CN103646176B - The comprehensive calculation method of energy-saving effect after turbine steam seal transformation - Google Patents

Abstract

The invention discloses the comprehensive calculation method of energy-saving effect after a kind of turbine steam seal is transformed, concretely comprise the following steps: arrange pressure, temperature, flow, electrical power test point in Steam Turbine therrmodynamic system；Calculate feedwater flow, main steam flow, cold reheated steam flow and reheated steam flow；Four: calculate unit height, intermediate pressure cylinder balancing frame shaft gland steam leakage；Measure height, intermediate pressure cylinder shaft gland steam leakage, low pressure cylinder shaft seal throttle flow, low pressure shaft seal pressure, through the temperature rise of condensate of gland heater；Calculate unit test heat consumption rate, the heat consumption rate after parameters revision；Each for steam turbine parameter is compared with design value before packing transformation, evaluates the energy-saving effect of turbine steam seal transformation.This method passes through Thermal Performance Test of Steam Turbine, tests therrmodynamic system parameter, provides energy-saving effect evaluation and analysis method after turbine steam seal transformation, and method advantages of simple, the result calculated is more accurate.

Description

Comprehensive Calculation Method for Energy-saving Effect of Steam Turbine Seal Reformation

technical field

The invention relates to the field of steam turbines, in particular to a comprehensive calculation method for the energy-saving effect of steam turbine seal reformation.

Background technique

The most commonly used steam seal for modern steam turbines is still the comb structure. In recent years, with the development of technology, many new types of steam seals have been introduced from abroad. The typical ones are: honeycomb steam seal, brush type steam seal, adjustable Gas seal, contact type gas seal, side gear gas seal, etc. Although these steam seals have different structural forms, the designer's guiding ideology is to increase the number of teeth, reduce the gap, and increase the resistance to improve the sealing effect and reduce the loss caused by steam leakage. The new type of steam seal is currently widely used in steam turbines. The steam seal of the flow part and the steam seal of the shaft end are being upgraded.

Steam turbine steam seal renovation can significantly improve the economic indicators of the steam turbine unit. When judging and evaluating the steam turbine steam seal renovation effect, the most commonly used method is based on the improvement of the efficiency of each cylinder of the steam turbine and the reduction of the heat consumption rate of the unit. However, there are many factors that affect the efficiency and heat consumption rate of the steam turbine cylinder, including: (1) the transformation of the flow part of the steam turbine; (2) the transformation of the steam seal and shaft seal of the steam turbine; (3) the fouling and descaling of the flow part; (4) System internal and external leakage, etc. Due to the different models of the unit, the influence of steam leakage from the steam seal and shaft seal on the performance indicators of the unit is not the same. Sometimes, the improvement of the cylinder efficiency and heat consumption rate is not obvious after the steam seal of the steam turbine is modified, and the flow part of the unit is also included. The effects of overhaul such as descaling and internal and external leakage control of the system, so the improvement of cylinder efficiency and heat rate cannot be used to comprehensively analyze the effect of steam turbine seal renovation.

Contents of the invention

The purpose of the present invention is to solve the above problems, and proposes a comprehensive calculation method for the energy-saving effect of steam turbine seal reformation

In order to achieve the above object, the present invention adopts the following technical solutions:

A comprehensive calculation method for the energy-saving effect of steam turbine steam seal reconstruction, comprising the following steps:

Step 1: Arrange several test points for pressure, temperature and flow in the thermal system of the steam turbine unit;

Step 2: Measure the leakage steam flow rate of the front and rear shaft seals of the high-pressure cylinder and medium-pressure cylinder, the steam intake flow rate of the low-pressure cylinder shaft seal, the parameters of the steam turbine monitoring section, the steam intake parameters of the shaft seal heater, and the temperature rise of condensate passing through the shaft seal heater ;

Step 3: Carry out the test of the variable steam temperature of the steam turbine, measure and calculate the steam leakage percentage of the balance plate between the high pressure cylinder and the medium pressure cylinder of the symmetrical arrangement structure;

Step 4: Calculate the actual efficiency of the high-pressure cylinder, the nominal efficiency of the medium-pressure cylinder, and the actual efficiency of the low-pressure cylinder of the steam turbine unit;

Step 5: Calculate the test heat rate of the steam turbine unit, and calculate the heat rate after the parameter correction of the steam turbine unit;

Step 6: Set the parameters of the steam turbine monitoring section, the steam leakage of the balance disc between the high and medium pressure cylinders, the steam leakage of the front and rear shaft seals of the high and medium pressure cylinders, the steam intake of the low pressure cylinder shaft seal, the steam supply pressure of the low pressure cylinder shaft seal, and the heating of the shaft seal The inlet steam pressure, inlet steam temperature and condensate temperature rise, the actual efficiency of the high-pressure cylinder, the actual efficiency of the medium-pressure cylinder, the actual efficiency of the low-pressure cylinder, and the heat consumption rate after the unit parameter correction are respectively compared with the design values of the manufacturer before the steam seal transformation Comparing and comprehensively judging the energy-saving effect of steam turbine seal renovation according to the comparison results;

The concrete measuring method of described step 2 is:

(1) Measure the leakage steam pressure P ₁ of the shaft seal of the high-pressure cylinder and the medium-pressure cylinder respectively, the working temperature t ₁ of the shaft seal leakage flow throttling device before and after the high-pressure and medium-pressure cylinder, the steam supply pressure P ₂ of the shaft seal of the low-pressure cylinder, and the pressure of the low-pressure cylinder Working temperature t ₂ of cylinder shaft seal inlet steam flow throttling device, steam turbine monitoring section pressure P ₃ , steam turbine monitoring section temperature t ₃ , shaft seal heater inlet steam pressure P ₄ , shaft seal heater inlet steam temperature t ₄ , shaft seal heater Seal heater inlet water temperature t ₅ , shaft seal heater outlet water temperature t ₆ ;

( ₂ ) Utilize known ΔT=t6 _- t5 to calculate the condensate temperature rise through the shaft seal heater, wherein, _t5 is the inlet water temperature of the shaft seal heater, and t6 is the outlet water temperature of the shaft seal heater _;

(3) Measure the steam leakage density ρ ₁ of the front and rear shaft seals of the high and medium pressure cylinders and the steam intake density ρ ₂ of the low pressure cylinder shaft seals;

(4) Calculate the opening diameter d _t1 of the leakage steam flow throttling device of the front and rear shaft seals of the high and medium pressure cylinders and the opening diameter d _t2 of the steam inlet flow throttling device of the shaft seal of the low pressure cylinder respectively; the specific formula is:

d _t1 =d ₂₀₁ ×λ _d1 ×(t ₁ -20);

d _t2 =d ₂₀₂ ×λ _d2 ×(t ₂ -20);

Among them, d ₂₀₁ is the opening diameter of the shaft seal leakage flow throttling device at the front and rear shaft seals of high and medium pressure cylinders at the design temperature of 20°C, and λ _d1 is the linear expansion of the shaft seal leakage flow throttling device of the front and rear shaft seals of high and medium pressure cylinders coefficient, t ₁ is the working temperature of the shaft seal leakage flow throttling device at the front and rear of the high and medium pressure cylinders; d ₂₀₂ is the opening diameter of the shaft seal inlet steam flow throttling device of the low pressure cylinder at the design temperature of 20°C, λ _d2 is The linear expansion coefficient of the low-pressure cylinder shaft seal inlet steam flow throttling device, _t2 is the working temperature of the low-pressure cylinder shaft seal inlet steam flow throttling device;

(5) Calculate the leakage steam flow G _zf of the front and rear shaft seals of the high and medium pressure cylinders and the steam intake flow G _dzf of the shaft seals of the low pressure cylinder respectively. The specific formula is:

G _zf ＝0.126446×α ₁ ×d _t1 ² ×ε ₁ ×(ΔP ₁ ×ρ ₁ ) ^1/2 ;

G _dzf ＝0.126446×α ₂ ×d _t2 ² ×ε ₂ ×(ΔP ₂ ×ρ ₂ ) ^1/2 ;

Among them, α1 is the flow coefficient _of the shaft seal leakage flow throttling device before and after the high and medium pressure cylinders, which is _a known quantity, and ΔP1 is the measured flow rate of the shaft seal leakage flow throttling device at the front and rear of the high and medium pressure cylinders during the test The differential pressure, unit kPa, ε ₁ is the expansion coefficient of the measured medium, which is a known quantity; α ₂ is the flow coefficient of the low-pressure cylinder front and rear shaft seal leakage flow throttling device, which is a known quantity, and ΔP ₂ is a known quantity during the test The differential pressure of the flow rate measured by the leakage steam flow throttling device of the front and rear shaft seals of the low-pressure cylinder, the unit is kPa, and _ε2 is the expansion coefficient of the measured medium, which is a known quantity.

The concrete measuring method of described step 3 is:

(1) Carry out two working condition tests of reducing the main steam temperature of the steam turbine and increasing the reheating temperature, and increasing the main steam temperature of the steam turbine and reducing the reheating temperature, so that the deviation between the main steam temperature and the reheating temperature is 20-30°C, and other parameters constant;

(2) Measure the inlet steam enthalpy i _ms of the high-pressure cylinder, the inlet steam enthalpy of the medium-pressure cylinder i _rh , the final feed water enthalpy i _{fw w} , the exhaust steam enthalpy of the high-pressure cylinder i _ch , the desuperheating water enthalpy of the superheater i _ss , and the desuperheating water of the reheater Enthalpy i _rs , #1 high-addition steam enthalpy i _n1 , #1 high-addition steam enthalpy i _s1 , #2 high-addition steam enthalpy i _n2 , #2 high-addition steam enthalpy i _s2 , #3 high-addition steam enthalpy i _n3 、#3 high water enthalpy i _s3 、#1 high water enthalpy i ₁₁ 、#1 high water enthalpy i ₁₂ 、#2 high water enthalpy i ₂₁ 、#2 high water enthalpy i ₂₂ 、# 3 high water enthalpy i ₃₁ , #3 high water enthalpy i ₃₂ and generator active power Pe;

(3) Measure the feedwater flow G _fw before the boiler economizer inlet, the equivalent flow G _b1 of boiler drum water level change, the superheater desuperheating water flow G _ss , and the reheater desuperheating water flow G _rs ;

(4) Calculate the inlet steam flow rate G _e1 of #1, the inlet steam flow rate G _e2 of #2 and the inlet steam flow rate G _e3 of #3 respectively. The specific calculation formulas are as follows:

G _e1 =G _fw ×(i ₁₂ -i ₁₁ )/(i _n1 -i _s1 );

