FIELD

The present disclosure relates to the field of mechanical engineering. In particular, the present disclosure relates to the field of fluidized bed reactors. DEFINITION

The expression 'Particulates' used hereinafter in the specification refers to, but is not limited, fine particles, granules, and agglomeration of fine particles.

BACKGROUND

Fluidized bed reactors generally involve the use of particulate removal systems for the removal of high temperature ash that collects on the fluidized bed reactor during the course of operation. Periodic removal of the ash from the fluidized bed is essential to keep the density of the fluidized bed under control. The ash that is removed from the fluidized bed is hot and has a temperature greater than 900°C. Thus, a cooling mechanism is also required to cool the ash to the desired temperature. To this end, particulate removal systems have been developed in the art which facilitate simultaneous removal and cooling of the ash. One such particulate removal system involves the use of a cooling screw conveyor that is in fluid communication with a reactor for receiving the ash from the reactor. The cooling screw conveyor conveys the ash into an ash cooler for further cooling. The cooled ash is then discharged from the ash cooler. A disadvantage associated with this conventional particulate removal system is that the reactor is generally operational at pressures of 500 - lOOOmmWC, requiring special seals for gland sealing of the cooling screw conveyor. At times, even after the use of special seals, water from a water jacket used for cooling of the cooling screw conveyor seeps into the cooling screw conveyor, which results in choking of the cooling screw conveyor. Hence, in order to overcome the aforementioned drawbacks, there is need for a particulate removal system that has a fail-safe operation and that can be easily retro-fitted into the existing setups. OBJECTS

Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.

It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.

An object of the present invention is to provide a particulate removal system for a fluidized reactor which has a fail-safe particulate removal mechanism and is easy on maintenance.

Another object of the present invention is to provide a particulate removal system for a fluidized reactor which can be easily retrofitted in the existing set-ups. Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY

The present disclosure envisages a particulate removal system for a fluidized bed reactor. The particulate removal system comprises a vessel in fluid communication with the fluidized bed reactor for receiving particulates from the fluidized bed reactor. The vessel defines a holdup chamber for containing the particulates. A fluidization device is in fluid communication with the vessel and supplies a fluidization media within the holdup chamber to fluidize the particulates contained therewithin. The fluidized particulates are then discharged from the vessel under the action of the fluidization media. The vessel has a first inlet for receiving the particulates into the holdup chamber. A second inlet is provided for receiving the fluidization media from the fluidization device. An outlet is also provided on the vessel to facilitate discharge of the fluidized particulates from the holdup chamber.

A plurality of nozzles is configured on the vessel for receiving the fluidization media within the holdup chamber to facilitate movement of the fluidized particulates towards the outlet.

The particulate removal system includes an outlet conduit extending from the outlet at an angle ranging from 30° to 45° with respect to a longitudinal axis of the vessel. The outlet conduit facilitates a discharge of the fluidized particulates into a particulate cooler. The particulate removal system includes a water jacket provided in thermal contact with the vessel, the water jacket is configured to provide cooling to the vessel. The water jacket includes an inlet and an outlet to facilitate a continual flow of water therethrough.

The fluidized bed reactor can be one of a circulating fluidized bed boiler, an atmospheric fluidized bed boiler, and a fluidized bed gasifier.

The fluidization device can be a windbox and the fluidization media is compressed air.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING

A particulate removal system of the present disclosure will now be described with the help of the non-limiting accompanying drawing, in which: Fig. 1 illustrates a schematic view of a fluidized bed reactor using a conventional particulate removal system;

Fig. 2 illustrates a schematic view of a fluidized bed reactor using a particulate removal system, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION Fig. 1 illustrates a schematic view of a fluidized bed reactor 100 using a conventional particulate removal system 130 (hereinafter referred to as system 130). The system 130 is used for removal of ash from the reactor 100. A dense bed 120 is formed within the reactor 100 by coal, coal ash, and recycled coal. Air is blown into the reactor 100 from a location operatively below the bed 120 for fluidizing the particles 110. The portion of the reactor operatively below the bed 120, from where the compressed air enters into the reactor 100, is referred to as a windbox 125. Fluidized particles 110 are fed to a cyclone (not shown in figure) where the solid coal particles are separated from the flue gas and re-fed to the bed 120 via a recycled material inlet 115.

The reactor 100 is in fluid communication with the system 130 via an outlet conduit 135 that extends from the bed 120 into a housing 140 of the system 130. The system 130 is a cooling screw conveyor that is defined by the housing 140. The system 130 includes a rotatable shaft 145 having thread formations 150 configured thereon. The rotatable shaft 145 is disposed within the housing 140. The rotatable shaft 145 can be coupled to a driving device such as a motor for causing the rotation of the rotatable shaft 145. A gland seal 155 is disposed on the rotatable shaft 145 adjacent to an operative end of the housing 140. The function of the seal 155 is to maintain the pressure within the housing 140 while at the same time preventing any seepage of water into the housing 140 from a water jacket (not shown in figure). The partially cooled ash exits the system 130 and enters into a particulate cooler 160. The cooler 160 is provided with suitable cooling means to further cool down the ash received from the system 130, for example, through intake of relatively cooler air (air intake shown by arrow). It comprises an air inlet 161, an air outlet 162, a solid discharge outlet 163 and a cooling jacket 164. A disadvantage associated with this conventional particulate removal system 130 is that the reactor 100 is generally operational at pressures of 500 - lOOOmmWC because of which special seals (gland seal 155) are required for gland sealing of the screw conveyor. At times, even after the use of special seals, water from a water jacket used for cooling of the cooling screw conveyor seeps into the cooling screw conveyor, which results in choking of the cooling screw conveyor.

