Energy-saving system for ammonia salt in ammonia-soda process mother liquor

Abstract

The utility model relates to an energy-saving system in ammonia-soda process mother liquor, in particular to an energy-saving system for carbon ammonia salt in the ammonia-soda process mother liquor. An upper port of the heat exchanger is a tube pass air inlet, and a heat exchanger tube pass air outlet is formed in the lower portion of the heat exchanger. A cold mother liquor inlet is formed in the shell above the air outlet side of the heat exchanger, and a hot mother liquor outlet is formed in the shell at the upper part of the heat exchanger; the hot mother liquor outlet is connected with the hot mother liquor inlet in the side wall of the evaporation separator, the hot mother liquor outlet of the evaporation separator is located at the lower end of the evaporation separator, and the air outlet of the evaporation separator is located at the upper end of the evaporation separator; a tube pass gas outlet of the heat exchanger is connected with a gas outlet of the evaporation separator through a first pipeline, and the first pipeline is connected with a gas inlet of the condensing tower through a second pipeline. Direct contact of the furnace gas and the cold mother liquor is improved into indirect contact, and most of water vapor in the furnace gas is condensed and recycled; an original high-end inlet of cold mother liquor is changed into a low-end inlet, and the defect that water vapor in furnace gas enters hot mother liquor is overcome.

Description

Technical Field

[0001] The utility model relates to an energy-saving system in ammonia-soda process mother liquor, in particular to an energy-saving system for carbon ammonium salt in ammonia-soda process mother liquor. Background Art

[0002] In the domestic and foreign soda ash industry, with the substantial increase in the production capacity of natural soda with lower costs, enterprises that do not have resource and technical management advantages in the ammonia-soda process and some soda-making enterprises will suffer from survival crises to varying degrees; from the perspective of the urgency of domestic environmental protection and water use, energy conservation and consumption reduction, water conservation and emission reduction are the general trend. At present, the method of direct heat exchange between furnace gas and cold mother liquor (i.e. hot mother liquor method) and indirect heat exchange between distilled gas and cold mother liquor (i.e. cold mother liquor method) in the ammonia-soda process soda ash device has been used for decades, but due to the structural problems of the two processes, the hot mother liquor method has the disadvantages that the water vapor in the furnace gas condenses into the mother liquor and expands, and the degree of carbon-ammonia salt decomposition is insufficient, that is, the degree of waste heat utilization needs to be improved; the cold mother liquor method has the disadvantages that the waste heat enthalpy value of the distilled ammonia gas is low, the degree of waste heat utilization is insufficient, and the degree of carbon-ammonia salt decomposition is even lower. Utility Model Content

[0003] The utility model aims to provide an energy-saving system for carbon ammonium salt in mother liquor of ammonia-soda process by overcoming the shortcomings of the prior art.

[0004] The utility model adopts the following technical solutions:

[0005] An energy-saving system for carbon ammonium salt in mother liquor of an ammonia-soda process comprises a heat exchanger connected to a condensing tower, wherein the upper port of the heat exchanger is a tube-side air inlet, and the tube-side air outlet of the heat exchanger is arranged at the lower part of the heat exchanger; a cold mother liquor inlet is arranged on the upper shell of the air outlet side of the heat exchanger, and a hot mother liquor outlet is arranged on the upper shell of the heat exchanger; the hot mother liquor outlet is connected to the hot mother liquor inlet on the side wall of an evaporative separator, the hot mother liquor outlet of the evaporative separator is located at the lower end of the evaporative separator, and the air outlet of the evaporative separator is located at the upper end of the evaporative separator; the tube-side air outlet of the heat exchanger is connected to the air outlet of the evaporative separator through a first pipeline, and the first pipeline is connected to the air inlet of the condensing tower through a second pipeline.

[0006] The utility model adopting the above technical solution has the following advantages: the combined structure of the heat exchanger and the evaporation separator is adopted to replace the packed tower or the flow-through plate tower structure adopted in the original device, the direct contact between the furnace gas and the cold mother liquid is improved to indirect contact, and most of the water vapor in the furnace gas can be condensed and recovered; the high-end position inlet of the original cold mother liquid is changed to the low-end position inlet, which overcomes the problem that the water vapor in the furnace gas enters the hot mother liquid and the cold mother liquid repeatedly absorbs CO 2 NH 3 The disadvantage of the waste heat is that it further decomposes the carbon ammonia salts in the hot mother liquor and the amount of decomposition increases.

[0007] The preferred embodiment of the present utility model is as follows:

[0008] The heat exchanger is provided with more than two hot mother liquid outlets, and each hot mother liquid outlet is respectively connected to a hot mother liquid inlet on the side wall of an evaporation separator.

