月: 2023年11月

What Is a Boiler Economizer?

A boiler economizer is a heat exchanger that recovers heat from combustion gases in boilers, which use combustion heat to generate steam. Typically used in steam boilers that combust fuels like oil, coal, or gas, these economizers heat water to generate steam.

Also known as “coal economizers,” these devices are named for their ability to conserve coal in coal-fired steam boilers.

Uses of Boiler Economizers

Boiler economizers are primarily used to preheat the feed water to steam generators. Their advantages include reducing heat loss in combustion gas, thereby improving boiler efficiency. For instance, a 20°C recovery in combustion gas temperature can enhance boiler efficiency by approximately 1%. They also help in decomposing gases in feed water, reducing thermal stress in drum-type boilers.

Apart from boilers, economizers also find use in recovering heat from diesel engine exhaust gases to generate steam, beneficial for diesel generators and marine engines.

Boiler Economizer Principle

A steam boiler comprises several heat exchangers, including the economizer, which recovers heat from combustion gases. The key components include:

1. Superheater:

Generates high-temperature, high-pressure steam from recovered heat, used in power plants to drive turbines for electricity generation. –

2. Reheater:

Reheats steam post-turbine rotation for use in medium or low-pressure turbines.

3. Economizer:

Recovers additional heat energy from combustion gas to preheat water supplied to the superheater, thereby boosting boiler efficiency.

Types of Boiler Economizers

1. Classification by Combustion Gas and Feed Water Flow Direction:

Includes parallel flow, counter-current flow, and mixed-flow types, with counter-current offering the highest efficiency.

2. Classification by Degree of Heating:

Divided into non-evaporative (common in economizers) and evaporative types. Non-evaporative economizers keep the feed water temperature below saturation at the outlet, while evaporative types partially heat water to evaporation.

Structure of Boiler Economizer

Boiler economizers generally comprise steel tubes, either bare or finned, arranged for continuous water flow from inlet to outlet. These tubes are often U-shaped for efficient heat transfer.

Other Information on Boiler Economizers

Standards: Relevant standards include JIS B0126 (Glossary of terms for thermal power plants-Boilers and auxiliary equipment) and JIS B8201 (Steel boilers for land use-Stationary steel boilers-Construction).

What Is a Fuel Cooler?

A fuel cooler is a device designed to cool fuel in engines. By cooling the fuel, which can become hot during engine operation, it helps prevent damage to engine components and maintains fuel temperature within an optimal range. Additionally, cooling fuel increases its density, improving combustion efficiency and, consequently, the engine’s propulsion and fuel economy.

Applications of Fuel Coolers

1. Aircraft:

In aircraft engines, high-temperature combustion gases can degrade fuel. As a result, fuel coolers are employed to manage internal temperatures and extend engine life.

2. Rockets:

Rocket engines operate at extremely high temperatures during the combustion of fuel and oxidizers. Fuel coolers help regulate this process, stabilizing propulsion and maximizing thrust.

3. Gas Turbines:

Used in power plants, gas turbines benefit from fuel coolers for efficient fuel combustion and power generation.

4. Submarines:

Operating under high-pressure, high-temperature conditions, submarines utilize fuel coolers to maintain diesel fuel at optimal temperatures for prolonged underwater navigation.

Principle of Fuel Coolers

Fuel coolers work by allowing hot fuel to flow through pipes or tubes, while a cooling medium like water circulates around the fuel, absorbing heat. This heat exchange cools the fuel while heating the medium, which is then discharged and often recirculated. The cooled fuel is then ready for the combustion process.

How to Select a Fuel Cooler

1. Capacity:

Selection should be based on the fuel’s flow rate and temperature differential, ensuring the cooler is adequately sized.

2. Fuel Type:

Cooler materials and designs should be compatible with the specific fuel used, such as jet or diesel fuel.

3. Refrigerant Type:

The choice of refrigerant, including water, cooling oil, fluorocarbons, or liquid nitrogen, depends on its properties and the required cooling capacity. Fluorocarbons are often compressed for enhanced cooling, while liquid nitrogen is released into the atmosphere post-use.

What Is An Industrial Water Pump?

Industrial water pumps are used in factories and production facilities for various purposes. These pumps are distinct from those used in building equipment or water and sewage systems due to their ability to handle various fluids, often mixed with different substances.

Applications of Industrial Water Pumps

1. Production Use:

Employed for cooling water supply and drainage in various industries like machine shops, chemical plants, and agricultural irrigation. Also used in semiconductor factories for cooling and clean room applications.

2. Power Generation:

Essential for supplying high-pressure water to boilers in power plants and for cooling equipment, including in cooling towers.

3. Air Conditioning and Fire Extinguishing:

Utilized in air conditioning systems in factory buildings and for water supply and drainage in fire extinguishing equipment.

Principles of Industrial Water Pumps

1. Positive Displacement Pumps:

Change volume to intake and discharge water under pressure, including reciprocating and rotary types. Examples are piston pumps, plunger pumps, and gear pumps.

2. Non-Displacement Pumps:

Also known as turbo-type pumps, they use impellers to convert velocity energy into pressure for water discharge. Types include centrifugal, semi-axial, and axial pumps.

3. Special Type Pumps:

Designed for specific applications such as submersible pumps, which operate underwater and use various pump types like cascade and volute.

