What Is Waste Heat Recovery?

Waste heat refers to the sensible and latent heat of the original design that has not been reasonably used in the industrial energy consumption devices that have been put into operation due to the limitations of history, technology, and ideas.

Residual heat refers to the sensible and latent heat of the original design that has not been reasonably used in the energy consumption devices of industrial enterprises that have been put into operation, due to the limitations of history, technology, ideas and other factors. It includes high-temperature waste heat, cooling medium waste heat, waste steam waste water waste heat, high-temperature product and slag waste heat, chemical reaction waste heat, combustible waste liquid waste and waste heat. According to the survey, the total waste heat resources of various industries account for about 17% to 67% of its total fuel consumption, and the waste heat resources that can be recycled are about 60% of the total waste heat resources.

The setting machine is mainly composed of five parts, including the feeding part, the wefter, the chain, the oven body and the cloth falling and rolling device. In addition, there are chemical system and oil furnace heating system.

1.feeding part

The structure is relatively simple. It consists of a trough and a roller. The cloth enters the trough, carries chemical materials, and then squeezes the excess chemical materials through the rollers. Therefore, the chemical material on the cloth is very uniform, which is a prerequisite for obtaining high-quality shaped cloth.

What you should pay attention to here is to always pay attention to whether the pressure on the left and right sides of the roll is consistent. Otherwise, the side with less pressure will feed more, while the side with higher pressure will feed less.

Weft shaper

The weft aligner configured on the current setting machine is Mahlo RFMC94H photoelectric weft aligner. Mahlo photoelectric weft aligner has four sets of sensors. Each set of sensors includes two parts, light and light. . The action part uses a hydraulic system. When the signal of the weft slope size is transmitted back to the control board, the control board will issue a command to drive the hydraulic system to make the angle adjustment of the curved roller or straight roller, so as to correct the weft slope. Specifically: when there is a difference between the cloth center and the two sides, the curved roller will act; when there is a difference between the left and right sides, the straight roller will act.

3. Chain part

The tenter of the cloth on the setting machine is produced by the chain. The chain of the setting machine is driven by a high-power motor close to the place where the cloth is dropped. The chain is equipped with a needle plate. When the cloth enters the chain, the cloth roller on the cloth pressing wheel presses the cloth on the small needle on the needle plate. Driven into the oven by two rows of chains. The chain of this type of setting machine is different from other types of setting machines. It can control the stretch of each segment of stitches separately, so as to make a good effect, while some setting machines cannot adjust each segment of stitches, they can only be adjusted to Rectangle or trapezoidal.

4. Oven body

The setting machine generally has eight groups of ovens, and the air is continuously sprayed on the cloth surface by the fine holes in the star-shaped jet rack under the action of the circulating fan. After the hot air contacts the wet cloth, the temperature drops and the humidity rises, and it is discharged from the large hole in the star jet frame, passes through the filter screen, and then is heated by the heat exchanger and continuously recycled. The heat exchanger is located under the filter. The hot coal body is hot oil. The heat exchanger has many thin heat sinks to generate efficient heat exchange.

5. Cloth dropping and rolling device

The setting machine can adopt two kinds of cloth-out styles according to the production needs. Both methods are driven by a motor to drive the chain. When the cloth is rolled out, the tension stability of the cloth is high, and the cloth needs to pass through a tension-adjusting guide roller controlled by air . In the case of cloth drop cloth, the cloth does not need to pass through the tension adjusting roller but changes to a fixed guide roller.

There are many ways to recycle waste heat. Generally speaking, comprehensive utilization of waste heat is the best, followed by direct use, and indirect use (such as waste heat power generation). The comprehensive utilization is based on the quality of the waste heat, according to the order of the temperature, and the use of the steps. The high quality can be used for production processes or waste heat power generation; medium (120 degrees-160 degrees) can use ammonia water absorption refrigeration equipment to make -30 degrees The cooling capacity to 5 degrees is used for air conditioning or industry; low temperature can be used for heating or use absorption heat pump to increase the amount of heat or temperature for production and daily use.

1. The rational utilization sequence of waste heat steam is:

Combined use of power heating; Combined use of power generation and heating; Production process use; Use of steam turbines to generate electricity or directly replace motor-driven pumps; Domestic use; Residual heat absorption refrigeration equipment to achieve combined heat, power and cooling .

2. The rational utilization sequence of waste heat and hot water is:

It is used for perennial production technology; It is used for boiler and power generation; for daily use.

3. The rational utilization sequence of waste heat air is:

for production; for HVAC; for power; for power generation.