In order to overcome the aforementioned drawbacks, the present disclosure envisages an ash removal system that does not involve the use of any mechanical devices like screw conveyors. The ash removal system of the present disclosure has a fail-safe operation and can be easily retro-fitted into the existing setups. Fig. 2 illustrates a schematic view of a fluidized bed reactor 200 using a particulate removal system 250 (hereinafter referred to as system 250), in accordance with an embodiment of the present disclosure. A dense bed 220 is formed within the reactor 200 by coal, coal ash, and recycled coal. Air is blown into the reactor 200 from a location operatively below the bed 220 for fluidizing the particles 210. Fluidized particles 210 are fed to a cyclone (not shown in figure) where the solid coal particles are separated from the flue gas and re-fed to the bed 220 via a recycled material inlet 215.

The reactor 200 is in fluid communication with the system 250 via an outlet extension 235 that extends from the bed 220. The system 250 comprises a vessel 252 in fluid communication with the fluidized bed reactor 200 for receiving particulates from the fluidized bed reactor 200. The vessel 252 defines a holdup chamber 254 for containing the particulates. A fluidization device 256 is in fluid communication with the vessel 252 and supplies a fluidization media within the holdup chamber 254 to fluidize the particulates contained therewithin. The fluidized particulates are the discharged from the vessel 252 under the action of the fluidization media.

The vessel 252 has a first inlet 252A for receiving the particulates into the holdup chamber 254. A second inlet 252B is provided for receiving the fluidization media from the fluidization device 256. An outlet 252C is also provided on the vessel 252 to facilitate the discharge of the fluidized particulates from the holdup chamber 254.

A plurality of nozzles is configured on the vessel for receiving the fluidization media within the holdup chamber to facilitate the movement of the fluidized particulates towards the outlet. The system 250 includes an outlet conduit 258 extending from the outlet 252C at an angle ranging from 30° to 45° with respect to a longitudinal axis L of the vessel 252. The outlet conduit 258 facilitates a discharge of the fluidized particulates into a particulate cooler 260.

The system 250 also includes a water jacket 262 provided in thermal contact with the vessel 252. The water jacket 262 is configured to provide cooling to the vessel 252. The water jacket 262 includes an inlet 262A and an outlet 262B to facilitate a continual flow of water therethrough.

The particulate cooler 260 is provided with suitable cooling means to further cool down the ash received from the system 250, for example, through intake of relatively cooler air (air intake shown by arrow). The particulate cooler 260 comprises an air inlet 260A, an air outlet 260B, a solid discharge outlet 260C, and a cooling jacket (not shown in figures).

In one embodiment, the fluidized bed reactor 200 is a circulating fluidized bed boiler. In another embodiment, the fluidized bed reactor 200 is an atmospheric fluidized bed boiler. In yet another embodiment, the fluidized bed reactor 200 is a fluidized bed gasifier.

In a preferred embodiment, the fluidization device is implemented using a wind-box. The fluidization media is compressed air.

The operational configuration of the system 250 is now described. The particulates, which include ash, granules and ash agglomerates, enter into the vessel 252 via the outlet extension 235. In the vessel, the fluidization device 256 supplies fluidization media into the holdup chamber 254 of the vessel 252. Fluidization of the particulates takes place in the holdup chamber 254. The plurality of nozzles (not shown in figures) configured on the operative bottom surface of the vessel 252 are so configured so as to allow the supply of the fluidization media into the holdup chamber 254 to fluidize the particulates in a manner that the particulates are directed towards the outlet 252C. The configuration of the outlet 252C and the outlet conduit 258 is such that it facilitates an easy exit of the particulates from the holdup chamber 254.

Water is continuously circulated in the water jacket 262, wherein the inlet 262A and the outlet 262B facilitate the continuous circulation of water in the water jacket. The water jacket 262 facilitates a first stage cooling of the particulates received from the reactor. The particulates are further cooled wherein the particulate cooler 260 provides a second stage cooling to the particulates.

The system 250 of the present disclosure does not involve the use of mechanical devices like screw conveyors. As such, the disadvantages associated with the screw conveyors are overcome by the system 250 of the present disclosure. The system 250 has a simple configuration and can be easily retrofitted into the existing setups.

It should be noted that although the particulate removal system 250 has been described as being used for ash removal purposes in fluidized bed reactors, the application of the system 250 is not just limited to fluidized bed reactors. The system 250 can be configured to use in any application that involves the removal of particulates. TECHNICAL ADVANCES

The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a particulate removal system that:

• has a fail-safe particulate removal mechanism and is easy on maintenance; and

• can easily retrofitted in the existing set-ups. The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary. While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.