凝结水管理 斯派莎克工程（中国）有限公司 基础培训课程

主 要 内 容 1) 有 效 排 除 冷 凝 水 2) 冷 凝 水 的 回 缩 3) 冷 凝 水 管 的 布 置 4) 二 次 蒸 汽 的 利 用

换 热 器 积 水 减 少 热 量 输 出 控 制 阀 振 荡 产 品 质 量 出 现 问 题 腐 蚀 水 锤 设 备 变 形 和 损 坏 换 热 器 积 水 会 引 起: 减 少 热 量 输 出 控 制 阀 振 荡 产 品 质 量 出 现 问 题 腐 蚀 水 锤 设 备 变 形 和 损 坏 设 备 和 管 道 产 生 冷 冻 和 热 应 力 板 式 换 热 器 选 型 过 大 使 这 种 情 况 更 加 严 重

由 于 回 水 管 提 升 引 起‘ 失 流’ 1.0 bar g 15 米 空 气 加 热 组 1.5 bar g ‘ 失 流’ 是 指 由 于 疏 水 阀 前 后 没 有 正 的 压 差 使 冷 凝 水 无 法 排 除 1.0 bar g 15 米 空 气 加 热 组 1.5 bar g

‘失 流’ 工 况 产 品 温 度 输 入 P1 换 热 器 P2

‘ 失 流’ 工 况 产 品 温 度 输 入 P1 换 热 器 P2

D) 现 在 确 定 满 足 实 际 负 荷240,000W 时， 换 热 器 中 的 压 力。 换 热 器 内 发 生 了 什 么？ A) 对 某 换 热 器， 设 计 者 计 算 最 大 热 负 荷 为 240,000 W。 为 了 适 应 偶 然 的 情 况， 增 加 25％ 的 余 量， 则 将 加 热 器 定 为300,000 W, 使 用 压 力 为3.5 bar g。 水 以80°C 流 出、70°C 流 入， 平 均 水 温 为75°C 。 B制 造 商 提 供 满 足 负 荷 要 求 的 加 热 器， 考 虑 结 垢 等 因 素， 提 供 的 加 热 器 将 产 生 390,000 W 的 负 荷， 蒸 汽 压 力3.5 bar g. C)热 负 荷＝ 加 热 表 面 积 ×传 热 系 数  温 差， 即 Q＝A ×U × T,A ×U＝390,000/(148-75)=5342 W/ °C D) 现 在 确 定 满 足 实 际 负 荷240,000W 时， 换 热 器 中 的 压 力。  T=240000/5342=45 °C , 则 蒸 汽 温 度 为＝45 ＋75＝120 °C ， 蒸 汽 的 饱 和 压 力 为 1 bar g。 E) 当 负 载 为50％ 时，即 输 出 为 120000W， 换 热 器 中 的 压 力 为，  T=120000/5342=22 °C , 则 蒸 汽 温 度 为＝22 ＋75＝97 °C ， 对 应 的 绝 对 蒸 汽 压 力 为 0.86 bar, 低 于 大 气 压 力( 1 bar)。 F) 换 热 器 内 会 如 何 ？？？

变 进 口 温 度 的‘ 失 流’ 图 1 3 2 空 气 加 热 器 应 用 T1 P1 T2 P2 温 度 篊 压 力 bar g 200 20 40 60 80 100 120 140 160 180 90 70 50 30 10 14.5 11.6 0.7 0.5 0.05 2.6 0.3 0.2 0.1 9.0 7.0 5.2 3.8 1.7 1.0 0.4 T1 P1 T2 P2 1 2 3 温 度 篊 压 力 bar g 空 气 加 热 器 应 用 蒸 汽 压 力 ( 温 度) - 2 bar g 总 的 背 压 - 0.4 bar g 最 终 要 求 温 度 - 80 oC 产 品 温 度 产 品 初 始 温 度 - 30 oC % 流 量 (控 制 阀 开 度)

对 有 些 工 况, 仅 仅 一 个 疏 水 阀 是 不 够 的 设 备 不 工 作 SLIDE 4 incomplete installation We need to continue to advise customers that if they don抰 complete the installation they must expect problems. BLANK 设 备 不 工 作

从 换 热 器 中 排 除 冷 凝 水 第 一 种 解 决 方 法 使 用 破 真 空 器, 利 用 静 压 头 第 二 种 解 决 方 法 第 一 种 解 决 方 法 使 用 破 真 空 器, 利 用 静 压 头 第 二 种 解 决 方 法 蒸 汽 疏 水 阀 和 泵 组 合 第 三 种 解 决 方 法 自 动 疏 水 阀 泵 SLIDE 5 - heat exchanger drainage SLIDE 5 BUILD UP Vacuum breaker and static head method and SLIDE 5 BUILD UP Pressure powered pump and trap combination They both have their place but there抯 a big gap between them. Let抯 look briefly at these and then what we are going to release to bridge this gap.