G _e2 ＝[G _fw ×(i ₂₂ -i ₂₁ )-G _e1 ×(i _s1 -i _s2 )]/(i _n2 -i _s2 );

G _e3 ＝[G _fw ×(i ₃₂ -i ₃₁ )-(G _e1 +G _e2 )×(i _s2 -i _s3 )]/(i _n3 -i _s3 );

Among them, G _fw is the feed water flow rate, i ₁₁ is #1 high feed water enthalpy, i ₁₂ is #1 high feed water enthalpy, i ₂₁ is #2 high feed water enthalpy, i ₂₂ is #2 high feed water enthalpy, i ₃₁ is the water enthalpy added to #3 high, i ₃₂ is the water enthalpy added to #3 high, i _s1 is the hydrophobic enthalpy added to #1 high, i _s2 is the hydrophobic enthalpy added to #2 high, and i _s3 is the hydrophobic enthalpy added to #3 high , i _n1 is the inlet steam enthalpy of #1, i _n2 is the inlet steam enthalpy of #2, and i _n3 is the inlet steam enthalpy of #3;

(5) Calculate the main steam flow G _ms , the cold reheat steam flow G _ch and the reheat steam flow G _rh respectively, and the specific calculation formulas are as follows:

G _ms = G _fw +G _b1 +G _ss ;

G _ch =G _ms -G _g1 -G _e1 -G _e2 -G _e3 ;

G _rh =G _ch +G _rs ;

Among them, G _fw is the feed water flow rate, G _b1 is the equivalent flow rate of boiler drum water level change, G _ss is the superheater desuperheating water flow rate; G _ms is the main steam flow rate, and G _g1 is the steam leakage amount of the high pressure cylinder door rod and front and rear shaft seals The sum is given by the thermodynamic characteristic book of the manufacturer, G _e1 , G _e2 and G _e3 are the #1 high-inlet steam flow, #2 high-inlet steam flow and #3 high-inlet steam flow respectively; G _rs is Reheater desuperheating water flow;

(6) Measure the steam leakage enthalpy i _leak of the shaft seal between high and medium pressure cylinders; measure the inlet steam pressure P _rh of the medium pressure cylinder, measure the exhaust steam pressure P _ich of the medium pressure cylinder, and measure the exhaust steam enthalpy i _ich of the medium pressure cylinder;

(7) Set the steam leakage G _leak between high and medium pressure cylinders as a percentage of the main steam flow G _ms N to be 0, 2, 4, 6, 8, and 10 respectively, and calculate the steam leakage between high and high pressure cylinders The enthalpy value i _mix after hot steam mixing, the specific calculation formula is:

i _mix =[G _rh ×i _ich +i _leak ×N×G _ms ]/(G _rh +N×G _ms );

Among them, G _rh is the reheat steam flow rate, i _leak is the steam leakage enthalpy of the shaft seal between high and medium pressure cylinders, and i _ich is the exhaust steam enthalpy of the medium pressure cylinder;

(8) Calculate the actual enthalpy drop H _i of the reheat steam in the medium pressure cylinder, the specific formula is:

H _i = i _mix - i _ich ;

Among them, i _mix is the enthalpy value of the steam leakage of the shaft seal between the high and medium pressure cylinders mixed with the reheated steam, and i _ich is the exhaust steam enthalpy of the medium pressure cylinder;

(9) Calculate the isentropic enthalpy drop H ₀ of the steam in the medium-pressure cylinder by using the measured pressure P _rh of the inlet steam of the medium-pressure cylinder, the enthalpy of inlet steam i _rh of the medium-pressure cylinder and the exhaust pressure P _ich of the medium-pressure cylinder;

(10) Calculate the actual efficiency η _IP of the medium pressure cylinder, the calculation formula is:

η _IP =H _i /H ₀ ;

Among them, H _i is the actual enthalpy drop of steam in the medium pressure cylinder, H0 is the isentropic enthalpy drop of steam in the medium pressure cylinder _;

(11) Utilize the calculation method described in step (2)-step (10) to calculate respectively and draw the medium-pressure cylinder efficiency _ηIP and the medium-pressure cylinder interaxial axis in the two variable steam temperature working conditions experiments of the steam turbine in step (1) The relationship curve of seal leakage steam percentage N, the value of the intersection point N in the two relationship curves obtained is the actual steam turbine unit's actual high and medium pressure inter-cylinder shaft seal leakage percentage.

The concrete method of described step 4 is:

(1) Measure the inlet steam pressure P _ms of the high-pressure _cylinder , the inlet steam temperature of the high-pressure cylinder t _ms , and the inlet steam _enthalpy of the high-pressure cylinder im _ms ; i _ch ; measure the inlet steam pressure P _rh , the inlet steam temperature t _rh of the intermediate pressure cylinder, and the inlet steam enthalpy i _rh of the intermediate pressure cylinder; measure the exhaust steam pressure P _ich of the intermediate pressure cylinder, the exhaust steam temperature of the intermediate pressure cylinder t _ich , Medium pressure cylinder exhaust enthalpy i _ich ; measure low pressure cylinder inlet steam pressure P _lp , low pressure cylinder inlet steam temperature t _Lp , low pressure cylinder inlet steam enthalpy i _lp ; measure low pressure cylinder exhaust pressure P _ex ;

