Coal water slurry system for rapid load increase of coal-fired unit

Abstract

This application relates to the field of energy storage media for thermal power units, and discloses a coal-water slurry system for rapid load increase in coal-fired power units. The coal-water slurry system is coupled to the pulverized coal boiler of the coal-fired power unit and includes a coal-water slurry preparation system, a coal-water slurry storage system, a coal-water slurry conveying system, and a coal-water slurry burner connected sequentially via coal-water slurry pipelines. By coupling the direct-fired pulverized coal boiler system with the coal-water slurry energy storage system, energy can be rapidly released through the stored coal-water slurry system while fully utilizing the fuel provided by the direct-fired pulverized coal system, achieving rapid load increase. The load can be increased to the value required by the power grid in a short time while maintaining stable boiler combustion.

Description

Technical Field

[0001] This application relates to the field of energy storage media for thermal power units, and in particular to a coal-water slurry system for rapid load increase of coal-fired power units. Background Technology

[0002] With the rapid increase in installed capacity of new energy wind and solar power in my country, new requirements have been placed on the operational design characteristics of future thermal power units, necessitating the ability of thermal power units to rapidly adjust loads. Currently, thermal power units mainly use direct-fired pulverized coal systems, controlling unit output changes by adjusting the amount of fuel and water entering the boiler. The regenerative systems of current thermal power units do not possess the function of assisting the unit in rapidly adjusting loads. The best-case scenario for thermal power units is a load adjustment rate of 2.5 Pe% / min when the unit load factor is above 50%. This is far from the target of 4%-5% Pe / min required for future thermal power units adapted to the new power system.

[0003] like Figure 1 As shown, a typical direct-fired pulverizing system in a thermal power plant currently consists mainly of a coal bunker, coal feeder, coal mill, and primary air fan. Large-capacity units of 300MW and above generally require 5-7 coal mills. Currently, due to limitations imposed by factors such as cutting and grinding on the output of direct-fired pulverizing systems, it is often impossible to meet the demand for timely delivery of sufficient fuel when a high load ramp-up rate is required.

[0004] like Figure 2 As shown, the existing external small pulverized coal silo solution solves the technical problem of long load increase response time of direct-fired pulverizing system, which limits the unit's rapid load change, by adding an intermediate pulverized coal silo and using an external intermediate storage pulverized coal feeding system to handle the extra pulverized coal required for load increase. This achieves the goal of improving the boiler's rapid load change capability.

[0005] However, those skilled in the art will understand that the main drawback of the aforementioned external small pulverized coal silo scheme is that the risk of deflagration in the silo system increases when the volatile matter content of the coal is relatively high. Furthermore, the system uses an impeller feeder for pulverized coal delivery, and the poor metering accuracy of the impeller feeder leads to inaccurate measurement of the amount of fuel entering the furnace. Under conditions of rapid load increase and unit overshoot operation, this can easily exacerbate the overheating of the boiler heating surfaces. In other words, the small pulverized coal silo + impeller feeder scheme suffers from high storage risks, a high risk of deflagration, low impeller feeder accuracy, and fuel overshoot exacerbating the overheating of the heating surfaces.

[0006] Therefore, there is an urgent need for a new technical solution that can effectively improve the rapid load-up capability of thermal power units, reduce safety risks, and ensure accurate metering, so as to achieve rapid, safe, and accurate fuel delivery, increase the load-up rate of units, and meet the needs of the new power system. Utility Model Content

[0007] The purpose of this application is to provide a coal-water slurry system for rapid load increase of coal-fired power units. This system couples the direct-fired pulverizing system of the pulverized coal boiler with a coal-water slurry energy storage system. By replacing the traditional pulverized coal storage scheme with the coal-water slurry energy storage system, and by utilizing the safety characteristics and precise liquid metering advantages of coal-water slurry, the system can effectively improve the rapid load increase capability of thermal power units and reduce safety risks.

