A thermal resistance insulation design method for a multi-stage smoke washing and heat eliminating device

Abstract

The present application belongs to the technical field of exhaust gas washing and cooling and heat-mass exchange enhancement of marine diesel engines, and in particular relates to a heat resistance insulation design method for a multi-stage smoke washing and heat eliminating device. The method divides multiple spraying sections along the airflow direction, collects the gas phase, liquid phase, air overcurrent, wall surface temperature and stable operation time parameters of each section, calculates the wall surface heat loss, determines the chord grid heat resistance through the heat resistance difference of the spraying sections before and after the chord grid, calculates the insulation layer thickness based on the heat boundary of the chord grid after the efficiency is improved, inversely calculates the maximum allowable thermal conductivity coefficient of the insulation material when the thickness is limited, screens the insulation material, and adjusts the material, insulation layer or chord grid arrangement according to the priority for the spraying sections that do not meet the requirements. The present application solves the problems of difficult quantification of chord grid efficiency improvement, experience-dependent determination of insulation thickness and material in a limited space, and improves the design precision of sectional insulation and the reliability of outer wall temperature control.

Description

Technical Field

[0001] This invention belongs to the field of ship propulsion shafting design and verification technology, specifically, it relates to a thermal resistance insulation design method for a multi-stage smoke washing and heat dissipation device. Background Technology

[0002] With the development of ocean shipping, marine diesel internal combustion engine power generation systems play a vital role in ship operation, cabin power supply, and emergency response. During operation, diesel internal combustion engines generate high-temperature, high-flow-rate exhaust gases. In environmentally sensitive areas, cabins, engine rooms, and other enclosed or semi-enclosed spaces, if these exhaust gases are simply guided or directly emitted, they can easily lead to increased local ambient temperature and enhanced heat radiation, posing thermal hazards to surrounding equipment and personnel. Therefore, filtering, scrubbing, and cooling the exhaust gases from diesel generators are crucial measures to reduce thermal hazards within the cabin and ensure the safe operation of equipment.

[0003] Existing fume scrubbing and heat dissipation devices typically utilize contact heat exchange between spray droplets and high-temperature airflow to cool the exhaust gas, and use a casing structure to guide and collect the exhaust gas. For fume scrubbing and heat dissipation devices installed in ship cabins, engine rooms, or other confined spaces, their outer walls usually require an insulation layer to reduce the surface temperature of the device, minimize the risk of burns to workers, and prevent continuous heat dissipation from the outer wall from adversely affecting the cabin environment.

[0004] However, the space available for installation and maintenance within a confined space is limited, and the thickness of the insulation layer cannot be arbitrarily increased. If the insulation layer thickness is insufficient, the temperature of the outer wall of the device will be difficult to control within the target range. If the insulation layer thickness is too large, it will increase the space occupied by the device, affecting the layout of equipment, maintenance operations, and piping connections within the cabin. At the same time, different insulation materials have different thermal conductivity, temperature resistance, and construction compatibility. Under a fixed installation space and a predetermined outer wall temperature target, selecting insulation materials based solely on experience can easily lead to insufficient insulation effect or redundant material configuration.

[0005] Furthermore, to improve the cooling efficiency inside the flue gas scrubbing and heat dissipation device, existing devices can incorporate heat and mass exchange enhancement structures such as gratings. These structures can alter the contact state between the airflow and the spray droplets, thus affecting the cooling effect. However, in engineering design, the effectiveness of these enhancement structures often relies on empirical judgment, lacking quantifiable evaluation criteria. This makes it difficult to establish a clear match between the internal enhancement structure design and the external insulation design. Especially in multi-stage spray cooling structures, the airflow temperature, water temperature changes, spray volume, and heat exchange intensity differ at each spray stage. If a uniform insulation thickness or material configuration is used for each stage, it can easily lead to insufficient insulation in the preceding stage, redundant insulation in the subsequent stage, or inaccurate localized external wall temperature control.

[0006] Therefore, there is an urgent need for a design method for multi-stage flue gas washing and heat dissipation devices in confined spaces. This method should be able to quantitatively analyze the internal heat and mass exchange efficiency, external wall heat dissipation, insulation layer thickness, and insulation material selection conditions based on the actual operating conditions of the device. This would address the problems of existing flue gas washing and heat dissipation devices relying mainly on experience to determine efficiency enhancement structures and insulation schemes in confined spaces, insufficient external wall temperature control accuracy, and weak targeting of staged insulation design. Summary of the Invention

[0007] This invention addresses the problems of existing flue gas scrubbing and heat dissipation devices, which rely primarily on experience to determine the chord enhancement structure, insulation layer thickness, and insulation material within confined installation spaces. These issues lead to difficulties in quantifying the internal heat and mass exchange enhancement effect, insufficient matching between external insulation design and actual heat load, and weak targeting of segmented insulation design. The invention proposes a thermal resistance insulation design method for multi-stage flue gas scrubbing and heat dissipation devices. This method involves segmented heat analysis of the multi-stage flue gas scrubbing and heat dissipation device to determine the wall heat loss, chord thermal resistance, insulation layer thickness, and the maximum allowable thermal conductivity of the insulation material for each spray segment. Based on thickness constraints, material thermal conductivity constraints, and chord enhancement requirements, the method adjusts each spray segment to be optimized, thereby achieving a quantitative matching design between the internal enhancement structure and the external insulation structure of the multi-stage flue gas scrubbing and heat dissipation device. This improves the accuracy of external wall temperature control and the adaptability of insulation schemes within confined spaces.

[0008] To achieve the above objectives, the present invention provides a thermal resistance insulation design method for a multi-stage smoke scrubbing and heat dissipation device, the method comprising:

[0009] Step 1: Divide the multi-stage smoke washing and heat removal device into multiple spray sections along the airflow direction. Run the multi-stage smoke washing and heat removal device in a simulated ventilation environment corresponding to the limited installation space. Collect the gas phase parameters, liquid phase parameters, air flow parameters, wall temperature parameters and stable operation time of each spray section. Determine the heat loss of the wall of each spray section based on the energy conservation relationship.

[0010] Step 2: Calculate the thermal resistance of each spray section under stable operating conditions with and without the chord grid, and determine the chord grid thermal resistance of the spray section by the difference in thermal resistance of the same spray section before and after the chord grid is installed.

[0011] Step 3: Determine the heat loss from the wall surface and the temperature of the wall surface to be insulated in each spray section using the stable operating parameters after setting the chord grid. Establish a thermal boundary condition model after chord grid enhancement based on the heat loss from the wall surface, the temperature of the wall surface to be insulated, and the coverage area of ​​the insulation material. Calculate the required insulation layer thickness for each spray section based on the thermal boundary condition model.

[0012] Step 4: Compare the required insulation layer thickness of each spray section with the allowable thickness of the limited installation space. For spray sections where the insulation layer thickness is greater than the allowable thickness of the limited installation space, use the allowable thickness of the limited installation space as the target insulation layer thickness, calculate the maximum allowable thermal conductivity of the insulation material for that spray section, and select the insulation material for that spray section based on the comparison between the actual thermal conductivity of the candidate insulation materials and the maximum allowable thermal conductivity.

[0013] Step 5: Based on the heat loss from the wall surface, the thermal resistance of the grid, the thickness of the insulation layer, the maximum allowable thermal conductivity of the insulation material, and the screening results of candidate insulation materials for each spray section, determine the spray sections to be optimized if the insulation layer thickness exceeds the allowable thickness of the limited installation space, the candidate insulation material does not meet the thermal conductivity requirements, or the grid thermal resistance does not meet the preset efficiency enhancement requirements.

[0014] Step 6: Determine the processing order for the spray sections to be adjusted according to the following order: heat loss from the wall surface from largest to smallest, insulation layer thickness exceeding the limit from largest to smallest, and thermal conductivity margin of the insulation material from smallest to largest. Then, determine the cause of adjustment for each section according to the processing order. When the cause of adjustment includes excessive insulation layer thickness or insufficient thermal conductivity of the insulation material, replace the insulation material or adjust the insulation layer locally first. When the cause of adjustment includes insufficient thermal resistance of the chord grid, or when the measured outer wall temperature of the insulation layer is still higher than the target temperature after replacing the insulation material and adjusting the insulation layer locally, adjust the chord grid arrangement of the corresponding spray section and recalculate the chord grid thermal resistance, heat loss from the wall surface, insulation layer thickness, and maximum allowable thermal conductivity of the insulation material for that spray section until all spray sections meet the target outer wall temperature of the insulation layer and the allowable thickness requirements of the limited installation space.

[0015] In a preferred implementation, further, in step 1, the step of collecting the gas phase parameters, liquid phase parameters, air flow parameters, wall temperature parameters, and stable operating time of each spray section, and determining the heat loss from the wall of each spray section based on the energy conservation relationship, includes: dividing the multi-stage smoke washing and heat dissipation device into spray sections 1 to n along the airflow direction, where n is an integer not less than 2; for the i-th spray section, collecting its inlet air temperature. Export temperature Water supply temperature Water temperature after heat exchange Water supply quality Mass of liquid after heat exchange Airflow quality and stable running time The heat loss from the wall surface of the i-th spray section is determined according to the following formula:

[0016] ;

[0017] In the formula: The heat loss from the wall surface of the i-th spray section; The airflow mass of the i-th stage spray section; The specific heat capacity of air at constant pressure; The inlet temperature of the i-th stage spray section; The outlet temperature of the i-th stage spray section; The specific heat capacity of water at constant pressure; Water supply quality for the i-th stage spray section; The water supply temperature for the i-th stage spray section; The water temperature after heat exchange in the i-th stage spray section; The latent heat of phase change of water; Let be the mass of the liquid after heat exchange in the i-th stage spray section.

[0018] In a preferred implementation, further, in step 2, calculating the thermal resistance of each spray section under stable operating conditions with and without a chord grid includes: when the i-th level spray section is without a chord grid, calculating the thermal resistance of the spray section without a chord grid according to the following formula:

[0019] ;

[0020] When setting a chord grid in the i-th stage spray section, the thermal resistance of the spray section when setting the chord grid is calculated according to the following formula: ;

[0021] In the formula: The thermal resistance of the i-th stage spray section when no chord grid is set; To set the thermal resistance of the i-th stage spray section when setting the chord grid; and The stable operating times of the i-th stage spray section are respectively the times when no chord grid is set and the times when a chord grid is set. and The inlet air temperatures of the i-th stage spray section are respectively the air temperature without and with the chord grid. and The outlet air temperatures of the i-th stage spray section are respectively the air temperature without and with the chord grid. and The water supply quality of the i-th stage sprinkler section is shown for the i-th stage without and with a chord grid, respectively. and The values ​​represent the liquid mass after heat exchange in the i-th stage spray section when there is no chord grid and when there is a chord grid, respectively. and These represent the water supply temperatures of the i-th stage spray section when no chord grid is installed and when a chord grid is installed, respectively. and These represent the water temperatures after heat exchange in the i-th stage spray section, with and without a chord grid, respectively. The specific heat capacity of water at constant pressure; is the latent heat of phase change of water.

[0022] In a preferred implementation, further, in step 2, determining the chordal thermal resistance of the spray segment based on the difference in thermal resistance of the spray segment before and after the chordal grid is set includes: determining the chordal thermal resistance of the i-th stage spray segment according to the following formula:

[0023] ;

[0024] In the formula: Let be the chordal thermal resistance of the i-th spray section; To set the thermal resistance of the i-th stage spray section when setting the chord grid; The thermal resistance of the i-th stage spray section when no chord grid is set;

[0025] The inlet air temperature, outlet air temperature, water supply temperature, water temperature after heat exchange, water supply quality, liquid quality after heat exchange, air flow quality, and stable operating time of the i-th stage spray section under the chord grid state are used as the operating parameters for calculating the insulation layer thickness of the i-th stage spray section.

