SE542301C2 - Method for controlling distribution of air factors in industrial reactors by proactive oxygen and temperature measurements - Google Patents

Abstract

A method for detecting imbalances in an industrial reactor comprising a reaction chamber, wherein the presence of oxidation and reduction zones (2, 3) in the reaction chamber (1) of the industrial reactor is determined by measuring and analyzing oxygen concentration 5 and temperature at measuring points (8) arranged inside the reaction chamber (1) in the industrial reactor and based on the measurements creating a an oxygen distribution profile and a temperature profile in the industrial reactor. The method may be used to minimize the production of environmentally harmful emissions such as NOx and CO in industrial processes without using chemicals. The method may be used to improve energy 10 conversion efficiency in industrial boilers, optimizing combustion and industrial processes, continued monitoring and optimizing of the air factors in industrial boilers, reducing noncombusted fuels, reducing corrosions in industrial boilers.

Description

METHOD FOR CONTROLLING DISTRIBUTION OF AIR FACTORS IN INDUSTRIAL REACTORS BY PROACTIVE OXYGEN AND TEMPERATURE MEASUREMENTS TECHNICAL FIELD The disclosure pertains to a method for detecting imbalances in an industrial high temperature reactor comprising a reaction chamber. The method may involve diagnosing the working condition of an industrial reactor and boiler. A method for counteracting imbalances in an industrial reactor is also disclosed herein. The methods as disclosed herein are applicable to any high-temperature industrial reactors, such as boilers, furnaces, etc.

BACKGROUND OF THE INVENTION The major challenges for both developed and developing countries are problems associated with climate changes. Emission reduction of greenhouse gases and other environmentally harmful emissions such as NOx and CO are of highest priority.

The climate challenges intensify rapidly due to megatrends such as population growth, industrialization, economic growth, urbanization, improved living standards etc.

In almost all industrial high temperature reactors the concentration of oxygen show imbalance due to a number of thermodynamics and operative factors. Such imbalances have been found to cause a number of negative effects on a combustion process or other high-temperature process in an industrial reactor such as increased emissions of NOx and CO, lowered energy and energy conversion efficiency, corrosion problems, noncombusted fuel, etc.

An object of the present invention is to provide methods of determining the presence of imbalances in industrial reactors. A further object may be to offer methods of counteracting continued monitored imbalances in industrial reactors.

This invention offers a new thermodynamic model for high temperature chemistry in industrial reactors. The innovation based on this new high temperature thermodynamic model aims to improve industrial reactor processes by providing one or more beneficial effects including reducing environmentally harmful emissions such as NOx, CO, improving energy conversion efficiency in industrial reactors, optimizing reactors in industrial processes, continued monitoring and immediate optimization of the air factors in industrial reactors, reducing the amount of non-combusted fuels, reducing corrosion in industrial reactors, etc.

SUMMARY OF THE INVENTION One or more of the above objects may be achieved with a method in accordance with claim 1. Further embodiments are set out in the dependent claims, in the following description and in the drawings.

Disclosed herein is a method for detecting imbalances in industrial reactors comprising reaction chambers. The formation and presence of oxidation and reduction zones in the reaction chamber of the industrial reactor is determined by presented novel approach of measuring and analyzing oxygen concentration and temperature inside the reaction chamber in the industrial reactor and making an oxygen distribution profile and a temperature profile in the industrial reactor.

The formation of oxidation zones and reduction zones in the industrial reactor may be counteracted by redistribution of oxygen in the reaction chamber using the oxygen distribution profile of the oxygen concentration and the temperature in the industrial reactor as a basis for supplying or removing oxygen where and when needed in order to optimizing the oxygen concentration in the reaction chamber from a thermodynamic viewpoint.

The method provides conditions to minimize NOx and CO production, optimizing energy conversion efficiency, optimizing combustion and industrial processes, continuous monitoring and optimizing the air factor, reducing non-combusted fuels, reducing corrosion in industrial boilers.

The formation of oxidation zones and reduction zones in the industrial reactor may i.e. be counteracted by regulating air supply to the reaction chamber based on the oxygen distribution profile of the oxygen concentration and/or the temperature in the industrial reactor. An elevated or lowered temperature detected at a location in the reaction chamber is an indication that an oxidation zone or a reduction zone is emerging or exists in that location. Accordingly, redistribution of oxygen to or from a location with a deviant temperature may be required even if the measured oxygen content or air factor is within predetermined limits.

The oxygen concentration and the temperature may be measured at different heights inside the reaction chamber.

The oxygen concentration and the temperature are measured adjacent to a wall of the reaction chamber. It has been found that oxidation zones and reduction zones often appear close to the walls of the reaction chamber.

