Frequently Asked Questions Regarding Venturi Technology for Steam System Condensate Removal
“EVCR Unit” – Enercon’s Venturi Technology for Condensate Removal
(316 Stainless Steel, Solid Drilled Venturi with Accompanying Y Strainer)
- 1. Why does Enercon recommend venturi technology for condensate removal from a steam operating system versus the standard mechanical steam trap offerings?
- 2. Why does Enercon start with a complete technical evaluation of a system before the sizing of an EVCR Unit?
The reason for performing a technical evaluation of a system is to ensure that the steam system is set up correctly. This evaluation informs all recommendations and actions thereafter.The correctness of a system design not only influences the operational efficiency of a steam system but also informs the correctness of all the future data we collect on the system. Therefore, Enercon’s initial steps involve discussion of the system with operational personnel, review of pertinent drawings, and walking the relevant portion of a system from the boiler to the end of the line.
Some, but not all, of the items we review during our technical evaluation are:
- Equipment (& original manufacturer design for such);
- Control Sizes;
- Functionality of DeSuperheaters;
- Are pumps required?
- Propriety of steam piping, indoor vrs outdoor systems, environmental issues such as temperature and humidity, etc;
- Trap spacing, are there traps where they need to be, where is the trap in the system, etc.
- Condensate return system – piping design, what is it returned to, designed pressure, distance, etc.;
Again, these are just some of the factors we consider when we examine a steam system.
- 3. Why does Enercon collect so much data before the sizing of an EVCR Unit?
To properly size any condensate removal technology, whether it be venturi technology or a traditional mechanical steam trap, it is necessary to have a complete understanding of not only the condensate loads but also any secondary and tertiary related factors at each point a unit is installed in the system. These secondary and tertiary factors include considerations such as the exact operation a unit is performing; understanding the equipment associated with any operation; where in the system is the unit’s location; is the condensate being returned; if returned then the pressure, lift, distance and to what is that return; what effect does factors such as an indoor system versus outdoor system, humidity, temperature, etc. have on the system; is the piping design of the system proper; etc.It is only in understanding these and other factors can a venturi, and a mechanical trap for that matter, be properly sized to maximize the efficiency of complete condensate removal while minimizing associated energy loss.
- 4. How is the EVCR Unit more efficient, more economical, and permanent in comparison to existing conventional mechanical steam traps?
The job of any condensate removal device is to completely rid a steam system of the condensate that forms continuously as steam gives up its latent heat and condenses while keeping BTU rich steam in the system. Condensate in a steam system reduces heat transfer, increases equipment damage, and causes erosion, corrosion and water hammer in the piping system. It is critical to purge condensate completely, quickly, and efficiently.Every condensate removal device, be it an EVCR Unit or a mechanical trap, has an orifice. Whereas the EVCR Unit extracts condensate through a non-moving, continual flow technology; a mechanical trap operates on a batch system – they open in the presence of condensate and close in the presence of steam.
A properly sized EVCR Unit operates continuously in the lower end of a Steam Loss to % Condensate Capacity chart while a mechanical trap (whether it’s open/shut mechanism is activated by internal floats, buckets, bimetals, bellows or discs) ramps up into the upper ranges every time it opens. Therefore, in normal operating steam processes, a properly sized EVCR Unit on day one of installation is up to 3% – 4% more efficient than a perfectly operating, brand new mechanical trap. Multiple clients have proven this in both laboratory setting tests and field tests. These tests have been performed under both general field operational comparisons and more defined Six Sigma parameters. In every test in which Enercon has been allowed to properly size the venturi, Enercon’s EVCR Unit has measured superior in performance.
This superior performance only increases as the mechanical trap begins to wear out. On 24-hour-a-day applications, mechanical traps cycle several times a minute or a couple of million times a year, resulting in wear and leakage. This is why lower quality mechanical traps can experience complete failure in six months or less. Even for the best quality mechanical traps, which can last 3 – 5 years before total failure, the wear and tear from the repeating purge cycle results in the initiation of performance degradation long before total failure. Due to this degradation, it is not unusual for the entire mechanical trap population of a plant to be operating at 15% to 30% below its maximum, brand new efficiency. On the other hand, since the EVCR Unit has no moving parts, it doesn’t wear out and the efficiency experienced in year ten will be exactly the same as that experienced on day one.
- 5. Why is the EVCR Unit superior to existing mechanical trap technology in handling varying loads?
(see a more detailed discussion in the “EVCR Unit Technology” Section)The EVCR Unit is sized to remove 100% of the condensate load produced by a particular application at a particular location in the system. With the EVCR Unit, steam traveling at the speed of sound continuously forces much slower, denser condensate through a precisely sized hole. This denser condensate blocks steam from escaping.
At 100% capacity, it is easy to understand that an accurately sized orifice device loses no steam and backs up no condensate. But varying, not constant, loads are the norm. The question is how well does the EVCR Unit handle this varying capacity – does it lose inordinate amounts of steam when condensate occupancy is less than 100% versus a functioning mechanical steam trap?
Actually, the opposite is true. An EVCR Unit handles varying loads more efficiently than mechanical steam traps in almost all applications. First, because the EVCR Unit continually removes condensate from a system, the size of the EVCR Unit orifice opening is significantly smaller than that of the orifice in a mechanical steam trap. This is because a mechanical steam trap requires a significantly larger orifice enough to handle the batch processing of larger periodic loads.
