Method for transforming dipleg expansion joint of boiler return feeder

Abstract

The invention discloses a boiler return feeder dipleg expansion joint transformation method. The original ash smoothing pipe is cut off; the ash smoothing pipe is reserved as a first cylinder body; the metal rib net is used as an internal supporting structure of the second cylinder body; the heat-resistant casting material is hardened and attached to the metal rib net to form a second barrel body at the lower part of the ash smoothing pipe; a heat-resistant pouring material of the second barrel ensures the service life of the second barrel, and an asbestos cushion layer between the second barrel and the ash guide pipe realizes heat-preservation sealing; the ash smoothing pipe is made of light heat insulation pouring materials, the inner diameter size is guaranteed, the sealing and heat insulation effects are achieved, normal operation of a material returning system is guaranteed, and the dipleg compensator with the replaced materials is more economical and more durable.

Description

Technical Field

[0001] The invention relates to the field of boiler slagging, and in particular to a method for modifying a boiler return leg expansion joint. Background Art

[0002] The circulating fluidized bed boiler is a low-pollution, environmentally friendly, clean-burning boiler that uses an in-furnace combustion desulfurization process. Through low-temperature combustion in the circulating fluidized bed, sulfides and nitrogen oxides are effectively removed, thereby greatly reducing the content of pollutants in the flue gas. Due to the energy-saving and environmentally friendly characteristics of the circulating fluidized bed, it has become increasingly popular among users in recent years. With the update of technology, the current development trend of circulating fluidized bed boilers is large-scale. The large-scale development of circulating fluidized beds directly leads to a significant increase in the amount of slag discharged from the boiler.

[0003] The expansion joint of the original return feeder of the boiler is a metal structure, with a double-layer retractable high-temperature resistant metal steel plate inside. The ash pipe is inside and the ash guide pipe is outside, and the two slide and expand relative to each other. After long-term operation, the steel plate of the internal ash pipe is burned and falls off, and the sealing cannot be guaranteed, which affects the return effect. Even after the ash pipe is replaced, it still opens and falls off. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of short service life and easy failure of the ash pipe by improving the technology of the expansion joint of the return feeder leg. A method for modifying the expansion joint of the return feeder leg of a boiler is proposed.

[0005] A method for modifying a boiler return feeder leg expansion joint; the expansion joint comprises an ash pipe and an ash guide pipe; the method steps are as follows:

[0006] 1) When the boiler is shut down and in cold state, cut off the original ash pipe and keep the ash pipe as the first cylinder;

[0007] 2) Welding the flange welding end along the ash pipe; the upper surface of the flange welding end is welded to the lower end of the first cylinder;

[0008] 3) Lay a thermal insulation sealing layer inside the ash guide pipe;

[0009] 4) Prepare the metal rib mesh and weld it for positioning; the upper end of the metal rib mesh is connected to the lower surface of the flange welding end of the ash pipe by welding, and after welding and positioning, it is rolled into a cylinder to serve as the internal support structure of the second cylinder;

[0010] 5) Arrange the mold box and pour the heat-resistant profiles; Arrange the mold box inside the metal rib mesh, and fill the pouring space with heat-resistant pouring materials from the upper edge of the ash guide pipe;

[0011] 6) After the hardening time, the heat-resistant casting material hardens and adheres to the metal rib net to form the second cylinder under the ash pipe;

[0012] 7) When the boiler starts the thermal engine and switches from a cold state to a hot state, the heat-resistant casting material of the second cylinder ensures its service life, and the asbestos cushion layer between the second cylinder and the ash guide pipe realizes thermal insulation and sealing.

[0013] The beneficial effects of the present invention are:

[0014] Compared with the existing technology, after the transformation, lightweight insulating casting materials are used to form the ash pipe, which ensures the inner diameter size, plays a sealing and insulation effect, ensures the normal operation of the return material system, and the material leg compensator with replaced materials is more economical and durable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the structural diagram of the expansion joint of the return feeder leg.

[0016] Figure 2 It is the process flow for the transformation of the expansion joint of the return feeder leg.

[0017] In the figure: 1 is the first cylinder of the ash pipe, 2 is the flange welding end, 3 is the second cylinder of the ash pipe, 4 is the metal reinforcement mesh, 5 is the ash guide pipe, and 6 is the thermal insulation sealing layer. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] A boiler return feeder leg expansion joint comprises an ash-following pipe and an ash-guiding pipe.

