Parallel type steam combined cycle waste heat boiler denitration system and denitration method

Abstract

The invention relates to the technical field of power plant denitration, in particular to a parallel type steam combined cycle waste heat boiler denitration system and method. Comprising a denitration assembly, the denitration assembly comprises a metering module, and the metering module comprises at least two furnace metering modules connected in parallel through a dilution water main pipe and a first flow control piece arranged between the two furnace metering modules; and the feeding assembly comprises a feeding water tank which is used for providing raw materials for the metering module and is connected with a dilution water main pipe. The system has the beneficial effects that the first flow control piece and the second flow control piece are additionally arranged between the dilution water pipelines of the waste heat boilers of every two adjacent units, so that part of pipeline systems can be independently isolated and can be switched into a single-unit denitration system operation mode, and the phenomenon that the pipelines are frozen in winter is avoided. Meanwhile, independent isolation and operation can be realized according to requirements, so that equipment can be conveniently and independently overhauled and operated, and the flexibility of a denitration system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of denitration in power plants, and in particular to a denitration system and a denitration method for a parallel steam combined cycle waste heat boiler. Background Art

[0002] For the waste heat boiler denitration system of the two units of the gas-steam combined cycle power plant, which adopts the mother pipe parallel operation mode, when there is only one unit, the dilution water must pass through the metering module of one unit before it can reach the other unit, thus forming a complete loop. However, this process is inevitably accompanied by the waste of medium, pressure loss and increased failure rate. Even under low temperature conditions in winter, the medium solution remaining in the pipeline will gradually freeze, causing pipeline blockage and even equipment damage, thus affecting the normal operation of the denitration system. In addition, due to the mother pipe parallel operation mode, it is impossible to isolate it separately. When the two units are running at the same time or one unit is running and the other is stopped, it is impossible to quickly carry out maintenance work, which puts great pressure on the stable operation of the units and the environmental protection requirements of emissions.

[0003] For the denitrification system that adopts the mother pipe parallel operation mode, the current common operation mode is to put the denitrification system into operation when the unit is started, that is, to spray urea solution, and stop spraying urea solution after the unit is shut down. This method may cause the following possibilities: First, it may cause waste of solution and increase production costs. Through experiments, we found that in the early stage of unit startup, due to the slow temperature rise in the denitrification area, the reaction temperature range of the catalyst could not be reached quickly, resulting in a low denitrification efficiency. Second, the start-stop method of the conventional urea spray gun may cause blockage of the pipeline and the spray gun, resulting in an increase in the failure rate. The urea solution used in denitrification is mostly a configuration solution, which is greatly affected by the ambient temperature and is prone to crystallization and blockage. Direct startup or shutdown under different temperature conditions will cause blockage of the pipeline and the spray gun. At the same time, the instability of the solution will also cause concentration instability, resulting in abnormal fluctuations in the denitrification system and unstable efficiency. Summary of the invention

[0004] In view of the above existing technical problems, the present invention is proposed.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a parallel steam combined cycle waste heat boiler denitrification system, which includes a denitrification component, the denitrification component includes a metering module, the metering module includes at least two furnace metering modules connected in parallel through a dilution water mother pipe, and a first flow control component arranged between the two furnace metering modules; a feeding component, the feeding component includes a feeding water tank that provides raw materials to the metering module and is connected to the dilution water mother pipe.

[0006] As a preferred solution of the parallel steam combined cycle waste heat boiler denitrification system of the present invention, the metering module includes a first furnace metering module and a second furnace metering module, and the first furnace metering module and the second furnace metering module are connected in parallel through a dilution water pipe.

[0007] As a preferred solution of the parallel steam combined cycle waste heat boiler denitrification system of the present invention, the first flow control component includes a first isolation valve and a second isolation valve, both of which are located on the dilution water mother pipe and are used to control the on and off of the dilution water to the first furnace metering module.

[0008] As a preferred solution of the parallel steam combined cycle waste heat boiler denitrification system of the present invention, a second flow control component is arranged on the sub-pipe of the second furnace metering module, and the second flow control component includes a third isolation valve and a fourth isolation valve, and the third isolation valve and the fourth isolation valve are used to control the on-off of the dilution water to the second furnace metering module.

[0009] As a preferred solution of the parallel steam combined cycle waste heat boiler denitration system of the present invention, the first flow control component and the first furnace metering module are provided with a sewage discharge component, and the sewage discharge component is located on the dilution jellyfish pipe.

[0010] As a preferred solution of the parallel steam combined cycle waste heat boiler denitrification system of the present invention, the sewage discharge component includes a sewage valve and a ditch, and the dilution water can be discharged into the ditch through the sewage valve.

