Category: Blog

A generator control panel works by displaying key status information and the ability to make adjustments via an interface.

The interface allows a user to monitor, manage, read codes, and regulate a generator. It links to several components, providing real-time feedback on the generator’s operation. This article explores the inner workings of a generator control panel.

How Does a Generator Control Panel Work?

A generator control panel typically works via a user interface that allows for data collection and process control.

User interface

Some control panels have microprocessors that enable autonomous operation, and some allow online access facilitating hands-free management. However, all control panels comes with a user interface that provisions manual generator, known as a a human-machine interface (HMI).

One of the key points of a control panel is data collection.

Data collection and processing

The module receives real-time information from the sensors placed at strategic components and sends this information to the microprocessors. The microprocessors then get to work analyzing and interpreting the data.

They make decisions based on pre-set parameters and adjustments where appropriate. For instance, if the generator overheats due to overspeed, the microprocessor will reduce running speed to ease the load.

Alternatively, the microprocessor might send a distress signal to the operators or shut it down if the issue is beyond its control. For example, if the cause of the overheating is high coolant temperature, it will shut it down.

Communication

The control module is at the epicenter of communication, receiving and instigating communication within the unit and to the operator. A generator control panel’s communication module sends information to the operator or receives instructions from the operation and sends it to the microprocessor to instigate the implementation.

Safety

A generator’s control panel keeps the unit safe by instigating shutdown procedures in an emergency. For instance, if the unit detects catastrophically low oil pressure or voltage drop, it will shut down the generator and set off an alarm or notify the operator.

Transition power

When the primary power source fails, most modern and large generators have an Automatic Transfer Switch (ATS). This automatically starts and transfers the power source to the generator, ensuring an uninterrupted loss of power.

Specifications and Regulations

Specifications

The product specifications contain important information crucial to the smooth operation of the generator. How a generator control panel works can be defined by several key parameters:

• Prime Rated Power: Represents the amount of power the generator is capable of producing when set to “unlimited run time” mode. “Standby rating” refers to the amount of power produced during a short amount of time.
• Engine speed and frequency: The frequency of a generator can be either 50 or 60 Hz. 50 Hz is more common in Europe, while 60 Hz is more prevalent in the US. The generator’s frequency determines its engine speed.
• Consumption and tank capacity: The spec sheet will provide the fuel tank capacity and consumption figures when it’s running at 100% load in both prime and standby modes.

The specs sheet also contains other information such as the model number, engine make and model, and alternator model and manufacturer.

Customer specifications may also specify redundancy requirements, hazardous area classifications, and other requirements for the control panel.

Regulations

The National Electric Code (NEC) Article 701 provides regulations legally requiring the installation of standby power systems in areas where a loss of power could endanger people’s lives, such as hospitals, wastewater treatment facilities, and military bases.

A government authority having jurisdiction (AHJ) will inform you if your establishment must adhere to this regulation. After that, the AHJ will inspect it to ensure compliance.

Some states, such as Florida and Louisiana, extend this requirement to other forms of businesses. The requirements affect motor fuel facilities like service stations near terminals, wholesalers, interstate highways, or evacuation routes.

What Does the Generator Control Panel Display?

The actual display panel shows a wide range of data and information, such as:

1. Anti-surge circuit breaker status
2. Error codes
3. Battery charge status
4. Load on the generator by connected appliances
5. Amount of time left before the next service

Benefits of a Generator Control Module

Installing a generator control panel delivers the following benefits over manual operation:

• Improved efficiency: The microprocessors receive real-time data and make adjustments to streamline operations, ensuring optimal operations.
• Enhanced safety: Provides up-to-the-minute updates on the volt and current supervision, sends alerts and notifications, can trigger the alarm in case of an emergency, and shuts down the generator if it becomes dangerous to continue running it, which enhances safety.
• Minimizes errors: It facilitates autonomous operations, with the microprocessors overlooking the running and daily management of the generator, minimizing operating errors.
• Reliability: A control panel sends data periodically, which you can analyze and find solutions to tweak the generator’s operations and run it more reliably.
• Lowers costs: Improved reliability and efficiency lowers maintenance costs and frequency while reducing operational costs.

