Recycling system for byproduct low-pressure steam in ethylene glycol production process

Abstract

The utility model belongs to the technical field of steam utilization, and relates to a recycling system for byproduct low and low pressure steam in an ethylene glycol production process, which comprises a steam pocket, a low and low pressure steam compressor, a low pressure steam pipe network, a condensate pipe network and a heater, the output end of the steam pocket is communicated with a condensate pipe network through a low-low pressure steam compressor and a heater; and the low-pressure steam pipe network is communicated with the low-pressure steam compressor. According to the utility model, the byproduct low-pressure and low-pressure steam in the ethylene glycol production process can be recycled and reutilized, so that the purposes of energy conservation, emission reduction and consumption reduction are achieved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to steam utilization technical field relates to a kind of by-product low low-pressure steam recycling system in ethylene glycol production process. BACKGROUND

[0002] Ethylene glycol is an important chemical raw material, in the production process of synthetic gas to ethylene glycol, the carbonylation reaction of oxalic acid dimethyl ester DMO synthesis process is strong continuous heat release process, the synthesis reactor of carbonylation reaction generally uses fixed bed reactor of tube bundle, catalyst is filled in the tube bundle, shell side medium is drum feed water;Boiler feed water enters the shell side of fixed bed reactor of tube bundle by pipe network and enters drum feed water pump for forced circulation, the heat generated by carbonylation reaction is removed by the warming of drum feed water in shell side, in this process, low low-pressure steam with pressure of 0.06MPaG~0.1MPaG is simultaneously by-produced, because low low-pressure steam pressure is low, the utilization value is small, so in actual production, these low low-pressure steam has following two processing methods:

[0003] (1) the first processing method: low low-pressure steam from drum is directly discharged by discharge pipeline, not only causes resource waste, but also brings heat pollution to environment;

[0004] (2) the second processing method: low low-pressure steam from drum is first cooled to obtain condensate in cooler, then is transported to condensate pipe network as cooling water for reuse;But this processing method still cannot make the heat of low low-pressure steam effectively utilized.

[0005] In summary, the processing method of existing low low-pressure steam cannot recycle low low-pressure steam heat, causing serious energy waste. UTILITY MODEL CONTENT

[0006] In view of the technical problem that low low-pressure steam heat cannot be recycled in the processing of existing low low-pressure steam, causing serious energy waste, the utility model provides a kind of by-product low low-pressure steam recycling system in ethylene glycol production process.

[0007] The utility model discloses a kind of by-product low low-pressure steam recycling system in ethylene glycol production process, which can recycle and realize secondary utilization of low low-pressure steam by-produced in ethylene glycol production process by setting drum, low low-pressure steam compressor, heater, low-pressure steam pipe network and condensate pipe network, to achieve the purpose of energy saving, emission reduction and consumption reduction.

[0008] To achieve the above purpose, the technical scheme adopted by the utility model is as follows:

[0009] A kind of by-product low low-pressure steam recycling system in ethylene glycol production process, including drum, low low-pressure steam compressor, low-pressure steam pipe network and condensate pipe network and heater;

[0010] The output end of the steam drum is communicated with the low-low pressure steam compressor, the heater and the condensate pipe network; the low pressure steam pipe network is communicated with the low-low pressure steam compressor.

[0011] Further limited, the heater includes a synthetic circulating gas heater and a nitric acid reduction system heater connected in parallel; one end of the heater connected in parallel is communicated with the low-low pressure steam compressor, and the other end of the heater connected in parallel is communicated with the condensate pipe network.

[0012] Further limited, the fourth gate valve is arranged between the low pressure steam pipe network and the low-low pressure steam compressor.

[0013] Further limited, the low-low pressure steam recycling system by-produced in the ethylene glycol production process further includes a synthetic circulating gas preheater; the output end of the steam drum is communicated with the input end of the steam drum and the low-low pressure steam compressor after the synthetic circulating gas preheater.

