Surge l Surge In centrifugal Compressor l

Girish Shinde

28 Feb 202313:26

Summary

TLDRThe script discusses the concept of surging in centrifugal compressors, a critical phenomenon in refrigeration systems. It explains the mechanism behind surging, its impact on compressor efficiency, and how it can lead to increased wear, noise, and vibration. The speaker also explores the reasons for surging, such as issues with the compressor's operation or blockages in the system. Finally, the script suggests methods to control surging, emphasizing the importance of maintaining optimal system performance and preventing potential damage to the compressor.

Takeaways

😀 The topic of the video script is about 'surge' in centrifugal compressors and its effects on the system.
🔧 Surge is a phenomenon where the flow of the compressor is reversed, causing the discharge gas to move towards the suction side.
🔄 The cause of surge includes a reduction in the compressor's power, leading to a decrease in the kinetic energy provided to the refrigerant.
🚫 Surge can be detrimental to the compressor's performance and can lead to increased wear and tear, noise, and vibration.
🛠️ The script explains the mechanism of surge, including how a decrease in the mass flow rate of the refrigerant or changes in the compressor's speed can trigger surge conditions.
🔍 The importance of maintaining the correct balance between the mass of the refrigerant, its speed, and the kinetic energy provided by the impeller is highlighted to prevent surge.
📉 Surge can result in a decrease in the compressor's efficiency and can cause increased stress on the compressor's components, potentially leading to mechanical failure.
🛑 The script suggests methods to control surge, such as adjusting the flow rate of the refrigerant and managing the pressure build-up within the system.
🔧 Surge can be caused by blockages in the inlet filter, issues with the diffuser, or problems with the compressor's internal components.
🔄 Understanding the compressor's working principle is crucial for identifying the causes of surge and implementing effective control measures.
🛠️ The video script aims to provide a comprehensive understanding of surge, its effects on the compressor, and the strategies for controlling it to ensure the system's optimal performance.

Q & A

What is the main topic of the video script?
-The main topic of the video script is the concept of surge in centrifugal compressors, its causes, effects on the compressor, and how to control it.
What is surge and how does it relate to the operation of a compressor?
-Surge is a phenomenon where the flow of the refrigerant in a compressor is reversed due to a decrease in kinetic energy or a reduction in the flow rate, causing the refrigerant to flow back towards the impeller instead of moving forward.
What are the consequences of surge on the compressor's performance?
-Surge can lead to a decrease in compressor efficiency, increased wear and tear on the compressor parts, noise, and potential damage to the compressor due to the reversed flow and uneven stress on the impeller and thrust bearings.
How does the direction of the wheel in a centrifugal compressor change during surge?
-During surge, the direction of the wheel changes as the refrigerant flow is reversed, causing the wheel to rotate in the opposite direction, which can lead to increased vibration and noise.
What factors affect the pressure build-up in a compressor?
-The pressure build-up in a compressor is affected by the mass of the refrigerant (quantity), the speed of the impeller (RPM), and the kinetic energy provided by the blades to the refrigerant.
How can a blockage in the compressor's inlet or filter cause surge?
-A blockage in the inlet or filter can reduce the quantity of refrigerant entering the compressor, leading to a decrease in pressure build-up and potentially causing surge if the pressure does not reach the required levels for normal operation.
What is the role of the compressor's speed in preventing surge?
-The speed of the compressor, measured in RPM, is crucial in maintaining the kinetic energy needed to prevent the reversal of the refrigerant flow, thus preventing surge.
How can changes in the refrigerant's flow rate and the compressor's speed affect the discharge pressure?
-If the flow rate of the refrigerant is reduced or the compressor's speed is decreased, the discharge pressure can also decrease, potentially leading to surge if it falls below the necessary pressure for proper operation.
What is the impact of high temperature in the condenser on the compressor's operation?
-High temperature in the condenser can cause the pressure of the refrigerant to increase, which can affect the pressure build-up in the compressor and potentially lead to surge if the pressure is not managed properly.
What methods can be used to control surge in a compressor?
-Surge can be controlled by monitoring and adjusting the flow rate of the refrigerant, the speed of the compressor, and by using devices such as surge arrestors or valves that can divert the flow and prevent the reversal of the refrigerant.
How does surge affect the overall life and performance of a compressor?
-Surge can cause increased wear on the compressor's components, leading to a reduction in the compressor's lifespan. It also results in decreased performance due to the inefficiency caused by the reversed flow of the refrigerant.

Outlines

00:00

🔧 Introduction to Compressor Operation and Search Mechanism

The script begins with a warm welcome to the audience at the GREE Academy and introduces the topic of the session, which is the 'search' in centrifugal compressors. It explains the concept of 'search', its causes, effects on the compressor, and how it can be controlled. The speaker uses an analogy of a car moving in a certain direction with engine power to illustrate the point at which the car would stop if the engine's power decreases. The script then delves into the workings of a normal compressor, explaining the discharge and intake process, and how a decrease in power leads to a reversal of the direction, which is referred to as 'searching'. The mechanism behind this phenomenon and its control methods are also discussed.

