Optimized calculation and analysis method for recycling and utilizing dilatation steam of drainage water

Abstract

The invention discloses a drainage and drainage expansion steam recycling optimization calculation analysis method. The method comprises the following steps that a mathematical model for quantitative calculation of heat energy and working medium recycling contained in drainage and drainage is established; the heat energy contained in the drainage water and the thermal performance of a working medium recovery system are calculated, and pricing is carried out according to the specific enthalpy value or the ratio # imgabs0 # value of steam; according to the current system, pricing is carried out according to the specific enthalpy value or the ratio # imgabs1 # value of steam to obtain the optimal calculation result of the maximum recovery income, and comparison and analysis are carried out; and automatically generating a working medium and heat recovery calculation book of the drainage and drainage expansion steam recycling system by combining the calculation and analysis method according to known parameters of the drainage and drainage expansion steam recycling system, a steam price valuation relationship valuated by a specific enthalpy value, and a steam price valuation relationship valuated by a specific # imgabs2 # value. According to the result obtained by the optimization calculation analysis method, the drainage expansion steam recycling system can be controlled, and the maximum recycling economic benefit is obtained.

Description

Technical Field

[0001] The present invention relates to the field of energy technology, and in particular to a method for optimizing calculation and analysis of recovery and utilization of steam for expansion of drainage water. Background Art

[0002] As one of the most widely used forms of energy, thermal energy is widely used in production and life throughout society. Water and water vapor are usually used as heat carriers to achieve the conversion and utilization of thermal energy through thermal systems. In some thermal equipment that constitutes the thermal system, there will always be some heat carriers - drainage water intentionally or unintentionally discharged from the thermal system for safety reasons or due to leaks in the equipment. The temperature and pressure of these discharged drainage waters are higher than the temperature and pressure of the atmospheric environment, so they contain thermal energy. If they are discharged into the environment in this way, the thermal energy contained in them will be lost as heat loss; not only that, the heat carriers in most thermal systems are not ordinary natural water. For example, the working water in thermal power plants is obtained by water treatment of ordinary natural water with higher quality, which is a very precious resource. Even if the heat carrier is ordinary natural water in some occasions, it is also a resource. It is a pity to discharge it into the environment in vain.

[0003] The drainage water expansion steam recovery and utilization system is usually used to recover the heat contained in the expanded steam and the heat carrier of the steam itself. The drainage water to be recovered (taking the continuous sewage discharge of drum boiler as an example) enters the expansion tank through the pipeline, and the volume increases and the pressure decreases in the expansion tank, and adiabatically expands. The saturated water originally at a higher pressure becomes supersaturated liquid water in the expansion tank due to the pressure reduction, and then evaporates into water vapor. Since the ability of water vapor to dissolve (carry) salts (oxides) is very weak, it can be considered that the evaporated water vapor is "clean" and can be completely recovered and reused according to the grade of the heat energy it contains, and the water vapor heat carrier itself is also recovered. Through the recovery pipeline, these recovered water vapors and the heat energy they contain are added to appropriate thermal equipment according to the principle of temperature and pressure matching for recovery. For example, taking the steam recovery from the continuous sewage discharge expansion of drum boiler as an example, it can enter the deaerator as a heating heat source. The remaining liquid water that has not evaporated has a higher concentration of dissolved (carried) salts (oxides). Since its temperature is higher than the atmospheric temperature, it also has recoverable heat energy. It can exchange heat with make-up water through a heat exchanger (sewage cooler) and then be discharged into the sewage pipeline as real sewage after the temperature is further reduced.

[0004] The Chinese patent document with the publication number CN103574586A discloses a multi-stage pressure reduction and volume expansion vaporization device for continuous blowdown wastewater of a steam drum, including a tank body, a primary diffusion barrel, a secondary diffusion barrel, a tertiary diffusion barrel, a nozzle, etc. arranged in the tank body; among them, a water inlet is provided at the top of the tank body, the bottom of the water inlet is connected to the large-diameter port of the nozzle, the small-diameter port at the other end of the nozzle is connected to the barrel mouth of the primary diffusion barrel through a diffusion pipe, the secondary diffusion barrel and the tertiary diffusion barrel are sequentially sleeved on the primary diffusion barrel, a plurality of diffusion holes are provided on the above three diffusion barrels, and a steam exhaust port is further provided at the bottom of the above tank body for discharging water vapor in the tank body.

[0005] However, as described above, this invention patent only converts the blowdown water discharged from the boiler steam drum into low-temperature saturated steam through multi-stage cooling and pressure reduction, so as to recover and utilize the heat contained in the steam and the steam working medium itself. However, exactly how to reduce the pressure and expand the volume, how much pressure to use for expansion, how to obtain the best economic benefits from the heat and working medium contained in the recovered steam from an economic perspective, what is the working medium recovery rate, and when the steam price changes or is priced according to different pricing methods, how much pressure should be used for expansion. These problems have not been involved in the prior art. Summary of the Invention

[0006] The purpose of the present invention is to provide an optimized calculation and analysis method for the recovery and utilization of blowdown water expansion steam, which can control the blowdown water expansion steam recovery and utilization system according to the results obtained by the optimized calculation and analysis method to obtain the maximum recovery economic benefits.

