Application of Polyurethane Insulation Material in External Wall Insulation of Yellow Wine Fermentation Tank

Application of Scientific and Technological Innovation of Polyurethane Insulation Material in External Wall Insulation of Yellow Wine Fermentation Tank Jiang Fengshan Zhejiang Yuezhou Anticorrosion Engineering Co., Ltd. Zhejiang Shaoxing 312000 Yi. The article first introduces the current status of the insulation of yellow wine fermenters and the thermal insulation properties of polyurethane materials. Then it briefly describes the construction process of polyurethane insulation materials on the outer wall of the fermenter. Finally, the concrete examples show the use of polyurethane insulation materials on the outer wall of the yellow wine fermentation tank. The economic benefits brought.

It has excellent physical and chemical properties, including low thermal conductivity, uniform material distribution, high compressive performance, good waterproof performance, good thermal insulation and cold preservation; easy construction and convenient processing, and can be used in a variety of objects. Surface construction and processing insulation layer. At the same time, it has the characteristics of protecting the main structure, preventing condensation inside the structure, and has no obvious influence on the environment. It belongs to energy-saving and environment-friendly insulation materials and is one of the ideal insulation materials at present. In this paper, the polyurethane insulation material is introduced into the outer wall insulation system of the yellow wine fermentation tank. It is proved by theory and practice that the polyurethane insulation material also has excellent performance in the fermenter insulation application.

1. Current Status of Yellow Wine Fermentation Tanks The production of yellow wine mainly includes three steps of cooking, fermentation and filtration. The fermentation process has the greatest impact on its quality. In the fermentation process of rice wine, a variety of intermediate metabolites are produced, which are rarely contained, but have a great influence on the quality and taste of rice wine. And their production depends mainly on the temperature during the fermentation process. Yellow wine fermentation is divided into pre-fermentation and post-fermentation, corresponding to the pre-fermentation tank and the post-fermentation tank. The temperature of the rice wine into the tank depends on the room temperature, but the highest fermentation temperature does not exceed 32 ° C. Immediately after the end of the fermentation, it is sent to the post-fermentation tank, and the temperature is maintained at 15 ° C and 18 ° C until the end of the fermentation. Generally, the fermentation broth temperature is required to be controlled within ±0.3 °C of a given temperature in order to obtain a desired fermentation condition. Therefore, grasping the fermentation temperature in the fermentation process of beer and controlling the rate of temperature rise and fall are the core to determine the quality of beer production.

The rice wine fermenter is generally a large-scale atmospheric pressure vessel welded by stainless steel or carbon steel. Usually, the volume of the post-fermentation tank is more than 20 cubic meters. Two layers of heat-insulating material are attached to the outer wall of the fermenter. There is a mixture of fermented raw materials such as water and rice. The temperature of the liquid inside the fermenter is kept uniform by self-circulation; the steam is supplied to the circulating liquid to heat the material in the tank to reach the temperature specified by the process, and the steam valve is closed. To maintain the state of constant temperature inside the fermenter. Therefore, the insulation layer on the outside of the fermenter is still important. Reducing the amount of heat dissipation can keep the internal constant temperature state longer and more stable, thereby reducing the consumption of steam and achieving energy saving.

The outer wall insulation material of the food industry is usually made of rock wool or polyurethane spray. As the thermal insulation material, the construction process is more complicated than other insulation materials. Firstly, it must be welded on the outer wall of the storage tank. After fixing the rock nails of the rock wool board, the rock wool board is tied to the outer wall of the storage tank by the steel mesh. Then layered plaster on the rock wool, wrapped with fiberglass mesh cloth, and then coated with asphalt paint on the outer layer. The whole construction process consumes a lot of time and manpower, and its use time is short, and the durability is not good. Relatively speaking, the construction process of polyurethane spraying is simpler, the durability is better, the thermal conductivity is lower than 0.029W/(m2K), and the protective layer of thin steel plate is added on the thermal insulation layer, which is relatively cheaper. high. Therefore, according to the thermal insulation characteristics of the yellow wine fermenter, the use temperature is relatively low, and it can be considered to use the energy-saving rigid polyurethane outer wall insulation system of the residential house for the thermal insulation construction on the outer wall of the yellow wine fermentation tank.

