Low-grade steam efficient utilization method and system

Abstract

The present application relates to a kind of low-grade steam efficient utilization method and system;The method includes sequencing steam turbine, motor and diesel engine driven induced draft fan;Judge whether there is steam and external power supply;When there is steam and external power supply, through steam turbine driven induced draft fan or through steam turbine and motor jointly driven induced draft fan;When there is steam and no external power supply, through steam turbine driven induced draft fan or through steam turbine and diesel engine jointly driven induced draft fan;When there is no steam, through motor and / or diesel engine driven induced draft fan.The present application can utilize the low-grade, discontinuous steam generated in the field of hazardous waste treatment and other energy environmental protection fields, improve energy utilization efficiency, reduce surrounding thermal pollution, be conducive to the construction of low-carbon environment, reduce pollution emissions, configure diesel engine can improve the safety factor of system, ensure the safe and reliable operation of system;It can also convert the surplus kinetic energy into electric energy for other electric equipment, save electric energy.

Description

Technical Field

[0001] This invention relates to the field of energy and environmental protection technology, and in particular to a method and system for the efficient utilization of low-grade steam. Background Technology

[0002] In the fields of energy conservation, environmental protection, power, metallurgy, and chemical engineering, discontinuous and small amounts of low-grade steam are generated in relevant process stages due to the requirements of their production processes, equipment characteristics, and management levels. Under normal circumstances, this discontinuous and low-grade steam is either directly discharged or cooled and condensed using circulating water. This method results in significant energy loss and thermal pollution, hindering the construction of a low-carbon and environmentally friendly society. In the incineration of hazardous waste, continuous operation is not possible due to the low calorific value of hazardous waste, small processing scale, and limitations in hazardous waste production. A certain amount of discontinuous steam is generated during hazardous waste treatment. If all of this steam is collected for waste heat power generation, the unit size would be too small to meet grid connection requirements. Directly discharging this steam or cooling it with circulating water would result in energy loss, which is detrimental to environmental protection and low-carbon development. Furthermore, during unit startup or in case of an accident, the lack of steam and / or external power means the induced draft fan has no driving equipment, causing the furnace to be unable to maintain negative pressure, posing a risk of explosion.

[0003] Existing dual-drive steam-electric induced draft fans have been widely used. Using dual-drive steam-electric induced draft fans has the convenience of starting electric induced draft fans and the high-efficiency speed regulation of steam-driven induced draft fans. However, when there is insufficient steam or no power supply, the induced draft fan cannot be used normally, which will cause the furnace to be unable to maintain negative pressure, posing a huge safety hazard. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for the efficient utilization of low-grade steam, comprising the following steps:

[0005] (1) Sort the steam turbine, electric motor and diesel engine driven induced draft fan in order;

[0006] (2) Determine whether there is steam driving the turbine and whether there is an external power source driving the motor.

[0007] (3) When there is steam and an external power source, the induced draft fan is driven by the steam turbine or driven by the steam turbine and the electric motor together.

[0008] When there is steam and no external power source, the induced draft fan is driven by a steam turbine or by a combination of a steam turbine and a diesel engine.

[0009] When there is no steam, the induced draft fan is driven to operate by the electric motor and / or the diesel engine.

[0010] Further, the step 2 further includes acquiring in real time the torque M1 of the steam turbine, the torque M2 of the electric motor, and the torque M3 of the diesel engine, wherein the set torque of the induced draft fan is denoted as M0,

[0011] Further, in the step 3, when steam is available and external power supply is available, the steam turbine is started; if M1≥M0, the electric motor is turned off, and the induced draft fan is driven to operate by the steam turbine; if M1<M0, the electric motor is started, and the induced draft fan is driven to operate jointly by the steam turbine and the electric motor.

[0012] Further, in the step 3, when steam is available and no external power supply is available, the steam turbine is started; if M1≥M0, the diesel engine is turned off, and the induced draft fan is driven to operate by the steam turbine; if M1<M0, the diesel engine is started, and the induced draft fan is driven to operate jointly by the steam turbine and the diesel engine.

[0013] Further, if M1>M0, the steam turbine drives the induced draft fan to operate and supplies power for the electric motor to store electric energy for powering electrical appliances.

