阅读说明：本技术 一种燃气-蒸汽联合循环机组高温成膜保养方法 (High-temperature film forming maintenance method for gas-steam combined cycle unit ) 是由 谭旭南 潘志强 杨春艳 于 2019-11-15 设计创作，主要内容包括：本发明公开了一种燃气-蒸汽联合循环机组高温成膜保养方法,通过保养试剂及加药设备,通过主加药点和辅加药点,将保养试剂加入水汽系统,一次加药即可实现锅炉与汽轮机、凝汽器等设备全部保养,非常方便机组检修保养的需求,具有较好的保养效果,改变了过去保养效果差,不便于检修等弊端。此发明用于停炉保养方法领域。(The invention discloses a high-temperature film-forming maintenance method for a gas-steam combined cycle unit, which is characterized in that a maintenance reagent and a dosing device are added into a water vapor system through a main dosing point and an auxiliary dosing point, and the maintenance of a boiler, a steam turbine, a condenser and other devices can be realized through one-time dosing. The invention is used in the field of furnace shutdown maintenance methods.)

1. A high-temperature film forming maintenance method for a gas-steam combined cycle unit is characterized by comprising the following steps: the method comprises the following steps:

s1, checking the water vapor quality system of the thermodynamic equipment system within a week before maintenance, and preparing chemical supervision and analysis medicines and instruments two days before maintenance;

s2: preparing a maintenance reagent by using a high-temperature film-forming maintenance dosing device one day before blowing out, and designing a main dosing point and an auxiliary dosing point;

s3: 8h before the unit stops sliding, the boiler water temporarily closes the continuous blowdown door of the steam drum, the condensate fine treatment device is pushed out to operate, the normal operating water level of the steam drum is stabilized before adding chemicals into the system, and the pH value of the feed water and the boiler water is adjusted to be 9.6-9.8;

s4: the operation starts the shutdown operation of the unit with sliding parameters, the steam exhaust valve, the steam drum connecting and the fixed sewage exhaust valve of the steam drum, the superheater and other equipment are closed, and the water inlet and outlet valves of the chemical online instrument are closed;

s5: the contact value is long, the medicine is required to be added, the maintenance reagent is added after the medicine adding instruction is obtained, the main medicine adding point and the auxiliary medicine adding point are added with medicine simultaneously, and the medicine adding is finished within 1 hour;

s6: and after the dosing is finished, the unit continues to operate circularly, the main air temperature is controlled to be below 530 ℃, and when the maintenance reagent is uniformly distributed in the whole water vapor system, the unit continues to stop sliding.

2. The high-temperature film forming maintenance method of the gas-steam combined cycle unit according to claim 1, characterized in that: adjusting the furnace pH 3-5 days before the scheduled furnace shut down and adding PO in the furnace water before step S2₄ ^3-The content is reduced to less than 0.3 mg/L.

3. The high-temperature film forming maintenance method of the gas-steam combined cycle unit according to claim 2, characterized in that: after the solution in the solution tank is used, the solution tank is washed once by demineralized water, then NaOH solution is prepared by analytically pure NaOH, then the NaOH solution is added by switching the medium-high pressure furnace water, the furnace water is increased for pollution discharge, and the furnace water PO is reduced₄ ^3-Controlling the pH value of furnace water.

4. The high-temperature film forming maintenance method of the gas-steam combined cycle unit according to claim 1, characterized in that: in step S3, the feed water and furnace water are adjusted to pH 9.6-9.8 by adding ammonia to the feed water or NaOH to the furnace water.

5. The high-temperature film forming maintenance method of the gas-steam combined cycle unit according to claim 1, characterized in that: in step S5, during the dosing period, the steam temperature parameter is concerned at the running time and recorded once in 5min, the boiler water vapor quality is concerned at the chemical time, data is recorded once in 5min, sampling is carried out every 0.5h from 30min before dosing to 30min after dosing, and the hydrogen conductivity, the formate, the acetate and the Cl are analyzed^-Conventional conductivity, pH, pNa, Cu, Fe, PO₄ ^3-And (5) data inspection of the dosing effect.

6. The high-temperature film forming maintenance method of the gas-steam combined cycle unit according to claim 1, characterized in that: in step S2, the condenser of the unit is set as a main dosing point, and the chemical is sucked into the condenser by using the condenser vacuum; the high-medium pressure water supply system of the unit is set as an auxiliary dosing point.

