阅读说明：本技术 一种构建多参数汽源辅汽联箱系统的方法 (Method for constructing multi-parameter steam source auxiliary steam header system ) 是由 屈杰 高庆 朱蓬勃 居文平 马汀山 高登攀 张永海 谷伟伟 曾立飞 潘渤 祁文玉 于 2021-03-15 设计创作，主要内容包括：本发明公开了一种构建多参数汽源辅汽联箱系统的方法,本发明通过对机组辅助蒸汽系统设计、运行、检修及改造等数据等关键资料进行收集分析,掌握辅助蒸汽系统技术现状,依据所定量核准的用户用汽参数,在系统中分别优化设计了涵盖高、低压汽源等多参数汽源的辅汽蒸汽系统,同时进行用户能级刨分,将高、低能级用户分别匹配连接至相应能级的辅助蒸汽系统中,达到了保证生产要求的条件下减少蒸汽消耗量,减少损提升系统运行效率的目的。本发明可有效解决汽源点与辅汽用户能级匹配能量梯级利用的问题,对改善机组安全经济运行具有十分重要的意义。(The invention discloses a method for constructing a multi-parameter steam source auxiliary steam header system, which collects and analyzes key data such as data of unit auxiliary steam system design, operation, maintenance, modification and the like, grasps the technical current situation of the auxiliary steam system, optimizes and designs an auxiliary steam system covering high-pressure steam sources, low-pressure steam sources and other multi-parameter steam sources in the system according to quantitatively approved steam parameters for users, simultaneously carries out user energy level planning, connects high-energy level users and low-energy level users to the auxiliary steam system with corresponding energy levels in a matching manner, reduces the steam consumption under the condition of ensuring the production requirement, and reduces the steam consumption The purpose of improving the operation efficiency of the system is reduced. The invention can effectively solve the problem of energy gradient utilization of energy level matching between the steam source point and the auxiliary steam users, and has very important significance for improving the safe and economic operation of the unit.)

1. A method for constructing a multi-parameter steam source auxiliary steam header system is characterized by comprising the following steps:

analyzing the steam source connection and the steam supply range of a user of the conventional auxiliary steam system according to the structure and an assembly drawing of an auxiliary steam system unit;

secondly, mastering the technical operation current situation of the auxiliary steam system according to the daily operation log of the unit and the data of the auxiliary steam system, and analyzing the problems existing between a steam source and the start and stop of the unit in the auxiliary steam system;

quantitatively approving the steam consumption of the auxiliary steam system user, carrying out steam level and consumption statistics of the auxiliary steam system user from two aspects of a starting process and unit commissioning, and dividing the auxiliary steam system user into a high-level user and a low-level user;

step four, optimizing the arrangement of an auxiliary steam system of a target unit on the basis of ensuring the safety and stability of the auxiliary steam system according to the requirements of auxiliary steam during the starting and running of the unit;

and fifthly, combining the steam utilization parameter requirements of each auxiliary steam user, performing energy level planning on each user, and covering the auxiliary steam systems of the high-pressure gas source and the low-pressure gas source respectively, wherein the high-energy-level user is connected in the high-pressure auxiliary steam system, and the low-energy-level user is connected in the low-pressure auxiliary steam system.

2. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 1, wherein in the first step, the assembly drawing of the auxiliary steam system comprises a steam turbine technical specification, a boiler technical specification, an auxiliary machine technical specification, a vertical section drawing of a high pressure part, a middle pressure part and a low pressure part of a steam turbine, a thermodynamic calculation book of the steam turbine, a thermal balance diagram, a centralized control operation rule and a maintenance rule.

3. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 1, wherein in the third step, the starting process comprises a flushing stage and an initial ignition stage, and the flushing stage comprises a cold flushing stage and a hot flushing stage.

4. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 1, wherein in the fifth step, the header parameter setting pressure of the high-pressure auxiliary steam system is 1.2MPa, the temperature is 300 ℃, and the header parameter setting pressure of the low-pressure auxiliary steam system is 0.8MPa, and the temperature is 280 ℃.

5. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 1, wherein in the fifth step, the header steam source of the high-pressure auxiliary steam system is cold reheat steam and auxiliary steam from an auxiliary steam connecting pipe, when the cold reheat steam parameter does not meet the steam using requirement, the auxiliary steam is used, and when the cold reheat steam parameter meets the switching condition, the cold reheat steam source is switched.

6. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 1, wherein in the fifth step, the header steam source of the low-pressure auxiliary steam system is auxiliary steam from an auxiliary steam connecting pipe and the low five-stage steam extraction of the steam turbine, and when the low five-stage steam extraction of the steam turbine does not meet the steam utilization requirement, the auxiliary steam is used.

7. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 1, wherein in the third step, the high-energy-level users comprise boiler start-up hearth heating and condenser start-up air extraction;

the low-level users comprise air preheater soot blowing, deaerator and water tank heating, steam for a steam turbine shaft seal system, dust remover ash bucket heating, a boiler air heater, denitration soot blowing and steam for a small steam turbine.

8. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 1, wherein after the energy level planning of the step five is completed, technical and economic analysis is performed to evaluate the technical and economic feasibility of the auxiliary steam system.

9. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 8, wherein the technical and economic analysis is used for carrying out steam source parameter accounting on the high-pressure auxiliary steam system and the low-pressure auxiliary steam system when the unit is in the working conditions of 100% THA, 75% THA and 50% THA respectively according to a turbine thermodynamic equilibrium diagram.

10. The method for constructing the multi-parameter steam source auxiliary steam header system according to claim 8, wherein the technical and economic analysis comprises quantitative approval of auxiliary steam consumption in the starting process of the unit, and an equivalent enthalpy drop method is adopted to respectively calculate the work capacity reduction amount and the heat absorption amount change of the system to obtain the device efficiency reduction value, and finally, the operation economy of the unit is evaluated, wherein the calculation method comprises the following steps:

the reduction of the work capacity:

△H₁＝20/G×(H_1z-H_n+Q)

wherein G is the main steam flow, H_1zIs the cold specific enthalpy, H_nIs the exhaust enthalpy, and Q is the reheat steam heat absorption capacity;

change of heat absorption:

△Q₁＝20/G×Q

the device efficiency decreases:

△η₁＝[(H-ΔH₁)/(Q₂-ΔQ₁)-η]/η×100％

wherein H is the equivalent enthalpy drop value of the new steam, Q₂The new steam heat absorption capacity is shown, and eta is the thermal efficiency of the steam turbine.

Technical Field

The invention belongs to the field of thermal power generation, and particularly relates to a method for constructing a multi-parameter steam source auxiliary steam header system.

Background

The auxiliary steam system is a steam supply system for heating and protecting steam in the thermal power plant, which is related to the starting, stopping and normal operation of a boiler and a steam turbine and auxiliary equipment thereof. The auxiliary steam system is used for steam supply users and mainly has the functions of starting and heating equipment such as a deaerator, a boiler air heater, a steam turbine cylinder interlayer, a flange bolt and the like; sealing a shaft seal system of the steam turbine; heating and purging of fuel facilities and atomization of fuel nozzles; fire fighting of the coal powder preparation system; instrument freezing prevention of an open-air boiler; maintaining equipment such as a boiler, a deaerator and the like when the equipment is stopped for a short time; heating a deaerator for standby when the unit is subjected to load shedding; heating and ventilation of a factory building, heating of an ash hopper of an electrostatic dust collector, starting and heating of a lower header of a natural circulation drum boiler and the like. The auxiliary steam system is an important subsystem involved in the starting and safe production of the thermal power plant.

At present, a thermal power generating unit is usually under a deep peak regulation operation condition, an auxiliary steam system generally has the phenomenon that an auxiliary steam user is not matched with a steam source point energy level, and in addition, a plurality of systems are directly used as an auxiliary steam header steam source to be provided to the user after high-quality steam is subjected to temperature reduction and pressure reduction, so that great energy loss is caused.