The oxygen distribution and the temperature in the reaction chamber may be continuously monitored.

The air supply to the reaction chamber may be continuously adapted in response to changes in the oxygen distribution profile and the temperature profile.

The method as disclosed herein may be an automated method.

In one embodiment the energy conversion efficiency of the industrial reactor is optimized.

In one embodiment the corrosion in the reaction chamber is minimized.

In one embodiment the amount of non-combusted fuel in the reaction chamber is minimized.

The efficiency of the method as disclosed herein may be verified by one or more of: - monitoring production of NOx and CO, - monitoring energy conversion efficiency, - monitoring combustion and industrial processes - monitoring corrosion in the reaction chamber, - monitoring the amount of non-combusted fuel in the industrial reactor.

The method as disclosed herein may be used to minimize the production in the industrial reactor of environmentally damaging gases such as NOx and CO. By continuously measuring the amount of oxygen and the temperature at selected locations inside the reaction chamber, thereby detecting the emergence of oxidation zones (zones of high temperature and high oxygen content) and reduction zones (zones of low temperature and low oxygen content), the formation of oxidation zones and reduction zones can directly be counteracted by redistributing oxygen in the reaction chamber of the industrial reactor. Redistribution of oxygen is made to optimize the oxygen concentration in the reaction chamber and to maintain optimal reaction conditions throughout operation of the industrial reactor.

As set out herein, continuous monitoring, mapping and evaluation of the oxygen concentration and the temperature inside the reaction chamber of the industrial reactor offers a tool to continuously counteract the creation of oxidation zones and reduction zones by redistributing oxygen in the reaction chamber and thereby not only lowering the production of environmentally damaging gases such as NOx and CO, but also increasing the energy conversion efficiency of the industrial reactor, minimizing corrosion in the reaction chamber and ascertaining that uniform reaction conditions are maintained in all parts of the reaction chamber. Thereby it is possible to minimize the amount of nonreacted material in the reaction chamber, e.g. the amount of non-combusted fuel in the reaction chamber.

As disclosed herein, the method of the invention offers a way to monitor and control the reaction conditions in a high-temperature industrial reactor. The method is a clean method and is based on thermodynamic principles, which means that the appearance of oxidation zones and reduction zones can be avoided without the need for adding chemical reduction or oxidation agents for counteracting the emergence of the detrimental oxidation and reduction zones.

The oxygen distribution profile and the temperature profile of the industrial reactor may be used to diagnose the condition of the reactor during daily operation.

The present invention has verified the formation of oxidation and reduction zones inside high-temperature industrial reaction chambers and that the formation of oxidation and reduction zones inside an industrial reaction chamber is the main source for high production of environmentally harmful gases such as NOx and CO. As set out herein, problems such as corrosion and reduced energy conversion efficiency are also related to the formation of oxidation and reduction zones.

Therefore it is of outmost importance to prevent the formation of oxidation and reduction zones in industrial reactors and thereby diminish the problems associated with the thermodynamic processes associated with the formation of oxidation and reduction zones.

The oxidation zones are oxygen enriched and reduction zones are oxygen depleted. The oxidation zones show higher temperature compared to reduction zones. These zones are quite stable and can persist for long periods of time. The above mentioned problems associated with the occurrence of oxidation and reduction zones will remain unless it is countered.

The oxidation and reduction zones may or may not coexist simultaneously in the reactor.

The concentrations of NOx and CO (and O2) in the flue gases determine the total air factor. The total air factor may be balanced by increasing the air factor in case of high CO concentration and the air factor may be decreased in case of high NOx (O2) concentration in the flue gases. These prevailing approaches have been found to ultimately result in inaccurate air factors and consequent energy losses. It has proven to be even more challenging to obtain a correct air factor for demanding fuels such as bio fuels with great fluctuations of parameters that have impact on the air factor, parameters such as calorific value, moisture and ash contents etc.

By application of the new detailed thermodynamic model on which the present invention relies it has been shown that the increased production of NOx or CO may or may not be related to high or low air factor. Instead it has been found that it is closely related to the imbalance distribution of oxygen in the reaction chamber and the formation of oxidation and reduction zones which is a result of oxygen distribution imbalance. The continuous and simultaneous production of both NOx (oxidation milieu) and CO (reduction milieu) in industrial reactors regardless of accurate / inaccurate air factor confirms this new thermodynamic model.

Currently there are no procedures of measuring and profiling the temperature and the distribution of oxygen across the reaction chambers in conventional high-temperature industrial reactors of today. The importance of being able to determine the occurrence of oxidation and reduction zones has not been previously recognized and there are no procedures to detect these zones and their movement inside the reaction chamber and no techniques to counteract the formation of such zones have been previously presented.

