CN103234120A - Peak pitching method and device based on utilization of pressure energy of high-pressure natural gas pipeline - Google Patents

Abstract

With the continuous development of natural gas technology, the pressure of natural gas pipeline network transmission is getting higher and higher. A large amount of pressure energy will be generated during throttling and pressure regulation of high-pressure natural gas pipeline network, and most of the pressure energy will not only be wasted, but also cause certain cold damage to downstream pipeline equipment. To this end, starting from the utilization of the pressure energy of high-pressure natural gas, combined with the storage characteristics of natural gas, the pressure energy is used for power generation, and a peak-shaving device based on the utilization of pressure energy of the high-pressure natural gas pipeline network is developed to effectively improve energy utilization and realize It improves the economy of the pipeline network operation and solves the peak-shaving problem of the urban pipeline network and power grid.

Description

A peak shaving method and device based on the utilization of natural gas high pressure pipeline network pressure energy

technical field

The invention belongs to the technical field of oil and gas storage and transportation engineering, and in particular relates to a gas storage peak-shaving method and a device for utilizing the pressure energy of a natural gas high-pressure pipeline network.

Background technique

In recent years, with the intensification of natural gas development in my country and the continuous growth of user demand, the construction of natural gas pipelines in my country has developed rapidly. Marked by the launch of the Second West-East Gas Pipeline, my country's natural gas pipeline network has officially entered a stage of rapid development. High-pressure gas transmission can reduce the diameter of pipelines and save pipe materials and construction costs. Therefore, high-pressure transmission is generally used in long-distance natural gas pipelines in the world.

The high-pressure natural gas pipeline network contains a large amount of pressure energy, and the high-pressure natural gas needs to be adjusted at various gate stations or pressure regulating stations. In the traditional pressure regulation process, high-pressure natural gas expands adiabatically through the throttle valve, the pressure decreases, and a small amount of cold energy is generated at the same time. In this pressure regulating process, a large amount of mechanical energy is converted into cold energy. But this part of cooling energy is wasted in vain, and may also bring danger to the operation of pipelines and pressure regulating equipment. Therefore, recovering this part of pressure energy can not only improve the economy of high-pressure pipeline network operation, but also eliminate cold damage to downstream pipelines. At the same time, the cold energy generated by the expansion of high-pressure natural gas is used for power generation, which improves the energy utilization rate.

的分析对方案作出一定的验证，

分析法为高压天然气压力能利用的深入研究打下了良好的研究基础，也为热力学完善性提供了系统的评价判据。火用代表了热力系统做功能力，效率则是描述系统热力过程完善程度的最佳指标，同时也自然成为了分析和判定系统运行是否合理的关键性参数。Since the beginning of this century, the research on the utilization of natural gas pressure energy has mainly relied on

The analysis of the program makes a certain verification,

The analysis method has laid a good research foundation for the in-depth study of the utilization of the pressure energy of high-pressure natural gas, and also provided a systematic evaluation criterion for the perfection of thermodynamics. Exergy represents the working ability of the thermal system, Efficiency is the best indicator to describe the completeness of the thermal process of the system, and it has naturally become a key parameter for analyzing and judging whether the system operation is reasonable.

In the urban natural gas transmission and distribution system, the demand of various gas users is constantly changing, and the gas supply is unstable. Therefore, in order to ensure the continuity of gas supply and the balance between gas supply and gas consumption, the characteristics of high-pressure natural gas transmission are used to combine pressure energy recovery with pipeline peak regulation to solve the problem of urban gas storage peak regulation and ensure the safety of gas , Smooth and sustainable delivery to users.

Contents of the invention

The object of the invention is a peak-shaving device based on the utilization of natural gas high-pressure pipeline network pressure energy. Through the joint application of high-pressure pipe network pressure energy and pipeline peak regulation, it not only realizes the safe storage and peak regulation of pipe network and power grid, but also promotes the development of cold energy utilization industry, improves energy utilization rate, and maximizes economic benefits.

