Abstract
The design of the utility engineering part of the production line with an annual production capacity of 1,000 tons of pyruvic acid is carried out to solve the problems of the supply of sterile air, chilled water and steam and to satisfy all the needs of the process production.
Combined with the material accounting, energy accounting and other calculation data of the plant process design, according to the specific requirements of the given process, to carry out the design and calculation of the public works supporting. On this basis, we draw the flow chart and carry out the selection of general equipment, non-standard equipment design, as well as the layout design of public works. After the comparison of the equipment, demonstration, selection of the most suitable for the process of public works equipment, in order to optimize the allocation of resources at the same time be able to do the least pollution of the environment, the least waste of energy.
Keywords: pyruvic acid fermentation plant design
1.1 Project Introduction 2
1.1 .1 Name of the construction project: 2
1.1.2 Scale of the construction, production method and working system 2
1.1.3 Selection of the plant site and its natural conditions 2
1.1.4 Conditions of the supply of utility works 3
2.1 Utility Engineering Design for Pyruvic Acid Fermentation Production 3
CHAPTER 2 AIR SYSTEM DESIGN 3
1.1 Air System Flow 3
1.1.1 Pre-treatment of Air 3
1.1.2 Air Decontamination Flow 4
2.1 Process Calculation of the Air System 5
2.1.1 Aseptic Fermentation Plant Peak Air Demand 6
2.1.2 Annual Consumption of Sterile Air in Fermentation Workshop 6
3.1 Selection of Air System Equipment 6
3.11 Rough Filter with Cloth Cloth Bag 6
3.1.2 Air Compressor 6
3.1.3 Cyclone Separator 7
3.1.4 Air Storage Tank 8
3.1.5 Wire Mesh Filter 9
3.1.6 Total Filter 11
4.1 Precautions for Equipment Installation 12
Chapter 3 Steam System Design 13
1.1 Flow of Steam System 13
1.1.1 Pre-treatment of Boiler Water 13
1.1.2 Flow Chart of Steam System 15
2.1 Calculation of Steam System 15
3.1 Selection of Equipment for Steam System 16
3.1.1 Single-flow Mechanical Filter 16
3.1.2 Countercurrent Na Ion Exchanger 16
3.1.3 Oxygen Removal Equipment 17
3.1.4 Horizontal Water-Fired Tube Boiler 18
4.1 Precautions for Equipment Installation 19
Chapter 4 Refrigerated Water System Design 19
1.1 Flow of the Refrigerated Water System 19
2.1 Calculation of the Cooling Water System 20
3.1 Selection of Equipment for the Refrigerated Water System 21
3.1.1 Compressor 21
3.1.2 Condenser 21
< p>3.1.3 Evaporator 224.1 Precautions for Equipment Installation 22
Chapter 5 Summary 23
1.1 Concluding Remarks 23
Chapter 1 Project Overview
1.1 Project Introduction
1.1 .1 Name of the Construction Project:
Annual Production Line of 1,000 tons of Pyruvic Acid Process design
1.1.2 Construction scale, production method and working system
(1) Construction scale: annual production capacity of 1000 tons of pyruvic acid
(2) Raw material glucose is preheated by preheater first, and then undergoes a continuous sterilizing process, which is made into sterilized culture medium. The yeast is put into the fermentation tank together with the sterilized medium and passes into the sterile air for fermentation, and then the product pyruvic acid crystals are extracted from the fermentation liquid.
(3) Work system: working days are counted as 300 days, and fermentation and filtration are carried out in two shifts.
