JP5765862B2 - Low pressure steam recycling equipment - Google Patents

Description

  The present invention relates to a low-pressure steam recycling apparatus for supplying low-pressure steam generated from hot water (drain) of 100 ° C. or less discharged from a steam use process to a steam line.

  Hot water of 100 ° C. or less discharged from the steam utilization process is limited to uses such as preheating boiler heating and heating, but most of them are released without being used.

  Incidentally, a part of the steam that has been used as a heat medium and has lost its latent heat is condensed to become hot water of high temperature and pressure. If the hot water is collected and introduced into a flash tank, compressed by a compressor and reused as flash heat and hot water as a heat medium, the pressure can be used at low cost with less energy than when steam is newly obtained from water. It is known that it can be regenerated to steam.

  Examples of the vapor compressor include a reciprocating compressor, a rotary compressor, and a screw compressor. For example, Patent Document 1 includes a horizontally disposed cylinder, a rotor that rotates in the cylinder, and a liquid sealing medium that is accommodated in the cylinder. The rotor is attached to a conical rotor shaft. There is disclosed a screw-type steam compressor having a structure in which a pitch is gradually reduced from a steam suction side to a discharge side.

  In Patent Document 2, surplus steam that is supplied to a steam turbine and a process demand from a high-pressure steam line and an intermediate-pressure steam line installed in the factory, respectively, and extracted from the high-pressure steam line or the medium- and low-pressure steam line. The surplus steam is effectively used by heating it using a heat exchanger using the steam as a heating medium, and supplying it to the steam turbine in the temperature range of about 150 to 260 ° C. by changing to 3 to 8 kgf / cm 2 G of heated steam. Is disclosed.

  The screw-type steam compressor and the turbine-type steam compressor cannot be used at a temperature of 100 ° C. or lower, that is, at atmospheric pressure or lower because of their structure, so that their use as a steam compressor is limited. For this reason, there has been a demand for the development and appearance of a method and apparatus for generating and using low-pressure steam from 100 ° C. or less hot water to be disposed of.

Japanese Patent Laid-Open No. 8-312553 JP 2005-282512 A

  An object of the present invention is to provide a low-pressure steam apparatus having a simple structure and low in equipment cost that enables low-pressure steam to be generated from hot water of 100 ° C. or less that is discarded without being used.

In order to achieve the above object, the invention according to claim 1 stores hot water discharged from a steam utilization process in a sealed tank, connects the sealed tank and a suction side of a roots-type blower , and the roots type the discharge side of the blower is connected to the steam line, by the operation of the Roots-type blower, the low pressure steam generating said sealed tank by vacuum, re-use of low-pressure steam which is configured to supply to the steam line A device,
About the axis of Roots rotor of the Roots-type blower, a position back a predetermined angle to the suction side from the discharge side of the casing surrounding the Roots rotor of the Roots-type blower, an indoor hot water of the fine particles to be retained in the closed tank It is characterized in that a nozzle for spraying is provided.

(Invention of Claim 1)
According to this low-pressure steam reuse device, steam can be reused by converting hot water of 100 ° C. or less that has been discharged without being used into low-pressure steam by a steam compressor. In addition, since the apparatus has a simple structure, maintenance is easy and equipment costs are low.

  By spraying hot water at a location close to the discharge side of the casing, the liquefaction phenomenon caused by mixing with the sucked steam is avoided, so that the Roots rotor rotates smoothly and drains downstream of the Roots-type blower. There is no need to install traps. In addition, it is possible to prevent overheating of the machine parts around the roots rotor and the casing by spraying fine particles of hot water stored and supplied from the nozzles in the sealed tank into the room.

Configuration diagram of low-pressure steam recycling apparatus according to the present invention Front view of Roots-type blower used in the device of the present invention Side view of the roots blower Graph showing the relationship between steam flow rate and compression ratio in Roots-type blowers Graph showing the relationship between power and differential pressure in roots-type blowers

  The best mode of the present invention will be described below with reference to the drawings.

  In FIG. 1, the low-pressure steam reuse device A according to the present invention is configured to correspond to a portion surrounded by an alternate long and short dash line on the downstream side of the steam utilization process.

  On the steam utilization process side, a steam generating boiler 1 and a plurality of processes 5 utilizing the steam are connected by pipes 2, and a steam trap 6 and a sealed tank 15 provided on the outlet side of each process 5, respectively. Are connected by a pipe 14. Reference numeral 3 denotes a pressure reducing valve interposed in the pipe 2. The capacity of the hot water discharged from each process 5 and stored in the sealed tank 15 is detected by a level sensor 16 installed in the tank 15, and a water supply tank 9 connected to the boiler 1 by a pipe 7 as necessary. It is provided so that it may be supplied by operating the hot water recovery pump 11. 8 is a water supply pump interposed in the pipe 7. An electromagnetic valve 12 is interposed in the conduit 10 connecting the sealed tank 15 and the hot water recovery pump 11.

  The closed tank 15 and the suction side of a roots blower 31 as a steam compressor are connected by a pipe 19, and the discharge side of the roots blower 31 is connected to one end of a steam line (steam line) 60. Reference numeral 20 denotes a pressure sensor interposed in the pipe 19. The other end of the steam line 60 is connected to the pipe 2 corresponding to the inlet side of each process 5. Reference numeral 61 denotes a temperature sensor interposed in the steam line 60.

