Product energy consumption calculation method based on air separation system

Abstract

The invention provides a product energy consumption calculation method based on an air separation system, and the method employs a segmented energy consumption calculation method, and can accurately calculate the energy consumption of products with different forms and different pressures, such as the energy consumption of gaseous and liquid product gases, and normal pressure and high pressure gases. The'air separation energy-saving 'effect caused by a nitrogen energy consumption reference value provided by a standard adopted by a machine is eliminated, and the energy consumption of an energy-consuming working medium is accurately evaluated. In addition, the method also realizes modular calculation, does not need to allocate for each device, and realizes packaging processing.

Description

Technical Field

[0001] The invention belongs to the technical field of energy consumption calculation, and relates to a product energy consumption calculation method based on an air separation system. Background Art

[0002] The air separation system usually uses a cryogenic process to provide the necessary compressed air, oxygen, and nitrogen for production. That is, it uses the difference in boiling points of different gases to provide medium-pressure and high-pressure nitrogen from a nitrogen compression system to cool and liquefy the air in a distillation tower to achieve the purpose of separating mixed gases. It is an important public engineering facility.

[0003] The air separation system has a low temperature, high energy consumption, and rich products. Regardless of whether it is used as a raw material or an energy-consuming working fluid, according to the standard of the "General Rules for Comprehensive Energy Consumption Calculation" (GB / T 2589-2020), the energy consumption of the air separation system should be included in the comprehensive energy consumption calculation, and the reference value of the energy-consuming working fluid discount coefficient is specified. With the commissioning of large-scale air separation system units, blindly increasing or decreasing energy consumption according to the reference values ​​in the "General Rules for Comprehensive Energy Consumption Calculation" will lead to large deviations. For example, taking a certain air separation unit as an example, the total energy consumption of the air compressor unit in a certain month was 24,000tce, which was equivalent to 1,680tce of standard coal. 20 million Nm2 of atmospheric pressure nitrogen was delivered 3 , 25,000 Nm of liquid oxygen delivered 3 , external liquid argon 650,000 Nm 3 , 14 million Nm of oxygen delivered 3 , external nitrogen pressure 10 million Nm 3 , self-use nitrogen 15 million Nm 3 , 40 million Nm of oxygen for own use 3 According to the recommended values ​​of Table B.1 "Coefficient of Standard Coal Conversion of Main Energy Consumption Mediums" in "GB / T 2589-2020 General Rules for Comprehensive Energy Consumption Calculation", the external delivery of atmospheric pressure nitrogen, liquid oxygen, liquid argon, external delivery of oxygen and nitrogen, etc., shall be 0.4000kgce / Nm 3 , the energy consumption of external energy-consuming fluids is reduced by 17870tce, the energy consumption of self-used energy-consuming fluids is 6130tce, and the discount coefficient is 0.11kgce / Nm 3 , resulting in the phenomenon of "air separation energy saving" where the more gas the air separation system sends out, the lower the energy consumption. In addition, when multiple devices share an air separation system, it is impossible to scientifically and accurately allocate the working fluid energy consumption between the devices, resulting in an energy consumption blind spot.

[0004] To this end, based on the low-temperature separation principle and refrigeration process of the air separation system, a method for calculating the energy consumption of products produced in sections according to pressure equalities was invented, which can accurately calculate the actual energy consumption of energy-consuming working fluids such as nitrogen and oxygen. Summary of the invention

[0005] The purpose of the present invention is to provide a method for calculating product energy consumption based on an air separation system to solve the problem of inaccurate product energy consumption calculation in the existing air separation system.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present application provides a method for calculating product energy consumption based on an air separation system, comprising: The air separation system is divided into a liquid air preparation unit, a liquid air separation unit and a nitrogen compression unit according to the process flow, wherein the nitrogen compression unit includes a first-stage compression unit, a second-stage compression unit and a third-stage compression unit; For the liquid air preparation unit, the energy consumption per unit volume is determined according to the total energy consumption and effective gas production of the liquid air preparation unit. 1 ; For the liquid air separation unit, the capacity is determined to be 10000 Nm based on the power used by the delivery pump and the quality of the liquid product. 3 Energy consumption of gas 液v ; For the nitrogen compression unit, the capacity is calculated to be 10000 Nm based on the nitrogen compression energy consumption and the gas volume produced by each compression unit. 3 The gas energy consumption of each compression unit during gas operation.

