WO2001061297A2

WO2001061297A2 - Combustion process optimisation system by means of direct measurements inside the furnace

Info

Publication number: WO2001061297A2
Application number: PCT/ES2001/000052
Authority: WO
Inventors: L. Cañadas Serrano; V. Cortes Galeano; F. Rodriguez Barea; E. Tova Holgado
Original assignee: Asociacion De Investigacion Y Cooperacion Industrial De Andalucia (Aicia)
Priority date: 2000-02-16
Filing date: 2001-02-15
Publication date: 2001-08-23
Also published as: ES2166312B1; WO2001061297A3; AU2001231780A1; EP1411298A2; ES2166312A1

Abstract

System consisting of a probe or probes (1) and in a variety of openings (2) that allow the accomplishment of direct measurements or characterisations (gas extraction or placing of sensors) in the interior of the furnace (3) of industrial boilers. These local measurements intend to optimise the operation of each burner, allowing the global improvement of the boiler operation. The probes (1) are designed with very narrow transversal sizes, to allow them to pass through the openings (2) carried out on the membranes (4) (typically around 20 mm) which join the water tubes (5), making up the water walls of the boiler, making the mentioned local measurements feasible with no need to undertake substantial modifications in the boiler. Additionally, the subject of this patent is the fully automated version of the described system, that allows the continuous characterisation and optimisation of boiler combustion conditions, as well as its application to any other combustion process.

Description

SYSTEM FOR THE OPTIMIZATION OF COMBUSTION PROCESSES THROUGH DIRECT MEASURES INSIDE THE HOME

The patent system consists, in its basic version, of a probe or probes and a series of holes that, due to their special characteristics, allow measurements or characterizations to be carried out in high-temperature areas (near the burners or any another area inside the home) of industrial boilers. These local determinations are aimed at optimizing the operation of each burner, allowing the global improvement of parameters such as combustion performance, generation of burns, the formation of pollutants, or slagging processes.

The holes are made on the fins that serve as a connection to the tubes that form the water walls of this type of installation, which makes it possible to carry out the aforementioned local determinations without the need for substantial modifications to the boiler. The probe is dimensioned taking into account the limitation of the width of these fins (typically around 20 mm) and, therefore, of the holes made in them.

Additionally, the fully automated version of the described system is the object of this patent, which allows to continuously characterize and optimize the boiler's combustion conditions.

These systems are equally applicable to the optimization of industrial furnaces, by adjusting their burners by measuring in high temperature areas. BACKGROUND OF THE INVENTION

Technique sector:

Industrial boilers are installations in which fuel (pulverized coal, fuel oil, diesel, gas, etc.) is injected into the combustion chamber through the burner nozzles, where it finally reaches the ignition point and burns to produce heat. This heat is transmitted to the water that circulates through the pipes that form the boiler walls and other heat exchange equipment, producing steam at high pressure and temperature. The energy of this steam is used either directly in different industrial processes, or as mechanical energy in a turbine, and then transformed into electrical energy by turning an alternator coupled to the turbine.

The performance and generation of pollutants in this type of installation depends, to a large extent, on the correct distribution of fuel and air in the boiler hearth, so that the existence of critical areas with an inadequate air / fuel ratio leads to penalties. in relation to these very important parameters. Likewise, in the case of coal, these imbalances can generate strongly reducing zones that lower the melting point of the ashes, facilitating their deposition on the boiler tubes (slag). This fact causes significant losses due to heat transfer, and sometimes problems that can force the installation to stop with the consequent loss of production.

These imbalances in the contributions of air and fuel are also very problematic for burners used in furnaces of any type of industrial process, affecting their energy performance, as well as the quality of the products and by-products obtained therein. * State of the art:

In industrial boilers, mainly thermal power plants, the use of flue gas analysis systems located at the boiler outlet is frequent. These systems are used for the adjustment and control of the overall combustion process. Thus, the determination of parameters, such as oxygen and carbon monoxide, in the boiler outlet area allows the correct combustion development to be identified.

However, the optimization of this process based on these values has certain limitations. In this sense, even when the gas analysis is carried out in a large number of points uniformly distributed in the boiler outlet ducts, the distance from the area where the combustion actually occurs, the evolution of the flame and the degree of gas mixture existing in the measurement area, make the obtained values do not allow to properly characterize the correct operation of each burner and, ultimately, optimize the overall combustion process.

