Device for reducing damp and hot waste gas emission of dryer and improving drying effect

Abstract

The utility model relates to a device for reducing damp and hot waste gas emission of a dryer and improving a drying effect, which is widely applied to a continuous drying technology of water-containing materials in industrial production. A damp and hot waste gas circulating pipeline made of a DN100 material 316, a damp and hot waste gas circulating flow regulating valve, a fin type low-temperature condenser, a waste gas circulating thermocouple and an Annubar waste gas circulating flowmeter are connected to the damp and hot waste gas pipeline; the top end of the humid and hot waste gas pipeline is transversely connected with a humid and hot waste gas pipeline, one end of the humid and hot waste gas pipeline is connected with a humid and hot waste gas induced draft fan, and the other end of the humid and hot waste gas pipeline is connected with a tail gas washing tower; the upper surface of the fin type low-temperature condenser is connected with a cold water pipeline which is made of a DN80 material and is 304, and the lower surface of the cold water pipeline is connected with a circulating temperature regulating valve; the bottom end of the damp and hot waste gas pipeline is transversely connected with a fresh air pipeline; an air filter, a fresh air flow control valve, a dry air blower and a dry air heater are sequentially mounted on the fresh air pipeline; and the dry air heater is connected with the dryer through a pipeline.

Description

TECHNICAL FIELD

[0001] The utility model relates to the continuous drying technology widely applicable to the water-containing material in industrial production, especially a device for reducing the wet hot exhaust emission of dryer and improving drying effect. BACKGROUND

[0002] The dryer is an equipment widely used by heating the material through the hot air flow to take away the moisture in the wet material to obtain the dried product, and the industrial dryer (such as spray dryer, fluidized bed dryer, etc.) is widely applied in the fields of chemical industry, food, pharmaceutical, etc., but the traditional system has the following problems:

[0003] 1. High energy consumption and exhaust emission: a large amount of high-temperature and high-humidity exhaust gas (usually containing moisture content > 30%) is generated during the drying process, which directly causes energy waste and environmental pollution (CO2 emission increase); 2. Low thermal efficiency: 30-50% of the sensible heat and latent heat in the exhaust gas is not recovered (see CN201510230456.X); 3. Non-uniform drying: single-stage drying easily leads to material surface crust, and internal moisture is difficult to diffuse (as described in CN201810567891.2).

[0004] Existing solutions and defects: CN201510230456.X: proposes partial recycling of exhaust gas, but does not solve the problem of drying efficiency reduction caused by high humidity of circulating exhaust gas; US20170321958A1: multi-stage drying design improves the effect, but the system is complex and the maintenance cost rises.

[0005] Technical pain points: the existing technology is difficult to balance the contradiction between exhaust emission reduction, energy consumption reduction and drying quality.

[0006] In the melamine project, some wet materials contain ammonia and other pollution media, which need to be washed and treated. Due to the problems of increased moisture of wet material, increased air humidity, high cooling water temperature in summer, etc., the tail gas washing tower load is often high, the absorption effect is poor, the ammonia content of the vent gas is over-standard, the drying effect is reduced, etc. At present, the ways such as increasing the temperature and flow of hot air, increasing the absorption water amount of tail gas washing tower, etc. are often used to relieve the treatment. This treatment not only further increases the gas phase and liquid phase load of the tail gas washing tower, but also cannot effectively improve the working condition of the tail gas washing tower, at the same time, the treatment amount of waste water after absorbing the exhaust gas is also greatly increased, causing the product energy consumption to rise. SUMMARY

[0007] The device for reducing the wet hot exhaust emission of dryer and improving drying effect is provided, which realizes the reduction of the wet hot exhaust emission of dryer under the premise of ensuring the drying effect, reduces the gas phase load of the tail gas washing tower, and also improves the drying effect.

