RU2438772C1 - Heat isolation of primary reforming tube furnace bottom manifold - Google Patents

Abstract

FIELD: process engineering. ^ SUBSTANCE: invention relates to structural elements of thermal units, particularly, to primary reforming tube furnace bottom manifold heat isolator incorporated with ammonium synthesis plant used in production of other chemical products. Proposed heat isolator represents a box resting on furnace hearth, its lateral lengthwise walls being formed by vertical plates arranged along manifold and jointed by tenons and slots. Box flooring is made up of horizontal plates laid on said vertical plates with opposite faces oriented perpendicular to manifold lengthwise axis and provided with symmetric recesses to receive reaction tubes. Box bottom follows the shape of plates arranged on furnace hearth between vertical plates while face blocks are made up of prefabricated modules from refractory fibrous material in contact with extreme vertical and horizontal plates, on one side, and, on opposite side, with furnace wall. Note also that butts between plates, and between plates and tubes are filled with linings from mullite siliceous felt. ^ EFFECT: fast diagnostics of manifold due to lifting of horizontal plates. ^ 3 cl, 3 dwg

Description

The invention relates to structural elements of thermal units, in particular to a device for thermal insulation of the lower collector of a primary reforming tube furnace, which is part of an ammonia synthesis unit, as well as used in the production of other chemical products, for example methanol.

There are various designs of thermal insulation of the lower manifold of the primary reforming tube furnace, including the surrounding manifold and adjacent sections of the reaction tubes, heat-insulating blocks or a packed refractory mass enclosed in a metal casing (Technical documentation "Insulation of the lower manifold of the reforming furnace 1015 (107)" under contract No. 2-04-079 R / 139 F dated 03/18/2004 between the company ASNEMA JSC (Republic of Lithuania) and the company CELIT (Czech Republic); RF patent No. 2102310, IPC С01В 3/26, publ. 1998; German patent No. 4327176 IPC B01J 19/14; B01J 8 / 06; С01В 3/26; СВВ 3/38; B01J 8/02; СВВ 3/00, publ. 1995; Yu. Levin. Refractory materials for monolithic linings of units of the oil refining and petrochemical industries / New refractories, No. 3, 2002, p. 56-58).

The closest known one is the thermal insulation of the lower collector of the primary reforming tube furnace, including covering the collector and adjacent sections of the reaction tubes, heat-insulating blocks installed along the collector, interconnected and having recesses for the reaction tubes, end heat-insulating blocks and fibrous refractory material filling joints between blocks and between blocks and pipes.

Moreover, the known design is made based directly on the collector, and shaped thermally insulating blocks made by vacuum molding are mirrored one relative to another and cover the collector with adjacent sections of two reaction tubes over the entire surface. These blocks are bonded to each other and to neighboring blocks along the longitudinal axis of the collector, as well as to disk-shaped end blocks by means of anchor fasteners on which protective tapes of refractory fibrous material are glued to prevent thermal oxidation. To compensate for temperature changes, the known design involves the use of a refractory material, which is located in the form of a cord in the joints between the insulating blocks and in the form of a mat covers the collector with adjacent sections of the reaction tubes. On the surface of the known thermal insulation, a protective coating of refractory mastic is made to increase the gas density of heat-insulating blocks having a porous structure (Technical documentation “Insulation of the lower collector of the reforming furnace 1015 (107)” under contract No. 2-04-079 R / 139 F of 03/18/2004 between the company ASNEMA JSC (Republic of Lithuania) and CELIT (Czech Republic)).

Known thermal insulation is quite effective and its design allows you to freely move with the collector in case of temperature changes.

The disadvantage of this thermal insulation is, firstly, the difficulty of manufacturing both its constituent elements, in particular vacuum shaped heat-insulating blocks, and the design as a whole, which includes 8 sizes of shaped blocks and 15 items of materials and components.

The implementation of the known design, based directly on the collector, increases the load on the suspension system of the reaction tubes, and therefore the mass of thermal insulation is strictly limited. The apparent density of the insulating blocks should not exceed 250 kg / m ³ , while their strength should be sufficient for installation and operation of thermal insulation. The manufacturing technology of vacuum shaped heat-insulating blocks with the specified physical and ceramic properties and a given configuration is quite complicated, which increases their cost.

