Heating energy-saving system and method for deeply utilizing waste heat of boiler plant

Abstract

Provided are a heating energy-saving system and method for deeply utilizing waste heat of a boiler plant, relating to the technical field of heating energy saving. In the heating energy-saving system, a forced draft fan is arranged at an upper part of the boiler plant, an operation level relay induced draft fan is arranged on the operation level, and an air preheater is installed in a bottom level of the boiler plant. The air preheater communicates with an air outlet of a boiler forced draft fan through a first air supply duct, and an air inlet of the boiler forced draft fan communicates with an air inlet device through a second air supply duct. The air inlet device is provided with an outdoor air inlet control valve, and an indoor air inlet control valve.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of heating energy saving, and relates to a heating energy-saving system and method for deeply utilizing waste heat of a boiler plant, thus achieving sufficient utilization of own waste heat of the boiler plant with a heat source.BACKGROUND

[0002] The boiler plant of power plant in cold area is a super-tall space building with a heat source, the negative pressure at the bottom level of the boiler plant is large in winter, making it difficult to guarantee the heating effect. The boiler plant of the thermal power plant is a typical super-tall building with a large heat source, the cold air at the bottom level of the building penetrates greatly in winter. Especially in cold and severe cold areas, the heating of the boiler plant in winter is large in energy consumption and poor in effect, and the instruments at the bottom level are often frozen out. Due to the influence of stack effect, the boiler plant mainly has the following problems at the site:

[0003] first, due to the huge negative pressure at the bottom level of the boiler plant, outdoor cold air is easy to intrude into the boiler plant through gaps in doors, windows, and wallboards, which makes the equipment and piping near the cold air penetration point easy to freezeout, and the safe and stable operation of the unit is affected. Second, at the same time, the temperature at the upper part of the boiler plant is too high, and the temperature of the furnace top is often as high as 50° C. or above in winter. The problem of high temperature at the upper part of the boiler plant not only seriously affects the normal operation of electrical and thermal components to further affect the safe operation of the unit, but also=causes difficulties for the inspection and maintenance of production personnel.

[0004] In view of the above situation, two patent technologies for invention have been produced, i.e., Heating System and Method for Transferring Heat from Upper part to Lower part of Large Space Building in Winter (patent number CN1743740A) and Heating System and Method for Controlling Negative Pressure at Bottom level of Super-large Space Building (patent number CN103743054A). According to Heating System and Method for Transferring Heat from Upper part to Lower part of Large Space Building in Winter, air exchange equipment and a heat source are installed at the top of the building, and the cold air sent into a space by the air exchange equipment is mixed with the air in a high temperature area at the upper part indoor, which makes an indoor pressure greater than an outdoor pressure, such that a slightly positive pressure environment is formed to prevent the cold air from entering and enhance the heating effect. According to Heating System and Method for Controlling Negative Pressure at Bottom level of Super-large Space Building, a fan is installed on an upper level of a boiler plant to suck outdoor cold air to destroy the stack effect of the heat in the boiler plant, and ventilation equipment is installed at a place of the building which is above the neutral surface and below the top. After the cold air enters the boiler plant, the air quality and indoor pressure at the upper part both increases, which makes a negative pressure value at the bottom level of the super-large space boiler plant smaller, and achieves good heating effect. Moreover, the indoor waste heat is also utilized. After the implementation of the two patent technologies for invention, the heating condition at the bottom level of the boiler plant of the power plant in the cold area has been well improved, and a great deal of heating heat energy is saved.

