CN114294708B - Method for adjusting heat storage of long-distance heat supply pipe network - Google Patents
Method for adjusting heat storage of long-distance heat supply pipe network Download PDFInfo
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Abstract
The invention discloses a method for adjusting heat storage of a long-distance heat supply pipe network operation, which relates to the technical field of urban long-distance heat supply, and comprises the steps of collecting structural size information and operation data of a pipe network and cleaning the data; establishing an energy conservation theoretical model, establishing a heat storage model, establishing an energy conservation artificial intelligence model, checking the obtained initial station water supply temperature, establishing a resistance characteristic model, judging whether the current pipeline total resistance meets the requirement, establishing a pressure characteristic numerical model, judging whether the current pressure characteristic numerical model meets the requirement, and outputting the water supply temperature for heat storage. The invention has simple operation method, reduces the work burden of operation operators, has high heat transfer efficiency, ensures the heat supply comfort of users, ensures a long-distance heat supply pipe network to prevent water hammer and reduces the energy consumption for conveying.
Description
Technical Field
The invention relates to the technical field of urban long-distance heat supply, in particular to a method for adjusting heat storage of a long-distance heat supply pipe network.
Background
The long-distance heat supply pipeline refers to a hot water pipe network with the length from a heat source to a main heat supply load area exceeding 20 km. The heating system usually includes a relay pump station, a relay energy source station or a pressure isolation heat exchange station, a long-distance heat supply pipeline and accessories, and the like. According to the regulation of 4.2.2 in the national industry Standard of the people's republic of China (design Specification for urban heating official network) (CJJ 34-2010): when the optimal supply and return water temperature is not met, the supply and return water temperature of the hot water pipe network can be determined according to the following principle: 1) When a thermal power plant or a large-scale regional boiler room is used as a heat source, the designed water supply temperature can be 110-150 ℃, and the return water temperature is not higher than 60 ℃; 2) The designed return water temperature of the long-distance pipeline is preferably 30-60 ℃. In order to embody the economical efficiency of long-distance pipeline network, large temperature difference heat supply is generally realized, and the temperature difference can even reach 80-100 ℃. Therefore, the long-distance conveying pipeline and the large temperature difference enable the long-distance heat supply pipe network to be a natural heat accumulator. But the time from the first station of the heat source to the user is too long due to the long conveying distance, and the heating time delay is too long. A new operation adjusting method is required to be provided according to the characteristics of the pipe network.
As urban heat supply for mainly consuming energy of buildings, long-distance or ultra-long-distance heat supply projects appear along with the continuous promotion of urbanization. For example, the Taiyuan ancient crossing project, the Jingneng Shengle project called and Haote City, and the Yinchuan project are 11 months in 2018. The long-distance heating projects have multiple operation modes, such as long-distance small temperature difference, long-distance large temperature difference, multi-heat-source networking and other system modes. The increase of pipe network heat supply distance, obvious hysteresis appears when the heat supply is adjusted, and the ageing nature of heat supply regulation is very poor. It is difficult to satisfy the demand of people on indoor heating temperature with high quality. For example, the project of long-distance heat supply in Yinchuan city is to supply heat from the national energy Ningxia Lingwu power plant about 41 km away from the main urban area in Yinchuan city. Under the design condition, the heat carried by the heat supply medium reaches the pressure isolation station in about 6 hours and then reaches the central station with the worst hydraulic working condition in about 8 hours. I.e. the heat from the power plant takes about 14 hours before reaching the most unfavourable end. Considering again the heat transfer to the end user, the lag time can even be as high as 18 hours. The traditional regulation method is obviously not beneficial to guaranteeing the heat supply quality, so some researchers discuss the heat storage mode to make up the hysteresis of heat supply regulation.
Patent document CN202110294128.3 "a balance adjusting method and heating system for heat storage and release of thermal power grid" discloses a balance adjusting method and heating system for heat storage and release of thermal power grid, and belongs to the technical field of centralized heating. The heating system comprises a thermoelectric unit, a heat supply network head station, a heat supply network circulating water pump, a heating power station, an electric regulating valve, a temperature and pressure flow measuring instrument, a temperature and flow measuring instrument, wherein the number of the heating power station is n, and n is more than or equal to 2; the heat loss scheduling of the heat supply system is calculated in real time, and the bypass is arranged on the primary network side of the heat station to adjust the water flow of the heat supply network entering the heat station, so that the heat supply load balance of each heat station is ensured, the dynamic balance of the operation of the heat supply network is achieved, the heat storage capacity of the heat supply system is exerted, the reliability of the balance adjustment of the heat supply system is improved, and the heat loss scheduling has high practical application value.