[0014] Further limited, the low-low pressure steam recycling system by-produced in the ethylene glycol production process further includes a low-low pressure steam condensate separation tank; the synthetic circulating gas preheater is communicated with the input end of the steam drum and the low-low pressure steam compressor after the low-low pressure steam condensate separation tank.

[0015] Further limited, the first gate valve is arranged between the output end of the steam drum and the low-low pressure steam compressor; the pipeline between the low-low pressure steam condensate separation tank, the first gate valve and the low-low pressure steam compressor is communicated.

[0016] Further limited, the fifth gate valve is arranged between the output end of the steam drum and the synthetic circulating gas preheater; the fifth gate valve is connected in parallel with the first gate valve.

[0017] Further limited, the low-low pressure steam recycling system by-produced in the ethylene glycol production process further includes a low-low pressure steam air cooler; one end of the low-low pressure steam air cooler is communicated with the first gate valve, the low-low pressure steam condensate separation tank and the low-low pressure steam compressor; the other end of the low-low pressure steam air cooler is communicated with the input end of the steam drum.

[0018] Further limited, the low-low pressure steam recycling system by-produced in the ethylene glycol production process further includes a low-low pressure steam condensate buffer tank arranged between the low-low pressure steam air cooler and the input end of the steam drum.

[0019] Further limited, the low-low pressure steam recycling system by-produced in the ethylene glycol production process further includes a second gate valve and a third gate valve; the low-low pressure steam air cooler is communicated with the low-low pressure steam compressor in sequence through the second gate valve and the third gate valve; the second gate valve is further connected with the first gate valve and the third gate valve.

[0020] Compared with the prior art, the beneficial effects of the technical scheme of the utility model are:

[0021] 1. The utility model discloses a steam drum and low low pressure steam compressor are set up, and the low low pressure steam is transported to the low pressure steam pipe network after being pressurized and is directly used secondly, or enters the heater and then enters the condensate pipe network to realize utilization after fully utilizing the heat. It can be seen that the utility model can recycle and realize secondary use of the low low pressure steam by-produced in the production process of ethylene glycol, and the purpose of energy saving, emission reduction and consumption reduction is achieved.

[0022] 2. The utility model discloses a heater includes parallelly connected synthetic circulating gas heater and nitric acid reduction system heater, and the low low pressure steam generated in the production of ethylene glycol is pressurized and then used in the intermediate process of ethylene glycol production to realize heat recycling, and the recycling effect is good, can effectively reduce the venting rate of steam, reduce the energy consumption required by ethylene glycol production, and save the cost.

[0023] 3. The utility model discloses still set up low low pressure steam air cooler, and the steam condensate formed after the by-product low low pressure steam is air cooled is all used to the steam drum by gravity return, not only realizes the use of low low pressure steam, and the low low pressure steam air cooler is used as spare, can guarantee the stability of system, in addition, still set up low low pressure steam condensate buffer tank and start the buffer effect to the steam condensate formed.

[0024] 4. The utility model discloses set up synthetic circulating gas preheater, first, the heat of low low pressure steam is recycled, then, the low low pressure steam after cooling is sent to pressurization or air cooling treatment, and the utilization rate of heat is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The schematic diagram of the by-product low low pressure steam recycling system is provided for example 1.

[0026] Figure 2 The schematic diagram of the by-product low low pressure steam recycling system is provided for example 2.

[0027] Figure 3 The schematic diagram of the by-product low low pressure steam recycling system is provided for example 3.

[0028] Among them:

[0029] E101-synthetic circulating gas preheater, E102-synthetic circulating gas heater, E103-nitric acid reduction system heater, E104-low low pressure steam air cooler, V101-steam drum, V102-low low pressure steam condensate separator, V103-low low pressure steam condensate buffer tank, C101-low low pressure steam compressor, Z001-first gate valve, Z002-second gate valve, Z003-third gate valve, Z004-fourth gate valve, Z005-fifth gate valve. DETAILED DESCRIPTION

[0030] The advantages and features of the present application will be more easily understood by those skilled in the art from the preferred embodiments of the present application described in detail below in conjunction with the accompanying drawings, so that the scope of protection of the present application can be more clearly defined.