[0011] As a preferred solution of the parallel steam combined cycle waste heat boiler denitrification system of the present invention, a dilution water pump water replenishment pneumatic valve is connected to the water inlet pipe of the feed water tank, and the desalted water enters the feed water tank through the dilution water pump water replenishment pneumatic valve.

[0012] As a preferred solution of the parallel steam combined cycle waste heat boiler denitrification system of the present invention, wherein: the water outlet pipeline of the feed water tank is connected with a manual regulating valve, the manual regulating valve is connected to the first outlet valve of the feed water tank on the side away from the feed water tank, and the water outlet of the feed water tank is connected to the dilution water pipe through the manual regulating valve.

[0013] As a preferred solution of the parallel steam combined cycle waste heat boiler denitrification system of the present invention, a second outlet valve is connected to the other water outlet pipe of the feed water tank, and a dilution water pump control component is arranged on the side of the second outlet valve away from the feed water tank.

[0014] The present invention also provides a denitration method, including a parallel steam combined cycle waste heat boiler denitration system, and before starting the generator set, adding dilution water to flush the pipeline, adding urea solution during the startup process; after the generator set is shut down, adding dilution water to flush the pipeline again.

[0015] The beneficial effects of the parallel steam combined cycle waste heat boiler denitration system and denitration method of the present invention are as follows: by installing the first flow control component and the second flow control component between the dilution water pipelines of the waste heat boilers of two adjacent units, it is possible to achieve the isolation of part of the pipeline system and switch to the operation mode of the single unit denitration system, thereby avoiding the freezing of pipelines in winter. At the same time, it can be isolated and operated separately according to demand, which is convenient for the separate maintenance and operation of the equipment and improves the flexibility of the denitration system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0017] Figure 1 This is a diagram of the parallel steam combined cycle waste heat boiler denitration system in the present invention.

[0018] Figure 2 This is a comparison chart of the denitrification efficiency of different gas turbine exhaust gas temperatures in the present invention.

[0019] Figure 3 It is a comparison diagram of urea flow rate in the present invention. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0023] Example 1, reference Figure 1 , which is the first embodiment of the present invention, and provides a parallel steam combined cycle waste heat boiler denitration system, including a denitration component 100, the denitration component 100 includes a metering module 100a, the metering module 100a includes at least two furnace metering modules connected in parallel through a dilution water tube, and a first flow control member 103 provided between the two furnace metering modules;

[0024] The material supply component 200 includes a material supply water tank 201 that provides raw materials to the metering module 100a and is connected to a dilution water pipe.

[0025] Preferably, the drain outlet of the feed water tank 201 is connected to the dilution water tube, and the dilution water tube is respectively connected to a plurality of furnace metering modules, and a first flow control member 103 is arranged between the plurality of furnace metering modules, and the number of the first flow control members 103 is set according to the number of furnace metering modules. If the number of furnace metering modules is N, the number of the first flow control members 103 is N-1.

[0026] Furthermore, the branch pipeline on the dilution water jelly pipe is a sub-pipeline, and the water inlet pipe of each furnace metering module is connected to the dilution water sub-pipe. Therefore, from the overall point of view, each furnace metering module tends to be connected in parallel.

[0027] It should be noted that the first flow control element 103 is used to control the on / off of the pipeline connected therein.

[0028] In summary, when the feeding assembly 200 provides desalted water dilution water to each furnace metering module to enter the pipeline of the metering module 100a, the desalted water dilution water can be discharged into the required furnace metering module separately by controlling the on and off of the first flow control component 103, without having to pass through all the furnace metering modules due to the influence of the parallel connection method.

[0029] Example 2, reference Figure 1 , which is the second embodiment of the present invention, and further provides a parallel steam combined cycle waste heat boiler denitration system. The metering module 100a includes a first furnace metering module 101 and a second furnace metering module 102, and the first furnace metering module 101 and the second furnace metering module 102 are connected in parallel through a dilution water pipe.

[0030] Preferably, the water inlet pipelines of the first furnace metering module 101 and the second furnace metering module 102 are connected to the desalted water dilution jellyfish pipe, and one side of the first furnace metering module 101 and the second furnace metering module 102 is called a sub-pipe.

[0031] The first flow control component 103 includes a first isolation valve 103a and a second isolation valve 103b. The first isolation valve 103a and the second isolation valve 103b are both located on the dilution water mother pipe and are used to control the flow of dilution water to the first furnace metering module 101.

[0032] Preferably, the first flow control member 103 includes at least two isolation valves for controlling the flow of liquid inside the pipeline. Two or more valves can control the flow of liquid more stably.