[0009] The heat exchanger adopts a bellows structure.

[0010] A gas-liquid separation device and a condensate outlet are arranged at the lower part of the heat exchanger, and a condensate drain port is arranged at the lower side of the condensate outlet.

[0011] The lower port of the heat exchanger is connected to the upper flange of the integral condensation tower through a lower flange, and a partition is added between the upper flange and the lower flange.

[0012] The air outlet of the heat exchanger is connected to the split-type condensing tower through a pipeline.

[0013] The condensate outlet is connected to the condensation tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the prior art.

[0015] Figure 2 It is a schematic diagram of the overall structure of the utility model.

[0016] Figure 3 It is a top view of the heat exchanger and the evaporation separator of the utility model.

[0017] Figure 4 It is a process flow diagram of the utility model connected with a hot alkali liquid tower.

[0018] Figure 5 It is a process flow diagram of the utility model connected with a mother liquor distillation tower. DETAILED DESCRIPTION

[0019] The utility model is described in detail below with reference to the accompanying drawings and embodiments:

[0020] See attached Figures 1 to 4The structure shown in the figure: heat exchanger 1, tube side air inlet 101, tube side air outlet 102, hot mother liquid outlet 1 1301, hot mother liquid outlet 2 1302, cold mother liquid inlet 104, first pipeline 105, second pipeline 106, heat exchanger condensate outlet 108, mother liquid drain outlet 109, condensate drain outlet 110; first evaporation separator 2, first evaporation separator air outlet 201, first hot mother liquid inlet 202, first hot mother liquid outlet 203; second evaporation separator 3, second evaporation separator air outlet 301, second hot mother liquid inlet 302, second hot mother liquid outlet 303; condensation tower 4, packed tower 5.

[0021] In this embodiment, an energy-saving system for carbon ammonium salt in mother liquor of ammonia-soda process includes a heat exchanger 1 connected to the furnace gas outlet of hot alkali liquid tower, and the heat exchanger 1 adopts a bellows structure with high convection heat transfer coefficient.

[0022] The bottom end of the heat exchanger 1 is connected to the condensing tower 4, the upper end of the heat exchanger 1 is the tube-side air inlet 101, and the tube-side air outlet 102 of the heat exchanger 1 is arranged at the lower part of the heat exchanger 1; a cold mother liquid inlet 104 is arranged on the upper shell of the air outlet side of the heat exchanger 1, and a hot mother liquid outlet is arranged on the upper shell of the heat exchanger 1; the hot mother liquid outlet is connected to the hot mother liquid inlet on the side wall of the evaporative separator, and the hot mother liquid outlet of the evaporative separator is located at the lower end of the evaporative separator, and the evaporative separator adopts a vacuum structure; the air outlet of the evaporative separator is located at the upper end of the evaporative separator; the tube-side air outlet 101 of the heat exchanger 1 is connected to the air outlet of the evaporative separator through a first pipeline 105, and the first pipeline 105 is connected to the air inlet of the condensing tower 4 through a second pipeline 106.

[0023] The heat exchanger 1 is provided with two hot mother liquid outlets, namely, hot mother liquid outlet 1 1301 and hot mother liquid outlet 1302. The hot mother liquid outlet 1 1301 is connected to the first hot mother liquid inlet 202 on the side wall of the first evaporation separator 2 through a pipeline. The hot mother liquid outlet 2 1302 is connected to the second hot mother liquid inlet 302 on the side wall of the second evaporation separator 3 through a pipeline.

[0024] A condensate outlet 108 is disposed at the lower portion of the heat exchanger 1 , and a condensate drain port 110 is disposed at the lower side of the condensate outlet 108 .

[0025] The lower port of the heat exchanger 1 is connected to the upper flange of the integral condensation tower 4 through a lower flange, and a partition is added between the upper flange and the lower flange.

[0026] If the condensation tower 4 is a split structure, the heat exchanger outlet 102 of the heat exchanger 1 is connected to the split condensation tower through a pipeline.

[0027] The lower end of the first evaporation separator 2 is provided with a first hot mother liquid outlet 203, and the upper end of the first evaporation separator 2 is the first evaporation separator gas outlet 201. The lower end of the second evaporation separator 3 is provided with a second hot mother liquid outlet 303, and the upper end of the second evaporation separator 3 is the second evaporation separator gas outlet 301.

[0028] The furnace gas from the hot lye tower Figure 5 As shown in (or the low-grade calorific value process gas or waste gas from other equipment such as the distillation tower, see Figure Attachment 6), enters through the tube side air inlet 101 of the bellows heat exchanger 1, and is indirectly heat-exchanged with the cold mother liquid filling the shell side in the heat exchanger 1 in countercurrent flow, and is led out from the tube side air outlet 102 of the heat exchanger, and after merging the gas from the first evaporator separator air outlet 201 and the second evaporator separator air outlet 301, it enters the next stage of cooling equipment, the furnace gas condensation tower 4.