  Reference numeral 22 denotes a motor that drives the Roots-type blower 31, and reference numeral 23 denotes an inverter control device that controls the rotational speed of the motor 20 based on data on the degree of vacuum detected by the pressure sensor 20. Reference numeral 55 denotes a nozzle for spraying fine particles of hot water stored in the sealed tank 15 into the chamber (r) of the roots-type blower 31 described later by the operation of the water supply pump 27. An electromagnetic valve 28 is interposed in the pipe 26 connecting the sealed tank 15 and the water supply pump 27. The electromagnetic valve 28 is provided so as to be able to adjust the steam temperature on the discharge side of the Roots blower 31 by being opened and closed based on a command from the temperature sensor 61.

  Note that the installation location of the nozzle 55 will be described in the description of the structure of the Roots-type blower 31.

  2 and 3, the Roots-type blower 31 includes a rotor shaft 40 by a bearing 39 provided in housings 35 and 36 in which three-leaf root rotors 41 and 41 are accommodated in a casing 32 and attached to the left and right sides of the casing 32. Are provided to be supported respectively.

  32 a is a suction port provided in the casing 32, and 32 b is a discharge port provided in the casing 32. A jacket 33 is provided at an appropriate position of the casing 32 to circulate hot water and prevent overheating due to the operation of the roots blower 31. Further, as shown in FIG. 2, the air is stored and supplied in the sealed tank 15 at a predetermined angle, i.e., 80 degrees, from the discharge side of the casing 32 to the suction side around the axis (o) of the roots rotor 41. A nozzle 55 for spraying fine particles of hot water into the chamber (r) is provided.

  A shaft sealing portion 42 is provided in the center hole 37 formed in the left housing 35. Reference numeral 45 denotes a plurality of (herein, two) dry Teflon (registered trademark) seals mounted in the center hole 37 so that the inner edge 45a contacts the ring 43 fitted to the rotor shaft 40.

  Steam that leaks from the root rotor 41 side to the center hole 37 during the operation of the roots blower 31 is collected from a drain hole 38 that is formed so as to communicate with the center hole 37, thereby preventing entry to the bearing 39 side. It is provided to do.

  Since the right housing 36 has the same configuration as that of the left shaft seal portion 42, the description is omitted for the sake of convenience, and the same reference numerals are given to the drawing of FIG. 3.

  In addition, when there is a concern about corrosion due to steam with respect to the casing 32 and the housings 35 and 36, the austenitic spheroidal graphite cast iron material having a corrosion resistance equivalent to that of a commonly used stainless steel material and a low thermal expansion coefficient (for example, Niresist D5) can be employed.

  48 is a seal case attached to the housing 35, and 49 is a pulley fixed to the left end of the rotor shaft 40. A timing gear 51 is fixed to the right end of the rotor shaft 40, and a gear cover 52 is attached to the housing 36.

  Thus, by operating the Roots-type blower 31, low-pressure steam is generated by depressurizing the inside of the sealed tank 15 in which hot water discharged from the steam utilization process 5 is stored, and the low-pressure steam is supplied to the steam line 60. A low-pressure steam recycling apparatus A is configured.

  About the effect | action of the low-pressure-steam reuse apparatus A which concerns on this invention, since it touched in description of each structure, description is abbreviate | omitted.

(Experiment)
An experiment was conducted on the low-pressure steam recycling apparatus A according to the present invention, and the characteristics of a roots blower used as a steam compressor were examined. The experimental results are shown in the graphs of FIGS.
Roots type blower Diameter: 40mm
Rotation speed: 2000rpm
Motor power: 7.5kW
Steam temperature: 120 ° C (using warm water of 80 ° C)
Spray amount from nozzle: 75 ml / min

  As a result of the experiment, a larger amount of steam was obtained than the value converted from the amount of air into the amount of steam. This is considered to be because the volumetric efficiency was improved because the specific volume was increased by the superheated steam. Furthermore, it is considered that the re-evaporation was efficiently performed by spraying warm water into the room of the roots type blower in order to prevent the generation of superheated steam. Further, as shown in FIG. 5, it was confirmed that there was almost no difference in power between the actual measurement value with steam and the characteristic value with air.

  In addition, in FIG. 4, the value converted into the steam flow rate from the measured air flow rate is represented in the graph as “blower equivalent steam flow rate”. The conversion formula and calculation example used for the conversion are shown below.

(Calculation example)
The example of calculation in compression ratio 2.46 is shown.
Suction pressure: 57.3 kPA
Discharge pressure: 141.3kPA
Compression ratio: 2.46
Theoretical air volume: 2.128 m3 / min
Rotation speed: 2000rpm
Actual air volume: 1.18m3 / min
Gas molecular weight: 18
Air molecular weight: 29

  By substituting the above numerical values into Equation 1, a gas amount of 0.92 (m3 / min) is obtained. The numerical value and the actually measured air amount are displayed in the graph of FIG. For other compression ratios, the gas amount was obtained by the same calculation method and plotted on a graph.

A ... Reuse apparatus 5 for low-pressure steam according to the present invention ... Process 15 ... Sealed tank 20 ... Pressure sensor 22 ... Motor 31 ... Roots type blower (steam compressor)
32 ... Casing 33 ... Jacket 41 ... Roots rotor 55 ... Nozzle 60 ... Steam line

Claims (1)

The hot water discharged from the steam utilization processes accumulated in a closed tank, as well as connects the suction side of the closed tank and Roots-type blower, the discharge side of the Roots-type blower is connected to the steam line, the Roots-type blower the operation, the low pressure steam generating said sealed tank by vacuum and a recycling apparatus of a low pressure steam which is configured to supply to the steam line,
About the axis of Roots rotor of the Roots-type blower, a position back a predetermined angle to the suction side from the discharge side of the casing surrounding the Roots rotor of the Roots-type blower, an indoor hot water of the fine particles to be retained in the closed tank A low-pressure steam recycling apparatus, characterized in that a nozzle for spraying is provided.

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