SYSTEM AND METHODS FOR DETECTING, MONITORING, AND REMOVING DEPOSITS ON BOILER HEAT EXCHANGER SURFACES USING DYNAMIC PRESSURE ANALYSIS

Abstract

A boiler system includes a boiler having at least one internal surface on which a deposit may form. The boiler system further includes at least one cleaning implement coupled to a high-pressure fluid supply for carrying a high-pressure fluid into the boiler. The cleaning implement is configured such that the high-pressure fluid impacts the surface. The boiler system also includes at least one pressure measuring device coupled to the high-pressure fluid system. The pressure measuring device is configured to measure at least one of the pressure or flow rate in a high-pressure fluid supply, and the measured pressure and/or flow rate indicates presence or absence of the deposit on the surface.

Description

FIELD

The present invention relates generally to fouling or ash deposits in boilers and, more particularly, to a system and methods for detecting, monitoring, measuring, and/or removing the deposits on heat exchangers of the boilers by using dynamic pressure monitoring and analysis.

BACKGROUND

Many energy sources burned in boilers to generate steam will produce ash products with the potential for fouling the internal components of the boiler, which can decrease the operating efficiency of the boiler. For example, in the paper-making process, chemical pulping yields black liquor as a by-product. Black liquor contains inorganic cooking chemicals along with lignin and other organic matter that separates from wood during pulping in a digester. The black liquor is burned in a boiler. The two main functions of the boiler are to recover the inorganic cooking chemicals used in the pulping process and to make use of chemical energy in the organic portion of the black liquor to generate steam for a paper mill. Other examples include boilers that burn coal and biomass to generate steam for energy production or other uses. As used herein, the term boiler includes any boiler that burns a fuel that, in the process, fouls internal structures of the boiler, including heat transfer surfaces.

An example of a boiler used to burn black liquor to generate steam is a Kraft boiler. A Kraft boiler includes banks of heat exchangers at various levels in the furnace for extracting heat by radiation and convection from the furnace gases to generate heated fluids such as steam. Typically, the furnace gases first interact with heat exchangers in a superheater bank to generate superheated steam. The furnace gases then interact with heat exchangers in a generating bank to generate working steam. The generating bank may also be referred to as a boiler bank. Finally, the furnace gases interact with heat exchangers in an economizer bank, which generates lower temperature heated fluids. The banks of heat exchangers are constructed of an array of platens that are constructed of tubes that function as heat exchanger surfaces for conducting and transferring heat. While operating, heat exchanger surfaces are continually fouled by ash generated in the furnace chamber from burning fuels such as black liquor or coal. The amount of fuel that can be burned in a boiler is often limited by the rate and extent of fouling on the surfaces of the heat exchangers. The fouling, including ash deposited on the heat exchanger surfaces, reduces the heat absorbed from fuel combustion, resulting in reduced exit steam temperatures in the fouled heat exchanger banks and high gas temperatures entering the next heat exchanger bank in the boiler. For example, fouling in the superheater bank results in decreased steam temperatures exiting the heat exchanger and increased furnace gas temperature entering the generating bank. The heat exchanger surfaces in the generating bank tend to be relatively narrow compared to the spacing in the superheater and economizer banks, which increases the likelihood of fouling in the generating bank as compared to fouling in the superheater and economizer banks.

Fouling can require a boiler to be shut down for cleaning when either the exit steam temperature is too low for use in downstream equipment or the temperature entering the downstream heat exchanger bank, such as the generating bank downstream from the superheater bank, exceeds the melting temperature of the deposits, resulting in gas side pluggage of the downstream bank. In addition, fouling can eventually cause plugging in the upstream bank as well, such as the superheater bank. In order to remove the plugging from the heat exchanger banks, the burning process in the boiler must be stopped. Kraft boilers are particularly prone to the problem of fouling in the generating bank with ash deposits that must be removed for efficient operation; however, the other heat exchanger banks may also become fouled. Three conventional methods of removing ash deposits from the heat exchanger banks in boilers: 1) sootblowing, 2) chill-and-blow, and 3) water washing. Sootblowing is a process that includes blowing deposited ashes off a heat exchanger surface that is fouled with ash deposits using blasts of high-pressure steam from nozzles of a lance of a sootblower. Sootblowing is performed essentially continuously during normal boiler operation, with sootblowers in various locations in operation at different times. Sootblowing is usually carried out using high-pressure steam, but other fluids may be used. The steam consumption of an individual sootblower is typically 2-3 kg/s, and as many as four sootblowers may be operated simultaneously. Typical sootblower usage may consume about 3-7% of the steam production of the entire boiler. Thus, the sootblowing procedure consumes a large amount of thermal energy produced by the boilers being cleaned.

