US3686773A

US3686773A - Material cooler

Info

Publication number: US3686773A
Application number: US146368A
Authority: US
Inventors: Paul Schreiner
Original assignee: Fuller Co
Current assignee: Fuller Co
Priority date: 1970-05-29
Filing date: 1971-05-24
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29
Also published as: DE2026261B2; AT301431B; DE2026261A1

Abstract

A cooler for hot material such as cement clinker which includes a plurality of superimposed heat exchanger sections. Each of the sections includes an arrangement such as a series of alternately fixed and movable grates for moving material from the inlet of the section to the outlet of the section. A material breaker is positioned between the initial heat exchanger section and the second heat exchanger section. A material lock is provided between each section. The material is cooled by air flowing upwardly through the grate and material. Cooling air is introduced into a plenum chamber beneath the last section, flows upwardly through the material in that section and through the material in the succeeding sections and is eventually sent to the furnace as heated combustion air. Before passing through the initial section, water may be sprayed into the air to cool the same.

Description

United States Patent Schreiner Aug. 29, 1972 [54] MATERIAL COOLER [72] Inventor: Paul Schreiner, 207 Gross-Han- Primary Examiner-Carroll Domy sdorf, Germany Attorney-Jack L. Prather and Frank H. Thomson [73] Assignee: Fuller Company [57] ABSTRACT [22] Filed: May 1971 A cooler for hot material such as cement clinker Appl. No.: 146,368

which includes a plurality of superimposed heat exchanger sections. Each of the sections includes an arrangement such as a series of alternately fixed and movable grates for moving material from the inlet of the section to the outlet of the section. A material breaker is positioned between the initial heat exchanger section and the second heat exchanger section. A material lock is provided between each section. The material is cooled by air flowing upwardly through the grate and material. Cooling air is introduced into a plenum chamber beneath the last section, flows upwardly through the material in that section and through the material in the succeeding sections and is eventually sent to the furnace as heated combustion air. Before passing through the initial section, water may be sprayed into the air to cool the same.

5 Claims, 1 Drawing Figure adv PATENTEmusze I972 3.686; 773

IINVENTOR PAUL saws/-51? TORNEY BACKGROUND OF THE INVENTION This invention relates to a cooler for hot or burning material with a large number of cooling grates divided into a plurality of grate sections through which the material passes one after the other, whereby the cooling air of the first grate section can be conducted into the burning furnace as combustion air. The invention is particularly suited to cooling cement clinker discharged from a rotary kiln.

In coolers of the kind to which the present invention relates, only the cooling air of the first grate section is supplied to the furnace as secondary air, or the cooling air first flows through the second cooler section in order to chill the hot material which is located there, and it then flows through the first cooler section from which it is conducted to the furnace. In the first case, the cooling air of the second grate section is blown off into the atmosphere, which results in heat losses and necessitates the use of dust collection apparatus before being discharged to atmosphere. In the second case, the cooling air flows through the two grate sections in a direct current, i.e., through the hottest material first and then through the cooler material. For heat management reasons it would be better to have an arrangement in which the cooling air flows through the succeeding sections in a countercurrent, i.e., through the cooler material first.

The accomplishment of this objective in existing coolers is essentially prevented by three factors. First of all, the cooling air must, from one section to the next, run through a blower, if locks for the material are to be avoided; this requires an expensive intermediate removal of dust from the cooling air or it will lead to a considerable wear and tear on the blower. Second, if the use of such blowers is to be avoided, the material must run through locks from one section to the next, which is impossible not only because of the high temperature of the material after the first grate section but also because of the differing grain size of the material. Third, the cooling air, which is conducted through the grates in a direction countercurrent to the flow of material, reaches the first grate section with an already comparatively high temperature, so that it cannot achieve the cooling affects required for the protection of the grate material used in the first stage.

SUMMARY It is the principal object of this invention to provide a novel cooler for hot material which overcomes the above mentioned problems.

It is a further object of this invention to provide a cooler for hot material which recuperates at least some of the heat of the hot material and substantially eliminates the necessity of venting cooling air to atmosphere and thereby substantially reduces heat losses and the use of dust collectors which accompanies such venting.

