Capital repair project of the horizontal area of the arch and transitional area of the thermal oil installation (TMU-1) of CJSC MUROM

On September 25, 2019, LLC “Wellons.RU” successfully completed a project to replace the refractory lining of the roof and the transitional section of the thermal oil installation (TMU-1). These works were performed on the terms of an EPCM contract, including engineering, selection and delivery of materials, as well as installation supervision of the work performed in accordance with the technical documentation of the project (installation work itself was performed by the customer).

ENGINEERING.

Within the framework of this project, the specialists of Wellons.RU LLC have developed various options for refractory lining using a multilayer structure (two-layer heat-insulating lining and lining of the working layer using monolithic refractory concrete).

The complexity of this project is due to the need to partially replace the existing lining, its adjacency to the existing wall lining, the design of a flat arch with a transitional cylindrical section, as well as the need to solve the constantly arising problem of the destruction of the refractory lining in the area of inclined and horizontal sections of the TMU flat arch.

SELECTION AND DELIVERY OF THE REFRACTORY.

Plot of flat vault. To solve the problem of periodic refractory failure, we selected analogues of refractory and heat-insulating materials, according to the original design of the lining of the manufacturer TMU-1. High-aluminate refractory concrete of the BORCAST-70W brand (layer thickness 200 mm.) With a working temperature of up to 1450-1500 ° C was used as the working layer refractory, as well as the KTP-70 kaolin plate (150 mm in two layers) as the first heat-insulating layer.) with a working temperature of application up to 1250 ° С, as a second heat-insulating layer - a calcium silicate plate of the SILBORD type (one layer with a thickness of 100 mm.) with a working temperature of use up to 1000 ° С. The total thickness of the lining is 450 mm. For forming expansion joints Durablanket 128 rolled heat-insulating material (blanket) with a thickness of 10 mm with an operating temperature of up to 1250 ° C is used.

To ensure the structural strength of the refractory lining as a whole, taking into account the high temperature in the area of application of the refractory (up to 1250 ° C), we have developed and manufactured ceramic anchors made of thixotropic concrete with a high Al2O3 content> 80%, having a high application temperature and strength characteristics. These ceramic anchors apply together with metal anchors made of high-alloy heat-resistant steel AISI 310S.

Transitional, cylindrical section. To reduce the possible installation / refractory lining time in this area, the WELL-PLAST P85 high-aluminate high-refractory plastic packing mass with an Al2O3 content> 84% and an operating temperature of up to 1550 ° C was used as the working layer. This material is delivered ready to use and does not require additional work on the construction of formwork, which can significantly reduce the installation time of this refractory, in comparison with traditional “pouring” concrete. A silicate-calcium plate 100 mm thick was used as a heat-insulating layer. To ensure the structural strength of the refractory lining, metal anchors made of high-alloy heat-resistant steel AISI 310S are used.

INSTALLATION WORKS.

ВAll work related to the installation of refractory lining was carried out under the direct supervision and with the participation of specialists of LLC Wellons.RU. Installation of the refractory, as well as the necessary auxiliary work was carried out by specialists of ZAO Murom.

All main types of work are described below in the relevant sections. They will also be presented in our short video reports on the company’s website in the section “REFRACTORY OF THE COVER OF THE THERMAL OIL INSTALLATION”.

1. PLOT OF TILT VOLTAGE OF TMU.

The design of the lining of the inclined roof is two layers of thermal insulation from a kaolin plate with a total thickness of 150 mm and a calcium silicate plate with a thickness of 100 mm .; working layer - from BORCAST-70W refractory concrete 200 mm thick. The total thickness of the lining is 450 mm.

Device and fill cards:

  • Before starting the installation of the heat-insulating layer, suspension elements of ceramic anchors (4 pcs.) And heat-resistant metal anchors (3 pcs.) Are installed to secure the fireproof concrete of the working layer.
  • A heat-insulating layer of a calcium silicate plate is placed in the inter-anchor space by fitting and sawing this material as tightly as possible. Existing seams are filled with a thermal blanket.
  • Then, the kaolin insulation boards are laid in two rows, if possible, ensuring maximum density between the different segments of the boards.
  • Before laying the second row of the kaolin plate on the suspension element, using the suspension elements (heat-resistant fastening element), the ceramic anchor is installed with its obligatory expansion using plastic wedges, as well as the suspension elements are fastened with knitting wire to ensure reliable anchoring to the period of pouring concrete of the working layer. The use of plastic anchors is a prerequisite! When temperature is set, these plastic wedges burn out and, thus, provide the possibility of thermal expansion of the concrete of the card and anchor, respectively.
  • Prior to the installation of the ceramic anchor, this anchor must be prepared - apply a thin layer of bitumen mastic ~ 0.5 mm thick. to provide compensation for thermal expansion of the concrete of the working layer and anchor material.
  • The formwork of the side walls of the card is installed and, accordingly, after the completion of the installation of heat-insulating layers and card anchors, the upper formwork cover is mounted on pre-welded threaded rods, and the formwork is fastened with additional racks. The top cover, the side walls of the formwork must be lubricated with used oil, to ensure the normal process of disassembling the formwork and to prevent concrete from sticking directly to the formwork cover material (plywood, metal).
  • The refractory concrete layer is poured. Layer thickness 200 mm. when using a deep vibrator.
  • Inclined vault consists of three cards - first of all, concrete is poured into two extreme cards. After concrete exposure (10-12 hours) the formwork is carefully removed. The middle map is prepared for filling according to the procedure described above. Cards are poured in parallel with other cards (maps of the transition section / entrance to the cylindrical part of TMU).
  • • Before the final assembly of the formwork of the middle card of the inclined vault, a tape is made from a heat-insulating blanket (200 mm wide) on previously formed card walls to form temperature expansion joints.
  • The adjoining of the wall lining and the newly laid refractory is also laid with a heat-insulating blanket to the width of the wall lining - a temperature seam is formed.