The technical scheme of the present invention is as follows: it is characterized in that:

The natural gas enters the conventional natural gas gate station from the high-pressure natural gas pipeline, and the initial pressure is 6-10MPa. After passing through the three-way valve, the high-pressure natural gas is divided into two streams a and b. The a-share natural gas that meets the instantaneous demand of the urban pipeline network is expanded and refrigerated by the expansion refrigeration equipment, the pressure drops to 0.5-1.6MPa, and the temperature drops to -110--49°C. This process produces a large amount of cold energy. The low-temperature natural gas and the refrigerant exchange cold energy in the heat exchanger, and the temperature is raised to 5°C and enters the urban pipe network; the temperature of the refrigerant drops to -30-0°C and is stored in a low-temperature refrigerant storage tank.

When the gas consumption is low, the b-share natural gas with excess instantaneous demand is stored in the high-pressure gas storage tank; when the gas consumption is peak, the high-pressure natural gas stored in the high-pressure gas storage tank is operated as above to achieve the effect of peak shifting and filling the valley, and solve the peak demand gas problem. The cold stored in the low-temperature refrigerant storage tank is sent to the air-conditioning unit to exchange heat with the environment along with the refrigerant, and the refrigerant after heat exchange is returned to the normal-temperature refrigerant storage tank, and the refrigerant is recycled. It not only reduces the power consumption of the urban power grid, solves the problem of utilizing the pressure energy of the high-pressure natural gas pipeline network, but also realizes the peak-shaving function of the urban pipeline network and power grid.

The above-mentioned system uses the pressure energy peak-shaving device reasonably and efficiently, which can effectively recover the pressure energy of the high-pressure pipeline network and use it for power generation. The comprehensive utilization rate of energy has a certain advanced nature in today's increasingly tense energy situation and the promotion of a conservation-oriented society.

Advantages of the invention

The invention has the advantages of simple flow, less equipment, flexible adjustment, reliable operation, easy starting, convenient operation and maintenance, and low operating cost. Making full use of the pressure energy of natural gas in high-pressure gas transmission pipelines can also solve the problem of daily and hourly peak regulation of city gas.

Description of drawings

Fig. 1 is the present invention based on natural gas high-pressure pipeline network pressure energy utilization peak-shaving device and technological process schematic diagram;

Detailed ways

Below in conjunction with accompanying drawing and embodiment mode, the patent of the present invention is described in further detail:

The patent of the present invention specifically relates to a peak-shaving device based on the utilization of natural gas high-pressure pipeline network pressure. Natural gas enters a conventional natural gas gate station from a high-pressure natural gas pipeline, and the initial pressure is 6-10 MPa. After passing through a three-way valve, the high-pressure natural gas is divided into a, b two shares. The a-share natural gas that meets the instantaneous demand of the urban pipeline network is expanded and refrigerated by the expansion refrigeration equipment, the pressure drops to 0.5-1.6MPa, and the temperature drops to -110--49°C. This process produces a large amount of cold energy. The low-temperature natural gas and the refrigerant exchange cold energy in the heat exchanger, and the temperature is raised to 5°C and enters the urban pipe network; the temperature of the refrigerant drops to -30-0°C and is stored in a low-temperature refrigerant storage tank.

