Boiler Auxiliaries

While the boiler is operating under normal conditions, observe the operation of all boiler auxiliaries for any defects that may prevent proper functioning of the boiler or indicate a lack of proper maintenance of auxiliary equipment. The unnecessary use of multiple auxiliaries or the use of a large auxiliary during a light-load period (when a smaller auxiliary could be substituted) should be discouraged. The maximum use of steam-driven auxiliaries short of atmospheric exhaust should be encouraged. Steam leaks, wastage to atmosphere, and so forth, should be called to the attention of operating personnel. Particular attention should be given to deaerator venting practice. Venting should be held to the minimum required to preclude oxygen entrainment in the feedwater.

When intermittently operating condensate pumps are used, look for any tendency toward creation of a vacuum when a pump starts. If this happens, recommend installation of a small, continuously operating, float-throttled, condensate pump (in parallel with intermittently operating pumps) to assure a condensate flow at all times. If there are a number of intermittently operating condensate pumps, it may be possible to convert one of them (if of small enough capacity) to continuous throttled operation.

PLANT OPERATION

To operate boilers or be a plant supervisor, you need to know all the mechanical details of the boiler you are operating and its associated auxiliaries. However, just knowing this information is not enough. To be a professional boiler operator or plant supervisor, you must develop a keen eye for trouble, a finely tuned ear, and an overall sense of awareness concerning boiler plant operation at all times.

As an operator and/or supervisor of a boiler plant, you must learn to tell the difference between normal and abnormal operating conditions. By training yourself to notice and analyze strange noises, unusual vibrations, abnormal temperatures and pressures, and other indications of trouble, you will be better able to prevent any impending trouble or casualty to the plant.

OPERATORS

Boiler plant operators must maintain accurate records. Logs provide a means of recording continuous data on boiler plant performance and analysis of operation. Logs are arranged for use over a 24-hour period, consisting of three 8-hour shifts. Log entries should be carefully made in columns.

Logs

supplied with fuel. It is kept at a value that has

Information of importance in the operation of boilers must be recorded. This section provides information concerning the type of data that should be recorded in logs.

1. Steam pressures. Steam pressure is recorded by the operator from steam gauges and shows performance of automatic or 'manual control.

2. Steam flow. Actual output of the plant is recorded by the operator in pounds per hour to obtain steam flow. This record determines the number of boilers to operate for greatest efficiency.

3. Feedwater heater. Feedwater-heater pressure indicates whether proper deaerating temperature can be maintained in the heater. Feedwater-heater temperature shows the effectiveness of the feedwater heater. A drop in steam supply pressure or insufficient venting may cause low heater temperature.

4. Feed-pump pressure. Feed-pump pressure indicates effectiveness of the boiler feed pumps. If feedwater supply fails, the pressure reading enables the operator to determine whether or not the difficulty is in the feed pumps. The pumps are defective when the feed-pump pressure reading is below normal.

5. Forced draft. Forced draft is an indication of thickness of the fuel bed. The most satisfactory value varies with different installations and fuels and is determined by actual trial.

6. Furnace draft. Furnace draft, when used in connection with forced draft, should be slightly less than atmospheric pressure to prevent smoke from leaking into the boiler room and overheating the furnace lining. If only an induced or natural draft is used, furnace draft must be sufficient to cause the quantity of air required for combustion to flow into the furnace. Operating with a furnace draft higher than actually required results in excessive air leakage into the setting with an accompanying loss in efficiency.

7. Last-pass draft. Last-pass draft shows actual draft produced by a stack or an induceddraft fan. Fireman should become familiar with last-pass draft at various ratings when the boiler is operating satisfactorily. A decrease in last-pass draft with-other conditions constant indicates leaking baffles. An increase in last-pass draft shows that gas passes are becoming clogged.

8. Percent CO2 flue gas. Percent CO2 flue gas is a measure of relative quantities of air been established as most satisfactory for the plant, fuel, rating, and like factors. In plants not equipped with CO2 recording meters, this value is determined with a hand gas analyzer. With experience, you can determine the correct amount of air supplied for a furnace by checking the draft gauges and from personal observation. In all cases, you should check values by use of a hand gas analyzer.

