Energy-saving concentrated acid preheater for hydrochloric acid desorption
By using a graphite shell-and-tube heat exchanger for heat exchange in the hydrochloric acid desorption process, the problems of high steam consumption and easy damage of the traditional hydrochloric acid preheater are solved, and energy saving and stable operation of the hydrochloric acid desorption device are achieved.
Patent Information
- Application Number
- CN202422653317.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2034-10-31
AI Technical Summary
In the traditional hydrochloric acid desorption process, the hydrochloric acid preheating process requires the use of hot water or steam, resulting in high steam consumption and uneconomical equipment, and the preheater is weak and easily damaged.
A graphite shell-and-tube heat exchanger is used to exchange heat between the high-temperature dilute acid after desorption in the desorption tower and the low-temperature concentrated hydrochloric acid to preheat the concentrated hydrochloric acid, and the dilute acid is cooled by the dilute acid cooler to reduce heat and cooling requirements.
The energy-saving operation of the hydrochloric acid desorption device is achieved, damage to the equipment due to vibration is avoided, operating costs are reduced, and equipment stability is improved.
Smart Images
Figure CN223392910U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of chemical production, and in particular relates to an energy-saving hydrochloric acid desorption concentrated acid preheater. Background Art
[0002] In current organic chemical production processes, especially in the chlor-alkali industry and vinyl chloride monomer (VCM) production, a large amount of hydrochloric acid is produced as a by-product. The hydrochloric acid desorption process can be used to recover high-quality hydrogen chloride gas from it. This gas can be reused in the synthesis of VCM or other chloride products, thereby achieving resource recycling and reducing waste emissions. At the same time, the desorbed hydrogen chloride gas can be further purified to obtain high-purity hydrogen chloride products for use in the semiconductor industry, pharmaceutical intermediate synthesis, fine chemical manufacturing and other fields.
[0003] In the hydrochloric acid desorption process, the concentrated acid preheater is a key equipment. Its function is to heat the concentrated hydrochloric acid before desorption to ensure that the hydrochloric acid reaches the appropriate desorption temperature. The pretreated hydrochloric acid usually needs to be heated to a certain temperature, generally around 60-70℃, to facilitate the subsequent desorption process. Heating can be achieved through a heat exchanger or direct heating equipment.
[0004] Traditional hydrochloric acid desorption processes require the use of hot water or steam to preheat the hydrochloric acid. This presents the following challenges during operation: Firstly, high steam consumption results in the cost of steam preheating exceeding the revenue generated by the hydrochloric acid desorption process, resulting in uneconomical operation of the system.
[0005] On the other hand, the preheaters usually selected have poor strength and rigidity, and steam water hammer and other phenomena may occur during system operation, which can easily cause vibration and damage to the equipment. Utility Model Content
[0006] The purpose of the utility model is to provide an energy-saving hydrochloric acid desorption concentrated acid preheater to solve the problem that in the traditional hydrochloric acid desorption process, hot water or steam is needed to preheat the hydrochloric acid, and the steam consumption is high, resulting in the device being unable to achieve economical operation and being very prone to vibration causing damage to the equipment.
[0007] The technical solution of the utility model is: an energy-saving hydrochloric acid desorption concentrated acid preheater, comprising a concentrated acid tank, the bottom of the concentrated acid tank is connected to a concentrated acid pump, a concentrated acid preheater and a hydrochloric acid desorption tower in sequence through a concentrated hydrochloric acid pipeline, the bottom of the hydrochloric acid desorption tower is connected to a reboiler, the reboiler is provided with a steam pipeline, the bottom of the reboiler is connected to a dilute acid pump, a concentrated acid preheater, a dilute acid cooler and a dilute acid tank in sequence through a dilute hydrochloric acid pipeline; the outlet of the hydrochloric acid desorption tower is connected to a primary hydrogen chloride cooler and a secondary hydrogen chloride cooler in sequence through a hydrogen chloride pipeline, and is discharged from the secondary hydrogen chloride cooler, the bottoms of the primary hydrogen chloride cooler and the secondary hydrogen chloride cooler are commonly connected to a condensed acid pipeline, and the condensed acid pipeline is connected to the dilute acid tank.
[0008] As a further improvement of the present invention, the primary hydrogen chloride cooler and the dilute acid cooler are respectively connected to circulating water pipelines, and the secondary hydrogen chloride cooler is connected to a 5°C water pipeline.
[0009] As a further improvement of the present invention, the inlet temperature of the steam pipe connected to the reboiler is 110°C-125°C.
[0010] As a further improvement of the present invention, the concentrated acid tank is a glass fiber reinforced plastic storage tank.
[0011] As a further improvement of the present invention, the primary hydrogen chloride cooler and the secondary hydrogen chloride cooler are graphite shell-and-tube heat exchangers.