When the gas consumption is low, the b-share natural gas with excess instantaneous demand is stored in the high-pressure gas storage tank; when the gas consumption is peak, the high-pressure natural gas stored in the high-pressure gas storage tank is operated as above to achieve the effect of peak shifting and filling the valley, and solve the peak demand gas problem. The cold stored in the low-temperature refrigerant storage tank is sent to the air-conditioning unit to exchange heat with the environment along with the refrigerant, and the refrigerant after heat exchange is returned to the normal-temperature refrigerant storage tank, and the refrigerant is recycled. It not only reduces the power consumption of the urban power grid, solves the problem of utilizing the pressure energy of the high-pressure natural gas pipeline network, but also realizes the peak-shaving function of the urban pipeline network and power grid. The detailed plan is as follows, and the devices used include: natural gas gate station (1), three-way valve (2), expansion refrigeration equipment (3), (7), heat exchangers (4), (8), high-pressure gas storage tank (5), centrifugal pumps (6), (10), (13), low-temperature refrigerant storage tanks (9), air-conditioning units (11), normal temperature refrigerant storage tanks (12); natural gas enters conventional natural gas from high-pressure natural gas pipelines The gate station (1), with an initial pressure of 6-10MPa, passes through the three-way valve (2), and the high-pressure natural gas is divided into two streams a and b. The a-share natural gas that meets the instantaneous demand of the urban pipeline network is expanded and refrigerated by the expansion refrigeration equipment (3), the pressure drops to 0.5-1.6MPa, and the temperature drops to -110--49°C. This process produces a large amount of cold energy. The low-temperature natural gas and the refrigerant are exchanged in the heat exchanger (4), and the temperature is raised to 5°C before entering the urban pipe network; the temperature of the refrigerant is reduced to -30-0°C and stored in the low-temperature refrigerant in the tank (9). When the gas consumption is low, the b-share natural gas with excess instantaneous demand is stored in the high-pressure gas storage tank (5); Operate as above to solve the peak gas consumption problem. The low-temperature refrigerant exchanged by the heat exchanger (8) is stored in the low-temperature refrigerant storage tank (9), and the refrigerant is sent to the air-conditioning unit (11) by the centrifugal pump (10) along with the refrigerant to exchange heat with the environment and heat up The final refrigerant returns to the normal temperature refrigerant storage tank (12), and is circulated by the centrifugal pump (13).

平衡法为工具，从热力学第一、第二定律出发，即从能量的数量和质量相结合的角度出发，揭示系统热力过程中

的转换、传递、利用和损失情况。高压天然气在膨胀机中的膨胀做功过程可近似为比热容为定值的多变过程，从而用

损失来分析天然气压力能转换效率。During the gas compression process, the work consumed by the compressor is completely transformed into the enthalpy increase of the gas and the external heat loss of the compressor cylinder, which is the internal cause of the pressure energy of the long-distance natural gas pipeline. Therefore, the device shown in accompanying drawing 1 takes

The balance method is a tool, starting from the first and second laws of thermodynamics, that is, from the perspective of combining the quantity and quality of energy, to reveal

transformation, transmission, utilization and loss. The expansion work process of high-pressure natural gas in the expander can be approximated as a variable process with a fixed specific heat capacity, so that

The loss is used to analyze the conversion efficiency of natural gas pressure energy.

损失：

loss:

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; xl</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; ln</span>}\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Among them: E _xl is loss, kJ; m is mass flow rate, kg/s;

n is the variability index; R _g is the gas constant of natural gas, J/kg·K;

T ₂ is the temperature at the inlet of the expander, K; T ₀ is the ambient temperature, K;

膨胀机压降比；η为等熵效率；

Expander pressure drop ratio; η is isentropic efficiency;

p ₂ is the inlet pressure of the expander, MPa p ₃ is the outlet pressure of the expander, MPa.

损失的大小取决于进出口气体的温度和压力，压降比越大，则其

损失就越大。此外，膨胀机受等熵效率的影响较大。这一算式表征了高压天然气通过膨胀系统利用压力能的能力，在高压输送的情况下这一能力在工程上具有重要的价值。The expansion process is approximately an isentropic process, and it can be seen from the above formula that

The size of the loss depends on the temperature and pressure of the inlet and outlet gases. The larger the pressure drop ratio, the

The greater the loss. In addition, the expander is greatly affected by the isentropic efficiency. This formula characterizes the ability of high-pressure natural gas to utilize pressure energy through the expansion system, and this ability has important engineering value in the case of high-pressure transmission.