In addition, the presence of a set of anchor fasteners made of expensive heat-resistant metal not only makes the suspension structure heavier, but also increases the cost of the thermal insulation itself and its installation due to the need for additional protection of the anchor fasteners from exposure to the working environment.

Another disadvantage of the known design is the complexity and duration of its installation and dismantling due to the large number of operations necessary for their implementation. Due to the small distance between the collector and the flue gas tunnels, installation of thermal insulation of a complex construction is possible only with a complete overhaul of the furnace in the absence of tunnel walls. For the same reason, the dismantling of a known design is also problematic.

For periodic pipe diagnostics, it is necessary to disassemble the thermal insulation section and also the nearby flue gas tunnels, which are located in the immediate vicinity of the collector. All this delays the overhaul period and increases unproductive reforming downtime due to thermal insulation.

In addition, the limited distance of the known thermal insulation from the bottom does not allow to increase the thickness of the latter and effectively insulate it, resulting in significantly increased heat loss through the bottom.

Thus, the use of the known design of thermal insulation of the lower collector of the tubular reforming furnace leads to an increase in the cost of its manufacture and installation, and also increases the downtime of reforming due to thermal insulation and increases heat loss through the bottom.

The problem that the invention solves is to create a more economical, sufficiently effective design of the thermal insulation of the lower collector, simple to install and disassemble, and convenient to maintain the collector.

The technical result that can be achieved by using the invention is to simplify the design, reduce the time for its installation and dismantling, facilitate access to the manifold during pipe diagnostics, and reduce heat loss through the hearth of the furnace.

The specified technical result is achieved in that the thermal insulation of the lower collector of the primary reforming tube furnace, including the reaction tubes surrounding the collector and adjacent to it, heat-insulating blocks mounted along the collector, interconnected and having recesses for reaction tubes, end heat-insulating blocks and fibrous refractory material filling joints both between blocks and between blocks and pipes, according to the invention it is made in the form of a box resting on the bottom of the furnace, more the longitudinal walls of which are formed by heat-insulating blocks installed along the collector in the form of vertical plates fixed in the hearth of the furnace and interconnected by means of a tongue-and-groove system, the ceiling of the duct is mounted from heat-insulating blocks freely laid on vertical plates in the form of horizontal plates having opposite sides, perpendicular to the longitudinal axis of the collector, symmetrical recesses for the reaction tubes, the bottom of the duct is made of heat-insulating blocks in the form of um, freely placed on the hearth of the furnace between the vertical plates, the end heat-insulating blocks closing the duct contour are made in the form of prefabricated modules of refractory fibrous material located on the hearth, in contact with one of its sides with the extreme vertical and horizontal plates of the box, and the other with the wall of the furnace, and as a refractory fibrous material for filling joints, gaskets made of mullite-siliceous felt are used.

In addition, according to the invention, the gaskets in the joints between the horizontal plates and sections of the reaction tubes are made glued to the surface of the faces with recesses.

In addition, according to the invention, the surface of the vertical and horizontal plates facing the working space of the furnace is impregnated with a refractory composition.

The thermal insulation of the lower manifold in the form of a box resting on the bottom of the furnace allows to transfer the load from thermal insulation from the collector and the suspension system of the reaction pipes to the bottom. This creates conditions for simplifying the design of thermal insulation and the possibility of using cheaper and more durable structural elements - heat-insulating blocks with an apparent density of more than 250 kg / m ³ , having the form of plates, the manufacture of which under production conditions is not particularly difficult.

Simplification and cheaper construction of the thermal insulation of the lower collector is facilitated by a decrease in the number of sizes of heat-insulating blocks from 8 to 4, as well as a decrease in the total number of materials and components from 15 to 7. In accordance with this, the number of operations during installation and dismantling is reduced, and the overhaul period is reduced.

The implementation of the lateral longitudinal walls of the box from vertical plates, the base of which is fixed (sandwiched) between the hearth products and connected to each other by means of a tongue groove, as well as the free laying of horizontal plates on vertical plates and the free installation of the box, made it possible to refuse expensive anchor fasteners that complicate installation thermal insulation and increasing its cost.

