Published: June 23, 2014 – by Dan Holohan
It would be an easy job – one of those transactions where a guy can make a quick dollar, but the truth was he did not really feel like he had it or not. He was already busy. But this one looked so easy. All that needed to be done was to convert a high pressure steam boiler into low pressure operation, so the building owner could use it for heating instead of the process. The owner also wanted it to reduce the boiler load by 75%, and everything related to the burner change, was not it? Nothing!
The contractor thought he could install the new burner, shake the old one for his parts, replace some steam traps throughout the system and remove the work. Easy. He did not know what to charge, as he knew he might encounter some unexpected problems, so he just threw a price that seemed okay, and he got the job.
Now, whenever that contractor got a job, he always liked to go back and look at his numbers. He wanted to compare them to what his competitors had offered – just to see if he had made a big mistake. When he asked the owner about the competitors, the owner told him that there had been none. He had been the only bidder at work. & Quot; No one else was interested, & quot; The owner told him. “We accepted your award because we had no choice.” How much time can you do the work? & Quot; This, of course, gave her a sense of rigor.
But all he had to do was take a 400 HP boiler that was running at 125 psi and was running like a 100 HP boiler that would release a 10 psi steam pressure in the system. The owner had just taken charge of this building, and he did not need such a boiler. The salesman had told him that he could pull many more years from the big boiler by rocking it a little. This made sense to the new owner. & Quot; It & # x27; S just like lowering a stove, & quot; The salesman had told him. “You just flipped the knob, as you would on a stove.” The salesman twisted with his hand and smiled. “Everything will be fine! & Quot;
This made sense for the contractor, as well as for the new owner. It seemed so easy.
But someone would have really noticed the size of the 400-HP boiler nozzle. You see the thing about high pressure steam is that it takes much less space than low pressure steam. It moves more slowly. People who do boilers know that. Unfortunately, the owner and the contractor did not know.
When the speed of the steam increases (which will certainly be when it is at low pressure and will target such a small nozzle), the steam will draw water from the boiler and send its vomiting into the Piping System. This causes the water hammer, which can break just about anything that is on its way. This will also cause a damp steam, which is not very useful when trying to heat something. This is why you can use a high pressure boiler on low pressure settings. The manufacturer of the boiler told the contractor about this when the contractor called to ask.
The contractor thought he could bypass the problem of high speed by cutting the boiler and lifting a larger nozzle over the hull. The manufacturer of the boiler said that it would probably work, but the contractor did not mention the pipes. They were still as small as ever. The manufacturer of the boiler had not requested the pipes because the contractor had not proposed them. The curiosity of the manufacturer of the boiler ended with the flanges of its equipment.
The contractor would reduce the largest hole, which would allow the steam to leave the boiler slower, but the steam would rise again when it touched those small pipes. The contractor had not considered any of these elements. He thought that when he installed the smaller burner, Mother Nature would take care of everything else. “It’s only 25 percent of the load!” He said. “The pipes should be fine. Should not they? I mean, I have not checked because I do not know how, but they should be fine. Should not they? & Quot;
Another problem was that the internal surface of the boiler had not changed a stinking bit. Of course, the contractor lowered the firing rate by installing the smaller burner, and it had increased the size of the nozzle to accommodate the relatively large volume of steam, but it still had all that internal surface at the ” Inside the boiler.
The boiler looked down on that little flame in his belly, laughed it, then went out. He ran, ran and ran, and ran without producing much steam. This, of course, solved the problem of excessive speed at the moment. Where there is virtually no steam, there will be virtually no vapor velocity.
But the owner wanted steam. It was, after all, the steam for which he had contracted, did not he?
The entrepreneur began to worry. It seemed so easy.
And then there was the smoke to consider. They began to condense inside the boiler and inside the chimney, because there were so many garbage collectors and so little fire. The entrepreneur knew instinctively that it was not good because it was not a condensing boiler. Well, at that time it was actually, but it was not supposed to be.
He solved the problem by increasing the load. He did this by installing a larger burner, which he now had to explain to the owner, who thought the smaller burner would save him money. The biggest burner, of course, caused an increase in the speed of the steam as it circled in these small pipes.
And then there were the steam traps. The contractor had changed some steam traps from high pressure to low pressure by replacing the seats. What he had not counted, however, was that some of the pitfalls spilled on general returns. He would need a steam pressure to push the condensate up and onto that bump. It needs a 1 psi pressure to lift the condensate every two feet, and it would have to be back pressure when it resizes the traps. The contractor has nothing to do with the calibration of the steam traps; He depended on a local steam trapper for help. It was the representative who had given him bad news about the back pressure. The representative had looked at the pipeline for a moment and then said, “Uh oh”. The contractor disliked it when the representatives declared it.
The contractor also learned from the trap representative that when you lower the pressure difference through a steam trap, the trap usually needs to be bigger to do the job. & Quot; There & # x27; S not as much pushing behind the condensate, & quot; The representative had said. & Quot; Water & # x27; S save. It’s not good. & Quot;
The entrepreneur thought he would have to change the pitfalls. He had not found the price of the new traps when he had quoted the work. But it was too late to come back for a report at that time. He would just have to eat them.
It was then that the contractor called and asked him if there was anything I could suggest to get him out of the whole problem he was. I sat down and listened while he was telling his great adventure, then I told him what he already knew. He was screwed.