Optimized operation method for reducing ORV and IFV seawater flow

Abstract

The invention discloses an optimized operation method for reducing the seawater flow of ORV and IFV, which comprises the following steps: obtaining the seawater flow required by the operation of each gasifier including an open rack gasifier and an intermediate medium gasifier; the vaporizers are combined, and the total seawater flow corresponding to different combinations of the vaporizers is calculated according to the seawater flow required by operation; and comparing the total seawater flows corresponding to different combinations of the vaporizers to obtain the lowest total seawater flow, the optimal running number of the vaporizers and the optimal liquefied natural gas flow corresponding to each vaporizer so as to realize optimal running for reducing the ORV and IFV seawater flows in the liquefied natural gas station.

Description

Technical Field

[0001] The invention belongs to the technical field of operation optimization of liquefied natural gas stations, and in particular relates to an optimized operation method for reducing seawater flow of ORVs and IFVs. Background Art

[0002] In liquefied natural gas (LNG) stations, the three commonly used vaporizers are open rack vaporizer (ORV), intermediate medium vaporizer (IFV) and submerged combustion vaporizer (SCV). LNG stations use ORV, IFV and SCV vaporizers to vaporize LNG and convert it into natural gas (NG) for external transmission. SCV uses natural gas combustion as heat input to vaporize LNG, which is very expensive. ORV and IFV vaporizers use seawater and warm seawater discharged from other companies as heat input to vaporize LNG, because seawater heat and warm seawater discharged from other companies are free energy and free waste. It is only necessary to keep the ORV vaporizer and IFV vaporizer to discharge seawater to meet environmental protection requirements. Many large LNG stations are built on the coast. Using free heat energy such as seawater, warm seawater discharged from factories, and geothermal heat to provide heat to ORV and IFV vaporizers can greatly reduce the operating costs of LNG stations.

[0003] The gasification process of LNG is a comprehensive utilization system of heat, cold and electric energy. LNG gasification requires heat, and the transportation of heat and cold media requires electric energy. LNG itself contains a large amount of cold energy. How to optimize and balance the relationship between the three, and rationally utilize seawater, warm seawater from power plants, geothermal energy or other resources, so as to achieve efficient use of heat energy and full use of cold energy, while ensuring efficient transportation of heat and cold media, so as to minimize the total energy consumption of the system, minimize CO2 emissions, and minimize pollutants. Under the background of "dual carbon", research on these issues is becoming more and more extensive.

[0004] Using seawater pumping stations to supply water to multiple ORV vaporizers and IFV vaporizers is currently the most commonly used method for LNG gasification. Since seawater heat is free, research work mainly focuses on how to match pump groups to reduce the power consumption of pump stations. These studies mixed the optimization of multiple vaporizers with the optimization of seawater pumping stations composed of multiple pump groups, and tentatively summarized the optimization combination methods of various water pumps, so the conclusions of each company are different. In fact, these are three problems. The first is to determine the minimum seawater heat input required for LNG gasification by optimizing the number of operating vaporizers and load distribution; the second is to determine the final minimum seawater flow rate for this minimum heat input and environmental protection and equipment constraints; the third is to optimize the number of operating pump groups and distribute the load of each pump group for this minimum seawater flow rate, so that the power consumption of the entire seawater pumping station is minimized. For the third question, there are definitive conclusions in theoretical research and technological inventions for optimizing the energy efficiency of pump station operation, for example, the book “Efficient Energy-Saving Control and Optimization for Multi-unit Systems-A Guide for Electrical Engineers” published by Springer and the U.S. patent “POWER-SAVING OPTIMIZATION OPERATION METHOD AND SWITCHING POINT DETERMINING METHOD FOR WATER PUMP UNIT, 17 / 339,381”.

[0005] There is currently no clear path for optimizing the energy efficiency of multiple ORV vaporizers and multiple IFV vaporizers, determining the number of ORVs and IFVs in operation and the load distribution method, and ultimately determining the minimum seawater flow required for LNG gasification that meets environmental protection and equipment constraints.

[0006] Therefore, it is urgent to propose an optimized operation method to reduce the seawater flow of ORVs and IFVs. Summary of the invention

[0007] In order to solve the above technical problems, the present invention proposes an optimized operation method for reducing the seawater flow of ORV and IFV to solve the problems existing in the above prior art.

