Intelligent soot blowing method for convection heating surface of boiler

Abstract

The invention discloses an intelligent soot blowing method for a convection heating surface of a boiler, which comprises the following steps of: 1, determining a soot blowing sequence influencing the heat exchange condition of the convection heating surface according to the arrangement condition of soot blowers corresponding to a certain convection heating surface of the boiler and the heat exchange characteristic of the heating surface; 2, online calculation boundary conditions of the convection heating surface pollution rate are determined, wherein the boundary conditions comprise the unit load rate, the coal feeder combination, the coal feeding amount and the operation state of a soot blower corresponding to the convection heating surface; 3, determining the maximum heat absorption capacity of the convection heating surface under a certain calculation boundary; 4, determining the actual heat absorption capacity of the convection heating surface under a certain calculation boundary; 5, according to the maximum heat absorption capacity and the actual heat absorption capacity, the real-time pollution rate of the convection heating surface under a certain calculation boundary is determined; 6, according to the real-time pollution rate and the pollution rate increasing rate, soot blowers of different sequences are triggered, and targeted soot blowing is achieved.

Description

Technical Field

[0001] The invention relates to an intelligent sootblowing method for a convection heating surface of a boiler. Background Art

[0002] At present, steam soot blowing of boiler convection heating surfaces adopts periodic soot blowing mode, which not only easily causes steam waste, but excessive soot blowing will also aggravate the wear of the heating surface and shorten its service life. On-demand soot blowing requires real-time analysis of the contamination rate and pollution rate of the heating surface, and targeted soot blowing is achieved based on the calculation results.

[0003] All current calculations of contamination and pollution rates are based on the ideal heat transfer coefficient derived from the heating surface structural parameters or the heat absorption of the heating surface under the boiler design conditions. Since changes in boundary conditions have a decisive effect on the heat absorption of the heating surface during actual operation, it is necessary to study the calculation method of the contamination rate based on actual operating conditions. Summary of the invention

[0004] The present invention provides an intelligent sootblowing method for a boiler convection heating surface, and the technical solution is as follows:

[0005] An intelligent sootblowing method for a boiler convection heating surface, characterized in that it comprises the following steps:

[0006] Step 1: according to the sootblower arrangement corresponding to a certain convection heating surface of the boiler and the heat exchange characteristics of the heating surface, determine the sootblowing sequence that affects the heat exchange of the convection heating surface;

[0007] Step 2: determining the online calculation boundary conditions of the contamination rate of the convection heating surface, wherein the boundary conditions include the unit load rate, the coal feeder combination, the coal feed rate, and the operation status of the soot blower corresponding to the convection heating surface;

[0008] Step 3: Determine the maximum heat absorption of the convection heating surface under a certain calculation boundary;

[0009] Step 4: Determine the actual amount of heat absorbed by the convection heating surface under a certain calculation boundary;

[0010] Step 5: Determine the real-time contamination rate of the convection heating surface under a certain calculation boundary according to the maximum heat absorption and the actual heat absorption;

[0011] Step six: triggering soot blowers in different sequences according to the real-time pollution rate and the pollution rate growth rate to achieve targeted soot blowing.

[0012] Preferably, the sootblowing sequence is divided into multiple sequences according to the actual arrangement of the sootblowers, and each sequence includes a plurality of sootblowers.

[0013] Preferably, the maximum heat absorption Q of the convection heating surface maxIt is calculated using the following formula:

[0014] Q max =G im *(h i2m -h i1m ) (1)

[0015] Where: G im It is the steam flow rate flowing through the convection heating surface under a certain calculation boundary after the full sequence of soot blowing on the convection heating surface, unit: t / h; h i1m and h i2m They are respectively the inlet steam enthalpy value and the outlet steam enthalpy value of the convection heating surface under a certain calculation boundary after the full sequence of sootblowing on the convection heating surface, in units of kj / kg.

[0016] Preferably, the actual heat absorption of the convection heating surface is Q sj It is calculated using the following formula:

[0017] Q sj =G i *(h i2 -h i1 )

[0018] Where: G i is the steam flow rate flowing through the convection heating surface under a certain calculation boundary, in t / h; h i1 and h i2 They are respectively the inlet steam enthalpy and outlet steam enthalpy of the convection heating surface under a certain calculation boundary, in kj / kg.

