RECIPROCATING AMMONIA FEED PUMP

MAINTENANCE

Author

Prem Baboo

Sr. Manager (Prod)

National Fertilizers Ltd., Vijaipur, India

Following regularly maintenance are required for Ammonia

reciprocating Feed pumps

1. Tandem valve maintenance,

2. Plunger packing maintenance.

3. Crank Case Maintenance

4. Other maintenance

1. PREVENTATIVE MAINTENANCE OF TANDEM VALVES

At least once every four months, check for proper operation by following the

preventative maintenance steps outlined below. These steps can be performed

while the actuator is in service and, in some cases, without interrupting service.

Generally by experience internal passing sound are coming from block means the

“ O” ring to be replaced.

1. Clean and lubricate all internal parts. All O-rings should be replaced and

lubricated using a silicone lubricant. The bore that houses the sliding seal

assembly in the transfer case must be smooth and clean.

2. Reassemble the sliding seal assembly by pushing the base seal into the

transfer case. Place the sliding seal collar on top of the base seal so that the

raised portion of the sliding collar protrudes through the hole in the top

clamp.

3. Replace the top clamp and the spiral snap-ring.

Fig-1 Tandem Valves

Fig.-2., High Pressure Block

2. PLUNGER PACKING REPLACEMENT In a reciprocating pump in which a plunger is slid ably disposed within a

pumping chamber for reciprocating movement therein it is necessary to provide

packing for the plunger to prevent the leakage of liquid out of the pumping

chamber between the plunger and the cylinder wall. It is a common practice to

provide a bore in the head of the pumping chamber for the packing box.

However, with this type of construction it is difficult to replace the worn packing

without removing the plunger from the head of the pumping chamber, especially

if the packing is of the closed ring type.

Reciprocating pumps use various method of packing as their sealing

methodology. For packing to be reliable it must always be in contact with

lubricant such as pump product or an external flash like steam condensate. The

flow for plunger about 120 lit/hr./plunger

Sample of ammonia plunger packing outlet should be done regularly twice in

week.

We are allowed about 12.0 % ammonia in plunger packing outlet analysis

Sample

Plunger packing outlet analysis for ammonia by lab.

Sample Points Ammonia analysis Status

Plunger No. 1 5.0% Ok

Plunger No. 2 7.0% Ok

Plunger no. 3 14.0 % Plunger packing

tightening to be done

About two month plunger packing tightening is required for reducing ammonia

contents in plunger outlet water.

Plunger packing life about 2.0 to 2.5 years depends upon packing quality. We are

using Inmarco packing.

Fig. 3., Packing material Enmarco

Fig. 4., Stuffing box

3. CRANK CASE MAINTENANCE

As you know this device can protect the pump against overload around the shaft The

reason of the overload can be as following items:

1. closing of control valve or hand valve in the discharge of the pump.

2. Suddenly increasing in the synthesis pressure.

No action can take during checking of the overload only the distance between switch

and body of crank shaft must be measure and checked in specific time intervals

Fig.5. Crank case Overload Protection switch

Over load Protection

Grooves

Water in Crankcase Oil

1. Water Condensation.

2. Worn seals.

3. Clogged Air Breather(s).

4. Worn Crankcase Packing.

5. Loose Covers

Oil Leakage from Crankcase

1. Oil Level/Temperature Too High.

2. Worn seals.

3. Worn Crankcase Packing.

4. Loose Crankcase Cover

Excessive Heat in Power End.

1. Pump Running Backward/RPM too low, Insufficient Oil in Power End.

2. Excessive Oil in Power End. Incorrect Oil Viscosity.

3. Operating Pump above Recommended Pressure 6) Main Bearings too Tight.

4. Drive Misaligned.

5. Suction dampener tracing steam closed

6. Pump RPM too Low.

7. Inadequate Ventilation.

8. Liquid end Packing Adjusted too Tight (adjustable style packing only)

4. OTHERS PROBLEMS

Like all other pump designs, reciprocating positive displacement pumps have their

own set of disadvantages with the most common being the pulsations. The

pulsating flow and pressure have specific suction and discharge piping system

requirement to ensure proper pump performance and to protect the piping and

other system components like discharge resonator and suction dampener.

(A) STUD FAILUR

1. Excessive discharge pressure.

2. Improper torqueing of nuts.

3. Shock overload caused by pump cavitations’

(B) EXCESSIVE VALVE NOISE

1. Broken or weak valve spring.

2. Pump cavitations’.

3. Air leak in inlet piping or loose bolts in pump inlet manifold.

4. Air trapped above inlet valve

Noisy Operation (Be sure to differentiate between liquid knock and mechanical knock -

very few knocks are mechanical on new installations.)

1. Piston or plunger loose

2. Valve noise amplified through power end

3. Pump cavitations

4. Liquid knock

5. Air leak in inlet piping

6. Loose bolts in pump inlet manifold

7. Hydraulic noise in liquid end

8. Loose or worn crosshead pins and bushings

9. Loose connecting rod cap bolt

10. Worn connecting rod bearings

11. Worn crosshead

12. Main bearing end play excessive

13. Worn gears

14. Gears out of line

15. Partial loss of prime

16. Shocks in piping system

17. Steam closed in suction dampener tracing.

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