[0008] To achieve the above object, the present invention provides an optimized operation method for reducing the seawater flow of ORV and IFV, comprising:

[0009] Obtaining the seawater flow rate required for the operation of each vaporizer, wherein the vaporizer includes an open-frame vaporizer and an intermediate medium vaporizer;

[0010] The vaporizers are combined, and the total seawater flow corresponding to different combinations of vaporizers is calculated according to the seawater flow required for operation;

[0011] The total seawater flow rates corresponding to different combinations of vaporizers were compared to obtain the lowest total seawater flow rate, the optimal number of operating units, and the optimal liquefied natural gas flow rate corresponding to each vaporizer.

[0012] Optionally, in a liquefied natural gas station, several of the gasifiers are connected in parallel, wherein the liquefied natural gas inlets of the several gasifiers are connected together, the natural gas outlets are connected together, and the seawater inlets are connected together.

[0013] Optionally, obtain the seawater flow rate Q required for the operation of the i-th open-frame gasifier SW-ORVi The process is:

[0014] Q SW-ORVi =Q LNG-ORVi ΔT LNG-ORVi / ΔT SW-ORVi / (a i0 +a i1 Q LNG-ORVi +…+a i9 Q 9 LNG-ORVi )

[0015] If Q SW-ORVi <Q SW-ORVi-min , then Q SW-ORVi =Q SW-ORVi-min ;

[0016] If Q SW-ORVi >Q SW-ORVi-max , then Q SW-ORVi =Q SW-ORVi-max ;

[0017] If Q LNG-ORVi >Q LNG-ORVi-max , then Q LNG-ORVi =Q LNG-ORVi-max ;

[0018] ΔT SW-ORVi ≤5

[0019] Among them, Q SW-ORVi is the seawater flow rate required for the operation of the i-th open-frame vaporizer, Q LNG-ORVi is the LNG flow rate of the i-th open-rack vaporizer, ΔT LNG-ORVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th open-rack vaporizer, ΔT SW-ORVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th open-frame vaporizer, a i0 、a i1 , …ai8 and a i9 Represent different coefficients respectively, are constants, Q SW-ORVi-min represents the minimum film-forming flow rate of seawater for the i-th open-frame vaporizer, Q SW-ORVi-max represents the maximum seawater flow rate of the i-th open-frame vaporizer, Q LNG-ORVi-max represents the maximum liquefied natural gas flow rate of the i-th open-rack vaporizer.

[0020] Optionally, the total seawater flow rate corresponding to different combinations of open-frame vaporizers is the sum of the seawater flow rates required for the operation of the open-frame vaporizers in different combinations of the open-frame vaporizers, where the total seawater flow rate Q SW-ORV-k The calculation formula is:

[0021] Q SW-ORV-k =Q SW-ORV1 +Q SW-ORV2 +…+Q SW-ORVk

[0022] If each open rack vaporizer is the same model, then

[0023] Q SW-ORV-k = k(Q LNG-ORV / k)ΔT LNG-ORVi / ΔT SW-ORVi / (a i0 +a i1 (Q LNG-ORV

[0024] / k)+…+a i9 (Q LNG-ORV / k) 9 )

[0025] Among them, Q SW-ORV-k represents the total seawater flow rate of k open-frame vaporizers, Q SW-ORVk represents the seawater flow rate required by the kth open-frame vaporizer, k = 1, 2, ..., m, m represents the total number of open-frame vaporizers, k represents the number of the open-frame vaporizer, ΔT LNG-ORVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th open-rack vaporizer, ΔT SW-ORVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th open-frame vaporizer, a i0 、a i1 , …a i8 and a i9 Represent different coefficients, Q LNG-ORV represents the total flow rate of liquefied natural gas flowing through k open-rack vaporizers.

[0026] Q LNG-ORV =Q LNG-ORV1 +Q LNG-ORV2 +…+QLNG-ORVk , k = 1, 2, ..., m

[0027] Optionally, the process of obtaining the seawater flow rate required for the operation of the intermediate medium gasifier includes:

[0028] Q SW-IFVi =Q LNG-IFVi ΔT LNG-IFVi / ΔT SW-IFVi / (b i0 +b i1 Q LNG-IFVi +…+b i9 Q 9 LNG-IFVi )

[0029] If Q SW-IFVi <Q SW-IFVi-min , then Q SW-IFVi =Q SW-IFVi-min ;

