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October 7, 2019

Pressurized Condensate System for Industrial Plants – Part 2


Part 2 — Pressurized Condensate Systems for industrial steam and condensate systems that have a tremendous benefit to increase the plant’s steam system thermal cycle efficiency.  The videos are in three parts; and this is part two.  Also, technical papers and articles are on our web site to help plant engineers understand all the benefits to the pressurized condensate system.  www.invenoeng.com

Pressurized condensate systems can provide plants with a minimum of between 5% and 35% savings in fuel costs when compared to a conventional atmospherically vented condensate system. That is a tremendous opportunity for facilities, since fuel prices have gone up and are expected to increase even further. The pressurized condensate system is not a luxury; rather, it is a necessary component to maximize and increase the steam system’s efficiency. Unfortunately, not all steam plants or steam applications can implement a high-pressure condensate return system. Therefore, proper preliminary engineering assessment, design review, and knowledge of the application are necessary to ensure a successful condensate system.

My name is Kelly Paffel, technical manager for Inveno Engineering LLC located in Tampa, Florida. We are a domestic and international engineering firm, specifically focused on steam and condensate systems. This is part two, the pressurized condensate recovery systems… again, a solution to increasing the steam system’s thermal cycle efficiency.

In a example of a standard condensate system. And we’ll take an application to come up with the benefits, cost benefits for implementing a pressurized return system. So we’ll give a example of a system out there is running at 190 psi. So the system running at 190 psi providing steam to these process coils right here. The steam temperature is 384 degrees Fahrenheit and we’ll say the steam flow rate’s 9,000 pounds per hour. Operation’s seven 24 and seven days a week, 24 hours, and 365 days a year.

As we come to the drain devices, steam traps, or control valve, the condensate is going to come down into this tank. It’s going to be at 384 degrees temperature and atmospheric there’s going to be a percentage of it is going to change from liquid back to flash steam. We’ll say that percentage is about 18.3%, standard atmospheric system, flashes just allowed to go to atmosphere, and that’s a sizeable loss.

So we look at the calculation. So this is a vented condensate receiver allowing the flash steam to be vented. If we did the calculation, S H minus S L divided by L H L, which is Latent heat law. So sensible high 190 psi, sensible low at atmospheric 180 Btu, and then the latent heat energy low 970. We do the calculations and we’ll come up with 18.3% of flash that’s going to occur. So if we take that times our flow rate, we come up with 1,647 pounds of flash going to be vented to atmosphere. Well, let’s say it costs us $7.50 per thousand pounds and we come up with a loss just in the flash steam $108,000, so this here is going to be $108,207 per year.

So if we look at understanding the standard condensate system losses, again, we have flash steam losses here of $108,000. Flash steam, and we give you condensate loss for every pound of steam that we’ve vent to atmosphere, we have to make up with a pound of water or makeup water. And the makeup water does have a cost.

So let’s say $4,360, sorry, $4,336 for a year at 15 cents per gallon for preparation costs of the makeup water and that’s water, chemical, et cetera. Then the energy to heat the makeup water back up to the deaerator operation and we’ve got $19,168 per year, and the deaerator we said was operating at 10 psi. Then energy to heat the condensate coming back, which was 7,353 pounds and that’s 9,000 miles of flash steam, and we come up with a cost of $11,431 per year. So if we add this all up, then we got 108,000 right here for the flash steam losses, 4,336 for the makeup water costs, 19,168 for the energy to heat the makeup water back, $11,431 to heat the condensate back from atmospheric conditions, which is a hundred degrees C or 212 degrees Fahrenheit. And we end up with a total energy loss per year, $143,142 per year. And the other note, this is a small process application. It’s only 9,000 pounds per hour.

So if we look at a pressurized system and the pressurized system we’re looking at coming off of the process coils, and then going through the drain devices, steam traps, and control valve, but we’re operating the condensate tank here 125 psi or 363 degrees Fahrenheit. So the condensate is coming down in here and we’re controlling the flash. Now to consume the flash, we take a flash steam and we provide that to the deaerator, because the deaerator needs steam to heat up the condensate coming back at atmospheric conditions and the makeup water. So we’re consumed the flash steam there.

Now we can take the condensate coming off this tank and pump it directly back into the border. Any condensate that’s not been exposed to atmosphere does not have to go through the deaerator operations. So a pressurized condensate system, we’re not allowing flash steam losses. We’re consuming it into the deaerator. Keeping the sensible energy in the condensate. You elevate it and going right back up in the border. And the other thing is controlling flash steam at a point the flash steam can be recovered into a deaerator, or a cascade system, or some other method instead of venting to atmosphere. So we’re controlling all those aspects of it.

Now, and the thing is is that the pressurized system really has to be looked at at total system and the failure with pressurized systems, people ain’t come and look at certain segments of the system. Really, there’s 14 different points out there that we look at, the operating pressure of the boiler, the fuel input, steam flow to the hatter. I mean again, there’s so many points out here in the system that has to be looked at and everything has to be detailed out to make sure the system’s going to work correctly. So the minimum is 14 points and we’ve done as many as 35 points in the system to look at all the dynamics of the system that makes sure that the system will work correctly.

Now we take this information here and we input it into our software system. And we just took a example, another example here, and the example here, what’s atmospheric system. And we came up with a total energy loss of $226,000 in energy loss. But the system here, the software system analyzes everything in the system with the calculation. So when we calculate out the implementation of a pressurized system, we give a very conservative number of what’s going to be achieved in the steam losses or energy reduction. And that really gives us a good number for the payback in the system. So here we have $226,701 to work with for implementing a pressurized system.

So here we go in the system after implementation, so we can put into the software, all the dynamics we’re going to change in the system, what pressures we’re going to come back and operate at. And then we come up with zero losses now because we’re recovering a flash, we’re bringing the condensate back, and really, the dynamics of the system is balancing out. So the point is it has to be looked at as a system and everything has to be calculated out, so you know what the cost benefits are. There are no fuzzy numbers you know. People always come into the plant says, “This is going to save you 5%,” or “This is going to save you 3%.” Everything in the steam and condensate system can be mathematically calculated out and that’s what you need to do to make sure that the project’s going to pay for itself.

The last is our contact information. Our approaches, we’re a part of your team, and we have short term impacts and longterm impacts. And we’re here to help you out. This is our contact information so please visit our website. We have… All information is generic. There’s no vendor information on our website, so it provides you great calculations and information on implementing different things in the steam system.