[0019] Preferably, the real-time contamination rate k of the convection heating surface under a certain calculation boundary is calculated using the following formula:

[0020]

[0021] Among them, k is the real-time pollution rate, Qsj is the actual heat absorption, and Qmax is the maximum heat absorption.

[0022] Preferably, when the convection heating surface completes the full sequence of sootblowing under the current load, the maximum heat absorption of the convection heating surface will be recalculated to achieve iterative optimization of the contamination rate of the convection heating surface.

[0023] Preferably, the execution status of the sootblowing sequence is determined according to the comparison result between the real-time contamination rate and the reference contamination rate, and when the contamination rate and the contamination rate growth rate are in different states, sootblower of different sequences are triggered.

[0024] Preferably, the method is applicable to coal-fired boilers, gas-fired boilers and other types of industrial boilers.

[0025] Preferably, the method monitors and adjusts the operating status of the sootblower in real time through a DCS system to ensure the optimization of the sootblowing effect.

[0026] The beneficial effects of the present invention are as follows:

[0027] The sootblower effects of a single heating surface are divided into sequences based on the layout of the sootblower and the heat transfer characteristics of the heating surface.

[0028] Taking load, coal feeder operation combination, coal feeding amount, and soot blower operation status as boundary conditions, determine the pollution rate benchmark under different boundary conditions, and accurately calculate the real-time pollution rate to guide soot blowing. Under a certain boundary condition, the maximum heat absorption of all convection heating surfaces is calculated through DCS (Distributed Control System) historical data analysis. During actual operation, after the boundary conditions are determined, the pollution rate of the heating surface is calculated by dividing the real-time heat absorption of the heating surface by the current maximum heat absorption of the boundary. The calculation formula for the pollution rate is k=Q_sj / Q_max, where k is the pollution rate, Q_sj is the actual heat absorption of the heating surface, and Q_max is the maximum heat absorption of the heating surface under certain boundary conditions.

[0029] When the pollution rate and pollution rate growth rate are in different states, different sequences of soot blowers will be triggered. When a heating surface completes the full sequence of soot blowing under the current load, the system will iterate the maximum heat absorption of the heating surface to avoid the impact of other boundary changes such as coal quality.

[0030] The contamination rate described in this patent is more in line with the actual operating conditions of the boiler and can provide a data basis for targeted soot blowing. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is the process of determining the maximum heat absorption Q_max of the convective heating surface under a certain boundary.

[0032] Figure 2 It is an iterative optimization process for the contamination rate of the convective heating surface. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but the present invention is not limited to the following embodiments.

[0034] like Figure 1 As shown, the load value is selected, and the working condition under the load is divided into coal feeder combination 1, coal feeder combination 2... coal feeder combination n according to different coal feeder combinations. Different coal feeder combination working conditions are divided into total coal quantity 1, total coal quantity 2... total coal quantity n according to different total coal quantities. Under the above working conditions, after the full sequence of soot blowing on each heating surface is completed, the maximum heat absorption under the boundary condition is calculated.

[0035] like Figure 2 As shown, when the real-time contamination rate of a convection heating surface of the boiler is less than a, continue to calculate the real-time contamination rate of the convection heating surface.

[0036] When the real-time contamination rate of the convection heating surface is greater than a: ① If it does not increase to a+b within the set period, the first sequence of soot blowing will start, and the contamination rate will be judged again after the first sequence of soot blowing ends; if the contamination rate is less than ab, the soot blowing ends; if the contamination rate is greater than ab, the next sequence of soot blowing will be triggered; the contamination rate judgment will be repeated until the contamination rate is less than ab and the soot blowing ends, or the whole sequence of soot blowing ends. ② If it increases to between a+b and a+2b within the set period, the first and second sequences of soot blowing will start, and the contamination rate will be judged again after the first and second sequences of soot blowing end; if the contamination rate is less than ab, the soot blowing ends; if the contamination rate is greater than ab, the next sequence of soot blowing will be triggered; the contamination rate judgment will be repeated until the contamination rate is less than ab and the soot blowing ends, or the whole sequence of soot blowing ends. ③ If it increases to between a+2b and a+3b within the set period, the first, second and third sequence soot blowing will start. After the first, second and third sequence soot blowing ends, the pollution rate will be judged again; if the pollution rate is less than ab, the soot blowing ends; if the pollution rate is greater than ab, the next sequence soot blowing will be triggered; the pollution rate judgment will be repeated until the pollution rate is less than ab and the soot blowing ends, or the whole sequence soot blowing is completed. ④ If it increases to more than a+3b within the set period, the whole sequence soot blowing will be directly carried out.