2. TRANSITIONAL AREA OF THE FORM OF TMU.

The design of the lining of the transitional section of the arch is two layers of thermal insulation from a kaolin plate with a total thickness of 150 mm and a calcium silicate plate with a thickness of 100 mm .; working layer - from BORCAST-70W refractory concrete 200 mm thick. The total thickness of the lining is 450 mm.

Device and fill cards:

  • Due to the complex geometry of the map - the transition of the horizontal section to the vertical plane, while main-taining the radius of the vertical part, the details of the formwork of the map are made in advance, according to the drawings of Wellons, from sheet metal 2 mm thick. with assembly of formwork in place.
  • After installing the vertical edges / walls of the formwork, the installation of anchor products (ceramic and metal an-chors) is carried out, the insulation layers are installed according to the procedure described in section 1.
  • At the transitional section before the start of pouring concrete, five cards are prepared at the same time (through one), which allows to speed up the process of pouring concrete.
  • After the concrete has been soaked for 10-12 hours, the formwork is removed and the formwork is installed (includ-ing work on the installation of heat-insulating layers, installation of anchors, installation of expansion joints) of the remaining five cards and they are poured with refractory concrete of the working layer using a depth vibrator.

3. PLOT OF FLAT VALVE TMU.

The design of the lining of the direct arch is two layers of thermal insulation from a kaolin plate with a total thickness of 150 mm and a calcium silicate plate with a thickness of 100 mm .; working layer - from BORCAST-70W refractory concrete 200 mm thick. The total thickness of the lining is 450 mm.

Device and fill cards:

  • Similar to section 1 - fill in slanted vault cards.
  • The procedure for filling cards - first of all, filling in two side cards, the central card - is filled in last.
  • For the convenience of pouring a flat vault card, after all the preparatory work and the installation of the formwork, the fill is made into pre-cut holes in the ceiling of the TMU case using a deep vibrator.

4. CYLINDRICAL PLOT HEAT EXCHANGE-NIKA TMU.

Lining design - one layer of thermal insulation from silicate-calcium plate 100 mm thick .; working layer - from refractory concrete (ramming mass) VELL-PLAST P85 ~ 120 mm thick. The total thickness of the lining is 220 mm.

Device and fill cards:

  • After the pouring of concrete maps of the transitional section is completed, the heat-insulating layer is made of a calcium silicate plate 100 mm thick. At the same time, the installation of heat-resistant steel anchors is carried out.
  • On the concrete surface of the transition section, to form a temperature joint, a heat-insulation blanket with a width of 130 mm is laid.
  • Ready-made WELL-PALAST briquettes are placed on top of this blanket and “break through” / rammed with a rubber mallet and pneumatic rammer. The mass is stacked and rammed along the entire height of the card (~ 400 mm) in layers. The height of the layer is equal to the thickness of the briquette (65 mm.).
  • After laying the entire required volume of plastic mass, temperature seams are formed by punching or transverse cutting to a depth of 70 mm.

RECOMMENDATIONS:

Upon completion of all lining operations, the main factor in the reliable operation of the refractory is its drying, which must be performed according to the schedule for drying the lining. Please note that all the remaining refractory and heat-insulating materials, as well as the assortment of anchor products, must be placed in stock for the period of warranty obligations of Wellons.RU LLC. This material should be available upon the occurrence of a warranty case.

Note: we consider it necessary to note that when disassembling the formwork of the side map of the transitional section, a small part of the concrete was displaced with the formation of a small shell. This sink was subsequently sealed with plastic refractory WELL-PLAST. This section does not carry critical moments for the normal operation of the lining.

Organizational matters: On September 18, 2019, the plant specialists decided not to disassemble a part of the concrete of the existing vault and transitional section cards (from the material unloading side) in view of the strength of the existing structure. Subsequently, after filling in the middle map of the transitional section, it was decided to return to the original project, which made it difficult to work and, consequently, a loss of time. Despite this, the design of the card meets all the necessary requirements for operating the equipment.