High-speed screw expander with two-way steam inlet structure

Abstract

The utility model provides a high-speed screw expander with a bidirectional steam inlet structure, which is characterized in that an axial steam inlet is arranged on a steam inlet end seat, a radial air inlet is arranged on a shell, one end of a male screw rotor and one end of a female screw rotor respectively penetrate through a high-pressure dynamic pressure bearing to be contacted with a rolling oil film of the male screw rotor and the female screw rotor, and the high-pressure dynamic pressure bearing is fixed on the steam inlet end seat; the other ends of the male screw rotor and the female screw rotor respectively penetrate through a low-pressure dynamic pressure bearing and are in contact with rolling oil films thereof; a coupler, a shaft end gland, a labyrinth shaft seal, a locking nut, a high-pressure end oil slinger, a main thrust disc, a high-pressure dynamic pressure bearing, an auxiliary thrust disc, a spacer ring, a throttling ring, a high-pressure air floating seal and a sealing piece are sequentially installed on a left end shaft of the male screw rotor from left to right. And so on. The screw expander has the advantages that the energy efficiency is greatly improved, and the energy efficiency can be improved by 55%-75% under the same condition as that of an existing screw expander; 2, the production cost is reduced; and 3, the device has a good recovery effect on waste heat resources under the conditions of small flow (less than 10t / h) and high pressure difference (more than 2.5 Mpa).

Description

Technical Field

[0001] The utility model provides an improved screw expander, in particular to a high-speed screw expander with a bidirectional steam inlet structure. Background Art

[0002] Existing screw expanders have been widely used in waste heat recovery in various industrial fields, and have contributed to the sustainable development of national energy. As far as the development of screw expanders themselves is concerned, there are more than 20 years of history, but there are still many problems in their application, among which the biggest ones are: 1. The isentropic efficiency of existing screw expanders fluctuates widely in the actual operation process, ranging from 20-70%, and most of the average range is around 40-60%. In general, there is still a lot of room for improvement; 2. For waste heat sources under small flow (<10t / h) and high pressure difference (>2.5Mpa), the recovery effect is poor. In response to these problems, many enterprises, scientific research institutions and individuals have proposed various technical improvement plans, some starting from increasing the speed to nearly 5000rpm (very few), some improving the air inlet structure, some starting from the screw profile, and some starting from the rotor diameter size, etc. These improvements have indeed made progress in improving the energy efficiency ratio, but the overall effect is not significant. Most of these improvements are only started from a single technical route, and there are few improvements from the overall system of the screw machine, so the effect is difficult to be significant. Looking at the existing screw machines, most of the structures and structures have not changed much. For example, the steam inlet method is single (axial or radial), and the speed of most screws is still maintained at around 3000rpm. Therefore, if the efficiency of the screw expander is to be significantly improved, it seems difficult to achieve results without a major technological breakthrough. With the country's increasingly high requirements for energy conservation and emission reduction and dual carbon standards for enterprises, how to improve the energy efficiency of screw expanders is an important issue that must be solved as soon as possible by technicians in the field. Summary of the invention

[0003] The main purpose of the utility model is to propose a high-speed screw expander with a two-way steam inlet structure in view of the relatively low energy efficiency of existing screw expanders, which can significantly improve the energy efficiency of the screw expander; the secondary purpose of the utility model is that the technical solution proposed this time also has a good recovery effect on waste heat sources under conditions of small flow rate (<10t / h) and high pressure difference (>2.5Mpa).