[0008] The utility model discloses a purpose is realized like this, increase a low temperature condenser at the outlet of the hot waste gas, and part of hot waste gas is cooled and separates part moisture and then circulates uses. The specific structure is, the hot waste gas circulation pipeline of DN100 material for 316 is connected on the hot waste gas pipeline, and the hot waste gas circulation flow regulating valve, the finned low temperature condenser, the waste gas circulation thermocouple, the annaba waste gas circulation flowmeter of hot waste gas are connected on the hot waste gas pipeline, the top of the hot waste gas pipeline is transversely connected with the hot waste gas pipeline, and one end of its hot waste gas pipeline is connected with the hot waste gas induced draft fan, and the other end of the hot waste gas pipeline is connected with the tail gas washing tower, the finned low temperature condenser is connected with the cold water pipeline of DN80 material for 304 on the top, and the lower portion of its cold water pipeline is connected with the circulation temperature regulating valve, the bottom of the hot waste gas pipeline is transversely connected with the fresh air pipeline, and the air filter, the fresh air flow control valve, the dry air blower, the dry air heater are sequentially installed on its fresh air pipeline, and the dry air heater is connected with the dryer through the pipeline. BRIEF DESCRIPTION OF DRAWINGS

[0009] Fig. 1 is a kind of device schematic diagram for reducing the hot waste gas emission of dryer and improving drying effect, in the drawing 1, hot waste gas circulation flow regulating valve 2, hot waste gas circulation pipeline 3, cold water pipeline 4, low temperature condenser 5, circulation temperature regulating valve 6, waste gas circulation thermocouple 7, waste gas circulation flowmeter 8, fresh air flow control valve 9, air filter 10, dry air blower 11, dry air heater 12, hot waste gas induced draft fan. DETAILED DESCRIPTION

[0010] Example 1, the hot waste gas circulation pipeline 2 of DN100 material for 316 is connected on the hot waste gas pipeline, and the hot waste gas circulation flow regulating valve 1, the finned low temperature condenser 4, the waste gas circulation thermocouple 6, the annaba waste gas circulation flowmeter 7 of hot waste gas are connected on the hot waste gas pipeline, the top of the hot waste gas pipeline is transversely connected with the hot waste gas pipeline, and one end of its hot waste gas pipeline is connected with the hot waste gas induced draft fan 12, and the other end of the hot waste gas pipeline is connected with the tail gas washing tower, the upper surface of the finned low temperature condenser 4 is connected with the cold water pipeline 3 of DN80 material for 304, and the lower portion of its cold water pipeline 3 is connected with the circulation temperature regulating valve 5, the bottom of the hot waste gas pipeline is transversely connected with the fresh air pipeline, and the air filter 9, the fresh air flow control valve 8, the dry air blower 10, the dry air heater 11 are sequentially installed on its fresh air pipeline, and the dry air heater 11 is connected with the dryer through the pipeline.

[0011] The application method of the utility model is, fresh air filtered through the air filter 9 is pressurized by the dry air blower 10 and passes through the dry air heater 11, is sent into the dryer after being heated by steam, and the moisture and ammonia in the wet material are heated and taken away, and the tail gas is sent to the tail gas washing tower through the wet waste gas induced draft fan 12.

[0012] According to the situation that the humidity of fresh air is large, the water content of wet material rises, and the flow control of the ammonia-containing wet waste gas is large in hot and humid weather in summer, a wet waste gas circulating pipeline 2 made of DN100 material 316, a wet waste gas circulating flow regulating valve 1, a finned low-temperature condenser 4, a waste gas circulating thermocouple 6 and an Albaba waste gas circulating flowmeter 7 are additionally arranged on the wet waste gas pipeline.

[0013] A cold water pipeline 3 made of DN80 material 304 is additionally arranged on the low-temperature condenser 4, a temperature regulating valve 5 is arranged on the cold water pipeline 3 made of DN80 material 304, and a fresh air flow butterfly control valve 8 is additionally arranged on the fresh air pipeline. The flow of the cold water is regulated by the temperature regulating valve 5 to control the circulating temperature of the waste gas, and the fresh air flow is reduced by regulating the fresh air flow butterfly control valve 8 to keep the total flow of the dry air unchanged.

