CN203274521U - A cement kiln comprehensive energy saving and emission reduction integrated system - Google Patents

Abstract

The utility model provides a cement kiln synthesizes energy saving and emission reduction integrated system, the other hot boiler both ends link to each other with cement calcination device's flue gas take-out mouth and air heater respectively, and this air heater links to each other with dust collector, air filter device and air mixing device respectively again, and this air mixing device links to each other with oxygen boosting generating device and oxygen boosting combustion nozzle respectively again. One outlet of the economizer of the waste heat boiler is connected with the steam drum, the other outlet is connected with the urea dissolving tank of the SNCR device, and the outlet of the urea dissolving tank of the SNCR device, the upper part of which is provided with a urea inlet, is connected with an SNCR reducing agent spray gun arranged on the kiln tail decomposing furnace through a dilution module. The system makes full use of the waste heat of the cement kiln flue gas, realizes the cascade utilization of the energy of the cement kiln, generates electricity by using the high-temperature heat source, supports combustion by using the low-temperature heat source and assists in denitration, and reduces the emission of nitrogen oxides in the tail gas of the cement kiln while making full use of the waste heat energy.

Description

A cement kiln comprehensive energy saving and emission reduction integrated system

technical field

The utility model relates to an energy-saving and denitration device for a cement kiln. the

Background technique

The total energy consumption of the building materials industry ranks fourth in the country's industrial sectors after electric power, metallurgy, and petrochemicals. Nitrogen oxide emissions from the cement industry account for about 15% of the country's total industrial emissions, making it the third largest emitter of nitrogen oxides after thermal power generation and vehicle exhaust. Currently the most widely used flue gas denitrification technologies are SNCR technology and SCR technology. SCR technology has a high denitrification efficiency, which can reach more than 95%. However, due to the large investment, complex system and high operating cost of this technology, it is not suitable for cement kilns. However, SNCR technology has relatively low investment, low operating cost, simple system, and wide application range. Although its denitrification efficiency is low, it can basically meet the current national emission standards. the

The cement industry produces a large amount of waste heat, most of which have been utilized, but some low-temperature waste heat has not been fully utilized. For example, after the cement kiln bypass exhaust gas passes through the kiln exhaust waste heat boiler, the temperature generally reaches ~200 degrees before it is discharged. How to make full use of this part of the low-temperature waste heat is also a problem that people in the industry have been considering. the

At present, in my country, there is no example of cement kiln system performing oxygen-enriched combustion and flue gas denitrification at the same time, and there is no technology that combines the utilization of cement kiln flue gas waste heat with oxygen-enriched combustion technology and flue gas denitrification technology. Simply combining the oxygen-enriched combustion-supporting technology and flue gas denitrification technology is not only a complex system, but also a lot of equipment, a large building area, and high investment and operating costs. Moreover, the simple combination of two independent systems cannot achieve efficient energy saving and environmental protection effects. For example, in the oxygen-enriched combustion process, in order to further improve the combustion efficiency, it is usually necessary to increase the temperature of the combustion air. In the prior art, electric heating is usually used to heat it, which consumes a large amount of electric energy. Similarly, when using the SNCR flue gas denitrification process, in order to speed up the dissolution of urea particles and prevent the low-temperature crystallization of the urea solution, a steam or electric heating system is installed in the urea dissolution tank, and a certain amount of steam or electricity is consumed for heating, which is bound to Cause waste of high-grade energy. the

Contents of the invention

The purpose of this utility model is to provide a reasonable process system, which can make full use of the heat of the cement kiln waste heat boiler and its exhaust gas, and organically combine the oxygen-enriched combustion technology and the SNCR flue gas denitrification technology, which can not only achieve energy saving, The effect of denitrification, while simplifying the system, reducing the operating cost of the whole system is an integrated system of cement kiln comprehensive energy saving and emission reduction. the

In order to realize above-mentioned purpose of this utility model, the utility model adopts following technical scheme:

The utility model mainly includes: cement calcining device, waste heat boiler, dedusting device, oxygen-enriched generator, oxygen-enriched combustion-supporting nozzle, urea dissolving tank of SNCR (selective non-catalytic reduction reaction) device and reducing agent spray gun of SNCR device. Among them, the flue gas inlet of the waste heat boiler is connected with the flue gas outlet of the cement calcining device, and the flue gas outlet is either the waste heat flue gas outlet of the kiln tail smoke chamber of the cement calcining device, or the multi-stage preheater of the cement calcining device The waste heat flue gas outlet, or the waste heat flue gas outlet of the kiln head grate cooler of the cement calcining device. The flue gas outlet of the waste heat boiler is connected with the flue gas inlet of the air preheater, and the flue gas outlet of the air preheater is connected with the dust removal device inlet. The air inlet of the above-mentioned air preheater is connected with the outside air, preferably through an air filter device. The air outlet of the air preheater is connected to one inlet of the air mixing device, the other inlet of the air mixing device is connected to the oxygen-enriched generator, and the outlet of the air mixing device is connected to the oxygen-enriched combustion-supporting nozzle, and the oxygen-enriched combustion-supporting nozzle is n (1≤n≤20) are respectively located at the kiln head or kiln tail, and can be fed into the cement kiln with primary air, secondary air, and tertiary air or injected separately near the burner. The inlet of the waste heat boiler economizer is connected to the water supply platform, one outlet of the waste heat boiler economizer is connected to the steam drum, and the other is connected to the urea dissolving tank of the SNCR device, which can be used as a urea solvent and connected to the inlet of the urea dissolving tank. It is connected as a heat source with the heat medium inlet of the heat exchange coil installed in the urea dissolving tank, or as a urea solvent connected with the inlet of the urea dissolving tank, and as a heat source with the heat medium of the heat exchange coil installed in the urea dissolving tank The entrance is connected. The urea solution outlet of the urea dissolving tank of the SNCR device with urea inlet on the upper part is connected to the inlet of the dilution module, and the outlet of the dilution module is connected to the reducing agent spray gun of the SNCR device installed on the kiln tail calciner. The reducing agent spray gun has n( 1≤n≤20), which can be evenly arranged along the circumferential direction of the calciner, and can also be arranged in layers on the calciner. The waste heat boiler is either a cement kiln tail bypass exhaust heat waste heat boiler, or a cement kiln kiln head waste heat boiler, or a cement kiln tail heat waste heat boiler; The device may be a pressure swing adsorption oxygen enrichment generator, or a cryogenic oxygen enrichment generator.

The working process of the system is as follows: the high-temperature flue gas from the cement calcination device passes through the heat exchange surface of the waste heat boiler for heat exchange and cooling, and then is drawn out from the exit of the waste heat boiler, enters the air preheater for heat exchange, and the flue gas after heat exchange is sent to To the dust collector to reduce dust. After the cold air is filtered by the air filter, it is sent to the air preheater, and after heat exchange with the flue gas, the temperature rises to the design value; the heated air is mixed with the oxygen-enriched oxygen generated by the oxygen-enriched generator in the air mixing device After reaching the required temperature and concentration, it is sent to the oxygen-enriched combustion-supporting nozzle. The water supply device of the waste heat boiler sends deoxygenated water to the economizer inlet of the waste heat boiler. After being heated by the heating surface of the economizer, the deoxygenated water is divided into two paths; one of which is sent to the steam drum of the waste heat boiler, and the other is sent to the SNCR system The urea dissolution storage tank is used for heating and dissolving urea. The urea solution that dissolves and reaches the specified concentration is first sent to the dilution module, diluted to the design concentration, and finally sent to the reducing agent of the SNCR device installed in the kiln tail calciner. Spray gun, used for flue gas denitrification. the

Compared with the prior art, the utility model has the following advantages:

1. Use the waste heat of the flue gas discharged from the waste heat boiler of the cement kiln to preheat the combustion air, which can further improve the efficiency of oxygen-enriched combustion and reduce coal consumption. By calculating the cement plant, it can comprehensively save about 2~15% of coal, thereby saving costs .

2. Since the waste heat of the flue gas discharged from the waste heat boiler of the cement kiln is used to preheat the combustion air, it replaces the conventional technology that usually uses electric heating to preheat the combustion air, avoiding power loss and saving operating costs. Taking a 2500t/d cement production line as an example, the combustion air at the kiln head is 90,000 Nm ³ /h, and the combustion air at the kiln tail is 135,000 Nm ³ /h. If electric heating is used, the combustion air is heated from 25°C to about 100°C. The electric energy consumed per day is 1946.6 kWh. Based on 300 working days per year, the power consumed by heating the combustion air is 583983 kWh. If the electricity is calculated at 0.6 yuan per kWh, the cost can be saved by 350,000 yuan per year.