In addition, the configuration of horizontal plates with opposite edges, perpendicular to the longitudinal axis of the collector, symmetrical recesses for the reaction pipes, facilitates the installation and dismantling of thermal insulation and provides free access to the pipes for their diagnosis. To do this, you only need to lift the horizontal plate and it can be easily removed, and at the end of the diagnosis it fits into its original position.

Due to the implementation of the heat-insulating box resting on the bottom, an additional space appeared between the collector and the bottom, which in the proposed design was used to heat the bottom. The heat-insulating plates freely placed on the hearth of the furnace between the longitudinal side walls of the duct form the bottom of the duct, which reduces heat loss through the hearth.

The use of prefabricated modules of refractory fibrous material for closing the duct loop located on the bottom of the furnace and in contact with one of its sides with extreme vertical and horizontal plates, and the other with the furnace wall, ensures the gas tightness of the heat-insulating box with the free movement of its structural elements along the longitudinal axis of the collector at temperature changes.

Mullite-siliceous felt gaskets filling the joints between vertical plates are also designed to compensate for the movement of vertical plates along the longitudinal axis of the collector during temperature changes.

The gaskets located in the joints between the horizontal plates and the sections of the reaction tubes adjacent to the collector compensate for the thermal expansion of both the pipes and the plates themselves at temperature extremes, contributing to better sliding of the pipes when they move in the vertical direction, and keep the joints tight.

In order that these gaskets do not wrinkle and do not fall out when the pipes move, they are glued to the surface of the faces of horizontal plates with recesses.

To increase the gas density of the insulating duct between horizontal and vertical plates, mullite-siliceous felt gaskets are laid that reliably isolate the inner space of the duct from the working medium.

The use of vertical and horizontal plates with the impregnation of the outer layer with a refractory composition protects the lightweight plate material from premature wear by high-speed coolant flows, contributing to a longer operation of thermal insulation.

Thus, the design according to the invention is more economical compared to the known one, quite effective, reduces heat loss through the hearth of the furnace, reduces the duration of installation and dismantling, and is also convenient for servicing the collector.

The thermal insulation of the lower collector according to the invention is illustrated by drawings, where figure 1 shows thermal insulation in a perspective view; figure 2 is its cross section; figure 3 is a fragment of a longitudinal section of thermal insulation.

The proposed thermal insulation of the lower collector of the primary reforming tube furnace includes a duct 2 resting on the hearth 1 (Fig. 1) of the furnace, covering the manifold 3 and adjacent sections of the reaction tubes 4, the longitudinal side walls 5 of which are made of vertical plates 6 (Fig. 2) installed along the collector 3. Vertical plates 6 are sandwiched between the products 7 and the plates 8 of the bottom 9 and are interconnected by means of spikes 10 and grooves 11. The overlap 12 of the box 2 is formed by horizontal plates 13 freely laid on vertical plates 6.

The plates 13 have on the faces 14 (Fig. 3), perpendicular to the longitudinal axis 15 of the collector, symmetrical recesses 16 for the pipes 4. The bottom 9 of the box is made of plates 8, freely placed on the bottom 1 between the vertical plates 6. The assembly modules close the loop contour 2 17 of refractory fibrous material, which are placed on the hearth 1 and with one side in contact with the extreme vertical plates 6 and horizontal plates 13, and the other side with the wall 18 of the furnace.

At the joints 19 between the horizontal plates 13 and the sections of the reaction tubes 4, gaskets 20 made of mullite-siliceous felt are placed, which are glued to the surface of the faces 14 with recesses 16.

At the joints 21 between the vertical plates 6 laid gaskets 22.

At the joints 23 between the horizontal and vertical plates 6 and 13 laid gaskets 24.

Surfaces 25 and 26 of plates 6 and 13 facing the working space of the furnace are impregnated with a refractory composition.

Installation of thermal insulation of the lower collector of the primary reforming tube furnace is as follows.