[0031] Embodiment 1

[0032] Referring to Figure 1 The present embodiment provides a low-low pressure steam recycling system in an ethylene glycol production process, comprising a steam drum V101, a low-low pressure steam compressor C101, a low pressure steam pipe network, a condensate pipe network and a heater. The output end of the steam drum V101 is communicated with the condensate pipe network via the low-low pressure steam compressor C101 and the heater; the low pressure steam pipe network is communicated with the low-low pressure steam compressor C101.

[0033] In the present embodiment, the low pressure steam pipe network is a steam pipe network with a pressure of 0.15-0.22 MPaG; the condensate pipe network is a condensate pipe network with a pressure of 0.15-0.22 MPaG. In use, the low-low pressure steam is pressurized to the required pressure of the secondary steam by the low-low pressure steam compressor C101 according to the actual demand.

[0034] Preferably, the low pressure steam pipe network is a steam pipe network with a pressure of 0.2 MPaG; the condensate pipe network is a condensate pipe network with a pressure of 0.2 MPaG.

[0035] In the present embodiment, the heater comprises a synthetic cycle gas heater E102 and a nitric acid reduction system heater E103 connected in parallel; one end of the parallel connection is communicated with the low-low pressure steam compressor C101, and the other end of the parallel connection is communicated with the condensate pipe network.

[0036] The synthetic cycle gas heater E102 and the nitric acid reduction system heater E103 are both heating devices in the ethylene glycol production system, which pressurize the low-low pressure steam generated in the dimethyl oxalate DMO synthesis process of the ethylene glycol production and reuse it in the intermediate process of the ethylene glycol production, so as to realize heat recycling, effectively reduce the steam venting rate, reduce the energy consumption required for the ethylene glycol production and save costs.

[0037] In the embodiment, the by-product low-low pressure steam is discharged from the output end (steam outlet) of the steam drum V101; one end of the low-low pressure steam compressor C101 is the steam inlet end, the other end of the low-low pressure steam compressor C101 is the steam outlet end, the steam inlet end of the low-low pressure steam compressor C101 is communicated with the output end of the steam drum V101, and the steam outlet end of the low-low pressure steam compressor C101 is divided into three branches; the first branch is connected with the steam inlet end of the synthetic circulating gas heater E102, the liquid outlet end of the synthetic circulating gas heater E102 is connected with the condensate pipe network (0.2 MPa condensate pipe network); the second branch is connected with the steam inlet end of the nitric acid reduction system heater E103, and the liquid outlet end of the nitric acid reduction system heater E103 is connected with the condensate pipe network (0.2 MPa condensate pipe network); and the third branch is connected with the low-pressure steam pipe network (0.2 MpaG steam pipe network).

[0038] In the embodiment, the by-product low-low pressure steam recycling system in the ethylene glycol production process further comprises a fourth gate valve Z004 arranged between the low-pressure steam pipe network and the low-low pressure steam compressor C101, and the opening and closing of the 0.2 MpaG steam entering the low-pressure steam pipe network is controlled through the fourth gate valve Z004.

[0039] The by-product low-low pressure steam recycling system in the ethylene glycol production process provided by the embodiment has the following working process:

[0040] The by-product low-low pressure steam (pressure: 0.06 MPaG-0.1 MPaG) in the steam drum V101 is sent to the low-low pressure steam compressor C101, the by-product low-low pressure steam entering the low-low pressure steam compressor C101 is compressed into 0.2 MPaG low-pressure steam, and then is divided into three paths: the first path goes to the shell side of the synthetic circulating gas heater E102 to recover heat energy, and then the formed gas-liquid condensate is sent to the condensate pipe network for recycling; the second path goes to the shell side of the nitric acid reduction system heater E103 to recover heat energy, and then the formed gas-liquid condensate is sent to the condensate pipe network for recycling; and the third path all enters the low-pressure steam pipe network for recycling, and 0.2 MPaG low-pressure steam is output to the outside through the low-pressure steam pipe network, the 0.2 MPaG low-pressure steam can be supplied to the ethylene glycol production system, or can be transported to other devices needing this level of low-pressure steam, so as to realize the heat recovery and utilization of the low-low pressure steam, avoid resource waste, reduce the consumption of heat energy in the ethylene glycol production process, and save costs.

