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Sr . Name Application
1 Oil cooler Turbine, transformers, compressor, d.g set, hydraulic system, etc. .
2 Radiator (air cooler) Alternators, generators, motors, dg set, etc
3 Reboilers, chillers, condensor, ss & ms tanks Distillery, chemical plants, a/c plant, etc. .
4 Transient heater Centrifugal mahines (to heat c-massecute).
5 Super heated wash water system Centrifugal mahines (to wash the sugar).
6 Centrifugal blower Sugar hopper & others.
7 Inter / after coolers Air compressors (to cool the temperature of air).
8 Water / oil coolers Diesel geneartor (to cool water & oil).
9 L.p heater tube nest 210 mw bhel t.g. set for thermal power station.
10 S.S. Expansion bellow Turbine / steam line.
11 Tank assembly Transformer tank.
Type manufactured : Shell & tube type, finned tube type, double pipe type, “U” bend type, spiral finned tube type radiators.
SERVICES :
The Heat Exchanger are used for some of the following application.Oil Coolers :
For cooling the lubricating and governing oil of Gear Transmission, Centrifugal Generators, Compressors, Transformers, steam and Gas Turbine, Hydraulic Systems and other machines.
Inter coolers and After Coolers :
For cooling Air from Compressors and blowers.
Process Water Cooler :
For cooling closed circuit DM Water Distilled Water in Induction Furnaces/Cubicles For cooling Engine jacket water in Stationery & Marine Diesel Engines.
Condensers :
For condensing steam and other process vapors.
Chillers/Vaporizers :
Chilling liquids by Refrigerants. Heaters for Oil, Water, Air and Process fluids Normally soft water is employed as the cooling medium, through the Coolers, the Process Fluid being cooled passes, in counter flow a number of times back and forward across the Tube Bundle. In case of Heaters, Steam or hot oil is used as the heating medium.
 The main components of a Heat Exchanger are.
• A shell with fluid Inlet and outlet connections, drain, vent and supports Tube Bundle within the shell, with tube-sheets, tubes and baffle plates, tie rods and spacers.
• End covers with inlet and outlet connections.
The Tubes are roller expanded/welded into the tubesheets at both ends.
As mentioned above, the shell side/tube side fluid circuits are separately sealed.
A leak in the seal is always apparent by a rise or drop in pressure in one of the fluids. If contamination does occur, it indicates a defective tube or a tube expansion which is not tight, or leakage from the packed joint in a floating head construction.
The end covers are fitted to the shell assembly by means of bolts and nuts and gaskets.
 