Initially, the placement of the longitudinal side walls 5 of the duct relative to the longitudinal axis 15 of the manifold 3 is made on the hearth 1 of the furnace. Vertical plates 6 are impregnated with an impregnated surface 25 towards the working space of the furnace. In the joints 21 between the plates 6 are laid pads 22 of mullite-siliceous felt. Between the vertical plates 6 are placed the plates 8 of the bottom 9 of the box, and on the outside of the plates 6 put products 7 bottom.

On top of the vertical plates 6, horizontal gaskets 24 made of mullite-siliceous felt are laid on which horizontal plates 13 with gaskets 20 glued to the edges 14 are installed between the pipes 4, thereby forming a box closure.

Between the manufactured box 2 and the walls 18 of the furnace, prefabricated modules 17 of refractory fibrous material are placed, which isolate the collector 3 from the working space.

During the diagnosis of the collector, horizontal plates 13 are lifted and removed, and after the diagnosis is completed, the plates are installed in the same place.

When the temperature of the furnace rises, the reaction pipes 4 expand in length, the collector 3 drops above the level of the bottom 9 of the box 2, while the pipes slide freely along the gaskets 20 of mullite-siliceous felt. At the same time, the pipes 4 increase in diameter, compressing the gaskets 20, which provide sealing of the joints 19 between the horizontal plates 13 and the pipes 4.

In the longitudinal direction, the collector 3 is elongated, which, expanding, compresses the assembly module 17, pressing it against the wall 18. The gaskets 22 in the joints 21 between the vertical plates 6 are compressed due to the elasticity of the refractory fiber, thereby ensuring reliable sealing of the joints 21 between the vertical cookers.

When the furnace cools, the length of the pipes 4 decreases, the collector 3 rises, the pipes 4 slide up along the gasket 20. At the same time, the diameter of the pipes decreases, the gasket 20, due to its elasticity, expands, covering the joints 19 between the pipes and horizontal plates.

At the same time, the length of the collector is reduced, the module 17 is expanded, while maintaining the gas tightness of the duct.

The gaskets 24 during the heating and cooling of the furnace seal the joints 23 between the longitudinal side walls 5 and the overlap 12 of the box.

Thus, the use of thermal insulation according to the invention allows to reduce the cost of its manufacture and installation, to reduce the time of installation and dismantling during repair, to reduce heat loss through the bottom of the furnace, as well as to reduce unproductive downtime of reforming due to the reduction of repair time of thermal insulation and collector diagnostics.

Claims (3)

1. Thermal insulation of the lower manifold of the primary reforming tube furnace, including the surrounding manifold and adjacent sections of the reaction tubes, heat-insulating blocks installed along the collector, interconnected and having recesses for the reaction tubes, end heat-insulating blocks and fibrous refractory material filling the joints as between heat-insulating blocks, and between heat-insulating blocks and pipes, characterized in that it is made in the form of a box resting on the bottom of the furnace, side p the native walls of which are formed by heat-insulating blocks installed along the collector in the form of vertical plates mounted on the bottom of the furnace and interconnected by a tenon groove system, the ceiling of the duct is mounted from heat-insulating blocks freely laid on vertical plates in the form of horizontal plates having, on opposite sides, perpendicular to oriented longitudinal axis of the collector, symmetrical recesses for the reaction pipes, the bottom of the box is laid out of heat-insulating blocks in the form of plates, end-to-end heat insulating blocks, placed on the hearth of the furnace between the vertical plates, the end insulating blocks made in the form of prefabricated modules of refractory fibrous material located on the hearth of the furnace, in contact with one of their sides with the extreme vertical and horizontal plates of the box, the other with the wall of the furnace, and as refractory fibrous material to fill the joints using gaskets of mullite-siliceous felt. 2. Thermal insulation of the lower manifold of the primary reforming tube furnace according to claim 1, characterized in that the gaskets in the joints between the horizontal plates and the adjacent sections of the reaction pipes are glued to the surface of the faces of horizontal plates with recesses. 3. The thermal insulation of the lower collector of the primary reforming tube furnace according to claim 1, characterized in that the surface of the vertical and horizontal plates facing the working space of the furnace is impregnated with a refractory composition.

Images