[0029] The cold mother liquid enters from the cold mother liquid inlet 104 of the bellows heat exchanger and becomes hot mother liquid after absorbing heat; the hot mother liquid is discharged from the heat exchanger outlet 102 and enters the hot mother liquid inlet 202 of the first evaporation separator and the hot mother liquid inlet 302 of the second evaporation separator respectively. The gas components are evaporated to a certain extent under vacuum conditions and the gas is quickly separated. The remaining hot mother liquid comes out from the bottom outlet 203 of the first evaporation separator and the outlet 303 of the second evaporation separator, and enters the hot mother liquid barrel according to the original process. The condensate generated by the cooling of the furnace gas in the bellows heat exchanger is discharged from the condensate outlet 108, and is finally sent to the dilute liquid distillation system after being collected (see attached Figure 5 as shown).

[0030] Keep the furnace gas and cold mother liquid in countercurrent heat transfer in the heat exchanger. Improve the original furnace gas and mother liquid inlet and outlet positions, and discharge the gas from the original low-temperature liquid inlet point for direct contact mass transfer and heat transfer (there is a low-temperature mother liquid that repeatedly absorbs CO 2 NH 3 In the case of gas, the high-temperature gas inlet point is changed to a horizontal position for indirect heat exchange, the hot mother liquid is led into the evaporator separator, and the gas analyzed in the liquid is quickly separated.

[0031] The internal flow-through parts are made of TA2 material (or other permitted materials), the external shell is made of Q345R material, the shell-side tubes are made of bellows with large expansion volume, and the heat exchanger body is designed with compensation to ensure the service life of the tube ends and tube sheet expansion welding parts.

[0032] The bellows heat exchanger 1 used in this embodiment, under the conditions of production process and operation, is checked and determined according to the parameters and structure of the heat exchanger based on the cold and hot mother liquid, furnace gas load and related parameters in production. 4 + and CL -The internal flow-through parts are made of TA2 material (or other permitted materials), the external shell is made of Q345R material, the tube side uses a bellows with a large expansion volume, and the heat exchanger body is designed with compensation to ensure the service life of the tube end and the tube sheet expansion welding part.

[0033] The first evaporation separator 2 and the second evaporation separator 3 are made of TA2 material (or other permitted materials).

[0034] Evaporation separator layout description: The layout of the evaporation separator needs to be determined according to the production site conditions. If the original device is a combination of a packing tower and a cooling box, the heat exchanger 1 should be arranged at the original packing tower position, and the evaporation separator should be arranged on one side or both sides thereof. The space factors such as the plant, platform, and pipeline connection must be comprehensively considered to achieve a reasonable layout.

[0035] Use waste heat to heat the mother liquor to decompose NH 4 HCO 3 NH 4 ) 2 CO 3、 NH 4 OH and other components, and separate free ammonia, carbon dioxide and water vapor in the evaporation separator in time, while ensuring that there is no mother liquor. In order to speed up the reaction, it is necessary to maintain a high temperature and vacuum degree and quickly remove the gas. Considering the constraints of on-site factors during the transformation, in order to ensure rapid separation and a large evaporation area, generally one heat exchanger 1 is equipped with more than 2 evaporation separators and connected through pipelines (see attached Figure 2 ). The size and structure of the evaporation separator are determined according to the technical requirements such as the amount and composition of the mother liquor, vacuum degree, gas flow rate, etc. The whole equipment adopts TA 2 Material (or other allowed materials).

[0036] Specific application data in this embodiment:

[0037] (1) It overcomes the drawback that water vapor in the light ash calcining furnace gas of the hot alkali liquid tower enters the hot mother liquor. The waste heat further decomposes the carbon ammonia salt in the hot mother liquor, saving the amount of steam used in the distillation tower of the next process.

[0038] ①Incremental decomposition of carbon-ammonia salt saves steam in distillation tower

[0039] After the device was improved, according to the measured data, the hot mother liquor (NH 4 ) 2 CO 3 Decomposing 10 more Ti can save 0.5MPa steam and 59.48kg / t alkali.

[0040] ② The amount of steam condensed by the furnace gas and the amount of hot mother liquor equivalent are reduced, which reduces the amount of steam consumed

[0041] The difference in water vapor content between the inlet and outlet gases of the mother liquor washing tower is the water content entering the hot mother liquor before the improvement. The gas decomposed by the incremental carbon ammonia salt and the evaporation of the mother liquor reduce the hot mother liquor equivalent. Compared with before and after the improvement, the next distillation process can save 0.5MPa steam and 27.82kg / t alkali.