Operating Pressures
The Heat Exchangers are tested on shell and Tube sides at the pressure indicated on the name plate. The operating pressure should not exceed 70% of these values.
Installation
• The Heat Exchangers are delivered from the factory ready for operation. It is nevertheless advisable, before installing them to look in at the connections to see whether they have become dirty. If necessary, it must be cleaned using compressed air, or low pressure steam.
• The Heat Exchanger can be mounted horizontally or vertically, depending on the preference specified at the time of ordering.
• It is extremely important to install the Heat Exchanger so that the force, especially vibrational, exerted upon them are at a minimum. Force acting upon the Heat Exchanger may cause leaks or even tube failure. Heavy pipe connections should be properly supported and their weights should not be allowed to be taken up by the Heat Exchanger.
• The erection personnel should check all Heat Exchanger Installations for compliance with design and for correct executions and good accessibility of the air vent, drain and thermometer connections.
Operation & Maintenance
• The Heat Exchanger should be fitted up on the shell and tube sides and the air should be vented off after the Heat Exchanger is full of the liquid flowing through it. For this the appropriate plugs should be opened and closed again, as soon as the liquids flow out. Similarly, appropriate plugs must be opened to drain the Heat Exchanger. Refer to the performance Data Sheet to check the fluid that should be passed through the tubes and on the shell side.
Starting up with cold process fluid : 
Do not open the water valve until the process fluid temperature of about 300 to 400 is reached.
Starting up with warm process fluid :
The circulation of cooling water must be established before hand or simultaneously. Where valves are fitted on both inlet and outlet connections, only the outlet valve should be used to adjust the circulating water quantity. The inlet valve should be kept fully opened. The process fluid and water quantities should be adjusted in accordance with the valves specified in the performance data sheet pertaining to the particular Heat Exchanger. The value positions obtained by trial should be marked for operating guidance.
Important :
Clean treated water should be used as the coolant in the Heat Exchanger. Otherwise scale and dirt deposits on the Heat Exchanger tubes will result in lost efficiency. The minimum quality of water should be as indicated in annexure 1.
It is generally not permissible to employ too large or too small a water quantity than that specified i.e to operate on too small or too large a water temperature rise. The former, on account of excessively high water speed may increase the rate of corrosion and errosion. The latter gives an unduly low water velocity with an increased tendency to fouling & deposit sedimentation.
 Due to continuous operation for a long time, the Heat Exchanger become dirty especially on the water side. This is indicated by a rise in the temperature of process fluid, beyond the specified temperatures. An inspection, and if necessary, water side cleaning of the Heat Exchanger should be carried out before the process fluid temperature reaches the limiting valve. The nature and degree of the fouling depends primarily upon the quality of the circulating cooling water, which can be determined only by experience and by observation of the process fluid temperature during an extended period of operation.
It is advisable to order out thermometers and pressure gauges for emperatures and pressure measurements at inlet and outlet position of both fluids. The thermometers should be fitted in the pipes where they are accessible, ready visible and protected from radiation and other influences, at least 1 meter distance from the Heat Exchanger shell and the end covers may be used as measuring points in the absence of any better possibility.
If during operation, it is found that the Heat Exchanger on longer gives the design process fluid outlet temperature when the process fluid inlet and the cooling water inlet temperature are at the design level then :
1)  Examine the cooling water pump to ensure that it is delivering the specified quantity of cooling water. It is preferable to have a flow indicator in this line.
2) An increase in the pressure drop of cooling water flow in the Heat Exchanger compared with established initial condition for the same rate of flow, would indicate that scaling might exist and that descaling is necessary.
3) If examination (1) and (2) do not divulge any cause for failure to attain the design capacity, check the tubes for any leakage ue to deterioration of tubes.
This can be done as follows :
• Empty the Heat Exchanger.
• Fill up only the shell side with water and pressure it to 125 psig.
• Remove one of the end covers so that the tube ends are visible.
• Leaky tubes can be detected by water trickling out through them.Alternatively, low pressure  air can be used instead of water. Soap bubbles can be seen at the leaky tube ends, when soap solution is applied.
Cleaning :
Waterside : One of the following methods can be adopted.
1) Mechanical Cleaning.
Special metallic brushes could be effectively used for removal of Scales from inside the tubes, followed by rinse with clean water.
2) Chemical Cleaning.
• Make a 3% solution of Hydrochloric acid or an organic acid in water.
• Circulate the solution through the Heat Exchanger for sometime.
• Drain off the solution and rinse with clean water.
• The Heat Exchanger is now ready for efficient service.
• The Heat Exchanger should be cleaned regularly to prevent excessive fouling.The length of time required for soaking and for soaking and for re-circulating is dependent on the condition of the Heat Exchanger and may vary.
Oil Side :
Under normal conditions of operation, depending on the Quality of oil employed it is necessary to clean the Heat Exchanger on the oil side, only if it is found, during an overhaul, that the entire oil system has become excessively dirty.
• Drain the Heat Exchanger on the Oil as well as water side.
• Remove the end covers.
• Remove the packing and rings and pull out the tube bundle from the stationary tube
plate end.
• Inspect and if necessary clean them.
Mere washing does not remove sludge and oil film properly. The fouling should be softened by allowing a solvent to take effect for several hours. Drain off the solution and clean with water, Hot air or low pressure steam. Finally circulate oil to remove traces of moisture.
 