3. This technology uses 104°C hot water from an economizer to dissolve urea, replacing the use of steam in the prior art to heat and dissolve urea, avoiding the loss of high-quality energy. Also taking the 2500 t/d cement production line as an example, the SNCR system is used for denitrification, and the daily steam volume is 300t. After using the hot water from the economizer, this part of steam can be saved for power generation. the

4. The system is more compact, reasonable and easy to maintain. the

Description of drawings

Fig. 1 is the schematic flow chart diagram of the utility model example 1.

Fig. 2 is a schematic diagram of the layout of the reducing agent spray gun of the SNCR device of the present invention. the

Figure 3 is a schematic diagram of the process of Example 2 of the present invention. the

Fig. 4 is a schematic flow diagram of Example 3 of the present invention. the

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail:

In Figure 1, a schematic flow diagram of a cement kiln integrated energy-saving and emission-reduction integrated system,

It includes a cement calcining device 1, a bypass waste heat boiler 2, a dust removal device 3, a pressure swing adsorption method oxygen-enriched generator 4, an oxygen-enriched combustion-supporting nozzle 5 and a urea dissolving tank 6 of an SNCR device. The waste heat flue gas outlet of the kiln tail smoke chamber 7 of the cement calcination device is connected with the flue gas inlet of the bypass ventilation waste heat boiler, and the flue gas outlet of the bypass ventilation waste heat boiler is connected with the flue gas inlet of the air preheater 8, and the air is preheated The flue gas outlet of the device is connected with the inlet of the dust removal device; the air inlet of the air preheater is connected with the air filter device 9, and the air filter device is provided with an inlet connected with the outside air. The air outlet of the air preheater is connected with an inlet of the air mixing device 10, the other inlet of the air mixing device is connected with the pressure swing adsorption method oxygen-enriched generating device, and the outlet of the air mixing device is connected with the oxygen-enriched combustion-supporting nozzle; There are two oxygen-enriched combustion-supporting nozzles, which are respectively arranged at the kiln head and the kiln tail of the cement kiln. The inlet of the economizer 11 of the bypass exhaust waste heat boiler is connected to the water supply platform, one outlet of the bypass exhaust waste heat boiler economizer is connected to the steam drum 12, and the other is respectively connected to the solvent inlet and the exchange tank of the urea dissolution tank of the SNCR device. The heating coil 13 is connected to the heat medium inlet, and the urea solution outlet of the urea dissolving tank of the SNCR device with urea inlet is connected to the inlet of the dilution module 14. The reductant spray guns 16 of the six SNCR devices on 15 are connected. The layout of the reducing agent spray gun of the SNCR device in the calciner is shown in Figure 2.

The working process of the system is as follows: the 800-1100°C high-temperature flue gas discharged from the kiln tail smoke chamber of the cement kiln calcining system passes through the heat exchange surface of the waste heat boiler for ventilation through the bypass, and after the temperature drops to 180-240°C, the waste heat is released from the bypass The outlet of the boiler is drawn into the air preheater for heat exchange, and the flue gas after heat exchange is sent to the dust collector for dust reduction and emission. After the cold air at 25°C is filtered by the air filter device, it is sent to the air preheater, and after exchanging heat with the flue gas, the temperature rises to about 100°C; After the oxygen-enriched air is mixed into 26-28% oxygen-enriched air in the air mixing device, it is sent to the oxygen-enriched combustion-supporting nozzle. The water supply device of the bypass ventilation waste heat boiler sends deoxygenated water to the economizer inlet of the bypass ventilation waste heat boiler. After the deoxygenated water is heated by the heating surface of the economizer, it is divided into two paths: one of which is sent to the waste heat boiler steam drum, The other is connected with the solvent inlet of the urea dissolving tank of the SNCR system and the heat medium inlet of the heat exchange coil in the urea dissolving tank of the SNCR system, and is used for heating and dissolving urea. After the solution concentration reaches 50%, it is sent to the SNCR dilution module for dilution. After reaching 5%-10%, the urea solution is finally sent to the reducing agent spray gun of the SNCR device for denitrification of flue gas. the