In the context of the current state of the art, there are equipment marketed by numerous entities (Storm Technologies, ESA, IFRF, etc.), which allow determinations inside the boiler hearth (refrigerated probes, suction pyrometers, high-speed thermocouples, etc.), although these devices are designed to measure through the boiler sight glasses, these being several centimeters in size and being located only in certain areas of the home.

In this way, the realization of this type of measures inside the home is restricted to areas where direct access is available through the originally installed peepholes, since the opening of this type of holes requires, given their dimensions greater than 20 mm (usually around 100 mm), from the execution of important constructive modifications in the design of the boiler tube layout. Other approaches to the characterization of combustion processes consist of the use of systems based on the location of sensors on the boiler walls. These sensors measure the signals of different wavelengths produced by the combustion process itself, characterizing some property of the generated flames (passive systems, such as, for example, flame detectors, infrared pyrometers, cameras or heat flow meters arranged in tubes), or those signals generated by ex-professio emitters located in other areas of the boiler wall and that are attenuated or modified in their transmission through the home (active systems, such as those based on principles acoustic).

Examples of this type of applications based on "wall" or "contour" sensors or measurement systems are included in numerous patents such as, for example, US 4555800, US 3824391, US 4176369, DE 3224500, US 5794549, EP 0802372, DE 4328629 and US 4756684 (passive systems) and WO9710473 (active system), being, in any case, indirect or signal transmission measures of the actual development of the combustion process, as they are based on determinations from the home contour area.

These facts motivate that the available information on the actual development of the combustion process is scarce and limited in terms of its representativeness in industrial-size boilers.

These limitations in the knowledge of local combustion conditions are equally extrapolated to furnaces of any type of industrial process.

DESCRIPTION OF THE INVENTION

This invention refers to a system that allows measurements to be carried out in any area of the interior of the home of industrial boilers, especially those close to the burners. Examples of this type of measure would be the evaluation of local levels of gas concentrations, temperatures, heat fluxes, and even imaging, in these high-temperature areas with very limited access. for traditional boiler designs. The purpose of these determinations is to identify the combustion conditions at any point inside the boilers, in order to optimize their performance, generation of pollutants or tendency to slag.

This local information allows considering the installation as a set of small virtual installations made up of a single burner. The oriented adjustment of each of these small installations supposes the global optimization of the boiler.

To cover these objectives, the system presents a novelty in carrying out this type of measurements through holes of small dimensions, made on the connecting fins of the tubes that form the water walls of the boiler. The width of these holes (14 mm) is limited by the width of the fins itself (around 20 mm), while their height, due also to the same geometry of the fins, does not have any limitation.

This new concept of measurement in the home of industrial boilers makes it possible to carry them out in any desired location, without being subject to the existence of peepholes according to the original design of the boiler and allowing the direct determination of the combustion conditions in the interior of the home. In this way, it is feasible, without significant construction modifications in the installation, to measure the height of each of the boiler burners. For access to the interior of the home, for the extraction of samples or the introduction of sensors, a refrigerated probe has been devised, or it is constructed or lined with ceramic material, specially designed to be inserted through these holes, and capable of additionally withstanding high temperatures. (1400-1700 ° C) existing in this boiler zone.

In a further embodiment, the system can be automated in terms of its operation through the following elements: motorization (insertion-extraction, lateral displacement) of the movement of the probe; continuous treatment and analysis system for the gas samples collected or for the acquisition of the data provided by the sensors introduced into the home by the probe; cleaning system by means of pressurized air in countercurrent that guarantees the autonomy of the system between measurements; advanced supervision software that, in addition to controlling the operation of the entire automated system and conveniently treating the results obtained, provides the plant operator with operating recommendations based on these results and a series of rules established based on experience in optimizing this process.

The detailed invention is applicable to the optimization of any other type of burner, such as those existing in industrial furnaces.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of what is described herein, some drawings are attached in which, only by way of example, some variants of embodiment of the system are represented.

Thus, Figure 1 presents a schematic of the system in its basic version, where the probe (1) that is inserted through the hole (2) inside the boiler hearth (3) is observed. This hole (2) is made on a fin (4) for joining pipes (5) on the hearth wall in the vicinity of a burner in the installation.