[0005] However, the above two patents still have some technical defects, and there are still some problems that are still unsatisfactory and need to be solved as follows:

[0006] 1. The heat dissipation of the equipment in the boiler plant is far greater than a heating thermal load required by the boiler plant, the waste heat in the boiler plant is only partially utilized even in the coldest period of the heating season, and there is still a lot of waste heat that is not utilized. In the transition season, there is more waste heat in the boiler plant that is not used. In the transitional season, the outdoor air temperature is high, after the stack effect of the boiler plant is destroyed by sucking outdoor cold air through a roof forced draft fan and a sidewall forced draft fan, the temperature of the outdoor cold air is higher than the outdoor temperature in winter, in this case, the overall temperature in the boiler plant is still high. An operation level in the boiler plant is an entire platform, the heat at the upper level of the boiler plant is transferred to the bottom level through the gas in the operation level, the heat transfer is slow, and the heat will be accumulated at the operation level, leading to a higher temperature at the operation level.

[0007] 2. In the transitional season, the temperature requirement of the bottom level of the boiler plant can be ensured by only a small amount of outdoor air supply. If more air is supplied to reduce the temperature at the furnace top, the temperature of the operating level will be too high, and thus it is not worthwhile to supply so much air.

[0008] 3. At the same time as the situation that a large amount of waste heat on the top of the boiler plant is idle and cannot be used, the specialized forced draft fan of the boiler at the bottom level of the boiler plant has been sucking outdoor air, and the outdoor air below zero can be sent into a combustion system of the boiler after being heated to above 20° C. Otherwise, the cold air will lead to the corrosion of the air duct system. All boiler air supply systems in the power plants are equipped with air preheaters, and heating the inlet air of the air preheater to 20° C. will consume a lot of heat energy.SUMMARY

[0009] As mentioned above, the existing patent technology only uses a small part of waste heat in the boiler plant in the coldest season, and there is more unused waste heat in the transitional season (spring and autumn). An objective of the present disclosure is to make full use of the waste heat in most of the boiler plants that have not been utilized on the basis of saving the conventional heating heat and ensuring the heating temperature requirements at the bottom level of the boiler plant. To achieve the objective above, the present disclosure employs the following technical solution.

[0010] In a heating energy-saving system for deeply utilizing waste heat of a boiler plant, multiple forced draft fans are arranged at an upper part of the boiler plant, an operation level relay induced draft fan is installed on the operation level, and communicates with the bottom level of the boiler plant below the operation level, and an air preheater is installed in the bottom level of the boiler plant. The air preheater communicates with an air outlet of a boiler forced draft fan through a first air supply duct, and an air inlet of the boiler forced draft fan communicates with an air inlet device through a second air supply duct. The air inlet device penetrates through a sidewall of the boiler plant. An outdoor air inlet control valve is installed at an opening of one end of the air inlet device located outside the boiler plant, and an indoor air inlet control valve is located at an opening of a sidewall of the air inlet device located in the boiler plant.

[0011] Preferably, the forced draft fan is arranged at the roof of the boiler plant, or arranged on a sidewall of the boiler plant.

[0012] Preferably, the forced draft fan arranged on the sidewall of the boiler plant is a sidewall air supply device, which includes sidewall air supply piping with a square cross section. The sidewall air supply piping communicates with the inside of the boiler plant, a sidewall forced draft fan is installed in the sidewall air supply pipeline, and the sidewall air supply piping is provided with sidewall air supply outlets at a port of one end inside the boiler plant, an upper sidewall, a left sidewall, and a right sidewall.

[0013] Preferably, indoor temperature sensors and pressure difference sensors are arranged in the boiler plant, and multiple outdoor temperature sensors are arranged outside the boiler plant.

[0014] Preferably, a fan electric control cabinet is arranged in the boiler plant, and the fan electric control cabinet is electrically connected to the forced draft fan.

[0015] Preferably, an intelligent controller is arranged beside the fan electric control cabinet, and the intelligent controller is electrically connected to the fan electric control cabinet.

[0016] Preferably, the boiler forced draft fan includes a boiler forced draft fan and a boiler primary fan with inlet air needing to enter the air preheater.

