A molecular sieve adsorption energy-saving system

Abstract

The present invention provides a molecular sieve adsorption energy-saving system, comprising a preheater connected in sequence, two steam heaters running in parallel, and a molecular sieve adsorber; the steam heater comprises a regeneration gas inlet, a regeneration gas outlet, a steam inlet, and a steam outlet; the preheater comprises a gas side inlet, a gas side outlet, a water side inlet, and a water side outlet, the gas side outlet is connected to the regeneration gas inlet of the steam heater, and the regeneration gas outlet of the steam heater is connected to the molecular sieve adsorber; the regenerated dirty nitrogen gas is first passed into the preheater to be heated by low-temperature hot water, then passed into the steam heater to be heated by steam, and finally passed into the molecular sieve adsorber to be discharged after exothermic analysis. The technical solution of the present invention can reduce the steam consumption of the molecular sieve adsorption device.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieve adsorption in coal chemical industry, and in particular to a molecular sieve adsorption energy-saving system. Background Art

[0002] The molecular sieve adsorption device plays a key role in air purification. It uses the selective adsorption characteristics of the adsorbent and adopts the temperature swing adsorption method to continuously separate the moisture and CO in the raw air. 2 , hydrocarbons and other harmful components. When the temperature is low (about 15°C), the molecular sieve has a large adsorption capacity, and when the temperature is high, the adsorption capacity is small. By periodically changing the bed temperature, the water and CO in the raw air can be continuously separated. 2 The purpose of adsorbent desorption regeneration is an endothermic process. The regeneration gas is heated to 213°C by a steam heater and then passes through the bed to remove the adsorbed CO 2 , H 2 Desorption of impurities such as O and hydrocarbons.

[0003] In the prior art, waste heat recovery stations are set up in integrated refining and chemical projects to centrally recover low-temperature heat from refining and chemical plants. Since the number of heat-generating plants exceeds the number of heat-consuming plants, a large amount of waste heat is generated. Summary of the invention

[0004] According to the above technical problem that the steam consumption of the molecular sieve adsorption device in the existing refining and chemical integration project is large, a molecular sieve adsorption energy-saving system is provided.

[0005] The technical means adopted by the present invention are as follows:

[0006] A molecular sieve adsorption energy-saving system comprises a preheater, two steam heaters operating in parallel and a molecular sieve adsorber connected in sequence;

[0007] The steam heater comprises a regeneration gas inlet, a regeneration gas outlet, a steam inlet and a steam outlet; the preheater comprises a gas side inlet, a gas side outlet, a water side inlet and a water side outlet, the gas side outlet is connected to the regeneration gas inlet of the steam heater, and the regeneration gas outlet of the steam heater is connected to the molecular sieve adsorber;

[0008] The regenerated contaminated nitrogen gas is first passed into the preheater to be heated by low-temperature hot water, then passed into the steam heater to be heated by steam, and finally passed into the molecular sieve adsorber to be exothermic and analyzed before being discharged.

[0009] Furthermore, low-temperature hot water is introduced into the preheater through the water side inlet to heat the regenerated dirty nitrogen gas, and then discharged through the water side outlet; steam is introduced into the steam heater through the steam inlet to heat the regenerated dirty nitrogen gas, and then discharged through the steam outlet, and condensed and sent to the pipeline network as process condensate.

[0010] Furthermore, the regenerated dirty nitrogen at 24°C is heat exchanged with the low-temperature hot water at 95°C in the preheater, is heated to 85°C by the low-temperature hot water, and then passes into the steam heater, is heated to 213°C by the steam at 2.2Mpa and 226°C, and then passes into the molecular sieve adsorber, and the steam is condensed to 120°C and sent to the pipeline as process condensate.

[0011] Furthermore, the gas side outlet of the preheater is of bell-mouth design, a differential pressure transmitter is provided at the gas side inlet and outlet, the resistance at the gas side outlet is controlled within 150Pa, and the resistance at the heat exchange core inside the preheater is controlled within 100Pa.

[0012] Furthermore, isolation valves are provided at the water side inlet and the water side outlet of the preheater.