[0026] In a preferred implementation, further, in step 3, calculating the required insulation layer thickness for each spray section includes: determining the heat loss from the wall surface after setting the chord grid in the i-th stage spray section according to the following formula based on the operating parameters of the i-th stage spray section under the chord grid setting state:

[0027] ;

[0028] The required insulation layer thickness for the i-th spray section is calculated using the following formula:

[0029] ;

[0030] In the formula: Heat loss on the wall surface after setting the chord grid for the i-th stage spray section; To set the airflow mass of the i-th stage spray section after the chord grid; The specific heat capacity of air at constant pressure; To set the inlet air temperature of the i-th stage spray section after the chord grid; To set the outlet air temperature of the i-th stage spray section after setting the string grid; The specific heat capacity of water at constant pressure; To determine the water supply quality of the i-th stage spray section after setting the chord grid; To set the water supply temperature for the i-th stage of the spray section after the chord grid; The water temperature after heat exchange in the i-th stage spray section after setting the chord grid; The latent heat of phase change of water; The mass of the liquid after heat exchange in the i-th stage spray section after setting the chord grid; The required insulation layer thickness for the i-th spray section; The thermal conductivity of the insulation material used in the i-th spray section; The area covered by the insulation material in the i-th spray section; To determine the stable operating time of the i-th stage spray section after setting the chord grid; The temperature of the inner wall side of the i-th spray section; The target temperature of the outer wall of the insulation layer in the i-th spray section.

[0031] In a preferred implementation, further, in step 4, for spray sections where the insulation layer thickness is greater than the allowable thickness of the confined installation space, the allowable thickness of the confined installation space is used as the target insulation layer thickness, and the maximum allowable thermal conductivity of the insulation material for that spray section is calculated, including: when the required insulation layer thickness of the i-th level spray section... Thickness greater than the allowable thickness of the limited installation space At that time, with The target insulation layer thickness for the i-th level spray section The maximum allowable thermal conductivity of the insulation material for the i-th spray section is calculated according to the following formula:

[0032] ;

[0033] In the formula: The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section; The target insulation layer thickness for the i-th spray section; To set the airflow mass of the i-th stage spray section after the chord grid; The water-to-air ratio before mass exchange in the i-th stage spray section. ; The water-to-air ratio after mass exchange in the i-th stage spray section. ; To determine the water supply quality of the i-th stage spray section after setting the chord grid; The mass of the liquid after heat exchange in the i-th stage spray section after setting the chord grid; The specific heat capacity of air at constant pressure; The specific heat capacity of water at constant pressure; The latent heat of phase change of water; The area covered by the insulation material in the i-th spray section; To determine the stable operating time of the i-th stage spray section after setting the chord grid; The temperature of the inner wall side of the i-th spray section; The target temperature of the outer wall of the insulation layer in the i-th spray section.

[0034] In a preferred implementation, further, in step 5, the step of selecting the insulation material for the spray section based on the comparison result between the actual thermal conductivity of the candidate insulation material and the maximum allowable thermal conductivity includes: selecting the actual thermal conductivity of the j-th candidate insulation material for the i-th spray section. The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section Compare; when: When the j-th candidate insulation material is included in the range of usable materials for the i-th spray section; when the following conditions are met: When the j-th candidate insulation material is excluded, then... The actual thermal conductivity of the j-th candidate insulation material in the i-th spray section; The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section.

[0035] In a preferred implementation, further, in step 5, determining the spray section whose insulation layer thickness exceeds the allowable thickness of the limited installation space, whose candidate insulation material does not meet the thermal conductivity requirements, or whose chord thermal resistance does not meet the preset efficiency enhancement requirements as the spray section to be adjusted includes: when the i-th level spray section meets any of the following conditions, the i-th level spray section is determined as the spray section to be adjusted: , , ,in, The required insulation layer thickness for the i-th spray section; The allowable thickness for the i-th level spray section within the confined installation space; The actual thermal conductivity of the j-th candidate insulation material in the i-th spray section; The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section; The thermal resistance of the chord grid in the i-th stage spray segment; The lower limit of the thermal resistance of the chord grid in the i-th stage spray section; the lower limit of the thermal resistance of the chord grid is calculated according to... It is confirmed that, among them, The lower limit coefficient of the chord thermal resistance is taken as 0.05 to 0.15; The thermal resistance of the i-th stage spray section when no chord grid is set.

[0036] In a preferred implementation, further, in step 6, the process of determining the processing order for the spray sections to be adjusted according to the following order: heat loss from the wall surface from largest to smallest, degree of exceeding the insulation layer thickness limit from largest to smallest, and thermal conductivity margin of the insulation material from smallest to largest. This includes: first determining the processing order for multiple spray sections to be adjusted, and then judging the reasons for adjustment for each section according to the processing order; for the first... The spray section to be adjusted is used to read the heat loss from the wall surface of that spray section. Required insulation layer thickness Limited installation space allows for thickness The maximum permissible thermal conductivity of insulation materials The actual thermal conductivity of the insulation material to be used Chord grid thermal resistance According to the required insulation layer thickness With limited installation space, allowable thickness Determined that the thickness exceeds the limit :

[0037] ;

[0038] According to the maximum permissible thermal conductivity of the insulation material Compared with the actual thermal conductivity of the insulation material to be used Determine the thermal conductivity margin of the material : For any two spray sections to be adjusted and First, determine the processing order according to the amount of heat loss from the wall, when the following conditions are met: At that time, the first The first spray section precedes the second. First-stage spray section treatment; when the following conditions are met: In such cases, the processing order should be determined according to the extent of the thickness exceeding the limit;

[0039] When the following conditions are met: At that time, the first The first spray section precedes the second. First-stage spray section treatment; when the following conditions are met: When the material's thermal conductivity margin is satisfied, the processing order should be determined accordingly; when the following conditions are met: At that time, the first The first spray section precedes the second. First-stage spray treatment; after determining the treatment sequence, proceed with the second stage. Determine the reason for the need for adjustment in the first-stage spray section; when the first... The spray section to be adjusted meets the following requirements: Or it satisfies: If the insulation material of the spray section is still insufficient, first replace it; if the insulation material replacement still meets the requirements... or still satisfied Then, within the limited installation space, the allowable thickness The insulation layer of the high-temperature outer wall area of ​​the spray section is locally adjusted; when the first The spray section to be adjusted meets the following requirements: Alternatively, after replacing the insulation material and adjusting the local insulation layer, the measured temperature of the outer wall of the insulation layer under stable operating conditions can be obtained. Still satisfied: At that time, for the first The arrangement of the chords in the primary spray section was adjusted;

[0040] In the formula: For the first Heat loss occurs on the walls of the spray section; For the first Heat loss occurs on the walls of the spray section; For the first The thickness of the spray section exceeds the limit; For the first The thickness of the spray section exceeds the limit; For the first Thermal conductivity margin of the spray section material; For the first Thermal conductivity margin of the spray section material; For the first The required insulation layer thickness for the primary spray section; For the first The allowable thickness of the spray section within the limited installation space; For the first The maximum permissible thermal conductivity of the insulation material for the first-stage spray section; For the first The actual thermal conductivity of the insulation material to be used in the first-stage spray section; For the first Thermal resistance of the chord grid in the spray section; For the first Lower limit of thermal resistance of the chord grid in the spray section; For the first Measured temperature of the outer wall of the insulation layer in the spray section; For the first Target temperature of the outer wall of the insulation layer of the spray section.

[0041] In a preferred implementation, further, in step 6, the step of... The arrangement of the chord grid in the first-stage spray section is adjusted, including: when the first... The spray section meets the requirements And the first When the outlet temperature of the primary spray section is higher than the set outlet temperature, determine whether the spray section has an installation length along the airflow direction to increase the number of chord grid rows; if it has an installation length, add a row of chord grids downstream of the original chord grids, arrange the new chord grids in the spray droplet coverage area, and the flow interval between the new chord grids and the original chord grids is not less than 5 times the diameter of the grid bars.

[0042] If increasing the number of chord rows results in a lower airflow quality than the design airflow quality, then the newly added chords should be removed, and the spacing between the existing chord bars should be reduced. When reducing the bar spacing, the first... Projected occlusion rate of the multi-stage spray grating satisfy: And satisfy: ,in: , , , , After the chord arrangement is adjusted, the first... The spray section underwent a new operational test with the chord grid reconfigured. Inlet air temperature, outlet air temperature, supply water temperature, post-heat exchange water temperature, supply water quality, post-heat exchange liquid quality, airflow quality, and stable operating time were re-collected. The thermal resistance of the spray section after the chord grid reconfiguration was also recalculated. Wire grid thermal resistance Heat loss from the wall Required insulation layer thickness The maximum permissible thermal conductivity of insulation materials When the first After recalculation and retesting, the first-stage spray section simultaneously meets the following requirements: , , , At that time, the first... Treatment of the primary spray section;

[0043] In the formula: For the first The occlusion rate of the chordal grid projection of the spray section; For the first The preset shading limit for the spray section; The projected blocking area of ​​the chord grid bars on a cross section perpendicular to the airflow direction; For the first Cross-sectional area of ​​the primary spray section; The residual pressure of the induced draft fan can be used for adjusting the chord spacing; The static pressure that the induced draft fan can provide under the design airflow mass; This refers to the basic resistance loss of the flue gas washing and heat dissipation device under the design airflow mass before the adjustment of the chord spacing. To reserve a safe pressure differential; For the first Airflow velocity in the first-stage spray section; For the first Airflow quality in the spray section; For the first Gas density in the first spray section; Add drag loss to the chord grid; This represents the drag coefficient of the chord grid. This is the correction factor for the grid bar shape; This is the residual pressure distribution coefficient; To set the string grid after the first Thermal resistance of the spray section; For the first Thermal resistance of the chord grid in the spray section; For the first Heat loss occurs on the walls of the spray section; For the first The required insulation layer thickness for the primary spray section; For the first The allowable thickness of the spray section within the limited installation space; For the first The maximum permissible thermal conductivity of the insulation material for the first-stage spray section; For the first The actual thermal conductivity of the insulation material to be used in the first-stage spray section; For the first Lower limit of thermal resistance of the chord grid in the spray section; For the first Measured temperature of the outer wall of the insulation layer in the spray section; For the first Target temperature of the outer wall of the insulation layer of the spray section.

[0044] The beneficial effects of this invention are:

[0045] First, the thermal resistance insulation design method for a multi-stage flue gas scrubbing and heat dissipation device proposed in this application does not rely solely on experience to determine the grating structure and insulation scheme of the multi-stage flue gas scrubbing and heat dissipation device under limited installation space. Instead, it first divides the device into multiple spray sections along the airflow direction, and determines the heat loss from the wall of each spray section based on the actual collected gas phase parameters, liquid phase parameters, air flow parameters, wall temperature parameters, and stable operating time, thereby obtaining the heat load of each spray section under actual operating conditions. Then, it quantitatively characterizes the synergistic effect of the grating on the heat and mass exchange of the same spray section before and after the installation of the grating by using the thermal resistance difference of the same spray section before and after the installation of the grating. The thermal boundary conditions after the grating synergy are used to calculate the insulation layer thickness, so that the internal synergistic structure design and the external insulation design correspond to each other. At the same time, when the calculated insulation layer thickness exceeds the allowable thickness of the limited installation space, the maximum allowable thermal conductivity of the insulation material of the spray section is calculated in reverse. Based on this, candidate insulation materials are screened to avoid insufficient insulation layer thickness leading to excessive external wall temperature or excessive insulation layer thickness affecting the internal layout. Furthermore, this invention also determines the spray section to be optimized based on wall heat loss, chord thermal resistance, insulation layer thickness, the maximum allowable thermal conductivity of the insulation material, and the candidate material screening results. The processing order is determined according to heat load, thickness exceeding limit, and material thermal conductivity margin. The problem of insufficient insulation is solved first by material replacement or local insulation layer adjustment. If the target external wall temperature or chord thermal resistance still cannot be met, the chord arrangement is adjusted and recalculated. This allows for segmented and quantitative design based on the actual heat load differences of different spray sections, improving the accuracy of external wall temperature control, reducing problems such as insufficient pre-stage insulation, redundant post-stage insulation, and local external wall temperature runaway. This enables the multi-stage smoke washing and heat dissipation device to balance cooling efficiency, insulation safety, and installation space constraints within a confined space.