7. The high-temperature film forming maintenance method of the gas-steam combined cycle unit as claimed in claim 6, wherein: in step S5, the main dosing point controls the liquid level of the dosing tank to be above the liquid level of 10cm when dosing, and adopts the mode that the edge of the dosing tank adds the condensation water and adds the medicine, and after the solution tank and the dosing pipeline are washed clean, when the liquid level of the dosing tank drops to the liquid level of 10cm, the dosing tank outlet valve K1 is closed, the condenser is used for a primary valve and a secondary valve of dosing, and gas leakage is confirmed, and the main dosing point dosing operation is finished.

8. The high-temperature film forming maintenance method of the gas-steam combined cycle unit according to claim 7, characterized in that: in step S5, when adding the chemical, the maintenance reagent is first added into the octadecylamine adding device, the chemical is added, the chemical adding door is opened, the chemical adding pump is started to add the chemical to the outlet of the high pressure water supply pump of the high pressure water supply system, the outlet pressure is adjusted to 1.8-2.5MPa, when all the maintenance reagent is added, the metering tank, the chemical adding pump and the chemical adding pipeline are continuously flushed, and finally the chemical adding door is closed.

9. The high-temperature film forming maintenance method of the gas-steam combined cycle unit according to claim 1, characterized in that: the maintenance reagent is a film-forming rust inhibitor.

10. The high-temperature film forming maintenance method of the gas-steam combined cycle unit according to claim 1, characterized in that: the chemical analysis supervision analysis medicine and instruments comprise a pH meter calibration and standard reagent, a conductivity meter, a sodium meter, and a reagent and instrument for measuring silicon content, phosphate radical content, furnace water alkalinity, trace iron and low-content chlorine radical.

Technical Field

The invention relates to the field of furnace shutdown maintenance methods, in particular to a high-temperature film forming maintenance method for a gas-steam combined cycle unit.

Background

In order to prevent thermal equipment such as a thermal power generator boiler, a steam turbine, a condenser, a heater and the like from generating corrosion during the overhaul and the shutdown, and causing damage to a unit, the power industry standard stipulates that a proper shutdown maintenance method should be adopted during the use of the unit. At present, the general methods are dry maintenance and wet maintenance, wherein the dry maintenance mainly comprises waste heat drying, a hot air drying method and the like, and the wet maintenance mainly comprises an ammonia water method, a steam pressure method and the like.

The dry maintenance requires that the inside of a water vapor system is dry, external water vapor is prevented from entering in the maintenance process, the condensation on the metal surface is prevented, the structure of an internal system is complex in the practical application process, partial pipelines cannot be dried, the external water vapor enters the system in the maintenance process to cause the condensation on the local metal surface, the condition of local accelerated corrosion is formed, and finally the maintenance effect is poor.

Wet process maintenance adopts high concentration aqueous ammonia (ammonia-diamine) to soak usually, and the maintenance mode is united in the maintenance of nitrogen filling maintenance is adopted to the steam side, and this scheme is fit for the maintenance of unit standby condition, can not carry out the inside overhaul, and the maintenance liquid discharges and causes polluted environment easily simultaneously, perhaps increases treatment cost etc. not enough.

Therefore, a maintenance method suitable for the operation characteristics of the gas-steam combined cycle unit needs to be explored, and the shutdown maintenance effect of the unit is improved.

Disclosure of Invention

The invention aims to provide a high-temperature film forming maintenance method for a gas-steam combined cycle unit with a good maintenance effect.

The technical scheme adopted by the invention is as follows:

a high-temperature film forming maintenance method for a gas-steam combined cycle unit comprises the following steps:

s1, checking the water vapor quality system of the thermodynamic equipment system within a week before maintenance, and preparing chemical supervision and analysis medicines and instruments two days before maintenance;

s2: preparing a maintenance reagent by using a high-temperature film-forming maintenance dosing device one day before blowing out, and designing a main dosing point and an auxiliary dosing point;

s3: 8h before the unit stops sliding, the boiler water temporarily closes the continuous blowdown door of the steam drum, the condensate fine treatment device is pushed out to operate, the normal operating water level of the steam drum is stabilized before adding chemicals into the system, and the pH value of the feed water and the boiler water is adjusted to be 9.6-9.8;

