FIELD OF INVENTION
The present invention generally relates to Inclined Evaporator Coils In Back pass
of Circulating fluidized bed combustion boilers (CFBC). More particularly, the
present invention relates to an improved strap support device for supporting
inclined evaporator Coils in circulating fluidized bed combustion boilers.
BACKGROUND OF INVENTION
The CFBC is an environment friendly and efficient system of burning various
grades of fuels. The fuel is burnt inside the system at a temperature between
700-900 deg C, which ensures that Nox is not formed. Sorbent in the form of
limestone is added during the combustion to capture the sulphur present in the
fuel to prevent the formation of Sox. The principal heat transfer surfaces like
evaporator and super heaters are placed in the back/second pass. The primary
air of combustion is directed through the bed at a pre-determined velocity, at
which the bed behaves like a fluid, and an effective heat transfer takes place due
to fluidization.

The evaporator tubes are configured as hanger tubes for supporting the Super
heater coils, Reheater coils and Evaporator coils inside the steam cooled pass of
the boiler. A typical arrangement is shown in Fig 1.
According to prior art, at least two horizontal straps are used to support the coils
along with the vertical hanger tube. The arrangement is such that it supports the
coils, and simultaneously allows an accpmmodation of the thermal expansions.
The existing support structures are suitable for horizontal coils, and being
extensively used in supporting Horizontal coils such as Super heaters and
economizers. However the existing structure cannot be used for supporting the
Inclined Evaporator coils, due to their unique structural configurations.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose an improved strap
support device for supporting inclined evaporator coils, which eliminates the
disadvantages of the prior art.

Another object of the invention is to propose an improved strap support device
for supporting inclined evaporator coils, which is enabled to adapt vertical hanger
tubes.
A further object of the invention is to propose an improved strap supportsdevice
for supporting inclined evaporator coils, which is enabled to cater for longitudinal
including lateral thermal movements.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved strap support device for inclined
evaporator coils in CFBC boilers comprising a steam cooled membrane wall
disposed at exit of CFBC boiler cyclone. A first super heater coil; a second re-
heater coil, disposed above the inclined evaporator coils supported by a plurality
of hanger tubes. A tube assembly comprising at least one tube and a plurality of
strap means fitted over the tube.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS.
Figure 1- shows a typical arrangement of hanger tubes in a CFBC boiler.

Figure 2- shows a cross sectional view of a strap support device used in prior art
Figure 3- shows a cross sectional view of a strap support device used for inclined
evaporator coils.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
With the above and other objectives in view, the present invention provides an
improved strap support device for supporting inclined evaporator coils in CFBC
boiler.
As shown in Fig-3, a plurality of strap means are configured so as to provide
support to the inclined evaporator coils using vertical hanger tubes. According to
the invention, the inclined evaporator coil is mounted on the hanger tube
preceded by providing suitable inclinations for the vertical hanger tube, by
means of the strap means. The strap means is then assembled over it supporting
the Evaporator coils.

The profile of the strap means is so configured to accommodate for the
inclination of the coils including intersection of the vertical hanger tubes with the
inclined coils. This configuration enables the vertical hanger tubes to carry the
inclined evaporator coils. The strap means is capable to effectively carry the load
of the evaporator coils and permits the thermal movements anticipated in the hot
conditions.
An inclined evaporator coil (1) is fixedly arranged on the boundary wall (2) of the
CFBC boiler second pass by a hanger tube (3). The tube (3) is having a number
of straps means (4). As shown in figure-1, the evaporator coil (1) is covered by
at least one membrane (2).

We Claim:
1. An improved strap support device for supporting inclined evaporator coils
in circulating fluidized bed combustion (CFBC) boilers, the device
comprising:
- a steam-cooled membrane wall disposed at the exit of CFBC boiler
cyclone;
- a first super heater coil, and a second reheater coil disposed above
at least one inclined evaporator coil, the evaporator coil being
rigidly fixed on the membrane wall;
- a plurality of vertical hanger tubes supporting said atleast one
evaporator coil; and
- a plurality of strap means releasably supporting the hanger tubes,
the strap means being configured to cater for the inclination of the
evaporator coil including a corresponding inclination to the vertical
hanger tubes so that an intersection of the hanger tubes with the
inclined coil.

2. An improved strap support device for supporting inclined evaporator coils
in circulating fluidized bed combustion (CFBC) boilers as substantially
described and illustrated herein with reference to the accompanying
drawings.

The invention relates to an improved strap support device for supporting inclined
evaporator coils in circulating fluidized bed combustion (CFBC) boilers, the device
comprising a steam-cooled membrane wall disposed at the exit of CFBC boiler
cyclone a first super heater coil, and a second reheater coil disposed above at
least one inclined evaporator coil, the evaporator coil being rigidly fixed on the
membrane wall; a plurality of vertical hanger tubes supporting said atleast one
evaporator coil; and a plurality of strap means releasably supporting the hanger
tubes, the strap means being configured to cater for the inclination of the
evaporator coil including a corresponding inclination to the vertical hanger tubes
so that an intersection of the hanger tubes with the inclined coil.