1.1.3 Selection of plant site and its natural conditions
The project construction site is selected in Zhengzhou City, and its natural conditions are as follows:
Average annual temperature 16.3℃ Average highest temperature in a calendar year 38℃
Average lowest temperature in a calendar year -4.2℃ Average relative humidity of the hottest 85%
Average relative humidity of the coldest 75% of the year Average air pressure 1016.5mP
Average air pressure in summer 1004.5mP Average annual wind speed 3.6m/s
Average annual precipitation 1025.6mm Maximum daily precipitation 219.6mm
1.1.4 Conditions of supply of utility works
Utility Works Required conditions Required dosage
Bacteria-free air
Debacterialization rate >99% 102.6m3/min
Heating steam 121 ℃, 0.4mPa 2.5t/d
Cooling water 18 ℃ 126.73 t/d
2.1 Pyruvic acid fermentation production utility design
Plant design is a collaborative process of designers of all disciplines, collective creation. In the design process, the various professions both division of labor, and cooperation, in which the production process design is the core of the plant design, play a leading role in the work, and utility engineering design (auxiliary production engineering design) is to ensure that the normal production of the plant is an indispensable part of the important components, is based on the process of professional design requirements for the work. They complement each other to form the parts of the plant, forming an organic whole. In order to better play a leading role in the process, process designers must be familiar with and understand the auxiliary professional tasks, clear design process should be provided to the different auxiliary professional necessary process design information and put forward different requirements, as the basis for the auxiliary professional design. At the same time, we should utilize the design results of auxiliary specialties to serve the process design. When there is a contradiction, consult to solve it and determine a reasonable program. This is very important to ensure the quality of design, accelerate the progress of the project, and to ensure that the plant is put into operation after the good operating results. In addition, in some factories, especially in the construction of small plants, expansion, due to the lack of technical force, often also need process technicians to consider the relevant issues in the public works.
Chapter 2 Air System Design
1.1 Air System Flow
1.1.1 Pre-treatment of Air
Most of the microorganisms in the air are attached to the dust particles in the air. The main measures to improve the cleanliness of the air before compression are to raise the position of the air suction port and to strengthen the pre-filtration of the inhaled air.
In order to protect the air compressor, often set up in the air suction inlet coarse filter to filter out the air particles of larger dust, reduce the dust and microbial content into the air compressor and compressor wear and tear, and to reduce the load of the main filter to improve the quality of air sterilization. For this kind of pre-filter, it is required to have high filtration efficiency and low resistance, otherwise it will increase the suction load of the compressor and reduce the exhaust volume of the compressor. Usually use bag filter, packing filter, oil bath filter and water mist dust removal filter.
In order to save costs, this design uses a bag filter.
1.1.2 Air sterilization process
The use of two-stage cooling, heating sterilization system, the flow chart in Figure 1:
The two-stage cooling sterilization process is a more complete air sterilization process, which can be adapted to a variety of climatic conditions, and can adequately separate the oil and water, so that the air to reach a low relative humidity into the filter to improve filtration efficiency. The process is characterized by two coolings, two separations and proper heating. The advantages of two cooling and two separations of oil and water are that the heat transfer coefficient can be improved, cooling water can be saved, and oil and water can be separated more completely. After cooling by the first cooler, most of the water and oil have been formed into larger droplets, so it is appropriate to use the cyclone separator separation. The second cooler so that the air further cooling precipitated a portion of the smaller mist particles, it is appropriate to use the screen separator separation, so that the screen can be separated from the smaller diameter of the mist particles and the separation effect of the role of high. The first level of cooling to 30 ~ 35 ℃, the second level of cooling to 20 ~ 25 ℃. After removing the water, the relative humidity of the air is still 100%, and must be heated with a heater after the screen separator to reduce the relative humidity in the air to 50%~60% to ensure the normal operation of filtration [1].
In order to overcome the resistance of the filtration medium and other resistance in the conveying process, the inhaled air must be compressed by an air compressor. Air compressed, the temperature will rise significantly, the higher the compression ratio, the higher the temperature. If this high-temperature compressed air directly into the air filter, will cause charring or combustion of the filter media, but also increase the cooling load of the culture device, to bring difficulties in controlling the temperature of the culture, while high-temperature air will also increase the evaporation of the culture liquid water, the growth of microorganisms is also unfavorable, so it is necessary to reduce the temperature of the compressed air. So after the air storage tank to install a cooler, such as flow chart in the 4, 6 two places.