As shown in Figure 3, a schematic flow diagram of a cement kiln comprehensive energy-saving and emission-reduction integrated system includes a cement calcining device, a kiln tail waste heat boiler 17, a dust removal device, a membrane method oxygen-enriched generator 18, an oxygen-enriched combustion-supporting Nozzles and urea dissolution tanks for SNCR units. The waste heat flue gas outlet of the five-stage preheater 19 of the cement calcining device is connected to the flue gas inlet of the waste heat boiler at the kiln tail, the flue gas outlet of the kiln tail waste heat boiler is connected to the flue gas inlet of the air preheater, and the flue gas inlet of the air preheater The air outlet is connected with the dust removal device; the air inlet of the above-mentioned air preheater is connected with the air filter device, and the air filter device is provided with an inlet connected with the outside air. The air outlet of the air preheater is connected to one inlet of the air mixing device, the other inlet of the air mixing device is connected to the membrane method oxygen-enriched generator, and the outlet of the air mixing device is connected to the oxygen-enriched combustion-supporting nozzle; the oxygen-enriched combustion-supporting nozzle is Two, they are respectively arranged at the kiln head and the kiln tail of the cement kiln. The inlet of the waste heat boiler economizer 20 at the kiln tail is connected to the water supply platform, one outlet of the waste heat boiler economizer at the kiln tail is connected to the steam drum, and the other is connected to the heat medium inlet of the heat exchange coil in the urea dissolution tank of the SNCR device , the urea solution outlet of the urea dissolving tank of the SNCR device with urea and softened water inlets on the upper part is connected to the inlet of the SNCR dilution module, and the outlet of the dilution module with softened water inlets is connected to the six SNCRs on the kiln tail decomposition furnace The reducing agent spray gun of the device is connected. the

The working process of the system is as follows: the 300-400°C flue gas at the outlet of the five-stage preheater at the kiln tail of the cement kiln calcining system passes through the heat exchange surface of the waste heat boiler at the kiln tail, and after the temperature drops to 160-220°C, the waste heat from the kiln tail The outlet of the boiler is drawn into the air preheater for heat exchange, and the flue gas after heat exchange is sent to the dust collector for dust reduction. The cold air at 25°C is filtered by the air filter device and then sent to the air preheater. After exchanging heat with the flue gas, the temperature rises to about 100°C; After being mixed into 26-28% oxygen-enriched air in the air mixing device, it is sent to the oxygen-enriched combustion nozzle. The water supply device of the waste heat boiler at the kiln tail sends deoxygenated water to the inlet of the economizer of the waste heat boiler at the kiln tail. The heat medium inlet of the heat exchange coil sent to the urea dissolution storage tank of the SNCR system is used for heating and dissolving urea. After the solution concentration reaches 50%, it is sent to the SNCR dilution module, and the urea solution diluted to 5%-10% Finally, it is sent to the reducing agent spray gun of the SNCR device for denitrification of flue gas. the

As shown in Figure 4, a schematic flow diagram of a cement kiln comprehensive energy-saving and emission-reduction integrated system includes a cement calcining device, a kiln head waste heat boiler 21, a dust removal device, a cryogenic oxygen-enriched generator 22, an oxygen-enriched Combustion nozzles and urea dissolution tanks for SNCR systems. The hot flue gas outlet of the grate cooler 23 at the kiln head of the cement calcination device is connected to the flue gas inlet of the kiln head waste heat boiler, the outlet of the kiln head waste heat boiler is connected to the flue gas inlet of the air preheater, and the flue gas outlet of the air preheater It is connected with the dust removal device; the air inlet of the air preheater is connected with the air filter device, and the air filter device is provided with an inlet connected with the outside air. The air outlet of the air preheater is connected to one inlet of the air mixing device, the other inlet of the air mixing device is connected to the cryogenic oxygen-enriched generator, and the outlet of the air mixing device is connected to the oxygen-enriched combustion-supporting nozzle, and the oxygen-enriched combustion-supporting nozzle There are two, respectively located at the kiln head or kiln tail. The inlet of waste heat boiler economizer 24 at the kiln head is connected to the water supply platform, one outlet of the waste heat boiler economizer at the kiln head is connected to the steam drum, and the other is connected to the solvent inlet of the urea dissolving tank of the SNCR system and the urea dissolving tank of the SNCR device The heat medium inlet of the heat exchange coil in the upper part is connected to the urea solution outlet of the urea dissolving tank of the SNCR device with urea inlet connected to the inlet of the SNCR dilution module, and the outlet of the dilution module is connected to the 6 The reducing agent spray gun of the SNCR device is connected. the