[0046] Secondly, in the preferred implementation, step 1 of the present invention further divides the multi-stage smoke washing and heat dissipation device into multiple spray sections along the airflow direction, and collects the inlet and outlet air temperature, water supply temperature, water temperature after heat exchange, water supply quality, liquid quality after heat exchange, air flow quality, and stable operating time for each spray section. Then, based on the energy conservation relationship, the heat loss of the wall surface of the corresponding section is calculated. This can refine the originally estimated heat dissipation load of the device to each spray section, accurately reflect the heat load differences caused by the airflow temperature drop, water temperature change, and different spray heat exchange intensity in different sections, and provide reliable thermal boundary conditions for subsequent segmented determination of chord thermal resistance, insulation layer thickness, and insulation material selection.

[0047] Third, in the preferred implementation, step 2 of the present invention further calculates the thermal resistance of the same spray section under two stable operating conditions: without a chord and with a chord. The difference between the two is used to determine the chord thermal resistance of the spray section. This can transform the synergistic effect of the chord on the heat and mass exchange process between the airflow and the spray liquid into a quantifiable thermal resistance parameter, avoiding the need to judge the effect of the chord arrangement based solely on experience.

[0048] Fourth, in the preferred implementation, further, in step 3 of the present invention, after determining the synergistic effect of the string grid in each spray section, the heat loss of the wall surface of the corresponding spray section is calculated using the operating parameters under the string grid state. Based on this, the required insulation layer thickness is calculated in combination with the thermal conductivity of the insulation material of the spray section, the coverage area of ​​the insulation material, the stable operating time, the temperature of the inner wall side of the spray section and the target temperature of the outer wall of the insulation layer. This makes the insulation layer thickness no longer uniformly determined based on the overall empirical value of the device, but matched with the actual heat load of each spray section after the string grid synergistic effect.

[0049] Fifth, in the preferred implementation, further, in step 4 of the present invention, when the required insulation layer thickness for each spray section exceeds the allowable thickness of the limited installation space, the insulation layer thickness is no longer simply increased. Instead, the allowable thickness of the limited installation space is used as the target insulation layer thickness. Combined with the air flow mass after the chord grid is set in the spray section, the water-air ratio before and after mass exchange, the air temperature change, the water temperature change, the stable operation time, the insulation material coverage area, and the target inner and outer wall temperatures, the maximum allowable thermal conductivity of the insulation material of the spray section is calculated in reverse. Under the condition of limited installation space, the selection of insulation material can be directly related to the actual heat load and target outer wall temperature of the spray section, so that there is a clear quantitative basis for judging whether the candidate insulation material meets the requirements.

[0050] Sixth, in the preferred implementation, further, in step 5 of the present invention, after back-calculating the maximum allowable thermal conductivity of the insulation material for each spray section, the actual thermal conductivity of different candidate insulation materials is compared one by one with the maximum allowable thermal conductivity of the corresponding spray section. This can clearly determine whether each candidate material is suitable for the spray section, avoiding insufficient insulation or material redundancy due to material selection based solely on experience. In addition, the state of each spray section is determined by combining whether the insulation layer thickness exceeds the allowable thickness of the limited installation space, whether the candidate insulation material meets the thermal conductivity requirements, and whether the chord thermal resistance meets the preset efficiency enhancement requirements. Spray sections with excessive thickness, unsuitable materials, or insufficient chord efficiency are identified as spray sections to be adjusted, which can accurately screen out the local sections that need to be optimized in the multi-stage smoke washing and heat dissipation device.

[0051] Seventh, in the preferred implementation, further, in step 6 of the present invention, after screening out the spray sections to be adjusted, the processing priority is determined according to the heat loss from the wall surface, the excess thickness of the insulation layer, and the thermal conductivity margin of the insulation material. Spray sections with higher heat load, more severe space exceedance, or smaller material margin are prioritized for optimization. Depending on the reason for adjustment, insulation material replacement, local insulation layer adjustment, or ductwork arrangement adjustment are adopted. When adjusting the ductwork, constraints are made in combination with outlet air temperature, installable length, ductwork shading rate, airflow mass, additional resistance loss, and exhaust fan margin to prevent simply increasing the ductwork from causing excessive flow resistance or insufficient ventilation capacity. After each adjustment, the operating parameters are re-collected and the ductwork thermal resistance, heat loss from the wall surface, insulation layer thickness, and the maximum allowable thermal conductivity of the insulation material are recalculated so that each spray section ultimately meets the requirements of the target temperature of the outer wall, the allowable thickness of the limited installation space, and the thermal conductivity of the insulation material. Attached Figure Description

[0052] Figure 1 A schematic flowchart illustrating the thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device provided by this invention;

[0053] Figure 2 Schematic diagram of the multi-stage smoke washing and heat removal device provided by the present invention Figure 1 ;

[0054] Figure 3 Schematic diagram of the multi-stage smoke washing and heat removal device provided by the present invention Figure 2 . Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] As per the instruction manual Figure 1 This invention provides a thermal resistance insulation design method for a multi-stage flue gas scrubbing and heat dissipation device. This method is applied to flue gas scrubbing and heat dissipation devices with multi-stage spray cooling structures. Given a fixed device structure, airflow direction, number of spray stages, and limited installation space, it determines the insulation layer thickness, thermal conductivity requirements of the insulation material, and the adjustment method of the chord arrangement for each spray section based on the gas-liquid heat transfer parameters of each spray section, the change in thermal resistance before and after the installation of the chord grid, and the heat dissipation of the outer wall. To facilitate the explanation of the specific implementation process of this method, the following describes... Figure 2 and Figure 3 The four-stage spray-type flue gas washing and heat dissipation device shown is described. The structure of the device itself can adopt the form of an existing multi-stage flue gas washing and heat dissipation device. The method of the present invention uses this device as the object of parameter acquisition and calculation.

[0057] As per the instruction manual Figure 2-3 The smoke washing and heat dissipation device used in this embodiment is a multi-stage spray-type smoke washing and heat dissipation structure. The smoke washing and heat dissipation device 5 is provided with a first-stage spray section 11, a second-stage spray section 22, a third-stage spray section 33, and a fourth-stage spray section 44 in sequence along the airflow direction. Each spray section is connected sequentially along the length of the device body, so that the high-temperature airflow entering the device body can pass through each spray section in sequence for cooling and disinfection.

[0058] A heat source 6 is located on the inlet side of the flue gas scrubbing and heat dissipation device 5, providing the device with a high-temperature airflow to be treated. An induced draft fan 7 is located on the exhaust side of the device, guiding the high-temperature airflow along the sequence of the first-stage spray section 11, the second-stage spray section 22, the third-stage spray section 33, and the fourth-stage spray section 44. A wastewater tank 8 is located below the device, collecting the liquid formed after heat exchange between the spray liquid and the high-temperature airflow in each spray section. Spray nozzles are provided in each spray section, oriented towards the airflow channel of the corresponding section, allowing the spray liquid to enter and contact the high-temperature airflow. A grid is installed in the gas-liquid contact area of ​​the corresponding spray section. An external insulation layer is installed on the outer wall of the device, covering the corresponding outer wall areas of the first-stage spray section 11, the second-stage spray section 22, the third-stage spray section 33, and the fourth-stage spray section 44.

[0059] To implement the method of this invention, temperature acquisition points are respectively set at the airflow inlet and outlet sides of each spray section to collect the air temperature before and after heat and mass exchange in each spray section. Water temperature and water volume acquisition points are set at the water supply end of each spray section to collect the water supply temperature and mass. Temperature and mass acquisition devices are set at the wastewater tank 8 or the corresponding collection point to collect the liquid temperature and mass after heat exchange. Air flow rate acquisition points are set at the induced draft fan 7 or within the airflow channel to obtain the air flow mass. Wall temperature acquisition points are set on the outer wall of the smoke washing and heat dissipation device 5 to obtain the temperature of the corresponding outer wall area of ​​each spray section. The above acquisition points are used to obtain the calculation parameters of each spray section and do not limit the smoke washing and heat dissipation device 5 to using a specific type of sensor or a fixed installation method.

[0060] The method specifically includes the following steps:

[0061] Step 1: Divide the multi-stage smoke washing and heat removal device into multiple spray sections along the airflow direction. Operate the multi-stage smoke washing and heat removal device in a simulated ventilation environment corresponding to the confined installation space. Collect the gas phase parameters, liquid phase parameters, air flow parameters, wall temperature parameters, and stable operation time of each spray section. Determine the heat loss from the wall of each spray section based on the energy conservation relationship.

[0062] Specifically, based on the flow direction of the high-temperature airflow within the multi-stage flue gas scrubbing and heat dissipation device, the device is sequentially divided into the first-stage spray section, the second-stage spray section, and so on, up to the nth-stage spray section, where n is an integer ≥ 2. For each spray section, the outlet airflow position of the previous spray section is used as the airflow inlet position, and the airflow position after the current spray section is used as the airflow outlet position. For the first-stage spray section, its airflow inlet position is where the high-temperature airflow enters the flue gas scrubbing and heat dissipation device; for the nth-stage spray section, its airflow outlet position is where the airflow leaves the flue gas scrubbing and heat dissipation device.

[0063] Before the test, the multi-stage smoke scrubbing and heat dissipation device was placed in a simulated ventilation environment corresponding to the confined installation space. This simulated ventilation environment was set according to the actual installation space's ventilation volume, inlet air temperature, exhaust resistance, and surrounding heat dissipation conditions. The heat source and induced draft fan were started, allowing high-temperature airflow to enter the smoke scrubbing and heat dissipation device at a predetermined airflow rate. After the airflow rate stabilized, the spray mechanisms corresponding to each spray section were activated, allowing the spray water to contact and exchange heat with the high-temperature airflow within each spray section. The spray water volume for each spray section was set according to the designed water-to-air ratio, which is the ratio of the mass of water supplied to the mass of air flowing through that spray section, denoted as [formula missing]. ,and In one specific parameter embodiment, the design water-to-air ratios for the first, second, third, and fourth spray sections are 0.20, 0.18, 0.15, and 0.12, respectively. When the outlet air temperature or the water temperature after heat exchange fails to meet the stability test requirements during prototype operation, the spray water volume of the corresponding spray section is fine-tuned, and the actual water supply quality after fine-tuning is used. This serves as a parameter for subsequent calculations of heat loss from the wall surface and insulation layer thickness.

[0064] When collecting parameters for the i-th level spray section, the inlet air temperature of that level spray section is collected. Export temperature Water supply temperature Water temperature after heat exchange Water supply quality Mass of liquid after heat exchange Airflow quality Spray section wall temperature and stable operating time Among them, the entrance temperature and export temperature The water supply temperature was measured by temperature sensors placed in the airflow channels before and after the corresponding spray section. The water temperature after heat exchange was measured by the temperature acquisition device at the water supply end. The water supply quality is measured by temperature sensors at the corresponding collection points in the wastewater tank or spray section. The mass of the liquid after heat exchange is obtained by accumulating the flow rate from the flow meter in the water supply pipeline over the operating time. The mass of the airflow was measured by a mass acquisition device in the wastewater tank or the corresponding collection area. It is calculated by combining the wind speed data collected at the induced draft fan or in the airflow channel with the channel cross-sectional area and gas density.

[0065] Stable running time The time limit is calculated from the moment the spray section enters continuous heat exchange until the outlet air temperature, post-heat exchange water temperature, and wall temperature of the spray section reach relative stability. As an optional determination method, if the outlet air temperature, post-heat exchange water temperature, and wall temperature change do not exceed 1°C, and the wall temperature change does not exceed 0.5°C within 5 consecutive minutes, the spray section is considered to have reached a relatively stable state, and the corresponding stable operating time tᵢ is recorded. If the sensor accuracy or operating conditions of the actual device differ, the above temperature change limits can be adjusted according to sensor error and the designed external wall temperature control requirements.