[0012] The beneficial effects of the utility model are as follows: the high-temperature dilute acid separated out from the hydrochloric acid separation tower is utilized to exchange heat with the low-temperature concentrated hydrochloric acid entering the separation tower by setting a graphite shell-and-tube heat exchanger. On the one hand, the preheating of the concentrated hydrochloric acid entering the tower is achieved, ensuring that the preheating temperature of the hydrochloric acid entering the tower is between 60°C and 70°C. At the same time, heat exchange is used to ensure that the high-temperature dilute acid leaving the tower enters the dilute acid cooler for cooling after precooling, thereby saving the heat required for the concentrated acid preheater and the cooling capacity required for the dilute acid cooler, thereby achieving energy-saving and consumption-reducing operation of the hydrochloric acid separation device and effectively eliminating the problems arising from the above-mentioned background. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a schematic diagram of the overall structure of the utility model.
[0014] In the figure: 1-concentrated acid tank; 2-hydrochloric acid desorption tower; 3-concentrated acid preheater; 4-diluted acid cooler; 5-reboiler; 6-hydrogen chloride primary cooler; 7-hydrogen chloride secondary cooler; 8-diluted acid tank; 9-concentrated acid pump; 10-diluted acid pump; a-concentrated hydrochloric acid pipeline; b-diluted hydrochloric acid pipeline; c-hydrogen chloride pipeline; d-condensed acid pipeline; e-circulating water pipeline; f-5℃ water pipeline; z-steam pipeline. DETAILED DESCRIPTION
[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0016] like Figure 1 As shown, an energy-saving hydrochloric acid desorption concentrated acid preheater comprises a concentrated acid tank 1, the bottom of the concentrated acid tank 1 is connected in sequence to a concentrated acid pump 9, a concentrated acid preheater 3 and a hydrochloric acid desorption tower 2 through a concentrated hydrochloric acid pipeline a, the bottom of the hydrochloric acid desorption tower 2 is connected to a reboiler 5, a steam pipeline z is provided on the reboiler 5, and the bottom of the reboiler 5 is connected in sequence to a dilute acid pump 10, a concentrated acid preheater 3, a dilute acid cooler 4 and a dilute acid tank 8 through a dilute hydrochloric acid pipeline b; the outlet of the hydrochloric acid desorption tower 2 is connected in sequence to a primary hydrogen chloride cooler 6 and a secondary hydrogen chloride cooler 7 through a hydrogen chloride pipeline c, and is passed out of the secondary hydrogen chloride cooler 7, the bottoms of the primary hydrogen chloride cooler 6 and the secondary hydrogen chloride cooler 7 are commonly connected to a condensed acid pipeline d, and the condensed acid pipeline d is connected to the dilute acid tank 8.
[0017] The primary hydrogen chloride cooler 6 and the dilute acid cooler 4 are respectively connected to a circulating water pipe e, and the secondary hydrogen chloride cooler 7 is connected to a 5°C water pipe f; the steam pipe z connected to the reboiler 5 has an inlet temperature of 110°C-125°C; the concentrated acid tank 1 is a glass fiber reinforced plastic storage tank; the primary hydrogen chloride cooler 6 and the secondary hydrogen chloride cooler 7 are graphite shell and tube heat exchangers.
[0018] Before operation, all pipes and fittings in the device are pressure tested for leaks at a pressure of 0.5 MPA. The equipment and facility pipelines are made of steel-lined PTFE material, and the flange joints are made of corrosion-resistant gaskets such as EPDM. The acid pipes in the device are equipped with observation mirrors to facilitate inspection and observation during system operation. The hydrochloric acid desorption tower 2 is equipped with an explosion-proof device, which can be exploded in time in the event of a fault to ensure the safe operation of all equipment; start the concentrated acid pump 9 to start adding acid to the hydrochloric acid desorption tower 2. When the liquid level of the hydrochloric acid desorption tower 2 shows 80%, stop the concentrated acid pump 9; open the reboiler 5 The steam valve starts to heat up the hydrochloric acid desorption tower 2. When the temperature of the hydrochloric acid desorption tower 2 displays 110℃-125℃ and the pressure displays 65-70kPa, open the air supply valve on the hydrogen chloride pipeline c to start delivering hydrogen chloride; start the concentrated acid pump 9 to continuously supply acid to the hydrochloric acid desorption tower 2, and start the dilute acid pump 9 to deliver the desorbed dilute acid to the dilute acid tank 8; adjust the balance of the inlet and outlet of the concentrated acid pump 9 and the dilute acid pump 10 to ensure the stability of the liquid level of the hydrochloric acid desorption tower 2; adjust the opening of the steam valve of the steam pipeline z entering the reboiler 5 to ensure the constant temperature and pressure of the hydrochloric acid desorption tower 2.