An appropriate generator control panel works autonomously and allows for remote and manual interventions to ensure the smooth running of the generator.

In the world of energy production, power plant control systems play a crucial role in managing the intricate operations of modern power plants. These systems, monitor, regulate, and optimize the various processes to ensure the efficient generation of electricity. This article delves into the purpose of power plant control systems, types of controls, and common systems.

Purpose of the Power Plant Control Systems

For the power plant to operate and generate electricity, multiple pieces of equipment, including control systems must work in tandem. Synchronizing the operation requires precise control to ensure the cycle and the equipment and processruns within the specified design parameters. Power plant control systems coordinate plant operations, and ensure the dependable and efficient generation of power.

Types of Controls in the Power Plant

In a contemporary power plant, most of the control operations operate automatically. The control functions can be classified into two basic groups: on-off control and modulating control.

The on-off control generates a control response that fluctuates between distinct conditions. An illustration of this form of regulation involves the initiation and cessation of a motor. The control system generates a begin command or a halt command, and the controlled equipment responds to the prompt by either running or stopping the motor.

Modulating control generates a control output signal that efficiently fluctuates in magnitude between different values. An illustration of this form of control involves the regulation of the flow of oil to a tank by adjusting the position of an oil intake valve in some industrial equipment. Most commonly, modulating control equates to 4-20mA control. The 4-20mA schema allows for a varying degree of current to modulate the control output.

Common Types of Power Plant Control Systems

A power plant control system typically contains different systems which include distributed control systems (DCS), supervisory control and data acquisition (SCADA), IOT systems, safety instrumented systems (SIS), programmable logic controllers (PLC), human-machine interface (HMI), and historian systems. One, some, or all of these systems may be deployed, depending on process design.

Ensuring these systems work together seamlessly provide predictable operation and quick responses to changing circumstances. Seamless integration makes it easier for data to run smoothly, lowering the chance of miscommunication and improving plant performance. Putting DCS, SCADA, Historian, PLCs, and HMIs together demands an efficient power plant control schema to ensure safe, reliable, and efficient processes.

Distributed Control Systems (DCS):

Most power plant control systems employed in large-scale facilities contain a distributed control system (DCS) which is a computerized control system designed for managing a procedure or facility. These are found in large power plants where multiple processes need to be coordinated and controlled centrally. It consists of multiple independent controllers that are spread out across the system, without a central operator supervising management. The Distributed Control System (DCS) idea enhances dependability and diminishes installation expenses by localizing control functions near the process plant while enabling remote monitoring and supervision.

Supervisory Control and Data Acquisition (SCADA):

SCADA, short for supervisory control and data acquisition, refers to a group of software tools employed to operate manufacturing procedures. It entails collecting real-time data from distant places to regulate equipment and states of the system.

SCADA systems consist of both hardware and software components. The hardware portion collects and transmits data to field controller systems, which then relay the data to other systems for processing and presentation on a human-machine interface (HMI) immediately. SCADA systems also document and chronicle all occurrences to demonstrate the status and problems of the process. SCADA applications offer alerts when conditions become perilous by emitting audible alarms.

IoT System

The IoT control system utilizes a microcontroller to analyze the data collected by the sensors and transmit it to a cloud-based application. The IoT system offers up-to-the-minute information on the overall condition of a power generation facility, therefore aiding in plant automation. IoT focuses more on data collection and analysis vs. SCADA which focuses more on machine-to-machine communication.