[0066] After obtaining the above parameters for the i-th stage spray section, the heat loss from the wall surface of this stage spray section is determined according to the energy conservation principle. The heat released by the high-temperature airflow in the i-th stage spray section is:

[0067]

[0068] The heat absorbed by the spray liquid during the temperature rise in the i-th stage of the spray is:

[0069]

[0070] The heat absorbed by the sprayed liquid during the phase change in the i-th stage spray section is:

[0071]

[0072] In the formula: The specific heat capacity of air at constant pressure; γ is the specific heat capacity of water at constant pressure; γ is the latent heat coefficient of water during phase change. The above physical properties were determined according to the temperature and pressure conditions during the experiment.

[0073] Heat loss from the wall surface of the i-th stage spray section Determined according to the following formula:

[0074]

[0075] when When it is positive, it indicates that there is heat dissipated outward through the wall in the i-th stage of the spray section; when... When the value is close to 0, it indicates that the heat released by the high-temperature airflow in this spray section is primarily absorbed by the heating and phase change of the spray liquid. If the calculation yields... If the value is negative, verify whether the inlet air temperature, outlet air temperature, water supply quality, post-heat exchange liquid quality, and sampling time correspond to the same steady-state condition, and re-collect the parameters for that spray section. Through the above method, the wall heat loss from the first to the nth spray sections is obtained sequentially. , until The heat loss from the walls of each spray section serves as the basis for subsequent calculations of the chord thermal resistance, insulation layer thickness, and insulation material selection.

[0076] Step 2: Calculate the thermal resistance of each spray section under stable operating conditions with and without the chord grid, and determine the chord grid thermal resistance of the same spray section by the difference in thermal resistance before and after the chord grid is installed.

[0077] Specifically, operational tests were conducted on each spray section under two conditions: without and with the chord grid. The thermal resistance of the chord grid at that stage was determined by the difference in thermal resistance between the two conditions. To ensure a correlation between the two test results, the same spray section division method should be used for both the test without and with the chord grid, and the inlet airflow position, outlet airflow position, water supply position, and post-heat exchange liquid collection position of the spray section should remain consistent.

[0078] Taking the i-th level spray section as an example, initially, without installing a duct grid in this spray section, the heat source, induced draft fan, and spray mechanism are started to operate this spray section under the same simulated ventilation environment as in step 1. Without the duct grid, the inlet air temperature of this spray section is collected. Export temperature Water supply temperature Water temperature after heat exchange Water supply quality Mass of liquid after heat exchange and stable running time All the above parameters were recorded after the outlet air temperature, heat exchange water temperature and wall temperature of the spray section reached relative stability. The method for determining the stable state was the same as in step 1.

[0079] Without a chord grid, the mainstream heat exchanged per unit time in this spray section Calculate using the following formula:

[0080]

[0081] In the formula: γ is the specific heat capacity of water at constant pressure; γ is the latent heat coefficient of water during phase change. The first term in this equation... The second term represents the heat absorbed per unit time corresponding to the temperature rise of the sprayed liquid. This represents the heat absorbed per unit time corresponding to the phase change of the sprayed liquid.

[0082] When no chord grid is installed, the thermal resistance Rᵖʳᵉᵢ of the i-th stage spray section is calculated by the following formula:

[0083]

[0084] Furthermore, After substituting the values, the thermal resistance of the spray section without a chord grid is obtained. :

[0085]

[0086] After completing the test without a chord grid, install a chord grid within the gas-liquid contact area of ​​the i-th stage spray section. The chord grid should be positioned within the channel where the spray droplets contact the high-temperature gas flow, with both ends fixed to the inner wall of the spray section or to a mounting bracket. The grid bars are arranged along the cross-sectional direction of the spray section, and the bar spacing, bar diameter, number of bars, and the angle between the bars and the airflow direction are determined according to the evaluation scheme. If the spray section has multiple rows of chord grids, the distance between each row should be recorded in the test record.

[0087] After setting the grating, restart the heat source, induced draft fan, and spray mechanism to ensure the i-th stage spray section operates under the same settings. To minimize testing errors, the deviation in airflow quality between the two tests should be ≤3%, inlet air temperature deviation ≤2℃, water supply temperature deviation ≤1℃, and water supply quality deviation ≤3%. If any parameter exceeds the above range during the actual test, the heat source, induced draft fan, or water supply flow rate should be readjusted before recording.

[0088] When setting the chord grid, the inlet air temperature of that spray section is collected. Export temperature Water supply temperature Water temperature after heat exchange Water supply quality Mass of liquid after heat exchange and stable running time When a chord grid is set, the mainstream heat exchanged per unit time in this spray section is... Calculate using the following formula:

[0089]

[0090] When setting the chord grid, the thermal resistance of the i-th stage spray section Calculate using the following formula:

[0091]

[0092] Furthermore, After substituting the values, the thermal resistance of the spray section after setting the chord grid is obtained. :

[0093]

[0094] The chordal thermal resistance of the i-th stage spray section Determine using the following formula:

[0095]

[0096] In the formula: This represents the change in thermal resistance corresponding to the chord grid in the i-th stage spray section; To set the thermal resistance of the spray section after the chord grid; This represents the thermal resistance of the spray section without a chord grid. If... A positive value indicates that the calculated thermal resistance of the corresponding spray section increases after the chord grid is set; if... A value close to 0 indicates that the arrangement of the chord grid has little impact on the calculated thermal resistance of the spray section; if If the value is negative, it should be checked whether the airflow quality, inlet temperature, water supply quality and stabilization time of the two tests are under the same set conditions, and whether the installation position of the chord grid has changed the airflow distribution near the temperature measurement point.

[0097] Furthermore, the chordal thermal resistance of the spray sections from the first stage to the nth stage is obtained sequentially. , until The inlet air temperature, outlet air temperature, water supply temperature, water temperature after heat exchange, water supply quality, liquid quality after heat exchange, air flow quality, and stable operating time of each spray section after the chord grid is set are used as the operating parameters for calculating the insulation layer thickness of each spray section in step 3. The parameters when the chord grid is not set are only used to calculate the thermal resistance difference of the corresponding spray section.

[0098] Step 3: Determine the heat loss from the wall surface and the temperature of the wall surface to be insulated in each spray section using the stable operating parameters after setting the chord grid. Establish a thermal boundary condition model after chord grid enhancement based on the heat loss from the wall surface, the temperature of the wall surface to be insulated, and the coverage area of ​​the insulation material. Calculate the required insulation layer thickness for each spray section based on the thermal boundary condition model.

[0099] Specifically, step 2 obtains the chord thermal resistance of the i-th stage spray segment. Then, the thermal resistance of the string grid is... The thermal resistance of the chord is associated with the number of chord rows, the spacing between the bars, the diameter of the bars, the angle between the bars, and the installation position. The inlet air temperature measured under the same chord arrangement in step 2 is also read. Export temperature Water supply temperature Water temperature after heat exchange Water supply quality Mass of liquid after heat exchange Airflow quality and stable running time Among them, the thermal resistance of the string grid This parameter characterizes the change in thermal resistance caused by the corresponding chord arrangement relative to the state without chords, and serves as a parameter in step 5 to determine whether the degree of chord enhancement meets the preset requirements; and is related to the chord thermal resistance. The corresponding stable operating parameters after setting the chord grid are used to determine the actual thermal boundary conditions under the chord grid arrangement.

[0100] Based on the same energy conservation principle as in step 1, determine the heat loss on the wall surface of the i-th stage spray section after the chord grid is installed. :

[0101]

[0102] In the formula: The specific heat capacity of air at constant pressure; The specific heat capacity at constant pressure of the sprayed liquid; The latent heat of phase change of the sprayed liquid; The heat released by the high-temperature airflow in the i-th stage spray section; Sensible heat absorbed by the sprayed liquid to raise its temperature; The latent heat absorbed by the unrecovered spray liquid during phase change. The difference between the heat released by the airflow and the sensible and latent heat absorbed by the spray liquid is taken as the wall heat loss of the i-th stage spray section transferred outward through the device wall in the current chord arrangement. .

[0103] Determine the wall area where the insulation layer will be installed in the i-th level spray section, and divide the wall area into sections based on the wall shape, spray section length, and temperature measuring point locations. The temperature measurement sub-regions are non-overlapping, and each sub-region has one wall temperature measuring point. The boundary between adjacent temperature measurement sub-regions is set at the midpoint of the line connecting the adjacent wall temperature measuring points. The temperature measurement sub-region located at the edge of the wall to be insulated uses the actual boundary of the wall to be insulated as its outer boundary.

[0104] The actual wall area covered by the r-th temperature measurement sub-region is denoted as . ,in, For the r-th temperature measurement sub-region, Let be the area of ​​the wall element in the r-th temperature measurement sub-region. This application divides the region along the wall based on the shortest distance from any point on the wall to each temperature measurement point, using each wall temperature measurement point as the center. The area of ​​the wall where the distance from the r-th wall temperature measurement point is no greater than the distance from any other wall temperature measurement point is defined as the r-th temperature measurement sub-region. ,in, For the first All wall surfaces in the spray section that require insulation. For any point on the wall surface to be insulated, For the first Location of each wall temperature measuring point For the first Location of each wall temperature measuring point It is the shortest distance between two points along the wall surface to be insulated.

[0105] Actual wall area This represents the area of ​​the wall surface to be insulated corresponding to and characterized by the r-th wall temperature measurement point, excluding the area of ​​other temperature measurement sub-regions adjacent to this sub-region. The sum of the actual wall areas of all temperature measurement sub-regions is equal to the area covered by the insulation material of the i-th spray section. ,Right now .

[0106] During a stable operating period with parameters identical to the inlet air temperature, outlet air temperature, supply water temperature, post-heat exchange water temperature, and mass parameters, temperature data at wall temperature measurement points within each temperature measurement sub-region are continuously collected. The stable wall temperature of the r-th temperature measurement sub-region during the stable operating period is... Determine using the following formula:

[0107]

[0108] In the formula: For the first After the first-stage spray section is equipped with a chord grid, the second stage... The stable wall temperature of each temperature measurement sub-region during the stable operating period; For the first The first stage of the spray section The number of temperature measurements collected in each temperature measurement sub-region during a stable operating period; For the first After the first-stage spray section is equipped with a chord grid, the second stage... The temperature measurement sub-region during the stable operation period The wall temperature collected in the second sampling; The temperature acquisition order is as follows, and ; The spray section is numbered according to its level, and ; Number the temperature measurement sub-regions, and The superscript "sub" indicates that the corresponding parameter is the first... The parameters are measured or calculated after the chord grid is set in the spray section.

[0109] Based on the stable wall temperature and actual wall area of ​​each temperature measurement sub-region, calculate the area-weighted average wall temperature of the i-th spray section:

[0110]

[0111] In the formula: For the first Area-weighted average wall temperature after setting a chord grid in the multi-stage spray section; For the first The total number of temperature measurement sub-regions divided into the wall surface to be insulated in the spray section; For the first The first stage of the spray section The actual wall area covered by the temperature measurement sub-region, i.e., the first... The area of ​​the wall surface to be insulated, represented by each wall temperature measuring point; For the first After the first stage of spray section is equipped with a chord grid, the second stage of spray section The stable wall temperature of each temperature measurement sub-region; For the first The total wall area of ​​the spray section to be insulated is also the sum of the actual wall areas of each temperature measurement sub-area, i.e. Among them, the temperature measurement sub-regions do not overlap with each other and together cover the first... All wall surfaces to be insulated in the spray section. Therefore, the stable wall temperature corresponding to the larger temperature measurement sub-region has a larger weight in the area-weighted average wall temperature; when the actual wall areas of each temperature measurement sub-region are equal, the area-weighted average wall temperature is equal to the arithmetic mean of the stable wall temperatures of each temperature measurement sub-region.

[0112] Further determine the highest stable wall temperature in each temperature measurement sub-region of the i-th stage spray section. and minimum stable wall temperature And calculate the wall temperature range. :

[0113]

[0114]

[0115]

[0116] The measurement uncertainties of the temperature acquisition devices used to measure the highest and lowest stable wall temperatures are denoted as follows: and Temperature non-uniformity judgment limit of the i-th level spray section for:

[0117]

[0118] Temperature of the wall surface to be insulated in the i-th stage spray section for:

[0119]

[0120] When the wall temperature is extremely different The temperature non-uniformity judgment limit was not exceeded. When the temperature difference between the various temperature measurement sub-regions is within the measurement error range, the area-weighted average wall temperature is used as the wall temperature to be insulated. When the wall temperature range exceeds the temperature non-uniformity judgment limit, it indicates that there is a local high temperature area in the i-th level spray section. The highest stable wall temperature is used as the wall temperature to be insulated to avoid insufficient local insulation caused by calculating based on the average temperature.

