GB2087523A

GB2087523A - Modular package boiler

Info

Publication number: GB2087523A
Application number: GB8134475A
Authority: GB
Original assignee: Foster Wheeler (London) Ltd
Current assignee: Foster Wheeler (London) Ltd
Priority date: 1980-11-14
Filing date: 1981-11-16
Publication date: 1982-05-26
Also published as: GB2087523B

Abstract

A boiler is provided in modular form for assembly on site. The boiler comprises a boiler bank (2) disposed between two furnace modules (4, 6), each having been manufactured as a separate integral unit. The final assembly is completed by the connection of the furnace headers (18, 20) to stubs on the steam (8) and water (10) drums of the boiler bank (2), and by the interconnection of the superheater sections (22, 24). Means are provided for defining flow paths for combustion gases from burners in the furnace modules (4, 6) through the respective superheater sections (22, 24) and into the boiler bank (2). <IMAGE>

Description

SPECIFICATION Modular package boiler The present invention relates to boilers, and more particularly to a boiler in modular form which minimizes site erection time.

The size of many boilers in current designs renders their transportation as an assembled unit both difficult and costly. On-site assembly is also costly and time-consuming. The present invention is directed at a boiler construction suited to onsite assembly, but which is so designed as to minimize the time required to complete the assembly of the boiler.

According to the invention a boiler comprises a boiler bank and two furnace modules constructed as separate components for subsequent connection to the boiler bank, each furnace module including a superheater section; a burner housing; and means defining a flow path for combustion gases from the burner to the superheater section, and from the superheater section to an outlet from the module coupled to one of two inlets to the boiler bank.

In the use of a preferred boiler according to the invention fuel is burnt in each furnace module and the hot gases pass across the respective modules, up through superheaters, and into the boiler bank prior to discharge. Each module is constructed separately, and the only on site connections that have to be made are between the furance header feeder and riser tubes, and stubs on the steam and water drums.

In a preferred embodiment of the invention, the boiler bank is disposed between the two furnace modules defining common front and rear walls.

The burners (typically of natural gas) are positioned on the front wall and hot gases therefrom flow to the rear wall. The tubes of the furnace modules are spread in the lower third to form an exit screen from which the gases pass upwardly over superheaters. Preferably, a primary superheater is located in one furnace module, and a secondary superheater in the other. Reheater surface area can also be incorporated as needed.

The tubes of the front wall of the boiler are preferably of MONOWALL (Registered Trade Mark) construction, as are those in the furnace modules. The boiler bank tubes may be finned, where appropriate, to improve heat transfer.

The invention will now be described by way of example and with reference to the accompanying drawings wherein: Figure 1 is a sectional plan view of a boiler according to the invention; Figure 2 is a sectional elevation taken on line A-A of Figure 1; and Figure 3 is a sectional elevation taken on line B-B of Figure 2.

The boiler shown in the drawings comprises a boiler bank 2 disposed between furnace modules 4 and 6 defining a front wall and a rear wall. The boiler bank has an upper steam drum 8 and a lower water drum 10 connected by riser tubes 12.

External downcomers 14 are located at the rear wall. Each furnace module has a rear wall comprising riser tubes 1 6 extending vertically between headers 1 8 and 20 which are connected to stubs (not shown) on the steam (8) and water (10) drums. A primary superheater 22 and a secondary superheater 24 are also included in the respective furnace modules, adjacent the rear wall of the boiler. Steam from the drum 8 is fed to the primary inlet 26 to the superheater 22. Its outlet 28 connects with the secondary inlet 30 to the superheater 24, whence superheated steam is discharged at 42. Each superheater is fully drainabie by means of one or more drain pipes 32 (shown in Figure 3).

The furnace modules 4 and 6, and the boiler bank 2 are manufactured as integral units in the factory, and delivered separately to the site. The boiler assembly is completed on a suitable support surface by connecting the furnace headers 1 8 and 20 to the stubs on the steam (8) and water (10) drums, and connecting the superheater sections 22 and 24. The abutting walls of the boiler bank 2 and the respective furnace modules 4, 6 may be provided with suitable seals 40 as desired to prevent leakage of combustion gases.

Burners 34 and 36 for the respective furnace modules are located in the front wall of the boiler.

With the boiler in use, hot gases from the burners flow across the furnace modules towards the rear wall. The MONOWALL tubes 16 in the lower part of the furnace modules are spread to form an exit screen from which the gases pass upwards to the superheaters. From the superheater exit cavities, the hot gases pass to the boiler bank for discharge at the front wall. Suitable baffle walls 38 are provided to define these flow paths. The boiler bank tubes 1 2 may also have helical fins if the gas temperature allows, to provide extended heat transfer surface area.

The front and side walls of each furnace modules are each preferably comprised of a single layer of tubes, with adjacent tubes being directly interconnected. The front wall of the boiler bank will normally be of welded finned tubes, as is the entire rear wall. The diameter of the tubes in the rear walls of the furnace modules is enlarged below the superheater sections.

1. A boiler comprising a boiler bank and two furnace modules constructed as separate components for subsequent connection to the boiler bank, each furnace module including a superheater section; a burner housing; and means defining a flow path for combustion gases from the burner to the superheater section, and from the superheater section to an outlet from the module coupled to one of two inlets to the boiler bank.