[0033] A second flow control component 104 is provided on the sub-pipe of the second furnace metering module 102 . The second flow control component 104 includes a third isolation valve 104a and a fourth isolation valve 104b . The third isolation valve 104a and the fourth isolation valve 104b are used to control the flow of dilution water to the second furnace metering module 102 .

[0034] The first flow control component 103 and the first furnace metering module 101 are provided with a sewage discharge component 105, and the sewage discharge component 105 is located on the diluted jellyfish pipe.

[0035] The sewage discharge part 105 includes a sewage discharge valve 105a and a ditch 105b, and the dilution water can be discharged into the ditch 105b through the sewage discharge valve 105a.

[0036] In summary, a diversion isolating valve is installed between the dilution water pipes of the waste heat boilers of two adjacent units, that is, two inlet valves, namely the first isolation valve 103a and the second isolation valve 103b, are added at the three-way branch of the dilution water pump outlet main pipe to the first furnace metering module 101 and the second furnace metering module 102. At the same time, a sewage gate, namely the sewage gate 105a, is installed at the bottom of the ditch section to the first furnace metering module 101, so as to achieve separate isolation and sewage discharge of the two furnaces, and at the same time ensure that the water in the dilution water pipeline can be drained through the sewage gate to prevent the denitrification dilution water pipeline of the idle unit from freezing under low temperature conditions in winter. It is also possible to switch the start and stop of the corresponding dilution water according to the operating mode of the two units, and it is also convenient for the isolation of the system pipeline for maintenance and troubleshooting.

[0037] Example 3, reference Figure 1 , which is the third embodiment of the present invention, further provides a parallel steam combined cycle waste heat boiler denitration system. The feed water tank 201 includes a dilution water pump water supply pneumatic valve 201d connected to the water inlet pipe, and the desalted water enters the feed water tank 201 through the dilution water pump water supply pneumatic valve 201d.

[0038] The water outlet pipeline of the feed water tank 201 is connected with a manual regulating valve 201b, and the side of the manual regulating valve 201b away from the feed water tank 201 is connected to the first outlet valve 201c of the feed water tank. The water outlet of the feed water tank 201 is connected to the dilution water pipe through the manual regulating valve 201b.

[0039] Preferably, a first check valve 201c is further provided between the manual regulating valve 201b and the desalted water dilution water mother pipe to prevent the desalted water dilution water from flowing back.

[0040] A second outlet valve 201 a is connected to one side of the other water outlet pipe of the feed water tank 201 , and a dilution water pump control component 202 is provided on the side of the second outlet valve 201 a away from the feed water tank 201 .

[0041] Preferably, the dilution water pump control component 202 includes a first dilution water pump control component 202a and a second dilution water pump control component 202b connected in parallel with the first dilution water pump control component 202a. The first dilution water pump control component 202a and the second dilution water pump control component 202b are connected to the outlet water pipeline of the feed water tank 201 and are connected in parallel with the outlet water pipeline of the feed water tank 201. After the first dilution water pump control component 202a and the second dilution water pump control component 202b are merged, they are jointly input into the desalted water dilution water pipe.

[0042] Furthermore, the first dilution water pump control component 202a and the second dilution water pump control component 202b have the same internal components. Taking the first dilution water pump control component 202a as an example, the first dilution water pump control component 202a includes a dilution water pump inlet valve 202g, a dilution water pump 202f, a dilution water pump outlet check valve 202e and a dilution water pump outlet valve 202c, which are connected in sequence according to the water flow direction of the feed water tank 201.

[0043] It should be noted that the feed water tank 201 is a desalted water tank.

[0044] In summary, the feed water tank 201, i.e. the desalted water tank, controls the flow direction in parallel through the first dilution water pump control component 202a and the second dilution water pump control component 202b, and selects different output routes as required to send the desalted water dilution water into the desalted water dilution mother water pipe and finally into the denitrification component 100.

[0045] Example 4, reference Figure 1 to Figure 3 , which is the fourth embodiment of the present invention, further provides a denitration method for a parallel steam combined cycle waste heat boiler denitration system. It includes adding dilution water to flush the pipeline before the generator set is started, adding urea solution during the startup process; and adding dilution water to flush the pipeline again after the generator set is shut down.

[0046] Reference Figure 2 During the unit startup process, strictly pay attention to the gas turbine exhaust gas temperature. When the temperature rises to 180℃, add spray gun flushing water (dilution water). When the temperature reaches 210℃, add urea solution to ensure that the best denitrification efficiency is achieved when urea is sprayed. The test found that when the temperature reaches about 210℃, the denitrification rate can be optimized by adding urea spray gun, which improves the economy of the denitrification system.