冷 凝 水 的 排 除 破 真 空 器 PMax = 4 bar g Mmax = 500 kg/h 静 压 头 依 靠 重 力 排 放

蒸 汽 疏 水 阀 和 机 械 泵 组 合 PMax = 4 bar g Mmax = 500 kg/h 蒸 汽 压 力 = 7 bar g

自 动 疏 水 阀 泵 PMax = 4 bar g Mmax = 500 kg/h 蒸 汽 压 力 = 7 bar g 0.3 bar g

APT14 自 动 疏 水 阀 泵

APT14 切 面 图 速 动 机 构 低 阻 力 的 摆 动 式 入 口 止 回 阀 可 换 的 阀 和 阀 座 低 高 度 的 结 实 的 不 锈 钢 浮 球 高 排 量 的 两 级 疏 水 阀 申 请 专 利 的 低 高 度 机 构 球 形 出 口 止 回 阀 简 洁 的 设 计， 包 括 了 所 有 用 来 在 各 种 条 件 下 排 除 冷 凝 水 的 需 要 的 部 件

APT14 工 作 原 理 (1) 冷 凝 水 由 入 口 摆 动 式 止 回 阀 进 入 泵 体 使 浮 球 上 升 冷 凝 水 由 入 口 摆 动 式 止 回 阀 进 入 泵 体 使 浮 球 上 升 浮 球 与 疏 水 阀 机 构 相 连 如 果 上 游 压 力 足 以 克 服 背 压， 冷 凝 水 将 被 排 出

APT14 工 作 原 理 (2) 如 果 系 统 压 力 低 于 背 压 ， 标 准 的 疏 水 阀 将 失 流 设 备 将 积 水 如 果 系 统 压 力 低 于 背 压 ， 标 准 的 疏 水 阀 将 失 流 设 备 将 积 水 对 APT14， 冷 凝 水 则 将 进 入 泵 体

APT14 工 作 原 理 (3) 浮 球 上 升， 触 发 泵 的 翻 转 机 构 蒸 汽 入 口 阀 开， 同 时 排 汽 阀 关

APT14 工 作 原 理 (4) 速 动 机 构 保 证 了 从 疏 水 阀 模 式 向 泵 模 式 的 快 速 转 换 速 动 机 构 保 证 了 从 疏 水 阀 模 式 向 泵 模 式 的 快 速 转 换 动 力 蒸 汽 入 口 阀 打 开， 泵 体 内 的 压 力 增 大， 超 过 背 压 冷 凝 水 被 推 出， 进 入 回 收 管

APT14 工 作 原 理 (5) 泵 体 内 冷 凝 水 水 位 下 降 再 次 触 发 翻 转 机 构 关 闭 进 汽 阀， 同 时 打 开 排 汽 阀

APT14 工 作 原 理 (6) APT14 内 的 压 力 有 排 汽 阀 释 放 当 泵 体 内 压 力 再 次 平 衡 ， 冷 凝 水 由 入 口 止 回 阀 进 入 泵 体 同 时 出 口 止 回 阀 确 保 没 有 冷 凝 水 逆 流 进 入 泵 体 循 环 重 新 开 始

从 板 式 换 热 器 中 排 除 冷 凝 水

从 管 壳 式 换 热 器 中 排 除 冷 凝 水

从 过 程 罐 中 排 除 冷 凝 水

从 真 空 设 备 中 排 除 冷 凝 水

从 多 组 加 热 器 中 排 除 冷 凝 水

应 用 实 例 “- - 使 用 Spirax Sarco APT 14 自 动 疏 水 阀 泵 替 换 通 常 的 疏 水 阀 后, 加 热 时 间 从25 分 钟 降 低 到15 分 钟 - - ”

冷 凝 水 的 回 收 Spirax Sarco Publication P38 揅ondensate and Flash Steam Recovery Contents 1. Condensate Return 2. Sizing Condensate Return Lines 3. Long Delivery Lines 4. Flooded Return Lines 5. General 6. Condensate Pumping 7. Flash Steam 8. Typical Applications Introduction When steam condenses, the enthalpy transferred to the cooler material being heated accounts for about only 75% of the enthalpy supplied in the boiler to produce the steam. The remainder, about 25%, is still held by the condensed water. As well as having this heat content, the condensate is distilled water and is ideal for use as boiler feed water. An efficient instillation will collect every drop of condensate it economically can, and return it to the deaerator or boiler feed tank, or use it in the process. Condensate is discharged through steam traps from a higher to a lower pressure. Some of its heat content then re-evaporates, as 揻lash steam? a proportion of the condensate. A 10% loss of flash steam means that 10% of the fuel is being burnt, just to heat the atmosphere. Flash Steam Recovery is an important part of achieving an energy efficient system. This training module will look at two essential areas - Condensate Return and Flash Steam Recovery. Some of the apparent problem areas are outlined and solutions offered. 冷 凝 水 的 回 收

带 冷 凝 水 回 收 的 简 单 蒸 汽 系 统 90篊 冷 凝 水 feedtank 蒸 汽 8 bar g 给 水 箱 设 备 90篊 冷 凝 水 feedtank 设 备 集 水 箱 蒸 汽 8 bar g 给 水 箱 控 制 阀 90篊 疏 水 阀 锅 炉 给 水 泵 热 量 机 械 泵

为 什 么 回 收 冷 凝 水? 冷 凝 水 是 极 有 价 值 的 资 源. 其 所 含 有 的 高 热 量 是 回 收 的 最 佳 理 由. 冷 凝 水 是 经 过 水 处 理, 回 收 冷 凝 水 可 以 降 低 水 处 理 费 用. 减 少 锅 炉 排 污. 可 以 避 免 冷 凝 水 排 放 的 巨 大 费 用. 减 少 补 充 给 锅 炉 的 水, 降 低 水 费 用. 总 的 效 果: 可 以 节 约 20% 以 上 的 燃 料.

