Title of Invention

METHOD FOR CONTROLLING THE OPERATION OF A BULK GOOD GRATE COOLER

Abstract

The aim of the invention is to control the operation of a bulk good grate cooler for cooling hot cement clinker, for example, in a process-controlled manner in order to ensure that the volume flows of cooling air (21) in all areas of the cooling grate and/or the residence time in the respective area of the bed of the goods to be cooled can be matched to the cooling requirements occurring in each area. According to the invention, a control intervention is carried out during the operation of the grate cooler with respect to the respective local cooling air volume flow (21) and/or with respect to the respective local speed of conveyance of cooling grid according to the respective bulk good bed height measured per area and/or the bulk good bed temperature and/or the cooling air through-flow resistance such that if a modification occurs in one or several of the measured parameters i.e. bed height, bed temperature and through-flow resistance, the respective local cooling air volume flow (21) and/or the conveyance speed of the grate system is altered.

Full Text

Method for controlling the operation of a bulk good grate cooler Description The aim of the invention is to control the operation of a bulk good grate cooler to cool heated bulk goods such as cement clinkers that are transported from the bulk good inlet connection via suitable conveyors to the chilled goods discharge connection, while the cooling grid and the hot bulk goods distributed onto the grid are supplied with cooling air flow passed from the bottom up, which is regulated by control systems arranged beneath the cooling grid. In a cement clinker production line, the hot cement clinker produced from calcinated raw meal by a rotary kiln is dropped from the discharge point of the kiln onto a cooling unit, usually onto the cooling grate of a grate cooler, onto which the clinker is distributed and transported by suitable conveyors in longitudinal direction to the cooler discharge point. During this process the cooling grate and the hot bulk material layer are essentially ventilated from bottom up by cooling air. In the following, some of the more well-known grate cooler types shall be briefly illustrated. In the case of a reciprocating grate cooler, fixed grate plate sequences and reciprocal grate plate sequences alternate in the course of conveyance, all grate plates are furnished with cooling air vents and are essentially ventilated from bottom up by cooling air. By the joint oscillating movement of all movable grate plate sequences, the hot material to be cooled is transported batch-wise and cooled in the process. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi An alternative to such reciprocating grate coolers is e.g. the grate cooler type EP-B-1 021 692 with which the cooling grate through which cooling air is passed is not movable, i.e. it is set. Numerous rows of adjoining reciprocal bar-shaped thrust elements are arranged above the cooling grate, which are moved between the pre-stroke position in the cooling material conveyance direction and the return stroke position, so that the reciprocating movement of these elements within the cooling bed successively move and cool the material from the cooler start point to its end point. Irregular distribution in the hot bulk material bed in terms of height of bulk material bed, clinker grit size, temperature profile, etc. cannot always be avoided with these types of grate coolers, which in turn also causes irregular cooling. In cooling grate areas with a larger bulk material bed height there is an increase in flow through-flow resistance for cooling air, a decrease in flow velocity and less cooling air is passed through the bulk material bed. In the opposite sense, a low bulk material bed height means a decrease in the through-flow resistance of cooling air and an increase in flow velocity and blowout risk. Too much cooling air is passed through such bulk material bed areas that would require the lowest amount of cooling air. It is therefore known that when implementing a grate cooler to cool hot bulk goods such as cement clinker (EP-B-0 848 646) the specific cooling air quantity should be adjusted automatically in the cooling air flow beneath the cooling grid, so that in the case of an increasing cooling air flow quantity, caused by a decrease in cooling material bed height and flow resistance, the size of the cross section surface of the specific cooling air route is reduced, KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi and conversely, in order to balance a changing decrease in pressure via the bulk material cooling bed in this manner, so that the specific cooling air quantity is no longer dependent on the respective pressure loss or flow resistance of the cooling air in the respective bulk goods bed zone. The well-known mechanical cooling air flow rate control system operates with a weight-loaded swing flap with a horizontal pivot axle, whereby the swing flap automatically restricts the cooling air inflow, the extent of which depends on the existing pressure and flow conditions. If the existing cooling air regulator, which operates with a purely gravitational operating lever weight with upstream flow body, were arranged below the cooling grid in the cooling air flow of the cooling grid zones, and were not fixed but rather, such as a reciprocating grate cooler for bulk goods transport with regulator, movable, the independent function of the regulator would be disrupted by the reciprocating movement, causing the regulating result to be falsified. The above-mentioned independently operating cooling air control system of a grate cooler leads to the control of an essentially constant flow volume of cooling air. The common grate cooler control system does not take into account the individual cooling requirements in various zones of the, in practice, very long and wide grate cooler, which cannot optimally respond with a constant control of the cooling air volume flow. Need-driven changes of the cooling air volume flow within the individual zones of the grate cooler during operation are not possible with the common grate coolers. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi With the EP-A-0 943 881 it is also known that the conveyor velocity of the grate cooler is regulated depending on the height of the cooling material bed as well as the cooling air flow resistance in the inlet area of the grate cooler. This leads to a homogenization of the cooling material bed. The so-called chamber pressure in the air chambers beneath the cooling grate is generally applied when measuring the flow resistance. As the cooling air chambers arranged successively in cooling direction are large, whereby the air chamber size at the end of the cooler generally increases, the measured chamber pressure, even in connection with the measured height of the bulk material bed, is no longer necessarily representative for the current cooling air requirements within one of the zones of the grate cooler. The task of this invention is the operation of a bulk good grate cooler to cool e.g. hot cement clinker in a process controlled manner in order to ensure that the volume flows of cooling air in all areas of the cooling grate and/or the resident time in the respective zone of the cooling bed can be matched to the cooling requirements occurring in each area. This task is solved pursuant to the invention with a procedure in accordance with the properties of claim 1. Beneficial further developments of the invention are specified in the dependent claims. While the known control procedures of the bulk good grate cooler offer the possibility to keep cooling air volume flow essentially constant in all zones of the cooler, the invented procedure for controlling the operation of a bulk good grate cooler offers the possibility, to supply each zone of the grate cooler, depending on the heat content of the hot bulk goods, with cooling air flow in line with the specific cooling requirement. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi According to the invention, a control intervention is carried out during the operation of the grate cooler with respect to the respective local cooling air volume flow and/or with respect to the respective local speed of conveyance of the cooling grid according to the respective bulk good bed height measured per area and/or the bulk good bed temperature and/or the cooling air flow resistance such that if a modification occurs in one or several of the measured parameters i.e. bed height, bed temperature and through-flow resistance, the respective local cooling air volume flow and/or the conveyance speed of the grate system is altered. In this manner the local cooling air volume flow can be increased when there is an increase in the parameters bed height and/or bed temperature and/or through-flow resistance, and conversely, whereas an increase of the bed temperature especially on the upper side of the bed may induce a so-call "red river" formation, to reduce the conveyor velocity of the grate system and vice versa. It is possible to combine the three indicators bulk good bed height, bulk good bed temperature and through-flow resistance, whereby it may involve the measured pressure difference of the specific cooling air flow between lower and upper side of the specific volume flow control system, into one newly combined indicator. However, it is also possible to utilize one or two of the indicators as reference variables and the remaining indicators as correction values for the invention-related control. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi The through-flow resistance of the bulk good bed, especially hot clinker beds, is determined by the bed height, granulometry and the bed temperature. A thermo-scanner or a camera equipped with temperature field detectors can provide information on the actual bulk goods temperature. In this manner, all essential indicators relevant to zone-specific cooling are captured, in order for the grate cooler to operate optimally according to cooling requirements. The requirement-based cooling of the grate cooler can also be realized with a combination of ventilation and conveyor technological measures, i.e. through control interventions on the cooling air volume flow and the conveyor velocity of the grate system in order to align the cooling air volume flow to the cooling quantities occurring in specific zones of the grate cooler. Conveyor velocity is controlled with reciprocating grate coolers via the stroke length and/or the stroke frequency of the movable grate plate sequences. This also applies to a bulk good grate cooler operating by the so-called walking floor principle, with which the individual successively arranged floor elements supporting the cooling good jointly controlled forward, but not jointly, rather they are moved back separately. With the invention procedure, the pressure difference between the lower side and the upper side of the cooling air control system beneath the cooling grate is measured by the length and the width of the zones distributed on the cooling grate. With a grate cooler that transports the bulk good step-wise by the walking floor principle, the bulk good bed height is measured by the neighboring cooling grate tracks in conveying direction and the KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi indicators are used by activating the drives of the specific grate tracks for targeted transverse distribution of the bulk good bed throughout the entire cooler width. In connection with temperature measurements, especially on the upper side resp. the upper layers of the cooling good bed, the so-called "red river" formation can be suppressed for grate coolers to cool red-hot cement clinker. Most of the cooling air control systems implemented in the cooling air inflows operate with control characteristics, that especially render an increase of cooling air demand with increased cooling bed height resp. cooling bed temperature, resp. cooling bed through-flow resistance for each specific cooling air flow. A special feature of the invention allows these control characteristics to be altered during the cooling operation by mechanically adjusting the discharge height of the mobile final control elements within the control casing. The invention and further features and advantages shall be illustrated in detailed on the basis of the schematic exemplary embodiments. They show: Fig. 1: a schematic perspective view of the inlet area of a grate cooler for cooling hot cement clinker produced in a rotary kiln. And Fig. 2: a cooling air control system from which the front part of the control casing has been cut out in order to allow for proper inspection. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi In line with exemplary embodiment of fig. 1, the cooling grate of the grate cooler is composed of numerous successively arranged cooling grate modules in a chessboard manner. Each module possesses numerous oblong, vat-shaped floor elements arranged next to each other in cooler direction that are independently movable between a pre-stroke position 10 in chilled goods conveyance direction and a return stroke position 11, so that the unembodied chilled good stored on the floor elements, is discharged from the discharge connection of a rotary kiln 12 and entered via a transition system 13, on which reciprocating floor elements e.g. by the walking floor principle transport it step-wise through the cooler. The actuation of the individual vat-shaped floor elements of the cooling grate modules is executed from beneath the cooling grate via push frames that are support by castors to which hydraulic cylinders are attached, in a manner that the floor elements are jointly moved forward, but not jointly, rather they are temporally moved back separately. The longitudinal tracks of the cooling grate module sequences are identified by the numbers 15, 16, 17, 18, 19, 20 etc. The floor elements of all cooling grate modules are constructed as hollow bodies. In the cross section, they display an upper side that supports the cooling good and allows for passing of cooling air from bottom to top and a closed lower side arranged at a distance to prevent cooling good grate sinkage. The lower sides of the floor elements possess numerous longitudinally distributed cooling air vents to which the cooling air controls are flanged, as shown in the exemplary embodiment in figure 2. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi The automatically acting cooling air control system of fig. 2 possesses a control case 22 and a therein contained internal body 23. The e.g. disk-shaped or cup-shaped internal body 23 is in opposition to the effects of a reset force, in which the, with cooling air 21 saturated, control case 22 is guided reciprocally and translationally as final control element. With increasing height of the internal body 23 filled with cooling air within the control case 22, the remaining cross section available for the cooling air decreases, and vice versa. A change in pressure loss in the cooling air flow above the internal body 23 resp. a change in the pressure difference between the upper and the lower side of the internal body 23 causes an axial shift of the internal body 23 and thus a change in cooling air volume flow. The control case 22 of fig. 2 possesses numerous vents 24 distributed along the height and the volume of the case, whereby the cooling air can pass through these vents into the inside of the case 22 and then exit the case from its upper side 25, that is flanged onto the lower side of the cooling grate module of figure 1. A reset spring can trigger at the center of the internal body 23 functioning as final control element. During the operation of the grate cooler, a control intervention is carried out during the operation of the grate cooler with respect to the respective local cooling air volume flow 21 and/or with respect to the respective local speed of conveyance of the cooling grate according to the respective bulk good bed height measured per zone and/or the bulk good bed temperature and/or the cooling air flow resistance such that if a modification occurs in one or several of the measured parameters i.e. bed height, bed temperature and through-flow resistance, the respective local cooling air volume flow and/or the conveyance speed of the grate system is altered. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi The cooling air volume flows in the specific cooling grate zones 15 to 20 and/or the conveyance velocity of the grate cooler are regulated in line with heat content of the bulk good bed in a cooling requirement and process controlled manner. The control characteristics of the cooling air control system 22 portrayed in figure 2 can be adjusted and modified so that the preload force of a reset spring 26 supported in the translationary mobile internal body 23 can be changed and adjusted by activating the positioning mechanism 27. KHD Humboldt Wedag AG 02 11 2005 H 04/010 PCT T-PP Chr/Bi Method for controlling the operation of a bulk good grate cooler Claims 1. The operation of a bulk good grate cooler to cool heated bulk goods such as cement clinkers that are transported from the bulk good inlet connection via suitable conveyors to the chilled goods discharge connection, while the cooling grate (15-20) and the hot bulk goods distributed onto the grate are supplied with cooling air flow (21) passed from the bottom up, which is regulated by control systems (22) arranged beneath the cooling grate, is characterized in that, during the operation of the grate cooler, a control intervention is carried out during the operation of the grate cooler with respect to the respective local cooling air volume flow (21) and/or with respect to the respective local speed of conveyance of the cooling grate according to the respective bulk good bed height measured per zone and/or the bulk good bed temperature and/or the cooling air flow resistance such that if a modification occurs in one or several of the measured parameters i.e. bed height, bed temperature and through-flow resistance, the respective local cooling air volume flow and/or the conveyance speed of the grate system is altered. 2. Procedure as in claim 1, characterized in that, the parameters bulk good bed height, bed temperature and through-flow resistance are measured on the basis of the length and width of the zones (15-20 and A-E) distributed along the cooling grate. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi 3. Procedure as in claim 1 or 2, characterized in that, the cooling air volume flows of the specific cooling grate zones (1 5-2 0 and A - E) and/or conveyor velocity of the grate cooler are regulated in a process-controlled manner in line with warmth dependent cooling requirement. 4. Procedure as in claim 1, characterized in that, with an increase of the parameters bed height and/or bed temperature and/or through-flow resistance the specific local cooling air volume flow (21) is increased and conversely, with an increase of bed temperature, especially the upper side of the bed, the conveyor velocity of the grate system is reduced, and vice versa. 5. Procedure especially as in claim 1, characterized in that, the control characteristics of the cooling air volume flow control system (22) can be altered during the cooling operation, whereby the control characteristic reflects an increase in cooling requirements with an increased cooling good bed height resp. cooling good bed temperature resp. an increase in cooling good through-flow resistance for the specific cooling air flow (21). 6. Procedure as in claim 5, characterized in that, the control characteristics are applied for the control of essentially constant cooling air volume flows. 7. Procedure as in claim 1, characterized in that, the pressure difference between the lower side and the upper side the cooling air control system beneath the cooling grate, measured by the length and the width of the zones (15-20 and A - E) distributed on the cooling grate is representative for the cooling air through-flow resistance. KHD Humboldt Wedag AG 02.11.2005 H 04/010 PCT T-PP Chr/Bi 8. Procedure as in claim 1, characterized in that, with a grate cooler that transports the bulk good step-wise by the walking floor principle, the bulk good bed height is measured by the neighboring cooling grate tracks (A - E) in conveying direction and the indicators are used by activating the drives of the specific grate tracks (A - E) for targeted transverse distribution of the bulk good bed throughout the entire cooler width. 9. Procedure as in claim 5, characterized in that, the modification of the control characteristics of the cooling air volume flow control system (22) is initiated by a mechanical change in position of the mobile final control elements (23) within control system case saturated by cooling air.

