CN103836899B - Waste heat utilization technology of cluster intermittent refractory brick drying kiln - Google Patents

Abstract

The present invention relates to a kind of cluster batch (-type) refractory brick dry kiln UTILIZATION OF VESIDUAL HEAT IN technique, comprise the processing steps such as high-temperature residual heat utilization, electrical heating, low temperature heat, pressure cooling, next circulation, adopt the physical sensible heat that heat recovery technology recovery kiln body and refractory brick discharge at temperature descending section, be used for carrying out preheating to the cold kiln and brindles base that just enter intensification section, then the flue gas hot water will discharged after preheating, reaches the object made full use of waste heat.

Description

Waste heat utilization technology of cluster intermittent refractory brick drying kiln

technical field

The invention relates to a cluster intermittent refractory brick drying kiln waste heat utilization process.

Background technique

At present, refractory materials such as magnesia-carbon bricks and lightweight bricks used in the iron and steel industry are generally formed by pressing the ingredients and then drying them at a low temperature of about 220 °C. The drying process is divided into three processes: heating, heat preservation and cooling. Drying is heated by electric heating, which consumes a lot of electric energy. Each kiln of the existing drying kiln operates independently and periodically, which is an intermittent heating equipment. After the drying cycle is over, the furnace door is opened to naturally dissipate heat and cool down to the temperature of the kiln (as shown in Figure 1). According to the preliminary statistics of China Refractories Association, electric drying is still the current mainstream drying process.

The problems existing in the drying process are as follows:

1) A large amount of physical sensible heat is wasted, the waste heat is not fully utilized, and the thermal efficiency is low;

2) The natural cooling speed is slow, the production efficiency is low, and the equipment utilization rate is not high;

3) High temperature in summer, hot flue gas is discharged into the workshop in an unorganized state, causing high temperature effect in the workshop and deteriorating working conditions of workers;

4) Exhaust gas is unorganizedly discharged to the workshop, polluting the air in the workshop and affecting the health of workers.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings, and to provide a method of recovering the physical sensible heat discharged by the kiln body and refractory bricks in the cooling section by waste heat recovery technology, which is used to preheat the cold kiln and cold bricks that have just entered the heating section, and then A cluster intermittent refractory brick drying kiln waste heat utilization process for heating hot water with flue gas discharged after preheating.

In order to achieve the above technical purpose, the solution provided by the present invention is: a cluster intermittent refractory brick drying kiln waste heat utilization process, including the following steps.

Step 1: Utilization of high-temperature waste heat. After the operation of kiln A reaches the cooling period, the high-temperature gas in kiln A is sent to kiln B in the heating period through the circulation pipeline with a circulating fan for heat exchange until kiln A and kiln B Basically no temperature difference.

Step 2, electric heating, close the circulation pipeline between A kiln and B kiln, and conduct electric heating on B kiln to the rated process requirements, and complete the heating and heat preservation process of B kiln.

Step 3, low-temperature waste heat utilization, a small amount of normal temperature air is introduced into A kiln to adjust the waste temperature in A kiln, and then the waste heat gas in A kiln is guided through the waste heat pipe with a smoke exhauster to be heated by the air/water heat exchanger. Exchange, and finally discharge the exhaust gas.

Step 4: Forced cooling. When the temperature of kiln A is too low, close the waste heat pipe, let the normal-temperature air into the kiln A and discharge it from the low-temperature pipe until the kiln A reaches the temperature required by the kiln exit process, and complete the cooling process.

Step 5, the next cycle, after the operation of the B kiln is completed, the above-mentioned waste heat utilization process of the A kiln is circulated to the next working kiln, and the cycle is like this.

Moreover, the temperature of the high-temperature gas is 220°C, the temperature with almost no temperature difference between A kiln and B kiln is 110°C, and the temperature at which the residual temperature gas in A kiln exchanges heat with the gas/water heat exchanger is about 80-110°C , A kiln temperature is too low when the temperature is below 80 ℃.