[0004] The purpose of the utility model can be achieved through the following technical scheme, a high-speed screw expander with a bidirectional steam inlet structure, which includes a steam inlet end seat, a machine casing, a screw rotor, a front cover, and a rear cover, characterized in that an axial steam inlet is provided on the steam inlet end seat, and a radial air inlet is provided on the machine casing. One end of the male and female screw rotors respectively passes through a high-pressure dynamic pressure bearing to contact with a rolling oil film therewith, and the high-pressure dynamic pressure bearing is fixed on the steam inlet end seat; the other ends of the male and female screw rotors respectively pass through a low-pressure dynamic pressure bearing to contact with a rolling oil film therewith; a coupling, a shaft end pressure cover, a labyrinth shaft seal, a locking nut, a high-pressure end oil slinger, Main thrust plate, high-pressure dynamic pressure bearing, auxiliary thrust plate, spacer ring, throttle ring, high-pressure air flotation seal, and sealing parts; low-pressure air flotation seal, throttle ring, spacer ring, low-pressure dynamic pressure bearing, synchronous gear and shaft end gland are installed on the right end shaft of the male screw rotor from left to right in sequence; main thrust plate, high-pressure dynamic pressure bearing, auxiliary thrust plate, spacer ring, throttle ring, high-pressure air flotation seal, and sealing parts are installed on the left end shaft of the female screw rotor from left to right in sequence; low-pressure air flotation seal, throttle ring, spacer ring, low-pressure dynamic pressure bearing, synchronous gear and shaft end gland are installed on the right end shaft of the female screw rotor from left to right in sequence; the front cover is fixedly connected to the steam inlet end seat, and the rear cover is fixedly connected to the machine casing.

[0005] The position and size of the axial steam inlet and radial air inlet are determined based on the heat source inlet and exhaust steam pressure ratio; the designed internal expansion ratio; the rotation angles of the male and female screws; the rotation centers of the male and female screw rotors; the parameters of the male and female screw tooth bottom arcs, long side segment profiles, screw tooth top arcs, high-pressure side sealing lines and top arc intersection line.

[0006] The male and female screw rotors are 6 / 8 type.

[0007] The beneficial effects of the utility model are:

[0008] 1. The energy efficiency is greatly improved. Compared with the isentropic efficiency of 35%-45% of the existing screw expander under the above background conditions, the isentropic efficiency of the utility model is 60%-72%, which can be increased by 55-75%. This is because the technical solution has made great improvements to the existing screw expander: ⑴, the existing air inlet, which only has one axial or radial air inlet, is changed to two air inlets; ⑵, the speed of the screw expander is greatly improved, from the existing 3000rpm to more than 10000rpm, and the screw rotor structure is optimized to enable it to withstand high speed, which is the main reason; ⑶, the structural construction of the whole machine is optimized, not only in the arrangement and combination of parts, but also in the number of parts and components reduced by about one third compared with the existing screw expander, and many parts have been upgraded; so as to reduce the probability of failure. The overall improvement of these aspects has greatly reduced the leakage loss and mechanical loss of the main engine itself, and improved the efficiency of the main engine. Through the design of non-contact air flotation seal and hydrodynamic bearing, the unit has high speed, thereby reducing the equipment size, increasing the flow capacity of the unit, further reducing leakage loss, and further improving the efficiency of the unit;

[0009] 2. The production cost is reduced. This is mainly because after the speed is increased, the diameter and length of the screw expander shaft can be greatly reduced, making processing equipment resources easier to obtain and processing costs significantly reduced. In addition, the number of parts is reduced by one third, which greatly reduces the size and weight of the whole machine, thereby reducing production, transportation costs and floor space.

[0010] 3. It has a good recovery effect on waste heat resources under conditions of small flow (<10t / h) and high pressure difference (>2.5Mpa). Because the existing screw expander has a single air intake mode and a low speed, when the expansion ratio of the waste heat source is too large or too small, the flow resistance loss and leakage loss account for a large proportion, so the efficiency is very low (generally the isentropic efficiency is only 30-45%); and the utility model has improved the air intake mode and the speed, so it has overcome the shortcomings of the prior art, and can achieve an isentropic efficiency of more than 70% when recovering waste heat sources under conditions of small flow (<10t / h) and high pressure difference (>2.5Mpa).