A typical sootblowing process utilizes a procedure known as sequence sootblowing, wherein sootblowers operate at predetermined intervals and in a predetermined order. The sootblowing procedure runs at this pace irrespective of the amount of fouling that may occur at any particular location in the heat exchanger. Often, this leads to plugging in areas of the heat exchanger that are insufficiently cleaned by the predetermined sootblowing sequence that cannot necessarily be prevented even if the sootblowing procedure consumes a large amount of steam. Each sootblowing operation reduces a portion of nearby ash deposits, but ash deposits that are not completely removed may nevertheless continue to build up over time. As ash deposits grow, sootblowing becomes gradually less effective and impairs heat transfer. When an ash deposit reaches a certain threshold where boiler efficiency is significantly reduced or combustion gases cannot be removed from the furnace, deposits may need to be removed by another cleaning process requiring the boiler to be shut down. However, overusing the sootblowing procedure across the entire boiler can also decrease the operating efficiency of the boiler by consuming the thermal energy produced by the boiler and can damage the boiler tubes by causing erosion and corrosion of the tube surface.

SUMMARY

It is desirable to monitor the pressure in the supply of high-pressure fluid of a boiler cleaning implement, such as a sootblower or water cannon. The dynamic response of the pressure in the supply of high-pressure fluid can be monitored for signals that define the profile of a fouled surface along the path of the cleaning implement. In an embodiment, the signal is a change in the pressure of the supply of high-pressure fluid that results from the high-pressure fluid expelled from the cleaning implement contacting fouling, such as a deposit, on a surface in the boiler system. The dynamic pressure signal in the supply of high-pressure fluid is then used to detect, monitor, measure, and/or remove ash deposits from the surfaces of boilers, such as heat exchanger surfaces, and, as a result, conserve energy by directing sootblower activity to areas in need of cleaning and thus having the cleaning implement use a minimum amount of high-pressure fluid such as steam, air, or water.

It is also desirable to develop a map of the deposition pattern of deposits surrounding the path of each of the cleaning implements so that the information in the map may be used to adjust priority of cleaning implement operations for efficient use and, in general, to develop an effective cleaning strategy.

It is also desirable to monitor the operating condition of the boiler cleaning implements such as by monitoring the pressure in the supply of high-pressure of the boiler cleaning implement or vibrations in or coming from the boiler cleaning implement. The operating conditions may include poppet valve condition, bearing condition, and leaks in the supply of high-pressure fluid.

An aspect of the invention is directed to a boiler system that includes a boiler having at least one heat exchanger, the at least one heat exchanger having a surface on which a deposit may form. The boiler system further includes at least one cleaning implement which may be selected from a sootblower having a lance tube or water canon for carrying a high-pressure fluid into the boiler. The cleaning implement is configured such that the high-pressure fluid impacts a surface in the boiler. The boiler system also includes at least one pressure measuring device coupled to the supply of high-pressure fluid to the cleaning implements of the boiler system, the pressure measuring device being configured to measure changes in pressure in the supply of high-pressure fluid that results from high-pressure fluid contacting the boiler surfaces or deposits on the boiler surfaces. The measured pressure changes of the high-pressure fluid supply to the cleaning implement indicates presence or absence of the deposit on a boiler surface, such as a heat exchange surface. Another aspect of the invention may include vibration measuring devices used either in concert with the pressure measuring device or independent of the pressure measuring device. The vibration measuring device may be used to identify the presence of deposits in the boiler system as well as the operating condition of the boiler cleaning implement or the supply of high-pressure fluid.

Another aspect of the invention is directed to a method of detecting a deposit on at least one surface of a boiler that includes moving a cleaning implement relative to the at least one boiler surface and impacting the at least one boiler surface with high-pressure fluid discharged from the cleaning implement. The method further includes measuring a pressure change in the supply of high-pressure fluid to the cleaning implement caused by the impact of the high-pressure fluid with the at least one boiler surface and analyzing the measured pressure to detect the presence of the deposit at the location.

Another aspect of the invention is directed to methods of mapping the location deposits in a boiler system. The method includes identifying the location of a deposit on a boiler surface based on reactive pressure changes in the supply of high-pressure fluid generated by impacting deposits with the high-pressure fluid discharged from a cleaning implement. A deposit map may then be generated based on the positions of the identified deposits.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various embodiments of the invention and, together with a general description of the invention given above and the detailed description of the embodiments given below, serve to explain the embodiments of the invention.

FIG. 1 is a schematic illustration of a boiler system in accordance with an embodiment of the invention;

FIG. 2 is an enlarged detail of top perspective view of a portion of the boiler system shown in FIG. 1 illustrating a number of accelerometers positioned on hanger rods supporting a number of platens; and

FIG. 3 is a flow chart illustrating a process for analyzing signals from a pressure measuring device to identify the presence of deposits in accordance with an embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration of a boiler system 10 having a boiler 12 including a plurality of heat exchangers 22 with deposits 20 formed thereupon, pressure measuring device 14, a cleaning implement, in this illustrated embodiment a sootblower 16, a deposit detection device 18, and an integrated device 30.