[0019] The main function of the concentrated acid tank 1 is to store and buffer the concentrated hydrochloric acid before it enters the hydrochloric acid desorption tower 2. A concentrated hydrochloric acid pipeline a is set at the bottom outlet of the concentrated acid tank 1 and connected to the inlet of the concentrated acid pump 9. The outlet of the concentrated acid pump 9 pumps the concentrated hydrochloric acid to the concentrated acid preheater 3 through the concentrated hydrochloric acid pipeline a and then enters the hydrochloric acid desorption tower 2.
[0020] The hydrochloric acid desorption tower 2 is usually made of corrosion-resistant materials such as fiberglass, polytetrafluoroethylene-coated carbon steel or titanium alloy to ensure long-term stable operation in a hydrochloric acid environment. The hydrochloric acid desorption tower 2 includes tower plates: such as float valve tower plates, bubble cap tower plates, sieve plates, etc.; fillers: such as ball rings, Raschig rings, etc., or unique desorption membrane components. The function of the components is to increase the contact area and contact time between hydrochloric acid and the desorption gas, usually air or inert gas, to promote the volatilization of hydrogen chloride from the hydrochloric acid solution and transport it from the top of the tower to the hydrogen chloride cooler under the tower's own pressure.
[0021] A reboiler 5 is connected to the bottom of the hydrochloric acid desorption tower 2. Steam is introduced into the shell side of the reboiler 5 for heating, thereby ensuring that the heat generated at the bottom of the tower is sufficient to bring the hydrogen chloride in the concentrated hydrochloric acid to the decomposition temperature. The introduction temperature is 110°C-125°C. The hydrogen chloride at the outlet of the hydrochloric acid desorption tower 2 is transported through the hydrogen chloride pipeline c, sequentially cooled to 30°C by the primary hydrogen chloride cooler 6, cooled to 10°C by the secondary hydrogen chloride cooler 7, and then transported to the downstream production process.
[0022] The bottom of the reboiler 5 is connected to the dilute acid pump 10 through the dilute hydrochloric acid pipeline b. The outlet of the dilute acid pump 10 passes the hot hydrochloric acid in the tower through the dilute hydrochloric acid pipeline b, passes through the concentrated acid preheater 3 and the dilute acid cooler 4 in sequence, and then enters the dilute acid tank 8. The hydrochloric acid passes through the shell side of the concentrated acid preheater 3 and exchanges heat with the cold hydrochloric acid entering the tower. The shell side of the dilute acid cooler 4 is cooled by circulating water. The hot hydrochloric acid is cooled by the concentrated acid preheater 3 and the dilute acid cooler 4 and then transported to the dilute acid tank 8 for standby use. A condensed acid pipeline d is set at the bottom of the hydrogen chloride primary cooler 6 and the hydrogen chloride secondary cooler 7, and the acid flows to the dilute acid tank 8 by gravity through the high head difference.
Claims
1. An energy-saving hydrochloric acid desorption concentrated acid preheater, characterized by: The invention comprises a concentrated acid tank (1), wherein the bottom of the concentrated acid tank (1) is connected to a concentrated acid pump (9), a concentrated acid preheater (3) and a hydrochloric acid desorption tower (2) in sequence through a concentrated hydrochloric acid pipeline (a), the bottom of the hydrochloric acid desorption tower (2) is connected to a reboiler (5), a steam pipeline (z) is provided on the reboiler (5), and the bottom of the reboiler (5) is connected to a dilute acid pump (10), a concentrated acid preheater (3), a dilute acid cooler (4) and a dilute acid tank (8) in sequence through a dilute hydrochloric acid pipeline (b); the outlet of the hydrochloric acid desorption tower (2) is connected to a primary hydrogen chloride cooler (6) and a secondary hydrogen chloride cooler (7) in sequence through a hydrogen chloride pipeline (c), and is discharged from the secondary hydrogen chloride cooler (7), the bottoms of the primary hydrogen chloride cooler (6) and the secondary hydrogen chloride cooler (7) are commonly connected to a condensed acid pipeline (d), and the condensed acid pipeline (d) is connected to the dilute acid tank (8).
2. The energy-saving hydrochloric acid desorption concentrated acid preheater according to claim 1, characterized in that: The hydrogen chloride primary cooler (6) and the dilute acid cooler (4) are respectively connected to a circulating water pipeline (e), and the hydrogen chloride secondary cooler (7) is connected to a 5°C water pipeline (f).
3. An energy-saving hydrochloric acid desorption concentrated acid preheater according to claim 1 or 2, characterized in that: The steam pipe (z) connected to the reboiler (5) has an inlet temperature of 110°C-125°C.
4. The energy-saving concentrated acid preheater for hydrochloric acid desorption according to claim 3, characterized in that: The concentrated acid tank (1) is a glass fiber reinforced plastic storage tank.
5. The energy-saving concentrated acid preheater for hydrochloric acid separation according to claim 4, characterized in that: The hydrogen chloride primary cooler (6) and the hydrogen chloride secondary cooler (7) are graphite shell-and-tube heat exchangers.