Secondly, a continual flow technology is subject to the dynamics of two-phase flow physics. When the load drops below 100% capacity, the physics of two-phase flow, along with the magnification effect the venturi design, causes a violent turbulent mixture of steam and water. The turbulence of the significantly heavier and denser water results in a shield that prevents steam loss as the water works its way through the orifice. Even as the varying load drops to 68% of capacity, no steam loss will occur through the venturi orifice due to this turbulence. As the load continues to drop below 68%, the turbulent effect still continues and will only allow negligible steam loss.
For instance, in a 100-psi system producing 375 lbs/hr condensate, an accurately sized Enercon unit loses 1.76 lbs/hr steam if load drops to 25% of capacity, which it will do only sporadically. At 100 psi, according to the D.O.E. and trap company ‘Leaking Steam Trap Discharge Rate’ charts, a failed conventional trap with a 1/8” internal orifice loses 52.8 lbs/hr.
In varying pressure environments without the presence of a pressure control valve, Eneron recommends EVCR Units for applications where the load may drop as low as 25% of capacity, although sources such as the U.S. Naval Facilities Engineering Command Supplements (10-90 & 1-92) say ‘a fixed orifice sized for a 100% load operates efficiently down to a 10% load. Any turndown greater than 4 to 1 will be reviewed to as whether an EVCR Unit or another technology is a more appropriate application.
A modulating or solenoid control valve eliminates any issue of an EVCR Unit’s application in a varying pressure environment
Hampton Affiliates, a leading lumber company which converted multiple mills to the EVCR Unit system stated: “Our operations are all zone control, so we have a constant variable load situation. (Enercon) traps perform with excellence in this type of environment.” (Timber Processing magazine July/Aug. 2004)
- 6. What are the anticipated financial and performance results in a complete facility conversion from mechanical traps to EVCR Units?
What are the results? Historically, upon installation of the implementation of our technical evaluation findings and our EVCR Units, Enercon customers typically report the following;
- Increased Facility and Equipment Operational Efficiency;
- Improved Product Quality;
- Reduced Energy Costs of 10%-35%+;
- Reduced Carbon Footprint of a Similar Amount
- Reduced Water Demand and Chemicals of a Similar Amount;
- Virtual Elimination of Steam Trap Maintenance and Failed Steam Trap Related Equipment Repair Expenses;
- Reduce Condensate Related Equipment Damage;
- Solutions to some Steam Related Problems such as Low and Inconsistent Temperatures, Trap-Related Pressure Drops, High Back Pressure and Water Hammer;
- Improved Facility and Environment Safety
The result is that most customers experience project paybacks less than 12 months with some extreme cases experiencing payback less than 3 months. And these savings are repeated annually as the EVCR Units are a permanent solution with minimal, if any, maintenance.
- 7. What are the results of conversion to the EVCR Unit when a company believes it has a first rate steam trap maintenance program?
TO ACHIEVE LESS THAN A 5% TRAP FAILURE RATE, The Department of Energy (Energy Tips – 6-99) states that a facility needs to perform weekly inspections of its systems 150 psig and above, monthly inspections of its systems in the 35 psig to 150 psig range and annually inspect its systems below 35 psig.Almost every production and maintenance person will tell you that this level of testing is unrealistic as is the immediate replacement of every trap as it reaches a certain level of degradation/failure. Plants do not have maintenance budgets that allow for such. Just the weekly testing of a 500 unit facility would require two, or more full time persons. Then add to that the personnel necessary to change faulty units as they are found along with the cost of replacement traps, fabrication, sectional shut down, and installation and you can see that such recommendations are just not practical. Steam traps are typically viewed as a low priority item and are changed on an ‘as needed’ basis.
As a result, The Alliance to Save Energy claims its studies show that on average 15% to 20% of steam traps in a facility will be inoperative – completely failed either open or closed. An English study claimed that 36% of the traps it examined were not functioning properly.
ENERCON UNITS ARE PERMANENT – To this day, Enercon has never had an EVCR Unit returned for non-performance or wear. Plants that converted to EVCR Units as long as 25+ years ago report that the units are still performing exactly as they did upon installation even when the plant has performed zero maintenance on the units. Plants in which Enercon performed system reviews 13+ years after installation of EVCR Units and implementation of technical suggestions showed zero wire draw on every inspected/measured unit, performance measurements exactly as on day one of installation on every tested unit, and exact pressure along the entire length of the operating system as designed for.
Even in systems experiencing severe chemical and corrosion problems, these issues have been typically resolved with a blowdown program of the Y strainer each EVCR Unit includes
- 8. In what type of applications do the EVCR Units efficiently operate?
EVCR Units are operating efficiently on tracing lines, unit heaters, humidifiers, drip legs, steam headers, submerged coils, heat exchangers, jacketed coils and other applications. EVCR Units are being used in facilities ranging from small, simple, low pressure systems to huge, complex, multi pressure, multi- process systems. Existing clients encompass almost every industry and application –petrochemical, lumber, plating, chemical, pulp & paper, packaging, pharmaceutical, food & beverage, hospitals, large buildings, airports, universities, dairy industries, power generation, etc.
from small individual plants to multi operational, multi facilities of Fortune 500 companies.
On completely converted plants, Enercon technology has been applicable for and replaced, on average, 99% of existing conventional traps.
It is company policy that we will not ship an EVCR Unit if it cannot perform the task involved or if there is not an economic benefit for an existing steam trap to be changed out. In the rare instance where Enercon technology is not appropriate, we will tell you what the correct alternative is.
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