Documents:

2508-CHENP-2007 CORRESPONDENCE OTHERS 18-07-2013.pdf

2508-CHENP-2007 AMENDED CLAIMS 01-09-2014.pdf

2508-CHENP-2007 CORRESPONDENCE OTHERS 17-07-2014.pdf

2508-CHENP-2007 EXAMINATION REOIRT REOKY RECEIVED 09-06-2014.pdf

2508-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 01-09-2014.pdf

2508-CHENP-2007 FORM-13 27-08-2014.pdf

2508-CHENP-2007 FORM-3 09-06-2014.pdf

2508-CHENP-2007 OTHER PATENT DOCUMENT 01-09-2014.pdf

2508-CHENP-2007 OTHER PATENT DOCUMENT 09-06-2014.pdf

2508-CHENP-2007 OTHERS 09-06-2014.pdf

2508-CHENP-2007 AMENDED CLAIMS 09-06-2014.pdf

2508-chenp-2007-abstract.pdf

2508-chenp-2007-claims.pdf

2508-chenp-2007-correspondnece-others.pdf

2508-chenp-2007-description(complete).pdf

2508-chenp-2007-drawings.pdf

2508-chenp-2007-form 1.pdf

2508-chenp-2007-form 26.pdf

2508-chenp-2007-form 3.pdf

2508-chenp-2007-form 5.pdf

2508-chenp-2007-pct.pdf

2545-2007_Claims.pdf

Form 13.pdf

Petition 2508-CHENP-2007.pdf