RU2790510C1 - Integrated method for production and transportation of liquefied natural gas - Google Patents

Abstract

FIELD: fuel and energy complex.

SUBSTANCE: invention relates to the fuel and energy complex and can be used in energy and gas supply systems in the absence of main gas transport. The integrated method for the production and transportation of liquefied natural gas (LNG) is that LNG is drained from the transport tank through the receiving device into the storage tank, fed to the evaporator, where it is converted into a vapor phase, then heated, odorized and fed to consumers through the reduction point. LNG is transported in a cryogenic tank, inside which a vessel for transporting gas is placed. Between the main shell and the vessel for transporting gas, an additional shell is installed and fixed, and the space between the main and additional shells is used to transport a refrigerant that maintains a negative temperature in the tank. The space between the additional shell and the vessel is filled with a low density insulating material. LNG regasification takes place in a heat exchanger, the heating medium of which is the refrigerant transported in a cryogenic tank. Pre-cooling of natural gas is carried out in a heat exchanger with a refrigerant in the cooling circuit.

EFFECT: increase in thermodynamic efficiency and simplification of technology and equipment.

1 cl, 2 dwg

Description

The invention relates to the fuel and energy complex, in particular, to methods for supplying consumers with liquefied natural gas (LNG) and can be used in energy and gas supply systems for various consumers of fuel and energy resources in the absence of main gas transport: for gas supply to cities and rural settlements, industrial , municipal and agricultural consumers, farms.

LNG, which is one of the promising cryogenic products, is used for the same purposes as network natural gas: generation of electricity, thermal energy, gas supply to consumers, creation of a fuel reserve to compensate for peak loads, use as motor fuel and raw materials for chemical industries.

Among the advantages of LNG technology over pipeline deliveries is the ability to deliver LNG from any LNG plant, regardless of the pipeline route.

The technology of gas supply to objects using LNG, depending on the source of its production, consists of the following stages:

- selection of natural gas from the main gas pipeline (marginal gas wells, oil fields, with the release of associated gas with a low content of heavy fractions);

- gas supply to the liquefaction plant;

- storage of liquefied gas until shipment to LNG storage systems;

- transfusion of liquefied gas into a cryogenic tank truck (or railway tank car) and transportation to the place of consumption;

- draining and storage in a storage tank at the consumer;

- regasification in evaporator-heaters;

- preparation and supply of gas to the consumer.

The following methods of natural gas transportation are known: pipeline transport; transportation of liquefied gas by ships, motor transport, railway transport.

Each method has its own advantages and disadvantages.

Known pipeline transport of natural gas [Ionin A.A. Gas supply. - M.: Stroyizdat, 1989. - 438 p.]. Gas under pressure of 7.5 MPa moves through pipelines up to 1.4 meters in diameter. As the gas moves through the main pipeline, it loses some of its energy to overcome friction forces, therefore, after about 150 km, compressor stations are built, where the gas is boosted to its initial pressure.

The disadvantages of pipeline transportation of natural gas to consumers remote from main gas pipelines are:

- Significant capital costs for the creation of a network of gas pipelines-branches from the main pipelines of natural gas;

- the connection between the laying of gas pipelines and branches with a number of factors that complicate and increase the cost of work (terrain relief, soil composition, availability of roads, water barriers, climatic conditions of the area);

- a limited area of operation, which ensures the possibility of supplying gas to consumers located in the directions along which the routes of the main gas pipelines pass;

- the inability to choose an alternative source of energy supply for consumers.

In relation to the conditions of the Russian Federation, the remoteness of a large number of settlements from main and inter-settlement gas pipelines, small volumes of gas consumption and a large dispersal of consumers sharply limit the prospects for their gasification with network gas. At the same time, a high degree of diversification and autonomy of energy supply systems based on liquefied gas, combined with a high consumer and environmental effect, make LNG the most preferred energy carrier for settlements and related agro-industrial facilities remote from power supply strongpoints.

A known method of marine delivery of natural gas to the consumer [Patent RU No. 2375246, priority date: 12.05.2008, IPC: B63B 25/12]. Natural gas in a liquefied or gaseous state is supplied from onshore facilities to a transport vessel. The liquefaction of gas is carried out at a plant located on the ship. At the destination, liquefied natural gas is transformed and supplied to the consumer.