Patent document CN202020138251.7, "heat supply load adjustment system based on molten salt heat storage", discloses a heat supply load adjustment system based on molten salt heat storage. The system comprises a cold salt tank, a cold salt pump, a flue gas heater, a hot salt tank, a hot salt pump, a molten salt steam generator, a pipeline and a valve, wherein the pipeline is communicated with the units according to the process requirements; a steam heater is arranged between the cold salt pump and the flue gas heater connecting pipeline, a molten salt steam superheater is arranged between the hot salt pump and the molten salt steam generator connecting pipeline, and the molten salt steam superheater further comprises a steam heat exchange tube pass; and an outlet pipeline of the steam drum is communicated with a heat supply steam pipeline through a steam heat exchange tube pass of the molten salt steam superheater. The utility model discloses a system can deal with the undulant demand of steam load on a large scale in industrial park, both can provide technology production steam, also can provide overheated power steam.
Patent document CN201910953952.8 "a power station energy storage and heat supply peak-valley adjusting system and method" discloses a power station energy storage and heat supply peak-valley adjusting system. The device comprises a deaerator, a deaerator water tank, a deaerator water supply pipeline, a water tank water supply pipeline, a bypass adjusting pipeline, a steam balance pipeline and a steam supplementing pipeline; the deaerator is positioned at a high position, the lower end of the deaerator is connected with a water supply pipeline of the deaerator, and the deaerator water supply pipeline is used for supplying water to a boiler; the upper end of the deaerator is connected with the steam balance pipeline, the steam balance pipeline is respectively connected with the deaerating water tank and the steam supplementing pipeline, and the steam supplementing pipeline is connected to the heat supply main pipe; the deoxidization water tank is in the low level, the deoxidization water tank includes the box, the box upper end is provided with the admission valve, the admission valve is connected the steam balance pipeline, the box lower extreme is provided with the feed water valve, be connected with the hot-water pump on the feed water valve. The system has the advantages of stable operation, strong heat supply capability, high energy utilization rate, safety and environmental protection.
Patent document CN201921163432.9 "a building cooling and heating regulation system using aquifers and surface water", which discloses a building cooling and heating regulation system using aquifers and surface water, and comprises a building (a), a machine room (B), surface water (C), an aquifer energy storage well I (1) and an aquifer energy storage well II (2), wherein a tail end plate type heat exchanger (7), a plate type heat exchanger I (8) and a plate type heat exchanger II (9) are arranged in the machine room (B); and the tail end plate type heat exchanger (7), the first plate type heat exchanger (8) and the second plate type heat exchanger (9) are respectively communicated with the two water paths. The utility model discloses a do not need the water source heat pump, through the temperature variation who utilizes surface water, supplementary underground water-bearing stratum energy storage system according to the actual conditions of local climatic conditions, adjusts the cooling heating system of near building, utilizes natural resources ingeniously, has saved the energy consumption of building cooling heating.
Patent document cn201710213216.X "heat supply network adjusting method using heat supply network energy storage", discloses a heat supply energy storage technology of a power plant, and relates to a heat supply network energy storage technology and a heat supply network adjusting method for cooperative adjustment of a primary station and a secondary station. According to the adjusting method, the energy storage and heat release processes of the primary pipe network are respectively completed in the high-load stage and the low-load stage of the unit by controlling the temperature of supply and return water of the primary net and combining with the flow adjustment of the secondary net side bypass, so that the heat supply peak-shaving capacity of the thermoelectric unit is improved on the premise of ensuring the heating load in the heating period, and the consumption dilemma of renewable energy sources is effectively relieved.
Patent document CN201911334314.4 discloses a system and a method for implementing fine adjustment and multi-energy complementary transformation for heat supply. The invention is suitable for northern residents and public building areas, realizes the heat storage of the valley electricity or the direct heat supplement of the valley electricity by utilizing a large amount of valley electricity surplus of the solar-powered electric generator at night, and assists the heat supply of a heat supply network while realizing the full utilization of the valley electricity. The invention cancels the traditional heating station, arranges small heat exchange equipment in front of the building, realizes the fine adjustment of building heat supply by heating building heat supply media through the heat exchange equipment, and solves the problem of imbalance between buildings. The invention realizes electric heat storage by using the electrode boiler and the heat storage tank, and is arranged in parallel with a building unit to supply heat to a building. The invention can enlarge the heat supply area under the condition of not changing the capacity of a pipe network and a heat source.
The above patents discuss methods for heat storage or regulation in a heat supply network, which basically employ external systems or devices for heat storage.
For example, in patent document CN202110294128.3, "a balance adjusting method for heat storage and release of heat supply network and a heat supply system", a bypass is provided on a primary network side of a heat station to adjust the flow rate of water entering the heat network of the heat station. Patent document CN202020138251.7 "heat supply load regulation system based on molten salt heat storage" adopts a molten salt heat storage system. Patent document CN201921163432.9 "a building cooling and heating regulation system using aquifers and surface water" utilizes aquifers and surface water. Patent document CN201911334314.4, a system and method for implementing fine adjustment and multi-energy complementary transformation of heat supply, utilizes valley electricity to store heat.