Therefore, the existing auxiliary steam system of the unit is optimized, the problem of energy level matching and energy gradient utilization of an air source point and an auxiliary steam user is solved, and the method has great significance for improving the operation economy of the unit.

Disclosure of Invention

The invention aims to overcome the defects and provides a method for constructing a multi-parameter steam source auxiliary steam header system, which can optimize the conventional auxiliary steam system of a unit, is additionally provided with the multi-parameter steam source auxiliary steam header system by separating high-pressure auxiliary steam users and low-pressure auxiliary steam users, carries out energy level planning on each user, is respectively provided with the multi-parameter auxiliary steam systems covering high-pressure steam sources and low-pressure steam sources and the like, connects high-energy-level users in the high-pressure auxiliary steam system, connects low-energy-level users in the low-pressure auxiliary steam system, solves the problem of energy level matching and energy level gradient utilization of a gas source and auxiliary steam users, reduces the steam consumption under the condition of ensuring the production requirement, reduces the steam consumption, reduces the energy level, and solves the problem of energy level matching and energy gradient utilization of the gas source and auxiliary steam usersThe purpose of improving efficiency is lost.

In order to achieve the above object, the present invention comprises the steps of:

analyzing the steam source connection and the steam supply range of a user of the conventional auxiliary steam system according to the structure and an assembly drawing of an auxiliary steam system unit;

secondly, mastering the technical operation current situation of the auxiliary steam system according to the daily operation log of the unit and the data of the auxiliary steam system, and analyzing the problems existing between a steam source and the start and stop of the unit in the auxiliary steam system;

quantitatively approving the steam consumption of the auxiliary steam system user, carrying out steam level and consumption statistics of the auxiliary steam system user from two aspects of a starting process and unit commissioning, and dividing the auxiliary steam system user into a high-level user and a low-level user;

step four, optimizing the arrangement of an auxiliary steam system of a target unit on the basis of ensuring the safety and stability of the auxiliary steam system according to the requirements of auxiliary steam during the starting and running of the unit;

and fifthly, combining the steam utilization parameter requirements of each auxiliary steam user, performing energy level planning on each user, and covering the auxiliary steam systems of the high-pressure gas source and the low-pressure gas source respectively, wherein the high-energy-level user is connected in the high-pressure auxiliary steam system, and the low-energy-level user is connected in the low-pressure auxiliary steam system.

In the first step, the assembly drawing of the auxiliary steam system comprises a steam turbine technical specification, a boiler technical specification, an auxiliary machine technical specification, a high-pressure part, a middle-pressure part and a low-pressure part of the steam turbine, a thermal calculation specification of the steam turbine, a thermal balance diagram, a centralized control operation rule and a maintenance rule.

In the third step, the starting process includes a flushing stage and an initial stage of ignition, and the flushing stage includes a cold flushing stage and a hot flushing stage.

In the fifth step, the pressure of the header parameter setting of the high-pressure auxiliary steam system is 1.2MPa, the temperature is 300 ℃, the pressure of the header parameter setting of the low-pressure auxiliary steam system is 0.8MPa, and the temperature is 280 ℃.

And fifthly, the steam source of the header of the high-pressure auxiliary steam system is cold reheat steam and auxiliary steam from an auxiliary steam connecting pipe, when the cold reheat steam parameter does not meet the steam using requirement, the auxiliary steam is used, and when the cold reheat steam parameter meets the switching condition, the cold reheat steam source is switched.

And step five, a header steam source of the low-pressure auxiliary steam system is auxiliary steam from an auxiliary steam connecting pipe and low five-section steam extraction of the steam turbine, and when the low five-section steam extraction of the steam turbine does not meet the steam utilization requirement, the auxiliary steam is used.

In the third step, the high-energy-level user comprises boiler starting furnace bottom heating and condenser starting air extraction;

the low-level users comprise air preheater soot blowing, deaerator and water tank heating, steam for a steam turbine shaft seal system, dust remover ash bucket heating, a boiler air heater, denitration soot blowing and steam for a small steam turbine.

And after the energy level planning in the step five is completed, carrying out technical and economic analysis, and evaluating the technical and economic feasibility of the auxiliary steam system.