[0007] In one aspect of the present invention, the present invention proposes an optimized calculation and analysis method for the recovery and utilization of blowdown water expansion steam. According to an embodiment of the present invention, the method includes the following steps:

[0008] (1) Establish a quantitative calculation mathematical model for the recovery of heat energy and working medium contained in blowdown water;

[0009] (2) Apply the quantitative calculation mathematical model for the recovery of heat energy and working medium contained in blowdown water to calculate the thermodynamic performance of the heat energy and working medium recovery system of blowdown water;

[0010] (3) Apply the quantitative calculation mathematical model for the recovery of heat energy and working medium contained in blowdown water to an optimized calculation and analysis method for blowdown water recovery priced according to the specific enthalpy value of steam;

[0011] (4) Apply the quantitative calculation mathematical model for the recovery of heat energy and working medium contained in blowdown water to an optimized calculation and analysis method for blowdown water recovery priced according to the specific value of steam;

[0012] (5) Operate the drain water expansion steam recovery and utilization system under the current expansion pressure, and conduct a comparative analysis of the optimization calculation results of obtaining the maximum recovery benefit by pricing according to the specific enthalpy value of the steam in step (3) and the optimization calculation results of obtaining the maximum recovery benefit by pricing according to the specific value of the steam in step (4);

[0013] (6) Based on the known parameters of the drain water expansion steam recovery and utilization system, the pricing relationship of steam priced by specific enthalpy value, and the pricing relationship of steam priced by specific value, combined with the above-mentioned calculation and analysis methods, automatically generate the calculation book for the recovery of working medium and heat of the drain water expansion steam recovery and utilization system.

[0014] In addition, according to an optimization calculation and analysis method for drain water expansion steam recovery and utilization according to the above embodiments of the present invention, the following additional technical features may also be provided:

[0015] In some embodiments of the present invention, step (1) is specifically as follows. From the energy balance equation and material balance equation of the flash tank, establish a mathematical model to quantitatively calculate its working medium recovery rate and the recovered heat:

[0016] Material balance equation of the flash tank: D bl =D f +D' bl ;

[0017] In the formula, D bl is the flow rate of the blowdown water, D f is the flow rate of the recovered expansion steam, and D' bl is the flow rate of the blowdown water;

[0018] Heat balance equation of the flash tank: D bl h' bl η f =D f h'' f +D' bl h' f ;

[0019] In the formula, h' bl is the specific enthalpy value of the blowdown water, η f is the thermal efficiency of the flash tank, h'' f is the specific enthalpy value of saturated steam under the pressure of the flash tank, and h' f is the specific enthalpy value of saturated water under the pressure of the flash tank;

[0020] Heat balance equation of the blowdown water cooler:

[0021] In the formula, is the specific enthalpy value of the blowdown water, η l is the thermal efficiency of the blowdown water cooler, and Dma is the flow rate of chemical make-up water, is the specific enthalpy value of the chemical make-up water when it leaves the blowdown cooler, h w.ma is the specific enthalpy value of the chemical make-up water when it enters the blowdown cooler;

[0022] From D bl = D f + D' bl we get: D' bl = D bl - D f , substituting D bl h' bl η f = D f h” f + D' bl h' f ,

[0023] D bl h' bl η f = D f h” f +(D bl - D f )h' f , D bl h' bl η f = D f h” f + D bl h' f - D f h' f ,

[0024] D bl (h' bl η f - h' f ) = D f (h” f - h' f ),

[0025] The working medium recovery rate of the flash tank:

[0026] p f is the working pressure of the flash tank;

[0027] When there is no blowdown utilization system, the blowdown heat loss: Q bl = D bl (h' bl - h w.ma );

[0028] When there is a blowdown utilization system, the blowdown heat loss is:

[0029] Available blowdown heat: ΔQ bl = Q bl - Q' bl .

[0030] In some embodiments of the present invention, the step (2) is specifically as follows. According to the established mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drain water, the drain water flash steam recovery system is operated at any flash pressure, and the thermal performance indicators are calculated. The thermal performance indicators include the recovery rate of the working medium, the specific enthalpy value of the saturated water in the flash tank, the specific enthalpy value of the saturated steam in the flash tank, the specific enthalpy value of the recovered flash steam, the ratio value of the recovered flash steam, the temperature of the recovered flash steam, the dryness of the recovered flash steam, the flow rate of the recovered working medium, the heat recovered by the blowdown water cooler, and the additional heat recovered by the system.

[0031] In some embodiments of the present invention, the step (3) is specifically as follows:

[0032] Applying the mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drain water, and the pricing relationship of steam prices based on specific enthalpy values, the optimization calculation model is used:

[0033] MaxRecoveryFlowIncome = RecoveryFlowPrice × RecoveryFlow

[0034] RecoveryFlowPrice = f(SteamEnthalpy)

[0035] RecoveryFlow = g(pf)

[0036] s.t. p0 < p f < p bl

[0037] In the formula, RecoveryFlowIncome is the income of the recovered working medium (yuan / h), RecoveryFlowPrice is the price of the recovered working medium (yuan / t), SteamEnthalpy is the specific enthalpy value of the recovered working medium (kJ / kg), pf is the pressure of the recovered working medium (bar), RecoveryFlow is the flow rate of the recovered working medium (t / h), f() is the pricing relationship of steam prices based on specific enthalpy values, and g() is the dependence relationship between the flow rate of the recovered working medium and the pressure of the recovered working medium.