9. Flue-gas temperature. Flue-gas temperature is an indication "of the portion of heat "leaving the boiler with the flue gases. This heat represents a direct energy loss in fuel. Abnormally high flue-gas temperatures at a given boiler rating are caused by dirty heating surfaces or leakage of baffles. If the heating surface has a coating of soot and ash, heat that cannot escape is discharged to the stack. Leakage through baffles allows the gases to take a shorter path than intended and reduces contact of gases with the entire heating surface. Excessive fouling of the boiler's firesides increases the draft loss while leaking baffles decreases the draft loss. Either condition raises the temperature of flue gases above normal.

10. Fuel. Always determine the quality of fuel being used as this represents a major operating cost.

a. Pounds of coal. Procedures for determining the quantity of coal burned depends upon the means available. You may use scales that automatically dump weighed quantities of coal into the stoker or pulverizer hoppers. A register indicates the number of "dumps" that, multiplied by the weight of coal discharged per dump, gives the total. Another weighing method uses traveling larries equipped with scales so that the weight of each load can be recorded before it is dumped into the boiler hopper. In the absence of a weighing device, the quantity of coal consumed can be determined by filling and leveling bunkers at given intervals and recording the coal used from the report of coal received during a given interval. Methods for approximating coal burned by counting stoker revolutions are only estimates and are subject to considerable error when the size of coal changes.

b. Cubic feet of gas. The quantity of gas used is indicated on a meter. The readings can be direct or they may necessitate calculation by use of a meter factor.

c. Gallons of oil. Fuel oil quantities are determined by use of a measuring stick. Tables supplied with a given tank are then used to determine quantity from level of fuel. Tanks may also be supplied with gauges that can be read directly.

11. Outside temperature. A heating plant load is greatly influenced by outside temperature. Record this temperature for comparison with steam generated and fuel used. These comparative values are useful in determining abnormal fuel consumption and in estimating future requirements.

12. Makeup water. The quantity of makeup water used should be recorded. This enables the operator to note an abnormal increase in makeup water before a dangerous condition develops. Return all possible condensate to the boiler plant; this will save on water and chemicals being used to treat the water.

13. Water Pressure. Feedwater is most important to the safe operation of the boiler plant. The hot-water supply temperature should be recorded. Insufficiently heated water can cause scaling or deposits in a boiler.

14. Hot-water supply temperature. Record the hot-water supply temperature. Insufficiently heated water can cause scaling or deposits in a boiler.

15. Water softeners. Where softeners are employed, you should keep a meter record to inform the shift operator of the time when the units must be regenerated. A decrease in the time of runs between regeneration is an indicator of either an increase in hardness of incoming water or of deterioration of the softening material. The note columns are for recording total water softened and pounds of salt added.

16. Totals and averages. Space is provided for recording total and average quantities per shift.

17. Steam flow. To find the quantity of steam generated, subtract the steam flowmeter integrator reading at the start of shift from the reading at the end of the shift, then multiply the remainder by the meter constant. Dividing steam generated by fuel burned (pounds of coal, cubic feet of gas, or gallons of oil) yields a quantity that indicates the overall economy obtained. If the plant does not have a steam flowmeter, pumps can be calibrated for flow and a record kept of their operating time, or the condensate and makeup water can be metered.

18. Boiler feed pump in service. A record of the boiler feed pump in service makes it possible to determine appropriate operating hours and to see that the various pumps are used for equal lengths of service.

19. Soot blown time and blowdown. A record of blown time and blowdown is valuable to the relieving shift operator because it is an indicator of plant conditions, and it will show irregularities if any exist.

20. Phosphate, caustic soda, and tannin added. A record of phosphate, caustic soda, and tannin used is valuable in keeping correct boiler water analysis and in determining the total amount of chemicals used.

21. Remarks. The remarks column is in the upper right area of the log sheet. List all the equipment that is to be checked each day according to the schedule listed in TM 5-651. Annotate all the irregularities that are found in connection with these inspections. List the dates when the boilers are drained and washed and at other intervals, as determined by local water conditions. Indicate the degree of internal cleanliness.

22. Using personnel. Names of personnel responsible for these data must be entered in the appropriate area on the bottom of the log sheet.

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