The technical and economic analysis respectively carries out the steam source parameter accounting of the high-pressure auxiliary steam system and the low-pressure auxiliary steam system when the unit is in the working conditions of 100% THA, 75% THA and 50% THA according to a thermal equilibrium diagram of the steam turbine.

The technical and economic analysis comprises quantitatively approving the auxiliary steam consumption in the starting process of the unit, respectively calculating the work capacity reduction amount and the heat absorption change of the system by adopting an equivalent enthalpy drop method to obtain the device efficiency reduction value, and finally evaluating the operation economy of the unit, wherein the calculation method comprises the following steps:

the reduction of the work capacity:

△H₁＝20/G×(H_1z-H_n+Q)

wherein G is the main steam flow, H_1zIs the cold specific enthalpy, H_nIs the exhaust enthalpy, and Q is the reheat steam heat absorption capacity;

change of heat absorption:

△Q₁＝20/G×Q

the device efficiency decreases:

△η₁＝[(H-ΔH₁)/(Q₂-ΔQ₁)-η]/η×100％

wherein H is the equivalent enthalpy drop value of the new steam, Q₂Eta is turbine for new steam heat absorptionAnd (4) thermal efficiency.

Compared with the prior art, the auxiliary steam system has the advantages that the technical current situation of the auxiliary steam system is mastered by collecting and analyzing key data such as data of unit auxiliary steam system design, operation, maintenance, modification and the like, the auxiliary steam system covering high-pressure steam sources, low-pressure steam sources and other multi-parameter steam sources is respectively and optimally designed in the system according to quantitatively approved steam parameters of users, the energy level of the users is planed, the high-energy level users and the low-energy level users are respectively connected to the auxiliary steam systems with corresponding energy levels in a matching mode, the steam consumption is reduced under the condition of ensuring the production requirement, and the steam consumption is reducedThe purpose of improving the operation efficiency of the system is reduced. The invention can effectively solve the problem of energy gradient utilization of energy level matching between the steam source point and the auxiliary steam users, and has very important significance for improving the safe and economic operation of the unit.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a diagram of a primary auxiliary steam system of a power plant according to an embodiment;

FIG. 3 is a diagram of an auxiliary steam system after optimization of a power plant according to an embodiment.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1, the present invention comprises the steps of:

step one, analyzing the steam source connection and the steam supply range of a user of the conventional auxiliary steam system according to the actual structure of the unit and a system assembly drawing.

Further, the actual structure of required unit and system assembly drawing include: technical specification specifications of a steam turbine, technical specification specifications of a boiler, technical specification specifications of other auxiliary machines (such as a boiler pulverizing system, a feed pump, a condensate pump, a circulating water pump, a condenser, a cooling tower, a main transformer and the like), longitudinal section diagrams of high, middle and low pressure parts of the steam turbine, thermodynamic calculation specifications of the steam turbine, a thermal balance diagram, centralized control operation regulations, maintenance regulations and the like;

and secondly, mastering the technical operation current situation of the auxiliary steam system according to the daily operation log of the unit, the design data, the operation data and other data of the auxiliary steam system in the plant, and analyzing the steam source and unit start-stop problems of the auxiliary steam system.

And step three, quantitatively approving the steam consumption of the auxiliary steam system user, and carrying out steam level and consumption statistics of the auxiliary steam system user from two aspects of a starting process and unit commissioning.

Further, the start-up process includes a flushing stage, which is a cold flushing stage and a hot flushing stage, respectively. The starting process also includes an initial phase of ignition.

And step four, according to the requirements of auxiliary steam during starting and running of the unit, on the basis of ensuring the safety and stability of the auxiliary steam system, and simultaneously referring to relevant standards of the power industry, an optimization scheme is provided for the arrangement of the auxiliary steam system of the target unit.