The disadvantage of this method is that it can be used by regions that have large-capacity LNG plants, large LNG storage facilities, tankers and berths, which narrows the geography of LNG supplies.

Another disadvantage of the known method is the fact that the regasification of large volumes of LNG on a transport vessel and subsequent unloading take considerable time and are not always economically justified.

The noted shortcomings reduce the efficiency of the known method, reducing its scope to local supplies, in this regard, this method is not a sufficiently reliable and effective means of sustainable gas supply to settlements.

A pipeless method of gas supply to settlements is known [Rachevsky B.S. Compressed gas for rural facilities // Gas industry. - No. 11, 1993. - S. 34-35], according to which natural gas in a form compressed to 250 atmospheres is delivered by mobile gas tankers.

The disadvantage of the known method is the fact that it is advisable to use it only in the presence of automobile gas-filling compressor stations (CNG) located within a radius of up to 100 km from the gasified object.

There is also known a method of transporting natural gas [Patent RU No. 2391600, priority date: 06/19/2008, IPC: F17D 1/02, F17D 1/07, F17C 1/00], according to which natural gas is liquefied and loaded into a container, which move under the action of the pressure drop existing in the pipeline in which the gas flows, and the liquefied gas is at a pressure equal to the pressure in the pipeline.

The disadvantage of this method is the fact that it involves the transportation of liquefied natural gas in containers that move on ball bearings, while it is proposed to make a frame for the container and cover it with a heat-insulating material. Since the container contains cryogenic liquid, such containers are subject to increased requirements for their design, and one of the reasons for decommissioning cryogenic containers is the lack of vacuum in the heat-insulating cavity.

Another disadvantage of the known method is the need to create security measures due to the mandatory expansion of the gas, since the latter heats up during transportation.

Also, a disadvantage of the known method is its use only in the construction of new and modernization of existing high-pressure gas pipelines, which limits its scope.

The closest in technical essence to the claimed technical solution is a plant for liquefying natural gas and its regasification [Patent RU 2212600 C1, 20.09.2003, F25J 1/02], consisting of a regasification system, a vehicle for moving cold and warm coolants, a vehicle to move LNG from the tank to the gasifier tank. The gas liquefaction system is equipped with a heat exchanger-heater and an additional compressor, the suction line of which is connected through the heat exchanger-heater to the vapor space of the liquefied gas tank, and the discharge line is connected to a gas pipeline or to the suction line of a high-pressure compressor. As a coolant in the known invention, a mixture of hydrocarbons is used, the boiling and crystallization temperatures of which are controlled by changing its composition and pressure.

One of the disadvantages of the known invention is the fact that it is proposed to use a mixture of propane and butane of a certain percentage - 50% propane and 50% butane at a pressure of 0.4 MPa as the so-called mixed refrigerant (SHA) used as a coolant. Currently, LNG production uses mixtures of light hydrocarbons and nitrogen as refrigerants. For example, Shell DMR technology uses a refrigerant mixture of methane, ethane and propane in the pre-cooling circuit, while the refrigerant in the liquefaction circuit is a mixture of nitrogen, methane, ethane and propane. Thus, the limitation on the percentage of components in the SCA reduces the efficiency of the LNG production process.

Another disadvantage of the known solution is that the cooling and partial liquefaction of the gas taken from the gas source is carried out by heating the intermediate coolant, which must be periodically delivered by a separate tank truck and drained into a special container, which leads to a significant increase in the cost of the LNG production process.

Also, the disadvantages of the known installation include an undeveloped solution for saving the generated refrigeration potential during the production, transportation and storage of LNG, since natural gas will partially condense in the pre-cooling circuit, which will cause an uneven distribution of the gas flow. In small-scale LNG production, the process of gas condensation by heating the coolant is inefficient, requires an increase in the amount of circulating coolant and additional equipment, which ultimately leads to an increase in the pressure drop in the system, a decrease in the efficiency of the liquefaction process, and an increase in the cost of the system as a whole.

