Issue 43/2013 - Application of advanced practical energy-saving technologies in chemical production

Talk about the application of advanced practical energy-saving technology in chemical production

□ Haohua Haitong Investment Management Co.
, Ltd.
Zhang Xinhua

China's chemical production in product innovation, optimization process, equipment upgrading, energy saving and consumption reduction, improve management and other aspects of still have a lot of room for improvement, this article takes the optimization of equipment in chemical production as an example, talk about several commonly used measures for energy saving and consumption reduction, in order to throw bricks and lead jade
.

1.
Energy-saving transformation of the three-way flow impeller of the water pump

At present, most of the pump products used by domestic enterprises are designed and manufactured on the basis of the theory of one-dimensional flow
.
The monist theory simply regards the flow state of the fluid inside the impeller as the uniform flow of the fluid in the bent tube, and the mathematical model established by this method is unrealistic for the impeller, so the actual efficiency of the impeller is very low
.

High-efficiency three-element flow pump energy-saving technology is a new energy-saving method
for pump equipment.
The technology can be designed and replaced with a high-efficiency three-way flow impeller according to the use of the pump, and the power saving rate can reach 5%~30%, and the power saving rate of the water pump with the valve is fully open is as high as more than
25%.
It is very suitable for energy-saving transformation of pumps with relatively stable working conditions (variable frequency speed regulation technology should be adopted for pumps with variable working conditions).

For example, Yunnan Huixi Iron and Steel carried out energy-saving renovation of 12 water pumps, and the comprehensive power saving rate reached more than 25%, saving 1.
6 million yuan in annual electricity costs; Haohua Aerospace Qinyang chlor-alkali branch plans to transform 5 DFS500-700 pumps, which is expected to save 1.
1 million yuan per year, and has done a good job in the preliminary technical demonstration
.

This technology has the characteristics of
outstanding energy-saving effect, less maintenance in the later stage, and no negative impact on the power grid.
When installing, the motor, pipeline, pump body, etc.
can be used, and the construction is simple and the effect is fast
.
It is mainly suitable for clean water pumps, circulating pumps, deep well pumps, pressurized pumps, soft water pumps, sewage pumps, etc
.
with relatively stable working conditions.

2.
Use heat and power cogeneration steam turbine to realize steam ladder utilization

The characteristic of steam is that it can be used in successive grading steps, and the more times it is used, the more fully
the energy is converted.
In general, the higher the steam parameters (temperature, pressure), the higher the energy grade and the higher
its energy conversion rate.
Steam ladder utilization is to reasonably arrange the matching relationship and conversion of various energies such as work, heat and material thermodynamics to achieve the best comprehensive effect
.

In order to meet the requirements of different working conditions, the steam generated from the boiler is generally depressurized by the temperature and pressure reducing device to match
the relevant process.
The steam ladder utilization is to first drive the running equipment through the work of the steam turbine, replacing the original equipment driven by electricity
.
The steam is then used for material heating according
to the process requirements.

There are three ways for steam turbines to achieve energy saving: directly drive various pumps, fans, compressors, etc.
; Power generation, driving a variety of synchronous and asynchronous generator sets; Both drag and generate electricity at the same time, that is, "one drags two" drags equipment and motors
at the same time.
For example, Haohua Junhua acetic acid project uses two power generation pumps to generate heat power steam turbines, which can save about 900,000 yuan in electricity costs every year; A B1.
8-1.
6/0.
02 thermal power steam turbine dragging air separation compressor can save more than
600,000 yuan in electricity costs every year.

Steam turbine energy saving has the advantages of
convenient operation, good safety, easy maintenance, mature technology, and can be networked with DCS or industrial computer to achieve remote control.

3.
Low temperature waste heat utilization of boiler flue gas

The low-temperature economizer is to recover the condensate of the boiler exhaust smoke waste heat heating recovery system, the condensate absorbs the exhaust heat in the low-temperature economizer, and then returns to the turbine low-pressure heater system after being heated and the temperature rises, and finally the turbine uses this part of the flue gas heat to drive the generator to generate electricity
.

Advantages of installing a low-temperature economizer:
1.
Fuel saving: After installing energy-saving measures such as low-temperature economizers, it can be seen from the thermal balance theory of the unit thermal system that the boiler can improve the thermal efficiency by about 3 percentage points, taking a 220t/h pulverized coal boiler as an example, it can save about 850 kg of fuel coal per hour, save about 9350 tons of fuel per year, and save more than
3 million yuan.

2.
Reduce water consumption: Generally speaking, the best desulfurization working temperature for wet desulfurization is 80~90 °C, and it is necessary to spray the relatively high temperature smoke through water at the inlet of the absorption tower, and then desulfurize after reducing to the appropriate temperature, which usually requires the consumption of a large amount of cooling water, resulting in waste
of water resources.
After installing a low-temperature economizer, the exhaust gas temperature is further reduced, which can reduce the consumption of
cooling water.

3.
Reduction of CO2 emissions: If an environmental tax is introduced, the carbon dioxide tax (carbon tax) will be included as a new tax, which can save a lot of carbon tax every year and contribute
to reducing the greenhouse effect.