[0038] In some embodiments of the present invention, in the step (3), the optimization calculation is carried out in ascending order of the pressure pf of the recovered working medium to obtain the optimal state values of the recovered flash steam pressure and the income of the recovered working medium, as well as the change trends of the key indicators

[0039] In some embodiments of the present invention, step (4) is specifically as follows:

[0040] Apply the mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drainage, and the pricing relationship of steam priced by specific values, and adopt the optimization calculation model:

[0041] Max RecoveryFlowIncome=RecoveryFlowPrice×RecoveryFlow

[0042] RecoveryFlowPrice=h(SteamExergy)

[0043] RecoveryFlow=i(pf)

[0044] s.t.p0<p f <p bl

[0045] In the formula, RecoveryFlowIncome is the income of the recovered working medium (yuan / h), RecoveryFlowPrice is the price of the recovered working medium (yuan / t), SteamExerg is the specific value (kJ / kg) of the recovered working medium, pf is the pressure of the recovered working medium (bar), RecoveryFlow is the flow rate of the recovered working medium (t / h), h() is the pricing relationship of steam priced by specific values, and i() is the dependence relationship between the flow rate of the recovered working medium and the pressure of the recovered working medium.

[0046] In some embodiments of the present invention, in step (4), the optimization calculation is carried out in ascending order of the pressure pf of the recovered working medium to obtain the optimal state values of the pressure of the recovered flash steam and the income of the recovered working medium, as well as the change trends of the key indicators.

[0047] In some embodiments of the present invention, in step (5), the calculation results include the pressure of the recovered flash steam, the specific enthalpy value of the recovered flash steam, the specific value of the recovered flash steam, the temperature of the recovered flash steam, the dryness of the recovered flash steam, the working medium recovery rate, the price of the recovered working medium, and the income of the recovered working medium.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] (1) Any expansion pressure can be input, and the drain water expansion steam recovery and utilization system can be operated at this pressure to quantitatively calculate and analyze the "quantity" of steam that can be recovered by the drain water expansion steam recovery and utilization system and the "quality" of the thermal energy contained in the recovered steam. The size of the working medium recovery rate depends on the flash tank pressure. The lower the expansion pressure, the more the "quantity" of the recovered working medium. Since the increase in the "quantity" of the recovered expansion steam is achieved by reducing the pressure of the recovered expansion steam (depreciation of energy grade), as the flash tank pressure decreases, although the quantity of the recovered working medium increases, the quality (grade) of the thermal energy contained in the recovered working medium decreases. Furthermore, the change trends of key indicators such as the specific enthalpy value of the recovered expansion steam, the temperature of the recovered expansion steam, the dryness of the recovered expansion steam, the working medium recovery rate, and the heat recovered by the system can be calculated and analyzed as the pressure of the recovered expansion steam increases from small to large. The optimized calculation and analysis method for drain water recovery provided by the present invention can adjust the inlet and outlet pressure regulating valves of the flash tank according to the calculation and analysis results, control the pressure of the flash tank, balance the contradiction between the "quantity" of the recovered steam and the "quality" of the thermal energy contained in the recovered steam, make the best choice, and achieve the best recovery economic benefits.

[0050] (2) Usually, the pricing of steam is determined by the state parameters of steam, namely pressure and temperature. Since the state parameters of low-temperature and low-pressure steam, such as pressure and temperature, are low, the price per unit mass of steam is low; the state parameters of medium-temperature and medium-pressure steam, such as pressure and temperature, are higher, and the price is also higher; the state parameters of high-temperature and high-pressure steam, such as pressure and temperature, are even higher, and the price is also higher. This pricing method is discrete, with only a limited number of price steps. For the drain water expansion steam recovery and utilization system to recover steam, both the "quality" of the thermal energy contained in the recovered steam and the "quantity" of the recovered steam need to be considered, and this pricing method is very disadvantageous. It is best to convert this discrete method into a continuous method to better unify the "quality" and "quantity" of the recovered steam. The optimized calculation and analysis method for drain water recovery provided by the present invention calculates the specific enthalpy value and specific value of the recovered steam based on the state parameters of the recovered steam, namely pressure and temperature, then forms data pairs with the corresponding prices, and then fits these data pairs into a continuous pricing method using the least squares method. Furthermore, an optimized calculation and analysis method for the drain water expansion steam recovery and utilization system applicable to different steam pricing methods is proposed, which can perform the most optimized calculation and analysis for the maximum recovery benefit of the drain water expansion steam recovery based on the specific enthalpy value of the recovered steam, and achieve the best recovery economic benefits; and the most optimized calculation and analysis for the maximum recovery benefit of the drain water expansion steam recovery based on the specific value of the recovered steam, and achieve the best recovery economic benefits.

