Page 154 - Boiler_Operators_Handbook,_Second_Edition

Special Systems 139

carry them. Ships today can have engines rated at 60,000 to the fuel. Recall what I said about boilers in that a puff
to 80,000 shaft horsepower. Despite their large size their is simply an explosion that didn’t do any damage and
requirements for operation are no different than small is very strong warning that a more extensive explosion
engines. could follow. Normally the blow by consists principally
Environmental regulations developed under EPA’s of the products of combustion so the crankcase should
Tier 4 requirements have changed the procedures for contain a reasonably inert gas.
operating engines. Those requirements apply to all land Of the two types of engines diesels are the most
based equipment whether stationary or mobile. Some common in boiler plants. Occasionally you might be
of you are bound to be familiar with requirements for called upon to operate a gasoline engine that introduces
adding DEF (diesel exhaust fluid) into a separate reser- additional concerns. I’m sure you’ve been told that you
voir of your diesel engine powered pickup truck. New should not store gasoline in your house or attached ga-
emergency generators and stationary diesel engines rage. Some of you may have a hot water heater in your
will also have that requirement. They will be fitted with garage but noted that it is installed on a platform. All this
CDPFs (catalyzed diesel particulate filters) that capture is because gasoline evaporates at normal atmospheric
the engine’s particulate emissions, which are principally temperatures and the vapor is heavier than air so if gaso-
unburned hydrocarbons, then burn off the carbon while line vapors leak from a storage container, or your auto-
simultaneously reacting to break down nitrogen oxides mobile, and mix with the air in the space it will produce
using a catalyst alone or the DEF. To achieve the emis- a combustible mixture and the mixture will gravitate to
sion limits now established engines will also have control the lowest space in your garage. The solutions to these
features added to augment PCV and EGR valves. Because problems in your home consist of elevating the hot water
the implementation of Tier 4 regulations are progress- heater and not storing gasoline inside even if it’s in an
ing as I work on this edition I can’t tell you about all the approved container. When it’s necessary for the use of
modifications to normal engines that will become normal portable gasoline engines in a boiler plant it’s not always
in the coming years. Once again, read your instruction possible to keep the engine outdoors. It is, however, nor-
manual. mally possible to take the engine powered equipment
It’s not necessary to describe putting an engine driv- outside for filling and starting. During normal operation
en generator online or disconnecting it from the line be- when gasoline is drawn from the tank a small orifice in
cause the operation is basically the same as it is for steam the top of the tank admits air and no gasoline vapor is
turbine powered generators. The only concern with an emitted from the tank. Operation of an engine inside
engine is that operators and automatic controls can con- a building without providing additional openings for
nect an engine driven generator before it’s warmed up ventilation may result in that engine running fuel rich so
and some instability will result in fluctuating frequency it’s exhaust is discharging gasoline vapor into the build-
and voltage. Except for actual emergency operation it’s ing. Make sure you have adequate ventilation for those
advisable to allow the engine to idle for a period of time engines and whenever possible means to discharge the
so it reaches normal operating temperatures before put- exhaust outdoors.
ting it online. Procedures for starting an engine should always
Engines can be used to power pumps, fans, blowers, include checking the lubricating oil level first. Before you
and any number of pieces of mechanical equipment asso- argue with me about checking it every time before start-
ciated with a boiler plant in addition to the more common ing keep in mind that someone else could have decided
emergency generator. Engines have hazards associated to change the oil, drained it, and failed to get around
with them that make them almost as dangerous as a boil- to refilling the engine. Yes, that’s happened thousands
er. Blow by, which is the term used to describe the leakage of times. When lead acid batteries are used to power a
of a fuel air mixture in an engine cylinder past the piston starter for the engine it’s also a good procedure to check
rings and into the crankcase, combined with the aerosol the battery water level as well. The typical emergency
produced by the mechanical agitation of the lubricating generator has radiator cooling and the level of the cool-
oil can be counted on to produce a combustible, hence ant in the radiator needs to be checked, otherwise the
explosive, mixture in the crankcase. Those spring loaded cooling systems for the engine must be in operation be-
covers over the access openings for the crankcase have fore starting. Then, whenever possible after starting the
the dual purpose of first relieving “puffs” then immedi- engine, wait for it to warm up before connecting to the
ately closing to prevent the admission of air which could load. Closely monitor cooling water and lubricating oil
produce a larger puff or a true explosion as air is added temperatures after connecting to the load to ensure they