The working process of the system is as follows: the 300-400°C flue gas from the air inlet of the grate cooler at the kiln head of the cement kiln calcining system passes through the heat exchange surface of the kiln head waste heat boiler for heat exchange, and after the temperature drops to 140-160°C, it is discharged from the kiln head waste heat boiler The outlet is drawn out and enters the air preheater for heat exchange, and the flue gas after heat exchange is sent to the dust collector for dust reduction. After the cold air at 25°C is filtered by the air filter device, it is sent to the air preheater, and after exchanging heat with the flue gas, the temperature rises to about 80-100°C; The oxygen-enriched air is mixed into 26-28% oxygen-enriched air in the air mixing device, and then sent to the oxygen-enriched combustion nozzle. The water supply device of the waste heat boiler at the kiln head sends deoxygenated water to the inlet of the economizer of the waste heat boiler at the kiln head. It is connected with the solvent inlet of the urea dissolving tank of the SNCR system and the heat medium inlet of the heat exchange coil in the urea dissolving tank of the SNCR system, and is used for heating and dissolving urea. After the solution concentration reaches 50%, it is sent to the SNCR dilution module and diluted to The 5%-10% urea solution is finally sent to the reducing agent spray gun of the SNCR device for denitrification of flue gas. the

Claims (8)

1. An integrated system for comprehensive energy saving and emission reduction of cement kiln, characterized in that: the flue gas inlet of the waste heat boiler is connected with the flue gas outlet of the cement calcining device, and the flue gas outlet of the above waste heat boiler is connected with the flue gas of the air preheater The inlet is connected, the flue gas outlet of the air preheater is connected with the inlet of the dust removal device, the air inlet of the air preheater is connected with the outside air, the air outlet of the air preheater is connected with an inlet of the air mixing device, and the air mixing device The other inlet of the device is connected with the oxygen-enriched generating device, and the outlet of the air mixing device is connected with the oxygen-enriched combustion-supporting nozzle, and the oxygen-enriched combustion-supporting nozzles are respectively set at the kiln head or the kiln tail, and the inlet of the waste heat boiler economizer is connected with the Connected to the water supply platform, one outlet of the waste heat boiler economizer is connected to the steam drum, and the other is connected to the urea dissolving tank of the SNCR device, and the urea solution outlet of the SNCR device's urea dissolving tank with urea inlet is connected to the dilution module on the upper part The inlet is connected, and the outlet of the dilution module is connected with the reducing agent spray gun of the SNCR device installed on the kiln tail calciner. 2. The cement kiln comprehensive energy saving and emission reduction integrated system according to claim 1, characterized in that: the flue gas outlet of the cement calcining device or the waste heat flue gas outlet of the kiln tail smoke chamber of the cement calcining device, or the cement calcining Install the waste heat flue gas outlet of the multi-stage preheater, or the waste heat flue gas outlet of the kiln head grate cooler of the cement calcining device. 3. The cement kiln comprehensive energy-saving and emission-reduction integrated system according to claim 1, characterized in that: the other outlet of the economizer of the waste heat boiler is either connected to the inlet of the urea dissolving tank, or connected to the inlet of the urea dissolving tank The heat medium inlet of the heat exchange coil inside is connected, or is connected with the inlet of the urea dissolving tank, and is connected with the heat medium inlet of the heat exchange coil arranged in the urea dissolving tank. 4. The cement kiln comprehensive energy saving and emission reduction integrated system according to claim 1, characterized in that: the air inlet of the air preheater is connected to the outside air through an air filter device. 5. The cement kiln comprehensive energy saving and emission reduction integrated system according to claim 1, characterized in that: the waste heat boiler is either a kiln head waste heat boiler, or a kiln tail waste heat boiler, or a kiln tail bypass exhaust heat waste heat boiler . 6. The cement kiln comprehensive energy-saving and emission-reduction integrated system according to claim 1, characterized in that: the oxygen-enriched generator is either a membrane oxygen-enriched generator or a pressure swing adsorption oxygen-enriched generator, Or a cryogenic oxygen enrichment generating device. 7. The cement kiln comprehensive energy-saving and emission-reduction integrated system according to claim 1, characterized in that: there are n oxygen-enriched combustion-supporting nozzles, where 1≤n≤20. 8. The cement kiln comprehensive energy saving and emission reduction integrated system according to claim 1, characterized in that: there are n reducing agent spray guns in the SNCR device, where 1≤n≤20.

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