[0008] The embodiments of this application disclose a coal-water slurry system for rapid load increase of a coal-fired unit. The coal-water slurry system is coupled to the pulverized coal boiler of the coal-fired unit. The coal-water slurry system includes a coal-water slurry preparation system, a coal-water slurry storage system, a coal-water slurry conveying system, and a coal-water slurry burner connected in sequence through coal-water slurry pipelines.

[0009] The coal-water slurry preparation system is used to prepare coal-water slurry from raw coal in a liquid environment and to transport the coal-water slurry to the coal-water slurry storage system.

[0010] The coal-water slurry storage system is used to store the coal-water slurry prepared by the coal-water slurry preparation system;

[0011] The coal-water slurry conveying system is used to convey the coal-water slurry stored in the coal-water slurry storage system to the coal-water slurry burner;

[0012] The coal-water slurry burner is used to inject the coal-water slurry delivered by the coal-water slurry conveying system into the pulverized coal furnace for combustion, so as to release the energy required for the coal-fired unit to rapidly increase its load.

[0013] In another preferred embodiment, the coal-water slurry preparation system includes: a coal-water slurry bunker, a belt weighing feeder, a coal-water slurry wet ball mill, a slurry buffer tank, a slurry circulation pump, and a slurry hydrocyclone;

[0014] The input end of the belt weighing feeder is connected to the coal slurry bunker, the output end of the belt weighing feeder is connected to the input end of the coal slurry wet ball mill, the output end of the coal slurry wet ball mill is connected to the input end of the slurry buffer tank, the output end of the slurry buffer tank is connected to the input end of the slurry circulation pump, the output end of the slurry circulation pump is connected to the input end of the slurry hydrocyclone, the underflow output end of the slurry hydrocyclone is connected to the input end of the coal slurry wet ball mill, and the overflow output end of the slurry hydrocyclone is connected to the input end of the coal slurry storage system and the input end of the slurry buffer tank.

[0015] The coal slurry bunker is used to store the raw coal;

[0016] The belt weighing feeder is used to transport the raw coal stored in the coal-water slurry coal bunker to the coal-water slurry wet ball mill.

[0017] The coal-water slurry wet ball mill is used to grind the raw coal into a coal-water slurry of appropriate particle size and concentration in a liquid environment.

[0018] The slurry buffer tank is used to buffer and store the coal-water slurry;

[0019] The slurry circulation pump is used to pump the coal-water slurry stored in the slurry buffer tank to the slurry hydrocyclone;

[0020] The slurry hydrocyclone is used to separate the coal-water slurry pumped by the slurry circulation pump, and discharge the separated coarse particles through the underflow output end to the coal-water slurry wet ball mill for re-grinding, and discharge the fine particles and liquid through the overflow output end to the coal-water slurry storage system and the slurry buffer tank.

[0021] In another preferred embodiment, the coal-water slurry storage system includes a coal-water slurry tank, the storage volume of which meets the coal-water slurry fuel requirements for 2-3 rapid load increases of the unit.

[0022] In another preferred embodiment, the coal-water slurry conveying system includes a coal-water slurry pump.

[0023] In another preferred embodiment, the coal-water slurry pump is a variable frequency screw pump with a flow rate that is continuously adjustable from 20% to 100%.

[0024] In another preferred embodiment, the coal-water slurry burner includes a coal-water slurry steam atomization system and an air distribution system;

[0025] The coal-water slurry steam atomization system is used to break the coal-water slurry into fine droplets using the kinetic energy of a high-speed steam flow.

[0026] The air distribution system is used to provide the air required for the combustion of coal-water slurry.

[0027] In another preferred embodiment, the air distribution system is equipped with an air regulating valve and a flow measurement device.

[0028] In another preferred embodiment, the elbows of the coal-water slurry pipeline are made of wear-resistant material, and a flow monitoring device is installed on the coal-water slurry pipeline to monitor the conveying status of the coal-water slurry in real time.