[0020] The ash-following pipe is arranged inside the ash-guiding pipe, and heat-insulating materials are arranged between the ash-following pipe and the ash-guiding pipe.

[0021] When the expansion joint of the return feeder leg is used, one end is connected to the boiler slag outlet and the other end is connected to the slag cooler. That is, the ash pipe is connected to the boiler slag outlet and the ash guide pipe is connected to the slag cooler.

[0022] The ash pipe is composed of two parts, the upper part is a first cylinder made of metal material, and a standard spigot-and-socket joint is provided at the upper end of the first cylinder. The ash pipe is connected to the upstream pipe section through the standard spigot-and-socket joint.

[0023] The lower end of the first cylinder has a flange welding end. The lower part is a second cylinder made of high temperature and wear resistant material. The second cylinder has a metal rib mesh as an internal structural member, and the outer layer is paved with cast high temperature and wear resistant material. The upper end of the metal rib mesh of the second cylinder is connected and fixed to the flange welding end of the lower end of the first cylinder by welding.

[0024] The lower end of the second cylinder is a free end, which is inserted into the ash guiding pipe.

[0025] A flange is provided at the lower end of the ash guide pipe, and the flange is connected to the downstream pipe section of the ash guide pipe by welding.

[0026] A heat-insulating sealing layer is filled between the second cylinder and the ash guiding pipe.

[0027] In the specific implementation, when modifying the expansion joint of the existing return feeder leg, the method and steps are as follows:

[0028] 1) When the boiler is shut down and in cold state, cut off the original ash pipe.

[0029] On-site processing to cut off the lower part of the original ash pipe can be done by gas cutting and grinding.

[0030] After processing and cutting, the lower edge of the retained ash pipe is higher than the upper edge of the ash guide pipe, and the height difference between the two is 10-20CM.

[0031] The retained ash pipe serves as the first cylinder.

[0032] 2) Weld the flange end of the ash pipe.

[0033] The flange welding end is a ring structure, its outer diameter is equal to the outer diameter of the ash pipe, and its inner diameter is slightly smaller than the inner diameter of the ash pipe. The inner diameter is slightly smaller than the inner diameter of the ash pipe by 5-10CM.

[0034] The flange welding end is used as the base surface of the second cylinder, and the flange welding end is used to connect the metal reinforcement mesh at the bottom. When the flange welding end is prefabricated, a number of rooting foundation piles are evenly welded on its lower surface.

[0035] The upper surface of the flange welding end is connected to the lower end of the first cylinder by welding.

[0036] 3) A thermal insulation sealing layer is laid inside the ash guide pipe, using a 3CM thick asbestos cushion layer, which is laid from the upper end of the ash guide pipe downwards, with an extension height of about 100CM.

[0037] 4) Prepare metal mesh and weld it in place.

[0038] The metal rib net is in the shape of a long strip, and its height is equal to the downward extension height of the second cylinder, which is about 50-70CM.

[0039] The length is approximately the circumference of the ash pipe. The upper end of the metal rib net is connected to the rooting foundation pile on the lower surface of the flange welding end of the ash pipe by welding, and after welding and positioning, it is rolled into a cylinder to serve as the internal support structure of the second cylinder.

[0040] 5) Arrange the mold box and pour the heat-resistant profiles.

[0041] A mold box is arranged inside the metal rib net. The mold box is cylindrical. A 10-15CM pouring space is formed between the outer wall of the mold box and the heat-insulating sealing layer of the ash guide pipe, in which the metal rib net is contained. The pouring space is connected to the outside world at the upper edge of the ash guide pipe.

[0042] Fill the pouring space with heat-resistant pouring material from the upper edge of the ash guide pipe. The main base material of the heat-resistant pouring material is special grade bauxite, mullite or corundum, with a volume density of 1.2-1.7g / cm 2 It is a lightweight insulating castable that can withstand temperatures above 1350 degrees.

[0043] After a hardening period, the heat-resistant casting material hardens and adheres to the metal reinforcement mesh to form a second cylinder at the lower part of the ash pipe.

[0044] Remove the mold box. Or use a wooden mold box, that is, there is no need to remove the wooden mold box. During the furnace baking stage, the wooden mold box will be burned out along the high temperature slag discharge in the ash pipe.