[0121] According to the heat loss from the wall of the i-th spray section Insulation material coverage area and stable running time Determine the wall heat flux density after setting the chord grid in the i-th stage spray section. :

[0122]

[0123] Wall heat flux density This represents the amount of heat transferred outward per unit time through a unit area of ​​the wall to be insulated under the current string grid arrangement, air flow rate, and spray water volume conditions of the i-th stage spray section.

[0124] Taking the contact point between the outer wall of the device and the insulation material in the i-th stage of the spray section as the starting point of the insulation layer thickness direction, and taking the direction perpendicular to the outer wall of the device and pointing outward of the insulation layer as the positive coordinate direction, a coordinate system for the insulation layer thickness direction is established. ,in Corresponding to the inner interface of the insulation layer, Corresponding to the outer wall of the insulation layer.

[0125] From wall heat flux density Temperature of the wall surface to be insulated and the target temperature of the outer wall of the insulation layer Establish the thermal boundary condition model for the i-th stage spray section after chord enhancement:

[0126]

[0127] In the formula: The spray section is numbered according to its level, and ; For the first The position coordinates of the insulation layer in the spray section along its thickness are defined with the interface between the wall to be insulated and the insulation layer as the origin, and the positive direction as the direction perpendicular to the wall to be insulated and pointing outwards from the insulation layer. ; This indicates the inner interface of the insulation layer, i.e., the interface between the insulation layer and the first... The contact position of the wall surface to be insulated in the spray section; This indicates the outer interface of the insulation layer, that is, the position where the insulation layer comes into contact with the external environment; For the first Location coordinates of the insulation layer in the spray section The temperature at that location is used to represent the temperature distribution of the insulation layer along its thickness, and the unit is Celsius or Kelvin. For the first Temperature gradient along the thickness direction of the insulation layer in the spray section; For the first The one-dimensional thermal conductivity control equation for the insulation layer of the spray section under the conditions of no internal heat source, steady state, and heat transfer mainly along the thickness direction of the insulation layer; For the first The equivalent thermal conductivity of the insulation material used in the primary spray section is taken as the temperature of the insulation material at the surface of the wall to be insulated. Target temperature of the outer wall of the insulation layer The thermal conductivity within the formed temperature range; when the thermal conductivity changes little with temperature Take the average value within that temperature range; when the change in thermal conductivity with temperature is not negligible, A function representing temperature, i.e. The unit is watts per meter Kelvin; For the first After the chord grid is set in the spray section, the temperature of the wall to be insulated is determined under stable operation and is also used as the temperature boundary of the inner interface of the insulation layer. When the temperature distribution of the wall to be insulated is uniform, the area-weighted average of the stable wall temperature of each temperature measurement sub-region is taken. When there is a local high temperature area on the wall to be insulated that exceeds the temperature non-uniformity judgment limit, the highest stable wall temperature in each temperature measurement sub-region is taken. For the first After the spray section is equipped with a chord grid, the heat flux density transferred from the wall to be insulated to the insulation layer under stable operating conditions is expressed in watts per square meter; the negative sign indicates that heat is transferred along the direction of decreasing temperature; due to the coordinate system... From the hotter wall surface to the outside of the cooler insulation layer, there is usually... This results in the outward transfer of wall heat flux density. It is a positive value; For the first The required insulation layer thickness for the spray section is the vertical distance from the inner interface of the insulation layer to the outer interface of the insulation layer, in meters. For the first Calculated temperature of the outer interface of the insulation layer in the first-stage spray section; For the first The target temperature of the outer wall of the insulation layer of the spray section is determined based on the safe temperature for personnel contact, the allowable temperature of adjacent equipment, and the environmental conditions of the confined installation space; when multiple temperature limits exist simultaneously, the lowest value among the allowable temperatures is taken. Indicates the thickness of the insulation layer The calculated outer wall temperature of the insulation layer should not exceed the predetermined target temperature.

[0128] Based on the safe temperature requirements for surfaces accessible to personnel, the allowable operating temperature of adjacent equipment, and the ambient temperature within the confined installation space, the target temperature of the outer wall of the insulation layer in the i-th level spray section is determined. When the outer wall of the insulation layer is subject to both the safe temperature for personnel contact and the allowable temperature of adjacent equipment, the lower of the two temperatures shall be taken as the target temperature for the outer wall of the insulation layer.

[0129] Under steady-state one-dimensional thermal conductivity conditions, the temperature distribution along the thickness direction of the insulation layer in the i-th stage spray section is as follows:

[0130]

[0131] To bring the temperature of the outer wall of the insulation layer to the target temperature, that is:

[0132]

[0133] To obtain the theoretical insulation layer thickness required for the i-th stage spray section :

[0134]

[0135] wall heat flux density After substituting, we get:

[0136]

[0137] Further reduce heat loss from the wall surface After substituting, we get:

[0138]

[0139] Calculated The theoretical insulation layer thickness required to ensure that the outer wall temperature of the insulation layer does not exceed the target temperature under the current chord arrangement, air flow rate, spray water volume, and thermal conductivity of the insulation material for the i-th stage spray section.

[0140] When multiple candidate insulation materials exist in the same spray section, the equivalent thermal conductivity of the j-th candidate insulation material within the corresponding temperature range is denoted as . Substitute the values ​​into the insulation layer thickness calculation formula to obtain the theoretical insulation layer thickness for each candidate insulation material. :

[0141]

[0142] The correspondence between candidate insulation materials, thermal conductivity, and theoretical insulation layer thickness is retained, and the theoretical insulation layer thickness corresponding to the proposed insulation material is denoted as the required insulation layer thickness for the i-th level spray section. For step 4 and the thickness allowed by the limited installation space The comparison is then performed. Step 4 is based on the insulation layer thickness obtained in Step 3, which is used to compare the allowable thickness and back-calculate the maximum thermal conductivity.

[0143] when and When, the insulation layer thickness is calculated according to the above thermal boundary condition model. When the temperature is approximately 0, it indicates that the heat transferred outward from the wall surface in the i-th spray section is relatively small. Based on whether the temperature of the wall to be insulated is higher than the target temperature of the outer wall of the insulation layer, it is determined whether to install the insulation layer according to the minimum construction thickness of the candidate insulation material. If this occurs, it indicates that the currently collected air-side heat release, sensible heat absorption of the spray liquid, and latent heat absorption of phase change do not satisfy the steady-state energy conservation relationship. The inlet air temperature, outlet air temperature, supply water temperature, post-heat exchange water temperature, supply water quality, post-heat exchange liquid quality, air flow quality, and stable operating time must be checked to ensure they correspond to the same stable operating period. Negative values ​​should not be used to calculate the insulation layer thickness; the thickness calculation should only proceed after verification. When the temperature of the wall surface to be insulated is no higher than the target temperature of the outer wall of the insulation layer, it indicates that the current temperature of the wall surface to be insulated is no higher than the target temperature of the outer wall of the insulation layer. Based on the requirements for anti-condensation, fire resistance, and minimum construction thickness, it is determined whether a base insulation layer needs to be configured. Through the above method, the required insulation layer thicknesses for the first to nth spray sections are obtained sequentially. , Until .

[0144] Step 4: Compare the required insulation layer thickness for each spray section with the allowable thickness for the limited installation space. For spray sections where the insulation layer thickness is greater than the allowable thickness for the limited installation space, use the allowable thickness for the limited installation space as the target insulation layer thickness. Calculate the maximum allowable thermal conductivity of the insulation material for that spray section. Select the insulation material for that spray section based on the comparison between the actual thermal conductivity and the maximum allowable thermal conductivity of the candidate insulation materials.

[0145] Specifically, the required insulation layer thickness for each spray section obtained in step 3... Each with the allowable thickness of the limited installation space Comparison. Limited installation space allows for thickness. This refers to the maximum thickness of the insulation layer that can be installed between the outer wall of the i-th level spray section and surrounding equipment, bulkheads, maintenance access routes, or pipelines, determined through on-site measurements or installation models. For different spray sections, The values ​​can be the same, or they can vary depending on the installation location.

[0146] when ≤ This indicates that when using the current candidate insulation material for this spray section, the required thickness does not exceed the allowable thickness within the confined installation space. Therefore, this spray section is... Configure an insulation layer. When considering construction errors, in... Increase the reserved thickness on the basis ,and +δᵢ≤ Reserved thickness Determined based on the compression of the insulation material. When > At that time, The target insulation layer thickness for the i-th spray section And calculate the maximum allowable thermal conductivity of the insulation material in that spray section. Before back-calculation, first calculate the water-to-air ratio before mass exchange after setting the chord grid in this spray section. Water-to-gas ratio after mass exchange :

[0147]

[0148]

[0149] In the formula: This represents the ratio of the mass of the spray water to the mass of the air flowing through it before the i-th stage of the spray section enters the heat and mass exchange phase. This represents the ratio of the mass of the liquid after heat exchange to the mass of the air flowing through it.

[0150] The maximum permissible thermal conductivity of the insulation material in the i-th stage spray section is... Calculate using the following formula:

[0151]

[0152] get Then, the actual thermal conductivity of the candidate insulation materials was determined. and Compare them, where j represents the j-th candidate insulation material. If the following conditions are met... If the j-th candidate insulation material can be included in the range of usable materials for the i-th spray section, then... > If the j-th candidate insulation material is not included in the range of usable materials for that level of spray section, then the selection should be based on temperature resistance rating, flame retardant rating, moisture resistance, construction thickness deviation, and fixing method. It should be noted that the above selection does not change the... The calculation results. When the actual thermal conductivity of all candidate insulation materials is greater than... When this occurs, record the spray section as a material-constrained spray section and retain the data for that spray section. , , and each candidate material This is used in step 5 to determine the spray section to be adjusted.

[0153] Step 5: Based on the heat loss from the wall surface, the thermal resistance of the chord grid, the thickness of the insulation layer, the maximum allowable thermal conductivity of the insulation material, and the screening results of candidate insulation materials for each spray section, determine the spray sections to be optimized if the insulation layer thickness exceeds the allowable thickness of the limited installation space, the candidate insulation material does not meet the thermal conductivity requirements, or the chord grid thermal resistance does not meet the preset efficiency enhancement requirements.

[0154] Specifically, the spray sections to be adjusted are determined based on the calculation results of each spray section. For the i-th level spray section, at least the following data should be recorded: heat loss from the wall surface. Wire grid thermal resistance Required insulation layer thickness Limited installation space allows for thickness The maximum permissible thermal conductivity of insulation materials and the actual thermal conductivity of candidate insulation materials .

[0155] When the i-th level spray segment satisfies or Under any of these conditions, it is identified as the spray section to be adjusted. This represents the actual thermal conductivity of the candidate insulation materials to be used in this spray section. When there are multiple candidate materials for this spray section, if none of the candidate materials meet the requirements... ≤ If the conditions are met, then the spray section at that level is determined to be a spray section to be adjusted.

[0156] or ,in, This is the lower limit of the chordal thermal resistance of the i-th stage spray section. The thermal resistance was determined through prototype testing, or based on the thermal resistance of the spray section without a chord grid. A certain proportion is determined. For example:

[0157]

[0158] In the formula: This is the lower limit coefficient of the chord thermal resistance, which can be taken as 0.05 to 0.15. For the pre-stage high-temperature spray section, A value close to 0.15 can be taken; for the subsequent low-temperature spray section, A value close to 0.05 can be used. If the same spray section has the same conditions of excessive thickness, unsatisfactory material, and insufficient chord thermal resistance, it will be recorded as only one spray section to be adjusted, but all unsatisfactory conditions will be retained for use in step 6 to determine the processing order.