[0014] Further, in the step 3, when no steam is available and external power supply is available, the electric motor is started, and the induced draft fan is driven to operate by the electric motor; when no steam is available and no external power supply is available, the diesel engine is started, and the induced draft fan is driven to operate by the diesel engine.

[0015] Further, if M3>M0, the diesel engine drives the induced draft fan to operate and supplies power for the electric motor to store electric energy for powering electrical equipment.

[0016] In another aspect, the present invention further provides a low-grade steam high-efficiency utilization system, comprising a steam turbine, an induced draft fan, an electric motor, a diesel engine and a control unit, wherein the steam turbine is provided with a steam inlet for steam to pass in, the output end of the steam turbine is connected with the electric motor through a first shaft system meshing device, the induced draft fan is connected with the electric motor, the diesel engine is connected with the induced draft fan through a second shaft system meshing device, and the steam turbine, the induced draft fan, the electric motor, the diesel engine, the first shaft system meshing device and the second shaft system meshing device are all electrically connected with the control unit.

[0017] Further, the steam turbine, the electric motor and the diesel engine are respectively connected with torque sensors, and each of the torque sensors is electrically connected with the control unit.

[0018] Further, a gearbox is arranged between the steam turbine and the first shaft system meshing device.

[0019] By adopting the above technical solutions, this invention has the following beneficial effects compared with the prior art: It establishes an integrated, safe, and efficient utilization system for low-grade steam, electricity, and diesel fuel, which can utilize low-grade, discontinuous steam generated in the field of hazardous waste treatment and other energy and environmental protection fields, improving energy utilization efficiency, reducing thermal pollution around the project, contributing to the construction of a low-carbon environment, reducing pollution emissions, and configuring a diesel engine to improve the system's safety factor and ensure safe and reliable operation; it can also convert surplus kinetic energy into electrical energy for use by other electrical equipment, saving electricity. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the low-grade steam high-efficiency utilization system provided by the present invention.

[0021] 1-Steam turbine; 2-Electric motor; 3-Induced draft fan; 4-Diesel engine; 5-Control unit; 6-First shaft engagement device; 7-Second shaft engagement device; 8-First torque sensor; 9-Second torque sensor; 10-Third torque sensor; 11-Fourth torque sensor; 12-Gearbox. Detailed Implementation

[0022] 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. In the accompanying drawings, the dimensions and relative dimensions of certain parts may be enlarged for clarity.

[0023] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connection" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] In the description of this invention, terms such as "upper," "lower," "left," "right," "front," and "rear," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] Furthermore, in the description of this invention, the terms "first" and "second" are used only for descriptive purposes.

[0026] Example 1

[0027] As per the instruction manual Figure 1 As shown, the present invention provides a low-grade steam high-efficiency utilization system, including a steam turbine 1, an induced draft fan 3, an electric motor 2, a diesel engine 4, and a control unit 5. The steam turbine 1 is provided with a steam inlet for steam introduction. The output end of the steam turbine 1 is connected to the electric motor 2 through a first shaft engagement device 6. The induced draft fan 3 is connected to the electric motor 2. The diesel engine 4 is connected to the induced draft fan 3 through a second shaft engagement device 7, realizing a combined drive mode of steam, electric energy, and diesel fuel for the induced draft fan 3. The steam turbine 1, induced draft fan 3, electric motor 2, diesel engine 4, first shaft engagement device 6, and second shaft engagement device 7 are all electrically connected to the control unit 5. In this embodiment, the combined drive of the steam turbine 1, the electric motor 2, and the diesel engine 4 to the induced draft fan 3 is achieved through the first shaft engagement device 6 and the second shaft engagement device 7. The control unit 5 can acquire the operating parameters of the steam turbine 1, the induced draft fan 3, the electric motor 2, and the diesel engine 4, and adjust the first shaft engagement device 6 and the second shaft engagement device 7 to be in an engaged or disengaged state by judging the operating parameters, thereby ensuring the normal operation of the induced draft fan 3.

[0028] Preferably, the motor 2 is a generator motor, which can be used as a motor to convert electrical energy into kinetic energy, and also as a generator to convert kinetic energy into electrical energy, so that excess kinetic energy can be converted into electrical energy for use by other electrical equipment.