According to equation (1):
(1)
When the total pressure P and moisture content χ of the air is a certain value, the relative humidity φ varies with Ps. However, Ps is a function of temperature, and φ therefore varies with the temperature, i.e., φ decreases when the temperature increases, and conversely, φ increases. If the temperature drops to the dew point, φ rises to 100%, the excess part of the water vapor will be condensed into dew droplets and precipitation, the same compressed air entrained oil will also be condensed down. It can be seen that the cooling of the air after the increase in relative humidity, will precipitate water, so that the filter media moisture failure, so the compressed wet air to remove water, at the same time, because the air after the compressor will inevitably entrained lubricating oil, so remove the water at the same time also to remove oil. Therefore, in the 5 place to set up a cyclone separator used to remove the water and oil in the air.
Media filter is the use of block media, granular media, mesh media or polymer material screen inertia interception to separate the air in the water and oil droplets in the method. In a variety of media filter screen separator has a high separation efficiency, it is greater than 5 μm diameter particles separation effect of up to 99%, greater than 10 μm can be as high as 99.5%, and can go out part of the 2-5 μm of the finer particles, coupled with a simple structure, resistance is not large, etc., is widely used in production. Flow chart in 7 is a screen filter.
A total filter is set at the end, which is the most important filter in the process, used to filter out most of the residual oil, water and fungi in the air to achieve the required sterile air requirements.
2.1 Air System Process Calculation
Basic data of production process: annual output of 1000t pyruvic acid, acid production rate of 72g/l, conversion rate of 70%, extraction rate of 80%, 1% bacterial contamination rate, 300 working days per year, fermentation cycle of 64h, 8 hours of auxiliary time, the average aeration ratio of 1:0.3
2.1.1 Peak of aseptic air in fermentation workshop Demand
Vmax=2×238.75+6×995=6247.5(m3/h)=1.74(m3/s)
2.1.2 Annual consumption of aseptic air in fermentation plant
V=6×6.5×10-6+2×1.63×106=4.23×107(m3)
Aseptic air Consumption: (75×0.7×6+5×0.7×2)×0.3=102.6m3/h
3.1 Selection of air system equipment
3.11 Rough cloth bag filter
The structure of the cloth bag filter is simple, as long as the filter cloth is sewn into a cloth bag of the same shape as the skeleton, which is tautly sewn to the skeleton and sewn tightly to all the gaps causing a short circuit. The filtration efficiency and resistance loss of bag filter depends on the structure of the selected filter cloth and the area of the filter cloth. The cloth is strong and detailed, the filtration efficiency is high, but the resistance is large. Now more synthetic fiber filter cloth, non-woven cloth. Filter cloth requires regular washing to reduce resistance and improve filtration efficiency. This design uses synthetic fiber filter cloth, airflow rate of 2-2.5m/min, air resistance is about 60-120mmHg.
3.1.2 air compressor
Fermentation industry commonly used gas transmission equipment for low-pressure air compressor, used to provide the fermentation industry production requirements for the provision of compressed air 0.2 ~ 0.3MPa (gauge pressure). Generally used is the turbine air compressor or modified reciprocating air compressor as the main air compressor station for gas delivery equipment. The air is compressed to a certain pressure, and through the air sterilization system, a certain pressure of sterile air is obtained for deep culture. Comparison of the two types of air compressors is shown in Table 1.
Types of compressors Feature Advantages Disadvantages
Turbine type Large air supply, stable outlet pressure, the output of compressed air does not contain oil mist Power consumption is small, compact structure, small footprint Higher technical requirements
Reciprocating type
Operation of the gas under pressure and heat, so the outside of the cylinder should be cooled Capacity range, cheaper, operation and maintenance. The price is cheaper, the operation and maintenance is more convenient The outlet flow is not stable, the pressure out of the gas with oil mist
Table 1 Comparison of two kinds of air compressors
Because of the turbine air compressor output compressed air does not contain oil mist, to the back of the air sterilization to bring a great deal of convenience to the air filtration system has been simplified to reduce some of the cost, so the design of this design adopts the turbine type of air compressor.