[0017] The present disclosure provides a heating energy-saving method for deeply utilizing the waste heat of a boiler plant, which uses and the heating energy-saving system for deeply utilizing the waste heat of the boiler plant, and includes the following steps: when an outdoor temperature of the boiler plant is lower than a set threshold, starting a forced draft fan to send outdoor air into the boiler plant from an upper part of the boiler plant, where the outdoor air is mixed with indoor air at the upper part of the boiler plant for temperature rise; after the outdoor air absorbs the indoor waste heat of the boiler plant, an internal pressure of the boiler plant is increased, and sent to the bottom level of the boiler plant through the operation level relay induced draft fan, making a negative pressure value of the bottom level of the boiler plant reduced, and a temperature of the boiler plant higher than a set minimum heating temperature; meanwhile, keeping an indoor air inlet control valve open, and reducing opening degree of an outdoor air inlet control valve open, thus maximizing air volume sucked from the inside of the boiler plant by the boiler forced draft fan; sucking, by the boiler forced draft fan, mixed hot air into a boiler air supply system to reduce suction volume of outdoor cold air of the boiler forced draft fan, thus reducing steam consumption of an air preheater, and achieving the purpose of energy saving.

[0018] In the existing related patent technology, after sending air indoors, only the indoor pressure is increased, the pressure is transferred downward to reduce the negative pressure at the bottom level, but the air does not flow downward. In addition to reducing the negative pressure at the bottom level, the hot air also needs to be transferred from the upper part of the boiler plant to the lower part, and can be fully utilized to save the energy consumption of the air preheater.

[0019] Preferably, a sealing condition of the boiler plant is detected by indoor and outer pressure difference sensors.

[0020] Preferably, indoor and outdoor temperatures are collected by temperature sensors, and an intelligent controller is used to control the forced draft fan, an indoor air inlet control valve, and an outdoor air inlet control valve according to the change of indoor and outdoor temperatures.

[0021] The present disclosure has the beneficial effects that:

[0022] different from the existing patent technology, in addition to controlling the negative pressure at the bottom level of the boiler plant and ensuring the temperature at the bottom level of the boiler plant, the residual waste heat in the boiler plant can be sent into a forced draft fan system of the boiler with more air volume, so as to make full use of the waste heat of the boiler plant and reduce the steam consumption of the air preheater.

[0023] The outdoor air is sent indoors by the forced draft fan at the upper part of the boiler plant to absorb the heat dissipation of the boiler and thermal piping and other equipment to form hot air. Then the hot air is sent to the bottom level of the boiler plant by the operation level relay induced draft fan, and sucked in the air supply system of the boiler by the indoor air inlet control valve at the boiler forced draft fan. Because the hot air is sucked, the steam consumption of the air preheater is reduced.

[0024] The air suction volume of the boiler forced draft fan is controlled by the temperatures at the bottom level and upper part of the boiler plant, that is, reducing the steam consumption of the air preheater is achieved on the premise that the heating system of the boiler plant does not operate and the heating effect at the bottom level of the boiler plant is guaranteed, thus saving the heating energy consumption.

[0025] The air supplied by the sidewall air supply device is mixed with indoor air in an annular space between a boiler body and an external wall of the boiler plant. Because there are four directions for air outlet, the air volume and wind speed in each direction are not too large, and the air supply range is controlled in the annular space between the boiler body and the external wall of the boiler plant. There is no such an air supply mode in the previous patent.

[0026] As the operating level platform prevents the air from running to the bottom level, a relay induced draft fan is arranged on the operation level platform to send the air that has entered from the upper part of the boiler plant and absorbed heat to the bottom level of the boiler plant.

[0027] In the past patent, the air supply system was started with the temperature at the bottom level of the boiler plant as the control point, while the air supply system provided by the present invention is started with the outdoor temperature as the control point. In the present disclosure, the air supply system should still be started even if the temperature at the bottom level of the boiler plant meets the requirements, so as to send the waste heat that is not utilized into the boiler forced draft fan.

