JPH0445303A - Supporter of heat exchanger - Google Patents

Abstract

PURPOSE:To prevent anchor bolts from restraining the thermal deformation of a feed water heater as a whole when the heater is deformed into a stoop-shaped by making the distance between a nut in engagement with an end of an anchor bolt and the upper surface of a leg bottom plate equal to or larger than a minimum nut clamp distance which is determined depending on the distance between the legs of a heat exchanger and the temperature in the heat exchanger at that time. CONSTITUTION:A feed water heater is deformed into a stoop-shape such that the upper part thereof is pushed upwardly due to the temperature distribution in the heater when a plant is started up or shut down. When the heater is deformed into an arcuate form, a leg bottom plate 15 of a slide leg 12 is elevated from the surface of a foundation concrete 16 by a distance C. Therefore, if a nut 14 is fixed in such a manner that the clearance between the nut 14 of an anchor bolt 13 and a washer 17 is made equal or larger than the dimension C, the plate 15 is not restrained by the nut 14 from being elevated and hence excessive thermal stress is not produced in a slide leg 12 or in the area where the leg 12 is fixed to the body of the heater. Further, the fracture of the foundation concrete 16 caused by the tensile force of the bolt 13 can be avoided.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) (Prior Art) A feedwater heater heats condensed water condensed in a condenser using turbine oil gas in order to improve the thermal efficiency of a power generation plant. , a heat exchanger for supplying water to boilers and nuclear reactors.

Figure 5 shows the structure of a conventional feed water heater and its foundation. Figure 5 is an example of a high-pressure feed water heater that heats feed water using turbine extraction air with a higher degree of superheating. Explain the basic functions of a heater.

The steam extracted from the turbine flows into the superheat return section 2 through the heating steam population 1, where the temperature of the superheated steam is reduced to the saturation temperature of the internal pressure of the feed water heater, and then flows into the condensation section 3. . On the other hand, the water supplied to the boiler flows from the water supply 4 into the water chamber 5, passes through a large number of heat transfer tubes 6, returns to the water chamber 5, and is discharged.

During this time, the boiler feed water is heated by the turbine oil air, and the turbine oil air from which heat has been removed is cooled by the lower temperature boiler feed water and condenses to become the drain 7.

The condensed drain 7 accumulates at the bottom of the feed water heater, and its water level is always controlled to be constant. This drain flows into the drain cooling section 8, and after being supercooled to below the saturation temperature inside the vessel,
It flows out of the container from the drain outlet 9. In addition, most of the turbine oil gas is cooled and condensed in the condensing section 3 and becomes drain, but some non-condensable gas is discharged from the vent lO to the deaerator (not shown) and the condenser (not shown). Ru.

Since feed water heaters handle high-temperature fluids in this way, the method of fixing the equipment to the foundation needs to be structured in such a way that sufficient consideration is given to thermal expansion of the equipment. In the example shown in FIG. 5, the leg attached to the water chamber 5 is used as a fixed leg 11, and the leg attached on the side opposite to the ice chamber 5 is used as a sliding leg 1z, so that thermal expansion of the feed water heater is released. That is, while the foundation bolts between the fixed legs 11 completely fix the equipment and the foundation, the nuts 14 on the foundation bolts 13 on the sliding leg 12 side are not completely tightened as shown in FIG. First, the sliding legs 12 are fixed with some clearance between them and the leg bottom plate 15. Further, in order to assist the heat transfer of the sliding legs 12, the bolt holes of the foundation bolts 13 are formed in the leg bottom plate 15 as long oval holes in the heat transfer direction. This allows the sliding leg 12 to thermally expand in the direction of the arrow in FIG.

(Problems to be Solved by the Invention) However, the above-mentioned conventional techniques may not be able to cope with the thermal deformation peculiar to the feed water heater as described below.