For the purposes of the present invention, the term “boiler” 12 refers to a closed vessel in which water or other fluid is heated in heat exchangers that are contacted by hot gases from a combusted fuel. Exemplary boilers 12 include a recovery boiler and a utility boiler. The heated or vaporized fluid exits the boiler 12 for use in various processes or heating applications, including boiler-based power generation, process heating, and the like.

The term “recovery boiler” includes the type of boiler 12 that is part of the Kraft process of pulping where chemicals for pulping are recovered and reformed from black liquor, which contains lignin (among other organic materials) from previously processed wood. The black liquor is burned, generating heat, which is usually used in the process or in making electricity, much as in a conventional steam power plant. The two main functions of recovery boilers are to recover the inorganic cooking chemicals used in the pulping process and to use the chemical energy in the organic portion of the black liquor to generate steam for the mill. A detailed description of Kraft black liquor boilers are described in detail in U.S. Pat. Nos. 6,323,442 and 7,341,067, which are incorporated by reference herein in their entireties.

With reference to FIGS. 2 and 3, the boiler 12 comprises a series of heat exchangers 22. The heat exchangers 22 may be organized into a superheater bank, a generating bank, an economizer bank, and combinations thereof. The heat exchangers 22 are formed of tubes (FIG. 1) or platens (FIG. 2) having surfaces 48. Each heat exchanger 22 may comprise approximately 20-100 tubes, for example. The heat exchanger surfaces 48 have passages 50 upstream and/or downstream therethrough to allow a sootblower 16 to move relative to the heat exchanger surfaces 48, as will be described in greater detail below.

In an embodiment, the boiler 12 is suspended from a ceiling with boiler supporting structures that may include overhead beams 34 and hanger rods 32. The overhead beams 34 may include I-beams. Approximately 30-100 hanger rods 32 (FIG. 2) may be used to suspend the boiler 12 from the overhead beams 34. More specifically, the hanger rods 32 may be bolted or otherwise coupled to the overhead beams 34 at one end and coupled to the heat exchangers 22 either directly or via headers 36 (FIG. 2) at an opposite end. The hanger rods 32 typically have a diameter that ranges from about 1 inch to about 3 inches and length range from about 2 feet to about 20 feet long.

As explained above during use, slag and/or ash deposits 20 may form on the surfaces 48 of the boiler 12 including the heat exchangers 22, the internal surfaces 37 of the walls of the boiler 12, which degrades thermal performance of the boiler system 10. The amount of the deposit 20 may vary at different locations in the boiler 12 on the heat exchanger surfaces 48 and the internal surfaces 37 of the walls.

The boiler system 10 includes one or more sootblowers 16 for cleaning deposits 20 from the heat exchanger surfaces 48. For example, a boiler system 10 may include a plurality of sootblowers 16 spaced apart by approximately 5-15 feet within the boiler 12. For the purposes of the present invention, the term “sootblower” 16 refers to an apparatus used to project a stream of a high-pressure fluid 24, such as steam, air, water or other fluid against heat exchanger surfaces 48 of large-scale combustion devices, such as utility or recovery boilers. Generally, the sootblowers 16 include a lance tube 26 that is in fluid communication with a source (not shown) of high-pressure fluid 24, such as steam. As illustrated in FIG. 2, each sootblower 16 may also include a motor 76 for rotating the lance tube 26. The motor 76 is typically suspended from a rail 78 by one or more rollers 80 that couple the motor to a hood 82. The rail 78 allows the motor 76 to move with the lance tube 26 as the lance tube 26 translates in and out of the boiler 12, as described in greater detail below. The hood 82 covers the motor 76 and rail 78 and typically provides at least one attachment point, such as a pair of brackets 84, for coupling the sootblower 16 to an external support structure 88. For drafting efficiency, only a subset of the sootblowers 16 illustrated on FIG. 2 are shown as including motors 76, rails 78, and hoods 82. However, it is appreciated that in embodiments of the invention, all of the sootblowers 16 in a boiler system 10 include these additional structures.

While the exemplary embodiment illustrated herein utilize sootblowers 16 expelling steam, it is noted that embodiments of the invention are not so limited, and the sootblowers 16 may also use other high-pressure fluids 24, such as air, water, or other fluids, and other cleaning implements such as water cannons. In embodiments of the invention, the high-pressure fluid 24 may be supplied via a supply line at a pressure of approximately 100-400 psi. Each sootblower 16 also includes at least one nozzle 28 at the distal end 29 of the lance tube 26 of the sootblower 16. In an embodiment, each sootblower 16 includes two nozzles 28 that are spaced 180° apart at the distal end 29 of the lance tube 26.