[0051] (3) Even if the pricing of steam changes with the development of the national economy, the optimized calculation and analysis method for drain water recovery provided by the present invention can still set a steam pricing table, fit a new continuous pricing method according to the changed steam pricing through the least squares method, and conduct the optimization calculation and analysis of the drain water expansion steam recovery and utilization system applicable to different steam pricing methods to obtain the optimal recovery economic benefits.

[0052] (4) The optimized calculation and analysis method for drain water recovery provided by the present invention can conveniently conduct the optimization calculation results of the drain water expansion steam recovery and utilization system operating at the current expansion pressure, the optimization calculation results of obtaining the maximum recovery benefit by pricing according to the specific enthalpy value of the recovered steam, and the comparison and analysis of the optimization calculation results of obtaining the maximum recovery benefit by pricing according to the ratio value, so as to understand and evaluate the similarities and differences of key thermal economic indicators.

[0053] (5) Based on the above aspects, the optimized calculation and analysis method for drain water recovery provided by the present invention can automatically generate a calculation book for the optimization calculation and analysis of the drain water expansion steam recovery and utilization system, according to the research object; calculation and analysis mechanism; known conditions required for calculation and analysis; setting of the steam pricing table; thermal performance calculation and analysis of the drain water expansion steam recovery and utilization system; the optimization calculation and analysis of obtaining the maximum recovery economic benefit by pricing according to the specific enthalpy value of the recovered steam, and obtaining the optimal recovery economic benefit; the optimization calculation and analysis of obtaining the maximum recovery economic benefit by pricing according to the ratio value of the recovered steam, and obtaining the optimal recovery economic benefit; the comparison, analysis and evaluation of the optimization calculation results of the drain water expansion steam recovery and utilization system operating at the current expansion pressure, the optimization calculation results of obtaining the maximum recovery benefit by pricing according to the specific enthalpy value of the recovered steam, and the optimization calculation results of obtaining the maximum recovery benefit by pricing according to the ratio value; these aspects are visually expressed and elaborated. Description of the Drawings

[0054] Figure 1 is a flowchart of an optimized calculation and analysis method for drain water expansion steam recovery and utilization in an embodiment of the present invention;

[0055] Figure 2 is a structural diagram of a drain water expansion steam recovery and utilization system in an embodiment of the present invention;

[0056] Figure 3 is a relationship diagram between the thermal performance of heat and working medium recovery and the expansion steam pressure recovered in an embodiment of the present invention;

[0057] Figure 4 is a steam price trend diagram by pricing according to the specific enthalpy value or ratio value of the recovered steam in an embodiment of the present invention;

[0058] Figure 5 This is the optimized calculation result diagram of the current and the maximum recovery benefit in the embodiment of the present invention according to the specific enthalpy value of the recovered steam;

[0059] Figure 6 This is the optimized calculation result diagram of the current and the maximum recovery benefit in the embodiment of the present invention according to the specific enthalpy value of the recovered steam;

[0060] Figure 7 This is the comparative analysis diagram of the optimized calculation results of the current blowdown expansion steam recovery and utilization system operating at the current expansion pressure in the embodiment of the present invention, the maximum recovery benefit obtained according to the specific enthalpy value of the recovered steam, and the optimized calculation results of the maximum recovery benefit obtained according to the specific enthalpy value of the recovered steam. Specific embodiments

[0061] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0062] See Figure 2 , the blowdown expansion steam recovery and utilization system (illustrated by the continuous blowdown of a steam drum boiler) see Figure 2 , which is composed of a blowdown collection pipeline, an inlet pressure regulating valve of the flash tank, a flash tank, an outlet pressure regulating valve of the flash tank, a steam recovery pipeline, a mixing heater (deaerator), a blowdown pipeline, a heat exchanger (blowdown cooler), etc. Please refer to Figure 1 , the optimized calculation and analysis method for the blowdown expansion steam recovery and utilization applicable to different steam pricing methods includes the following steps:

[0063] (1) Establish a quantitative calculation mathematical model for the recovery of thermal energy and working medium contained in the blowdown.

[0064] List the heat balance equation and material balance equation for the flash tank, and combine with the international IFC formula for calculating the thermodynamic properties of water and steam heat carriers to solve these equations, quantitatively calculate the amount of working medium recovered by the flash tank and the recovery rate of the working medium, and calculate and determine the state parameters of the recovered working medium, such as pressure, temperature, humidity, specific enthalpy value, specific enthalpy value, etc.; list the heat balance equation of the heat exchanger (blowdown cooler), and solve to obtain the heat recovered from the blowdown by the blowdown cooler and the heat loss actually carried away by the blowdown.