Other Information on Industrial Water Pumps

For Cleaning: High-pressure washing pumps with warm water, usually operating at 20~30 MPa. For Residual Water: Submersible pumps capable of draining water down to 1mm, suitable for draining out hollows. For Sewage Drainage: Submersible pumps designed for sewage and wastewater, made of materials like stainless steel and resin. For Chemical Use: Submersible pumps for chemical sewage, constructed from stainless steel and titanium.

What Is An Electrostatic Generator?

An electrostatic generator is a type of generator that generates static electricity or high-voltage, low-current electricity.

It is sometimes referred to as an electrostatic generator or electromotive generator. In most cases, products that generate static electricity are sold under product names such as electrostatic high-voltage generators and electrostatic guns.

Uses of Electrostatic Generators

Electrostatic generators and electrostatic generators can be used to observe discharge phenomena and to check the conductivity of materials by generating static electricity. For this reason, these devices are used in experiments in science education and nuclear physics.

They can also generate high voltages, and their industrial applications include power supplies for X-ray tubes, medical care, and food sterilization. Today, however, semiconductor circuits are used more often than electrostatic generators as practical high-voltage power sources.

Electrostatic spray guns and various types of electrified guns used in electrostatic painting utilize the principle of electrostatic generation. Electrostatic painting is an industrial technique in which paint particles are charged with static electricity and evenly adhere to the coated object. Electrostatic testers can also be considered a variant of electrostatic generators as a device that artificially generates static electricity. Specific examples of the use of static guns are as follows

• Attracting non-metals such as paper, foil, and plastic sheets to metals (plates)
• Charging performance testing (paper, plastic sheets, fibers, etc.)
• Adsorption of plastic and ceramic powders
• Electrostatic application of fine powders
• Power source for electret production
• Power source for electrospinning equipment for nanofiber production

Principle of Electrostatic Generator

Electrostatic generators use friction between objects to generate static electricity. A typical example of an electrostatic generator that uses frictional charging is the Van de Graaff generator. The Van de Graaff generator is a device that generates an electrical charge by rotating a belt over two rollers, which carries the charge and charges a hollow metal sphere with an electrical charge. Vandegraaff generators generate a high-voltage DC voltage, but the current generated is low.

Other electrostatic generators include electro-force machines, which spin glass disks and electrify them by friction, and Wimshurst induction electromotive generators, which use two disks and several metal fan strips on the disks to electrify them. The Wimshurst-type induction electromotive generator is an electromotive generator that uses electrostatic induction rather than frictional electromotive force.

EHD generators are generators that use a charged fluid to carry an electrical charge.

Types of Static Generators

As mentioned above, electrostatic generators that use frictional charging include Van de Graaff generators and electro-force machines. In addition, the Wimshurst induction electromotive generator is an electromotive generator that uses electrostatic induction. In addition, a type of device called a charging gun or discharge gun is a device that generates static electricity by simply pulling a trigger on an object, as the electrode at the tip of the gun is electrically charged by simply pulling the trigger.

By application, there are those for demonstration experiments used for educational purposes, and those used for industrial purposes such as electrostatic painting. The size of the device and output voltage vary greatly depending on the device. If used, it is necessary to select the right one for the application.

Other Information on Electrostatic Generators

Principle of Electrostatic Generation

Electric charges exist in the atoms that make up matter. Among the components of an atom, those with a positive charge are the nucleus and those with a negative charge are the electrons.

When two objects rub against each other due to friction, electrons are transferred from one to the other, resulting in the accumulation of a negative charge on one object and a positive charge on the other. This state of electrical bias is called electrification and is referred to as the “generation of static electricity.

What Is a Constant-Current Power Supply?

A constant-current power supply is a circuit that controls and delivers a steady output current. It is sometimes referred to as a constant-current source or a constant-current stabilized power supply. While DC constant-current power supplies are more common, AC versions are also available.

Uses of Constant Current Supplies

1. LEDs:

Used for powering LEDs, as their brightness is determined by the current. A stable current supply prevents brightness fluctuations and flickering.

2. Rechargeable Battery Charging:

Essential for charging rechargeable batteries, like lithium-ion batteries in smartphones, where a constant current is needed regardless of voltage variations.

3. Power Supplies for Sensor Signals:

Employed in powering sensor signals, converting resistivity changes into voltage changes for CPU interpretation. Examples include piezoelectric elements and resistance thermometers.

Principle of Constant Current Supply Devices

According to Kirchhoff’s law, in a circuit with a power supply of electromotive force E and internal resistance r connected to a variable resistor R, the current value I is given by I = E / (R+r). A constant-current supply achieves a stable current (I ≈ E / r) by having an internal resistance r significantly larger than R.

Additionally, voltage and current sources are equivalently convertible. An ideal voltage source with electromotive force E and internal resistance r in series can be equivalent to a current source with the same internal resistance r in parallel.

Types of Constant Current Supplies

Stabilized DC Power Supply:

Includes regulated DC power supplies with the ability to switch between constant voltage and constant current modes. Control methods vary between series regulators and switching power supplies, the latter being more efficient but generating more noise.

Others:

There are also output-isolated constant-current supplies, AC constant-current units, and AC-regulated power supplies, each suited for specific applications.