As described in greater detail below, a retractable sootblower 16 is configured such that the lance tube 26 translates (i.e., periodically advance and retract) in and out of an interior of the boiler 12 as the high-pressure fluid 24 is discharged from the nozzles 28. The lance tube 26 of the sootblower 16 may also be configured to rotate while the high-pressure fluid 24 is discharged from the nozzles 28.

The boiler system 10 also includes one or more pressure measuring devices 14 coupled to the boiler system 10 to measure pressure in the high-pressure fluid supply of the cleaning implements, e.g. sootblowers 16 or water cannons, in the boiler system 10. Exemplary pressure measuring devices 14 may include a pressure transducer, a fluid velocity measurement device, and combinations thereof. In an embodiment, the pressure measuring device is a pressure transducer. The pressure measuring devices 14 are mounted on strategic locations along the flow path of high-pressure fluid supply in the boiler system 10. In an embodiment, the pressure measuring device is mounted along the pressure line between the cleaning implement and the source of this high-pressure fluid. For example, the pressure measuring device may be mounted along the pressure line leading to an individual cleaning implement. In an embodiment of this exemplary structure, the pressure measuring device is in the supply line as close to the individual cleaning implement as possible. An advantage of this location for the pressure measuring device is isolating the pressure measuring device from interference or noise from other sources or sinks in the high-pressure fluid supply. In another example. The pressure measuring device may be located upstream along the pressure line serving multiple cleaning implements. This exemplary structure would allow a single pressure measuring device to monitor multiple cleaning implements. In another embodiment, the pressure measuring device is located along or on the sootblower 16, such as in the lance tube 26. The pressure measuring devices 14 collect pressure data, such as changes in amplitude and natural frequency, in the supply of high-pressure fluid to the cleaning implements of the boiler system 10 that occurs as a result of the high-pressure fluid expelled from the cleaning implement contacting a deposit on a boiler 12 surface such as on boiler surfaces of the boiler walls. The pressure measuring device 14 could also monitor the operating conditions of the cleaning implements, the high-pressure supply, and combinations thereof. The operating conditions that may be monitored include the condition of poppet valves in the high-pressure fluid supply, the condition of mechanical aspects of the cleaning implement such as bearings or gears, and the occurrence of leaks or reductions in flow rate or pressure in the high-pressure fluid supply lines.

In an embodiment, the system may also include vibration detecting devices 90 to detect vibrations in or coming from the boiler cleaning implement or the high-pressure fluid supply. The vibration detecting devices 90 may be used in concert with the pressure measuring device 18 or independently. The vibrations detected by the vibration detection devices could be used to monitor the operating condition of the boiler cleaning implement or the high-pressure fluid supply. Exemplary vibration detecting devices 90 include accelerometers. The vibration detecting devices may directly detect vibrations in the boiler system or be coupled to a diaphragm to detect vibrations in a medium such as air, which may be manifest as oscillating wave of pressure and displacement in the medium, that originated in the boiler system. In an embodiment, the vibration detecting device 90 is coupled directly to the boiler system via at least one of the boiler, boiler support structures, the cleaning implement, the support structures of the cleaning implement, or the high-pressure fluid supply. In another exemplary embodiment, the vibration measuring device is spaced apart from the boiler system to measure vibrations in the air.

The system also includes a deposit detection device 18 that receives input for the pressure measuring devices 14 as well as the optional vibration measuring device 90 and optionally communicates with the integrated device 30 that may control the operation of the cleaning implement such as a sootblower 16. The deposit detection device 18 includes software configured to interpret pressure data received from the pressure measuring devices 14 and to provide instructions to the integrated device 30, so as to direct operation of the cleaning implement sootblower 16 and the lance tube 26.

The sootblowers 16 are periodically operated to clean the heat exchanger surfaces 48 to restore desired operational characteristics. In use, a lance tube 26 of a sootblower 16 moves relative to heat exchanger surfaces 48 through passages 50. The sootblowers 16 are inserted into and extracted from the boiler 12 such that the nozzles 28 move between a first position located outside of the boiler 12 and a second position located inside the boiler 12. As the nozzle 28 on the lance tube 26 of the sootblower 16 move between the first and second positions, the nozzle 28 rotates adjacent the heat exchanger surfaces 48 such that the high-pressure fluid 24 is expelled about a radius along the path of the nozzle 28 between the first and second positions. In an embodiment, the second position is the maximum inserted position. The sootblowers 16 move generally perpendicularly to the heat exchanger surfaces 48 as the lance tubes 26 move through the passages 50.