回 收 冷 凝 水 蒸 汽 全 热 能 蒸 汽 潜 热 能 焓 (kJ/kg) 冷 凝 水 中 的 能 量 Condensate Return An effective condensate recovery system, collecting the hot condensate from the steam using equipment and returning it to the boiler feed system, can pay for itself in reduced fuel costs alone in a remarkably short time. The above slide illustrates the heat content of steam. 焓 (kJ/kg) 冷 凝 水 中 的 能 量 可 供 二 次 蒸 汽 的 能 量 大 气 压 力 下 冷 凝 水 的 能 量 压 力 (bar g)

回 收 冷 凝 水 的 节 约 ( 一) 燃 料 费 用 冷 凝 水 回 收 温 度 为 90 oC 补 给 冷 水 温 度 为 10 oC ( 一) 燃 料 费 用 冷 凝 水 回 收 温 度 为 90 oC 补 给 冷 水 温 度 为 10 oC 温 度 差 80 oC 升 高 1 kg 的 补 给 水 至 90 oC, 所 需 能 量 为, 1 x 80 x 4.1868 = 335 KJ 如 果 蒸 汽 负 载 为 100kg/hr 335 x 1000 ＝ 335,000 KJ/hr 工 厂 运 行 24 小 时/ 天, 300 天/ 年, 则 加 热 补 给 水 所 需 能 量 为： 335000 x 24 x 300 = 2,412,000,000 KJ 1 升 燃 油 的 热 量 为 41,100kJ, 锅 炉 效 率 为 80％, 则 需 要 燃 油： 2,412,000,000 / ( 41100 x 0.8) =73358 升 总 的 燃 油 费 用 为 2.2 x 73358=161,388 元

回 收 冷 凝 水 的 节 约 水 8400 吨/ 年 如 果 每 吨 水 费 用 为 0.7 元 ( 二) 水 的 费 用 水 8400 吨/ 年 如 果 每 吨 水 费 用 为 0.7 元 总 计 8400 x 0.70 = 5,880 元 ( 三) 水 处 理 费 每 吨 水 处 理 费 为 1.1 元 总 计 1.1 x 8400 = 9,240 元

回 收 冷 凝 水 的 节 约 燃 料 + 水 + 水 处 理 161,388 + 5,880 + 9,240 = 176,508 元 总 节 约 燃 料 + 水 + 水 处 理 161,388 + 5,880 + 9,240 = 176,508 元 还 有 其 它…….

有冷凝水回收的蒸汽系统 90℃冷凝水 feedtank 设备 水槽 蒸汽 8 bar g 给水槽 控制阀 90℃ 疏水阀 锅炉 给水泵 泵

回 收 冷 凝 水 的 机 械 泵

在 大 气 压 力 下 回 收 冷 凝 水: 开 式 系 统 控 制 阀 破 真 空 器 泵 克 服 冷 凝 水 管 道 的 背 压, 但 换 热 器 出 口 必 须 高 于 集 水 箱, 使 冷 凝 水 通 过 重 力 流 入. 设 备 排 向 大 气 口 疏 水 阀 集 水 箱 动 力 蒸 汽 泵

泵机构 - MFP14 系列 排废汽阀 吊耳 蒸汽进汽阀 弹簧 顶杆 浮球及连杆

MFP14 特性 进排汽阀的整个机构不会浸入水中 浮球及连杆 吊耳 高排量止回阀 球墨铸铁泵体

MFP14: 进 水 冲 程 如 果 有 足 够 的 注 水 头, 进 口 止 回 阀 打 开, 泵 开 始 进 水 并 排 除 废 气. 废 气阀 打 开, 动 力 蒸 汽 阀 关 闭. 如 果 有 足 够 的 注 水 头, 进 口 止 回 阀 打 开, 泵 开 始 进 水 并 排 除 废 气. 注 水 使 浮 球 升 起 进 口 止 回 阀 打 开

MFP14: 排 水 冲 程 浮 球 升 起 触 发 阀 门 机 构, 打 开 进 汽 阀, 关 闭 排 气 阀 蒸 汽 进 口 阀 打 开, 废 气 阀 关 闭 浮 球 升 起 触 发 阀 门 机 构, 打 开 进 汽 阀, 关 闭 排 气 阀 泵 体 内 升 压, 克 服 背 压 排 出 冷 凝 水 泵 内 排 空 出 口 止 回 阀 打 开

MFP: 特 点 和 使 用 优 点 在 所 有 的 负 载/ 压 力- 甚 至 是 真 空 情 况 下, 排 除 和 回 收 冷 凝 水. 一 种 设 计 能 满 足 所 有 应 用. 没 有 汽 蚀 问 题. 无 需 电 力 : 经 济, 适 用 于 危 险 区 域. 安 装 和 维 护 方 便. 最 高 操 作 压 力 可 至 13.8 bar. 不 锈 钢 内 部 件, 减 少 磨 损, 堵 塞 和 热 应 力. 高 排 量.