[0065] The specific calculation formulas are as follows:

[0066] Material balance equation of the flash tank: D bl = D f + D′ bl ;

[0067] where D bl is the flow rate of the blowdown water, D f is the flow rate of the recovered flash steam, and D' bl is the flow rate of the blowdown water;

[0068] Heat balance equation of the flash tank: D bl h′ bl η f = D f h″ f + D′ bl h′ f ;

[0069] where h' bl is the specific enthalpy value of the blowdown water, η f is the thermal efficiency of the flash tank, h” f is the specific enthalpy value of the saturated steam at the flash tank pressure, and h' f is the specific enthalpy value of the saturated water at the flash tank pressure;

[0070] Heat balance equation of the blowdown water cooler (heat recovered from the blowdown water):

[0071]

[0072] where is the specific enthalpy value of the blowdown water, η l is the thermal efficiency of the blowdown water cooler, D ma is the flow rate of the chemical make-up water, is the specific enthalpy value of the chemical make-up water when it leaves the blowdown water cooler, and h w.ma is the specific enthalpy value of the chemical make-up water when it enters the blowdown water cooler;

[0073] From D bl = D f + D' bl we get: D' bl = D bl - D f , substituting it into D bl h' bl η f = D f h” f + D' bl h' f ,

[0074] D bl h' bl η f = D f h”f +(D bl -D f )h' f ,D bl h' bl η f =D f h” f +D bl h' f -D f h' f ,

[0075] D bl (h' bl η f -h' f )=D f (h” f -h' f )。

[0076] Recovery rate of working medium in flash tank:

[0077] p f is the working pressure of the flash tank;

[0078] When there is no sewage utilization system, heat loss of sewage: Q bl =D bl (h' bl -h w.ma );

[0079] When there is a sewage utilization system, heat loss of sewage is:

[0080] Available sewage heat: ΔQ bl =Q bl -Q' bl ;

[0081] (2) Calculation of thermal energy and working medium recovery system thermal performance contained in drain water

[0082] According to the established quantitative calculation mathematical model of thermal energy and working medium recovery contained in drain water, operate the drain water flash steam recovery and utilization system at any flash pressure, and solve it by combining with the international IFC formula for calculating the thermal properties of water and steam heat carriers, and calculate the working pressure of the flash tank (bar), the working temperature of the flash tank (°C), the recovery rate of the working medium, the specific enthalpy value of saturated water in the flash tank (kJ / kg), the specific enthalpy value of saturated steam in the flash tank (kJ / kg), the specific enthalpy value of the recovered flash steam (kJ / kg), the ratio of the recovered flash steam Thermodynamic performance indicators such as value (kJ / kg), temperature of the recovered flash steam (°C), dryness of the recovered flash steam (%), flow rate of the recovered working fluid (t / h), heat recovered by the blowdown cooler (kJ / h), and additional heat recovered by the system (kJ / h) are shown in Table 1.

[0083] Table 1 Thermodynamic Performance Index Table

[0084]

[0085]

[0086] Moreover, combined with the international IFC formula for calculating the thermodynamic properties of bound water and water vapor heat carriers, it is also possible to calculate through the quantitative calculation mathematical model of the thermal energy and working fluid recovery contained in the blowdown water established by cyclic calling. As the pressure of the recovered flash steam (bar) increases from small to large, the specific enthalpy value (kJ / kg) of the recovered flash steam, the specific value (kJ / kg), and the temperature of the recovered flash steam (°C) of the three indicators gradually increase; while the dryness of the recovered flash steam (%), the working fluid recovery rate, and the additional heat recovered by the system (kJ / h) of the three indicators gradually decrease; the state values (flash steam pressure bar, working fluid recovery rate) at the current recovered flash steam pressure are shown in Figure 3 .

[0087] Set the pricing information of steam: With the development of the national economy, the prices of technology and energy will change, resulting in changes in the pricing of steam. The optimized calculation and analysis method for blowdown water recovery provided by the present invention can still set the steam price list, as shown in Table 2, and fit a new continuous pricing method by the least squares method according to the changed steam pricing. It can be seen that as the specific enthalpy value and specific value of the recovered steam increase (that is, the improvement of the thermal energy quality contained in the recovered steam), the price of steam increases, as shown in Figure 4 , and perform the optimization calculation and analysis of the blowdown water flash steam recovery and utilization system suitable for different steam pricing methods to obtain the optimal recovery economic benefits.

[0088] Table 2 Steam Price List

[0089]

[0090]

[0091] (3) Optimized calculation and analysis of blowdown water recovery according to the specific enthalpy value of steam.

[0092] Apply the mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drainage water obtained in step (1), as well as the pricing relationship of steam priced by specific enthalpy value (the "specific enthalpy value and specific value" described above), and adopt the optimization calculation model:

[0093] Max RecoveryFlowIncome = RecoveryFlowPrice × RecoveryFlow

[0094] RecoveryFlowPrice = f(SteamEnthalpy)

[0095] RecoveryFlow = g(pf)

[0096] s.t. p0 < p f < p bl

[0097] Wherein, RecoveryFlowIncome is the income of the recovered working medium (yuan / h), RecoveryFlowPrice is the price of the recovered working medium (yuan / t), SteamEnthalpy is the specific enthalpy value of the recovered working medium (kJ / kg), pf is the pressure of the recovered working medium (bar), RecoveryFlow is the flow rate of the recovered working medium (t / h), f() is the pricing relationship of steam priced by specific enthalpy value, and g() is the dependence relationship between the flow rate of the recovered working medium and the pressure of the recovered working medium.

