FIELD OF INVENTION
This invention relates to integrated gasification based power generation; especially pressurized fluidized bed gasification based systems used for any grade of coals,
BACKGROUND OF ART
Combined cycle fs increasingly being used to generate electricity through integrated gasification. Such combined cycles are capable of using various grades of low calorific value and high contents coals.
In a refractory lined pressurized fluidized bed gasifier the air and steam mixture is introduced through a distributor located at bottom of the gasifier. Coal is continuously injected to the gasifier through ejector using compressed air. Coal gas caTTed 'fuel gasr is produced due to the chemical reaction of coal with air and steam. The fly ash and unburnt carbon particles in fuel gas are separated by the serially arranged^ cyclones. Part of the fly ash is recycled back to gasifier, remaining is cooled in ash coolers and collected in ash receivers. The coal gas at the exit of the cyclone is cooled in a Heat Recovery Boiler (HRB). The gas is further cooled in the gas cooler while superheating the saturated steam of FfRB. Fart of the superheated steam is utilized for gasification process and the rest expands in the steam turbine to generate electricity. The gas

is further processed in the gas cleaning systems and admitted to the gas turbine combustion chamber to generate electricity.
During the gasification process, for a particular load, to maintain the bed height the bed ash is extracted from the bottom of the gasifier. Maintaining the gasifier bed height is vital because it determines the fluidization velocity, better fluidization, better composition of fuel gas with adequate quantity, and reduction in the over loading of equipment in the down stream of gas path with fly ash.
STATE OF CURRENT ART
In a pressurized fluidization bed gasifier the bed is removed by using rotary bucket type extractors through ash coolers. Part of the fly ash is recycled back to gasifier, remaining is cooled in ash coolers and collected in ash receivers. The double shelled ash cooler has a number of smaller diameter tubes staggerly arranged and welded in the inner shelT with suitable pitch. Water tubes are grouped by a number of baffle plates welded only in the inner shell have a zigzag water path. Required quantity of water is admitted between shells and flowing through the tubes in zigzag manner and the hot ash is faTling/ flowing in between the tubes and gets cooled. Often problems are encountered with failure of tubes, due to absent of flow of required quantity of water in the tubes.
The reason being, there are gaps between baffle plates and the outer allowing water to escape instead of flowing only through the tubes,
OBJECT OF INVENTION
The object of this invention is to propose a pressurized ffuidization bed gasification based system having a high temperature bulk solid cooler to cool the bed ash and fly ash continuously by ensuring flow of water only through the tubes of the ash cooler.
A further object of this invention is to propose a pressurized fluidization bed gasifier based system having a high temperature bulk solid cooler which avoids firing of ash in the receiver or in hopper, to avoid failure of pressure vessels due to over heating and also to dispose the ash to atmosphere with highest safety.
A still further object of this invention is to propose a pressurized ffuidization bed gasifier based system having a high temperature bulk solid cooler which increases the life of down stream equipment like receiver, lock, hopper etc.
Yet a further object of this invention is to propose a pressurized fluidization bed gasifier based system having a high temperature bulk solid cooler which has no rotating parts engaged in this system.
DESCRIPTION OF INVENTION
According to this invention there Is provided a high temperature bulk solid water for a pressurized fluidized bed gasification based systems comprising: -
1. an outer shell;
2. an Inner shell disposed In their said outer shell & In a
spaced relation to said outer shell;
3. a plurality of water tubes disposed In their said Inner shell;
4. a plurality of baffle plates;
5. a water inlet & outlet.
In accordance with this invention the costing water tubes are oriented at an angle of 5 to 14° to the horizontal.
Further, a vertical plate Is provided T their said Inner shtl]. DESCRIPTION OF INVENTION W.R.T. DRAWINGS
Further objects and advantages of their invention will be more apparent from the ensuing description when read In conjunction with the accompanying drawings and wherein: -
Fig. 1 shows a sectional view of the cooler of the pressure. When the required quantity of cold water at ambient temperature is admitted in between the outer shell 01 [refer Fig. 1} and inner shell 02 through inlet pipe 06, water flow takes place in a zigzag path, through a group of stainless steel tubes 03, outer diameter varying from 10mm to 25mm, welded in the inner shell with suitable pitch and slope & ranging from 5T to 14°. The cold water absorbing heat from the bulk solids and the hot water leaves out through outlet pipe OT. a number of baffle plates 04 are designed in such a way (extended beyond the outer shell) and arranged in a fashion so that water flows only through the tubes in a zigzag path. Vertical plates 05" also help to route the water path. The hot bulk solids 08 are falling from top of the cooler, get cooled and leave at the bottom.
The invention has additional features in th arrangement of baffle plates, vertical plates, and the application for hot bulk solids at higher pressure.

WE CLAIM; -
1. A high temperature bulk solid water for a pressurized fTuidfzed beol
gasification based systems comprising: -
1. an outer shell
2. an inner shell disposed in their said outer shell & in a
spaced relation to said outer shell;
3. a plurality of water tubes disposed in their said inner shelj;
4. a plurality of baffle plates;
5. a water inlet & outlet.

2. A high temperature bulk solid water cooler as claimed in claim 1,
the costing water tubes are oriented at an angle of 5 to 14^ to the
horizontal.
3. A high temperature bulk solid water cooler as claimed in claim I, a
vertical plate is provided I their said inner shell.
4. A high temperature bulk solid water cooler for a pressurized
fluidized bed gasification based system substantially as herein
described & illustrated.