Liquefaction of natural gas is carried out by cooling it to saturation temperature, which corresponds to the pressure of the resulting LNG. To obtain low-temperature and cryogenic liquids, as a rule, a large amount of electricity is spent, that is, the liquefaction process is quite energy-intensive. For example, the well-known nitrogen cycle of natural gas liquefaction [Kuzmenko I.F., Peredelsky V.A. Natural gas liquefaction plants based on expander nitrogen cycles // Technical gases. - 2010. - No. 2. - With. 39-43], which is based on the circulation of nitrogen in a closed circuit containing compressors and turbines. The disadvantage of this method of liquefying natural gas is the high level of electricity consumption. Given the fact that prices for liquefied gas are constantly growing, the problem of saving electricity during its production and transportation is relevant.

The objective of the present invention is to increase the efficiency of the combined process of production and transportation of liquefied natural gas to ensure a reliable gas supply to consumers.

The technical problem to be solved by the present invention is to increase the efficiency, technical and economic indicators and the level of safety of production and transportation of liquefied natural gas by expanding the geography of supplies of natural gas in liquid and gaseous state to specific facilities, taking into account the specifics of their location and additional use of the refrigeration potential obtained during the regasification of liquefied natural gas in the process of its production and transportation.

The technical result provided by the invention is to minimize the amount of wasted refrigeration potential obtained during LNG regasification by returning the refrigerant back to the LNG plant and using it to pre-cool natural gas in the liquefaction cycle. Combining the benefits of liquefaction and transportation using the same refrigerant is beneficial in terms of thermodynamic efficiency, process and equipment simplicity, reducing LNG transportation and storage costs, minimizing technical risks, and optimizing system continuity.

This technical result is achieved by the fact that the known method of transporting liquefied natural gas contains: a liquefaction plant, an LNG base storage at a low- and medium-scale LNG production plant (LNG storage cryogenic tanks), a storage at the consumer (LNG storage cryogenic tanks), delivery vehicles gas to consumers (automobile or railway cryogenic tanks), means of gasification at consumers of gas fuel.

When implementing the combined method for the production and transportation of liquefied natural gas, LNG regasification occurs in a heat exchanger, the heating coolant of which is the refrigerant transported in a cryogenic tank, and natural gas reduction is carried out at a gas reduction point (GRP).

Pre-cooling of natural gas is carried out in a heat exchanger with a refrigerant in the cooling loop and the refrigeration potential obtained from LNG regasification is returned back to the small and medium-sized LNG plant and used to pre-cool the natural gas in the liquefaction cycle. The liquefaction efficiency improves with increasing pressure and, accordingly, the natural gas liquefaction pressure must be higher than the critical pressure of methane (as the main component of natural gas) in order to minimize the energy consumption for the LNG production process.

LNG transportation is carried out in a cryogenic tank containing a main shell, inside which a gas transportation vessel is located, an additional shell is installed and fixed between the main shell and the gas transportation vessel, and the space between the main and additional shells is used to transport a refrigerant that maintains a negative temperature in the tank in during gas transportation, and the space between the additional shell and the vessel is filled with a low-density insulating material that minimally increases the weight of the tank and prevents thermal interaction between the inner vessel and the outer cavity. As an insulating material, for example, screen-vacuum thermal insulation (super-insulation) is used, which is a system of parallel or concentric (coaxial) gas-permeable metal films deposited on a substrate, separated from each other by a porous gasket made of a material with a high coefficient of thermal resistance, providing a low degree of absorption thermal radiation and a low degree of accommodation of the energy of the inter-screen gas molecules with a high and stable adsorption capacity of metal films and allows you to protect the tank, operating at cryogenic temperatures, from heat inflows. The thermal conductivity of the insulation is (2-3)×10 ^-5 W/(m×K). Or screen-vacuum-powder insulation, the space in which between adjacent “screen-gasket” pairs is filled with fine powder, which reduces the heat transfer by the residual gas already at a relatively low vacuum. At the same time, the screens make it possible to reduce heat gain by radiation compared to powder-vacuum insulation.

At the same time, in order to ensure safety, the diameters of the discharge holes and safety valves correspond to the volume of LNG in the storage tank and the cryogenic tank.