[0029] In another preferred embodiment, a shutdown purging system is provided in the coal-water slurry pipeline between the coal-water slurry storage system and the coal-water slurry burner, for purging the residue in the coal-water slurry pipeline into the pulverized coal furnace for combustion through the coal-water slurry burner; a shutdown flushing system is provided in the coal-water slurry pipeline between the coal-water slurry preparation system and the coal-water slurry storage system, for flushing the residue in the coal-water slurry pipeline with water to prevent blockage.

[0030] In another preferred embodiment, the water-coal slurry of appropriate particle size and concentration has a water content of 30%-40%, a coal powder concentration of 60%-70%, a 40-mesh particle size ratio of 99%, and a 200-mesh particle size ratio of 30%-50%.

[0031] The main differences and effects of the implementation method of this application compared with the prior art are as follows:

[0032] By coupling a direct-fired pulverized coal boiler system with a coal-water slurry energy storage system, and replacing the traditional pulverized coal storage scheme with the coal-water slurry energy storage system, the safety characteristics and precise liquid metering advantages of coal-water slurry can be utilized to effectively improve the rapid load-up capability of thermal power units and reduce safety risks.

[0033] Furthermore, a coal-water slurry preparation system is set up for 2 to 4 units. The daily output of the coal-water slurry wet ball mill can meet the fuel consumption required for rapid load increase of all units in the system, thus ensuring the continuous operation of the coal-water slurry preparation system.

[0034] Furthermore, vertical agitators are installed in the slurry buffer tank and the coal-water slurry tank to prevent the sedimentation of solid particles in the coal-water slurry.

[0035] Furthermore, by setting up a coal-water slurry steam atomization system, when the coal-water slurry enters the atomization system, it encounters the high-speed ejected steam. The high-speed impact and shearing action of the steam disperses the coal-water slurry into micron-sized particles, thereby greatly increasing the specific surface area of ​​the coal-water slurry, which is beneficial to the rapid evaporation and combustion of the coal-water slurry.

[0036] Furthermore, the air distribution system is equipped with air regulating valves and flow measurement devices to precisely control the flow rate and proportion of each airflow.

[0037] Furthermore, the elbows of the coal-water slurry pipeline are made of wear-resistant materials to reduce wear from solid particles in the coal-water slurry. Additionally, a flow monitoring device is installed on the coal-water slurry pipeline to monitor the slurry's transport status in real time.

[0038] Furthermore, this coal-water slurry system for rapid load increase of coal-fired units can ensure the rapid fuel response requirements during the rapid load increase process of the unit.

[0039] Furthermore, this coal-water slurry system for rapid load increase in coal-fired power units couples the direct-fired pulverizing system of the pulverized coal boiler with a coal-water slurry energy storage system. While fully utilizing the fuel supplied by the direct-fired pulverizing system, the energy is rapidly released through the stored coal-water slurry system, achieving rapid load increase. It can quickly raise the load to the level required by the power grid while maintaining stable boiler combustion. Attached Figure Description

[0040] Figure 1This is a schematic diagram of the structure of a direct-fired pulverizing system for thermal power units in the prior art;

[0041] Figure 2 This is a structural diagram of an external small powder hopper solution in the prior art;

[0042] Figure 3 This is a schematic diagram of a water-coal slurry system for rapid load increase of a coal-fired power unit according to an embodiment of this application;

[0043] Figure 4 This is a schematic diagram of a water-coal slurry system for rapid load increase of a coal-fired power unit, as described in an embodiment of this application. Detailed Implementation

[0044] In the following description, numerous technical details are presented to facilitate the reader's understanding of this application. However, those skilled in the art will understand that the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0045] Explanation of some concepts:

[0046] 1. Rapid Load Increase of Thermal Power Units: Rapid load increase of thermal power units refers to an operating mode in which the power output of a thermal power unit is significantly increased within a short period of time. This is generally achieved by increasing the amount of fuel entering the boiler, causing a rapid change in the amount of steam produced, and thus quickly adjusting the output power of the steam turbine. When the unit's rapid load increase capability is enhanced, the thermal power unit can quickly respond to fluctuations in the power grid's load, meet the balance between power supply and demand, and ensure the stable operation of the power grid.