[0028] In addition to ensuring the temperature at the bottom level of the boiler plant, the present disclosure also needs to ensure that the residual waste heat in the boiler plant is sent to the boiler forced draft fan with appropriate air volume. As the outdoor temperature changes in real time, the air supply volume needs to be adjusted at any time, which is completed by the intelligent controller. The intelligent controller may also be used to detect a sealing condition of the boiler plant, thus reminding the personnel on duty to check or maintain.

[0029] A suction port is formed in an indoor air duct of the boiler forced draft fan to suck air from the boiler plant, and no previous boiler blower system sucks air from the boiler plant.

[0030] The present disclosure is simple in structure and principle, less in equipment investment, and easy to implement.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a schematic diagram of a structure according to Embodiment 1 of the present disclosure;

[0032] FIG. 2 is an enlarged view of position A in FIG. 1;

[0033] FIG. 3 is a schematic structural diagram of a bottom level of a boiler plant according to Embodiment 1 of the present disclosure;

[0034] FIG. 4 is a schematic diagram of a structure according to Embodiment 2 of the present disclosure;

[0035] FIG. 5 is a schematic diagram of a structure according to Embodiment 3 of the present disclosure;

[0036] FIG. 6 is a first top view of a sidewall forced draft fan arranged on all sides of a boiler plant according to Embodiment 4 of the present disclosure;

[0037] FIG. 7 is a second top view of a sidewall forced draft fan arranged on all sides of a boiler plant according to Embodiment 4 of the present disclosure;

[0038] FIG. 8 is a third top view of a sidewall forced draft fan arranged on all sides of a boiler plant according to Embodiment 4 of the present disclosure.In the drawings: 1—sidewall air supply device; 2—roof forced draft fan; 3—operation level relay induced draft fan; 4—outdoor air inlet control valve; 5—indoor air inlet control valve; 6—pressure difference sensor; 7—indoor temperature sensor; 8—outdoor temperature sensor; 9—sidewall air supply outlet; 10—boiler plant; 11—operation level; 12—air preheater; 13—boiler; 14—-bottom level of boiler plant; 15—sidewall air supply piing; 16—first air supply duct; 17—boiler forced draft fan.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The present disclosure is further described below with reference to accompanying drawings and embodiments.Embodiment 1

[0041] As shown in FIG. 1, FIG. 2 and FIG. 3, a boiler 13 is fixedly installed at a middle position in a boiler plant 10. A heating energy-saving system for deeply utilizing waste heat of a boiler plant includes an operation level relay induced draft fan 3, which is fixedly installed on an operating level 11 and communicates with a bottom level 14 of the boiler plant below the operating level 11, and an air preheater 12 is fixedly installed in the bottom level 14 of the boiler plant. The air preheater 12 communicates with an air outlet of a boiler forced draft fan 17 through a first air supply duct 16, and an air inlet of the boiler forced draft fan 17 communicates with an air inlet device through a second air supply duct. The air inlet device penetrates through a sidewall of the boiler plant. An outdoor air inlet control valve 4 is installed at an opening of one end of the air inlet device located outside the boiler plant 10, and an indoor air inlet control valve 5 is located at an opening of a sidewall of the air inlet device located in the boiler plant 10. An indoor temperature sensor 7 is fixedly installed in the boiler plant 10 below the air inlet device, a pressure difference sensor 6 is fixedly installed in the sidewall of the boiler plant below the air inlet device, and an outdoor temperature sensor 8 is fixedly installed outside the boiler plant 10 below the air inlet device.

[0042] Multiple roof forced draft fans 2 are fixedly installed at the top of the boiler plant 10, and the roof forced draft fan 2 communicates with the inside of the boiler plant 10. Multiple sidewall air supply devices 1 are fixedly installed at an upper part of the sidewall of the boiler plant, and the sidewall air supply device 1 includes a sidewall air supply piping 15, the sidewall air supply piping 15 communicates with the inside of the boiler plant 10, a sidewall forced draft fan is fixedly installed in the sidewall air supply piping 15, a sidewall air supply outlet 9 is formed in a sidewall of one end, located in the boiler plant 10, of the sidewall air supply piping 15. Four sidewall air supply outlets 9 are provided, which are formed in an upper sidewall, a left sidewall, a right sidewall 15 and a front-end wall of the sidewall air supply piping 15, respectively. Multiple pressure difference sensors 6 are fixedly installed at a position, close to the sidewall air supply piping 15, of the upper part of the sidewall of the boiler plant, and multiple indoor temperature sensors 7 are fixedly installed close to the sidewall air supply piping 15 in the boiler plant 10.