[0007] Preferably, the energy consumption per unit volume is determined according to the total energy consumption and effective gas output of the liquid air preparation unit. 1 include: The total energy consumption of the liquid air preparation unit is: (1) In formula (1), E 1 is the total energy consumption of the liquid air preparation unit, E 电 、E 9.8汽 、E 1.27汽 、E 冷凝液 The electricity consumed by the liquid air preparation unit, the 9.8Mpa steam energy, the 1.27Mpa steam energy and the quality of the external condensate, k 电 , k 9.8汽 , k 1.27汽 , k 冷凝液 It is the discount coefficient of electric energy, 9.8Mpa steam energy, 1.27Mpa steam energy and external condensate; The effective gas output is: Q 产 =Q 0 -Q 污氮气 -Q 粗氩气 -Q其他 (2) In formula (2), Q 0 Q is the air volume inhaled by the air compressor. 污氮气 is the amount of polluted nitrogen delivered, Q 粗氩气 is the crude argon gas delivery rate, Q 其他 Venting volume for other non-product gases; Energy consumption per unit volume 1 for: , unit: tce / 10,000 Nm 3 (3).

[0008] Preferably, the capacity is determined to be 10000 Nm according to the power used by the delivery pump and the quality of the liquid product. 3 Energy consumption of gas 液v include: The energy required for transporting liquid products is (4) In formula (4), E 泵 The power consumption of the delivery pump is m is the mass of produced liquid product, unit: tce / t; 10000Nm 3 Energy consumption of gas 液v for e 液v =10n / 22.4× e 2 (5) In formula (5), n is the molecular weight of the product.

[0009] Preferably, the capacity is calculated to be 10000 Nm based on the nitrogen compression energy consumption and the gas volume produced by each compression unit. 3 The gas energy consumption of each compression unit in gas mode includes: Nitrogen compression energy consumption (6) In formula (1), E 3 is the total energy consumption of the nitrogen compression unit, E 电 、E 9.8汽 、E 1.27汽 、E 冷凝液 The electric energy consumed by the nitrogen compression unit, the 9.8Mpa steam energy, the 1.27Mpa steam energy and the quality of the external condensate, k 电 , k 9.8汽 , k 1.27汽 , k 冷凝液 It is the discount coefficient of electric energy, 9.8Mpa steam energy, 1.27Mpa steam energy and external condensate; The first stage gas energy consumption is (7) The second stage gas energy consumption is + e 31 (8) The third stage gas energy consumption is + e 31 + e 32 (9) In formulas (7)-(9), Q 31 , Q 32 , Q 33 The gas volumes produced by the first compression unit, the second compression unit and the third compression unit respectively; For 10000Nm 3 Gas, the energy consumption of each compression unit is: Energy consumption of gas produced in the first stage: e 一段 =e 1 +e 31 ; Energy consumption of gas produced in the second stage: e 二段 =e 1 +e 31 +e 32 ; Energy consumption of gas produced in the third stage: e 三段 =e 1 +e 31 +e 32 +e 33 .

[0010] The present invention has the following beneficial effects: In this application, a segmented energy consumption calculation method is used to accurately calculate the energy consumption of products of different forms and pressures, such as gaseous and liquid product gases, and the energy consumption of normal pressure and high pressure gases, eliminating the "air separation energy saving" effect caused by the nitrogen energy consumption reference value provided by the mechanical standard, and accurately evaluating the energy consumption of energy-consuming working fluids. In addition, this method also realizes modular calculation, without the need to apportion for each device, and realizes package processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Diagram for air separation system division. DETAILED DESCRIPTION

[0012] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0013] The present application embodiment provides a method for calculating product energy consumption based on an air separation system, the method comprising: S01: According to the process flow, the air separation system is divided into a liquid air preparation unit, a liquid air separation unit and a nitrogen compression unit, wherein the nitrogen compression unit includes a first-stage compression unit, a second-stage compression unit and a third-stage compression unit.

[0014] In the embodiment of the present application, the product energy consumption of the air separation system includes the basic energy consumption of liquid air, the separation energy consumption and the nitrogen compression energy consumption. Therefore, the air separation system is divided into a liquid air preparation unit, a liquid air separation unit and a nitrogen compression unit according to the process flow, and the energy consumption of each unit is calculated separately, as shown in the attached figure. Figure 1 shown.