(2) Calculate the actual enthalpy drop H _HP of steam in the high-pressure cylinder and the actual enthalpy drop H _IP of steam in the medium-pressure cylinder respectively. The specific calculation formula is as follows:

H _HP = i _ms - i _ch ;

H _IP = i _rh - i _ich ;

Among them, i _ms is the steam inlet enthalpy of the high-pressure cylinder, i _ch is the exhaust steam enthalpy of the high-pressure cylinder, i _rh is the steam inlet enthalpy of the medium-pressure cylinder, and i _ich is the exhaust steam enthalpy of the medium-pressure cylinder;

(3) Calculate the isentropic enthalpy drop H _OHP of steam in the high-pressure cylinder by using the measured high-pressure cylinder inlet steam pressure P _ms , high-pressure cylinder inlet steam enthalpy im _ms and high-pressure cylinder exhaust pressure P _ch ; Calculate the isentropic enthalpy drop H _OIP of the steam in the medium pressure cylinder using the steam pressure P _rh , the inlet steam _enthalpy i _rh of the medium pressure cylinder and the exhaust pressure P _ich of the medium pressure cylinder; Inlet steam enthalpy i _lp and low pressure cylinder exhaust pressure P _ex calculate steam calculation entropy enthalpy drop H _OLP in low pressure cylinder;

(4) Calculating the exhaust enthalpy i _ex of the low-pressure cylinder by using the steam turbine energy balance method;

(5) Calculate the actual enthalpy drop H _LP of steam in the low pressure cylinder, the calculation formula is: H _LP =i _lp -i _ex ;

(6) Calculate the actual efficiency η _HP of the high-pressure cylinder, the nominal efficiency η _IPM of the medium-pressure cylinder, and the efficiency η _LP of the low-pressure cylinder respectively. The specific calculation formulas are as follows:

_ηHP = _HHP / _HOHP ;

_ηIPM = _HIP / _HOIP ;

η _LP = H _LP /H _OLP ;

Among them, H _HP is the actual enthalpy drop of steam in the high-pressure cylinder, H _OHP is the isentropic enthalpy drop of steam in the high-pressure cylinder, H _IP is the nominal enthalpy drop of steam in the medium-pressure cylinder, and _HOIP is the steam in the medium-pressure cylinder H _LP is the actual enthalpy drop of steam in the low-pressure cylinder, and H _OLP is the isentropic enthalpy drop in the low-pressure cylinder.

The concrete steps of described step five are:

(1) The computer group test heat consumption rate H _t , the calculation formula is:

H _t ＝((G _ms -G _ss )×(i _ms -i _fw )+G _ch ×(i _rh -i _ch )+G _ss ×(i _ms -i _ss )+G _rs ×(i _rh -i _rs ))/Pe;

Among them, G _ms is the main steam flow rate, G _ss is the desuperheating water flow rate of the superheater, i _ms is the inlet steam enthalpy of the high pressure cylinder, i _fw is the final feed water enthalpy, G _ch is the cold reheat steam flow rate, and i _rh is the inlet steam flow rate of the medium pressure cylinder steam enthalpy, i _ch is the exhaust steam enthalpy of the high pressure cylinder, _iss is the superheater desuperheating water enthalpy, G _rs is the reheater desuperheating water flow rate, i _rs is the reheater desuperheating water enthalpy, P _e is the active power of the generator;

(2) The heat consumption rate H _r corrected by the computer group, the calculation formula is:

H _r ＝H _t /(C ₁ ×C ₂ ×C ₃ ×C ₄ ×C ₅ )

Among them, C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ are all known parameters provided by the manufacturer, which are the main steam pressure, main steam temperature, reheat steam pressure loss, reheat steam temperature and low-pressure cylinder row Correction factor for steam pressure to heat rate.

The beneficial effects of the present invention are:

(1) For the steam turbine unit with steam seal reformation, the high, medium and low pressure cylinder efficiencies and unit heat consumption rate, as well as the high and medium pressure cylinder shaft seal leakage of the steam turbine, the low pressure cylinder shaft seal steam intake, and shaft addition can be used Steam parameters, condensate temperature rise through the shaft seal heater, shaft seal pressure, and monitoring section temperature are used to comprehensively evaluate the effect of steam turbine seal renovation.

(2) For the steam turbine with the high and medium pressure cylinders arranged in reverse, the test of variable steam temperature is carried out, and the test of reducing the main steam temperature and increasing the reheating temperature, and increasing the main steam temperature and reducing the reheating temperature are respectively carried out. Make the relationship curve between the efficiency η _IP of the medium pressure cylinder of the above two working conditions and the percentage N of the shaft seal leakage between the high and medium pressure cylinders accounting for the main steam G _ms , and obtain the actual percentage of the shaft seal leakage between the high and medium pressure cylinders of the unit, Evaluate the effect of high and medium pressure inter-cylinder balance disc steam seal modification.

(3) The parameters of the monitoring section of the steam turbine, the steam leakage of the front and rear shaft seals of the high and medium pressure cylinders, the steam intake of the low pressure shaft seal, the pressure of the low pressure shaft seal, the inlet steam pressure of the shaft seal heater, the inlet steam temperature of the shaft seal heater, and the condensation Water temperature rise, high-pressure cylinder efficiency, medium-pressure cylinder efficiency, low-pressure cylinder efficiency, and the heat consumption rate after the unit parameter correction are compared with the design value of the manufacturer before the steam seal renovation to evaluate the energy-saving effect of the steam turbine steam seal renovation. The parameters are easy The measurement and calculation method is simple and feasible, and the calculation result is accurate.