The referenced power industry-related standards include: DL/T834-2003 thermal power plant guide rules for preventing water inflow and cold steam of steam turbines, ASME TDP-1-2013 recommended implementation regulations for preventing water damage of steam turbines for power generation;

and step five, combining the steam utilization parameter requirements of each auxiliary steam user in the step three, performing energy level planning on each user, and respectively setting multi-parameter auxiliary steam systems covering high-pressure steam sources, low-pressure steam sources and the like, wherein the high-energy-level user is connected in the high-pressure auxiliary steam system, and the low-energy-level user is connected in the low-pressure auxiliary steam system. And an adjustment suggestion is provided for the operation mode of the optimized system.

Further, the pressure of the high-pressure auxiliary steam system header parameter setting is 1.2MPa, the temperature is 300 ℃, the pressure of the low-pressure auxiliary steam header parameter setting is 0.8MPa, and the temperature is 280 ℃.

Further, the steam source of the header of the high-pressure auxiliary steam system is cold reheat steam and auxiliary steam from an auxiliary steam connecting pipe, when the cold reheat parameter can not meet the steam using requirement, machine-side auxiliary steam is used, and when the cold reheat steam parameter reaches a switching condition (not lower than 1.4 MPa), the cold reheat steam is switched to the cold reheat steam source.

Furthermore, the steam source of the header of the low-pressure auxiliary steam system is auxiliary steam from an auxiliary steam connecting pipe and steam extraction at the lower five sections of the steam turbine, and when the steam extraction at the lower five sections of the steam turbine cannot meet the steam utilization requirement, the auxiliary steam is used immediately.

Further, the high-level users connected in the high-pressure auxiliary steam system respectively include: 1) starting a boiler to heat the bottom of the furnace; 2) the condenser starts to pump air.

Further, the low level users connected in the low pressure auxiliary steam system respectively include: 1) blowing ash by an air preheater; 2) heating a deaerator and a water tank; 3) steam for a steam turbine shaft seal system; 4) heating an ash bucket of the dust remover; 5) a boiler air heater; 6) denitration soot blowing; 7)

steam for small turbines.

And step six, after the design of the system scheme is finished, carrying out technical and economic analysis, and comprehensively evaluating the technical and economic feasibility of the designed and optimized auxiliary steam system.

Further, the technical analysis carries out the steam source parameter accounting of the high-pressure auxiliary steam system and the low-pressure auxiliary steam system when the unit is in the working conditions of 100% THA, 75% THA and 50% THA respectively according to a thermal equilibrium diagram of the steam turbine.

Further, the auxiliary steam consumption in the starting process of the unit is quantitatively approved through economic analysis, the work capacity reduction amount and the heat absorption change of the system are respectively calculated by adopting an equivalent enthalpy drop method so as to obtain the device efficiency reduction value, and finally the operation economy of the unit is evaluated.

1) Reduction of work capacity

△H₁＝20/G×(H_1z-H_n+Q)(1)

Wherein: g is the main steam flow, and the main steam flow is designed according to the rated working condition; h_1zIs the cold specific enthalpy, kJ/kg; h_nTaking a THA working condition design value as exhaust enthalpy, kJ/kg; q is reheat steam endotherm, kJ/kg.

2) Variation of heat absorption

△Q₁＝20/G×Q (2)

3) Reduction in device efficiency

△η₁＝[(H-ΔH₁)/(Q₂-ΔQ₁)-η]/η×100％ (3)

Wherein: h is the equivalent enthalpy drop value of the new steam, kJ/kg; q₂kJ/kg as new steam heat absorption; eta is the thermal efficiency of the steam turbine, and is 0.44.

Referring to fig. 2, an embodiment of the present invention is shown in a power plant as an example.

The type of a steam turbine in a certain power plant is as follows: subcritical, single intermediate reheating, single shaft, three cylinders, double steam discharge and impulse condensing type.