The present invention also provides a cluster intermittent refractory brick drying kiln using the waste heat utilization process of the cluster intermittent refractory brick drying kiln, including a kiln group consisting of several kilns, each kiln in the kiln group has an electric Heating equipment, each kiln is connected through circulation pipes, waste heat pipes, and low-temperature pipes, valves are installed at the points where the circulation pipes, waste heat pipes, and low-temperature pipes are connected to each kiln, circulation fans are installed in the circulation pipes, and waste heat pipes pass through the gas/ After the water heat exchanger, it is connected with the chimney with exhaust fan, and the low temperature pipe is connected with the chimney with smoke exhaust machine.

Moreover, the circulation pipeline communicates with the kiln head and kiln tail of each kiln through an electronically controlled three-way valve, and the waste heat pipe and low temperature pipe communicate with each kiln through a two-way valve.

The beneficial effects of the present invention are:

1. According to theoretical calculations, the physical heat absorption of bricks is equivalent to power consumption of 38.14kW·h/ton of bricks, and the waste heat is calculated according to the theoretical utilization rate of 50%, saving 19kW·h of electricity per ton of bricks, and the electricity bill of the existing drying kiln The measured value of power consumption is 54.67 kW·h/per ton of bricks, and the energy saving rate=19/54.67=34.75% (Note: This data does not take into account the positive leakage generated in the waste heat recovery process: the usable hot water generated by waste heat; waste heat is also not considered Negative leakage generated during the recovery process: such as increased fan power consumption, correspondence between heating up period and cooling period between kilns, etc., positive and negative leakage have hedging properties and have limited impact on energy saving rate);

According to the data provided by the China Refractory Materials Association, the annual output of this refractory brick in the country is more than 8 million tons, which can save 152 million kW h of electricity, equivalent to 53,200 tons of standard coal, reduce 132,600 tons of carbon dioxide emissions, and economic benefits of about 152 million yuan ;

2. Improve the working efficiency of the kiln. Due to the use of forced convection heat exchange, the temperature uniformity in the kiln is improved and the cooling time is shortened compared with the traditional process; due to the use of waste heat preheating, the heating time is shortened compared with the traditional process;

3. The exhaust gas is discharged in an organized manner, which eliminates the heat pollution and smoke pollution in the workshop, and improves the working conditions of the workers.

Description of drawings

Figure 1 is a schematic diagram of a traditional refractory brick drying kiln.

Fig. 2 is a schematic diagram of high temperature waste heat utilization in the present invention.

Fig. 3 is a schematic diagram of low-temperature waste heat utilization in the present invention.

Figure 4 Schematic diagram of forced cooling.

Among them, 1. Circulation main pipe, 2. Circulation outlet branch pipe, 3. Electric control three-way valve, 4. Kiln, 5. Low temperature pipe, 6. Two-way valve, 7. Circulation fan, 8. Circulation inlet branch pipe, 10. Waste heat Pipe, 11, exhaust machine, 12, air/water heat exchanger, 14, cold water inlet, 15, hot water outlet.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

This embodiment provides a cluster intermittent refractory brick drying kiln waste heat utilization process, which includes the following steps.

Step 1: Utilization of high-temperature waste heat. As shown in Figure 2, after the operation of kiln A reaches the cooling period, the high-temperature gas in kiln A is sent to kiln B in the heating period through the circulation pipeline with a circulating fan for heat exchange. Until there is basically no temperature difference between A kiln and B kiln. A kiln transfers the physical sensible heat of the kiln body and refractory bricks to B kiln to preheat the kiln body and refractory bricks for B kiln, so as to improve the utilization rate of waste heat and reduce the power consumption of B kiln during the heating period.

In actual operation, for a group formed by multiple kilns, the cooling period of some kilns does not necessarily correspond to the heating period of other kilns. The mutual combined heat exchange is a dynamic process, and the optimization of the process can be achieved through scientific production. Scheduling and intelligent control means matching to achieve.

