Claims:WE CLAIM:
1. A tube bundle insertion fixture for shell and tube type heat exchangers comprising:
a bundle support rest assembly;
a shell support assembly; and
a tube sheet support characterized in that
a tube bundle is stationary and kept in horizontal position;
a shell is clamped on said shell support assembly and is aligned with said tube bundle.

2. The tube bundle insertion fixture as claimed in claim 1, wherein said bundle support rest assembly comprises: a support rib plate (1);
A Support pipe (2);
An Eccentric shaft (3);
A Top plate (4); and
A Hinge assembly (5).

3. The tube bundle insertion fixture as claimed in claim 1, wherein said shell support assembly comprises: A Frame (6);
Wheel assemblies (7);
an End support for shell (8);
Profile ribs (9);
a Clamping lug (10); and
a Pulling lug (11).

4. The tube bundle insertion fixture as claimed in claim 1, wherein said shell support assembly comprises: A Base plate (12);
A Support Frame (13);
Shafts (14);
Pulleys (15); and
Ribs (16).

5. The tube bundle insertion fixture as claimed in claim 1, wherein said fixture, supported on trolley wheels, is pulled slowly on to said tube bundle by means of pulley and sling mechanism which is clamped on tube sheet side of tube bundle.

6. The tube bundle insertion fixture as claimed in claim 1, wherein said bundle support rest assembly is made of carbon steel plates, pipes and rods and assembled by welding.

7. The tube bundle insertion fixture as claimed in claim 1, wherein said shell support assembly is made of carbon steel plates, Stainless steel rounds, and SKF Bearings assembled by Welding and Fastened with carbon steel screws

8. The tube bundle insertion fixture as claimed in claim 1, wherein said tube sheet support is made of carbon steel I-Beams, plates, pipes and rounds and assembled by welding.
, Description:FIELD OF THE INVENTION
The present invention in general relates to the field of heat exchangers. The present invention in particular relates to shell and tube type heat exchangers that contain tube bundles for insertion into the shell.
BACKGROUND OF THE INVENTION
Shell and tube type heat exchanger consists of a shell (a large pressure vessel) and a set of tubes called a tube bundle, and may be composed of several types of tubes which are plain, longitudinally finned, etc. inside it. One fluid runs through the tubes, and another fluid flows over the tubes (through the shell) to transfer heat between the two fluids either from tube side to shell side or vice versa. The fluids can be either liquids or gases on either the shell or the tube side. In order to transfer heat efficiently, a large heat transfer area should be used, leading to the use of many tubes. In large power plants with steam-driven turbines, shell-and tube Heat exchangers used to condense the exhaust steam exiting the turbine into condensate water which is recycled back to be turned into steam in the steam generator.
To improve the thermal efficiency of the power plant feed water heaters are installed in between condenser and steam generator. A feed water heater is a shell and tube type heat exchanger which is used to pre-heat feed water or condensate delivered to a steam generating boiler passing through its tubes by means of steam or condensate on the shell side.
Construction of Feed water Heat exchanger:
The main parts of Feed water heat exchanger is
1. Shell assembly,
2. Tube bundle assembly
3. Water box assembly.
Feed water heaters assembling sequence process involves
1. Inserting the tube bundle into the shell,
2. Water box assembly to "Tube bundle and shell" assembly
Drawback of prior-art:
During manufacturing of feed water heat exchangers the most critical operation is insertion of the tube bundle into the shell. Tube bundle insertion assembly process: shell assembly (15% weight of the feed water heater) is placed in inclined position on the v-block on the floor and horizontal movement at the end is arrested by dead weight. The tube bundle (75% weight of the feed water heater) is lifted by crane with slings in the same inclination and slowly the bundle is inserted in tithe shell by gradual downward and horizontal movement of tube bundle. While bundle insertion sling positions have to be changed to hold the remaining portion of bundle in same inclined position. This operation needs highly skilled slingers and crane operators as sling positions have to be changed while bundle is in hanging position which is not a safe working procedure. The same procedure cannot be used for 800MW and single bank heaters (660 MW) as weight of the bundle is very high which cannot be lifted safely by existing crane capacity.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a method and fixture for safe and easy procedure for tube bundle insertion.
A further objective of the invention is to reduce the cycle time of tube bundle insertion.
Yet another objective of the present invention is to reduce the crane capacity required for insertion of tube bundle.
Yet another objective of the present invention is to increase the productivity of HP Heaters with safety.
SUMMARY OF THE INVENTION
In the invented procedure of tube bundle insertion, tube bundle (75% weight of heater) is stationary and kept in horizontal position. Shell (15 % weight of heater) is clamped on the fixture and which is aligned with tube bundle. Slowly the fixture, supported on trolley wheels, is pulled on to the tube bundle by means of pulley and sling mechanism which clamped on tube sheet side of tube bundle. As compared to old procedure of bundle insertion new procedure has completely eliminated lifting of tube bundle and shell. So it is safe and easy way of tube bundle insertion and this also does not require skilled slingers and crane operators as there is no lifting after clamping of shell to fixture. Cycle time also has significantly reduced compared to earlier method; because once the fixture (supported on trolley wheels) is aligned with the tube bundle it does not take much time to pull the shell on to the bundle. Another implicit cost reduction has been achieved by reduction in cycle time of bundle insertion.
BRIEF DESCRIPTION OF DRAWNGS
The proposed invention will be better understood by the following description with reference to the accompanying drawings:
Figure 1 shows the shell and tube heat exchanger with its parts
Figure 2shows the prior-art method of inserting tube bundle into the shell
Figure 3 discloses support plate rest assembly according to the present invention
Figure 4 discloses shell support assembly according to the present invention
Figure 5 discloses tube sheet support according to the present invention