2, polyurethane material insulation performance analysis of the selection of insulation materials: the first use of materials with low thermal conductivity, large heat storage coefficient; secondly should choose materials with better chemical stability to ensure that no chemical reactions occur during insulation; Lightweight, non-toxic, flame-retardant thermal insulation material; finally, the material requires low water absorption and good construction performance.

In order to maintain a good thermal insulation effect, when the thermal insulation material is selected on the outer wall of the yellow wine fermentation tank, the thermal insulation material with high thermal resistance is selected in the same manner as other industrial storage tanks, that is, the apparent density is relatively small, and the thermal conductivity is relatively high. The low-efficiency and low-cost insulation material has a thermal conductivity of not more than 0.05 W/(m2K) under normal conditions. At the same time, the lower the moisture absorption rate of the insulating material selected, the better, and the bonding performance should be as good as possible. In addition, as long as possible, a dimensionally stable insulating material is used, so that the stress generated when the dimensional change is relatively small, so that the stress on the adhesive surface is as small as possible. Table 1 shows the main technical properties of three commonly used insulation materials.

Table 1) Table 1 Technical properties of commonly used insulation materials Thermal conductivity iw/mK) Maximum use temperature / C fire performance Rock wool non-burning rigid polyurethane foam Flame retardant EPS polystyrene board flame retardant can be seen from Table 1 above Among these three materials, the rigid polyurethane foam has the lowest density and the lowest thermal conductivity, which is much lower than 0.05WmK. At the same time, the water absorption rate is the lowest among the three materials, and it has better fire resistance and can prevent it. Fuel, can be extinguished when leaving. At the same time, polyurethane hard materials can withstand the great stress changes caused by temperature and humidity changes, and have a good thermal insulation effect. It can also be seen from Table 1 that the temperature of the polyurethane rigid foam on the outer wall surface temperature of the reaction tank cannot exceed 120C. Therefore, if the actual application temperature is lower than 120C, it may be considered to use a rigid polyurethane foam or spray paint for thermal insulation construction. Therefore, when the temperature outside the tank is low, the heat energy in the tank can be prevented from being lost. When the temperature outside the tank is high, the temperature inside the tank can be prevented from rising, thereby facilitating the relatively constant temperature in the reaction tank, which is favorable for the stable fermentation process of the rice wine.

3. Fermentation tank outer wall polyurethane insulation construction process Hard foam polyurethane spraying construction process is to feed the two materials of A material and B material to the spray gun at the set ratio through the A and B feed pumps, after the compressed air is pressurized. The spray gun is sprayed onto the surface of the object to form a layer of insulation. It is widely used and can be directly sprayed, and is not limited by the conditions of the external thermal insulation type and the working surface; the thermal insulation layer formed by spraying is an overall shape without seams. The whole insulation construction process is divided into the following steps. The first is to weld the iron skeleton and install the raft; the second is to remove the rust and antirust paint; then the polyurethane spray coating, the plastic film seal; the final installation of the color steel plate. The specific steps are as follows: First, scribe the sample on the outer wall of the tank to determine the specific position of the angle iron bracket, pay attention to the uniform spacing in all directions, the angle iron frame welding should be firm, and the iron frame should be installed straight. In this way, the raft can be installed more accurately and reliably.

Secondly, the rust on the outer wall of the tank is removed by mechanical means to achieve the standard of no visible grease and dirt on the surface of the steel plate. After the rust is finished, the anti-rust paint should be completed as soon as possible to minimize the exposure time. Before the anti-rust paint is applied, the outer surface of the tank should be kept dry and clean. The thickness of the coating should be uniform during construction, and it should not be leaked or repeatedly painted.