Figure 2 represents a longitudinal section view of the probe (1) in its refrigerated variant and for gas sampling; In it you can see the outer bushing (6) for entering and leaving the coolant and its circulation inside the probe. Likewise, the sample aspiration duct (7) can be seen. Figure 3 shows a front view and a cross section of the hole (2) made in the fin (4) between tubes (5), for the probe variant (1) collected in Figure 2 (refrigerated and for gas sampling) .

Figure 4 shows a diagram of an automated version of the system, specifically its variant for gas sampling, in which the movement of the probe can only be insertion-extraction (one probe per hole), or with additional lateral displacement (a multi-hole probe). The elements necessary for this last variant are presented schematically in Figure 5.

DESCRIPTION OF A PREFERRED EMBODIMENT

The access holes (2) are distributed throughout the boiler in the vicinity of each burner. The detail of one of these holes, for the refrigerated probe and gas sampling variant, is presented in Figure 3, where its geometry can be seen (two semicircles of 7 mm radius joined by a square of 14 mm on each side) .

The probe is specially designed to withstand the high temperatures existing in this area (between 1400 and 1700 ° C) and to access the interior of the boiler through the holes described.

In its refrigerated and gas sampling variant (Figure 2), a rectangular section tube (14 x 12 mm sides and 1 mm thick) and two half-rods (7 mm radius and 1 mm thickness) welded together as presented in Section AA of the figure. In this same section, the three resulting chambers (8, 9, 10) through which the cooling fluid, for example, water, can be seen. Of these, the intermediate chamber (9) is crossed by a 6 mm diameter tube through which the gas sample to be analyzed is extracted. These elements are assembled at the tip of the probe by means of two cone half-trunks and two triangular plates, as observed in the detail of the probe tip, Figure 2. At the other end, an outer sleeve (6) is provided. that allows the entry and exit of the cooling fluid and the sample collection tube.

In short, the path of the cooling fluid is as follows: it enters through hole (11) into chamber A (12) of the sleeve, from where it passes into the two outer chambers (8) and (10) of the probe. Upon reaching the tip of the probe, the fluid returns through the intermediate chamber (9) until it reaches chamber B (13) of the bush where it exits through the hole (14). An example of the automation of the system is outlined in Figure 4. This figure shows how the probe (1 1), cooled or not, is arranged in association with a pneumatic cylinder (15), controlled by a multi-way valve (16) , whose actuation causes the probe to deploy or retract, thus allowing its introduction or extraction from the boiler hearth (3).

In the gas sampling and analysis variant, to which the aforementioned Figure 4 corresponds, the sample collected by the probe passes to a heated filter (17) for the removal of ash in suspension and, subsequently, to a set of valves ( 18) that controls the passage of the sample towards the conditioning system, or the introduction of pressurized air in the direction of the heated filter and the probe, causing a countercurrent blow that allows cleaning of both elements.

An example of a sample conditioning system (19) is composed of a condenser, a refrigerator, a filter and a pump. Said conditioning system can be housed in a cabinet (20) located on the support of the cylinder-probe assembly, which can also be used to house valves (16) and (18), or be located in a nearby area where it provides service to various probes.

The collected sample is taken from the conditioning system to an analysis system whose fundamental part is a gas analyzer (21), and which can be completed with other filters, a humidity detector and a valve to control the entry of the sample into the analyzer.

A programmable automaton (22) is used to collect the results of the analysis, control the entire process and collect possible incidents. Said information can be sent to a control room computer (23) that also collects the information provided by other automata or monitoring systems, and that has software implemented to provide operating recommendations to the plant operator, starting from said readings and according to a series of rules established based on the experience on optimizing that process. For the automated version with lateral displacement (a multi-hole probe, Figure 5), the probe (1) for gas sampling or the introduction into the home of any type of sensor, the pneumatic cylinder (15), the multi-way valve for the actuation of this (16) and other auxiliary elements (for example, for the gas sampling version, the heated filter (17), the set of control valves (18) and the sample conditioning system (19) housed in the cabinet (20), which can also contain the valves (16) and (18)) are arranged on a carriage (24) powered by motors (25), in order to allow the displacement of the set and the obtaining of measurements at other points of the boiler. On the trolley (24) several proximity sensors (26) are arranged, which make the trolley motors stop in the presence of a positioner (27) that signals the exact location of a sampling point. To ensure the carriage (24) stops at the exact point, a speed variator (28) controlled by an automaton reduces the speed of the motors in the vicinity of the positioner to a minimum, thanks to the location signal provided by a device suitable (eg, an encoder (29) located on the carriage (24)).