电 泵 和 机 械 泵 的 比 较 电 泵 机 械 泵 易 掌 握 通 常 价 格 低 廉 连 续 运 行 维 修 保 养 少 电 泵 机 械 泵 易 掌 握 通 常 价 格 低 廉 连 续 运 行 维 修 保 养 少 使 用 广 泛 低 廉 的 运 行 费 用， 可 适 用 于 危 险 区 域 最 小 进 口 压 力 必 须 为 正 压 进 口 压 力 可 以 为 负 多 种 安 装 方 式 单 一 安 装 方 式

典 型 应 用 回 收 冷 凝 水 ( 开 式 系 统) 泵 送 高 温 冷 凝 水, 没 有 汽 蚀 和 机 械 密 封 的 问 题. 排 气 口 回 收 冷 凝 水 ( 开 式 系 统) 泵 送 高 温 冷 凝 水, 没 有 汽 蚀 和 机 械 密 封 的 问 题. 提 供 最 大 热 量 回 收. 动 力 蒸 汽 疏 水 阀 冷 凝 水 收 集 罐 泵

典 型 应 用 从 过 程 容 器 和 换 热 器 中 排 除 冷 凝 水( 泵/ 疏 水 阀 组 合, 封 闭 系 统) 从 过 程 容 器 和 换 热 器 中 排 除 冷 凝 水( 泵/ 疏 水 阀 组 合, 封 闭 系 统) 在 所 有 压 力 工 况 下 排 除 冷 凝 水, 确 保 温 度 的 稳 定 , 避 免 水 锤, 腐 蚀 和 冷 冻 等. 换 热 器 排 空 冷 凝 水 收 集 罐 泵

不 同 压 力 下 工 作 的 疏 水 阀 10 bar g 3 bar g 10 bar g 0-10 bar g 变 化 3 bar g Receiver 0 bar g

满 溢 型 回 水 管 不 好 的 布 置 Steam Trap 满 溢 主 管 Condensate 改 善 的 布 置 Steam FLOODED RETURN LINES Connecting the discharge from any number of traps into a common return line causes few problems providing that the pipework is properly sized. Some care should be taken with the actual connection. Often sweep tees are preferred to the usual square tees, if erosion by a high velocity jet of flash steam and water from the discharge of an inverted bucket trap or a thermodynamic trap is to be avoided. Problems do occur, however, if condensate is discharged into a flooded return main. This often happens when draining steam lines. Frequently a pumped condensate return main follows the same route. It is tempting to simply connect the discharge from mains drain traps, and sometimes other traps, into the adjacent return main. Since a mains drain trap is required to discharge any condensate reaching it, with the minimum of back up, the usual choice is a trap discharging condensate at, or as close as possible to, steam temperature. This condensate will release maximum amounts of flash steam at the lower pressure in the return main. The flash steam has a relatively large volume and must push violently out of the way the water already present in the main. Then as the bubbles of flash steam make their way along the pipe, they can collapse quickly if they contact cooler condensate or even the cooler pipe wall. Both effects lead to waterhammer. The best solution is to avoid the flooded line, returning the condensate and flash steam to the nearest collecting point as shown in the slide. Where this is impractical, a second choice is to use a trap which holds back condensate until it is sub-cooled. To avoid water logging the steam main, a generous condensate collecting pocket and an unlagged cooling leg of 2 -- 3 m is essential. Another possibility is to use a float trap with its continuous discharge characteristic. This discharges saturated, flashing condensate, though a cooling leg at the outlet side of the trap may reduce a little the flash steam volume. Often the steady flow from the trap can be absorbed by the flooded line without major problems, especially if a diffuser fitting is used at the entry to the condensate main. Note:-It must be remembered that these are compromises only, and a gravity fall from the trap to a receiver should always be the aim. 改 善 的 布 置 Steam 双 金 属 疏 水 阀 冷 却 管 满 溢 主 管 Condensate 理 想 的 布 置 Steam Trap Condensate Receiver Pump

远 距 离 输 送 破 真 空 器 Boiler Feed Tank Plant 例 1 增 加 的 止 回 阀 Pump The momentum of the moving contents of a long delivery line may keep the water in motion for a little time after the Ogden Pump has completed its discharge stroke. Steam can then be pulled through the outlet check valve into the pipework. When the water in the pipe comes to rest, the back pressure in the line can compress the bubble of steam which had been stretched by the moving "column'' of water. The bubble shrinks, and water moves violently back towards the outlet check valve. The waterhammer which is implicit in this reversal of motion can be both alarming and serious. It usually is prevented by using a second, line size check, or non-return, valve in the line, perhaps 6m along from the pump. In some cases, where the delivery line rises to high level soon after leaving the pump, a vacuum breaker can be fitted at the high point. By admitting air at the appropriate time, this can allow the water to continue flowing towards the discharge point by its own momentum. An ideal arrangement which is sometimes possible is to have a receiver or break tank connected to the delivery line, closely after the pump and installed at a height from which gravity flow to the final receiver is practical. This means that in effect the pump is only required to lift condensate from its own receiver at low level to a second receiver at high level. The delivery line can then be sized to accept the continuous flow of condensate at the same rate as it is flowing towards the pump. See above slide.