[0159] To facilitate sorting, the thickness exceeding the limit is calculated separately for each spray section to be adjusted. and material thermal conductivity margin Thickness exceeds limit Δ Determine using the following formula:

[0160]

[0161] when ≤ At that time, Δ Recorded as 0. Material thermal conductivity margin. Determine using the following formula:

[0162]

[0163] In the formula: Let be the actual thermal conductivity of the insulation material to be used in the i-th stage spray section. A negative value indicates that the thermal conductivity of the proposed insulation material exceeds the allowable value for that spray section. A positive value indicates that the thermal conductivity of the proposed insulation material still has a margin of safety. If the proposed material has not yet been determined, the material with the lowest thermal conductivity among the candidate materials is selected. Perform sorting calculations.

[0164] Step 6: Determine the processing order for the spray sections to be adjusted according to the following sequence: heat loss from the wall surface from largest to smallest, insulation layer thickness exceeding the limit from largest to smallest, and thermal conductivity margin of the insulation material from smallest to largest. Then, determine the cause of adjustment for each section according to the processing order. When the cause of adjustment includes excessive insulation layer thickness or insulation material thermal conductivity not meeting the requirements, first replace the insulation material or adjust the insulation layer locally. When the cause of adjustment includes the chord thermal resistance not meeting the preset requirements, or the measured outer wall temperature of the insulation layer is still higher than the target temperature after insulation material replacement and local insulation layer adjustment, adjust the chord arrangement of the corresponding spray section, and recalculate the chord thermal resistance, heat loss from the wall surface, insulation layer thickness, and maximum allowable thermal conductivity of the insulation material for that spray section, until each spray section meets the target temperature of the outer wall of the insulation layer and the allowable thickness requirements of the limited installation space.

[0165] Specifically, based on the spray sections to be adjusted determined in step 5, the processing order between each spray section to be adjusted is first determined. Then, the reason for adjustment of each individual spray section to be adjusted is determined, and the corresponding processing method is selected according to the reason for adjustment. The spray sections to be adjusted are not processed simultaneously, but are processed one by one in the processing order. After the current spray section to be adjusted is processed and recalculated to meet the requirements, the next spray section to be adjusted is then moved on to.

[0166] For the i-th stage of the spray section to be adjusted, read the heat loss from the wall surface of that spray section. Required insulation layer thickness Limited installation space allows for thickness The maximum permissible thermal conductivity of insulation materials The actual thermal conductivity of the insulation material to be used and grid thermal resistance .according to and The difference determines the thickness exceeding the limit. :

[0167]

[0168] according to and The difference determines the material's thermal conductivity margin. :

[0169]

[0170] In the formula: Δ The thickness of the i-th spray section exceeds the limit; The required insulation layer thickness for the i-th spray section; The allowable thickness for the i-th level spray section within the confined installation space; This is the thermal conductivity margin for the material of the i-th spray section; The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section; Let be the actual thermal conductivity of the insulation material to be used in the i-th stage spray section.

[0171] When multiple spray sections belong to the category of spray sections to be adjusted, for any two spray sections i and j to be adjusted, the processing order is first determined according to the magnitude of heat loss from the wall. If the following conditions are met: If the i-th level spray section is treated before the j-th level spray section, then the i-th level spray section will be treated first.

[0172] When the heat loss from both walls meets the following condition: At this point, it is assumed that the heat loss from both walls is similar, and the processing order is determined according to the degree of thickness exceeding the limit. If the following conditions are met: If the i-th level spray section is treated before the j-th level spray section, then the i-th level spray section will be treated first.

[0173] When the thickness of both exceeds the limit, the following conditions are met: When the thicknesses of the two materials are considered to be close in excess, the processing order is determined according to the margin of the material's thermal conductivity. If the following conditions are met: If the i-th level spray section is treated before the j-th level spray section, then the i-th level spray section will be treated first.

[0174] After determining the processing order, first determine the reason for adjustment for the i-th level spray segment that needs adjustment. When the i-th level spray segment needs adjustment satisfies: Or it satisfies: If the spray section is found to have deficiencies in insulation thickness or thermal conductivity, the insulation material for that section should be replaced. During material replacement, materials meeting the requirements of limited installation space in terms of temperature resistance, flame retardancy, and moisture resistance are selected from the candidate insulation materials, and the actual thermal conductivity of each candidate insulation material is compared. For the j-th candidate insulation material, if it satisfies: If the following conditions are met: the candidate insulation material is included in the range of usable materials for the i-th level spray section; If a candidate insulation material is not found to meet the criteria, it is excluded. If multiple candidate insulation materials meet the criteria, the material with the lowest thermal conductivity and that meets the construction thickness requirements is selected as the replacement material. The thermal conductivity of this replacement material is then substituted into the insulation layer thickness calculation formula in step 3 to recalculate the required insulation layer thickness for the i-th level spray section. .

[0175] If the recalculation satisfies: Furthermore, the measured temperature of the outer wall of the insulation layer of the i-th stage spray section under stable operating conditions was obtained. Not higher than the target temperature of the outer wall of the insulation layer of the spray section. If the material replacement process is completed for that spray section, no further adjustments to the local insulation layer or chord arrangement are required. The criteria for determining the outer wall temperature of the insulation layer are: ,in, This represents the measured temperature at the temperature measuring point on the outer wall of the insulation layer corresponding to the i-th level spray section; when multiple temperature measuring points are set on the outer wall of the insulation layer for this level of spray section... Take the highest measured temperature among multiple temperature measurement points.

[0176] If the following conditions are still met after material replacement: Or it may still satisfy: Then, the local insulation layer of the i-th spray section is adjusted. Before the local insulation layer adjustment, the stable temperature of multiple temperature measuring points on the outer wall of the spray section is read. Let the stable temperature of the r-th temperature measuring point be... The average temperature of the outer wall of the i-th spray section is When the temperature measurement point meets the following conditions: At that time, the area on the outer wall where the temperature measuring point is located is defined as the local coverage area. The local coverage area covers the section of the outer wall where the high-temperature temperature measuring point is located along the airflow direction, and extends upstream and downstream by a predetermined length respectively. The preset length satisfies:

[0177]

[0178] In the formula: is the length of the i-th spray section along the airflow direction.

[0179] If the distance between two adjacent high-temperature measuring points satisfy: Then the outer wall area between the two high-temperature measuring points will be merged into a local coverage area.

[0180] When adjusting the local insulation layer, a partial covering layer is added to the outside of the original insulation layer, or a wall-mounted insulation layer is added to the inside of the original insulation layer. The maximum thickness after partial covering... Should meet: If there is still a thickness margin after partial covering, the covering thickness of the area corresponding to the high-temperature measurement point should be increased first; if the thickness margin is insufficient, the local covering area should be expanded without increasing the maximum thickness. After completing the local insulation layer adjustment, the outer wall temperature of the insulation layer in the locally covered area should be remeasured under the same operating conditions. If the following conditions are met: And satisfy: Then the local insulation layer adjustment of the spray section is completed.

[0181] When the i-th level spray section to be adjusted satisfies: At that time, or after replacing the insulation material and adjusting the local insulation layer, it still meets the following requirements: At this point, the arrangement of the chord grid in the i-th level spray section is adjusted. Instead of continuing to increase the thickness of the insulation layer for this spray section, the arrangement of the chord grid is adjusted, and the operating parameters of the spray section under the chord grid setting are re-acquired after the adjustment.

[0182] When adjusting the arrangement of the chord grids, first determine whether the i-th stage spray section has the installation length to increase the number of chord grid rows along the airflow direction. If there is still a reserved length between the chord grid installation area and the outlet of the spray section, and the outlet temperature of the i-th stage spray section is higher than the set outlet temperature, then add a row of chord grids downstream of the original chord grids. The new chord grids are arranged within the spray droplet coverage area. A flow gap is maintained between the new chord grids and the original chord grids, and the flow gap is not less than 5 times the diameter of the grid bars. After adding the chord grids, re-measure the air flow mass, inlet temperature, outlet temperature, water temperature after heat exchange, water supply mass, liquid mass after heat exchange, and stable operating time, and recalculate. If the following conditions are met: If the airflow quality is not lower than the design airflow quality, the newly added chord grid is retained; if the airflow quality is lower than the design airflow quality, the newly added chord grid is removed, and the spacing of the existing chord grid bars is adjusted instead.

[0183] When adjusting the grid bar spacing, decrease it gradually from the original spacing, with each decrease being 5%-10% of the original spacing. After each adjustment, calculate the projected shading rate of the chord grid on the cross-section of the i-th level spray section. :

[0184]

[0185] In the formula: The projected blocking area of ​​the chord grid bars on a cross section perpendicular to the airflow direction; Let be the cross-sectional area of ​​the i-th spray section.

[0186] Projection occlusion rate Should meet: ,in, Set a maximum shielding limit for the i-th level spray section. The residual pressure of the induced draft fan, which can be used to adjust the chord spacing, is determined first. The design airflow mass of the i-th stage spray section is then obtained. The flow cross-sectional area below Gas density And the static pressure that the induced draft fan can provide under this airflow mass. The foundation resistance loss of the flue gas scrubbing and heat dissipation device under the design airflow mass was measured before the adjustment of the chord spacing. Reserve a safety pressure difference. Afterwards, the induced draft fan can be used to adjust the residual pressure of the chord spacing. Determine using the following formula:

[0187]

[0188] In the formula: It is used to compensate for resistance deviations caused by pipeline resistance fluctuations, spray droplet entrainment, and changes in wastewater tank level.

[0189] The airflow velocity of the i-th stage spray section for:

[0190]

[0191] Additional drag loss caused by the chord grid Estimate using the following formula:

[0192]

[0193] String grid drag coefficient for:

[0194]

[0195] In the formula: This is a correction factor for the shape of the grid bars; when the grid bars are round rods... Take 1.1 to 1.3; when the grid bars are flat bars, Take a value between 1.3 and 1.6.

[0196] The additional drag loss after adjusting the chord spacing satisfies:

[0197]

[0198] In the formula: λ is the residual pressure distribution coefficient, ranging from 0.4 to 0.6. Based on the above relationship, the maximum shading rate that satisfies the resistance condition is obtained, and this maximum shading rate is used as the preset shading upper limit for the i-th stage spray section. When calculated When the value is greater than 0.35, 0.35 is used as the preset occlusion limit; when the calculated value is... When the value is less than 0.20, the bar spacing will not be further reduced.

[0199] If the grid spacing is reduced, the outlet temperature will decrease. Not less than If the airflow quality meets the design requirements, the current grid spacing is retained. If continuous liquid accumulation at the chord grid, increased droplet fall, or insufficient airflow quality occurs, the current grid spacing is restored to the previous level.

[0200] If, after reducing the spacing between the grid bars, the high-temperature area on the wall remains concentrated on one side of the spray section, or if the temperature of that side of the wall is more than 3°C higher than the temperature of the other side, then adjust the angle between the grid bars and the airflow direction. The angle adjustment should be based on the original angle, increasing gradually by 5° to 10° each time; the angle should not exceed 60°. After adjusting the angle, re-measure the wall temperatures on both sides of the spray section, the outlet air temperature, and the airflow quality. If the temperature difference between the two walls decreases, the outlet air temperature decreases, and the airflow quality meets the design requirements, then retain the current angle; if the airflow quality decreases below the design value, or the wall temperature difference does not decrease, then revert to the previous angle level.

[0201] After the chord grid arrangement is adjusted, the i-th stage spray section is retested with the chord grid set. The inlet air temperature, outlet air temperature, supply water temperature, post-heat exchange water temperature, supply water quality, post-heat exchange liquid quality, air flow quality, and stable operating time are collected again. The thermal resistance of the spray section after the chord grid is set is also recalculated. Wire grid thermal resistance Heat loss from the wall Required insulation layer thickness The maximum permissible thermal conductivity of insulation materials .

[0202] The processing of a spray segment ends when the following conditions are met simultaneously after recalculation and retesting of the i-th level spray segment:

[0203]

[0204]

[0205]

[0206]

[0207] The remaining spray sections to be adjusted are processed sequentially in the same manner as described above. When the adjustment of the chord arrangement of the current spray section changes the inlet temperature of the next spray section, the inlet temperature, outlet temperature, water temperature after heat exchange, and stable operating time of the next spray section are collected again. The wall heat loss, insulation layer thickness, and maximum allowable thermal conductivity of the insulation material of the next spray section are recalculated, and then it is determined whether the next spray section is still a spray section to be adjusted.