Claims

1. System that allows measurements (by means of gas extraction or introduction of sensors) in the areas inside the home (high temperatures) of industrial boilers (such as thermal power plants), as well as controlled and guided optimization of the processes of combustion in these facilities based on the results of these local determinations; said system characterized by comprising the following elements: A) boiler access holes whose reduced dimensions (width less than that of the connecting fins of the water wall pipes, typically <20 mm) allow their implantation on said fins , so that they allow direct determinations to be made inside the home (not only in its outline), such as measurements of gas concentrations through their extraction at a preselected point and subsequent analysis, temperature determinations or heat fluxes, and Obtaining images of any type of wavelength, without the need to make modifications in the design of the characteristic arrangement of the boiler tubes; B) probe or probes of small transverse dimensions, specially designed for the recovery of gas samples and introduction and conditioning of sensors in high temperature areas, through the holes described above.

2. System according to claim 1, wherein the probe or probes are introduced into the boiler house through holes that are made in the vicinity of each of the existing burners, in order to enable individual optimization of these.

3. System according to claims 1 or 2, wherein the probe or probes are cooled by water, water with additives, oil, oil with additives, air or any other type of cooling fluid.

System according to claims 1 or 2, wherein the probe or probes are constructed, or coated extensively, of any type of ceramic material that adequately supports the temperatures existing in the boiler's home, thus avoiding the use of fluids of refrigeration

System according to claims 1, 2, 3 or 4, wherein the probe or constituent probes are fully automated and controlled by a specific software in their different possibilities of movement, using a probe, equipped with insertion-extraction movement, for each hole through which the measure is of interest

System according to claims 1, 2, 3 or 4, wherein the constituent probe or probes are fully automated and controlled by a specific software in its various possibilities of movement, using or one or several probes, each used for measurement through empty gaps based on lateral displacement movements additional to those of insertion-extraction

System according to the preceding claim, which allows the probe or probes to face the boiler access ports with an accuracy of ± 1 mm, for example by the combined action of proximity detectors for the final positioning of the probe and an encoder mcremental that allows the change of the lateral displacement speed according to the distance to its objective (high speed at the time of movement and slow in the vicinity of the stopping point), or by any other positioning and location determination system. the probe that contemplates the use of any of these devices or infrared, acoustic, electromagnetic sensors or that use radiation of other types of wavelength

System according to claims 5, 6 or 7, characterized, in its vain for analysis of household gases, for locating the treatment systems and conditioning of gas samples on the probe support, moving with it in the lateral movement version described in claims 6 and 7; and said treatment and conditioning system being composed of a filter holder for ash retention and a cooling and / or condensation system for the sample moisture.

9. System according to claims 5, 6, 7 or 8, which allows the cleaning of the different parts of the sampling circuit by means of the action of pressurized air in countercurrent (blowing of the filter support and the probe) allowing the autonomy of the system between show us.

10. System according to claims 5, 6, 7, 8 or 9, wherein the results of the local determinations provided by the system itself are transmitted to the Control Room of the installation to enable monitoring and adjustment of the process.

11. System according to claims 5, 6, 7, 8, 9 or 10, equipped with software for optimization of combustion conditions (yield, generation of pollutants, scoriations, etc.) from the results of the determinations premises provided by the system itself and, eventually, other results or data of the operation of the plant.

12. System according to the preceding claims applied to combustion processes other than those set forth in claim 1 and, in particular, those that employ gaseous, liquid, solid fuels or mixtures thereof, in the presence of air, enriched air, oxygen and, in general, any oxidizer.

13. System according to claims 1 to 11 applied to the optimization of other industrial burners, either individually or jointly, such as those existing in process furnaces, clinker furnaces, furnaces Metallurgical, Toxic and Hazardous Waste Incinerator (RTP) or Urban Solid Waste (MSW) incinerator.