Figure 6 discloses the method of tube bundle insertion according to the present invention

DETAIL DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
Bundle insertion fixture is composed of three main assemblies:
1. Bundle support rest assembly
2. Shell support assembly
3. Tube sheet support assembly
Bundle support rest assembly:
The main parts of Support plate rest assembly are
1. Support rib plate
2. Support pipe
3. Eccentric shaft
4. Top plate
5. Hinge assembly.
Support plate rest assembly is manufactured as per the Figure-3.
The main function of this assembly is to support the support plates or baffles of HP Heater tube bundle.
Initially while tubing the top plate (4) (pos.4, figure.3) on the support plate rest assembly is in top most position as shown in the figure.
Later during the bundle insertion process the support plates rest has to be removed for bundle to move inside the shell assembly, so the top plate (pos.4, figure.3) on support plate rest is moved down by the eccentric mechanism (pos.3, figure.3) provided on the shaft as shown below and support plate rest assembly is removed for bundle insertion.
Shell support assembly (Fig. 4):
The main parts of Shell Support assembly are
6. Frame
7. Wheel assemblies
8. End support for shell
9. Profile ribs
10. Clamping lug
11. Pulling lug
Frame (6) is fabricated from plates is designed and tested to withstand 300 Tons load. It is rested and clamped to Wheel assemblies (7) which roll directly on the floor. An end support (8) is provided at the rear end of the frame to restrict the shell assembly from sliding back. Shell assembly which rests on the profile ribs (9) are designed to match the shell diameter. Profile ribs are changed when there is change in shell diameter. Pulling lug (11) and Clamping lug (10) are welded to frame for clamping the shell assembly and to pull the trolley while bundle insertion.
Shell support assembly has to take to shell assembly load before bundle insertion and heater assembly load after bundle insertion. Therefore, shell assembly has been designed to take weight of heater assembly. Maximum load carrying capacity of this fixture is 300 tons. Load carry capacity is ensured through analysis and it has successfully passed a practical test for 200 tons load.
Diameters of shell assemblies vary according to megawatt rating, so to use same shell support assembly for varying diameters a replaceable profile ribs matching to the shell diameters are provided.
Tube-sheet support assembly (Fig. 5):
The main parts of Tube sheet support are
12. Base plate
13. Support Frame
14. Shafts
15. Pulleys
16. Ribs
To pull the shell assembly on to tube bundle assembly a fixed support is required. Tube sheet support assembly (figure. 5) acts as a fixed support during bundle insertion. Shell support assembly (figure.4) is pulled with slings rolled over pulleys (15) supported on support frame (13) of tube sheet support assembly.
Bundle insertion is carried out by pulling shell assembly against a fixed support (i.e. tube sheet support assembly figure.5). Instead of limiting bundle insertion to a single workplace by grouting the tube-sheet support assembly to make it a fixed support. It is made movable and at same time it is used as fixed support by resting tube-sheet of heater on the assembly. Tube sheet weight holds the tube sheet support assembly in the fixed position.
Method of insertion: -
Assembly before tube insertion is called skeleton assembly is supported on bundle support assembly figure-3. After ensuring proper alignment of skeleton assembly tubes are inserted in to skeleton assembly. Assembly after tube insertion is called as bundle assembly/tube bundle assembly.
Shell assembly, in to which bundle assembly has to be inserted, is placed on shell support assembly figure-4 and it is aligned in a such way that shell support assembly and bundle support assembly are in straight line.
Tube sheet support assembly figure-5, acts as fixed support during bundle insertion, placed on tube sheet side of bundle assembly.
After ensuring proper alignment of three assemblies i.e. Shell support assembly, bundle support assembly and tube sheet support assembly, slings are hooked to pulling hooks provided on both sides along length of shell support assembly and passed over pulleys in tube support assembly are eventually hooked to lifting hook of the crane.
Slowly slings are brought to tension by raising the lifting hook in vertical direction. Ensure alignment of three assemblies once again and gradually raise the lifting hook up so that shell support assembly is pulled on to bundle support assembly and insertion of bundle assembly in to the shell is completed.
The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the specification, the reference numerals are merely for convenience, and are not to be in any way limiting, the invention may be practiced otherwise than is specifically described.