Step 2, electric heating, close the circulation pipeline between A kiln and B kiln, and conduct electric heating on B kiln to the rated process requirements, and complete the heating and heat preservation process of B kiln. At this stage, there is a small amount of high-temperature flue gas, which is discharged into the atmosphere through high-temperature exhaust pipes, heat exchangers, and chimneys.

Step 3, low-temperature waste heat utilization, as shown in Figure 3, a small amount of normal temperature air is introduced into kiln A to adjust the waste temperature in kiln A, and then the waste heat gas in kiln A and air/ The water heat exchanger performs heat exchange, and finally discharges the exhaust gas. Low-temperature waste heat can be used to heat hot water, which can be used for bathing, heating, etc., so that the waste heat can be fully utilized.

Step 4, forced cooling, as shown in Figure 4, when the temperature of kiln A is too low, close the valve of the waste heat pipe, pass air at normal temperature into kiln A and discharge it from the low-temperature pipe until kiln A reaches the temperature required by the kiln process, and the process is completed Cooling process. The purpose of this process is to speed up the turnover of the kiln, improve the utilization rate of the kiln, and increase the production efficiency. At the same time, the organized exhaust gas is conducive to reducing the heat pollution and smoke pollution of the workshop and improving the production conditions of the workers.

Step 5, the next cycle, after the operation of kiln B is completed, the waste heat utilization process is circulated to the next working kiln, and so on.

Further, the temperature of the above-mentioned high-temperature gas is 220°C, the temperature with almost no temperature difference between A kiln and B kiln is 110°C, and the temperature of the heat exchange between the residual temperature gas in A kiln and the gas/water heat exchanger is about 80~110°C , A kiln temperature is too low when the temperature is below 80 ℃.

This embodiment also provides a cluster intermittent refractory brick drying kiln using the waste heat utilization process of the cluster intermittent refractory brick drying kiln, including a kiln group consisting of several kilns 4, each kiln 4 in the kiln group All have electric heating equipment, and each kiln 4 is connected through the circulation pipeline, waste heat pipe 10, and low temperature pipe 5 respectively, and the circulation pipeline, waste heat pipe 10, low temperature pipe 5 are connected with each kiln 4. There is a circulating fan 7, and the waste heat pipe 10 communicates with the chimney with the exhaust fan after passing through the air/water heat exchanger 12, and the low temperature pipe 5 communicates with the chimney with the exhaust machine 11. The circulation pipeline includes a circulation main pipe 1 , a circulation outlet branch pipe 2 and a circulation inlet branch pipe 8 .

Further, the above-mentioned circulation pipeline communicates with the kiln head and the kiln tail of each kiln 4 through an electronically controlled three-way valve 3 , and the waste heat pipe 10 and low temperature pipe 5 communicate with each kiln 4 through a two-way valve 6 .

The high-temperature waste heat utilization process is as follows: in a kiln group, when a certain kiln A reaches the cooling period and a certain B kiln is in the heating period, open the valves leading to the circulation pipeline at both ends of the A and B kilns, and start under the action of the fan suction. Circulating heat exchange, the temperature of kiln A gradually approaches from 220°C to 110°C, and the temperature of kiln B gradually approaches from ambient temperature to 110°C. After hot air circulation, kiln A transfers the physical sensible heat of the kiln body and refractory bricks to Kiln B, for kiln B to preheat the kiln body and refractory bricks.

The electric heating process is: after cyclic heat exchange, the temperature of kiln B gradually approaches 110°C from the ambient temperature, and electric heating is required to raise the temperature to 220°C and keep it warm to meet the process requirements. At this time, close the valves at both ends of the B kiln leading to the circulation pipeline, open the valve of the B kiln leading to the high-temperature exhaust pipe, and turn on the electric heating until the furnace temperature rises to 220°C for heat preservation.