Safety Instrumented Systems (SIS)

Safety instrumented systems are frequently employed in process facilities such as nuclear or chemical plants, as well as refineries. They safeguard against accidents resulting from elevated fuel gas pressure or increasing reactor temperatures, for example. A Safety Instrumented System comprises sensors, logic solvers, and final control components that bring the procedure to a secure state after breaching of specific conditions. An SIS, or Safety Instrumented System, carries out precise control functions to prevent hazardous process processes in the event of unacceptable or perilous situations. An essential feature of a SIS is its inclusion of instruments that detect when process variables such as flow, temperature, and pressure in the case of a processing facility exceed predetermined parameters.

Programmable Logic Controllers (PLC)

A programmable logic controller (PLC) or programmable controller fits typical use in a small-scale facility or an equipment package that is part of a bigger plant. This specialized computer systems controls manufacturing procedures in industrial settings. It can withstand harsh conditions and controls activities such as assembly lines, machines, and robotic devices. PLCs provide high reliability, ease of programming, and the ability to diagnose process faults.

Human-Machine Interface (HMI)

A Human-Machine Interface (HMI) works well for local components in a power plant control system installed in a small-scale facility. An HMI provides a user interface that establishes a connection between an individual and an industrial machine, or device. HMIs oversee and modify set points, issue commands, and control algorithms, and modify and manage settings in the controller.

Historian Systems

Historian Systems provide high-capacity data storage systems specifically designed to efficiently gather, store, and retrieve time-dependent information at exceptionally fast rates. Historians offer a consolidated and thorough perspective on the performance of industrial processes throughout time in the monitoring and control of such processes. The historian’s role entails the storage and documentation of all the data aggregated by the SCADA system. It enables operators and stakeholders to analyze past data about the plant. A historian may possess the skill to report as well.

In Conclusion

Engineers should take care to understand the needed function of a power plant control system and how to design systems accordingly. Whereas, plant operators must know that power plant control systems typically comprise of a multiple of subsystems. Understanding how each type of control system works together allows operators to better understand and maintain existing systems.

One significant hurdle that industrial facilities encounter is the build-up of coke/scale deposits within process tubes. This internal fouling, if not addressed, could result in a plethora of operational issues. This introduces the need for the decoking process. In this article, we review the coke formation process in equipment and its effects, coke detection techniques, and methods of decoking.

Coke Formation in Equipment

Coke refers to a carbonaceous residue that forms on the walls of combustion chambers or process tubes of equipment such as boilers. The formation of this material is a complex process that occurs due to the decomposition of heavy hydrocarbons like asphaltenes into solid carbonaceous deposits. During the heating process in facilities such as fired heaters and boilers, the hydrocarbons in the feedstock crack and decompose into smaller molecules. As the temperature increases, the smaller molecules polymerize and cross-link with each other to form heavier, more complex molecules. These new molecules are less volatile and have a higher tendency to decompose and form solid carbon deposits, or coke.

Effects of Internal Fouling

Internal fouling, which refers to the presence of coke/scale deposits on the walls of industrial equipment, can have profound effects. The following sections review some of these effects, thus, highlighting the need for decoking.

Degradation

Coke deposits create an environment for the accumulation of corrosion-promoting species. For example, sulfur-containing compounds can aggregate at deposit sites and react with the metal surface of equipment to form sulfides. These sulfides can cause hydrogen embrittlement and localized corrosion. Also, the build-up of coke may result in carburization – a type of high temperature corrosion where carbon diffuses into metal and forms carbides, which weaken the metal. Moreover, the formation of carbides reduces the effectiveness of coatings and other corrosion inhibitors. Thus, highlighting the need for the decoking process.

Minimal Heat Transfer

Coke has a low thermal conductivity. So, as it accumulates on the walls of equipment, it acts as an insulating layer that reduces heat transfer efficiency between combustion gasses and process fluids. Compensating for this requires an increase in operating temperature, but ensues harmful effects. Operating at higher temperatures increases the risk of mechanical damage and certain types of corrosion. Eventually, it will become necessary to carry out decoking.

Hotspots

Hotspots refer to localized areas of elevated temperature on equipment. They are a result of a variety of factors, one of which are coke deposits. When a hotspot occurs, the temperature of the affected component could rise above its design limit, thus, leading to warping, material degradation, or even failure. 