The movement of the sootblower 16 into the boiler 12, which is typically the movement between the first and second positions, may be identified as a “first stroke” or insertion, and the movement out of the boiler 12, which is typically the movement between the second position and the first position, may be identified as the “second stroke” or extraction. Generally, sootblowing methods use the full motion of the sootblower 16 between the first position and the second position; however, a partial motion may also be considered a first or second stroke. The high-pressure fluid is usually applied during both the first and second strokes.

As the sootblower 16 moves adjacent to the heat transfer surfaces 48, the high-pressure fluid 24 is expelled through the openings in the nozzle 28. The impact of the high-pressure fluid 24 with the deposits 20 accumulated on the heat exchanger surfaces 48 produces both a thermal and mechanical shock that dislodges at least a portion of the deposits 20. However, some amount of deposit 20 remains. As used herein, the term “removed deposit” refers to the mass of a deposit that is removed by the sootblowing procedure, and “residual deposit” refers to the mass of a deposit that remains on a heat exchanger surface 48 after a sootblowing cycle.

The impact of the high-pressure fluid 24 on the heat exchanger surfaces 48 affects the flow of high-pressure fluid in the high-pressure fluid supply line and can cause changes in the pressure or flow rate, or both the pressure and flow rate, which may be detected and measured by one or more of the pressure measuring devices 14. The impact of the high-pressure fluid 24 on the heat exchanger surfaces 48 may also affect the pressure of the high-pressure fluid in the high-pressure fluid supply line and can cause changes in the pressure or flow rate, or both the pressure and flow rate, of the high-pressure fluid supply, which may be detected and measured by one or more of the pressure measuring devices 14. The changes in the pressure or flow rate, or both the pressure and flow rate can be caused directly by the impact of the high-pressure fluid 24 with the heat exchanger surfaces 48 or indirectly, such as by reflection of the fluid off the heat exchanger surfaces 48 back into the flow path of the high-pressure fluid 24.

As an amount of deposit 20 buildup changes on the heat exchanger surfaces 48, the effect of the deposit 20 on the pressure and/or flow rate of high-pressure fluid in the high-pressure fluid changes. As the size of a deposit 20 increases, the pressure in the high-pressure fluid supply will increase or the flow rate may decrease. As the size of the pressure applied by the high-pressure fluid 24 delivered by the deposit 20 decreases, the pressure in the high-pressure fluid supply will decrease or the flow rate may increase. The pressure, or flow rate, or both the pressure and flow rate of the high-pressure fluid supply to a cleaning implement, such as a sootblower 16 or water cannon can be analyzed to detect the presence of residual deposits. The amount of pressure in the high-pressure fluid supply that results from the high-pressure fluid 24 contacting a deposit is a direct function of or directly proportional to the amount of deposit 20 buildup on a heat exchanger surface 48. In other words, increased pressure in the high-pressure fluid, as indicated by increase in the pressure or decrease in flow rate measured in the high-pressure fluid supply, signifies an increase in deposit 20 buildup on the boiler surface being cleaned, such as on the heat exchanger surface 48 internal wall of the boiler.

The pressure in the high-pressure fluid supply is proportional to the surface area perpendicular to the high-pressure fluid flow hitting a deposit 20 on the boiler surfaces. The surface area of the deposit 20 may correlate to the mass of the deposit 20. The changes in pressure or flow rate in the high-pressure fluid supply that result from the pressure buildup caused by the high-pressure fluid impacting deposits 20 on the boiler surface can be used to determine an amount of high-pressure fluid 24 the sootblower 16 needs to deliver to remove the deposits 20 from the boiler surface such as a heat exchanger surface 48. Aspects of the present invention are directed to analyzing the changes in pressure, flow rate, or both, in the high-pressure fluid supply produced by the forces transmitted to the high-pressure fluid supply by the high-pressure fluid 24 expelled from the cleaning implement contacting deposits 20 on the boiler surfaces. Therefore, the concept of energy excitation response is used to determine the location and removal of the deposits 20. The measured pressure and/or flow rate in the high-pressure fluid supply may then be used to control a flow characteristic of the high-pressure fluid 24, such as an amount of high-pressure fluid 24 discharged from the nozzle 28 on the lance tube 26 or a flow rate of the high-pressure fluid 24 to more efficiently clean the boiler surfaces.