[0011] The utility model is further described below in conjunction with the accompanying drawings and embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Attached Figure 1 This is a schematic diagram of the main structure of the utility model;

[0013] Attached Figure 2 It is a left-side structural schematic diagram of the utility model;

[0014] Attached Figure 3 For attachment Figure 2 A-A in the middle is an enlarged schematic diagram of the transverse cross-sectional structure;

[0015] Attached Figure 4 For attachment Figure 2 A1-A1 in the middle is an enlarged schematic diagram of the transverse cross-sectional structure;

[0016] Attached Figure 5 For attachment Figure 1 Schematic diagram of the axial cross-section structure at the middle BB;

[0017] Attached Figure 6 For attachment Figure 1 Schematic diagram of the axial cross-section structure at the center CC;

[0018] Attached Figure 7 For attachment Figure 1 Schematic diagram of the transverse cross-section structure at the middle DD;

[0019] Attached Figure 8 For attachment Figure 1 Schematic diagram of the transverse cross-section structure at HH in the middle. DETAILED DESCRIPTION

[0020] It should be noted that the embodiments listed below are only examples of the present technical solution. Other embodiments with the same functions as the present technical solution obtained by those skilled in the art without making any creative work shall all fall within the scope of protection of the present technical solution.

[0021] Example 1, see attached Figure 1 , 2, 3, 4, 5, 6, 7, 8, a high-speed screw expander with a two-way steam inlet structure, which consists of a steam inlet end seat 1, a machine casing 2, a male screw rotor 3, a female screw rotor 4, a front cover 5, a rear cover 6, an axial steam inlet 7, a high-pressure air flotation seal 8, and a high-pressure dynamic pressure bearing 9; a radial steam inlet 10, an exhaust port 11, an expansion chamber 12, a low-pressure air flotation seal 13, a low-pressure dynamic pressure bearing 14, a synchronous gear 15, a shaft end gland 16, a seal 17, a labyrinth shaft seal 18, a spacer ring 19, a throttle ring 20, an auxiliary thrust plate 21, a locking nut 22, a main thrust plate 23, a high-pressure end oil slinger 24, a coupling 25, a synchronous gear oil supply pipe 26, and an air inlet 27. Its connection structure is: the steam inlet end seat 1 is connected to the machine casing 2 by bolts. The front cover 5 is fixed to the steam inlet end seat 1 by bolts. The rear cover 6 is fixed to the machine casing 2 by bolts. The high-pressure dynamic pressure bearing 9 is fixed to the steam inlet end seat 1 by bolts. The low-pressure dynamic pressure bearing 14 is fixed to the casing 2 by bolts. The shafts at both ends of the male screw rotor 3 and the female screw rotor 4 pass through the high-pressure dynamic pressure bearing 9 and the low-pressure dynamic pressure bearing 14 respectively, contact with the rolling oil film and play a supporting role. The left end of the male screw rotor 3 is connected to the coupling 25, and the shaft end pressure cover 16 is bolted to the left end face of the male screw rotor 3. The labyrinth shaft seal 18, the locking nut 22, the high-pressure end oil slinger 24, the main thrust plate 23, the high-pressure dynamic pressure bearing 9, the auxiliary thrust plate 21, the spacer ring 19, the high-pressure air flotation seal 8, and the seal 17 are installed on the left end shaft of the male screw rotor 3 from left to right; the low-pressure air flotation seal 13, the spacer ring 19, the low-pressure dynamic pressure bearing 14, the synchronous gear 15 and the shaft end pressure cover 16 are installed on the right end shaft of the male screw rotor 3 from left to right. The left end shaft of the female screw rotor 4 is equipped with a main thrust plate 23, a high-pressure dynamic pressure bearing 9, a secondary thrust plate 21, a spacer ring 19, a high-pressure air flotation seal 8, and a seal 17 in sequence from left to right; the right end shaft of the female screw rotor 4 is equipped with a low-pressure air flotation seal 13, a spacer ring 19, a low-pressure dynamic pressure bearing 14, a synchronous gear 15, and a shaft end gland 16 in sequence from left to right. The synchronous gear oil supply pipe 26 is fixed on the rear cover 6. The high-pressure air flotation seal 8 and the low-pressure air flotation seal 13 are built with a multi-stage throttling ring 20;