05:02

🔧 Impact of Search on Compressor Performance and Control Methods

This paragraph discusses the effects of 'search' on the performance of a compressor, highlighting how a reduction in kinetic energy or refrigerant flow can lead to a reversal of flow, causing the compressor to operate in the wrong direction, which is termed as 'searching'. It explains the importance of the refrigerant quantity and the speed of the impeller in building up the discharge pressure. The script provides examples to illustrate how changes in the compressor's settings, such as reducing the refrigerant flow rate or the impeller speed, can affect the discharge pressure and lead to searching. It also touches upon the potential causes of searching, such as blockages, issues with the diffusion, or problems with the compressor's ability to pump gas effectively.

10:04

🔧 Consequences and Control Techniques for Compressor Searching

The final paragraph elaborates on the consequences of searching on the compressor, such as reduced efficiency, increased wear and tear, noise, and potential damage to the compressor's components due to reverse flow and uneven stress. It also discusses various methods to control searching, including the use of a separate line to manage the flow of refrigerant and prevent it from entering the impeller in the wrong direction. The script suggests monitoring the compressor's operation to open a valve that equalizes the pressure and stops the reverse flow of refrigerant, thus controlling the searching effect. The importance of maintaining the correct pressure and flow to prevent damage and ensure the compressor's longevity is emphasized.

Mindmap

Keywords

💡Surge

In the context of the video, 'surge' refers to the reverse flow of refrigerant that occurs when the compressor's power decreases or fails to maintain the necessary pressure. It is a critical concept as it directly impacts the efficiency and operation of the compressor. The script describes surge as an effect that happens when the discharge gas from the compressor enters the suction side, leading to a change in the direction of the wheel, which is not the normal operation.

💡Compressor

A 'compressor' is a device that increases the pressure of a gas by reducing its volume. In the video, it is central to the discussion as it is the heart of the refrigeration cycle. The script explains how the compressor works in a centrifugal system, compressing the refrigerant and building up pressure, which is essential for the cooling process.

💡Refrigerant

The 'refrigerant' is the substance that circulates through the system, absorbing heat in the evaporator and releasing it in the condenser. The script mentions the importance of the refrigerant's flow rate and its quantity in the system, which are crucial for maintaining the compressor's performance and avoiding issues like surge.

💡Evaporator

An 'evaporator' is a part of the refrigeration system where the refrigerant evaporates, absorbing heat from the space to be cooled. The script uses the evaporator as an example to illustrate the normal operation of the compressor and how a decrease in the evaporator's performance can lead to a surge condition.

💡Condenser

A 'condenser' is where the refrigerant gas releases heat and changes back to a liquid state. The script explains the role of the condenser in the refrigeration cycle and how issues in the condenser, such as high temperature, can affect the pressure of the refrigerant and lead to compressor surge.

💡Suction

In the context of the video, 'suction' refers to the process of drawing the refrigerant into the compressor. The script describes how a decrease in the power of the engine can affect the suction process, leading to a potential surge if the compressor is not able to maintain the necessary pressure.

💡Discharge

'Discharge' is the process of the compressor expelling the compressed refrigerant gas into the condenser. The script discusses how the pressure at the discharge side of the compressor is crucial for the proper functioning of the system and how a surge can occur if the pressure is not high enough.

💡Impeller

An 'impeller' is a part of the compressor that imparts kinetic energy to the refrigerant, increasing its velocity and pressure. The script explains how the impeller's speed and the energy it provides to the refrigerant are key factors in the compressor's ability to build up pressure and avoid surge.

💡Pressure Build-Up

The term 'pressure build-up' refers to the increase in pressure within the system as the refrigerant is compressed. The script emphasizes the importance of pressure build-up for the efficient operation of the compressor and how factors such as the mass of the refrigerant and the impeller's speed affect it.

💡RPM (Revolutions Per Minute)

RPM is a measure of the rotational speed of the compressor's impeller. The script mentions RPM as a critical parameter that influences the energy provided to the refrigerant and, consequently, the pressure build-up and the prevention of surge.

💡Inlet Filter

An 'inlet filter' is a component that prevents contaminants from entering the compressor along with the refrigerant. The script suggests that a blockage in the inlet filter can reduce the flow of refrigerant, affecting the pressure build-up and potentially causing a surge.

Highlights

Introduction to centrifugal compressor and its surge phenomenon.

Explanation of normal operation of a centrifugal compressor.

Surge occurs when the compressor power decreases, causing reverse flow of refrigerant.

Surge mechanism and its effects on compressor performance.

Importance of refrigerant mass and impeller speed for pressure build-up.

Example demonstrating how changes in refrigerant flow and RPM affect discharge pressure.

Explanation of how kinetic energy converts to pressure energy in the compressor.

Factors affecting compressor surge, including inlet blockages and condenser issues.

Impact of surge on compressor efficiency and system performance.

Surge can cause increased wear and tear on compressor components.

Surge leads to noise and vibration, affecting both the compressor and its surroundings.

Methods to control surge, such as adding a bypass line with a valve between discharge and suction sides.

Effect of surge on compressor bearings and impeller, causing potential damage.

Surge control by balancing pressure between discharge and suction sides.

Summary of reasons for compressor surge and its impact on compressor operation.