bath

These limitations should be met in design process in order for the system can be installed and functioning properly.

READ MORE - Homemade Solar Water Heater Design

Water Storage Tank in Solar Water Heater System

Water storage tank in solar water heater system is used to store hot water that is heated and collected for use as needed. Water storage tank is made cylindrical horizontal and is equipped with 4 channel pipes with their respective functions as shown in Figure 1.

Figure 1: Water Storage Tank in Solar Water Heater System

The following below are the function of respective channel pipe:

1. Hot water channel pipe from solar collector

It is located on the top left side of water storage tank for water channel that has been heated in the solar collector.

2. Cold water channel pipe

It is located at most bottom right of water storage tank. This pipe serves as cold water line to solar collector and as an inlet for cold water replacement (make-up water).

3. Channel pipe for hot water retrieval/usage

It is located on the upper right side of water storage tank in solar water heater system. This pipe serves to drain the hot water to be used. This channel is placed above the entrance of solar collector drains, to ensure the water level inside water storage tank is always above the water line of solar collector so that the thermosyphon circulation from collector to the tank will always be running.

4. Channel for air expenditure

It is located between inlet cold water and hot water-usage channel. This channel is useful for removing trapped air inside the water storage tank in solar water heater system. When there is air inside the tank, so this air will inhibit the entry of water into tank. Water circulation system will be disrupted and the pressure within system will rise due to air expansion.

READ MORE - Water Storage Tank in Solar Water Heater System

Reverse Osmosis Advantages-Disadvantages

Reverse osmosis system is one of water treatment process. There are 4 steps in reverse osmosis system; pretreatment, giving pressure, membrane separation and stabilization. Reverse osmosis system has some advantages and disadvantages as follow:

1. Advantages of reverse osmosis system

-          Reverse osmosis process is relatively easy.

-          Low installation costs.

-          Without the non-metallic materials in construction.

-          Energy used to treat brackish water between 1-3 kWh per 1 m³ of product water.

-          Can generate big production capacity ratio, between 25,000 to 60,000 liters per day per m².

-          Reverse osmosis technologies can be used to remove contaminants either organic or inorganic.

-          Reverse osmosis process does not has any impact to environment.

2. The following below are disadvantages of reverse osmosis system

-          The membrane is sensitive or not efficient when used excessively.

-          Feed water must be treated first to remove particulates.

-          Operation of reverse osmosis requires materials and tools with high standard of quality.

-          There is a possibility of bacterial growth on the membrane itself

READ MORE - Reverse Osmosis Advantages-Disadvantages

Hot Water Heater Installation

Hot water is provided by using clean water source which is heated in various ways. There are two methods of hot water heater installation. These methods are local hot water heater installation and central hot water heater installation. Both installations are selected based on the use type of building, how to use hot water and equipment cost.

1. Local Hot Water Heater Installation

In this installation method, water heater is placed adjacent to the plumbing equipment which need hot water. Advantages of Local Hot Water Heater Installation are hot water can be rapidly obtained, the heat loss into environment is relatively small, installation and maintenance is easy, and the price is quite low. Therefore, the local installation of hot water heater is widely used in places that require limited hot water.

In the local installation, heating process can be carried out shortly. It means the water is heated in pipe which is mounted on the heater and then directly channeled towards plumbing equipment. Moreover, the saving heating process can be done also. Water is heated in a tank that can store hot water in a little amount.

Generally the local installation of hot water heater takes several minutes to get hot water. Then the technique of mixing steam and water can also be applied. If in a building there is steam source, the steam can be directly mixed with water in tank heater.

2. Central Hot Water Heater Installation

Hot water will be generated in other place, then through distribution pipeline will be channeled towards the entire plumbing equipment. Central Hot Water Heater Installation is generally used in places that require lots of hot water. There are two methods of hot water distribution system, namely: direct central hot water system and circulation central hot water system.

In direct system, water is flowed once only to plumbing equipment. If water is not used for long time and when it will be reused, so the plumbing equipment that is far located will get hot water with lower temperature. While in the circulation system, if water is not used, the water will return to the tank heating. Furthermore the quality of water temperature can be maintained.

READ MORE - Hot Water Heater Installation

Water Heating System

Water heating system is the process to heat water.  Water heating can be performed by two methods; direct water heating system and indirect water heating system. The following below is differences of direct water heating and indirect water heating:

1. Direct water heating system

One of method to heat water directly is use water heating boiler. Water will be heated by boiler combustion chamber wall and then to be distributed to required point. In addition to the water is distributed directly from boiler, hot water can be also accommodated in the storage tank.

If we use water heating boiler, there are some disadvantages wen can experience such as:

1.      When hot water out from water heating boiler, cold water will enter to replace the lost water mass. This condition will cause the temperature change continuously on the walls of water heating boiler so that it can lead to stress changes in the walls of boiler, and finally will shorten the life of boiler.

2.      If quality of feed water is not good, it will produce crust on the wall boiler.

2. Indirect water heating system

Water can be heated indirectly by use heat exchanger. Heat exchanger is used as a medium to produce hot water. The efficiency of this system is lower, but the disadvantages of direct water heating system can be overcome.

READ MORE - Water Heating System