No oil mist in the compressed air output.
Aseptic air consumption: (75×0.7×6+5×0.7×2)×0.3=102.6m3/h=60.38acfm.
Turbine air compressor is selected at the beginning, model HP1.0, exhaust 40acfm, two parallel work, 40acfm×2 =80acfm>60.38acfm, so it meets the process production requirements. So it meets the requirements of process production.
3.1.3 Cyclone separator
Cyclone separator is a simple structure, low resistance, high separation effect of gas-solid or gas-liquid separation equipment. Air generally 15-24m / s flow rate in the tangential direction into the cyclone separator, and in the circumference of the circular motion, oil and water droplets have much greater than the air due to the gravity, so there is a larger inertial force, so when the air in the separator to do the circular motion, oil and water droplets are still straight line of motion, and thus settled on the wall. Exhaust air velocity of 4-8m / s, oil and water droplets in the cyclone separator in the radial velocity and air velocity is proportional to the square, but with the increase in the radius of gyration and decrease, so the cyclone separator inlet tube cross-sectional area is generally smaller, the separator tube diameter is also smaller. However, the greater the flow rate of the inlet air, the smaller the tube diameter, the greater the resistance of the air.
Figure 2 Cyclone Separator
The scale size of a general cyclone separator is roughly:
D1=0.4-0.6, L1=1-2D, 2-3D, h=0.5D, b=0.2-0.25D, D2=0.2-0.35D
For convenience, the following formula can be used to roughly estimate the diameter of the separator D
(2)
Equation (2) in: Q - air flow through the cyclone separator, m3/min.
The air flow through the cyclone separator Q = 120m3/min
D = 0.1 = 1.095m, so D take 1.1m.
D1=0.5m L1=2D=2.2m L2=3D=3.3m h=0.5D=0.55m b=0.2d=0.22m D2=0.2D=0.22m
3.1.4 Air Storage Tank
The compressed air is cooled to a certain temperature, and after splitting the oil and water, the relative humidity of the air is still 100%, and if it is not heated up, the temperature is slightly reduced. Warming, as long as the temperature is slightly lower, it will again precipitate water, so that the filter media moisture and reduce or lose filtration capacity. Therefore, it is necessary to heat the compressed air to a certain temperature after cooling and removing the moisture, so that the relative humidity is reduced before it is fed into the filter. Compressed air heating temperature selection to ensure that the air is dry, to ensure that the filter sterilization efficiency is very critical. Generally speaking, the temperature difference between the temperature after humidity reduction and the temperature after humidity increase is about 10-15 ℃, which can ensure that the relative humidity down to a certain level to meet the requirements of the filter.
Heating of the air is generally realized with a tube heat exchanger, the air from the compressor is pulsed, in front of the filter needs to be installed in an air storage tank to eliminate the pulse to maintain the stability of the tank pressure. The role of the air storage tank in addition to pressure stabilization, but also allows some of the droplets to settle in the tank. The structure of the tank is shown below:
Figure 3 Structural diagram of the tank
The volume of the storage tank is calculated as follows: V=0.15v (3)
Equation (3) in which: V-volume of the storage tank; v-compressed air flow rate, m3/min.
Volume of the storage tank V=0.15v = 0.15v. 0.15v=0.15×120=18m3
Set the height to diameter ratio of the cylinder part of the storage tank is 2.5:1
Then
Then D=2.09m, H=2.5D=5.23m
3.1.5 Silk Screen Filter
This design of media filter filter medium using 0.25mm×40 Mesh stainless steel wire mesh, mesh media layer height of 150mm, the schematic diagram is as follows:
Figure 4 Wire mesh filter structure
Maximum air flow rate through the mesh:
(4)
Equation (4) in: ωmax - the maximum air flow rate, m / s; ρp -- specific gravity of the droplet, kg/m3; ρg -- specific gravity of air, kg/m3; K -- coefficient, take 0.107
Find out that at 25℃ the air's The specific gravity ρg is 1.2×103 kg/m3, and the specific gravity ρp of water droplets is 1.022 kg/m3
Then ωmax=0.107 = 3.12m/s
The design speed ω of the screen separator is 75% of the maximal flow rate of the air as mentioned above, i.e.
