US 4,045,162 A · Method of burning granular or pulverulent raw material and kiln plant therefor

Abstract

A method is disclosed for heat treating granular or pulverulent raw material wherein the raw material is directed to a heat exchanger having at least two preheating units operating in parallel, each preheating unit having at least a first preheating stage and at least a lowermost calcination stage to effect a preheating and at least partial calcination of the material. The preheated, at least partially calcined material is fed from the heat exchanger into a kiln and undergoes a sintering process in the kiln. The sintered material is directed from the kiln into a cooling means in which cooling air is directed in a manner to effect a heat exchange between the material and the cooling air. The method further comprises dividing the heated cooling air exiting the cooling means and directing a portion of the heated cooling air to at least one of the calcination stages of the heat exchanger and directing a portion thereof to the kiln in excess of that required to support combustion of fuel in the kiln for the sintering process thereby intensifying the effectiveness of a material cooling zone within the kiln proper. Hot kiln exit gases are directed to at least one of the calcination stages and fuel is directed to at least one of the calcination stages to support combustion with preheated cooling air to provide supplementary heating of the material and at least partially calcining of the preheated material. An apparatus for practicing the inventive method is also disclosed.

Claims33

Dependent claims

A method of heat treating granular or pulverulent raw material by means of a suspension heat exchanger connected to the material inlet end portion of a rotary kiln having a burner pipe extending into the material outlet end portion, said heat exchanger including at least first and second multi-stage string preheating units operating in parallel, each of said units having at least one cyclone preheater stage defining a heat exchange zone in which the granular or pulverulent raw material is brought into heat exchange relationship with hot gases and a lowermost calcination stage for preheating and at least partially calcining the raw material, means to supply raw material to each of said multi-stage string preheater units, means for directing the preheated, at least partially calcined raw material to said material inlet end portion of said rotary kiln for sintering, and cooling means communicating with said rotary kiln defining a heat exchange zone in which the sintered material is brought into heat exchange relationship with cooling air comprising:

(a) directing raw material to said multi-stage string preheating units for preheating and at least partially calcining the material;
(b) feeding preheated, at least partially calcined material from said heat exchanger into said rotary kiln;
(c) sintering the preheated, at least partially calcined material in said kiln;
(d) directing the sintered material from said kiln into said communicating cooling means;
(e) directing cooling air into said cooling means so as to contact said sintered material to effect a heat exchange between the sintered material and the cooling air thereby at least partially cooling the sintered material and at least partially heating the cooling air;
(f) dividing the heated cooling air exiting the cooling means and directing a first portion of said heated cooling air to at least one of said calcination stages of at least a first of said multi-stage preheating units of said heat exchanger and directing a second portion thereof to said kiln in excess of that required to support combustion of fuel in the kiln for the sintering process thereby creating an intensified material cooling zone between the mouth of said burner pipe and the material exit end portion of said rotary kiln;
(g) directing hot kiln exit gases to said calcination stage of at least a second of said multi-stage string preheating units;
and
(h) directing fuel to at least one of said calcination stages of said multi-stage string preheating units to support combustion with at least partially heated cooling air and thereby provide supplementary heating and at least partial calcining of said preheated material.

6 more elements

A method of heat treating granular or pulverulent raw material in the form of cement raw meal by means of a suspension heat exchanger connected to the material inlet end portion of a rotary kiln having a burner pipe extending into the material outlet end portion, said heat exchanger including at least two multi-stage cyclone string preheater units operating in parallel, each of said units having at least an uppermost cyclone preheater stage defining a heat exchanger zone in which the granular or pulverulent raw material is brought into heat exchange relationship with hot gases and a lowermost calcination stage for preheating and at least partially calcining the raw material, means to supply raw material to each of said multi-stage string preheater units, means for directing the preheated, at least partially calcined raw material to the material inlet end portion of said rotary kiln for sintering, and cooling means positioned and adapted to receive sintered material from said rotary kiln and defining a heat exchange zone in which the sintered material is brought into heat exchange relationship with cooling air comprising:

(a) directing the raw material to said multi-stage preheater units for preheating and at least partially calcining the material;
(b) feeding preheated at least partially calcined material from said lowermost cyclone preheater stage of said first string preheater to said calcination stage of said second string preheater;
(c) further calcining said at least partially calcined material in said calcination stage of said second string preheater;
(d) feeding preheated material from the penultimate cyclone preheater stage of said second string preheater to said calcination stage of said second string preheater;
(e) feeding preheated, at least partially calcined material from said calcination stage of said second string preheater to the lowermost cyclone preheater stage of said second string preheater;
(f) feeding preheated, at least partially calcined material from said lowermost cyclone preheater stage of said second string preheater of said heat exchanger to said material inlet end portion of said rotary kiln;
(g) burning the preheated, at least partially calcined material in said rotary kiln;
(h) directing the burnt material from said rotary kiln into said material cooling means communicating with said rotary kiln and adapted to receive material burnt in said rotary kiln for cooling therein;
(i) directing cooling air into said cooling means countercurrent to the flow of material therein and in a manner to effect a heat exchange between said burnt material and said cooling air thereby at least partially cooling said burnt material and at least partially heating said cooling air;
(j) dividing the heated cooling air exiting the material cooling means and directing a first portion of said heated cooling air to said calcination stage associated with said second string preheater and the remaining portion thereof to said rotary kiln to support combustion of fuel therein;
(k) directing a second portion of said heated cooling air to said calcination stage of said second multi-stage string preheater;
(l) directing hot kiln exit gases to the lowermost calcination stage associated with said first string preheater;
(m) directing fuel to said calcination stage of at least said second string preheater and burning said fuel at least in said calcination stage while supporting combustion in said calcination stages of said first and second string preheaters with heated cooling air from said material cooling means and from said kiln;
and
(n) adjustably controlling the flow of heated cooling air through each of said string preheaters so as to divide the heated cooling air passing therethrough such that the heated cooling air passing through said rotary kiln is in excess of that required to support combustion of fuel for the burning process in the kiln thereby creating an intensified material cooling zone between the mouth of said burner pipe and the material outlet end portion of said rotary kiln.

12 more elements

A method of heat treating granular or pulverulent raw material in the form of cement raw meal by means of a suspension heat exchanger connected to the material inlet end portion of a rotary kiln having a burner pipe extending into the material outlet end portion, said heat exchanger including at least three multi-stage cyclone string preheater units operating in parallel, each of said units having at least an uppermost cyclone preheater stage defining a heat exchanger zone in which the granular or pulverulent raw material is brought into heat exchange relationship with hot gases and a lowermost calcination stage for preheating and at least partially calcining the raw material, means to supply raw material to each of said multi-stage string preheater units, means for directing the preheated, at least partially calcined raw material to the material inlet end portion of said rotary kiln for sintering, and cooling means positioned and adapted to receive sintered material from said rotary kiln and defining a heat exchange zone in which the sintered material is brought into heat exchange relationship with cooling air comprising:

a. directing the raw meal to said heat exchanger to effect a preheating and at least a partial calcination of the material;
b. feeding peheated, at least partially calcined raw meal from the first two string preheaters to a rotary kiln;
c. feeding preheated, at least partially calcined raw meal from one cyclone preheater of the last preheater stage of said third string preheater to the calcining stage associated with said second string preheater;
d. feeding preheated, at least partially calcined raw meal from the other preheater cyclone of said third string preheater to the calcining stage associated with said first string preheater;
e. burning the preheated, at least partially calcined raw meal in said rotary kiln;
f. directing the burnt material from the kiln into cooling means communicating with the kiln;
g. directing cooling air into said cooling means in a manner to effect a heat exchange between the burnt material and the cooling air;
h. dividing the heated cooling air leaving the cooling means and directing a portion of said heated cooling air to the calcining stage associated with each of said first two string preheaters and the remaining portion of heated cooling air to said rotary kiln to support the combustion of fuel therein, the remaining portion being in excess of that required to support combustion of fuel for the burning process in the kiln and thereby creating an intensive material cooling zone between the mouth of said burner pipe and the material outlet end portion of said rotary kiln;
i. directing the hot kiln exit gases to the lowermost calcining chamber associated with said third string preheater;
j. directing fuel to each calcining stage of said string preheaters and burning said fuel in said calcining stages while supporting combustion in first and second chambers with preheated cooling air from said cooling means and in the third chamber with excess heated cooling air passing through said kiln;
and
k. controlling the flow of gases through each of said string preheaters and maintaining the flow of gases therethrough at levels capable of maintaining the deposits of alkalis therein at predetermined desired levels.