The essence of the invention is illustrated by drawings, where in Fig. 1 is a diagram of an integrated process for the production and transport of liquefied natural gas from the liquefaction plant to the end user, FIG. 2 shows an integrated process for the production and transport of liquefied natural gas from a consumer to a liquefaction plant. Positions in the drawings indicate the following: 1 - cryogenic tank; 2 - submersible centrifugal cryogenic pump; 3 - pump for refrigerant pumping; 4 - LNG storage cryogenic tank; 5 - storage tank for refrigerant; 6 - heat exchanger; 7 - evaporator-heater; 8 - section for loading LNG and heated refrigerant (shown by a dotted line); 9 - section for the issuance of a cooled refrigerant (shown by a dotted line); 10 - reduction block; 11 - gas distribution network; 12 - plant for small- and medium-tonnage production of liquefied natural gas (shown by a dotted line); 13 - main gas pipeline; 14 - section for loading the cooled refrigerant (shown by a dotted line); 15 - area for the issuance of LNG and heated refrigerant (shown by a dotted line); 16 - compressor station; 17 - liquefaction unit.

The integrated method for the production and transportation of liquefied natural gas is carried out as follows.

At the plant for small- and medium-scale production of liquefied natural gas 12, liquefied natural gas is pumped from the LNG storage cryogenic tank 4 using a submersible centrifugal cryogenic pump 2 into the cryogenic tank 1 at the LNG and heated refrigerant loading area 8. Into the space between the outer shell and the additional shell of the cryogenic tank 1 from the storage tank for the refrigerant 5 with the help of a pump for pumping the refrigerant 3, the refrigerant heated in the heat exchanger 6 is supplied and the refrigerant and LNG are delivered to consumers at the site for the issuance of LNG and heated refrigerant 15, where the LNG is supplied using a submersible centrifugal cryogenic pump 2, and the refrigerant using a pump for pumping refrigerant 3, it is fed into the evaporator-heater 7, from where regasified natural gas that meets the requirements of GOST R 57431-2017 is fed into the reduction unit 10, after reducing the pressure in which, it enters the existing gas distribution network 11. The refrigerant is submersible centrifugal cryogenic pump 2 enters the cryogenic tank 1 at the chilled refrigerant loading section 14, after which the tank is transported to the small- and medium-scale LNG production plant 12, where the cooled refrigerant is fed into the heat exchanger at the chilled refrigerant dispensing section 9 using a submersible centrifugal cryogenic pump 2 6, representing, among other things, several stages of cooling, after which the heated refrigerant is fed into the storage tank for the coolant 5. Liquefied natural gas after the liquefaction unit 17 at the plant of small and medium-scale production of LNG 12 using a submersible centrifugal cryogenic pump 2 is fed into the storage tank. cryogenic capacity of LNG 4.

An example of a specific implementation of the method.