[0030] If Q SW-IFVi >Q SW-IFVi-max , then Q SW-IFVi =Q SW-IFVi-max ;

[0031] If Q LNG-IFVi >Q LNG-IFVi-max , then Q LNG-IFVi =Q LNG-IFVi-max ;

[0032] ΔT SW-IFVi ≤5

[0033] Among them, Q SW-IFVi is the seawater flow rate required by the i-th intermediate medium gasifier, Q LNG-IFVi is the liquefied natural gas flow rate of the i-th intermediate medium gasifier, ΔT LNG-IFVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th intermediate medium gasifier, ΔT SW-IFVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th intermediate medium vaporizer; b i0 、b i1 ,…b i8 and b i9 Represents the coefficient of different terms, which is a constant; Q SW-IFVi-min represents the minimum film-forming flow rate of seawater for the i-th intermediate medium vaporizer, Q SW-IFVi-max represents the maximum seawater flow rate and Q of the i-th intermediate medium vaporizer LNG-IFVi-max represents the maximum liquefied natural gas flow rate of the i-th intermediate medium vaporizer.

[0034] Optionally, the total seawater flow corresponding to different combinations of intermediate medium type vaporizers is the sum of the seawater flow required for the operation of the intermediate medium type vaporizers in different combinations of intermediate medium type vaporizers, wherein the total seawater flow calculation formula is:

[0035] Q SW-IFV-k1 =Q SW-IFV1 +Q SW-IFV2 +…+Q SW-IFVk1

[0036] If the intermediate medium gasifier is the same model, then

[0037] Q SW-IFV-k1 =(Q LNG-IFV / k 1 )ΔT LNG-IFVi / ΔT SW-IFVi / (b i0 +b i1 (Q LNG-IFV / k 1 )+…+b i9 (Q LNG-IFV / k 1 ) 9 )

[0038] Q SW-IFV-k1 Indicates k 1 Total seawater flow rate of each intermediate medium vaporizer, Q SW-IFV1 Indicates the kth 1 The seawater flow rate required for an open-frame vaporizer, k 1 =1, 2, ..., n, where n represents the total number of intermediate medium gasifiers; k 1 Indicates the number of the open-frame vaporizer, ΔT LNG-IFVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th intermediate medium gasifier, ΔT SW-IFVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th intermediate medium vaporizer, b i0 、b i1 ,…b i8 and b i9 Denotes the coefficients of different terms, Q LNG-IFV It represents the total flow rate of liquefied natural gas flowing through k1 intermediate medium vaporizers.

[0039] Q LNG-IFV =Q LNG-IFV1 +Q LNG-IFV2 +…+Q LNG-IFVk1 , k 1 =1,2,…,n

[0040] Optionally, the process of comparing the total seawater flow rates corresponding to different combinations of vaporizers includes:

[0041] The minimum value of the total amount of seawater in different combinations of vaporizers is selected to obtain the lowest total amount of seawater, and the vaporizer combination corresponding to the lowest total amount of seawater is determined to obtain the number of vaporizers as the optimal number of vaporizers in operation. If the models of the vaporizers are the same, the total flow of liquefied natural gas is evenly divided according to the optimal number of operating units, and the evenly divided result is used as the optimal liquefied natural gas flow corresponding to each vaporizer.

[0042] Optionally, the process of combining the gasifiers includes: obtaining different combinations of gasifiers by adjusting the number of open-frame gasifiers and intermediate-medium gasifiers in operation respectively.

[0043] Compared with the prior art, the present invention has the following advantages and technical effects:

[0044] The present invention provides an optimized operation method for reducing the seawater flow of ORV and IFV. The method can optimize the energy efficiency of multiple ORV and IFV gasifiers, and provide the number of operating units and load distribution method for energy efficiency optimization. The measures taken have a clear execution path and are feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0046] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0047] Figure 2 This is a schematic diagram of the structure of an LNG station according to an embodiment of the present invention;

[0048] Among them, 1. the first ORV vaporizer, 2. the second ORV vaporizer, 3. the third ORV vaporizer, 4. the fourth ORV vaporizer, 5. the seawater inlet pipe, 6. the seawater return channel, 7. the liquefied natural gas inlet pipe, and 8. the liquefied natural gas outlet pipe. DETAILED DESCRIPTION