[0047] 2. Coal-water slurry: refers to a non-Newtonian fluid fuel made by mixing coal powder, water and additives. It has the characteristics of good fluidity, safe storage and stable combustion. Its coal powder concentration is generally 60%-70%.

[0048] 3. Direct-fired pulverizing system: The pulverized coal is ground in a coal mill and then directly sent to the boiler for combustion by primary air. The system response speed is limited by the capacity of the pulverizing system.

[0049] 4. Impeller feeder: A device that measures and conveys pulverized coal by rotating an impeller. Its accuracy is greatly affected by the flowability of the pulverized coal.

[0050] Additionally, it should be noted that pulverized coal boilers and boilers are the same concept in this article.

[0051] This application aims to install a coal-water slurry storage silo and corresponding grinding, storage, conveying, and combustion systems in the coal bunker or on the boiler steel frame. When a rapid load increase is required, a coal-water slurry pump will deliver the slurry to a dedicated boiler burner for atomization and combustion to supplement energy. By replacing pulverized coal storage with a coal-water slurry energy storage system, the safety characteristics and precise liquid metering advantages of coal-water slurry are utilized, eliminating the limitations of the pulverized coal cloud explosion sensitivity index. This effectively improves the rapid load increase capability of thermal power units while reducing safety risks.

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0053] Embodiments of this application relate to a coal-water slurry system for rapid load increase of coal-fired power units. Figure 3 This is a schematic diagram of the water-coal slurry system used for rapid load increase in coal-fired power units. Figure 4 This is a schematic diagram of the water-coal slurry system used for rapid load increase in coal-fired power units.

[0054] Specifically, such as Figure 3 As shown, the coal-water slurry system for rapid load increase of a coal-fired unit is coupled to the pulverized coal boiler of the coal-fired unit. The coal-water slurry system includes a coal-water slurry preparation system, a coal-water slurry storage system, a coal-water slurry conveying system, and a coal-water slurry burner connected in sequence through coal-water slurry pipelines.

[0055] The coal-water slurry preparation system is used to prepare coal-water slurry from raw coal in a liquid environment and to transport the coal-water slurry to the coal-water slurry storage system.

[0056] The coal-water slurry storage system is used to store the coal-water slurry prepared by the coal-water slurry preparation system.

[0057] The coal-water slurry conveying system is used to convey the coal-water slurry stored in the coal-water slurry storage system to the coal-water slurry burner.

[0058] The coal-water slurry burner is used to inject the coal-water slurry delivered by the coal-water slurry conveying system into the pulverized coal furnace for combustion, so as to release the energy required for the coal-fired unit to rapidly increase its load.

[0059] like Figure 4 As shown, in this embodiment, preferably, the coal-water slurry preparation system includes: a coal-water slurry bunker 1, a belt weighing feeder 2, a coal-water slurry wet ball mill 3, a slurry buffer tank 4, a slurry circulation pump 5, and a slurry hydrocyclone 6.

[0060] The belt weighing feeder 2 is connected to the coal slurry bunker 1, the output of the belt weighing feeder 2 is connected to the input of the coal slurry wet ball mill 3, the output of the coal slurry wet ball mill 3 is connected to the input of the slurry buffer tank 4, the output of the slurry buffer tank 4 is connected to the input of the slurry circulation pump 5, the output of the slurry circulation pump 5 is connected to the input of the slurry hydrocyclone 6, the underflow output of the slurry hydrocyclone 6 is connected to the input of the coal slurry wet ball mill 3, and the overflow output of the slurry hydrocyclone 6 is connected to the input of the coal slurry storage system and the input of the slurry buffer tank 4.

[0061] Specifically,

[0062] The coal slurry bunker 1 is used to store the raw coal.

[0063] In this embodiment, preferably, the coal-water slurry bunker 1 can be set up separately or shared with the coal bunker in front of the pulverized coal boiler direct-fired pulverizing system. Furthermore, the storage volume of the coal-water slurry bunker 1 needs to meet the raw coal demand required for at least two rapid load increases of two generating units.