The low-temperature waste heat utilization process is as follows: after heat exchange, the temperature of A kiln gradually approaches 110 °C from 220 °C, and the cold air gear of the valve at both ends of A kiln and the valve leading to the high-temperature exhaust pipe of A kiln are opened, so that the cold air passes through both sides of the kiln. It enters through the high-temperature exhaust pipe, heat exchanger, and chimney into the atmosphere (as shown by the arrow in Figure 3), until the temperature of the smoke leaving A kiln drops to 80°C. This process uses a low temperature of 80°C-110°C The waste heat is used to heat hot water for daily use such as bathing and heating.

The forced cooling process is: when the temperature of kiln A gradually approaches 80 ℃ from 110 ℃, it is no longer useful. At this time, open the valve of kiln A leading to the low-temperature exhaust pipe, and close the valve of kiln A leading to the high-temperature exhaust pipe. Let the cold air enter through both ends of the kiln, and discharge into the atmosphere through the low-temperature exhaust pipe and chimney until the temperature of the smoke leaving A kiln drops to the temperature required by the kiln process, and the finished bricks leave the kiln.

The above description is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements or deformations can be made, including the traditional drying kiln Improvements made according to the present invention, these improvements or deformations should also be regarded as the protection scope of the present invention.

Claims (4)

1. a cluster batch (-type) refractory brick dry kiln UTILIZATION OF VESIDUAL HEAT IN technique, comprises the steps:

Step one, high-temperature residual heat utilizes, and arrives cooldown period after the operation of A kiln, to be sent into by the high-temperature gas in A kiln in the B kiln being in temperature raising period carry out cycle heat exchange, until A kiln and B kiln are substantially without the temperature difference by the circulating line with circulating fan;

Step 2, electrical heating, closes the circulating line between A kiln and B kiln, and carries out electrical heating to technique specification requirement to B kiln, complete heating and the insulating process of B kiln;

Step 3, low temperature heat, temperature more than passing in A kiln in a small amount of normal temperature air adjustment A kiln, more than the waste heat pipe then by having induced-draft fan guides in A kiln, wet body and gas/water-to-water heat exchanger carry out heat exchange, are finally discharged by tail gas;

Step 4, forces cooling, when A kiln temperature is spent low, closes waste heat pipe, passes into normal temperature air and discharged by cryotronl in A kiln, until A kiln arrives the temperature of kiln discharge technological requirement, complete temperature reduction technology process;

Step 5, next circulation, after the operation of B kiln, to next operation kiln circulation UTILIZATION OF VESIDUAL HEAT IN technique, so circulates.

2. cluster batch (-type) refractory brick dry kiln UTILIZATION OF VESIDUAL HEAT IN technique according to claim 1, it is characterized in that: described hot-gas temperature is 220 DEG C, A kiln and B kiln are 110 DEG C without the temperature of the temperature difference substantially, the temperature that remaining wet body in A kiln and gas/water-to-water heat exchanger carry out heat exchange is about 80 ~ 110 DEG C, and temperature when A kiln temperature is spent low is less than 80 DEG C.

3. one kind uses the cluster batch (-type) refractory brick dry kiln of cluster batch (-type) refractory brick dry kiln UTILIZATION OF VESIDUAL HEAT IN technique as claimed in claim 1, comprise the kiln group be made up of some kilns, it is characterized in that: each kiln in described kiln group all has electric heating equipment, each kiln is respectively by circulating line, waste heat pipe, cryotronl is communicated with, circulating line, waste heat pipe, cryotronl and each kiln connectivity part are equipped with valve, circulating fan is provided with in circulating line, waste heat pipe is communicated with the chimney with exhaust blower after gas/water-to-water heat exchanger, cryotronl is communicated with the chimney with induced-draft fan.

4. cluster batch (-type) refractory brick dry kiln according to claim 3, it is characterized in that: described circulating line is all communicated with by Electrocontrolled tee valve door with kiln tail with the kiln hood of each kiln, described waste heat pipe, cryotronl are communicated with by two-way valve with each kiln.