[0049] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0050] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0051] The present invention discloses an optimized operation method for reducing the seawater flow rate of an open-frame vaporizer (ORV) and an intermediate medium vaporizer (IFV), the steps comprising: obtaining the seawater flow rate required for the operation of each open-frame vaporizer and the intermediate medium vaporizer; for each combination of the open-frame vaporizer and the intermediate medium vaporizer, adding the seawater flow rate required for the operation of each open-frame vaporizer and the intermediate medium vaporizer to obtain the total seawater flow rate required by the open-frame vaporizer and the intermediate medium vaporizer; comparing the total seawater flow rates of various combinations to obtain the lowest total seawater flow rate; and obtaining the corresponding optimal number of operating units; and providing the optimal liquefied natural gas flow rate of each open-frame vaporizer and the intermediate medium vaporizer. The measures taken by the present invention have a clear execution path and are achievable.

[0052] In order to solve the above technical problems, the present invention proposes an optimized operation method for reducing the seawater flow of ORV and IFV to solve the problems existing in the above prior art.

[0053] To achieve the above purpose, for a liquefied natural gas station, there are m open-frame vaporizers and n intermediate medium vaporizers. The open-frame vaporizers and intermediate medium vaporizers of the liquefied natural gas station are connected in parallel, the liquefied natural gas inlets flowing through all the open-frame vaporizers and intermediate medium vaporizers are connected together, the natural gas outlets flowing through all the open-frame vaporizers and intermediate medium vaporizers are connected together, and the seawater inlets flowing through all the open-frame vaporizers and intermediate medium vaporizers are connected together. Figure 1 As shown, the present invention provides an optimized operation method for reducing the seawater flow rate of an open rack vaporizer (ORV) and an intermediate medium vaporizer (IFV), comprising the following steps:

[0054] Obtain the seawater flow rate required for the operation of each open-frame vaporizer and intermediate medium vaporizer;

[0055] For each combination of open-frame gasifier and intermediate medium gasifier, the seawater flow rate required for the operation of each open-frame gasifier and intermediate medium gasifier is added to obtain the total seawater flow rate required by the open-frame gasifier and the intermediate medium gasifier;

[0056] By comparing the total seawater flow rates of various combinations, the lowest total seawater flow rate is obtained, and the corresponding optimal number of operating units is obtained, and the optimal liquefied natural gas flow rate of each open-frame vaporizer and intermediate medium vaporizer is given.

[0057] As some embodiments, the process of obtaining the seawater flow rate required for the operation of each open rack gasifier includes:

[0058] The seawater flow rate Q required for the operation of the i-th open-frame gasifier SW-ORVi The formula for obtaining is:

[0059] Q SW-ORVi =Q LNG-ORVi ΔT LNG-ORVi / ΔT SW-ORVi / (a i0 +a i1 Q LNG-ORVi +…+a i9 Q 9 LNG-ORVi )

[0060] If Q SW-ORVi <Q SW-ORVi-min , then Q SW-ORVi =Q SW-ORVi-min ;

[0061] If Q SW-ORVi >Q SW-ORVi-max , then Q SW-ORVi =Q SW-ORVi-max ;

[0062] If Q LNG-ORVi >Q LNG-ORVi-max , then Q LNG-ORVi =Q LNG-ORVi-max ;

[0063] ΔT SW-ORVi ≤5

[0064] Among them, Q SW-ORVi is the seawater flow rate required by the i-th open-frame vaporizer, Q LNG-ORVi is the LNG flow rate of the i-th open-rack vaporizer, ΔT LNG-ORVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th open-rack vaporizer, ΔT SW-ORVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th open-frame vaporizer. The environmental protection requirement ΔT SW-ORVi ≤5℃,a i0 、a i1 , …a i8 and a i9 Represent the coefficients of different terms and are constants.

[0065] In the above constraints, the minimum film-forming flow rate of seawater for the i-th open-frame vaporizer is expressed as Q SW-ORVi-min , the maximum seawater flow is expressed as Q SW-ORVi-max and the maximum LNG flow rate is denoted as Q LNG-ORVi-max .

[0066] The process of obtaining the required total seawater flow includes:

[0067] Assume that the total flow rate of liquefied natural gas passing through k open-rack vaporizers is Q LNG-ORV, k open-frame vaporizers are in operation, where k = 1, 2, ..., m, and the total seawater flow Q for k open-frame vaporizers SW-ORV-k The formula for obtaining is:

[0068] Q SW-ORV-k =Q SW-ORV1 +Q SW-ORV2 +…+Q SW-ORVk

[0069] Among them, Q SW-ORVk Represents the seawater flow rate required by the kth open-frame vaporizer, k = 1, 2, ..., m.