远 距 离 输 送 破 真 空 器 Boiler Feed Tank Plant 例 1 Pump Break Tank Boiler The momentum of the moving contents of a long delivery line may keep the water in motion for a little time after the Ogden Pump has completed its discharge stroke. Steam can then be pulled through the outlet check valve into the pipework. When the water in the pipe comes to rest, the back pressure in the line can compress the bubble of steam which had been stretched by the moving "column'' of water. The bubble shrinks, and water moves violently back towards the outlet check valve. The waterhammer which is implicit in this reversal of motion can be both alarming and serious. It usually is prevented by using a second, line size check, or non-return, valve in the line, perhaps 6m along from the pump. In some cases, where the delivery line rises to high level soon after leaving the pump, a vacuum breaker can be fitted at the high point. By admitting air at the appropriate time, this can allow the water to continue flowing towards the discharge point by its own momentum. An ideal arrangement which is sometimes possible is to have a receiver or break tank connected to the delivery line, closely after the pump and installed at a height from which gravity flow to the final receiver is practical. This means that in effect the pump is only required to lift condensate from its own receiver at low level to a second receiver at high level. The delivery line can then be sized to accept the continuous flow of condensate at the same rate as it is flowing towards the pump. See above slide. Break Tank Boiler Feed Tank Plant 例 2 增 加 的 止 回 阀

起 动 疏 水 高 位 冷 凝 水 管 Steam 蓄 水 点 Trap 液 体 膨 胀 式 疏 水 阀 排 入 地 沟 GENERAL It is often sought to lift condensate from a trap to a high level return line, using the steam pressure within the trap. It will be remembered that a lift of 5.3 m means a back pressure on the trap of 0.5 bar. This reduces the differential pressure available to push water through the trap, although the reduction in trap capacity is likely to be significant only where low upstream pressures are being used. At start up, though, the steam pressures are likely to be very low for appreciable periods and it is common to find water backing up before the trap. Since this can lead to waterhammer in the space being drained, means should be provided for draining off this condensate until sufficient steam pressure is present to overcome the back pressure. Often the liquid expansion thermostatic trap can be used, discharging cold condensate to waste but closing to hot condensate when the steam pressure is enough to push condensate through the normal trap to the return line. See above slide. The delivery line from the trap to the overhead return line preferably is turned over on to the top of the main, rather than simply teed to the underside. This helps operation a little, since although the riser is probably full of water at start up, it contains little more than flash steam once hot condensate under pressure passes through the trap. Being so much less dense, this can reduce the back pressure on the trap, and will often reduce the noise and the waterhammer associated with rising lines at trap discharges. It is usual to fit a check valve at the outlet side of a steam trap particularly when the discharge line rises to a higher level. Steam 蓄 水 点 Trap 液 体 膨 胀 式 疏 水 阀 排 入 地 沟

二 次 蒸 汽 的 量 4 bar g 0 bar g 质 量 冷 凝 水 900 kg/h 二 次 蒸 汽 100 kg/h 体 积 冷 凝 水 0.9 m3/h 二 次 蒸 汽 167.3 m3/h 4 bar g 0 bar g

管 道 内 的 二 次 蒸 汽 100 kg 二 次 蒸 汽 99.44% 的 总 体 积 900 kg 冷 凝 水 0.56 % 的 总 体 积

冷 凝 水 排 放 举 例 7 bar g 的 蒸 汽, 170.5oC hg = 2769.1 kJ/kg Steam 排 气 阀 截 止 阀 7 bar g 的 蒸 汽, 170.5oC hg = 2769.1 kJ/kg 7 bar g 的 冷 凝 水, 170.5oC hf =721.4 kJ/kg 0 bar g 的 冷 凝 水 和 二 次 蒸 汽 100oC hf = 419.04 kJ/kg 排 气