Limited Productivity

As coke builds up on the internal walls of channels, there is reduction in the cross-sectional area. If this continues, it could result in bottle-necks or even complete blockages. This will have a significant impact on operational throughput. Therefore, it is necessary to have a monitoring system or carry out regular inspections to ascertain the level of build-up, and to enable decoking process scheduling.

Coke Detection Techniques

Early detection of coke deposits is crucial for minimizing operational disruptions via proactive maintenance. Some common techniques include:

• Infrared Imaging: This entails utilizing infrared cameras to identify hotspots on equipment, which are indicative of coke deposits. This non-intrusive method is ideal in areas where access is challenging.
• Ultrasonic Testing: Ultrasonic testing detects coke deposits in equipment by measuring sound waves. Utilizing this method is effective when identifying coke deposits before they become severe, thus allowing for proper scheduling of the decoking procedure.
• Nuclear Magnetic Resonance (NMR): NMR provides detailed insights into the composition and thickness of coke deposits. In addition, it allows for a comprehensive analysis of coke accumulation, which aids in determining the most suitable decoking method.

Types of Decoking

Several methods can serve in the decoking of process tubes in industrial applications with mechanical, chemical, steam-air decoking, and in-line spalling being the most common.

Mechanical Decoking

This decoking process entails flushing out coke from equipment using a pig – a mechanical device with radial appendages like a wire brush. Pressurized water traverses the pig through the equipment, and as it moves, its appendages scrape out the coke on the internal surfaces. Generally, the cleaning process starts with a pig of a smaller diameter and gradually progresses to a pig diameter equivalent to the pipe/tube nominal diameter. Several runs are made with the duration of the process depending on the level of adherence, thickness, and hardness of the fouling.

Chemical Decoking

The chemical decoking process involves circulating and soaking equipment in solvents that soften or dissolve coke deposits. After giving enough time for the solvents to work, water is used to remove all deposits. During this process, it is important to monitor the chloride content of the water to avoid corrosion damage of the equipment. Chemical decoking is ideal for systems with complex geometries and hard-to-reach areas. However, this method is not environmentally friendly, so there is need for careful disposal when flushing, which makes this method more expensive.

Steam-Air Decoking

This method entails using a mixture of steam, air, and heat to cause shrinkage and cracking of the coke deposits. While the steam and air mixture passes inside the equipment, the heating is external. Steam-air decoking works best for radiant tubes, but it does not always remove coke thoroughly. When this is the case, it may be necessary to use another method or to dismantle the equipment; which incurs additional expense and risks damage. Another disadvantage is that chemical reactions of hot coke, steam, and air produce CO, CO₂, and H₂, which are bad for the environment.

In-Spalling Decoking

In-spalling decoking involves using high-velocity steam to deliver thermal shocks to equipment to create a contracting and expanding effect, to spall coke off internal walls. This is achieved by alternately heating and cooling the steam. Although this method offers less environmental issues than steam-air decoking, and minimizes downtime in comparison to other methods, it is largely less effective. Also, the equipment is susceptible to damage due to contraction and expansion during the spalling process.

Making the right choice between utilizing a gas turbine vs steam turbine is crucial when setting up power generation plants, as each technology offers distinct features. In this article, we delve into how gas and steam turbines operate, their respective advantages and disadvantages, and provide a comprehensive comparison across various technical parameters.

Gas Turbine

A gas turbine operates on the principle of generating energy from the combustion of fuel and converting it into mechanical energy. The process begins with air intake from the atmosphere, which is subsequently pressurized by a compressor. Then, the compressed air passes into a combustion chamber. There it mixes with gaseous fuel, and undergoes combustion to further increase its temperature and pressure.

Next, this hot and pressurized air is channeled to flow over the turbine blades, where it expands and causes rotation of the blades. The torque from these blades is transmitted via its shaft to a generator to produce electricity. Hot air, which could be up to 1500℃, exhausts into the atmosphere or preheats air coming into the system. Gas turbines are renowned for their high power-to-weight ratios. This means they work well in weight sensitive applications such as aircraft propulsion.