[0070] For k open-rack vaporizers with similar performance, the LNG flow rate Q of each open-rack vaporizer is LNG-ORVi Approximately the same, seawater flow Q SW-ORVi The total seawater flow rate Q of k open-frame vaporizers is approximately the same. SW-ORV-k The formula for obtaining is:

[0071] Q SW-ORV-k = k(Q LNG-ORV / k)ΔT LNG-ORVi / ΔT SW-ORVi / (a i0 +a i1 (Q LNG-ORV / k)+…+a i9 (Q LNG-ORV / k) 9 )

[0072] The total LNG flow through k open rack vaporizers is represented by Q LNG-ORV , Q LNG-ORV / k represents the total liquefied natural gas flow rate of each open-frame vaporizer. The performance of m open-frame vaporizers is approximately the same. The minimum total seawater flow rate Q SW The formula for obtaining is:

[0073] Q SW =min{Q SW-ORV-1 , Q SW -ORV-2, ..., Q SW-ORV-m}

[0074] Corresponding to the minimum Q SW The number of operating units is the optimal number of open-rack vaporizers. Due to the above formula, each vaporizer divides the total flow of liquefied natural gas equally, and the average value corresponds to the optimal liquefied natural gas flow.

[0075] As some embodiments, the process of obtaining the seawater flow rate required for the operation of each open-frame gasifier and intermediate medium gasifier includes:

[0076] The seawater flow rate Q required for the operation of the i-th intermediate medium gasifier SW-IFVi The formula for obtaining is:

[0077] Q SW-IFVi =Q LNG-IFVi ΔT LNG-IFVi / ΔT SW-IFVi / (b i0 +b i1 Q LNG-IFVi +…+b i9 Q 9 LNG-IFVi )

[0078] If Q SW-IFVi <Q SW-IFVi-min , then Q SW-IFVi =Q SW-IFVi-min ;

[0079] If Q SW-IFVi >Q SW-IFVi-max , then Q SW-IFVi =Q SW-IFVi-max ;

[0080] If Q LNG-IFVi >Q LNG-IFVi-max , then Q LNG-IFVi =Q LNG-IFVi-max ;

[0081] ΔT SW-IFVi ≤5

[0082] Among them, Q SW-IFVi is the seawater flow rate required by the i-th intermediate medium gasifier, Q LNG-IFVi is the liquefied natural gas flow rate of the i-th intermediate medium gasifier, ΔT LNG-IFVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th intermediate medium gasifier, ΔT SW-IFVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th intermediate medium gasifier. The environmental protection requirement ΔT SW-IFVi ≤5℃; b i0 、b i1 ,…b i8 and b i9 Represents the coefficient of different terms, which is a constant.

[0083] In the above constraints, the minimum film-forming flow rate of seawater for the i-th intermediate medium vaporizer is expressed as Q SW-IFVi-min , the maximum seawater flow is expressed as Q SW-IFVi-max and the maximum LNG flow rate is denoted as Q LNG-IFVi-max .

[0084] The process of obtaining the required total seawater flow includes:

[0085] The total flow rate of liquefied natural gas passing through the intermediate medium vaporizer is set to Q LNG-IFV , k 1 Intermediate medium gasifiers are in operation, k 1 =1,2,…,n,k 1 Total seawater flow rate Q of each intermediate medium vaporizer SW-IFV-k1 The formula for obtaining is:

[0086] Q SW-IFV-k1 =Q SW-IFV1 +Q SW-IFV2 +…+Q SW-IFVk1

[0087] Among them, Q SW-IFVk1 Indicates the kth 1 The seawater flow rate required for an open-frame vaporizer, k 1 =1, 2,…, n.