有 多 少 二 次 蒸 汽 7 bar 饱 和 水 的 焓 值 = 721.4 kJ/kg 二 次 蒸 汽 比 例 = 302.4 2257 = 0.134 kg/kg 冷 凝 水 How Much Flash Steam The condensate enters the trap as saturated water, at a gauge pressure of 7 bar and a temperature of 170.5癈. Its enthalpy of saturated water is 721.4 kJ/kg. After passing through the steam trap, the pressure on the condensate is the return line pressure at 0 bar gauge. At this pressure, the enthalpy of saturated water is 419.0 kJ/kg and its temperature 100癈. If a kilogram of saturated water at 0 bar gauge were supplied with an additional (721.4 -- 419 = 302.4)kJ then this enthalpy would evaporate some of the water. The enthalpy of evaporation at 0 bar gauge is 2257 kJ/kg. An addition of 302.4 kJ must evaporate 302.4/2257 kg of steam from the water. Equally, when one kilogram of condensate containing 721.4 kJ reaches the return line where the pressure is 0 bar g, it has a surplus of 302.4 kJ above the enthalpy of saturated water it can hold. The same proportion of 302.4/2257 kg of "flash steam'' will be evaporated. Thus:-- Enthalpy of saturated water at 7 bar = 721.4 kJ/kg Enthalpy of saturated water at 0 bar = 419 kJ/kg Surplus = 302.4 kJ/kg Enthalpy of evaporation at 0 bar = 2257 kJ/kg Proportion of flash steam = 302.4/2257 = 0.134 If the steam using equipment were condensing 250 kg/h of steam, then the amount of flash steam released by the condensate at 0 bar g would be:-- 0.134 x 250 kg/h = 33.5 kg/h.

产 生 二 次 蒸 汽 曲 线 图 疏 水 阀 前 压 力 bar kg 二 次 蒸 汽 / kg 冷 凝 水 二 次 蒸 汽 压 力 bar g 4 10 % 1 2 3 5 6 7 8 9 10 12 11 13 14 15 2.5 1.5 0.5 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 大 气 压 力

回 收 二 次 蒸 汽 的 节 约? 实 例 蒸 汽 负 载 5000kg/h, 蒸 汽 压 力10bar g, 二 次 蒸 汽 压 力 1bar g, 二 次 蒸 汽 的 量 根 据 曲 线, 二 次 蒸 汽 量 为 0.125kg/kg. 总 的 二 次 蒸 汽 量 为＝5000X0.125=625 kg/hr 节 约 1 升 油 大 约 产 生 14kg 的 蒸 汽 , 则 产 生 625kg 的 蒸 汽 需 要 625/14＝44.6 的 油, 如 果 燃 油 价 格 为2.20 元/ 升, 工 厂 运 行 24 小 时/ 天, 300 天/ 年, 则: 44.6 x 2.20 x 24 x 300=706,464 元 其 它 节 约 包 括: 给 水, 水 处 理 费 用, 减 少 排 污, 等 等.

回 收 二 次 蒸 汽 二 次 蒸 汽 出 口 Sizing Flash Steam Recovery Vessels In order that use can be made of the steam which flashes off the condensate at low pressure, it is necessary to separate the steam from the condensate using a "flash vessel''. This is usually a vertical vessel as shown in Fig. 20, with the inlet for the flashing condensate about one third of the way up the side. The diameter of the flash vessel is chosen so that the steam flows towards the top outlet connection at not more than about 3m/s. This is sufficiently slow that the drops of water can fall through the steam in contra-flow, to the bottom of the vessel. Adequate height above the inlet is necessary, to ensure this separation. Further, the diameter of the vessel must be great enough to allow the condensate to pass through the vessel without the liquid stream being too turbulent. In those cases where only relatively small pressure differences exist across the steam traps, it is quite possible to have large quantities of condensate but only small amounts of flash steam. Sizing the vessel diameter on the steam velocity only would then lead to the choice of an unduly small vessel. Instead, the larger of the two diameters indicated must be selected. Recommended heights for the vessel are given in the list of dimensions, which is shown on the next slide, with sizes for the condensate outlet. The inlet, and the flash steam outlet, connections, can both be chosen to allow a steam velocity not exceeding 15 m/s. Most applications will be covered by the standardised range of Spirax Sarco Vessels in sizes 150 mm dia up to 380 mm dia. 进 口 冷 凝 水 出 口

使 用 二 次 蒸 汽 使 用 的 条 件 足 够 的 冷 凝 水 量 使 用 低 压 蒸 汽 的 设 备 就 地 使 用 Requirements for Successful Flash Steam Applications If full use is to be made of flash steam, some basic requirements have to be satisfied. 1. The first essential is to have a sufficient supply of condensate, from loads at sufficiently higher pressures, that enough flash steam will be released to make recovery economically effective. The steam traps, and the equipment from which they are draining the condensate, must be able to function satisfactorily while accepting the back pressure applied to them by the recovery system. In particular, care is needed when attempting flash steam recovery from condensate leaving temperature controlled equipment. At less than full loads, the steam space pressure will be lowered by the action of the control valve. If it approaches or even falls below the flash steam pressure, recovery from this condensate becomes impractical. 2. The second essential is a suitable use for the low pressure flash steam. Ideally, the low pressure load (s) should require a supply of steam which at all times either equals or exceeds the available flash steam. The deficit can then be made up through a pressure reducing valve set. If the supply of flash steam exceeds the demand for it, then the surplus may have to be vented to waste through a relief valve, or preferably a Back Pressure (surplussing) control. Thus it is possible to utilise on a space heating installation the flash steam from process condensate -- but then savings will only be achieved during the heating season. When heating is not required, the recovery system becomes ineffective. Wherever possible, the better arrangement is to use flash steam from process condensate to supply process loads -- and that from heating condensate to supply heating loads. Supply and demand are then more likely to remain "in-step'' . 3. It is preferable to select an application for the flash steam, other things being equal, which is reasonably close to the high pressure condensate source. Piping for low pressure steam inevitably is of relatively large diameter. This makes it somewhat costly to install. Further, the heat loss from large diameter pipes reduces the benefits obtained from flash steam recovery and in the worst cases could out-weigh them.