An aspect of the invention is directed to methods of mapping deposits 20 on one or more heat exchanger surfaces 48 in a boiler system 10. A deposit map is generally a spatial representation of the location of each sootblower 16 in the boiler 12 and the respective deposit 20 buildup profiles as determined by the path of the individual sootblower 16 within the boiler 12. A deposit map may be generated by moving at least one lance tube relative to at least one heat exchanger surface while discharging a high-pressure fluid 24. The high-pressure fluid 24 impacts deposits on the heat exchanger surfaces resulting in pressure and/or flow rate changes in the high-pressure fluid supply that may be measured to identify the presence of a deposit. Thus, by incrementally and simultaneously translating and rotating the nozzle 28 on the lance tube 26 at a set penetration distance into the boiler 12, deposits 20 may be detected at a plurality of locations on the heat exchanger surfaces 48. The position of the nozzle 28 on the lance tube 26 of the sootblower 16 relative to the heat exchanger surfaces 48 when a deposit is identified may then be used to determine the position of identified deposits 20 along the path of the nozzle 28 on the lance tube 26 of the sootblower 16. The position of deposits 20 identified along the path of nozzle 28 of each sootblower 16 may be used to generate a map of deposits 20 at each sootblower 16 location.

In an embodiment, the map may be represented as a table that identifies the sootblower 16 and the position along the path of the identified sootblower 16 where a deposit 20 is detected. The table may also identify the relative location of the sootblower 16 in the boiler system 10. In another embodiment, the map is a two-dimensional representation of one or more deposits 20 on the heat exchanger surfaces 48 along the path of a sootblower 16. In another embodiment, the map is a three-dimensional representation of one or more deposits 20 on heat exchanger surfaces 48 along the paths of a plurality of sootblowers. Because a conventional boiler may have, depending on the size, from just a few to more than one hundred sootblowers 16 located across the height and width of the boiler 12, detailed maps of deposits 20 may be obtained. Successive deposit maps may change as the heat exchanger surfaces 48 become fouled or are cleaned and relative changes in deposit 20 build up or position may be illustrated on the successive maps.

The generated maps may assist with identifying areas in the boiler system 10 in which deposits 20 do not form, areas where the sootblowers 16 are adequately removing deposits, and areas where residual deposits remain and that may require additional sootblower 16 activities to remove. These data may be used to develop an efficient sootblowing strategy that reduces steam consumption for energy savings or improves heat exchanger surface 48 effectiveness. For example, a sootblower 16 could be operated in “deposit 20 location mode” periodically, for example, once per day, and the collected information may be used to update a current deposit map. This map may be used to adjust the priority of sootblower 16 operations for effective and efficient use of the sootblower 16 and to reduce steam consumption for energy savings.

Referring now to FIG. 3, a flow chart depicting a process 100 for analyzing a signal from a pressure measuring device 14 is presented in accordance with an embodiment of the invention. The analytical process 100 includes a sequence of operations that may be performed by the deposit detection device 18.

In block 102, a threshold for determining the presence of an event indicative of a residual deposit on a boiler surface, such as a heat exchanger surface 48 or internal boiler wall is established. The threshold is a value or a range of values against which the signal from the pressure measuring device 14 may be compared. In embodiments of the invention, a narrow frequency range of the signal from the pressure measuring device 14 is analyzed for the presence of an event. For example, the threshold may be a pressure or a flow rate. In an exemplary embodiment, the threshold is predetermined and can be based on historical data. The historical data can include data taken when the boiler is clean such as just after startup. In an alternative embodiment, the threshold is determined based on real time or near real time data from the pressure measuring device 14. In yet another alternative, the threshold is established as a multiple of the background pressure or flow rate of the high-pressure fluid supply.

In block 104, a signal from the pressure measuring device 14 is analyzed for signals that exceed the threshold to establish the occurrence of an event. The signal from the pressure measuring device 14 corresponds to the pressure, the flow rate, or both the pressure and flow rate of the high-pressure fluid supply measured by the pressure measuring device 14. An event may be identified as a signal from the pressure measuring device 14 that exceeds the threshold. In an embodiment, the event is a signal that significantly exceeds the threshold as determined by statistical analysis. In an alternative embodiment, the event is a signal that exceeds the threshold by a predetermined value or percentage.

In block 106, the location of the nozzle 28 is identified at the occurrence of the event. In an embodiment, the location of the nozzle may be identified by recording the time of the occurrence of the event during a stroke of the sootblower 16 and correlating that time with the location of the nozzle 28. Other methods of identifying the location of the nozzle 28 of the sootblower 16 at the occurrence of an event may be employed, such as the use of rotational and displacement measurement sensors.

In block 108, the location of the nozzle at the occurrence of an event is recorded as the location of a potential deposit.

The analytical process 100 set forth in FIG. 3 may be repeated for each stroke of a sootblower 16 into and out of a boiler system. In an embodiment, the location of a potential deposit recorded in a first stroke is compared with the location of a potential deposit recorded in a second stroke. If the location of a potential deposit recorded in a first stroke is near to or the same as the location of a potential deposited recorded in a second stroke, then the presence of a deposit at the location may be considered to be confirmed. In some embodiments, the sootblower 16 does not follow the same helical path on the way into the boiler system as it does on the way out. In such embodiments, a deposit recorded in a first stroke might not be recorded for the second stroke. Additionally, the pressure in the high-pressure fluid supply that results from the expelled high-pressure fluid during insertion may differ from the pressure in the high-pressure fluid supply during extraction. As such, deposits that may be detected in a first stroke might not be detected in a second stroke.