[0088] For k 1 The performance of the intermediate medium gasifier is similar, the liquefied natural gas flow rate of each intermediate medium gasifier is similar, and the seawater flow rate is similar. 1 Total seawater flow rate Q of each intermediate medium vaporizer SW-IFV-k1 The formula for obtaining is:

[0089] Q SW-IFV-k1 =k 1 (Q LNG-IFV / k 1 )ΔT LNG-IFVi / ΔT SW-IFVi / (b i0 +b i1 (Q LNG-IFV / k 1 )+…+b i9 (Q LNG-IFV / k 1 ) 9 )

[0090] The total flow rate of liquefied natural gas flowing through the intermediate medium vaporizer is expressed as Q LNG-IFV , Q LNG-IFV / k 1 represents the total liquefied natural gas flow rate of each intermediate medium vaporizer, k 1 The performance of the intermediate medium gasifier is approximately the same, with the lowest total seawater flow rate Q SW The formula for obtaining is:

[0091] Q SW =min{Q SW-IFV-1 , Q SW-IFV-2 , …, Q SW-IFV-n}

[0092] Corresponding to the minimum Q SW The number of operating units is the optimal number of operating units of the intermediate medium gasifier. Due to the above formula, each gasifier divides the total flow of liquefied natural gas equally, and the average value corresponds to the optimal liquefied natural gas flow.

[0093] As another embodiment, the above is the related content of the same type of independent combination of the open-frame gasifier and the intermediate medium gasifier, in addition to which, it also includes the lowest total seawater flow rate acquisition performed by the open-frame gasifier and the intermediate medium gasifier, wherein:

[0094] kth 2 The total seawater flow Q corresponding to the combined combination SW-h-k2 for:

[0095] Q SW-h-k2 =Q SW-IFV-k1 +Q SW-ORV-k

[0096] Among them, the joint combination index k 2 =1, 2, ..., q, q is the total number of joint combinations;

[0097] Minimum total seawater flow Q SW The formula for obtaining is:

[0098] Q SW =min{Q SW-h-1 , Q SW-h-2 , …, Q SW-h-q}

[0099] Corresponding to the minimum Q SW The number of open-frame gasifiers and intermediate medium gasifiers in operation in the combined combination is the optimal number of operating units. In the calculation process of the total seawater flow corresponding to the combined combination, the total flow of liquefied natural gas corresponding to the open-frame gasifier and the intermediate medium gasifier is used as the optimal total flow of liquefied natural gas corresponding to different types. Due to the above formula, for each type of gasifier, the total flow of liquefied natural gas is evenly divided, and the evenly divided value corresponds to the optimal liquefied natural gas flow of each gasifier.

[0100] The above technical solution of the present invention is described in conjunction with relevant drawings and specific data: Figure 2 As shown, this embodiment provides an optimized operation method for reducing the seawater flow rate of an open rack vaporizer (ORV) and an intermediate medium vaporizer (IFV), providing support for the energy-saving operation of the vaporizer of a liquefied natural gas station.

[0101] The liquefied natural gas station consists of four open-frame vaporizers of the same model (the first ORV vaporizer 1, the second ORV vaporizer 2, the third ORV vaporizer 3, and the fourth ORV vaporizer 4) connected in parallel. The minimum film-forming flow rate of seawater in each open-frame vaporizer is equal to Q SW-ORVi-min (m 3 / h)=3660, the maximum seawater flow rate of each open-frame vaporizer is equal to Q SW-ORVi-max (m 3 / h)=11000, the maximum liquefied natural gas flow rate of each open-frame vaporizer is equal to Q LNG-ORVi-max (m 3 / h)=900, environmental protection requires seawater temperature difference ΔT SW-ORVi ≤5℃.

[0102] The liquefied natural gas inlets flowing through all open-rack vaporizers are connected together, and the natural gas outlets flowing through all open-rack vaporizers are connected together. k open-rack vaporizers are in operation, and the seawater flow rate required for the operation of the i-th open-rack vaporizer is

[0103] Q SW-ORVi =Q LNG-ORVi ΔT LNG-ORVi / ΔT SW-ORVi / (a i0 +a i1 Q LNG-ORVi +…+a i9 Q 9 LNG-ORVi )

[0104] Q SW-ORVi is the seawater flow rate required by the i-th open-frame vaporizer, Q LNG-ORVi is the LNG flow rate of the i-th open-rack vaporizer, ΔT LNG-ORVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th open-rack vaporizer (℃). The liquefied natural gas inlet and outlet temperature differences of all running open-rack vaporizers are equal. i0 、a i1 , …a i8 and a i9 is a constant.