[0098] Perform optimization calculation in ascending order of the pressure pf of the recovered working medium to obtain the optimal state values (the pressure of the recovered flash steam (bar), the income of the recovered working medium (yuan / h)) and the change trends of the key indicators.

[0099] According to the pricing by the specific enthalpy value of the recovered steam, when optimizing the calculation to maximize the income of the recovered steam from the drainage water, the working pressure (bar) of the flash tank, the working temperature (°C) of the flash tank, the specific enthalpy value of the saturated water in the flash tank (kJ / kg), the specific enthalpy value of the saturated steam in the flash tank (kJ / kg), the specific enthalpy value of the recovered flash steam (kJ / kg), the temperature (°C) of the recovered flash steam, the dryness (%) of the recovered flash steam, the working medium recovery rate, the flow rate of the recovered working medium (t / h), the heat recovered more by the system (kJ / h), the price of the recovered working medium (yuan / t), the income of the recovered working medium (yuan / h), the pressure of the recovered flash steam (bar), etc. The results of the optimization calculation and analysis are shown in Table 3.

[0100] Table 3 Optimization calculation and analysis results table of performance indicators priced by the specific enthalpy value of the recovered steam

[0101]

[0102]

[0103] Moreover, it is also possible to price according to the specific enthalpy value of the recovered steam. As the pressure (bar) of the recovered flash steam increases from small to large, calculate the change trends of key indicators such as the specific enthalpy value (kJ / kg) of the recovered flash steam, the temperature (°C) of the recovered flash steam, the working fluid recovery rate, the price (yuan / t) of the recovered working fluid, and the income (yuan / h) of the recovered working fluid; the current state value (pressure (bar) of the recovered flash steam, income (yuan / h) of the recovered working fluid), and the optimal state value (pressure (bar) of the recovered flash steam, income (yuan / h) of the recovered working fluid). It can be seen that as the pressure of the recovered flash steam increases from small to large, the income of the recovered working fluid first increases, reaches a certain maximum value (the maximum income of the recovered working fluid), and then gradually decreases. The state with the maximum income of the recovered working fluid is the optimal result obtained by optimization. See Figure 5 .

[0104] (4) Optimization calculation and analysis of drain water recovery priced according to the specific enthalpy value of steam.

[0105] Apply the quantitative calculation mathematical model for the recovery of thermal energy and working fluid contained in drain water, as well as the pricing relationship of steam price priced according to the specific enthalpy value, and adopt the optimization calculation model:

[0106] Max RecoveryFlowIncome = RecoveryFlowPrice × RecoveryFlow

[0107] RecoveryFlowPrice = h(SteamExergy)

[0108] RecoveryFlow = i(pf)

[0109] s.t. p0 < p f < p bl

[0110] In the formula, RecoveryFlowIncome is the income (yuan / h) of the recovered working fluid, RecoveryFlowPrice is the price (yuan / t) of the recovered working fluid, SteamExerg is the specific enthalpy value (kJ / kg) of the recovered working fluid, pf is the pressure (bar) of the recovered working fluid, RecoveryFlow is the flow rate (t / h) of the recovered working fluid, h() is the pricing relationship of steam price priced according to the specific enthalpy value, and i() is the dependence relationship between the flow rate of the recovered working fluid and the pressure of the recovered working fluid.

[0111] Optimal calculation is carried out in ascending order of the pressure pf of the recycled working medium to obtain the optimal state values (the pressure of the expanded steam recovered (bar), the income of the recycled working medium (yuan / h)) and the changing trends of the key indicators.

[0112] According to the specific enthalpy value of the recovered steam for pricing, when optimizing the calculation to maximize the income of the recovered steam from the drain water, the working pressure of the flash tank (bar), the working temperature of the flash tank (°C), the specific enthalpy value of the saturated water in the flash tank (kJ / kg), the specific enthalpy value of the saturated steam in the flash tank (kJ / kg), the specific enthalpy value of the recovered expanded steam (kJ / kg), the temperature of the recovered expanded steam (°C), the dryness of the recovered expanded steam (%), the working medium recovery rate, the flow rate of the recycled working medium (t / h), the heat recovered by the system more (kJ / h), the price of the recycled working medium (yuan / t), the income of the recycled working medium (yuan / h), the pressure of the recovered expanded steam (bar), etc. The results of the optimization calculation and analysis are shown in Table 4 specifically.

[0113] Table 4 Results of the optimization calculation and analysis of the performance indicators priced according to the specific enthalpy value of the recovered steam

[0114]

[0115] Moreover, it is also possible to price according to the specific enthalpy value of the recovered steam and calculate the changing trends of the key indicators such as the specific enthalpy value of the recovered expanded steam (kJ / kg), the temperature of the recovered expanded steam (°C), the working medium recovery rate, the price of the recycled working medium (yuan / t), the income of the recycled working medium (yuan / h), etc. as the pressure of the recovered expanded steam (bar) increases from small to large; the current state values (the pressure of the recovered expanded steam (bar), the income of the recycled working medium (yuan / h)), the optimal state values (the pressure of the recovered expanded steam (bar), the income of the recycled working medium (yuan / h)). It can be seen that as the pressure of the recovered expanded steam increases from small to large, the income of the recycled working medium first increases, reaches a certain maximum value (the maximum income of the recycled working medium), and then gradually decreases. The state with the maximum income of the recycled working medium is the optimal result obtained by optimization, see . Figure 6 .