Advantages of Gas Turbines

Gas turbines provide several benefits including:

• Fuel Flexibility: Gas turbines can operate on various types of fuel such as aviation fuel, natural gas, and diesel.
• High Power Density: Their power output is high in comparison to their size and weight.
• Quick Start-Up: They have rapid start-up times, which makes them ideal for applications with fluctuating power demands.

Disadvantages of Gas Turbines

Some downsides of using gas turbines are:

• Lower Efficiency at Partial Loads: Gas turbines are likely to experience a reduction in efficiency under partial loads.
• Emissions: Because they use hydrocarbons as fuel in the combustion process, the process results in the emission of pollutants such as NOx.

Steam Turbine

Unlike a gas turbine, a steam turbine is powered by the energy in hot, gaseous steam, thus, working like a cross between a wind turbine and a water turbine. For a steam turbine, a pump sends water into a boiler, which produces steam by utilizing the heat from coal or other fuel combustion.

Renewable thermal energy sources can also be the source of steam.

Moreover, in a combined cycle setup, the exhaust air from a gas turbine heats up water in the boiler to obtain steam. This setup works well because the highest internal temperature in a steam turbine ranges between 500 and 650℃, which is less than half of the exhaust air temperature from a gas turbine.

Typically, the steam passes through a series of boilers and intercoolers, where the pressure at each stage is higher than the previous. After the final boiler stage, the superheated steam passes over the turbine’s blades where it causes rotation of these blades as it expands and condenses. Generally, steam turbines are used for electricity generation, but can also serve in providing mechanical drive for various rotating equipment such as compressors and pumps.

Advantages of a Steam Turbine

The benefits of using steam turbines include:

• High Efficiency: The steam turbine can achieve high thermal efficiency vs a gas turbine, especially in large-scale power generation.
• Better Efficiency at Partial Loads: A steam turbine offers better efficiency when handling partial loads in comparison to a gas turbine.
• Lower Emissions: They produce lower emissions during operation, and renewable energy sources can serve in heating instead of hydrocarbons. In addition, the working fluid, which is water, can be reused.

Disadvantages of a Steam Turbine

• Slow Start-Up: Steam turbines have longer start-up times in comparison to gas turbines. So, they are not ideal for applications where power demands fluctuate frequently.
• Size and Weight: A typical steam turbine setup will have several stages of boilers and intercoolers, which occupy significant floor space. This setup gets larger and heavier as the power output increases, thus, limiting their use in certain applications.

Differences Between Gas Turbine vs Steam Turbine

Gas turbines and steam turbines are similar in that they both generate electricity and provide mechanical drive for equipment. However, they have unique features as the following table highlights.

Parameters	Gas Turbines	Steam Turbines
Efficiency	Have lower efficiency values than steam turbines. The highest efficiency values achieved by OEMs is currently just over 60%	Thermodynamic efficiency ranges from 65% for small units (under 1000 kW) to over 90% for large industrial units.
Installation	Its main parts consist of just a compressor, combustion chamber and turbine. Thus, it occupies less space and is cheaper to install.	Usually has multiple stages of boilers and intercoolers that take up significant floor space. So, installing the same capacity is more expensive in comparison to gas turbines.
Execution	Operates using the Brayton cycle.	Executes a water-based cycle, which is the Rankine cycle.
Control	It is easier to control with fluctuating load conditions, but is less efficient during partial loading.	Difficult to control with fluctuating load conditions, but more efficient during partial loading.
Environmental Impact	Has more emission as it always uses hydrocarbons, and the exhaust air is vented to the atmosphere.	Gives off less emissions and can use renewable energy for heat generation. Also, the exhaust steam can be reused.
Maintenance	Offers a low-maintenance setup.	Utilizes several components, so requires more maintenance efforts.