The frequency or high-pressure fluid output delivered by particular sootblowers 16 may be adjusted in accordance with their respective pressure measurements. By reviewing the pressure differences indicative of deposits 20 on the heat exchangers 22 that area associated with individual sootblowers 16, or groups of sootblowers 16, the boiler operator may develop an understanding of locations in the boiler 12 where the most deposit 20 buildup or fouling is occurring. This information may be used to establish the frequency of operation or high-pressure fluid output delivered to particular sootblowers 16 for reducing fouling and improving boiler 12 efficiency by using only an amount of high-pressure fluid 24 necessary to remove deposits 20. The information may also be used to adjust boiler 12 conditions or configurations to reduce fouling at particular locations. For example, the information may be used to improve the design of the boiler 12 to reduce fouling or to identify locations within the boiler 12 for additional or reduced fouling abatement mechanisms.

The deposit detection device 18 (FIG. 1) receives signals from the pressure measuring devices and may optionally control the operation of the cleaning implement, such as a sootblower lance tube 26, based on the deposits 20 located on one or more of the heat exchanger surfaces 48. The deposit detection device 18 may also control the amount of high-pressure fluid 24 supplied or the high-pressure fluid's 24 flow rate to the heat exchanger surfaces 48 during cleaning portions of the insertion and extraction strokes and during cooling portions of the insertion and extraction strokes when steam is used to keep the sootblower from overheating but not for cleaning purposes. The deposit detection device 18 generally includes a processing unit and a memory device. The deposit detection device 18 may be implemented as a computer (not shown) programmed to carry out the tasks described. The deposit detection device 18 may also be implemented using hardware, software, or combinations thereof. The memory may be encoded with computer readable instructions that cause the processing unit to perform the data analysis described herein.

The deposit detection device 18 may communicate with the integrated device 30, which provides control signals to the cleaning implement, such as a sootblower lance tube 26, to start and stop the cleaning implement strokes. Accordingly, the integrated device 30 may control the frequency of use of each of the cleaning implements. The integrated device 30 may also provide signals to a data acquisition system (not shown) indicating when individual cleaning implements, or groups of cleaning implements, are at particular locations of their strokes. For example, the integrated device 30 may provide a signal to the data acquisition system when a particular cleaning implement begins a stroke and when the particular cleaning implement ends its stroke. Furthermore, the integrated device 30 may indicate the insertion and extraction portions of the stroke. The data acquisition system may utilize the signals indicative of the beginning and the end of a particular cleaning implement stroke to identify pressure measurements from the pressure measuring device 14 occurring at or near the beginning and the end of the cleaning implement stroke. The deposit detection device 18 may then utilize statistical techniques to manipulate the pressure or flow rate data associated with individual cleaning implement or groups of cleaning implements. The pressure characteristics such as the pressure change or flow rate of the high-pressure fluid supply can be used to select a suitable frequency for operation of the cleaning implements or a high-pressure fluid 24 output of the cleaning implements.

The data acquisition system generally includes a processing unit and a memory device. The data acquisition system may be implemented as a computer (not shown) programmed to carry out the tasks described. The data acquisition system may also be implemented using hardware, software, or combinations thereof. The memory may be encoded with computer readable instructions that cause the processing unit to perform the data analysis described herein. The data acquisition system may be a standalone device or part of the deposit detection devices 18 or the integrated device 30. In some embodiments, the deposit detection device 18, the integrated device 30, and the data acquisition system are combined in a single unit. It is to be understood that the location and configuration of the deposit detection device 18 and the integrated device 30 are flexible in accordance with general computing technology.

By selecting frequencies or high-pressure fluid 24 usage for individual cleaning implements or groups of cleaning implements based on their measured performance, the overall amount of the high-pressure fluid 24 utilized by the cleaning implements may be reduced and the effectiveness of the cleaning implements improved. This technique can improve the overall efficiency of the boiler 12, which may allow the boiler system 10 to consume less fuel for the same high-pressure fluid 24 output or to operate longer without shutdown (scheduled or unscheduled) due to plugging.

While the present invention has been illustrated by the description of specific embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.

Claims

1. A boiler system comprising:

a boiler having at least one heat exchanger, the at least one heat exchanger having a surface on which a deposit may form;

at least one cleaning implement having a tube for carrying a high-pressure fluid into the boiler, the tube being fluidly coupled to a high-pressure fluid supply and configured to discharge the high-pressure fluid such that the high-pressure fluid impacts at least one of the heat exchanger surface and/or internal boiler wall surface; and

at least one pressure measuring device coupled to the high-pressure fluid supply, the pressure measuring device being configured to measure the changes in at least one of the pressure or flow rate in the high-pressure fluid supply resulting from the impact of the high-pressure fluid with a deposit,

wherein the measured pressure of the high-pressure fluid indicates presence or absence of the deposit on the at least one of heat exchanger surface or internal boiler wall surface.