[0022] The steam inlet end seat 1 is provided with an axial air inlet 7, the casing 2 is provided with a radial air inlet 10, and the upper end of the casing 2 is an air inlet 27. After the airflow enters the cavity between the steam inlet end seat 1 and the casing 2, it is divided into two branches, one of which enters the expansion chamber 12 from the axial air inlet 7 to do work, and the other enters the expansion chamber 12 from the radial air inlet 10 to do work. The cross-sectional area of ​​the axial steam inlet 7 is 6736.1523mm 2 , radial steam inlet 10 space cross-sectional area 1137.9525mm 2(The position and spatial cross-sectional area of ​​the axial steam inlet 7 and the radial steam inlet 10 are mainly determined by the inlet and exhaust pressure ratio of the heat source; the parameters of the design internal expansion ratio; the rotation angles of the male and female screws, the rotation center (axis) of the screw rotor, the male and female screw tooth bottom arcs, the long side segment profile, the screw tooth top arc, the high-pressure side sealing line and the top arc intersection edge and other profile parameters;); the rotation angle of the male screw rotor 3 is 67.8°, and the rotation angle of the female screw rotor 4 is 105.25°.

[0023] The effects of this embodiment are shown in Table 1.

[0024] Example 2, see attached Figure 1 , 2 , 3, 4, 5, 6, 7, 8, a high-speed screw expander with a two-way steam inlet structure, which consists of a steam inlet end seat 1, a machine casing 2, a male screw rotor 3, a female screw rotor 4, a front cover 5, a rear cover 6, an axial steam inlet 7, a high-pressure air flotation seal 8, and a high-pressure dynamic pressure bearing 9; a radial steam inlet 10, an exhaust port 11, an expansion chamber 12, a low-pressure air flotation seal 13, a low-pressure dynamic pressure bearing 14, a synchronous gear 15, a shaft end gland 16, a seal 17, a labyrinth shaft seal 18, a spacer ring 19, a throttle ring 20, an auxiliary thrust plate 21, a locking nut 22, a main thrust plate 23, a high-pressure end oil slinger 24, a coupling 25, a synchronous gear oil supply pipe 26, and an air inlet 27. Its connection structure is: the steam inlet end seat 1 is connected to the machine casing 2 by bolts. The front cover 5 is fixed to the steam inlet end seat 1 by bolts. The rear cover 6 is fixed to the machine casing 2 by bolts. The high-pressure dynamic pressure bearing 9 is fixed to the steam inlet end seat 1 by bolts. The low-pressure dynamic pressure bearing 14 is fixed to the casing 2 by bolts. The shafts at both ends of the male screw rotor 3 and the female screw rotor 4 pass through the high-pressure dynamic pressure bearing 9 and the low-pressure dynamic pressure bearing 14 respectively, contact with the rolling oil film and play a supporting role. The left end of the male screw rotor 3 is connected to the coupling 25, and the shaft end pressure cover 16 is connected to the left end face screw of the male screw rotor 3. The labyrinth shaft seal 18, the locking nut 22, the high-pressure end oil slinger 24, the main thrust plate 23, the high-pressure dynamic pressure bearing 9, the auxiliary thrust plate 21, the spacer ring 19, the high-pressure air flotation seal 8, and the seal 17 are installed on the left end shaft of the male screw rotor 3 from left to right; the low-pressure air flotation seal 13, the spacer ring 19, the low-pressure dynamic pressure bearing 14, the synchronous gear 15 and the shaft end pressure cover 16 are installed on the right end shaft of the male screw rotor 3 from left to right. The left end shaft of the female screw rotor 4 is equipped with a main thrust plate 23, a high-pressure dynamic pressure bearing 9, a secondary thrust plate 21, a spacer ring 19, a high-pressure air flotation seal 8, and a seal 17 in sequence from left to right; the right end shaft of the female screw rotor 4 is equipped with a low-pressure air flotation seal 13, a spacer ring 19, a low-pressure dynamic pressure bearing 14, a synchronous gear 15, and a shaft end gland 16 in sequence from left to right. The synchronous gear oil supply pipe 26 is fixed on the rear cover 6. The high-pressure air flotation seal 8 and the low-pressure air flotation seal 13 are built with a multi-stage throttling ring 20;