9 more elements

A method of heat treating granular or pulverulent raw material in the form of cement raw meal by means of a suspension heat exchanger connected to the material inlet end portion of a rotary kiln having a burner pipe extending into the material outlet end portion, said heat exchanger including at least four multi-stage cyclone string preheater units operating in parallel, each of said units having at least an uppermost cyclone preheater stage defining a heat exchanger zone in which the granular or pulverulent raw material is brought into heat exchange relationship with hot gases and a lowermost calcination stage for preheating and at least partially calcining the raw material, means to supply raw material to each of said multi-stage string preheater units, means for directing the preheated, at least partially calcined raw material to the material inlet end portion of said rotary kiln for sintering, and cooling means positioned and adapted to receive sintered material from said rotary kiln and defining a heat exchange zone in which the sintered material is brought into heat exchange relationship with cooling air comprising:

a. directing the raw meal to said heat exchanger to effect a preheating and at least a partial calcination of the material;
b. feeding preheated, at least partially calcined raw meal from each preheater string to a common conduit;
c. feeding the preheated meal through the common conduit into a rotary kiln;
d. burning the preheated, at least partially calcined raw meal in said rotary kiln;
e. directing the burnt material from the rotary kiln into a cooler communicating with the kiln;
f. directing cooling air into said cooler in a manner to effect a heat exchange between the burnt material and the cooling air;
g. dividing the heated cooling air leaving the cooler and directing a portion of said heated cooling air into two of said calcination stages associated respectively with a first two of said preheater strings, and directing the remaining portion of said heated cooling air to said rotary kiln in excess of that required to support combustion of fuel in the kiln for the burning process, thereby creating an intensive material cooling zone between the mouth of said burner pipe and the material outlet portion of said rotary kiln;
h. directing hot kiln exit gases to the calcining stages of said remaining two string preheaters;
i. directing fuel to each calcining stage of said string preheaters and burning said fuel in said calcining stages while supporting combustion in two of said stages with preheated cooling air from said cooler and supporting combustion in the remaining two stages with excess heated cooling air passing through said kiln;
and
j. controlling the flow of gases through each string of said last heat exchanger units so as to control the division of waste cooling air between said rotary kiln and said string preheaters and maintaining the flow of gases therethrough at levels capable of maintaining alkali deposits therein at predetermined desired minimum levels.

8 more elements

A plant for heat treating granular or pulverulent raw material which comprises:

a. a heat exchanger having at least two preheating units operating in parallel relation, each preheating unit having at least a first preheater stage for preheating raw material, and at least a lowermost calcination stage to at least partially calcine the preheated raw material;
b. an inclined rotary kiln communicating with said exchanger and adapted and positioned to receive preheated, at least partially calcined material from said heat exchanger for sintering, said kiln having a material discharge end portion and a burner pipe extending into the material discharge end portion;
material cooling means communicating with the material discharge end portion of said rotary kiln and adapted to receive sintered material discharged from said material discharge end portion of said kiln;
d. means for dividing waste heated cooling air leaving the cooling means and for directing at least a portion of said cooling air to at least one of said calcination chambers of said heat exchanger and a portion to said kiln in excess of the air required to support combustion in the kiln for the sintering process, said excess cooling air thereby creating an intensive material cooling zone between the mouth of said burner pipe and the material outlet end portion of said rotary kiln;
e. means to direct hot kiln exit gases to at least one calcination stage of said heat exchanger;
and
f. means to supply fuel to at least one of said calcination stages to support combustion therein with preheated cooling air to provide supplementary heat for said material and to at least partially calcine said preheated material.

4 more elements

Plant for heat treating granular or pulverulent raw material such as cement raw meal which comprises:

a. a heat exchanger having at least two strings of multi-stage cyclone preheaters operating in parallel relation, each preheater having at least a first cyclone preheater and a last stage formed by a calcination chamber, the calcination chamber being positioned below the last cyclone stage;
b. a rotary kiln communicating with said heat exchanger positioned and adapted to receive preheated, at least partially calcined material from said heat exchanger for sintering the material;
c. a cooler connected to the material discharge end portion of the kiln and adapted to receive sintered material such as cement clinker from said kiln and capable of cooling said sintered material;
d. means for dividing waste heated cooling air leaving the cooling means and for directing a first portion of said cooling air to a first calcination chamber of said heat exchanger associated with a first string preheater, and the remaining portion of said heat cooling air to said kiln to support combustion for the sintering process therein, said cooling air directed to said kiln being in excess of the air required to support combustion in the kiln to thereby create an intensive material cooling zone within said kiln extending from the mouth of the burner pipe to the material discharge end portion of the kiln;
e. means to direct hot kiln exit gases to the calcination chamber of at least one of said other string preheaters of said heat exchanger;
f. means to supply fuel to each calcination chamber to support combustion therein in combination with the preheated cooling air directed to said calcination chambers from said cooler and said rotary kiln respectively, to provide supplementary heat for said material and to at least partially calcine said preheated material therein;
and
g. means adjacent the gas outlet end portion of each string preheater to control the flow of gas through said preheater string to divide according to predetermined proportions, the waste cooling air directed through said kiln and said preheaters.