The original auxiliary steam system of the unit consists of a steam supply system, an auxiliary steam header, an auxiliary steam user and an auxiliary steam system safety door, wherein an auxiliary steam main pipe is arranged in the whole plant, and each unit is provided with an auxiliary steam header. The pressure of the auxiliary steam header is set to be 1.2MPa, and the temperature is 300 ℃. Wherein the cold steam supply pressure is 4.17MPa, and the cold steam supply temperature is 326 ℃. The pressure operation pressure of the auxiliary steam header is 1.2MPa, and the steam temperature of the auxiliary steam header is 300 ℃. Setting pressure of 3 safety doors of the auxiliary steam header: no. 1.4MPa, No. 2 1.4MPa, No. 3 1.4 MPa. When the auxiliary steam system is in operation, when the pressure of the cold reheating steam is not lower than 1.4MPa, steam is supplied to the auxiliary steam header from the cold reheating steam, otherwise, steam is supplied to the auxiliary steam header from the temporary machine. The auxiliary steam header of the No. 1 and No. 2 unit in the original system is connected with the auxiliary steam header through an auxiliary steam connecting pipe, the auxiliary steam header and the auxiliary steam header are mutually standby, and the auxiliary steam system can be operated in parallel or independently by opening and closing an auxiliary steam connecting door and a main pipe sectional door. When the unit operates independently, the auxiliary steam header is supplied with steam by the cold reheat steam of the unit.

The main function of the auxiliary steam header is to provide steam for the unit during starting and steam for the relevant equipment and the desulfurization system during normal operation, and the steam supply objects are as follows:

1) steam turbine shaft seal;

2) heating a water supply tank;

3) starting an air extractor;

4) boiler air heater

5) Heating an ash bucket of the electrostatic dust collector;

6) steam for a small steam engine;

7) auxiliary steam soot blowing of an air preheater;

8) denitration soot blowing;

9) a WGGH heat medium water auxiliary steam heater;

10) and G, blowing ash by a WGGH smoke cooler.

The number of times of starting and stopping of the unit is large, main users of auxiliary steam in the starting process are steam for a deaerator, continuous soot blowing of an air preheater, steam for heating the bottom of a boiler and starting air extraction of a condenser, and the duration of the continuous soot blowing of the deaerator and the air preheater and the heating of the bottom of the boiler is long in the starting process, so that the consumption of the auxiliary steam is large. When the annual starting and stopping times of the unit are increased, the auxiliary steam consumption is also increased.

The auxiliary steam consumption is counted by analyzing the auxiliary steam consumption under 3 conditions of cold state flushing, ignition cleaning and cold state starting, and the statistical conditions are shown in table 1.

The main user of auxiliary steam in the cold state flushing stage is heating of a deaerator. The temperature of cold state flushing water is generally 20-70 ℃, the water supply flow rate is 150-250 t/h, the deaerator is a main heating auxiliary steam user at the stage, and the actual steam consumption is about 15 t/h.

The boiler possesses the condition of igniteing this moment in the hot washing stage, and stove water is retrieved to the oxygen-eliminating device, and main auxiliary steam user order is: the steam amount for the plasma heater is 7.8t/h per month, the duration is 3h per month, the temperature of the primary hot air can be increased to 150 ℃, and the auxiliary steam consumption can be reduced to 5 t/h; continuously blowing the soot by an air preheater for about 5 t/h; the shaft seal is thrown in about 2.5 t/h.

After the boiler is ignited, the boiler enters a thermal state cleaning stage. Boiler plant design requires that the flow through the waterwall during the hot cleaning stage is not less than 30% BMCR. In actual operation, in order to ensure combustion in the initial ignition stage, the primary air temperature needs to be increased, steam for a heater, steam for a shaft seal and steam for soot blowing of an air preheater need to be ensured in the initial ignition stage, and the steam for a deaerator is properly reduced, which is the same as the hot washing operation. Meanwhile, in cold starting, the washing time is prolonged, the temperature of the water wall is gradually increased, the air heater is generally ignited for 3 hours, the steam inlet quantity can be gradually reduced, the auxiliary steam pressure is gradually increased, and the soot blowing effect and the water supply heating effect of the air preheater are improved.

According to the characteristics of the boiler, the actual feedwater flow range at the initial ignition stage is 220-320 t/h. The ignition to rush parameter takes approximately 5h, during which the plasma heater has switched to hot primary air and the heater stops with steam. The auxiliary steam user is used for blowing dust of the air preheater, heating the deaerator and sealing the shaft. In actual operation, the auxiliary steam consumption of 20t/h can completely meet the steam demand.