加 热 应 用 中 回 收 二 次 蒸 汽 减 压 站 高 压 蒸 汽 低 压 加 热 器 加 热 器 高 压 疏 水 阀 TYPICAL APPLICATIONS Flash Steam Supply and Demand In Step As indicated, this is the optimal case, providing maximum recovery of the available flash steam. The air heater battery discussed above is a system within this group. Similar arrangements are practicable with many other applications. Of these, perhaps space heating installations using either radiant panels or unit heaters come most readily to mind. The slide shows such a system where a number of heaters are supplied with high pressure steam. The condensate from say 90% of the heaters is collected and taken to a flash recovery vessel. This supplies low pressure steam to the remaining 10% of heaters. With 10% of the units supplied with steam at a lower pressure than formerly, the total heat output of the system is reduced a little. However it is rare to find an installation which does not have a sufficient margin of output above the maximum load to accept this small reduction. In any case where the output of the heaters was found to be inadequate, it would be advantageous to install additional heater capacity so as to gain the benefit of using flash steam which otherwise would be lost. Sometimes an apparent problem arises, when to just make use of the available flash steam might require more than say one heater but less than two. Usually it is then better to connect two heaters to the flash steam supply, rather than vent off to waste the excess flash steam not used by a single heater. Two heaters together will often then pull down the flash pressure to a low level, even below atmospheric. To cope with this, the supply of flash steam can be supplemented through a pressure reducing valve. 空 气 流 高 压 疏 水 阀 低 压 疏 水 阀 疏 水 阀 二 次 蒸 汽 回 收 罐 低 压 冷 凝 水

加 热 过 程 中 回 收 冷 凝 水 高 压 蒸 汽 至 高 压 蒸 汽 使 用 设 备 过 程 负 载 减 压 阀 二 次 蒸 汽 罐 Flash Steam Supply and Demand Not In Step The arrangement shown in the slide is an example of flash steam recovery where the supply and demand are not always in step. Condensate from process plant releases flash steam, but the only use which can be found for it is to augment the supply of steam to the space heating installation. Clearly this can be quite satisfactory during the heating season, as long as the heating load exceeds the availability of flash steam. During the summer season the heating equipment will not be in use, and even during spring and autumn the heating load may not be able to use all the available flash steam. The arrangement is much less than ideal, although it is quite possible for the steam savings made during the winter to justify the cost of the flash steam recovery equipment. Sometimes the surplus flash can only be vented to atmosphere, and as indicated a surplussing valve is more suitable for this purpose than a safety valve which usually has a "pop'' or on/off action. The surplussing valve will be set so that it begins to open at a little above the normal pressure in the heating steam system. When the heating load falls and the pressure in the system begins to increase, the pressure reducing valve supplying the make up steam closes down. A further increase of pressure, perhaps 0.15 or 0.2 bar, is then allowed before the surplussing valve begins to open. In some instances it may be preferred to bypass the flash vessel through a manual valve during summer conditions. The condensate and its associated flash steam may then pass direct to the boiler feed tank or to a condensate receiver, but unless a large proportion of make up water is being used the flash steam will still be vented to atmosphere at the tank. 二 次 蒸 汽 罐 二 次 蒸 汽 加 热 负 载 二 次 蒸 汽 冷 凝 水 溢 流 阀

使 用二 次 蒸 汽 一 级 盘 管 二 级 盘 管 Steam Condensate An even simpler example where supply and demand remain in step is the steam heated Hot Water Storage Calorifier. Some of these incorporate a secondary coil, fitted near the bottom where the cold feed water enters. Condensate and flash steam from the trap on the primary coil is passed direct to the secondary coil. Here the flash steam is condensed, while giving up its enthalpy of evaporation to the feed water. The arrangement is shown above.

