Boiler efficiency is an important factor in process and manufacturing industries defined by the amount of combustion energy converted into steam energy. On the other hand, steam quality determines the amount of liquid or water present in the generated steam. Steam is beneficial as a heat transfer medium for processing operations as it releases a large amount of heat by condensing with water. Additionally, steam is safe and non-flammable with the capability to transfer heat at a constant and controlled temperature. Compared to other heating mediums, steam is cost-effective and completely recyclable. Despite the many advantages of the steam, process plants experience various problems like safety issues, equipment failures, and poor efficiency of the steam boiler. It may lead to severe boiler problems such as frequent boiler shutdowns, damaged steam pipes and valves due to water hammer, vibration, erosion, corrosion, reduced steam heater capacity, and overloaded steam traps. The most common cause for boiler problems is low steam quality, also known as wet steam or water carryover.
Although standards of steam quality depend on the application, it is necessary to ensure required actions by,
- Assessment of steam utilization and costs
- Managing the water quality
- Optimizing steam boiler design
- Incorporating best maintenance practices
Factors Influencing Steam Quality:
Applications of Steam:
The degree of steam quality varies by its application. High steam quality is vital for industries like power generation and food processing. Pharmaceutical industries require high-quality pure steam, whereas hotels can tolerate steam boilers with a relatively low steam quality but optimal efficiency.
Understanding the Challenges:
Lack of maintenance and knowledge is one of the common threats faced in manufacturing and process units. Secondly, the advanced age of steam boiler systems hinders the steam-generating capacity. Water carryover is the primary cause of low steam quality that results from incomplete separation of steam and water. Both mechanical and chemical factors lead to water carryover. It not only impacts steam quality but also affects steam boiler efficiency and safety. Carryover reduces the dryness of steam and heat content as well as causes erosive damage to piping and equipment of steam boilers. Steam quality also includes risks of tuning of the control system for adapting component usage and wear.
Steam Usage and Costs:
Proper boiler maintenance depends on understanding steam usage. It is necessary to determine the amount of steam used compared to the cost of the steam. In regular maintenance of the steam traps, examine the amount of steam used, method, and purpose of use, assessing if there are ways that would improve the steam quality.
Quality of Feed Water:
Ensuring high-quality feed water is the best way to eliminate steam quality issues. Water consists of impurities like dissolved salts, silica, and organics. It is essential to monitor the feed water quality and maintain it to industry standards to prevent water impurities from being carried over with steam. Scrubbing steam is an ideal way to achieve clean steam.
Steam Boiler Design:
Steam quality depends on the design and piping of the steam boiler. With the latest developments in technology and design, steam boilers are fabricated to reduce maintenance costs. The tolerance of carryover is a major consideration while selecting a steam boiler system. Once the system is installed, it must be ensured that the steam lines are properly insulated.
Maintenance Practices:
Proper and regular maintenance practices can prevent steam quality issues. Some of the essential steps advised by the boiler manufacturers are,
- Auditing the Boiler system and control equipment to detect weak points and make necessary improvements.
- Re-tuning of process control loops
- Introducing and improving automation control
- Train the operating staff for the proper handling and maintaining of the boiler system.
Effects of Low Steam Quality:
Proper operating practices and maintenance of steam boilers ensure high steam quality, necessary for controlling the heat transfer efficiency and steam boiler performance. Low steam quality impacts the boiler system in various ways such as,
Decreased heat transfer efficiency:
Low steam quality can reduce the heat transfer efficiency by around 65%. The excess liquid in low-quality steam accumulates on the surface of the heat exchanger that causes a buildup of liquid. It reduces the ability to transfer the steam energy to the product.
Failure of Valves:
When low steam quality containing liquid passes through control valves, it erodes the internal of valves and causes failure.
Failure of Turbine Component:
Liquid introduced with steam in turbine operation reduces the lifespan of the internal components.
Water hammer:
Excess liquid due to poor steam quality leads to a water hammer. It is a safety issue in a steam boiler that may cause failure in the system.
Rakhoh Boilers is one of the leading boiler manufacturers in Pune since its inception in 1983. We provide efficient steam boilers and thermal solutions in over 20 process industries globally. We offer the best boiler services like steam trap assessment, boiler automation, energy audit, annual boiler maintenance, etc. to boost the efficiency and productivity of steam boilers.
For ensuring high steam quality, it is necessary to follow the given guidelines,
- Insulation of steam lines and components
- Proper startup procedures
- Proper chemical treatment of feed water
- Installation of steam separators if required
Learn more about our products and services at www.rakhoh.com