These patents add heat storage devices, i.e. increase initial investment, and also need to consider the problems of equipment occupation and subsequent system maintenance. Thus, prior to implementation, demonstration is also required.
Patent document CN201910953952.8 discloses a power station energy storage and heat supply peak-valley adjusting system and method, and the system comprises a deaerator, a deaerator water tank, a deaerator water supply pipeline, a water tank water supply pipeline, a bypass adjusting pipeline, a steam balance pipeline and a steam supplementing pipeline; the deaerator is positioned at a high position, the lower end of the deaerator is connected with a water supply pipeline of the deaerator, and the deaerator water supply pipeline is used for supplying water to a boiler; the upper end of the deaerator is connected with the steam balance pipeline, the steam balance pipeline is respectively connected with the deaerating water tank and the steam supplementing pipeline, and the steam supplementing pipeline is connected to the heat supply main pipe; the deoxidization water tank is in the low level, the deoxidization water tank includes the box, the box upper end is provided with the admission valve, the admission valve is connected the steam balance pipeline, the box lower extreme is provided with the feed water valve, be connected with the hot-water pump on the feed water valve. The system has the advantages of stable operation, strong heat supply capacity, high energy utilization rate, safety and environmental protection.
Patent document cn201710213216.X "heat supply network adjusting method using heat supply network energy storage", discloses a heat supply energy storage technology of a power plant, and relates to a heat supply network energy storage technology and a heat supply network adjusting method for cooperative adjustment of a primary station and a secondary station. According to the adjusting method, the energy storage and heat release processes of the primary pipe network are respectively completed at the high load stage and the low load stage of the unit by controlling the temperature of supply and return water of the primary network and combining with the flow adjustment of the secondary network side bypass, so that the heat supply peak regulation capacity of the thermoelectric unit is improved on the premise of ensuring the heating load in the heating period, and the consumption predicament of renewable energy is effectively relieved.
In the above two patents, no heat storage device is added, and as in patent document CN201910953952.8, a power station energy storage and heat supply peak and valley regulation system and method, a power plant oxygen removal device is regulated. Patent document cn201710213216.X "a heat supply network regulating method using heat supply network energy storage" uses a primary station and a secondary station to cooperatively regulate energy storage.
But does not solve the problem of regulation lag existing in the long-distance heat supply pipe network. In particular, patent document cn201710213216.X, "a heat supply network adjusting method using energy storage of a heat supply network", compares values between a maximum heat supply load P1 of a unit and a heat load P2 of a heat consumer to determine the storage of heat in the heat supply network. The adjusting method is suitable for occasions with nearby heat supply, such as the delivery range of 2.5h of the specific patent embodiment. If the time delay can reach 18 hours according to the time delay of the long-distance heat supply pipe network in Yinchuan, the heat release of the pipe network during the heat storage can occur by applying the method, and the heat storage can occur during the heat release. Since basically most of the heat supplied by the plant will reach the users in around 12 hours. That is, the heat supplied by the midday power plant can only reach the user in the morning.
At present, for a long-distance heat supply pipe network, because the occurrence time is short, rich operation experience is not accumulated, and a new operation adjusting method needs to be provided.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for regulating the heat storage of the long-distance heat supply pipe network operation, which is simple in operation method, high in heat transfer efficiency, capable of reducing the work burden of operation operators, guaranteeing the heat supply comfort of users, ensuring that the long-distance heat supply pipe network prevents water hammer and reduces the energy consumption for conveying.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method for regulating heat storage of long-distance heat supply pipe network operation comprises the following steps:
step S101: collecting the structural size information of a pipe network;
step S102: collecting operation data of a pipe network;
step S103: cleaning the acquired data;
step S104: establishing a theoretical model of energy conservation of the long-distance transmission pipe network;
step S105: establishing a heat storage model of the long-distance pipeline network, wherein the step S105 comprises the following steps: dividing the whole heating period into a plurality of stages according to the outdoor environment temperature; the dividing basis is that a data mining mode is usually adopted, and the outdoor temperature of a heat supply object is subjected to statistical classification; during each determined heating stage, the data is mined to obtain the distribution of the circulating water flow; the heat storage capacity of the pipe network is the heat corresponding to the maximum temperature and flow designed by the pipe network, and the heat corresponding to the normal operation temperature and flow is subtracted;
step S106: establishing an artificial intelligence model of energy conservation of the long-distance transmission pipe network, wherein in the step S106, the temperature of circulating water leaving a heat supply initial station of the thermal power plant is obtained by adopting the artificial intelligence model according to the scheduled load, the thermoelectric proportion, the outdoor environment temperature and other parameters in combination with equipment of the thermal power plant;
step S107: verifying the obtained first station water supply temperature;
step S108: establishing a resistance characteristic model of the long-distance pipeline network, calculating the total resistance of the pipeline, and determining that the specific friction resistance of the pipeline does not exceed a set value;
step S109: calculating the current total resistance of the pipeline and calculating the specific friction resistance of the pipeline; if the specific friction resistance is smaller than the design value of the long-distance pipeline, the step S110 is proceeded; if the calculated specific friction resistance is larger than the design value of the long-distance pipeline, returning to the step S106;
step S110: establishing a numerical model of the pressure characteristic of the long-distance pipeline network;
step S111: according to the calculation result, if two states of overhigh pressure and overlow pressure of the pipeline exist, overhigh pressure refers to the pressure exceeding 1.3-1.5 times of the design pressure of the pipeline, and overlow refers to the temperature lower than the calculation point minus the saturated vapor pressure corresponding to 5 degrees; if these phenomena exist, return to step S106; if these phenomena do not exist, the process proceeds to step S112, and the calculation ends;
step S112: and finally outputting the water supply temperature for heat storage.