[0208] Example

[0209] This embodiment uses a four-stage spray-type smoke and heat dissipation device as an example. This device is installed in a simulated ship cabin ventilation environment, with a target temperature of [missing information - likely a temperature range] on the outer wall of the insulation layer. At 50℃, allowable thickness for each spray section within the confined installation space. All thicknesses are 25mm. Stable operating time for each spray section. All values ​​are taken as 600s, and the specific heat capacity of air at constant pressure is... Take 1.005 kJ / (kg·℃) as the specific heat capacity of water at constant pressure. Take 4.18 kJ / (kg·℃) as the latent heat of phase change of water. The thermal conductivity of the initial candidate insulation material is 2256 kJ / kg. Take 0.045 W / (m·K).

[0210] The stable operating parameters of the four spray sections after the installation of the chord grid are shown in Table 1:

[0211] Table 1

[0212]

[0213] Calculate the first according to the following formula. Heat loss from the walls of the spray section:

[0214]

[0215] Taking the first-stage spray section as an example:

[0216]

[0217] Calculated using the same method, the heat loss from the walls of the second-stage spray section, the third-stage spray section, and the fourth-stage spray section are 56.05 kJ, 114.99 kJ, and 227.21 kJ, respectively.

[0218] Thermal conductivity of initial candidate insulation materials Under the given conditions, calculate the required insulation layer thickness for each spray section using the following formula:

[0219]

[0220] in, When substituting, convert to J. The required insulation layer thickness for the first-stage spray section is:

[0221]

[0222] The required insulation layer thickness for the first-stage spray section is 30.69 mm. The insulation layer thicknesses for the second, third, and fourth-stage spray sections are calculated in the same way, and are 30.35 mm, 6.34 mm, and 1.71 mm, respectively.

[0223] Therefore, when using the initial candidate material with a thermal conductivity of 0.045 W / (m·K), the required insulation layer thickness for both the first and second spray stages is greater than 25 mm, necessitating material screening or further adjustments; the required insulation layer thickness for the third and fourth spray stages is less than 25 mm. For the first spray stage, a target insulation layer thickness of 25 mm is set based on the allowable thickness within the limited installation space. The maximum allowable thermal conductivity of the insulation material can be calculated by reverse calculation. Since the thickness of the insulation layer is directly proportional to the thermal conductivity of the insulation material, therefore... For the second-stage spray section .

[0224] Candidate insulation materials include materials A, B, and C, with thermal conductivity coefficients of 0.045 W / (m·K), 0.038 W / (m·K), and 0.034 W / (m·K), respectively. In both the first and second stage spray sections, the thermal conductivity of materials A and B is greater than that of their corresponding materials. The thermal conductivity of material C is less than that of the corresponding material. Therefore, material C is selected for both the first and second stage spray sections. Substituting the thermal conductivity of material C (0.034 W / (m·K)) into the thickness calculation formula, the required insulation layer thickness for the first stage spray section is... The required insulation layer thickness for the second-stage spray section is: Both of these thicknesses are less than 25mm, which meets the allowable thickness requirements for confined installation space.

[0225] Furthermore, the thermal resistance of the second-stage spray section was determined by the chord grid. The thermal resistance of the second-stage spray section without the chord grid was measured experimentally. The thermal resistance of the spray section after the original chord grid is set at 20.20 K / kW. If the value is 20.60 K / kW, then the thermal resistance of the second-stage spray section chord is... The lower limit coefficient of thermal resistance of the second-stage spray section chord grid If we take 0.05, then ,At The second-level spray section was identified as the spray section to be adjusted.

[0226] When adjusting the chord arrangement of the second-stage spray section, it was first determined that the installation length of the spray section along the airflow direction was insufficient to add a row of chords. Therefore, the spacing of the existing chord bars was adjusted. The original bar spacing was 20mm, and after reducing it by 10%, the bar spacing was adjusted to 18mm.

[0227] Before adjustment, the static pressure provided by the induced draft fan was measured. The base resistance loss is 650 Pa. The pressure is 420Pa, with a safety differential pressure reserved. If the pressure is 50 Pa, then the residual pressure available for adjusting the chord spacing in the second-stage spray section is: .

[0228] After adjustment, calculate the shading rate of the second-stage spray section chord grid projection. The value is 0.24; based on the additional resistance loss of the chord grid, the preset upper limit of shading for the second-stage spray section is [value missing]. The value is 0.30, which satisfies the condition. ,Right now Therefore, the adjusted bar spacing is retained.

[0229] After rerunning the test, the thermal resistance of the second-stage spray section after setting the chord grid was determined. If it is 21.48K / kW, then At this time, it is satisfied The heat loss from the wall surface of the second-stage spray section was recalculated under this chord grid arrangement, and the results were obtained. When using material C, the required insulation layer thickness for the second-stage spray section is: That is, the required insulation layer thickness for the second-stage spray section is 22.6mm, which is less than 25mm.

[0230] The required insulation layer thicknesses for the third and fourth spray sections, based on the initial candidate materials, are 6.34 mm and 1.71 mm, respectively, both less than 25 mm. The chord thermal resistance of both spray sections is not lower than the corresponding lower limit value; therefore, no material replacement or chord arrangement adjustment is required. Considering the insulation material's construction thickness and fixing requirements, the third and fourth spray sections will be configured with insulation layers of at least 10 mm thickness.

[0231] After completing the above treatment, the four-stage spray-type smoke scrubbing and heat dissipation device was run again under the same simulated ventilation environment. The highest temperature of the outer wall of the insulation layer in each spray section was measured as shown in Table 2:

[0232] Table 2

[0233]

[0234] If all four spray sections use an initial candidate material with a thermal conductivity of 0.045 W / (m·K) and are all limited by an installation thickness of 25 mm, then the outer wall temperature of the insulation layer corresponding to the first and second spray sections can be calculated using the following formula:

[0235]

[0236] The outer wall temperature of the insulation layer in the first-stage spray section with a thickness of 25mm is:

[0237]

[0238] The outer wall temperature of the insulation layer in the second-stage spray section with a thickness of 25mm is:

[0239]

[0240] All of the above temperatures are above 50°C. Using the method of this embodiment, the first and second spray sections can select C material with a lower thermal conductivity based on the calculated insulation material. The second spray section further adjusts the grid spacing according to the lower limit requirement of the chord thermal resistance. During the re-run test, the highest measured temperature of the outer wall of the insulation layer in each spray section did not exceed 50°C, and the actual configuration thickness did not exceed 25mm.

[0241] The multi-stage smoke washing and heat dissipation device thermal resistance insulation design method of the present invention divides the device into multiple spray sections according to the airflow direction. Gas phase, liquid phase, air flow, wall temperature, and operating time parameters are collected for each spray section. The heat loss from the wall surface of each spray section is calculated. The thermal resistance of the spray section is calculated under two conditions: without and with a grating. The difference between the two conditions determines the grating thermal resistance. Then, the required insulation layer thickness for each spray section is calculated using the operating parameters after the grating is installed. When the required thickness exceeds the allowable thickness of the limited installation space, the maximum allowable thermal conductivity of the insulation material is calculated and insulation materials are selected. For spray sections with excessive thickness, unsuitable materials, or insufficient grating thermal resistance, the processing sequence is determined according to the wall heat loss, the amount of thickness exceeding the limit, and the material thermal conductivity margin. By replacing the insulation material, locally adding an insulation layer, or adjusting the grating arrangement, the corresponding spray section can meet the target external wall temperature and installation thickness requirements.

[0242] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics of the solutions is not described in detail here. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A thermal resistance insulation design method for a multi-stage smoke scrubbing and heat dissipation device, characterized in that, The method includes: Step 1: Divide the multi-stage smoke washing and heat removal device into multiple spray sections along the airflow direction. Run the multi-stage smoke washing and heat removal device in a simulated ventilation environment corresponding to the limited installation space. Collect the gas phase parameters, liquid phase parameters, air flow parameters, wall temperature parameters and stable operation time of each spray section. Determine the heat loss of the wall of each spray section based on the energy conservation relationship. Step 2: Calculate the thermal resistance of each spray section under stable operating conditions with and without the chord grid, and determine the chord grid thermal resistance of the spray section by the difference in thermal resistance of the same spray section before and after the chord grid is installed. Step 3: Determine the heat loss from the wall surface and the temperature of the wall surface to be insulated in each spray section using the stable operating parameters after setting the chord grid. Establish a thermal boundary condition model after chord grid enhancement based on the heat loss from the wall surface, the temperature of the wall surface to be insulated, and the coverage area of ​​the insulation material. Calculate the required insulation layer thickness for each spray section based on the thermal boundary condition model. Step 4: Compare the required insulation layer thickness of each spray section with the allowable thickness of the limited installation space. For spray sections where the insulation layer thickness is greater than the allowable thickness of the limited installation space, use the allowable thickness of the limited installation space as the target insulation layer thickness, calculate the maximum allowable thermal conductivity of the insulation material for that spray section, and select the insulation material for that spray section based on the comparison between the actual thermal conductivity of the candidate insulation materials and the maximum allowable thermal conductivity. Step 5: Based on the heat loss from the wall surface, the thermal resistance of the grid, the thickness of the insulation layer, the maximum allowable thermal conductivity of the insulation material, and the screening results of candidate insulation materials for each spray section, determine the spray sections to be optimized if the insulation layer thickness exceeds the allowable thickness of the limited installation space, the candidate insulation material does not meet the thermal conductivity requirements, or the grid thermal resistance does not meet the preset efficiency enhancement requirements. Step 6: Determine the processing order for the spray sections to be adjusted according to the following order: heat loss from the wall surface from largest to smallest, insulation layer thickness exceeding the limit from largest to smallest, and thermal conductivity margin of the insulation material from smallest to largest. Then, determine the cause of adjustment for each section according to the processing order. When the cause of adjustment includes excessive insulation layer thickness or insufficient thermal conductivity of the insulation material, replace the insulation material or adjust the insulation layer locally first. When the cause of adjustment includes insufficient thermal resistance of the chord grid, or when the measured outer wall temperature of the insulation layer is still higher than the target temperature after replacing the insulation material and adjusting the insulation layer locally, adjust the chord grid arrangement of the corresponding spray section and recalculate the chord grid thermal resistance, heat loss from the wall surface, insulation layer thickness, and maximum allowable thermal conductivity of the insulation material for that spray section until all spray sections meet the target outer wall temperature of the insulation layer and the allowable thickness requirements of the limited installation space.

2. The thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device according to claim 1, characterized in that, In step 1, the process of collecting gas phase parameters, liquid phase parameters, air flow parameters, wall temperature parameters, and stable operating time for each spray section, and determining the heat loss from the wall of each spray section based on the energy conservation relationship, includes: dividing the multi-stage smoke washing and heat dissipation device into spray sections 1 to 1n along the airflow direction, where n is an integer not less than 2; for the 1st spray section, collecting its inlet air temperature. Export temperature Water supply temperature Water temperature after heat exchange Water supply quality Mass of liquid after heat exchange Airflow quality and stable running time The heat loss from the wall surface of the i-th spray section is determined according to the following formula: ； In the formula: The heat loss from the wall surface of the i-th spray section; The airflow mass of the i-th stage spray section; The specific heat capacity of air at constant pressure; The inlet temperature of the i-th spray section; The outlet temperature of the i-th stage spray section; The specific heat capacity of water at constant pressure; Water supply quality for the i-th stage sprinkler section; The water supply temperature for the i-th stage spray section; The water temperature after heat exchange in the i-th stage spray section; The latent heat of phase change of water; Let be the mass of the liquid after heat exchange in the i-th stage spray section.