Replacements .
The internal condition of the Heat Exchanger especially the tubes, tubeplates, rubber rings, gaskets & end covers, can be determine at each maintenance operation. It is not advisable to employ used and possibly deformed jointing a second time. The gaskets, O-rings and tubes should be kept in stock.
Failures.
There is always the possibility of failure of a tube and it should be plugged, after proper detection, by means of a 1:20 conical plug of wood, rubber or metal. Refrain from driving the plug in unnecessarily hard, to avoid damage to neighbouring expanded seats. These simple measures allow the Heat Exchanger to run to normalcy, without any further hindrance to operation. The reduction of cooling effect resulting from the loss of a single tube is negligible. It is, however necessary to ascertain the condition of the other tubes, as fully as possible in the event of failure of tube. If for example, a corrosion failure has taken place, it is probable, in view of the homogeneity of tube material which today prevails, that all the tubes are in danger or already affected. If this situation is found, it is necessary to take steps to ensure that a spare tube bundle is on hand when it is required. As a good maintenance practice, the following spares should be kept in stock :
• 20% of total number of tubes in cut lengths.
• 4 sets of gaskets for all joints.
• 4 number Synthetic rubber, O rings or Asbestos ropes for the floating head joint
( if applicable).
• 4 sets of each size of nuts and bolts.
• Tube plugs for 20% of total tube holes.
• A spare tube bundle for immediate replacement. :
• 20% of total number of tubes in cut lengths.
• 4 sets of gaskets for all joints.
• 4 number Synthetic rubber, O rings or Asbestos ropes for the floating head joint
( if applicable).
• 4 sets of each size of nuts and bolts.
• Tube plugs for 20% of total tube holes.
• A spare tube bundle for immediate replacement. :
Maintenance Tools And Repairs.
The following is a list of special tools required for the proper maintenance and repair of the Heat Exchangers.
• Collapsing tool.
• External tube cutting tool.
• Tube puller.
• Drifter.
• Plug Puller.
• Wrenches.
• Tube Expander.
• Metallic Brushes.
Maintenance of Heat Exchanger consists principally in keeping the Heat Exchanger surface free of deposit. An increase in the pressure drop through the Heat Exchanger and in increase in the outlet temperature are indicator of fouling. By recording the initial ‘clean’operating conditions, a departure from these will indicate need for corrective action.
If at any time it becomes necessary to replace any tube, proceed as follows :
• Remove the end covers and expose the tube sheet on both sides.
• Collapse the tube ends using the collapsing tool and pull out the defective tube with the tube puller.
• Insert the new tube through the tube sheet and baffle assembly, allowing the end of the tube to extend beyond the face of the tube sheet by about 1/16”.
• With the free end of the tube securely held to prevent movement, roll the tube end into the tube sheet with the expander and mandrel.
• Test for leakage by applying a hydraulic pressure of 125 psig on the shell side.
Important Note
When ordering parts for this Heat Exchanger, be sure to state the serial number which is on the Heat Exchanger name plate. This will fully identify the items in our records and ensure the furnishing of proper parts.

Annexture – 1

Recommended Analysis Of Cooling Water All Figures Expressed In Parts Per Million.

Total Solids

95

Dissolved Solids

90

Silica as CaCo3

26.8 x 0.835 = 22.4

Iron as Fe

0.13

Calcium as Ca

11.2

Magnesium as Mg

3.5 x 4.12 (14.35 as CaCo3)

Sodium Na

11.2

Sulphate as CaCo3

2.1 x 1.04 (2.39 as CaCo3)

Hardness Temporary

43.00

Hardness Permanent

-

Alkalinity to Methyl Orange

54

Colour (A.P.H.A.) Units

10

Turbidity (Max During Mansoon)

25

pH

7.7


 

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