[0029] As one implementation method, the electric motor 2 is also connected to electrical equipment, such as lighting equipment in the park, etc. When the kinetic energy of the steam turbine or diesel engine is sufficient to drive it, energy can be saved.

[0030] In the optimized implementation, the steam turbine 1 is connected to a first torque sensor 8 to acquire the torque M1 of the main shaft when the steam turbine is working; the electric motor 2 is connected to a second torque sensor 9 to acquire the torque M2 of the main shaft when the electric motor 2 is rotating; and the diesel engine 4 is connected to a third torque sensor 10 to acquire the torque M3 of the main shaft when the diesel engine 4 is working. The first torque sensor 8, the second torque sensor 9, and the third torque sensor 10 are all connected to the control unit 5. The control unit 5 can receive the torques of the steam turbine 1, the electric motor 2, and the diesel engine 4 in real time, compare them with the set torque of the induced draft fan 3, and adjust the start and stop of the steam turbine 1, the electric motor 2, and the diesel engine 4 to achieve the set torque of the induced draft fan 3 and ensure that the induced draft fan 3 can work normally.

[0031] In an optimized implementation, the induced draft fan 3 is connected to a fourth torque sensor 11, which is used to obtain the working torque M4 of the main shaft when the induced draft fan 3 is working. The induced draft fan 3 is driven by the steam turbine 1, the electric motor 2 and the diesel engine 4, so that the working torque of the induced draft fan 3 is close to or equal to the set torque, ensuring the normal operation of the system.

[0032] In an optimized implementation, a gearbox 12 is provided between the steam turbine 1 and the first shaft meshing device 6, and the gear coefficient of the gearbox 12 can be adjusted as needed.

[0033] Example 2

[0034] This invention also provides a method for efficient utilization of low-grade steam, using the system described in Example 1, comprising the following steps:

[0035] (1) Arrange the steam turbine 1, electric motor 2 and diesel engine 4 driving the induced draft fan 3 in sequence;

[0036] (2) Determine whether there is steam driving the turbine 1 to work and whether there is an external power source driving the motor 2 to work;

[0037] (3) When there is steam and an external power source, the induced draft fan 3 is driven by the steam turbine 1 or the induced draft fan 3 is driven by the steam turbine 1 and the electric motor 2.

[0038] When there is steam and no external power source, the induced draft fan 3 is driven by the steam turbine 1 or by the steam turbine 1 and the diesel engine 4 working together.

[0039] When there is no steam, the induced draft fan 3 is driven by the electric motor 2 and / or the diesel engine 4.

[0040] Specifically, in step 1, the steam turbine 1, the electric motor 2, and the diesel engine 4 drive the induced draft fan 3 in sequence. The steam turbine 1 is driven to do work by low-grade, discontinuous steam. When there is steam, the steam turbine 1 is preferably turned on to drive the induced draft fan 3. When the steam is insufficient to drive the induced draft fan 3 to the set torque, the electric motor 2 is turned on to assist the steam turbine 1. When there is insufficient steam and no external power supply, the diesel engine 4 is turned on. The diesel engine 4 drives the induced draft fan 3 alone or together with the steam turbine 1.

[0041] In an optimized implementation, the control unit 5 acquires the real-time torques of the steam turbine 1, electric motor 2, and induced draft fan 3 through various torque sensors to ensure that the induced draft fan 3 operates under a set torque. Specifically, the torque of the steam turbine 1 is M1, the torque of the electric motor 2 is M2, the torque of the diesel engine 4 is M3, and the operating torque of the induced draft fan 3 is M4. The specific control strategy is as follows:

[0042] 1) When there is steam and an external power supply is available

[0043] The torque data of the corresponding shafting is transmitted to the control unit via each torque sensor, and the control unit analyzes and processes the torque data.

[0044] When steam is available, the steam turbine 1 is started, and steam drives the steam turbine 1 to perform work, which can reduce the power consumption of the electric motor 2. The steam turbine 1 drives the induced draft fan 3, and the working torque M4 of the induced draft fan 3 is monitored in real time, so that the working torque of the induced draft fan approaches or equals the set torque, ensuring normal operation of the system.