[0025] An axial air inlet 7 is provided on the steam inlet end seat 1, a radial steam inlet 10 is provided on the casing 2, and an air inlet 27 is provided at the upper end of the casing 2. After the intake air flow enters the cavity between the steam inlet end seat 1 and the casing 2, the air flow is divided into two branches, one branch enters the expansion chamber 12 from the axial air inlet 7 to perform work, and the other branch enters the expansion chamber 12 from the radial steam inlet 10 to perform work. The axial steam inlet space cross-sectional area is 11311.9mm2, and the radial steam inlet space cross-sectional area is 2126.8mm2 (the position and space cross-sectional area of ​​the axial steam inlet and radial steam inlet are mainly determined by the heat source inlet and exhaust steam pressure ratio; the design parameters of the internal expansion ratio; the angles of the male and female screws, the rotation center (axis) of the screw rotor, the male and female screw tooth bottom arcs, the long side segment profile, the screw tooth top arc, the high-pressure side sealing line and the top arc intersection edge and other profile parameters;); the male screw rotor 3 has a rotation angle of 67°, the female screw rotor 4 has a rotation angle of 95.25°,

[0026] The effects of this embodiment are shown in Table 1.

[0027] Example 3, see attached Figure 1 , 2, 3, 4, 5, 6, 7, 8, a high-speed screw expander with a two-way steam inlet structure, which consists of a steam inlet end seat 1, a machine casing 2, a male screw rotor 3, a female screw rotor 4, a front cover 5, a rear cover 6, an axial steam inlet 7, a high-pressure air flotation seal 8, and a high-pressure dynamic pressure bearing 9; a radial steam inlet 10, an exhaust port 11, an expansion chamber 12, a low-pressure air flotation seal 13, a low-pressure dynamic pressure bearing 14, a synchronous gear 15, a shaft end gland 16, a seal 17, a labyrinth shaft seal 18, a spacer ring 19, a throttle ring 20, an auxiliary thrust plate 21, a locking nut 22, a main thrust plate 23, a high-pressure end oil slinger 24, a coupling 25, a synchronous gear oil supply pipe 26, and an air inlet 27. Its connection structure is: the steam inlet end seat 1 is connected to the machine casing 2 by bolts. The front cover 5 is fixed to the steam inlet end seat 1 by bolts. The rear cover 6 is fixed to the machine casing 2 by bolts. The high-pressure dynamic pressure bearing 9 is fixed to the steam inlet end seat 1 by bolts. The low-pressure dynamic pressure bearing 14 is fixed to the casing 2 by bolts. The shafts at both ends of the male screw rotor 3 and the female screw rotor 4 pass through the high-pressure dynamic pressure bearing 9 and the low-pressure dynamic pressure bearing 14 respectively, contact with the rolling oil film and play a supporting role. The left end of the male screw rotor 3 is connected to the coupling 25, and the shaft end pressure cover 16 is bolted to the left end face of the male screw rotor 3. The labyrinth shaft seal 18, the locking nut 22, the high-pressure end oil slinger 24, the main thrust plate 23, the high-pressure dynamic pressure bearing 9, the auxiliary thrust plate 21, the spacer ring 19, the high-pressure air flotation seal 8, and the seal 17 are installed on the left end shaft of the male screw rotor 3 from left to right; the low-pressure air flotation seal 13, the spacer ring 19, the low-pressure dynamic pressure bearing 14, the synchronous gear 15 and the shaft end pressure cover 16 are installed on the right end shaft of the male screw rotor 3 from left to right. The left end shaft of the female screw rotor 4 is equipped with a main thrust plate 23, a high-pressure dynamic pressure bearing 9, a secondary thrust plate 21, a spacer ring 19, a high-pressure air flotation seal 8, and a seal 17 in sequence from left to right; the right end shaft of the female screw rotor 4 is equipped with a low-pressure air flotation seal 13, a spacer ring 19, a low-pressure dynamic pressure bearing 14, a synchronous gear 15, and a shaft end gland 16 in sequence from left to right. The synchronous gear oil supply pipe 26 is fixed on the rear cover 6. The high-pressure air flotation seal 8 and the low-pressure air flotation seal 13 are built with a multi-stage throttling ring 20;