[0064] The belt weighing feeder 2 is used to transport the raw coal stored in the coal-water slurry bunker 1 to the coal-water slurry wet ball mill 3.

[0065] In this embodiment, preferably, the output of the belt weighing feeder 2 needs to meet the maximum output of the water-coal slurry wet ball mill 3 and leave a margin of more than 20%.

[0066] The wet ball mill 3 is used to grind the raw coal into a coal-water slurry of appropriate particle size and concentration in a liquid environment.

[0067] In this embodiment, preferably, the water-coal slurry of appropriate particle size and concentration has a water content of 30%-40%, a coal powder concentration of 60%-70%, a particle size distribution of 99% passing through 40 mesh (420μm), and a particle size distribution of 30%-50% passing through 200 mesh (74μm).

[0068] Furthermore, preferably, a coal-water slurry preparation system is set up for 2 to 4 units. The coal-water slurry wet ball mill 3 can meet the fuel consumption required for rapid load increase of all units in the system on a single day. This can ensure the continuous operation of the coal-water slurry preparation system. Since the capacity of the continuously operating coal-water slurry wet ball mill 3 is small, it can be installed on a spring foundation and arranged in the coal feeder layer between the coal bunkers.

[0069] The slurry buffer tank 4 is used to buffer and store the coal-water slurry.

[0070] In this embodiment, preferably, the slurry buffer tank 4 is also equipped with a vertical agitator to prevent the sedimentation of solid particles in the coal-water slurry.

[0071] The slurry circulation pump 5 is used to pump the coal-water slurry stored in the slurry buffer tank 4 to the slurry hydrocyclone 6.

[0072] A slurry circulation pump 5 is installed in the coal-water slurry preparation system. The flow rate of the slurry circulation pump 5 meets the maximum output of the coal-water slurry wet ball mill 3 and has a margin of more than 20%. Furthermore, the flow rate of the slurry circulation pump 5 is controlled in a closed loop by a mass flow meter (not shown in the figure).

[0073] The slurry hydrocyclone 6 is used to separate the coal-water slurry pumped by the slurry circulation pump 5, and discharge the separated coarse particles through the underflow output end to the coal-water slurry wet ball mill 3 for re-grinding, and discharge the fine particles and liquid through the overflow output end to the coal-water slurry storage system (coal-water slurry tank 7) and the slurry buffer tank 4.

[0074] For example Figure 4 As shown, in this embodiment, preferably, the coal-water slurry storage system includes a coal-water slurry tank 7, with one coal-water slurry tank 7 for each unit. The storage volume of the coal-water slurry tank meets the coal-water slurry fuel requirements for 2-3 rapid load increases of the unit.

[0075] Furthermore, preferably, a vertical agitator is also provided in the coal-water slurry tank 7 to prevent the sedimentation of solid particles in the coal-water slurry.

[0076] For example Figure 4 As shown, in this embodiment, preferably, the coal-water slurry conveying system includes a coal-water slurry pump 8, and each unit is equipped with one coal-water slurry pump 8.

[0077] Furthermore, preferably, the coal-water slurry pump 8 is a variable frequency screw pump with a flow rate that is continuously adjustable from 20% to 100%. Additionally, the flow rate of the coal-water slurry pump 8 is also controlled in a closed loop using a mass flow meter (not shown in the figure).

[0078] In this embodiment, preferably, each unit is equipped with one coal-water slurry burner 9.

[0079] In this embodiment, two generating units are used as an example for explanation, so Figure 4 The diagram shows two coal-water slurry tanks 7, two coal-water slurry pumps 8, and two coal-water slurry burners 9.

[0080] Furthermore, preferably, the coal-water slurry burner 9 includes a coal-water slurry steam atomization system (not shown) and an air distribution system (not shown).

[0081] The coal-water slurry steam atomization system is used to break the coal-water slurry into fine droplets using the kinetic energy of a high-speed steam flow. The air distribution system is used to provide the necessary air for the combustion of the coal-water slurry.