ωdesign=0.75ωmax=2.34m/s
Diameter of screen separator:
(5)
Equation (5) in: D - diameter of the screen separator, m; V - gas flow rate, m3/s.
Then the diameter of the screen separator, D = = 0.977 m
3.1.6 Total filter
Because the production needs of sterile air requirements are relatively high, from the filtration efficiency and affordability considerations, this design adopts the fiber media deep filter, the structure of which is shown in Figure 5:
Figure 5 Fiber Media Deep Filter
This fiber media deep filter is usually a vertical cylinder type, the internal filling of the filter media, the air passes through the filter media from the bottom up to achieve the purpose of decontamination.
The dimensions of the air filter mainly include the diameter D and the height of the effective filter layer L, where D can be derived from the formula (6):
(6) (6)
The formula (6): qν - the volume flow rate of air through the filter, m3 / s;
νs
The air cross-section air velocity, m/s.
The air cross-section air velocity νs can be generally taken as 0.1-0.3m/s, according to the operating process is set to 0.2m/s,
qν= 102.6m3/min=1.17 m3/s
Then D= =2.73m
The effective filter media height L of the filter is calculated as:
Then
Cotton fiber filter is selected, and the diameter of the selected cotton fiber is d=16 μm, and the filling coefficient is α=8%
Ventilation volume is 120 m3/min, p=4kg/m3, and the fermentation cycle is 72h
Assuming that the bacterial content of the air entering the filter is 5000 bacteria/m3, air flow rate is 0.2m/s
Check K'=0.135cm-1, the backflow rate is 0.1%
Then N1=5000×120×60×72=2.592×109, N2=10-3
Thickness of filtering layer =63.6cm
4.1 Precautions for equipment installation
(1) A safety valve should be installed on the gas storage tank, a drain should be installed at the bottom, the flow direction of air in the tank is from bottom to top, and a screen mist eliminator should be placed inside the tank.
(2) The filter's effective filtration medium height L decision, usually on the basis of experimental data, according to the law of logarithmic penetration calculation. However, due to the need for the thickness of the filter layer, consume too much cotton, installation is more difficult, resistance loss is very large, so the factory commonly used activated carbon as an intermediate had to improve these factors. This would have been inconsistent with the calculation requirements. Usually the total height of the upper and lower cotton layer thickness of each of the total filtration layer of 1/4-1/3, the middle of the activated carbon layer accounted for 1/3-1/2. Before laying cotton, first in the lower orifice plate laying a layer of 30-40 mesh wire mesh and fabrics, which helps the air evenly into the cotton filter layer.
Chapter 3 Steam System Design
1.1 Steam System Flow
1.1.1 Pre-treatment of Boiler Water
In order to ensure reliable, long-lasting and safe operation of the heating system, the water supplied to the boiler room must be treated. In the boiler room using a variety of water sources, whether natural water, or tap water, contain some impurities, can not be directly used for boiler water supply, must be processed, in line with the boiler water quality standard difficult to supply the boiler to use, otherwise it will affect the boiler's safe and economic operation. Therefore, the boiler room to set up water treatment equipment.
Natural water (whether groundwater or groundwater) in the process of cyclic movement in nature, dissolved and mixed with a large number of impurities. These impurities can be divided into three categories according to the size of their particles: the largest particles known as suspended solids, followed by colloids, the smallest are ions and molecules, i.e., dissolved substances. Suspended matter is the water flow is suspended state of the material, its particle diameter of 10-4mm or more, through the filter paper can be separated. Mainly clay, sand, plant residues, industrial waste, etc..
Colloidal material is a collection of many molecules and ions, its particle size between 10.4 ~ 10.6mm. Colloidal substances in water are compounds of iron, aluminum, silicon, etc., as well as decomposition products of plant and animal organisms - organic matter.