[0043] Further, a fan electric control cabinet is arranged in the boiler plant 10, which is electrically connected to the roof forced draft fan 2 and the sidewall forced draft fan, and used to control the air volume of the roof forced draft fan 2 and the sidewall forced draft fan. Further, an intelligent controller is arranged beside the fan electric control cabinet, and the intelligent controller may be integrated with the fan electric control cabinet.

[0044] When the unit capacity of a power plant in a heating region is too large, the air volume for sucking the waste heat from the boiler plant 10 into the specialized boiler supply device 17 is large, and the number of fans required is more. In this case, in Embodiment 1, the fans can be simultaneously arranged on the roof and the sidewall, two or more layers of the fans can be arranged on the sidewall. The fans on the sidewall can be arranged on both sides of the boiler plant 10, or on all sides of the boiler plant 10.

[0045] The operation level relay induced draft fan 3 needs to be arranged more.

[0046] A heating energy-saving method for deeply utilizing the waste heat of a boiler plant is provided, which uses and the heating energy-saving system for deeply utilizing the waste heat of a boiler plant, and includes the following steps:

[0047] When an outdoor temperature is lower than a set threshold, it is considered that a fan system of the heating energy-saving system can be started to supply air indoors, the boiler forced draft fan 17 can suck air from the boiler plant to improve the air supply temperature, and ensure the heating effect required by the bottom level 14 of the boiler plant at the same time.

[0048] The sidewall air supply device 1 at the upper part of the boiler plant 10 and the roof forced draft fan 2 can supply air indoors, and meanwhile, the operation level relay induced draft fan 3 supplies air to the bottom level 14 of the boiler plant. When a temperature at the bottom level 14 of the boiler plant is higher that a set lowest heating temperature, the indoor air inlet control valve 5 at the boiler forced draft fan 17 is kept open. When the indoor air inlet control valve 5 is opened, the opening degree of an outdoor air inlet control valve 4 open at the boiler forced draft fan 17 is reduced to decrease the air input from the outside, thus maximizing air volume sucked from the inside of the boiler plant by the boiler forced draft fan 17, thus reducing steam consumption of the air preheater 12 and achieving the purpose of energy saving.

[0049] There are two reference values for controlling the air suction volume from the boiler plant by the boiler forced draft fan 17, one is the temperature of the bottom level 14 of the boiler plant, and the other is the temperature of the upper part of the boiler plant 10. When any temperature is lower than the corresponding set value, the opening degree of the indoor air inlet control valve 5 at the boiler forced draft fan 17 needs to be reduced, while the opening degree of the outdoor air inlet control valve 4 open at the boiler forced draft fan 17 needs to be increased to ensure the heating of the bottom level 14 of the boiler plant. The premise of the boiler forced draft fan 17 to suck air from the boiler plant to improve the air supply temperature is to ensure the temperature of the bottom level 14 of the boiler plant. When the temperature of the bottom level 14 of the boiler plant decreases, the opening degree of the indoor air inlet control valve 5 needs to be reduced. Even if the reduction of the opening degree leads to an increase in the steam consumption of the air preheater 12, the indoor air suction volume of the boiler blower 17 needs to be reduced.

[0050] The indoor and outdoor pressure difference sensors can detect a sealing condition of the boiler plant 10. If a pressure difference of any of the upper part and lower part of the boiler plant 10 decreases significantly, it is indicated that the sealing at this part has a problem, for example, the door and window at the bottom level are opened or damaged, or the entrance, a hanging hole and a ventilator at the furnace top are opened or damaged. When the pressure difference value changes greatly, the intelligent controller can remind the personnel on duty to inspect or repair.