[0041] Embodiment 2

[0042] Reference Figure 2 On the basis of Embodiment 1, the by-product low-low pressure steam recycling system in the ethylene glycol production process provided by the embodiment further comprises a synthetic circulating gas preheater E101; the output end of the steam drum V101 is communicated with the input end of the steam drum V101 and the low-low pressure steam compressor C101 after passing through the synthetic circulating gas preheater E101.

[0043] In the embodiment, the low-low pressure steam recycling system by-produced in the ethylene glycol production process further comprises a low-low pressure steam condensate separation tank V102; the synthetic circulating gas preheater E101 is communicated with the input end of the steam drum V101 and the low-low pressure steam compressor C101 after passing through the low-low pressure steam condensate separation tank V102.

[0044] In the embodiment, the first gate valve Z001 is arranged between the output end of the steam drum V101 and the low-low pressure steam compressor C101; the pipeline between the low-low pressure steam condensate separation tank V102 and the first gate valve Z001 and the low-low pressure steam compressor C101 is communicated.

[0045] In the embodiment, the fifth gate valve Z005 is arranged between the output end of the steam drum V101 and the synthetic circulating gas preheater E101, and the fifth gate valve Z005 is connected in parallel with the first gate valve Z001.

[0046] In the embodiment, the synthetic circulating gas preheater E101 is a preheating device in the ethylene glycol production system, which pressurizes the low-low pressure steam generated in the dimethyl oxalate DMO synthesis process of the ethylene glycol production and reuses it in the intermediate process of the ethylene glycol production, so as to realize heat recycling, effectively reduce the steam venting rate, reduce the energy consumption required by the ethylene glycol production, and save costs.

[0047] Specifically, the output end (steam outlet end) of the steam drum V101 is divided into two branches; the first branch is connected to one end (i.e. steam inlet end) of the synthetic circulating gas preheater E101 through the fifth gate valve Z005, and the second branch is connected to the steam outlet end at the top of the low-low pressure steam condensate separation tank V102 and the steam inlet end of the low-low pressure steam compressor C101 after passing through the first gate valve Z001; the other end (i.e. liquid outlet end) of the synthetic circulating gas preheater E101 is connected to the liquid inlet end of the low-low pressure steam condensate separation tank V102, and the liquid outlet end at the bottom of the low-low pressure steam condensate separation tank V102 is connected to the liquid inlet end (i.e. liquid inlet end) of the steam drum V101.

[0048] The low-low pressure steam recycling system by-produced in the ethylene glycol production process provided in the embodiment has the following working process:

[0049] The first gate valve Z001 and the fifth gate valve Z005 are opened, so that the low-low pressure steam from the output end (steam outlet end) of the steam drum V101 is divided into two parts and processed through two paths.

[0050] The first portion of low-pressure steam enters the synthesis cycle gas preheater E101 through the fifth gate valve Z005 and enters the shell side of the synthesis cycle gas preheater E101 to recover the heat energy of the low-pressure steam. The resulting gas-liquid condensate then flows by gravity to the low-pressure steam condensate separator V102 for separation. The separated condensate flows from the bottom of the low-pressure steam condensate separator V102 and is fully recycled to the input end of the steam drum V101. The separated steam flows from the top of the low-pressure steam condensate separator V102. The second portion of low-pressure steam passes through the first gate valve Z001 and is mixed with the steam flowing from the top of the low-pressure steam condensate separator V102. The steam then enters the low-pressure steam compressor C101 for supercharging to produce 0.2 MPaG low-pressure steam. The 0.2 MPaG low-pressure steam is then processed in the same manner as in Example 1, further realizing the recovery of heat and steam from the low-pressure steam.