[0082] The coal-water slurry burner 9 is a key piece of equipment for efficiently and stably injecting coal-water slurry into the pulverized coal boiler for combustion. Its main function is to rapidly atomize and ignite the coal-water slurry within the boiler, ensuring stable combustion and good mixing with air to achieve high combustion efficiency and low pollutant emissions. The output of the coal-water slurry burner 9 is 12-16% of the boiler load.

[0083] The coal-water slurry steam atomization system is one of the core components of the coal-water slurry burner 9. Its principle is to utilize the kinetic energy of a high-speed steam stream to break the coal-water slurry into fine droplets. When the coal-water slurry enters the atomization system, it encounters the high-speed ejected steam. The high-speed impact and shearing action of the steam disperses the coal-water slurry into micron-sized particles, significantly increasing its specific surface area and facilitating rapid evaporation and combustion. In other words, this coal-water slurry burner 9 is a coal-water slurry burner with steam atomization function suitable for pulverized coal boiler combustion environments.

[0084] The air distribution system of the coal-water slurry burner provides the necessary air for the combustion of coal-water slurry.

[0085] Furthermore, preferably, the air distribution system is equipped with an air regulating valve and a flow measurement device to precisely control the flow rate and proportion of each airflow.

[0086] In this embodiment, preferably, the elbows of the coal-water slurry pipeline are made of wear-resistant material to reduce wear from solid particles in the coal-water slurry. Furthermore, a flow monitoring device is installed on the coal-water slurry pipeline to monitor the conveying status of the coal-water slurry in real time.

[0087] Furthermore, preferably, a shutdown purging system is provided in the coal-water slurry pipeline between the coal-water slurry storage system and the coal-water slurry burner, for purging the residue in the coal-water slurry pipeline into the pulverized coal furnace for combustion through the coal-water slurry burner 9; a shutdown flushing system is provided in the coal-water slurry pipeline between the coal-water slurry preparation system and the coal-water slurry storage system, for flushing the residue in the coal-water slurry pipeline with water to prevent blockage.

[0088] A shutdown purging and flushing system is installed in this coal-water slurry system. Specifically, steam purging is used between the coal-water slurry tank 7 and the coal-water slurry burner 9 in front of the furnace to purge the residue in the coal-water slurry pipeline into the boiler through the coal-water slurry burner 9 for combustion, preventing accidents such as pipeline sediment clogging the burner. In other pipelines of the coal-water slurry system, water flushing is used during shutdown to prevent blockage, and the flushing water source is process water.

[0089] In this embodiment, preferably, the coal-water slurry system may further include a control system. Specifically, the control system can determine the total amount of fuel entering the boiler based on the unit's current load rate and the required load increase rate, taking into account the unit's overshoot requirements. Ultimately, the total fuel demand of the boiler is met by the coal supply from the direct-fired pulverizing system plus precisely controlled auxiliary fuel coal-water slurry supplied according to a calorific value correction coefficient. This achieves coordinated control of the coal-water slurry and the direct-fired pulverizing system during the combustion process. The system can monitor the coal-water slurry tank level and interlock the operation of the slurry preparation system. It can also monitor, adjust, and coordinate various operating parameters of the boiler's burners for both fuels, and coordinate various operating elements such as fuel, feedwater, and air distribution to achieve safe and stable boiler operation under dual-fuel and rapid load increase conditions.

[0090] To address the deflagration and metering difficulties of pulverized coal, this coal-water slurry system replaces pulverized coal storage with a coal-water slurry energy storage system. Coal-water slurry contains 30%-40% water, which suppresses the release of volatiles from the coal, eliminating the risk of deflagration. Simultaneously, the slurry flow rate metering accuracy can be controlled within ±1%. Utilizing the safety characteristics and precise metering advantages of coal-water slurry, the system effectively enhances the rapid load-up capability of thermal power units while reducing safety risks. This coal-water slurry energy storage system, through components such as storage silos, coal feeders, wet ball mills, coal-water slurry pumps, coal-water slurry tanks, and dedicated burners, achieves rapid, safe, and precise fuel delivery, increasing the unit's load-up rate and meeting the demands of new power systems.