The pre-treatment steps that can be used in the present invention usually begin with the known LNG production steps - purification, dehydration. After separating heavy fractions using low-temperature separation (this technological stage is not shown in the diagram), the gas prepared for liquefaction under pressure (for example, 0.3-0.5 MPa for small-scale production of liquefied natural gas) is successively cooled in a low-temperature heat exchanger (heat exchanger- condenser) 6 to approximately minus 160°C (depending on the LNG composition, the boiling point ranges from minus 166°C to minus 157°C at atmospheric pressure). The heat exchanger 6 has several cooling stages to enable the refrigerant to evaporate at different pressures. After that, the gas flow is compressed at the compressor station 16 and sent to the liquefaction unit 17 at the plant for small- and medium-scale production of LNG 12, liquefied and fed under its own pressure for storage in storage cryogenic tanks LNG 4, designed for storing media with ultra-low temperatures (for example, LNG storage systems based on block systems (BSHP) using cryogenic tanks with screen-vacuum superinsulation), from where liquefied natural gas is pumped into the vessel space of a cryogenic tank using a submersible centrifugal cryogenic pump 2 (for example, brand NTs-TS or TsPG-P) 1 at the site for loading LNG and heated refrigerant 8. Cryogenic tank 1 contains the main shell, inside which a gas transportation vessel is located, an additional shell is installed and fixed between the main shell and the gas transportation vessel, and the space between the main and additional shells is used for the transportation of refrigerants, and the space between the additional shell and vessel is filled with a low-density insulating material that minimally increases the weight of the tank, for example, screen-vacuum-powder insulation. Cryogenic tank 1 is equipped with fittings, devices for measuring level, pressure and temperature, safety devices from exceeding the working pressure in the inner vessel, heat-insulating cavity and pipelines (not shown in the diagram). The LNG temperature is assumed to be minus 161.5°С, which ensures non-boiling during transportation. In the space between the outer shell and the additional shell of the cryogenic tank 1, the refrigerant is supplied from the storage tank for the refrigerant 5 using a refrigerant transfer pump 3 (for example, an electric pump of the BEN brand). The temperature of the refrigerant is equal to the ambient temperature and is approximately minus 27°C for the cold period. After filling the cryogenic tank 1 with liquefied natural gas and refrigerant, it delivers them by road or rail transport to consumers at the LNG and heated refrigerant 15 dispensing site. At consumers, by means of a submersible centrifugal cryogenic pump 2 (for example, brand NTs-TS or TsPG-P) LNG is pumped into storage cryogenic tanks LNG 4 (for example, BSHP brand) or membrane-type tanks, from where it is sent to the evaporator-heater 7 (for example, atmospheric evaporator) using a submersible centrifugal cryogenic pump 2 (for example, NTs-TS or TsPG-P brand). IKZh-A and explosion-proof electric gas heater). The refrigerant with the help of an electric pump 3 (for example, an electric pump of the BEN brand) is also pumped into the evaporator-heater 7, in which the refrigerant exchanges thermal energy with LNG through a separating wall. As a result of heat exchange, the refrigerant lowers its temperature to approximately minus 130°C, and the LNG is heated to approximately minus 25°C and evaporates, turning into natural gas. After the evaporator-heater 7, natural gas under its own pressure, equal to, for example, 1.2 MPa, is fed into the reduction unit 10, where the gas pressure is reduced to the required consumer, for example, to 3-5 kPa to be fed into the gas distribution network 11 low pressure. The pressure is maintained automatically by means of a pressure regulator and does not require electrical power or the presence of an operator. For consumers, the system for receiving, storing and regasifying LNG is designed to provide natural gas gasified from liquefied gas and maintain the parameters of the gas supplied to the consumer within the specified pressure, temperature and flow rates. The system includes (not shown in the diagram): a filling station, cryogenic pipelines and fittings, gas reduction points, commercial gas flow units and a parameter control system. The gas temperature after the evaporator is 3÷5°С (approximately minus 29°С) lower than the ambient temperature. In the cold season, natural gas can be additionally heated in electric heaters (not shown in the diagram). The gas temperature at the outlet of the heaters is automatically maintained in the range from minus 10 to 0°C. At the reduction point, the gas is automatically reduced to the operating pressure of gas-using consumer devices, which does not exceed 5 kPa for low pressure. The refrigerant after the evaporator-heater 7 with the help of a submersible centrifugal cryogenic pump 2 (for example, brand NTs-TS or TsPG-P) enters the space of the vessel of the cryogenic tank 1, previously cleared of LNG, at the section for loading the cooled coolant 14. After filling the vessel of the cryogenic tank 1 refrigerant, the tank is transported by road or rail to the plant for small- and medium-scale production of LNG 12. The energy spent on obtaining cold is saved due to the fact that the refrigerant supplied to the plant for small- and medium-scale production of LNG 12 from the consumer refrigerant at the area for issuing cooled refrigerant 9 using a submersible centrifugal cryogenic pump 2 (for example, brand NTs-TS or TsPG-P) is fed into the heat exchanger 6 (for example, a spiral-wound heat exchanger (SVTO)), where the refrigerant exchanges heat with natural gas coming, for example, from the main gas pipeline 13 .Pre-cooling allows cost-effective use less energy for subsequent cooling, compression in the compressor unit 16 and liquefaction of natural gas in the liquefaction unit 17. The refrigerant, heated from natural gas in the heat exchanger 6, is fed into the storage tank for refrigerant 5 by means of a refrigerant transfer pump 3. Liquefied natural gas after the liquefaction unit 17, with the help of a submersible centrifugal cryogenic pump 2 (for example, the brand NTs-TS or TsPG-P), it is fed into the storage cryogenic tanks of LNG 4.