The technical scheme of the invention is further improved as follows: in step S103, the data is examined and verified, and erroneous data is deleted or corrected, including: removing the data marked by 'Failure', removing the data which is not displayed, removing unreasonable data, analyzing the variation rate of the acquired data, and analyzing the data with the variation rate of the acquired data value higher than 5% before and after analysis.
The technical scheme of the invention is further improved as follows: the amount of heat transferred by the thermal power plant to the circulating water in the long transport pipeline in step S104 can be expressed as:
Q 1,pt ＝G cw c cw (T out,pt -T in,pt )
in the formula, Q1 and pt are heat transferred to circulating water in a long-distance pipeline by a thermal power plant, and Gcw is the flow of the circulating water; ccw is the specific heat capacity of water; tout, pt and Tin, pt are respectively the temperature of the circulating water leaving and entering a heating initial station of the thermal power plant;
if the peak shaving boiler exists, the heat transferred to the circulating water in the long-distance pipeline by the thermal power plant is counted;
the user side exchanges heat through circulating water in the pressure isolation station and the long-distance pipeline, and the heat exchange is determined by the following formula:
Q 2,user ＝G user c user (T out,pis -T in,pis )
in the formula, Q2 and user are the heat exchanged between the user side and the circulating water in the long-distance pipeline through the pressure isolation station, and Guser is the flow of the circulating water at the user side; the cuser is the specific heat capacity of the circulating water at the user side; tout, pis and Tin, pis are respectively the temperature of circulating water at the user side when the circulating water leaves and enters the pressure insulation station;
the heat exchange of the circulating water in the pressure isolation station and the long-distance pipeline at the user side can meet the heat load requirement of the user, and the heat load Q3 of the user is as follows:
Q 3 ＝f(T user,set -T surrouding )
in the formula, tuser, set and Tsurroundding are respectively the indoor set temperature and the outdoor ambient temperature of the user, and f represents a relation function;
when the outdoor environment temperature is higher than a certain value, the long-distance pipeline network has heat storage capacity when the outlet water temperature of the heat supply primary station does not need to reach the designed highest temperature;
the heat stored in the long-distance pipeline network is determined by the following formula:
Q storage ＝Q 1,pt -Q 2,user 。
the technical scheme of the invention is further improved as follows: the calculation of the on-way resistance loss of the pipeline in the step S108 adopts a Darcy-Weisbach formula,
in the formula, delta H is resistance loss, lambda is a friction resistance coefficient, L is the length of the pipe, D is the diameter of the pipe, V is the flow velocity in the pipe, and g is the gravity acceleration;
the calculation formula of the friction resistance coefficient lambda is most accurate to be a Colebrook-White formula,
in the formula, epsilon is the equivalent roughness of the inner wall of the pipeline; d is the diameter of the pipeline; re is Reynolds number;
the Colebrook-White formula is an implicit equation;
for a long-distance pipeline network, the friction resistance coefficient lambda can be applied to the following formula;
in the formula, re is a Reynolds number, and C5 is a calculation correction variable;
the calculation process of C5 is as follows: first calculate A5, then B5, and finally C5:
due to the adoption of the technical scheme, the invention has the technical progress that:
the operation method is simple, only one temperature of the water supply temperature of the first station needs to be controlled, and the work burden of operation operators is greatly reduced.
The invention has high heat transfer efficiency, ensures the heat supply requirement of users in all operation time, has the elastic capacity of improving the indoor heating temperature, and ensures the heat supply comfort of the users.
And can also guarantee the long-distance heat supply pipe network prevents the water hammer and reduces and carries the energy consumption, operate under safe, economic condition, still have the characteristics that improve the economic nature of steam power plant simultaneously.
Drawings
Fig. 1 is a schematic block diagram of the present invention.