For example, a 240t/h circulating fluidized bed boiler and a 220t/h pulverized coal boiler produced by Wuhan Boiler Plant are respectively equipped with low-temperature economizers, and each boiler can improve the boiler efficiency by about 3 percentage points after the transformation, save about 850kg/h of fuel, plus cost savings such as hydropower, and the annual energy-saving benefits of each are expected to be about 5.
75 million yuan
.

4.
Promotion and application of frequency conversion technology

In industrial production, according to the different process requirements and operating conditions, it is necessary to adjust the temperature, pressure, flow and other process parameters, and the most commonly used control means is to adjust the opening of the damper and valve of fans, pumps and other equipment
.
In this way, regardless of the demand for production, the fan and water pump must run at full speed, and the change of operating conditions makes the energy consumed by the throttling loss of the damper and valve
.

Through the frequency conversion speed regulation device, the motor speed is reduced to meet the operating conditions, and there is a lot of energy-saving space
.
For example, the operating speed of fans and pumps is reduced by 20%, and the power is reduced by 50%.

Haohua Junhua acetic acid project adopts frequency converter, with an average power saving rate of 30%, and the annual electricity saving income is about 1.
5 million yuan
.

After the fan water pump unit adopts frequency conversion speed regulation transformation, not only saves a lot of electric energy, but also because of the real soft start of the motor, the starting impact on the motor, fan, damper, high-voltage switch and other equipment and the power grid is greatly reduced, so that their service life can be extended, and the maintenance cost
of these equipment can be greatly saved.
In addition, the inverter has high-precision, wide-range stepless speed regulation function, which can not only fully meet the dynamic adjustment needs of flow, but also the inverter is a highly intelligent new equipment, which can improve production efficiency and unit automation level
.

5.
Water kinetic energy recovery cooling tower

The water kinetic energy recovery cooling tower uses the surplus pressure of the water pump to replace the traditional cooling tower motor and reducer with a water turbine, and changes the electric drive to a hydraulic drive to save the energy consumption
of the motor.
For example, the cooling tower of the circulating water system of Haohua Junhua acetic acid project has reduced a fan motor with a power of 90kW through energy-saving transformation, which can save more than 700,000 kWh
of electricity per year.

Compared with traditional cooling towers, turbine cooling towers have the following advantages: energy saving and making full use of the residual pressure
of circulating water pumps.
Safe, safe operation
in any explosion-proof environment.
Economical, due to the elimination of motors and reducers, which greatly reduces daily management and maintenance costs
.
Reliable, the hydraulic fan has mature technology, rigorous design, reasonable structure and stable operation, which fundamentally eliminates the failure of electric leakage, oil leakage, burning and damage of motor, electronic control and reducer, and provides a guarantee for safe and continuous operation; At the same time, the weight of the turbine is less than the sum of the canceled motor and reducer, so that the center of gravity of the cooling tower is shifted down, which increases the safety
of the operating environment.
Good cooling efficiency, with the change of the season, the speed of the hydrodynamic fan increases and decreases with the increase and decrease of the circulating water flow, and the air volume also increases and decreases, so that the air-to-water ratio of the cooling tower is stable in the best state, so as to achieve the best cooling effect
.

6.
Water (ground) source heat pump unit

According to the principle of the Carnot cycle, with the help of the compressor system, through a small amount of high-grade electrical energy input, a large amount of low-grade thermal energy that is not easy to use in the water source water is continuously replaced, so that it becomes available high-grade thermal energy, and realizes the transfer
of low-level energy to high-level energy 。 The resulting cold and heat source can not only meet the needs of winter heating and summer cooling of various buildings, but also solve the supply problem of domestic hot water at the same time, which is an energy-saving, environmentally friendly and advanced and practical new air conditioning technology, which has now become the first choice for
efficient and economical heating and cooling systems.
Junhua office building and acetic acid project production laboratory building use this device to control heating and cooling, which can save a lot of energy every year and have significant
economic benefits.

Water source heat pump unit products are characterized by safety and reliability, easy operation, automatic adjustment, high energy efficiency ratio and remarkable
energy-saving effect.

7.
Membrane oxygen production, oxygen enrichment and combustion energy-saving technology

Oxygen enrichment combustion is also a new energy-saving and environmental protection technology
.
The use of oxygen-enriched combustion technology in industrial boilers can improve efficiency by 5%~19%, and the coal-saving rate of coal-fired boilers is at least 10%.

For example, a SHL20-3.
82-I coal-fired chain grate steam boiler adopts membrane oxygen enrichment combustion energy-saving device, which can save 72,000 kW·h of electricity and 2,142 tons of coal throughout the year, and the economic benefits reach more than 1.
07 million yuan, and the equipment investment
can be recovered within one year of operation.
It also has the effect of stabilizing boiler working conditions, reducing air pollution, and prolonging boiler life, and the comprehensive benefits are very significant
.

In addition, there are other energy-saving equipment such as steam recovery devices, float steam traps, reactive power compensation (module technology) devices, fluorescent lamp savers, etc
.

All of these energy-saving measures apply to the contract energy management (EMC) model, which is an energy-saving investment method that pays for the full cost of energy-saving projects with the energy savings and can be shared
with the company.
After the expiration of the contract, the ownership of all energy-saving equipment belongs to the enterprise
.

EMC mode has the advantages of high energy saving efficiency, zero investment for enterprises, short investment recovery (the average payback period is generally 2~5 years), and enhancing the competitiveness of enterprises, which is worth vigorously promoting
.