Method and apparatus for controlling the rate of heat release

The subject invention relates to an improved method and apparatus to control the rate of heat release (ROHR) from a reaction zone confined within a chamber, air and fuel having been introduced into said reaction zone to achieve combustion, plural sensors being utilized one sensor adapted to sense ROHR, another to generate a target value for a desired ROHR within a comparator, still another sensor to determine heat generation and transmit it to the comparator, a control means for controlling ROHR of heat generation and connecting said comparator with said control means to achieve coincidence between a target value and said sensed value.

BACKGROUND OF THE INVENTION 
Man made air pollution is a well-known fact. Reducing unnecessary pollution 
is accepted today to be important. A large amount of air pollution is 
generated by man made devices for burning fossile energy. Many attempts 
have been recently made to clean up the exhaust and/or flue gases leaving 
said devices. 
The primary object of the hereinafter described invention is to conduct the 
combustion process so as to dramatically reduce at least some components 
of its final residual products, as, for example, partially burnt 
hydrocarbons and nitrogen oxides. Furthermore, an extraordinarily cheap 
and hence cost-benefit optimized method of controlling said combustion 
process is aimed for and described hereinafter. 
Although the claims are basically self-explanatory for those skilled in the 
art, a short description is provided hereinafter in combination with the 
description of FIG. 1 showing the flow chart of the preferred steps in a 
schematic manner. 
If a predetermined amount of power is demanded for, let us assume X KW, 
designated by Q.sub.1, then, due to efficiency losses, as is well-known, a 
larger amount of power=X times total efficiency, designated by Q.sub.2, 
must be generated. 
In the case of a thermal power generating device, correspondingly 
combustible material, hereinafter called fuel, must be introduced into a 
particular zone where combustion takes place. Essentially simultaneously a 
corresponding amount of oxygen, usually contained in ambient air must also 
be carried towards said zone. The aforesaid zone quoted Z is usually 
arranged in a predetermined combustion space wherein combustion 
hereinafter referred to is to take place. 
Up to now, combustion of burnable products or fuel will conform to natural 
laws whereby an initially smaller rate of heat release, hereinafter call 
ROHR, is followed upon a time axis by a higher ROHR, and, towards the end 
of the oxidation process, when already a majority part of the obtainable 
heat has been released out of a given quantum of burnable components, said 
ROHR might become smaller than at the time, where only about 60% of heat 
has been generated. 
It has been found by the applicant that a controlled ROHR efficiently 
contributes to improve combustion and simultaneously dramatically reduces 
undesired pollution normally generated by conventional combustion 
processes with exhaust gases being permitted to escape in the usual manner 
through a stack. 
It has also been found by the applicant that the most efficient method to 
control the ROHR is to recirculate exhaust gases back into the oxygen or 
oxygen containing air destined for the combustion, hereinafter referred to 
as EGR for exhaust gas recirculation. 
It therefore remains to be determined for a desired ROHR, to measure the 
effective ROHR and then to control said ROHR in a desired manner, 
preferably in combination with a closed loop control means. 
The measurement of a ROHR is preferably realized by at least one, 
preferably temperature related, measurement in a first combustion zone 
quoted A, where combustion, respectively oxidation, takes place. A more 
efficient method is achievable by measuring a second temperature related 
value in a second combustion zone quoted B, preferably following said 
first zone in respect of the heat released already by the oxidizing 
components. The first and second temperature related values, which will be 
referred to in greater detail hereinafter, allow for more accurate 
determination of said ROHR which preferably has to be determined at a 
given time and at the then prevailing and/or given operating conditions of 
such thermal power release. 
The improved method to be revealed herein has been applied to small scale 
thermal power generators having a controllable power output between 300 to 
1000 KW. The obtained improvements have been: 
ca. 50% reduction of the usual losses encountered with state of the art 
heat generating; 
ca. 80% reduction in unburnt hydrocarbons; 
ca. 50% reduction in CO emissions; 
ca. 60% reduction of NO.sub.x emissions; 
reduced control and maintenance costs and 
improved cost-benefit-emission ratio. 
Further improvements are considered possible by those skilled in the art. 
A so-called retrofit onto existing power plants is extremely cheap to 
achieve. 
An apparatus according to the invention is easily produced upon the 
revealed teaching by those skilled in the art. 
The invention will be better understood and further objects and advantages 
thereof will become more apparent from the ensuing detailed description of 
a preferred embodiment taken in conjunction with the drawings.

From a study of the drawing it will be seen that ambient air A. is 
introduced towards an oxidizing zone Z contained in a compartment C and 
into which fuel F is also introduced. Upon oxidation, in other words 
combustion, a quantity Q.sub.2 of exothermic power is generated. This 
exothermic power Q.sub.2 is then conveyed to any suitable means 20, which 
may be tubular or not, which is provided to yield a desired amount of heat 
output Q.sub.1 which generally is smaller than the exothermic power 
Q.sub.2. 
The end products of the combustion process are exhausted gases EG which are 
discharged from compartment C, and eventually the ashes, or other residue 
25, may be conveniently extracted also from compartment C by means known 
in the art. The system includes a series of sensor means preferably in at 
least one first zone, for example, A and/or B, preferably in both zones, 
these sensors are connected to a control, arranged to receive signals, 
measurements and the like from predetermined sensors as for instance; 
______________________________________ 
an air inlet temperature 
sensor 1; 
a chamber temperature sensor 2; 
a flue gas temperature 
sensor 3; and 
a fuel flow related sensor 4 
signal 
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as well as a temperature and/or flow measuring sensor 5, which is arranged 
to sense, for example, the heat output in said means 20. 
More particularly, several sensors, designated by 1, 2, 3, 4, 5, TA, TB and 
eventually others may be connected to a process control means P which 
actuates upon a control device CD which preferably controls the flow rate 
of EGR so to essentially obtain coincidence between a targeted ROHR and 
the effective one. 
The system furthermore includes a first zone condition sensor, as for 
example, a temperature sensor in zone A; a second such or similar sensor 
arranged in zone B, following zone A in respect to the gaseous flow 
direction prevailing in the zone Z. All of said aforesaid sensors are 
connected with said processor P by suitable means drawn schematically and 
denoted by 1', 2', A', B', 3', 4', 5'. The processor is adapted to control 
the aimed for coincidence of prevailing (existing) ROHR and a targeted 
value of the ROHR desired. The control signal being transmitted via 
connecting means 21 toward a control device 22 designed to control the 
flow rate of EGR. Furthermore, an auxiliary blower or pump device 23 may 
be utilized so as to enhance or even generate, if so required, said EGR 
mass flow, required for efficiently controlling the described and 
controlled oxidation process. 
It is also to be understood that said control of said ROHR is achievable by 
introducing towards said combustion zone a controllable flowrate of other 
components such as, lime, chalk and or other desirable material through 
accordingly arranged introducing and flow control means as shown by arrow 
30 in FIG. 1. 
Furthermore, the preferable combination of heavy, this means up to over 50% 
EGR recirculation, together with adequate feeding of other material yields 
into a most desirable effect to thereby avoid nondesired clogging 
tendencies of components within and or above said combustion zone. 
The foregoing relates to a preferred exemplary embodiment of the invention, 
it being understood that other variants and embodiments thereof are 
possible within the spirit and scope of the invention, the latter being 
defined by the appended claims.