Do you install Gas Generators?

Tim McElwain

Something I came across that might make it easier to size piping to gas generators:



Generator Sizing Software Piping Module

 

A gas piping module, the first in a series of enhance­ments to the Power Design Pro™ software, a genera­tor sizing tool, has been added. The gas piping module is used to determine the required pipe size for gaseous fuel generators by automatically selecting and sizing the appropriate gas piping for a generator. It also al­lows the user to manually select the pipe sizing and calculate the available gas pressure at the unit. The module supports a single Generac generator as well as multiple generators in any Modular Power System (MPS) configuration. The Power Design Pro features includes full harmonic and transient analysis to ensure complete generator-to-Load compatibility; advanced load modeling that uses an expert system approach to model a load's true characteristics and allows users to build their own load types; and load shedding capa­bilities that enable the user to shed loads entered into the program and evaluate the effects of running those loads against any generator configuration selected by the user. The software offers specification sheets, installation drawings, emission information, a specifi­cation text library with full inclusive design notes, and the ability to link directly to supporting dealers for bud­getary quoting and additional support.

<span style="font-size:12pt">Generac Power Systems, S45 W29290 Hwy. 59, Wau­kesha, WI 53189; 888-436-3722 or 262-544-4811; </span>

<span style="font-size:12pt"> </span>

<a href="http://www.generac.com/powerdesignpro">[u][size=12][color=#0000ff]www.generac.com/powerdesignpro[/size][/color][/u]</a><span style="font-size:12pt"> or </span><a href="http://www.generac.com/">[u][size=12][color=#0000ff]www.generac.com[/size][/color][/u]</a><span style="font-size:12pt"> </span>

icesailor

Gas Generators:

Tim,

I hope your software covers the need for LP fuel tanks be large enough to have enough surface area for the gas to boil off so you have enough vapor to run the thing. It can be a real bear in the winter on a large generator.

I know of an application where they had a big boiler and multiple buried tanks. The thing would go off on safety in the coldest months but fire off in the morning. They finally figured out that the tanks had frozen the ground to frost and it spread to all the tanks buried. The ground lost the ability to supply heating BTU's to vaporize the liquid.

I know that you could go liquid but that has its own issues.

I know of generators that had tanks that wouldn't vaporize fast enough in the winter under emergency conditions. They just added more cylinders.

Bummer

Tim McElwain

I have had similar issues

with LP, the answer is to install a vaporizer to vaporize the gas before it gets to the end use equipment. One of the down sides of LP. This is typically the case were there is a large demand for a lot of gas in a very short time. That is exactly what a generator does.



The software will however help installers of piping to generators who have asked here several times about pipe sizing and piping requirements.

Mark Eatherton

I remember HR talking about tank heaters...

Electric band heaters that were used up in Utah to keep the tanks warm enough to insure adequate vapor production. Seems silly to use one energy source (electricity) that cost more than the other source (LP) to insure that the other source stays intact, but I guess a fellas got do what a fells got to do to make sure people stay warm....



ME

icesailor

LPG/LNG gas vaporization:

Here's a story for you that may explain the problem.

About three miles away from where I live is a big gas facility where the service trucks go. You can also get your car filled with CNG if it is so equipped

Less than 1/2 mile from my house, on a winding road is a spot in a curve where there is a big flat spot, next to a hill. There's no brush or anything in this spot. One day, I went by this spot and there were these two big trailers parked there with big hoses laying on the ground. Being ever curious about anything that has a pipe on it, I had to check it out. The hoses all had quick connects on them. They went to a trailer with pumps and things on it that looked like some sort of heat exchangers on them. There were hoses that went to the other trailer that had these huge square things that looked like boilers on it. There was no one around. I kept going by for a few days and finally found someone there so I asked him what it was for.

It seems that the place ( the service center) was a place that the gas company injected vaporized gas to keep the gas pressure up in the system during peak times. That they have these systems all over New England. That the send LNG tankers down to inject the gas. But first, they must "heat" the liquid so it will vaporize. They have redundant pumps so if one goes down, they switch to the other set so they can fix the other one. If the second set of pump/vaporizer goes down and they need to do shut-downs, they must physically go to each service and turn it off before they can turn the gas back on. If no one is home, they can't turn it back on. If the house froze up and was damaged, they are responsible. So, they have this portable back up vaporizing system that they can quick connect to their system and keep the pressure up. If they start to have a problem, they just send a LNG tanker down, connect the hoses and fire and pump away. There were two hot water gas boilers on the truck. One was a back up in case one failed. Each boiler was 12,000,000 BTU's. Pumped to a heat exchanger to extract the cold or inject heat into the liquid gas.

They have these sites all over New England. If they need to maintenance on a system, they bring these two trailers for redundancy. "Just in case."

Heat transfer 101

Tim McElwain

Icesailor

were was that setup located?

TonyS

What issues do you have

with liquid and using heat from the engine to vaporize?

icesailor

LP generators:

If you are asking me that question, I have been told by those who know that it is a PITA if you try to feed it with liquid. The liquyid goes through a scewwn on the way to the vaporizer and I guess it must need heat to help. But, there is an oil in the LP that ends up fouling the screen and the gas flow will slow down over time and decrease the HP and amp output of the generator. When you use vapor only, you need a bigger pipe but you don't need to wory about vaporization. It occurs in the tank (s).

Not a problem with Natural Gas.

TonyS

Interesting

My last welding machine/gererator was a 4 stator Miller Legend with a factory conversion to LP. It was using a finned vaporizer that received its heat from the fan on the air cooled motor. This along with a pressure drop caused vaporization.

Most of the lifts and towmotors we rent for inside work are also liquid fed.

I was following the LP conversion fad for a while until the price of LP didnt make it worthwhile. They also were using liquid feed systems, many with optional gasoline preheat. I never heard of an oil precipitating out of LP. I will ask the mechanic at my rental service about this problem. Thanks