Description of drawings

Fig. 1 is the arrangement diagram of measuring points of the thermal system of steam turbine unit of the present invention;

Figure 2(a) is the relationship curve between the efficiency _ηIP of the medium-pressure cylinder and the steam leakage percentage N of the shaft seal of the high- and medium-pressure cylinder before the steam seal transformation;

Figure 2(b) is the relationship curve between the efficiency _ηIP of the medium-pressure cylinder and the percentage of steam leakage N of the shaft seal of the medium-pressure cylinder after the steam seal transformation.

detailed description

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

The 660MW steam turbine of a power generation company is a supercritical, single-shaft, three-cylinder (high and medium pressure combined cylinder), four-exhaust steam, one-time intermediate reheat condensing steam turbine produced by Shanghai Steam Turbine Factory. After the unit was put into production, the heat consumption rate has not reached the design value, and the heat consumption is too high. The power generation company took advantage of the opportunity of overhaul of the unit to optimize and transform the shaft end of the steam turbine and the shaft seal and steam seal of the flow part.

The reconstruction plan of steam turbine seal is as follows:

(1) The front and rear shaft seals of high and medium pressure are transformed into honeycomb type seals; (2) The low pressure shaft seals are transformed into comb teeth + contact type gland seals (the outer 2 rings and the inner 1 ring are transformed from comb teeth gland seals to contact type gland seals) ; (3) The low-pressure forward and reverse first to fourth-stage vane top seals are transformed into honeycomb seals; (4) The worn high-pressure nozzle-inlaid seals are replaced; (5) The rest of the seals are all comb-teeth seals.

According to ASME PTC6-2004 "Steam Turbine Performance Test Regulations", the performance test of the steam turbine unit is carried out, and the layout of the test measurement points is shown in Figure 1.

Unit measurement system and measuring instruments: (1) Electric power measurement: The power of the generator is measured by a 0.02-level WT3000 power transmitter that has passed the calibration at the outgoing line of the generator. (2) Flow measurement: The condensate flow is measured by a standard throat pressure-taking long-neck nozzle and a 0.075-level 3051 differential pressure transmitter. The condensate flow nozzle is installed at the level between the #5 low-load outlet and the deaerator inlet. On the pipeline, and have been calibrated by a qualified testing center in advance. The desuperheating water flow rate of superheater and reheater is measured by standard orifice plate; the steam leakage flow rate of high and medium pressure cylinder shaft seal is measured by standard orifice plate; the steam supply flow rate of low pressure cylinder shaft seal is measured by standard orifice plate. (3) Pressure measurement: All pressure measuring points are measured with 0.1 grade 3051 pressure transmitters. (4) Temperature measurement: All temperature measurement points use industrial grade E graduation armored thermocouples.

All the data are collected by the IMP distributed data collector produced by Schlumberger, which is equipped with a portable computer, and the collection period is 30 seconds. The arithmetic mean value of the collected test raw data is calculated according to a period of continuous recording time with relatively stable working conditions, and the pressure measuring points are corrected for elevation and atmospheric pressure. The arithmetic mean value of the measured values of multiple measuring points of the same parameter in the test is taken.

Table 1 lists the original data of the 660MW working condition and variable steam temperature test before and after the steam seal modification of the unit, Table 2 lists the calculation results of the 660MW working condition test before and after the steam seal modification of the unit, and Table 3 lists the steam seal of the unit The calculation results of the variable steam temperature test before and after the transformation.

Table 1 Raw data of 660MW and variable steam temperature test before and after steam seal modification of unit

In this test, the condensate flow is used as the calculation basis, and the feed water flow is calculated according to the heat balance and mass balance of the #1, #2, and #3 high-pressure heaters and deaerators, and then the main steam flow, reheat steam flow, and high-pressure cylinder exhaust flow are calculated. Steam flow (cold reheating steam flow); calculate high and medium pressure shaft seal steam leakage and low pressure shaft seal steam supply flow according to the measured high and medium pressure shaft seal leakage and low pressure cylinder shaft seal steam supply parameters; according to the measured shaft seal The temperature parameters of the inlet steam and water inlet and outlet of the heater are used to calculate the temperature rise of the shaft seal heater and other parameters, as shown in Table 2.

Table 2 Calculation results of 660MW working condition test before and after steam seal modification of unit

After the steam seal modification of the supercritical 660MW unit above, the steam temperature test was carried out under the working conditions of electric power 640MW and three main control valves fully open. During the test, the power of the unit was kept constant, the main steam pressure was constant, and the three valves were fully opened. . Respectively reduce the main steam temperature and increase the reheat steam temperature, increase the main steam temperature and reduce the reheat steam temperature, so that the difference between the two is 20-30°C, so as to determine the leakage of the shaft seal at the balance plate between the high and medium pressure cylinders and Real efficiency values for medium pressure cylinders. See Table 3 for the calculation results of the steam leakage test of the shaft seal at the balance plate between high and medium pressure cylinders.