2. A boiler according to Claim 1 wherein each furnace module has a front wall; a rear wall; and two side walls, the burner being located adjacent the front wall, the superheater being located adjacent the rear wall, and the outlet for combustion gases being located in one of the side

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Modular package boiler The present invention relates to boilers, and more particularly to a boiler in modular form which minimizes site erection time. The size of many boilers in current designs renders their transportation as an assembled unit both difficult and costly. On-site assembly is also costly and time-consuming. The present invention is directed at a boiler construction suited to onsite assembly, but which is so designed as to minimize the time required to complete the assembly of the boiler. According to the invention a boiler comprises a boiler bank and two furnace modules constructed as separate components for subsequent connection to the boiler bank, each furnace module including a superheater section; a burner housing; and means defining a flow path for combustion gases from the burner to the superheater section, and from the superheater section to an outlet from the module coupled to one of two inlets to the boiler bank. In the use of a preferred boiler according to the invention fuel is burnt in each furnace module and the hot gases pass across the respective modules, up through superheaters, and into the boiler bank prior to discharge. Each module is constructed separately, and the only on site connections that have to be made are between the furance header feeder and riser tubes, and stubs on the steam and water drums. In a preferred embodiment of the invention, the boiler bank is disposed between the two furnace modules defining common front and rear walls. The burners (typically of natural gas) are positioned on the front wall and hot gases therefrom flow to the rear wall. The tubes of the furnace modules are spread in the lower third to form an exit screen from which the gases pass upwardly over superheaters. Preferably, a primary superheater is located in one furnace module, and a secondary superheater in the other. Reheater surface area can also be incorporated as needed. The tubes of the front wall of the boiler are preferably of MONOWALL (Registered Trade Mark) construction, as are those in the furnace modules. The boiler bank tubes may be finned, where appropriate, to improve heat transfer. The invention will now be described by way of example and with reference to the accompanying drawings wherein: Figure 1 is a sectional plan view of a boiler according to the invention; Figure 2 is a sectional elevation taken on line A-A of Figure 1; and Figure 3 is a sectional elevation taken on line B-B of Figure 2. The boiler shown in the drawings comprises a boiler bank 2 disposed between furnace modules 4 and 6 defining a front wall and a rear wall. The boiler bank has an upper steam drum 8 and a lower water drum 10 connected by riser tubes 12. External downcomers 14 are located at the rear wall. Each furnace module has a rear wall comprising riser tubes 1 6 extending vertically between headers 1 8 and 20 which are connected to stubs (not shown) on the steam (8) and water (10) drums. A primary superheater 22 and a secondary superheater 24 are also included in the respective furnace modules, adjacent the rear wall of the boiler. Steam from the drum 8 is fed to the primary inlet 26 to the superheater 22. Its outlet 28 connects with the secondary inlet 30 to the superheater 24, whence superheated steam is discharged at 42. Each superheater is fully drainabie by means of one or more drain pipes 32 (shown in Figure 3). The furnace modules 4 and 6, and the boiler bank 2 are manufactured as integral units in the factory, and delivered separately to the site. The boiler assembly is completed on a suitable support surface by connecting the furnace headers 1 8 and 20 to the stubs on the steam (8) and water (10) drums, and connecting the superheater sections 22 and 24. The abutting walls of the boiler bank 2 and the respective furnace modules 4, 6 may be provided with suitable seals 40 as desired to prevent leakage of combustion gases. Burners 34 and 36 for the respective furnace modules are located in the front wall of the boiler. With the boiler in use, hot gases from the burners flow across the furnace modules towards the rear wall. The MONOWALL tubes 16 in the lower part of the furnace modules are spread to form an exit screen from which the gases pass upwards to the superheaters. From the superheater exit cavities, the hot gases pass to the boiler bank for discharge at the front wall. Suitable baffle walls 38 are provided to define these flow paths. The boiler bank tubes 1 2 may also have helical fins if the gas temperature allows, to provide extended heat transfer surface area. The front and side walls of each furnace modules are each preferably comprised of a single layer of tubes, with adjacent tubes being directly interconnected. The front wall of the boiler bank will normally be of welded finned tubes, as is the entire rear wall. The diameter of the tubes in the rear walls of the furnace modules is enlarged below the superheater sections. CLAIMS

2. A boiler according to Claim 1 wherein each furnace module has a front wall; a rear wall; and two side walls, the burner being located adjacent the front wall, the superheater being located adjacent the rear wall, and the outlet for combustion gases being located in one of the side walls.

3. A boiler according to Claim 1 or Claim 2 wherein the boiler bank comprises an upper steam drum and a lower water drum, and wherein the walls of the furnace modules comprise vertically extending tubes connected to the steam and water drums of the boiler bank, adjacent tubes being directly interconnected to form a gas tight seal.

4. A boiler according to Claim 3 wherein each furnace module includes upper and lower headers between which said vertically extending tubes extend, the headers being connected respectiveiy to the steam and water drums.

5. A boiler according to any preceding Claim wherein the flow path defining means are walls comprising tubes having interconnected flanges forming gas tight barriers.

6. A boiler according to any preceding Claim wherein the superheater sections comprise primary and secondary superheater sections, the boiler including means for directing steam from the boiler bank to the primary section, and thence to the secondary section.

7. A boiler according to Claim 6 wherein the primary superheater section is in one furnace module, and the secondary superheater section is in the other furnace module.

8. A boiler substantially as described herein with reference to the accompanying drawings.