Third, direct spray method construction, first check the operation of spraying machine, air compressor and other equipment; pour the prepared A and B materials into their respective containers, start the pump, carry out material circulation, calibrate the metering pump flow, press A , the proportion of the B material is adjusted; when spraying, the air compressor, the material pump, the air compressor should be adjusted, and the specified pressure should be connected to the spray gun. After the spray of the material pump is fogged, the muzzle is opened. Spraying on the surface of the tank; spraying the thickness of the insulation layer is generally 2cm thick, and the total thickness is more than 2cm, spraying layer by layer until the final insulation thickness is reached. When spraying multiple times, the first layer is the bottom layer. Appropriately increase the proportion of B material to increase the adhesion with the base layer; the compressed air can not be interrupted during the spraying process, and stop the material pump when the construction is intermittent; in general, the spraying sequence first tank top, then the top circle, then from Spray from top to bottom until the bottom plate, after the spraying operation is completed, the material pump should be turned off first, and then the parts of the spray gun should be thoroughly cleaned in acetone.

Fourth, choose to carry out plastic sealing construction in the weather without wind or wind, and keep the plastic film and polyurethane insulation layer closely attached, to prevent defects such as empty drum, discount, damage, etc.; then, install color steel plate, install When the line shape should be straight, prevent deformation from the drum, the seam should be sealed with silicone seal, the screw is installed, and the nut is sealed with silicone.

In the construction process of the insulation layer, we must also pay attention to the following points: First, because the polyurethane spray coating construction is greatly affected by the environment, the environmental factors should be strengthened during the construction process. The ambient temperature of the construction site is not lower than 5C in summer. The sunny day shall not be higher than 35C. If it is used outdoors, the wind shall not be greater than 5; no construction shall be allowed on rainy days. If necessary, use a shelter on the scaffolding to avoid direct sunlight. Second, the polyurethane spray coating construction, the surface of the tank should be dry and clean, no wet marks or miscellaneous technological innovations. 2 Calculation of the bending moment of the rectangular cap: Since the pitch of the tower crane pile is equal to the standard pitch of the tower crane, no bending moment is generated.

2.1.4 Rectangular Cap Section Cross-Shear Calculation The second step of the calculation scheme can obtain the maximum shear force of the XY-direction pile to the rectangular cap. Considering the symmetry, it is recorded as V=2809.063kN. In case, the shear bearing capacity of the oblique section satisfies the following formula: where the meaning is - the shear span ratio of the calculated section, 2 = 1.500; ft - the design value of the tensile strength of the concrete shaft, ft = 1.570 N / inm2; Calculated width at the place, b=4000mm; h0 cap calculates the calculated height at the section, h0=700mm; fy steel bar tensile strength design value, fy=300.000N/imm2; tower crane manufacturer provides S=560mm steel bar spacing To meet the requirements, the following considerations are made to construct the reinforcement.

According to the calculation formula of the second step, the calculation of the bearing capacity of the pile body can be based on the calculation formula of the second step. The design value of the axial pressure of the pile should be satisfied. The following formula: Fc - a pile pile forming process coefficient, take 0.750, fc - concrete axis core resistance calculated to obtain the axial pressure design value of the pile top to meet the requirements, the pressure-reinforcing steel only need to construct reinforcement!

The pile body is subjected to the calculation of the pile body. According to the technical specification of the pile foundation 194-2008, Article 5.8.7: the tensile load capacity is calculated, the maximum tensile force is N=871.636kN. After calculation, the main reinforcement of the tensile steel pile is 12, 18, AS= 3053.63mm2, steel can meet the requirements.