[0051] In the previous super-large space building, an indoor heat source shown in the patent for controlling the negative pressure at the bottom level is in the lower part of the space, while the heat source in the boiler plant of the power plant is the boiler body, and the height of the boiler body is similar to that of the boiler plant. Except for the sidewall forced draft fan at the top, the sidewall forced draft fan below the furnace top cannot blow the air to an opposite outer wall or to the middle of the boiler plant. The air supplied by these fans can only be mixed with the indoor air in an annular space between the boiler body and the external wall of the boiler plant, and the air supply outlets of these fans may have four directions, i.e., front, left and right and above. Because there are four directions of air outlet, the air volume and wind speed in each direction cannot be too large, and the air supply range is controlled in the annular space between the boiler body and the external wall of the boiler plant, and the hot air cannot be effectively blown to the operation level 11. As the platform of the operation level 11 prevents the hot air from running to the bottom level, the operation level relay induced draft fan 3 is arranged on the platform of the operation level 11 to transfer the air that has entered the upper part of the boiler plant 10 and absorbed heat to the bottom level 14 of the boiler plant.

[0052] The boiler forced draft fan 17 in Embodiment 1 includes a boiler forced draft fan and a boiler primary fan with inlet air needing to enter the air preheater 12.Embodiment 2

[0053] As shown in FIG. 4, when the unit capacity of a power plant in the heating region is small, the air volume for sucking the waste heat from the boiler plant 10 into the boiler forced draft fan 17 is small, and the number of fans required is less. In this case, in Embodiment 2, the forced draft fan can be arranged only on the sidewall, and two or more layers of fans can be arranged on the sidewall, and the forced draft fans on the sidewall can be arranged on both sides of the boiler plant 10, or on all sides of the boiler plant 10.

[0054] The operation level relay induced draft fan 3 can be determined according to the air volume of the upper forced draft fan.Embodiment 3

[0055] As shown in FIG. 5, when the unit capacity of a power plant in the heating region is small, the air volume for sucking the waste heat from the boiler plant 10 into the boiler forced draft fan 17 is small, and the number of fans required is less. In this case, the fans can be simultaneously arranged on the roof and the sidewall, one layer of the fans can be arranged on the sidewall. The forced draft fans on the sidewall can be arranged on both sides of the boiler plant 10, or on all sides of the boiler plant 10.

[0056] The operation level relay induced draft fan 3 can be determined according to the air volume of the upper forced draft fan.Embodiment 4

[0057] Embodiment 4 is a further limitation of an arrangement structure of the sidewall air supply devices in Embodiment 1, 2, or 3. As shown in FIG. 6, the number of the sidewall air forced draft fans 1 required is less, and the sidewall air supply devices 1 are fixedly installed on two opposite sidewalls of the boiler plant 10. As shown in FIG. 7, the number of the sidewall air supply devices 1 required is more, and the sidewall air supply devices 1 are fixedly installed on four sidewalls of all sides of the boiler plant 10, and the number of the arranged sidewall air supply devices is more. As shown in FIG. 8, the number of the sidewall air supply devices 1 required is less, and the sidewall air supply devices 1 are fixedly installed on four sidewalls of all sides of the boiler plant 10, and the number of the arranged sidewall air supply devices is less.

[0058] Although the specific embodiments of the present disclosure are described above with reference to the accompanying drawings, the descriptions of the specific embodiments are not intended to limit the scope of protection of the present disclosure. Those skilled in the art should appreciate that on the basis of the technical solution of the present disclosure, various modifications or variations made by those skilled in the art without creative labor are still within the scope of protection of the present disclosure.