3. The thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device according to claim 2, characterized in that, In step 2, calculating the thermal resistance of each spray section under stable operating conditions with and without a chord grid includes: when the i-th stage spray section is without a chord grid, calculating the thermal resistance of the spray section without a chord grid according to the following formula: ； When setting a chord grid in the i-th stage spray section, the thermal resistance of the spray section when setting the chord grid is calculated according to the following formula: ; In the formula: The thermal resistance of the i-th stage spray section when no chord grid is set; To set the thermal resistance of the i-th stage spray section when setting the chord grid; and The stable operating times of the i-th stage spray section are respectively the times when no chord grid is set and the times when a chord grid is set. and The inlet air temperatures of the i-th stage spray section are respectively the air temperature without and with the chord grid. and The outlet air temperatures of the i-th stage spray section are respectively the air temperature without and with the chord grid. and The water supply quality of the i-th stage sprinkler section is shown for the i-th stage without and with a chord grid, respectively. and The values ​​represent the liquid mass after heat exchange in the i-th stage spray section when there is no chord grid and when there is a chord grid, respectively. and These represent the water supply temperatures of the i-th stage spray section when no chord grid is installed and when a chord grid is installed, respectively. and These represent the water temperatures after heat exchange in the i-th stage spray section, with and without a chord grid, respectively. The specific heat capacity of water at constant pressure; is the latent heat of phase change of water.

4. The thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device according to claim 3, characterized in that, In step 2, determining the chordal thermal resistance of the spray section based on the difference in thermal resistance of the spray section before and after the chordal grid is set includes: determining the chordal thermal resistance of the i-th stage spray section according to the following formula: ； In the formula: Let be the chordal thermal resistance of the i-th spray section; To set the thermal resistance of the i-th stage spray section when setting the chord grid; The thermal resistance of the i-th stage spray section when no chord grid is set; The inlet air temperature, outlet air temperature, water supply temperature, water temperature after heat exchange, water supply quality, liquid quality after heat exchange, air flow quality, and stable operating time of the i-th stage spray section under the chord grid state are used as the operating parameters for calculating the insulation layer thickness of the i-th stage spray section.

5. The thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device according to claim 4, characterized in that, In step 3, calculating the required insulation layer thickness for each spray section includes: determining the heat loss from the wall surface after setting the chord grid in the i-th stage spray section according to the following formula based on the operating parameters of the i-th stage spray section under the chord grid setting state: ； The required insulation layer thickness for the i-th spray section is calculated using the following formula: ； In the formula: Heat loss on the wall surface after setting the chord grid for the i-th stage spray section; To set the airflow mass of the i-th stage spray section after the chord grid; The specific heat capacity of air at constant pressure; To set the inlet air temperature of the i-th stage spray section after the chord grid; To set the outlet air temperature of the i-th stage spray section after setting the string grid; The specific heat capacity of water at constant pressure; To determine the water supply quality of the i-th stage spray section after setting the chord grid; To set the water supply temperature for the i-th stage of the spray section after the chord grid; The water temperature after heat exchange in the i-th stage spray section after setting the chord grid; The latent heat of phase change of water; The mass of the liquid after heat exchange in the i-th stage spray section after setting the chord grid; The required insulation layer thickness for the i-th spray section; The thermal conductivity of the insulation material used in the i-th spray section; The area covered by the insulation material in the i-th spray section; To determine the stable operating time of the i-th stage spray section after setting the chord grid; The temperature of the inner wall side of the i-th spray section; The target temperature of the outer wall of the insulation layer in the i-th spray section.

6. The thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device according to claim 5, characterized in that, In step 4, for spray sections where the insulation layer thickness exceeds the allowable thickness of the confined installation space, the allowable thickness of the confined installation space is used as the target insulation layer thickness. The maximum allowable thermal conductivity of the insulation material for that spray section is then calculated, including: when the required insulation layer thickness for the i-th level spray section... Thickness greater than the allowable thickness of the limited installation space At that time, with The target insulation layer thickness for the i-th level spray section The maximum allowable thermal conductivity of the insulation material for the i-th spray section is calculated according to the following formula: ； In the formula: The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section; The target insulation layer thickness for the i-th spray section; To set the airflow mass of the i-th stage spray section after the chord grid; The water-to-air ratio before mass exchange in the i-th stage spray section. ; The water-to-air ratio after mass exchange in the i-th stage spray section. ; To determine the water supply quality of the i-th stage spray section after setting the chord grid; The mass of the liquid after heat exchange in the i-th stage spray section after setting the chord grid; The specific heat capacity of air at constant pressure; The specific heat capacity of water at constant pressure; The latent heat of phase change of water; The area covered by the insulation material in the i-th spray section; To determine the stable operating time of the i-th stage spray section after setting the chord grid; The temperature of the inner wall side of the i-th spray section; The target temperature of the outer wall of the insulation layer in the i-th spray section.

7. The thermal resistance insulation design method for the multi-stage smoke scrubbing and heat dissipation device according to claim 6, characterized in that, In step 5, the step of screening the insulation material for the spray section based on the comparison between the actual thermal conductivity and the maximum allowable thermal conductivity of the candidate insulation materials includes: selecting the actual thermal conductivity of the j-th candidate insulation material for the i-th spray section. The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section Compare; when: When the j-th candidate insulation material is included in the range of usable materials for the i-th spray section; when the following conditions are met: When the j-th candidate insulation material is excluded, then... The actual thermal conductivity of the j-th candidate insulation material in the i-th spray section; The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section.

8. The thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device according to claim 7, characterized in that, In step 5, determining the spray section to be adjusted as the spray section where the insulation layer thickness exceeds the allowable thickness of the limited installation space, the candidate insulation material does not meet the thermal conductivity requirements, or the chord thermal resistance does not meet the preset efficiency enhancement requirements includes: when the i-th level spray section meets any of the following conditions, the i-th level spray section is determined as the spray section to be adjusted: , , ,in, The required insulation layer thickness for the i-th spray section; The allowable thickness for the i-th level spray section within the confined installation space; The actual thermal conductivity of the j-th candidate insulation material in the i-th spray section; The maximum permissible thermal conductivity of the insulation material for the i-th stage spray section; The thermal resistance of the chord grid in the i-th stage spray segment; The lower limit of the thermal resistance of the chord grid in the i-th stage spray section; the lower limit of the thermal resistance of the chord grid is calculated according to... It is confirmed that, among them, The lower limit coefficient of the chord thermal resistance is taken as 0.05 to 0.15; The thermal resistance of the i-th stage spray section when no chord grid is set.

9. The thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device according to claim 8, characterized in that, In step 6, the processing order for the spray sections to be adjusted is determined according to the following order: heat loss from the wall surface from largest to smallest, degree of exceeding the insulation layer thickness limit from largest to smallest, and thermal conductivity margin of the insulation material from smallest to largest. This includes: first determining the processing order for multiple spray sections to be adjusted, and then judging the reasons for adjustment for each section according to the processing order; for the first... The spray section to be adjusted is used to read the heat loss from the wall surface of that spray section. Required insulation layer thickness Limited installation space allows for thickness The maximum permissible thermal conductivity of insulation materials The actual thermal conductivity of the insulation material to be used Chord grid thermal resistance According to the required insulation layer thickness With limited installation space, allowable thickness Determined that the thickness exceeds the limit : ； According to the maximum permissible thermal conductivity of the insulation material Compared with the actual thermal conductivity of the insulation material to be used Determine the thermal conductivity margin of the material : For any two spray sections to be adjusted and First, determine the processing order according to the amount of heat loss from the wall, when the following conditions are met: At that time, the first The first spray section precedes the second. First-stage spray section treatment; when the following conditions are met: In such cases, the processing order should be determined according to the extent of the thickness exceeding the limit; When the following conditions are met: At that time, the first The first spray section precedes the second. First-stage spray section treatment; when the following conditions are met: When the material's thermal conductivity margin is satisfied, the processing order should be determined accordingly; when the following conditions are met: At that time, the first The first spray section precedes the second. First-stage spray treatment; after determining the treatment sequence, proceed with the second stage. Determine the reason for the need for adjustment in the first-stage spray section; when the first... The spray section to be adjusted meets the following requirements: Or it satisfies: If the insulation material of the spray section is still insufficient, first replace it; if the insulation material replacement still meets the requirements... or still satisfied Then, within the limited installation space, the allowable thickness The insulation layer of the high-temperature outer wall area of ​​the spray section is locally adjusted; when the first The spray section to be adjusted meets the following requirements: Alternatively, after replacing the insulation material and adjusting the local insulation layer, the measured temperature of the outer wall of the insulation layer under stable operating conditions can be obtained. Still satisfied: At that time, for the first The arrangement of the chord grid in the primary spray section was adjusted; In the formula: For the first Heat loss occurs on the walls of the spray section; For the first Heat loss occurs on the walls of the spray section; For the first The thickness of the spray section exceeds the limit; For the first The thickness of the spray section exceeds the limit; For the first Thermal conductivity margin of the spray section material; For the first Thermal conductivity margin of the spray section material; For the first The required insulation layer thickness for the primary spray section; For the first The allowable thickness of the spray section within the limited installation space; For the first The maximum permissible thermal conductivity of the insulation material for the spray section; For the first The actual thermal conductivity of the insulation material to be used in the first-stage spray section; For the first Thermal resistance of the chord grid in the spray section; For the first Lower limit of thermal resistance of the chord grid in the spray section; For the first Measured temperature of the outer wall of the insulation layer in the spray section; For the first Target temperature of the outer wall of the insulation layer of the spray section.

10. The thermal resistance insulation design method for the multi-stage smoke washing and heat dissipation device according to claim 9, characterized in that, In step 6, the first The arrangement of the chord grid in the first-stage spray section is adjusted, including: when the first... The spray section meets the requirements And the first When the outlet temperature of the first-stage spray section is higher than the set outlet temperature, determine whether the spray section has an installation length along the airflow direction sufficient to increase the number of chord rows. If there is installation length, add a row of chords downstream of the original chords, with the new chords arranged within the spray droplet coverage area, and the flow interval between the new chords and the original chords not less than 5 times the chord bar diameter. If the airflow quality is lower than the design airflow quality after increasing the number of chord rows, remove the new chords and reduce the chord bar spacing of the existing chords. When reducing the chord bar spacing, the first... Projected occlusion rate of the multi-stage spray grating satisfy: And satisfy: ,in: , , , , After the chord arrangement is adjusted, the first... The spray section underwent a new operational test with the chord grid reconfigured. Inlet air temperature, outlet air temperature, supply water temperature, post-heat exchange water temperature, supply water quality, post-heat exchange liquid quality, airflow quality, and stable operating time were re-collected. The thermal resistance of the spray section after the chord grid reconfiguration was also recalculated. Wire grid thermal resistance Heat loss from the wall Required insulation layer thickness The maximum permissible thermal conductivity of insulation materials When the first After recalculation and retesting, the first-stage spray section simultaneously meets the following requirements: , , , At that time, the first... Treatment of the primary spray section; In the formula: For the first Projected occlusion rate of the primary spray section chord grid; For the first The preset shading limit for the spray section; The projected blocking area of ​​the chord grid bars on a cross section perpendicular to the airflow direction; For the first Cross-sectional area of ​​the primary spray section; The residual pressure of the induced draft fan can be used for adjusting the chord spacing; The static pressure that the induced draft fan can provide under the design airflow mass; This refers to the basic resistance loss of the flue gas washing and heat dissipation device under the design airflow mass before the adjustment of the chord spacing. To reserve a safe pressure differential; For the first Airflow velocity in the first-stage spray section; For the first Airflow quality in the spray section; For the first Gas density in the first spray section; Add drag loss to the chord grid; This is the chord drag coefficient; This is the correction factor for the shape of the grid bars; This is the residual pressure distribution coefficient; To set the string grid after the first Thermal resistance of the spray section; For the first Thermal resistance of the chord grid in the spray section; For the first Heat loss occurs on the walls of the spray section; For the first The required insulation layer thickness for the primary spray section; For the first The allowable thickness of the spray section within the limited installation space; For the first The maximum permissible thermal conductivity of the insulation material for the spray section; For the first The actual thermal conductivity of the insulation material to be used in the first-stage spray section; For the first Lower limit of thermal resistance of the chord grid in the spray section; For the first Measured temperature of the outer wall of the insulation layer in the spray section; For the first Target temperature of the outer wall of the insulation layer of the spray section.

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