That is, before the plant is started, drain, which is normally at a low temperature, is collected in the feedwater heater, and when the plant is started, turbine oil flows into the drain, and the upper surface side of the main body of the feedwater heater is heated. Therefore, a temperature difference occurs between the upper surface and the lower surface of the feed water heater main body, and the entire feed water heater deforms into a hunched shape. This deformation state is shown in FIG. 7(a). This arching deformation continues even when the load on the plant is increasing, and the tendency to hunch back is further exacerbated when the turbine suddenly stops due to plant load interruption or the like. This is because, when the turbine is stopped, the oil check valve is closed, the drain outlet regulating valve is closed, and steam and drain are confined within the feedwater heater body. The steam in the vessel then exits through the vent seat and is discharged to the deaerator in the case of high pressure feedwater heaters and to the condenser in the case of low pressure feedwater heaters. Along with this, the pressure inside the vessel also decreases, and the metal temperature of the main body of the feedwater heater also begins to cool down from the steam temperature at rated operation. In this cooling process, heat transfer due to natural convection of steam is inferior to heat transfer through condensate, and in the process of cooling condensate, there is agitating flow due to the flash phenomenon when the condensate pressure drops. The upper side of the feed water heater is less likely to be cooled, and the lower side in contact with the drain is more likely to be cooled. This causes the feed water heater to become hunched over, similar to the temperature distribution state at plant start-up.

When this hunched back deformation occurs in the conventional water heater, as shown in Figure 7(b), the foundation bolts 1
Since the clearance between the nut 14 of No. 3 and the leg bottom plate 15 of the sliding leg 12 is small, the foundation bolt 13 restrains thermal deformation of the entire feed water heater, which not only generates a very large thermal stress on the foundation bolt 13. , there is a high risk of damage to the sliding leg 12 itself and damage to the foundation concrete 16;
The restraint caused by the hunched back deformation caused by the nut 14 of the foundation bolt 13 restrains the original axial thermal expansion of the feed water heater, and the reaction force of this restraint is also applied to the fixed leg 11 side, so that the fixed leg 1
1 damage, foundation bolt 13 deformation, foundation concrete 1
Damage to the foundation concrete 16 or fixed legs 11 of this feed water heater, which has a high risk of causing damage in item 6, is damage to the foundation of the equipment, and not only is it extremely difficult to repair, but it also affects the equipment itself. there is a possibility.

SUMMARY OF THE INVENTION An object of the present invention is to provide a foundation bolt for a feed water heater that does not have the risk of restricting the thermal deformation of the entire feed water heater when the feed water heater is deformed in a hunched position.

[Structure of the invention]

↓4 The other end of the foundation bolt buried in the foundation concrete is loosely fitted and engaged with the leg of the heat exchanger placed on the top surface of the foundation concrete via the leg bottom plate, and the heat exchanger is heated by thermal expansion. When the legs are displaced horizontally, the heat exchanger is supported while sliding on the top surface of the leg bottom plate, and the distance between the nut fitted to the other end of the foundation bolt and the top surface of the leg bottom plate. The nut is fixed at a minimum nut tightening interval determined from the distance between the legs of the heat exchanger and the internal temperature of the heat exchanger at that time.

(Function) According to the present invention, the thermal deformation of the feed water heater can be performed without being restrained by the nuts of the foundation bolts, and the thermal stress due to thermal deformation is not applied to the foundation bolts, foundation concrete, and legs. Breakage and damage can be prevented, and the plant can be started and stopped safely.

(Example) A typical embodiment of the present invention will be described with reference to FIG.

The feed water heater is installed on a foundation concrete 16 or a foundation frame using fixed legs 11 and sliding legs 12. The sliding legs 12 are connected to the foundation concrete 16 by foundation bolts 13.
The nut 14 is connected to the leg bottom plate 15 of the sliding leg 12.
The upper surface of the upper washer 17 is fixed with a clearance D. The nuts are usually fixed using a double nut as shown in this figure or by welding to prevent rotation.

The clearance D is assumed to be greater than or equal to the expected lifting amount C of the leg bottom plate 15 due to thermal expansion and hunched back deformation when the feed water heater in Fig. ε is started and stopped.