Claims

1. A heating energy-saving system for deeply utilizing waste heat of a boiler plant, wherein a plurality of forced draft fans are arranged at an upper part of the boiler plant, an operation level relay induced draft fan is installed on the operation level, and communicates with a bottom level of the boiler plant below the operation level, and an air preheater is installed in the bottom level of the boiler plant; the air preheater communicates with an air outlet of a boiler forced draft fan through a first air supply duct, and an air inlet of the boiler forced draft fan communicates with an air inlet device through a second air supply duct; the air inlet device penetrates through a sidewall of the boiler plant; and an outdoor air inlet control valve is installed at an opening of one end of the air inlet device located outside the boiler plant, and an indoor air inlet control valve is located at an opening of a sidewall of the air inlet device located in the boiler plant.

2. The heating energy-saving system for deeply utilizing waste heat of a boiler plant according to claim 1, wherein the forced draft fan is arranged at the roof of the boiler plant, or arranged on a sidewall of the boiler plant.

3. The heating energy-saving system for deeply utilizing waste heat of a boiler plant according to claim 2, wherein the forced draft fan arranged on the sidewall of the boiler plant is a sidewall air supply device, which comprises sidewall air supply piping with a square cross section; the sidewall air supply piping communicates with the inside of the boiler plant, a sidewall forced draft fan is installed in the sidewall air supply pipeline, and the sidewall air supply piping is provided with sidewall air supply outlets at a port of one end inside the boiler plant, an upper sidewall, a left sidewall, and a right sidewall.

4. The heating energy-saving system for deeply utilizing waste heat of a boiler plant according to claim 1, wherein a plurality of indoor temperature sensors and pressure difference sensors are arranged in the boiler plant, and a plurality of outdoor temperature sensors are arranged outside the boiler plant.

5. The heating energy-saving system for deeply utilizing waste heat of a boiler plant according to claim 1, wherein a fan electric control cabinet is arranged in the boiler plant, and the fan electric control cabinet is electrically connected to the forced draft fan.

6. The heating energy-saving system for deeply utilizing waste heat of a boiler plant according to claim 5, wherein an intelligent controller is arranged beside the fan electric control cabinet, and the intelligent controller is electrically connected to the fan electric control cabinet.

7. The heating energy-saving system for deeply utilizing waste heat of a boiler plant according to claim 1, wherein the boiler forced draft fan comprises a boiler forced draft fan and a boiler primary fan for supplying air into the air preheater.

8. A heating energy-saving method for deeply utilizing the waste heat of a boiler plant, wherein the heating energy-saving system for deeply utilizing the waste heat of a boiler plant according to claim 1 is utilized, comprising the following steps:when an outdoor temperature of the boiler plant is lower than a set threshold, starting a forced draft fan to send outdoor air into the boiler plant from an upper part of the boiler plant, wherein the outdoor air is mixed with indoor air at the upper part of the boiler plant for temperature rise; after the outdoor air absorbs the indoor waste heat of the boiler plant, an internal pressure of the boiler plant is increased, and sent to a bottom level of the boiler plant through the operation level relay induced draft fan, making a negative pressure value of the bottom level of the boiler plant reduced, and a temperature of the boiler plant higher than a set minimum heating temperature; meanwhile, keeping an indoor air inlet control valve open, and reducing opening degree of an outdoor air inlet control valve open, thus maximizing air volume sucked from the inside of the boiler plant by the boiler forced draft fan; sucking, by the boiler forced draft fan, mixed hot air into a boiler air supply system to reduce suction volume of outdoor cold air of the boiler forced draft fan, thus reducing steam consumption of an air preheater, and achieving the purpose of energy saving.

9. The heating energy-saving method for deeply utilizing waste heat of a boiler plant according to claim 8, wherein a sealing condition of the boiler plant is detected by indoor and outer pressure difference sensors.

10. The heating energy-saving method for deeply utilizing waste heat of a boiler plant according to claim 8, wherein indoor and outdoor temperatures are collected by temperature sensors, and an intelligent controller is used to control the forced draft fan, an indoor air inlet control valve, and outdoor air inlet control valve according to the change of indoor and outdoor temperatures.

Images