The dissolved substances in natural water are mainly salts such as calcium, magnesium, potassium, sodium and gases such as oxygen and carbon dioxide. Most of these salts exist in the water in an ionic state, and their particle diameter is less than 10.6mm. the dissolved gases in the water exist in a molecular state.
Suspended matter will cause deposits, contaminate the resin, clogging pipes, too much suspended matter will make the pot of water froth. Colloidal substances will contaminate the resin, affecting the quality of water, into the boiler, will produce a large number of bubbles, causing vapor **** vacated. Suspended and colloidal substances in natural water are usually removed for the most part by coagulation and filtration in the waterworks. If this appears to be clarified, still contains impurities in the water without treatment directly to the boiler supply, a part of the dissolved salts in the water (mainly calcium, magnesium salts) will precipitate or concentrate precipitate out. Part of the precipitate is relatively loose, known as water slag; and the other part of the heated surface attached to the inner wall, forming a hard and dense scale. The presence of scale on the boiler safety, economic operation is very harmful.
(1) boiler water filtration
Industrial boiler room water is generally supplied by the water plant. If the suspended solids content of the raw water is high, in order to reduce the burden of softening equipment, the raw water must be filtered. For smooth regeneration fixed bed ion exchanger, suspended solids greater than or equal to 5mg / L of raw water should be filtered; into the countercurrent regeneration fixed bed ion exchanger or floating bed exchanger raw water, suspended solids content greater than or equal to 2mg / L should be filtered; suspended solids content of greater than 20mg / L of raw water or lime treatment of water should be coagulated, clarified by filtration after treatment.
(2) cation exchange softening
Suspended and colloidal substances in the water is usually precipitation, filtration and other treatments after the water plant is mostly removed. But the hardness of the water, alkalinity and other impurities still exist, in order to meet the boiler feed water quality requirements, the need for boiler feed water treatment. Industrial boiler room water treatment is the main content of softening and deoxidizing, that is, to remove calcium and magnesium ions in the water, reduce the oxygen content of the feed water. The use of cations that do not produce hardness (such as Na +, H +) will be in the water Ca2 +, Mg2 + replacement, so as to achieve the purpose of water softening, this method is called cation softening method. Also known as ion exchange softening. Ion exchange softening is achieved through the ion exchange agent.
Currently in the industrial boiler water treatment, sodium ion exchange softening used most. Ion exchanger loaded with cationic exchanger, raw water flow through the sodium ion exchange agent, the Na + exchange agent with the Ca2 +, Mg2 + ions in the water for replacement reaction, so that the water is softened. Sodium ion exchange can remove both the temporary hardness in water, and can remove permanent hardness, but not in addition to alkali, because the temporary hardness of the main part of the alkalinity of natural water according to the rules of the mass of the same thing is transformed into sodium salt alkalinity NaHCO3; In addition, according to the rules of the exchange of the same thing is the mass of the same thing 1 mol Ca2 + and 2 mol of Na + exchange reaction, so that the soft water increased the amount of salt.
With the exchange of softening process, the Na+ in the exchanger is gradually replaced by Ca2+ and Mg2+ in the water, and the exchanger is gradually changed from NaR type to CaR2 or MgR2 type. When the hardness of the softened water exceeds a certain value, the water quality does not meet the requirements of the boiler water quality standards, it is considered that the exchanger has failed, at this time should immediately stop the softening of the exchanger for regeneration.
There are many types of ion exchange equipment, fixed bed, floating bed, flowing bed. Floating bed, flowing bed ion exchange equipment for raw water quality is stable, the softened water output does not change much, continuous uninterrupted operation, the fixed bed without the above requirements, is commonly used in industrial boiler room softening equipment.
Fixed-bed ion exchange equipment can be divided into two categories: downstream regeneration ion exchanger and counter-current regeneration ion exchanger.
(3) deoxygenation of boiler feed water
The corrosion of boiler metal is mainly electrochemical corrosion. Boiler feed water and pot water are electrolytes, because the impurity part of the metal wall of the boiler for the cathode, the electrons it gets will be combined with the pot water ions (such as H +) and constantly removed.