[0045] 7) When the boiler starts the thermal engine and switches from a cold state to a hot state, the heat-resistant profile of the second cylinder ensures that it has a long service life, and the asbestos cushion between the second cylinder and the ash guide pipe realizes the thermal insulation and sealing effect.

[0046] In this application, the ash pipe steel plate of the expansion joint of the boiler return feeder leg is cut off, and a heat-resistant steel mesh is welded around the upper metal edge, and no welding is performed on the lower part to ensure free expansion. Insulation seal is filled between the steel mesh and the outer steel plate to ensure the expansion gap. Lightweight insulation castable is poured on the steel mesh to ensure the inner diameter size, which plays a sealing and insulation effect, ensures the normal operation of the return feed system, and the leg compensator with replaced materials is more economical and durable.

[0047] Finally, it should be noted that the above description is only an explanation of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail, those skilled in the art can still modify the technical solutions described above or replace some of the technical features with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for modifying the expansion joint of a boiler return feeder leg; the expansion joint includes an ash pipe and an ash guide pipe; the characteristic is that: The steps are as follows: 1) When the boiler is shut down and in cold state, cut off the original ash pipe and keep the ash pipe as the first cylinder; 2) Welding the flange welding end along the ash pipe; the upper surface of the flange welding end is welded to the lower end of the first cylinder; 3) Lay a thermal insulation sealing layer inside the ash guide pipe; 4) Prepare the metal rib mesh and weld it for positioning; the upper end of the metal rib mesh is connected to the lower surface of the flange welding end of the ash pipe by welding, and after welding and positioning, it is rolled into a cylinder to serve as the internal support structure of the second cylinder; 5) Arrange the mold box and pour the heat-resistant profiles; Arrange the mold box inside the metal rib mesh, and fill the pouring space with heat-resistant pouring materials from the upper edge of the ash guide pipe; 6) After the hardening time, the heat-resistant casting material hardens and adheres to the metal rib net to form the second cylinder under the ash pipe; 7) The boiler starts the thermal engine and switches from a cold state to a hot state. The heat-resistant casting material of the second cylinder ensures its service life, and the asbestos cushion layer between the second cylinder and the ash guide pipe realizes thermal insulation and sealing.

2. According to the method for modifying the expansion joint of the feed leg of a boiler return feeder according to claim 1, it is characterized in that: In step 1), after machining and cutting, the lower edge of the ash pipe is retained to be higher than the upper edge of the ash guide pipe, with a height difference of 10-20CM, and is used as a heat-resistant casting material to fill the channel.

3. A method for modifying a boiler return feeder leg expansion joint according to claim 1, characterized in that: In step 2), the flange welding end is an annular structure, whose outer diameter is equal to the outer diameter of the ash pipe and whose inner diameter is slightly smaller than the inner diameter of the ash pipe. The flange welding end serves as the base surface of the second cylinder.

4. A method for modifying a boiler return feeder leg expansion joint according to claim 3, characterized in that: The flange welding end is used to connect the metal reinforcement mesh at the bottom. When the flange welding end is prefabricated, a number of rooting foundation piles are evenly welded on its lower surface.

5. A method for modifying a boiler return feeder leg expansion joint according to claim 1, characterized in that: In step 4), the metal rib mesh is in the shape of a long strip, the height of which is equal to the downward extension height of the second cylinder, and the length of which is approximately the circumference of the ash pipe.

6. A method for modifying a boiler return feeder leg expansion joint according to claim 1, characterized in that: In step 5), the mold box is cylindrical, and a casting space of 10-15CM is formed between the outer wall of the mold box and the ash guide pipe insulation sealing layer, in which a metal rib mesh is accommodated.

7. A method for modifying a boiler return feeder leg expansion joint according to claim 1, characterized in that: In step 5), the pouring space is filled with heat-resistant pouring material from the upper edge of the ash guide pipe. The main base material of the heat-resistant pouring material is special grade bauxite, mullite or corundum, and the volume density is 1.2-1.7g / cm 2 , which is a lightweight insulating castable.

8. A method for modifying a boiler return feeder leg expansion joint according to claim 1, characterized in that: In step 6), the mold box is removed; or a wooden mold box is used, that is, the wooden mold box does not need to be removed, and in the furnace baking stage, the wooden mold box is burned completely along the high temperature slag discharge in the ash pipe.

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