Abstract: The spiral wound heat exchangers used in domestic hot water system energy savings generated by the project significantly, analysis of this example to illustrate the application, to be the way to save energy.

Keywords: hot water heat exchanger, spiral wound energy Catic Hotel

At present, domestic hot water steam heat exchangers used in heat transfer coefficient is generally 2000 ~ 5000w / ㎡ · ℃ with plate heat exchanger, the most common. I use a variety of common spiral wound heat exchanger and the heat transfer performance of heat exchangers to be compared, with reference to engineering practice, through the heat exchangers used in domestic hot water system, demonstrating for energy conservation, efficiency a new approach.

For a long time, shell and tube heat exchangers are widely used in domestic hot water systems are, but because of its bulky, heat is not sufficient, condensed water discharge high temperature and other reasons, in recent years, domestic hot water systems are most used plate heat exchanger as its alternative. However, domestic hot water plate heat exchanger used in the steam temperature system still exists, the pressure is not too high, short life, maintain certain limitations and shortcomings of its water requirements. The spiral wound heat exchanger because of its high heat transfer coefficient, can withstand the high steam pressure and steam heat exchanger length is longer, in the domestic hot water heat exchanger applications with great advantage.

Fundamentals

As shown, due to the heat exchanger tubes using an efficient internal and external structural characteristics of two-winding thread, used in domestic hot water system, including pipe thread wall so that the steam is fully condensed, particularly the effect of enhanced heat transfer significant. Shell and tube heat transfer cross-flow mode, the port temperature is small, the initial rapid temperature rise and heating to achieve a very short time, suitable for heating domestic hot water system, variable flow heat sterilization and the flow state . All-welded structure makes its temperature and pressure to meet the domestic hot water heat exchanger system, without further temperature and pressure reduction devices installed. As the heat of the refrigerant as hot water, the steam side exit is generally below 60 ℃, suitable working conditions, the steam side exit may set traps.

Project

Catic Hotel is opened in 1995, has 367 rooms, a three-star hotel, located in the quiet environment, trade-studded Asian Games Village. The original volume of heat exchanger system, covers an area of ​​about 80 square meters in 2006, imports of efficient transformation of spiral screw heat exchanger and heat transfer not only after energy efficiency has been greatly improved, and the heat exchanger size is the original heat exchanger volume of 1 / 10, room design compact, saving valuable floor space.
 
Here is the project used three sets of heat exchangers briefing:

1, the high area: 0.6MPa saturated steam, 60 / 4 degrees, 9.8t / h, heat transfer area of ​​4 square meters, installation dimensions (H × W) 1510mm × 204mm, 2 sets

2, in the area: 0.6Mpa saturated steam, 60 / 4 degrees, 16.8t / h, heat transfer area of ​​5.9 square meters, installation dimensions (H × W) 1492mm × 206mm, 2 sets

3, the lower zone: 0.6Mpa saturated steam, 60 / 4 degrees, 10.8t / h, heat transfer area of ​​4 square meters, installation dimensions (H × W) 1510mm × 204mm, 2 sets





Spiral wound heat exchangers used in the project than the original volume heat exchanger found that the condensation temperature can be controlled at a lower level, to ensure full condensation of steam, and without going through the second heat, save a lot of steam; original There are volumetric heat exchanger cleaning service once every six months to be scale, after using the heat exchanger to achieve a high flow rate, temperature gradient is small, dirt coefficient of the system characteristics, fouling tendency was significantly reduced. Heat transfer coefficient reflects the level of heat exchanger performance is superior or not, applied to the domestic hot water system, spiral wound heat exchangers, heat transfer coefficient can be up to 8000w / ㎡. ℃ or so, the original volume of heat exchanger heat transfer coefficient is only 2000-3000 w / m. ℃ or so, assuming installation of plate heat exchanger heat transfer coefficient is only 3000-5000 w / m. ℃.

The domestic hot water applications, the use of spiral wound heat exchangers Owen (OWEN) principle of turbulence buffeting frequency standards, using the minimum clearance Tube bundle design, effectively eliminating the turbulence buffeting phenomenon, extending the life of the heat exchanger. Its design life of up to 40 years, the average domestic heat exchanger only 15 years.

The heat exchanger temperature, high pressure, due to its beams and tubes used in all stainless steel shell, with a uniform coefficient of expansion, not because of pressure and temperature instability of deformation caused by heat; heat exchanger temperature , high pressure, temperature and pressure reduction devices without the need both to save the initial investment costs, but also avoiding the vacuum caused by temperature waste heat of steam; internal structure designed with sound resonance, and effectively inhibited the phenomenon of acoustic vibrations, the maximum limits restrict the operation noise, heat exchangers running almost no noise, and the original heat exchanger at 70dB above the noise level.