Disclosed herein is a novel approach to detect and map the movement of oxidation and reduction zones in a high-temperature industrial reactor and to offer counter measures to neutralize and to prevent the formation of oxidation and reduction zones in order to address the environmental and operational problems associated with these zones.

This new comprehensive and detailed thermodynamic model disclosed herein reveals new features for production of NOx and CO in industrial processes. The invention based on this new thermodynamic model presents a new approach to monitor and adjusting reaction conditions and offers a tool for minimizing the production of NOx and CO in industrial processes. Preferably, the distribution of oxygen in an industrial reactor is continuously monitored and the result of the mapped oxygen distribution may be continuously used to regulate the air factor in an industrial process in order to optimize the energy conversion efficiency as well as to minimize the NOx and CO emissions and corrosion in industrial reactors etc.

In this invention a novel approach has been implemented. That is to analyze oxygen and temperature at selected locations, optionally at different heights inside the reaction chambers in industrial reactors in order to determine the distribution profiles of oxygen as well as the profile of temperature inside the reaction chambers.

In this invention the temperature and oxygen are preferably profiled by sampling inside the reaction chamber adjacent to the reactor wall. The temperature profile can be recorded by conventional thermocouples. The oxygen distribution can be mapped by Gas Chromatography (GC) or by Zirconium sensors.

This novel approach provides a unique opportunity to optimize the total reactor air factor instantly and continuously in order to optimize the energy conversion of the process in the reactor in spite of often rapid fluctuations of fuel parameters that affect the air factor such as calorific value, ash and moisture contents etc. This continuous correction and optimal air factor results i.e. optimal energy conversion and reduced corrosion in industrial reactors.

The proactive process control described in this invention may be implemented in an automated mode in order to detect the formation and movement of the oxidation and reduction zones and automatically redistribute oxygen cross the reaction chamber. The goal of these conducts is to distribute oxygen in a manner that the oxygen and temperature profile show as uniform profiles as thermodynamically is sound considering other parameters such as NOx and CO production, reactor load etc. at the same time.

These oxidation and reduction zones can arise from asymmetrical oxygen distribution in industrial reactors for a number of thermodynamics and operative factors such as: - Variations in proportions between combustible and non-combustible matter in fuels when the total air factors are not adjusted and corrected continuously for these variations during operation.

- Fluctuation of solid fuel quality, e.g. fluctuation in calorific value, moisture, ash content, etc.

- Fluctuation of gaseous fuel quality, e.g. fluctuation in calorific value, density, combustible constitution, etc.

- Variations in reactor loads.

- Faulty or unknown malfunctions or imprecisions of dampers and feeding systems for fuel and/or air quantities into the reactor.

- Soot removing procedures.

- Asymmetrical distribution of solid fuel in the reactor.

- Asymmetrical distribution of natural gas into various burners.

Another application area for this novel approach of monitoring the oxygen and temperature profiles inside the reaction chamber is the fact that it can be used as a diagnostic tool for daily operations. Faulty fuel and air dampers and feeding systems can be detected with continuous monitoring of oxygen and temperature.

For instance, sudden irregularities in the temperature profile despite correct oxygen distribution profile are an indication of faulty fuel dampers and / or irregular distribution of the fuel inside the reaction chamber.

This novel approach further enables a user to evaluate the quality of fuels continuously. This approach reveals a number of important details of reactor and industrial processes that have to be supervised and managed and would not be detected otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further explained hereinafter with reference to the appended drawings wherein: Fig. 1 shows a schematic representation of a process chamber of an industrial reactor; and Fig. 2 shows the process chamber in Fig. 1 with measuring points. It also shows the disappearances of oxidation and reduction zones with correct air distribution.

DETAILED DESCRIPTION With reference to Fig. 1, a process chamber 1 of a high-temperature industrial reactor shown in a highly schematic representation. Fig. 1 illustrates the thermodynamic model for formation of oxidation zones 2 and reduction zones 3 in the process chamber 1. Fig. 1 also shows inlets 4, 5 for secondary air and tertiary air which inlets may be used to regulate oxygen supply to the interior of the process chamber 1.

This invention has determined the nature and behavioral pattern of the oxidation and reduction zones 2, 3. The new high temperature thermodynamic model that this invention is based on, demonstrates that the oxidation and reduction zones 3,4 form adjacent to the inner wall 6 of the combustion chamber a and usually rearranges and moves around both vertically and horizontally inside the combustion chamber 1.