If the corrosion products (such as Fe3+) accumulated in the anode, or electron e accumulated in the cathode is not removed, then the potential difference between the two poles to reduce the corrosion stagnation or cessation of this phenomenon is called "polarization". Conversely, the elimination of polarization (known as "depolarization" phenomenon), the corrosion will be accelerated.
pH<7, the water has more H +, H + is the cathode of the depolarizing agent will accelerate corrosion. At the same time, acidic water will make the metal oxidation protective layer dissolved, also accelerate corrosion. It can be seen that in order to avoid and reduce the electrochemical corrosion of boiler metals, in addition to maintaining a certain alkalinity of the pot water, but also deoxygenation of the feed water.
1.1.2 Steam system flow chart
Steam system of simple flow diagram shown in Figure 2:
Figure 6 Steam system flow diagram
Design of the steam system should also be economically considerations, in order to meet the needs of users under the premise of the lower the pressure of the steam supply, the better, but still need to take into account the pressure drop required by the steam condensate recovery system. In order to effectively utilize the energy of the swallow steam, often the first high-pressure steam through the turbine, and then use the turbine exhaust steam supply plant production; when the turbine stops working, there should be pressure reducing valves and desuperheaters to ensure that the steam supply of low-pressure steam system.
2.1 Calculation of steam system
The process needs to be heated by 121℃, 0.4mPa steam
The amount of steam needed for the serpentine steam heating stage of each fermenter is G=3887.15 kg
The amount of steam needed for the direct steam heating stage of each fermenter is G'= 2139.53 kg
Considering 5% steam loss, and there are two fermenters fermenting at the same time, the total steam consumption is:
Total G=(3887.15+2139.53)×2/0.95=12.696 t/d
3.1 Selection of Steam System Equipments
3.1.1 Single-flow Mechanical Filter
The filtration equipment used in this design is single-flow mechanical filter because it has the advantages of simple filtration piping system, stable operation and low price. Single-flow mechanical filter is also the simplest kind of filter. Its simple schematic diagram is shown in Figure 3:
Figure 7 Single-flow Mechanical Filter
Single-flow mechanical filter body is a closed steel cylindrical container, with water inlet and drain piping, the filter is filled with filtering materials, commonly used quartz sand, marble, anthracite and so on. Quartz sand should not be used for filtering alkaline water, because quartz sand dissolved in the water to produce silicic acid harmful to the boiler; anthracite, marble is suitable for alkaline water. The diameter of the filter media is 0.5~1.5mm, the filtration speed is 4~5m/h, and the operation cycle is generally 8h.
3.1.2 Countercurrent regenerative Na ion exchanger
Because the countercurrent regenerative ion exchanger equipment has the advantages of high quality of effluent and low salt consumption, the countercurrent regenerative Na ion exchanger is adopted in this design. Its simple schematic diagram in Figure 4:
Figure 8 Countercurrent regeneration ion exchange equipment
The so-called "countercurrent regeneration", that is, regeneration of regeneration liquid flow and water softening operation in the opposite direction of the flow. Usually, the salt solution enters from the lower part of the exchanger and discharges from the upper part. Therefore, the fresh regeneration fluid is always the first with the bottom of the exchanger has not yet completely failed to contact the exchanger, so that it gets a very high degree of regeneration, with the regeneration fluid continues to flow upward, the regeneration degree of the exchanger is gradually reduced, but the regeneration process than the downstream much slower (lower exchanger saturated degree of small than the upper part of the...), the regeneration fluid in the replacement of the Cold Water Replacement System. Regeneration of Ca2+, Mg2+ replaced in the liquid less). When the regeneration fluid and the upper part of the complete failure of the exchange agent contact, the regeneration fluid still has a certain "freshness", can still play a reducing role, the regeneration fluid can be fully utilized [8].