[0042] The two items add up to 87.30 kg / t alkali, with an economic benefit of approximately RMB 15.71 / t alkali.

[0043] (2) Benefits of saving excess ash from distillation waste liquid and ammonia in waste liquid

[0044] The hot mother liquor equivalent is reduced, saving about 1.365kg / t alkali of active CaO, equivalent to 2.037kg / t alkali of crude lime. The price of crude lime is 320 yuan / ton, and the economic benefit is 0.65 yuan / ton alkali.

[0045] The ammonia content in the waste liquid was reduced by 0.039kg / t alkali, with an economic benefit of 0.12 yuan / ton alkali.

[0046] The additional costs such as equipment depreciation shall not exceed RMB 1.0 / ton of alkali.

[0047] The total economic benefit is 15.48 yuan / ton of alkali.

[0048] In addition, after the transformation, the distillation waste liquid equivalent was reduced by 0.65m 3 / ton of alkali or above, the transportation power and slag storage costs of this link are reduced; the amount of ammonia condensate entering the high vacuum dilute liquid tower is increased, and the waste dilute liquid generated is used in the filtration process instead of desalted water.

[0049] This embodiment overcomes the drawback of water vapor in the furnace gas entering the hot mother liquor. The waste heat further decomposes the carbon ammonia salt in the hot mother liquor and the decomposition amount increases, saving the steam used in the distillation tower of the next process. The equivalent amount of distillation waste liquid is reduced by 0.65m 3 / ton of alkali or above, the transportation power and slag storage costs of this link are reduced; the amount of ammonia condensate increases and enters the high vacuum dilute liquid tower and is distilled with waste steam, and the resulting waste dilute liquid replaces desalted water for the filtration process.

[0050] The expressions of first and second adopted in this embodiment are only for distinguishing the names of technical features, and do not imply that the first comes first and the second comes later.

[0051] The present invention is not limited to the contents described in the above-mentioned embodiments; any structural method that improves the original direct contact between the furnace gas or the cold mother liquid medium to indirect contact, so that most of the water vapor in the furnace gas can be condensed and recovered, is considered to be within the protection scope of the present invention.

Claims

1. An energy-saving system for carbon ammonium salt in mother liquor of ammonia-soda process, comprising a heat exchanger connected to a condensing tower, characterized in that: The upper port of the heat exchanger is a tube-side air inlet, and the tube-side air outlet of the heat exchanger is arranged at the lower part of the heat exchanger; a cold mother liquid inlet is arranged on the upper shell of the air outlet side of the heat exchanger, and a hot mother liquid outlet is arranged on the upper shell of the heat exchanger; the hot mother liquid outlet is connected with the hot mother liquid inlet on the side wall of the evaporative separator, the hot mother liquid outlet of the evaporative separator is located at the lower end of the evaporative separator, and the air outlet of the evaporative separator is located at the upper end of the evaporative separator; the tube-side air outlet of the heat exchanger is connected with the air outlet of the evaporative separator through a first pipeline, and the first pipeline is connected with the air inlet of the condensation tower through a second pipeline.

2. The energy-saving system for carbon ammonium salt in the mother liquor of the ammonia-soda process according to claim 1, characterized in that: The heat exchanger is provided with more than two hot mother liquid outlets, and each hot mother liquid outlet is respectively connected to a hot mother liquid inlet on the side wall of an evaporation separator.

3. The energy-saving system for carbon ammonium salt in the mother liquor of the ammonia-soda process according to claim 1, characterized in that: The heat exchanger adopts a bellows structure.

4. The energy-saving system for carbon ammonium salt in mother liquor of ammonia-soda process according to claim 1, characterized in that: A gas-liquid separation device and a condensate outlet are arranged at the lower part of the heat exchanger, and a condensate drain port is arranged at the lower side of the condensate outlet.

5. The energy-saving system for carbon ammonium salt in the mother liquor of the ammonia-soda process according to claim 1, characterized in that: The lower port of the heat exchanger is connected to the upper flange of the integral condensation tower through a lower flange, and a partition is added between the upper flange and the lower flange.

6. The energy-saving system for carbon ammonium salt in the mother liquor of the ammonia-soda process according to claim 1, characterized in that: The air outlet of the heat exchanger is connected to the split-type condensing tower through a pipeline.

7. The energy-saving system for carbon ammonium salt in the mother liquor of the ammonia-soda process according to claim 4, characterized in that: The condensate outlet is connected to the condensation tower.

8. The energy-saving system for carbon ammonium salt in the mother liquor of the ammonia-soda process according to claim 1, characterized in that: The evaporation separator adopts a vacuum structure.

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