[0013] Furthermore, the gas side outlet is also provided with an online water content analyzer.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] The molecular sieve adsorption energy-saving system provided by the present invention, by setting a preheater, utilizes the factory waste heat low-temperature hot water to preheat the regenerated gas to 85°C, and then further heats the regenerated gas to 213°C by steam, thereby achieving the purpose of saving steam and making full use of the waste heat.

[0016] Based on the above reasons, the present invention can be widely promoted in the field of molecular sieve adsorption in coal chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 This is a process flow chart of the molecular sieve adsorption energy-saving system of the present invention.

[0019] In the figure: 1. Preheater; 2. Steam heater. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0023] Example 1

[0024] like Figure 1 As shown, the present invention provides a molecular sieve adsorption energy-saving system, comprising a preheater connected in sequence, two steam heaters operating in parallel, and a molecular sieve adsorber;

[0025] The steam heater comprises a regeneration gas inlet, a regeneration gas outlet, a steam inlet and a steam outlet; the preheater comprises a gas side inlet, a gas side outlet, a water side inlet and a water side outlet, the gas side outlet is connected to the regeneration gas inlet of the steam heater, and the regeneration gas outlet of the steam heater is connected to the molecular sieve adsorber;

[0026] The regenerated contaminated nitrogen gas is first passed into the preheater to be heated by low-temperature hot water, then passed into the steam heater to be heated by steam, and finally passed into the molecular sieve adsorber to be exothermic and analyzed before being discharged.

[0027] Furthermore, low-temperature hot water is introduced into the preheater through the water side inlet to heat the regenerated dirty nitrogen gas, and then discharged through the water side outlet; steam is introduced into the steam heater through the steam inlet to heat the regenerated dirty nitrogen gas, and then discharged through the steam outlet, and condensed and sent to the pipeline network as process condensate.

[0028] Furthermore, the regenerated dirty nitrogen at 24°C is heat exchanged with the low-temperature hot water at 95°C in the preheater, is heated to 85°C by the low-temperature hot water, and then passes into the steam heater, is heated to 213°C by the steam at 2.2Mpa and 226°C, and then passes into the molecular sieve adsorber, and the steam is condensed to 120°C and sent to the pipeline as process condensate.

[0029] Furthermore, the gas side outlet of the preheater is of bell-mouth design, and a differential pressure transmitter is provided at the gas side inlet and outlet to monitor the working status of the preheater. The resistance at the gas side outlet is controlled within 150Pa, and the resistance at the heat exchange core inside the preheater is controlled within 100Pa.

[0030] Furthermore, isolation valves are provided at the water inlet and outlet of the preheater. When the preheater needs to be repaired, the isolation valves at the water inlet and outlet can be closed and isolated. At the same time, controlling the isolation valve to be closed when the preheater is not started can save the consumption of low-temperature hot water.

[0031] Furthermore, the gas side outlet is also provided with an online water content analyzer for real-time monitoring of heat exchanger leakage. When the heat exchange tube leaks, an alarm can be immediately sounded to avoid incomplete regeneration of the molecular sieve and ensure safe operation of the device.

[0032] Furthermore, the low-temperature hot water is provided by low-temperature waste heat from the factory.

[0033] Furthermore, after starting the preheater, each of the steam heaters is set to operate at 75% of the device load. When the preheater is deactivated, the two steam heaters can meet the 100% load condition requirement.

[0034] Furthermore, the differential pressure transmitter model is Yokogawa EJA120E-JE95J-917EA / NS21.

[0035] Furthermore, the water content online analyzer model is ORTHODYNE OZR5000.

[0036] Furthermore, the isolation valve model is Shanghai Electric 0600-9150-P-31-2236MTT.

[0037] Furthermore, the preheater adopts a floating head structure, and the rear end tube bundle can achieve free expansion to reduce thermal stress; the internal heat exchange tube of the preheater adopts a bimetallic rolled fin tube structure to maximize the fin ratio; the air intake side of the preheater can be analyzed by CFD simulation to optimize the flow field distribution and avoid impact damage; the water side inlet can also be simulated by CFD to optimize the interface layout of the collecting pipe and the distribution pipe to achieve uniform distribution without dead pipes.

