Heat exchangers power plant

Types of heat exchangers power plants

A heat exchanger is an engineering device that transforms thermal energy between two or more fluids. There are several types of industrial heat exchangers used in power plants:

• Tubular heat exchangers: commonly used tube bundle heat exchangers. The heat exchanger comprises a tube bundle, an outer shell, inlet/outlet header boxes, and other accessories. The tubular heat exchanger's working principle is to build a thermal transmission path between the fluid in the tube and the fluid outside the tube through the tube wall. This allows heat transfer (heating or cooling) between two different fluids. Tubular heat exchangers have the following advantages. They are suitable for processing a large number of products. Tubular heat exchangers typically have a high heat transfer area, which can handle a large volume of fluids. Tubular heat exchangers also have strong adaptability. By changing the tube quantity and layout, the tubular heat exchangers can be used for countercurrent, concurrent, or mixed flow.
• Tubular heat exchangers: is a compact thermal exchange device. It comprises numerous small diameter tubes. The tube bundles are assembled into a block, which is then enclosed inside a shell. Heat transfer occurs from the fluid circulating inside the tubes to that in the shell side (or vice versa). The amount of heat transferred is dependent on the temperature difference between the fluids and the surface area of the tubes.
• Plate heat exchangers: consist of many plates with a corrugated surface. The plates are mounted between a top frame and a bottom frame. The seal in the corrugated grooves, which is then applied with two sealing plates that seal the outside of the corrugation, creates channels through which fluids pass. The fluids then transfer heat via the plates. Plate heat exchangers are distinguished from other heat exchangers by their corrugated plates.
• The air cooler heat exchanger: also known as the finned tube heat exchanger, consists of many tubes assembled into a bundle, with fins attached to each tube. By coupling the cool ambient air to the hot fluid flowing inside the tubes, the heat is exchanged between them. Air cooler heat exchangers are efficient and environmentally friendly.
• The evaporator heat exchanger: is the first component of the refrigerator's working cycle; it occurs between the surrounding atmosphere and the refrigerant. The heat is absorbed from the surrounding environment by the refrigerant in the evaporator, changing the state of the refrigerant from liquid to gas. The process cools the environment around the evaporator.

Specifications and maintenance of heat exchangers power plant

Specifications:

• Size and area: Industrial heat exchangers are bigger than those used for normal purposes. So, their sizes and areas are more than those tiny ones.
• Materials: The materials for industrial heat exchangers power plants are usually tough metal alloys like carbon steel, stainless steel, titanium, etc. These materials are long-lasting and can withstand high pressure and temperature. Also, they resist corrosion well and allow for stable and safe operations throughout their service lives.
• Flow Pattern: The common flow patterns of industrial heat exchangers power plant are counterflow, co-current, cross-flow, etc. The choice of flow pattern depends on the functions and needs for efficiency of the heat exchanger.
• Efficiency: The thermal efficiency of industrial heat exchangers power plants is usually high. Their heat transfer coefficients are also very high. For instance, shell and tube heat exchangers have an overall heat transfer coefficient of around 1000-5000 W/(m2·K) or even higher. That shows that they can utilize energy resources, effectively reducing production costs for businesses.

Maintenance:

• Cleaning: Regularly clean the exterior surfaces and heat-conducting elements of the heat exchanger to prevent scaling, deposits, and dirt. Use appropriate cleaning agents and equipment.
• Leak inspection: Periodically inspect the heat exchanger for leaks. Check the seals, joints, and connections to ensure there are no leaks, and make timely repairs if any are found.
• Operations: Always carefully obey the operation instructions provided by manufacturers during the use of heat exchangers. Do not overload and pursue higher efficiency at the cost of equipment's safety.
• Lubrication: If some components need lubrication for themselves to function optimally and for longer, apply suitable lubricating agents for them as per the requirements put forward by manufacturers.
• In brief, maintaining industrial heat exchangers in power plants properly is important if they are to work well over decades and during harsh conditions. Only by doing so can these critical pieces of equipment continue allowing plants to produce energy efficiently, economically, and safely.