[0047] Reference Figure 3, under the same load of the unit, controlling the same environmental emission requirements, performing the dilution water flushing operation and not performing the urea flow comparison chart. It can be seen that after performing the dilution water flushing operation, under the same unit load and controlling the same environmental emission requirements, the instantaneous flow of the urea solution spray gun is significantly reduced, indicating that the flow in the pipeline and the spray gun is good and unblocked, and it also greatly saves production costs.

[0048] During the unit startup process, after a lot of test analysis, it was found that the efficiency of the denitration system is highest when the catalyst is around 210°C. Finally, the best way to put the urea denitration system into use is determined as follows: during the unit startup process, the flue gas temperature of the tail flue gradually increases with the unit startup process. When the temperature reaches 180°C, spray gun flushing water (dilution water) is added, and when the temperature reaches 210°C, urea solution is added. Ensure that the best denitration efficiency is achieved when the urea solution is sprayed.

[0049] Before the unit is put into use with denitrification urea solution, use diluted water to flush the operation mode in advance, and use diluted water to flush after stopping the urea solution spray gun after the unit is shut down, so as to remove the residual urea solution in the pipeline and spray gun, avoid solution crystallization and blockage in the pipeline and spray gun, and avoid residual affecting the solution concentration.

[0050] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0051] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0052] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0053] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A parallel steam combined cycle waste heat boiler denitration system, characterized in that: include, A denitration assembly (100) comprises a metering module (100a), wherein the metering module (100a) comprises at least two furnace metering modules connected in parallel via a dilution jellyfish tube, and a first flow control element (103) disposed between the two furnace metering modules; The material supply component (200) comprises a material supply water tank (201) which provides raw materials for the metering module (100a) and is connected to a dilution water pipe.

2. The parallel steam combined cycle waste heat boiler denitration system according to claim 1, characterized in that: The metering module (100a) comprises a first furnace metering module (101) and a second furnace metering module (102), wherein the first furnace metering module (101) and the second furnace metering module (102) are connected in parallel via a dilution jellyfish pipe.

3. The parallel steam combined cycle waste heat boiler denitration system according to claim 2, characterized in that: The first flow control component (103) comprises a first isolation valve (103a) and a second isolation valve (103b), wherein the first isolation valve (103a) and the second isolation valve (103b) are both located on the dilution water mother pipe and are used to control the flow of dilution water to the first furnace metering module (101).

4. The parallel steam combined cycle waste heat boiler denitration system according to claim 3, characterized in that: A second flow control component (104) is provided on the sub-pipe of the second furnace metering module (102), and the second flow control component (104) comprises a third isolation valve (104a) and a fourth isolation valve (104b), and the third isolation valve (104a) and the fourth isolation valve (104b) are used to control the flow of dilution water to the second furnace metering module (102).

5. The parallel steam combined cycle waste heat boiler denitration system according to claim 4, characterized in that: The first flow control component (103) and the first furnace metering module (101) are provided with a sewage discharge component (105), and the sewage discharge component (105) is located on the dilution jellyfish pipe.

6. The parallel steam combined cycle waste heat boiler denitration system according to claim 5, characterized in that: The sewage discharge component (105) comprises a sewage discharge valve (105a) and a ditch (105b), and the dilution water can be discharged into the ditch (105b) through the sewage discharge valve (105a).

7. The parallel steam combined cycle waste heat boiler denitration system according to claim 6, characterized in that: The water inlet pipe of the feed water tank (201) is connected to a dilution water pump water replenishment pneumatic valve (201d), and desalted water enters the feed water tank (201) through the dilution water pump water replenishment pneumatic valve (201d).

8. The parallel steam combined cycle waste heat boiler denitration system according to claim 7, characterized in that: The water outlet pipeline of the feed water tank (201) is connected to a manual regulating valve (201b); the side of the manual regulating valve (201b) away from the feed water tank (201) is connected to the first outlet valve (201c) of the feed water tank; the water outlet of the feed water tank (201) is connected to the dilution water pipe through the manual regulating valve (201b).

9. The parallel steam combined cycle waste heat boiler denitration system according to claim 8, characterized in that: A second outlet valve (201a) is connected to one side of the other water outlet pipe of the feed water tank (201), and a dilution water pump control component (202) is provided on the side of the second outlet valve (201a) away from the feed water tank (201).

10. A denitration method, characterized in that: A parallel steam combined cycle waste heat boiler denitration system comprising any one of claims 1 to 9; and Before starting the generator set, dilution water is added to flush the pipeline. During the startup process, urea solution is added. After the generator set is shut down, dilution water is added again to flush the pipeline.

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