1. Application in chemical industry:

(1) Recovery of waste heat from the upper and lower gas of small synthetic ammonia

(2) Residual heat recovery from up and down gas in synthetic ammonia

(3)

1. Heat pipe waste heat recovery device

Waste heat recovery waste gas composition

The waste flue gas in the waste heat recovery equipment often contains sulfur dioxide and other components. When it encounters steam or moisture, it will form sulfurous acid substances, which will cause corrosion to the tube sheet and the weld, which will cause the leakage of the tube sheet or the weld, which will seriously affect the company's Continuous production requirements. In view of the above problems, traditional methods such as argon arc welding have a long maintenance cycle and high cost, and the service life after repair is often short, and the repair effect is difficult to achieve the desired effect. The polymer sheet can be used for on-site anticorrosion protection of the waste heat recovery device. The better application is the water-based coating containing inorganic ceramics from Amco (Kobe 3015-AL) high temperature resistant polymer composite. The material has excellent thermal shock resistance, oxidation resistance, chemical resistance, and temperature resistance up to 1200 ° F (648 ° C). This material can adhere to boilers, furnaces, rotary calciners, drying furnaces, chimneys and other High temperature structural steel and refractory. Can extend equipment life, reduce energy consumption and increase productivity. Therefore, the anticorrosion protection of the flue gas waste heat recovery device can be well completed. ^[1]

The exhaust gas emitted by the printing and dyeing setting machine not only contains a large amount of smoke and dust, but also contains various components such as polybenzene organics, printing and dyeing auxiliaries, and oil. Each setting machine generally emits 150-250 mg / m3 of particulate matter and 40-80 mg / m3 of oil smoke . The discharged oil, smoke, and dust have great harm to human health and the environment, and the pollution caused by the exhaust of the molding machine has become more and more acute.

Oil: derived from the nature of the fabric and the previous process, such as the exhaust gas contains a large amount of oil mist when the chemical fiber is shaped, while the exhaust oil content of pure cotton fabrics is very low;

Dust: fiber and combustible dust from fabric;

Smoke: solid particulate matter;

Printing and dyeing auxiliaries: At present, the annual output of China's textile auxiliaries is 260,000 to 280,000 tons, of which pretreatment agents are about 74,000 to 77,000 tons. 300 varieties; printing and dyeing auxiliaries of about 118,000 to 112,000 tons, including leveling agent, defoaming agent, opening powder, dye accelerator, emulsifier, dispersant, adhesive, fixing agent, fluorescent brightener There are about 600 varieties, including insurance powder, and post-finishing agents of about 68,000 to 71,000 tons. There are 5 varieties of antistatic agents, softeners, resin finishing agents, waterproofing agents, and coating agents.

Waste heat recovery and utilization

1. Direct heating heating system

After heating the circulating water with steam, it directly supplies heat to users. This heating method is called direct heating. The water supply pressure of the direct heating method is relatively low, generally not exceeding 0.6 MPa. This method is suitable for a heating system with a small heating area.

2.Indirect heating heating system

The indirect heating heating system divides the heating system into two circulation circuits, which are called primary network and secondary network, respectively. The two circulation circuits are connected together by the surface heat exchanger in the heat exchange station. High temperature water is circulated in the primary network, low temperature water is circulated in the secondary network, and the high temperature water is heated by the surface heat exchanger. The main function of the spray type hybrid heater is to replace the surface type steam-water heat exchanger and complete the heat exchange process of steam heating water. In this way, a condensate recovery system that is troublesome to manage can be omitted, and the space occupied is small, no maintenance is required, and the investment is only 1/5 of the surface steam-water heat exchanger, so it has obvious use advantages.

3.Recover flash steam from condensate

In the industrial production process that requires steam heating, a large amount of condensed water is often generated, and during the cooling process, a certain amount of flash steam is generated. In the past, this part of the low-pressure steam was often released because of difficult recovery or high recovery costs, wasting a lot of energy. Under the situation of increasing energy shortage, energy conservation is increasingly valued by enterprises. For production enterprises, throttling is more important than open source. Energy saving is to create benefits. The use of jet steam water heater technology can recover this part of waste steam. Although there is more than one method for recovering waste steam, this method has a small investment, high utilization of thermal energy, and is widely used. This method uses waste steam to heat water and then supplies it to industrial production or domestic use. A thermal system using a jet mixing heater to recover waste steam.

4. Use the secondary steam generated by the fixed and continuous drainage to heat the brine

In thermal power plants or industrial boiler room thermal systems that produce steam, continuous blowdown vessels and regular blowdown vessels are essential thermal equipment. The function of continuous drainage is to exclude the salt impurities in the pot water and control the salt concentration of the pot water; and the function of regular drainage is mainly to remove the loose sediment in the pot water. The amount of sewage discharged varies with the tonnage of the boiler. Generally, the continuous sewage discharge does not exceed 5% of the boiler evaporation, and the regular sewage discharge does not exceed 2% of the boiler evaporation. The sewage contains a lot of heat, but because the salt concentration in the sewage is too high, it cannot be reused and can only be discharged. After the sewage is discharged into the sewage expansion container, a large amount of secondary steam will be generated due to the expansion and pressure reduction. This part of the steam is pure and can be recycled. This type of steam can be recovered using jet-type mixing heater technology. It can be known from calculation that the energy saving benefit of recycling this part of steam is still considerable.