概念为基础，在对该装置进行了全面的热力学分析基础上，实现了高压天然气压力能的利用，大幅度节省电耗，降低生产运营成本，广泛地应用于城市调峰系统，提高了城市天然气管网运行可靠性，优化能源结构，改善大气环境，推动我国天然气产业快速协调发展。The invention has low manufacturing cost, stable operation, and

Based on the concept, based on a comprehensive thermodynamic analysis of the device, the utilization of pressure energy of high-pressure natural gas has been realized, power consumption has been greatly saved, production and operation costs have been reduced, and it has been widely used in urban peak-shaving systems, improving urban natural gas Reliability of pipeline network operation, optimization of energy structure, improvement of atmospheric environment, and promotion of rapid and coordinated development of my country's natural gas industry.

Claims (6)

1. A peak-shaving method based on the utilization of natural gas high-pressure pipeline network pressure energy. The devices used in the method include: natural gas gate station (1), three-way valve (2), expansion refrigeration equipment (3), (7), replacement Heater (4), (8), high pressure gas storage tank (5), centrifugal pump (6), (10), (13), low temperature refrigerant storage tank (9), air conditioning unit (11), normal temperature refrigerant storage tank (12); it is characterized in that: natural gas enters the conventional natural gas gate station (1) from the high-pressure natural gas pipeline, and the initial pressure is 6-10 MPa. After passing through the three-way valve (2), the high-pressure natural gas is divided into two streams a and b, which meet the needs of the city. The a-share natural gas in the instantaneous demand of the pipeline network is expanded and refrigerated by the expansion refrigeration equipment (3), the pressure drops to 0.5~1.6MPa, and the temperature drops to -110~-49℃. This process generates a large amount of cold energy. The heat exchanger (4) performs cooling exchange, the temperature increases to 5°C, and enters the urban pipe network; the temperature of the refrigerant drops to -30-0°C, and is stored in the low-temperature refrigerant storage tank (9). When the gas consumption is low, the instantaneous demand Excess b-share natural gas is stored in the high-pressure gas storage tank (5); during the peak gas consumption, the high-pressure natural gas stored in the high-pressure gas storage tank (5) is operated as above through the centrifugal pump (6) to solve the peak gas consumption The problem is that the low-temperature refrigerant exchanged by the heat exchanger (8) is stored in the low-temperature refrigerant storage tank (9). The heated refrigerant returns to the normal temperature refrigerant storage tank (12), and is circulated by the centrifugal pump (13). 2. A peak-shaving device and method based on the utilization of natural gas high-pressure pipeline network pressure energy as claimed in claim 1, characterized in that the expansion refrigeration equipment (3), (7) is used to fully recover the pipeline network pressure energy, which improves the Improve energy utilization and reduce cold damage to equipment caused by high-pressure natural gas depressurization. 3. A peak shaving device and method based on the utilization of natural gas high-pressure pipeline network pressure energy as claimed in claim 1, characterized in that, when the gas consumption is low, the high-pressure natural gas is stored in the high-pressure gas storage tank (5); When the gas peaks, the stored natural gas will be expanded and exported to achieve the effect of peak shaving and valley filling, and the cooling capacity will be used for the air conditioning unit (11), which reduces the power consumption of the urban power grid and solves the problem of utilizing the pressure energy of the high-pressure natural gas pipeline network. Realized the peak regulation function of urban pipe network and power grid. 4. A kind of peak-shaving device and method based on natural gas high-pressure pipeline network pressure energy utilization as claimed in claim 1, is characterized in that, utilizes

Analytical method, combining the first law and the second law of thermodynamics, that is, from the perspective of combining the quantity and quality of energy, reveals the energy of the device

The conversion, transmission, utilization and loss of the equipment ensure the feasibility of the operation of the device. 5. A peak shaving device and method based on utilization of natural gas high-pressure pipeline network pressure energy as claimed in claim 1, wherein the refrigerant used in the refrigerant cycle power generation system is propane. 6. A peak shaving device and method based on utilization of natural gas high-pressure pipeline network pressure energy according to claim 1, characterized in that the air pressure in the high-pressure gas storage tank (5) is 6-10 MPa.

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