The invention is intended, in spite of the conditions described, to create a cooler for burning material of the type mentioned in the beginning, where the cooling medium can flow through the grate sections countercurrent to the flow of material.

The solution according to the invention consists in the combination ofthe features in that:

a. The known heat exchanger design is used, where several grate sections, following each other in the direction of movement of the'burning material, have the same cooling air current flow through them in reverse sequence and where locks for the material are arranged between successive grate sections;

b. That a material breaker is arranged between the first and second grate sections, looking in the direction of movement of the material;

0. That devices are provided for the introduction of water into the cooling air current before the latter flows through the first grate section.

These features supplement each other in such a manner that one feature, each, is made possible only through the presence of the other features. Thus it is necessary for the use of locks between the individual grate sections to make sure that the material is broken in connection with the first grate section. The arrangement of these locks makes it possible to conduct the cooling air current through all grate stages without intermediate blowers. We can prevent the overheating of the first grate section, due to insufficient cooling of the air heated up in the other grate sections, by introducing water before the first grate section. Due to this water introduction, as a result of which the air temperature is reduced, we can attain such a low material temperature at the end of the first stage that a material breaker can be inserted at this place. In this way we can close the circle of mutually conditioning features. The cooler design according to the invention is facilitated by the fact that a very specificplace in the cooler has been selected for this introduction of water.

The presence of the locks between the successive grate sections makes it possible in each case to connect the under-chamber of a grate section, preceding in the direction of material movement, directly with the upper chamber of the following grate section. A particularly advantageous and compact design for the cooler emerges whenever more than two grate sections are arranged in a zig-zag fashion above each other.

The devices for the introduction of the water are best made in the form of spray nozzles positioned in the upper chamber of the second grate section.

The cooling in the first grate section and especially the adequate cooling of the grate in the highly-stressed first part of this grate section, as well as the chilling of the material dropped from the furnace can be achieved if a first part of the first grate section is hit with cold cooling air.

BRIEF DESCRIPTION OF THE DRAWING The invention is described in connection with the annexed drawing wherein the single FIGURE is a schematic longitudinal.cross-section of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Three heat exchanger or

grate sections

1, 2 and 3, which best belong to a design with alternatingly stationary and moving air permeable grate plates and of which the uppermost and first grate section is best designed in an inclined fashion such as the heat exchanger shown in US. Pat. No. 2,431,799 are arranged above each other in a zig-zag fashion. The

cooler sections

2 and 3 are preferably horizontal coolers such as those shown in U.S. Pat. Nos. 2,846,778; 3,197,887; or 3,358,385. The beginning of the first grate sections 1 lies under the shaft 4 into which opens the discharge end 5 of a furnace such as a rotary kiln. A breaker 6 of any suitable design that can be operated at the temperatures prevailing there is positioned at the end of the first grate section.

The material dropped by the breaker is moved into a material lock shaft 7 which is made between the outside wall 8 and a separating wall 9. The separating wall 9 has a slide member 10 positioned at its lower end which can be adjusted for regulatory purposes during operation of the apparatus or can be fixed. Two level measurement members 11 are positioned in the lock shaft 7 of which the lower one is place so high that the lock effect is still guaranteed when the filling level is just slightly below this member.

The lock shaft 7 opens at the beginning of grate section 2. A material lock shaft 12 is positioned at the discharge end of section 2 and is likewise equipped with level measurement members 13 similar to members 11. The partition 14 which forms part of the shaft 12 is equipped with a slide element 15 which corresponds to the element 10 in terms of arrangement and operation.

The shaft 12 empties above the beginning of grate section 3 which terminates in a third lock shaft 16 which is also equipped with level measurement members 17 which control discharge members indicated in the drawing as double butterfly valves 18 so that the lock shaft 16 will constantly be so filled that the lock effect will be guaranteed. If the force-controlled discharge members themselves have enough of a lock effect, the plug-effect of the material which accumulates in shaft 16 can be reduced or eliminated.

Cooling air is supplied to the lower chamber of grate 3 by means of a blower 19. This lower chamber is limited on the underside by funnels 20 which catch the material falling through the grate and these funnels are likewise provided with discharge locks which are indicated in the example as double butterfly valves 21 which, in turn, can be controlled by level measurement members 22. If desired, the lower chamber can be divided into compartments by suitable partitions with a separate blower supplying cooling air to each compartment.