Detailed Description
The present invention is further illustrated in detail below with reference to examples:
as shown in figure 1 of the drawings, in which,
step S101: collecting information such as the structure size of a pipe network, such as the length, the diameter and the material of a pipeline; the length, the trend, the gradient and the elevation of each point of the pipe network; the positions and detailed parameters of the relay station, the pressure isolation station and the heating station; pump, valve, etc. details; and the like.
The collected information should be comprehensive. The structural parameters are fixed data, typically provided by a design unit. After receiving the data, the data needs to be checked. Especially, the elevation difference of the pipe network is the elevation of each point of the pipe network. This has a very large impact on the safe operation of the pipe network.
Step S102: collecting operation data of a pipe network, such as ambient temperature; the inlet and outlet temperatures of each important node; pressure of the critical area; the flow rate of each main pipe; a water replenishing access point and flow thereof; water tank level; opening degree of the valve; current, voltage and frequency of each pump; etc.;
all collected data should have a time tag, the collected data are in the csv format of Excel, one column of the collected data is time, and the data at the same time are put together to be gathered in a row. Because data acquisition systems have many sources and very different storage formats, time tags of data must be coupled with data when the data is summarized.
Some data is automatically collected and some data is manually input. Either way, the time of data acquisition is specified.
The data is finally summarized into a database. The database may be conventional, such as Oracle, SQL Server, mySQL, access, infilxdb, etc. One of them is selected. And form a summary csv file. This file is the basic file for subsequent operations.
Step S103: and carrying out data cleaning on the acquired data. When the long-distance pipeline network runs, the fluctuation of data is relatively stable due to thermal inertia. But the measuring points can cause the data to deviate from the real situation for various reasons. Such as the temperature of the fluid in the temperature tube, loosens, resulting in a measured value that is not the temperature of the fluid in the tube, but the ambient air.
Therefore, data is required to be examined and checked, and erroneous data is deleted or corrected, so as to ensure the quality of the data. Data identified by 'Failure' is removed, data not displayed is removed, and particularly unreasonable data is removed. Such as temperature shown at-2000 degrees or 5000 degrees, etc.; as described below.
Especially, the change rate of the acquired data needs to be analyzed, and the data with the change rate of the acquired data value higher than 5% before and after the data is focused. If the temperature of the first station water supply is generally between 110 and 150 ℃, if the verification of the temperature data collected twice is higher than 5.5 ℃, the possible generation reasons of the data are analyzed.
According to the first law of thermodynamics, energy is not generated or lost by air space. The heat input and output of each node of the pipeline are balanced and equal. And checking and calculating the temperature measuring points according to the principle that the total heat quantity is equal.
For the pressure measuring point, because the pipeline may leak and the pressure wave occurs, when the data change rate is high, the position of the measuring point should be firstly checked to eliminate the fault reason. For the leakage to be caused, the maintenance should be performed in time.
Step S104: and establishing a theoretical model of energy conservation of the long-distance transmission pipe network. The energy transfer of the long-distance pipeline network mainly comprises three links, namely, a thermal power plant transfers heat to circulating water in a long-distance pipeline through a heat supply first station; circulating water is pressurized by a circulating pump and circularly flows in the long-distance pipeline; the user side exchanges heat with the circulating water in the long-distance pipeline through the pressure isolation station.
The heat transferred by the thermal power plant to the circulating water in the long transmission pipeline can be expressed as:
Q 1,pt ＝G cw c cw (T out,pt -T in,pt )
in the formula, Q 1,pt Heat transferred to the circulating water in the long-distance pipeline of the thermal power plant, G cw Is the flow of the circulating water; c. C cw Is the specific heat capacity of water; t is out,pt And T in,pt Respectively the temperature of the circulating water leaving and entering the thermal power plant heating primary station.
In some cases, peak shaving boilers are available, and if the peak shaving boilers are available, the heat transferred to the circulating water in the long-distance pipeline by the thermal power plant is counted.
The user side exchanges heat through circulating water in the pressure isolation station and the long-distance pipeline, and the heat exchange is determined by the following formula:
Q 2,user ＝G user c user (T out,pis -T in,pis )
in the formula, Q 2,user For exchanging heat at the user side by means of the pressure-isolating station and the circulating water in the long-distance pipeline, G user The flow of circulating water at the user side is obtained; c. C user Is the specific heat capacity of the circulating water at the user side; t is a unit of out,pis And T in,pis The temperatures of the circulating water at the user side leaving and entering the pressure insulation station respectively.
The heat exchange between the pressure isolation station and the circulating water in the long-distance pipeline at the user side can meet the heat load requirement of the user, and the heat load Q of the user 3 Comprises the following steps:
Q 3 ＝f(T user,set -T surrouding )
in the formula, T user,set And T surroundingt Respectively the temperature set indoors and the ambient temperature outdoors for the user. In the formula, f represents the corresponding relation function.
Because the temperature set by the user indoor is a range, generally 16-20 ℃, and the outdoor temperature greatly fluctuates. Meanwhile, the building structure has thermal inertia, so that the thermal load of a user is difficult to accurately calculate at any time, and the calculation deviation is normal.