[0116] (5) Comparative analysis of the optimization calculation results of the current flash pressure operation drain water flash steam recovery and utilization system to obtain the maximum recovery income priced according to the specific enthalpy value of the recovered steam and the optimization calculation results to obtain the maximum recovery income priced according to the specific enthalpy value of the recovered steam.

[0117] Obtain the optimization calculation results of operating the drain expansion steam recovery and utilization system at the current expansion pressure, achieving the maximum recovery benefit by pricing according to the specific enthalpy value of the recovered steam, and compare and analyze the optimization calculation results of achieving the maximum recovery benefit by pricing according to the specific value, so as to understand and evaluate the similarities and differences of key thermo-economic indicators. The calculation results of the comparison of the three methods include: the pressure of the expanded steam recovered, the specific enthalpy value of the expanded steam recovered, the specific value of the expanded steam recovered, the temperature of the expanded steam recovered, the dryness of the expanded steam recovered, the working fluid recovery rate, the price of the recovered working fluid, and the benefit of the recovered working fluid. According to the steam pricing scheme set above, the benefit of the recovered working fluid obtained by the optimization calculation of achieving the maximum recovery benefit by pricing according to the specific value is the largest. The benefit of the recovered working fluid obtained by the optimization calculation of achieving the maximum recovery benefit by pricing according to the specific enthalpy value of the recovered steam is the second. The benefit of the recovered working fluid obtained by operating the drain expansion steam recovery and utilization system at the current expansion pressure is the smallest. See Figure 7 .

[0118] (5) Based on the known parameters of the drain expansion steam recovery and utilization system, the pricing relationship of steam priced by specific enthalpy value, and the pricing relationship of steam priced by specific value, combined with the above calculation and analysis methods, use the Python programming language to write a program to automatically control the Word software and automatically generate the calculation book of the recovered working fluid and heat of the drain expansion steam recovery and utilization system.

[0119] Based on the above aspects, an optimization analysis calculation book of the drain expansion steam recovery and utilization system can be automatically generated. According to the research object, the calculation analysis mechanism, the known conditions required for the calculation analysis, the setting of the steam pricing table, and the thermal performance calculation and analysis of the drain expansion steam recovery and utilization system; the optimization calculation analysis of the maximum drain expansion steam recovery benefit priced by the specific enthalpy value of the recovered steam to obtain the optimal recovery economic benefit; the optimization calculation analysis of the maximum drain expansion steam recovery benefit priced by the specific value of the recovered steam to obtain the optimal recovery economic benefit; the comparison and analysis evaluation of the optimization calculation results of operating the drain expansion steam recovery and utilization system at the current expansion pressure, achieving the maximum recovery benefit by pricing according to the specific enthalpy value of the recovered steam, and achieving the maximum recovery benefit by pricing according to the specific value of the recovered steam; visualize and elaborate on these aspects.

[0120] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as it does not deviate from the structure of the present invention or exceed the scope defined by this claim book, it shall fall within the protection scope of the present invention.

Claims

1. An optimized calculation and analysis method for the recovery and utilization of drained and expanded steam, characterized in that, It includes the following steps: (1) Establish a mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drain water; (2) Apply the mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drain water to calculate the thermodynamic performance of the thermal energy and working medium recovery system for the drain water; (3) Apply the mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drain water, and the optimization calculation analysis method for drain water recovery priced according to the specific enthalpy value of steam; (4) Apply the mathematical model for quantitative calculation of heat energy and working medium recovery in drainage, and the optimization calculation and analysis method for drainage recovery priced according to the specific value of steam; (5) Optimize the calculation results of the maximum recovery benefit obtained by operating the drain water expansion steam recovery and utilization system under the current expansion pressure and pricing according to the specific enthalpy value of the steam in step (3), and compare and analyze it with the optimized calculation results of the maximum recovery benefit obtained by pricing according to the specific value of the steam in step (4); (6) Based on the known parameters of the drain water expansion steam recovery and utilization system, the steam price pricing relationship based on specific enthalpy value, and the steam price pricing relationship based on specific value, combined with the above-mentioned calculation and analysis method, automatically generate the calculation book for the recovery of working medium and heat in the drain water expansion steam recovery and utilization system.