Here, the minimum nut tightening that does not restrict the lifting of the sliding leg due to hunched back deformation is the clearance between the fixed leg and the sliding leg, and the internal clearance when the feed water heater is operated at the rated load. It can be determined from Figure 2 depending on the temperature. In FIG. 2, the distance between the legs is plotted on the horizontal axis, and the amount of sliding leg nut tightening is plotted on the vertical axis, with the spacing S being determined using the internal temperature of the water heater as a parameter.

Next, the function of the foundation bolt according to the present invention will be explained using FIG.

As mentioned above, the feedwater heater undergoes a hunched deformation in which the upper part of the main body rises due to the temperature distribution inside the main body of the feedwater heater when the plant is started or stopped. At this time, as the main body of the feed water heater deforms into a bow, the leg bottom plate 15 on the sliding leg 12 side also rises by C from the upper surface of the foundation concrete 16.As in the present invention, the nut 14 of the foundation bolt 13 and the washer 17 If the nut 14 is fixed with a clearance greater than or equal to this C dimension, the lifting of the leg bottom plate 15 will be the same as the nut 1.
4, the sliding leg 12 and the sliding leg 1
Excessive thermal stress will no longer be generated at the attachment portion between 2 and the main body.

Furthermore, there is no risk of damage to the foundation concrete 16 due to the tension of the foundation bolts 13. Since the sliding leg 12 is no longer constrained in the vertical direction in this manner, thermal expansion in the axial direction of the water heater can be carried out smoothly, and the reaction force applied to the fixed leg 11 side is also reduced.

FIG. 4 shows another embodiment of the invention.

Fig. 4 shows that the clearance D of the nuts 14 of the foundation bolts 13 is made equal to or greater than the amount of thermal deformation C, and at the same time, the corners of the leg bottom plates 15 of the sliding legs 12 in contact with the foundation concrete 16 on the return water chamber side are rounded. The effect of this embodiment is that when the feed water heater thermally expands in the axial direction while deforming its back when the plant is started or stopped, the corner of the leg bottom plate 15 in contact with the foundation concrete 16 is By changing the shape from an acute angle to a rounded shape, thermal expansion in the axial direction can be performed more smoothly.

〔Effect of the invention〕

As explained above, the present invention determines the distance between the nut fitted to the other end of the foundation bolt and the top surface of the leg bottom plate based on the distance between the legs of the heat exchanger and the internal temperature of the heat exchanger at that time. Since the nuts were fixed at the minimum nut tightening interval or more,
Under any operating condition of the feedwater heater, the feedwater heater will thermally expand and deform without restraint, causing excessive thermal stress to the fixed legs, sliding legs, foundation bolts, and foundation concrete.

It can prevent damage or damage.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a support device for a heat exchanger according to the present invention, and FIG. 2 is a graph defining the minimum distance between the nut of the foundation bolt and the leg bottom plate of the feed water heater according to the present invention.
3(a) and 3(b) are explanatory diagrams of the operation of the support device according to the present invention, FIG. 4 is a configuration diagram showing another embodiment of the present invention, and FIG.
The figure is a sectional view showing a feed water heater according to the prior art, FIG. 6 is a configuration diagram showing a support device according to the prior art, and FIG. 7 (a)
(b) is an action explanatory diagram showing the deformation of the feed water heater into a hunched back shape and the behavior of the support device portion. 11... Fixed leg 12... Sliding leg 13.
... Foundation bolt 14 ... Nut 15 ... Leg bottom plate 16 ... Foundation concrete agent
Patent Attorney Rules Noriyuki Chika Diagram Diagram (0-n Diagram Diagram

Claims (1)

[Claims] The other end of the foundation bolt buried in the foundation concrete is loosely fitted and engaged with the leg of the heat exchanger placed on the top surface of the foundation concrete via the leg bottom plate, and the leg of the heat exchanger is loosened by thermal expansion. The heat exchanger is supported by sliding on the upper surface of the leg bottom plate when the base bolt is displaced horizontally, and the nut fitted to the other end of the foundation bolt and the upper surface of the leg bottom plate. A support for a heat exchanger, characterized in that the nut is fixed so that the interval between the legs of the heat exchanger is equal to or greater than the minimum nut tightening interval determined from the distance between the legs of the heat exchanger and the internal temperature of the heat exchanger at that time. Device.