s4: the operation starts the shutdown operation of the unit with sliding parameters, the steam exhaust valve, the steam drum connecting and the fixed sewage exhaust valve of the steam drum, the superheater and other equipment are closed, and the water inlet and outlet valves of the chemical online instrument are closed;

s5: the contact value is long, the medicine is required to be added, the maintenance reagent is added after the medicine adding instruction is obtained, the main medicine adding point and the auxiliary medicine adding point are added with medicine simultaneously, and the medicine adding is finished within 1 hour;

s6: and after the dosing is finished, the unit continues to operate circularly, the main air temperature is controlled to be below 530 ℃, and when the maintenance reagent is uniformly distributed in the whole water vapor system, the unit continues to stop sliding.

As a further improvement of the technical scheme of the invention, before the step S2, the pH value of the furnace is adjusted 3-5 days before the furnace is scheduled to be stopped, and PO in the furnace water is added₄ ^3-The content is reduced to less than 0.3 mg/L.

As a further improvement of the technical scheme of the invention, after the phosphate solution in the phosphate solution tank is used, the phosphate solution tank is washed once with demineralized water, then analytically pure NaOH is used for preparing NaOH solution, then middle-high pressure furnace water is switched to be added with NaOH solution, the furnace water pollution discharge is increased, and the furnace water PO is reduced₄ ^3-Controlling the pH value of furnace water.

As a further improvement of the technical scheme of the invention, in step S3, the pH value of the feed water and the furnace water is adjusted to be between 9.6 and 9.8 by adding ammonia into the feed water or adding NaOH into the furnace water.

Further as an improvement of the technical scheme of the invention, in step S5, during the dosing period, the operation time focuses on steam temperature parameters and records once in 5min, the chemical time focuses on the quality of water vapor of the boiler, data is recorded once in 5min, sampling is carried out every 0.5h from 30min before dosing to 30min after dosing, and hydrogen conductivity, formate, acetate and Cl are analyzed^-Conventional conductivity, pH, pNa, Cu, Fe, PO₄ ^3-And (5) data inspection of the dosing effect.

As a further improvement of the technical solution of the present invention, in step S2, a condenser of the unit is set as a main dosing point, and a chemical is sucked into the condenser by using condenser vacuum; the high-medium pressure water supply system of the unit is set as an auxiliary dosing point.

In step S5, the liquid level of the dosing tank is controlled to be above 10cm when the main dosing point adds medicine, and the mode of adding condensed water to the inner side of the dosing tank and adding medicine is adopted, after the solution tank and the dosing pipeline are washed clean and the liquid level of the dosing tank drops to 10cm, the outlet valve K1 of the dosing tank is closed, the primary dosing valve and the secondary dosing valve of the condenser are closed, no air leakage is confirmed, and the dosing operation of the main dosing point is finished.

Further as an improvement of the technical scheme of the invention, in step S5, when adding the chemical at the auxiliary chemical adding point, the maintenance reagent is firstly added into the octadecylamine chemical adding device, the stirring is carried out, the chemical adding door is opened, the chemical adding pump is started to add the chemical to the outlet of the high-pressure water feeding pump of the high-pressure water feeding system, the outlet pressure is adjusted to be 1.8-2.5MPa, after all the maintenance reagent is added, the metering tank, the chemical adding pump and the chemical adding pipeline are continuously flushed, then the chemical adding door is closed, and the long-term chemical adding work is reported to be finished.

As a further improvement of the technical scheme of the invention, the maintenance reagent is a film-forming antirust agent.

Further as an improvement of the technical scheme of the invention, the chemical analysis supervision analysis drugs and instruments comprise a pH meter calibration and standard reagent, a conductivity meter, a sodium meter, and a reagent and instrument for measuring silicon content, phosphate content, furnace water alkalinity, trace iron and low-content chlorine.

The invention has the beneficial effects that: according to the high-temperature film forming maintenance method for the gas-steam combined cycle unit, the maintenance reagent is added into the water vapor system through the maintenance reagent and the dosing equipment and through the main dosing point and the auxiliary dosing point, and the whole maintenance of the boiler, the steam turbine, the condenser and other equipment can be realized through once dosing, so that the unit maintenance requirement is very convenient, the maintenance effect is good, the defects of poor past maintenance effect, inconvenience in maintenance and the like are overcome.