5 more elements

Plant for heat treating granular or pulverulent raw material in the form of cement raw meal which comprises:

a. a heat exchanger having at least two preheating units operating in parallel relation, the first preheating unit being divided into first and second string preheaters and the second unit forming a third string preheater, each string preheater having a first cyclone preheater stage, at last preheater stage formed of two opposed cyclone preheaters, and a lowermost calcination chamber for at least partially calcining the preheated raw material from the associated string preheater;
b. a rotary kiln communicating with said heat exchanger and adapted and positioned to receive preheated, at least partially calcined material from said heat exchanger for sintering therein;
c. means to direct preheated, at least partially calcined raw material from the first two string preheaters to a common duct and into said kiln for burning therein to form cement clinker;
d. means to direct preheated raw material from the penultimate preheater stage of the first two string preheaters to the calcining chambers associated with said first two string preheaters;
e. means to direct preheated material from the penultimate stage of the third string preheater to the calcining chamber associated with said third string preheater;
f. means to direct preheated, at least partially calcined raw material from at least one of the last cyclone preheaters of said third string preheater to the calcining chamber of said second string preheater, and means to direct preheated, at least partially calcined raw material from the last cyclone preheater of said third string preheater to the calcining chamber of said first string preheater;
g. means to divide waste heated cooling air exiting the cooling means and to direct a portion thereof to the calcining stages of said first and second string preheaters and the remaining portion thereof to the kiln to support combustion in the kiln for the sintering process, the cooling air directed to said kiln being in excess of the cooling air required to support combustion therein to thereby create an intensive material cooling zone between the mouth of the burner pipe of the kiln and the material outlet end portion of the kiln;
h. means to direct the kiln exit gases to the calcining chamber of said third string preheater to support combustion therein;
i. means to supply fuel to each of said calcining chambers to support combustion therein with preheated cooling air so as to provide supplementary heat therein for said material and to at least partially calcine said preheated material therein;
and
j. means positioned adjacent the gas outlet end portion of each string preheater to adjustably control the gas flow through the respective string preheater in a manner to control the division of heated cooling air through said kiln and said string preheaters.

8 more elements

A plant for heat treating granular or pulverulent raw material in the form of cement raw meal which comprises:

a. a heat exchanger having four strings of multi-stage cyclone suspension preheaters operating in parallel relation, each string preheater having at least a first cyclone preheater stage and a lowermost calcination chamber for at least partially calcining the preheated material;
b. means to feed preheated at least partially calcined raw material from each preheater string to a common conduit, the conduit extending into a rotary kiln to feed the material therein for burning into cement clinker;
c. a clinker cooler communicating with the material outlet end portion of the rotary kiln and positioned and adapted to receive cement clinker from the kiln for cooling by means of air directed therein;
d. means to divide the heated cooling air leaving the cooler and for directing a portion of said heated cooling air to the calcination chambers of two of said string preheaters while directing the remaining portion of heated cooling air to the rotary kiln to support combustion of fuel therein, the portion of heated cooling air directed to said rotary kiln being in excess of that required to support combustion of fuel in the kiln for the burning process, said excess air creating a material cooling zone within said rotary kiln extending approximately from the mouth of the kiln burner pipe to the clinker exit portion of said kiln;
e. means to direct hot kiln exit gases to the calcining chambers of the remaining third and fourth string preheaters;
f. means to direct fuel to each calcining chamber of said string preheaters for burning said fuel in said calcining chambers while supporting combustion in two of said chambers with preheated cooling air from said cooler and supporting combustion in the other two stages with excess heated cooling air passing through said kiln;
and
g. means associated with each string preheater for cooling the gas flow through the individual preheater to control the division of waste cooling air between the kiln and the string preheaters.

5 more elements

Dependencies are inferred from the claim text.

Method of burning granular or pulverulent raw material and kiln plant therefor

Life of this patent

Method of burning granular or pulverulent raw material and kiln plant therefor

Life of this patent

Abstract

Claims33