Table 3 Experimental results of variable steam temperature conditions before and after steam seal modification of supercritical 660MW steam turbine

The test results of variable steam temperature conditions: before the steam seal renovation, the steam leakage of the shaft seal at the balance plate of the high and medium pressure cylinders accounted for 1.283% of the main steam flow; The steam leakage of the shaft seal accounts for 0.8945% of the main steam flow; According to the design data of the THA working condition, the steam leakage of the shaft seal at the balance plate of the high and medium pressure cylinders accounts for 0.986% of the main steam flow, and the actual steam leakage is larger than the designed steam leakage. The amount is less than the amount of steam leakage of the shaft seal before the optimization of the steam seal. Figure 2(a) is the relationship curve between the efficiency of the medium pressure cylinder of the steam turbine and the percentage N of the shaft seal leakage at the balance plate between the high and medium pressure cylinders before the steam seal renovation; Figure 2(b) is the steam turbine after the steam seal renovation The relationship curve between the efficiency of the pressure cylinder and the percentage N of the steam leakage of the shaft seal at the balance plate between the high and medium pressure cylinders.

From the test calculation results in Table 2 and Table 3, it can be seen that after the transformation of the steam turbine shaft end seal and the shaft seal and steam seal of the flow part, the efficiency of the high-pressure cylinder is increased from 82.29% to 85.048%, and the efficiency of the medium-pressure cylinder is increased from 90.151%. to 91.724%, the heat consumption rate after the unit parameter correction is reduced from 7910.408kJ/kW.h to 7642.052kJ/kW.h, and the steam leakage from the first section of the high-pressure rear shaft seal to the exhaust pipe of the medium-pressure cylinder is reduced from 9474.5kg/h To 9315.4kg/h, the percentage of steam leakage from balance plate shaft seal between high and medium pressure cylinders to main steam flow is reduced from 1.283% to 0.8945%. Under low-load conditions, the steam supply pressure of the shaft seal is reduced, and the steam supply flow rate of the low-pressure shaft seal is reduced, which cannot meet the self-sealing requirements of the unit; after the steam seal is modified, the steam inlet pressure of the shaft seal heater is reduced from 0.142MPa to 0.109MPa, The temperature rise of the condensate passing through the shaft seal heater is reduced from 1.988°C to 1.7°C; the steam leakage of the shaft seal at the balance plate of the high and medium pressure cylinders is smaller than the design value. The above data shows that the energy-saving effect of steam turbine steam seal renovation is good.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (4)