3.1.3 Oxygen removal equipment
From the law of gas solubility. The solubility of the gas in water is proportional to the partial pressure of the gas at the gas-water interface, and inversely proportional to the temperature of the water. In the open equipment will be heated, as the water temperature rises, the gas-water interface on the partial pressure of water vapor also increased, the partial pressure of other gases to reduce, when the water reaches the boiling point, the water interface on the partial pressure of water vapor and the outside world pressure is equal to the partial pressure of other gases tends to zero, the content of dissolved gases in the water also tends to zero. This is the working principle of thermal deoxidation.
Heating method of oxygen removal equipment called thermal deaerator. Industrial boiler room steam boiler is often used atmospheric thermal deaerator, that is, deaerator pressure slightly higher than atmospheric pressure (generally 0.02MPa, operating temperature 104 ℃), in order to facilitate the escape of gas can be discharged.
Commonly used spray packing type thermal deaerator shown in Figure 9.
Figure 9 spray packing type deaerator
Deaerator consists of deaerator head and deaerator tank two parts. Feed water from the deaerator head of the upper inlet pipe into the inlet pipe and parallel to each other with several rows of nozzles with the spray pipe connection, the water through the nozzle is sprayed into the mist, the requirements of the nozzle inlet pressure of 0.15-0.2MPa or so. The lower part of the deoxidizing head has two layers of aperture plate, between the aperture plate is equipped with stainless steel packing (also known as Ω element), foggy water droplets fall into the water tank after the packing layer.
Steam from the deoxidizing head of the lower part of the inlet pipe into the upward flow, precipitation of gas and part of the steam through the top of the conical baffle refractor, discharged by the exhaust pipe.
The feed water in the deaerator is first sprayed into a mist heating, with a large surface area, conducive to the escape of oxygen from the water, and then in the filler layer in the state of the water film is heated, and the steam has a full contact, and the filler also has the role of heat storage, so the deaerating effect is better, and adapt to load fluctuations is strong.
3.1.4 Horizontal water-fired tube boiler
Since the amount of steam required by the fermentation plant is not large, so the use of horizontal water-fired tube boiler is more appropriate.
Horizontal water-fire tube boiler is a horizontal external combustion boiler that combines water tubes and fire tubes. This boiler is the creation of the 20th century in the horizontal external combustion back to the water tube boiler on the basis of the development of a whole boiler. Currently in the use of small coal-fired boilers occupy a large proportion.
The boiler cylinder and the heating surface are supported in the steel plate welded to the base, grate grate and ventilation devices are all formed in the support structure. The boiler walls are insulated with vermiculite bricks, plus a thin iron skin, forming a whole boiler. Therefore, the boiler is also known as horizontal quick release boiler. Quick-fit boilers are compact, easy to transport and simple to install. Relative to other fire tube boilers, because the furnace can be arranged according to the circumstances of the kind of arch wall, the furnace combustion is better. At the same time, due to the high flue gas flow rate in the furnace, so that the heat transfer coefficient of the fire tube to improve and reduce the accumulation of ash. Especially in the layer part of the additional coal economizer, so that the exhaust temperature is reduced, the boiler efficiency can reach more than 75%.
4.1 Precautions for equipment installation
(1) When the pressure drop of the raw water through the filter layer reaches 0.05~0.06MPa, the filtration should be stopped and the backwash should be carried out to flush out the sludge retained in the layer of the filter media in order to restore its working capacity. Backwashing intensity is 15L/(s?m2), rinsing time is 10min, and finally positive washing until the water is qualified, then filtration can be carried out again.
(2) the exhaust valve opening should be appropriate, too large will cause steam waste, too small will affect the deoxygenation effect, so need to be repeatedly adjusted to maintain its optimal opening.
(3) In order to ensure that the important users of steam, the design should be considered to set up an automatic steam cut-off system, in the event of an accident, according to a predetermined procedure to cut off the load of non-important users. In order to confirm the reliability of the sub-system, the test is carried out during daily production.
(4) the design of the steam system, the diameter of the system trunk to be considered in accordance with the steam generating equipment for the continuous maximum supply of steam, in order to facilitate future plant expansion or to adapt to changes in production.