[0037] After the full sequence of soot blowing is completed, the pollution rate a1 is read, and the judgment index of the next pollution rate is iteratively obtained as a2 (a2=a1+2b). At this point, one iteration calculation is completed.

[0038] For the convection heating surface, a reference contamination rate a is set according to the boiler operation characteristics. After comparing the real-time contamination rate k of the convection heating surface with the reference contamination rate a, the execution of the sootblowing sequence of the convection heating surface is determined, that is, when the contamination rate k and the contamination rate growth rate are in different states, the sootblower of different sequences of the convection heating surface will be triggered. When the convection heating surface completes the full sequence of sootblowing under the current load L, the maximum heat absorption of the convection heating surface will be recalculated to achieve iterative optimization of the contamination rate of the convection heating surface.

[0039] The online calculation method for the contamination rate of the boiler convection heating surface in this embodiment specifically includes the following steps:

[0040] Step 1) According to the sootblower arrangement corresponding to a certain convective heating surface of the boiler and the heat exchange characteristics of the heating surface, a sootblowing sequence that affects the heat exchange of the convective heating surface is determined.

[0041] The sootblowing sequence can be divided into XL1, XL2, XL3, ..., XL4 according to the actual arrangement of the sootblower. m Each sootblowing sequence includes several sootblowers.

[0042] Step 2) determining the online calculation boundary conditions of the contamination rate of the convective heating surface.

[0043] The online calculation boundary conditions of the convection heating surface pollution rate include the unit load rate L, the coal feeder combination GM n (n=1, 2, 3, ...), coal feeding amount ML, the operation state XL of the soot blower corresponding to the convection heating surface ty Among them, XL ty Represents the commissioning status of the soot blowing sequence of the convection heating surface. According to the concept of sequential execution, XL1 is executed first, then XL2, ..., and so on. m The specific execution of the soot blowing sequence is determined by the real-time contamination rate of the convection heating surface. m The state is called full sequence sootblowing.

[0044] Step 3) Determine the maximum heat absorption Q of the convection heating surface under a certain calculation boundary. max .

[0045] Preferably, as attached Figure 1 According to step 2), determine the online calculation boundary of the convection heating surface contamination rate, and when the sootblower operation status XL is met ty In the case of full sequence soot blowing, the calculated heat absorption of the convection heating surface is the maximum heat absorption Q under the current calculation boundary. max Based on the heat transfer characteristics of the heating surface and according to the boiler operating parameters, the maximum heat absorption of the convection heating surface Q max It is calculated using formula (1).

[0046] Q max =G im *(h i2m -h i1m ) (1)

[0047] Where: G im is the steam flow rate flowing through the convection heating surface under a certain calculation boundary after the full sequence of soot blowing on the convection heating surface, t / h; h i1m and h i2m They are respectively the inlet steam enthalpy and the outlet steam enthalpy of the convection heating surface under a certain calculation boundary after the full sequence of soot blowing on the convection heating surface, kj / kg.

[0048] Step 4) Determine the actual heat absorption Q of the convection heating surface under a certain calculation boundary. sj .

[0049] Based on the heat transfer characteristics of the heating surface and according to the boiler operating parameters, the actual heat absorption Q of the convection heating surface sj It is calculated using formula (2).

[0050] Q sj =G i *(h i2 -h i1 ) (2)

[0051] Where: G i is the steam flow rate flowing through the convection heating surface under a certain calculation boundary, t / h; h i1 and h i2 are the inlet steam enthalpy and outlet steam enthalpy of the convection heating surface under a certain calculation boundary, kj / kg respectively.

[0052] Step 5) determining the real-time contamination rate of the convection heating surface under a certain calculation boundary.

[0053] The real-time contamination rate k of the convective heating surface under a certain calculation boundary is calculated using formula (3).

[0054]

[0055] Step 6) realizing iterative optimization of the contamination rate of the convection heating surface.