1. A comprehensive calculation method of energy-saving effect after steam turbine steam seal transformation, it is characterized in that, comprises the following steps: Step 1: Arrange several test points for pressure, temperature and flow in the thermal system of the steam turbine unit; Step 2: Measure the leakage steam flow rate of the front and rear shaft seals of the high-pressure cylinder and medium-pressure cylinder, the steam intake flow rate of the low-pressure cylinder shaft seal, the parameters of the steam turbine monitoring section, the steam intake parameters of the shaft seal heater, and the temperature rise of condensate passing through the shaft seal heater ; Step 3: Carry out the test of the variable steam temperature of the steam turbine, measure and calculate the steam leakage percentage of the balance plate between the high and medium pressure cylinders of the symmetrical arrangement structure of the high pressure cylinder and the medium pressure cylinder; Step 4: Calculate the actual efficiency of the high-pressure cylinder, the actual efficiency of the medium-pressure cylinder and the actual efficiency of the low-pressure cylinder of the steam turbine unit; Step 5: Calculate the test heat rate of the steam turbine unit, and calculate the heat rate after the parameter correction of the steam turbine unit; Step 6: Set the parameters of the steam turbine monitoring section, the steam leakage of the balance disc between the high and medium pressure cylinders, the steam leakage of the front and rear shaft seals of the high and medium pressure cylinders, the steam intake of the low pressure cylinder shaft seal, the steam supply pressure of the low pressure cylinder shaft seal, and the heating of the shaft seal The inlet steam pressure, inlet steam temperature and condensate temperature rise, the actual efficiency of the high-pressure cylinder, the actual efficiency of the medium-pressure cylinder, the actual efficiency of the low-pressure cylinder, and the heat consumption rate after the unit parameter correction are respectively compared with the design values of the manufacturer before the steam seal transformation Comparing and comprehensively judging the energy-saving effect of steam turbine seal renovation according to the comparison results; The concrete measuring method of described step 2 is: (1) Measure the leakage steam pressure P ₁ of the shaft seal of the high-pressure cylinder and the medium-pressure cylinder respectively, the working temperature t ₁ of the shaft seal leakage flow throttling device before and after the high-pressure and medium-pressure cylinder, the steam supply pressure P ₂ of the shaft seal of the low-pressure cylinder, and the pressure of the low-pressure cylinder Working temperature t ₂ of cylinder shaft seal inlet steam flow throttling device, steam turbine monitoring section pressure P ₃ , steam turbine monitoring section temperature t ₃ , shaft seal heater inlet steam pressure P ₄ , shaft seal heater inlet steam temperature t ₄ , shaft seal heater Seal heater inlet water temperature t ₅ , shaft seal heater outlet water temperature t ₆ ; ( ₂ ) Use the known ΔT=t6 _- t5 to calculate the temperature rise of the condensed water passing through the shaft seal heater; (3) Measure the steam leakage density ρ ₁ of the front and rear shaft seals of the high and medium pressure cylinders and the steam intake density ρ ₂ of the low pressure cylinder shaft seals; (4) Calculate the opening diameter d _t1 of the leakage steam flow throttling device of the front and rear shaft seals of the high and medium pressure cylinders and the opening diameter d _t2 of the steam inlet flow throttling device of the shaft seal of the low pressure cylinder respectively; the specific formula is: d _t1 =d ₂₀₁ ×λ _d1 ×(t ₁ -20); d _t2 =d ₂₀₂ ×λ _d2 ×(t ₂ -20); Among them, d ₂₀₁ is the opening diameter of the shaft seal leakage flow throttling device at the front and rear shaft seals of high and medium pressure cylinders at the design temperature of 20°C, and λ _d1 is the linear expansion of the shaft seal leakage flow throttling device of the front and rear shaft seals of high and medium pressure cylinders Coefficient, d ₂₀₂ is the opening diameter of the low-pressure cylinder shaft seal inlet steam flow throttling device at the design temperature of 20°C, λ _d2 is the linear expansion coefficient of the low-pressure cylinder shaft seal inlet steam flow throttling device; (5) Calculate the leakage steam flow G _zf of the front and rear shaft seals of the high and medium pressure cylinders and the steam intake flow G _dzf of the shaft seals of the low pressure cylinder respectively. The specific formula is: G _zf ＝0 _. 126446×α ₁ ×d _t1 ² ×ε ₁ ×(ΔP ₁ ×ρ ₁ ) ^1/2 ; G _dzf ＝ _0.126446 ×α ₂ ×d _t2 ² ×ε ₂ ×(ΔP ₂ ×ρ ₂ ) ^1/2 ; Among them, α1 is the flow coefficient _of the shaft seal leakage flow throttling device before and after the high and medium pressure cylinders, which is _a known quantity, and ΔP1 is the measured flow rate of the shaft seal leakage flow throttling device at the front and rear of the high and medium pressure cylinders during the test The differential pressure, unit kPa, ε ₁ is the expansion coefficient of the measured medium, which is a known quantity; α ₂ is the flow coefficient of the low-pressure cylinder front and rear shaft seal leakage flow throttling device, which is a known quantity, and ΔP ₂ is a known quantity during the test The differential pressure of the flow rate measured by the leakage steam flow throttling device of the front and rear shaft seals of the low-pressure cylinder, the unit is kPa, and _ε2 is the expansion coefficient of the measured medium, which is a known quantity. 2. the comprehensive calculation method of energy-saving effect after a kind of steam turbine steam seal transformation as claimed in claim 1, it is characterized in that, the concrete measuring method of described step 3 is: (1) Carry out two working condition tests of reducing the main steam temperature of the steam turbine and increasing the reheating temperature, and increasing the main steam temperature of the steam turbine and reducing the reheating temperature, so that the deviation between the main steam temperature and the reheating temperature is 20-30°C, and other parameters constant; (2) Measure the inlet steam enthalpy i _ms of the high-pressure cylinder, the inlet steam enthalpy of the medium-pressure cylinder i _rh , the final feedwater enthalpy i _fw , the exhaust steam enthalpy of the high-pressure cylinder i _ch , the desuperheating water enthalpy of the superheater i _ss , and the desuperheating water enthalpy of the reheater i _rs , #1 high feed steam enthalpy i _n1 , #1 high feed steam enthalpy i _s1 , #2 high feed steam enthalpy i _n2 , #2 high feed steam enthalpy i _s2 , #3 high feed steam enthalpy i _n3 , #3 high water enthalpy i _s3 , #1 high water enthalpy i ₁₁ , #1 high water enthalpy i ₁₂ , #2 high water enthalpy i ₂₁ , #2 