[0015] The liquid air preparation unit includes the components from the air entering the air separation system to the outlet of the lower tower of the distillation tower, and also includes the liquid delivery pumps for cold recovery and external gas delivery within this range, such as the dirty liquid nitrogen pump, crude argon pump, and high-pressure liquid oxygen pump for external oxygen delivery. The energy consumed by the liquid air preparation unit is mainly 9.8Mpa steam, 1.27Mpa steam, electricity, external condensate and system energy.

[0016] The liquid air separation unit includes a liquid air distillation tower, a crude argon tower, a subcooler and a liquid product delivery pump, and the energy consumed is mainly the energy used for product delivery.

[0017] The nitrogen compression unit includes nitrogen compression equipment and its ancillary facilities, and the energy consumed is mainly steam for the nitrogen compressor, electricity and electricity for its ancillary equipment. In the embodiment of the present application, the nitrogen compression unit is divided into a first-stage compression unit, a second-stage compression unit and a third-stage compression unit according to different gas products.

[0018] In an embodiment of the present application, the products produced by the air separation system include oxygen, nitrogen and non-product gas, wherein oxygen includes oxygen and liquid oxygen, nitrogen includes atmospheric pressure nitrogen, medium pressure nitrogen, high pressure nitrogen, high pressure nitrogen and liquid nitrogen, and non-product gas includes crude argon and contaminated nitrogen.

[0019] S02: For the liquid air preparation unit, determine the energy consumption per unit volume e according to the total energy consumption and effective gas output of the liquid air preparation unit. 1 .

[0020] According to the General Rules for Comprehensive Energy Consumption Calculation (GB / T 2589-2020), the total energy consumption of 9.8Mpa steam, 1.27Mpa steam, electricity, external condensate and system energy consumed by the liquid air preparation unit is: (1) In formula (1), E 1 is the total energy consumption of the liquid air preparation unit, E 电 、E 9.8汽 、E 1.27汽 、E冷凝液 The electricity consumed by the liquid air preparation unit, the 9.8Mpa steam energy, the 1.27Mpa steam energy and the quality of the external condensate, k 电 , k 9.8汽 , k 1.27汽 , k 冷凝液 It is the discount coefficient for electric energy, 9.8Mpa steam energy, 1.27Mpa steam energy and external condensate.

[0021] According to the law of conservation of materials, the effective gas output of the liquid air preparation unit is: Q 产 =Q 0 -Q 污氮气 -Q 粗氩气 -Q 其他 (2) In formula (2), Q 0 Q is the air volume inhaled by the air compressor. 污氮气 is the amount of polluted nitrogen delivered, Q 粗氩气 is the crude argon gas delivery rate, Q 其他 The venting volume for other non-product gases.

[0022] According to the total energy consumption E of the liquid air preparation unit 1 and effective gas production Q 产 Calculate the energy consumption per unit volume e 1 for: , unit: tce / 10,000 Nm 3 (3).

[0023] S03: For the liquid air separation unit, the capacity is determined to be 10000 Nm based on the power used by the delivery pump and the quality of the liquid product. 3 Energy consumption of gas 液v .

[0024] The energy consumed by the liquid air separation unit is mainly the energy used for product transportation, including the energy used for gas product transportation and the energy used for liquid product transportation. For gas products, they are extracted from the top of the lower tower and the top of the upper tower of the distillation tower, and no transportation energy is required. Therefore, the energy consumption of the liquid air separation unit is mainly the energy used for liquid product transportation, that is, the electricity used by the liquid product transportation pump.

[0025] For liquid products, the transport energy is (4) In formula (4), E 泵 The power consumption of the delivery pump is m It is the quality of produced liquid product, unit: tce / t.

[0026] Since the liquid in the liquid air separation unit comes from the gas produced by the liquid air preparation unit, in order to calculate the energy consumption of the raw gas corresponding to the liquid product, it is necessary to calculate according to the ideal gas equation. 3 The mass of the gas is 10*n / 22.4 tons, where n is the molecular weight of the product, and the capacity is 10000Nm 3 Energy consumption of liquid air separation unit when gas is 液v for e 液v =10n / 22.4× e 2 (5) In formula (5), n is the molecular weight of the product.

[0027] For the comprehensive energy consumption of the liquid air separation unit and the liquid air preparation unit, the energy consumption of 10000Nm3 gas is: e = e 1 , 1 ton of liquid is equivalent to 10000Nm 3 Gas energy consumption: e = e 1 + e 液v .