One of the tasks for the implementation of the proposed method is the selection of the refrigerant. The main requirements for the refrigerant are a low melting point, close to the temperature of liquefied natural gas under normal conditions, and a relatively high boiling point, which would allow the refrigerant to be transported in a liquid state without additional external thermal insulation. Also, the refrigerant must not be aggressive to the material of the tank, and remain stable for the entire period of operation.

According to the results of the analysis, it is proposed to use pure components as refrigerants, the so-called natural refrigerants, for example, dimethyl ether (DME), which is a colorless, chemically inert, highly purified gas, odorless, non-toxic to the consumer, does not affect the environment with low emissions volatile organic compounds or isopentane.

To assess the economic efficiency of the proposed integrated method for the production and transportation of liquefied natural gas to various categories of consumers, it was compared with the basic (existing) method. As a basic option, a gas supply scheme for consumers based on liquefied natural gas using an automobile cryogenic tank-semi-trailer was adopted. The proposed option is implemented using the cryogenic tank design developed by the authors [Useful model RU No. 115309 Tank for transporting liquefied natural gas, V60R 3/22 (2006.01)]. Technical characteristics of the basic and proposed tank are presented in table 1.

To determine the heat capacity of the refrigerant in the liquid state, we use the Rawlinson-Bondi equation:

- приведенная температура.Where

- reduced temperature.

. Количество тепла, необходимое для испарения 16 м³ СПГ, составляет 3486 МДж. Следовательно, для испарения 16 м³ СПГ потребуется хладагент в количестве:

.The approximate average heat capacity is

. The amount of heat required to vaporize 16 ^m3 of LNG is 3486 MJ. Therefore, for the evaporation of 16 m ³ LNG, a refrigerant is required in the amount of:

.

.We accept the expected results as the same, that is, R _1t =R _2t . The calculation horizon is considered equal to the service life of the system:

.

Economic effect:

where K _1p , K _2p - capital investments in the p-th element of the system according to the basic and proposed options, respectively, rub; m - number of the next capital investments; n is the number of regular capital investments (the number of replacements of the p-th element over the life of the system); t=mt ₀ - year of next capital investments; t ₀ - service life of the p-th element of the system, years; α - coefficient of efficiency of capital investments, 1/year; And ₁ , And ₂ - operating costs for maintenance, energy resources for the basic and proposed options, respectively, rub./year; t is the number of the year of operation; T is the service life of the system, years; E - discount rate, 1/year, is taken equal to the average bank lending rate in a market economy, 1/year.

The number of replacements of the p-th element during the service life of the system:

Since the production of tanks is carried out within one year, the capital investments for both options are not discounted over time. When calculating on a net basis, the components of capital and operating costs, which are the same for both options, are not taken into account.

Capital investments under the base case are defined as:

where K ₁ - capital costs in the transport tank, are taken according to the price lists of manufacturers, rub.

Reduced correction factor ψ _pr :

ψ _pr \u003d ψ _nr ⋅ψ _mon ⋅ψ _vat ,

where ψ _nr ^_ coefficient taking into account the increase in the cost of work due to overhead costs;

ψ _mon - coefficient taking into account the rise in the cost of work due to planned savings;

ψ _vat - coefficient taking into account value added tax.

Capital investments under the base case will be:

The operating costs for the base case are determined by the formula:

where c _e is the cost of 1 MWh of electricity consumed by the compressor, rub/(MWh); g _e - the amount of electricity consumed by the compressor according to the base case, kWh / (kg LNG); m _LNG is the mass of LNG transported by one tank, kg; τ _g - duration of operation of the compressor during the year, days / year; ϕ ₁ - the share of annual deductions for the operation of a cryogenic tank.

Operating costs will be:

Integral costs for the base case for the entire life of the tank will be: Z ₁ =34.721 million rubles.

Capital investments under the proposed option will be:

where K ₂ - capital costs in the transport tank, taken according to the price list, taking into account changes to the design, rub.

The operating costs for the proposed option are determined by the formula:

where c _t is the cost of 1 liter of diesel fuel, additionally spent on the transportation of refrigerant, rub; ℓ - the distance traveled by the tanker to the settlement and back, is taken according to the results of optimization calculations, km. In this case, the length of the path corresponds to one shift per day; g _t is the amount of additionally consumed fuel for the transportation of refrigerant per 1 kg of LNG, l/km⋅(kg of LNG); τ _g - duration of operation of the tank during the year, days / year; ϕ ₂ - the share of annual deductions for the operation of a cryogenic tank.