[0091] Therefore, this coal-water slurry system for rapid load increase in coal-fired power units couples the direct-fired pulverizing system of the pulverized coal boiler with a coal-water slurry energy storage system. While fully utilizing the fuel provided by the direct-fired pulverizing system, it rapidly releases energy through the stored coal-water slurry system, achieving rapid load increase. It can quickly raise the load to the level required by the power grid while maintaining stable boiler combustion.

[0092] It is understandable that this water-coal slurry system for rapid load increase of coal-fired units is suitable for new or retrofitted units with single or double reheat, and has the following advantages:

[0093] 1) Safety: The coal-water slurry system uses coal-water slurry, a rapid energy replenishment medium for coal-fired power plants. It has the lowest cost per unit price / calorific value among liquid media. At the same time, it is safe to operate without the risk of deflagration. The slurry storage tank does not require a complicated explosion-proof design, which reduces operation and maintenance costs.

[0094] 2) Precise control: By precisely controlling the amount of coal-water slurry entering the furnace, the overshoot parameters of the unit can be accurately controlled, avoiding overheating of the heating surface.

[0095] 3) Rapid response: The flow rate adjustment rate of the slurry pump can reach 10% / s, which can fully meet the energy replenishment needs of the unit for rapid load increase.

[0096] 4) Strong adaptability to various coal types: It is compatible with various coal qualities, and the coal types used for combustion are not subject to the restriction in the explosion protection standard DL / T5203 for thermal power plants that the cloud explosion sensitivity index of coal powder in the storage system should not be greater than 3.

[0097] 5) Long conveying distance: The flow characteristics of coal-water slurry are similar to those of liquid. Compared with pneumatic conveying, the conveying distance can be very long, and multiple units can be equipped with only one slurry preparation system.

[0098] 6) The coal-water slurry is directly pumped into the coal-water slurry burner and atomized before entering the boiler. This part of the fuel does not use primary air as carrier air, which can increase the boiler's secondary air rate, reduce the flue gas temperature, and thus improve boiler efficiency.

[0099] In summary, this coal-water slurry system for rapid load increase of coal-fired power units couples the direct-fired pulverizing system of the pulverized coal boiler with a coal-water slurry energy storage system. By replacing the traditional pulverized coal storage scheme with the coal-water slurry energy storage system, and by utilizing the safety characteristics and precise liquid metering advantages of coal-water slurry, it can effectively improve the rapid load increase capability of thermal power units and reduce safety risks.

[0100] It should be noted that the components or devices mentioned in the embodiments of this application are all logical modules. Physically, a logical module can be a physical module, a part of a physical module, or a combination of multiple physical modules. The physical implementation of these logical modules themselves is not the most important factor; rather, the combination of functions implemented by these logical modules is the key to solving the technical problem proposed in this application. Furthermore, to highlight the innovative aspects of this application, the above-described system embodiments have not introduced components or devices that are not closely related to solving the technical problem proposed in this application. This does not mean that other components or devices do not exist in the above embodiments.

[0101] It should be noted that in the claims and specification of this patent, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0102] Although this application has been illustrated and described with reference to certain preferred embodiments thereof, those skilled in the art should understand that various changes in form and detail may be made thereto without departing from the spirit and scope of this application.

Claims

1. A water-coal slurry system for rapid load increase in coal-fired power units, characterized in that, The coal-water slurry system is coupled to the pulverized coal boiler of the coal-fired unit. The coal-water slurry system includes a coal-water slurry preparation system, a coal-water slurry storage system, a coal-water slurry conveying system, and a coal-water slurry burner, which are connected in sequence through coal-water slurry pipelines. The coal-water slurry preparation system is used to prepare coal-water slurry from raw coal in a liquid environment and to transport the coal-water slurry to the coal-water slurry storage system. The coal-water slurry storage system is used to store the coal-water slurry prepared by the coal-water slurry preparation system; The coal-water slurry conveying system is used to convey the coal-water slurry stored in the coal-water slurry storage system to the coal-water slurry burner; The coal-water slurry burner is used to inject the coal-water slurry delivered by the coal-water slurry conveying system into the pulverized coal furnace for combustion, so as to release the energy required for the coal-fired unit to rapidly increase its load.

2. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 1, characterized in that, The coal-water slurry preparation system includes: a coal-water slurry bunker, a belt weighing feeder, a coal-water slurry wet ball mill, a slurry buffer tank, a slurry circulation pump, and a slurry hydrocyclone; The input end of the belt weighing feeder is connected to the coal slurry bunker, the output end of the belt weighing feeder is connected to the input end of the coal slurry wet ball mill, the output end of the coal slurry wet ball mill is connected to the input end of the slurry buffer tank, the output end of the slurry buffer tank is connected to the input end of the slurry circulation pump, the output end of the slurry circulation pump is connected to the input end of the slurry hydrocyclone, the underflow output end of the slurry hydrocyclone is connected to the input end of the coal slurry wet ball mill, and the overflow output end of the slurry hydrocyclone is connected to the input end of the coal slurry storage system and the input end of the slurry buffer tank. The coal slurry bunker is used to store the raw coal; The belt weighing feeder is used to transport the raw coal stored in the coal-water slurry coal bunker to the coal-water slurry wet ball mill. The coal-water slurry wet ball mill is used to grind the raw coal into a coal-water slurry of appropriate particle size and concentration in a liquid environment. The slurry buffer tank is used to buffer and store the coal-water slurry; The slurry circulation pump is used to pump the coal-water slurry stored in the slurry buffer tank to the slurry hydrocyclone; The slurry hydrocyclone is used to separate the coal-water slurry pumped by the slurry circulation pump, and discharge the separated coarse particles through the underflow output end to the coal-water slurry wet ball mill for re-grinding, and discharge the fine particles and liquid through the overflow output end to the coal-water slurry storage system and the slurry buffer tank.

3. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 1, characterized in that, The coal-water slurry storage system includes a coal-water slurry tank, the storage volume of which meets the coal-water slurry fuel requirements for 2-3 rapid load increases of the unit.

4. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 1, characterized in that, The coal-water slurry conveying system includes a coal-water slurry pump.

5. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 4, characterized in that, The coal-water slurry pump is a variable frequency screw pump with a flow rate that is continuously adjustable from 20% to 100%.

6. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 1, characterized in that, The coal-water slurry burner includes a coal-water slurry steam atomization system and an air distribution system; The coal-water slurry steam atomization system is used to break the coal-water slurry into fine droplets using the kinetic energy of a high-speed steam flow. The air distribution system is used to provide the air required for the combustion of coal-water slurry.

7. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 6, characterized in that, The air distribution system is equipped with air regulating valves and flow measurement devices.

8. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 1, characterized in that, The elbows of the coal-water slurry pipeline are made of wear-resistant materials, and a flow monitoring device is installed on the coal-water slurry pipeline to monitor the conveying status of the coal-water slurry in real time.

9. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 1, characterized in that, A shutdown purging system is provided in the coal-water slurry pipeline between the coal-water slurry storage system and the coal-water slurry burner to purge the residue in the coal-water slurry pipeline into the pulverized coal furnace for combustion; a shutdown flushing system is provided in the coal-water slurry pipeline between the coal-water slurry preparation system and the coal-water slurry storage system to flush the residue in the coal-water slurry pipeline with water to prevent blockage.

10. The water-coal slurry system for rapid load increase of coal-fired power units according to claim 2, characterized in that, The appropriate particle size and concentration of the coal-water slurry are as follows: water content of 30%-40%, coal powder concentration of 60%-70%, particle size of 99% passing through 40 mesh, and particle size of 30%-50% passing through 200 mesh.

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