high water enthalpy i ₂₂ , #3 High feed water enthalpy i ₃₁ , #3 high feed water enthalpy i ₃₂ and generator active power Pe; (3) Measure the feedwater flow G _fw before the boiler economizer inlet, the equivalent flow G _b1 of boiler drum water level change, the superheater desuperheating water flow G _ss , and the reheater desuperheating water flow G _rs ; (4) Calculate the inlet steam flow rate G _e1 of #1, the inlet steam flow rate G _e2 of #2 and the inlet steam flow rate G _e3 of #3 respectively. The specific calculation formulas are as follows: G _e1 =G _fw ×(i ₁₂ -i ₁₁ )/(i _n1 -i _s1 ); G _e2 ＝[G _fw ×(i ₂₂ -i ₂₁ )-G _e1 ×(i _s1 -i _s2 )]/(i _n2 -i _s2 ); G _e3 ＝[G _fw ×(i ₃₂ -i ₃₁ )-(G _e1 +G _e2 )×(i _s2 -i _s3 )]/(i _n3 -i _s3 ); (5) Calculate the main steam flow G _ms , the cold reheat steam flow G _ch and the reheat steam flow G _rh respectively, and the specific calculation formulas are as follows: G _ms = G _fw +G _b1 +G _ss ; G _ch =G _ms -G _g1 -G _e1 -G _e2 -G _e3 ; G _rh =G _ch +G _rs ; Among them, G _g1 is the sum of the steam leakage of the door rod of the high pressure cylinder and the front and rear shaft seals, which is given by the thermal characteristic book of the manufacturer; (6) Measure the steam leakage enthalpy i _leak of the shaft seal between high and medium pressure cylinders; measure the inlet steam pressure P _rh of the medium pressure cylinder, measure the exhaust steam pressure P _ich of the medium pressure cylinder, and measure the exhaust steam enthalpy i _ich of the medium pressure cylinder; (7) Set the steam leakage G _leak between high and medium pressure cylinders as a percentage of the main steam flow G _ms N to be 0, 2, 4, 6, 8, and 10 respectively, and calculate the steam leakage between high and high pressure cylinders The enthalpy value i _mix after hot steam mixing, the specific calculation formula is: i _mix =[G _rh ×i _ich +i _leak ×N×G _ms ]/(G _rh +N×G _ms ); (8) Calculate the actual enthalpy drop H _i of the reheat steam in the medium pressure cylinder, the specific formula is: H _i = i _mix - i _ich ; (9) Using the measured inlet steam pressure P _rh of the medium pressure cylinder, the enthalpy value i _mix of the shaft seal leakage between the high and medium pressure cylinders mixed with the reheat steam, and the exhaust pressure P _ich of the medium pressure cylinder to calculate the reheat steam in the middle The isentropic enthalpy drop H ₀ in the cylinder; (10) Calculate the actual efficiency η _IP of the medium pressure cylinder, the calculation formula is: η _IP =H _i /H ₀ ; (11) Utilize the calculation method described in step (2)-step (10) to calculate respectively and draw the actual efficiency η _IP of the medium-pressure cylinder in the two variable steam temperature working conditions experiments of the steam turbine in step (1) and the difference between the medium-pressure cylinder and the medium-pressure cylinder The relationship curve of shaft seal leakage percentage N, the value of the intersection point N in the two relationship curves obtained is the actual percentage of shaft seal leakage between high and medium pressure cylinders of the steam turbine unit. 3. the comprehensive calculation method of energy-saving effect after a kind of steam turbine steam seal transformation as claimed in claim 1, it is characterized in that, the concrete method of described step 4 is: (1) Measure the inlet steam pressure P _ms of the high-pressure _cylinder , the inlet steam temperature of the high-pressure cylinder t _ms , and the inlet steam _enthalpy of the high-pressure cylinder im _ms ; i _ch ; measure the inlet steam pressure P _rh , the inlet steam temperature t _rh of the intermediate pressure cylinder, and the inlet steam enthalpy i _rh of the intermediate pressure cylinder; measure the exhaust steam pressure P _ich of the intermediate pressure cylinder, the exhaust steam temperature of the intermediate pressure cylinder t _ich , Medium pressure cylinder exhaust enthalpy i _ich ; measure low pressure cylinder inlet steam pressure P _lp , low pressure cylinder inlet steam temperature t _Lp , low pressure cylinder inlet steam enthalpy i _lp ; measure low pressure cylinder exhaust pressure P _ex ; (2) Calculate the actual enthalpy drop H _HP of steam in the high-pressure cylinder and the actual enthalpy drop H _i of steam in the medium-pressure cylinder respectively. The specific calculation formula is as follows: H _HP = i _ms - i _ch ; H _i = i _mix - i _ich ; Among them, i _mix is the enthalpy value of the steam leakage of the shaft seal between the high and medium pressure cylinders mixed with the reheated steam; (3) Calculate the isentropic enthalpy drop H _OHP of steam in the high-pressure cylinder by using the measured high-pressure cylinder inlet steam pressure P _ms , high-pressure cylinder inlet steam enthalpy im _ms and high-pressure cylinder exhaust pressure P _ch ; Using the measured inlet steam pressure P _rh of the medium pressure cylinder, the enthalpy value i _mix of the leakage steam between the high and medium pressure cylinders mixed with the reheat steam, and the exhaust pressure Pi _ich of the medium pressure cylinder to calculate the reheat steam in the medium pressure cylinder The isentropic enthalpy drop H ₀ ; Use the measured low-pressure cylinder inlet steam pressure P _lp , low-pressure cylinder inlet steam enthalpy i _lp and low-pressure cylinder exhaust pressure P _ex to calculate steam and calculate the entropy-enthalpy drop H _OLP in the low-pressure cylinder; (4) Calculating the exhaust enthalpy i _ex of the low-pressure cylinder by using the steam turbine energy balance method; (5) Calculate the actual enthalpy drop H _LP of steam in the low pressure cylinder, the calculation formula is: H _LP =i _lp -i _ex ; (6) Calculate the actual efficiency η _HP of the high-pressure cylinder, the actual efficiency η _IP of the medium-pressure cylinder, and the actual efficiency η _LP of the low-pressure cylinder respectively. The specific calculation formulas are as follows: _ηHP = _HHP / _HOHP ; η _IP =H _i /H ₀ ; η _LP =H _LP / _HOLP . 4. the comprehensive calculation method of energy-saving effect after a kind of steam turbine steam seal transformation as claimed in claim 2, it is characterized in that, the concrete steps of described step 5 are: (1) The computer group test heat consumption rate H _t , the calculation formula is: H _t ＝((G _ms -G _ss )×(i _ms -i _fw )+G _ch ×(i _rh -i _ch )+G _ss ×(i _ms -i _ss )+G _rs ×(i _rh -i _rs ))/Pe; (2) The heat consumption rate H _r corrected by the computer group, the calculation formula is: H _r ＝H _t /(C ₁ ×C ₂ ×C ₃ ×C ₄ ×C ₅ ) Among them, C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ are all known parameters provided by the manufacturer, which are the main steam pressure, main steam temperature, reheat steam pressure loss, reheat steam temperature and low-pressure cylinder row Correction factor for steam pressure to heat rate.