Drawings

The invention will be further described with reference to the accompanying drawings in which:

FIG. 1 is a schematic view of a main dosing point according to an embodiment of the present invention;

FIG. 2 is a schematic view of the main dosing point according to the embodiment of the present invention;

FIG. 3 is a schematic view of an auxiliary dosing point according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

A high-temperature film forming maintenance method for a gas-steam combined cycle unit comprises the following steps:

s1: carry out the systematic check of thermodynamic device system steam quality in a week before the maintenance, prepare chemical supervision analysis medicine and instrument two days ago, mainly include: a pH meter calibration and standard reagent, a conductivity meter, a sodium meter, a reagent for measuring silicon content, phosphate radical content, furnace water alkalinity, trace iron and low-content chlorine radical and a meter, and effective supervision during the period of non-use is ensured;

s2: in order to improve the film forming quality, PO in the furnace water is added as much as possible₄ ^3-The concentration is reduced to below 0.3 mg/L. NaOH needs to be used to replace phosphate to adjust the furnace water pH 3-5 days before planned furnace shutdown. The method comprises the following specific steps: preparing in advance to use the phosphate solution tank solution, washing the phosphate solution tank solution once by using desalted water, and preparing NaOH solution by using 2kg of analytically pure NaOH; then switching the medium-high pressure furnace water and adding NaOH solution, properly increasing the furnace water pollution discharge and reducing the furnace water PO₄ ^3-Content and controlling the pH value of furnace water. The automatic control parameter settings are accordingly set according to actual measurements.

S3: preparing a maintenance reagent by using a special high-temperature film-forming maintenance dosing device one day before stopping a furnace, designing a main dosing point and an auxiliary dosing point by one unit, taking a condenser 10 as the main dosing point, and vacuumizing the condenser 10 by using the condenser 10; the high-pressure water supply system 50 and the medium-pressure water supply system 40 are auxiliary dosing points, and are added into the inlet of the water supply pump through the chemical dosing system and the octadecylamine dosing device 30, 150kg of high-temperature film-forming antirust agent is needed at the same time, wherein the main dosing point is 100kg, and the auxiliary dosing point is 50 kg. The design of the main dosing point and the auxiliary dosing point has the advantages that: the main point of adding medicine begins to add medicine from the source, guarantees that entire system maintains reagent concentration and maintenance effect basically, and the design of supplementary point of adding medicine is in middling pressure water supply system 40 and high-pressure water supply system 50, is in whole steam circulation system intermediate link, mainly remedies the maintenance reagent and progressively consumes maintenance reagent concentration problem of putting on the shelf through preceding low pressure system for maintenance reagent distributes more evenly in entire system, improves the maintenance effect.

S4: and 8h before the unit stops sliding, the boiler water temporarily closes the steam drum continuous blowdown door, and the condensed water fine treatment device is withdrawn from operation. Before adding medicine into the system, the normal operation water level of the steam drum is stabilized, and the pH value of the feed water and the furnace water is between 9.6 and 9.8 by adjusting the feed water and adding ammonia or adding sodium hydroxide into the furnace water.

S5: and (4) starting unit sliding parameter shutdown operation, stopping until the unit sliding is stopped to proper thermal parameters (the main steam temperature and the reheating steam diffuse temperature are reduced to 530 ℃, the unit load is about 240MW), and closing exhaust valves of equipment such as a steam drum, a superheater and the like, and a steam drum connecting and fixed exhaust valve. Closing chemical on-line meters such as a silicon meter, a sodium meter, a phosphorus meter, a positive conductivity meter and the like and water inlet and outlet valves, and only keeping the pH meter and the specific conductivity meter to monitor the water quality.

S6: and (4) the connection value is long, and the chemical adding is requested, after the chemical adding instruction is obtained, the film-forming anti-corrosion liquid medicine is added according to the following steps. The main dosing point and the auxiliary dosing point are dosed simultaneously, and the dosing is finished within about 1 hour.

S7: after the dosing is finished, the unit continuously and circularly operates for about 2.5 hours, the temperature of the main steam is controlled to be below 530 ℃, so that the maintenance agent is uniformly distributed in the whole water vapor system, and then the unit continuously slides and stops.