2. The optimized calculation and analysis method for the recovery and utilization of drained and expanded steam according to claim 1, wherein: The specific content of step (1) is as follows. Based on the energy balance equation and material balance equation of the flash tank, a mathematical model is established to quantitatively calculate its working medium recovery rate and recovered heat: Material balance equation of the flash tank: D bl = D f + D' bl ; Where D bl is the flow rate of the sewage discharged, D f is the flow rate of the flash steam recovered, D b ' l is the flow rate of the sewage discharged; Heat balance equation of the flash tank: D bl h′ bl η f = D f h″ f + D′ bl h′ f ; where h′ bl is the specific enthalpy value of the sewage discharged, η f is the thermal efficiency of the flash tank, h″ f is the specific enthalpy value of the saturated steam under the pressure of the flash tank, h' f is the specific enthalpy value of the saturated water under the pressure of the flash tank; Heat balance equation of the sewage cooler: In the formula, is the specific enthalpy value of the sewage discharge, η l is the thermal efficiency of the sewage cooler, D ma is the flow rate of the chemical makeup water, is the specific enthalpy value of the chemical makeup water when it leaves the sewage cooler, h w.ma is the specific enthalpy value of the chemical makeup water when it enters the sewage cooler; From D bl = D f + D' bl we get: D' bl = D bl - D f , substituting D bl h' bl η f = D f h″ f + D' bl h' f , D bl h′ bl η f = D f h″ f +(D bl - D f )h' f ,D bl h′ bl η f = D f h″ f + D bl h' f - D f h' f , D bl (h′ bl η f -h' f ) = D f (h″ f -h' f ) Working fluid recovery rate of the flash tank: p f is the working pressure of the flash tank; When there is no sewage utilization system, the heat loss of sewage discharge: Q bl = D bl (h′ bl - h w.ma ); When there is a sewage utilization system, the heat loss of the sewage is as follows: Available sewage heat: ΔQ bl = Q bl - Q' bl .

3. The optimized calculation and analysis method for drainage and expansion steam recovery and utilization according to claim 1, characterized in that: The specific steps of step (2) are as follows. Based on the established mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drainage, the drainage expansion steam recovery and utilization system is operated at any expansion pressure to calculate the thermal performance indicators, which include the recovery rate of the working medium, the specific enthalpy value of the saturated water in the flash tank, the specific enthalpy value of the saturated steam in the flash tank, the specific enthalpy value of the recovered expansion steam, the ratio value of the recovered expansion steam, the temperature of the recovered expansion steam, the dryness of the recovered expansion steam, the flow rate of the recovered working medium, the heat recovered by the sewage cooler, and the additional heat recovered by the system.

4. An optimized calculation and analysis method for the recovery and utilization of drained and expanded steam according to claim 1, characterized in that The specific content of step (3) is as follows: Apply the mathematical model for quantitative calculation of the thermal energy and working medium recovery contained in the drain water, and the pricing relationship of steam price priced according to the specific enthalpy value, and adopt the optimization calculation model: MaxRecoveryFlowIncome = RecoveryFlowPrice × RecoveryFlow RecoveryFlowPrice = f(SteamEnthalpy) RecoveryFlow = g(pf) s.t. p0 < p f < p bl In the formula, RecoveryFlowIncome is the income of the recovered working medium (yuan / h), RecoveryFlowPrice is the price of the recovered working medium (yuan / t), SteamEnthalpy is the specific enthalpy value of the recovered working medium (kJ / kg), pf is the pressure of the recovered working medium (bar), RecoveryFlow is the flow rate of the recovered working medium (t / h), f() is the pricing relationship of steam price priced according to the specific enthalpy value, and g() is the dependence relationship between the flow rate of the recovered working medium and the pressure of the recovered working medium.

5. The optimized calculation and analysis method for the recovery and utilization of the steam with water drainage and volume expansion according to claim 3, characterized in that: In step (3), the optimization calculation is carried out in ascending order of the pressure pf of the recovered working medium to obtain the optimal state values of the pressure of the recovered flash steam and the income of the recovered working medium, as well as the change trend of the key indicators.

6. The optimized calculation and analysis method for recovering and utilizing the expanded steam by draining water according to claim 1, wherein, The specific content of step (4) is as follows: Apply the mathematical model for quantitative calculation of heat energy and working medium recovery contained in drainage, and the pricing relationship of steam priced by ratio value, and adopt the optimization calculation model: MaxRecoveryFlowIncome = RecoveryFlowPrice × RecoveryFlow RecoveryFlowPrice = h(SteamExergy) RecoveryFlow = i(pf) s.t. p0 < p f < p bl Where, RecoveryFlowIncome is the income from the recovered working fluid (yuan / h), RecoveryFlowPrice is the price of the recovered working fluid (yuan / t), SteamExerg is the specific value (kJ / kg), pf is the pressure of the recovered working fluid (bar), RecoveryFlow is the flow rate of the recovered working fluid (t / h), h() is the pricing relationship of steam priced by specific value, and i() is the dependence relationship between the flow rate of the recovered working fluid and the pressure of the recovered working fluid.

7. An optimized calculation and analysis method for the recovery and utilization of drained and expanded steam according to claim 5, characterized in that: In step (4), the optimization calculation is carried out in ascending order of the pressure pf of the recovered working medium to obtain the optimal state values of the pressure of the recovered flash steam and the income of the recovered working medium, as well as the change trend of the key indicators.

8. An optimized calculation and analysis method for hydrophobic drainage and steam recovery and utilization according to claim 1, characterized in that: In the step (5), the calculation results include the pressure of the recovered flash steam, the specific enthalpy value of the recovered flash steam, the ratio value, the temperature of the recovered flash steam, the dryness of the recovered flash steam, the working fluid recovery rate, the price of the recovered working fluid, and the revenue of the recovered working fluid.

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