2. The boiler system of claim 1, wherein the measured pressure of the high-pressure fluid supply indicates at least one of a location of the deposit or an amount of the deposit on the at least one of heat exchanger surface or internal boiler wall surface.

3. The boiler system of claim 1, wherein the at least one pressure measuring device is located in at least one of a high-pressure fluid line carrying the high-pressure fluid supply to at least one cleaning implement or a high-pressure fluid line carrying the high-pressure fluid supply to more than one cleaning implement.

4. (canceled)

5. The boiler system of claim 1, wherein the at least one pressure measuring device is in fluid communication with the high-pressure fluid in the cleaning implement.

6. The boiler system of claim 1, wherein the at least one pressure measuring device is selected from the group consisting of a pressure transducer, a flow rate measurement device, and combinations thereof.

7. The boiler system of claim 1 wherein the cleaning implement is selected from the group consisting of a sootblower and a water cannon.

8. The boiler system of claim 1 further comprising a vibration measuring device.

9. A method of detecting a deposit on a surface disposed within a boiler system, the method comprising:

moving a cleaning implement coupled to a high-pressure fluid supply relative to the surface;

impacting the surface with a high-pressure fluid discharged from the cleaning implement;

measuring at least one of a pressure or flow rate in the high-pressure caused by the impact of the high-pressure fluid at a location on the at least one of the pressure or flow rate; and

analyzing the measured pressure to detect the presence of the deposit at the location.

10. The method of claim 9, further comprising:

controlling a flow characteristic of the high-pressure fluid discharged from the cleaning implement at the location of the surface in response to the measured at least one of the pressure or flow rate.

11. The method of claim 10, wherein the flow characteristic is selected from the group consisting of an amount of high-pressure fluid discharged from the cleaning implement, a flow rate of the high-pressure fluid, and combinations thereof.

12. The method of claim 9 one of claims 9 to 11, wherein the step of measuring a pressure further comprises:

dynamically measuring pressures in the high-pressure fluid supply caused by the impact of the high-pressure fluid with the surface at each of a plurality of locations,

wherein the step of analyzing the measured pressure further comprises analyzing the measured pressure in the high-pressure fluid supply caused by the impact of the high-pressure fluid with the plurality of locations on the surface, the method further comprising:

generating a map of the locations of any detected deposits on the surface.

13. The method of claim 12, further comprising:

controlling a flow characteristic of the high-pressure fluid discharged from the cleaning implement while moving the cleaning implement relative to the at least one heat exchanger surface based on the map of detected deposits.

14. The method of claim 13, wherein the flow characteristic is greater for a location of the surface having a greater amount of deposit than for a location of the surface having a lesser amount of deposit.

15. The method of claim 9, wherein the pressure is measured with at least one pressure transducer coupled to at least one of the high-pressure fluid supply, the cleaning implement, a high pressure fluid line supplying high-pressure to at least one cleaning implement, or combinations thereof.

16. (canceled)

17. (canceled)

18. The method of claim 9, wherein the impacting of the surface with high-pressure fluid removes at least a portion of the deposit at the location on the surface, the method further comprising:

measuring a first pressure at a first time point caused by the impact of the high-pressure fluid at the location of the surface;

measuring a second pressure at a second time point caused by the impact of the high-pressure fluid at the location of the surface; and

comparing the first pressure to the second pressure to determine changes in the amount of the deposit on the surface at the location.

19. The method of claim 9, wherein the greater the measured pressure in the high-pressure fluid supply when impacting the surface at the location on the surface, the greater an amount of the deposit at the location on the surface.

20. The method of claim 9 wherein the surface is selected from the group consisting of a heat exchanger surface, an internal boiler wall surface, and combinations thereof.

21. The method of claim 9 wherein the cleaning implement is selected from the group consisting of a sootblower and a water cannon.

22. A method of analyzing a surface of a boiler system, the process comprising:

passing a cleaning implement coupled to a high-pressure fluid supply through a boiler in a first pass and contacting a surface in the boiler with a high-pressure expelled from the cleaning implement;

receiving a first signal indicative of a pressure in a high-pressure fluid supply in the boiler system; and

in response to the signal exceeding a threshold, determining the existence of a deposit on the surface of the boiler.

23. The method of claim 22, further comprising:

identifying the position of the cleaning implement when the signal exceeds the threshold; and

determining a position of the deposit in the boiler based on the position of the cleaning implement when the signal exceeds the threshold.

24-30. (canceled)