The level measurement members, which in each case are arranged in pairs, work in such a manner that the material is discharged as soon as the upper level measurement member has been reached, while the discharge operation is stopped as soon as the filling level drops to the lower level measurement member.

The

level measurement members

11 and 13 in

look shafts

7 and 12 serve to regulate the material level in such a manner that there will always be enough filling material in these layers. They can act either upon the

slide members

10 and 15, respectively, and/or upon the drive of the grate sections 2, respectively 3, for the purpose of adjusting their speed and thereby adjusting the rate at which material is moved through the heat exchanger sections. The lock shafts insure that cooling air flows through the grates and material supported thereon and is not short-circuited around the material.

The cooler housing, which encloses the three grate sections, is completely closed with the exception of shaft 4. The pressure of the cooling air, conveyed by blower 19, drops in three stages while passing through

grate sections

3, 2, and 1, until it has reached in the upper chamber of grate section 1 the pressure at the furnace outlet which is near atmospheric pressure.

By means of partition 23 in the lower chamber of the first grate section 1, the first pan of the first grate section is protected against being hit by the general cooling air current. This grate section, in the meantime, is connected to a separate blower 24 which supplied this grate section with cooling air so that this highlystressed part of the first grate section will be effectively cooled and so that the materiaL dropped by the furnace into this area, will experience a rapid temperature reduction. This feature will reduce the tendency of the initial grates of the section 1 to fail before the other grates of that section due to exposure to extremely high temperature material discharged from the furnace.

Water spray nozzles 25 run into the lower chamber of the first grate section. The injected water gives the cooling air current the moisture content desired for the secondary air and furthermore so reduces the temperature of the cooling air current that sufficient cooling is achieved in the first grate section. The spraying of water can be regulated as a function of the secondary air temperature and/or the clinker terminal temperature. Both temperatures are reduced as a result of the injection of water.

I claim:

1. A cooler for hot material including a plurality of heat exchanger sections through which material to be cooled sequentially passes whereby cooling air which is heated by the hot material can be returned to a furnace as combustion air, the improvement comprising:

a plurality of flow connected heat exchangers each including means for supporting the material to be cooled and advancing said material through the heat exchanger;

means for supplying cooling air for sequential passage through the material in each heat exchanger whereby cooling air passes through the coolest material first and the hottest material last;

material lock means between each heat exchanger;

breaker means positioned between at least two heat exchangers; and

means for introducing water into the cooling air before it passes through the hottest material.

2. A cooler according to claim 1 wherein said heat exchangers are superimposed upon each other and each includes a lower chamber and an upper chamber separated by said means for supporting the material and the lower chamber of one heat exchanger is directly connected with the upper chamber of the following section.

3. The cooler according to claim 2 wherein there are at least three heat exchangers arranged above each other so that material flows through the cooler in a zigzag pattern.

4. The cooler according to claim 1 wherein said means for introducing water includes means for spraying water into the cooling air just prior to the cooling air passing through the heat exchanger containing the hottest material.

5. The cooler according to claim 1 further comprising means for supplying additional cooling air directly to the heat exchanger which receives the hot material to be cooled at the point nearest the point hot material flows into the cooler from a furnace. 5

Claims

1. A cooler for hot material including a plurality of heat exchanger sections through which material to be cooled sequentially passes whereby cooling air which is heated by the hot material can be returned to a furnace as combustion air, the improvement comprising: a plurality of flow connected heat exchangers each including means for supporting the material to be cooled and advancing said material through the heat exchanger; means for supplying cooling air for sequential passage through the material in each heat exchanger whereby cooling air passes through the coolest material first and the hottest material last; material lock means between each heat exchanger; breaker means positioned between at least two heat exchangers; and means for introducing water into the cooling air before it passes through the hottest material.

3. The cooler according to claim 2 wherein there are at least three heat exchangers arranged above each other so that material flows through the cooler in a zig-zag pattern.

5. The cooler according to claim 1 further comprising means for supplying additional cooling air directly to the heat exchanger which receives the hot material to be cooled at the point nearest the point hot material flows into the cooler from a furnace.