换 热 器 组 & 二 次 蒸 汽 利 用 被 加 热 流 体 温 度 控 制 阀 换 热 器 蒸 汽 疏 水 阀 An extension of this idea is shown in above. Here a "packaged calorifier unit'' is used with a normal steam-to-water calorifier draining through a float trap to a smaller shell-and-tube exchanger. In this lower unit, the flash steam is condensed in the upper part and the condensate is sub-cooled in the lower part. The unit is fitted in series with the calorifier so that it can preheat the return water from the system. This reduces the demand for live steam. Notice that the steam space of the preheater is at atmospheric pressure and any air is vented through a simple U seal. An Ogden Pump is used to lift the condensate to the return line, and the exhaust steam leaving the pump is itself condensed with the flash steam in the preheater. The pumping of the condensate is thus achieved at virtually no energy cost. 换 热 器 蒸 汽 疏 水 阀 二 次 蒸 汽 冷 凝 器 蒸 汽 回 水 至 冷 凝 水 回 水 管 机 械 泵

利 用 污 染 的 冷 凝 水 热 的 腐 蚀 性 的 冷 凝 水 16 oC 锅 炉 给 水 10 oC 排 下 水 道 Contaminated Condensate Sometimes condensate is discharged from sources where the small possibility arises that it may have been contaminated by corrosive process liquids. Alternatively, it may be condensed exhaust steam from an engine and carry traces of oil. In either case it becomes unsuitable for use as boiler feed. However, although contaminated it still carries the same useful heat as does clean condensate. Some effort must be made to recover as much as possible of this heat content at least, while in some circumstances the residual water itself may be usable within the process. The slide shows what is probably one of the simplest possible heat exchangers, to enable heat to be recovered from condensate which must be discharged to waste. The hot condensate with its contaminants is taken to a tank, and an overflow arranged so that cool water from the bottom of the tank runs to drain. Fresh make up water for the boiler is passed through a coil, and picks up useful amounts of heat in cooling the water flowing through the tank. The arrangement can be very effective, and if the feed water temperature is increased by 6癈 by recovering energy otherwise wasted, then about 1% of the fuel bill can be saved. In many plating works, condensate from the steam heating coils in the acid plating solution vats is suspect because of the rather higher possibility of leaking coils. The condensate is taken to a flash steam recovery vessel, and the flash steam it releases is used to supply a coil which preheats boiler feed water. The low pressure condensate from the coil, together with that from the flash vessel, is then utilised in the hot swill tanks. In some cases it may be effective to simply discharge the condensate (and flash steam) from the plating vats direct to the hot swill tanks. A similar arrangement might be used where boilers are supplied with heavy fuel oil from heated tanks. Condensate from the tank heaters is suspect because of the possibility of oil contamination through coil leaks, and often is drained to waste. Flash steam recovered from this condensate could more usefully preheat cold make up feed water. 锅 炉 给 水 10 oC 排 下 水 道

从 污 染 的 冷 凝 水 中 回 收 能 量 水 槽 二 次 蒸 汽 受 污 染 的 高 压 冷 凝 水 疏 水 阀 闪 蒸 罐 低 压 冷 凝 水 疏 水 阀 组

锅 炉 排 污 回 收 系 统 除 氧 头 冷 凝 水 排 污 阀 蒸 汽 除 氧 器 Boiler 闪 蒸 罐 换 热 器 Trap 给 水 泵 排 污 阀 闪 蒸 罐 换 热 器 Trap 补 充 水 排 下 水 道 除 氧 器 除 氧 头 Boiler Blowdown Recovery Applications Mention of the return of flash steam to the boiler feed tank or deaerator, and the need for a sufficiently high proportion of make up if the flash steam is to condense, leads to consideration of another application in the same area. Continuous blowdown of boiler water to control the level of TDS (total dissolved solids) within the boiler, is becoming more common. It lends itself to the recovery of the heat content of the blow down water and enables savings to be made which can be appreciable, since they continue all the time the boiler is steaming. The system discharges some of the concentrated boiler water so that it is replaced by an equal weight of treated make up water. This counteracts the tendency for the water in the boiler to become more and more concentrated. The water blown down contains the same concentration of solids as the rest of the water circulating within the boiler. Further, it is at boiler pressure and temperature, so it holds the corresponding enthalpy of saturated water. Much of this enthalpy, leaving the boiler in the blowdown water, is often recovered in flash steam. After it passes through the blowdown control valve, the water at low pressure is taken into a flash recovery vessel. There the flash steam released is separated from the liquid water, and becomes available for heating purposes elsewhere. In particular, this steam can often be used in the deaerator or sparged directly into the boiler feed tank, where it helps to heat the make up water, as illustrated in the slide.

喷 水 冷 凝 二 次 蒸 汽 温 控 探 头 自 作 用 温 控 排 放 的 冷 凝 水 冷 凝 水 入 口 冷 凝 水 蓄 水 槽 离 心 泵 排 放 的 冷 凝 水 冷 凝 水 入 口 Spray Condensing Finally, consideration must be given to those cases where flash steam is available at low pressure, but no suitable load which can make use of it as steam is available. Rather than simply discharge the flash steam to waste, the arrangement shown in the slide can often be adopted. A light weight but corrosion resistant chamber is fitted to the receiver tank vent. Cold water is sprayed into the chamber in sufficient quantity to just condense the flash steam. The flow of cooling water is readily controlled by a simple self acting temperature control, responding to the air temperature at the outlet side of the spray nozzle. It will amount to roughly 6 kg of cooling water per kg of flash steam condensed. If the cooling water is of boiler feed quality, then the warmed water is added to the condensate in the receiver and reused. Condensing water which is not of boiler feed quality, must be kept separate from the water in the receiver as shown by the dotted lines.