[0028] An axial air inlet 7 is provided on the steam inlet end seat 1, a radial steam inlet 10 is provided on the casing 2, and an air inlet 27 is provided at the upper end of the casing 2. After the intake air flow enters the cavity between the steam inlet end seat 1 and the casing 2, the air flow is divided into two branches, one branch enters the expansion chamber 12 from the axial air inlet 7 to perform work, and the other branch enters the expansion chamber 12 from the radial steam inlet 10 to perform work. The spatial cross-sectional area of ​​the axial steam inlet is 11311.9mm2, and the spatial cross-sectional area of ​​the radial steam inlet is 2126.8mm2 (the position and spatial cross-sectional area of ​​the axial steam inlet and radial steam inlet are mainly determined by the inlet and exhaust pressure ratio of the heat source; the parameters of the design internal expansion ratio; the rotation angles of the male and female screws, the rotation center (axis) of the screw rotor, the bottom arc of the male and female screw teeth, the long side segment profile, the screw tooth top arc, the high-pressure side sealing line and the top arc intersection edge and other profile parameters;); the rotation angle of the male screw rotor 3 is 67°, and the rotation angle of the female screw rotor 4 is 95.25°.

[0029] The effects of this embodiment are shown in Table 1.

[0030] Table 1: Comparison of the three embodiments with the existing low-speed screw expander.

[0031]

Claims

1. A high-speed screw expander with a bidirectional steam inlet structure, comprising a steam inlet end seat, a casing, a screw rotor, a front cover, and a rear cover, characterized in that: An axial steam inlet is arranged on the steam inlet end seat, and a radial air inlet is arranged on the casing. One end of the male and female screw rotors passes through the high-pressure dynamic pressure bearings to contact with the rolling oil film, and the high-pressure dynamic pressure bearings are fixed on the steam inlet end seat; the other ends of the male and female screw rotors pass through the low-pressure dynamic pressure bearings to contact with the rolling oil film; the left end shaft of the male screw rotor is equipped with a coupling, a shaft end gland, a labyrinth shaft seal, a locking nut, a high-pressure end oil slinger, a main thrust plate, a high-pressure dynamic pressure bearing, an auxiliary thrust plate, a spacer ring, a throttle ring, a high-pressure air flotation seal, a seal, etc. from left to right. Seals; The right end shaft of the male screw rotor is equipped with low-pressure air flotation seal, throttling ring, spacer ring, low-pressure dynamic pressure bearing, synchronous gear and shaft end pressure cover from left to right; The left end shaft of the female screw rotor is equipped with main thrust plate, high-pressure dynamic pressure bearing, auxiliary thrust plate, spacer ring, throttling ring, high-pressure air flotation seal and seals from left to right; The right end shaft of the female screw rotor is equipped with low-pressure air flotation seal, throttling ring, spacer ring, low-pressure dynamic pressure bearing, synchronous gear and shaft end pressure cover from left to right; The front cover is fixedly connected to the steam inlet end seat, and the rear cover is fixedly connected to the machine casing.

2. The high-speed screw expander with a bidirectional steam inlet structure according to claim 1, characterized in that: The position and size of the axial steam inlet and radial air inlet are determined based on the following parameters: the heat source inlet and exhaust steam pressure ratio; the designed internal expansion ratio; the rotation angles of the male and female screws; the rotation centers of the male and female screw rotors; the bottom arcs of the female and male screw teeth, the long side profiles, the top arcs of the screw teeth, the high-pressure side sealing lines and the intersection lines of the top arcs.

3. The high-speed screw expander with a bidirectional steam inlet structure according to claim 1 or 2, characterized in that: The male and female screw rotors are 6 / 8 type.

Images