Metering, monitoring feedwater systems

One of the most common misunderstandings sees in boiler water treatment programs is the confusion surrounding the measurement of condensate return and the correct configuration and dosing point for chemical injection.

09/18/2013


One of the most common misunderstandings sees in boiler water treatment programs is the confusion surrounding the measurement of condensate return and the correct configuration and dosing point for chemical injection.

How to determine condensate return

The amount of condensate return is an important aspect of understanding the water/steam relationship of any steam generating plant. From a water treatment perspective, it determines the cycles of concentration, the level of make-up dilution and therefore the untreated quality of feed water.

Mass balance equation: FW = MU + CR

By placing meters on the make-up (MU) and feedwater (FW) pipelines, we can quickly determine the amount of condensate return by mass balance.

When combined with steam metering (S) we can also determine the blow down rate (BD) of the boiler.

Mass balance equation: FW = S + BD

These two critical parameters determine the level of chemical dosing required and the adequate level of blow down, and the estimated chemical consumption and therefore cost of the program.

Chemical dosing—where and how?

Now that we can quantify the chemical demand of the feed water with adequate metering, where do we dose the chemicals? The chemical dosing point can be a complicated decision based on the sophistication of pre-treatment plant and the nature and number of chemicals used. For this discussion we will restrict our interests to simple feed tank (no economizer or deaerator) and simple chemical programs based on oxygen scavenger, alkalinity and non sequestrant inhibitors. This would adequately represent 90% of industrial steam plants.

Ensure that the chemical containing oxygen control is dosed close to the feed water outlet at the feed tank away from incoming make-up water agitation. The most common mistake is to dose this chemical into the middle or upper part of the feed tank, this results in inadequate corrosion protection of the boiler, or excessive chemical use. For the preferred two- to four-pump system, depending on the chemistry, most scale inhibitors and alkalinity agents may be dosed in the feed line. There are no one-drum programs that outperform the multi pump alternatives.

Content provided by Spirax Sarco, originally published in Steam News Magazine.



No comments
The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
Strategic outsourcing delivers efficiency; Sleeve bearing clearance; Causes of water hammer; Improve air quality; Maintenance safety; GAMS preview
World-class maintenance: The three keys to success - Deploy people, process and technology; 2016 Lubrication Guide; Why hydraulic systems get hot
Your leaks start here: Take a disciplined approach with your hydraulic system; U.S. presence at Hannover Messe a rousing success
Flexible offshore fire protection; Big Data's impact on operations; Bridging the skills gap; Identifying security risks
The digital oilfield: Utilizing Big Data can yield big savings; Virtualization a real solution; Tracking SIS performance
Getting to the bottom of subsea repairs: Older pipelines need more attention, and operators need a repair strategy; OTC preview; Offshore production difficult - and crucial
Applying network redundancy; Overcoming loop tuning challenges; PID control and networks
Putting COPS into context; Designing medium-voltage electrical systems; Planning and designing resilient, efficient data centers; The nine steps of designing generator fuel systems
Package boilers; Natural gas infrared heating; Thermal treasure; Standby generation; Natural gas supports green efforts

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
This article collection contains several articles on the vital role that compressed air plays in manufacturing plants.
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.
This article collection contains several articles on strategic maintenance and understanding all the parts of your plant.
click me