[0045] If M1>M0, the control unit 5 outputs instructions to the first shafting engagement device 6 and the second shafting engagement device 7, the first shafting engagement device 6 is in the engaged state, the second shafting engagement device 7 is in the disengaged state, part of the torque generated by the shafting of the steam turbine 1 is supplied to the induced draft fan 3, so that the working torque of the induced draft fan 3 is equal to the set torque to meet the operation requirements of the induced draft fan 3, and the remaining part of the torque is supplied to the electric motor 2. The electric motor 2 functions as a generator, converting the excess torque into electric power to supply power to other electrical equipment. At this time, both the induced draft fan 3 and the electric motor 2 are driven by the steam turbine 1, and the diesel engine 4 is in a deactivated state.

[0046] If M1=M0, the control unit 5 outputs instructions to the first shafting engagement device 6 and the second shafting engagement device 7, the first shafting engagement device 6 is in the engaged state, the second shafting engagement device 7 is in the disengaged state, and all the torque generated by the shafting of the steam turbine 1 is exactly supplied to the induced draft fan 3, so that the working torque of the induced draft fan 3 is equal to the set torque to meet the operation requirements of the induced draft fan 3. At this time, the induced draft fan 3 is driven solely by the steam turbine 1, and the diesel engine 4 and the electric motor 2 are in a deactivated state.

[0047] If M1<M0, the control unit 5 outputs instructions to the first shafting engagement device 6 and the second shafting engagement device 7, the first shafting engagement device 6 is in the engaged state, the second shafting engagement device 7 is in the disengaged state, and all the torque generated by the shafting of the steam turbine 1 is supplied to the induced draft fan 3. At this time, the working torque M4 of the induced draft fan 3 is less than the set torque M0, the electric motor 2 is started, and the power of the electric motor 2 is gradually increased until the working torque M4 of the induced draft fan 3 approaches or equals the set torque M0.

[0048] If the working torque of the induced draft fan 3 is still less than the set torque after the steam turbine 1 and the electric motor 2 are started, the second shafting engagement device 7 can be driven to the engaged state, the diesel engine 4 is started, and the induced draft fan 3 is jointly driven by the steam turbine 1, the electric motor 2 and the diesel engine 4, so that the working torque of the induced draft fan 3 is equal to the set torque to meet the working requirements of the induced draft fan 3.

[0049] 2) When there is steam and no external power supply is available

[0050] The torque data of the corresponding shafting is transmitted to the control unit via each torque sensor, and the control unit analyzes and processes the torque data.

[0051] When steam is available, the steam turbine 1 is started, and the steam drives the steam turbine 1 to perform work, so as to drive the induced draft fan 3 to operate.

[0052] If M1≥M0, the control method is the same as the control method when steam is available and external power supply is available, which will not be repeated here, and the induced draft fan 3 is similarly driven by the steam turbine 1.

[0053] If M1<M0, the control unit 5 outputs instructions to the first shafting meshing device 6 and the second shafting meshing device 7, the first shafting meshing device 6 is in the meshed state, the second shafting meshing device 7 is in the meshed state, and all the torque generated by the shafting of the steam turbine 1 is supplied to the induced draft fan 3. At this time, the operating torque M4 of the induced draft fan 3 is less than the set torque M0, the diesel engine 4 is started, and the power of the diesel engine 4 is gradually increased until the operating torque M4 of the induced draft fan 3 approaches or equals the set torque M0.

[0054] 3) When there is no steam but external power supply is available

[0055] When the system detects that there is no steam but external power supply is available, the steam turbine 1 cannot perform work. The control unit 5 outputs instructions to the first shafting meshing device 6 and the second shafting meshing device 7, both the first shafting meshing device 6 and the second shafting meshing device 7 are in the disengaged state, the motor 2 is started, the induced draft fan 3 is driven by the motor 2, the power of the motor 2 is gradually increased, and the operating torque of the induced draft fan 3 is monitored in real time until the operating torque of the induced draft fan 3 equals the set torque.

[0056] In general cases, the main shaft torque of the motor 2 under the rated power is not less than the set torque of the induced draft fan 3; in some special cases, the set torque of the induced draft fan 3 is relatively large, and when the motor 2 is adjusted to the maximum power, the operating torque of the induced draft fan 3 is less than the set torque, then the diesel engine 4 can be started until the operating torque of the induced draft fan 3 equals the set torque.