[0038] The present invention mainly utilizes low-temperature hot water to preheat the regenerated gas to 85°C, and then further heats the regenerated gas to 213°C by steam, thereby achieving the purpose of saving steam. The application of the preheater saves steam consumption and can balance the low-temperature heat of the entire plant; at the same time, the process steam condensate temperature is set to 80°C. In order to reduce the condensate grid-connected temperature difference and reduce the heat exchange area of ​​the steam heater, the condensation temperature of the steam discharged from the steam heater is increased to 120°C, thereby reducing the equipment investment cost.

[0039] This example uses ASPEN PLUS 7.2 to perform process simulation calculations, calculate the heat exchange process in detail, and verify the feasibility of the process:

[0040] First, the model is built according to the process flow chart, one is the process without a preheater, and the other is the process provided by the present invention with a preheater;

[0041] PENG-ROB was selected as the physical property analysis method. Given the inlet parameters of the dirty nitrogen gas and the temperature after heating, model one simulated and calculated the 2.2Mpa steam consumption value. Model two adjusted the low-temperature hot water flow rate, and at the same time adjusted the 2.2Mpa steam flow rate according to the temperature of the regenerated gas after leaving the steam heater. After multiple simulations and calculations, the 2.2Mpa consumption value required for heating the dirty nitrogen gas was obtained, and compared with the results of model one. The comparison results are shown in the following table.

[0042] No preheater With preheater <![CDATA[Regenerated waste nitrogen gas flow rate (Nm 3 / h)]]> 100,000 100,000 Steam consumption (t / h) 11.2 8

[0043] It can be seen from the table that if the preheating process is adopted, the steam consumption can be effectively reduced. In actual production, reducing steam consumption is of great significance.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A molecular sieve adsorption energy-saving system, characterized in that: It includes a preheater connected in sequence, two steam heaters operating in parallel, and a molecular sieve adsorber; The steam heater comprises a regeneration gas inlet, a regeneration gas outlet, a steam inlet and a steam outlet; the preheater comprises a gas side inlet, a gas side outlet, a water side inlet and a water side outlet, the gas side outlet is connected to the regeneration gas inlet of the steam heater, and the regeneration gas outlet of the steam heater is connected to the molecular sieve adsorber; The regenerated contaminated nitrogen gas is first passed into the preheater to be heated by low-temperature hot water, then passed into the steam heater to be heated by steam, and finally passed into the molecular sieve adsorber to be exothermic and analyzed before being discharged; The regenerated dirty nitrogen gas at 24°C exchanges heat with the low-temperature hot water at 95°C in the preheater, is heated to 85°C by the low-temperature hot water, and then passes into the steam heater, is heated to 213°C by the steam at 2.2Mpa and 226°C, and then passes into the molecular sieve adsorber, and the steam is condensed to 120°C and sent to the pipe network as process condensate; After starting the preheater, each steam heater is set to work at 75% of the device load. When the preheater is deactivated, the two steam heaters can meet the 100% load condition requirement. Low-temperature hot water is introduced into the preheater through the water side inlet to heat the regenerated dirty nitrogen gas, and then discharged through the water side outlet; steam is introduced into the steam heater through the steam inlet to heat the regenerated dirty nitrogen gas, and then discharged through the steam outlet, and condensed and sent to the pipe network as process condensate; The gas outlet of the preheater is of bell-mouth design, and a differential pressure transmitter is provided at the gas inlet and outlet. The resistance at the gas outlet is controlled within 150Pa, and the resistance at the heat exchange core inside the preheater is controlled within 100Pa. Isolation valves are provided at the water side inlet and the water side outlet of the preheater; The gas side outlet is also provided with an online water content analyzer; The preheater adopts a floating head structure; the internal heat exchange tube of the preheater adopts a bimetallic rolled fin tube structure; the air inlet side of the preheater is analyzed by CFD simulation, and the water side inlet is also simulated by CFD.

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