Scenarios of heat exchangers in power plants

The main usage of heat exchangers in a power plant is to facilitate the transfer of heat between two fluids. Exchangers' designs and uses vary according to the type of power plant they are in.

• Cooling water systems

  Freshwater is usually heated when it passes through the condenser of a thermal power plant. A heat exchanger is used to transfer the heat from the condenser to the cooling water. The cooling water then flows back to the river or lake. In this case, the heat exchanger prevents the cooling water from getting too hot.

• Superheaters and economizers

  In a steam power plant, heat exchangers are used to heat the steam flowing to the turbine. They are located in the boiler and are called superheaters. Superheaters can raise the temperature and pressure of steam by a few hundred degrees. An economizer is a different type of heat exchanger found in a power plant. It is usually found in the boiler like a superheater. Its work is to use the heat from flue gas to heat the water coming into the boiler.

• Air-to-air heat exchangers

  At some points in a power plant, it may be necessary to separate the two gases. This could be to avoid contamination or for safety reasons. An example is heat exchangers between flue gas and combustion air. In this case, heat is transferred from flue gas to combustion air. Heat exchangers can be used to recover heat from flue gas and use it to heat incoming air used for combustion.

• Gas turbine power plants

  In a gas turbine power plant, heat exchangers can be used in a combined cycle. In a combined cycle, power is first generated using a gas turbine. Some of the heat generated in the gas turbine is transferred to a heat exchanger. The heat exchanger is then used to generate steam for power generation using a steam turbine.

How to Choose Heat Exchangers for Power Plants

Heat exchangers play a crucial role in power generation. The following tips may help buyers identify the heat exchangers suitable for their power plants:

• Assess Media Properties

  Consider the properties of both the hot and cold fluids. Look out for the pressure and temperature ranges, flow rates, and chemical properties (corrosive, toxic, or hazardous) of the fluids. Also, consider if the fluids are gases, liquids, or slurries. Then, choose a heat exchanger design that can handle their specific requirements.

• Consider the Space Constraints

  Determine the physical dimensions (length, width, and height) of the heat exchanger that will fit in the power plant. Also, consider the layout of the plant. Then, choose a compact heat exchanger design, such as plate or shell-and-tube models, if there are space constraints.

• Evaluate Maintenance Requirements

  Choose a heat exchanger that has low maintenance requirements if the power plant location makes it difficult to carry out regular maintenance. Consider reliable designs like shell-and-tube units. Ensure the selected heat exchanger also has accessible components for easy service and checks.

• Account for Budget Constraints

  When deciding on a heat exchanger for a power plant, the budget is an important consideration. Set a budget for the acquisition and installation of the heat exchanger. Then, prioritize spending on units that will enhance the performance of the power plant. Consider the long-term costs (energy and maintenance expenses) of the heat exchanger and not just the upfront purchase price.

Q & A

Q1. What are the trends in the heat exchanger market?

A1. According to market reports, the global heat exchanger market size was valued at $25.92 billion in 2021 and is projected to reach $39.34 billion by 2031, registering a CAGR of 4.5% from 2022 to 2031. Some of the key trends include compact heat exchanger power plants, smart heat exchangers, and sustainable heat exchangers.

Q2. What are the differences between the condensers and heaters in power plants heat exchangers?

A2. The function of a condenser is to remove heat from a vapor and change it into a liquid. It also releases heat to the cooling medium, usually water or air. The heater, on the other hand, receives heat from a hot fluid that is usually from a boiler. It passes the heat to another fluid that is usually water that is used for heating.

Q3. What is the difference between plate and tube heat exchangers?

A3. Plate heat exchangers are mainly used in plumbing applications while tube heat exchangers are mainly used in industrial applications. Tubular heat exchangers also take up more space compared to compact plate heat exchangers. Heat exchangers can be classified into counterflow, crossflow, and shell tube which are mainly used in power plant industries.