[0057] 4) When there is no steam and no external power supply

[0058] The torque data of the corresponding shafting is transmitted to the control unit via each torque sensor, and the control unit analyzes and processes the torque data.

[0059] When the system detects that there is neither steam nor external power, the turbine 1 and the motor 2 are both shut down, and the induced draft fan 3 cannot be driven. The control unit 5 outputs commands to the first shaft engagement device 6 and the second shaft engagement device 7. The first shaft engagement device 6 is in the disengaged state, and the second shaft engagement device 7 is in the engaged state. At this time, the diesel engine 4 is started, and the power of the diesel engine 4 is gradually increased. The working torque of the induced draft fan 3 is monitored in real time until the working torque of the induced draft fan 3 is equal to the set torque.

[0060] If there is still an external demand for electricity, the output torque of the diesel engine 4 is increased so that the electric motor 2 is in generator mode and supplies power to the outside.

[0061] In use, the maximum output torque of the diesel engine 4 meets the working requirements of the induced draft fan 3.

[0062] Those skilled in the art will understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the invention. Although embodiments of the invention have been described, it should be understood that the invention is not limited to these embodiments, and those skilled in the art can make changes and modifications within the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for efficient utilization of low-grade steam, characterized in that, comprising the following steps: (1) sorting the steam turbine, the electric motor and the diesel engine that drive the induced draft fan; (2) determining whether there is a steam-driven steam turbine in operation and whether there is an external power supply-driven electric motor in operation; (3) when steam is available and external power supply is available, the induced draft fan is driven to operate by the steam turbine, or the induced draft fan is driven to operate jointly by the steam turbine and the electric motor; when steam is available and no external power supply is available, the induced draft fan is driven to operate by the steam turbine, or the induced draft fan is driven to operate jointly by the steam turbine and the diesel engine; when no steam is available, the induced draft fan is driven to operate by the electric motor and / or the diesel engine; The step 2 further comprises acquiring the torque M1 of the steam turbine, the torque M2 of the electric motor and the torque M3 of the diesel engine in real time, and recording the set torque of the induced draft fan as M0; In the step 3, when steam is available and no external power supply is available, the steam turbine is started; if M1≥M0, the diesel engine is shut down, and the induced draft fan is driven to operate by the steam turbine; if M1<M0, the diesel engine is started, and the induced draft fan is driven to operate jointly by the steam turbine and the diesel engine; In the step 3, when no steam is available and external power supply is available, the electric motor is started, and the induced draft fan is driven to operate by the electric motor; when no steam is available and no external power supply is available, the diesel engine is started, and the induced draft fan is driven to operate by the diesel engine; If M3>M0, the diesel engine drives the induced draft fan to operate and causes the electric motor to store electric energy for supplying power to electric equipment.

2. The method for efficient utilization of low-grade steam according to claim 1, characterized in that, In the step 3, when steam is available and external power supply is available, the steam turbine is started; if M1≥M0, the electric motor is shut down, and the induced draft fan is driven to operate by the steam turbine; if M1<M0, the electric motor is started, and the induced draft fan is driven to operate jointly by the steam turbine and the electric motor.

3. The method for efficient utilization of low-grade steam according to claim 2, characterized in that, If M1>M0, the steam turbine drives the induced draft fan to operate and causes the electric motor to store electric energy for supplying power to electrical appliances.

4. A system for implementing the method for efficient utilization of low-grade steam as described in any one of claims 1-3, characterized in that, comprising a steam turbine, an induced draft fan, an electric motor, a diesel engine and a control unit, wherein the steam turbine is provided with a steam inlet for steam to pass in, the output end of the steam turbine is connected with the electric motor through a first shaft system meshing device, the induced draft fan is connected with the electric motor, the diesel engine is connected with the induced draft fan through a second shaft system meshing device, and the steam turbine, the induced draft fan, the electric motor, the diesel engine, the first shaft system meshing device and the second shaft system meshing device are all electrically connected with the control unit.

5. The low-grade steam high-efficiency utilization system according to claim 4, characterized in that, The steam turbine, the electric motor and the diesel engine are respectively connected with torque sensors, and each of the torque sensors is electrically connected with the control unit.

6. The low-grade steam high-efficiency utilization system according to claim 4, characterized in that, A gear box is arranged between the steam turbine and the first shaft system meshing device.

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