TABLE 1 statistical table of original auxiliary steam consumption

Referring to fig. 3, a power plant is taken as an example, the method of the present invention is adopted to perform an optimization design, and the arrangement and the operation mode of the auxiliary steam system are optimized on the basis of ensuring the safety and the stability of the auxiliary steam system according to the requirement of the auxiliary steam during the starting and the operation of the unit.

Firstly, according to the connection of the auxiliary steam system and the requirements of users, the steam parameters of each auxiliary steam user are counted, and the details are shown in table 2.

TABLE 2 auxiliary steam user steam usage parameter statistics

In the design of the new auxiliary steam system, the steam source of the high-auxiliary header is set to be cold reheat steam and auxiliary steam from an auxiliary steam connecting pipe, and the steam source of the low-pressure auxiliary steam header is auxiliary steam from the auxiliary steam connecting pipe and 5-section steam extraction. The steam sources of the auxiliary steam header are mutually standby.

And (3) combining the steam utilization parameter requirements of each auxiliary steam user in the table 2, distinguishing and treating each auxiliary steam user according to the steam utilization parameters of each user, and setting a high-pressure auxiliary steam system and a low-pressure auxiliary steam system, wherein the high-parameter user is connected in the high-pressure auxiliary steam system, and the low-parameter user is connected in the low-pressure auxiliary steam system.

The parameters of the high-pressure auxiliary steam header are set to be 1.2MPa and 300 ℃, and the parameters of the low-pressure auxiliary steam header are set to be 0.8MPa and 280 ℃. The high-pressure auxiliary steam header steam source is cold reheat steam and auxiliary steam from an auxiliary steam connecting pipe, when the cold reheat parameter can not meet the steam using requirement, machine-side auxiliary steam is used, and when the cold reheat steam parameter reaches a switching condition (not lower than 1.4 MPa), the cold reheat steam source is switched. The steam source of the low-pressure auxiliary steam header is the switching of the auxiliary steam from the auxiliary steam connecting pipe and the 5-section steam extraction, and the switching mode of the steam source of the high-pressure auxiliary steam header is also the same.

Auxiliary steam header steam sources are mutually standby

Accordingly, the high-parameter auxiliary steam header users are as follows:

1) starting a boiler to heat the bottom of the furnace;

2) the condenser starts to pump air.

The low-parameter auxiliary steam header users are as follows:

1) blowing ash by an air preheater;

2) heating a deaerator and a water tank;

3) steam for a steam turbine shaft seal system;

4) heating an ash bucket of the dust remover;

5) a boiler air heater;

6) denitration soot blowing;

7) steam for small turbines.

And after the system design is finished, carrying out economic analysis on the unit.

The income generated in the starting process of the newly designed system is the difference of the influence of the steam supply of the low auxiliary header and the steam supply of the cold reheat steam adopted by the original system on the economy of the unit.

According to the isentropic enthalpy drop calculation method, the unit operation economy analysis results are summarized in table 3, wherein the coal price is 700 yuan/t. Therefore, under the THA working condition, according to the isentropic enthalpy drop calculation method, in the original auxiliary steam system, the steam work is reduced by 23.71kJ/kg, the heat absorption capacity is changed by 9.90kJ/kg, and the efficiency of the device is reduced by 1.59 percent; the steam work of the optimized auxiliary steam system is reduced by 16.55kJ/kg, and the efficiency of the device is reduced by 1.36 percentage points. The optimized auxiliary steam system is compared with the original auxiliary steam system, the coal consumption reduction per year is calculated to be 1167.43t, and the converted income is 81.72 ten thousand yuan per year;

by implementing the invention, the problem of energy cascade utilization of energy level matching between a steam source point and an auxiliary steam user can be effectively solved, and the steam consumption are reduced under the condition of ensuring the production requirementThe purpose of improving the operation efficiency of the system is achieved, and the method has ten advantages for improving the safe and economic operation of the unitIt has important meaning.

TABLE 3 optimized auxiliary steam System operating economics analysis