[0014] In the wet waste gas circulating operation, first, the circulating temperature regulating valve 5 is fully opened, then the wet waste gas circulating flow regulating valve 1 is slowly opened, the waste gas circulating flowmeter 7 is observed, the opening of the waste gas circulating flowmeter 7 is gradually adjusted to 40%-60%, the flow of the wet waste gas is controlled at the design flow of 800-1000 kg / h, then the opening of the fresh air flow control valve 8 is adjusted, the amount of the reduced fresh air is consistent with the flow of the waste gas, the total amount of the dry air is kept unchanged at 2700 kg / h, and then the circulating temperature regulating valve 5 is gradually adjusted, so that the waste gas circulating thermocouple 6 indicates the design temperature of 20℃, the partial circulation of the wet waste gas can be realized to reduce the emission, the absolute humidity of the hot air is reduced from 0.025 kg / kg dry air to 0.021 kg / kg dry air, the drying steam of the dryer is reduced from 800 kg / h to 670 kg / h, the steam consumption is reduced, at the same time, the temperature of the dryer is increased from the original 95℃ to and stabilized at above 110℃, and the drying effect is improved.

[0015] Through actual application, the method is applied in a 30000 tons / year high-pressure melamine project, when the drying load increases or the effect decreases due to hot and humid weather in summer or the humidity of the material changes, the amount of the dry air needs to be increased, and when the tail gas washing tower has the risk of emission exceeding the standard due to high load, the operation method can be used, the method can avoid environmental accidents caused by too large emission of the wet waste gas and product quality accidents caused by poor drying effect, and can be widely applied and popularized in fine chemical enterprises involving the circulating drying of wet waste materials containing pollution media.

[0016] The utility model discloses the beneficial effect is: (1) guarantee the premise of the total amount of dry air unchanged, reduce the hot waste gas emission 800kg / h, reduce the tail gas washing tower load 30%, avoid the ammonia content of emptying over 150ppm and cause environmental protection emission to exceed the standard, (2) guarantee the air relative humidity to reach 90% and above and the wet material water content to exceed 10% and above in the hot weather of summer, and the dryer temperature maintains 110 DEG C and above, (3) adopt the finned condenser, and the heat exchange efficiency is high, and the equipment occupies the area 2-3m 2 , and the investment is little, and the operation is simple.

Claims

1. A device for reducing the emission of dryer wet heat exhaust and improving drying effect, characterized in that: The wet hot exhaust gas pipeline is connected with a wet hot exhaust gas circulating pipeline (2) made of DN100 material 316, a wet hot exhaust gas circulating flow regulating valve (1), a finned low temperature condenser (4), a waste gas circulating thermocouple (6), and an Albaba waste gas circulating flowmeter (7); the top end of the wet hot exhaust gas pipeline is transversely connected with a wet hot exhaust gas pipeline, one end of which is connected with a wet hot exhaust gas induced draft fan (12), and the other end of which is connected with a tail gas washing tower. ​ 2. A device for reducing the emission of dryer wet exhaust and improving drying effect according to claim 1, characterized in that: The upper surface of the finned low temperature condenser (4) is connected with a cold water pipeline (3) made of DN80 material 304, the lower surface of which is connected with a circulating temperature regulating valve (5).

3. The device for reducing the emission of dryer wet exhaust and improving drying effect according to claim 1, characterized in that: The bottom end of the wet hot exhaust gas pipeline is transversely connected with a fresh air pipeline, on which an air filter (9), a fresh air flow control valve (8), a dry air blower (10), and a dry air heater (11) are sequentially installed; the dry air heater (11) is connected with a dryer through a pipeline.

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