In any case, however, it should be ensured that the heat exchanged on the user side by the pressure-insulated station and the circulating water in the long-distance line is greater than the current heat load of the user.
The water supply and return temperature of the long-distance pipeline network is within a range, and the water supply temperature is designed to be 110-150 ℃. This is also determined by the location and parameters of the plant extraction.
When the outdoor environment temperature is higher than a certain value, the long-distance pipeline network has heat storage capacity when the outlet water temperature of the heat supply primary station does not need to reach the designed highest temperature.
The heat stored in the long-distance pipeline network is determined by the following formula:
Q storage ＝Q 1,pt -Q 2,user
it should be noted, however, that the two heats are not at the same time.
Step S105: and establishing a heat storage model of the long-distance pipeline network. The heat storage capacity of the pipe network is the heat corresponding to the maximum temperature and flow designed by the pipe network, and the heat corresponding to the normal operation temperature and flow is subtracted) the heat storage is that the power plant passes through the first station to store the heat to the long-distance pipe network in advance. The heat storage of the long-distance pipeline network is usually realized by increasing the water supply temperature or increasing the circulating flow.
In the present invention, the way of implementation is as follows:
firstly, dividing the whole heating period into a plurality of stages according to the temperature of outdoor environment: the initial cold period, the severe cold period, the final cold period or more heat supply periods. There are generally three stages. But for particularly cold cities, more stages can be divided.
The dividing basis is usually data mining, and the statistical classification is carried out on the outdoor temperature of the heat supply object.
At each heating stage determined, the data is then mined to derive a distribution of circulating water flow. The flow rates of the circulating water in different heating periods are usually different.
The heat storage capacity of the pipe network is the heat corresponding to the maximum temperature and flow designed by the pipe network, and the heat corresponding to the normal operation temperature and flow is subtracted.
The upper limit of the amount of heat stored in each pipe network is therefore constant. For a long-distance pipeline network, the heat storage capacity is large, mainly the pipe diameter is large, so the flow of circulating water is large; the temperature difference is large; and also has large amount.
Step S106: and establishing an artificial intelligence model of energy conservation of the long-distance transmission pipe network, and eliminating the consequences caused by time delay.
According to the data collected on site, the temperature T of the circulating water leaving the heat supply primary station of the thermal power plant out,pt Is an output parameter; other data collected, such as load of the plant, outdoor ambient temperature, temperature of the incoming heat supply head of the thermal power plant, temperature of the user-side circulating water leaving the pressure-insulated plant, temperature of the user-side circulating water entering the pressure-insulated plant, current of the circulating water pumps, frequency of the circulating water pumps, current of the water supply pumpsFrequency, circulating water flow, water replenishing flow, water supplying pressure, water returning pressure, front and back pressures of pumps and the like are used as input parameters; and establishing an artificial intelligence model by adopting a neural network.
The flow rate in the pipe is constantly changed due to different loads and different working states of the pumps. The flow rate is generally designed to be 3m/s, but during normal operation, the flow rate fluctuates greatly, the lower flow rate is 1-2 m/s, the higher flow rate is 2-3 m/s, and the difference between the flow rate and the lower flow rate is even more than one time.
Because the long-distance transmission of the long-distance transmission pipe network is long, the time from the first station to the user side of the pressure-isolating station is not a fixed value. Or the time of the circulating water from the first station to the user side is constantly fluctuating. The maximum and minimum values differ by more than a factor of two.
If a theoretical model is simply adopted, it is difficult to accurately calculate the time from the initial station to the user side of the pressure isolation station. It is therefore necessary to build an artificial intelligence mathematical model to establish a function of the initial station temperature, i.e. the heat source output.
For heating, the more data the neural network, the more accurate the relative model. Therefore, it is necessary to accumulate operational data of the past year for modeling and model training.
The thermal power plant has an electric quantity scheduling plan, and the overall efficiency of the power plant is improved as much as possible according to the plan and the thermoelectric proportion.
In actual operation, according to the scheduled load, the thermoelectric proportion, the outdoor environment temperature and other parameters, in combination with the equipment reality of the thermal power plant, an artificial intelligence model is adopted to obtain the temperature of the circulating water leaving the heat supply primary station of the thermal power plant.
Step S107: and verifying the obtained first station water supply temperature. If the temperature of the first station water supply is lower than 110 ℃ or higher than 150 ℃, the calculation parameters are adjusted, and the step S106 is returned to calculate again. If the obtained temperature of the first station water supply is between 110-150 ℃, the process proceeds to step S108.
Step S108: and establishing a resistance characteristic model of the long-distance pipeline network. And calculating the total resistance of the pipeline and determining that the specific friction resistance of the pipeline does not exceed a set value.