[0051] Example 3

[0052] See also Figure 3 Based on Example 2, the system for recovering and utilizing the low-pressure steam produced as a by-product in the ethylene glycol production process provided in this embodiment further includes a low-pressure steam air cooler E104; one end of the low-pressure steam air cooler E104 is respectively connected to the first gate valve Z001, the low-pressure steam condensate separator V102, and the low-pressure steam compressor C101; the other end of the low-pressure steam air cooler E104 is connected to the input end of the steam drum V101.

[0053] In this embodiment, the system for recovering and utilizing the low-pressure steam produced as a by-product during the production of ethylene glycol further includes a low-pressure steam condensate buffer tank V103 disposed between the low-pressure steam air cooler E104 and the input end of the steam drum V101.

[0054] In this embodiment, the system for recovering and utilizing the low-pressure steam produced as a by-product during the production of ethylene glycol further includes a second gate valve Z002 and a third gate valve Z003; the low-pressure steam air cooler E104 is connected to the low-pressure steam compressor C101 via the second gate valve Z002 and the third gate valve Z003 in sequence; the second gate valve Z002 is also connected to the low-pressure steam condensate buffer tank V103 and the first gate valve Z001 and the third gate valve Z003.

[0055] The sealed steam network is a 0.5MpaG steam network; the low-pressure steam network is a 0.2MpaG steam network; and the condensate network is a 0.2MpaG condensate network.

[0056] In the embodiment, the low-low pressure steam air cooler E104 is used as a backup scheme, when the low-low pressure steam compressor C101 is out of service or the obtained 0.2 MPa G steam is too much to balance the 0.2 MPa G steam pipe network, at this time, the third gate valve Z003 is closed and the second gate valve Z002 is opened to switch to the low-low pressure steam air cooler E104 for processing.

[0057] The working process of the byproduct low-low pressure steam recycling system in the ethylene glycol production process is as follows:

[0058] Part of the low-low pressure steam is mixed with steam from the top of the low-low pressure steam condensate separation tank V102 after passing through the first gate valve Z001, and then is sent to the low-low pressure steam air cooler E104 through the second gate valve Z002, the byproduct low-low pressure steam is air-cooled to form steam condensate, and the steam condensate is all self-flowing to the low-low pressure steam condensate buffer tank V103 and then is all self-flowing to the input end of the steam drum V101 for recycling.

[0059] In the embodiment, in the dimethyl oxalate DMO synthesis process of the ethylene glycol production system, the activity of the catalyst gradually decreases with the progress of the carbonylation reaction, and the steam drum V101 needs to be pressurized, therefore, in order to ensure that the steam condensate after air cooling of the low-low pressure steam air cooler E104 can smoothly flow back to the input end (liquid inlet end) of the steam drum V101, a low-pressure steam sealing device is arranged on the low-low pressure steam condensate buffer tank V103, and a liquid seal is arranged on the low-low pressure steam condensate buffer tank V103, so as to maintain the back pressure of the ethylene glycol production system and ensure the stability of the system operation.

[0060] Preferably, the low-low pressure steam condensate buffer tank V103 is connected with a sealing steam pipe network (0.5 MPa G low-pressure steam pipe network) on the side, so as to seal the low-low pressure steam condensate buffer tank V103 at low pressure, and enable the steam condensate after air cooling of the low-low pressure steam air cooler E104 to smoothly flow back to the input end of the steam drum V101. Preferably, a U-shaped bend pipe line is arranged at the liquid outlet end of the bottom of the low-low pressure steam condensate buffer tank V103, for liquid sealing at the bottom. The sealing steam pipe network and the U-shaped bend pipe line ensure the pressure balance of the system and stable operation.

[0061] The above technical scheme provided by the utility model is suitable for byproduct steam (namely low-low pressure steam) with a pressure of 0.06-0.1 MPa G, and the secondary low-pressure steam (preferably 0.2 MPa G) with a pressure of 0.15-0.22 MPa G obtained through pressurization can effectively recycle and realize secondary utilization of the byproduct low-low pressure steam, so as to achieve the purpose of energy saving, emission reduction and consumption reduction. Meanwhile, the above technical scheme is used to recycle 60 t / h low-low pressure steam, and the annual production operation time is calculated as 7200 h, the unit price of the secondary low-pressure steam is about 12 yuan / t, and the economic cost of 518.4 ten thousand yuan can be saved per year.