[0105] The total liquefied natural gas flow rate Q flowing through the open rack vaporizer LNG-ORV =800(m 3 / h) as an example, seawater enters the tops of four open-frame vaporizers from the seawater inlet pipe 5, and the seawater temperature is 18°C. The low-temperature seawater return water flowing down from the open-frame vaporizer enters the seawater return channel 6. According to environmental protection requirements, the seawater return temperature shall not be lower than 13°C. Liquefied natural gas is sent into each operating open-frame vaporizer through the liquefied natural gas inlet pipe 7. The temperature of the liquefied natural gas entering the open-frame vaporizer is -140°C. The natural gas is sent out through the liquefied natural gas outlet pipe 8, and the temperature of the natural gas is 10°C.

[0106] The four open-frame vaporizers in this embodiment have a constant a i0 =3.625, a i1 =-0.002398, a i2 =a i3 =…=a i9 = 0, the above-mentioned number selection method and load distribution method require the least total seawater flow, and the lowest total seawater flow Q SW The formula for obtaining is:

[0107] Q SW =min{Q SW-ORV-1 , Q SW-ORV-2 , Q SW-ORV-3 , Q SW-ORV-4}

[0108] =min{14004, 8991, 10980, 14640} = 8991

[0109] =Q SW-ORV-2

[0110] Corresponding to this minimum total seawater flow Q SW The optimal number of units is 2. Final conclusion: The optimal number of units is 2, each open-frame vaporizer takes 50% of the LNG flow, and the total seawater flow is the least, which is 8991 (m 3 / h).

[0111] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optimized operation method for reducing the seawater flow of ORV and IFV, characterized in that: include: Obtaining the seawater flow rate required for the operation of each vaporizer, wherein the vaporizer includes an open-frame vaporizer and an intermediate medium vaporizer; The vaporizers are combined, and the total seawater flow corresponding to different combinations of vaporizers is calculated according to the seawater flow required for operation; The total seawater flow rates corresponding to different combinations of vaporizers were compared to obtain the lowest total seawater flow rate, the optimal number of operating units, and the optimal liquefied natural gas flow rate corresponding to each vaporizer.

2. The method according to claim 1, characterized in that In a liquefied natural gas station, several of the gasifiers are connected in parallel, wherein the liquefied natural gas inlets of the several gasifiers are connected together, the natural gas outlets are connected together, and the seawater inlets are connected together.

3. The method according to claim 1, characterized in that The process of obtaining the seawater flow rate required for the operation of the open-frame vaporizer is: Q SW-ORVi =Q LNG-ORVi ΔT LNG-ORVi / ΔT SW-ORVi / (a i0 +a i1 Q LNG-ORVi +…+a i9 Q 9 LNG-ORVi ) stIf Q SW-ORVi <Q SW-ORVi-min , then Q SW-ORVi =Q SW-ORVi-min ; If Q SW-ORVi >Q SW-ORVi-max , then Q SW-ORVi =Q SW-ORVi-max ; If Q LNG-ORVi >Q LNG-ORVi-max , then Q LNG-ORVi =Q LNG-ORVi-max ; ΔT SW-ORVi ≤5 Among them, Q SW-ORVi is the seawater flow rate required for the operation of the i-th open-frame vaporizer, Q LNG-ORVi is the LNG flow rate of the i-th open-rack vaporizer, ΔT LNG-ORVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th open-rack vaporizer, ΔT SW-ORVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th open-frame vaporizer, a i0 、a i1 , …a i8 and a i9 Represent different coefficients respectively, are constants, Q SW-ORVi-min represents the minimum film-forming flow rate of seawater for the i-th open-frame vaporizer, Q SW-ORVi-max represents the maximum seawater flow rate of the i-th open-frame vaporizer, Q LNG-ORVi-max represents the maximum liquefied natural gas flow rate of the i-th open-rack vaporizer.

4. The method according to claim 1, characterized in that The total seawater flow rate corresponding to different combinations of open-frame vaporizers is the sum of the seawater flow rates required for the operation of the open-frame vaporizers in different combinations of the open-frame vaporizers. The total seawater flow rate calculation formula is: Q SW-ORV-k =Q SW-ORV1 +Q SW-ORV2 +…+Q SW-ORVk If each open rack vaporizer is the same model, then Q SW-ORV-k =k(Q LNG-ORV / k)ΔT LNG-ORVi / ΔT SW-ORVi / (a i0 +a i1 (Q LNG-ORV / k)+…+a i9 (Q LNG-ORV / k) 9 ) Among them, Q SW-ORV-k represents the total seawater flow rate of k open-frame vaporizers, Q SW-ORVk represents the seawater flow rate required by the kth open-frame vaporizer, k = 1, 2, ..., m, m represents the total number of open-frame vaporizers, k represents the number of the open-frame vaporizer, ΔT LNG-ORVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th open-rack vaporizer, ΔT SW-ORVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th open-frame vaporizer, a i0 、a i1 , …a i8 and a i9 Represent different coefficients, Q LNG-ORV represents the total flow rate of liquefied natural gas flowing through k open-rack vaporizers.