S8: during the dosing period, the steam temperature parameter is concerned at the running time, the recording is once carried out for 5min, the boiler water vapor quality is concerned at the chemical time, the data is recorded once for 5min, the sampling is carried out every 0.5h from 30min before dosing to 30min after dosing, and the hydrogen conductivity, the formate, the acetate, the chloride, the conventional conductivity, the pH value, the pNa, the Cu, the Fe and the PO are analyzed₄ ^3-Data to verify dosing effect.

The method utilizes the excellent water vapor distribution coefficient of the high-temperature film-forming maintenance reagent, adds the water vapor into a condensed water and water supply system, enters a boiler, finally volatilizes into steam, and enters a subsequent superheater, a steam turbine condenser and other systems along with the circulation of the system, so that the whole water vapor system is filled with the high-temperature film-forming maintenance reagent with certain concentration, and finally adheres to the metal surface of the water vapor system, a layer of hydrophobic protective film is generated on the technical surface when the machine is stopped, the water vapor is isolated, the maintenance is realized, and the comprehensive maintenance of the water vapor system can be realized by adding the agent once. Meanwhile, the high-temperature film-forming maintenance reagent is easy to decompose when exceeding the decomposition temperature, so that the method has the advantages of less waste liquid, easy treatment and the like, can be completely suitable for the operating characteristics of a gas-steam combined cycle unit, and improves the shutdown maintenance effect of the unit.

Referring to fig. 1 to 3, the main dosing point dosing method is as follows:

1. the high-temperature film-forming rust inhibitor dilution method comprises the following steps: a. preparation before dosing: pouring 50kg of film-forming rust inhibitor into a solution tank, adding condensed water (30-50 ℃) to dilute to full scale (about 500 kg); washing the residual liquid medicine in the medicine barrel into a solution box by using condensed water (30-50 ℃); the stirring is started to prevent precipitation. b. Adding a medicament: opening a primary dosing valve and a secondary dosing valve of a condenser 10, adjusting the opening degree of an adjusting valve K1 at the outlet of an octadecylamine dosing device 30, adding a medicament into condensed water at the flow rate of about 16.7kg/min (controlled according to the liquid level descending speed), adding 25kg (one barrel) of film-forming rust inhibitor into a solution tank every 15min after dosing is started, continuously adding condensed water (30-50 ℃) for dilution to maintain the full scale of the liquid scale of the solution tank, and stopping the dilution of the condensed water after 1 barrel of the film-forming rust inhibitor is added into the solution tank (correspondingly adding 30 min). The dosing speed is continuously controlled to ensure that the residual liquid medicine (500kg) in the solution tank completely flows out within about 30 min. Controlling the control value of all dosing time for 60 min; the solution tank and the dosing pipeline are flushed with condensed water (30-50 ℃).

2. When in dosing, the liquid level of the dosing tank 20 is controlled to be above a low liquid level (10cm liquid level), so that air is prevented from being sucked into the condenser to influence the vacuum of the unit;

3. when the medicine is added at a low liquid level, a mode of adding condensed water to the inner side of the medicine adding box 20 and adding medicine can be adopted;

4. after the solution tank and the dosing pipeline are washed clean, when the liquid level of the dosing tank 20 is reduced to a low liquid level (10cm liquid level), an outlet valve K1 of the dosing tank 20 is closed, the dosing primary valve and the dosing secondary valve of the condenser 10 are closed, air leakage is confirmed, and dosing work is finished.

An auxiliary dosing point dosing method comprises the following steps:

1. firstly, 50kg of high-temperature film forming liquid is mixed into an octadecylamine dosing device 30, diluted by 2 times by demineralized water if necessary, and after uniform mixing, a dosing door is opened, and a dosing pump is started to dose medicine to the outlet of a high-pressure water feeding pump;

2. adjusting the outlet pressure to about 1.8-2.5MPa, and pressing down the air release valve with force if the pressure of the pump cannot be increased);

3. and after all the anti-corrosion liquid medicine is added, adding a small amount of demineralized water, continuously flushing the metering tank, the dosing pump and the dosing pipeline, closing the dosing door after the metering tank, the dosing pump and the dosing pipeline are flushed, and reporting the running value and ending the dosing work.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.