[0056] Preferably, as attached Figure 2 As shown. For the convection heating surface, a reference contamination rate a is set according to the boiler operating characteristics. After comparing the real-time contamination rate k of the convection heating surface with the reference contamination rate a, the execution status of the sootblowing sequence of the convection heating surface is determined, that is, when the contamination rate k and the contamination rate growth rate are in different states, the sootblower of different sequences of the convection heating surface will be triggered. When the convection heating surface completes the full sequence of sootblowing under the current load L, the maximum heat absorption Q of the convection heating surface will be recalculated. max , to achieve iterative optimization of the contamination rate of the convective heating surface, thereby avoiding the impact of other boundary changes such as coal quality.

[0057] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. An intelligent sootblowing method for a boiler convection heating surface, characterized in that: The following steps are involved: Step 1: according to the sootblower arrangement corresponding to a certain convection heating surface of the boiler and the heat exchange characteristics of the heating surface, determine the sootblowing sequence that affects the heat exchange of the convection heating surface; Step 2: determining the online calculation boundary conditions of the contamination rate of the convection heating surface, wherein the boundary conditions include the unit load rate, the coal feeder combination, the coal feed rate, and the operation status of the soot blower corresponding to the convection heating surface; Step 3: Determine the maximum heat absorption of the convection heating surface under a certain calculation boundary; Step 4: Determine the actual amount of heat absorbed by the convection heating surface under a certain calculation boundary; Step 5: Determine the real-time contamination rate of the convection heating surface under a certain calculation boundary according to the maximum heat absorption and the actual heat absorption; Step six: triggering soot blowers in different sequences according to the real-time pollution rate and the pollution rate growth rate to achieve targeted soot blowing.

2. The intelligent sootblowing method for a boiler convection heating surface according to claim 1, characterized in that: The sootblowing sequence is divided into a plurality of sequences according to the actual arrangement of the sootblowers, and each sequence includes a plurality of sootblowers.

3. The intelligent sootblowing method for a boiler convection heating surface according to claim 1, characterized in that: The maximum heat absorption Q of the convection heating surface max It is calculated using the following formula: Q max =G im *(h i2m -h i1m ) Where: G im It is the steam flow rate flowing through the convection heating surface under a certain calculation boundary after the full sequence of soot blowing on the convection heating surface, unit: t / h; h i1m and h i2m They are respectively the inlet steam enthalpy value and the outlet steam enthalpy value of the convection heating surface under a certain calculation boundary after the full sequence of sootblowing on the convection heating surface, in units of kj / kg.

4. The intelligent sootblowing method for a boiler convection heating surface according to claim 1, characterized in that: The actual amount of heat absorbed by the convection heating surface Q sj It is calculated using the following formula: Q sj =G i *(h i2 -h i1 ) Where: G i is the steam flow rate flowing through the convection heating surface under a certain calculation boundary, in t / h; h i1 and h i2 They are respectively the inlet steam enthalpy and outlet steam enthalpy of the convection heating surface under a certain calculation boundary, in kj / kg.

5. The intelligent sootblowing method for a boiler convection heating surface according to claim 1, characterized in that: The real-time contamination rate k of the convection heating surface under a certain calculation boundary is calculated using the following formula: Among them, k is the real-time pollution rate, Q sj is the actual amount of heat absorbed, Q max For maximum heat absorption.

6. The intelligent sootblowing method for a boiler convection heating surface according to claim 1, characterized in that: When the convection heating surface completes the full sequence of sootblowing under the current load, the maximum heat absorption of the convection heating surface will be recalculated to achieve iterative optimization of the contamination rate of the convection heating surface.

7. The intelligent sootblowing method for a boiler convection heating surface according to claim 1, characterized in that: The execution of the sootblowing sequence is determined according to the comparison result between the real-time pollution rate and the reference pollution rate. When the pollution rate and the pollution rate growth rate are in different states, sootblower of different sequences are triggered.

8. The intelligent sootblowing method for a boiler convection heating surface according to claim 1, characterized in that: The method is applicable to coal-fired boilers, gas-fired boilers and other types of industrial boilers.

9. The intelligent sootblowing method for a boiler convection heating surface according to claim 1, characterized in that: The method monitors and adjusts the operating state of the soot blower in real time through a DCS system to ensure the optimization of the soot blowing effect.

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