The on-way resistance loss calculation of pipeline transportation adopts Darcy-Weisbach formula,
in the formula, Δ H is resistance loss, λ is frictional resistance coefficient, L is tube length, D is tube diameter, V is in-tube flow velocity, and g is gravitational acceleration.
The calculation formula of the friction resistance coefficient lambda is most accurate to be a Colebrook-White formula,
wherein epsilon is the equivalent roughness of the inner wall of the pipeline, and the equivalent roughness of the inner wall of the pipeline is recommended to be 0.5mm in the design specification of urban heat supply pipe network CJJ 34-2010; d is the diameter of the pipeline; re is Reynolds number.
The Colebrook-White formula is an implicit equation, and the solving process is extremely complicated. Therefore, many scholars propose dozens of improvement methods aiming at the approximate solution of the Colebrook-White formula.
For long-distance pipe networks, the frictional resistance coefficient λ can be applied as follows.
Wherein Re is Reynolds number, C 5 To calculate the correction variables.
C 5 The calculation process of (2) is as follows: first calculate A 5 Then calculate B 5 And finally calculating C 5 ：
Step S109: and calculating the current total resistance of the pipeline and calculating the specific friction resistance of the pipeline. If the specific friction resistance is smaller than the design value of the long-distance pipeline, the process proceeds to step S110. If the calculated specific friction resistance is larger than the design value of the long-distance pipeline, the step S106 is returned to.
Step S110: a numerical model of the pressure characteristic is established. If a continuity equation, a momentum equation, an energy equation and the like are established, the water hammer phenomenon is prevented, and the running safety of a pipe network is guaranteed.
In the operation of a long-distance heat supply pipe network, due to the opening and closing of valves and pumps required by the weather change of high and low terrains and multiple ends in different regions, safety problems can occur in the operation, wherein water hammer impact is the most important phenomenon.
Once the water hammer occurs, a pressure wave rapidly propagates in the pipe at a very high velocity, and thus an oscillation phenomenon occurs. The heat supply pipe network for long-distance conveying of high-temperature water is particularly easy to generate water hammer problem, and the water hammer accident can cause super strong destructive power in serious conditions, so that engineering accidents and casualties are very likely to occur.
Thus, data mining is used to monitor where water hammer may occur. Particularly pressure fluctuations due to vaporization phenomena caused by the partial vacuum.
And meanwhile, the states of over-high pressure and over-low pressure of the pipeline are analyzed by adopting numerical simulation.
Step S111: according to the calculation result, if two states of overhigh pressure and overlow pressure of the pipeline exist, overhigh pressure means that the pressure exceeds 1.3-1.5 times of the design pressure of the pipeline, and overlow pressure means that the temperature is lower than the saturated vapor pressure corresponding to the temperature minus 5 ℃ at the calculation point. If these phenomena exist, return is made to step S106. If these phenomena do not exist, the process proceeds to step S112, and the calculation ends.
Step S112: and finally obtaining the water supply temperature for heat storage. This is also the control target for system operation. The temperature of the existing circulating water leaving the heat supply primary station of the thermal power plant is adjusted to the calculated water supply temperature, and the heat storage adjustment operation of the long-distance pipe network can be completed.
The heat storage regulation mainly regulates the temperature and the flow, and the invention takes the temperature as a regulation means. There are also flow regulating devices, as described in the aforementioned patent documents. However, the resistance characteristics change greatly due to the actual field, and water hammer and other problems are easy to occur. So the temperature is currently regulated. In the field of temperature regulation, the invention firstly proposes a way of regulating the temperature of the first-station effluent.
Those skilled in the art will appreciate that variations may be implemented by those skilled in the art in combination with the prior art and the above-described embodiments, and will not be described in detail herein. Such variations do not affect the essence of the present invention and are not described herein.
The above description is of the preferred embodiment of the invention. It is to be understood that the invention is not limited to the particular embodiments described above, in which devices and structures not described in detail are understood to be implemented in a manner that is conventional in the art; it will be understood by those skilled in the art that various changes and modifications may be made, or equivalents may be modified, without departing from the spirit of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.