[0062] The above only describes the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, which is made by using the content of the present application specification and drawings, is also included in the patent protection scope of the present application.

Claims

1. A system for recycling low pressure steam by-product in an ethylene glycol production process, characterized by, The system comprises a steam drum (V101), a low-low pressure steam compressor (C101), a low pressure steam pipe network, a condensate pipe network and a heater; the output end of the steam drum (V101) is connected with the low-low pressure steam compressor (C101) and the heater in sequence and is communicated with the condensate pipe network; the low pressure steam pipe network is communicated with the low-low pressure steam compressor (C101).

2. The system for recycling low-pressure steam produced as a byproduct in an ethylene glycol production process according to claim 1, characterized by, The heater comprises a synthetic cycle gas heater (E102) and a nitric acid reduction system heater (E103) connected in parallel; one end of the heater connected in parallel is communicated with the low-low pressure steam compressor (C101), and the other end of the heater connected in parallel is communicated with the condensate pipe network.

3. The system according to claim 2, wherein the low-pressure steam is used for heating the boiler feed water. A fourth gate valve (Z004) is arranged between the low pressure steam pipe network and the low-low pressure steam compressor (C101). ​ 4. The system for recycling low-pressure steam produced as a byproduct in an ethylene glycol production process according to claim 1, characterized by, The system further comprises a synthetic cycle gas preheater (E101); the output end of the steam drum (V101) is communicated with the input end of the steam drum (V101) and the low-low pressure steam compressor (C101) through the synthetic cycle gas preheater (E101).

5. The system for recycling low-pressure steam produced as a byproduct in an ethylene glycol production process according to claim 4, characterized by, The system further comprises a low-low pressure steam condensate separation tank (V102); the synthetic cycle gas preheater (E101) is communicated with the input end of the steam drum (V101) and the low-low pressure steam compressor (C101) through the low-low pressure steam condensate separation tank (V102).

6. The system for recycling low-pressure steam produced as a byproduct in an ethylene glycol production process according to claim 5, wherein A first gate valve (Z001) is arranged between the output end of the steam drum (V101) and the low-low pressure steam compressor (C101); the low-low pressure steam condensate separation tank (V102) is communicated with the pipeline between the first gate valve (Z001) and the low-low pressure steam compressor (C101).

7. The system according to claim 6, wherein the low-pressure steam is used for heating the boiler feed water. A fifth gate valve (Z005) is arranged between the output end of the steam drum (V101) and the synthetic cycle gas preheater (E101); the fifth gate valve (Z005) is connected in parallel with the first gate valve (Z001).

8. The system for recovering and utilizing by-product low-pressure steam in the ethylene glycol production process according to claim 5, characterized in that: The system further comprises a low-low pressure steam air cooler (E104); one end of the low-low pressure steam air cooler (E104) is communicated with the first gate valve (Z001), the low-low pressure steam condensate separation tank (V102) and the low-low pressure steam compressor (C101) respectively; the other end of the low-low pressure steam air cooler (E104) is communicated with the input end of the steam drum (V101).

9. The system for recycling low-pressure steam produced as a byproduct in an ethylene glycol production process according to claim 8, characterized by, The system further comprises a low-low pressure steam condensate buffer tank (V103) arranged between the low-low pressure steam air cooler (E104) and the input end of the steam drum (V101).

10. The system for recycling low-pressure steam produced as a byproduct in an ethylene glycol production process according to claim 9, wherein The system further comprises a second gate valve (Z002) and a third gate valve (Z003); the low-low pressure steam air cooler (E104) is communicated with the low-low pressure steam compressor (C101) in sequence through the second gate valve (Z002) and the third gate valve (Z003); the second gate valve (Z002) is further connected with the first gate valve (Z001) and the third gate valve (Z003).

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