Catic Hotel replacement heat exchanger, according to a large number of such heat exchanger according to engineering experience, the heat exchanger heat exchanger for the average domestic consumption of steam 90%, or about 10% energy saving. Catic Plaza Hotel to the actual operation of the heat transfer conditions, for example, we calculate the following characteristics:

Domestic hot water heat exchanger unit: the average domestic consumption of steam heat exchanger is about 0.85t / (t · hot water), Catic Plaza Hotel to 60t calculate the average daily water consumption of steam 0.85 × 60 = 51t / (t · day domestic hot water), the consumption of steam heat exchanger is about 0.76t / (t · hot water), heat exchanger than the domestic savings of 10% to an average of Catic Plaza Hotel 60t calculated daily consumption of water Steam 0.76 × 60 = 45.6t / (t · day hot water), a total saving of steam 5.4t / day. According to the daily running 24h, 365 days a year, then about a year to save steam: 5.4t / day × 365 = 1971t. Therefore, according to the current steam price 200 yuan / t meter, the device is running about a year to save money 200 yuan / t × 1971t = 394200.00 yuan.

Picture this topic are as follows:






Spiral wound heat exchangers and plate heat exchanger, a comprehensive comparison
1, plate heat exchanger gasket material determine its application is limited in a variety of conditions: temperature of the current general domestic gasket (critical temperature), tincture of nitrile rubber 110 ℃, 160 ℃ EPDM , fluorine rubber, 175 ℃, some of the imported rubber gasket temperature up to 265 ℃, but the price is expensive. The screw thread imported shell and tubes heat exchanger bundles all-stainless steel welding production, no gasket, the working pressure 1.6MPa, highest working temperature of up to 400 ℃.

2, plate heat exchanger used in high temperature and pressure of the steam - water heat conditions, the sealing gasket and easy to aging, the frequent need to remove, replace gaskets, high maintenance costs. The import of highly efficient heat exchanger itself during operation without maintenance and cleaning simple and low cost.

3, threaded screw heat exchanger at a high temperature, high pressure steam conditions, is even more evident advantages, the general board for the restrictions; for water - water heat exchanger such as symmetry conditions, the board for a more competitive advantage.

4, plate heat exchanger plate spacing is only 2-3mm, easy plug and the internal heat exchanger diversion trough structure complex, slow water flow rate of fouling tendency; and because the plate heat exchanger gasket sealing reasons, the heat exchanger fouling or clogging after chemical cleaning can not only clean the board removed the piece; in damage not only easy to disassemble and clean the sealing plate, resulting in increased cleaning costs, but also because of manual cleaning, resulting in heat exchanger plate The damage to the film surface, resulting in pitting corrosion, affecting the life of the heat exchanger.

The import of highly efficient heat exchanger 100 ° connection and screw thread structure, a unique surface treatment technology and media on both sides of the countercurrent heat exchanger to achieve a high flow rate, temperature gradient is small, dirt coefficient characteristics, low fouling tendency.
     Even after scaling phenomenon long-term use can also be used quickly descaling chemical cleaning methods, saving time, effort, low cost, good effect.

5, spiral thread an integrated heat exchanger heat transfer coefficient is high, the heat transfer effect.

The types of heat exchangers and other heat exchanger cost

In order to adapt to high temperature steam heat exchange system in the non-symmetric flow conditions, this new type of high temperature, high pressure screw threaded tube heat exchanger with advanced production technology, the use of spiral wound reverse threaded pipe, and enhance the fluid turbulence effect, the heat transfer coefficient of up to 14000w / ㎡ · ℃, 400 ℃ and can withstand high temperature steam. (The following is based on 0.6MPa saturated steam, with 4 million square meters of residents to compare the heating)

Species

Comparison Project
 Spiral wound heat exchanger
 Assembled imported

Plate heat exchanger
 Shell and tube heat exchanger coil floating
 Remarks
 

 
Equipment investment (million)
 6.76
 5.96
 5.66
 
 
Life
 40 years
 12 years
 20 years
 
 
Average annual investment in equipment (million)
 0.19
 1.15
 0.59
 Annual cost of equipment
 
12-year cumulative investment in equipment (million)
 2.28
 13.59
 6.99
 For comparison, the 12-year
 
Cleaning and maintenance costs (dollars / year)
 200
 5960 +400
 3000
 Replacement parts, cleaning
 
Area
 Dimensions (mm)
 ¢ 273 × 1031
 1205 × 500 × 1655
 ¢ 700 * 2247
 
 
Maintenance space (m2)
 0.4
 2.0
 3.24
 
 
Equipment and materials
 Full stainless steel welding
 Steel frame, stainless steel plate
 Carbon steel shell, copper
 
 
Installation and construction
 Manual operation

2 people, 1 hours
 Crane operation

4 people, 2 hours
 Crane operation

5 2 hours
 
 
Weight (kg)
 77.5
 880
 2900
 
 
Heat transfer coefficient (w/m2.k)
 10024
 3035
 3678
 
 
Design Principles
 Asymmetric flow design
 Symmetrical flow design
 Asymmetric design
 
 
Degree of temperature (℃)
 400
 150
 180
 
 


Conclusion

Catic Plaza through the hot water within the wine with the actual operation of the spiral wound heat exchanger found: that the hot water heat control system, the spiral wound heat exchanger because of its high heat transfer coefficient, area small size, more suitable for high temperature and pressure systems, etc., compare the use of volumetric heat exchanger operation saves a lot of steam energy.