Claims (4)
1. A method for regulating heat storage of long-distance heat supply pipe network operation is characterized in that: the method comprises the following steps:
step S101: collecting structural size information of a pipe network;
step S102: collecting operation data of a pipe network;
step S103: cleaning the acquired data;
step S104: establishing a theoretical model of energy conservation of the long-distance transmission pipe network;
step S105: establishing a heat storage model of the long-distance pipeline network, wherein the step S105 comprises the following steps: dividing the whole heating period into a plurality of stages according to the outdoor environment temperature; the dividing basis is that a data mining mode is usually adopted, and the outdoor temperature of a heat supply object is subjected to statistical classification; during each determined heating stage, the data is mined to obtain the distribution of the circulating water flow; the heat storage capacity of the pipe network is the heat corresponding to the maximum temperature and flow designed by the pipe network, and the heat corresponding to the normal operation temperature and flow is subtracted;
step S106: establishing an artificial intelligence model of energy conservation of the long-distance transmission pipe network, wherein in the step S106, the temperature of circulating water leaving a heat supply initial station of the thermal power plant is obtained by adopting the artificial intelligence model according to the scheduled load, the thermoelectric proportion, the outdoor environment temperature and other parameters in combination with equipment of the thermal power plant;
step S107: verifying the obtained first station water supply temperature;
step S108: establishing a resistance characteristic model of the long-distance pipeline network, calculating the total resistance of the pipeline, and determining that the specific friction resistance of the pipeline does not exceed a set value;
step S109: calculating the current total resistance of the pipeline and calculating the specific friction resistance of the pipeline; if the specific friction resistance is smaller than the design value of the long-distance pipeline, the step S110 is proceeded; if the calculated specific friction resistance is larger than the design value of the long-distance pipeline, returning to the step S106;
step S110: establishing a numerical model of the pressure characteristic of the long-distance pipeline network;
step S111: according to the calculation result, if two states of overhigh pressure and overlow pressure of the pipeline exist, overhigh pressure means that the pressure exceeds 1.3-1.5 times of the design pressure of the pipeline, and overlow pressure means that the temperature is lower than the calculation point and the saturated vapor pressure corresponding to the temperature minus 5 degrees is obtained; if these phenomena exist, return to step S106; if these phenomena do not exist, the process proceeds to step S112, and the calculation ends;
step S112: and finally outputting the water supply temperature for heat storage.
2. The method for regulating the heat storage of the long-distance heat supply pipe network operation according to claim 1, wherein the method comprises the following steps: in step S103, the data is examined and checked, and erroneous data is deleted or corrected, including: removing the data marked by 'Failure', removing the data which is not displayed, removing unreasonable data, analyzing the variation rate of the acquired data, and analyzing the data with the variation rate of the acquired data value higher than 5% before and after analysis.
3. The method for regulating the heat storage of the long-distance heat supply pipe network operation according to claim 1, wherein the method comprises the following steps: the amount of heat transferred by the thermal power plant to the circulating water in the long transport pipeline in step S104 can be expressed as:
Q 1,pt ＝G cw c cw (T out,pt -T in,pt )
in the formula, Q1 and pt are heat transferred to circulating water in a long-distance pipeline by a thermal power plant, and Gcw is the flow of the circulating water; ccw is the specific heat capacity of water; tout, pt and Tin, pt are respectively the temperature of the circulating water leaving and entering a heating initial station of the thermal power plant;
if the peak shaving boiler exists, the heat transferred to the circulating water in the long-distance pipeline by the thermal power plant is counted;
the heat exchange between the user side and the circulating water in the long-distance pipeline through the pressure isolation station is determined by the following formula:
Q 2,user ＝G user c user (T out,pis -T in,pis )
in the formula, Q2 and user are the heat exchanged between the user side and the circulating water in the long-distance pipeline through the pressure isolation station, and Guser is the flow of the circulating water at the user side; cuser is the specific heat capacity of circulating water at the user side; tout, pis and Tin, pis are respectively the temperature of circulating water at the user side leaving and entering the pressure isolation station;
the heat exchange of the user side through the pressure isolation station and the circulating water in the long-distance transmission pipeline can meet the heat load requirement of the user, and the heat load Q3 of the user is as follows:
Q 3 ＝f(T user,set -T surrouding )
in the formula, tuser, set and Tsurrounding are respectively the indoor set temperature and the outdoor ambient temperature of the user, and f represents a relation function;
when the outdoor environment temperature is higher than a certain value, the long-distance pipeline network has heat storage capacity when the outlet water temperature of the heat supply primary station does not need to reach the designed highest temperature;
the heat stored in the long-distance pipeline network is determined by the following formula:
Q storage ＝Q 1,pt -Q 2,user 。
4. the method for regulating the heat storage of the long-distance heat supply pipe network operation according to claim 1, wherein the method comprises the following steps: the calculation of the on-way resistance loss of the pipeline transportation in the step S108 adopts Darcy-Weisbach formula,
in the formula, delta H is resistance loss, lambda is a friction resistance coefficient, L is the length of the pipe, D is the diameter of the pipe, V is the flow velocity in the pipe, and g is the gravity acceleration;
the calculation formula of the friction resistance coefficient lambda is most accurate to be a Colebrook-White formula,
wherein epsilon is the equivalent roughness of the inner wall of the pipeline; d is the diameter of the pipeline; re is Reynolds number;
the Colebrook-White formula is an implicit equation;
for a long-distance pipeline network, the friction resistance coefficient lambda can be applied to the following formula;
in the formula, re is a Reynolds number, and C5 is a calculation correction variable;
the calculation process of C5 is as follows: first calculate A5, then B5, and finally C5:
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