[0028] S04: For the nitrogen compression unit, the capacity is calculated to be 10000 Nm based on the nitrogen compression energy consumption and the gas volume produced by each compression unit. 3 The gas energy consumption of each compression unit during gas operation.

[0029] The nitrogen compression unit uses the atmospheric pressure nitrogen separated by the liquid air separation unit as raw material, and consumes high-pressure steam and electricity to produce medium-pressure nitrogen and high-pressure nitrogen. According to the "General Rules for Calculation of Comprehensive Energy Consumption" (GB / T 2589-2020), the calculation formula for the steam, electricity and electricity consumed by the nitrogen compressor and its ancillary equipment consumed by the nitrogen compression unit is the same as formula (1), where 9.8Mpa steam, 1.27Mpa steam, electricity, and external condensate are all data consumed by the nitrogen compression unit. In other words, the energy consumption of nitrogen compression is: (6) In formula (1), E 3 is the total energy consumption of the nitrogen compression unit, E 电 、E 9.8汽 、E 1.27汽 、E 冷凝液 The electric energy consumed by the nitrogen compression unit, the 9.8Mpa steam energy, the 1.27Mpa steam energy and the quality of the external condensate, k 电 , k 9.8汽, k 1.27汽 , k 冷凝液 It is the discount coefficient for electric energy, 9.8Mpa steam energy, 1.27Mpa steam energy and external condensate.

[0030] In the embodiment of the present application, the nitrogen compression unit produces nitrogen of different pressures by staged compression, that is, the first stage compression unit produces nitrogen of 0.7Mpa, and the gas volume is Q 31 The second compression unit produces 2.0Mpa nitrogen with a gas volume of Q 32 The third compression unit produces 4.0Mpa nitrogen with a gas volume of Q 33 In the nitrogen compression unit, the first compression unit, the second compression unit and the third compression unit share the total energy consumption of the nitrogen compression unit. The energy consumption of the gas produced by the three compression units is: The first stage gas energy consumption is (7) The second stage gas energy consumption is + e 31 (8) The third stage gas energy consumption is + e 31 + e 32 (9) In formulas (7)-(9), Q 31 , Q 32 , Q 33 They are the gas volumes produced by the first compression unit, the second compression unit and the third compression unit respectively.

[0031] For a capacity of 10000Nm 3 Gas, the energy consumption of each compression unit is: Energy consumption of gas produced in the first stage: e 一段 =e 1 +e 31 ; Energy consumption of gas produced in the second stage: e 二段 =e 1 +e 31 +e 32 ; Energy consumption of gas produced in the third stage: e 三段 =e 1 +e 31 +e 32 +e 33 .

[0032] Taking the air separation system of a factory as an example, the designed air intake volume is 250000Nm 3 / h, oxygen output is 30000Nm 3 / h, atmospheric pressure nitrogen output is 40000Nm 3 / h, 0.7Mpa nitrogen output is 20000Nm 3 / h, 4.0Mpa nitrogen output is 20000Nm 3 / h, the amount of polluted nitrogen discharged is 100000Nm 3 / h, the crude argon volume is 40000Nm3 / .

[0033] According to the product energy consumption calculation method provided in the embodiment of the present application, the air compressor energy consumption, equipment power consumption, standard reduction coefficient, and total energy consumption E of the liquid air preparation unit are calculated. 1 The energy consumption per unit volume is shown in Table 1, the equipment energy consumption and total energy consumption of the liquid air separation unit are shown in Table 2, and the energy consumption of the nitrogen compression unit is shown in Table 3.

[0034] Table 1: Energy consumption data of liquid air preparation unit Table 2: Energy consumption data of liquid air separation unit Table 3: Energy consumption data of nitrogen compression unit The energy consumption of the first stage of the nitrogen compressor to produce 0.7Mpa gas is: 一段 =e 1 +e 31 =1.315tce / 10,000Nm 3 ; The energy consumption of the second stage of the nitrogen compressor to produce 4.0 MPa gas is: 二段 =e 1 +e 31 +e 32 =1.7641tce / 10,000Nm 3 ; The energy consumption of the third stage of the nitrogen compressor to produce 4.0 MPa gas is: 三段 =e 1 +e 31 +e 32 +e 33 =2.21tce / 10,000Nm 3 .