According to the new thermodynamic model which is the basis for the methods as disclosed herein, thermodynamic and operative factors institute imbalance in the oxygen distribution in industrial reactors and thereby oxidation and reduction zones 2, 3 are formed in industrial reactors. As set out herein, such oxidation and reduction zones 2,3 instigate increased production of environmentally damaging gases such as NOx in the oxidation zones 2 and CO in the reduction zones 3 in the flue gases regardless of correct / incorrect air factor quantities.

Apart from increased NOx and CO the formation of these oxidation and reduction zones 2,3 in industrial reactors give rise to problems such as corrosion, poor/incomplete fuel combustion etc. The production of NOx and CO reduces energy conversion efficiency due to the endothermic nature for formation enthalpy of NOx and CO. The oxidation zones show higher temperature in comparison to reduction zones. NOx is produced in oxidation zones with high oxygen concentration and CO is created in reduction zones with lower oxygen concentration as is illustrated by Fig. 1.

Fig 2 illustrates a proactive method to counteract the formation of oxidation and reduction zones in industrial reactors based on the thermodynamic model as disclosed herein.

The creation of oxidation and reduction zones 2,3 can therefore be detected and the distributions and movements of these zones 2,3 can therefore be monitored by implementation of the methods as described herein.

In this invention with the novel approaches of continuous monitoring of temperature and oxygen distribution inside the reaction chamber 1, the formation of oxidation and reduction zones is countered by redistributing the oxygen inside the reaction chamber 1 by regulating the oxygen input and/or oxygen removal where and when it is required. The redistribution system may include control of the air supply from the secondary and tertiary air inlets 4, 5, and optionally further air inlets (not shown). The reaction chamber 1 is also provided with a primary air inlet, which is not shown in the figures and which is not part of the system for regulating the oxygen profile inside the reaction chamber 1.

As is shown in Fig. 2, measuring points 8 are arranged on the reactor wall 6, for measuring the oxygen distribution profile and a temperature profile inside the reaction chamber 1. Although Fig. 2 shows measuring points 8 placed at a single level in the reaction chamber, it may be preferred that measuring points are arranged at different levels in the reactor wall 6. The number of measuring points 8 at a particular level may be selected as desired and the measuring points 8 may be distributed over the reactor wall 6 in a pattern of measuring points.

The data gathered from the measuring points 8, is analysed and an oxygen distribution profile and a temperature profile are created which forms the basis for further actions, such as redistribution of oxygen/air in the reaction chamber 1 to optimize the oxygen concentration in the reaction chamber 1 and eradicate any emerging oxidation zones 2 and reduction zones 3, as indicated in Fig. 2. The method is preferably computerized such that data can be gathered and processed in a central processing unit (CPU) and such that measuring equipment, valves, etc. can be continuously monitored and controlled electronically.

The reaction chamber 1 may have a shape different from the rectangular shape shown in the figures. Accordingly, the reaction chamber 1 may have any useful shape as known in the art, such as cylindrical, conical, etc.

Claims (7)

1. A method for minimizing the production of environmentally harmful emissions such as NOx and CO in an industrial reactor comprising a reaction chamber (1), characterized in that imbalances in the reaction chamber (1) are detected and counteracted, the method comprising detection of the presence and movement of oxidation and reduction zones (2, 3) in the reaction chamber (1) of the industrial reactor by measuring and analyzing oxygen concentration and temperature adjacent to a wall (6) at measuring points (8) arranged on the wall (6) inside the reaction chamber (1) in the industrial reactor and creating an oxygen distribution profile and a temperature profile in the industrial reactor and counteracting formation of oxidation zones (2) and reduction zones (3) in the industrial reactor by redistribution of oxygen in the reaction chamber (1) based on the oxygen distribution profile of the oxygen concentration and/or the temperature profile in the industrial reactor.

2. The method according to claim 1, wherein redistribution of oxygen in the reaction chamber comprises regulating air supply to the reaction chamber (1) based on the oxygen distribution profile of the oxygen concentration and the temperature profile in the industrial reactor.

3. The method according to claim 1 or 2, wherein the oxygen concentration and the temperature are measured at different heights inside the reaction chamber (1).

4. The method according to any one of the preceding claims, wherein oxygen distribution and temperature in the reaction chamber (1) are continuously monitored.

5. The method according to claim 4, wherein air supply to the reaction chamber (1) is continuously and proactively adapted in response to changes in the oxygen distribution profile and/or the temperature profile.

6. The method according to any one of the preceding claims, wherein the method is an automated method.

7. The method according to any one of the preceding claims, wherein the oxygen distribution profile and the temperature profile of the industrial reactor are used to diagnose a working condition of the industrial reactor.