2.1.6 Calculation of bearing capacity of piles According to the provisions of 5.2.5 and 5.3.5 of the Technical Specifications for Building Piles (G94-2008), the axial pressure design of piles can be obtained according to the calculation scheme of the second step. The value, taking the maximum value N=1 404.531kN, the vertical ultimate bearing capacity of the pile should be checked to meet the following formula, the maximum pressure: the vertical bearing capacity characteristic value of the R pile; the vertical bearing capacity characteristic value of Ra single pile; K ——Safety factor, take 1.0; fak—weighted average of eigenvalues ​​of foundation bearing capacity of a pile capping soil—cape effect coefficient: qsk—the standard value of the limit side resistance of the i-layer soil on the pile side, as shown in the following table Value; qpk - a limit value of the ultimate resistance, according to the following table; u - the circumference of the pile, u = 2.513mAp - the end area of ​​the pile, take Ap = 0.5027m2Ac - calculate the net area of ​​the pile corresponding to the pile foundation , Ac=3.50m2; the thickness of the i-th layer of the first layer, as shown in Table 1.3 above; since the depth of the pile is 39m, the pile end is in the 10th layer. The calculation here is the most unfavorable state before the cap is not poured, so the cap effect is not considered. There is also no need to consider the effects of earthquakes.

The maximum pressure of the pile top is 1037.840kN. The R value calculated by the above formula is much larger than the maximum pressure of the pile top, so it meets the requirements.

The calculation of pile uplift capacity is based on Article 5.4.5 of the Technical Standard for Building Piles (G94-2008). The pile uplift capacity should meet the following requirements: Obtained: After calculation, all indicators can meet the requirements, especially in the pile. The calculation of the compressive and uplift bearing capacity is obviously much more than that, so the pile length can be appropriately reduced. It will not be described in detail here.

At present, there are more and more tower crane foundation forms using lattice columns + bored pile foundations at the construction site. However, this basic form cannot be normalized according to the specifications, and the value of the parameters is very important.

Equipment insulation layer flat insulation effect area average thickness insulation before insulation, fermenter outer wall 100m22cm use 3 sets of heaters use 1 set of heaters (on page 152), equipment performance should be intact, work continuous and reliable, construction site Clean and at the same time do a good job of material management to prevent material contamination.

4. Example of polyurethane insulation on the outer wall of fermenter This section takes the insulation of yellow wine fermentation tank in the factory of a yellow wine production enterprise in a certain province and city as an example. The insulation material is hard polyurethane spray. By comparing the heat required before and after the warming of the yellow wine fermenter in winter, the operating temperature in the fermenter is 25 ° C. The specific heat preservation effect is shown in Table 2 below. Table 2 polyurethane spray insulation effect can be seen from Table 2, in the winter rice wine fermenter outer wall before the end of the polyurethane spray insulation needs to open 34 sets of heaters to maintain the temperature inside the tank, use polyurethane spray insulation, just open a group of heaters Therefore, it can save about 2T of steam every day, and the energy saving effect is obvious. At the same time, in the summer, it is also beneficial to maintain the low-temperature fermentation process in the fermenter. From the overall point of view, the use of polyurethane spray insulation on the outer wall of the yellow wine fermenter has a great effect on the temperature of the fermentation temperature during the fermentation of the yellow wine, and has a fixed Economic benefits.

The tank is insulated and insulated, and a large part of the heat in the tank is diffused into the air through the exposed tank wall, so that it is difficult to control the temperature change gently during the cold season in winter or when the temperature difference between the tank and the outside is relatively large. As well as causing huge heat loss, it can be seen from the actual operation process that the outer wall of the rice wine fermentation tank is insulated. In this paper, the fermentation of the yellow wine fermenter is carried out by using polyurethane spray. It can be seen that the polyurethane is sprayed to bring certain economic benefits. In addition, although the construction of the polyurethane spray insulation project is a very professional project, the required construction technology is relatively high, but as long as the design, construction and acceptance are strictly in accordance with the technical specifications of the construction, the ideal insulation effect can be achieved.

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