[0035] It can be seen from the above examples that the product energy consumption calculation method provided in the embodiments of the present application can accurately calculate the actual energy consumption of the gas produced in stages by the liquid air preparation unit, the liquid air separation unit and the nitrogen compression unit, thereby avoiding the "air separation energy saving" caused by directly adopting the standard recommended values.

[0036] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for calculating product energy consumption based on an air separation system, characterized in that: include: The air separation system is divided into a liquid air preparation unit, a liquid air separation unit and a nitrogen compression unit according to the process flow, wherein the nitrogen compression unit includes a first-stage compression unit, a second-stage compression unit and a third-stage compression unit; For the liquid air preparation unit, the energy consumption per unit volume e1 is determined according to the total energy consumption and effective gas output of the liquid air preparation unit; For the liquid air separation unit, the capacity is determined to be 10000 Nm based on the power used by the delivery pump and the quality of the liquid product. 3 Energy consumption of gas 液v ; For the nitrogen compression unit, the capacity is calculated to be 10000 Nm based on the nitrogen compression energy consumption and the gas volume produced by each compression unit. 3 The gas energy consumption of each compression unit during gas operation.

2. The method for calculating product energy consumption based on an air separation system according to claim 1, characterized in that: The energy consumption per unit volume e1 is determined based on the total energy consumption and effective gas output of the liquid air preparation unit, including: The total energy consumption of the liquid air preparation unit is: （1） In formula (1), E1 is the total energy consumption of the liquid air preparation unit, E 电 、E 9.8汽 、E 1.27汽 、E 冷凝液 The electricity consumed by the liquid air preparation unit, the 9.8Mpa steam energy, the 1.27Mpa steam energy and the quality of the external condensate, k 电 , k 9.8汽 , k 1.27汽 , k 冷凝液 It is the discount coefficient of electric energy, 9.8Mpa steam energy, 1.27Mpa steam energy and external condensate; The effective gas output is: Q 产 =Q0-Q 污氮气 -Q 粗氩气 -Q 其他 (2) In formula (2), Q0 is the air volume at the air compressor intake, Q 污氮气 is the amount of polluted nitrogen delivered, Q 粗氩气 is the crude argon gas delivery rate, Q 其他 Venting volume for other non-product gases; The energy consumption per unit volume e1 is: , unit: tce / 10,000 Nm 3 (3).

3. The method for calculating product energy consumption based on an air separation system according to claim 1, characterized in that: The capacity is determined to be 10000Nm according to the power used by the delivery pump and the quality of the liquid product. 3 Energy consumption of gas 液v include: The energy required for transporting liquid products is (4) In formula (4), E 泵 The power consumption of the delivery pump is m is the mass of produced liquid product, unit: tce / t; 10000Nm 3 Energy consumption of gas 液v for e 液v =10n / 22.4× e 2 (5) In formula (5), n is the molecular weight of the product.

4. The method for calculating product energy consumption based on an air separation system according to claim 1, characterized in that: According to the nitrogen compression energy consumption and the gas volume produced by each compression unit, the production capacity is calculated to be 10000Nm 3 The gas energy consumption of each compression unit in gas mode includes: Nitrogen compression energy consumption (6) In formula (1), E3 is the total energy consumption of the nitrogen compression unit, E 电 、E 9.8汽 、E 1.27汽 、E 冷凝液 The electric energy consumed by the nitrogen compression unit, the 9.8Mpa steam energy, the 1.27Mpa steam energy and the quality of the external condensate, k 电 , k 9.8汽 , k 1.27汽 , k 冷凝液 It is the discount coefficient of electric energy, 9.8Mpa steam energy, 1.27Mpa steam energy and external condensate; The first stage gas energy consumption is (7) The second stage gas energy consumption is + e 31 (8) The third stage gas energy consumption is + e 31 + e 32 (9) In formulas (7)-(9), Q 31 , Q 32 , Q 33 The gas volumes produced by the first compression unit, the second compression unit and the third compression unit respectively; For 10000Nm 3 Gas, the energy consumption of each compression unit is: Energy consumption of gas produced in the first stage: e 一段 =e1+e 31 ; Energy consumption of gas produced in the second stage: e 二段 =e1+e 31 +e 32 ; Energy consumption of gas produced in the third stage: e 三段 =e1+e 31 +e 32 +e 33 .

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