Approximation expression for determining the energy costs of the compressor at various ratios of the masses of the refrigerant and LNG:

The operating costs of the proposed option will be:

Integral costs for the entire life of the proposed option: Z ₂ =30.13 million rubles.

Net present value of the compared options:

- экономия затрат на электроэнергию при производстве СПГ, руб.;

- стоимостная оценка эффекта при сравнении затрат на топливо при транспортировке СПГ, руб.;

- разность затрат на эксплуатацию цистерны по базовому и предлагаемому варианту, руб.where τ is the number of the year of operation; T is the service life of the system, years;

- savings in electricity costs in the production of LNG, rub.;

- valuation of the effect when comparing fuel costs for LNG transportation, rub.;

- the difference in the cost of operating the tank according to the basic and proposed options, rub.

As a result, we get: ΔZ _Σ =6.419 million rubles.

The economic effect of the proposed combined method:

E _g \u003d W ₁ - W ₂ \u003d 4.471 million rubles,

or in relative terms: Δ=12.9%.

The analysis of the prior art made it possible to establish that there are no analogues characterized by sets of features identical to all the features of the claimed combined method of production and transportation of liquefied natural gas. Therefore, the claimed variants of technical solutions meet the condition of patentability "novelty".

The results of the search for known solutions in this field of technology in order to identify features that match the distinguishing features of the prototype of the proposed options for technical solutions have shown that they do not follow explicitly from the prior art. From the level of technology determined by the applicant, the popularity of the influence of the transformations provided for by the essential features of the claimed technical solutions on the achievement of the specified technical result has not been revealed. Therefore, the claimed technical solutions meet the condition of patentability "inventive step".

The proposed technical solution can be used in the cycle of preliminary liquefaction of natural gas and the delivery of liquefied natural gas to consumers remote from the main gas pipelines of network natural gas. Therefore, the claimed version of the technical solution meets the condition of patentability "industrial applicability".

The use of the proposed combined method of production and transportation of liquefied natural gas for gas supply to buildings, industrial, municipal and agricultural consumers will significantly increase the level of engineering service, expand the functionality of liquefied natural gas installations without additional energy costs.

The technical result of this invention is to increase the efficiency and economy of the combined production method and liquefied natural gas, to ensure the simplicity of the design scheme, operational reliability, durability, safety precautions for vehicle maintenance personnel, improve the environmental situation due to the absence of methane emissions into the atmosphere, since during operation the proposed method does not occur any chemical reactions and neither harmful substances nor heat are released. Therefore, such an integrated method of production and transportation of liquefied natural gas is absolutely environmentally friendly and does not contribute to global warming.

A feature of the proposed combined method for the production and transportation of liquefied natural gas is that this technology can be used as a supplement to traditional gas supply through the construction of a gas distribution system and allows providing potential consumers with gas fuel. Implementation of the proposed method does not require significant reconstruction of the gas transmission system. Using the method will improve the efficiency of gas supply by reducing energy consumption for the transportation of liquefied natural gas by using the generated refrigeration potential for production purposes.

Claims (1)

The combined method of production and transportation of liquefied natural gas, which consists in the fact that liquefied natural gas from the transport tank is drained into the storage tank through the receiving device, then it is fed through the shut-off valves to the evaporator, where it is converted into a vapor phase, then it is heated, odorized and through the point reduction is supplied to consumers, characterized in that the transportation of liquefied natural gas is carried out in a cryogenic tank, inside which a vessel for transporting gas is located, an additional shell is installed and fixed between the main shell and the vessel for transporting gas, and the space between the main and additional shells is used for transporting the refrigerant which maintains a negative temperature in the tank during gas transportation, and the space between the additional shell and the vessel is filled with a low-density insulating material that minimally increases the weight of the tank, and LNG regasification occurs in a heat exchanger, the heating medium of which is the refrigerant transported in a cryogenic tank, and the preliminary cooling of natural gas is carried out in a heat exchanger with a refrigerant in the cooling circuit, and the refrigeration potential obtained during LNG regasification is returned back to the small- and medium-tonnage LNG production plant, where for pre-cooling natural gas in the liquefaction cycle.

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