5. The method according to claim 1, characterized in that The process of obtaining the seawater flow rate required for the operation of the intermediate medium gasifier includes: Q SW-IFVi =Q LNG-IFVi ΔT LNG-IFVi / ΔT SW-IFVi / (b i0 +b i1 Q LNG-IFVi +…+b i9 Q 9 LNG-IFVi ) stIf Q SW-IFVi <Q SW-IFVi-min , then Q SW-IFVi =Q SW-IFVi-min ; If Q SW-IFVi >Q SW-IFVi-max , then Q SW-IFVi =Q SW-IFVi-max ; If Q LNG-IFVi >Q LNG-IFVi-max , then Q LNG-IFVi =Q LNG-IFVi-max ; ΔT SW-IFVi ≤5 Among them, Q SW-IFVi is the seawater flow rate required by the i-th intermediate medium gasifier, Q LNG-IFVi is the liquefied natural gas flow rate of the i-th intermediate medium gasifier, ΔT LNG-IFVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th intermediate medium gasifier, ΔT SW-IFVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th intermediate medium vaporizer; b i0 , b i1 ,…b i8 and b i9 Represents the coefficient of different terms, which is a constant; Q SW-IFVi-min represents the minimum film-forming flow rate of seawater for the i-th intermediate medium vaporizer, Q SW-IFVi-max represents the maximum seawater flow rate and Q of the i-th intermediate medium vaporizer LNG-IFVi-max represents the maximum liquefied natural gas flow rate of the i-th intermediate medium vaporizer.

6. The method according to claim 1, characterized in that The total seawater flow rate corresponding to different combinations of intermediate medium type vaporizers is the sum of the seawater flow rates required for the operation of the intermediate medium type vaporizers in different combinations of intermediate medium type vaporizers, wherein the total seawater flow rate is calculated as follows: Q SW-IFV-k1 =Q SW-IFV1 +Q SW-IFV2 +…+Q SW-IFVk1 If the intermediate medium gasifier is the same model, then Q SW-IFV-k1 =(Q LNG-IFV / k1)ΔT LNG-IFVi / ΔT SW-IFVi / (b i0 +b i1 (Q LNG-IFV / k1)+…+b i9 (Q LNG- IFV / k1) 9 ) Q SW-IFV-k1 represents the total seawater flow rate of k1 intermediate medium vaporizers, Q SW-IFV1 represents the seawater flow rate required by the k1th open-frame vaporizer, k1 = 1, 2, ..., n, n represents the total number of intermediate medium vaporizers; k1 represents the number of the open-frame vaporizer, ΔT LNG-IFVi is the difference between the natural gas outlet temperature and the liquefied natural gas inlet temperature of the i-th intermediate medium gasifier, ΔT SW-IFVi is the difference between the seawater inlet temperature and the seawater outlet temperature of the i-th intermediate medium vaporizer, b i0 、b i1 ,…b i8 and b i9 Denotes the coefficients of different terms, Q LNG-IFV It represents the total flow rate of liquefied natural gas flowing through k1 intermediate medium vaporizers.

7. The method according to claim 1, characterized in that The process of comparing the total seawater flow rates for different combinations of vaporizers includes: The minimum value of the total amount of seawater in different combinations of vaporizers is selected to obtain the lowest total amount of seawater, and the vaporizer combination corresponding to the lowest total amount of seawater is determined to obtain the number of vaporizers as the optimal operating number of vaporizers. If the models of the vaporizers are the same, the total flow of liquefied natural gas is evenly divided according to the optimal operating number, and the evenly divided result is used as the optimal liquefied natural gas flow corresponding to each vaporizer.

8. The method according to claim 2, characterized in that: The process of combining the gasifiers includes: respectively targeting the open-frame gasifier and the intermediate-medium gasifier, and adjusting the number of operating open-frame gasifiers and the intermediate-medium gasifier to obtain different combinations of gasifiers.

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